WO2018181770A1

WO2018181770A1 - Adhesive sheet

Info

Publication number: WO2018181770A1
Application number: PCT/JP2018/013357
Authority: WO
Inventors: 高志阿久津; 揮一郎加藤
Original assignee: リンテック株式会社
Priority date: 2017-03-31
Filing date: 2018-03-29
Publication date: 2018-10-04
Also published as: JPWO2018181770A1; TW201842103A; JP6764526B2; KR20190129053A; TWI774745B; CN110494524A; CN110494524B; KR102511639B1

Abstract

Provided is an adhesive sheet comprising: a non-adhesive thermally expandable substrate containing a resin and thermally expandable particles that have an expansion start temperature (t) of 120-250°C; and an adhesive layer containing an adhesive resin. The thermally expandable substrate satisfies the requirements (1) and (2) indicated below. Requirement (1): the storage elastic modulus E'(23) of the thermally expandable substrate at 23°C is 1.0 × 106 Pa or more. Requirement (2): the storage elastic modulus E'(t) of the thermally expandable substrate at the expansion start temperature (t) of the thermally expandable particles is 1.0 × 107 Pa or less.

Description

Adhesive sheet

The present invention relates to an adhesive sheet.

The pressure-sensitive adhesive sheet may be used not only for semi-permanent fixing of members but also for temporary fixing for temporarily fixing building materials, interior materials, electronic parts and the like.
Such a pressure-sensitive adhesive sheet for temporarily fixing is required to satisfy both adhesiveness at the time of use and peelability after use.

For example, Patent Document 1 discloses a heat-peelable pressure-sensitive adhesive sheet for temporarily fixing when cutting an electronic component, in which a heat-expandable pressure-sensitive adhesive layer containing heat-expandable microspheres is provided on at least one surface of a base material. Yes.
This heat-peelable pressure-sensitive adhesive sheet adjusts the maximum particle size of the heat-expandable microspheres with respect to the thickness of the heat-expandable pressure-sensitive adhesive layer, and calculates the center line average roughness of the surface of the heat-expandable pressure-sensitive adhesive layer before heating. It is adjusted to 0.4 μm or less.
In Patent Document 1, the heat-peelable pressure-sensitive adhesive sheet can secure an area of contact with an adherend when cutting an electronic component and can exhibit adhesiveness that can prevent adhesion failure such as chip jumping. Later, there is a description that the heat-expandable microspheres can be easily peeled off by expanding the thermally expandable microspheres by heating to reduce the contact area with the adherend.

Japanese Patent No. 3594853

In recent years, electronic devices have been reduced in size, thickness, and density, and semiconductor devices mounted on electronic devices are also required to be reduced in size, thickness, and density. FOWLP (Fan out Wafer Level Package) is drawing attention as a semiconductor package technology that can meet such demands.
As shown in FIG. 3, the FOWLP 50 is provided with a rewiring layer 53 on the surface of the semiconductor chip 51 sealed with the sealing resin layer 52, and the solder balls 54 and the semiconductor chip 51 are interposed via the rewiring layer 53. Is a semiconductor package electrically connected to each other.
As shown in FIG. 3, the FOWLP 50 can be applied to applications where the number of terminals is larger than the area of the semiconductor chip 51 because the terminals that are the solder balls 54 can be expanded to the outside of the semiconductor chip 51 (Fan out). be able to.

By the way, in the manufacturing process of FOWLP, a semiconductor chip is placed on an adhesive sheet, and a sealing resin in a fluid state heated to around 100 ° C. is used as (1) an adhesive sheet around the semiconductor chip and the semiconductor chip. Or the like. (2) A sealing resin film is laminated on a semiconductor chip and heated and laminated. The sealing step (1) or (2) is performed. Then, after the sealing step, FOWLP is manufactured through a step of removing the adhesive sheet and forming a redistribution layer and solder balls on the exposed surface of the semiconductor chip.
In the pressure-sensitive adhesive sheet used in the above-described sealing step, the semiconductor chip is not misaligned between the time when the semiconductor chip is placed and the time when the semiconductor chip is sealed with the sealing resin. Adhesiveness to such an extent that the sealing resin does not enter at the adhesive interface is required. On the other hand, after sealing, the peelability which can remove an adhesive sheet easily is calculated | required.

In the sealing step of the FOWLP manufacturing method, for example, it is conceivable to use a heat-peelable pressure-sensitive adhesive sheet provided with a heat-expandable pressure-sensitive adhesive layer containing heat-expandable microspheres.
However, according to the study by the present inventors, it has been found that when the heat-peelable pressure-sensitive adhesive sheet is used in the sealing step, the semiconductor chip placed thereon sinks to the pressure-sensitive adhesive sheet side.
When the sealing resin is cured while the semiconductor chip is sinking to the adhesive sheet side, the surface on the semiconductor chip side including the sealing resin after removing the adhesive sheet is the surface of the semiconductor chip and the surface of the sealing resin. The level difference is inferior and the flatness is poor. In addition, the semiconductor chips may be misaligned, resulting in problems such as the distance between the chips being not constant.
Furthermore, when removing the pressure-sensitive adhesive sheet described in Patent Document 1, even if the thermally expandable pressure-sensitive adhesive layer is expanded by heating, the semiconductor chip sinks to the pressure-sensitive adhesive sheet side. It is also possible that peeling is difficult without this external force.

Note that such a problem is not limited to the sealing process of the FOWLP manufacturing method, and may occur in the manufacturing process of a PSP (panel scale package), for example, and heat treatment while temporarily fixing an object with an adhesive sheet This is a concern that may arise in the process of applying.

The present invention has been made in view of the above-described problems, and when temporarily fixing an object, it is easy to use a slight force at the time of peeling while suppressing sinking of the object during heating. It aims at providing the adhesive sheet which can be peeled.

The inventors of the present invention provide a pressure-sensitive adhesive sheet containing a resin and a heat-expandable particle and having a non-adhesive heat-expandable base material and a pressure-sensitive adhesive layer containing a pressure-sensitive resin. It has been found that the above problem can be solved by adjusting the storage elastic modulus E ′ at a predetermined temperature to a specific range.

That is, the present invention relates to the following [1] to [8].
[1] A pressure-sensitive adhesive sheet comprising a resin and heat-expandable particles having an expansion start temperature (t) of 120 to 250 ° C., having a non-adhesive heat-expandable base material, and a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive resin Because
The pressure-sensitive adhesive sheet, wherein the thermally expandable substrate satisfies the following requirements (1) to (2).
-Requirement (1): The storage elastic modulus E '(23) of the said thermally expansible base material in 23 degreeC is 1.0 * 10 < ⁶ > Pa or more.
Requirement (2): The storage elastic modulus E ′ (t) of the thermally expandable substrate at the expansion start temperature (t) of the thermally expandable particles is 1.0 × 10 ⁷ Pa or less.
[2] The pressure-sensitive adhesive sheet according to [1], wherein the thermally expandable substrate satisfies the following requirement (3).
-Requirement (3): The storage elastic modulus E '(100) of the said thermally expansible base material in 100 degreeC is 2.0 * 10 < ⁵ > Pa or more.
[3] The above [1], wherein the ratio of the thickness of the thermally expandable substrate to the thickness of the adhesive layer (thermally expandable substrate / adhesive layer) at 23 ° C. is 0.2 or more. The pressure-sensitive adhesive sheet according to [2].
[4] In any one of the above [1] to [3], the thickness of the thermally expandable substrate at 23 ° C. is 10 to 1000 μm, and the thickness of the pressure-sensitive adhesive layer is 1 to 60 μm. The adhesive sheet as described.
[5] The pressure-sensitive adhesive sheet according to any one of [1] to [4], wherein the probe tack value on the surface of the thermally expandable substrate is less than 50 mN / 5 mmφ.
[6] The storage shear modulus G ′ (23) of the pressure-sensitive adhesive layer at 23 ° C. is 1.0 × 10 ⁴ to 1.0 × 10 ⁸ Pa. The pressure-sensitive adhesive sheet according to claim 1.
[7] The pressure-sensitive adhesive sheet according to any one of the above [1] to [6], which has two pressure-sensitive adhesive layers on both surfaces of the thermally expandable substrate.
[8] The pressure-sensitive adhesive sheet according to any one of [1] to [7], wherein the thermally expandable particles have an average particle diameter before expansion at 23 ° C. of 3 to 100 μm.
[9] The pressure-sensitive adhesive sheet according to any one of the above [1] to [8], which is used in a sealing step involving heating using a sealing resin.
[10] A thermally expandable substrate comprising a resin and thermally expandable particles having an expansion start temperature (t) of 120 to 250 ° C., non-adhesive, and satisfying the following requirements (1) to (2):
-Requirement (1): The storage elastic modulus E '(23) of the said thermally expansible base material in 23 degreeC is 1.0 * 10 < ⁶ > Pa or more.
Requirement (2): The storage elastic modulus E ′ (t) of the thermally expandable substrate at the expansion start temperature (t) of the thermally expandable particles is 1.0 × 10 ⁷ Pa or less.
[11] After the pressure-sensitive adhesive sheet according to any one of [1] to [9] is attached to an adherend, the pressure-sensitive adhesive sheet is removed from the adherend by a heat treatment at an expansion start temperature (t) or higher. How to use the adhesive sheet to peel off.
[12] The method for using the pressure-sensitive adhesive sheet according to the above [11], which is used in a sealing step involving heating using a sealing resin.
[13] The ratio of the average particle diameter of the thermally expandable particles at 23 ° C. to the thickness of the thermally expandable substrate at 23 ° C. (average particle diameter / thermally expandable substrate) is more than 0.3 and 1.0 The pressure-sensitive adhesive sheet according to any one of [1] to [9], which is less than

The pressure-sensitive adhesive sheet using the heat-expandable substrate of the present invention can be easily peeled off with a slight force at the time of peeling while suppressing the sinking of the object during heating when temporarily fixing the object. Is possible.

It is a cross-sectional schematic diagram of an adhesive sheet which shows an example of a structure of the adhesive sheet of this invention. It is a cross-sectional schematic diagram of a double-sided pressure-sensitive adhesive sheet showing an example of the configuration of the pressure-sensitive adhesive sheet of the present invention. It is a cross-sectional schematic diagram which shows an example of FOWLP.

In the present invention, the “active ingredient” refers to a component excluding a diluent solvent among components contained in a target composition.
The mass average molecular weight (Mw) is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method, specifically a value measured based on the method described in the examples.

In the present invention, for example, “(meth) acrylic acid” indicates both “acrylic acid” and “methacrylic acid”, and the same applies to other similar terms.
Moreover, about the preferable numerical range (for example, range of content etc.), the lower limit value and upper limit value which were described in steps can be combined independently, respectively. For example, from the description “preferably 10 to 90, more preferably 30 to 60”, “preferable lower limit (10)” and “more preferable upper limit (60)” are combined to obtain “10 to 60”. You can also.

[Configuration of the pressure-sensitive adhesive sheet of the present invention]
The pressure-sensitive adhesive sheet of the present invention is not particularly limited as long as it includes a resin and heat-expandable particles and has a non-adhesive heat-expandable base material and a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive resin.
1 and 2 are schematic cross-sectional views of a pressure-sensitive adhesive sheet showing the configuration of the pressure-sensitive adhesive sheet of the present invention.

As the pressure-sensitive adhesive sheet of one embodiment of the present invention, a pressure-sensitive adhesive sheet 1a having a pressure-sensitive adhesive layer 12 on a thermally expandable substrate 11 as shown in FIG.
In addition, the adhesive sheet of 1 aspect of this invention is good also as a structure which has the peeling material 13 on the adhesive surface of the adhesive layer 12 like the adhesive sheet 1b shown in FIG.1 (b).

As the pressure-sensitive adhesive sheet of another aspect of the present invention, as shown in FIG. It is good also as the double-sided adhesive sheet 2a.
Moreover, like the double-sided pressure-sensitive adhesive sheet 2b shown in FIG. A configuration having 132 is also possible.

In addition, in the double-sided pressure-sensitive adhesive sheet 2b shown in FIG. 2B, the peeling force when peeling the release material 131 from the first pressure-sensitive adhesive layer 121, and the peeling force when peeling the peeling material 132 from the second pressure-sensitive adhesive layer 122, In the case of the same level, if the two release materials are pulled outward to be peeled off, a phenomenon may occur in which the pressure-sensitive adhesive layer is divided and peeled off along with the two release materials.
From the viewpoint of suppressing such a phenomenon, it is preferable to use two types of release materials designed so that the two

release materials

131 and 132 have different release forces from the adhesive layer attached to each other.

As another pressure-sensitive adhesive sheet, in the double-sided pressure-sensitive adhesive sheet 2a shown in FIG. 2 (a), a release material in which release treatment is performed on both surfaces of one pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer 121 and the second pressure-sensitive adhesive layer 122. May be a double-sided pressure-sensitive adhesive sheet having a configuration in which a laminate is wound in a roll shape.

Here, the pressure-sensitive adhesive sheet of one embodiment of the present invention may have a configuration having another layer between the thermally expandable base material and the pressure-sensitive adhesive layer.
However, from the viewpoint of making the pressure-sensitive adhesive sheet easily peelable with a slight force, the thermally expandable substrate 11 and the pressure-sensitive adhesive sheets 1a and 1b shown in FIG. 1 and the double-sided pressure-

sensitive adhesive sheets

2a and 2b shown in FIG. It is preferable to have a structure in which the pressure-sensitive adhesive layer 12 is directly laminated.

(Thermally expandable substrate)
The heat-expandable base material of the pressure-sensitive adhesive sheet of the present invention comprises a resin and heat-expandable particles having an expansion start temperature (t) of 120 to 250 ° C., and is a non-adhesive base material. ) To (2) are satisfied.
-Requirement (1): The storage elastic modulus E '(23) of the said thermally expansible base material in 23 degreeC is 1.0 * 10 < ⁶ > Pa or more.
Requirement (2): The storage elastic modulus E ′ (t) of the thermally expandable substrate at the expansion start temperature (t) of the thermally expandable particles is 1.0 × 10 ⁷ Pa or less.
In the present specification, the storage elastic modulus E ′ of the thermally expandable substrate at a predetermined temperature means a value measured by the method described in the examples.

For example, in the sealing process in the manufacturing process of FOWLP, a semiconductor chip is pasted on an adhesive sheet at a room temperature of about 23 ° C., and heated to about 100 ° C. from above to form a sealing resin in a fluid state. In general, the semiconductor chip is sealed by a method of filling the top or laminating a sealing resin sheet on the semiconductor chip and laminating by heating.
That is, the requirement (1) is that the storage elastic modulus E ′ (23) of the thermally expandable substrate under the temperature environment (23 ° C.) when the object such as the semiconductor chip is stuck on the adhesive sheet in this way. ).
A semiconductor chip is usually placed so that its circuit surface is covered with an adhesive surface. For mounting the semiconductor chip, a known device such as a flip chip bonder or a die bonder can be used.
Among the above procedures, when a semiconductor chip is placed on the adhesive sheet using a flip chip bonder or a die bonder, a force is applied to push the semiconductor chip in the thickness direction of the adhesive sheet. May sink excessively in the direction. In addition, among the above procedures, when a semiconductor chip is placed on the adhesive sheet using a flip chip bonder or a die bonder, a force to move the semiconductor chip in the plane direction of the adhesive sheet is applied, so the semiconductor chip is an adhesive. There is a risk of displacement in the plane direction of the layer.

For such a problem, the pressure-sensitive adhesive sheet of the present invention contains a resin and thermally expandable particles, and has a storage elastic modulus E ′ (23) at 23 ° C. of 1 as defined in the requirement (1). The problem is solved by using a thermally expandable base material adjusted to 0.0 × 10 ⁶ Pa or more.

By using a thermally expansible base material that satisfies the above requirement (1), it is possible to prevent misalignment when attaching an object such as a semiconductor chip on an adhesive sheet. Can do. Moreover, when a target object is stuck, excessive sinking into the pressure-sensitive adhesive layer can also be prevented.

From the above viewpoint, the storage elastic modulus E ′ (23) of the thermally expandable base material defined by the requirement (1) is preferably 5.0 × 10 ⁶ to 5.0 × 10 ¹² Pa, more preferably 1. 0 × 10 ⁷ to 1.0 × 10 ¹² Pa, more preferably 5.0 × 10 ⁷ to 1.0 × 10 ¹¹ Pa, still more preferably 1.0 × 10 ⁸ to 1.0 × 10 ¹⁰ Pa is there.

On the other hand, the said requirement (2) prescribes | regulates the storage elastic modulus E 'of a thermally expansible base material at the time of peeling of an adhesive sheet.
When the pressure-sensitive adhesive sheet of the present invention is peeled off from the adherend, the heat-expandable particles in the heat-expandable substrate expand by heating to a temperature equal to or higher than the expansion start temperature (t) of the heat-expandable particles. As a result, irregularities are formed on the surface of the thermally expandable substrate, and the pressure-sensitive adhesive layer laminated on the irregularities is also pushed up, and irregularities are also formed on the adhesive surface.
Then, by forming irregularities on the adhesive surface of the adhesive layer, the contact area between the adherend (semiconductor chip and cured sealing resin) and the adhesive surface decreases, and the adherend and the adhesive surface By forming a space between them, the pressure-sensitive adhesive sheet can be easily peeled off from the adherend with a slight force.

By the way, before the expansion of the thermally expandable particles, the temperature rises and the storage elastic modulus E ′ of the thermally expandable substrate decreases. However, as in the present invention, the heat-expandable base material containing the heat-expandable particles in the “base material” contains the heat-expandable particles in the “adhesive layer” as in Patent Document 1. Compared with the thermally expandable pressure-sensitive adhesive layer, the degree of decrease in the storage elastic modulus E ′ of the thermally expandable substrate due to the temperature rise is small. Therefore, also in the sealing step, it is possible to prevent the positional deviation of the object such as the semiconductor chip and the excessive sinking into the pressure-sensitive adhesive layer.
On the other hand, in order to improve the peelability of the pressure-sensitive adhesive sheet, it is necessary to make it easy to form irregularities on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer when heated to a temperature equal to or higher than the expansion start temperature (t). For this purpose, the heat-expandable particles contained in the heat-expandable substrate need to be adjusted so as to easily expand.

In the above requirement (2), the storage elastic modulus E ′ (t) of the thermally expandable substrate at the expansion start temperature (t) of the thermally expandable particles is defined. It can also be said that the index indicates the rigidity of the thermally expandable substrate immediately before expansion.
That is, according to the study by the present inventors, the storage elastic modulus E ′ (t) of the thermally expandable substrate at the expansion start temperature (t) of the thermally expandable particles is more than 1.0 × 10 ⁷ Pa. Even if an attempt is made to expand the thermally expandable particles by heating to a temperature equal to or higher than the expansion start temperature (t), the expansion is suppressed, and the thermally expandable particles are not sufficiently large. It turned out that the uneven | corrugated formation of the adhesion surface of the adhesive layer laminated | stacked becomes inadequate.

From the above viewpoint, the storage elastic modulus E ′ (t) defined in the requirement (2) of the thermally expandable substrate used in one embodiment of the present invention is preferably 9.0 × 10 ⁶ Pa or less, more preferably 8. It is 0 × 10 ⁶ Pa or less, more preferably 6.0 × 10 ⁶ Pa or less, and still more preferably 4.0 × 10 ⁶ Pa or less.
In addition, from the viewpoint of suppressing the flow of the expanded thermally expandable particles, improving the shape maintaining property of the unevenness formed on the adhesive surface of the adhesive layer, and further improving the peelability, the requirements for the thermally expandable substrate The storage elastic modulus E ′ (t) specified in (2) is preferably 1.0 × 10 ³ Pa or more, more preferably 1.0 × 10 ⁴ Pa or more, and further preferably 1.0 × 10 ⁵ Pa or more. It is.

Moreover, it is preferable that the thermally expansible base material which the adhesive sheet of 1 aspect of this invention has further satisfies the following requirements (3).
-Requirement (3): The storage elastic modulus E '(100) of the said thermally expansible base material in 100 degreeC is 2.0 * 10 < ⁵ > Pa or more.

For example, in the sealing process in the manufacturing process of FOWLP, a sealing resin heated to around 100 ° C. and filled with fluidity is filled on the semiconductor chip, or a sealing resin sheet is laminated on the semiconductor chip. In general, the semiconductor chip is sealed by heating and laminating.
That is, the above requirement (3) prescribes the storage elastic modulus E ′ of the thermally expandable substrate under the temperature environment in the sealing process, assuming that the temperature environment in the sealing process of the manufacturing process of FOWLP is 100 ° C. Is.

Generally, since the heat-expandable pressure-sensitive adhesive layer as the pressure-sensitive adhesive sheet described in Patent Document 1 contains a pressure-sensitive adhesive resin, the degree of decrease in the storage elastic modulus E ′ becomes very large as the temperature rises. There is a tendency.
Here, when the degree of decrease in the storage elastic modulus E ′ of the heat-expandable pressure-sensitive adhesive layer becomes very large, the heat-expandable particles and the pressure-sensitive resin contained in the heat-expandable pressure-sensitive adhesive layer easily flow, and accordingly, The pressure-sensitive adhesive surface of the thermally expandable pressure-sensitive adhesive layer is easily deformed.
As a result, when the sealing resin is heated on a target such as a semiconductor chip around 100 ° C. and poured with a fluid sealing resin, the weight of the sealing resin is increased. When the pressure-sensitive adhesive sheet becomes flexible along with the heating and heating, the object can easily sink into the pressure-sensitive adhesive sheet side. The sinking of the object is caused by the occurrence of positional deviation of the object, the occurrence of variation in the distance between the objects, and unevenness on the surface on which the object after sealing is placed, and the flatness is It also causes inferiority. This problem also applies to the sealing method using a laminate using a sealing resin film.
Further, in the pressure-sensitive adhesive sheet in which a new pressure-sensitive adhesive layer is provided on the surface of the heat-expandable pressure-sensitive adhesive layer, the flow of the heat-expandable particles and the pressure-sensitive resin in the heat-expandable pressure-sensitive adhesive layer is the same as described above. Therefore, the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer is likely to be deformed, and the above-described problem may occur.

For such a problem, the pressure-sensitive adhesive sheet of one embodiment of the present invention contains a resin and thermally expandable particles and, as defined in the above requirement (3), storage elastic modulus E ′ (100) at 100 ° C. Is solved by using a thermally expansible base material adjusted to 2.0 × 10 ⁵ Pa or more.

By having a thermally expandable substrate that satisfies the requirement (3), the flow of thermally expandable particles can be moderately suppressed even in a temperature environment in a sealing process such as a FOWLP manufacturing process. The pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer provided on is difficult to deform.
As a result, the weight of the sealing resin laminated on the object such as a semiconductor chip or the pressure accompanying the lamination using the sealing resin sheet causes the object to sink to the adhesive sheet side, and a flat surface is formed. It is possible to suppress the adverse effects such as difficulty and the occurrence of displacement of the object.

In one embodiment of the present invention, the thickness of the thermally expandable substrate at 23 ° C. is preferably 10 to 1000 μm, more preferably 20 to 500 μm, still more preferably 25 to 400 μm, and still more preferably 30 to 300 μm.
In addition, in this specification, the thickness of the thermally expansible base material in 23 degreeC means the value measured by the method as described in an Example.

The thermally expansible base material which the adhesive sheet of 1 aspect of this invention has is a non-adhesive base material.
In the present invention, whether or not the non-adhesive substrate is determined if the probe tack value measured in accordance with JIS Z0237: 1991 is less than 50 N / 5 mmφ with respect to the surface of the target substrate. The said base material is judged as a "non-adhesive base material".
Here, the probe tack value on the surface of the thermally expandable substrate used in one embodiment of the present invention is less than 50 mN / 5 mmφ, preferably less than 30 mN / 5 mmφ, more preferably less than 10 mN / 5 mmφ, and even more preferably 5 mN. / 5mmφ or less.
In addition, in this specification, the specific measuring method of the probe tack value on the surface of a thermally expansible base material is based on the method as described in an Example.

Although the heat-expandable base material which the adhesive sheet of 1 aspect of this invention has contains resin and heat-expandable particle | grains, it is a range which does not impair the effect of this invention, and contains the additive for base materials as needed. May be.
Moreover, a thermally expansible base material can be formed from the resin composition (y) containing resin and a thermally expansible particle.
Hereinafter, each component contained in the resin composition (y) which is a forming material of a thermally expansible base material is demonstrated.

<Resin>
The resin contained in the resin composition (y) may be any polymer that can form a thermally expandable substrate that satisfies the above requirements (1) and (2).
In addition, as resin contained in resin composition (y), non-adhesive resin may be sufficient and adhesive resin may be sufficient.
That is, even if the resin contained in the resin composition (y) is an adhesive resin, the adhesive resin undergoes a polymerization reaction with the polymerizable compound in the process of forming the thermally expandable substrate from the resin composition (y). The obtained resin becomes a non-adhesive resin, and the heat-expandable substrate containing the resin may be non-adhesive.

The mass average molecular weight (Mw) of the resin contained in the resin composition (y) is preferably 1,000 to 1,000,000, more preferably 1,000 to 700,000, and still more preferably 1,000 to 500,000.
Further, when the resin is a copolymer having two or more kinds of structural units, the form of the copolymer is not particularly limited, and any of a block copolymer, a random copolymer, and a graft copolymer It may be.

The content of the resin is preferably 50 to 99% by mass, more preferably 60 to 95% by mass, and still more preferably 65 to 90% with respect to the total amount (100% by mass) of the active ingredients of the resin composition (y). It is 70% by mass, more preferably 70 to 85% by mass.

In addition, from the viewpoint of forming a thermally expandable base material that satisfies the above requirements (1) and (2), the resin contained in the resin composition (y) is selected from acrylic urethane resins and olefin resins. Preferably it contains more than one species.
Moreover, as said acrylic urethane type resin, the following resin (U1) is preferable.
An acrylic urethane resin (U1) obtained by polymerizing a urethane prepolymer (UP) and a vinyl compound containing a (meth) acrylic acid ester.

(Acrylic urethane resin (U1))
Examples of the urethane prepolymer (UP) serving as the main chain of the acrylic urethane resin (U1) include a reaction product of a polyol and a polyvalent isocyanate.
The urethane prepolymer (UP) is preferably obtained by further performing a chain extension reaction using a chain extender.

Examples of the polyol used as a raw material for the urethane prepolymer (UP) include alkylene type polyols, ether type polyols, ester type polyols, ester amide type polyols, ester / ether type polyols, and carbonate type polyols.
These polyols may be used independently and may use 2 or more types together.
The polyol used in one embodiment of the present invention is preferably a diol, preferably an ester-type diol, an alkylene-type diol, and a carbonate-type diol, more preferably an ester-type diol and a carbonate-type diol, and even more preferably a carbonate-type diol. .

Examples of ester type diols include alkane diols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol; ethylene glycol, propylene glycol, One or more selected from diols such as alkylene glycols such as diethylene glycol and dipropylene glycol; phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4-diphenyldicarboxylic acid, diphenylmethane-4 , 4'-dicarboxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, het acid, maleic acid, fumaric acid, itaconic acid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, hexa Hydrophthalic acid, Examples thereof include condensation polymers of one or more selected from dicarboxylic acids such as hexahydroisophthalic acid, hexahydroterephthalic acid, and methylhexahydrophthalic acid, and anhydrides thereof.
Specifically, polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyhexamethylene isophthalate diol, polyneopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butylene adipate diol, polybutylene hexamethylene adipate diol, Polydiethylene adipate diol, poly (polytetramethylene ether) adipate diol, poly (3-methylpentylene adipate) diol, polyethylene azelate diol, polyethylene sebacate diol, polybutylene azelate diol, polybutylene sebacate diol and polyneo Examples thereof include pentyl terephthalate diol.

Examples of the alkylene type diol include alkane diols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol; ethylene glycol, propylene glycol, And alkylene glycols such as diethylene glycol and dipropylene glycol; polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol; polyoxyalkylene glycols such as polytetramethylene glycol; and the like.

Examples of the carbonate type diol include 1,4-tetramethylene carbonate diol, 1,5-pentamethylene carbonate diol, 1,6-hexamethylene carbonate diol, 1,2-propylene carbonate diol, and 1,3-propylene carbonate diol. 2,2-dimethylpropylene carbonate diol, 1,7-heptamethylene carbonate diol, 1,8-octamethylene carbonate diol, 1,4-cyclohexane carbonate diol, and the like.

Examples of the polyvalent isocyanate used as a raw material for the urethane prepolymer (UP) include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.
These polyvalent isocyanates may be used alone or in combination of two or more.
These polyisocyanates may be a trimethylolpropane adduct type modified product, a burette type modified product reacted with water, or an isocyanurate type modified product containing an isocyanurate ring.

Among these, the polyisocyanate used in one embodiment of the present invention is preferably diisocyanate, and 4,4′-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,6 More preferred is at least one selected from tolylene diisocyanate (2,6-TDI), hexamethylene diisocyanate (HMDI), and alicyclic diisocyanate.

Examples of the alicyclic diisocyanate include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane. Examples include diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, and isophorone diisocyanate (IPDI) is preferred.

In one embodiment of the present invention, the urethane prepolymer (UP) serving as the main chain of the acrylic urethane resin (U1) is a reaction product of a diol and a diisocyanate, and is a straight chain having ethylenically unsaturated groups at both ends. A urethane prepolymer is preferred.
As a method for introducing an ethylenically unsaturated group into both ends of the linear urethane prepolymer, an NCO group at the end of the linear urethane prepolymer obtained by reacting a diol and a diisocyanate compound, and a hydroxyalkyl (meth) acrylate And a method of reacting with.

Examples of the hydroxyalkyl (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxy Examples thereof include butyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate.

As a vinyl compound used as the side chain of acrylic urethane resin (U1), at least (meth) acrylic acid ester is included.
The (meth) acrylic acid ester is preferably one or more selected from alkyl (meth) acrylates and hydroxyalkyl (meth) acrylates, and more preferably used in combination with alkyl (meth) acrylates and hydroxyalkyl (meth) acrylates.

When alkyl (meth) acrylate and hydroxyalkyl (meth) acrylate are used in combination, the proportion of hydroxyalkyl (meth) acrylate to 100 parts by mass of alkyl (meth) acrylate is preferably 0.1 to 100 parts by mass, The amount is preferably 0.5 to 30 parts by mass, more preferably 1.0 to 20 parts by mass, and still more preferably 1.5 to 10 parts by mass.

The carbon number of the alkyl group of the alkyl (meth) acrylate is preferably 1 to 24, more preferably 1 to 12, still more preferably 1 to 8, and still more preferably 1 to 3.

Moreover, as hydroxyalkyl (meth) acrylate, the same thing as the hydroxyalkyl (meth) acrylate used in order to introduce | transduce an ethylenically unsaturated group into the both ends of the above-mentioned linear urethane prepolymer is mentioned.

Examples of vinyl compounds other than (meth) acrylic acid esters include aromatic hydrocarbon vinyl compounds such as styrene, α-methylstyrene, and vinyl toluene; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; vinyl acetate and vinyl propionate. Polar group-containing monomers such as (meth) acrylonitrile, N-vinylpyrrolidone, (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, and meta (acrylamide).
These may be used alone or in combination of two or more.

The content of the (meth) acrylic acid ester in the vinyl compound is preferably 40 to 100% by mass, more preferably 65 to 100% by mass, and still more preferably based on the total amount (100% by mass) of the vinyl compound. It is 80 to 100% by mass, more preferably 90 to 100% by mass.

The total content of alkyl (meth) acrylate and hydroxyalkyl (meth) acrylate in the vinyl compound is preferably 40 to 100% by mass, more preferably 65 to 100% by mass with respect to the total amount (100% by mass) of the vinyl compound. The amount is 100% by mass, more preferably 80 to 100% by mass, and still more preferably 90 to 100% by mass.
The acrylic urethane-based resin (U1) used in one embodiment of the present invention is obtained by mixing a urethane prepolymer (UP) and a vinyl compound containing a (meth) acrylic acid ester and polymerizing both.
The polymerization is preferably performed by adding a radical initiator.

In the acrylic urethane resin (U1) used in one embodiment of the present invention, the content ratio of the structural unit (u11) derived from the urethane prepolymer and the structural unit (u12) derived from the vinyl compound [(u11) / ( u12)] is preferably 10/90 to 80/20, more preferably 20/80 to 70/30, still more preferably 30/70 to 60/40, still more preferably 35/65 to mass by mass ratio. 55/45.

(Olefin resin)
The olefin resin suitable as the resin contained in the resin composition (y) is a polymer having at least a structural unit derived from an olefin monomer.
The olefin monomer is preferably an α-olefin having 2 to 8 carbon atoms, and specifically includes ethylene, propylene, butylene, isobutylene, 1-hexene and the like.
Among these, ethylene and propylene are preferable.

Specific olefinic resins, for example, ultra low density polyethylene (VLDPE, density: 880 kg / ^{m 3} or more 910 kg / ^m less than ^3), low density polyethylene (LDPE, density: 910 kg / ^{m 3} or more 915 kg / ^m less than ³ ), Medium density polyethylene (MDPE, density: 915 kg / m ³ or more and less than 942 kg / m ³ ), high density polyethylene (HDPE, density: 942 kg / m ³ or more), linear low density polyethylene, etc .; polypropylene resin (PP); polybutene resin (PB); ethylene-propylene copolymer; olefin elastomer (TPO); poly (4-methyl-1-pentene) (PMP); ethylene-vinyl acetate copolymer (EVA); Vinyl alcohol copolymer (EVOH); ethylene-propylene Olefinic terpolymers such as-(5-ethylidene-2-norbornene); and the like.

In one embodiment of the present invention, the olefin resin may be a modified olefin resin further modified by one or more selected from acid modification, hydroxyl group modification, and acrylic modification.

For example, as an acid-modified olefin resin obtained by subjecting an olefin resin to acid modification, a modified polymer obtained by graft polymerization of the above-mentioned unmodified olefin resin with an unsaturated carboxylic acid or its anhydride. Is mentioned.
Examples of the unsaturated carboxylic acid or anhydride thereof include maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, aconitic acid, (meth) acrylic acid, maleic anhydride, itaconic anhydride. , Glutaconic anhydride, citraconic anhydride, aconitic anhydride, norbornene dicarboxylic anhydride, tetrahydrophthalic anhydride, and the like.
In addition, unsaturated carboxylic acid or its anhydride may be used independently and may use 2 or more types together.

As an acrylic modified olefin resin obtained by subjecting an olefin resin to acrylic modification, a modification obtained by graft polymerization of an alkyl (meth) acrylate as a side chain to the above-mentioned unmodified olefin resin as a main chain. A polymer is mentioned.
The number of carbon atoms in the alkyl group of the alkyl (meth) acrylate is preferably 1-20, more preferably 1-16, and still more preferably 1-12.
As said alkyl (meth) acrylate, the same thing as the compound which can be selected as a below-mentioned monomer (a1 ') is mentioned, for example.

Examples of the hydroxyl group-modified olefin resin obtained by subjecting an olefin resin to hydroxyl group modification include a modified polymer obtained by graft polymerization of a hydroxyl group-containing compound to the above-mentioned unmodified olefin resin, which is the main chain.
Examples of the hydroxyl group-containing compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxybutyl. Examples thereof include hydroxyalkyl (meth) acrylates such as (meth) acrylate and 4-hydroxybutyl (meth) acrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol.

(Resin other than acrylic urethane resin and olefin resin)
In one embodiment of the present invention, the resin composition (y) may contain a resin other than the acrylic urethane-based resin and the olefin-based resin as long as the effects of the present invention are not impaired.
Examples of such resins include vinyl resins such as polyvinyl chloride, polyvinylidene chloride, and polyvinyl alcohol; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer Polycarbonate; Polyurethane not applicable to acrylic urethane resin; Polysulfone; Polyetheretherketone; Polyethersulfone; Polyphenylene sulfide; Polyimide resin such as polyetherimide and polyimide; Polyamide resin; Acrylic resin; Fluorine resin etc. are mentioned.

However, from the viewpoint of forming a thermally expandable substrate that satisfies the above requirements (1) and (2), the content of the resin other than the acrylic urethane-based resin and the olefin-based resin in the resin composition (y) is smaller. Is preferred.
The content ratio of the resin other than the acrylic urethane-based resin and the olefin-based resin is preferably less than 30 parts by mass, more preferably 20 parts by mass with respect to 100 parts by mass of the total amount of the resin contained in the resin composition (y). Less than, more preferably less than 10 parts by mass, still more preferably less than 5 parts by mass, and even more preferably less than 1 part by mass.

<Thermal expandable particles>
The heat-expandable particles used in the present invention may be particles whose expansion start temperature (t) is adjusted to 120 to 250 ° C., and are appropriately selected according to the application.
In the present specification, the expansion start temperature (t) of the thermally expandable particles means a value measured based on the following method.
[Measurement method of expansion start temperature (t) of thermally expandable particles]
To an aluminum cup having a diameter of 6.0 mm (inner diameter 5.65 mm) and a depth of 4.8 mm, 0.5 mg of thermally expandable particles to be measured is added, and an aluminum lid (diameter 5.6 mm, thickness 0. 1 mm) is prepared.
Using a dynamic viscoelasticity measuring device, the height of the sample is measured from the upper part of the aluminum lid while a force of 0.01 N is applied to the sample by a pressurizer. Then, in a state where a force of 0.01 N is applied by the pressurizer, heating is performed from 20 ° C. to 300 ° C. at a rate of temperature increase of 10 ° C./min, and the amount of displacement of the pressurizer in the vertical direction is measured. Let the displacement start temperature be the expansion start temperature (t).

The thermally expandable particles are microencapsulated foaming agents composed of an outer shell composed of a thermoplastic resin and an encapsulated component encapsulated in the outer shell and vaporized when heated to a predetermined temperature. Preferably there is.
Examples of the thermoplastic resin constituting the outer shell of the microencapsulated foaming agent include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, and polysulfone.

Examples of the inclusion component contained in the outer shell include propane, butane, pentane, hexane, heptane, octane, nonane, decane, isobutane, isopentane, isohexane, isoheptane, isooctane, isononane, isodecane, cyclopropane, cyclobutane, cyclopentane. , Cyclohexane, cycloheptane, cyclooctane, neopentane, dodecane, isododecane, cyclotridecane, hexylcyclohexane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nanodecane, isotridecane, 4-methyldodecane, isotetradecane, isopentadecane, iso Hexadecane, 2,2,4,4,6,8,8-heptamethylnonane, isoheptadecane, isooctadecane, isonanodecane, , 6,10,14-tetramethylpentadecane, cyclotridecane, heptylcyclohexane, n-octylcyclohexane, cyclopentadecane, nonylcyclohexane, decylcyclohexane, pentadecylcyclohexane, hexadecylcyclohexane, heptadecylcyclohexane, octadecylcyclohexane, etc. .
These encapsulated components may be used alone or in combination of two or more.
The expansion start temperature (t) of the thermally expandable particles can be adjusted by appropriately selecting the type of inclusion component.

The average particle size (D ₅₀ ) before expansion of the thermally expandable particles at 23 ° C. used in one embodiment of the present invention is preferably 3 to 100 μm, more preferably 4 to 70 μm, still more preferably 6 to 60 μm, and still more. The thickness is preferably 10 to 50 μm.
The average particle diameter before expansion of the thermally expandable particles is the volume-median particle diameter (D ₅₀ ), and is a laser diffraction particle size distribution measuring device (for example, product name “Mastersizer 3000” manufactured by Malvern). In the particle distribution of the heat-expandable particles before expansion measured by means of a particle diameter, the cumulative volume frequency calculated from the smaller particle diameter of the heat-expandable particles before expansion means a particle diameter corresponding to 50%.
The ratio of the average particle diameter of the heat-expandable particles at 23 ° C. to the thickness of the heat-expandable substrate at 23 ° C. (average particle diameter / heat-expandable substrate) From the viewpoint of suppression and ease of peeling at the time of peeling of the object, preferably 0.1 or more and less than 1.0, more preferably 0.2 or more and less than 1.0, and further preferably more than 0.3. It is less than 0, more preferably 0.35 to 0.8, still more preferably 0.4 to 0.6, and still more preferably 0.4 to 0.5.

The 90% particle diameter (D ₉₀ ) of the thermally expandable particles at 23 ° C. used in one embodiment of the present invention is preferably 10 to 150 μm, more preferably 20 to 100 μm, still more preferably 25 to 90 μm, and still more preferably. Is 30 to 80 μm.
The 90% particle size (D ₉₀ ) of the thermally expandable particles is the heat before expansion measured using a laser diffraction particle size distribution measuring device (for example, product name “Mastersizer 3000” manufactured by Malvern). In the particle distribution of the expandable particles, it means a particle diameter corresponding to 90% of the cumulative volume frequency calculated from the smaller particle diameter of the thermally expandable particles before expansion.

The maximum volume expansion coefficient when heated to a temperature equal to or higher than the expansion start temperature (t) of the thermally expandable particles used in one embodiment of the present invention is preferably 1.5 to 100 times, more preferably 2 to 80 times, Preferably it is 2.5 to 60 times, and more preferably 3 to 40 times.

The content of the heat-expandable particles is preferably 1 to 40% by mass, more preferably 5 to 35% by mass, and still more preferably 10% with respect to the total amount (100% by mass) of the active ingredients of the resin composition (y). To 30% by mass, and more preferably 15 to 25% by mass.

<Substrate additive>
The resin composition (y) used in one embodiment of the present invention may contain a base material additive contained in a base material included in a general pressure-sensitive adhesive sheet as long as the effects of the present invention are not impaired.
Examples of such base material additives include ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, slip agents, antiblocking agents, and colorants.
These base material additives may be used alone or in combination of two or more.
In the case of containing these base material additives, the content of each base material additive is preferably 0.0001 to 20 parts by mass with respect to 100 parts by mass of the resin in the resin composition (y). More preferably, it is 0.001 to 10 parts by mass.

<Solvent-free resin composition (y1)>
The resin composition (y) used in one embodiment of the present invention is ethylenic having a mass average molecular weight (Mw) of 50000 or less from the viewpoint of forming a thermally expandable substrate that satisfies the above requirements (1) and (2). Examples include a solventless resin composition (y1), which is obtained by blending an oligomer having an unsaturated group, an energy beam polymerizable monomer, and the above-described thermally expandable particles, and not blending a solvent.
In the solventless resin composition (y1), no solvent is blended, but the energy beam polymerizable monomer contributes to the improvement of the plasticity of the oligomer.
By irradiating the coating film formed from the solventless resin composition (y1) with energy rays, it is easy to form a thermally expandable substrate that satisfies the above requirements (1) and (2).

In addition, it is as above-mentioned about the kind and shape of a thermally expansible particle mix | blended with a solventless type resin composition (y1), and a compounding quantity (content).

The mass average molecular weight (Mw) of the oligomer contained in the solventless resin composition (y1) is 50000 or less, preferably 1000 to 50000, more preferably 2000 to 40000, and still more preferably 3000 to 35000. More preferably, it is 4000-30000.

Moreover, as said oligomer, what is necessary is just to have an ethylenically unsaturated group whose mass mean molecular weight is 50000 or less among resin contained in the above-mentioned resin composition (y), but the above-mentioned urethane prepolymer (UP ) Is preferred.
As the oligomer, a modified olefin resin having an ethylenically unsaturated group can also be used.

The total content of the oligomer and the energy beam polymerizable monomer in the solventless resin composition (y1) is preferably 50 with respect to the total amount (100% by mass) of the solventless resin composition (y1). It is ˜99% by mass, more preferably 60 to 95% by mass, still more preferably 65 to 90% by mass, and still more preferably 70 to 85% by mass.

Examples of the energy ray polymerizable monomer include isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxy (meth) acrylate, cyclohexyl (meth) acrylate, adamantane ( Cycloaliphatic polymerizable compounds such as (meth) acrylate and tricyclodecane acrylate; Aromatic polymerizable compounds such as phenylhydroxypropyl acrylate, benzyl acrylate and phenol ethylene oxide modified acrylate; Tetrahydrofurfuryl (meth) acrylate, morpholine acrylate, N- And heterocyclic polymerizable compounds such as vinylpyrrolidone and N-vinylcaprolactam.
These energy beam polymerizable monomers may be used independently and may use 2 or more types together.

The content ratio of the oligomer and the energy beam polymerizable monomer (oligomer / energy beam polymerizable monomer) in the solventless resin composition (y1) is preferably 20/80 to 90 / in mass ratio. 10, more preferably 30/70 to 85/15, still more preferably 35/65 to 80/20.

In one embodiment of the present invention, it is preferable that the solventless resin composition (y1) is further blended with a photopolymerization initiator.
By containing the photopolymerization initiator, the curing reaction can be sufficiently advanced even by irradiation with a relatively low energy beam.

Examples of the photopolymerization initiator include 1-hydroxy-cyclohexyl-phenyl-ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyrol. Nitrile, dibenzyl, diacetyl, 8-chloroanthraquinone and the like can be mentioned.
These photoinitiators may be used independently and may use 2 or more types together.

The blending amount of the photopolymerization initiator is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 4 parts by mass with respect to the total amount (100 parts by mass) of the oligomer and the energy ray polymerizable monomer. The amount is preferably 0.02 to 3 parts by mass.

(Adhesive layer)
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of one embodiment of the present invention only needs to contain a pressure-sensitive adhesive resin, and if necessary, for pressure-sensitive adhesives such as a crosslinking agent, a tackifier, a polymerizable compound, and a polymerization initiator. An additive may be contained.
Note that the pressure-sensitive adhesive layer included in the pressure-sensitive adhesive sheet of one embodiment of the present invention is non-thermal from the viewpoint of preventing an object such as a mounted semiconductor chip from sinking into the pressure-sensitive adhesive layer due to heating in the sealing step. It is preferable that it is an expandable adhesive layer.

In one embodiment of the present invention, the adhesive force on the adhesive surface of the adhesive layer on which an object such as a semiconductor chip is placed at 23 ° C. before expansion of the thermally expandable particles is preferably 0.1 to 10 It is 0.0 N / 25 mm, more preferably 0.2 to 8.0 N / 25 mm, still more preferably 0.4 to 6.0 N / 25 mm, and still more preferably 0.5 to 4.0 N / 25 mm.
If the adhesive force is 0.1 N / 25 mm or more, the adherend such as a semiconductor chip can be sufficiently fixed to the extent that positional displacement can be prevented in the next step such as a sealing step.
On the other hand, if the said adhesive force is 10.0 N / 25mm or less, at the time of peeling, it can peel easily with slight force by heating to the temperature more than expansion start temperature (t).
In addition, said adhesive force means the value measured by the method as described in an Example.

In the pressure-sensitive adhesive sheet of one embodiment of the present invention, the storage shear modulus G ′ (23) of the pressure-sensitive adhesive layer on which an object such as a semiconductor chip is placed at 23 ° C. is preferably 1.0 × 10 ⁴ to It is 1.0 × 10 ⁸ Pa, more preferably 5.0 × 10 ⁴ to 5.0 × 10 ⁷ Pa, and still more preferably 1.0 × 10 ⁵ to 1.0 × 10 ⁷ Pa.
In the case of the pressure-sensitive adhesive sheet having a plurality of pressure-sensitive adhesive layers, it is preferable that the storage shear modulus G ′ (23) of the pressure-sensitive adhesive layer to which an object such as a semiconductor chip is attached is in the above range. It is preferable that the storage shear modulus G ′ (23) of all the pressure-sensitive adhesive layers on the side to which an object such as a semiconductor chip is attached rather than the material is within the above range. Further, the storage shear elastic modulus G ′ (23) of the pressure-sensitive adhesive layer on the side opposite to the side to which the object such as a semiconductor chip is affixed with respect to the thermally expandable base material may be within the above range. It may be outside.
If the storage shear elastic modulus G ′ (23) of the pressure-sensitive adhesive layer is 1.0 × 10 ⁴ Pa or more, it is possible to prevent positional deviation when attaching an object such as a semiconductor chip, It is possible to prevent excessive sinking into the adhesive layer.
On the other hand, if the storage shear modulus G ′ (23) of the pressure-sensitive adhesive layer is 1.0 × 10 ⁸ Pa or less, it becomes easy to be deformed by heating to a temperature of the expansion start temperature (t) or more during peeling, Due to the expansion of the thermally expandable particles in the thermally expandable substrate, irregularities are easily formed on the surface of the pressure-sensitive adhesive layer, and as a result, it can be easily peeled off with a slight force.
In addition, in this specification, the storage shear modulus G '(23) of an adhesive layer means the value measured by the method as described in an Example.

In addition, when it is an adhesive sheet which has several adhesive layers like the double-

sided adhesive sheets

2a and 2b shown in FIG. 2, among the several adhesive layers, the adhesive on which objects, such as a semiconductor chip, are mounted The storage shear modulus G ′ (23) of the layer is preferably within the above range.
On the other hand, in order to fix the pressure-sensitive adhesive sheet, the storage shear modulus G ′ (23) of the pressure-sensitive adhesive layer on the side to be attached to the support or the like at 23 ° C. has good adhesion to the support or the like. From the viewpoint, it is preferably 1.0 × 10 ⁴ to 1.0 × 10 ⁸ Pa, more preferably 3.0 × 10 ⁴ to 5.0 × 10 ⁷ Pa, still more preferably 5.0 × 10 ⁴ to 1. 0 × 10 ⁷ Pa.

The thickness (23 ° C.) of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of one embodiment of the present invention is due to the viewpoint of developing excellent pressure-sensitive adhesive force and the expansion of the heat-expandable particles in the heat-expandable base material by heat treatment. From the viewpoint of easily forming irregularities on the surface of the pressure-sensitive adhesive layer to be formed, the thickness is preferably 1 to 60 μm, more preferably 2 to 50 μm, still more preferably 3 to 40 μm, still more preferably 5 to 30 μm.

In the pressure-sensitive adhesive sheet of one embodiment of the present invention, the ratio of the thickness of the heat-expandable base material to the thickness of the pressure-sensitive adhesive layer at 23 ° C. [heat-expandable base material / pressure-sensitive adhesive layer] In the sealing step, from the viewpoint of flattening the surface on the object side after sealing and preventing positional displacement of the object, it is preferably 0.2 or more, more preferably 0.5 or more, and still more preferably. 1.0 or more, still more preferably 5.0 or more, and from the viewpoint of making a pressure-sensitive adhesive sheet that can be easily peeled with a slight force when peeled, preferably 1000 or less, more preferably 200 or less, More preferably, it is 60 or less, More preferably, it is 30 or less.

In the present specification, when the adhesive sheet has a plurality of adhesive layers, such as the double-

sided adhesive sheets

2a and 2b shown in FIG. 2, the “thickness of the adhesive layer” at 23 ° C. is It means the thickness of each adhesive layer. That is, for each pressure-sensitive adhesive layer, it is preferable that the thickness and the ratio [thermally expandable substrate / pressure-sensitive adhesive layer] are within the above ranges.
Moreover, the thickness of the adhesive layer in 23 degreeC means the value measured by the method as described in an Example.

The adhesive layer which the adhesive sheet of 1 aspect of this invention has can be formed from the adhesive composition containing adhesive resin.
Moreover, in the adhesive sheet which has several adhesive layers like the double-

sided adhesive sheet

2a, 2b shown in FIG. 2, each adhesive layer may be formed from the same adhesive composition, and it mutually differs. You may form from an adhesive composition.
Hereinafter, each component contained in the pressure-sensitive adhesive composition which is a material for forming the pressure-sensitive adhesive layer will be described.

<Adhesive resin>
As the adhesive resin used in one embodiment of the present invention, any polymer may be used as long as the resin has adhesiveness and has a mass average molecular weight (Mw) of 10,000 or more.
The mass average molecular weight (Mw) of the adhesive resin used in one embodiment of the present invention is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,500,000, and even more preferably 30,000, from the viewpoint of improving the adhesive strength. ~ 1 million.

Specific examples of the adhesive resin include rubber resins such as acrylic resins, urethane resins, and polyisobutylene resins, polyester resins, olefin resins, silicone resins, and polyvinyl ether resins.
These adhesive resins may be used independently and may use 2 or more types together.
In addition, when these adhesive resins are copolymers having two or more kinds of structural units, the form of the copolymer is not particularly limited, and a block copolymer, a random copolymer, and a graft copolymer are not limited. Any of polymers may be used.

The adhesive resin used in one embodiment of the present invention may be an energy ray curable adhesive resin in which a polymerizable functional group is introduced into the side chain of the above-mentioned adhesive resin.
Examples of the polymerizable functional group include a (meth) acryloyl group and a vinyl group.
Examples of energy rays include ultraviolet rays and electron beams, but ultraviolet rays are preferred.

The content of the adhesive resin is preferably 30 to 99.99% by mass, more preferably 40 to 99.95% by mass, still more preferably based on the total amount (100% by mass) of the active ingredients of the adhesive composition. It is 50 to 99.90% by mass, more preferably 55 to 99.80% by mass, still more preferably 60 to 99.50% by mass.
In the following description of the present specification, “content of each component relative to the total amount of active ingredients of the pressure-sensitive adhesive composition” means “content of each component in the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition”. Is synonymous with.

In one embodiment of the present invention, it is easy to form unevenness on the surface of the pressure-sensitive adhesive layer formed by the viewpoint of developing excellent adhesive force and the expansion of the thermally expandable particles in the thermally expandable substrate by heat treatment. In view of this, the adhesive resin preferably contains an acrylic resin.
The content of the acrylic resin in the adhesive resin is preferably 30 to 100% by mass, more preferably 50 to 100% by mass with respect to the total amount (100% by mass) of the adhesive resin contained in the adhesive composition. %, More preferably 70 to 100% by mass, and still more preferably 85 to 100% by mass.

(Acrylic resin)
In one embodiment of the present invention, the acrylic resin that can be used as an adhesive resin includes, for example, a polymer including a structural unit derived from an alkyl (meth) acrylate having a linear or branched alkyl group, a cyclic structure And a polymer containing a structural unit derived from a (meth) acrylate having a hydrogen atom.

The mass average molecular weight (Mw) of the acrylic resin is preferably 100,000 to 1,500,000, more preferably 200,000 to 1,300,000, still more preferably 350,000 to 1,200,000, still more preferably 500,000 to 1,100,000. .

As an acrylic resin used in one embodiment of the present invention, a structural unit (a1) derived from an alkyl (meth) acrylate (a1 ′) (hereinafter also referred to as “monomer (a1 ′)”) and a functional group-containing monomer (a2). An acrylic copolymer (A1) having a structural unit (a2) derived from ') (hereinafter also referred to as "monomer (a2')") is more preferred.

The number of carbon atoms of the alkyl group contained in the monomer (a1 ′) is preferably 1 to 24, more preferably 1 to 12, still more preferably 2 to 10, and still more preferably 4 to 8 from the viewpoint of improving adhesive properties. It is.
The alkyl group contained in the monomer (a1 ′) may be a linear alkyl group or a branched alkyl group.

Examples of the monomer (a1 ′) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, tridecyl ( Examples include meth) acrylate and stearyl (meth) acrylate.
These monomers (a1 ′) may be used alone or in combination of two or more.
As the monomer (a1 ′), methyl (meth) acrylate, butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are preferable. For example, butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are preferable.

The content of the structural unit (a1) is preferably 50 to 99.9% by mass, more preferably 60 to 99.0% by mass with respect to the total structural unit (100% by mass) of the acrylic copolymer (A1). %, More preferably 70 to 97.0% by mass, and still more preferably 80 to 95.0% by mass.

As a functional group which a monomer (a2 ') has, a hydroxyl group, a carboxy group, an amino group, an epoxy group etc. are mentioned, for example.
That is, examples of the monomer (a2 ′) include a hydroxyl group-containing monomer, a carboxy group-containing monomer, an amino group-containing monomer, and an epoxy group-containing monomer.
These monomers (a2 ′) may be used alone or in combination of two or more.
Among these, as the monomer (a2 ′), a hydroxyl group-containing monomer and a carboxy group-containing monomer are preferable.

Examples of the hydroxyl group-containing monomer include the same hydroxyl group-containing compounds as described above.

Examples of the carboxy group-containing monomer include ethylenically unsaturated monocarboxylic acids such as (meth) acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid and citraconic acid, and anhydrides thereof. 2- (acryloyloxy) ethyl succinate, 2-carboxyethyl (meth) acrylate, and the like.

The content of the structural unit (a2) is preferably 0.1 to 40% by weight, more preferably 0.5 to 35% by weight with respect to all the structural units (100% by weight) of the acrylic copolymer (A1). %, More preferably 1.0 to 30% by mass, and still more preferably 3.0 to 25% by mass.

The acrylic copolymer (A1) may further have a structural unit (a3) derived from another monomer (a3 ′) other than the monomers (a1 ′) and (a2 ′).
In the acrylic copolymer (A1), the content of the structural units (a1) and (a2) is preferably 70 with respect to the total structural units (100% by mass) of the acrylic copolymer (A1). To 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, and still more preferably 95 to 100% by mass.

Examples of the monomer (a3 ′) include olefins such as ethylene, propylene, and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; diene monomers such as butadiene, isoprene, and chloroprene; cyclohexyl (meth) acrylate, It has a cyclic structure such as benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, imide (meth) acrylate, etc. (Meth) acrylate; styrene, α-methylstyrene, vinyl toluene, vinyl formate, vinyl acetate, acrylonitrile, (meth) acrylamide, (meth) acrylonitrile, (meth) acryloyl Ruhorin, N- vinylpyrrolidone and the like.

The acrylic copolymer (A1) may be an energy ray curable acrylic copolymer having a polymerizable functional group introduced in the side chain.
The polymerizable functional group and the energy ray are as described above.
The polymerizable functional group includes an acrylic copolymer having the above structural units (a1) and (a2), and a substituent that can be bonded to the functional group of the structural unit (a2) of the acrylic copolymer. And a compound having a polymerizable functional group can be reacted.
Examples of the compound include (meth) acryloyloxyethyl isocyanate, (meth) acryloyl isocyanate, glycidyl (meth) acrylate, and the like.

<Crosslinking agent>
In one aspect of the present invention, the pressure-sensitive adhesive composition preferably further contains a cross-linking agent when it contains a pressure-sensitive adhesive resin containing a functional group such as the acrylic copolymer (A1) described above.
The said crosslinking agent reacts with the adhesive resin which has a functional group, and bridge | crosslinks adhesive resins by using the said functional group as a crosslinking origin.

Examples of the crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, and a metal chelate crosslinking agent.
These crosslinking agents may be used independently and may use 2 or more types together.
Among these crosslinking agents, an isocyanate-based crosslinking agent is preferable from the viewpoints of increasing cohesive force and improving adhesive force, and availability.

The content of the crosslinking agent is appropriately adjusted depending on the number of functional groups that the adhesive resin has, but is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the adhesive resin having a functional group, The amount is more preferably 0.03 to 7 parts by mass, still more preferably 0.05 to 5 parts by mass.

<Tackifier>
In one embodiment of the present invention, the pressure-sensitive adhesive composition may further contain a tackifier from the viewpoint of further improving the adhesive strength.
In the present specification, the “tackifier” is a component that assists in improving the adhesive strength of the above-mentioned adhesive resin, and refers to an oligomer having a mass average molecular weight (Mw) of less than 10,000. It is distinguished from a functional resin.
The mass average molecular weight (Mw) of the tackifier is preferably 400 to 10000, more preferably 5000 to 8000, and still more preferably 800 to 5000.

Examples of the tackifier are obtained by copolymerizing C5 fractions such as rosin resin, terpene resin, styrene resin, pentene, isoprene, piperine, 1.3-pentadiene generated by thermal decomposition of petroleum naphtha. And C9 petroleum resin obtained by copolymerizing C9 fractions such as indene generated by thermal decomposition of petroleum naphtha and vinyltoluene, and hydrogenated resins obtained by hydrogenating these.

The softening point of the tackifier is preferably 60 to 170 ° C, more preferably 65 to 160 ° C, and still more preferably 70 to 150 ° C.
In the present specification, the “softening point” of the tackifier means a value measured according to JIS K2531.
A tackifier may be used independently and may use 2 or more types from which a softening point and a structure differ.
And when using 2 or more types of several tackifier, it is preferable that the weighted average of the softening point of these several tackifier belongs to the said range.

The content of the tackifier is preferably 0.01 to 65% by mass, more preferably 0.05 to 55% by mass, and still more preferably relative to the total amount (100% by mass) of the active ingredients of the adhesive composition. It is 0.1 to 50% by mass, more preferably 0.5 to 45% by mass, still more preferably 1.0 to 40% by mass.

<Photopolymerization initiator>
1 aspect of this invention WHEREIN: When an adhesive composition contains an energy-beam curable adhesive resin as an adhesive resin, it is preferable to contain a photoinitiator further.
By forming an adhesive composition containing an energy ray-curable adhesive resin and a photopolymerization initiator, the adhesive layer formed from the adhesive composition can be irradiated with a relatively low energy energy beam. It is possible to sufficiently advance the curing reaction and adjust the adhesive strength to a desired range.
In addition, as a photoinitiator used by one aspect | mode of this invention, the same thing as what is mix | blended with the above-mentioned solvent-free resin composition (y1) is mentioned.

The content of the photopolymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, and still more preferably 0.001 parts by mass with respect to 100 parts by mass of the energy ray curable adhesive resin. 05 to 2 parts by mass.

<Adhesive additive>
In one embodiment of the present invention, the pressure-sensitive adhesive composition as a material for forming the pressure-sensitive adhesive layer is a pressure-sensitive adhesive used for general pressure-sensitive adhesives in addition to the above-described additives, as long as the effects of the present invention are not impaired. May contain additives.
Examples of such an adhesive additive include antioxidants, softeners (plasticizers), rust inhibitors, pigments, dyes, retarders, reaction accelerators (catalysts), ultraviolet absorbers, and the like.
These pressure-sensitive adhesive additives may be used alone or in combination of two or more.

When these pressure-sensitive adhesive additives are contained, the content of each pressure-sensitive adhesive additive is preferably 0.0001 to 20 parts by mass, more preferably 0.001 to 100 parts by mass of the adhesive resin. ~ 10 parts by mass.

The pressure-sensitive adhesive composition, which is a material for forming the pressure-sensitive adhesive layer, may contain thermally expandable particles as long as the effects of the present invention are not impaired.
However, as described above, the pressure-sensitive adhesive layer included in the pressure-sensitive adhesive sheet of one embodiment of the present invention is preferably a non-thermally expandable pressure-sensitive adhesive layer. Therefore, the pressure-sensitive adhesive composition, which is a material for forming the pressure-sensitive adhesive layer, is more preferable as the content of thermally expandable particles is as small as possible.
The content of the heat-expandable particles is preferably less than 5% by mass, more preferably less than 1% by mass, and still more preferably 0.1% by mass with respect to the total amount (100% by mass) of the active ingredients of the pressure-sensitive adhesive composition. Is more preferably less than 0.01% by mass, particularly preferably less than 0.001% by mass.

[Release material]
Like the adhesive sheet 1b of FIG.1 (b) and the adhesive sheet 2b of FIG.2 (b), the double-sided adhesive sheet of 1 aspect of this invention has a peeling material further on the sticking surface of an adhesive layer. Also good.
In addition, in the adhesive sheet which has two adhesive layers like the adhesive sheet 2b of FIG.2 (b), the two peeling materials provided on the sticking surface of each adhesive layer differ in the peeling force difference. It is preferable that it is adjusted as described above.
As the release material, a release sheet that has been subjected to a double-sided release process, a release sheet that has been subjected to a single-sided release process, or the like is used. Examples include a release material coated on a release material substrate.

Examples of the base material for the release material include papers such as high-quality paper, glassine paper, and kraft paper; polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin; and olefins such as polypropylene resin and polyethylene resin. A plastic film such as a resin film;

Examples of the release agent include silicone-based resins, olefin-based resins, isoprene-based resins, rubber-based elastomers such as butadiene-based resins, long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins.

The thickness of the release material at 23 ° C. is not particularly limited, but is preferably 10 to 200 μm, more preferably 25 to 170 μm, and still more preferably 35 to 80 μm.

[Method for producing adhesive sheet]
There is no restriction | limiting in particular as a manufacturing method of the adhesive sheet of this invention, The manufacturing method (a) which has the following process (1a) and (2a) is mentioned.
Step (1a): On the release treatment surface of the release material, the resin composition (y), which is a material for forming the thermally expandable substrate, is applied to form a coating film, and the coating film is dried or irradiated with UV. Forming a thermally expandable substrate.
Step (2a): On the surface of the formed thermally expandable substrate, a pressure-sensitive adhesive composition, which is a material for forming a pressure-sensitive adhesive layer, is applied to form a coating film, and the coating film is dried. Forming a layer;

Another method for producing the pressure-sensitive adhesive sheet of the present invention includes a method (b) having the following steps (1b) to (3b).
Step (1b): On the release treatment surface of the release material, the resin composition (y), which is a material for forming the thermally expandable substrate, is applied to form a coating film, the coating film is dried, and the thermal expansion is performed. Forming a conductive substrate.
Step (2b): On the release treatment surface of the release material, a pressure-sensitive adhesive composition as a material for forming the pressure-sensitive adhesive layer is applied to form a coating film, the coating film is dried, and the pressure-sensitive adhesive layer is formed. Process.
Step (3b): A step of bonding the surface of the thermally expandable substrate formed in step (1b) and the surface of the pressure-sensitive adhesive layer formed in step (2b).

In the production methods (a) and (b), the resin composition (y) and the pressure-sensitive adhesive composition may be further mixed with a diluent solvent to form a solution.
Examples of the coating method include spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating.

Further, in the step (1a) of the production method (a) and the step (1b) of the production method (b), the expansion of the thermally expandable particles is prevented in the drying process of forming the thermally expandable substrate from the coating film. From the viewpoint, the drying temperature is preferably less than the expansion start temperature (t) of the thermally expandable particles.

[Use of pressure-sensitive adhesive sheet of the present invention, method of using pressure-sensitive adhesive sheet]
When temporarily fixing an object, the pressure-sensitive adhesive sheet of the present invention can be easily peeled off with a slight force while peeling while suppressing the sinking of the object during heating.
Therefore, the pressure-sensitive adhesive sheet of the present invention is preferably used in a sealing step with heating using a sealing resin, and specifically, preferably used in a sealing step when manufacturing FOWLP. .

In the sealing step when manufacturing FOWLP, the semiconductor chip is placed on the adhesive surface of the adhesive layer of the adhesive sheet of the present invention, and then the upper surface and the adhesive surface of the semiconductor chip are covered with a sealing resin and heated. Sealing is performed by thermosetting the sealing resin.
At this time, when a general pressure-sensitive adhesive sheet is used, the elastic modulus of each layer constituting the pressure-sensitive adhesive sheet decreases due to heating in the sealing process, and the semiconductor chip placed sinks to the pressure-sensitive adhesive sheet side. Is seen.
On the other hand, the pressure-sensitive adhesive sheet of the present invention satisfies the above requirement (1), and thus effectively suppresses the sinking of the semiconductor chip to the pressure-sensitive adhesive sheet side, which may occur in the sealing step, and the semiconductor after sealing. The surface on the chip side can be flattened, and the occurrence of misalignment of the semiconductor chip can be suppressed.

As the sealing resin, an arbitrary one can be appropriately selected from those used as a semiconductor sealing material. For example, a sealing resin containing a thermosetting resin or an energy ray curable resin can be used. And a sealing resin containing
Further, the sealing resin may be a solid such as a granule or a sheet at room temperature, or a liquid in the form of a composition. From the viewpoint of workability, the sealing resin is in the form of a sheet. Is preferred.

As a method of covering the semiconductor chip and its peripheral part using the sealing resin, it is appropriately selected and applied according to the type of the sealing resin from methods conventionally used in the semiconductor sealing process. For example, a roll laminating method, a vacuum pressing method, a vacuum laminating method, a spin coating method, a die coating method, a transfer molding method, a compression molding mold method, or the like can be applied.

In addition, it is preferable that a sealing process is performed on temperature conditions less than the expansion start temperature (t) of a thermally expansible particle.
The sealing resin coating process and the thermosetting process may be performed separately. However, when the sealing resin is heated in the coating process, the sealing resin is cured as it is by the heating, and the coating process is performed. And thermosetting treatment may be performed simultaneously.

On the other hand, after the sealing step is completed, the pressure-sensitive adhesive sheet can be easily peeled with a slight force by heating to a temperature equal to or higher than the expansion start temperature (t).
The “temperature higher than the expansion start temperature (t)” when peeling the adhesive sheet is preferably “expansion start temperature (t) + 10 ° C.” or higher and “expansion start temperature (t) + 60 ° C.” or lower. It is more preferable that the expansion start temperature (t) + 15 ° C. or more and “expansion start temperature (t) + 40 ° C.” or less.

Moreover, from the above-mentioned characteristic of the adhesive sheet of this invention, this invention can also provide the usage method of the adhesive sheet of following [1].
[1] A method for using a pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive sheet is peeled from the adherend by a heat treatment at a temperature equal to or higher than an expansion start temperature (t) after the pressure-sensitive adhesive sheet of the present invention is attached to the adherend.
In addition, it is preferable to use the said usage method at the sealing process with a heating using sealing resin.

The present invention will be specifically described with reference to the following examples, but the present invention is not limited to the following examples. In addition, the physical-property value in the following manufacture examples and Examples is a value measured by the following method.

<Mass average molecular weight (Mw)>
Using a gel permeation chromatograph (product name “HLC-8020” manufactured by Tosoh Corporation), measurement was performed under the following conditions, and values measured in terms of standard polystyrene were used.
(Measurement condition)
Column: “TSK guard column HXL-L”, “TSK gel G2500HXL”, “TSK gel G2000HXL”, and “TSK gel G1000HXL” (both manufactured by Tosoh Corporation) Column temperature: 40 ° C.
・ Developing solvent: Tetrahydrofuran ・ Flow rate: 1.0 mL / min

<Measurement of thickness of each layer>
The thickness (23 ° C.) of each layer was measured using a constant pressure thickness measuring instrument (model number: “PG-02J”, standard standards: conforming to JIS K6783, Z1702, Z1709) manufactured by Teclock Co., Ltd.

<Average particle diameter (D ₅₀ ) of thermally expandable particles, 90% particle diameter (D ₉₀ )>
The particle distribution of the thermally expandable particles before expansion at 23 ° C. was measured using a laser diffraction particle size distribution measuring apparatus (for example, product name “Mastersizer 3000” manufactured by Malvern).
The particle diameters corresponding to 50% and 90% of the cumulative volume frequency calculated from the smaller particle diameter of the particle distribution are expressed as “average particle diameter (D ₅₀ ) of thermally expandable particles” and “thermally expandable particles”, respectively. 90% particle diameter (D ₉₀ ) ”.

<Storage elastic modulus E 'of thermally expandable substrate>
When the measurement target was a non-adhesive thermally expandable substrate, the thermally expandable substrate was 5 mm long × 30 mm wide × 200 μm thick, and the test piece was prepared by removing the release material.
Using a dynamic viscoelasticity measuring apparatus (TA Instruments, product name “DMAQ800”), a test start temperature of 0 ° C., a test end temperature of 300 ° C., a temperature increase rate of 3 ° C./min, a frequency of 1 Hz, and an amplitude of 20 μm Under the conditions, the storage elastic modulus E ′ of the test sample at a predetermined temperature was measured.

<Storage shear modulus G ′ of the pressure-sensitive adhesive layer, storage elastic modulus E ′ of the thermally expandable pressure-sensitive adhesive layer>
When the object to be measured is a heat-expandable pressure-sensitive adhesive layer and a pressure-sensitive adhesive layer having a tackiness, the heat-expandable pressure-sensitive adhesive layer and the pressure-sensitive adhesive layer are 8 mm in diameter x 3 mm in thickness, and the release material is removed from the test sample. It was.
Torsional shear using a viscoelasticity measuring device (manufactured by Anton Paar, device name “MCR300”) under the conditions of a test start temperature of 0 ° C., a test end temperature of 300 ° C., a heating rate of 3 ° C./min, and a frequency of 1 Hz By the method, the storage shear modulus G ′ of the test sample at a predetermined temperature was measured.
The value of the storage elastic modulus E ′ was calculated from the approximate expression “E ′ = 3G ′” based on the measured value of the storage shear elastic modulus G ′.

<Probe tack value>
After cutting the heat-expandable base material or the heat-expandable pressure-sensitive adhesive layer to be measured into a square with a side of 10 mm, it is left to stand in an environment of 23 ° C. and 50% RH (relative humidity) for 24 hours, The removed sample was used as a test sample.
Under the environment of 23 ° C. and 50% RH (relative humidity), using a tacking tester (manufactured by Nippon Special Instrument Co., Ltd., product name “NTS-4800”), the light release film was removed and exposed. The probe tack value on the surface of the test sample was measured according to JIS Z0237: 1991.
Specifically, a stainless steel probe having a diameter of 5 mm is brought into contact with the surface of the test sample at a contact load of 0.98 N / cm ² for 1 second, and then the probe is tested at a speed of 10 mm / second. The force required to move away from the surface was measured. And the measured value was made into the probe tack value of the test sample.

Details of the adhesive resin, additives, thermally expandable particles, and release material used in the formation of each layer in the following production examples are as follows.
<Adhesive resin>
Acrylic copolymer (i): having a structural unit derived from a raw material monomer consisting of 2-ethylhexyl acrylate (2EHA) / 2-hydroxyethyl acrylate (HEA) = 80.0 / 20.0 (mass ratio), A solution containing an acrylic copolymer having a Mw of 600,000. Diluting solvent: ethyl acetate, solid content concentration: 40% by mass.
Acrylic copolymer (ii): n-butyl acrylate (BA) / methyl methacrylate (MMA) / 2-hydroxyethyl acrylate (HEA) / acrylic acid = 86.0 / 8.0 / 5.0 / 1. A solution containing an acrylic copolymer having an Mw of 600,000 having a structural unit derived from a raw material monomer consisting of 0 (mass ratio). Diluting solvent: ethyl acetate, solid content concentration: 40% by mass.
<Additives>
Isocyanate crosslinking agent (i): manufactured by Tosoh Corporation, product name “Coronate L”, solid content concentration: 75 mass%.
Photopolymerization initiator (i): manufactured by BASF, product name “Irgacure 184”, 1-hydroxy-cyclohexyl-phenyl-ketone.
<Thermal expandable particles>
Thermally expandable particles (i): manufactured by Kureha Co., Ltd., product name “S2640”, expansion start temperature (t) = 208 ° C., average particle size (D ₅₀ ) = 24 μm, 90% particle size (D ₉₀ ) = 49 μm .
<Release material>
Heavy release film: manufactured by Lintec Corporation, product name “SP-PET382150”, a polyethylene terephthalate (PET) film provided with a release agent layer formed from a silicone release agent on one side, thickness: 38 μm.
Light release film: manufactured by Lintec Co., Ltd., product name “SP-PET381031”, a PET film provided with a release agent layer formed from a silicone release agent on one side, thickness: 38 μm.

Production Example 1 (Formation of first adhesive layer (X-1))
The isocyanate-based crosslinking agent (i) 5.0 parts by mass (solid content ratio) is blended with 100 parts by mass of the solid content of the acrylic copolymer (i), which is an adhesive resin, and diluted with toluene. The composition (x-1) having a solid content concentration (active ingredient concentration) of 25% by mass was prepared by stirring uniformly.
Then, on the surface of the release agent layer of the above heavy release film, the prepared composition (x-1) was applied to form a coating film, and the coating film was dried at 100 ° C. for 60 seconds to have a thickness of 10 μm. The first pressure-sensitive adhesive layer (X-1) was formed.
The storage shear modulus G ′ (23) of the first pressure-sensitive adhesive layer (X-1) at 23 ° C. was 2.5 × 10 ⁵ Pa.

Production Example 2 (Formation of second adhesive layer (X-2))
The isocyanate-based crosslinking agent (i) 0.8 parts by mass (solid content ratio) is blended with 100 parts by mass of the acrylic copolymer (ii), which is an adhesive resin, and diluted with toluene, The composition (x-2) having a solid content concentration (active ingredient concentration) of 25% by mass was prepared by stirring uniformly.
Then, on the surface of the release agent layer of the light release film, the prepared composition (x-2) was applied to form a coating film, and the coating film was dried at 100 ° C. for 60 seconds to have a thickness of 10 μm. The second pressure-sensitive adhesive layer (X-2) was formed.
The storage shear modulus G ′ (23) of the second pressure-sensitive adhesive layer (X-2) at 23 ° C. was 9.0 × 10 ⁴ Pa.

Production Example 3 (Formation of Thermally Expandable Substrate (Y-1))
(1) Preparation of Composition (y-1) A terminal isocyanate urethane prepolymer obtained by reacting an ester-type diol with isophorone diisocyanate (IPDI) was reacted with 2-hydroxyethyl acrylate to obtain a mass average molecular weight ( Mw) 5000 bifunctional acrylic urethane oligomer was obtained.
Then, 40% by mass (solid content ratio) of the acrylic urethane-based oligomer synthesized as described above, 40% by mass (solid content ratio) of isobornyl acrylate (IBXA), and phenylhydroxypropyl acrylate (HPPA) as an energy ray polymerizable monomer ) 20% by mass (solid content ratio), and 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF Corporation) as a photopolymerization initiator with respect to 100 parts by mass of the total amount of the acrylic urethane oligomer and the energy ray polymerizable monomer. The product name “Irgacure 184”) 2.0 parts by mass (solid content ratio) and 0.2 parts by mass (solid content ratio) phthalocyanine pigment as an additive were blended to prepare an energy ray curable composition. .
And the said heat-expandable particle | grains (i) were mix | blended with the said energy-beam curable composition, and the solvent-free composition (y-1) which does not contain a solvent was prepared.
The content of thermally expandable particles (i) relative to the total amount (100% by mass) of the composition (y-1) was 20% by mass.

(2) Formation of thermally expandable substrate (Y-1) The prepared composition (y-1) was applied on the surface of the release agent layer of the light release film to form a coating film.
Then, using an ultraviolet irradiation device (product name “ECS-401GX” manufactured by Eye Graphics Co., Ltd.) and a high-pressure mercury lamp (product name “H04-L41” manufactured by Eye Graphics Co., Ltd.), an illuminance of 160 mW / cm ² and a light amount of 500 mJ / The coating film was cured by irradiating ultraviolet rays under the condition of cm ² to form a thermally expandable substrate (Y-1) having a thickness of 50 μm. The above illuminance and light intensity during ultraviolet irradiation are values measured using an illuminance / light meter (product name “UV Power Pack II” manufactured by EIT).

Production Example 4 (Formation of Thermally Expandable Substrate (Y-2))
(1) Synthesis of urethane prepolymer In a reaction vessel under a nitrogen atmosphere, isophorone diisocyanate (IPDI) is mixed with carbonate type diol with respect to 100 parts by mass (solid content ratio) of carbonate type diol having a mass average molecular weight of 1,000. Mixing so that the equivalent ratio of hydroxyl group to isocyanate group of isophorone diisocyanate is 1/1, adding 160 parts by mass of toluene, until the isocyanate group concentration reaches the theoretical amount while stirring under a nitrogen atmosphere , And reacted at 80 ° C. for 6 hours or more.
Subsequently, a solution obtained by diluting 1.44 parts by mass (solid content ratio) of 2-hydroxyethyl methacrylate (2-HEMA) in 30 parts by mass of toluene is added, and further at 80 ° C. until the isocyanate groups at both ends disappear. The mixture was reacted for 6 hours to obtain a urethane prepolymer having a mass average molecular weight of 29,000.

(2) Synthesis of acrylic urethane-based resin In a reaction vessel under nitrogen atmosphere, 100 parts by mass (solid content ratio) of urethane prepolymer obtained in (1) above and 117 parts by mass (solid content ratio) of methyl methacrylate (MMA) 2-hydroxyethyl methacrylate (2-HEMA) 5.1 parts by mass (solid content ratio), 1-thioglycerol 1.1 parts by mass (solid content ratio), and toluene 50 parts by mass, The temperature was raised to ° C.
Further, a solution obtained by further diluting 2.2 parts by mass (solid content ratio) of radical initiator (manufactured by Nippon Finechem Co., Ltd., product name “ABN-E”) with 210 parts by mass of toluene in a reaction vessel was heated to 105 ° C. It was dripped over 4 hours, maintaining.
After completion of the dropping, the reaction was carried out at 105 ° C. for 6 hours to obtain a solution of an acrylic urethane resin having a mass average molecular weight of 105,000.

(3) Formation of Thermally Expandable Substrate (Y-2) The isocyanate-based crosslinking agent (i) is 6.3 parts by mass with respect to 100 parts by mass of the solid content of the acrylic urethane-based resin solution obtained in (2) above. Parts (solid content ratio), dioctyltin bis (2-ethylhexanoate) 1.4 parts by mass (solid content ratio) as a catalyst, and the above-mentioned thermally expandable particles (i), and diluted with toluene, The mixture was uniformly stirred to prepare a composition (y-2) having a solid content concentration (active ingredient concentration) of 30% by mass.
The content of the heat-expandable particles (i) relative to the total amount (100% by mass) of active ingredients in the obtained composition (y-2) was 20% by mass.
Then, on the surface of the release agent layer of the light release film, the prepared composition (y-2) was applied to form a coating film, and the coating film was dried at 100 ° C. for 120 seconds to have a thickness of 50 μm. A heat-expandable base material (Y-2) was formed.

Production Example 5 (Formation of thermally expandable pressure-sensitive adhesive layer (Y-3))
To 100 parts by mass of the solid content of the acrylic copolymer (ii), which is an adhesive resin, 6.3 parts by mass (solid content ratio) of the isocyanate-based crosslinking agent (i) and the thermally expandable particles ( i) was mixed, diluted with toluene, and stirred uniformly to prepare a composition (y-3) having a solid content concentration (active ingredient concentration) of 30% by mass.
The content of thermally expandable particles (i) relative to the total amount (100% by mass) of active ingredients in the obtained composition (y-3) was 20% by mass.
Then, on the surface of the release agent layer of the light release film, the prepared composition (y-3) was applied to form a coating film, and the coating film was dried at 100 ° C. for 120 seconds to have a thickness of 50 μm. The heat-expandable pressure-sensitive adhesive layer (Y-3) was formed.

Production Example 6 (Formation of thermally expandable substrate (Y-4))
(1) Synthesis of acrylic copolymer (iii) 52 parts by mass of n-butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 28 parts by mass of 2-hydroxyethyl acrylate (HEA) were mixed with an ethyl acetate solvent. The solution was polymerized in a non-energy ray curable acrylic copolymer.
The reaction is carried out by adding methacryloyloxyethyl isocyanate (MOI) in such an amount that the number of isocyanate groups is 0.9 equivalent to the total number of hydroxyl groups of the acrylic copolymer thus obtained to the solution containing the acrylic copolymer. Thus, an energy ray-curable acrylic copolymer (iii) having an Mw of 1,000,000 having a methacryloyl group in the side chain was obtained.

(2) Formation of thermally expandable base material (Y-4) The above isocyanate-based material is used with respect to 100 parts by mass of the solid content of the energy ray-curable acrylic copolymer (iii) obtained in (1) above. 0.5 parts by mass (solid content ratio) of the crosslinking agent (i), 3.0 parts by mass (solid content ratio) of the photopolymerization initiator (i), and the thermally expandable particles (i) are blended, and toluene. And the mixture was stirred uniformly to prepare a composition (y-4) having a solid content concentration (active ingredient concentration) of 30% by mass.
The content of the heat-expandable particles (1) relative to the total amount (100% by mass) of active ingredients in the obtained composition (y-4) was 20% by mass.
Then, on the surface of the release agent layer of the light release film, the prepared composition (y-4) was applied to form a coating film. After drying the coating film at 100 ° C. for 120 seconds, an illuminance of 160 mW / cm ^2. Irradiation with ultraviolet rays under conditions of a light amount of 500 mJ / cm ² formed a thermally expandable substrate (Y-4) having a thickness of 50 μm. The above illuminance and light intensity during ultraviolet irradiation are values measured using an illuminance / light meter (product name “UV Power Pack II” manufactured by EIT).

Thermally expandable substrates (Y-1) to (Y-2) and (Y-4) formed in Production Examples 3 to 4 and 6, and a thermally expandable pressure-sensitive adhesive layer (Y-3) formed in Production Example 5 ), The storage elastic modulus E ′ (208) and the probe tack value at 23 ° C., 100 ° C. and 208 ° C., which is the expansion start temperature of the thermally expandable particles used, were measured, respectively. These results are shown in Table 1.

Example 1
The surfaces of the first pressure-sensitive adhesive layer (X-1) formed in Production Example 1 and the heat-expandable base material (Y-1) formed in Production Example 3 were bonded together to form a heat-expandable base material (Y- The light release film on the 1) side was removed, and the second pressure-sensitive adhesive layer (X-2) formed in Production Example 2 was bonded onto the surface of the exposed thermally expandable substrate (Y-1).
As a result, the light release film / second pressure-sensitive adhesive layer (X-2) / thermally expandable substrate (Y-1) / first pressure-sensitive adhesive layer (X-1) / heavy release film were laminated in this order. A sheet (1) was produced.

Example 2
Lightly peelable film / second adhesive as in Example 1, except that the thermally expandable substrate (Y-1) was replaced with the thermally expandable substrate (Y-2) formed in Production Example 4. A pressure-sensitive adhesive sheet (2) was prepared by laminating layer (X-2) / thermally expandable substrate (Y-2) / first pressure-sensitive adhesive layer (X-1) / heavy release film in this order.

Comparative Example 1
The surfaces of the second pressure-sensitive adhesive layer (X-2) formed in Production Example 2 and the thermally expandable pressure-sensitive adhesive layer (Y-3) formed in Production Example 5 were bonded together.
Then, the light release film on the side of the heat-expandable pressure-sensitive adhesive layer (Y-3) is removed, and the first pressure-sensitive adhesive formed in Production Example 1 on the surface of the exposed heat-expandable pressure-sensitive adhesive layer (Y-3). The agent layer (X-1) was bonded.
Thus, the light release film / second pressure-sensitive adhesive layer (X-2) / thermally expandable pressure-sensitive adhesive layer (Y-3) / first pressure-sensitive adhesive layer (X-1) / heavy release film was laminated in this order. An adhesive sheet (3) was produced.

Comparative Example 2
Lightly peelable film / second adhesive as in Example 1, except that the thermally expandable substrate (Y-1) was replaced with the thermally expandable substrate (Y-4) formed in Production Example 6. A pressure-sensitive adhesive sheet (4) was prepared by laminating layer (X-2) / thermally expandable substrate (Y-4) / first pressure-sensitive adhesive layer (X-1) / heavy release film in this order.

Comparative Example 3
The surface of the second pressure-sensitive adhesive layer (X-2) formed in Production Example 2 and the surface of the heat-expandable pressure-sensitive adhesive layer (Y-3) formed in Production Example 5 are bonded together to form a light release film / second pressure-sensitive adhesive A pressure-sensitive adhesive sheet (5) in which layer (X-2) / heat-expandable pressure-sensitive adhesive layer (Y-3) / light release film was laminated in this order was produced.

Further, the following measurements were performed on the produced adhesive sheets (1) to (5). These results are shown in Table 2.

<Evaluation of misalignment of semiconductor chip during chip mounting and sealing process>
The light release film on the second pressure-sensitive adhesive layer (X-2) side of the produced pressure-sensitive adhesive sheets (1) to (5) is removed to support the pressure-sensitive adhesive surface of the exposed second pressure-sensitive adhesive layer (X-2) Affixed to the body.
Then, the heavy release film of the pressure-sensitive adhesive sheets (1) to (4) and the other light release film of the pressure-sensitive adhesive sheet (5) are removed, and the first pressure-sensitive adhesive layer (X-1) or the thermal expansibility that is exposed On the adhesive surface of the adhesive layer (Y-3), nine semiconductor chips (each chip size is 6.4 mm × 6.4 mm, chip thickness is 200 μm (# 2000)), the adhesive surface and each semiconductor The chips were placed at a necessary interval so as to be in contact with the circuit surface of the chip. Further, the light release film on the heat-expandable pressure-sensitive adhesive layer (Y-3) side of the pressure-sensitive adhesive sheet (5) is removed, and the pressure-sensitive adhesive sheet is placed on the pressure-sensitive adhesive surface of the exposed heat-expandable pressure-sensitive adhesive layer (Y-3). As in the cases (1) to (4), a semiconductor chip was placed.

After mounting the semiconductor chip on the pressure-sensitive adhesive sheets (1) to (5) as described above, the semiconductor chip on the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer is visually and microscopically observed to check whether the semiconductor chip is misaligned. Was confirmed and evaluated according to the following criteria.
A: A semiconductor chip in which a positional deviation of 25 μm or more with respect to the planned placement location was not confirmed.
F: A semiconductor chip in which a positional deviation of 25 μm or more with respect to the place to be placed was confirmed.

Thereafter, a sealing resin film is laminated on the adhesive surface and the semiconductor chip, and the semiconductor chip is sealed using a vacuum heating and pressure laminator (“7024HP5” manufactured by ROHM and HAAS) to produce a sealing body. did.
The sealing conditions are as follows.
-Preheating temperature: 100 ° C for both table and diaphragm
・ Vacuum drawing: 60 seconds ・ Dynamic press mode: 30 seconds ・ Static press mode: 10 seconds ・ Sealing temperature: 180 ° C. (temperature lower than 208 ° C. which is the expansion start temperature of thermally expandable particles)
・ Sealing time: x 60 minutes

After sealing, the pressure-sensitive adhesive sheets (1) to (5) are heated for 3 minutes at 240 ° C., which is equal to or higher than the expansion start temperature (208 ° C.) of the thermally expandable particles. The stop body is separated, and the semiconductor chip on the surface of the separated sealing body (the surface on which the adhesive sheet has been attached) is observed visually and with a microscope, and the presence or absence of misalignment of the semiconductor chip is confirmed. evaluated.
A: A semiconductor chip in which a positional deviation of 25 μm or more from before sealing was not confirmed.
F: A semiconductor chip in which a positional deviation of 25 μm or more occurred before sealing was confirmed.

<Evaluation of flatness of the surface on the semiconductor chip side after the sealing step>
The surface on the semiconductor chip side of the sealing body from which the pressure-sensitive adhesive sheets (1) to (5) are separated, obtained by the above-described “evaluation of positional deviation of the semiconductor chip during the sealing process”, is contact-type surface roughness meter (Mitutoyo The level difference was measured using “SV3000” manufactured by the company and evaluated according to the following criteria.
-A: The location where the level | step difference of 2 micrometers or more has arisen was not confirmed.
-F: The location where the level difference of 2 micrometers or more has arisen was confirmed.

<Measurement of adhesive strength of adhesive sheet before and after heating>
The light release film on the second pressure-sensitive adhesive layer (X-2) side of the produced pressure-sensitive adhesive sheets (1) to (5) is removed, and the second pressure-sensitive adhesive layer (X-2) is exposed on the pressure-sensitive adhesive surface. A 50 μm thick polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name “Cosmo Shine A4100”) was laminated to form an adhesive sheet with a substrate.
Then, the heavy release film of the pressure-sensitive adhesive sheets (1) to (4) is also removed, and the pressure-sensitive adhesive surface of the first pressure-sensitive adhesive layer (X-1) or the heat-expandable pressure-sensitive adhesive layer (Y-3) is exposed. A test sample was prepared by attaching to a stainless steel plate (SUS304 360 polishing) as an adherend and allowing it to stand for 24 hours in an environment of 23 ° C. and 50% RH (relative humidity). Further, the light release film on the heat-expandable pressure-sensitive adhesive layer (Y-3) side of the pressure-sensitive adhesive sheet (5) is removed, and the pressure-sensitive adhesive sheet is applied to the pressure-sensitive adhesive surface of the exposed heat-expandable pressure-sensitive adhesive layer (Y-3). Test samples were prepared in the same procedure as (1) to (4).
Then, using the above test sample, in an environment of 23 ° C. and 50% RH (relative humidity), in accordance with JIS Z0237: 2000, by a 180 ° peeling method at a pulling speed of 300 mm / min at 23 ° C. The adhesive strength was measured.
In addition, the above test sample is heated on a hot plate for 3 minutes at 240 ° C., which is equal to or higher than the expansion start temperature (208 ° C.) of the thermally expandable particles, and the standard environment (23 ° C., 50% RH (relative humidity)). Then, the adhesive strength after heating at a temperature equal to or higher than the expansion start temperature was also measured at a pulling rate of 300 mm / min by a 180 ° peeling method based on JIS Z0237: 2000.
In addition, when measurement of adhesive force was so difficult that it could not be affixed to the stainless steel plate which is a to-be-adhered body, it was set as "impossible to measure" and the adhesive force was set to 0 (N / 25mm).

From Table 2, in the pressure-sensitive adhesive sheets (1) and (2) of Examples 1 and 2, no misalignment of the semiconductor chip at the time of mounting the chip was observed, and the misalignment of the semiconductor chip at the sealing step was also observed. The surface on the semiconductor chip side after the sealing process was also flat.
In addition, the pressure-sensitive adhesive sheets (1) and (2) have good pressure-sensitive adhesive strength before heating, but the pressure-sensitive adhesive strength is reduced to such an extent that they cannot be measured after heating at or above the expansion start temperature. In some cases, the results proved that they were easily peelable with a slight force.

On the other hand, the pressure-sensitive adhesive sheet (3) of Comparative Example 1 and the pressure-sensitive adhesive sheet (5) of Comparative Example 3 have a thermally expandable pressure-sensitive adhesive layer, not a thermally expandable base material. The position shift of the semiconductor chip was observed, and a step was observed on the surface of the semiconductor chip side after the sealing process. Therefore, for example, it is considered that it is not suitable for use in a sealing process when manufacturing FOWLP.
In addition, the pressure-sensitive adhesive sheet (4) of Comparative Example 2 had a certain pressure-sensitive adhesive force even after heating at a temperature equal to or higher than the expansion start temperature, and could not be said to be peelable by heating.

DESCRIPTION OF SYMBOLS 1a,

1b Adhesive sheet

2a, 2b Double-sided adhesive sheet 11 Thermal expansible base material 12 Adhesive layer 121 1st adhesive layer 122 2nd

adhesive layer

13, 131, 132 Release material 50 FOWLP
51 Semiconductor Chip 52 Sealing Resin Layer 53 Redistribution Layer 54 Solder Ball

Claims

A pressure-sensitive adhesive sheet comprising a resin and heat-expandable particles having an expansion start temperature (t) of 120 to 250 ° C. and having a non-adhesive heat-expandable base material and a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive resin ,
The pressure-sensitive adhesive sheet, wherein the thermally expandable substrate satisfies the following requirements (1) to (2).
-Requirement (1): The storage elastic modulus E '(23) of the said thermally expansible base material in 23 degreeC is 1.0 * 10 < 6 > Pa or more.
Requirement (2): The storage elastic modulus E ′ (t) of the thermally expandable substrate at the expansion start temperature (t) of the thermally expandable particles is 1.0 × 10 7 Pa or less.
The pressure-sensitive adhesive sheet according to claim 1, wherein the thermally expandable substrate satisfies the following requirement (3).
-Requirement (3): The storage elastic modulus E '(100) of the said thermally expansible base material in 100 degreeC is 2.0 * 10 < 5 > Pa or more.
The ratio of the thickness of the thermally expandable substrate and the thickness of the pressure-sensitive adhesive layer (thermally expandable substrate / pressure-sensitive adhesive layer) at 23 ° C is 0.2 or more. Adhesive sheet.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein a thickness of the thermally expandable substrate at 23 ° C is 10 to 1000 µm, and a thickness of the pressure-sensitive adhesive layer is 1 to 60 µm.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein a probe tack value on the surface of the thermally expandable substrate is less than 50 mN / 5 mmφ.
The storage shear elastic modulus G ′ (23) of the pressure-sensitive adhesive layer at 23 ° C. is 1.0 × 10 4 to 1.0 × 10 8 Pa, according to any one of claims 1 to 5. Adhesive sheet.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, which has two pressure-sensitive adhesive layers on both surfaces of the thermally expandable substrate.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein the thermally expandable particles have an average particle diameter before expansion at 23 ° C of 3 to 100 µm.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 8, which is used in a sealing step involving heating using a sealing resin.
A thermally expandable base material comprising a resin and thermally expandable particles having an expansion start temperature (t) of 120 to 250 ° C., being non-tacky, and satisfying the following requirements (1) to (2):
-Requirement (1): The storage elastic modulus E '(23) of the said thermally expansible base material in 23 degreeC is 1.0 * 10 < 6 > Pa or more.
Requirement (2): The storage elastic modulus E ′ (t) of the thermally expandable substrate at the expansion start temperature (t) of the thermally expandable particles is 1.0 × 10 7 Pa or less.
A pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive sheet according to any one of claims 1 to 9, wherein the pressure-sensitive adhesive sheet is peeled off from the adherend by a heat treatment at a temperature equal to or higher than an expansion start temperature (t). how to use.
The usage method of the adhesive sheet of Claim 11 used in the sealing process with a heating using sealing resin.
The ratio of the average particle diameter of the thermally expandable particles at 23 ° C. to the thickness of the thermally expandable substrate at 23 ° C. (average particle diameter / thermally expandable substrate) is more than 0.3 and less than 1.0. The pressure-sensitive adhesive sheet according to any one of claims 1 to 9.