WO2023037747A1 - Mounting structure - Google Patents

Abstract

The present invention provides an electronic component comprising a component body and an external electrode provided on a surface of the component body, characterized in that the external electrode comprises an Ni/Cu/Sn stacked structure.

Description

implementation structure

The present disclosure relates to an electronic component and a mounting structure including the electronic component.

In general, an electronic component includes a component body and external electrodes provided on the surface thereof. (A joint formed by soldering is also referred to herein as a “solder joint”). For example, Patent Document 1 discloses a laminated ceramic capacitor having terminal electrodes (external electrodes) at the ends of a laminate (component body) formed from internal electrode layers and dielectric layers, wherein the terminal electrodes are Ag-based conductor films. (base film), a Ni-plated intermediate layer, and an external plated layer (Sn-plated layer). In Patent Document 1, by setting the thickness of the Ni-plated intermediate layer to a predetermined thickness or more and reducing the variation thereof, it is possible to effectively prevent the solder erosion of the Ag-based conductor film that may occur during soldering. It is disclosed that an excellent terminal electrode can be formed at a temperature of 270° C. for 10 seconds, for example.

JP-A-6-196351

A mounting structure in which electronic components are mounted on a substrate is required to withstand use in even harsher temperature environments, such as when used in electronic fuel injection control circuits in automobile engine compartments. ing. When the mounting structure is used in such a severe high-temperature environment, Ni contained in the Ni-plated intermediate layer can diffuse (thermally diffuse) into the solder joints at a relatively high speed in the configuration of Patent Document 1. As a result, Ag from the Ag-based conductor film (base film) can also diffuse into the solder joint. "Solder erosion", in which Ag is lost from the Ag-based conductor film due to diffusion into the solder joint, can also occur during use of the mounting structure, resulting in damage between the main body of the electronic component and the Ag-based conductor film. The connection between them may become insufficient, and the connection reliability of the electronic components may deteriorate.

The present disclosure aims to provide an electronic component that can effectively suppress the diffusion of metal atoms from external electrodes to solder or solder joints even when exposed to a high-temperature environment after mounting the electronic component. aim. A further object of the present disclosure is to provide a mounting structure on which such electronic components are mounted.

The present disclosure includes the following aspects.
[1] a component body;
An electronic component comprising an external electrode provided on the surface of the component body,
The external electrode includes a laminated structure of M ¹ /Cu/antioxidation film,
The M ¹ is a Group 9-11 metal or an alloy containing a Group 9-11 metal,
electronic components.
[2] The electronic component according to [1] above, wherein the ^M1 is Ni or an alloy containing Ni.
[3] The electronic component according to [1] or [2] above, wherein ^M1 is Ni.
[4] The electronic component according to any one of [1] to [3] above, wherein the antioxidant film is a layer of Sn, Ag, Au, or OSP.
[5] The electronic component according to any one of [1] to [4] above, wherein the antioxidant film is a Sn layer.
[6] The electronic component according to any one of [1] to [5] above, wherein the Cu layer has a thickness of 0.1 μm or more and 10 μm or less.
[7] The electronic component according to any one of [1] to [6] above, wherein the Cu layer has a thickness of 0.3 μm or more and 5 μm or less.
[8] An electronic component comprising a component body and an external electrode provided on the surface of the component body;
A mounting structure comprising a solder joint,
The electronic component is joined to another electronic component by a solder joint,
The external electrode has an intermetallic compound layer represented by (Cu, M ² ) _x Sn _y or Cu _x Sn _y at the interface with the solder joint,
said M ² is a metal of Groups 9 to 11;
The x is 5 or more and 7 or less,
The y is 4 or more and 6 or less,
Structural implementation.
[9] the external electrode includes a laminated structure of M ¹ /(Cu, M ² ) _x Sn _y or M ¹ /Cu _x Sn _y ,
The M ¹ is a metal of Groups 9 to 11 or an alloy containing metals of Groups 9 to 11,
said M ² is a metal of Groups 9 to 11;
The x is 5 or more and 7 or less,
The y is 4 or more and 6 or less,
The mounting structure according to [8] above.
[10] The external electrode includes a laminated structure of M ¹ /Cu/(Cu, M ² ) _x Sn _y or M ¹ /Cu/Cu _x Sn _y ,
The M ¹ is a Group 9 to Group 11 metal or an alloy containing a Group 9 to Group 11 metal,
said M ² is a metal of Groups 9 to 11;
The x is 5 or more and 7 or less,
The y is 4 or more and 6 or less,
The mounting structure according to [8] above.
[ ¹¹ _] ^The _{above -} ^mentioned _[ 10].
[12] The mounting structure according to any one of [9] to [11] above, wherein ^M1 is Ni or an alloy containing Ni ^, and M2 is Ni.
[13] Any one of the above [8] to [12], wherein the coverage of the (Cu, M ² ) _x Sn _y layer or the Cu _x Sn _y layer with respect to the lower layer is 50% or more and 100% or less. The implementation struct described in .
[14] The mounting structure according to any one of [8] to [13] above, wherein the (Cu, M ² ) _x Sn _y layer or the Cu _x Sn _y layer has a thickness of 0.1 μm or more. .
[15] The mounting structure according to any one of [8] to [14] above, wherein x+y is 10 or more and 12 or less.
[16] The mounting structure according to any one of [8] to [15] above, wherein x is 6 and y is 5.

According to the present disclosure, it is possible to provide an electronic component that can effectively suppress diffusion of metal atoms from external electrodes to solder joints even when exposed to a high-temperature environment after mounting the electronic component.

FIG. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor 1a that is one embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view of a mounting structure 21 that is one embodiment of the present disclosure.

The electronic component and mounting structure of the present disclosure will be described in detail below with reference to the drawings. However, the shape, arrangement, etc. of the electronic component and the mounting structure of each embodiment are not limited to the illustrated example.

The electronic component of the present disclosure is
a component body;
An electronic component comprising an external electrode provided on the surface of the component body,
The external electrode includes a laminated structure of M ¹ /Cu/antioxidation film. Here, M ¹ is a group 9-11 metal or an alloy containing a group 9-11 metal.

In this embodiment, the electronic component of the present disclosure can be the multilayer ceramic capacitor 1a shown in FIG. A multilayer ceramic capacitor 1a has a component body 2 and external electrodes 3a and 3b provided on the surface of the component body. The component body 2 has internal electrodes 5 a and 5 b and a dielectric portion (dielectric layer) 6 . The external electrodes 3a and 3b are respectively composed of base layers 11a and 11b, ^M1 layers 12a and 12b, Cu layers 13a and 13b, and antioxidant films 14a and 14b.

The electronic component of the present disclosure includes a laminate structure of M ¹ /Cu/antioxidation film in the external electrode. With such a laminated structure, when the electronic component of the present disclosure is mounted on another electronic component by soldering, intermetallic intermetallics derived from the laminated structure of the M ¹ /Cu/antioxidation film are formed at the interface between the external electrode and the solder joint. A compound layer is formed. Such an intermetallic compound layer can function as a barrier film against solder erosion, and can function as a barrier film for a long period of time, particularly during use at high temperatures, thereby increasing reliability.

Although the component body 2 is the body of the capacitor in this embodiment, it is not limited to this as long as external electrodes are provided on its surface. For example, the component body can include electronic component bodies that can be used as inductors, resistors, LC composite components, and the like.

The component main body is not particularly limited, and can be configured using a commonly used method.

The material of the main part is not particularly limited, and commonly used materials can be used. Examples of materials include ceramics, resins, metals, composites thereof, and more specifically, ceramics.

Although the multilayer ceramic capacitor 1a shown in FIG. 1 has two external electrodes, the electronic component of the present disclosure is not limited to this aspect, and three or more external electrodes can be provided.

As shown in FIG. 1, the external electrodes 3a and 3b are respectively composed of underlying layers 11a and 11b, ^M1 layers 12a and 12b, Cu layers 13a and 13b, and antioxidant films 14a and 14b. That is, the external electrode includes a laminated structure of M ¹ /Cu/antioxidation film on the base layer.

Although the underlayer is not particularly limited, it may be Cu, Ag, Ni, Pd, or an alloy layer thereof. The underlayer may preferably be a layer of Cu or Ag, more preferably Cu. The underlayer may be a single layer or two or more layers.

The underlayer may contain other materials such as glass.

The base layer is provided on the surface of the component body, preferably in contact with the component body.

The thickness of the underlayer is not particularly limited, and may be, for example, 1 μm or more and 500 μm or less, preferably 3 μm or more and 300 μm or less, more preferably 5 μm or more and 100 μm or less, for example 5 μm or more and 50 μm or less, or 10 μm or more and 30 μm or less. obtain.

The method of forming the underlayer is not particularly limited, and examples thereof include plating (eg, electrolytic plating or electroless plating), sputtering, applying a paste, and curing or baking.

The ^M1 layer is provided on the underlayer.

M ¹ is a group 9-11 metal or an alloy containing a group 9-11 metal.

In one aspect, M ¹ is Ni or an alloy containing Ni.

Said alloy is preferably selected from the group consisting of Ni and Zn, W, Re, Os, Mo, Nb, Ir, Ru, Rh, Cr, Pt, Ti, Lu, Pd, Fe, Cu and Co It is an alloy with one or more metals.

In preferred embodiments, M ¹ is Ni.

The thickness of the ^M1 layer is not particularly limited. It can be 3 μm or less or 1 μm or more and 5 μm or less.

The method of forming the ^M1 layer is not particularly limited, but examples thereof include plating (eg, electrolytic plating or electroless plating), sputtering, and the like.

The thickness of the Cu layer is preferably 0.1 μm or more and 10 μm or less, more preferably 0.2 μm or more and 8 μm or less, and still more preferably 0.3 μm or more and 5.0 μm or less. By setting the thickness of the Cu layer to 0.3 μm or more, the following (Cu,M ² ) _x Sn _y Alternatively, a layer of Cu _x Sn _y is formed, and solder erosion can be suppressed more reliably. Further, by setting the thickness of the Cu layer to 10 μm or less, miniaturization is facilitated. By setting the thickness of the Cu layer to 0.1 μm or more, it becomes easy to form a uniform layer of (Cu, M ² ) _x Sn _y or Cu _x Sn _y , and the effect of suppressing solder erosion is large. Become. It is considered that this is because Cu in the solder is also supplied to the interface if the thickness of the Cu layer is 0.1 μm or more.

The method of forming the Cu layer is not particularly limited, but examples thereof include plating (eg, electrolytic plating or electroless plating), sputtering, and the like.

The antioxidant film is preferably a layer of Sn, Ag, Au, or OSP (Organic Solderability Preservative, that is, water-soluble preflux).

The anti-oxidation film is preferably a layer of Sn, Ag or Au, more preferably an Sn layer.

The thickness of the antioxidant film is not particularly limited, and may be, for example, 0.01 μm or more and 100 μm or less, preferably 0.1 μm or more and 50 μm or less, more preferably 0.3 μm or more and 10 μm or less, for example 0.3 μm or more. It can be 3 μm or less or 1 μm or more and 5 μm or less.

The method for forming the anti-oxidation film is not particularly limited, but examples thereof include plating (eg, electrolytic plating or electroless plating), sputtering, and the like.

The thickness of the laminated structure of M ¹ /Cu/antioxidation film is preferably 1.0 μm or more and 300 μm or less, more preferably 5.0 μm or more and 100 μm or less.

The ^M1 layer, the Cu layer, and the anti-oxidation film may each contain other trace substances such as trace atoms that may be unavoidably mixed.

The M ¹ /Cu/antioxidation film is preferably Ni/Cu/Sn.

The electronic component of the present disclosure described above can be mounted on another electronic component using solder, thereby obtaining a mounted structure. The present disclosure also provides mounting structures that include the electronic components of the present disclosure and solder joints.

The implementation structure of the present disclosure is:
an electronic component comprising a component body and external electrodes provided on the surface of the component body;
A mounting structure comprising a solder joint,
The electronic component is joined to another electronic component by a solder joint,
The external electrode has an intermetallic compound layer represented by (Cu, M ² ) _x Sn _y or Cu _x Sn _y at the interface with the solder joint. Here, M ² is a group 9 to group 11 metal, x is 5 or more and 7 or less, and y is 4 or more and 6 or less.

In this embodiment, the mounting structure of the present disclosure can be the mounting structure 21 shown in FIG. The mounting structure 21 includes a laminated ceramic capacitor 1b and solder joints 22a and 22b. The multilayer ceramic capacitor 1b of the mounting structure 21 is soldered to a substrate 23, which is another electronic component. The laminated ceramic capacitor 1b is obtained by soldering the laminated ceramic capacitor 1a to a substrate 23, and is the same as the electronic component described above except that the external electrodes 3a and 3b are changed to external electrodes 3c and 3d. has a configuration of

In the present embodiment, the other electronic component is the substrate 23, but it is not limited to this, and is not particularly limited as long as it is an electronic component that can be soldered to the electronic component of the present disclosure.

The solder joints 22a and 22b are for joining the substrate 23 and the multilayer ceramic capacitor 1, and specifically, the electrode portions 24a and 24b provided on the surface of the substrate 23 and the external electrodes of the multilayer ceramic capacitor 1b. 3c and 3d are joined.

The electrodes 24a and 24b provided on the surface of the substrate are not particularly limited, and commonly used ones can be used. The electrode portion can be formed of, for example, a conductive material such as Ni, Cu, Ag, Sn, Au, Pd, and, in some cases, preflux or the like.

The solder joints can be formed by a general method, for example, by using solder paste and reflowing.

In this embodiment, solder is not particularly limited, and commonly used solder can be used. Solders include, for example, Sn—Ag—Cu alloy (SAC), Sn—Zn—Bi alloy, Sn—Cu alloy, Sn—Ag—In—Bi alloy, Sn—Zn—Al alloy, Sn A -Sb alloy or the like can be used.

In a preferred embodiment, the solder is SAC.

The external electrodes 3c and _3d have an intermetallic compound layer represented _by (Cu, ^M2 ) _xSny or _CuxSny at the interface with the solder joint. The presence of such an intermetallic compound layer can suppress the diffusion of metal atoms from the external electrode to the solder joint, that is, the solder erosion.

The intermetallic compound layer exists over the entire interface between the external electrode and the solder joint. The presence of the intermetallic compound layer over the entire interface between the external electrode and the solder joint can more reliably suppress the diffusion of metal atoms from the external electrode to the solder joint.

The external electrode in the mounting structure has _a laminated structure _of ^M1 /(Cu, ^M2 ) _{xSny or CuxSny} , or ^M1 /Cu/(Cu, ^M2 ) _{xSny or CuxSny} . including.

The above M ¹ has the same meaning as above, and is a group 9-11 metal or an alloy containing a group 9-11 metal.

^M2 is a group 9-11 metal.

In a preferred embodiment, ^M2 is Ni.

The above x is 5 or more and 7 or less, and the above y is 4 or more and 6 or less.

In one aspect, x is 5.5 or more and 6.5 or less, and y is 4.5 or more and 5.5 or less.

x+y is preferably 10 or more and 12 or less, more preferably 10.5 or more and 11.5 or less.

In a preferred embodiment, x is 6 and y is 5.

The laminated structure of M ¹ /(Cu, M ² ) _x Sn _y or Cu _x Sn _y and M ¹ /Cu/(Cu, M ² ) _x Sn _y or Cu _x Sn _y is the laminated ceramic capacitor 1a described above. Sn in the M ¹ /Cu/antioxidant film and Sn in the solder are formed by forming an intermetallic compound when soldering to the substrate 23 .

The content of M ² in (Cu, M ² ) _x Sn _y is preferably 0.01 at % or more and 25 at % or less, more preferably 0.1 at % or more and 20 at % or less.

The thickness of the ^M1 layer may be preferably 0.1 μm to 10 μm, more preferably 0.5 μm to 8 μm.

The thickness of the Cu layer, if present, may preferably be 0.1 μm or more and 5 μm or less, more preferably 0.3 μm or more and 3 μm or less.

The thickness of the (Cu, M ² ) _x Sn _y or Cu _x Sn _y layer may preferably be 0.01 μm or more and 20 μm or less. By setting the thickness of the (Cu, M ² ) _x Sn _y layer or the Cu _x Sn _y layer to 0.01 μm or more, the diffusion of metal atoms from the external electrode to the solder joint can be suppressed more reliably. By setting the thickness of the (Cu, M ² ) _x Sn _y or Cu _x Sn _y layer to 20 μm or less, the mounting structure can be further miniaturized.

The electronic component and mounting structure of the present disclosure will be specifically described below using examples, but the electronic component and mounting structure of the present disclosure are not limited to these examples.

Examples 1-3
(Production of electronic parts)
A chip-shaped ceramic laminate was immersed in a paste in which Cu powder and glass were mixed, and then lifted out to adhere the paste. After that, it was fired at 800° C. to form a composite layer containing Cu and glass as a base layer on the surface of the ceramic laminate. Next, a Ni layer, a Cu layer, and an Sn layer were formed on the underlayer by a sputtering method to obtain samples of Examples 1-3. Table 1 shows the thickness of each layer.

Comparative example 1
A sample of Comparative Example 1 was obtained in the same manner as in Examples 1 to 3 above, except that the Cu layer was not formed between the Ni layer and the Sn layer.

Examples 4-6
(Fabrication of mounting structure)
The samples of Examples 1 to 3 were reflow-mounted on a printed circuit board using SAC solder to obtain mounting structures of Examples 4 to 6. Reflow was performed at a preheating temperature of 150° C. for 60 seconds and then at a maximum temperature of 250° C. for 100 seconds.

Comparative example 2
The sample of Comparative Example 1 was reflow-mounted on a printed circuit board using SAC solder to obtain a mounted structure of Comparative Example 2.

Test example 1
Regarding the mounting structures of Examples 4 to 6 and Comparative Example 2, the cross section of the external electrode was examined with a scanning electron microscope (FE-SEM/EDX) (manufactured by Hitachi High-Technologies Corporation, FE-SEM: SU8230/EDX: 5060FQ). Observed.

As for the mounting structures of Examples 4 to 6, it was confirmed that the external electrodes had a Ni/(Cu, Ni) ₆ Sn ₅ layer formed on the underlying layer. On the other hand, for the sample of Comparative Example 2, it was confirmed that a Ni/Ni ₃ Sn ₄ /(Cu,Ni) ₆ Sn ₅ layer was formed on the underlayer.

Test Example 2 (heat resistance test)
The mounting structures obtained in Examples 4 to 6 and Comparative Example 2 were allowed to stand in an environment at a temperature of 175° C., and observed for the occurrence of solder leaching. The presence or absence of solder leaching was determined by observing the cross section of the external electrode with a scanning electron microscope (FE-SEM/EDX) (manufactured by Hitachi High-Technologies Corporation, FE-SEM: SU8230/EDX: 5060FQ). . Also, the reaction rate constant for solder erosion was calculated from the difference between the initial film thickness and the film thickness after standing at 175°C. The results are shown in the table below.

No solder erosion was observed in the mounting structures of Examples 4 to 6 even after 500 hours had passed. On the other hand, it was confirmed that the mounting structure of Comparative Example 2 had localized solder erosion.

The electronic component of the present disclosure is suitably used in applications that require use at high temperatures.

DESCRIPTION OF SYMBOLS 1a, 1b... Laminated ceramic capacitor 2... Component body 3a, 3b... External electrode 3c, 3d... External electrode 5a, 5b... Internal electrode 6... Dielectric part (dielectric layer)
DESCRIPTION OF SYMBOLS 11a, 11b... Base layer 12a, 12b... M ¹ layer 13a, 13b... Cu layer 14a, 14b... Antioxidation film 21... Mounting structure 22a, 22b... Solder joint part 23... Substrate 24a, 24b... Electrode part

Claims (16)

a component body;
An electronic component comprising an external electrode provided on the surface of the component body,
The external electrode includes a laminated structure of M ¹ /Cu/antioxidation film,
The M ¹ is a Group 9-11 metal or an alloy containing a Group 9-11 metal,
electronic components. The electronic component according to claim ¹ , wherein the M1 is Ni or an alloy containing Ni. The electronic component according to claim 1 or 2, wherein said ^M1 is Ni. The electronic component according to any one of claims 1 to 3, wherein the antioxidant film is a layer of Sn, Ag, Au, or OSP. The electronic component according to any one of claims 1 to 4, wherein the antioxidant film is a Sn layer. The electronic component according to any one of claims 1 to 5, wherein the Cu layer has a thickness of 0.1 µm or more and 10 µm or less. The electronic component according to any one of claims 1 to 6, wherein the Cu layer has a thickness of 0.3 µm or more and 5 µm or less. an electronic component comprising a component body and external electrodes provided on the surface of the component body;
A mounting structure comprising a solder joint,
The electronic component is joined to another electronic component by a solder joint,
The external electrode has an intermetallic compound layer represented by (Cu, M ² ) _x Sn _y or Cu _x Sn _y at the interface with the solder joint,
said M ² is a metal of Groups 9 to 11;
The x is 5 or more and 7 or less,
The y is 4 or more and 6 or less,
Structural implementation. the external electrode includes a laminated structure of M ¹ /(Cu, M ² ) _x Sn _y or M ¹ /Cu _x Sn _y ,
The M ¹ is a metal of Groups 9 to 11 or an alloy containing metals of Groups 9 to 11,
said M ² is a metal of Groups 9 to 11;
The x is 5 or more and 7 or less,
The y is 4 or more and 6 or less,
The mounting structure according to claim 8. the external electrode includes a laminated structure of M ¹ /Cu/(Cu, M ² ) _x Sn _y or M ¹ /Cu/Cu _x Sn _y ,
The M ¹ is a metal of Groups 9 to 11 or an alloy containing metals of Groups 9 to 11,
said M ² is a metal of Groups 9 to 11;
The x is 5 or more and 7 or less,
The y is 4 or more and 6 or less,
The mounting structure according to claim 8. 11. The thickness of the Cu layer in _the stacked structure of ^M1 /Cu/(Cu, ^M2 ) _xSny or ^M1 /Cu/ _{CuxSny is} 0.1 [mu]m or more and 5 [mu]m or less, according to claim 10. The implementation struct of . The mounting structure according to any one of claims 8 to 11, wherein said M ¹ is Ni or an alloy containing Ni, and said M ² is Ni. The mounting structure according to any one of claims 8 to 12, wherein the (Cu, M ² ) _x Sn _y layer or the Cu _x Sn _y layer has a coverage rate of 50% or more and 100% or less with respect to the lower layer. . The mounting structure according to any one of claims 8 to 13, wherein the (Cu, M ² ) _x Sn _y layer or the Cu _x Sn _y layer has a thickness of 0.1 µm or more. The mounting structure according to any one of claims 8 to 14, wherein x+y is 10 or more and 12 or less. The mounting structure according to any one of claims 8 to 15, wherein x is 6 and y is 5.

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