WO2016053966A2

WO2016053966A2 - Temperature regulation using phase change materials contained in an emi can

Info

Publication number: WO2016053966A2
Application number: PCT/US2015/052831
Authority: WO
Inventors: Amit Kulkarni; Daniel Maslyk; Mulugeta BERHE
Original assignee: Henkel IP & Holding GmbH
Priority date: 2014-09-30
Filing date: 2015-09-29
Publication date: 2016-04-07
Also published as: CN106717141A; TWI714535B; TW201622551A; WO2016053966A3; CN106717141B

Abstract

Provided herein are multicomponent shield can(s) for temporary heat storage and junction temperature regulation using a phase change material (PCM) contained therein. Invention articles can be applied to most electronic devices, especially to small portable electronic devices such as cell phones and tablets.

Description

TEMPERATURE REGULATION USING PHASE CHANGE MATERIALS

CONTAINED IN AN EMI CAN

FIELD OF THE INVENTION

[0001] The present invention relates to methods for regulating the temperature of an EMI

(electromagnetic interference)-shielded electronic component (e.g., a printed circuit board). In another aspect, the invention relates to articles useful in invention methods. In yet another aspect, the invention relates to assemblies comprising an electronic component and an invention article.

BACKGROUND OF THE INVENTION

[0002] In electronic applications, in the absence of an external heat sink, most of the heat generated by an electrical component is conducted into the printed circuit board where it spreads and is dissipated to the ambient environment.

[0003] Shielding cans are typically used in electronic devices to isolate the electrical components on a printed circuit board from radio frequency electromagnetic radiation.

Occasionally metal shield cans are also used as heat spreaders by making direct contact with the electrical component using a thermal interface pad.

[0004] Traditionally, gap pads have been used inside shield cans to improve heat sinking to the shield can in some applications. While these solutions may improve heat flow, they do not, however, provide temperature regulation due to lack of latency effect.

[0005] Cans have been directly filled with phase change materials, however the application and rework of these materials tendss to be difficult and can be messy. Also the occurrence of contamination and electrical shorting due to the presence of thermally conductive fillers may pose problems. SUMMARY OF THE INVENTION

[0006] In accordance with one aspect of the present invention, there are provided multiconiponent shield can(s) for temporary heat storage and junction temperature regulation using a phase change material (PCM). The invention articles can be applied to most electronic devices, especially to small portable electronic devices such as cell phones and tablets.

[0007] The lid of invention shielding cans provides a chamber for the PCM which may be hermetically sealed, thereby allowing the use of a wide variety of phase change materials such as waxes (e.g., paraffins (C„H₂„+₂) and fatty acids (CH₃(CH2)_2/JCOOH)), salt hydrates (e.g., EiH₂0)^a), low melting alloys, and the like, without the risk of damage to the devices embraced by the shield can due to leaks, contamination, electrical shorting, and the like.

[0008] Therefore, in accordance with one aspect of the present invention, shield cans provide the additional function of heat absorber, heat spreader and/or heat sink by allowing the lid of the shield can (which is filled with phase change material; PCM) to make direct contact with the electrical device. The lid of the multicomponent (e.g., two part shield) can design, filled with PCM, is useful as a temporary heat storage medium to regulate junction temperature of an electrical device, e.g., during small power fluctuations.

[0009] In accordance with another aspect of the current invention, there are provided assemblies comprising one or more of the above-described articles associated with a shielding can, wherein the shielding can is positioned so as to protect said component from radio frequency electromagnetic radiation and/or promote the dissipation of heat from said electronic component.

[0010] In accordance with yet another aspect of the present invention, there are provided methods to isolate electrical components on a printed circuit board from radio frequency electromagnetic radiation employing one or more articles as described herein.

[0011] Invention methods provide a solution to the problem of temporary heat storage in electronic devices; invention methods also enable temperature regulation at the junction of electrical devices comprising a printed circuit board having a component thereon. [0012] Invention methods, articles and assemblies provide numerous advantages over the art, e.g.,

- the hermetically sealed lid of the shield can provides a clean, leak free design;

- the hermetically sealed lid filled with PCM allows for the use of a wide variety of PCM materials (e.g., waxes, salt hydrates, low melting alloys, and the like) without the risk of contamination and/or electrical shorting; and

- the multipart (e.g., 2 part) shield can design, with a hermetically sealed

PCM-filled lid allows for ease of rework and trouble shooting of the PCB.

BRIEF DESCRIPTION OF THE FIGURES

[0013] Figures 1, 2 and 3 each show a cross-sectional view of an exemplary printed circuit board 10 with the electronic component 12 housed in a shield can (14, 24, 34). The shield can in each of Figures 1, 2 and 3 is a 2 part design consisting of a "wall" (16, 26, 36) and a "lid" (18, 28, 38). The lid consists of a hollow cavity 20 which can be filled with a "material" 22 such as a solid, a fluid, a phase change material, a low melting alloy, a salt hydrate, or the like, as well as any combination of any two or more thereof. The purpose of this "material" is to absorb and store heat during short power fluctuations and slowly release it over a period of time, thereby regulating the temperature of the component.

[0014] The two part shield can design allows for ease and flexibility of rework. The lid and/or the wall make good thermal contact with the component thereby enhancing heat transfer to the lid and thereby to the material filled inside the lid.

[0015] The material inside the lid is completely sealed, thereby ensuring leak free, nonmessy, clean solution.

[0016] The "heat storage and slow release over time" provides adequate junction temperature regulation of the electrical device housed inside the shield can; due to small but frequent power cycles.

[0017] Figure 4 shows the cross-sectional view of a printed circuit board with an electronic component 12 housed in an exemplary shield can 44 according to the invention. In the embodiment illustrated herein, the shield can 44 is a 2 part design consisting of a "wall" 46 and a "lid" 48. The lid itself is also a 2-part design, consisting of a hollow cavity 20 which can be filled with a "material" such as a solid, fluid, phase change material, low melting alloy, salt hydrate, or the like, or any combination of the above.

[0018] Figure 5A-5D show an exemplary three-part assembly according to the present invention. Figure 5A illustrates an exemplary "fence" 50 (also referred to in the art as a "wall") and tabs 52, which may provide for height adjustment. Figure 5B illustrates an exemplary middle pan 54, with a flange 55 all around, adapted to receive PCM thereon. Figure 5C illustrates a cross sectional view of middle pan 54 of Figure 5B and fence 50. Figure 5D illustrates an exemplary cover 56 with slots 57, which coordinates with the middle pan 54 to securely contain the PCM therein. Figure 5E illustrates a cross sectional assembly view of the cover 56 of Figure 5D, along with the middle pan 54, wall 50, tab 52.

[0019] Figure 6 shows yet another exemplary assembly according to the invention, wherein, from top-to-bottom, 68 is a lid, 64 is a cavity-forming portion of the lid, 62 is the component to be shielded, 66 is the fence or wall which defines the height of the shield can; and 60 is the printed circuit board on which the invention shield can is assembled.

DETAILED DESCRIPTION OF THE INVENTION

[0020] In accordance with the present invention, there are provided articles comprising a shielding can having:

a first cavity-forming element and a second cavity-forming element which combine to form a cavity,

wherein said cavity is adapted to securely contain therein heat absorbing material and/or thermally conductive material in paste and/or pad format, and

wherein said article is adapted to:

protect an electronic component from radio frequency electromagnetic radiation and/or

promote the dissipation of heat from said electronic component.

[0021] In some embodiments, the first cavity-foiTning element and the second cavity- forming element of the invention article combine to form the lid of said shielding can. [0022] In some embodiments, the invention article may further comprise a wall (also referred to in the art as a "fence"). Invention articles including a wall or fence may be further defined such that the first cavity-forming element and the second cavity-forming element combine to form the lid of said shielding can.

[0023] In accordance with an aspect of the present invention, EMI shielding and junction temperature regulation of the electronic component housed in the shield can is accomplished using phase change material inside a hermetically sealed lid of a 2 part shield can design as described herein.

[0024] In accordance with another aspect of the present invention, the hermetically sealed lid of the shield can provides a clean, leak-free design— which is a useful solution for temporary heat storage and junction temperature regulation.

[0025] The hermetically sealed lid filled with PCM as described herein allows for use of a variety of PCM materials such as waxes, salt hydrates and low melting alloys without the risk of contamination and/or electrical shorting.

[0026] In accordance with yet another aspect of the present invention, a 2-part shield can design with a hermetically sealed PCM filled lid allows for ease of rework and trouble shooting of the PCB.

[0027] Shield cans contemplated for use in the practice of the present invention can be made of a variety of materials, e.g., metal, thermally conductive plastic, non-conductive plastic, and the like, so long as the material provides the desired functional properties, including:

protect an electronic component from radio frequency electromagnetic radiation and/or promote the dissipation of heat from said electronic component.

[0028] A wide variety of heat absorbing materials and/or thermally conductive materials are contemplated for use in the practice of the present invention. Exemplary materials include waxes, low melting alloys, salt hydrates, thermally conductive greases, gels, pastes, pads, and the like, as well as mixtures of any two or more thereof.

[0029] In some embodiments, invention articles further comprise heat absorbing material and/or thermally conductive material in paste and/or pad format in the cavity thereof. [0030] In some embodiments, the cavity of the invention articles (especially cavities having heat absorbing material and/or thermally conductive material in paste and/or pad format in the cavity thereof) are hermetically sealed.

[0031] In accordance with another aspect of the present invention, there are provided assemblies comprising the invention articles described herein, further comprising a printed circuit board having a component adhered thereto; wherein said shielding can is positioned so as to protect said component from radio frequency electromagnetic radiation and/or promote the dissipation of heat from said electronic component.

[0032] In some embodiments, the shielding can and said component of the invention assembly make good thermal contact.

[0033] In some embodiments, the heat absorbing material and/or thermally conductive material in paste and/or pad fomiat do not come in direct contact with the electronic component of the invention assembly.

[0034] In some embodiments, the invention assembly further comprises a printed circuit board having a component adhered thereto; wherein said shielding can is positioned so as to protect said component from radio frequency electromagnetic radiation and/or promote the dissipation of heat from said electronic component.

[0035] In some embodiments, the lid and/or the wall of the shielding make good thermal contact with the electronic component of the invention assembly.

[0036] In accordance with another aspect of the present invention, there are provided methods to isolate electrical component(s) on a printed circuit board from radio frequency electromagnetic radiation, said method comprising positioning an invention article as described herein about said component.

[0037] In accordance with yet another aspect of the present invention, there are provided methods to regulate the junction temperature of an electrical device comprising a printed circuit board having a component thereon, said method comprising positioning an invention article as described herein about said component. [0038] In some embodiments, said temperature regulation occurs during small power fluctuations.

[0039] In accordance with another aspect of the present invention, there are provided methods for the temporary storage of heat in an electronic device, said methods comprising positioning an invention article as describer herein about said device.

[0040] In accordance with still another aspect of the present invention, there are provided methods for the efficient conduction of heat from an electronic device, said methods comprising positioning an invention article as described herein about said device.

[0041] Various aspects of the present invention are illustrated by the following non- limiting examples. The examples are for illustrative purposes and are not a limitation on any practice of the present invention. It will be understood that variations and modifications can be made without departing from the spirit and scope of the invention. One of ordinary skill in the art readily knows how to synthesize or commercially obtain the reagents and components described herein.

EXAMPLE 1

[0042] The temperature change undergone by a printed circuit board having a prior art shield can thereon was measured in the presence and absence of added phase change material.

[0043] It was observed that the presence of phase change material provided a several degree moderation of the temperature of the printed circuit board.

EXAMPLE 2

[0044] The same protocol as Example 1 was repeated with a shield can of the present invention.

[0045] It was observed that the use of phase change material in the invention article provided nearly double the temperature moderation than observed in Example 1.

[0046] Various modifications of the present invention, in addition to those shown and described herein, will be apparent to those skilled in the art of the above description. Such modifications are also intended to fall within the scope of the appended claims. [0047] Patents and publications mentioned in the specification are indicative of the levels of those skilled in the art to which the invention pertains. These patents and publications are incorporated herein by reference to the same extent as if each individual application or publication was specifically and individually incorporated herein by reference.

[0048] The foregoing description is illustrative of particular embodiments of the invention, but is not meant to be a limitation upon the practice thereof. The following claims, including all equivalents thereof, are intended to define the scope of the invention.

Claims

That which is claimed is:

1. An article comprising a shielding can having:

wherein said article is adapted to:

promote the dissipation of heat from said electronic component.

2. The article of claim 1 wherein said shielding can further comprises a wall or a fence.

3. The article of claim 2, wherein said first cavity-forming element and said second cavity-forming element combine to form the lid of said shielding can.

4. The article of claim 1, wherein said first cavity-forming element and said second cavity- forming element combine to form the lid of said shielding can.

5. The article of claim 1, wherein said heat absorbing material and/or thermally conductive material is selected from a wax, a low melting alloy, a salt hydrate, a thermally conductive grease, a gel, a paste, a pad, as well as mixtures of any two or more thereof.

6. The article of claim 1, further comprising heat absorbing material and/or thermally conductive material in paste and/or pad format in the cavity thereof.

7. The article of claim 6, wherein said cavity is hermetically sealed.

8. An assembly comprising the article of claim 1, further comprising a printed circuit board having a component adhered thereto; wherein said shielding can is positioned so as to protect said component from radio frequency electromagnetic radiation and/or promote the dissipation of heat from said electronic component.

9. The assembly of claim 8, wherein the shielding can and said component make good thermal contact.

10. The assembly of claim 9, wherein the heat absorbing material and/or thermally conductive material in paste and/or pad format does not come in direct contact with said electronic component.

11. An assembly comprising the article of claim 3, further comprising a printed circuit board having a component adhered thereto; wherein said shielding can is positioned so as to protect said component from radio frequency electromagnetic radiation and/or promote the dissipation of heat from said electronic component.

12. The assembly of claim 11, wherein the lid and/or the wall of the shielding can make good thermal contact with the component.

13. A method to isolate an electrical component on a printed circuit board from radio frequency electromagnetic radiation, said method comprising positioning an article according to claim 1 about said component.

14. A method to regulate junction temperature of an electrical device comprising a printed circuit board having a component thereon, said method comprising positioning an article according to claim 1 about said component.

15. The method of claim 14, wherein said regulation occurs during small power fluctuations.

16. A method for the temporary storage of heat in an electronic device, said method comprising positioning an article according to claim 1 about said device.

17. A method for the efficient conduction of heat from an electronic device, said method comprising positioning an article according to claim 6 about said device.