US20180259271A1

US20180259271A1 - Thermal interface structure resilient to shearing forces

Info

Publication number: US20180259271A1
Application number: US15/456,360
Authority: US
Inventors: Xiaoning Wu
Original assignee: Jones Tech (usa) Inc
Current assignee: Jones Tech (usa) Inc
Priority date: 2017-03-10
Filing date: 2017-03-10
Publication date: 2018-09-13

Abstract

Providing a thermal interface structure can include: forming a thermal interface material for thermally coupling a heat-generating structure to a heat-dissipating structure such that the thermal interface material capable of enduring a repeated shearing force caused by sliding the heat-generating structure against the heat-dissipating structure; and forming an adhesive material for holding the thermal interface material in place on the heat-dissipating structure.

Description

BACKGROUND

A thermal interface material may be used to thermally couple a heat-generating component to a heat-dissipating component. For example, a thermal interface material may be used to thermally couple an electronics module to a heat sink.
A thermal interface material can be subjected to shearing forces during normal operation. For example, a removable electronics module can impart shearing forces on a thermal interface material of a heat sink as the removable electronics module is repeatedly installed and removed from contact with the heat sink. The shearing forces can damage the thermal interface material, create air gaps, reduce the thermal transfer efficiency of the thermal interface material, and cause failures in electronic systems.

SUMMARY

In general, in one aspect, the invention relates to a thermal interface structure. The thermal interface structure can include: a thermal interface material for thermally coupling a heat-generating structure to a heat-dissipating structure while enduring a repeated shearing force caused by sliding the heat-generating structure against the heat-dissipating structure; and an adhesive material for holding the thermal interface material in place on the heat-dissipating structure.
In general, in another aspect, the invention relates to a method for providing a thermal interface structure. The method can include: forming a thermal interface material for thermally coupling a heat-generating structure to a heat-dissipating structure such that the thermal interface material is capable of enduring a repeated shearing force caused by sliding the heat-generating structure against the heat-dissipating structure; and forming an adhesive material for holding the thermal interface material in place on the heat-dissipating structure.
Other aspects of the invention will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements.

FIGS. 1A-1D illustrate a variety of embodiments of a thermal interface structure resilient to shearing forces.

FIG. 2 illustrates an application of the thermal interface structure of FIG. 1A in system in which it is subject to repeated shearing forces.

FIG. 3 illustrates an application of the thermal interface structure of FIG. 1B in system in which it is subject to repeated shearing forces.

FIG. 4 illustrates an application of the thermal interface structure of FIG. 1C in system in which it is subject to repeated shearing forces.

FIG. 5 illustrates an application of the thermal interface structure of FIG. 1D in system in which it is subject to repeated shearing forces.

FIG. 6 illustrates a method for providing a thermal interface structure in one or more embodiments.

DETAILED DESCRIPTION

Reference will now be made in detail to the various embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Like elements in the various figures are denoted by like reference numerals for consistency. While described in conjunction with these embodiments, it will be understood that they are not intended to limit the disclosure to these embodiments. On the contrary, the disclosure is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the disclosure as defined by the appended claims. Furthermore, in the following detailed description of the present disclosure, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be understood that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, components, have not been described in detail so as not to unnecessarily obscure aspects of the present disclosure.
FIG. 1A illustrates a thermal interface structure 10 in one or more embodiments. The thermal interface structure 10 includes a thermal interface material 12 for thermally coupling a heat-generating structure to a heat-dissipating structure. The thermal interface material 12 is capable of enduring a repeated shearing force caused by sliding a heat-generating structure against a heat-dissipating structure. The thermal interface structure 10 includes an adhesive material 14 for holding the thermal interface material 12 in place on a heat-dissipating structure.
In one or more embodiments, the thermal interface material 12 is a foam-like synthetic graphite. The thermal interface material 12 can be a foam-like graphite film with a low density. The thermal interface material 12 can be a single layer of foam-like graphite film. The thermal interface material 12 can include multiple layers of foam-like graphite films stacked.
The thermal interface material 12 can be a synthetic graphite that is converted by a polymer film after high temperature treatment. The polymer film for heat treatment can be selected from one or combination of polymide (PI), polybenzoxazole (PBO) polybenzobisoxazole (PBBO), polybenzothiazole (PBT), polybenzobisthiazole (PBBT), polyamide (PA), etc.
In one or more embodiments, the thermal interface material 12 has compression ratio of between 30 and 80 percent. The thermal interface material 12 provides low thermal resistance by filling an air gap between a heat-generating structure and a heat-dissipating structure.
In one or more embodiments, the thermal interface material 12 is 200 micrometers thick. The thermal interface material 12 can have a density of less than 0.5 grams per cubic centimeter and be compressible.
In one or more embodiments, the adhesive material 14 is a pressure-sensitive adhesive. The adhesive material 14 can be an acrylic-based pressure sensitive adhesive. The adhesive material 14 can be a silicone rubber-based pressure-sensitive adhesive. The adhesive material 14 can be a combination of acrylic-based and silicone rubber-based pressure-sensitive adhesives.
In one or more embodiments, the adhesive material 14 is a hot-melt adhesive. The adhesive material 14 can be a combination of a pressure sensitive adhesive and a hot-melt adhesive.
In one or more embodiments, the adhesive material 14 is selected to provide a balance between a thermal performance and a mechanical bonding performance. For example, the adhesive material 14 can be a non-thermally conductive adhesive that increases mechanical bonding performance or a thermally conductive adhesive that increases thermal coupling performance.
In the embodiment of FIG. 1A, the adhesive material 14 substantially covers an entire surface area of the thermal interface material 12. In one or more embodiments, the adhesive material 14 is 5 micrometers thick.
FIG. 1B illustrates an embodiment of the thermal interface structure 10 in which the adhesive material 14 covers only a portion of the surface area of the thermal interface material 12 as indicated by the adhesive areas 14 a-14 c. In one or more embodiments, the adhesive area 14 b corresponds to a contact area between a heat-generating structure and a heat-dissipating structure.
FIG. 1C illustrates an embodiment of the thermal interface structure 10 that includes a plastic film 16 a-16 b for protecting the thermal interface material 12 from repeated shearing forces. In one or more embodiments, the plastic film 16 a-16 b covers only portions of the thermal interface material 12 that are substantially outside of a contact area between a heat-generating structure and a heat-dissipating structure.
The plastic film 16 a-16 b can include a plastic or a metal film. For example, the plastic film 16 a-16 b can include a polyimide tape, a polyethylene terephthalate (PET) tape, etc. The plastic film 16 a-16 b can include a pressure sensitive adhesive, e.g., an acrylic-based pressure sensitive adhesive, a silicone-based pressure sensitive adhesive, etc. In one or more embodiments, the plastic film 16 a-16 b is 10 micrometers thick.
FIG. 1D illustrates an embodiment of the thermal interface structure 10 in which the adhesive areas 14 a-14 c cover only a portion of the surface area of the thermal interface material 12 and which includes the plastic film 16 a-16 b covering only portions of the thermal interface material 12 that are substantially outside of a contact area between a heat-generating structure and a heat-dissipating structure.
FIG. 2 illustrates an application in which the thermal interface structure 10 of FIG. 1A is positioned on a beveled lead-in 24 of a heat-dissipating structure 22. The beveled lead-in 24 facilitates repeated coupling and decoupling of a heat-generating structure 20 to and from the heat-dissipating structure 22 by the application of shearing forces to the heat-generating structure 20. The thermal interface structure 10 yields low thermal resistance between the heat-dissipating structure 22 and the heat-generating structure 20 by filling air gaps between the heat-dissipating structure 22 and the heat-generating structure 20.
For example, the heat-generating structure 20 can be a removable electronics component that can be repeatedly inserted and removed from a connector housing and the heat-dissipating structure 22 can be a riding-high heat sink in the connector housing. The thermal interface material 12 is capable of enduring repeated shearing forces caused by sliding the heat-generating structure 20 against the heat-dissipating structure 22 while a pressing force is applied to the heat-dissipating structure 22.
FIG. 3 illustrates an application in which the thermal interface structure 10 of FIG. 1B is positioned on the heat-dissipating structure 22 so that the adhesive area 14 b is positioned at a contact area between the heat-generating structure 20 and the heat-dissipating structure 22. The compressive nature of the thermal interface material 12 enables it to make contact with the heat-dissipating structure 22 between the adhesive areas 14 a-14 c.
FIG. 4 illustrates an application in which the thermal interface structure 10 of FIG. 1C is positioned on the heat-dissipating structure 22 so that the thermal interface material 12 can make contact with the heat-generating structure 20 between the plastic film 16 a-16 b.
FIG. 5 illustrates an application in which the thermal interface structure 10 of FIG. 1D is positioned on the heat-dissipating structure 22 so that the thermal interface material 12 can make contact with the heat-generating structure 20 between the plastic film 16 a-16 b and the thermal interface material 12 can make contact with the heat-dissipating structure 22 between the adhesive areas 14 a-14 c.
In one or more embodiments, the thermal interface structure 10 can be employed in a high speed, e.g., 100 Gbps, data communication system, e.g., for telecommunications, in which the heat-dissipating structure 22 is part of a pluggable interface for a network device motherboard that receives a fiber optic networking cable. Smaller 100 Gbps modules, e.g., CFP, CFP2, CXP, QSFP28, etc., can have a power density from approximately 0.1 watt per square centimeter (W/cm²) to 0.3 or 0.5 W/cm². The thermal interface structure 10 can help maintain case temperature limits in such applications.
In one or more embodiments, the thermal interface structure 10 can resist shearing forces and survive more than 50 cycles of sliding-in and sliding-out of the heat-generating structure 20.
In one or more embodiments, it may be desirable to minimize the thickness of the adhesive material 14 while still maintaining its effectiveness.
FIG. 6 illustrates a method for providing a thermal interface structure in one or more embodiments. While the various steps in this flowchart are presented and described sequentially, one of ordinary skill will appreciate that some or all of the steps can be executed in different orders and some or all of the steps can be executed in parallel. Further, in one or more embodiments, one or more of the steps described below can be omitted, repeated, and/or performed in a different order. Accordingly, the specific arrangement of steps shown in FIG. 6 should not be construed as limiting the scope of the invention.
At step 610, a thermal interface material is formed for thermally coupling a heat-generating structure to a heat-dissipating structure such that the thermal interface material capable of enduring a repeated shearing force caused by sliding the heat-generating structure against the heat-dissipating structure. Forming a thermal interface material can include forming the thermal interface material on a beveled lead-in of a heat-dissipating structure. Forming a thermal interface material can include forming a foam-like synthetic graphite.
At step 620, an adhesive material is formed for holding the thermal interface material in place on the heat-dissipating structure. Forming an adhesive material can include forming a pressure-sensitive adhesive. Forming an adhesive material can include forming a hot-melt material. Forming an adhesive material can include selecting a balance between a thermal performance and a mechanical bonding performance of the thermal interface structure. Forming an adhesive material can include covering an entire surface of a thermal interface material or only a portion of the thermal interface material corresponding to a contact area between a heat-generating structure and a heat-dissipating structure.
While the foregoing disclosure sets forth various embodiments using specific diagrams, flowcharts, and examples, each diagram component, flowchart step, operation, and/or component described and/or illustrated herein may be implemented, individually and/or collectively, using a range of processes and components.
The process parameters and sequence of steps described and/or illustrated herein are given by way of example only. For example, while the steps illustrated and/or described herein may be shown or discussed in a particular order, these steps do not necessarily need to be performed in the order illustrated or discussed. The various example methods described and/or illustrated herein may also omit one or more of the steps described or illustrated herein or include additional steps in addition to those disclosed.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the invention as disclosed herein.

Claims

What is claimed is:

1. A thermal interface structure, comprising:

a thermal interface material for thermally coupling a heat-generating structure to a heat-dissipating structure, the thermal interface material capable of enduring a repeated shearing force caused by sliding the heat-generating structure against the heat-dissipating structure; and

an adhesive material for holding the thermal interface material in place on the heat-dissipating structure.

2. The thermal interface structure of claim 1, wherein the thermal interface material is positioned on a beveled lead-in of the heat-dissipating structure.

3. The thermal interface structure of claim 1, wherein the thermal interface material comprises a foam-like synthetic graphite.

4. The thermal interface structure of claim 1, wherein the thermal interface material has compression ratio of substantially between 30 and 80 percent.

5. The thermal interface structure of claim 1, wherein the thermal interface material is selected to provide a substantially low thermal resistance by substantially filling an air gap between the heat-generating structure and the heat-dissipating structure.

6. The thermal interface structure of claim 1, wherein the adhesive material comprises a pressure-sensitive adhesive.

7. The thermal interface structure of claim 1, wherein the adhesive material comprises a hot-melt adhesive.

8. The thermal interface structure of claim 1, wherein the adhesive material is selected to provide a balance between a thermal performance and a mechanical bonding performance of the thermal interface structure.

9. The thermal interface structure of claim 1, wherein the adhesive material substantially covers an entire surface of the thermal interface material.

10. The thermal interface structure of claim 1, wherein the adhesive material substantially covers only a portion of the thermal interface material corresponding to a contact area between the heat-generating structure and the heat-dissipating structure.

11. The thermal interface structure of claim 1, further comprising a plastic film for protecting the thermal interface material from the repeated shearing force.

12. The thermal interface structure of claim 11, wherein the plastic film covers only portions of the thermal interface material substantially outside of a contact area between the heat-generating structure and the heat-dissipating structure.

13. A method for providing a thermal interface structure, comprising:

forming a thermal interface material for thermally coupling a heat-generating structure to a heat-dissipating structure such that the thermal interface material capable of enduring a repeated shearing force caused by sliding the heat-generating structure against the heat-dissipating structure; and

forming an adhesive material for holding the thermal interface material in place on the heat-dissipating structure.

14. The method of claim 13, wherein forming a thermal interface material comprises forming a thermal interface material on a beveled lead-in of the heat-dissipating structure.

15. The method of claim 13, wherein forming a thermal interface material comprises forming a foam-like synthetic graphite.

16. The method of claim 13, wherein forming a thermal interface material comprises forming a thermal interface material having a compression ratio of substantially between 30 and 80 percent.

17. The method of claim 13, wherein forming a thermal interface material comprises forming a thermal interface material to provide a substantially low thermal resistance by substantially filling an air gap between the heat-generating structure and the heat-dissipating structure.

18. The method of claim 13, wherein forming an adhesive material comprises forming a pressure-sensitive adhesive.

19. The method of claim 13, wherein forming an adhesive material comprises forming a hot-melt adhesive.

20. The method of claim 13, wherein forming an adhesive material comprises forming an adhesive material selected to provide a balance between a thermal performance and a mechanical bonding performance of the thermal interface structure.

21. The method of claim 13, wherein forming an adhesive material comprises forming an adhesive material substantially covering an entire surface of the thermal interface material.

22. The method of claim 13, wherein forming an adhesive material comprises forming an adhesive material substantially covering only a portion of the thermal interface material corresponding to a contact area between the heat-generating structure and the heat-dissipating structure.

23. The method of claim 13, further comprising forming a plastic film for protecting the thermal interface material from the repeated shearing force.

24. The method of claim 23, wherein forming a plastic film comprises forming a plastic film covering only portions of the thermal interface material substantially outside of a contact area between the heat-generating structure and the heat-dissipating structure.