Patent Application
20180259271
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.
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.
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.
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.
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
The plastic film 16a-16b can include a plastic or a metal film. For example, the plastic film 16a-16b can include a polyimide tape, a polyethylene terephthalate (PET) tape, etc. The plastic film 16a-16b 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 16a-16b is 10 micrometers thick.
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.
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.
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.
