WO2009129237A1

WO2009129237A1 - Thermal interface material delivery system

Info

Publication number: WO2009129237A1
Application number: PCT/US2009/040522
Authority: WO
Inventors: David M. Casella; Matthew Weiss; Brian Gaul
Original assignee: JBC TECHNOLOGIES Inc
Current assignee: JBC TECHNOLOGIES Inc
Priority date: 2008-04-15
Filing date: 2009-04-14
Publication date: 2009-10-22
Anticipated expiration: 2010-10-15

Abstract

A thermal interface material (TIM) delivery system includes a removable layer having first and second end portions and first and second surfaces, a TIM having first and second surfaces, a spacing member adjacent the TIM and having first and second surfaces, the spacing member being dimensioned to prevent or reduce pump out of the TIM, and a substrate having a surface. The first surface of the TIM is removably attached to the second surface of the first end portion of the removable layer, and the second surface of the TIM is removably attached to the surface of the substrate. The first surface of the spacing member is in contact with the second surface of the second end portion of the removable layer, and the second surface of the spacing member is in contact with the surface of the substrate.

Description

THERMAL INTERFACE MATERIAL DELIVERY SYSTEM

Related Application

This application claims priority to U.S. Provisional Patent Application Serial No. 61/044,916, filed April 15, 2008, the entirety of which is hereby incorporated by reference.

Technical Field

The present invention relates generally to a system and method for transferring heat, and more particularly to a thermal interface material (TIM) delivery system for delivering a TIM to an energy-generating or energy-dissipating device.

Background of the Invention

For many applications, the thermal coupling of relatively rigid energy- generating and energy-dissipating devices requires a resilient or compilable interface to increase between the devices. Materials used for such purposes are commonly referred to as thermal interface materials (TIMs). TIMs are inherently soft and become softer as their temperature increases. This softening characteristic allows TIMs to "flow" and thereby promote heat transfer from a heat source to a heat sink.

TIMs are typically formed into a layer of single thickness and subsequently cut into desired shapes. These shapes are typically supplied in sheets or rolls similar to labels. As smaller and smaller TIMs are required for different applications, the compressive stress imparted on the TIMs when packaged can cause the TIMs to flow outward beyond desirable limits. The outward flow of TIMs, often referred to as pump out, can result in dimensional changes and thereby reduce TIM effectiveness to an unacceptable level.

Summary of the Invention

In one aspect of the present invention, a thermal interface material (TIM) delivery system includes a removable layer having first and second end portions and first and second surfaces, a TIM having first and second surfaces, a spacing member adjacent the TIM and having first and second surfaces, and being dimensioned to prevent or reduce pump out of the TIM, and a substrate having a surface. The first surface of the TIM is removably attached to the second surface of the first end portion of the removable layer, and the second surface of the TIM is removably attached to the surface of the substrate. The first surface of the spacing member is in contact with the second surface of the second end portion of the removable layer, and the second surface of the spacing member is in contact with the surface of the substrate.

In another aspect of the present invention, a method is provided for combining an energy-generating device with an energy-dissipating device to facilitate transfer of heat energy therebetween with a TIM. One step of the method includes providing a TIM delivery system comprising a removable layer having first and second end portions and first and second surfaces, a TIM having first and second surfaces, a spacing member adjacent the TIM and having first and second surfaces, and a substrate having a surface. The first surface of the TIM is removably attached to the second surface of the first end portion of the removable layer, and the second surface of the TIM is removably attached to the surface of the substrate. The first surface of the spacing member is in contact with the second surface of the second end portion of the removable layer, and the second surface of the spacing member is in contact with the surface of the substrate. Next, the removable layer is separated from the substrate so that the TIM and the spacing member remain removably attached to the removable layer. The second surface of the TIM is then contacted with one of the devices.

Brief Description of the Drawings

The foregoing and other features of the present invention will become apparent to those skilled in the art to which the present invention relates upon reading the following description with reference to the accompanying drawings, in which:

Fig. 1 is an exploded cross-sectional view of a thermal interface material (TIM) delivery system constructed in accordance with the present invention; Fig. 2 is an assembled cross-sectional view of the TIM delivery system shown in Fig. 1;

Fig. 3A is an exploded perspective view of the TIM delivery system shown in Fig. 1; Fig. 3B is an assembled perspective view of the TIM delivery system shown in Fig. 3 A;

Fig. 4 is a perspective view of a roll device for storing the TIM delivery system;

Fig. 5A is a magnified perspective view of the TIM delivery system shown in Fig. 4;

Fig. 5B is a magnified perspective view showing an alternative embodiment of the TIM delivery system in Fig. 5A;

Fig. 6 is a cross-sectional view of the TIM delivery system in Fig. 2 showing a removable layer being removed from a substrate; Fig. 7 is a cross-sectional view showing the removable layer of Fig. 6 in contact with an energy-dissipating device;

Fig. 8 is a cross-sectional view showing the removable layer in Fig. 7 being removed from the energy-dissipating device; and

Fig. 9 is a cross-sectional view showing a TIM of the TIM delivery system attached to the energy-dissipating device.

Detailed Description

The present invention relates generally to a system and method for transferring heat, and more particularly to a thermal interface material (TIM) delivery system for delivering a TIM to an energy-generating or energy-dissipating device. As representative of the present invention, Figs. 1 and 2 illustrate a TIM delivery system 10 comprising a removable layer 12, a TIM 14, a spacing member 16, and a substrate 18. By including a spacing member 16 adjacent the TIM 14, the TIM delivery system 10 substantially reduces or prevents the compressive load on the TIM during processing and shipping. In turn, the TIM delivery system 10 substantially prevents or eliminates pump out to ensure TIM 14 dimensional stability. -A-

Referring to Figs. 3A and 3B, the TIM delivery system 10 has a rectangular configuration defined by a length Ll, a width Wl, and a thickness Tl. The length Ll, width Wl, and thickness Tl of the TIM delivery system 10 can be varied as needed, depending upon a particular application. As described in more detail below, the TIM delivery system 10 can be cut {e.g., die cut) to a desired configuration and then stored in preparation for delivery. The TIM delivery system 10 can be stored using any suitable storage device including, for example, a roll device 20 (or other similar means) such as the one shown in Fig. 4.

The TIM delivery system 10 (Fig. 1) has a layered configuration and includes a removable layer 12 having first and second end portions 22 and 24 with first and second surfaces 26 and 28. The removable layer 12 has a length L2 (Fig. 3A), a width W2, and a thickness T2 which can be varied as needed, depending upon a particular application.

As described in more detail below, the second surface 28 of each of the first and second end portions 22 and 24 of the removable layer 12 include different release values to facilitate the release and subsequent application of the TIM 14 and spacing member 16 (respectively). As used herein, the term "release value" refers to the pulling force (typically measured in g/cm) needed to peel a component {e.g., the removable layer 12) of the TIM delivery system 10 from another component {e.g., the substrate 18) of the TIM delivery system. For example, the second surface 28 of the removable layer 12 at the first end portion 22 can have a release value that is greater than the release value of the second surface at the second end portion 24. By varying the release values, the TIM 14 will not peel or release as readily from the removable layer 12 as compared to the spacing member 16.

The removable layer 12 is comprised of a paper or plastic film, such as a polyester or polypropylene material, for example. The removable layer 12 can additionally or optionally include a layer of tape (not shown) disposed on a portion of the first surface 26 of the removable layer. All or only a portion of the tape can be colored {e.g., red, blue, orange, green, or any other desired color) to facilitate delivery and handling of the TIM 14. The tape can be comprised of a paper or plastic film and may be coupled to the removable layer 12 using an adhesive, for example. One example of tape suitable for application to the removable layer 12 can include SCOTCH tape (3M, Inc., St. Paul, MN).

The TIM delivery system 10 further includes a TIM 14 having first and second surfaces 30 and 32. The TIM 14 has a length L3, a width W3, and a thickness T3 that can be varied as needed, depending upon a particular application.

The TIM 14 can comprise up to 100% of a phase change material. Phase change materials are useful in TIM applications because they store and release heat as they oscillate between solid and liquid form. For example, as a phase change material changes to a solid state, it gives off heat, and as the phase change material returns to a liquid, it can absorb heat. Accordingly, the TIM 14 can comprise a phase change material in an amount greater than 0 weight percent up to about 100 weight percent.

The TIM 14 can include any one or combination of commercially available phase change materials. Examples of suitable phase change materials can include those having the following material properties: a thermal conductivity of about 1.0

W/mK to about 5 W/mK; a thermal resistance of about 0.001°C-in²/W to about 0.1°C-in²/W; a volume resistivity of about 1 x 10¹² ohm-cm to about 5 x 10¹² ohm-cm; a phase change softening range between about 0⁰C to about 100⁰C; an operating temperature of about -100⁰C to about 300⁰C; and a density of about 1 g/cc to about 5 g/cc.

As shown in Figs. 1-3B, the spacing member 16 is positioned adjacent the TIM 14 and includes first and second surfaces 34 and 36. The first surface 30 of the TIM 14 and the first surface 34 of the spacing member 16 are in contact with the second surface 28 at each of the first and second end portions 22 and 24 of the removable layer 12 (respectively). The spacing member 16 includes a length L4, a width W4, and a thickness T4 that can be varied as needed, depending upon a particular application. As shown in Fig. 5A, for example, the length IA, width W4, and thickness T4 of the spacing member 16 can be identical or nearly identical to the length L3, width W3, and thickness T3 of the TIM 14. Alternatively, the spacing member 16 can have an elongated configuration and extend perpendicular to multiple TIMs 14 as shown in Fig. 5B. The spacing member 16 is comprised of an extensible polymer, such as a low density polyethylene (LDPE) or a similar material. Examples of suitable extensible polymers which may be used to construct the spacing member 16 include those with the following material properties: a maximum temperature tolerance of about 100⁰F to about 300⁰F; a minimum temperature tolerance of about -100⁰F to about 0⁰F; a melting point of about 100⁰F to about 400⁰F; a tensile strength of about 1000 psi to about 3000 psi; and a specific gravity of about 0.5 to about 2.0.

It will be appreciated that the material properties of the extensible polymer may change based on the size of the spacing member 16. For example, a spacing member 16 comprised of LDPE may have the following material properties: a maximum temperature tolerance of about 176°F; a minimum temperature tolerance of about -58°F; a melting point of about 248°F; a tensile strength of about 1700 psi; a hardness of about SD55; and a specific gravity of about 0.92. It will also be appreciated that the spacing member 16 may be comprised of other materials, such as a polyester liner, for example. By including a spacing member 16 adjacent the TIM 14, the TIM delivery system 10 substantially reduces or prevents the compressive load on the TIM during processing and shipping. For example, when a load is applied to the TIM delivery system 10, the thickness T4 of the spacing member 16 decreases while the length L4 and the width W4 of the spacing member increase in proportion. This, in turn, substantially prevents or eliminates pump out of the TIM 14 and ensures TIM dimensional stability.

The TIM delivery system 10 also includes a substrate 18 having a surface 38. As shown in Fig. 1, the second surface 32 of the TIM 14 and the second surface 36 of the spacing member 16 are in contact with the surface 38 at a first end portion 40 and a second end portion 42 of the substrate 18 (respectively). The substrate 18 includes a length L5, a width W5, and a thickness T5 that can be varied as needed, depending upon a particular application.

The substrate 18 can comprise a polyester liner, and at least one surface of the substrate can be coated with easy or very easy release silicone, for example.

Examples of suitable polyester liners can include those with easy or very easy to release characteristics, i.e., those with release values of about 0 g/cm to about 50 g/cm. It will be appreciated that the substrate 18 can alternatively comprise a paper liner with easy or very easy release characteristics.

The layered configuration of the TIM delivery system 10 not only prevents or reduces pump out of the TIM 14, but also provides a simple and convenient means for applying the TIM to an energy-dissipating device 44 (Fig. 7) or an energy-generating device (not shown). Simple and convenient application of the TIM 14 is achieved by forming the TIM delivery system 10 with components having different release values. For example, the surface 38 of the substrate 18 can have a release value which is less than the release value at the first surface 30 of the TIM 14 and the second surface 36 of the spacing member 16. When a force is applied to the removable layer 12 and/or the substrate 18, the substrate can readily separate from the TIM 14 and the spacing member 16 while leaving the removable layer in contact with the TIM and the spacing member.

The present invention also provides a method for combining an energy- generating device with an energy-dissipating device 44 to facilitate transfer of heat energy therebetween with a TIM 14. Examples of energy-dissipating 44 and energy-generating devices are well known in the art. As shown in Figs. 6-9, one example of an energy-dissipating device 44 is a heat sink 46. Heat sinks 46 are typically used with electrically powered devices that generate heat energy. Heat sinks 46 may have a plurality of fins and may be fabricated from heat conductive materials such as aluminum, copper, iron, and/or carbon-based compounds. Examples of known energy-generating devices generally include electrically powered devices that generate heat energy, such as digital processing circuits, power transistor circuits, analog-to-digital converters, digital-to- analog converters, disk drive units, and the like.

It is known that conventional electronic parts and/or heat sinks 46 can have small voids or other minor manufacturing defects on their surfaces. When such parts are mated together, small gaps may appear at the interface(s) between surfaces. These gaps and defects can inhibit the flow of heat between the components. The method of the present invention solves this problem by providing a TIM delivery system 10 capable of delivering a TIM 14 between an energy-generating device and an energy-dissipating device 44. TIMs are highly compressible and can conform to gaps and voids located on the surface(s) of such devices to create an effective interface capable of improving the overall thermal conductivity of the assembly.

One step of the method includes providing a TIM delivery system 10. The TIM delivery system 10 can be identically constructed as the TIM delivery system shown in Figs. 1-3. It should be appreciated, however, that the TIM delivery system 10 can be configured differently (e.g., size, shape, material composition, etc.) depending upon the intended application. For example, the TIM delivery system 10 can be dimensioned to have a larger or smaller size depending upon the size and/or application surface of an energy-generating or energy-dissipating device 44. Prior to use of the TIM delivery system 10, the TIM delivery system can be stored using a roll device 20, such as the one shown in Fig. 4, for example.

To apply the TIM 14 to a heat-dissipating device 44, such as a heat sink 46, the removable layer 12 is first peeled away from the substrate 18 as shown in Fig. 6. As the removable layer 12 is peeled away from the substrate 18, both the spacing member 16 and the TIM 14 remain in contact with the second surface 28 of the first and second end portions 22 and 24 of the removable layer. The TIM 14 and spacing member 16 remain in contact with the second surface 28 of the removable layer 12 because the release values at the first surface 34 of the spacing member and the first surface 30 of the TIM are greater than the release value at the surface 38 of the substrate 18.

After the removable layer 12 (including the TIM 14 and the spacing member 16) has been entirely removed from the substrate 18, the removable layer is then applied to a mating surface 48 (Fig. 8) of the heat sink 46. As shown in Fig. 7, the removable layer 12 is applied to the heat sink 46 so that the second surface 32 of the TIM 14 is contacted with the mating surface 48. Tactile pressure can be applied to the first surface 26 of the removable layer 12 to ensure that the second surface 32 of the TIM 14 is firmly coupled with the mating surface 48 of the heat sink 46. Next, the removable layer 12 is progressively peeled away from the heat sink 46. As the removable layer 12 is peeled away, the spacing member 16 remains coupled to the second surface 28 of the removable layer because the release value at the first surface 34 of the spacing member is greater than the release value at the second surface 36 of the spacing member.

The removable layer 12 is then entirely peeled away from the heat sink 46 so that the removable layer is separated from the TIM 14 and the TIM remains securely coupled to the mating surface 48 of the heat sink 46 (Fig. 9). The removable layer 12 is separated from the TIM 14 while the TIM remains in contact with the mating surface 48 because the release value at the second surface 28 of the first end portion 22 of the removable layer is less than the release value at the second surface 32 of the TIM. With the TIM 14 securely coupled to the heat sink 46, an energy-generating device can be coupled to the first surface 30 of the TIM so that the TIM is sandwiched between the energy-generating device and the heat sink. When energy is flowed through the energy-generating device, heat is generated. The TIM 14 can then obtain a more fluid configuration and effectively convey heat into the heat sink 46 and away from the energy-generating device.

From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. It will be appreciated that the steps of the method described above are illustrative only and may be varied as needed depending upon the intended application of the present invention. For example, the TIM delivery system 10 may be used to first deliver a TIM 14 to an energy-generating device. Such improvements, changes, and modifications are within the skill of the art and are intended to be covered by the appended claims.

Claims

Having described the invention, we claim:

1. A thermal interface material (TIM) delivery system comprising: a removable layer having first and second end portions and first and second surfaces; a TIM having first and second surfaces; a spacing member adjacent said TIM and having first and second surfaces, said spacing member being dimensioned to prevent or reduce pump out of said TIM; and a substrate having a surface; said first surface of said TIM being removably attached to said second surface of said first end portion of said removable layer, and said second surface of said TIM being removably attached to said surface of said substrate; said first surface of said spacing member being in contact with said second surface of said second end portion of said removable layer, and said second surface of said spacing member being in contact with said surface of said substrate.

2. The TIM delivery system of claim 1, wherein said second surface of each of said first and second end portions of said removable layer include different release values.

3. The TIM delivery system of claim 2, wherein said second surface of said removable layer at said first end portion has a release value greater than the release value of said second surface at said second end portion.

4. The TIM delivery system of claim 1, wherein said removable layer permits the removal of said spacing member and said TIM from the substrate without substantial removal of said TIM and said spacing member from said removable layer.

5. The TIM delivery system of claim 1, wherein said removable layer permits removal of said TIM from said substrate without substantial removal of said TIM from said removable layer.

6. The TIM delivery system of claim 1, wherein said TIM is comprised of a phase change material.

7. The TIM delivery system of claim 1, wherein a portion of said first surface of said removable layer includes a layer of tape disposed thereon.

8. A method for combining an energy generating device with an energy dissipating device to facilitate transfer of heat energy therebetween with a thermal interface material (TIM), said method comprising the steps of: providing a TIM delivery system comprising a removable layer having first and second end portions and first and second surfaces, a TIM having first and second surfaces, a spacing member adjacent the TIM and having first and second surfaces, and a substrate having a surface, the first surface of the TIM being removably attached to the second surface of the first end portion of the removable layer and the second surface of the TIM being removably attached to the surface of the substrate, the first surface of the spacing member being in contact with the second surface of the second end portion of the removable layer and the second surface of the spacing member being in contact with the surface of the substrate; separating the removable layer from the substrate so that the TIM and the spacing member remain in contact with the removable layer; and contacting the second surface of the TIM with one of the devices.

9. The method of claim 8 further comprising the step of removing the removable layer from the first surface of the TIM so that the spacing member remains in contact with the removable layer.

10. The method of claim 9 further comprising the step of placing the other of the devices in contact with the first surface of the TIM.

11. A TIM delivery system comprising: a substrate having a surface; first and second removable layers, each of said first and second removable layers being spaced apart from one another and including first and second end portions and first and second surfaces; first and second TIMs, each of said first and second TIM having first and second surfaces; and a spacing member that extends between said second end portion of each of said first and second removable layers; wherein said first surface of each of said first and second TIM is removably attached to said second surface of said first end portion of each of said first and second removable layers, and said second surface of each of said first and second TIM is removably attached to said surface of said substrate; wherein separate portions of said first surface of said spacing member are in contact with said second surface of said second end portion of each of said first and second removable layers, and said second surface of said spacing member is in contact with said surface of said substrate.

12. The TIM delivery system of claim 11, wherein said second surface of each of said first and second end portions of said first and second removable layers include different release values.

13. The TIM delivery system of claim 12, wherein said second surface of said first removable layer at said first end portion has a release value greater than the release value of said second surface at said second end portion, and said second surface of said second removable layer at said first end portion has a release value greater than the release value of said second surface at said second end portion.

14. The TIM delivery system of claim 11 , wherein each of said first and second TIM is comprised of a phase change material.

15. The TIM delivery system of claim 11, wherein a portion of said first surface of each of said first and second removable layers includes a layer of tape disposed thereon.