Thermal management of high heat flux multi-element assemblies

Abstract

The electronic package includes a thermal interface for dissipating heat from an array of electronic components, which comprises multiple electronic components fixed to a substrate. The thermal interface includes a thin heat-diffusing layer for transferring heat input from the electronic components in a direction transverse to the heat flux. This heat-diffusing layer is part of a laminated structure that is effectively utilized by diffusing thermal energy across the input plane.

Description

Technical Field

[0001] The present invention relates generally to thermal management of electronic devices, and more specifically to thermal interface construction for efficiently transferring heat energy from an array of electronic components to a heat sink. Background Technology

[0002] Thermal interfaces are widely used in heat dissipation applications where excess heat needs to be transferred from one location to another. Thermal interfaces are typically positioned between these locations in a manner that accommodates the required heat transfer in an efficient and mechanically useful way. Example applications of such thermal interfaces include the electronics industry, where electronic components must be cooled to maintain minimum threshold performance characteristics. Heat is typically transferred from heat-generating electronics by thermally coupling the electronic device to a heat sink, which usually has a relatively high heat dissipation capacity. Heat dissipation characteristics include appropriate materials, configuration, and exposure to a cooling medium.

[0003] Thermal interface materials and structures can facilitate thermal coupling between heat-generating elements, such as electronic components, and heat sinks. For example, direct physical coupling between heat-generating electronic components and heat sinks can be difficult due to relative external geometry, materials, and specific constraints near the heat-generating element. Therefore, thermal interfaces can act as a physical connection mechanism between the heat-generating element and the heat sink without significantly hindering heat transfer. Because heat transfer can be significantly impeded at thermal barriers where thermal energy must pass through a medium with relatively low thermal conductivity, thermal interfaces can improve the efficiency of heat transfer to the heat sink by minimizing the presence of thermal barriers. Thermal interfaces can be made flexible to "conform" to surface irregularities, thereby minimizing voids that could further impede heat transfer.

[0004] With the miniaturization and increased power of microelectronic devices, heat dissipation has become critical for the performance, reliability, and further miniaturization of various electronic devices. Integrated circuits (“ICs”) represent examples of heat-generating electronic components that may require heat dissipation for reliable operation. ICs are typically assembled into packages by physically and electrically coupling them to a substrate such as a circuit board or more specifically a printed circuit board (“PCB”). An array of ICs and / or other electronic components fixed to a substrate forms an electronic assembly. The demand for improved performance in smaller electronic assemblies leads to an increase in heat generation per unit area. Therefore, improved thermal management solutions are needed to address the increased heat transfer requirements.

[0005] A heat-generating element thermally coupled to a thermal interface constitutes a heat source that emits heat energy through a path of lowest thermal resistance. For example, in applications where a heat generator element is thermally coupled to a uniform thermal interface, heat energy is typically dissipated to a heat sink along a tapered or cylindrical pattern. Where the heat sink is much more thermally conductive than the thermal interface, heat dissipation from the heat source follows a path of lowest thermal resistance to the heat sink. In the case of a uniform thermal interface, such a path is the shortest distance between the heat source and the heat sink through the thermal interface. This phenomenon has led to the development of thermal interfaces with anisotropic thermal conductivity, where the thermal conductivity along the thickness (“z”) direction—the shortest path between the heat source and the heat sink—is a specially designed configuration tuned to facilitate heat transfer along this “z” direction. Examples of such thermal interfaces include oriented graphite pads, where graphite fibers are oriented parallel to the “z” axis through the thickness of the thermal interface. With such an arrangement, the thermal interface exhibits preferential heat transfer along the “z” axis. Although anisotropic thermal interfaces have proven useful for conducting heat energy with high thermal conductivity values ​​along the z-axis, several drawbacks have hindered their widespread acceptance. For example, oriented fiber thermal interfaces are often expensive. Additionally, some applications require compression of the electronic package along the z-axis during manufacturing; this compression can damage the oriented fibers and reduce overall thermal conductivity.

[0006] Some conventional high thermal conductivity interfaces, including many variants of anisotropic thermal interfaces, exhibit resistivity insufficient to be considered nonconductors. Many applications require electrical insulation of connected electronic components, where such high thermal conductivity interfaces are unsuitable.

[0007] Therefore, one objective is to provide a thermal interface that is non-conductive in its thickness.

[0008] Another objective is to provide a thermal interface that maintains effective thermal conductivity after thickness compression.

[0009] Another objective is to provide a cost-effective thermal interface that can simultaneously dissipate heat energy from an array of heat-generating electronic components.

[0010] A further objective is to provide an electronic package that utilizes a thermal interface to effectively dissipate heat from an array of multiple spaced-apart electronic components. Summary of the Invention

[0011] This invention enables the efficient dissipation of excess heat generated by an array of multiple electronic components to a heat sink. Specifically, the invention provides a thermal interface that enhances the overall thermal conductivity along directions parallel to the thickness axis by diffusing heat from a heat source along the x and y axes. This thermal interface utilizes a heat-diffusing layer configured to efficiently conduct heat along the x and y axes, thereby improving the volumetric efficiency of heat transfer from the thermal interface to the heat dissipator along the z-axis.

[0012] In an example embodiment, the electronic package of the present invention includes a substrate and an array of electronic components, the array of electronic components including a plurality of independent, spaced-apart electronic components fixed to the substrate. The electronic package further includes a heat sink and a thermal interface located in a thermal path between the electronic component array and the heat sink. The thermal interface includes a heat-diffusing layer and a compliant layer, and a thickness defined along a thickness axis passing through the heat-diffusing layer and the compliant layer. The heat-diffusing layer is less than 20% of the thickness and exhibits a first thermal conductivity. The compliant layer exhibits a second thermal conductivity significantly lower than the first thermal conductivity and 10 4 Pa–10 6 Pa is the compressive modulus.

[0013] In another embodiment, the electronic package of the present invention includes a substrate and an array of electronic components, the array of electronic components including a plurality of independent, spaced-apart electronic components fixed to the substrate. The electronic package further includes a thermal interface comprising a heat-diffusing layer and a flexible layer, and a thickness defined along a thickness axis passing through the heat-diffusing layer and the flexible layer. The heat-diffusing layer is less than 20% of the thickness and exhibits a first thermal conductivity. The flexible layer exhibits a second thermal conductivity significantly lower than the first thermal conductivity and 10 4 Pa–10 6 The compressive modulus of Pa. The thermal diffusion layer is thermally connected to the array of electronic components, and the heat sink is thermally connected to the flexible layer of the thermal interface.

[0014] A method for fabricating the electronic package of the present invention includes providing a thermal interface having a heat-diffusing layer and a flexible layer, and a thickness defined along a thickness axis passing through the heat-diffusing layer and the flexible layer. The thermal interface exhibits an initial thermal conductivity. The heat-diffusing layer of the thermal interface is less than 20% of the thickness and exhibits a thermal conductivity of at least 100 W / m*K. The flexible layer exhibits a thermal conductivity of 10... 4 Pa–10 6 The compressive modulus of Pa. A thermal interface is fixed in a thermal path between a heat sink and an array of electronic components fixed to a substrate. The thermal interface is compressed along the thickness axis to reduce its thickness, such that the thermal interface with a thickness reduction of up to 50% exhibits a compressive thermal conductivity of at least 80% of its initial thermal conductivity. Compression of the thermal interface may include moving at least one of the substrate and the heat sink toward the other of the substrate and the heat sink. Attached Figure Description

[0015] Figure 1 This is a cross-sectional view of the electronic package of the present invention;

[0016] Figure 2 This is a cross-sectional view of the thermal interface portion of the electronic package of the present invention;

[0017] Figure 3This is a perspective view of the thermal interface portion of the electronic package of the present invention;

[0018] Figure 4 This is a cross-sectional view of a portion of the electronic package of the present invention;

[0019] Figure 5 This is a flowchart describing a method for manufacturing the thermal interface portion of the electronic package of the present invention;

[0020] Figure 6 It is a comparison of thermal conductivity diagrams;

[0021] Figure 7A This is a cross-sectional view of the electronic package of the present invention under compressive force; and

[0022] Figure 7B This is a cross-sectional view of the electronic package of the present invention after compression. Detailed Implementation

[0023] The objects and advantages listed above, as well as other objects, features, and advancements represented by the present invention, will now be presented in light of the detailed embodiments described with reference to the accompanying drawings. Other embodiments and aspects of the invention are believed to be within the grasp of those skilled in the art.

[0024] In describing the apparatus of the present invention, the terms "upper," "lower," "horizontal," "vertical," "above," "below," "proximal," "farthest," or similar related terms may be used herein to describe the components of the apparatus and their relative positions. These terms are used for convenience of reference to the accompanying drawings and should not be construed as limiting the scope of the invention.

[0025] Now, referring to the attached diagram, first refer to... Figure 1 The electronic package 10 includes a substrate 12 and an array of electronic components 14, the array of electronic components 14 including a plurality of electronic components 16 fixed to the substrate 12. The electronic package 10 further includes a heat sink 18 and a thermal interface 20 in a thermal path (indicated by dashed arrow 22) between the electronic component array 14 and the heat sink 18. The electronic package 10 is arranged to dissipate heat generated by the electronic components 16 by providing a thermally conductive path from the electronic component array 14 to a heat-absorbing fluid medium 24 in contact with the heat sink 18. In typical applications, the fluid medium 24 may be a gas, such as air, driven by an air thruster to absorb heat from the heat sink 18. The electronic package 10 is an example arrangement that can be suitably modified to suit various electronic applications such as data processors, data storage devices, communication boards, antennas, etc. Such a device can be used in computing devices, communication devices, and their peripherals. In a particular example embodiment, the electronic package 10 can be employed to support various functions in a cellular communication device.

[0026] In addition to serving as a support for the electronic component array 14, substrate 12 may provide one or more of a variety of functions. For the purpose of simplifying the description of the electronic package 10 of the present invention, substrate 12 may be a circuit board, such as a printed circuit board with conductive traces on a mounting surface 13 for electrically connecting electronic components 16 in the assembly as needed. Components 16 may be electrically connected to wiring traces by soldering or other known techniques. In operation, electronic components 16 generate significant excess heat that must be dissipated to maintain optimal performance. Electronic components 16 may be any of a variety of components useful in electronic processes, including, for example, integrated circuits, resistors, transistors, capacitors, inductors, and diodes.

[0027] Thermal interface 20 typically provides a thermal bridge between electronic component array 14 and heat sink 18 along thermal path 22. Heat sink 18 can be thermally coupled to thermal interface 20 in a manner that most efficiently transfers heat to heat sink 18. As schematically shown, heat sink 18 can have a configuration incorporating a relatively high surface area, such as through fins 28. The use of heat sinks is readily understood, and both conventional and custom designs are contemplated for use in the arrangements of the present invention.

[0028] Conventional methods for thermal interfaces include uniform and flexible thermally conductive materials, such as pastes or gels. Another example interface includes oriented fiber devices with thermally conductive fibers oriented substantially parallel to the thermal path 22. As mentioned above, such solutions may be unsuitable for certain applications. The thermal interface 20 has been developed to most effectively utilize the flexible thermally conductive volume of the interface to maximize heat capacity. To this end, the thermal interface 20 includes a heat diffusion layer 30 for diffusing the heat energy received from the electronic component 16 over a wider area before being transferred to the flexible layer 32. The arrangement of the present invention facilitates heat transfer by making fuller use of the total conductivity of the thermal interface 20, which correspondingly improves the overall thermal conductivity performance of the thermal interface 20 when used in conjunction with multiple spaced-apart heat sources, such as the electronic component 16.

[0029] The thermal interface 20 may be a multilayer composite material comprising a heat diffusion layer 30 and a flexible layer 32. The thermal interface 20 has a thickness "T" defined along a thickness axis 34 passing through the heat diffusion layer 30 and the flexible layer 32. The heat diffusion layer 30 has a thickness "T1" less than 20% of the thickness T, preferably less than 15% of T, and more preferably less than 10% of the thickness T. In some embodiments, the diffusion layer 30 may have a thickness T1 that is 5-10% of the thickness T of the thermal interface 20.

[0030] Compared to the total thickness T of the thermal interface 20, the heat diffusion layer 30 is relatively thin to promote the distribution of thermal energy essentially along the "x" and "y" axes, such as Figure 2 and 3As shown. The heat diffusion layer 30 preferably exhibits a first thermal conductivity "C1" that is significantly greater than the second thermal conductivity "C2" of the flexible layer 32. Because heat energy is transferred along the path of least resistance, the heat energy received at the heat diffusion layer 30 at the thermal interface 20 will be primarily transferred throughout the heat diffusion layer 30 before being transferred through the flexible layer 32. This "path of least resistance" effect causes the heat input from the individual electronic components 16 of the electronic component array 14 to diffuse primarily along the x and y axes throughout the heat diffusion layer 30 before being transferred through the z-axis. In this way, the heat energy transferred to the flexible layer 32 is substantially distributed throughout the interface region presented at the first surface 33 of the flexible layer 32, and then substantially throughout the entire volume of the flexible layer 32. This method maximizes the thermal conductivity of the flexible layer 32. In the absence of the heat diffusion layer 30 at the thermal interface 20, as in conventional pastes and gels, heat input from individual heat sources typically does not transfer throughout the thermal interface volume, but is instead transferred to the heat sink along the thickness axis in a more direct path.

[0031] To achieve thermal diffusion properties, the thermal diffusion layer 30 preferably exhibits a first thermal conductivity C1 of at least 100 W / m*K, more preferably at least 400 W / m*K. In some embodiments, the first thermal conductivity C1 can be 100-1500 W / m*K, more preferably 400-1000 W / m*K. For the purposes of this invention, the thermal conductivity of the layer or structure is determined according to ASTM D5470. The thermal conductivity of the thermal diffusion layer 30 can be substantially equal in all three dimensions, or it can be anisotropic, with preferential heat transfer substantially along the x and y axes. In other words, the heat transfer through the thermal diffusion layer 30 is preferably substantially equal either along all three axes (x, y, z), or in a manner such as... Figure 2 and 3 The directions shown indicate that heat transfer along the x and y axes is preferred over heat transfer along the z axis. To achieve heat diffusion along the x and y axes, an anisotropic heat diffusion layer 30 that prioritizes heat transfer along the z axis over heat transfer along the x and y axes is undesirable. Example materials that can be used for the heat diffusion layer 30 include copper, aluminum, graphite, and boron nitride. However, other materials with high thermal conductivity are considered suitable for use in the heat diffusion layer 30 of this invention.

[0032] To facilitate heat transfer along the x and y axes of the thermal interface 20, the heat diffusion layer 30 is preferably relatively thin along the thickness axis 34 compared to the total thickness T of the thermal interface 20. Since the thermal diffusion layer 30 has a significantly higher thermal conductivity compared to the flexible layer 32, the relatively thin heat diffusion layer 30 more effectively guides heat transfer along the x and y axes. However, the applicant has found that a balance is preferably struck between driving heat transfer along the x and y axes and providing sufficient heat capacity in the heat diffusion layer 30 to accommodate the thermal energy input from the electronic component array 14 without prematurely transferring heat to the flexible layer 32. Therefore, at least in some embodiments, it is preferable to maintain a minimum thickness threshold for the heat diffusion layer 30 to accommodate the thermal energy input in a manner that does not “overload” the total heat capacity of the heat diffusion layer 30, which could result in heat from a separate heat source being transferred more directly through the thickness axis 34. Therefore, it is desirable that the heat diffusion layer thickness T1 can account for at least 5% of the total thickness T of the thermal interface 20, more preferably 5-20% of the thickness T. In some embodiments, the heat diffusion layer thickness T1 can be 25-125 micrometers.

[0033] The flexible layer 32 is preferably thermally conductive at least along the z-axis and is preferably a conformable material to maximize thermal contact with the heat sink 18. The flexible layer 32 can be formed of a variety of materials, which can be used alone or in combination to create a conformable and thermally conductive substance. Preferably, the flexible layer 32 is self-supporting at least at room temperature, wherein the defined three-dimensional shape of the flexible layer 32 is self-sustaining at least at room temperature and without the application of external forces. Example materials for the flexible layer 32 include microcrystalline waxes or silicone-based polymers, including silicone waxes, silicone greases, and silicone gels. Examples of formulations that can be used for the flexible layer 32 include those described in U.S. Patent Nos. 5,950,066 and 6,197,859, the contents of which are incorporated herein by reference. In some embodiments, the flexible layer 32 may comprise a phase change material with a melting point of about 40-80°C.

[0034] The flexible layer 32 may further include thermally conductive particulate material dispersed therein to improve thermal conductivity. A variety of thermally conductive particulate materials can be used to improve the thermal conductivity of the flexible layer 32, including, for example, alumina, aluminum nitride, boron nitride, graphite, silicon carbide, diamond, metal powders, ceramic particles, carbon fibers and nanotubes, metal alloys, and combinations thereof. Particle sizes up to approximately 200 micrometers are typical. The particulate filler material can be provided in the flexible layer 32 at a concentration of approximately 10 to 95% by weight. The loading level of the particulate filler can affect the total compressive modulus of the flexible layer 32. Therefore, it is desirable to maintain a value no greater than approximately 10 at room temperature. 6 Pa, preferably 10 4 -10 6 The compressive modulus of Pa. For this purpose, the term "compressive modulus" is defined by the test procedure ASTM D575.

[0035] The flexible layer 32 can exhibit a thermal conductivity C2 that is significantly lower than that of the thermal diffusion layer C1. While low thermal resistance / high thermal conductivity is required in the thermal interface, maximizing the thermal conductivity of the thermal interface bulk itself may come at the expense of conformability. The applicant recognizes that conformability is even more important than the thermal conductivity within the thermal interface material in terms of the effectiveness of controlling the thermal interface material. Therefore, a balance is often struck between the thermal conductivity and conformability of the thermal interface. The device of the present invention achieves this balance by maintaining conformability in the flexible layer 32, expressed in terms of its compressive modulus. The conformable thermal interface material can vary in thermal conductivity, but is typically below 20 W / m*K. Therefore, the flexible layer 32 preferably exhibits a thermal conductivity of at least 1-15 W / m*K along the z-axis. In some preferred embodiments, the thermal conductivity of the flexible layer 32 at least along the z-axis is 5-12 W / m*K. It should be understood that local thermal conductivity values ​​at various points within the flexible layer 32 and / or the thermal diffusion layer 30 may be less than the values ​​described above. However, the net thermal conductivity at least along the z-axis is preferably as described above.

[0036] The flexible layer 32 can be formed to have a thickness T2, which can balance the thickness T of the thermal interface 20 with that of the heat diffusion layer 30. However, it is contemplated that layers other than the heat diffusion layer 30 and the flexible layer 32 may be present in the thermal interface 20. In some example embodiments, the flexible layer 32 may have a thickness T2 of 0.25-2.5 mm, more preferably 0.5-1 mm.

[0037] In some embodiments, adhesive material 40 can be used to attach the heat-diffusing layer 30 to the electronic component array 14. For example... Figure 4 As shown, an adhesive material 40, such as a pressure-sensitive adhesive, can be applied to the thermal diffusion layer 30 to secure the thermal diffusion layer 30 to one or more electronic components 16 of the electronic component array 14. The adhesive material 40 may be provided in the layer or in separate pads for securing to the one or more electronic components 16 of the array 14. The adhesive material 40 may be thermally conductive and have an electrical conductivity of at least about 0.5 W / m*K. Examples of useful adhesive materials include Bond Ply, commercially available from Henkel Corporation, Irvine, CA. TM and LiquiBond TM Thermally conductive adhesive.

[0038] The thermal interface 20 is preferably electrically insulating throughout its thickness T along the thickness axis 34. An advantage of the thermal interface 20 over conventional high thermal conductivity interfaces is its suitability for applications requiring electrical insulation. Some conventional high thermal conductivity interfaces rely on structures and compositions that reduce electrical resistance to the point of losing their insulating properties. A conventional approach to high thermal conductivity interfaces uses oriented graphite, which is oriented throughout the thickness of the interface to promote thermal conductivity along the z-axis. However, in doing so, the oriented graphite forms conductive paths through the thermal interface. Low-resistance thermal interfaces are unsuitable for certain applications. The flexible layer 32 is preferably non-conductive, such that the thermal interface 20 exhibits at least 10 Ω·cm in resistance throughout its thickness T along the thickness axis 34. 8 The resistivity is Ω*cm. The thermal interface 20 can more preferably exhibit at least 10 Ω*cm resistivity throughout the entire thickness T along the thickness axis 34. 10 Resistivity in Ω*cm.

[0039] The thermal diffusion layer 30 is expected to be assembled to the flexible layer 32 by one of a variety of methods, including, for example, vapor deposition, plasma polymerization, spraying, sputtering, etc. Figure 5 A flowchart illustrating example process steps for manufacturing a thermal interface is shown. Specifically, material for the thermal diffusion layer 30 is deposited onto a release liner to a predetermined thickness to form a coated substrate. In some embodiments, the material may be applied to the substrate to a predetermined thickness of approximately 25-125 micrometers. Release liners are well known in the art, and conventional release liners that can be relatively easily removed from the thermal diffusion layer 30 are contemplated for use in the thermal interface manufacturing process. An example release liner that may be used to receive and subsequently remove the deposited thermal diffusion layer 30 is polyethylene terephthalate (PET).

[0040] The coated substrate is then brought into contact with calendering rolls along the release liner, exposing the heat diffusion layer 30 material in an orientation aligned with the flexible layer 32 during the calendering operation. This alignment results in the heat diffusion layer 30 adhering to the flexible layer 32 with a stronger coupling than the heat diffusion layer 30 has with its corresponding release liner substrate. Consequently, the substrate is then removed from the heat diffusion layer 30, while the heat diffusion layer 30 remains in contact with the flexible layer 32. The individual thermal interfaces can then be punched to the desired dimensions.

[0041] One aspect of the invention is how the thermal interface 20 loses very little thermal conductivity after compression along the thickness axis 34. The thermal conductivity of some thermal interfaces decreases significantly upon compression. This may be due to, for example, the destruction of the oriented fibers that rely on them to achieve thermal conductivity. The thermal interface 20 of the present invention is constructed to allow compression along the thickness axis 34 without a significant reduction in its thermal properties.

[0042] Figure 6A comparison of the thermal performance of a nominal 20 W / m*K oriented graphite thermal interface with an initial thickness of 0.07 inches under progressive compression is shown, compared to the 0.08-inch nominal 10 W / m*K thermal interface of the present invention. Specifically, Figure 6 Comparative data show that the thermal conductivity of oriented graphite interfaces decreases significantly under compression, while the thermal conductivity of this arrangement is almost unaffected, even under significant compression. In a preferred embodiment, the thermal interface 20, with a thickness reduction of up to 50%, exhibits a compressive thermal conductivity of at least 80% of its initial thermal conductivity. Figure 6 As shown, the thermal conductivity of a nominal 10 W / m*K thermal interface decreases by less than 20% after being compressed by 50% along its thickness axis.

[0043] Figure 7A and 7B A method for fabricating the electronic package of the present invention is illustrated, wherein a thermal interface 20 is fixed in a thermal path 22 between a heat sink 18 and an array 14 of electronic components 16 fixed to a substrate 12. As indicated by force vectors F1 and F2, the thermal interface 20 is compressed along the thickness axis 34 by applying a force to one or both of the heat sink 18 and the substrate 12. Conventional compression mechanisms can be used to compress the electronic package 10 to the desired extent. In some embodiments, the electronic package 10 can be compressed along the thickness axis 34 to such that the thickness T of the thermal interface 20 is reduced by up to 50%. Figure 7B The electronic package 10 after the compression process is shown. Each of the heat sink 18, the electronic component array 14, and the substrate 12 is relatively incompressible compared to the thermal interface 20. In some embodiments, the heat diffusion layer 30 of the thermal interface 20 is relatively incompressible compared to the flexible layer 32. In such embodiments, the compressive forces F1 and F2 applied to the electronic package 10 can compress primarily only the flexible layer 32 of the thermal interface 20. Figure 7A and 7B In the example shown, the initial thickness T of the thermal interface 20 i It can reduce the thickness by up to approximately 50%, where the final thickness T f This can be represented by the following relationship:

[0044] T f =0.5≤T i ≤1.0

[0045] As stated above, the applicant has discovered that the thermal interface 20 can be compressed in such a way that it still substantially retains its thermal conductivity. This property is important in applications where compression is required or utilized during assembly.

[0046] This invention has been described in considerable detail to provide those skilled in the art with the information needed to apply the novel principles and to construct and use embodiments of the invention as desired. However, it should be understood that various modifications can be made without departing from the scope of the invention itself.

Claims

1. An electronic package comprising: substrate; An array of electronic components, the array comprising a plurality of independent, spaced-apart electronic components fixed to the substrate; heat sink; and A thermal interface located in the thermal path between the electronic component array and the heat sink, the thermal interface comprising a heat-diffusing layer and a flexible layer, and a thickness defined along a thickness axis passing through the heat-diffusing layer and the flexible layer, wherein the heat-diffusing layer is less than 20% of the thickness and exhibits a first thermal conductivity, and the flexible layer exhibits a second thermal conductivity significantly lower than the first thermal conductivity and 10 4 Pa – 10 6 The compressive modulus of Pa, wherein the first thermal conductivity is at least 100 W / m*K and the second thermal conductivity is 1-15 W / m*K.

2. The electronic package of claim 1, wherein the thermal interface exhibits at least 10°C over the entire thickness along the thickness axis. 8 *cm resistivity.

3. The electronic package of claim 1, wherein the thermal interface is fixed to at least one of the heat sink and the array of electronic components.

4. The electronic package of claim 3, comprising an adhesive material for securing the thermally diffusing layer to a plurality of electronic components of the electronic component array.

5. The electronic package according to claim 4, wherein the adhesive material comprises a pressure-sensitive adhesive.

6. The electronic package according to claim 1, wherein the substrate is a circuit board.

7. The electronic package of claim 1, wherein the electronic component comprises one or more of an integrated circuit, a resistor, a transistor, a capacitor, an inductor, and a diode.

8. The electronic package according to claim 1, wherein the heat diffusion layer is selected from copper, aluminum, graphite and boron nitride.

9. The electronic package of claim 1, wherein the heat diffusion layer is 25-125 μm along the thickness axis.

10. The electronic package of claim 1, wherein the flexible layer comprises particulate filler dispersed in a silicone polymer matrix.

11. The electronic package of claim 1, wherein the thickness axis is parallel to the thermal path.

12. A method for preparing an electronic package, the method comprising: a. Providing a thermal interface having a heat-diffusing layer and a flexible layer, and a thickness defined along a thickness axis passing through the heat-diffusing layer and the flexible layer, wherein the thermal interface exhibits an initial thermal conductivity, and wherein the heat-diffusing layer is less than 20% of the thickness and exhibits a thermal conductivity of at least 100 W / m*K, and wherein the flexible layer of the thermal interface exhibits a thermal conductivity of 1-15 W / m*K, and the flexible layer exhibits a thermal conductivity of 10 W / m*K. 4 Pa – 10 6 The compressibility modulus of Pa; b. Fix the thermal interface in the thermal path between the heat sink and the array of multiple electronic components fixed to the substrate; and c. Compress the thermal interface along the thickness axis to reduce the thickness, wherein the thermal interface with a thickness reduction of up to 50% exhibits a compressive thermal conductivity of at least 80% of the initial thermal conductivity.

13. The method of claim 12, wherein the thickness axis is parallel to the thermal path.

14. The method of claim 12, wherein the thermal interface exhibits at least 10 along the entire thickness of the thickness axis. 8 *cm resistivity.

15. The method of claim 12, wherein compression comprises moving at least one of the substrate and the heat sink toward the other of the substrate and the heat sink.

16. An electronic package comprising: substrate; An array of electronic components, the array comprising a plurality of independent, spaced-apart electronic components fixed to the substrate; A thermal interface comprising a heat-diffusing layer and a flexible layer, and a thickness defined along a thickness axis passing through the heat-diffusing layer and the flexible layer, wherein the heat-diffusing layer is less than 20% of the thickness and exhibits a first thermal conductivity, and the flexible layer exhibits a second thermal conductivity significantly lower than the first thermal conductivity and 10. 4 Pa – 10 6 The compressive modulus of Pa, wherein the first thermal conductivity is at least 100 W / m*K and the second thermal conductivity is 1-15 W / m*K, wherein the heat diffusion layer is thermally connected to the electronic component array; and A heat sink, which is thermally connected to the flexible layer of the thermal interface.

17. The electronic package of claim 16, wherein the thermal interface exhibits at least 10°C over the entire thickness along the thickness axis. 8 *cm resistivity.

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