A mechanical interface that enhances thermal contact

Abstract

This invention discloses a mechanical interface for enhanced thermal contact, characterized by comprising a hot-end substrate, a cold-end substrate, and a thermal interface material. At least one of the hot-end and cold-end substrates is provided with a tip array formed by a plurality of sharp points. The thermal interface material is sandwiched between the hot-end and cold-end substrates, and the tip array is embedded in the thermal interface material. During use, the hot-end and cold-end substrates are embedded in the thermal interface material under encapsulation pressure, forming excellent contact and significantly improving the heat transfer performance of the thermal interface. Furthermore, this invention reveals that after thermal cycling, the total interfacial thermal resistance drops to its limit, approaching the volumetric thermal resistance of the thermal interface material, resulting in a significant leap in interfacial heat transfer capability.

Description

Technical Field

[0001] This invention relates to the field of thermal interface technology, and more particularly to a mechanical interface that enhances thermal contact. Background Technology

[0002] As electronic devices evolve towards miniaturization, high density, and multifunctionality, the risk of overheating continues to rise, potentially limiting their effectiveness, scope of implementation, or overall feasibility. This necessitates an increasing demand for efficient heat dissipation solutions. When two solid surfaces come into contact, the actual contact area is largely limited by surface roughness; without sufficient load, this poor contact can be exacerbated. In the thermal management of electronic devices, this contact problem manifests as contact thermal resistance. Contact thermal resistance is a key factor limiting heat transfer and directly determines the heat extraction capability of electronic devices.

[0003] Thermal interface materials (TIMs) play a crucial role in thermally connecting various components in heat dissipation solutions. TIMs are widely used in electronic device packaging for heat dissipation, primarily filling microscopic gaps and surface irregularities created when two materials are joined or in contact. This effectively reduces interfacial thermal resistance along the transfer path, enhancing interfacial heat transport capacity and improving the thermal conductivity of electronic products. However, in practice, TIMs do not fully realize their thermal conductivity potential because the contact between TIM and the solid interface remains insufficient, and the contact thermal resistance between TIM and the substrate remains the main contributor to the total interfacial thermal resistance. Therefore, it is necessary to provide a contact enhancement strategy for the thermal interface to optimize the thermal contact performance between TIM and the solid substrate, thereby improving the heat extraction capability of the thermal interface. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a mechanical contact thermal interface structure to solve the problem of insufficient thermal interface contact in the background.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A mechanical interface for enhanced thermal contact, characterized in that it comprises a hot end substrate, a cold end substrate, and a thermal interface material, wherein at least one of the hot end substrate and the cold end substrate is provided with a tip array formed by a plurality of tip arrangements, the thermal interface material is sandwiched between the hot end substrate and the cold end substrate, and the tip array is embedded in the thermal interface material.

[0007] Furthermore, the tip array includes a first tip array and a second tip array, the first tip array being disposed on the surface of the hot end substrate and the second tip array being disposed on the surface of the cold end substrate, and the first tip array and the second tip array being embedded in the thermal interface material.

[0008] Furthermore, the hot end substrate, cold end substrate, and thermal interface material are arranged in parallel.

[0009] Furthermore, the cross-section of each tip in the tip array is circular or rectangular.

[0010] Furthermore, the angle of the tips on the first and second tip arrays is 10-40°.

[0011] Furthermore, the heights of the first and second tip arrays are 30-300 μm.

[0012] Furthermore, the first tip array and the second tip array are arranged in a circular arrangement or a straight line arrangement.

[0013] Furthermore, the thermal interface material is a soft material with a thermal conductivity higher than 10 W / (m·K) and a Young's modulus lower than 100 GPa, and the stiffness of the materials used for the hot end substrate and the cold end substrate is greater than that of the thermal interface material.

[0014] Furthermore, the clamping force between the hot end substrate, the cold end substrate, and the thermal interface material comes from the bolt fastening force in the electronic packaging system.

[0015] Furthermore, the thermal interface undergoes a thermal cycling treatment after assembly.

[0016] Compared with existing technologies, the beneficial effects of this invention are: 1. It solves the problem of achieving sufficient contact thermal conductivity at the thermal interface. The thermal interface structure involved in this invention is entirely prepared by mechanical processing, which is simple and easy to operate. Moreover, the processed substrate surface structure is a micron-level array of tips, which does not cause the thermal interface to occupy additional usable space. 2. Compared with related thermal interfaces, the thermal interface contact strengthening strategy proposed in this invention significantly improves the interface heat transfer capacity and reduces the total interface thermal resistance to near the bulk thermal resistance of the thermal interface material. 3. This invention proposes a unique strengthening effect of thermal cycling on this thermal interface, that is, with the thermal cycling process, the total interface thermal resistance of the thermal interface in this invention will be further reduced. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram comparing the embodiments of the present invention with traditional thermal interface structures;

[0019] Figure 3 These are schematic diagrams of various tip array structures for the thermal interface of this invention;

[0020] Figure 4 This is a graph showing the change in interfacial thermal resistance of the thermal interface as a function of pressure before thermal cycling, according to an embodiment of the present invention.

[0021] Figure 5 This is a schematic diagram illustrating the change in thermal resistance of the thermal interface before and after thermal cycling in an embodiment of the present invention.

[0022] Wherein: 1-hot end substrate, 2-cold end substrate, 3-thermal interface material, 4-first tip array, 5-second tip array. Detailed Implementation

[0023] To enhance understanding of the present invention, we will now describe it in further detail with reference to the accompanying drawings. These embodiments are for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0024] Figure 1 A specific embodiment of a mechanical interface for enhanced thermal contact is shown, including a hot end substrate 1, a cold end substrate 2, and a thermal interface material 3. A first tip array 4 formed by a plurality of tips is provided on one side of the hot end substrate 1, and a second tip array 5 formed by a plurality of tips is provided on one side of the cold end substrate 2. The thermal interface material 3 is sandwiched between the hot end substrate 1 and the cold end substrate 2, and the first tip array 4 and the second tip array 5 are arranged opposite to each other and embedded in the thermal interface material 3.

[0025] The specific processing steps of this embodiment include the following:

[0026] 1) Prepare cutting heads with different angles for machining first tip array 4 and second tip array 5 at various angles on hot end substrate 1 and cold end substrate 2;

[0027] 2) Using the prepared cutting tool, the surfaces of the hot end substrate 1 and the cold end substrate 2 are machined by turning and milling to form the first tip array 4 and the second tip array 5;

[0028] 3) After each turning operation, move the tool head or base position and continue machining to complete the arrangement of the tip array;

[0029] 4) The thermal interface material 3 is sandwiched between the prepared hot end substrate 1 and cold end substrate 2, so that the first tip array 4 and the second tip array 5 are embedded in the thermal interface material 3 to a certain extent, and the clamping force comes from external pressure.

[0030] Preferably, the materials used for the hot-end substrate 1 and the cold-end substrate 2 have greater rigidity than the thermal interface material 3, such as hard metal materials like brass or copper, or semiconductor materials. The thermal interface material 3 is a soft material with a thermal conductivity higher than 10 W / (m·K) and a Young's modulus lower than 100 GPa, such as the indium foil in this embodiment. The clamping force between the hot-end substrate 1, the cold-end substrate 2, and the thermal interface material 3 comes from the bolt tightening force in the electronic packaging system. The hot-end substrate 1, the cold-end substrate 2, and the thermal interface material 3 should be kept as parallel as possible to each other during assembly.

[0031] Figure 2 This is a schematic diagram comparing an embodiment of the present invention with a traditional thermal interface structure. Traditional thermal interfaces use substrate surfaces that are smooth or specially polished, such as... Figure 2 As shown on the left. This invention mechanically processes a densely arranged array of tips on the surfaces of the hot-end substrate 1 and the cold-end substrate 2. Through encapsulation pressure, the first tip array 4 and the second tip array 5 are embedded into the indium foil, which serves as the thermal interface material 3, forming good contact conditions and providing more pathways for thermal contact, such as... Figure 2 As shown on the right. The dashed box represents the interfacial thermal resistance component characterized in this invention, that is, the total interfacial thermal resistance is the sum of the bulk thermal resistance of the thermal interface material and the contact thermal resistance between the thermal interface material and the substrate. The thermal resistance measured in this embodiment is also the total interfacial thermal resistance.

[0032] Figure 3 The diagram shows various array structures of the thermal interface of the present invention. By designing different tip angles, such as 20°, 28°, and 35°, different heights, such as 50μm, 100μm, and 150μm, and different arrangement methods, such as circular arrangement and straight line arrangement, this embodiment designs and processes a total of 6 different forms of tip arrays to constitute the thermal interface.

[0033] Figure 4 This is a graph showing the change in interfacial thermal resistance of the thermal interface of this invention before thermal cycling as a function of pressure. The thermal resistance measurement was performed using a self-designed device, following the standard ASTM-D5470. Pressure was applied by adding weight to the top of the measuring device. It can be seen that at a pressure of 0.75 MPa, the lowest total interfacial thermal resistance of the thermal interface of this invention reaches 5.56 mm. 2 KW –1 The total thermal resistance of a traditional smooth thermal interface is 25.75 mm. 2 KW –1 The thermal interface of this invention improves the interfacial heat transfer performance by 4-5 times.

[0034] Figure 5 This is a schematic diagram illustrating the change in thermal resistance of the thermal interface before and after thermal cycling in an embodiment of the present invention. After thermal cycling, the minimum interfacial thermal resistance of the thermal interface designed in this invention can reach 2.32 mm.2 KW –1 The volume thermal resistance is close to that of the indium foil, which is the thermal interface material, indicating that the contact thermal resistance has been reduced to its limit.

[0035] In summary, the thermal interface preparation method of this invention is simple and easy to assemble. Its core technology involves constructing a pointed array on the substrate surface without altering the thermal interface material, thus possessing broad applicability. Compared to related technologies, this invention proposes an interface thermal contact enhancement strategy. By mechanically machining a densely arranged first pointed array 4 and a second pointed array 5 on the surfaces of the hot-end substrate 1 and the cold-end substrate 2 respectively, a super-strong contact between the hot-end substrate 1, the cold-end substrate 2, and the thermal interface material 3 is achieved, resulting in a significant improvement in contact thermal conductivity. After the thermal interface is assembled, thermal cycling produces a unique enhanced heat transfer effect on the thermal interface of this invention. This invention attributes this phenomenon to the softening effect of heating on the thermal interface material 3 and the contact enhancement caused by thermal stress during thermal cycling. Electronic heat dissipation devices served by the thermal interface undergo numerous start-stop processes, accompanied by a large number of thermal cycles. The thermal interface in this invention experiences greatly enhanced contact thermal conductivity under the action of thermal cycling, which will be well demonstrated in practical applications.

[0036] The above specific embodiments are only for illustrating the technical concept and structural features of the present invention, and are intended to enable those skilled in the art to implement them. However, the above content does not limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit and essence of the present invention should fall within the scope of protection of the present invention.

Claims

1. A mechanical interface for enhanced thermal contact, characterized in that: The material includes a hot end substrate (1), a cold end substrate (2), and a thermal interface material (3). At least one of the hot end substrate (1) and the cold end substrate (2) is provided with a tip array formed by a plurality of tip arrangements. The thermal interface material (3) is sandwiched between the hot end substrate (1) and the cold end substrate (2), and the tip array is embedded in the thermal interface material (3). The tip array is arranged in a circular pattern; The thermal interface material (3) is an indium foil with a thermal conductivity higher than 10 W / (m·K) and a Young's modulus lower than 100 GPa. The stiffness of the materials used in the hot end substrate (1) and the cold end substrate (2) is greater than that of the thermal interface material (3). The clamping force between the hot end substrate (1), the cold end substrate (2), and the thermal interface material (3) comes from the bolt fastening force in the electronic packaging system; The thermal interface undergoes a thermal cycling process after assembly.

2. The mechanical interface for enhanced thermal contact according to claim 1, characterized in that: The tip array includes a first tip array (4) and a second tip array (5). The first tip array (4) is disposed on the surface of the hot end substrate (1), and the second tip array (5) is disposed on the surface of the cold end substrate (2). The first tip array (4) and the second tip array (5) are simultaneously embedded in the thermal interface material (3).

3. The mechanical interface for enhanced thermal contact according to claim 1, characterized in that: The hot end substrate (1), cold end substrate (2), and thermal interface material (3) are arranged in parallel.

4. The mechanical interface for enhanced thermal contact according to claim 1, characterized in that: The cross-section of each tip in the tip array is circular or rectangular.

5. The mechanical interface for enhanced thermal contact according to claim 1, characterized in that: The angle of the tips on the tip array is 10-40°.

6. The mechanical interface for enhanced thermal contact according to claim 1, characterized in that: The height of the tip array is 30-300 μm.

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