A thermal interface material and a preparation method and application thereof

Abstract

This invention provides a thermal interface material, its preparation method, and its application. The thermal interface material includes: a thermally conductive substrate layer; an intermediate metal layer disposed on the upper and lower sides of the thermally conductive substrate layer; a plurality of groove units disposed on the surface of the intermediate metal layer; and a surface dielectric layer covering the surface of the intermediate metal layer. The thermal interface material of this invention, by disposing of an intermediate metal layer between the thermally conductive substrate and the surface dielectric, and by providing a groove structure in the intermediate metal layer, effectively alleviates interfacial thermal stress, reduces the thermal resistance of the thermal interface material, provides support, buffers excessive compression of the surface thermally conductive medium under pressure, solves the overflow problem, and simultaneously addresses the changes in solubility gradient caused by temperature gradient differences, avoids long-range migration of the surface thermally conductive medium material, and improves the structural stability and reliability of the material under thermal cycling.

Description

Technical Field

[0001] This invention belongs to the field of thermal conductive materials technology, specifically relating to a thermal interface material, its preparation method, and its application. Background Technology

[0002] As high-end consumer electronics products, such as gaming phones and laptops, continue to evolve towards higher performance and more compact designs, the power density of their internal core processors (CPUs) is constantly increasing, placing more stringent demands on heat dissipation systems. Thermal interface materials, as the key medium filling the tiny gaps between the chip and the heatsink, play a crucial role in reducing contact thermal resistance and improving overall heat transfer efficiency.

[0003] Traditional thermal greases or gels are prone to drying out or insufficient thermal conductivity under long-term high-power conditions, making it difficult to meet the requirements of continuous and efficient heat dissipation. In recent years, composite metal-based thermal interface materials have gradually become a research and application hotspot. These materials often adopt a "sandwich" three-layer structure: the middle layer is a high thermal conductivity metal layer, which provides mechanical support and enables longitudinal heat conduction; the top and bottom layers are covered with low-melting-point alloys, which utilize their softening or melting properties at operating temperatures to fill the micro-gaps between the interfaces, thereby reducing contact thermal resistance.

[0004] However, this structure still faces challenges in long-term high-load applications. When the low-melting-point alloy layer is too thick, the material is prone to overflow during the pressing and temperature cycling of the heat dissipation module. This not only contaminates surrounding components but also leads to uneven actual filling thickness at the interface, affecting heat dissipation stability. Furthermore, under continuous temperature gradients, the low-melting-point alloy undergoes directional migration due to solid-liquid phase transitions and differences in melt surface tension. The alloy melt in the central high-temperature region gradually diffuses to the surrounding low-temperature region, i.e., a pumping effect. This results in a reduction in thickness or even localized drying at the high-temperature interface, causing a continuous increase in contact thermal resistance and a gradual decrease in heat dissipation performance. This problem severely restricts its long-term high-reliability application.

[0005] Therefore, it is necessary to develop a novel interface material that combines high thermal conductivity with effective suppression of alloy migration and spillover. Summary of the Invention

[0006] The purpose of this invention is to provide a thermal interface material, its preparation method and application, which can effectively improve alloy overflow and migration caused by local pressure and temperature gradient, and enhance the safety and long-term service reliability of the thermal interface material.

[0007] To achieve this objective, the present invention employs the following technical solution:

[0008] In a first aspect, the present invention provides a thermal interface material, the thermal interface material comprising: a thermally conductive substrate layer, an intermediate metal layer disposed on the upper and lower sides of the thermally conductive substrate layer, a plurality of groove units disposed on the surface of the intermediate metal layer, and a surface dielectric layer covering the surface of the intermediate metal layer.

[0009] The thermal interface material provided by this invention has an intermediate metal layer between the thermally conductive substrate and the surface medium. The intermediate metal layer can effectively alleviate the interfacial thermal stress between the thermally conductive substrate and the surface thermally conductive medium, improve the interfacial bonding, and enhance the structural stability and reliability of the material under thermal cycling. Groove units are set on the interface of the intermediate metal layer. The protrusions of the groove units can form a supporting force, buffer the excessive compression of the surface thermally conductive medium under pressure, and solve the overflow problem. At the same time, the surface medium is filled in the grooves and separated into unit distributions, which solves the changes in solubility gradient caused by temperature gradient differences, avoids long-range migration of the surface thermally conductive medium material, and thus improves the material performance stability.

[0010] In this invention, the groove unit is formed by a surface recess in the region where the intermediate metal layer groove unit is located, directed towards the heat-conducting substrate layer. At least a portion of the surface dielectric layer fills the groove unit.

[0011] Preferably, the material of the thermally conductive substrate layer includes at least one of copper, silver, gold, graphene film, or thermally conductive ceramic.

[0012] Preferably, the thickness of the thermally conductive substrate layer is 0.01-5mm, for example, it can be 0.01mm, 0.03mm, 0.05mm, 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.5mm, 1mm, 1.5mm, 2mm, 3mm, 4mm or 5mm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0013] Preferably, the outer periphery extension length of the cross-section of the groove unit is 2-10mm, for example, it can be 2mm, 4mm, 5mm, 6mm, 8mm or 10mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] Preferably, the minimum radial dimension of the cross-section of the groove unit is 0.5-2.5mm, for example, it can be 0.5mm, 0.8mm, 1mm, 1.2mm, 1.5mm, 2mm or 2.5mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0015] The cross-sectional shape of the groove unit can be circular and / or polygonal, including but not limited to triangles, quadrilaterals, pentagons, or hexagons. A square shape is preferred.

[0016] The minimum radial dimension is the diameter of the largest inscribed circle that can be accommodated within the shape.

[0017] When the cross-sectional shape of the groove unit is circular, the minimum radial dimension is the diameter of the circle; when it is square, it is the side length of the square; when it is a regular hexagon, it is the distance between two opposite parallel sides of the regular hexagon.

[0018] Preferably, the depth of the groove unit is 0.01-0.05mm, for example, it can be 0.01mm, 0.02mm, 0.03mm, 0.04mm or 0.05mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, the spacing between adjacent groove units is 0.1-0.5 mm, for example, it can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm or 0.5 mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, the groove units are arranged in an array.

[0021] Preferably, the melting point of the intermediate metal layer is higher than that of the surface dielectric layer, and the difference between the two melting points is ≥50℃.

[0022] Preferably, the melting point of the intermediate metal layer material is 120-250°C, for example, it can be 120°C, 150°C, 180°C, 200°C, 220°C or 250°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] Preferably, the material of the intermediate metal layer includes at least one of indium, tin, indium-tin alloy, indium-bismuth alloy, tin-bismuth alloy, indium-zinc alloy, or indium-silver alloy.

[0024] In this invention, the intermediate metal layer is made of indium, tin, or an alloy, which has an appropriate melting point and hardness, can form good contact and adhesion between the layers, reduce interface stress, reduce material thermal resistance, and is also easy to process into a concave-convex structure.

[0025] Preferably, in the intermediate metal layer, in the indium-tin alloy, the mass percentage of indium is 40%-90% and the mass percentage of tin is 10%-60%; in the indium-bismuth alloy, the mass percentage of indium is 40%-55% and the mass percentage of bismuth is 45%-60%; in the tin-bismuth alloy, the mass percentage of tin is 50%-70% and the mass percentage of bismuth is 30%-50%; in the indium-zinc alloy, the mass percentage of indium is 90%-98% and the mass percentage of zinc is 2%-10%; and in the indium-silver alloy, the mass percentage of indium is 95%-98% and the mass percentage of silver is 2%-5%.

[0026] Preferably, the melting point of the material of the surface dielectric layer is 60-160℃, for example, it can be 60℃, 80℃, 100℃, 120℃, 140℃ or 160℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0027] Preferably, the material of the surface dielectric layer includes at least one of indium tin bismuth eutectic alloy, indium bismuth eutectic alloy, or indium tin alloy.

[0028] In the indium-tin-bismuth eutectic alloy, the mass content of indium is 51%, the mass content of tin is 32.5%, and the mass content of bismuth is 16.5%; in the indium-bismuth eutectic alloy, the mass content of indium is 66.67%, and the mass content of bismuth is 33.33%.

[0029] Preferably, in the surface dielectric layer, the indium-tin alloy contains 40%-90% indium by mass and 10%-60% tin by mass.

[0030] Preferably, the thickness of the intermediate metal layer is 0.01-0.05 mm, for example, it can be 0.01 mm, 0.02 mm, 0.03 mm, 0.04 mm or 0.05 mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] Preferably, the thickness between the surface of the surface dielectric layer and the upper surface of the intermediate metal layer is 0.003-0.05 mm, for example, it can be 0.003 mm, 0.005 mm, 0.008 mm, 0.01 mm, 0.02 mm, 0.03 mm, 0.04 mm or 0.05 mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] The upper surface of the intermediate metal layer refers to the surface of the non-groove unit area of ​​the intermediate metal layer.

[0033] In a second aspect, the present invention provides a method for preparing the thermal interface material described in the first aspect, the method comprising the following steps:

[0034] After pretreating the upper and lower surfaces of the thermally conductive substrate, a first coating is applied using the material of the intermediate metal layer. Then, a textured film is used to form a grooved unit structure on the surface of the intermediate metal layer to obtain a composite substrate. A second coating is applied to the surface of the composite substrate using a surface medium material, and then cooled to obtain the thermal interface material.

[0035] Preferably, the pretreatment method includes plasma treatment.

[0036] Preferably, the temperature of the first coating is 150-300℃, for example, it can be 150℃, 180℃, 200℃, 220℃, 250℃, 280℃ or 300℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0037] Preferably, the first coating speed is 10-30 mm / s, for example, it can be 10 mm / s, 15 mm / s, 20 mm / s, 25 mm / s or 30 mm / s, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0038] Preferably, the pressure of the first coating is 0.5-2 MPa, for example, it can be 0.5 MPa, 0.8 MPa, 1 MPa, 1.2 MPa, 1.5 MPa, 1.8 MPa or 2 MPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] Preferably, the method for forming the groove unit structure includes: heating the coated thermally conductive substrate, covering the surface with a textured film, placing it under vacuum conditions, then keeping it at a constant temperature under an inert gas atmosphere, cooling it after the heat preservation is completed, and peeling off the textured film.

[0040] To form the grooved unit structure, the surface of the textured film has raised units. The surface structure of the textured film can be obtained from PET or flexible metal foil through embossing or engraving.

[0041] Preferably, the thickness of the textured film is 0.02-0.2 mm, for example, it can be 0.02 mm, 0.05 mm, 0.1 mm, 0.15 mm or 0.2 mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] Preferably, the vacuum degree of the vacuum condition is 10. -3 -10 -1 Pa, for example, could be 10. -3 Pa, 5×10 -3 Pa, 10 - 2 Pa, 5×10 -2 Pa or 10-1 Pa, but not limited to the listed values, applies to other unlisted values ​​within the range as well.

[0043] Preferably, the flow rate of the inert gas is 2-5 L / min, for example, it can be 2 L / min, 2.5 L / min, 3 L / min, 3.5 L / min, 4 L / min, 4.5 L / min or 5 L / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] Preferably, the heating temperature is 0-5°C below the melting point of the intermediate metal layer material, for example, it can be 0°C, 1°C, 2°C, 3°C, 4°C or 5°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] Preferably, the heat preservation time is 15-30 minutes, for example, it can be 15 minutes, 20 minutes, 25 minutes or 30 minutes, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0046] Preferably, the temperature of the second coating is 0-10°C higher than the melting point of the surface medium layer material, for example, it can be 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C or 10°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0047] Preferably, the second coating speed is 10-30 mm / s, for example, it can be 10 mm / s, 15 mm / s, 20 mm / s, 25 mm / s or 30 mm / s, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0048] Preferably, the pressure of the second coating is 0.5-2 MPa, for example, it can be 0.5 MPa, 0.8 MPa, 1 MPa, 1.2 MPa, 1.5 MPa, 1.8 MPa or 2 MPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0049] Preferably, the cooling rate is 2-5℃ / min, for example, it can be 2℃ / min, 3℃ / min, 4℃ / min or 5℃ / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0050] Preferably, the cooling atmosphere includes a nitrogen atmosphere and / or an argon atmosphere.

[0051] Thirdly, the present invention provides an application of the thermal interface material described in the first aspect, wherein the thermal interface material is used for chip thermal conductivity.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] The thermal interface material of the present invention has an intermediate metal layer between the thermally conductive substrate and the surface medium, and a groove structure is provided in the intermediate metal layer. This effectively relieves the interfacial thermal stress, reduces the thermal resistance of the thermal interface material, and provides support force. It buffers the excessive compression of the surface thermally conductive medium under pressure, solves the overflow problem, and solves the change in solubility gradient caused by the difference in temperature gradient. This avoids the long-range migration of the surface thermally conductive medium material and improves the structural stability and reliability of the material under thermal cycling. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the structure of the thermal interface material in Example 1;

[0055] Figure 2 This is a flowchart of the preparation process of the thermal interface material in Example 1. Detailed Implementation

[0056] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative and should not be considered as specific limitations of the present invention. It should be noted that the following embodiments are for illustrative purposes only and do not represent a limitation of the present invention. For example, in the present invention, the material of the intermediate metal layer includes at least one of indium, tin, indium-tin alloy, indium-bismuth alloy, tin-bismuth alloy, indium-zinc alloy, or indium-silver alloy. The embodiments only use indium-tin alloy as an example and do not imply that the present invention can only use indium-tin alloy. In the present invention, indium-tin alloy can also be replaced by one or a combination of several of indium, tin, indium-bismuth alloy, tin-bismuth alloy, indium-zinc alloy, or indium-silver alloy. The material of the surface dielectric layer includes at least one of indium-tin-bismuth eutectic alloy, indium-bismuth eutectic alloy, or indium-tin alloy. The embodiments only use indium-tin-bismuth eutectic alloy and indium-bismuth eutectic alloy as examples. In the present invention, indium-tin-bismuth eutectic alloy or indium-bismuth eutectic alloy can also be replaced by a combination of several of indium-tin alloy, indium-tin-bismuth eutectic alloy, indium-bismuth eutectic alloy, or indium-tin alloy. Other structures and raw materials of the present invention can be understood in the same way.

[0057] Unless otherwise specified, the raw materials involved in the following specific embodiments of the present invention are all conventional materials in the art and can be purchased from commercially available products.

[0058] Example 1

[0059] This embodiment provides a thermal interface material, comprising: a thermally conductive substrate layer, an intermediate metal layer disposed on the upper and lower sides of the thermally conductive substrate layer, the surface of the intermediate metal layer having arrayed square groove units, and a surface dielectric layer covering the surface of the intermediate metal layer. The surface dielectric layer includes a filling portion filling the square groove units and extending from the filling portion to cover the upper surface of the intermediate metal layer. The structure of the thermal interface material is as follows: Figure 1 As shown.

[0060] The thermally conductive substrate layer is made of pure copper with a thickness of 0.1 mm. The intermediate metal layer is made of indium-tin alloy, in which indium accounts for 52% by mass and tin accounts for 48% by mass. The melting point of the indium-tin alloy is 120℃, and the thickness of the intermediate metal layer is 0.05 mm. The surface dielectric layer is made of indium-bismuth alloy, in which indium accounts for 66.67% by mass and bismuth accounts for 33.33% by mass. The melting point of the indium-bismuth alloy is 72℃, and the thickness between the surface of the surface dielectric layer and the upper surface of the intermediate metal layer is 0.005 mm. The square groove unit has a square cross-section with a side length of 1 mm, a depth of 0.03 mm, and a spacing of 0.5 mm between adjacent square groove units.

[0061] The thermal interface material is prepared using the following method, and the process flow diagram is shown below. Figure 2 As shown:

[0062] (1) Select a pure copper substrate with a thickness of 0.1 mm (purity of 99.99%) and perform plasma treatment on both sides for 120 s;

[0063] (2) Place the pure copper substrate on a heating platform and coat both sides with indium tin alloy. Control the coating temperature at 150±10℃, the coating speed at 20mm / s, the coating pressure at 1MPa, and control the coating thickness on each side at 0.05±0.005mm.

[0064] (3) Cool the coated substrate to 120°C, cover the upper and lower surfaces of the coated substrate with a layer of textured film. The surface of the textured film has an array of square raised units. The square raised units are separated by a grid groove structure. The grid groove structure is formed by the intersection of longitudinal grooves and transverse grooves arranged at intervals. The side length of the cross section of the square raised unit is 1 mm, the height is 0.03 mm, and the width of the groove is 0.5 mm. The textured film is made of PET and has a total thickness of 0.15 mm. Place the substrate covered with the textured film into a vacuum chamber and keep it in a nitrogen atmosphere for 10 minutes to allow the indium tin alloy to completely wet the textured film and transfer the uneven structure of the textured film to the surface of the indium tin alloy. After the temperature drops to room temperature, peel the textured film off the substrate to obtain a composite substrate with an indium tin alloy layer. The surface of the indium tin alloy layer has an array of square groove units.

[0065] (4) Coating the upper and lower surfaces of the composite substrate with an indium-bismuth eutectic alloy, the coating temperature is controlled at 80°C, the coating speed is 20 mm / s, the coating pressure is 1 MPa, the indium-bismuth eutectic alloy fully fills the square groove unit and covers the upper surface of the indium-tin alloy layer to form an indium-bismuth alloy layer, and the coated composite substrate is placed in a cooling table and cooled to room temperature at a rate of 3°C / min to obtain the thermal interface material.

[0066] Example 2

[0067] This embodiment provides a thermal interface material. Compared with Embodiment 1, the thickness of the thermally conductive substrate layer is set to 0.05 mm, and the rest is the same as in Embodiment 1.

[0068] In the preparation method of the thermal interface material, a pure copper substrate with a thickness of 0.05 mm is used, and the rest is the same as in Example 1.

[0069] Example 3

[0070] This embodiment provides a thermal interface material. Compared with Embodiment 1, the side length of the cross-section of the square groove unit is set to 2mm, and the rest is the same as Embodiment 1.

[0071] In the preparation method of the thermal interface material, a textured film with a side length of 2 mm for the cross-section of the square protrusion unit on the surface is used, and the rest is the same as in Example 1.

[0072] Example 4

[0073] This embodiment provides a thermal interface material. Compared with Embodiment 1, the side length of the cross-section of the square groove unit is set to 0.5 mm, and the rest is the same as Embodiment 1.

[0074] In the preparation method of the thermal interface material, a textured film with a side length of 0.5 mm for the cross-section of the square protrusion unit on the surface is used, and the rest is the same as in Example 1.

[0075] Example 5

[0076] This embodiment provides a thermal interface material. Compared with Embodiment 1, the material of the intermediate metal layer is replaced with pure indium (purity of 99.99%), and all other aspects are the same as in Embodiment 1.

[0077] In the preparation method of the thermal interface material, the coating material in step (2) is replaced with pure indium, the coating temperature is adjusted to 170±10℃, the cooling temperature in step (3) is adjusted to 155-160℃, and the rest are the same as in Example 1.

[0078] Example 6

[0079] This embodiment provides a thermal interface material. Compared with Embodiment 1, the material of the intermediate metal layer is replaced with pure tin (purity of 99.99%), and the rest is the same as in Embodiment 1.

[0080] In the preparation method of the thermal interface material, the coating material in step (2) is replaced with pure tin, the coating temperature is adjusted to 240±10℃, the cooling temperature in step (3) is adjusted to 227-232℃, and the rest are the same as in Example 1.

[0081] Example 7

[0082] This embodiment provides a thermal interface material. Compared with embodiment 1, the depth of the square groove unit is set to 0.04 mm, so the thickness of the middle metal layer minus the groove unit portion is 0.01 mm. The rest is the same as in embodiment 1.

[0083] In the preparation method of the thermal interface material, a textured film with a surface square protrusion unit height of 0.04 mm is used, and the rest is the same as in Example 1.

[0084] Example 8

[0085] This embodiment provides a thermal interface material. Compared with embodiment 1, the depth of the square groove unit is set to 0.01 mm, so the thickness of the middle metal layer minus the groove unit portion is 0.04 mm. The rest is the same as in embodiment 1.

[0086] In the preparation method of the thermal interface material, a textured film with a surface square protrusion unit height of 0.01 mm is used, and the rest is the same as in Example 1.

[0087] Example 9

[0088] This embodiment provides a thermal interface material. Compared with Embodiment 1, the spacing between adjacent square groove units is set to 0.1 mm, and the rest is the same as in Embodiment 1.

[0089] In the preparation method of the thermal interface material, a textured film with a groove width of 0.1 mm for the square protrusion unit on the surface is used, and the rest is the same as in Example 1.

[0090] Example 10

[0091] This embodiment provides a thermal interface material. Compared with Embodiment 1, the main material of the surface dielectric layer is replaced with an indium-tin-bismuth eutectic alloy. In the indium-tin-bismuth eutectic alloy, the mass content of indium is 51%, the mass content of tin is 32.5%, and the mass content of bismuth is 16.5%. The rest are the same as in Embodiment 1.

[0092] In the preparation method of the thermal interface material, the indium bismuth eutectic alloy in step (4) is replaced with an indium tin bismuth eutectic alloy, and the rest are the same as in Example 1.

[0093] Comparative Example 1

[0094] This comparative example provides a thermal interface material, comprising: a thermally conductive substrate layer, wherein indium-bismuth alloy layers are disposed on the upper and lower surfaces of the thermally conductive substrate layer. The thermally conductive substrate layer is a pure indium substrate with a thickness of 0.1 mm; each indium-bismuth alloy layer has a thickness of 0.03 mm and a melting point of 72°C.

[0095] Comparative Example 2

[0096] This comparative example provides a thermal interface material, comprising: a thermally conductive substrate layer, wherein pure indium metal layers are disposed on the upper and lower surfaces of the thermally conductive substrate layer. The thermally conductive substrate layer is a pure copper substrate with a thickness of 0.1 mm; the pure indium metal layers have a thickness of 0.03 mm and are made of pure indium (99.99% purity).

[0097] Comparative Example 3

[0098] This comparative example provides a thermal interface material, comprising: a thermally conductive substrate layer, the surface of which has arrayed square groove units, and a surface dielectric layer covering the surface of the thermally conductive substrate layer. The surface dielectric layer includes filling portions that fill the square groove units and extends from the filling portions to cover the upper surface of the thermally conductive substrate layer.

[0099] The thermally conductive substrate layer is made of pure copper with a thickness of 0.07 mm. The surface dielectric layer is made of indium bismuth alloy with a melting point of 72°C. The square groove unit has a side length of 1 mm and a depth of 0.03 mm, with a spacing of 0.5 mm between adjacent square groove units. The square groove units on the surface of the thermally conductive substrate layer are formed by laser engraving. The thickness between the surface of the surface dielectric layer and the upper surface of the thermally conductive substrate layer is 0.005 mm.

[0100] Comparative Example 4

[0101] This comparative example provides a thermal interface material, comprising: a thermally conductive substrate layer, an intermediate metal layer disposed on the upper and lower surfaces of the thermally conductive substrate layer, and a surface dielectric layer disposed on the surface of the intermediate metal layer.

[0102] The thermally conductive substrate layer is made of pure copper with a thickness of 0.1 mm; the intermediate metal layer is made of indium tin alloy with a thickness of 0.02 mm and a melting point of 125 °C; and the surface dielectric layer is made of indium bismuth alloy with a thickness of 0.005 mm and a melting point of 72 °C.

[0103] Performance testing

[0104] The thermal interface materials prepared in the examples and comparative examples were tested for thermal resistance using a thermal resistance meter. The meter used was a Taiwan Ruiling LW-9389, and the tests were conducted according to the standard ASTM D5470. The test conditions included 80°C and 50 psi, and material leakage was also tested. The results are shown in Table 1.

[0105] Table 1

[0106]

[0107] As can be seen from the test results in Table 1, the thermal interface material of the present invention, by setting an intermediate metal layer and incorporating a grooved unit structure within the intermediate metal layer, can effectively solve the problems of long-range migration and material overflow of the surface thermal conductive medium material. The thermal resistance of the material is within 0.055℃×cm. 2 Below / W, while ensuring good thermal conductivity, the material exhibits minimal leakage, with a leakage mass of <10g, effectively improving the structural stability and reliability of the thermal interface material. In contrast, in Comparative Examples 1-5, without an intermediate metal layer or groove structure, the thermal interface material shows significant leakage, exceeding 15g, failing to address material migration and overflow issues and thus failing to meet usage requirements.

[0108] In summary, the thermal interface material of the present invention provides an intermediate metal layer between the thermally conductive substrate and the surface medium, and a groove structure is provided in the intermediate metal layer. This effectively alleviates interfacial thermal stress, reduces the thermal resistance of the thermal interface material, provides support, buffers excessive compression of the surface thermally conductive medium under pressure, solves the overflow problem, and at the same time solves the change in solubility gradient caused by temperature gradient differences, avoids long-range migration of the surface thermally conductive medium material, and improves the structural stability and reliability of the material under thermal cycling.

[0109] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A thermal interface material, characterized in that, The thermal interface material includes: a thermally conductive substrate layer, an intermediate metal layer disposed on the upper and lower sides of the thermally conductive substrate layer, a plurality of groove units disposed on the surface of the intermediate metal layer, and a surface dielectric layer covering the surface of the intermediate metal layer.

2. The thermal interface material according to claim 1, characterized in that, The outer periphery extension length of the cross-section of the groove unit is 2-10 mm; Preferably, the minimum radial dimension of the cross-section of the groove unit is 0.5-2.5 mm; Preferably, the depth of the groove unit is 0.01-0.05 mm; Preferably, the spacing between adjacent groove units is 0.1-0.5 mm; Preferably, the groove units are arranged in an array.

3. The thermal interface material according to claim 1 or 2, characterized in that, The melting point of the intermediate metal layer material is higher than that of the surface dielectric layer material, and the difference between the two melting points is ≥50℃; Preferably, the melting point of the intermediate metal layer material is 120-250°C; Preferably, the material of the intermediate metal layer includes at least one of indium, tin, indium-tin alloy, indium-bismuth alloy, tin-bismuth alloy, indium-zinc alloy, or indium-silver alloy; Preferably, in the intermediate metal layer, the indium-tin alloy contains 40%-90% indium by mass and 10%-60% tin by mass. Preferably, in the intermediate metal layer, the indium-bismuth alloy contains 40%-55% indium by mass and 45%-60% bismuth by mass. Preferably, in the intermediate metal layer, the tin-bismuth alloy contains 50%-70% tin by mass and 30%-50% bismuth by mass. Preferably, in the intermediate metal layer, the indium-zinc alloy contains 90%-98% indium by mass and 2%-10% zinc by mass. Preferably, in the intermediate metal layer, the indium-silver alloy contains 95%-98% indium by mass and 2%-5% silver by mass. Preferably, the melting point of the material of the surface dielectric layer is 60-160℃; Preferably, the material of the surface dielectric layer includes at least one of indium tin bismuth eutectic alloy, indium bismuth eutectic alloy, or indium tin alloy; Preferably, in the surface dielectric layer, the indium-tin alloy contains 40%-90% indium by mass and 10%-60% tin by mass.

4. The thermal interface material according to any one of claims 1-3, characterized in that, The thickness of the intermediate metal layer is 0.01-0.05 mm; Preferably, the thickness between the surface of the surface dielectric layer and the upper surface of the intermediate metal layer is 0.003-0.05 mm.

5. The thermal interface material according to any one of claims 1-5, characterized in that, The material of the thermally conductive substrate layer includes at least one of copper, silver, gold, graphene film, or thermally conductive ceramic. Preferably, the thickness of the thermally conductive substrate layer is 0.01-5 mm.

6. A method for preparing a thermal interface material as described in any one of claims 1-5, characterized in that, The preparation method includes the following steps: After pretreating the upper and lower surfaces of the thermally conductive substrate, a first coating is applied using the material of the intermediate metal layer. Then, a textured film is used to form a grooved unit structure on the surface of the intermediate metal layer to obtain a composite substrate. A second coating is applied using the material of the surface dielectric layer to the surface of the composite substrate, and then cooled to obtain the thermal interface material.

7. The preparation method according to claim 6, characterized in that, The pretreatment method includes plasma treatment; Preferably, the temperature of the first coating is 150-300℃; Preferably, the coating speed is 10-30 mm / s; Preferably, the pressure of the first coating is 0.5-2 MPa.

8. The preparation method according to claim 6 or 7, characterized in that, The method for forming the groove unit structure includes: heating the coated thermally conductive substrate, covering the surface with a textured film, placing it under vacuum conditions, then keeping it at a constant temperature under an inert gas atmosphere, cooling it down after the heat preservation is completed, and peeling off the textured film. Preferably, the heating temperature is 0-5°C below the melting point of the intermediate metal layer material; Preferably, the vacuum degree of the vacuum condition is 10. -3 -10 -1 Pa; Preferably, the flow rate of the inert gas is 2-5 L / min; Preferably, the heat preservation time is 15-30 minutes.

9. The preparation method according to any one of claims 6-8, characterized in that, The temperature of the second coating is 0-10°C higher than the melting point of the surface dielectric layer material; Preferably, the second coating speed is 10-30 mm / s; Preferably, the pressure of the second coating is 0.5-2 MPa; Preferably, the cooling rate is 2-5°C / min; Preferably, the cooling atmosphere includes a nitrogen atmosphere and / or an argon atmosphere.

10. An application of the thermal interface material as described in any one of claims 1-5, characterized in that, The thermal interface material is used for chip thermal conductivity.

Images