An indium-based high-efficiency thermal conductive pad

Abstract

The present invention proposes a novel indium-based high-efficiency thermally conductive gasket, which uses indium metal and indium bismuth tin alloy as the material of the thermally conductive gasket, and rolls the indium metal and indium bismuth tin alloy into square metal sheets, which are cut and stacked and pressed to form a "dam-shaped" thermally conductive gasket with indium bismuth tin alloy on the upper and lower surfaces. By reducing the gap between the thermally conductive gasket itself and the chip and the heat sink, the contact thermal resistance is reduced to meet higher power heat dissipation requirements.

Description

Technical Field

[0001] The invention belongs to the C22C28 / 00 technical field, and specifically relates to a novel indium-based high-efficiency thermal conductive pad. Background Art

[0002] Indium sheet is a metal gasket commonly used in the electronics field as a thermal pad between chips and heat sinks. However, in actual use, since there are convex and concave contact points on the solid surfaces of the chip, indium sheet, heat sink, etc. that are in contact with each other, there will be a large number of gaps between the indium sheet and the heat sink and chip. The air in the gaps will cause the contact thermal resistance to be extremely high, reducing the heat dissipation effect of the chip.

[0003] Chinese patent CN105400497A discloses a metal thermal conductive paste, which is a compound of multiple metals and is made into a semi-solid thermal conductive paste at room temperature with a melting point of 45°C and good viscosity and fluidity, reducing the gaps between the surfaces of thermal interface materials, but the wettability of the thermal conductive paste and the thermal interface material is poor. Chinese patent CN112898929A discloses a liquid metal composite thermal interface material. In order to prevent the leakage of liquid metal during use, additives such as curing agent and coupling agent are added, but the addition of additives is equivalent to introducing impurities into the liquid metal, reducing the thermal conduction effect of the liquid metal. Chinese patent CN204369797U discloses a metal thermal conductive gasket, which uses a copper mesh as a metal mesh to fix the indium bismuth tin alloy, reducing the overflow of the indium bismuth tin alloy during the use of the thermal conductive gasket, but does not solve the problem of gaps between the thermal conductive gasket and the surface of the chip and the heat sink.

[0004] Based on this, in order to avoid the existence of gaps and to improve the thermal conductivity efficiency, the present invention proposes a new indium-based high-efficiency thermal conductive gasket, which is suitable for immersive servers and can improve the heat dissipation effect of the heat source chip of the immersive server. Summary of the invention

[0005] The first aspect of the present invention provides a novel indium-based high-efficiency thermal conductive gasket, the preparation raw materials of which include indium metal and liquid metal.

[0006] In a preferred embodiment, the constituent metal elements of the liquid metal include at least two of indium, bismuth, tin, gallium, zinc, aluminum, gold, silver, and cesium.

[0007] In a preferred embodiment, the constituent metal elements of the liquid metal are at least three of indium, bismuth, tin and gallium.

[0008] In a preferred embodiment, the constituent metal elements of the liquid metal are indium, bismuth and tin.

[0009] In a preferred embodiment, the mass ratio of indium, bismuth and tin is (24-26): (7-9): (16-18).

[0010] In a preferred embodiment, the melting temperature of the liquid metal is 55-65°C.

[0011] In a preferred embodiment, the melting temperature of the liquid metal is 60°C.

[0012] In the present application, the liquid metal is an indium bismuth tin alloy, which is purchased from Dongguan Guangtai Technology Co., Ltd. In the present application, the liquid metal sheet is an indium bismuth tin alloy sheet.

[0013] The second aspect of the present invention provides a method for preparing a novel indium-based high-efficiency thermally conductive pad, comprising the following steps:

[0014] (1) rolling indium metal into a first indium sheet having a thickness of 0.01-0.50 mm and a second indium sheet having a thickness of 0.01-0.50 mm;

[0015] (2) rolling the liquid metal into a liquid metal sheet with a thickness of 0.01-0.50 mm;

[0016] (3) Overlapping the first indium sheet, the second indium sheet, and the liquid metal sheet, and pressing them with a hot press to obtain the thermal conductive pad.

[0017] In a preferred embodiment, in step (1), the thickness of the first indium sheet is 0.01-0.05 mm, and the thickness of the second indium sheet is 0.05-0.10 mm.

[0018] In a preferred embodiment, the first indium sheet and the second indium sheet in step (1) are square indium sheets.

[0019] In a preferred embodiment, the first indium sheet in step (1) is an indium sheet having a central cavity, and the second indium sheet in step (1) is a solid indium sheet.

[0020] In a preferred embodiment, the thickness of the first indium sheet and the second indium sheet in step (1) is 1:(2-4).

[0021] In a preferred embodiment, in step (1), the thickness ratio of the first indium sheet to the second indium sheet is 1:3.

[0022] In a preferred embodiment, the thickness of the liquid metal sheet in step (2) and the first indium sheet in step (1) are the same.

[0023] In a preferred embodiment, the thickness of the liquid metal sheet and the first indium sheet is 0.03 mm.

[0024] In a preferred embodiment, the area of ​​the central cavity of the first indium sheet is the same as the area of ​​the liquid metal sheet.

[0025] In a preferred embodiment, the top view of the structure of the first indium sheet presents a “U-shape”.

[0026] In a preferred embodiment, the overlapping manner in step (3) is, from bottom to top, liquid metal sheet, first indium sheet, second indium sheet, first indium sheet, and liquid metal sheet.

[0027] There is a positive correlation between the melting temperature of liquid metal and the contact thermal resistance of liquid metal. The lower the melting temperature of liquid metal, the smaller the contact thermal resistance. In this application, the applicant selected liquid metal with a melting temperature of 60°C to reduce the contact thermal resistance of the thermal pad. However, liquid metal with a lower melting point is easier to transform into a liquid state and is more likely to undergo oxidation reaction when in contact with air. The thermal resistance of the oxidized liquid metal increases, which will directly affect the heat dissipation effect of the thermal pad.

[0028] During the experiment, the applicant found that by preparing the thermally conductive gasket into the shape described in this application, that is, the upper and lower surfaces of the thermally conductive gasket are a "U-shaped" first indium sheet filled with liquid metal, and a solid second indium sheet is arranged between the two first indium sheets. With such a structure, after the liquid metal melts, the liquid metal can fill the gaps between the indium sheets, drive out the air in the gaps between the indium sheets, maintain a vacuum state, and delay the oxidation of the liquid metal. In addition, the thermally conductive gasket of the present application is in direct contact with the heat source chip and the radiator. The liquid metal in the center of the upper and lower surfaces of the thermally conductive gasket can be in direct and close contact with the chip and the radiator in a molten state, and can also fill the gaps between the indium sheet and the chip and the radiator, reducing the presence of air, ensuring that heat is vertically transferred from the first indium sheet on one surface to the first indium sheet on another surface, or in the process of heat being vertically transferred from the chip to the radiator through the thermally conductive gasket, heat is dissipated with lower thermal resistance and higher thermal conductivity efficiency.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The thermally conductive gasket of the present invention is formed by hot pressing an indium sheet with a central cavity and a solid indium sheet to form a "dam-shaped" structure with cavities on both the upper and lower surfaces, and the cavity is filled with a liquid metal sheet. Such a structure can prevent the liquid metal from overflowing and flowing out in a liquid state.

[0031] 2. The present invention adopts liquid metal with a specific melting temperature, which remains in a solid state at room temperature. At the operating temperature, through phase change, the solid state is transformed into a liquid state, filling the gaps between the thermal gasket and the solid surfaces of the chip and the heat sink, and also filling the gaps between the indium sheets, thereby improving the contact tightness between the various layers of the thermal gasket, and also improving the close contact degree between the thermal gasket and the solid surfaces of the chip and the heat sink, reducing the contact thermal resistance by at least 50%, and meeting higher power heat dissipation requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a vertical cross-sectional structural diagram of the high-efficiency thermal conductive gasket of this application.

[0033] Figure 2 This is a top view of the high-efficiency thermal conductive gasket for this application.

[0034] Figure 3 Data test results of preparing a high-efficiency thermal conductive gasket for this application.

[0035] Among them, 1. a first indium sheet; 2. a second indium sheet; 3. an indium bismuth tin alloy sheet. DETAILED DESCRIPTION

[0036] Example 1

[0037] This embodiment proposes a novel indium-based high-efficiency thermal conductive pad, the raw materials for preparing the high-efficiency thermal conductive pad include indium metal and indium bismuth tin alloy. The indium bismuth tin alloy has a melting point of 60° C. and is purchased from Dongguan Guangtai Technology Co., Ltd.

[0038] The preparation steps of high-efficiency thermal conductive pads are as follows:

[0039] (1) Indium metal is rolled using a rolling machine to form a first indium sheet 1 with a thickness of 0.03 mm and a square second indium sheet 2 with a thickness of 0.09 mm;

[0040] (2) rolling the solid indium bismuth tin alloy by a rolling machine to form an indium bismuth tin alloy sheet 3 with a thickness of 0.03 mm;

[0041] (3) cutting the first indium sheet 1 and removing the central portion to form a "U-shaped" indium sheet with a central cavity;

[0042] (4) Cutting the indium-bismuth-tin alloy sheet 3 into a square shape, the size of which is the same as the size of the central cavity of the first indium sheet 1;

[0043] (5) stacking the indium bismuth tin alloy sheet 3, the first indium sheet 1, the second indium sheet 2, the first indium sheet 1, and the indium bismuth tin alloy sheet 3 in order from bottom to top, and after stacking, pressing with a hot press to obtain the thermal conductive pad.

[0044] Example 2

[0045] This embodiment proposes a novel indium-based high-efficiency thermal conductive pad, the raw materials for preparing the high-efficiency thermal conductive pad include indium metal and indium bismuth tin alloy. The indium bismuth tin alloy has a melting point of 60° C. and is purchased from Dongguan Guangtai Technology Co., Ltd.

[0046] The preparation steps of high-efficiency thermal conductive pads are as follows:

[0047] (1) Indium metal is rolled using a rolling machine to form a first indium sheet 1 with a thickness of 0.03 mm and a square second indium sheet 2 with a thickness of 0.09 mm;

[0048] (2) rolling the solid indium bismuth tin alloy by a rolling machine to form an indium bismuth tin alloy sheet 3 with a thickness of 0.03 mm;

[0049] (3) cutting the first indium sheet 1 and removing the central portion to form a "U-shaped" indium sheet with a central cavity;

[0050] (4) Cutting the indium-bismuth-tin alloy sheet 3 into a square shape, the size of which is the same as the size of the central cavity of the first indium sheet 1;

[0051] (5) The indium bismuth tin alloy sheet 3, the first indium sheet 1, and the second indium sheet 2 are stacked together in order from bottom to top. After the stacking is completed, they are pressed by a hot press to obtain the thermal conductive pad.

[0052] Comparative Example 1

[0053] This comparative example is a traditional pure indium thermal pad,

[0054] Performance Testing

[0055] The thermal resistance test of the thermally conductive gasket prepared in the embodiment was carried out, and the thermal resistance of the thermally conductive gasket was tested under the conditions of 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 PSI respectively, and the thermal resistance value under 40 PSI was recorded in Table 1.

[0056] Table 1

[0057] Example <![CDATA[Thermal resistance (cm 2 K / W)]]> Example 1 0.14 Example 2 0.10 Comparative Example 1 0.31

Claims

1. An indium-based high-efficiency thermally conductive pad, characterized in that: The raw materials for preparing the high-efficiency thermal conductive pad include indium metal and liquid metal; The constituent metal elements of the liquid metal are indium, bismuth and tin; the melting temperature of the liquid metal is 55-65° C.; the preparation method of the thermal conductive pad comprises the following steps: (1) rolling indium metal into a first indium sheet having a thickness of 0.01-0.50 mm and a second indium sheet having a thickness of 0.01-0.50 mm; (2) rolling the liquid metal into a liquid metal sheet with a thickness of 0.01-0.50 mm; (3) overlapping the first indium sheet, the second indium sheet, and the liquid metal sheet, and pressing them with a hot press to obtain the thermal conductive pad; In the step (1), the first indium sheet is an indium sheet with a central cavity, and in the step (1), the second indium sheet is a solid indium sheet.

2. The thermally conductive pad according to claim 1, characterized in that: The mass ratio of indium, bismuth and tin is (24-26):(7-9):(16-18).

3. A method for preparing a thermally conductive gasket according to any one of claims 1 to 2, characterized in that: The steps include: (1) rolling indium metal into a first indium sheet having a thickness of 0.01-0.50 mm and a second indium sheet having a thickness of 0.01-0.50 mm; (2) rolling the liquid metal into a liquid metal sheet with a thickness of 0.01-0.50 mm; (3) Overlapping the first indium sheet, the second indium sheet, and the liquid metal sheet, and pressing them with a hot press to obtain the thermal conductive pad.

4. The preparation method according to claim 3, characterized in that: In the step (1), the thickness of the first indium sheet is 0.01-0.05 mm, and the thickness of the second indium sheet is 0.05-0.10 mm.

5. The preparation method according to claim 3, characterized in that: The thickness of the liquid metal sheet in step (2) is the same as that of the first indium sheet in step (1).

6. The preparation method according to claim 3, characterized in that: The area of ​​the central cavity of the first indium sheet is the same as that of the liquid metal sheet.

7. The preparation method according to claim 3, characterized in that: The overlapping manner in the step (3) is, from bottom to top, liquid metal sheet, first indium sheet, second indium sheet, first indium sheet, and liquid metal sheet.

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