Foamed indium heat-conducting gasket as well as preparation method and application thereof

Abstract

The invention discloses a foamed indium heat-conducting gasket as well as a preparation method and application thereof. The foamed indium heat-conducting gasket comprises the following raw materials in parts by mass: 100 parts of pure indium ingot; 1-2 parts of a tackifier; 2-10 parts of a stabilizer; 2-10 parts of a foaming agent; wherein the purity of the pure indium ingot is greater than 99.9%. The raw materials are mixed according to preset parts by mass, and then the foamed indium heat-conducting gasket is obtained through a chemical foaming method. Compared with a traditional foam metal material, the prepared foam indium heat-conducting gasket has good ductility and flexibility, interface contact gaps can be effectively reduced after the foam indium heat-conducting gasket is pressed, and interface thermal resistance is reduced; when the working temperature change of the electronic device causes non-uniform thermal deformation between the materials, the thermal expansion mismatching phenomenon between the two matching surfaces can be effectively compensated; therefore, the actual heat-conducting effect of the foam indium heat-conducting gasket at high temperature is improved, and the reliability of an electronic device is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal conductive materials, and in particular relates to a foamed indium thermal conductive pad and a preparation method and application thereof. Background Art

[0002] For electronic devices, especially chips, integration, miniaturization and high power density are the hot spots and directions of their development. According to Moore's Law, the number of components that can be accommodated on an integrated circuit will double every 18 months; and with the advancement of the high integration of electronic devices, the heat generated will also increase significantly. Studies have shown that the increase in the junction temperature of the heat-generating components of electronic devices will cause changes in output power, forward voltage, and mean failure time; for example: when the junction temperature of the heat-generating components of electronic devices exceeds the operating temperature of the electronic devices, every increase of 1°C will cause the reliability of the electronic devices to decrease by 4%. Therefore, how to transfer the heat generated by high-power and high-density electronic devices to the heat dissipation components in a timely and effective manner and dissipate it in the air to achieve good thermal management is receiving more and more attention and attention from relevant researchers.

[0003] For thermal management of electronic devices, the efficiency of heat transfer from electronic devices to heat sinks is the lowest, which is the bottleneck of the entire heat transfer process; this bottleneck is mainly caused by the incomplete contact between the electronic device and the heat sink surface. The surface of the electronic device and the heat sink is not an ideal plane, but has a certain degree of roughness, so the contact between the two is actually point contact; and the air at the contact point between the two will seriously hinder the heat transfer of the electronic device, resulting in a significant increase in the interface contact thermal resistance. In addition, the difference in thermal expansion coefficients between the electronic device and the heat sink will also cause uneven deformation between the materials when the temperature changes. These deformations will inevitably lead to gaps between the surface of the electronic device and the heat sink, and cause the thermal conductivity to be further seriously reduced.

[0004] To solve the above problems, researchers have tried to use flexible elastomer interface materials or metal materials with high thermal conductivity as heat sinks to improve the heat transfer process. For example, CN 118388964 A discloses a thermally conductive gasket and a preparation method thereof, which uses silicone gel and methyl vinyl silica gel as the matrix, and bridges the interface gap during pressing by the high flexibility of the matrix to reduce the interface contact thermal resistance, and at the same time, adds a high number of thermally conductive fillers to the matrix to improve the overall thermal conductivity of the gasket. However, due to the poor thermal conductivity of the elastomer, the thermally conductive fillers added therein are still in the form of point contact even if a thermal conductive path is formed, resulting in the thermal conductivity of this gasket still being at a low level, which cannot meet the actual needs of high integrated circuit heat dissipation. CN108109975 A discloses a high thermal conductivity heat sink with a three-dimensional foam metal skeleton and a preparation method thereof, which uses foam copper as the skeleton material, realizes the effective conduction of heat transfer through the high thermal conductivity of the metal, and at the same time, composites high thermal conductivity materials inside and / or on the surface thereof, and utilizes the three-dimensional structure of the foam copper to enhance the thermal conductivity. Unfortunately, there is actually a problem of poor interface contact between high thermal conductivity materials and copper foam. At the same time, it should be noted that as the electronic device works, its temperature will rise. The change in temperature will cause thermal deformation of the copper foam and the surface material of the electronic device. Due to the different types of materials, there will be differences in the thermal expansion coefficients of the two. This difference will cause uneven deformation of the interface and produce interface gaps. The rigidity of copper foam is relatively large and it is difficult to fill these gaps. Therefore, as the operating temperature rises, the actual thermal conductivity of the copper foam heat sink will tend to decrease. Summary of the invention

[0005] In view of the above problems existing in the prior art, the embodiments of the present invention provide a foam indium thermal conductive pad and a preparation method and application thereof. The foam indium thermal conductive pad not only has the high thermal conductivity of the foam metal material, but also has good flexibility, so it can effectively reduce the interface contact thermal resistance of the foam indium thermal conductive pad and improve the thermal conductivity of the foam indium thermal conductive pad.

[0006] According to a first aspect of an embodiment of the present invention, a foamed indium thermal pad is provided, comprising the following raw materials in parts by mass: 100 parts of pure indium ingot; 1-2 parts of a tackifier; 2-10 parts of a stabilizer; and 2-10 parts of a foaming agent; wherein the purity of the pure indium ingot is greater than 99.9%.

[0007] Optionally, the foam indium thermally conductive gasket further comprises: 0-5 parts of a foaming aid; preferably, the foaming aid comprises 0.5-4 parts of the foaming aid.

[0008] Optionally, the viscosity enhancer is selected from one or more of metal calcium particles and alumina powder; the stabilizer is selected from one or more of alumina, silicon carbide, and metal magnesium; preferably, the stabilizer is metal magnesium; the foaming agent is selected from any one or more of azodicarbonamide, N,N-dinitrosopentamethyltetramine, diisopropyl azodicarboxylate and 4,4'-oxydibenzenesulfonylhydrazide.

[0009] Optionally, the foaming aid is selected from one or more of zinc oxide, zinc stearate, stearic acid, lead stearate, cadmium oxide and sodium bicarbonate.

[0010] According to the second aspect of an embodiment of the present invention, a method for preparing a foamed indium thermally conductive gasket is also provided, the method comprising: mixing the pure indium ingot, a viscosity enhancer, a stabilizer, a foaming agent, and / or the foaming aid according to preset mass fractions and then preparing the foamed indium thermally conductive gasket by a chemical foaming method.

[0011] Preferably, the preparation method includes: adding a viscosity enhancer and a stabilizer to the indium melt formed by the pure indium ingot, and obtaining an indium melt mixture after sufficient stirring; adding a foaming agent and / or a foaming aid to the indium melt mixture at a first preset temperature, and obtaining a foamed indium melt mixture after sufficient stirring; wherein the first preset temperature is greater than the melting point of the pure indium ingot; and after injection molding the foamed indium melt mixture, cutting it according to preset requirements to obtain a foamed indium thermal pad.

[0012] Preferably, a thickener and a stabilizer are added to the indium melt formed by the pure indium ingot, and an indium melt mixture is obtained after sufficient stirring; comprising: heating the pure indium ingot to 170-180°C and then keeping it warm for 20-30 minutes to obtain an indium melt; adding a thickener and a stabilizer to the indium melt and then sufficiently stirring it at a stirring paddle speed of 1000-1500r / min to generate an indium melt mixture.

[0013] Preferably, the method of adding a foaming agent and / or a foaming aid to an indium melt mixture at a first preset temperature and stirring the mixture sufficiently to obtain a foamed indium melt mixture comprises: heating the indium melt mixture to 190-220° C.; adding a foaming agent and / or a foaming aid to the heated indium melt mixture and stirring the mixture sufficiently to obtain a foamed indium melt mixture.

[0014] Preferably, the foamed indium melt mixture is injection molded and then cut according to preset requirements to obtain a foamed indium thermal pad; comprising: injecting the foamed indium melt mixture into a mold and keeping it warm at 190-220 degrees Celsius for 2-5 minutes; then cooling it to solidification, and taking out the foamed indium from the mold at 60-70°C; after the foamed indium is cooled to room temperature, cutting it according to a preset size to obtain a foamed indium thermal pad.

[0015] According to a third aspect of an embodiment of the present invention, there is also provided an application of a foamed indium thermally conductive gasket in an electronic device, wherein the foamed indium is attached to a surface of the electronic device and is used to transfer heat generated by the electronic device to a heat sink.

[0016] The embodiment of the present invention provides a foamed indium thermally conductive gasket and a preparation method and application thereof, wherein the foamed indium thermally conductive gasket comprises the following raw materials in parts by mass: 100 parts of pure indium ingot; 1-2 parts of a tackifier; 2-10 parts of a stabilizer; 2-10 parts of a foaming agent; wherein the purity of the pure indium ingot is greater than 99.9%. The above raw materials are mixed according to preset parts by mass, and the foamed indium thermally conductive gasket is obtained by a chemical foaming method. Compared with traditional foamed metal materials (such as foamed copper and foamed aluminum), the foamed indium thermally conductive gasket prepared by the present invention has good ductility and flexibility, which can not only effectively reduce the interface contact gap and reduce the interface thermal resistance after being compressed; but also effectively compensate for the thermal expansion mismatch between the two mating surfaces when the operating temperature of the electronic device changes and causes uneven thermal deformation between the materials; thereby improving the actual thermal conductivity effect of the foamed indium thermally conductive gasket at high temperatures, thereby improving the reliability of the electronic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0018] Figure 1 A schematic diagram of a process for preparing a foamed indium thermally conductive gasket provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0020] At present, for thermal management of electronic devices, the transfer of heat from electronic devices to heat sinks is the bottleneck of the entire heat conduction process. Due to the existence of surface roughness, it is often difficult to achieve ideal surface contact between the surface of electronic devices and the surface of heat sinks. Instead, point contact exists in the form of synaptic points, which is bound to cause serious interface gaps; the interface gaps are filled with air, and the thermal conductivity of air is only 0.02W / (m·k), which will seriously hinder the transfer of heat. Therefore, even if the thermal conductivity of the thermal interface material is high, it is still difficult to achieve good heat transfer when the interface gap is large. In addition, the different thermal expansion coefficients of electronic devices and heat sinks should also be taken seriously. Even if the electronic device and the heat sink are well fitted during installation and the interface gap is minimized as much as possible, when the electronic device is in working state, it will inevitably bring about a temperature rise, and the temperature rise will cause the electronic device material itself to have a volume thermal response. Due to the different interface materials between the electronic device and the heat sink, the resulting thermal expansion coefficients will bring different volume thermal response values, which will inevitably cause uneven deformation of the thermal interface, resulting in new interface gaps and affecting the heat transfer.

[0021] A foamed indium thermally conductive pad comprises the following raw materials in parts by mass: 100 parts of pure indium ingot; 1-2 parts of a tackifier; 2-10 parts of a stabilizer; 2-10 parts of a foaming agent; and 0-5 parts of a foaming aid. The purity of the pure indium ingot is greater than 99.9%.

[0022] The foamed indium thermally conductive pad is prepared by mixing the pure indium ingot, the tackifier, the stabilizer, the foaming agent, and / or the foaming aid according to preset mass fractions through a chemical foaming method.

[0023] Here, there is no limitation on the specific implementation process of the chemical foaming method, as long as the foamed indium thermal conductive gasket can be prepared.

[0024] In this embodiment, an appropriate amount of tackifier is added to the indium melt prepared from the pure indium ingot, which can improve the adhesion and adhesion of the finished foam indium thermal gasket; by adding an appropriate amount of stabilizer, the thermal stability and chemical stability of the foam indium thermal gasket can be improved; by adding an appropriate amount of foaming agent and / or foaming aid, tiny bubbles can be formed in the foam indium thermal gasket, and these bubbles not only help to increase the overall thermal conductivity of the foam indium thermal gasket (for example: the foaming structure can improve the thermal conductivity efficiency, because the presence of bubbles can promote the diffusion of heat and reduce thermal resistance), but also can reduce the weight of the thermal gasket, reduce the cost of the thermal gasket, and increase the vibration absorption performance of the thermal gasket.

[0025] In order to improve the flexibility and thermal conductivity of the foam indium thermal pad, in a preferred implementation of this embodiment, the viscosity enhancer is selected from one or more of metal calcium particles and aluminum oxide powder; the stabilizer is selected from one or more of aluminum oxide, silicon carbide, and metal magnesium; the foaming agent is selected from any one or more of azodicarbonamide, N,N-dinitrosopentamethyltetramine, diisopropyl azodicarboxylate and 4,4'-oxydibenzenesulfonylhydrazide.

[0026] In a more preferred implementation of this embodiment, the stabilizer is metallic magnesium; this is because metallic magnesium can reduce the surface tension of the indium melt, thereby inhibiting the rupture of the bubble walls, the merging of the bubbles and the collapse of the bubbles in the indium melt; thereby improving the overall thermal conductivity of the foam indium thermal gasket and reducing the weight of the foam indium thermal gasket.

[0027] In another preferred embodiment of this embodiment, the foaming agent is selected from one or more of zinc oxide, zinc stearate, stearic acid, lead stearate, cadmium oxide and sodium bicarbonate. The foaming agent can reduce the surface tension of the indium melt and promote the formation of bubbles in the indium melt, thereby helping to form a uniform foam structure during the manufacturing process of the foamed indium thermal pad, improving the foaming efficiency of the indium melt, and further improving the overall thermal conductivity and flexibility of the foamed indium thermal pad.

[0028] Compared with the traditional polymer elastomer thermal conductive pad, the foam indium thermal conductive pad prepared in this embodiment not only has good flexibility, but also has a higher thermal conductivity. In addition, the metal characteristics of the foam indium thermal conductive pad can also overcome the problems of aging and failure of the traditional polymer elastomer thermal conductive pad.

[0029] like Figure 1 , which is a schematic diagram of a process for preparing a foamed indium thermally conductive gasket provided by an embodiment of the present invention.

[0030] A method for preparing a foamed indium thermally conductive pad comprises at least the following steps:

[0031] S101, adding a viscosity enhancer and a stabilizer to an indium melt formed by a pure indium ingot, and stirring the mixture sufficiently to obtain an indium melt mixture;

[0032] S102, adding a foaming agent and / or a foaming aid to an indium melt mixture at a first preset temperature, and stirring the mixture sufficiently to obtain a foamed indium melt mixture; wherein the first preset temperature is greater than the melting point of a pure indium ingot;

[0033] S103, cutting the foamed indium melt mixture according to preset requirements after injection molding to obtain a foamed indium thermally conductive gasket.

[0034] Specifically, the pure indium ingot is heated to 170-180°C and kept warm for 20-30 minutes to obtain an indium melt; after adding a thickener and a stabilizer to the indium melt, the mixture is stirred at a stirring speed of 1000-1500r / min for 10-20 minutes to generate an indium melt mixture. The indium melt mixture is heated to 190-220°C; a foaming agent and / or a foaming aid is added to the heated indium melt mixture, and a stirring paddle is used to stir for 2-4 minutes until it is uniform to obtain a foamed indium melt mixture. The foamed indium melt mixture is injected into a mold and kept warm at 190-220 degrees Celsius for 2-5 minutes; then it is cooled to solidification, and the foamed indium is taken out from the mold at 60-70°C; after the foamed indium is cooled to room temperature, it is cut according to a preset size to obtain a foamed indium thermal pad.

[0035] Here, the solidified foamed indium is taken out from the mold at 60-70°C. This is mainly because indium is very active and a layer of indium oxide is easily formed on its surface. Taking it out of the mold and placing it in the air at a suitable temperature can form an oxide film on the surface of the foamed indium, thereby reducing the fluidity of the foamed indium and preventing leakage of the indium melt.

[0036] Compared with the foam metal using metal hydride as the foaming agent in the prior art, this embodiment innovatively uses the chemical foaming method to prepare foamed indium; this preparation method not only has the advantages of low energy consumption and easy control of foaming temperature, but also fills the gap in the prior art in the preparation method from metal indium to foamed indium.

[0037] The mass percentages in the following embodiments are all obtained with reference to the mass of the indium melt. For example, 1% of metallic calcium particles is used to indicate that the mass of the metallic calcium particles is 1% of the mass of the indium melt.

[0038] Example 1

[0039] A foamed indium thermally conductive pad comprises the following raw materials in parts by mass: 100 parts of pure indium ingot; 1 part of metal calcium particles; 3 parts of metal magnesium; 4 parts of 4,4'-oxydibenzenesulfonyl hydrazide; and 0.5 parts of stearic acid.

[0040] The preparation method of the above-mentioned foamed indium thermally conductive pad comprises the following steps:

[0041] S1, heating the pure indium ingot to 175°C, allowing it to stand for 20 minutes after being fully melted, and obtaining an indium melt;

[0042] S2, adding 1% by mass of metal calcium particles and 3% by mass of metal magnesium to the indium melt, and stirring the mixture at a speed of 1200 r / min for 15 minutes using a stirring paddle to obtain an indium melt mixture;

[0043] S3, adjusting the temperature of the indium melt mixture to 200° C., adding 0.5% by mass of stearic acid and 4% by mass of 4,4'-oxydibenzenesulfonylhydrazine to the indium melt mixture; and stirring the mixture uniformly with a stirring paddle to obtain a foamed indium melt mixture;

[0044] S4, injecting the foamed indium melt mixture into a mold and keeping it at 200°C for 3 minutes; then cooling it to solidification, and taking out the foamed indium from the mold at 60-70°C; after cooling it to room temperature, cutting it into 10cm*10cm, 0.3mm thick thermal conductive sheets to obtain foamed indium thermal conductive pads.

[0045] Example 2

[0046] A foamed indium thermally conductive pad comprises the following raw materials in parts by mass: 100 parts of pure indium ingots; 1 part of metal calcium particles; 3 parts of metal magnesium; 4 parts of diisopropyl azodicarboxylate; and 0.5 parts of stearic acid.

[0047] The preparation method of the above-mentioned foamed indium thermally conductive pad comprises the following steps:

[0048] S1, heating the pure indium ingot to 175°C, allowing it to stand for 20 minutes after being fully melted, and obtaining an indium melt;

[0049] S2, adding 1% by mass of metal calcium particles and 3% by mass of metal magnesium to the indium melt, and stirring the mixture at a speed of 1200 r / min for 15 minutes using a stirring paddle to obtain an indium melt mixture;

[0050] S3, adjusting the temperature of the indium melt mixture to 190° C., adding 0.5% by mass of stearic acid and 4% by mass of diisopropyl azodicarboxylate to the indium melt mixture; and stirring the mixture evenly with a stirring paddle to obtain a foamed indium melt mixture;

[0051] S4, injecting the foamed indium melt mixture into a mold and keeping it at 190°C for 3 minutes; then cooling it to solidification, and taking out the foamed indium from the mold at 60-70°C; after cooling it to room temperature, cutting it into 10cm*10cm, 0.3mm thick thermal conductive sheets to obtain foamed indium thermal conductive pads.

[0052] Example 3

[0053] A foamed indium thermally conductive pad comprises the following raw materials in parts by mass: 100 parts of pure indium ingots; 1 part of metal calcium particles; 3 parts of metal magnesium; 3 parts of N,N-dinitrosopentamethyltetramine; and 0.5 parts of stearic acid.

[0054] The preparation method of the above-mentioned foamed indium thermally conductive pad comprises the following steps:

[0055] S1, heating the pure indium ingot to 175°C, allowing it to stand for 20 minutes after being fully melted, and obtaining an indium melt;

[0056] S2, adding 1% by mass of metal calcium particles and 3% by mass of metal magnesium to the indium melt, and stirring the mixture at a speed of 1200 r / min for 15 minutes using a stirring paddle to obtain an indium melt mixture;

[0057] S3, adjusting the temperature of the indium melt mixture to 220° C., adding 0.5% by mass of stearic acid and 3% by mass of N,N-dinitrosopentamethyltetramine to the indium melt mixture; and stirring the mixture evenly with a stirring paddle to obtain a foamed indium melt mixture;

[0058] S4, injecting the foamed indium melt mixture into a mold and keeping it at 220°C for 3 minutes; then cooling it to solidification, and taking out the foamed indium from the mold at 60-70°C; after cooling it to room temperature, cutting it into 10cm*10cm, 0.3mm thick thermal conductive sheets to obtain foamed indium thermal conductive pads.

[0059] Comparative Example 1

[0060] A commercially available foam copper with a porosity of >90% was selected and cut into 10 cm*10 cm foam copper thermal conductive sheets with a thickness of 0.3 mm.

[0061] Performance Testing

[0062] The thermal conductive pads provided in the embodiment and the comparative example were tested for performance in the following manner:

[0063] Thermal conductivity: Tested according to ASTM D5470 international standard;

[0064] Elastic modulus test: Tested according to GB / T 22315-2008 national standard.

[0065] The test results are shown in Table 1:

[0066] Table 1 Performance parameters of thermally conductive gaskets in comparative examples and embodiments

[0067] sample Thermal conductivity (W / (m·k)) Elastic modulus (E / GPa) Comparative Example 9.0 84.0 Example 1 51.7 6.4 Example 2 43.9 6.9 Example 3 48.8 5.7

[0068] The test results show that compared with the foam copper thermal conductive gasket prepared by the traditional electrodeposition method in Comparative Example 1, the foam indium thermal conductive gasket prepared by the chemical foaming method in this embodiment not only has a higher thermal conductivity coefficient; but also the elastic modulus of the foam indium thermal conductive gasket is greatly reduced, and the low elastic modulus just brings higher flexibility to the foam indium thermal conductive gasket, thereby improving the flexibility of the foam indium thermal conductive gasket.

[0069] In the prior art, when electronic device materials respond to temperature, uneven deformation of the electronic device interface due to differences in thermal expansion coefficients will produce interface gaps, which will increase thermal resistance and reduce the actual thermal conductivity between the electronic device and the heat sink. The good flexibility of the foam thermal pad in the present application can reduce the interface gaps caused by the deformation of the electronic device interface, thereby improving the thermal conductivity between the electronic device and the heat sink.

[0070] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0071] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0072] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

[0073] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0074] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0075] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A foam indium thermally conductive pad, characterized in that: Including the following raw materials by mass: 100 parts of pure indium ingot; 1-2 parts of tackifier; Stabilizer 2-10 parts; 2-10 parts of foaming agent; Wherein, the purity of the pure indium ingot is greater than 99.9%.

2. The foamed indium thermally conductive pad according to claim 1, characterized in that: Also includes: 0-5 parts of foaming agent; preferably, 0.5-4 parts of the foaming agent.

3. The foamed indium thermally conductive pad according to claim 1, characterized in that: The viscosity enhancer is selected from one or more of metal calcium particles and aluminum oxide powder; The stabilizer is selected from one or more of aluminum oxide, silicon carbide, and metal magnesium; preferably, the stabilizer is metal magnesium; The foaming agent is selected from any one or more of azodicarbonamide, N,N-dinitrosopentamethyltetramine, diisopropyl azodicarboxylate and 4,4'-oxydibenzenesulfonylhydrazide.

4. The foamed indium thermally conductive pad according to claim 2, characterized in that: The foaming aid is selected from one or more of zinc oxide, zinc stearate, stearic acid, lead stearate, cadmium oxide and sodium bicarbonate.

5. A method for preparing a foamed indium thermally conductive pad, characterized in that: include: The pure indium ingot, the tackifier, the stabilizer, the foaming agent, and / or the foaming aid are mixed according to preset mass fractions and then prepared by a chemical foaming method to obtain a foamed indium thermal conductive pad.

6. The preparation method according to claim 5, characterized in that: include: Adding a viscosity enhancer and a stabilizer to the indium melt formed by the pure indium ingot, and stirring thoroughly to obtain an indium melt mixture; Adding a foaming agent and / or a foaming aid to an indium melt mixture at a first preset temperature, and stirring the mixture sufficiently to obtain a foamed indium melt mixture; wherein the first preset temperature is greater than the melting point of the pure indium ingot; The foamed indium melt mixture is injection molded and then cut according to preset requirements to obtain a foamed indium thermal conductive pad.

7. The method according to claim 6, characterized in that The step of adding a viscosity enhancer and a stabilizer to the indium melt formed by the pure indium ingot and stirring the mixture sufficiently to obtain an indium melt mixture comprises: The pure indium ingot is heated to 170-180° C. and then kept warm for 20-30 minutes to obtain an indium melt; After adding a viscosity enhancer and a stabilizer to the indium melt, the mixture is fully stirred at a stirring speed of 1000-1500 r / min to generate an indium melt mixture.

8. The method according to claim 6, characterized in that The method comprises adding a foaming agent and / or a foaming aid to the indium melt mixture at a first preset temperature, and stirring the mixture sufficiently to obtain a foamed indium melt mixture; comprising: The indium melt mixture is heated to 190-220° C.; A foaming agent and / or a foaming aid is added to the heated indium melt mixture, and the mixture is fully stirred to obtain a foamed indium melt mixture.

9. The method according to claim 6, characterized in that The foamed indium melt mixture is injection molded and then cut according to preset requirements to obtain a foamed indium thermal conductive pad; comprising: The foamed indium melt mixture is injected into a mold and kept at 190-220 degrees Celsius for 2-5 minutes; then cooled to solidify, and the foamed indium is taken out from the mold at 60-70 degrees Celsius; After the indium foam is cooled to room temperature, it is cut according to a preset size to obtain an indium foam thermal conductive pad.

10. An application of a foamed indium thermally conductive gasket in an electronic device, characterized in that: The foamed indium is attached to the surface of the electronic device and is used to transfer the heat generated by the electronic device to the heat sink.

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