High-thermal-conductivity silicone pad and preparation method therefor

Abstract

A high-thermal-conductivity silicone pad and a preparation method therefor, for use in preparing a silicone pad having high thermal conductivity and a great thickness. The high-thermal-conductivity silicone pad comprises a first thermally-conductive composite film, a first adhesive, a silicone pad, a second adhesive, and a second thermally-conductive composite film which are sequentially stacked from bottom to top. The preparation method for the high-thermal-conductivity silicone pad comprises the following steps: preparation of a thermally-conductive composite coating, degassing of adhesives, and assembly of the high-thermal-conductivity silicone pad.

Description

A high thermal conductivity silicone sheet and preparation method thereof Technical Field

[0001] The present invention belongs to the technical field of high thermal conductivity silicone sheet manufacturing, specifically to the application of new materials and new processes in silicone sheet manufacturing, and especially relates to a high thermal conductivity silicone sheet and a preparation method thereof, which can be used to prepare high-temperature thermal conductive and high-thickness silicone sheets. Background Art

[0002] Thermal conductive silicone sheet is a kind of thermal conductive medium material synthesized by special process with silicone as base material and various auxiliary materials such as metal oxides added. In the industry, it is also called thermal conductive silicone pad, thermal conductive silicone sheet, soft thermal conductive pad, thermal conductive silicone gasket, etc. It is specially produced for the design scheme of transferring heat through gaps. It can fill the gaps and open up the heat channel between the heating part and the heat dissipation part, effectively improving the heat transfer efficiency. At the same time, it also plays the role of insulation, shock absorption, sealing, etc., which can meet the design requirements of miniaturization and ultra-thin equipment. It is highly manufacturable and practical, and has a wide range of thickness applications. It is an excellent thermal conductive filling material. It is widely used in control motherboards of electronic and electrical products, internal and external pads and foot pads of motors, electronic appliances, automotive machinery, computer hosts, laptops, DVDs, VCDs and any materials that require filling and heat dissipation modules. However, the thermal conductive silicone sheets currently produced in my country have low thermal conductivity (thermal conductivity less than 10 W m -1 K -1 Due to issues such as low thickness (thickness above 10 mm) and immature manufacturing technology for double-sided adhesive and high-temperature film, it is difficult to achieve the same performance as American brands such as Bergquist and Laird. Therefore, my country still needs to import large quantities of thick, high-thermal-conductivity, and high-temperature-resistant thermal silicone sheets. Technical issues

[0003] In view of the problems of low thermal conductivity, low thickness, immature preparation technology of double-sided adhesive and back high-temperature film of thermal conductive silicone sheets currently produced in my country, the present invention optimizes the production process and materials of thermal conductive silicone sheets to prepare thermal conductive silicone sheets with high thermal conductivity, high thickness, double-sided stability and high temperature resistance. Technical Solutions

[0004] The present invention provides a high thermal conductivity silicone sheet and a preparation method thereof, wherein the high thermal conductivity silicone sheet comprises a first thermal conductive composite film, a first adhesive, a silicone sheet, a second adhesive, and a second thermal conductive composite film stacked in sequence from bottom to top; the preparation method of the high thermal conductivity silicone sheet comprises the following steps:

[0005] Preparation of S1 thermal conductive composite coating: Add high thermal conductivity medium to a multifunctional reactor, then add polydimethylsiloxane, evacuate the multifunctional reactor to a pressure of 10-20 kPa, then heat to 50-80°C and stir continuously at constant temperature for 1-3 hours;

[0006] Degassing of S2 adhesive: Place the adhesive in a vacuum reactor, set the temperature to 25°C, evacuate to 10~20kPa, and stir at constant temperature for 1~3 hours;

[0007] Assembly of S3 high thermal conductivity silicone sheet: a. Place the thermal conductive composite coating prepared in S1 into a cylindrical rotary coater, heat it to 120-180°C, and cure it for 0.5-1 hour to form a first thermal conductive composite film;

[0008] b. Then, the prepared first thermally conductive composite film is placed on a spin coater, and the degassed adhesive S2 is applied to the surface of the first thermally conductive composite film. The film is rotated at a speed of 7000 to 10000 rpm for 5 to 10 minutes to form a uniform first adhesive on the surface of the first thermally conductive composite film.

[0009] c. placing the silicone sheet on the surface of the first adhesive so that the silicone sheet and the first thermally conductive composite film are connected through the first adhesive;

[0010] d. Place the second adhesive on the surface of the silicone sheet and rotate it with a spin coater at a speed of 7,000 to 10,000 rpm for 5 to 10 minutes to evenly distribute the second adhesive on the surface of the silicone sheet;

[0011] e. Apply the thermally conductive composite coating prepared in S1 on the surface of the second adhesive, rotate it at a speed of 7000-10000 rpm for 5-10 minutes using a spin coater, then raise the temperature to 120-180°C and cure it for 0.5-1 hour, so that the thermally conductive composite coating is cured to form a second thermally conductive composite film, and the second adhesive is also cured to connect the second thermally conductive composite film to the silicone sheet.

[0012] In some embodiments, the high thermal conductivity medium in step S1 is a combination of one or more of copper powder, aluminum powder, aluminum oxide, silicon carbide, aluminum nitride, and graphite.

[0013] In some embodiments, the particle size of the high thermal conductivity medium in step S1 ranges from 0.1 to 40 μm.

[0014] In some embodiments, the mass ratio of the high thermal conductivity medium to polydimethylsiloxane in step S1 is 0.2:1 to 2:1.

[0015] In some embodiments, the adhesive in step S2 is a combination of one or more of AB glue, RTV1 organic silicone adhesive, RTV2 organic silicone adhesive, and polyacrylic resin.

[0016] In some embodiments, the thickness of the first thermally conductive composite film in step S3 is 1-5 mm.

[0017] In some embodiments, the thickness of the first adhesive in step S3 is 0.05-0.1 mm.

[0018] In some embodiments, the thickness of the silicone sheet in step S3 is 8-12 mm.

[0019] In some embodiments, the thickness of the second adhesive in step S3 is 0.05-0.1 mm.

[0020] In some embodiments, the thickness of the second thermally conductive composite film in step S3 is 1-5 mm. Beneficial effects

[0021] (1) By vacuum-preparing the thermally conductive composite coating, the air in the thermally conductive composite coating is largely eliminated, making the distribution of the thermal conductive medium in the first and second thermally conductive composite films cured later extremely dense. The thermal conductivity coefficient of the prepared thermally conductive silicone sheet is relatively high, reaching 12~20 W m -1 K -1 ;

[0022] (2) The silicone sheet is prepared by an industrially mature coating method, so that the components of the first and second thermally conductive composite films are evenly distributed, and a high-thickness thermally conductive silicone sheet can be prepared, with a thickness of up to 22 mm;

[0023] (3) A high-temperature resistant adhesive is used to bond the silicone sheet to the first and second thermally conductive composite films, thereby solving the problem of double-sided adhesive on the thermally conductive silicone sheet and making the thermally conductive silicone sheet have high-temperature resistant performance. Best Mode for Carrying Out the Invention

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings, technical process steps, specific implementation conditions and materials 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention. One embodiment of the present invention

[0025] Aluminum powder (particle size 20 µm) and polydimethylsiloxane at a mass ratio of 0.5:1 were added to a multifunctional reactor, and the pressure in the multifunctional reactor was evacuated to 10 kPa. The reactor was then heated to 70°C and stirred continuously at this temperature for 1 hour. AB glue was placed in a vacuum reactor, the temperature was set to 25°C, the pressure was evacuated to 10 kPa, and the temperature was stirred continuously for 1 hour. The prepared aluminum powder / polydimethylsiloxane thermal conductive composite coating was placed in a cylindrical rotary coater, heated to 180°C, and cured for 0.5 hours to form a first thermal conductive composite film. The prepared first thermal conductive composite film was then placed on the rotary coater, and the degassed AB glue was applied to the surface of the first thermal conductive composite film. The film was rotated at a speed of 7000 rpm for 10 minutes to form a uniform first adhesive on the surface of the first thermal composite film. A silicone sheet was placed on the surface of the first adhesive so that the silicone sheet and the first thermal conductive composite film were connected through the first adhesive. The degassed AB glue was then applied to the surface of the first thermal conductive composite film. The AB glue is placed on the surface of the silicone sheet and rotated at 10,000 rpm for 5 minutes using a spin coater to evenly distribute the second adhesive on the surface of the silicone sheet. The prepared aluminum powder / polydimethylsiloxane composite coating is applied to the surface of the second adhesive and rotated at 10,000 rpm for 5 minutes using a spin coater. The coating is then heated to 120°C and cured for 1 hour, allowing the thermally conductive composite coating to solidify into a second thermally conductive composite film. The second adhesive also solidifies, connecting the second thermally conductive composite film to the silicone sheet. In this embodiment, the thickness of the first thermally conductive composite film is 3 mm, the thickness of the first adhesive is 0.05 mm, the thickness of the silicone sheet is 8 mm, the thickness of the second adhesive is 0.05 mm, and the thickness of the second thermally conductive composite film is 2 mm.

[0026] The thermal conductivity of the prepared thermally conductive silicone sheet was tested according to ASTM F433-02 (2009, 2014) and was 12.56 W m -1 K -1 .

[0027] The prepared thermally conductive silicone sheet was baked at 200°C for 2 hours. The results showed that there was no adhesive on both sides of the thermally conductive silicone sheet. Another embodiment of the present invention

[0028] Copper powder (particle size 30 µm) and polydimethylsiloxane (PDMS) at a mass ratio of 1:1 were added to a multifunctional reactor. The reactor was evacuated to a pressure of 10 kPa, then heated to 80°C and stirred continuously at this temperature for 1 hour. RTV1 organic silicone adhesive was placed in a vacuum reactor, set to 25°C, evacuated to 10 kPa, and stirred at this temperature for 1 hour. The prepared copper powder / PDMS thermal conductive composite coating was placed in a rotary coater, heated to 150°C, and cured for 0.5 hours to form a first thermal conductive composite film. The first thermal conductive composite film was then placed on the rotary coater, and degassed RTV1 organic silicone adhesive was applied to the surface of the first thermal conductive composite film. The film was rotated at a speed of 10,000 rpm for 10 minutes to form a uniform first adhesive on the surface of the first thermal composite film. A silicone sheet was placed on the surface of the first adhesive, so that the silicone sheet and the first thermal conductive composite film were connected by the first adhesive. The degassed RTV1 organic silicone adhesive was then applied to the surface of the first thermal conductive composite film. RTV1 organic silicone adhesive was placed on the surface of the silicone sheet and rotated at 10,000 rpm for 5 minutes using a spin coater. The second adhesive was then evenly distributed on the surface of the silicone sheet. The prepared copper powder / polydimethylsiloxane composite coating was then applied to the surface of the second adhesive. The coating was rotated at 10,000 rpm for 5 minutes using a spin coater. The coating was then heated to 180°C and cured for 0.5 hours. This cured the thermally conductive composite coating to form a second thermally conductive composite film. The second adhesive also cured, connecting the second thermally conductive composite film to the silicone sheet. In this embodiment, the first thermally conductive composite film had a thickness of 4 mm, the first adhesive had a thickness of 0.08 mm, the silicone sheet had a thickness of 10 mm, the second adhesive had a thickness of 0.05 mm, and the second thermally conductive composite film had a thickness of 1 mm.

[0029] The thermal conductivity of the prepared thermally conductive silicone sheet was tested according to ASTM F433-02 (2009, 2014) and was 22.71 W m -1 K -1 .

[0030] The prepared thermally conductive silicone sheet was baked at 200°C for 2 hours. The results showed that there was no adhesive on both sides of the thermally conductive silicone sheet. Another embodiment of the present invention

[0031] Aluminum nitride and polydimethylsiloxane with a mass ratio of 0.5:1 are added to the multifunctional reactor in sequence, and the pressure in the multifunctional reactor is evacuated to 20kPa, and then the temperature is raised to 80°C and stirred continuously at a constant temperature for 1 hour; RTV2 organic silicone adhesive is placed in a vacuum reactor, the temperature is set to 25°C, the pressure is raised to 10kPa, and the temperature is stirred continuously for 1 hour. The prepared aluminum nitride / polydimethylsiloxane thermal conductive composite coating is placed in a cylindrical rotary coater, the temperature is raised to 180°C, and after curing for 0.5 hours, a first thermal conductive composite film is formed; the prepared first thermal conductive composite film is then placed on the rotary coater, and the degassed RTV2 organic silicone adhesive is coated on the surface of the first thermal conductive composite film. After rotating at a speed of 7000 rpm for 10 minutes, a uniform first adhesive is formed on the surface of the first thermal composite film; a silicone sheet is placed on the surface of the first adhesive so that the silicone sheet and the first thermal conductive composite film are connected through the first adhesive; the RTV2 organic silicone adhesive is placed on the surface of the first adhesive. A silicone adhesive is placed on the surface of a silicone sheet and rotated at 7000 rpm for 5-10 minutes using a spin coater to form a second adhesive, which is evenly distributed on the surface of the silicone sheet. The prepared aluminum nitride / polydimethylsiloxane thermally conductive composite coating is applied to the surface of the second adhesive and rotated at 7000 rpm for 10 minutes using a spin coater. The coating is then heated to 180°C and cured for 0.5 hours, allowing the thermally conductive composite coating to solidify into a second thermally conductive composite film. The second adhesive also solidifies, connecting the second thermally conductive composite film to the silicone sheet. In this embodiment, the thickness of the first thermally conductive composite film is 2 mm, the thickness of the first adhesive is 0.055 mm, the thickness of the silicone sheet is 12 mm, the thickness of the second adhesive is 0.1 mm, and the thickness of the second thermally conductive composite film is 3 mm.

[0032] The thermal conductivity of the prepared thermally conductive silicone sheet was tested according to ASTM F433-02 (2009, 2014) and was 18.39 W m -1 K -1 .

[0033] The prepared thermally conductive silicone sheet was baked at 200°C for 2 hours. The results showed that there was no adhesive on both sides of the thermally conductive silicone sheet. Another embodiment of the present invention

[0034] Silicon carbide (particle size 500 nm) and polydimethylsiloxane (PDMS) in a mass ratio of 2:1 were added to a multifunctional reactor. The reactor was evacuated to a pressure of 10 kPa, then heated to 80°C and stirred continuously at this temperature for 1 hour. RTV2 organic silicone adhesive was placed in a vacuum reactor, set to 25°C, evacuated to 10 kPa, and stirred continuously at this temperature for 1 hour. The prepared silicon carbide / PDMS thermal conductive composite coating was placed in a cylindrical rotary coater, heated to 180°C, and cured for 0.5 hours to form a first thermal conductive composite film. The prepared first thermal conductive composite film was then placed on the rotary coater, and degassed RTV2 organic silicone adhesive was applied to the surface of the first thermal conductive composite film. After rotating at a speed of 10,000 rpm for 10 minutes, a uniform first adhesive was formed on the surface of the first thermal composite film. A silicone sheet was placed on the surface of the first adhesive, so that the silicone sheet and the first thermal conductive composite film were connected through the first adhesive. RTV2 organic silicone adhesive was placed on the surface of the silicone sheet and rotated at 10,000 rpm for 5 minutes using a spin coater. The second adhesive was then evenly distributed on the surface of the silicone sheet. The prepared silicon carbide / polydimethylsiloxane composite coating was then applied to the surface of the second adhesive. The coating was then rotated at 10,000 rpm for 5 minutes using a spin coater. The coating was then heated to 180°C and cured for 0.5 hours. This cured the thermally conductive composite coating to form a second thermally conductive composite film. The second adhesive also cured, connecting the second thermally conductive composite film to the silicone sheet. In this embodiment, the first thermally conductive composite film was 5 mm thick, the first adhesive was 0.08 mm thick, the silicone sheet was 12 mm thick, the second adhesive was 0.05 mm thick, and the second thermally conductive composite film was 2 mm thick.

[0035] The thermal conductivity of the prepared thermally conductive silicone sheet was tested according to ASTM F433-02 (2009, 2014) and was 20.82 W m -1 K -1 .

[0036] The prepared thermally conductive silicone sheet was baked at 200°C for 2 hours. The results showed that there was no adhesive on both sides of the thermally conductive silicone sheet.

[0037] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A high thermal conductivity silicone sheet and its preparation method, Characterized in that, The high thermal conductivity silicone sheet includes a first thermal conductive composite film, a first adhesive, a silicone sheet, a second adhesive, and a second thermal conductive composite film stacked in sequence from bottom to top; the preparation method of the high thermal conductivity silicone sheet includes the following steps: S1 Preparation of the thermal conductive composite coating: Add a high thermal conductivity medium to a multi-functional reaction kettle, then add polydimethylsiloxane, evacuate to a pressure of 10 - 20 kPa in the multi-functional reaction kettle, and then heat up to 50 - 80 °C, and continuously stir at a constant temperature for 1 - 3 hours; S2 Degassing of the adhesive: Place the adhesive in a vacuum reaction kettle, set the temperature at 25 °C, evacuate to 10 - 20 kPa, and stir at a constant temperature for 1 - 3 hours; S3 Assembly of the high thermal conductivity silicone sheet: a. Place the thermal conductive composite coating prepared in S1 into a cylindrical rotary coater, heat up to 120 - 180 °C, and after curing for 0.5 - 1 hour, form a first thermal conductive composite film; b. Then place the prepared first thermal conductive composite film on the rotary coater, coat the adhesive degassed in S2 on the surface of the first thermal conductive composite film, and rotate at a speed of 7000 - 10000 revolutions per minute for 5 - 10 minutes to form a uniform first adhesive on the surface of the first thermal composite film; c. Place the silicone sheet on the surface of the first adhesive, so that the silicone sheet is connected to the first thermal conductive composite film through the first adhesive; d. Place the second adhesive on the surface of the silicone sheet, and rotate at a speed of 7000 - 10000 revolutions per minute for 5 - 10 minutes with the help of the rotary coater, so that the second adhesive is evenly distributed on the upper surface of the silicone sheet; e. Coat the thermal conductive composite coating prepared in S1 on the surface of the second adhesive, rotate at a speed of 7000 - 10000 revolutions per minute for 5 - 10 minutes with the help of the rotary coater, and then heat up to 120 - 180 °C and cure for 0.5 - 1 hour, so that the thermal conductive composite coating cures to form a second thermal conductive composite film, and the second adhesive will also cure to connect the second thermal conductive composite film to the silicone sheet.

2. The high thermal conductivity silicone sheet and its preparation method according to claim 1, Characterized in that, The high thermal conductivity medium in step S1 is one or a combination of copper powder, aluminum powder, alumina, silicon carbide, aluminum nitride, graphite.

3. The high thermal conductivity silicone sheet and its preparation method according to claim 1 or 2, Characterized in that, The particle size range of the high thermal conductivity medium in step S1 is 0.1 - 40 µm.

4. The high thermal conductivity silicone sheet and its preparation method according to claim 1, Characterized in that, The mass ratio of the high thermal conductivity medium to polydimethylsiloxane in step S1 is 0.2:1 - 2:

1.

5. The high thermal conductivity silicone sheet and its preparation method according to claim 1, Characterized in that, The adhesive in step S2 is one or a combination of AB glue, RTV1 type silicone adhesive, RTV2 type silicone adhesive, polyacrylic resin.

6. The high thermal conductivity silicone sheet and its preparation method according to claim 1, Characterized in that, The thickness of the first thermally conductive composite film in the step S3 is 1 to 5 mm.

7. The high thermal conductivity silicone sheet and its preparation method according to claim 1, characterized in that, the thickness of the first adhesive in the step S3 is 0.05 to 0.1 mm.

8. The high thermal conductivity silicone sheet and its preparation method according to claim 1, characterized in that, the thickness of the silicone sheet in the step S3 is 8 to 12 mm.

9. The high thermal conductivity silicone sheet and its preparation method according to claim 1, characterized in that, the thickness of the second adhesive in the step S3 is 0.05 to 0.1 mm.

10. The high thermal conductivity silicone sheet and its preparation method according to claim 1, characterized in that, the thickness of the second thermally conductive composite film in the step S3 is 1 to 5 mm.