Variable-dimension adjustable graphene high-thermal-conductivity gasket and preparation method thereof

Abstract

The invention discloses a variable-dimension adjustable graphene high-thermal-conductivity gasket and a preparation method thereof.The thermal-conductivity gasket comprises a gasket body and a covered edge, the gasket body is made of a modified graphene thermal-conductivity material, and the covered edge is made of an adhesive tape; the covered edge comprises a covered edge part which is adhered to the peripheral side wall of the gasket body and an extension part which is adhered to the edges of the two surfaces of the gasket body. A common graphene gasket is modified by means of thermoplastic polyurethane modification, foaming regulation and control, modified graphene layer number regulation and control, laser pore-forming regulation and control and the like, and the graphene-based heat-conducting gasket which is high in heat conductivity coefficient, good in elasticity, good in warping resistance and good in stability is developed.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor heat dissipation technology, specifically relating to a variable-dimensional tunable graphene high thermal conductivity pad and its preparation method. Background Technology

[0003] Intelligent computing chips are the brains of smart electronic products and cannot be overheated. Higher computing power and higher chip power density can lead to heat buildup, creating a dammed-up effect that causes electronic products to throttle down, crash, and pose safety hazards. Chip heat accumulation follows a 10°C rule: for every 10°C increase in chip temperature, the mean time between failures (MTBF) of electronic components decreases by 30%-50%, and chip performance drops by 25%.

[0004] Therefore, thermal management is crucial for the efficient operation of intelligent computing chips. If thermal management fails, the chip will experience thermal runaway, directly bearing the combined effects of mechanical pressure and thermal stress, leading to two major problems: pressure runaway and warpage failure. The chip's stress condition is critical; a GPU bare chip pressure exceeding 70 psi requires immediate alarm, with edge stress concentration areas being the first to crack. Warpage exceeding 100 μm causes the thermal interface material to fail, resulting in solder joint breakage. These two problems ultimately lead to the failure of the intelligent computing chip, causing significant losses.

[0005] According to authoritative statistics, intelligent computing chips are involved in multiple high-tech fields such as aerospace, military industry, and new energy vehicles. The efficient thermal management of intelligent computing chips is a market worth hundreds of billions of yuan with a growth rate of 10%, and has huge development potential.

[0006] As a critical thermal interface material (TIM) between the chip and the heat sink, the performance of thermal pads directly determines the effectiveness of the thermal management system. Common thermal pads on the market include thermal grease, phase change thermal pads, and indium tinplate; however, the performance of these conventional thermal pads cannot meet the stringent requirements of high-power, highly integrated AI bare chips. Breakthroughs in thermal management materials have become a key bottleneck in the development of intelligent computing chips. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a variable-dimensional adjustable graphene high thermal conductivity pad and its preparation method. The thermal conductivity pad of this invention has high thermal conductivity, good elasticity, good anti-warping performance, and good stability.

[0008] The technical solution adopted to achieve the above-mentioned objectives of this invention is as follows: A variable-dimensional tunable graphene high thermal conductivity pad includes a pad body and an edge banding. The pad body is made of modified graphene thermal conductive material, and the edge banding is made of adhesive tape. The edge banding includes an edge portion bonded to the four sides of the pad body and an extension portion bonded to the edges of the two surfaces of the pad body.

[0009] The gasket body is square, with a length of 2-7mm, a width of 1-6mm, a thickness of 0.03-2mm, an edge thickness of 0.08mm-0.5mm, an extension thickness of 0.1-0.6mm, and an extension width of 0.1-0.5mm.

[0010] The tape in question is a yellow polyimide tape.

[0011] A method for preparing a dimensionally tunable graphene high thermal conductivity pad includes the following steps: S1. Graphene oxide is dispersed in water and exfoliated to obtain a graphene oxide suspension. Copper powder is added to the graphene oxide suspension at a mass ratio of 5-7:3-5. The mixture is stirred evenly to obtain a turbid liquid. S2. Add thermoplastic polyurethane elastomer resin to the turbid liquid. The mass ratio of thermoplastic polyurethane elastomer resin to graphene oxide and copper powder is 1-5:1-5. Continue to mix evenly. Then add thermoplastic phenolic resin curing agent. The mass ratio of thermoplastic phenolic resin curing agent to polyurethane elastomer resin is 0.2-3:0.8-12. Mix evenly to obtain the coating material. S3. Coating material is applied to the substrate, cured into a film, and the film is peeled off to obtain a graphene oxide film. S4. Reduce the graphene oxide film at 2000-3000℃ in an inert gas environment for 10-30 minutes to obtain a graphene thermal conductive film. S5. Mix the graphene thermal conductive film, expandable microspheres and polyethylene glycol evenly at room temperature, then heat to 1000-1600℃ and anneal at 1000-1600℃ for 2-8 h to obtain a single-layer modified graphene thermal conductive film with high porosity and low defects. S6. When stacking multiple layers of single-layer modified graphene thermal conductive film, first, a vacuum is drawn. In a vacuum environment, a layer of epoxy resin structural adhesive is coated on the first layer of modified graphene thermal conductive film. Then, the second layer of modified graphene thermal conductive film is placed on the first layer of modified graphene thermal conductive film. Then, another layer of epoxy resin structural adhesive is coated on the second layer of modified graphene thermal conductive film. This process is repeated until the target height is reached. After the epoxy resin structural adhesive is cured, a graphene film block is obtained. S7. Die-cut the graphene film block according to the shape and size of the gasket body to obtain the graphene film sheet; S8. The graphene film is modified by laser scanning to create holes. The area of ​​the graphene film modified by creating holes is 5-30% of the total area of ​​the graphene film, and the pad body is obtained. S9. Use adhesive tape to cover the edges of both surfaces and the four sides of the gasket body to obtain the variable-dimensional adjustable graphene high thermal conductivity gasket.

[0012] The copper powder is in flake form, and the substrate is a tin-plated steel plate.

[0013] In step S2, before adding the thermoplastic phenolic resin curing agent, a polyurethane diluent is added to the uniform mixture formed by the turbid liquid and the polyurethane resin. The mass ratio of the polyurethane diluent to the thermoplastic polyurethane elastomer resin is [value missing], and the mixture is continued to be mixed evenly.

[0014] The polyurethane diluent is selected from at least one of ethyl acetate, alcohol, acetone, and pyrrolidone.

[0015] The method for curing and forming the film is as follows: After applying the coating material to the substrate, let the substrate stand at room temperature for 4-7 hours, then heat it at 70-90℃ for 1-5 hours, and finally cool it.

[0016] In step S5, the heating rate is 80-120℃ / min, the initial particle size of the expandable microspheres is 0.005-0.09mm, and the expansion rate of the expanded microspheres in the vertical direction is 800-1000%, while the expansion rate in the horizontal direction does not exceed 5%.

[0017] The method for using the epoxy resin structural adhesive is as follows: After repeated stacking to the target height, place the stack at 50-80℃, evacuate for 1-3 hours, and finally cool.

[0018] The laser-assisted hole-forming modification method is as follows: The graphene film was scanned with a laser with a power of 1000W-5000W and a pulse frequency of 1kHz-10kHz at a scanning speed of 10mm / s-100mm / s.

[0019] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. This invention modifies graphene oxide with thermoplastic polyurethane elastomer resin, which can significantly increase the anti-warping ability and adaptability pressure of thermal pads without significantly reducing thermal conductivity.

[0020] 2. This invention modifies the thermal pad by creating holes through laser scanning, which is not only simple to operate, but also significantly improves the elastic recovery rate of the thermal pad. Detailed Implementation

[0021] To facilitate understanding and implementation of the present invention by those skilled in the art, the present invention will be further described in detail below with reference to embodiments. It should be understood that the embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0022] The sources of the raw materials used in the following examples and comparative examples are as follows: The thermoplastic polyurethane elastomer resin (TPU) was purchased from Shanghai Huide Technology Co., Ltd., series 35. The thermoplastic phenolic resin curing agent was purchased from Henan Binhai Industrial Co., Ltd., and the thermoplastic phenolic resin was 5400. The expandable microspheres were purchased from Suzhou Bitai Materials Technology Co., Ltd., model 46100. The epoxy adhesive was purchased from 3M™ Scotch-Weld™, Epoxy Adhesive 2214.

[0023] Example 1 A variable-dimensional tunable graphene high thermal conductivity pad includes a pad body and an edge. The pad body is made of modified graphene thermal conductive material, and the pad body is square, with a length of 3mm, a width of 5mm, and a thickness of 0.20mm.

[0024] The edging includes an edging portion bonded to the four sides of the gasket body and an extension portion bonded to the edges of both surfaces of the gasket body. The edging thickness is 0.08 mm, the extension thickness is 0.10 mm, and the extension width is 0.5 mm. The edging material is yellow polyimide tape. The edging enhances the insulation of the gasket body, improves its mechanical strength and stability, and also prevents the modified graphene powder on the gasket body from falling off.

[0025] Example 2 The preparation method of the variable-dimensional tunable graphene high thermal conductivity pad in Example 1 is as follows: S1. Graphene oxide is dispersed in deionized water and ultrasonically exfoliated to obtain a graphene oxide suspension with a mass concentration of 1%. The copper flakes and graphene oxide suspension are added to a paint disperser according to a mass ratio of 1:1 and stirred evenly to obtain a turbid liquid.

[0026] S2. According to the mass ratio of thermoplastic polyurethane elastomer resin TPU to graphene oxide and copper powder of 3:2, add thermoplastic polyurethane elastomer resin TPU to the turbid liquid, continue to stir evenly, then add ethyl acetate according to the mass ratio of ethyl acetate to thermoplastic polyurethane elastomer resin TPU of 1:500, stir rapidly for 30 minutes to fully disperse, and obtain the mixture. S3. Add thermoplastic phenolic resin curing agent to the mixture according to the mass ratio of thermoplastic phenolic resin curing agent to thermoplastic polyurethane elastomer resin of 1:4, stir evenly, and obtain coating material. S4. Use sandpaper to polish the tin-plated steel sheet to remove oil and impurities from the surface of the tin-plated steel sheet, and then wipe the polished tin-plated steel sheet clean with alcohol. S5. The coating material is evenly coated on the tin-plated steel plate treated in step S4. Then the tin-plated steel plate is placed at room temperature for 5 hours, then heated in an oven at 80°C for 3 hours, and then cooled to room temperature. The cured film is carefully peeled off from the edge with a sharp tool such as a blade to obtain a graphene oxide film. S6. The graphene oxide film was heated at 2500℃ and in an inert gas environment for 20 minutes. The reduction was achieved by thermally decomposing oxygen-containing functional groups and repairing the interlayer structure, thus obtaining a graphene thermal conductive film. S7. Expandable microspheres and polyethylene glycol are added to the graphene thermal conductive film. The polyethylene glycol weakens the hydrogen bonds between GO layers, and the expansion of the microspheres pushes the graphene thermal conductive film to slide. After mixing evenly at room temperature, the mixture is placed between two plates of a hot press. The hot press is then heated to 1600°C at a heating rate of 100°C / min and annealed at 1600°C for 2 hours to obtain a single-layer modified graphene thermal conductive film with high porosity and low defects. S8. When stacking multiple layers of single-layer modified graphene thermal conductive film, a vacuum is first drawn to prevent air bubbles from reducing the performance of the graphene thermal conductive film. Under vacuum, an epoxy resin structural adhesive is coated on the first layer of modified graphene thermal conductive film, and then the second layer of modified graphene thermal conductive film is placed on the first layer of modified graphene thermal conductive film to obtain a stack. The stack is placed at 70°C and vacuumed for 2 hours, and then cooled to room temperature to obtain a graphene film block. S9. The graphene film block is die-cut with diamond wire according to the shape and size of the gasket body to obtain the graphene film sheet. S10. A laser with a power of 3000W and a pulse frequency of 5kHz is used to scan and modify the graphene film to create holes. The area of ​​the graphene film to be modified by creating holes is 20% of the total area of ​​the graphene film. The scanning speed is 75mm / s to obtain the pad body. S11. Use adhesive tape to cover the edges of both surfaces and the four sides of the gasket body to obtain the variable-dimensional adjustable graphene high thermal conductivity gasket.

[0027] The performance comparison between the variable-dimensional tunable graphene high thermal conductivity pad prepared in this embodiment and conventional pads is shown in Table 1 below: Table 1. Performance comparison between variable-dimensional tunable graphene high thermal conductivity pads and conventional pads As shown in Table 1, compared with conventional pads such as thermally conductive silicone grease, phase change thermal pads, and indium metal sheets, the variable-dimensional adjustable graphene high thermal conductivity pad prepared in this embodiment has significantly improved thermal conductivity, anti-warping ability, and other properties. Moreover, the variable-dimensional adjustable graphene high thermal conductivity pad prepared in this embodiment has an adaptability pressure of 40~100psi, indicating that it has good pressure resistance and heat dissipation performance.

[0028] By varying the amount of heat-shrinkable polyurethane elastomer resin (TPU) added, i.e., changing the mass ratio of TPU to graphene oxide and copper powder, different thermal conductive pads were obtained. The performance of the different thermal conductive pads is shown in the table below: By comparing Examples 2-5 and Comparative Example 1, it can be seen that without the addition of heat-shrinkable polyurethane elastomer resin (TPU), the thermal conductivity, anti-warping ability, and fitting pressure of the thermal pad are significantly reduced. When the amount of heat-shrinkable polyurethane elastomer resin (TPU) reaches a certain level, the thermal conductivity, anti-warping ability, and fitting pressure of the thermal pad no longer change when more heat-shrinkable polyurethane elastomer resin (TPU) is added.

[0029] By changing the porosity of the graphene film, i.e., changing the proportion of the area modified by laser scanning to the total area of ​​the graphene film, different thermal pads were obtained. The performance of the different thermal pads is shown in the table below: It can be seen that as the porosity increases, the thermal conductivity decreases, while the elastic recovery rate continuously increases.

[0030] The thermal pads obtained by varying the thickness of the graphene block (here, thickness refers to the thickness of the layers stacked according to step 8 of Example 2) are shown in the table below. It can be seen that as the thickness of the graphene block increases, the thermal conductivity and fitting pressure of the thermal pad decrease, while the anti-warping ability increases.

Claims

1. A variable-dimensional tunable graphene high thermal conductivity pad, characterized in that: It includes a gasket body and an edge banding. The gasket body is made of modified graphene thermal conductive material, and the edge banding is made of adhesive tape. The edge banding includes an edge banding portion bonded to the four sides of the gasket body and an extension portion bonded to the edges of the two surfaces of the gasket body.

2. The variable-dimensional tunable graphene high thermal conductivity pad according to claim 1, characterized in that: The gasket body is square, with a length of 2-7mm, a width of 1-6mm, a thickness of 0.03-2mm, an edge thickness of 0.08-0.5mm, an extension thickness of 0.1-0.6mm, and an extension width of 0.1-0.5mm.

3. The variable-dimensional tunable graphene high thermal conductivity pad according to claim 1, characterized in that: The tape in question is a yellow polyimide tape.

4. A method for preparing the variable-dimensional tunable graphene high thermal conductivity pad according to claim 1, characterized in that... Includes the following steps: S1. Disperse graphene oxide in water and exfoliate it to obtain a 0.5-3 wt% graphene oxide suspension. Add copper powder to the graphene oxide suspension. The mass ratio of copper powder to graphene oxide is 5-7:3-5. Mix evenly to obtain a turbid liquid. S2. Add thermoplastic polyurethane elastomer resin to the turbid liquid. The mass ratio of thermoplastic polyurethane elastomer resin to graphene oxide and copper powder is 1-5:1-5. Continue to mix evenly. Then add thermoplastic phenolic resin curing agent. The mass ratio of thermoplastic phenolic resin curing agent to polyurethane elastomer resin is 0.2-3:0.8-12. Mix evenly to obtain the coating material. S3. Coating material is applied to the substrate, cured into a film, and the film is peeled off to obtain a graphene oxide film. S4. Reduce the graphene oxide film at 2000-3000℃ in an inert gas environment for 10-30 minutes to obtain a graphene thermal conductive film. S5. Mix the graphene thermal conductive film, expandable microspheres and polyethylene glycol evenly at room temperature, then heat to 1000-1600℃ and anneal at 1000-1600℃ for 2-8 h to obtain a single-layer modified graphene thermal conductive film with high porosity and low defects. S6. When stacking multiple layers of single-layer modified graphene thermal conductive film, first, a vacuum is drawn. In a vacuum environment, a layer of epoxy resin structural adhesive is coated on the first layer of modified graphene thermal conductive film. Then, the second layer of modified graphene thermal conductive film is placed on the first layer of modified graphene thermal conductive film. Then, another layer of epoxy resin structural adhesive is coated on the second layer of modified graphene thermal conductive film. This process is repeated until the target height is reached. After the epoxy resin structural adhesive is cured, a graphene film block is obtained. S7. Die-cut the graphene film block according to the shape and size of the gasket body to obtain the graphene film sheet; S8. The graphene film is modified by laser scanning to create holes. The area of ​​the graphene film modified by creating holes is 5-30% of the total area of ​​the graphene film, and the pad body is obtained. S9. Use adhesive tape to cover the edges of both surfaces and the four sides of the gasket body to obtain the variable-dimensional adjustable graphene high thermal conductivity gasket.

5. The method for preparing the variable-dimensional tunable graphene high thermal conductivity pad according to claim 1, characterized in that: The copper powder is in flake form, the substrate is tin-plated steel plate, and the polyurethane diluent is selected from at least one of ethyl acetate, ethanol, acetone and pyrrolidone.

6. The method for preparing the variable-dimensional tunable graphene high thermal conductivity pad according to claim 1, characterized in that: In step S2, before adding the thermoplastic phenolic resin curing agent, a polyurethane diluent is added to the uniform mixture formed by the turbid liquid and the polyurethane resin. The mass ratio of the polyurethane diluent to the thermoplastic polyurethane elastomer resin is 1:1000-1:330, and the mixture is continued to be mixed evenly.

7. The method for preparing the variable-dimensional tunable graphene high thermal conductivity pad according to claim 1, characterized in that... The method for curing and forming the film is as follows: After applying the coating material to the substrate, let the substrate stand at room temperature for 4-7 hours, then heat it at 70-90℃ for 1-5 hours, and finally cool it.

8. The method for preparing the variable-dimensional tunable graphene high thermal conductivity pad according to claim 1, characterized in that: In step S5, the heating rate is 80-120℃ / min, the initial particle size of the expandable microspheres is 0.005-0.09mm, and the expansion rate of the expanded microspheres in the vertical direction is 800-1000%, while the expansion rate in the horizontal direction does not exceed 5%.

9. The method for preparing the variable-dimensional tunable graphene high thermal conductivity pad according to claim 1, characterized in that: The method for using the epoxy resin structural adhesive is as follows: After repeated stacking to the target height, place the stack at 50-80℃, evacuate for 1-3 hours, and finally cool.

10. The method for preparing the variable-dimensional tunable graphene high thermal conductivity pad according to claim 1, characterized in that... The laser-assisted hole-forming modification method is as follows: The graphene film was scanned with a laser with a power of 1000W-5000W and a pulse frequency of 1kHz-10kHz at a scanning speed of 10mm / s-100mm / s.

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