CN102153955B - Preparation method of heat conduction plaster adopting fiber glass mesh as supporting structure - Google Patents

Abstract

The invention discloses a method for preparing a heat-conducting patch using glass fiber mesh as a supporting structure. The preparation method comprises: dissolving silicone rubber to prepare a silicone rubber solution, adding vulcanizing agent, heat-conducting filler, and silane coupling agent in sequence, Ultrasonic dispersion, uniform mixing by ball milling, and preparation of a slurry with moderate viscosity and good coating performance; the silicone rubber slurry is evenly coated on the pretreated glass fiber mesh, and the solvent is evaporated, dried, molded and vulcanized, trimmed, A thermally conductive patch is obtained; this thermally conductive patch has high thermal conductivity, softness, small thermal expansion coefficient, high thermal stability, a certain viscosity on the surface, and the viscosity can be adjusted within a certain range, easy to use and disassemble, and meets the insulation performance requirements.

Description

A preparation method of a thermally conductive patch using a glass fiber mesh as a supporting structure

technical field

The invention relates to a preparation method of a heat conduction patch using a glass fiber mesh as a supporting structure.

Background technique

With the development of microelectronics technology, electronic components are developing toward miniaturization, integration, and multi-function. The microelectronics industry is facing the problem of heat dissipation bottlenecks. The temperature rises, the function of electronic components decreases, the reliability decreases, and the service life is obvious. decrease. Especially in LED packaging, the difficulty of heat dissipation greatly hinders the improvement of LED lighting power. There are three main ways of traditional heat dissipation: air cooling, circulating water cooling and adding heat sinks. Due to the limitation of small size, it is generally used in the packaging of electronic materials to dissipate heat by adding heat sinks. The heat sinks are generally made of metal copper with excellent thermal conductivity. And metal aluminum, the heat generated by the heating component is conducted to the copper-based or aluminum-based heat sink, and the heat is dissipated in time by increasing the heat dissipation area.

This heat dissipation method is widely used in the microelectronics industry. Heat dissipation is based on heat conduction. Studies have shown that the excellent thermal conductivity of heat dissipation components cannot ensure that heat can be dissipated in time. Some have high thermal resistance. There are many convex and concave parts on the interface that looks smooth on the surface, and there are gaps in the connection between the two parts that seem to fit tightly under the microscope, which leads to the gap being occupied by air when they are connected together, and the thermal resistance of air is very large , and the air circulation occupying the gap is extremely poor, and it is easy to generate local high temperature, which is not conducive to heat dissipation. In order to solve the problem of poor heat transfer at the interface, it is necessary to use thermal interface materials (thermal interface materials) at the interface between the heating component and the heat dissipation component. There are two traditional thermal interface materials: (1) thermal conductive silicone grease, which is added to various organic greases Made of thermally conductive filler, thermally conductive silicone grease has poor fluidity when the temperature is low. As the temperature rises, thermally conductive silicone grease starts to flow and can fill the gap between interfaces. As a gap filling material, thermally conductive silicone grease has a much higher thermal conductivity. In the air, can significantly enhance heat dissipation. Thermally conductive silicone grease is widely used in the electronics industry, but thermally conductive silicone grease has obvious disadvantages. The high viscosity makes it difficult for thermally conductive silicone grease to be evenly coated between interfaces. Studies have shown that too little thermally conductive silicone grease has limited effect. Coating too thick can cause packaging difficulties. As the temperature rises, the fluidity of thermal conductive silicone grease increases, which may contaminate electronic components, even cause a short circuit, and the residual grease is not easy to remove. (2) Thermally conductive potting compound, which is made by adding thermally conductive filler to epoxy resin, which can better package the heating parts and heat dissipation parts as a whole, and the thermally conductive filler plays the role of heat conduction channel, but the thermal conductivity of this potting compound is poor, And after curing, affected by the change of ambient temperature, it is easy to cause the two to detach and lose the heat conduction condition.

Sheets are easier to handle than grease, and thermally conductive sheets made of thermally conductive silicone rubber or the like are widely used in a wide variety of applications. Thermally conductive sheets are generally divided into two categories, general-purpose sheets selected for easy handling purposes and low-hardness sheets selected for bonding.

Contents of the invention

The thermally conductive filler used in the present invention is innovated on the basis of traditional thermally conductive fillers, using commonly used aluminum oxide micro-particles, nano-aluminum nitride with high thermal conductivity, especially carbon-coated copper nanocomposite particles, used alone or in combination. In order to improve the dispersibility of thermally conductive fillers in silicone rubber, dissolve silicone rubber to prepare a silicone rubber solution, add vulcanizing agent, thermally conductive fillers, and coupling agents, and use ultrasonic dispersion to uniformly disperse nano fillers in silicone rubber, and then ball mill method to further disperse evenly. Compared with the traditional mechanical blending method, this mixing method has obvious advantages. The mechanical blending method will destroy the filler structure and make it difficult to disperse the filler. All the solvents used in the invention can be recycled and reused, and the operation is simple, energy-saving and environment-friendly. Ultrasonic dispersion has a good dispersion effect on nano fillers, generally 800W ~ 1200W, 20min ~ 40min can achieve a uniform dispersion effect, which is obviously better than the mechanical blending method, the ball milling method further disperses the filler, and the filler dispersion is uniform and stable. The use of high thermal conductivity fillers ensures the excellent thermal conductivity of the patch. The solution method evenly disperses the fillers, the thermal conductivity of the patch is uniform, the coating performance is good, the surface is smooth, and the performance is stable.

A preparation method of a thermally conductive patch using glass fiber mesh as a supporting structure provided by the present invention has the following steps: dissolving silicone rubber in a solvent to prepare a silicone rubber solution; adding vulcanizing agent, thermally conductive filler, and coupling agent in sequence; Disperse and ball mill until the filler is evenly dispersed to obtain a silicone rubber slurry, which is evenly coated on the pretreated glass fiber net, and the glass fiber net coated with the slurry is fully dried, molded and vulcanized, and trimmed. A thermally conductive patch using a fiberglass mesh as a support structure is obtained.

The above-mentioned silicone rubber is methylvinyl silicone rubber with a Shore A hardness of less than 50 degrees, and is prepared by dissolving in a solvent to form a silicone rubber solution in which the silicone rubber accounts for 25% to 40% by mass of the solution, and the solvent is tetrahydrofuran or gasoline. In order to speed up the dissolution rate, it can be properly heated and mixed with stirring, but the heating temperature should be lower than 60 degrees Celsius, because tetrahydrofuran and gasoline are flammable and explosive substances.

The above-mentioned vulcanizing agent is a bis-2,5 vulcanizing agent, and the dosage is 1.5%-4.0% of the weight of the silicone rubber. Adjust appropriately according to vulcanization performance and patch softness.

The above-mentioned thermally conductive fillers are micron-sized aluminum oxide particles, aluminum nitride nanoparticles or carbon-coated copper nanoparticles; micron-sized aluminum oxide particles, aluminum nitride nanoparticles or carbon-coated copper nanoparticles The total mass should be less than or equal to 30% of the weight of silicone rubber.

The above-mentioned coupling agent is silane coupling agent KH-550, Dow Corning Z-6020 or Dow Corning Z-6040, and the dosage is 0.5%-2% of the total weight of the thermally conductive filler.

The above ultrasonic dispersion time is 20min-40min, the power is 800w-1200w; the ball milling speed is 100r/min, and the ball milling time is 2h-24h. The filler can be dispersed evenly.

The above-mentioned glass fiber mesh coated with the slurry was put into a drying device for drying, and the solvent was completely removed. The drying temperature was 60° C. and the drying time was 8 hours.

The above-mentioned pretreatment method for the glass fiber mesh is to soak the glass fiber mesh in concentrated sulfuric acid or concentrated nitric acid or a mixture of the two acids for 4 hours to 24 hours. Choose reasonably according to the coating performance.

The above vulcanization pressure is 10MPa-20MPa, the vulcanization temperature is 160°C-190°C, and the time is 8min-12min.

Beneficial effects of the present invention:

The heat conduction patch prepared by the invention is thin in thickness and has a layer of glass fiber mesh in the middle to enhance heat transfer, and at the same time as a support structure, a large area heat conduction patch can be prepared. Through the solution method, combined with ultrasonic dispersion and ball milling, the filler is uniformly dispersed in the silicone rubber slurry, the concentration of the slurry is controlled, and the slurry is evenly coated on the etched glass fiber mesh. More protrusions and grooves will be formed on the glass fiber mesh etched by strong acid. This structure enables the silicone rubber slurry to be better coated on the glass fiber mesh, and the coating performance is greatly improved. Carbon-coated copper nanocomposite particles, one of the heat-conducting fillers of the present invention, are nano-particles with a novel structure. The outer layer of carbon completely wraps the inner layer of metal copper, which not only has the high thermal conductivity of copper nanoparticles, but also the outer layer of carbon can Limit the thermal expansion of copper nanoparticles and reduce the thermal expansion of the patch. Studies have shown that the theoretical thermal conductivity of carbon nanotubes is 3000W/m.K, the thermal conductivity of aluminum nitride is 320W/m.K, and the thermal conductivity of aluminum oxide is 30W/m.K. As a thermally conductive filler, it plays a role in thermal conductivity inside the silicone rubber. The role of the channel. The silicone rubber in the present invention has excellent chemical stability, high thermal decomposition temperature, simple vulcanization operation, and the prepared heat conduction patch has a smooth surface and a certain viscosity, and can be closely attached between the heating part and the heat dissipation part, and the thickness is thin. Soft, with glass fiber mesh inside as a supporting structure, easy to disassemble without residue pollution, low thermal expansion coefficient, at the same level as metal aluminum, and can cooperate well during heat conduction to prevent deformation and new gaps caused by thermal expansion. DSC-TGA test shows that the thermal pad can be used for a long time at 180°C.

Detailed ways

The following examples are only used to describe the advantages of the present invention in detail, and the manufacture and application of the thermally conductive patch material of the present invention are not limited thereto.

Example 1

(1) Dissolve 30g of silicone rubber in 90g of tetrahydrofuran to prepare a 25% silicone rubber solution, add 1.0g of double 2,5 silicone rubber vulcanizing agent, and stir evenly.

(2) Add 4 g of micron-sized aluminum oxide, 2 g of nano-AlN thermally conductive fillers, and 0.015 g of silane coupling agent KH-550 into step (1).

(3) In step (2), the mixed solution was ultrasonically dispersed for 20 minutes with a power of 800W.

(4) The mixed liquid in step (3) is put into a ball mill tank and ball milled for 24 hours to obtain a silicone rubber slurry in which the thermally conductive filler is uniformly dispersed.

(5) Soak the glass fiber mesh with concentrated sulfuric acid for 4 hours to obtain a pretreated glass fiber mesh.

(6) The slurry obtained in step (4) is uniformly coated on the pretreated glass fiber web in step (5).

(7) The silicon rubber-coated glass fibers obtained in step (6) were dried in a vacuum drying oven at a drying temperature of 60° C. and a drying time of 8 hours.

(8) The unvulcanized patch in step (7) is vulcanized on a flat vulcanizing machine, the vulcanization pressure is 20MPa, the vulcanization temperature is 190°C, and the time is 8min. The product is trimmed to obtain a thermal conductive patch.

Example 2

(1) Dissolve 30g of silicone rubber in 70g of tetrahydrofuran to prepare a 30% silicone rubber solution, add 0.6g of double 2,5 silicone rubber vulcanizing agent, and stir evenly.

(2) Add 6 g of carbon-coated copper nanoparticle heat-conducting filler to step (1), and add 0.06 g of silane coupling agent Dow Corning Z-6020.

(3) In step (2), the mixed solution was ultrasonically dispersed for 30 minutes with a power of 1200W.

(4) The mixed solution in step (3) is put into a ball mill tank and ball milled for 2 hours to obtain a silicone rubber slurry in which the thermally conductive filler is uniformly dispersed.

(5) Soak the glass fiber mesh with concentrated sulfuric acid for 24 hours to obtain a pretreated glass fiber mesh.

(6) The slurry obtained in step (4) is uniformly coated on the pretreated glass fiber web in step (5).

(7) The silicon rubber-coated glass fibers obtained in step (6) were dried in a vacuum drying oven at a temperature of 60° C. and a drying time of 8 hours.

(8) The unvulcanized patch in step (7) is vulcanized on a flat vulcanizing machine, the vulcanization pressure is 14MPa, the vulcanization temperature is 160°C, and the time is 10min. The product is trimmed to obtain a thermal conductive patch.

Example 3

(1) Dissolve 30g of silicone rubber in 45g of tetrahydrofuran to prepare a 40% silicone rubber solution, add 0.45g of double 2,5 silicone rubber vulcanizing agent, and stir evenly.

(2) Add 9g of nanometer AlN particle thermal conductive filler to step (1), and add 0.045g of silane coupling agent Dow Corning Z-6040.

(3) In step (2), the mixed liquid was ultrasonically dispersed for 40 minutes, and the power was 1200W.

(4) The mixed liquid in step (3) is put into a ball mill tank and ball milled for 24 hours to obtain a silicone rubber slurry in which the thermally conductive filler is uniformly dispersed.

(5) Soak the glass fiber mesh with a mixed strong acid of concentrated sulfuric acid and concentrated nitric acid for 20 hours to obtain a pretreated glass fiber mesh.

(6) The slurry obtained in step (4) is uniformly coated on the pretreated glass fiber web in step (5).

(7) The glass fiber coated with silicone rubber obtained in step (6) was dried in a vacuum drying oven at a temperature of 60 degrees Celsius for 8 hours.

(8) The unvulcanized patch in step (7) is vulcanized on a flat vulcanizing machine, the vulcanization pressure is 10MPa, the vulcanization temperature is 180°C, and the time is 9min. The product is trimmed to obtain a thermal conductive patch.

Example 4

(1) Dissolve 30g of silicone rubber in 70g of gasoline to prepare a 30% silicone rubber solution, add 0.6g of double 2,5 silicone rubber vulcanizing agent, and stir evenly.

(2) Add 1.5g of nano-aluminum nitride, 4.5g of micron-sized aluminum oxide guide particles, 1.5g of carbon-coated copper nanoparticle thermal filler, and 0.15g of silane coupling agent KH-550 into step (1).

(3) In step (2), the mixed solution was ultrasonically dispersed for 30 minutes with a power of 1000W.

(4) The mixed solution in step (3) is put into a ball mill tank and ball milled for 20 hours to obtain a silicone rubber slurry in which the thermally conductive filler is uniformly dispersed.

(5) Soak the glass fiber mesh with concentrated sulfuric acid for 14 hours to obtain a pretreated glass fiber mesh.

(6) The slurry obtained in step (4) is uniformly coated on the pretreated glass fiber web in step (5).

(7) The silicon rubber-coated glass fibers obtained in step (6) were dried in a vacuum drying oven at a drying temperature of 60° C. and a drying time of 8 hours.

(8) The unvulcanized patch in step (7) is vulcanized on a flat vulcanizing machine, the vulcanization pressure is 12MPa, the vulcanization temperature is 170°C, and the time is 8min. The product is trimmed to obtain a thermal conductive patch.

Example 5

(1) Dissolve 30g of silicone rubber in 70g of gasoline to prepare a 30% silicone rubber solution, add 1.2g of double 2,5 silicone rubber vulcanizing agent, and stir evenly.

(2) Add 4.5 g of carbon-coated copper nanoparticles and 4.5 g of micron-sized aluminum oxide particle thermally conductive fillers to step (1), and add 0.1 g of coupling agent Dan Corning Z-6040.

(3) In step (2), the mixed solution was ultrasonically dispersed for 40 minutes with a power of 800W.

(4) The mixed liquid in step (3) is put into a ball mill tank and ball milled for 4 hours to obtain a silicone rubber slurry in which the thermally conductive filler is uniformly dispersed.

(5) Soak the glass fiber mesh with concentrated nitric acid for 10 hours to obtain a pretreated glass fiber mesh.

(6) The slurry obtained in step (4) is uniformly coated on the pretreated glass fiber web in step (5).

(7) The silicon rubber-coated glass fibers obtained in step (6) were dried in a vacuum drying oven at a drying temperature of 60° C. and a drying time of 8 hours.

(8) The unvulcanized patch in step (7) is vulcanized on a flat vulcanizing machine, the vulcanization pressure is 20MPa, the vulcanization temperature is 160°C, and the time is 12min. The product is trimmed to obtain a thermal conductive patch.

Claims (9)

1. A preparation method using glass fiber mesh as a thermally conductive patch of support structure, characterized in that the method has the steps of: dissolving silicone rubber into a silicone rubber solution; adding vulcanizing agent, thermally conductive filler, coupling The silicone rubber slurry is obtained by ultrasonic dispersion and ball milling until the filler is evenly dispersed, and the silicone rubber slurry is evenly coated on the pretreated glass fiber mesh, and the glass fiber mesh coated with the slurry is fully dried, and then molded and vulcanized. , trimming to obtain a thermally conductive patch using glass fiber mesh as a supporting structure. 2. The preparation method according to claim 1, characterized in that: the above-mentioned silicone rubber is a methyl vinyl silicone rubber with Shore A hardness less than 50 degrees, and the silicone rubber is dissolved in a solvent to form a mass fraction of 25% to 25% of the solution. 40% silicone rubber solution, the solvent is tetrahydrofuran or gasoline. 3. The preparation method according to claim 1, characterized in that: the above-mentioned vulcanizing agent is a bis-2,5 vulcanizing agent, and the dosage is 1.5%-4.0% of the weight of the silicone rubber. 4. The preparation method according to claim 1, characterized in that: the above-mentioned thermally conductive filler is micron-sized aluminum oxide particles, aluminum nitride nanoparticles or carbon-coated copper nanoparticles; Aluminum nanoparticles or carbon-coated copper nanoparticles are used alone or in combination, and the total mass of the thermally conductive filler should be less than or equal to 30% of the weight of the silicone rubber. 5. The preparation method according to claim 1, characterized in that: the above-mentioned coupling agent is silane coupling agent KH-550, Dow Corning Z-6020 or Dow Corning Z-6040, and the consumption is 0.5% to 0.5% of the total weight of the thermally conductive filler. 2%. 6. The preparation method according to claim 1, characterized in that: the ultrasonic dispersion time is 20min-40min, the power is 800w-1200w; the ball milling speed is 100r/min, and the ball milling time is 2h-24h. 7. The preparation method according to claim 1, characterized in that: the above-mentioned glass fiber mesh coated with the slurry is put into a drying device for drying, and the solvent is completely removed, the drying temperature is 60° C., and the drying time is 8 hours. 8 . The preparation method according to claim 1 , characterized in that: the glass fiber web pretreatment method is to soak the glass fiber web in concentrated sulfuric acid or concentrated nitric acid or a mixture of the two acids for 4 hours to 24 hours. 9. The preparation method according to claim 1, characterized in that: the vulcanization pressure is 10MPa-20MPa, the vulcanization temperature is 160°C-190°C, and the time is 8min-12min.