A method for preparing a silicon rubber gasket for electronic packaging heat dissipation of an integrated high-thermal-conductivity layered material based on peeling

Abstract

This invention relates to a method for preparing integrated high thermal conductivity layered material silicone rubber gaskets for heat dissipation in electronic packaging based on peeling. The method involves mixing polydopamine-modified boron nitride or graphite powder, silicone rubber, a silane coupling agent, and a bis(2,5)-pentachlor vulcanizing agent in a three-roll mill. By reducing the roller spacing and extending the mixing time, the boron nitride or graphite powder is peeled off within the composite material under the shear force of the rollers. The resulting mixture is placed in a metal mold and subjected to vacuum hot-pressing vulcanization, followed by a secondary vulcanization, to obtain a high thermal conductivity silicone rubber gasket for heat dissipation in electronic packaging. This method has broad application prospects in the fields of electronic packaging and thermal management.

Description

Technical Field

[0001] This invention relates to a method for preparing an integrated high thermal conductivity layered material for heat dissipation in electronic packaging based on peeling, belonging to the field of chip heat dissipation packaging technology. Background Technology

[0002] With the advancement of 5G technology, electronic products are developing towards miniaturization, high integration, and high power, while their heat dissipation requirements are also becoming increasingly stringent. If the heat of electronic devices cannot be dissipated in time, it can affect the product's lifespan and performance, and in severe cases, cause device failure and safety issues. Therefore, there is an urgent need to develop composite materials with high thermal conductivity to ensure effective heat dissipation and normal device operation. Traditional metal-based thermal conductive materials have high density and surface roughness, limiting their application scenarios. Polymer-based thermal conductive composite materials, due to their low density, good processability, and excellent flexibility and encapsulation properties, have become popular thermal conductive materials for chip heat dissipation.

[0003] Currently, a common method for preparing high thermal conductivity composite materials for electronic packaging is to add thermally conductive fillers to enhance thermal conductivity. This process is simple and suitable for mass production. Thermally conductive fillers include carbon fillers and inorganic fillers. Carbon fillers include graphite, graphene nanosheets, and carbon nanotubes, while inorganic fillers include Al2O3, SiN, and AlN, which have been successfully incorporated into various polymer matrices. Graphene and white graphene (BN nanosheets) are ideal thermally conductive fillers due to their extremely high thermal conductivity and high aspect ratio. However, the complex exfoliation process, low yield, and difficulty in dispersing graphene and boron nitride nanosheets result in high costs for the doped composite materials, making large-scale practical applications difficult. Even if dispersion is achieved, the relatively thick layers of graphene and boron nitride nanosheets prevent the production of high thermal conductivity boron nitride nanosheet / graphene polymer-based chip heat dissipation composite materials.

[0004] Therefore, it is of great significance to develop a low-cost and simple process for preparing high thermal conductivity boron nitride nanosheets / graphene polymer-based chip heat dissipation composite materials. Summary of the Invention

[0005] To address the challenges of complex exfoliation processes, low yields, and difficulties in dispersing graphene and boron nitride nanosheets, and even when dispersion is achieved, the thick layers of graphene and boron nitride nanosheets prevent the production of high thermal conductivity composite materials for heat dissipation in boron nitride nanosheet / graphene polymer-based chips, this invention provides a method for preparing integrated high thermal conductivity layered material silicone rubber pads for heat dissipation in electronic packaging based on exfoliation.

[0006] This invention is achieved through the following technical solution:

[0007] A method for preparing an integrated high thermal conductivity layered material silicone rubber pad for heat dissipation in electronic packaging based on peeling includes the following steps:

[0008] 1) Preparation of polydopamine-modified powder:

[0009] Tris is added to deionized water to adjust the pH of the solution and obtain Tris buffer. Dopamine hydrochloride is dispersed in Tris buffer. Boron nitride powder or graphite powder is immersed in the mixed solution and stirred. The solution is filtered, washed and dried to obtain polydopamine-modified boron nitride or graphite powder.

[0010] 2) Polydopamine-modified boron nitride or graphite powder, silicone rubber, silane coupling agent and bis(2,5-diphenyl) curing agent are placed in a three-roll mill for mixing. The roller spacing of the three-roll mill is 10-100 μm and the mixing time is 2-48 h. Reducing the roller spacing and extending the mixing time allows the boron nitride or graphite powder to peel off inside the composite material under the action of the roller shear force. The mixed mixture is placed in a metal mold, vacuum hot-pressed for vulcanization, and then vulcanized a second time to obtain a silicone rubber gasket for heat dissipation of high thermal conductivity electronic packaging.

[0011] According to a preferred embodiment of the present invention, in step 1), the mass-to-volume ratio of Tris to deionized water is (1.5-2.5):(1500-2500), in g / mL, and the pH of the solution is adjusted to 8-9.

[0012] According to a preferred embodiment of the present invention, in step 1), the amount of dopamine hydrochloride added is 1-2.5 mg / mL (Tris buffer).

[0013] According to a preferred embodiment of the present invention, in step 1), the particle size of the boron nitride powder is 5-50 μm, and the particle size of the graphite powder is 10-150 μm.

[0014] Most preferably, in step 1), the boron nitride powder has a particle size of 20 μm and the graphite powder has a particle size of 35 μm.

[0015] According to a preferred embodiment of the present invention, in step 1), the amount of boron nitride or graphite powder added is 40-60 g / L (Tris buffer).

[0016] According to a preferred embodiment of the present invention, in step 1), the stirring reaction temperature is 40-60°C and the reaction time is 6-10 h.

[0017] According to a preferred embodiment of the present invention, in step 2), the silicone rubber is a high-viscosity silicone rubber selected from methyl vinyl silicone rubber or methyl vinyl phenyl silicone rubber.

[0018] According to a preferred embodiment of the present invention, in step 2), the vinyl content in the methyl vinyl silicone rubber is 5-50 mol%, and the phenyl content in the methyl vinyl phenyl silicone rubber is 10-80 mol%.

[0019] More preferably, in step 2), the vinyl content in the methyl vinyl silicone rubber is 20 mol%, and the phenyl content in the methyl vinyl phenyl silicone rubber is 75 mol%.

[0020] According to a preferred embodiment of the present invention, in step 2), the coupling agent is KH550, KH560, KH570 or BTMOS.

[0021] Most preferably, in step 2), the coupling agent is BTMOS.

[0022] According to a preferred embodiment of the present invention, in step 2), the mass ratio of polydopamine modified powder, silicone rubber, silane coupling agent and bis(2,5-dimethyl)sulfurizing agent is (100-150):(100-150):(1-10):(1-3).

[0023] According to a preferred embodiment of the present invention, in step 2), the roller spacing is 30-60 μm and the mixing temperature is 25-40℃.

[0024] According to a preferred embodiment of the present invention, in step 2), the roller speed is 30-150 rpm / min and the mixing time is 20-48 h.

[0025] According to a preferred embodiment of the present invention, in step 2), the vacuum hot pressing vulcanization pressure is 8-12 MPa, the hot pressing temperature is 150-180°C, and the hot pressing time is 15-30 minutes; the secondary vulcanization temperature is 200-250°C, and the vulcanization time is 1-2 hours.

[0026] Technical features and advantages of the present invention:

[0027] 1. This invention uses high-viscosity silicone rubber as the medium and matrix. Compared with traditional mixing, this invention reduces the roller spacing and extends the mixing time. The roller speed of the three-roll mill is different, the roller spacing is 10-100μm, and the mixing time is 2-48h. This allows boron nitride or graphite powder to be exfoliated in situ inside the composite material under the action of roller shear force. This allows the thermal conductivity of graphene and BN nanosheets with extremely high thermal conductivity to be maximized in the composite material. It fully utilizes the advantages of high thermal conductivity of boron nitride nanosheets and graphene, and finally obtains a high thermal conductivity layered material silicone rubber gasket for heat dissipation in electronic packaging. This is also the core innovation of this invention.

[0028] 2. This invention uses dopamine hydrochloride to modify the powder, and then uses a coupling agent to perform secondary in-situ modification during mixing. The modified powder has good interfacial compatibility with silicone rubber and enhances the interfacial force, so that when silicone rubber is deformed, it can better drive the boron nitride or graphite powder to slide and produce a peeling effect. It also overcomes the problem that boron nitride or graphite powder cannot be uniformly dispersed due to the high viscosity and many pores of silicone rubber.

[0029] 3. This invention is the first to use silicone rubber as a medium to peel off two-dimensional materials and successfully prepares a silicone rubber pad for heat dissipation in electronic packaging with high thermal conductivity and high thermal stability.

[0030] 4. The silicone rubber gasket for heat dissipation in electronic packaging prepared by this invention has high tensile strength and hardness, while also having higher thermal conductivity and high thermal stability.

[0031] 5. The preparation method of the present invention is simple and can be mass-produced on a large scale. Detailed implementation method:

[0032] The specific embodiments of the present invention will be described below with reference to examples in order to better understand the present invention, but the scope of protection of the present invention is not limited thereto.

[0033] All materials used in the examples are commercially available products.

[0034] Example 1

[0035] A method for preparing an integrated high thermal conductivity layered material silicone rubber pad for heat dissipation in electronic packaging based on peeling includes the following steps:

[0036] 1) Preparation of polydopamine-modified boron nitride powder:

[0037] Add 4g Tris to 2000ml of deionized water and adjust the pH of the solution to 8. Disperse dopamine hydrochloride in Tris buffer and immerse boron nitride powder in the mixed solution. Stir and filter, wash and dry the solution to obtain polydopamine-modified boron nitride powder. Add 2mg of dopamine hydrochloride per milliliter of Tris buffer and 40g of powder per liter of Tris buffer. Stir at 40℃ for 6 hours. Filter, wash and dry the solution to obtain polydopamine-modified boron nitride powder.

[0038] 2) By mass: 100 parts of 75 mol% phenyl-content methyl vinyl phenyl silicone rubber, 100 parts of polydopamine-modified boron nitride, 3 parts of BTMOS and 1 part of bis(2,5)-5-vinyl chloride agent were put into a three-roll mixer. The roller gap was adjusted to 50 μm, the temperature to 25℃, the speed to 100 rpm / min, and the mixture was mixed for 2 hours. After the mixture was mixed evenly, it was taken out and placed in a metal mold. The metal mold was placed in a vacuum flat vulcanizing machine for vacuum hot pressing vulcanization (170℃, 10MPa, 20min). After the sample was taken out, it was vulcanized a second time (200℃, 1h) to obtain a high thermal conductivity silicone rubber gasket for heat dissipation in electronic packaging.

[0039] Example 2

[0040] The method described in the same way as in Example 1 differs in that:

[0041] In step 2), by weight: 100 parts of 75 mol% phenyl-content methyl vinyl phenyl silicone rubber, polydopamine-modified boron nitride powder, 3 parts of BTMOS, and 1 part of bis(2,5-dimethyl)-2-pentachloride vulcanizing agent are added to a three-roll mill and mixed for 24 hours.

[0042] Example 3

[0043] The method described in the same way as in Example 1 differs in that:

[0044] In step 2), the amount of polydopamine-modified boron nitride powder used is 150 parts.

[0045] Example 4

[0046] The method described in the same way as in Example 3 differs in that:

[0047] In step 2), the mixing time is 36 hours.

[0048] Example 5

[0049] The method described in the same way as in Example 3 differs in that:

[0050] In step 2), the mixing time is 48 hours.

[0051] Example 6

[0052] The method described in the same way as in Example 3 differs in that:

[0053] In step 2), the roller gap is 40 μm.

[0054] Example 7

[0055] The method described in the same way as in Example 3 differs in that:

[0056] In step 2), the roller gap is 30 μm.

[0057] Example 8

[0058] The method described in the same way as in Example 1 differs in that:

[0059] In step 2), the added powder is polydopamine-modified graphite powder, and the amount is 100 parts. The preparation of polydopamine-modified graphite powder is carried out according to Example 1.

[0060] Example 9

[0061] The method described in the same way as in Example 8 differs in that:

[0062] In step 2), the amount of polydopamine-modified graphite powder used is 120 parts.

[0063] Example 10

[0064] The method described in the same way as in Example 8 differs in that:

[0065] In step 2), the amount of polydopamine-modified graphite powder used is 150 parts.

[0066] Example 11

[0067] The method described in the same way as in Example 8 differs in that:

[0068] In step 2), the mixing time is 36 hours.

[0069] Example 12

[0070] The method described in the same way as in Example 8 differs in that:

[0071] In step 2), the mixing time is 48 hours.

[0072] Comparative Example 1

[0073] The method described in the same way as in Example 3 differs in that:

[0074] In step 2), the mixing time is 1 hour.

[0075] Comparative Example 2

[0076] The method described in the same way as in Example 3 differs in that:

[0077] In step 2), the mixing time is 96 hours.

[0078] Comparative Example 3

[0079] The method described in the same way as in Example 1 differs in that:

[0080] In step 2), the roller spacing is 4μm.

[0081] Comparative Example 4

[0082] The method described in the same way as in Example 1 differs in that:

[0083] In step 2), the roller spacing is 300 μm.

[0084] Comparative Example 5

[0085] The method described in the same way as in Example 1 differs in that:

[0086] In step 1), after obtaining the polydopamine-modified powder, the powder is modified a second time using a silane coupling agent.

[0087] In step 2), no silane coupling agent is added.

[0088] Experimental Example 1

[0089] The tensile strength, thermal conductivity, and thermal diffusivity of Examples 3 and 5, and Comparative Examples 1 and 2 were tested, and the results are shown in Table 1.

[0090] Table 1 Performance parameters of high thermal conductivity pad encapsulation materials

[0091] project Example 3 Example 5 Comparative Example 1 Comparative Example 2 Thermal conductivity (W / (m·K)) 9.6 22.7 2.8 3.8 Thermal diffusivity (mm² / s) 4.4 11.9 1.5 2.0 Tensile strength (MPa) 4.1 5.6 3.5 2.6

[0092] As shown in Table 1, Example 5, with a mixing time of 48 hours, exhibits the best thermal conductivity, thermal diffusivity, and tensile strength. The mixing time of Comparative Example 1 is significantly shorter than that of the present invention, while that of Comparative Example 2 is significantly longer, both resulting in a decrease in thermal conductivity. Furthermore, the longer mixing time of Comparative Example 2 also leads to a decrease in the tensile strength of the product. This demonstrates that the mixing time of the present invention, ranging from 2 to 48 hours, allows boron nitride or graphite powder to undergo in-situ exfoliation within the composite material under the shearing force of the rollers. This maximizes the thermal conductivity of the extremely high-thermal-conductivity graphene and BN nanosheets within the composite material, fully leveraging the advantages of the high thermal conductivity of boron nitride nanosheets and graphene. Ultimately, this yields a high-thermal-conductivity layered material silicone rubber gasket for heat dissipation in electronic packaging.

[0093] Experiment Example 2

[0094] The tensile strength, thermal conductivity, and thermal diffusivity of Example 1, Comparative Examples 3, 4, and 5 were tested, and the results are shown in Table 2.

[0095] Table 2 Performance parameters of high thermal conductivity pad encapsulation materials

[0096] project Example 1 Comparative Example 3 Comparative Example 4 Comparative Example 5 Thermal conductivity (W / (m·K)) 7.4 2.2 1.7 2.4 Thermal diffusivity (mm² / s) 2.2 1.2 0.9 1.3 Tensile strength (MPa) 4.1 3.9 3.6 3.9

[0097] As can be seen from Table 2, the roller spacing of Comparative Example 3 is significantly smaller than that of the present invention, and the roller spacing of Comparative Example 4 is significantly larger than that of the present invention, both of which lead to a decrease in thermal conductivity. The coupling agent in Comparative Example 5 is not modified in situ twice during mixing, but is directly modified once and then modified twice, which also leads to a decrease in thermal conductivity.

[0098] In summary, with a roller spacing of 10-100μm and a mixing time of 2-48h, secondary in-situ modification is performed during mixing, resulting in better in-situ exfoliation of boron nitride or graphite powder, and the resulting silicone rubber gaskets for heat dissipation in electronic packaging have higher thermal conductivity.

Claims

1. A method for preparing an integrated high thermal conductivity layered material silicone rubber pad for heat dissipation in electronic packaging based on peeling, comprising the following steps: 1) Preparation of polydopamine-modified powder: Tris is added to deionized water to adjust the pH of the solution and obtain Tris buffer. Dopamine hydrochloride is dispersed in Tris buffer. Boron nitride powder or graphite powder is immersed in the mixed solution and stirred. The solution is filtered, washed and dried to obtain polydopamine-modified boron nitride or graphite powder. 2) Polydopamine-modified boron nitride or graphite powder, silicone rubber, silane coupling agent and bis(2,5-diphenyl) curing agent are placed in a three-roll mill for mixing. The roller spacing of the three-roll mill is 10-100 μm and the mixing time is 2-48 h. Reducing the roller spacing and extending the mixing time allows the boron nitride or graphite powder to peel off inside the composite material under the action of the roller shear force. The mixed mixture is placed in a metal mold, vacuum hot-pressed for vulcanization, and then vulcanized a second time to obtain a silicone rubber gasket for heat dissipation of high thermal conductivity electronic packaging.

2. The method according to claim 1, characterized in that, In step 1), the mass-to-volume ratio of Tris to deionized water is (1.5-2.5):(1500-2500), unit, g / mL, and the pH of the solution is adjusted to 8-9.

3. The method according to claim 1, characterized in that, In step 1), the amount of dopamine hydrochloride added is 1-2.5 mg / mL (Tris buffer).

4. The method according to claim 1, characterized in that, In step 1), the particle size of boron nitride powder is 5-50 μm, and the particle size of graphite powder is 10-150 μm.

5. The method according to claim 1, characterized in that, In step 1), the amount of boron nitride or graphite powder added is 40-60 g / L (Tris buffer), the stirring reaction temperature is 40-60℃, and the reaction time is 6-10 h.

6. The method according to claim 1, characterized in that, In step 2), the silicone rubber is a high-viscosity silicone rubber, selected from methyl vinyl silicone rubber or methyl vinyl phenyl silicone rubber.

7. The method according to claim 6, characterized in that, In step 2), the vinyl content in methyl vinyl silicone rubber is 5-50 mol%, and the phenyl content in methyl vinyl phenyl silicone rubber is 10-80 mol%.

8. The method according to claim 1, characterized in that, In step 2), the coupling agent is KH550, KH560, KH570 or BTMOS, and the mass ratio of polydopamine modified powder, silicone rubber, silane coupling agent and bis(2,5-dimethyl)sulfurizing agent is (100-150):(100-150):(1-10):(1-3).

9. The method according to claim 1, characterized in that, In step 2), the roller spacing is 30-60μm, the mixing temperature is 25-40℃, the roller speed is 30-150rpm / min, and the mixing time is 20-48h.

10. The method according to claim 1, characterized in that, In step 2), the vacuum hot pressing vulcanization pressure is 8-12 MPa, the hot pressing temperature is 150-180℃, and the hot pressing time is 15-30 minutes. The secondary vulcanization temperature is 200-250℃, and the vulcanization time is 1-2 hours.