A high-elasticity thermally conductive silicone material, a high-elasticity thermally conductive silicone pad, and a method for preparing them.

Abstract

This application provides a high-elasticity thermally conductive silicone material, a high-elasticity thermally conductive silicone pad, and a preparation method thereof, relating to the field of thermally conductive materials. The high-elasticity thermally conductive silicone material comprises, by weight, 10-20 parts liquid silicone rubber; 20-40 parts silicone oil; 3-6 parts crosslinking agent; 800-1200 parts thermally conductive filler; 0.05-0.15 parts inhibitor; and 2-4 parts catalyst. The thermally conductive filler comprises: large-particle-size filler with a particle size range of 80-120 μm, accounting for 35%-45% by weight; medium-particle-size filler with a particle size range of 5-79.9 μm, accounting for 45%-60% by weight; and small-particle-size filler with a particle size range of 1-4.99 μm, accounting for 3%-10% by weight. The high-elasticity thermally conductive silicone pad of this application features high resilience and high thermal conductivity, ensuring heat dissipation and guaranteeing the normal service life of electronic devices.

Description

Technical Field

[0001] This application relates to the field of thermally conductive materials, and more specifically, to a high-elasticity thermally conductive silicone material, a high-elasticity thermally conductive silicone pad, and a method for preparing the material. Background Technology

[0002] With the development of integrated circuit technology and the increasing density of microelectronic assembly, the heat generated by electronic devices accumulates and increases rapidly. However, this rapid increase in heat generation leads to a decline in the performance and reliability of electronic devices. To address this issue, a thermally conductive interface material is typically applied to the heat exchange surface of electronic devices that generate significant heat. Thermally conductive silicone pads, as a good thermally conductive interface material, possess certain flexibility, excellent insulation, compressibility, and natural surface adhesion, allowing for relatively rapid and effective transfer of heat generated by electronic components to heat dissipation devices. However, different thermally conductive silicone pads exhibit varying performance characteristics.

[0003] Traditional thermal conductive silicone pads on the market currently have poor resilience, and long-term use will cause them to harden, resulting in stress relaxation. This can create gaps between the originally well-fitting electronic components, thermal conductive silicone pads, and heat dissipation devices, increasing thermal resistance, affecting heat dissipation, and reducing the normal lifespan of electronic components. Summary of the Invention

[0004] The purpose of this application is to provide a high-elasticity thermally conductive silicone material, a high-elasticity thermally conductive silicone pad, and a preparation method thereof. The silicone pad has the characteristics of high resilience and high thermal conductivity, ensuring heat dissipation effect and ensuring the normal service life of electronic devices.

[0005] In a first aspect, embodiments of this application provide a highly elastic thermally conductive silicone material, which comprises, by weight parts:

[0006]

[0007] The thermally conductive filler includes:

[0008] Large-particle-size fillers with a particle size range of 80–120 μm account for 35%–45% of the total mass.

[0009] Medium-sized fillers with a particle size range of 5–79.9 μm account for 45%–60% of the total mass.

[0010] Small-particle-size fillers with a particle size range of 1–4.99 μm account for 3%–10% of the total mass.

[0011] In the above technical solution, this application uses a specific combination of liquid silicone rubber and silicone oil to crosslink with a crosslinking agent to form a silicone matrix for a high-elasticity thermally conductive silicone pad. This achieves a high resilience effect, ensuring good contact stress between electronic components and the high-elasticity thermally conductive silicone pad, and between the high-elasticity thermally conductive silicone pad and the heat sink. This reduces stress relaxation and thus minimizes interfacial voids caused by increased hardness and stress relaxation over long-term use, thereby improving thermal conductivity.

[0012] This application employs a specific combination of thermally conductive filler and silicone matrix to achieve a low hardness and low internal stress effect in the formed high-elasticity thermally conductive silicone pad. This results in lower internal stress between electronic components and the high-elasticity thermally conductive silicone pad, and between the high-elasticity thermally conductive silicone pad and the heat sink, providing greater buffering and minimizing damage to electronic components.

[0013] This application employs a specific combination of thermally conductive fillers with a particle size gradient to ensure more complete filling and achieve high thermal conductivity. This enables the high thermal conductivity of the high-elasticity thermally conductive silicone pad under high resilience conditions, meeting the high thermal conductivity requirements for applications with high heat generation. This application comprehensively considers the high resilience and high thermal conductivity requirements of the high-elasticity thermally conductive silicone pad by controlling the particle size gradient distribution of the thermally conductive filler. Small-sized fillers in the thermally conductive filler have a significant impact on the viscosity of the system; excessive filler increases viscosity. A larger specific surface area of ​​the thermally conductive filler results in greater oil absorption; however, an excessively large specific surface area leads to a loose, sand-like state, preventing aggregation.

[0014] In one possible implementation, the mass ratio of liquid silicone rubber to silicone oil is 1:2 to 1:3;

[0015] Optionally, the molecular weight of the liquid silicone rubber is 400,000 to 1,000,000 g / mol;

[0016] Optionally, the silicone oil includes at least one of methyl silicone oil and vinyl silicone oil, wherein the viscosity of the methyl silicone oil is 50 to 500 mPa·s, the viscosity of the vinyl silicone oil is 100 to 5000 mPa·s, and the vinyl content is 0.5% to 5%.

[0017] In the aforementioned technical solutions, silicone rubber has relatively long molecular chains and high viscosity. After curing (crosslinking), the silicone matrix exhibits strong flexibility and elasticity, but its high viscosity limits the amount of thermally conductive filler that can be incorporated. Silicone oil, on the other hand, generally has shorter molecular chains and lower viscosity, allowing for the inclusion of more thermally conductive filler. However, after curing (crosslinking), the silicone matrix exhibits high rigidity and low elasticity. This application utilizes specific liquid silicone rubber and silicone oil, blended in a specific ratio, to achieve a relatively high thermal conductivity while ensuring strong resilience.

[0018] In one possible implementation, the mass of the crosslinking agent is 5% to 15% of the total mass of the liquid silicone rubber and silicone oil.

[0019] In the above technical solution, excessive crosslinking agent will result in excessive crosslinking, leading to excessive hardness of the produced thermally conductive silicone pad, which will lose its original elasticity and affect the thermal conductivity of the product during actual use; insufficient crosslinking agent will result in insufficient crosslinking, which will prevent the material from being formed and used.

[0020] In one possible implementation, the crosslinking agent comprises a hydrogen-containing silicone oil with a viscosity of 100–500 mPa·s and an active hydrogen content of 0.04%–0.4%.

[0021] In the above technical solution, using a specific hydrogen-containing silicone oil as a crosslinking agent allows for a certain degree of control over the crosslinking network. Thermally conductive silicone pads made with hydrogen-containing silicone oils with lower hydrogen content exhibit greater flexibility but lower tensile strength; thermally conductive silicone pads made with hydrogen-containing silicone oils with higher hydrogen content show greater rigidity and are easier to manufacture into products with high hardness. This application uses hydrogen-containing silicone oils with lower hydrogen content in combination with silicone rubbers and silicone oils of varying viscosity to produce highly elastic thermally conductive silicone pads with good resilience and high thermal conductivity, meeting the needs of scenarios requiring high resilience and high thermal conductivity.

[0022] In one possible implementation, the medium-sized filler is divided into a first medium-sized filler with a particle size range of 20–79.9 μm and a second medium-sized filler with a particle size range of 5–19.99 μm. The mass percentage of the first medium-sized filler in the thermally conductive filler is 5%–15%, and the mass percentage of the second medium-sized filler is 40%–45%.

[0023] In one possible implementation, the thermally conductive filler also includes nano-sized alumina with a particle size of 100–500 nm, wherein the mass percentage of the nano-sized alumina in the thermally conductive filler is 1%–5%.

[0024] In the above technical solution, nano-sized alumina increases the contact area between itself and the heat-conducting object, thereby reducing the interfacial thermal resistance.

[0025] In one possible implementation, it also includes 2 to 4 parts by weight of color paste;

[0026] And / or, the catalyst is one of platinum catalyst, rhodium catalyst and palladium catalyst;

[0027] And / or, the inhibitor is an alkynylcyclohexanol or an alkynyl alcohol compound.

[0028] Secondly, embodiments of this application provide a high-elasticity thermally conductive silicone pad, which is obtained by mixing and cross-linking the high-elasticity thermally conductive silicone material provided in the first aspect.

[0029] In the above technical solution, the high-elasticity thermally conductive silicone pad prepared in this application, while ensuring high thermal conductivity, has high resilience, maintaining good contact stress between electronic components and the high-elasticity thermally conductive silicone pad, and between the high-elasticity thermally conductive silicone pad and the heat sink, reducing stress relaxation phenomena, thereby reducing interface gaps caused by stress relaxation due to long-term hardening and improving thermal conductivity. The high-elasticity thermally conductive silicone pad is relatively soft and has low stress during the bonding process with electronic components, ensuring good adhesion between electronic components and the high-elasticity thermally conductive silicone pad, and between the high-elasticity thermally conductive silicone pad and the heat sink, reducing gaps, minimizing thermal resistance, and improving thermal conductivity.

[0030] Thirdly, embodiments of this application provide a method for preparing a highly elastic thermally conductive silicone pad, which includes the following steps using the highly elastic thermally conductive silicone material provided in the first aspect:

[0031] Liquid silicone rubber, silicone oil and crosslinking agent are premixed to prepare the matrix adhesive;

[0032] The matrix adhesive and thermally conductive filler are kneaded once until they are evenly mixed, and then the inhibitor and catalyst are added in sequence for a second kneading.

[0033] The raw materials, which are kneaded evenly twice, are vacuum-treated, rolled, and baked in a vacuum environment.

[0034] The above technical solution achieves efficient heat transfer while reducing product production costs.

[0035] In one possible implementation, the premixing time is 20–40 min; the first kneading time is 30–60 min; and the second kneading time is 40–80 min.

[0036] And / or, the vacuum level during evacuation is -0.07 to -0.1 MPa, and the time is 30 to 60 minutes;

[0037] And / or, the baking temperature is 120-150℃, and the baking time is 15-30 minutes. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0039] The following provides a detailed description of the high-elasticity thermally conductive silicone material, the high-elasticity thermally conductive silicone pad, and the preparation method according to embodiments of this application.

[0040] This application provides a high-elasticity thermally conductive silicone material, which comprises, by weight parts: 10-20 parts liquid silicone rubber; 20-40 parts silicone oil; 3-6 parts crosslinking agent; 800-1200 parts thermally conductive filler; 0.05-0.15 parts inhibitor; 2-4 parts catalyst; and 2-4 parts color paste.

[0041] In this embodiment, the mass ratio of liquid silicone rubber to silicone oil is 1:2 to 1:3. Silicone rubber refers to rubber whose main chain is composed of alternating silicon and oxygen atoms, with two organic groups typically attached to the silicon atoms. The molecular weight of the liquid silicone rubber is 400,000 to 1,000,000 g / mol, optionally 600,000 to 800,000 g / mol, and further optionally 700,000 g / mol. The silicone oil includes at least one of methyl silicone oil and vinyl silicone oil. The viscosity of methyl silicone oil is 50 to 500 mPa·s, optionally 50 to 150 mPa·s, and further optionally 100 mPa·s; the viscosity of vinyl silicone oil is 100 to 5000 mPa·s, optionally 850 to 1000 mPa·s, and the vinyl content is 0.5% to 5%, optionally 0.5% to 1%.

[0042] In this embodiment, the crosslinking agent is 5% to 15% of the total mass of the liquid silicone rubber and silicone oil. The crosslinking agent includes hydrogen-containing silicone oil with a viscosity of 100 to 500 mPa·s and an active hydrogen content of 0.04% to 0.4%, optionally 0.07% to 0.1%.

[0043] In the embodiments of this application, the thermally conductive filler is one or more of boron nitride, magnesium oxide, aluminum oxide, aluminum hydroxide, zinc oxide, silicon dioxide, boron nitride, aluminum nitride, and silicon carbide.

[0044] Based on particle size distribution, thermally conductive fillers include:

[0045] Large-particle-size fillers with a particle size range of 80–120 μm account for 35%–45% of the total mass.

[0046] The first medium-sized filler with a particle size range of 20–79.9 μm accounts for 5%–15% of the total mass.

[0047] The second medium-sized filler, with a particle size range of 5–19.99 μm, accounts for 40%–45% of the total mass.

[0048] Small-particle-size fillers with a particle size range of 1–4.99 μm account for 3%–10% of the total mass.

[0049] In some embodiments, the thermally conductive filler further includes nano-sized alumina with a particle size of 100-500 nm, and the mass percentage of nano-sized alumina in the thermally conductive filler is 1%-5%.

[0050] In the embodiments of this application, the catalyst is one of platinum catalyst, rhodium catalyst and palladium catalyst.

[0051] An inhibitor (also known as a polymerization retarder) is a substance used to inhibit or slow down a chemical reaction, acting similarly to a negative catalyst. It does not stop the polymerization reaction, but only slows it down. In the embodiments of this application, the inhibitor is an alkynylcyclohexanol or an alkynyl alcohol compound.

[0052] This application provides a high-elasticity thermally conductive silicone pad, which is obtained by mixing and cross-linking the aforementioned high-elasticity thermally conductive silicone material.

[0053] In addition, this application provides a method for preparing a highly elastic thermally conductive silicone pad, which includes the following steps using the aforementioned highly elastic thermally conductive silicone material:

[0054] S1. Premix liquid silicone rubber, silicone oil and crosslinking agent for 20-40 minutes to obtain matrix adhesive.

[0055] S2. Knead the matrix adhesive obtained in S1 with the thermally conductive filler once, and the kneading time is 30-60 minutes.

[0056] S3. After kneading evenly once, add the inhibitor, catalyst and colorant in sequence, and knead a second time for 40-80 minutes.

[0057] S4. The raw materials that have been kneaded evenly twice are subjected to vacuum treatment in a vacuum environment. The vacuum degree during vacuuming is -0.07 to -0.1 MPa, and the time is 30 to 60 minutes.

[0058] S5. The vacuum-treated raw material is calendered.

[0059] S6. After calendering, bake at 120-150℃ for 15-30 minutes to obtain a large sheet of high-resilience, high-thermal-conductivity silicone thermal pad.

[0060] S7. Cut the large sheet of high-resilience, high-thermal-conductivity silicone thermal pad into the specified size.

[0061] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0062] Examples 1-4

[0063] This embodiment provides a silicone pad, the preparation process of which is as follows:

[0064] (1) Liquid silicone rubber, silicone oil and hydrogen-containing silicone oil are premixed in a mixer at 2000 rpm for 20 min to obtain a matrix adhesive. The obtained matrix adhesive and thermally conductive filler are placed in a kneader and kneaded for 45 min. Then, alkynyl alcohol inhibitor, platinum catalyst and color paste are added in sequence and kneaded for 60 min.

[0065] Among them, the liquid silicone rubber is methyl vinyl silicone rubber with a molecular weight of 700,000 g / mol; the silicone oil is methyl silicone oil with a viscosity of 100 mPa·s; and the hydrogen-containing silicone oil has a viscosity of 200 mPa·s and a hydrogen content of 0.06%.

[0066] The thermally conductive filler consists of micron-sized alumina particles, micron-sized aluminum nitride particles, and nano-sized alumina particles, with the following particle size distribution:

[0067] Large particle size filler: 80-120μm alumina particles, accounting for 20% by mass;

[0068] Aluminum nitride particles of 80–120 μm, accounting for 20% by mass;

[0069] The first medium-sized filler: alumina particles of 20–79.9 μm, accounting for 10% by mass;

[0070] The second medium-sized filler consists of alumina particles ranging from 5 to 19.9 μm, accounting for 45% by mass.

[0071] Small particle size filler: 1-4.99μm alumina particles, accounting for 4% by mass;

[0072] Particle size filler: 0.1-0.5 μm alumina particles, accounting for 1% by mass.

[0073] (2) After kneading, the raw material is placed in a vacuum environment of -0.1MPa for 40 minutes. The vacuumed raw material is then put into a calender for molding and then baked in an oven at 120℃ for 20 minutes to cure.

[0074] (3) After it is fully cured, cut it into the specified size to obtain a high-elasticity thermally conductive silicone pad.

[0075] The proportions of each raw material are shown in Table 1.

[0076] Table 1: Raw material ratios in Examples 1-3 (unit: g)

[0077]

[0078]

[0079] Comparative Example 1

[0080] It is a silicone material formed from raw materials such as liquid silicone rubber and fillers of different particle sizes, according to Example 1 in CN113563721A.

[0081] Comparative Example 2

[0082] It is a silicone pad made from filler, methyl silicone oil, methyl vinyl silicone rubber and other raw materials, according to Example 1 in CN109777107A.

[0083] Comparative Example 3

[0084] The difference between this preparation method and that of Example 1 is that no large-particle-size filler was added, the mass ratio of other thermally conductive fillers changed accordingly, and the rest is the same as in Example 1.

[0085] Comparative Example 4

[0086] The difference between this preparation method and that of Example 1 is that no first medium-sized filler and second medium-sized filler were added, and the mass ratio of other thermally conductive fillers changed accordingly, while the rest is the same as in Example 1.

[0087] Comparative Example 5

[0088] The difference between this preparation method and that of Example 1 is that no small-particle-size filler was added, the mass ratio of other thermally conductive fillers changed accordingly, and the rest is the same as in Example 1.

[0089] The performance of the silicone pads prepared in Examples 1-3 and the silicone pads in Comparative Examples 1-2 was tested using the following methods:

[0090] Thermal conductivity: Thermal conductivity was tested according to ASTM D 5470 standard;

[0091] Mechanical properties: Tensile strength was tested according to ASTM D 412 standard;

[0092] Compression resilience: The resilience rate is tested according to ASTM D 575-91 standard;

[0093] Flame retardancy: Flame retardancy performance was tested according to UL 94 standard;

[0094] The test results are shown in Table 2.

[0095] Table 2: Performance test data for Examples 1-3

[0096]

[0097] As shown in Table 1, Examples 1 to 4 use the high-elasticity thermally conductive silicone material of this application. In particular, Examples 1 to 3 control the mass ratio of liquid silicone rubber and silicone oil to 1:2 to 1:3, and the resulting silicone pads have the characteristics of high resilience and high thermal conductivity.

[0098] Comparative Examples 1 and 2, which use other silicone pad materials, have poor resilience and thermal conductivity; Comparative Examples 3 and 5, which use the thermally conductive filler of this application, cannot have both high resilience and high thermal conductivity.

[0099] In summary, the high-elasticity thermally conductive silicone material, high-elasticity thermally conductive silicone pad, and preparation method of the embodiments of this application provide a silicone pad with high resilience and high thermal conductivity, ensuring heat dissipation and the normal service life of electronic devices.

[0100] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A highly elastic thermally conductive silicone material, characterized in that, It includes, by weight, parts: 10-20 parts of liquid silicone rubber; 20-40 parts silicone oil; 3-6 parts of crosslinking agent; 800-1200 parts of thermally conductive filler; Inhibitor 0.05~0.15 parts; 2-4 parts catalyst; The thermally conductive filler includes: Large-particle-size fillers with a particle size range of 80~120μm account for 35%~45% of the total mass. Medium-sized fillers with a particle size range of 5~79.9μm account for 45%~60% by mass; Small-particle-size fillers with a particle size range of 1~4.99μm account for 3%~10% of the total mass. The thermally conductive filler is one or more of boron nitride, magnesium oxide, aluminum oxide, aluminum hydroxide, zinc oxide, silicon dioxide, aluminum nitride, and silicon carbide; the mass ratio of the liquid silicone rubber to the silicone oil is 1:2 to 1:

3. The liquid silicone rubber is methyl vinyl silicone rubber with a molecular weight of 400,000 to 1,000,000 g / mol.

2. The high-elasticity thermally conductive silicone material according to claim 1, characterized in that, The silicone oil includes at least one of methyl silicone oil and vinyl silicone oil, wherein the viscosity of the methyl silicone oil is 50-500 mPa·s, the viscosity of the vinyl silicone oil is 100-5000 mPa·s, and the vinyl content is 0.5%-5%.

3. The high-elasticity thermally conductive silicone material according to claim 1, characterized in that, The mass of the crosslinking agent is 5% to 15% of the total mass of the liquid silicone rubber and the silicone oil.

4. The high-elasticity thermally conductive silicone material according to claim 1, characterized in that, The crosslinking agent includes hydrogen-containing silicone oil, which has a viscosity of 100~500 mPa·s and an active hydrogen content of 0.04%~0.4%.

5. The high-elasticity thermally conductive silicone material according to claim 1, characterized in that, The medium-sized filler is divided into a first medium-sized filler with a particle size range of 20~79.9μm and a second medium-sized filler with a particle size range of 5~19.99μm. The mass percentage of the first medium-sized filler in the thermally conductive filler is 5%~15%, and the mass percentage of the second medium-sized filler is 40%~45%.

6. The high-elasticity thermally conductive silicone material according to claim 1, characterized in that, The thermally conductive filler also includes nano-sized alumina with a particle size of 100~500nm, and the mass percentage of the nano-sized alumina in the thermally conductive filler is 1%~5%.

7. The high-elasticity thermally conductive silicone material according to claim 1, characterized in that, It also includes 2 to 4 parts by weight of color paste; And / or, the catalyst is one of a platinum catalyst, a rhodium catalyst, and a palladium catalyst; And / or, the inhibitor is an alkynol compound.

8. A high-elasticity thermally conductive silicone pad, characterized in that, It is obtained by mixing and cross-linking the high-elasticity thermally conductive silicone material as described in any one of claims 1 to 7.

9. A method for preparing a highly elastic thermally conductive silicone pad, characterized in that, It includes the following steps using the highly elastic thermally conductive silicone material as described in any one of claims 1 to 7: Liquid silicone rubber, silicone oil and crosslinking agent are premixed to prepare the matrix adhesive; The matrix adhesive and thermally conductive filler are kneaded once until they are uniformly mixed, and then the inhibitor and catalyst are added in sequence for a second kneading. The raw materials, which are kneaded evenly twice, are vacuum-treated, rolled, and baked in a vacuum environment.

10. The method for preparing the high-elasticity thermally conductive silicone pad according to claim 9, characterized in that, The premixing time is 20-40 minutes; the first kneading time is 30-60 minutes; the second kneading time is 40-80 minutes. And / or, the vacuum level during evacuation is -0.07 to -0.1 MPa, and the time is 30 to 60 minutes; And / or, the baking temperature is 120~150℃, and the baking time is 15~30min.

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