Ultrathin organic silicon gasket filler composition and ultrathin organic silicon gasket

Abstract

The invention provides an ultrathin organic silicon gasket filler composition and an ultrathin organic silicon gasket, and the ultrathin organic silicon gasket filler composition comprises: a powder filler, which comprises the following components in parts by weight: 400-600 parts of spherical or spheroidic alpha-alumina of 20-60 [mu] m, 150-300 parts of spherical alpha-alumina of 5-7 [mu] m, and 150-400 parts of alpha-alumina of 2-3 [mu] m; a surface modifier, which is 1-5 parts of a silane coupling agent; the filler composition is used for an organic silicon gasket with the thickness smaller than or equal to 0.2 mm, and the heat conductivity coefficient of the gasket is larger than or equal to 2.9 W / (m.K). According to the invention, a three-stage particle size compounding design that 20-60 [mu] m spherical / spheroidic alpha-alumina is used as a skeleton, 5-7 [mu] m spherical alpha-alumina is used for filling gaps, and 2-3 [mu] m alpha-alumina is used for optimizing microscopic gaps is adopted, so that a continuous and efficient three-dimensional heat-conducting network is constructed in an ultrathin thickness of less than 0.2 mm; the problems of thermal bottleneck and thermal contact resistance caused by single-particle-size or large-particle-size filler are effectively solved, the heat conductivity coefficient stably reaches 2.9 W / (m.K) or above, and the ultra-thin heat dissipation requirement of high-power electronic equipment is met.

Description

Technical Field

[0001] This application relates to the field of ultrathin silicone gaskets, and particularly to an ultrathin silicone gasket filler composition and an ultrathin silicone gasket. Background Technology

[0002] As electronic devices become increasingly miniaturized and denser, core components such as 5G communication modules and high-power chips place stringent demands on thermal management materials. Ultra-thin silicone pads (thickness ≤ 0.2 mm) have become key materials for achieving efficient heat dissipation in precision components due to their combination of good mechanical cushioning and insulation. However, existing technologies, including those using larger particle size thermally conductive fillers, struggle to achieve high thermal conductivity at ultra-thin thicknesses. When the pad thickness is limited to below 0.2 mm, if a single particle size or an unreasonable particle size distribution thermally conductive filler (such as particles with D50 > 60 μm) is used, large particles can only form a few layers of stacking within a limited space. This results in a large number of unfilled macroscopic voids between particles, forcing heat to be transferred through the silicone matrix with extremely low thermal conductivity, creating a "thermal bottleneck." Simultaneously, the small number of contact points and small contact area between large particles significantly increases contact thermal resistance, further reducing overall thermal conductivity. The aforementioned problems make it difficult to improve the thermal conductivity of existing ultra-thin silicone pads, which cannot meet the heat dissipation requirements of high-power electronic devices and has become a core technical bottleneck restricting their application. Summary of the Invention

[0003] The purpose of this invention is to provide an ultra-thin silicone gasket filler composition and an ultra-thin silicone gasket to solve the technical problems in the prior art.

[0004] An ultrathin silicone pad filler composition comprising:

[0005] The powder filler, by weight, includes: 400-600 parts of spherical or near-spherical α-alumina with a diameter of 20-60μm, 150-300 parts of spherical α-alumina with a diameter of 5-7μm, and 150-400 parts of α-alumina with a diameter of 2-3μm.

[0006] The surface modifier is a silane coupling agent, in the form of 1-5 parts.

[0007] The filler composition is used for silicone gaskets with a thickness ≤0.2mm and the thermal conductivity of the gasket is ≥2.9 W / (m·K).

[0008] Furthermore, the weight ratio of the 20-60μm alumina, 5-7μm alumina, and 2-3μm alumina is (400-600):(150-300):(150-400).

[0009] Furthermore, the silane coupling agent is selected from at least one of aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, vinylsilane coupling agents, and methacryloxysilane coupling agents.

[0010] Furthermore, a method for preparing an ultrathin silicone gasket filler composition includes:

[0011] (a) Stir the three types of alumina with different particle sizes at 300-1200 rpm for 1-3 minutes to obtain a mixed powder;

[0012] (b) Stir the mixed powder with the silane coupling agent at 1000-3000 rpm for 3-10 minutes.

[0013] An ultra-thin silicone gasket with a thickness of 0.18-0.2 mm and a thermal conductivity ≥2.9 W / (m·K).

[0014] The beneficial effects of this application are as follows:

[0015] This application employs a three-level particle size composite design, using 20-60μm spherical / quasi-spherical α-alumina as the skeleton, 5-7μm spherical α-alumina to fill the gaps, and 2-3μm α-alumina to optimize the micropores. This design constructs a continuous and efficient three-dimensional thermal conductive network in ultra-thin thicknesses below 0.2mm, effectively eliminating the "thermal bottleneck" and contact thermal resistance problems caused by single particle size or large particle size fillers (such as 60-80μm). This results in a stable thermal conductivity of over 2.9W / (m·K), meeting the ultra-thin heat dissipation requirements of high-power electronic devices. Detailed Implementation

[0016] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0017] This embodiment provides an ultra-thin silicone gasket filler composition, which aims to solve the problem mentioned in the background art of discontinuous thermal conductivity network and low thermal conductivity efficiency caused by thermally conductive fillers with single particle size or unreasonable particle size distribution in ultra-thin silicone gaskets (thickness ≤ 0.2 mm). The composition achieves a balance between high thermal conductivity and low cost in ultra-thin applications through a three-level particle size compounding design.

[0018] Raw material preparation:

[0019] 20-60μm alumina: Spherical α-alumina with a particle size D50 of 40μm and a weight of 500 parts are selected;

[0020] 5-7μm alumina: Spherical α-alumina with a particle size D50 of 6μm and a weight of 250 parts are selected;

[0021] 2-3μm alumina: Ordinary α-alumina with a particle size D50 of 2.5μm and a weight of 250 parts is selected.

[0022] Surface modifier: A mixture of silane coupling agents (containing aminosilane coupling agent and epoxysilane coupling agent in a weight ratio of 1:1) is selected, with a weight of 2 parts.

[0023] The above-mentioned 20-60μm spherical α-alumina, 5-7μm spherical α-alumina, and 2-3μm ordinary α-alumina were added to a high-speed mixer and stirred at 800 rpm for 2 minutes to obtain a uniformly mixed powder filler A.

[0024] The above-mentioned silane coupling agent mixture was added to powder filler A, the mixer speed was adjusted to 2000 rpm, and the mixture was stirred for 5 minutes to make the silane coupling agent uniformly coat the surface of the alumina particles, thus obtaining the ultra-thin organosilicon gasket filler composition of this application.

[0025] The above-mentioned 1000 parts of filler composition, 100 parts of vinyl-terminated polydimethylsiloxane (viscosity 500 cP), 2.5 parts of hydrogen-containing silicone oil (hydrogen equivalent 0.18%), 0.05 parts of delay agent, and 0.1 parts of platinum catalyst were mixed, vacuum degassed, and then calendered and cured at 130℃ for 15 minutes to prepare ultra-thin silicone gaskets with thicknesses of 0.197 mm, 0.199 mm, and 0.202 mm. The thermal conductivity was tested using a Xiangtan Xiangke DRL-III thermal conductivity meter according to ASTM D5470-12 standard. The results are as follows:

[0026] When the thickness is 0.197 mm, the thermal conductivity is 2.97 W / (m·K);

[0027] When the thickness is 0.199 mm, the thermal conductivity is 2.95 W / (m·K);

[0028] When the thickness is 0.202 mm, the thermal conductivity is 2.99 W / (m·K).

[0029] Meanwhile, observations revealed that the surface of the aforementioned ultra-thin gasket was smooth, without pits or pores, and exhibited excellent flatness.

[0030] This embodiment employs a compound design using alumina with three particle sizes:

[0031] Using 20-60μm spherical α-alumina as a framework, a stable thermally conductive support structure is formed within a thickness of 0.2mm, avoiding the void problem of large-diameter (such as 60-80μm) particles in an ultra-thin space;

[0032] 5-7μm spherical α-alumina fills the gaps in the framework, reducing the macroscopic void volume;

[0033] The 2-3μm α-alumina further optimizes the micro-gap, and the three work together to construct a continuous three-dimensional thermal conductive network, so that the thermal conductivity of the ultrathin gasket is stabilized above 2.9W / (m·K), effectively solving the thermal conductivity bottleneck problem in ultrathin scenarios in the background technology.

[0034] Meanwhile, the use of low-cost α-alumina to replace expensive boron nitride significantly reduces material costs and has advantages for industrial applications.

[0035] Furthermore, in the technical solution of this application, spherical α-alumina is used for 20-60μm and 5-7μm alumina, while ordinary α-alumina is used for 2-3μm alumina. The core difference between the two lies in the particle morphology, packing properties, and functional positioning, as detailed below:

[0036] Spherical α-alumina: The particles exhibit a regular spherical or near-spherical structure, with a smooth surface, uniform particle size distribution, and high sphericity (typically >0.8). This morphology is formed through specific processes (such as melt spraying, high-temperature calcination, etc.) and belongs to modified alumina with optimized morphology.

[0037] Ordinary α-alumina: The particle shape is mostly irregular (such as blocky, angular, etc.), with low sphericity. It is a conventional industrial-grade alumina product that has not undergone special morphology control.

[0038] Spherical α-alumina: Due to its regular shape, the gaps between particles are smaller, enabling a more compact packing (higher packing density). In the ultra-thin (≤0.2mm) scenario of this application, this characteristic can significantly reduce macroscopic voids between particles, avoiding "thermal bottlenecks" and is key to constructing a continuous thermally conductive network. For example, 20-60μm spherical alumina, as a "skeleton," can form a stable support structure within a finite thickness through its close packing; 5-7μm spherical alumina, as a "filler," can be precisely embedded in the gaps of the skeleton, further reducing porosity.

[0039] Ordinary α-alumina: Its irregular shape makes it easy for bridging or voids to form between particles, resulting in a low packing density. However, in this application, the function of 2-3μm ordinary α-alumina is to fill the microscopic gaps (micrometer level) between "skeleton particles and filler particles". Its irregular shape can fill the tiny gaps through multi-directional adhesion, and it does not need to bear the main structural support or high-density packing function. Therefore, there is no need for additional spheroidization treatment.

[0040] Spherical α-alumina (20-60μm and 5-7μm): plays a core role in "skeleton construction" and "gap filling," directly affecting the continuity and structural stability of the thermal conductivity network of ultra-thin gaskets. Its spherical shape is key to achieving "efficient stacking and reduced voids within a thickness of 0.2mm." If ordinary irregular alumina is used, the thermal conductivity path will be interrupted due to excessively large gaps between particles, failing to meet the high thermal conductivity requirements (>2.9 W / (m·K)).

[0041] Ordinary α-alumina (2-3μm): Its sole function is "microscopic gap optimization," used to fill the tiny gaps between spherical particles (such as the small voids around the contact points of spherical particles). Due to its extremely small particle size (2-3μm), even with irregular shapes, it can achieve microscopic-level thermal conductivity network reinforcement through infiltration filling, without the need for high-density packing. Therefore, using the lower-cost ordinary α-alumina can meet the requirements, while reducing the overall material cost.

[0042] Spherical α-alumina requires additional morphology control processes (such as spheroidization and particle size screening), resulting in higher production costs than ordinary α-alumina. This application uses spherical α-alumina only in the "skeleton" and "filler" grade particles where packing performance requirements are stringent, while using ordinary α-alumina in the micro-filler grade particles. This approach balances costs while ensuring thermal conductivity, meeting the technical objective of "low cost and high thermal conductivity."

[0043] In summary, the choice between spherical α-alumina and ordinary α-alumina is based on the functional positioning of particles with different particle sizes and the performance requirements of ultra-thin applications. The two work together to achieve the technical effect of "high-efficiency heat conduction network and low cost".

[0044] It should also be noted that D50 refers to the median diameter of the particle size distribution. Specifically, it means the particle size that represents 50% of the total mass of particles in a batch. That is, 50% of the particles in that batch have a diameter smaller than this value, and the remaining 50% have a diameter larger than this value. For example, in this application, "the D50 of 20-60μm alumina is 40μm" indicates that in that batch of alumina particles, 50% of the particles have a diameter smaller than 40μm, and 50% have a diameter larger than 40μm. 40μm is the median value of the particle size distribution in that batch, reflecting the typical fineness of particles in this grade.

[0045] The embodiments described above are merely preferred embodiments of this application. It should be noted that those skilled in the art can make several improvements and substitutions without departing from the technical principles of this application, and these improvements and substitutions should also be considered within the scope of protection of this application.

Claims

1. A composition for ultra-thin silicone gaskets and fillers, characterized in that, include: The powder filler, by weight, includes: 400-600 parts of spherical or near-spherical α-alumina of 20-60μm, 150-300 parts of spherical α-alumina of 5-7μm, and 150-400 parts of α-alumina of 2-3μm. The surface modifier is a silane coupling agent, consisting of 1-5 parts. The filler composition is used for silicone gaskets with a thickness ≤0.2mm and the thermal conductivity of the gasket is ≥2.9W / (m·K).

2. The ultra-thin silicone gasket filler composition according to claim 1, characterized in that, The weight ratio of the 20-60μm alumina, 5-7μm alumina, and 2-3μm alumina is (400-600):(150-300):(150-400).

3. The ultrathin silicone gasket filler composition according to claim 1, characterized in that, The silane coupling agent is selected from at least one of aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, vinylsilane coupling agents, and methacryloxysilane coupling agents.

4. The ultra-thin silicone gasket filler composition according to claim 1, characterized in that, Its preparation methods include: (a) Stir the three types of alumina at 300-1200 rpm for 1-3 minutes to obtain a mixed powder; (b) Stir the mixed powder with the silane coupling agent at 1000-3000 rpm for 3-10 minutes.

5. An ultrathin silicone pad, characterized in that, The gasket comprises the filler composition according to any one of claims 1 to 4 and an organosilicon matrix, wherein the gasket thickness is 0.18-0.2 mm and the thermal conductivity is ≥2.9 W / (m·K).