High-thermal-conductivity epoxy resin composition for packaging and preparation method therefor

Abstract

Disclosed in the present invention is a high-thermal-conductivity epoxy resin composition for packaging, which is prepared from the following raw materials in parts by weight: 1-5 parts of an epoxy resin, 1-3 parts of a modified epoxy resin, 1-3 parts of a curing agent, 88-95 parts of a thermally conductive filler, 0.5-1 part of a coupling agent, 0.5-1 part of a mold release agent, 0.1-0.5 parts of a low stress agent, and 0.1-0.5 parts of a colorant. In the present invention, by introducing a tertiary amine group-terminated hyperbranched polymer curing agent into an epoxy resin system, the resin composition can still exhibit a good kneading and molding effect when the usage amount of the thermally conductive filler is increased. The combined use of thermally conductive fillers having different particle sizes of 25 μm, 55 μm, and 75 μm can greatly improve the thermal conductivity while meeting packaging and kneading requirements.

Description

A high thermal conductivity epoxy resin composition for encapsulation and its preparation method Technical Field

[0001] This invention relates to the field of chip packaging, and more specifically to an epoxy resin composition for high thermal conductivity packaging and its preparation method. Background Technology

[0002] With technological advancements, electronic products are becoming increasingly integrated, miniaturized, and lightweight, leading to their widespread application. To ensure stable performance, it's crucial to improve the thermal conductivity of chip packaging. While increasing the amount of thermally conductive filler in the encapsulation resin improves thermal conductivity, the improvement diminishes significantly after a certain point. Replacing the filler with a new type increases costs. Therefore, developing an electronic packaging material that offers both excellent thermal conductivity and cost-effectiveness is essential.

[0003] Chinese invention patent CN117106400A discloses a high thermal conductivity epoxy resin adhesive for electronic packaging and its preparation method. It uses two types of spherical alumina powder with different particle sizes to construct more thermally conductive channels. Compared with epoxy resin adhesives containing only a single type of spherical alumina powder, it has lower viscosity, higher thermal conductivity, and better thermal conductivity. However, it has a lower glass transition temperature and poor stability at high temperatures. Chinese invention patent CN113930050B discloses a high thermal conductivity, low viscosity epoxy molding compound and its preparation method. Spherical alumina and flake alumina are chemically bonded together in a specific ratio to form a hybrid filler, which is then rapidly dispersed, mixed, pulverized, and molded with an epoxy molding compound mixture. The resulting epoxy resin molding compound has high thermal conductivity and low internal stress, with a spiral flow length of not less than 50 inches. However, it has low adhesion and poor encapsulation effect. Summary of the Invention

[0004] In order to develop an electronic packaging material with good thermal conductivity and high cost performance, the first aspect of the present invention provides an epoxy resin composition for high thermal conductivity packaging, wherein the raw materials for preparation include, by weight: 1-5 parts epoxy resin, 1-3 parts modified epoxy resin, 1-3 parts curing agent, 88-95 parts thermally conductive filler, 0.5-1 part coupling agent, 0.5-1 part release agent, 0.1-0.5 parts low-stress agent, and 0.1-0.5 parts colorant.

[0005] In a preferred embodiment, the chemical structure of the epoxy resin is as follows:

[0006] In a preferred embodiment, the modified epoxy resin is a phenolic modified epoxy resin, and the epoxy equivalent of the phenolic modified epoxy resin is 190-200 g / eq.

[0007] In a preferred embodiment, the epoxy equivalent of the phenolic modified epoxy resin is 198 g / eq.

[0008] In a preferred embodiment, the curing agent includes at least one of amine curing agents and / or phenolic curing agents, wherein the phenolic curing agent includes at least a biphenyl phenolic curing agent.

[0009] In a preferred embodiment, the phenolic curing agent further includes curing agent II, the structural formula of which is:

[0010] In a preferred embodiment, the amine curing agent is a terminal tertiary amine curing agent, and the curing temperature of the terminal tertiary amine curing agent is 70-90℃, and the curing time is 30-60min.

[0011] In a preferred embodiment, the amine curing agent is a terminal tertiary amine curing agent, and the curing temperature of the terminal tertiary amine curing agent is 80°C, and the curing time is 40-60 min.

[0012] In a preferred embodiment, the weight ratio of the amine curing agent to the phenolic curing agent is (5-10):1.

[0013] In a preferred embodiment, the weight ratio of the amine curing agent to the phenolic curing agent is (6-8):1.

[0014] In a preferred embodiment, the weight ratio of the amine curing agent to the phenolic curing agent is 7:1.

[0015] During their experiments, the inventors discovered that by introducing a terminal tertiary amine-based hyperbranched polymer curing agent into the epoxy resin system, the resin composition still exhibited good mixing and molding performance even with an increased amount of thermally conductive filler. They speculated that this might be because the terminal tertiary amine-based hyperbranched polymer curing agent could react with and modify the epoxy resin, improving its toughness and optimizing its encapsulation and adhesion, thus achieving mixing and molding. However, if the particle size of the thermally conductive filler is too small, its compaction density will be high, which is detrimental to the encapsulation of the epoxy resin system and can easily lead to mixing failure.

[0016] In a preferred embodiment, the thermally conductive filler includes at least one of silicon dioxide, aluminum oxide, and titanium dioxide.

[0017] In a preferred embodiment, the thermally conductive filler is alumina.

[0018] In a preferred embodiment, the alumina has a particle size of 20-80 μm.

[0019] In a preferred embodiment, the alumina has a particle size combination of 20-30μm, 50-60μm, and 70-80μm.

[0020] In a preferred embodiment, the alumina has a particle size combination of 25 μm, 55 μm, and 75 μm.

[0021] In a preferred embodiment, the alumina has a particle size combination of 20-30 μm and 70-80 μm.

[0022] In a preferred embodiment, the alumina has a particle size combination of 25 μm and 75 μm.

[0023] In a preferred embodiment, the alumina has a particle size combination of 20-30 μm and 50-60 μm.

[0024] In a preferred embodiment, the alumina has a particle size combination of 25 μm and 55 μm.

[0025] In a preferred embodiment, the weight ratio of the alumina particles with diameters of 20-30μm, 50-60μm, and 70-80μm is (20-40):(20-40):(20-40).

[0026] In a preferred embodiment, the weight ratio of the alumina particles with diameters of 20-30μm, 50-60μm, and 70-80μm is 31:30:32.

[0027] In a preferred embodiment, the weight ratio of the alumina particles with a diameter of 20-30μm and 70-80μm is (20-40):(50-70).

[0028] In a preferred embodiment, the weight ratio of the alumina particles with a diameter of 20-30μm and 70-80μm is 31:62.

[0029] In a preferred embodiment, the weight ratio of the alumina particles with a diameter of 20-30μm and 50-60μm is (20-40):(50-70).

[0030] In a preferred embodiment, the weight ratio of the alumina particles with a diameter of 20-30μm and 50-60μm is 31:62.

[0031] The inventors further discovered that using thermally conductive fillers with different particle sizes of 25μm, 55μm, and 75μm in combination can significantly improve thermal conductivity while meeting encapsulation and mixing requirements. The reason may be that thermally conductive fillers with different particle sizes can interweave, increasing the packing density and achieving better thermal conductivity. However, using only small-particle-size thermally conductive fillers lacks the skeletal support of larger-particle-size fillers, leading to a decrease in the stress effect of the resin composition and hindering mixing and molding. Conversely, using only large-particle-size thermally conductive fillers results in voids between the fillers, which is detrimental to optimizing thermal conductivity.

[0032] In a preferred embodiment, the alumina is spherical alumina.

[0033] The coupling agent is a silane coupling agent, preferably γ-glycidoxypropylpropyltrimethoxysilane. The stress-reducing agent is propylene-based elastomer (POE). The mold release agent includes, but is not limited to, polyethylene wax; the colorant includes, but is not limited to, carbon black.

[0034] A second aspect of the present invention provides a method for preparing an epoxy resin composition for high thermal conductivity encapsulation, comprising the following steps:

[0035] S1 mixes epoxy resin, modified epoxy resin, curing agent, thermally conductive filler, coupling agent, release agent, low-stress agent, and colorant in proportion to weight, places them in a mixer and mixes at 120-130℃ for 5-10 minutes, then discharges the material.

[0036] S2 is cooled to room temperature and then pulverized to 1-3mm to obtain pulverized material;

[0037] S3 compacts, shapes, and packages the pulverized material before discharging it.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The epoxy resin composition for high thermal conductivity encapsulation described in this invention, by introducing a terminal tertiary amine hyperbranched polymer curing agent into the epoxy resin system, can still have a good mixing and molding effect after the amount of thermally conductive filler used is increased.

[0040] (2) The high thermal conductivity epoxy resin composition for encapsulation described in this invention uses thermally conductive fillers with different particle sizes of 25μm, 55μm and 75μm, which can significantly improve thermal conductivity while meeting the requirements of encapsulation and mixing.

[0041] (3) The high thermal conductivity epoxy resin composition for encapsulation of the present invention introduces 93% by mass of thermally conductive filler, which improves the thermal conductivity of the epoxy resin composition without affecting the stress and encapsulation performance of the epoxy resin composition.

[0042] (4) The high thermal conductivity epoxy resin composition for encapsulation described in this invention uses spherical alumina of different particle sizes as thermally conductive fillers, achieving a thermal conductivity of 5W, without affecting the fluidity and mixing molding effect.

[0043] (5) The high thermal conductivity epoxy resin composition for packaging described in this invention can be applied to the packaging of electronic products with high heat dissipation requirements, such as QFN type packaging, DIP type packaging, and FC type packaging. Detailed Implementation

[0044] An epoxy resin composition for high thermal conductivity encapsulation is prepared by means of raw materials, as detailed in Tables 1-2 below.

[0045] Table 1

[0046] Table 2

[0047] The chemical structure of the epoxy resin is as follows: Purchased from DIC, brand name HP-7200.

[0048] The modified epoxy resin is a phenolic modified epoxy resin with an epoxy equivalent of 198 g / eq, purchased from Chang Chun in Taiwan, and its brand name is CNE 195LL.

[0049] The structural formula of the curing agent II is: Purchased from Shandong Shengquan, brand name PF-8011.

[0050] The biphenyl phenolic curing agent was purchased from Shanghai Hengfeng and its brand name is ResiCare 3900.

[0051] The terminal tertiary amine curing agent, with a curing temperature of 80℃ and a curing time of 60 min, was purchased from Shanghai Wujing Chemical Co., Ltd., and its brand name is QNP1-4085.

[0052] The γ-glycidyl etheroxypropylpropyltrimethoxysilane was purchased from Shin-Yue Chemical, model number KH-560.

[0053] The propylene-based elastomer POE was purchased from ExxonMobil and its grade is POE 3588FL.

[0054] The release agent is polyethylene wax, purchased from Hebei Tianyu Chemical Co., Ltd., brand name: TY-113.

[0055] The colorant is carbon black.

[0056] 25μm alumina was purchased from Denki Chemical, grade DAD-023; 55μm alumina was purchased from Denki Chemical, grade DAD-057; 75μm alumina was purchased from Denki Chemical, grade DAD-072.

[0057] A method for preparing a high thermal conductivity epoxy resin composition for encapsulation includes the following steps:

[0058] S1 mixes epoxy resin, modified epoxy resin, curing agent, thermally conductive filler, coupling agent, release agent, low-stress agent and colorant in parts by weight, places them in a mixer and mixes at 125°C for 10 minutes, then discharges the material.

[0059] S2 is cooled to room temperature and then pulverized to 1-3mm to obtain pulverized material;

[0060] S3 compacts, shapes, and packages the pulverized material before discharging it.

[0061] Performance testing

[0062] 1. Curing time: Raise the temperature of the hot plate to 175℃ and maintain it within ±1℃. Place 0.5-1.5g of sample on the hot plate and press it into a 6cm shape using a flat spatula. 2 -10cm 2 For thin slices, when the sample melts and the surface of the melt becomes glossy, press the stopwatch to start timing. Use a flat spatula to continuously scrape the sample and observe, or use a needle-shaped stirring rod to continuously stir the sample and observe. The timer stops when the sample changes from a molten state to a gel state. The time required is the gelation time of the sample.

[0063] 2. Spiral flow length: When the mold temperature is constant at 175℃, weigh 15-25g of powdered sample and pour it into the mold cavity for injection molding. Turn on and start timing; after automatic mold opening, remove the mold and open it to read the length of the longest continuous point.

[0064] 3. Glass Transition Temperature (Tg): The sample is mounted on the TMA stage. The initial temperature is 20℃, the heating rate is 10℃ / min, and the final temperature is 220℃. After scanning, the TMA test curve is obtained. Tangents are plotted at temperatures above and below the transition temperature. The temperature at the intersection of the two tangents is the glass transition temperature (Tg).

[0065] 4. Coefficient of thermal expansion: TMA: The sample is mounted on the TMA sample stage, with a starting temperature of 20℃, a heating rate of 10℃ / min, and a final temperature of 220℃. After scanning, the TMA test curve is obtained, and the coefficient of thermal expansion is obtained from the equipment reading.

[0066] 5. Molding shrinkage: Inject the epoxy molding compound into a 120mm×15mm×10mm sample. After injection molding, measure the difference between the sample and the mold.

[0067] 6. Thermal conductivity: Tested according to GB / T3139-2005 standard.

[0068] 7. Flexural modulus at 25℃: Tested according to GB / T3139-2005 standard.

[0069] 8. Bending strength at 25℃: Tested according to GB / T3139-2005 standard.

[0070] The test results are shown in Table 3.

[0071] Table 3

[0072] Note: The mixing process in Example 4 failed, and performance testing could not be performed.

[0073] Conclusions: In Examples 1-3, the alumina content was 90%, resulting in poor thermal conductivity (only 3W). In Example 4, the alumina content increased to 93%, but the unsuitable particle size led to mixing failure. In Example 5, the alumina content increased to 93% with a particle size of 55μm, but the improvement in thermal conductivity was not significant. In Example 6, the alumina content increased to 93% with a particle size of 75μm, but the improvement in thermal conductivity was not significant. In Example 7, the alumina content increased to 93%, and a combination of 25μm and 55μm particles met the requirements. In Example 8, the alumina content increased to 93%, and a combination of 25μm and 75μm particles met the requirements. In Example 9, the alumina content increased to 93%, and a combination of 55μm and 75μm particles did not significantly improve thermal conductivity. In Example 10, the alumina content increased to 93%, and a combination of 25μm, 55μm, and 75μm particles met the thermal conductivity requirements.

Claims

1. A high thermal conductivity epoxy resin composition for encapsulation, characterized in that, The raw materials for preparation include, by weight: 1-5 parts epoxy resin, 1-3 parts modified epoxy resin, 1-3 parts curing agent, 88-95 parts thermally conductive filler, 0.5-1 part coupling agent, 0.5-1 part release agent, 0.1-0.5 parts low-stress agent, and 0.1-0.5 parts colorant.

2. The epoxy resin composition for high thermal conductivity encapsulation according to claim 1, characterized in that, The modified epoxy resin is a phenolic modified epoxy resin, and the epoxy equivalent of the phenolic modified epoxy resin is 190-200 g / eq.

3. The epoxy resin composition for high thermal conductivity encapsulation according to claim 1, characterized in that, The curing agent includes at least one of amine curing agents and / or phenolic curing agents, wherein the phenolic curing agent includes at least a biphenyl phenolic curing agent.

4. The epoxy resin composition for high thermal conductivity encapsulation according to claim 3, characterized in that, The amine curing agent is a terminal tertiary amine curing agent, and the curing temperature of the terminal tertiary amine curing agent is 70-90℃, and the curing time is 30-60min.

5. The epoxy resin composition for high thermal conductivity encapsulation according to claim 3, characterized in that, The weight ratio of the amine curing agent to the phenolic curing agent is (5-10):

1.

6. The epoxy resin composition for high thermal conductivity encapsulation according to claim 1, characterized in that, The thermally conductive filler includes at least one of silicon dioxide, aluminum oxide, and titanium dioxide.

7. The epoxy resin composition for high thermal conductivity encapsulation according to claim 5, characterized in that, The alumina has a particle size of 20-80 μm.

8. The epoxy resin composition for high thermal conductivity encapsulation according to claim 5, characterized in that, The particle size of the alumina is selected from at least one of the particle size combinations of 20-30μm, 50-60μm, and 70-80μm.

9. The epoxy resin composition for high thermal conductivity encapsulation according to claim 8, characterized in that, The weight ratio of the alumina particles with diameters of 20-30μm, 50-60μm, and 70-80μm is (20-40):(20-40):(20-40).

10. A method for preparing a high thermal conductivity epoxy resin composition for encapsulation according to any one of claims 1-9, characterized in that, Includes the following steps: S1 mixes epoxy resin, modified epoxy resin, curing agent, thermally conductive filler, coupling agent, release agent, low-stress agent, and colorant in proportion to weight, places them in a mixer and mixes at 120-130℃ for 5-10 minutes, then discharges the material. S2 is cooled to room temperature and then pulverized to 1-3mm to obtain pulverized material; S3 compacts, shapes, and packages the pulverized material before discharging it.

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