Epoxy resin composite material with low thermal expansion coefficient, cured product and application thereof

Abstract

The application belongs to the technical field of electronic packaging materials, and more particularly relates to an epoxy resin composite material with a low thermal expansion coefficient, a cured product and applications. The epoxy resin composite material with a low thermal expansion coefficient, a high thermal conductivity and good fluidity is prepared through the synergistic effect of the negative thermal expansion filler, the heat-conducting filler, the epoxy resin and the curing agent, so that the epoxy resin composite material has good fluidity and filling property when being plastic encapsulated, can better perform encapsulation operation, improve encapsulation effect, and thus effectively improve the working stability of electronic components and prolong the working life, and has a wide application prospect in the field of electronic packaging materials.

Description

Technical Field

[0001] This application belongs to the field of electronic packaging materials technology, and more specifically, relates to an epoxy resin composite material with a low coefficient of thermal expansion, a cured product, and its application. Background Technology

[0002] Integrated circuits are an important pillar of the modern information industry and are widely used in communications, computers, aerospace and other fields. Flip chip packaging is the main form of chip-level electronic packaging at present, and generally adopts the underfill packaging process. An ideal underfill electronic packaging material should have the following characteristics: (1) a suitable coefficient of thermal expansion to ensure that the thermal stress on the solder joints under high and low temperature cycling can be effectively dispersed and prevent the solder joints from cracking; (2) excellent thermal conductivity to ensure that the heat generated by the chip during operation can be transferred out in time; (3) good flow properties to ensure that the packaging material can fully fill the gap between the chip and the substrate.

[0003] Currently, most integrated circuits are packaged in plastics, with epoxy resin accounting for 90% of the plastic packaging market share due to its excellent chemical and corrosion resistance, electrical insulation properties, mechanical strength, adhesive strength, and low curing shrinkage. However, the high coefficient of thermal expansion of epoxy resin leads to a mismatch between its coefficient of thermal expansion and that of the chip and silicon substrate. When the ambient temperature rises or falls, the epoxy resin expands or contracts significantly, and the resulting thermal stress causes solder joints to detach and components to fail. Furthermore, the low thermal conductivity of epoxy resin prevents it from effectively dissipating the heat generated during chip operation, leading to heat accumulation within the electronic packaging system, which in turn reduces chip performance and shortens its lifespan.

[0004] Inorganic fillers such as silica, aluminum oxide, boron nitride, aluminum nitride, and silicon carbide are characterized by low coefficients of thermal expansion and high thermal conductivity. Epoxy resins are often composited with these inorganic fillers to reduce the coefficient of thermal expansion and improve thermal conductivity. However, existing modification methods primarily use inorganic fillers with positive thermal expansion characteristics, often requiring high filler content (>50 vol%) to reduce the coefficient of thermal expansion of the composite system to a reasonable range. This high filler content leads to excessively high viscosity and poor processing flowability in the composite system. Designing and preparing high-performance epoxy resin composites with low coefficients of thermal expansion, high thermal conductivity, and low processing viscosity presents a significant challenge. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide an epoxy resin composite material with a low coefficient of thermal expansion, a cured product and its application, aiming to solve the problem that existing epoxy resin composite materials cannot simultaneously possess a low coefficient of thermal expansion, high thermal conductivity and low processing viscosity.

[0006] To achieve the above objectives, this application provides an epoxy resin composite material with a low coefficient of thermal expansion. By mass, the epoxy resin composite material comprises 5 to 50 parts of negative thermal expansion filler, 5 to 70 parts of thermally conductive filler, 12 to 35 parts of epoxy resin, and 0.3 to 18 parts of curing agent.

[0007] Preferably, the chemical formula of the above-mentioned negative thermal expansion filler is Zn. (2-x) M x P2O7, where M is a transition metal element and 0 < x < 2.

[0008] More preferably, the M element is selected from any one of Cu, Mg, Ca, Mn, Fe, Co, Ni, Ba, and Sr.

[0009] Preferably, the negative thermal expansion filler is random particles with an average particle size of 0.1 μm to 30 μm.

[0010] Preferably, the thermally conductive filler is spherical or near-spherical particles with an average particle size of 0.1 μm to 30 μm, selected from one or more of alumina, aluminum nitride, and boron nitride.

[0011] Preferably, the epoxy resin is one or more of bisphenol A type epoxy resin, bisphenol S type epoxy resin, bisphenol F type epoxy resin, phenolic epoxy resin and liquid crystal epoxy resin.

[0012] Preferably, the curing agent is one or more of 2-methylimidazole, 2,4-dimethylimidazole, 2-ethylimidazole, 2-phenylimidazole, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, triethylenetetramine, and isophorone diamine.

[0013] This application provides the application of the above-mentioned epoxy resin composite material in the encapsulation of electronic components.

[0014] Preferably, the aforementioned electronic components are one or more of the following: chips, transistors, LEDs, and resistive, capacitive, and inductive components.

[0015] On the other hand, this application provides a cured product comprising the above-mentioned epoxy resin composite material.

[0016] This application also provides an encapsulation device comprising the aforementioned cured material.

[0017] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages:

[0018] (1) This application improves the overall performance of epoxy resin composite materials by compounding negative thermal expansion filler, thermally conductive filler, epoxy resin and curing agent through the synergistic effect between the components, making it have low coefficient of thermal expansion, high thermal conductivity and low processing viscosity. The above-mentioned epoxy resin composite material has a wide process operation window, which is conducive to ensuring good flowability and filling properties during molding, better encapsulation operation, improving the encapsulation effect, and thus effectively improving the working stability and extending the service life of electronic components. It has broad application prospects in the field of electronic packaging materials.

[0019] (2) In a preferred embodiment, this application uses spherical or near-spherical thermally conductive fillers in combination with other components. While improving the thermal conductivity of the epoxy resin composite material, the fillers work synergistically with the negative thermal expansion fillers to effectively reduce the friction between fillers, significantly improving the processing fluidity of the system and reducing processing difficulty. In addition, spherical or near-spherical thermally conductive fillers can also work synergistically with the negative thermal expansion fillers to effectively reduce the coefficient of thermal expansion of the system. This can significantly reduce the coefficient of thermal expansion of the system with a relatively low filler content, while effectively avoiding the problem of high processing viscosity caused by high filler content. Attached Figure Description

[0020] Figure 1 This is a graph showing the relationship between the apparent viscosity and shear rate of the epoxy resin composite materials prepared in Examples 1, 1, 2, and 3 of this application at 25°C.

[0021] Figure 2 The thermal conductivity and coefficient of thermal expansion of the cured products prepared in Examples 1, 1, 2, and 3 of this application are the properties of the product. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0023] This application provides an epoxy resin composite material with a low coefficient of thermal expansion. By mass, the epoxy resin composite material comprises 5 to 50 parts of negative thermal expansion filler, 5 to 70 parts of thermally conductive filler, 12 to 35 parts of epoxy resin, and 0.3 to 18 parts of curing agent.

[0024] In some embodiments, the chemical formula of the aforementioned negative thermal expansion filler is Zn. (2-x) M x P2O7, where M is a transition metal element and 0 < x < 2.

[0025] In some embodiments, the M element is selected from any one of Cu, Mg, Ca, Mn, Fe, Co, Ni, Ba, and Sr.

[0026] In some embodiments, the negative thermal expansion filler is composed of random particles with an average particle size of 0.1 μm to 30 μm.

[0027] In some embodiments, the thermally conductive filler is spherical or near-spherical particles with an average particle size of 0.1 μm to 30 μm, selected from one or more of alumina, aluminum nitride, and boron nitride.

[0028] In some embodiments, the epoxy resin is one or more of bisphenol A type epoxy resin, bisphenol S type epoxy resin, bisphenol F type epoxy resin, phenolic epoxy resin, and liquid crystal epoxy resin.

[0029] In some embodiments, the curing agent is one or more of 2-methylimidazole, 2,4-dimethylimidazole, 2-ethylimidazole, 2-phenylimidazole, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, triethylenetetramine, and isophorone diamine.

[0030] In some embodiments, the epoxy resin composite material provided in this application can be prepared by stirring and mixing the various components. It is understood that this application does not limit the above-described stirring and mixing method; as long as uniform mixing of the components can be achieved, it is within the scope of protection of this application.

[0031] The epoxy resin composite material provided in this application cures upon heating, and the epoxy resin can chemically react with the curing agent to form a three-dimensional network polymer. After curing, the epoxy resin composite material transforms into a cured product of a certain shape, which can be a film, sheet, or have a three-dimensional structure. The epoxy resin composite material in this application is typically liquid and can be directly used as a liquid adhesive, forming an adhesive layer after coating, filling, and curing. Furthermore, the epoxy resin composite material can be transformed into a easily stored solid molding compound (the epoxy resin is not fully cross-linked and cured) after mixing and curing. This molding compound can be granular, sheet-like, or lumpy, and can subsequently be converted into a cured product of a certain shape using common molding processes.

[0032] This application provides the application of the above-described epoxy resin composite material in the encapsulation of electronic components. For example, it is used as an encapsulation material for electronic components. In some embodiments, the above-described epoxy resin composite material is used to form a molding compound covering the electronic components to fix and protect them. The electronic components may be, but are not limited to, chips, transistors (such as diodes and triodes), LEDs, and resistive-capacitive-inductive components (such as resistors, capacitors, and inductors).

[0033] This application provides a cured product comprising the aforementioned epoxy resin composite material. It is understood that the cured product can be used to cure the epoxy resin composite material into various shapes, such as, but not limited to, thin films, sheets, or three-dimensional structures, according to actual needs, and applied to the surface of electronic components requiring encapsulation to form a molding compound protecting various electronic components.

[0034] In some embodiments, this application provides a method for preparing the above-mentioned cured material, comprising the following steps:

[0035] The negative thermal expansion filler, thermally conductive filler, epoxy resin and curing agent are mixed according to the formula, degassed, and cured to obtain a cured product with a low coefficient of thermal expansion.

[0036] This application does not limit the source of the aforementioned negative thermal expansion filler, which can be prepared independently. In some embodiments, the preparation method of the aforementioned negative thermal expansion filler is as follows:

[0037] Transition metal oxides, zinc oxide, and phosphoric acid compounds are mixed according to atomic ratios. The mixed powder is then ground and dried to obtain a negative thermal expansion filler precursor. The negative thermal expansion filler precursor is then calcined at least twice, cooled, and ground to obtain the negative thermal expansion filler.

[0038] In some embodiments, the aforementioned transition metal oxide is any one of magnesium oxide, copper oxide, calcium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, barium oxide, or strontium oxide.

[0039] In some embodiments, the aforementioned phosphoric acid compound is one or more of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, phosphoric acid, metaphosphoric acid, and pyrophosphoric acid.

[0040] In some embodiments, the grinding process is ball milling or sand milling, specifically involving grinding the mixed powder with grinding media and grinding aids. In some embodiments, the grinding media are grinding balls, and the grinding aids are one or more of ethanol, isopropanol, acetone, and deionized water.

[0041] In some embodiments, the mass ratio of the mixed powder, grinding media and grinding aid in the above grinding process is 1:(5-10):(1-2).

[0042] In some embodiments, the above calcination specifically involves: pre-calcining the negative thermal expansion filler precursor at a temperature of 600°C to 800°C for 1 hour to 4 hours; and then performing a second calcination at a temperature of 800°C to 1000°C for 1 hour to 4 hours.

[0043] In some embodiments, the curing conditions are: pre-curing at 60°C to 100°C for 1 to 3 hours, followed by curing at 120°C to 180°C for 3 to 8 hours.

[0044] This application also provides an encapsulation device comprising the aforementioned cured material.

[0045] It should be understood that materials of the same or similar type, model, quality, properties, or function as the reagents and instruments used in the following embodiments can be used to implement this application. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0046] The following are examples and comparative examples:

[0047] Example 1

[0048] The epoxy resin composite material with a low coefficient of thermal expansion provided in this embodiment includes, by weight, 31 parts of zinc magnesium pyrophosphate powder (Zn 1.6 Mg 0.4 The mixture contains 29 parts of spherical alumina (P2O7), 23 parts of bisphenol F epoxy resin, 16.98 parts of methylhexahydrophthalic anhydride, and 0.02 parts of 2,4-dimethylimidazole, wherein the average particle sizes of zinc magnesium pyrophosphate powder and alumina are 2 μm and 5 μm, respectively.

[0049] The preparation steps of the above-mentioned epoxy resin composite material with low coefficient of thermal expansion are as follows:

[0050] (1) Preparation of zinc magnesium pyrophosphate precursor: Magnesium oxide, zinc oxide and ammonium dihydrogen phosphate were mixed in a molar ratio of 0.4:1.6:2. Then the mixed powder, agate grinding balls and ethanol were mixed evenly in a mass ratio of 1:7:2 and ball-milled at a speed of 300 rpm for 3 hours. Finally, the ball-milled product was dried to obtain zinc magnesium pyrophosphate precursor.

[0051] (2) Preparation of zinc magnesium pyrophosphate powder: The above zinc magnesium pyrophosphate precursor was precalcined at a temperature of 800℃ and a time of 2h. After the product was cooled to room temperature, it was calcined again at a temperature of 900℃ and a time of 2h. After cooling, the calcined product was ground in the manner of step (1) to obtain zinc magnesium pyrophosphate powder with an average particle size of 2μm.

[0052] (3) Preparation of epoxy resin composite material: The above zinc magnesium pyrophosphate powder, spherical alumina and bisphenol F type epoxy resin are mixed according to the ratio, and then methyl hexahydrophthalic anhydride and 2,4-dimethylimidazole are added, mixed and degassed to obtain epoxy resin composite material with low thermal expansion coefficient.

[0053] The preparation steps for cured products with low coefficients of thermal expansion are as follows:

[0054] The above-mentioned epoxy resin composite material was subjected to curing treatment, wherein the curing conditions were pre-curing at 100℃ for 2 hours and then curing at 150℃ for 5 hours to obtain a cured product with a low coefficient of thermal expansion.

[0055] Example 2

[0056] The epoxy resin composite material with a low coefficient of thermal expansion provided in this embodiment includes, by weight, 5 parts of zinc copper pyrophosphate powder (Zn). 1.8 Cu 0.2 The mixture consists of 30 parts of P2O7, 30 parts of spherical alumina, 30 parts of spherical aluminum nitride, 34.7 parts of bisphenol A type epoxy resin, and 0.3 parts of 2,4-dimethylimidazole, wherein the average particle sizes of zinc copper pyrophosphate powder, alumina, and aluminum nitride are 30 μm, 10 μm, and 20 μm, respectively.

[0057] The preparation steps of the above-mentioned epoxy resin composite material with low coefficient of thermal expansion are as follows:

[0058] (1) Preparation of zinc copper pyrophosphate precursor: copper oxide, zinc oxide and diammonium hydrogen phosphate were mixed in a molar ratio of 0.2:1.8:2. Then the mixed powder, agate grinding ball and isopropanol were mixed evenly in a mass ratio of 1:5:2 and sand milled at a speed of 200 rpm for 3 hours. Finally, the sand milled product was dried to obtain zinc copper pyrophosphate precursor.

[0059] (2) Preparation of zinc copper pyrophosphate powder: The above zinc copper pyrophosphate precursor was precalcined at a temperature of 600℃ and a time of 1h. After the product was cooled to room temperature, it was calcined again at a temperature of 800℃ and a time of 3h. After cooling, the calcined product was ground in the manner of step (1) to obtain zinc copper pyrophosphate powder with an average particle size of 30μm.

[0060] (3) Preparation of epoxy resin composite material: The above zinc copper pyrophosphate powder, alumina, aluminum nitride and bisphenol A type epoxy resin are mixed according to the ratio, and then 2,4-dimethylimidazole is added for mixing and degassing to obtain epoxy resin composite material with low thermal expansion coefficient.

[0061] The preparation steps for cured products with low coefficients of thermal expansion are as follows:

[0062] The above-mentioned epoxy resin composite material was subjected to curing treatment, wherein the curing conditions were pre-curing at 60℃ for 2 hours and then curing at 150℃ for 8 hours to obtain a cured product with a low coefficient of thermal expansion.

[0063] Example 3

[0064] The epoxy resin composite material with a low coefficient of thermal expansion provided in this embodiment includes, by weight, 40 parts of zinc calcium pyrophosphate powder (Zn 1.5 Ca 0.5 The mixture consists of 40 parts of P2O7, 40 parts of near-spherical boron nitride, 12.5 parts of liquid crystal epoxy resin, and 7.5 parts of triethylenetetramine, wherein the average particle sizes of zinc calcium pyrophosphate powder and boron nitride are 0.1 μm and 5 μm, respectively.

[0065] The preparation steps of the above-mentioned epoxy resin composite material with low coefficient of thermal expansion are as follows:

[0066] (1) Preparation of zinc calcium pyrophosphate precursor: calcium oxide, zinc oxide and phosphoric acid were mixed in a molar ratio of 0.5:1.5:2. Then the mixed powder, agate grinding balls and deionized water were mixed evenly in a mass ratio of 1:10:1 and ball-milled at a speed of 500 rpm for 6 hours. Finally, the ball-milled product was dried to obtain zinc calcium pyrophosphate precursor.

[0067] (2) Preparation of zinc calcium pyrophosphate powder: The above zinc calcium pyrophosphate precursor was precalcined at a temperature of 700℃ and a time of 3h. After the product was cooled to room temperature, it was calcined again at a temperature of 1000℃ and a time of 1h. After cooling, the calcined product was ground in the manner of step (1) to obtain zinc calcium pyrophosphate powder with an average particle size of 0.1μm.

[0068] (3) Preparation of epoxy resin composite material: The above zinc calcium pyrophosphate powder, near-spherical boron nitride and liquid crystal epoxy resin are mixed according to the ratio, and then triethylenetetramine is added for mixing and degassing to obtain epoxy resin composite material with low thermal expansion coefficient.

[0069] The preparation steps for cured products with low coefficients of thermal expansion are as follows:

[0070] The above-mentioned epoxy resin composite material was subjected to curing treatment, wherein the curing conditions were pre-curing at 60℃ for 3 hours and then curing at 120℃ for 5 hours to obtain a cured product with a low coefficient of thermal expansion.

[0071] Example 4

[0072] The epoxy resin composite material with low thermal expansion coefficient provided in this embodiment includes, by mass parts, 10 parts of zinc manganese pyrophosphate powder (Zn1Mn1P2O7), 55 parts of near-spherical boron nitride, 9 parts of bisphenol S type epoxy resin, 10 parts of bisphenol A type epoxy resin, 15.98 parts of methyltetrahydrophthalic acid and 0.02 parts of 2-ethylimidazole, wherein the average particle size of zinc manganese pyrophosphate powder and boron nitride is 10 μm.

[0073] The preparation method of the above-mentioned epoxy resin composite material with low coefficient of thermal expansion includes the following steps:

[0074] (1) Preparation of zinc manganese pyrophosphate precursor: Manganese oxide, zinc oxide and metaphosphoric acid were mixed in a molar ratio of 1:1:2. Then, the mixed powder, agate grinding ball and acetone were mixed evenly in a mass ratio of 1:8:1 and then sand milled at a speed of 300 rpm for 4 hours. Finally, the sand milled product was dried to obtain zinc manganese pyrophosphate precursor.

[0075] (2) Preparation of zinc manganese pyrophosphate powder: The above zinc manganese pyrophosphate precursor was precalcined at a temperature of 750°C and a time of 2 hours. After the product was cooled to room temperature, it was calcined again at a temperature of 850°C and a time of 2 hours. After cooling, the calcined product was ground in the manner of step (1) to obtain zinc manganese pyrophosphate powder with an average particle size of 10 μm.

[0076] (3) Preparation of epoxy resin composite material: The above zinc manganese pyrophosphate powder, near-spherical boron nitride, bisphenol S type epoxy resin and bisphenol A type epoxy resin are mixed according to the ratio, and then methyltetrahydrophthalic anhydride and 2-ethylimidazole are added and mixed and degassed to obtain epoxy resin composite material with low thermal expansion coefficient.

[0077] The preparation steps for cured products with low coefficients of thermal expansion are as follows:

[0078] The above-mentioned epoxy resin composite material was subjected to curing treatment, wherein the curing conditions were pre-curing at 100℃ for 1 hour and then curing at 180℃ for 5 hours to obtain a cured product with a low coefficient of thermal expansion.

[0079] Example 5

[0080] The epoxy resin composite material with a low coefficient of thermal expansion provided in this embodiment includes, by weight, 50 parts of zinc iron pyrophosphate powder (Zn). 1.4 Fe 0.6 The mixture consists of 20 parts of spherical alumina (P2O7), 12 parts of bisphenol F epoxy resin, 12 parts of bisphenol A epoxy resin, and 6 parts of isophorone diamine, wherein the average particle sizes of zinc iron pyrophosphate powder and alumina are 10 μm and 15 μm, respectively.

[0081] The preparation steps of the above-mentioned epoxy resin composite material with low coefficient of thermal expansion are as follows:

[0082] (1) Preparation of zinc iron pyrophosphate precursor: Iron oxide, zinc oxide, pyrophosphate and metaphosphoric acid were mixed in a molar ratio of 1.4:0.6:1:1. Then the mixed powder was mixed with agate grinding balls and acetone in a mass ratio of 1:9:1 and ball-milled at a speed of 200 rpm for 5 h. Finally, the ball-milled product was dried to obtain zinc iron pyrophosphate precursor.

[0083] (2) Preparation of zinc iron pyrophosphate powder: The above zinc iron pyrophosphate precursor was precalcined at a temperature of 800℃ and a time of 1h. After the product was cooled to room temperature, it was calcined again at a temperature of 900℃ and a time of 4h. After cooling, the calcined product was ground in the manner of step (1) to obtain zinc iron pyrophosphate powder with negative thermal expansion filler and an average particle size of 10μm.

[0084] (3) Preparation of epoxy resin composite material: The zinc iron pyrophosphate powder, spherical alumina, bisphenol F type epoxy resin and bisphenol A type epoxy resin are mixed according to the ratio, and then isophorone diamine is added for mixing and degassing to obtain epoxy resin composite material with low thermal expansion coefficient.

[0085] The preparation steps for cured products with low coefficients of thermal expansion are as follows:

[0086] The above-mentioned epoxy resin composite material was subjected to curing treatment, wherein the curing conditions were pre-curing at 80℃ for 2 hours and then curing at 120℃ for 6 hours to obtain a cured product with a low coefficient of thermal expansion.

[0087] Example 6

[0088] The epoxy resin composite material with a low coefficient of thermal expansion provided in this embodiment includes, by weight, 5 parts of zinc cobalt pyrophosphate powder (Zn). 0.5 Co 1.5 The mixture consists of 70 parts of P2O7, 70 parts of spherical aluminum nitride, 23 parts of phenolic epoxy resin, and 2 parts of 2-ethylimidazole, wherein the average particle sizes of zinc cobalt pyrophosphate powder and aluminum nitride are 5 μm and 1 μm, respectively.

[0089] The preparation steps of the above-mentioned epoxy resin composite material with low coefficient of thermal expansion are as follows:

[0090] (1) Preparation of zinc cobalt pyrophosphate precursor: Cobalt oxide, zinc oxide and diammonium hydrogen phosphate were mixed in a molar ratio of 1.5:0.5:2. Then the mixed powder, agate grinding ball and isopropanol were mixed evenly in a mass ratio of 1:6:1 and sand milled at a speed of 400 rpm for 3 hours. Finally, the sand milled product was dried to obtain zinc cobalt pyrophosphate precursor.

[0091] (2) Preparation of zinc cobalt pyrophosphate powder: The above zinc cobalt pyrophosphate precursor was precalcined at a temperature of 600℃ and a time of 4h. After the product was cooled to room temperature, it was calcined again at a temperature of 950℃ and a time of 1h. After cooling, the calcined product was ground in the manner of step (1) to obtain zinc cobalt pyrophosphate powder with an average particle size of 5μm.

[0092] (3) Preparation of epoxy resin composite material: The above zinc cobalt pyrophosphate powder, spherical aluminum nitride and phenolic epoxy resin are mixed according to the ratio, and then 2-ethylimidazolium is added for mixing and degassing to obtain epoxy resin composite material with low thermal expansion coefficient.

[0093] The preparation steps for cured products with low coefficients of thermal expansion are as follows:

[0094] The above-mentioned epoxy resin composite material was subjected to curing treatment, wherein the curing conditions were pre-curing at 60℃ for 2 hours and then curing at 170℃ for 3 hours to obtain a cured product with a low coefficient of thermal expansion.

[0095] Example 7

[0096] The epoxy resin composite material with a low coefficient of thermal expansion provided in this embodiment includes, by weight, 35 parts of zinc nickel pyrophosphate powder (Zn). 1.5 Ni 0.5 The mixture contains 45 parts of P2O7, 45 parts of spherical aluminum nitride, 18 parts of bisphenol A type epoxy resin, and 2 parts of 2-ethylimidazole, wherein the average particle sizes of zinc nickel pyrophosphate powder and aluminum nitride are 10 μm and 5 μm, respectively.

[0097] The preparation steps of the above-mentioned epoxy resin composite material with low coefficient of thermal expansion are as follows:

[0098] (1) Preparation of zinc nickel pyrophosphate precursor: Nickel oxide, zinc oxide and ammonium dihydrogen phosphate were mixed in a molar ratio of 0.5:1.5:2. Then the mixed powder, agate grinding balls and deionized water were mixed evenly in a mass ratio of 1:5:1 and ball-milled at a speed of 500 rpm for 2 hours. Finally, the ball-milled product was dried to obtain zinc nickel pyrophosphate precursor.

[0099] (2) Preparation of zinc nickel pyrophosphate powder: The above zinc nickel pyrophosphate precursor was precalcined at a temperature of 700℃ and a time of 2h. After the product was cooled to room temperature, it was calcined again at a temperature of 1000℃ and a time of 1h. After cooling, the calcined product was ground in the manner of step (1) to obtain zinc nickel pyrophosphate powder with an average particle size of 10μm and negative thermal expansion filler.

[0100] (3) Preparation of epoxy resin composite material: The zinc nickel pyrophosphate powder, spherical aluminum nitride and bisphenol A type epoxy resin are mixed according to the ratio, and then 2-methylimidazole is added for mixing and degassing to obtain epoxy resin composite material with low thermal expansion coefficient.

[0101] The preparation steps for cured products with low coefficients of thermal expansion are as follows:

[0102] The above-mentioned epoxy resin composite material was subjected to curing treatment, wherein the curing conditions were pre-curing at 70℃ for 2 hours and then curing at 120℃ for 5 hours to obtain a cured product with a low coefficient of thermal expansion.

[0103] Example 8

[0104] The epoxy resin composite material with a low coefficient of thermal expansion provided in this embodiment includes, by weight, 45 parts of zinc barium pyrophosphate powder (Zn). 1.6 Ba 0.4 The mixture consists of 20 parts of spherical alumina, 5 parts of near-spherical boron nitride, 27 parts of bisphenol F epoxy resin, and 3 parts of 2-phenylimidazole, wherein the average particle sizes of the zinc barium pyrophosphate powder, alumina, and boron nitride are 2 μm, 0.1 μm, and 1 μm, respectively.

[0105] The preparation steps of the above-mentioned epoxy resin composite material with low coefficient of thermal expansion are as follows:

[0106] (1) Preparation of barium zinc pyrophosphate precursor: Barium oxide, zinc oxide, metaphosphoric acid and ammonium dihydrogen phosphate were mixed in a molar ratio of 0.4:1.6:0.5:1.5. Then the mixed powder was mixed with agate grinding balls and ethanol in a mass ratio of 1:8:1. The mixture was then sand-milled at a speed of 300 rpm for 4 hours. Finally, the sand-milled product was dried to obtain the barium zinc pyrophosphate precursor.

[0107] (2) Preparation of zinc barium pyrophosphate powder: The above zinc barium pyrophosphate precursor was precalcined at a temperature of 650°C and a time of 3 hours. After the product was cooled to room temperature, it was calcined again at a temperature of 850°C and a time of 2 hours. After cooling, the calcined product was ground in the manner of step (1) to obtain zinc barium pyrophosphate powder with an average particle size of 2 μm.

[0108] (3) Preparation of epoxy resin composite material: The above-mentioned zinc barium pyrophosphate powder, spherical alumina, near-spherical boron nitride and bisphenol F type epoxy resin are mixed according to the formula, and then 2-phenylimidazolium is added for mixing and degassing to obtain epoxy resin composite material with low thermal expansion coefficient.

[0109] The preparation steps for cured products with low coefficients of thermal expansion are as follows:

[0110] The above-mentioned epoxy resin composite material was subjected to curing treatment, wherein the curing conditions were pre-curing at 70°C for 2 hours and then curing at 120°C for 5 hours to obtain a cured product with a low coefficient of thermal expansion.

[0111] Example 9

[0112] The epoxy resin composite material with low coefficient of thermal expansion provided in this embodiment includes 70 parts by weight of zinc strontium pyrophosphate powder (Zn). 1.2 Sr 0.8The mixture contains 5 parts of spherical alumina (P2O7), 9 parts of phenolic epoxy resin, 8 parts of bisphenol A epoxy resin, 7.98 parts of methylhexahydrophthalic anhydride, and 0.02 parts of 2,4-dimethylimidazole, wherein the average particle sizes of zinc strontium pyrophosphate powder and alumina are 20 μm and 30 μm, respectively.

[0113] The preparation steps of the above-mentioned epoxy resin composite material with low coefficient of thermal expansion are as follows:

[0114] (1) Preparation of zinc strontium pyrophosphate precursor: Strontium oxide, zinc oxide and diammonium hydrogen phosphate were mixed in a molar ratio of 0.8:1.2:2. Then the mixed powder, agate grinding balls and ethanol were mixed evenly in a mass ratio of 1:9:2 and sand milled at a speed of 350 rpm for 5 h. Finally, the sand milled product was dried to obtain zinc strontium pyrophosphate precursor.

[0115] (2) Preparation of zinc strontium pyrophosphate powder: The above zinc strontium pyrophosphate precursor was precalcined at a temperature of 800°C and a time of 3 hours. After the product was cooled to room temperature, it was calcined again at a temperature of 950°C and a time of 3 hours. After cooling, the calcined product was ground in the manner of step (1) to obtain zinc strontium pyrophosphate powder with an average particle size of 20 μm.

[0116] (3) Preparation of epoxy resin composite material: Zinc strontium pyrophosphate powder, spherical alumina, phenolic epoxy resin and bisphenol A type epoxy resin are mixed according to the formula, and then methyl hexahydrophthalic anhydride and 2,4-dimethylimidazole are added and mixed and degassed to obtain epoxy resin composite material with low thermal expansion coefficient.

[0117] The preparation steps for cured products with low coefficients of thermal expansion are as follows:

[0118] The above-mentioned epoxy resin composite material was subjected to curing treatment, wherein the curing conditions were pre-curing at 100℃ for 2 hours and then curing at 150℃ for 5 hours to obtain a cured product with a low coefficient of thermal expansion.

[0119] Comparative Example 1

[0120] The epoxy resin composite material provided in this comparative example comprises, by weight, 57.5 parts of bisphenol F type epoxy resin, 42.45 parts of methylhexahydrophthalic anhydride, and 0.05 parts of 2,4-dimethylimidazole.

[0121] The preparation steps of the cured product provided in this comparative example are as follows:

[0122] Bisphenol F type epoxy resin, methyl hexahydrophthalic anhydride and 2,4-dimethylimidazole were mixed and degassed according to the formula to obtain an epoxy resin composite material. The epoxy resin composite material was then cured under the following conditions: pre-curing at 100°C for 2 hours and then curing at 150°C for 5 hours to obtain a cured product.

[0123] Comparative Example 2

[0124] The epoxy resin composite material provided in this comparative example comprises, by weight, 60 parts of spherical alumina (same as in Example 1), 23 parts of bisphenol F type epoxy resin, 16.98 parts of methylhexahydrophthalic anhydride and 0.02 parts of 2,4-dimethylimidazole.

[0125] The preparation steps of the cured product provided in this comparative example are as follows:

[0126] According to the specified ratio, spherical alumina, bisphenol F epoxy resin, methyl hexahydrophthalic anhydride and 2,4-dimethylimidazole are mixed and degassed to obtain an epoxy resin composite material. Then, the epoxy resin composite material is cured under the following conditions: pre-curing at 100℃ for 2 hours, followed by curing at 150℃ for 5 hours to obtain the cured product.

[0127] Comparative Example 3

[0128] The epoxy resin composite material provided in this comparative example comprises, by weight, 60 parts zinc magnesium pyrophosphate powder (same as in Example 1), 23 parts bisphenol F type epoxy resin, 16.98 parts methyl hexahydrophthalic anhydride and 0.02 parts 2,4-dimethylimidazole.

[0129] The preparation steps of the cured product provided in this comparative example are as follows:

[0130] According to the specified ratio, zinc magnesium pyrophosphate powder, bisphenol F type epoxy resin, methyl hexahydrophthalic anhydride and 2,4-dimethylimidazole are mixed and degassed to obtain an epoxy resin composite material. Then, the epoxy resin composite material is subjected to curing treatment, wherein the curing conditions are pre-curing at 100℃ for 2 hours and then curing at 150℃ for 5 hours to obtain a cured product.

[0131] Viscosity tests were performed on the epoxy resin composites prepared in Examples 1-9 and Comparative Examples 1-3 using an AntonPaar MCR302 micrometer, with a shear rate of 10 s⁻¹. -1 The test temperature was controlled at 25℃ using a circulating constant temperature water bath system. Furthermore, the linear thermal expansion coefficient of the sample was tested using a TMA Q400EM, with a heating rate of 10℃ / min and a test temperature range of 20–200℃. The results are shown in Table 1.

[0132] Table 1 Viscosity and Coefficient of Thermal Expansion

[0133] Example 1 3.8 37.9 Example 2 8.9 39.8 Example 3 15.3 22.0 Example 4 5.7 35.3 Example 5 18.2 19.7 Example 6 8.4 33.4 Example 7 10.5 27.0 Example 8 13.0 25.6 Example 9 19.6 12.1

[0134] Experimental results show that the epoxy resin composite materials prepared in Examples 1-9 of this application all have a viscosity of less than 20 Pa·s and a coefficient of thermal expansion of less than 40 ppm·K. -1 The epoxy resin composite material prepared in this application has a wide processing window, which helps to ensure that the epoxy resin composite material has good flowability and filling properties during molding, thus enabling better encapsulation and improving the encapsulation effect.

[0135] Figure 1 This is a graph showing the relationship between the apparent viscosity and shear rate of the epoxy resin composite materials prepared in Examples 1, 2, and 3 of this application at 25°C. It can be seen that, when the total volume fraction of the epoxy resin composite materials is the same, the viscosity of Example 1 is significantly lower than that of Comparative Example 3 and slightly higher than that of Comparative Example 2, at a shear rate of 10 s⁻¹. -1 At that time, the viscosity of Example 1 decreased by 65% ​​compared with Comparative Example 3, and the processing fluidity was significantly improved.

[0136] Figure 2 The thermal conductivity and coefficient of thermal expansion of the cured products prepared in Comparative Examples 1, 2, 3, and 1 of this application are shown. It can be seen that the coefficient of thermal expansion of the cured product prepared in Example 1 is significantly lower than that of Comparative Examples 1 and 2, while its thermal conductivity is significantly higher than that of Comparative Examples 1 and 3. This application, by compounding negative thermal expansion fillers, thermally conductive fillers, epoxy resin, and curing agents, effectively improves the overall performance of the cured product through the synergistic effect between the components. This results in a product that combines a low coefficient of thermal expansion, high thermal conductivity, and good flowability, effectively improving the operational stability and extending the service life of electronic components, and has broad application prospects in the field of electronic packaging materials.

[0137] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An epoxy resin composite material with a low coefficient of thermal expansion, characterized in that, The epoxy resin composite material, by weight, consists of 5-50 parts of negative thermal expansion filler, 5-70 parts of thermally conductive filler, 12-35 parts of epoxy resin, and 0.3-18 parts of curing agent. The chemical formula of the negative thermal expansion filler is Zn. （2-x） M x P2O7, wherein M is selected from any one of Cu, Mg, Ca, Mn, Fe, Co, Ni, Ba, and Sr, and 0.2≤x≤1.5; The thermally conductive filler is composed of spherical or near-spherical particles; The epoxy resin composite material has a viscosity of less than 20 Pa·s and a coefficient of thermal expansion of less than 40 ppm·K. 1 .

2. The epoxy resin composite material as described in claim 1, characterized in that, The negative thermal expansion filler is composed of random particles with an average particle size of 0.1 μm to 30 μm.

3. The epoxy resin composite material as described in claim 1, characterized in that, The thermally conductive filler has an average particle size of 0.1 μm to 30 μm and is selected from one or more of alumina, aluminum nitride, and boron nitride.

4. The epoxy resin composite material as described in claim 1, characterized in that, The epoxy resin is one or more of bisphenol A type epoxy resin, bisphenol S type epoxy resin, bisphenol F type epoxy resin, phenolic epoxy resin and liquid crystal epoxy resin.

5. The epoxy resin composite material as described in claim 1, characterized in that, The curing agent is one or more of 2-methylimidazole, 2,4-dimethylimidazole, 2-ethylimidazole, 2-phenylimidazole, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, triethylenetetramine, and isophorone diamine.

6. The application of the epoxy resin composite material as described in any one of claims 1 to 5 in the encapsulation of electronic components.

7. A cured product, characterized in that, The cured product includes the epoxy resin composite material as described in any one of claims 1 to 5.

8. An encapsulated device, characterized in that, The encapsulation device includes the cured material as described in claim 7.

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