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

Abstract

The invention belongs to the technical field of electronic packaging materials, and particularly relates to an epoxy resin composite material with a low thermal expansion coefficient, a cured product and application. The epoxy resin composite material with low thermal expansion coefficient, high thermal conductivity and good flowability is prepared by compounding the negative thermal expansion filler, the thermal conductive filler, the epoxy resin and the curing agent through the synergistic effect of the components, so that the epoxy resin composite material has good flowability and filling property during plastic packaging; the packaging operation can be better carried out, the packaging effect is improved, the working stability of electronic components is effectively improved, the working life is prolonged, and the packaging material has wide application prospects in the field of electronic packaging materials.

Description

Technical Field

[0001] The present application belongs to the technical field of electronic packaging materials, and more specifically, relates to an epoxy resin composite material with a low thermal expansion coefficient, a cured product, and applications. Background Art

[0002] Integrated circuits are an important pillar of the contemporary information industry and are widely used in communications, computers, aerospace and other fields. Flip-chip packaging is currently the main form of chip-level electronic packaging, and generally uses an Underfill packaging process. Ideal Underfill electronic packaging materials should have the following characteristics: (1) Appropriate thermal expansion coefficient to ensure that the thermal stress on the solder joints under high and low temperature cycles can be effectively dispersed to prevent solder joint cracking; (2) Excellent thermal conductivity to ensure that the heat generated during chip operation can be transferred out in a timely manner; (3) Good flowability to ensure that the packaging material can fully fill the gap between the chip and the substrate.

[0003] At present, most integrated circuits are packaged in plastic, of which epoxy resin accounts for 90% of the plastic packaging share due to its excellent chemical and corrosion resistance, electrical insulation, mechanical strength, bonding strength and low curing shrinkage. However, the high thermal expansion coefficient of epoxy resin causes it to not match the thermal expansion coefficient between the chip and the silicon substrate. When the temperature of the surrounding environment rises or falls, the size of the epoxy resin expands or contracts significantly. The resulting thermal stress causes solder joints to fall off and components to fail. In addition, the thermal conductivity of epoxy resin is low, and it is unable to transfer the heat generated by the chip during operation in time, resulting in heat accumulation in the electronic packaging system, which leads to reduced chip performance and shortened life.

[0004] Inorganic fillers such as silicon dioxide, aluminum oxide, boron nitride, aluminum nitride, and silicon carbide have the characteristics of low thermal expansion coefficient and high thermal conductivity. Epoxy resin is usually compounded with these inorganic fillers to reduce the thermal expansion coefficient of the material and increase the thermal conductivity. However, the fillers used in existing modification methods are mostly inorganic fillers with positive thermal expansion characteristics, and a high filling amount (>50vol%) is often required to reduce the thermal expansion coefficient of the composite system to a reasonable range. The high filling amount of inorganic fillers leads to excessive viscosity of the composite system and poor processing fluidity. The design and preparation of high-performance epoxy resin composite materials with low thermal expansion coefficient, high thermal conductivity, and low processing viscosity are faced with challenges. Summary of the invention

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

[0006] To achieve the above objectives, the present application provides an epoxy resin composite material with a low thermal expansion coefficient. Calculated by weight, the epoxy resin composite material includes 5 to 50 parts of negative thermal expansion filler, 5 to 70 parts of thermal 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 negative thermal expansion filler is Zn (2-x) M x P2O7, wherein 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 a random particle with an average particle size of 0.1 μm to 30 μm.

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

[0011] Preferably, the epoxy resin is one or more of bisphenol A epoxy resin, bisphenol S epoxy resin, bisphenol F epoxy resin, novolac 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 isophoronediamine.

[0013] The present application provides the use of the above epoxy resin composite material in encapsulation of electronic components.

[0014] Preferably, the electronic components are one or more of chips, transistors, LEDs and resistors, capacitors and inductors.

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

[0016] The present application also provides an encapsulated device, which includes the above-mentioned solidified material.

[0017] In general, the above technical solutions conceived by this application have the following technical advantages compared with the prior art:

[0018] (1) The present application improves the comprehensive performance of the epoxy resin composite material by compounding negative thermal expansion filler, thermal conductive filler, epoxy resin and curing agent through the synergistic effect between the components, so that it has low thermal expansion coefficient, high thermal conductivity and low processing viscosity. The above epoxy resin composite material has a wide process operation window, which is conducive to ensuring that it has good fluidity and filling properties during plastic sealing, better packaging operation, improved packaging effect, and thus effectively improves the working stability of electronic components and prolongs the working life, and has broad application prospects in the field of electronic packaging materials.

[0019] (2) In the preferred embodiment, the present application selects spherical or nearly spherical thermal conductive fillers to cooperate with other components, while improving the thermal conductivity of the epoxy resin composite material, and cooperates with the negative thermal expansion filler to effectively reduce the friction between the fillers, significantly improving the processing fluidity of the system and reducing the processing difficulty. In addition, the spherical or nearly spherical thermal conductive filler can also cooperate with the negative thermal expansion filler to effectively reduce the thermal expansion coefficient of the system, and can significantly reduce the thermal expansion coefficient of the system under the condition of a lower filling amount of the negative thermal expansion filler, while effectively avoiding the problem of high processing viscosity caused by high filling amount. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0021] Figure 2 These are the properties of thermal conductivity and thermal expansion coefficient of the cured products prepared in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present application. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0023] The present application provides an epoxy resin composite material with a low thermal expansion coefficient. Calculated by weight, the epoxy resin composite material includes 5 to 50 parts of negative thermal expansion filler, 5 to 70 parts of thermal 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 negative thermal expansion filler is Zn (2-x) M x P2O7, wherein 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 a random particle with an average particle size of 0.1 μm to 30 μm.

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

[0028] In some embodiments, the epoxy resin is one or more of bisphenol A epoxy resin, bisphenol S epoxy resin, bisphenol F epoxy resin, novolac 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 isophoronediamine.

[0030] In some embodiments, the epoxy resin composite material provided by the present application can be prepared by stirring and mixing the components. It is understood that the present application does not limit the above stirring and mixing method, as long as the components can be mixed uniformly, it is within the protection scope of the present application.

[0031] The epoxy resin composite material provided in the present application will solidify when heated, and the epoxy resin can react chemically with the curing agent to form a three-dimensional network polymer. The above-mentioned epoxy resin composite material is transformed into a solidified product of a certain shape after solidification, and the solidified product can be a film, a sheet or a three-dimensional structure. In the present application, the above-mentioned epoxy resin composite material is usually liquid and can be directly used as a liquid glue, and a glue layer is formed after coating, filling and curing. In addition, the epoxy resin composite material can also be transformed into a solid molding material (the epoxy resin is not completely cross-linked and cured) that is easy to preserve after mixing, aging and other treatments. The molding material can be granular, flaky or lumpy, etc., and can be subsequently converted into a solidified product with a certain shape through a common molding process.

[0032] The present application provides the application of the above-mentioned epoxy resin composite material in the encapsulation of electronic components. For example, it is applied to electronic components as an encapsulation material. In some embodiments, the above-mentioned epoxy resin composite material is used to form a plastic package covering the electronic components to fix and protect the electronic components. The above-mentioned electronic components can be but are not limited to chips, transistors (such as diodes, triodes), LEDs, and RC components (such as resistors, capacitors, inductors).

[0033] The present application provides a cured product, which includes the epoxy resin composite material. It is understandable that the cured product can be cured into various shapes according to actual needs, such as but not limited to thin films, sheets, and three-dimensional structures, and covered on the surface of electronic components to be packaged to form a plastic package to protect various electronic components.

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

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

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

[0037] The transition metal element oxide, zinc oxide and phosphoric acid compound are mixed according to the atomic ratio, and then the mixed powder is ground and dried to obtain a negative thermal expansion filler precursor, and then the negative thermal expansion filler precursor is calcined at least twice, and then ground after cooling to obtain a negative thermal expansion filler.

[0038] In some embodiments, the transition metal element 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 phosphorus oxyacid compound is one or more of diammonium phosphate, diammonium hydrogen phosphate, phosphoric acid, metaphosphoric acid and pyrophosphoric acid.

[0040] In some embodiments, the grinding is ball milling or sand milling, and the specific operation is: grinding the mixed powder, grinding media and grinding aid. In some embodiments, the grinding media is grinding balls, and the grinding aid is one or more of ethanol, isopropanol, acetone and deionized water.

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

[0042] In some embodiments, the calcination is specifically as follows: pre-calcining the negative thermal expansion filler precursor at a temperature of 600°C to 800°C for a time of 1h to 4h; then performing a second calcination at a temperature of 800°C to 1000°C for a time of 1h to 4h.

[0043] In some embodiments, the curing conditions are pre-curing at 60° C. to 100° C. for 1 h to 3 h, and then curing at 120° C. to 180° C. for 3 h to 8 h.

[0044] The present application also provides an encapsulated device, which includes the above-mentioned solidified material.

[0045] It should be understood that materials with the same or similar types, models, qualities, properties or functions as the reagents and instruments in the following examples can be used to implement the present application. The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples can be obtained from commercial sources unless otherwise specified.

[0046] The following are examples and comparative examples:

[0047] Example 1

[0048] The epoxy resin composite material with low thermal expansion coefficient provided in this embodiment comprises, by weight, 31 parts of zinc magnesium pyrophosphate powder (Zn 1.6 Mg 0.4 P2O7), 29 parts of spherical alumina, 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 2μm and 5μm respectively.

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

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

[0051] (2) Preparation of zinc magnesium pyrophosphate powder: The zinc magnesium pyrophosphate precursor is pre-calcined at a calcination temperature of 800° C. and a calcination time of 2 h, respectively. After the product is cooled to room temperature, it is secondary calcined at a calcination temperature of 900° C. and a calcination time of 2 h, respectively. After cooling, the calcined product is ground according to the method of step (1) to obtain a negative thermal expansion filler zinc magnesium pyrophosphate powder with an average particle size of 2 μm.

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

[0053] The steps for preparing the low thermal expansion coefficient cured product are as follows:

[0054] The epoxy resin composite material is subjected to a curing treatment, wherein the curing conditions are pre-curing at 100° C. for 2 hours and then curing at 150° C. for 5 hours, to obtain a cured product with a low thermal expansion coefficient.

[0055] Example 2

[0056] The epoxy resin composite material with low thermal expansion coefficient provided in this embodiment includes 5 parts by weight of zinc copper pyrophosphate powder (Zn 1.8 Cu 0.2 P2O7), 30 parts of spherical alumina, 30 parts of spherical aluminum nitride, 34.7 parts of bisphenol A 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 30μm, 10μm and 20μm respectively.

[0057] The preparation steps of the above-mentioned epoxy resin composite material with low thermal expansion coefficient 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, and then the mixed powder was evenly mixed with agate grinding balls and isopropanol in a mass ratio of 1:5:2, and sand-milled at a speed of 200 rpm for 3 h. Finally, the sand-milled product was dried to obtain a zinc copper pyrophosphate precursor.

[0059] (2) Preparation of zinc copper pyrophosphate powder: The zinc copper pyrophosphate precursor was pre-calcined at a temperature of 600° C. and a calcination time of 1 h, respectively. After the product was cooled to room temperature, it was secondary calcined at a temperature of 800° C. and a calcination time of 3 h, respectively. After cooling, the calcined product was ground according to the method of step (1) to obtain a negative thermal expansion filler zinc copper pyrophosphate powder with an average particle size of 30 μm.

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

[0061] The steps for preparing the low thermal expansion coefficient cured product are as follows:

[0062] The epoxy resin composite material is subjected to a curing treatment, wherein the curing conditions are pre-curing at 60° C. for 2 hours and then curing at 150° C. for 8 hours, to obtain a cured product with a low thermal expansion coefficient.

[0063] Example 3

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

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

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

[0067] (2) Preparation of calcium zinc pyrophosphate powder: The calcium zinc pyrophosphate precursor is pre-calcined at a calcination temperature of 700° C. and a calcination time of 3 h, respectively. After the product is cooled to room temperature, it is secondary calcined at a calcination temperature of 1000° C. and a calcination time of 1 h, respectively. After cooling, the calcined product is ground according to the method of step (1) to obtain a negative thermal expansion filler calcium zinc pyrophosphate powder with an average particle size of 0.1 μm.

[0068] (3) Preparation of epoxy resin composite material: The above-mentioned calcium zinc pyrophosphate powder, nearly 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 an epoxy resin composite material with a low thermal expansion coefficient.

[0069] The steps for preparing the low thermal expansion coefficient cured product are as follows:

[0070] The epoxy resin composite material is subjected to a curing treatment, wherein the curing conditions are pre-curing at 60° C. for 3 hours and then curing at 120° C. for 5 hours, to obtain a cured product with a low thermal expansion coefficient.

[0071] Example 4

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

[0073] The method for preparing the above-mentioned epoxy resin composite material with low thermal expansion coefficient comprises 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, and then the mixed powder was uniformly mixed with agate grinding balls and acetone in a mass ratio of 1:8:1, and then sand-milled at a speed of 300 rpm for 4 h. Finally, the sand-milled product was dried to obtain a zinc manganese pyrophosphate precursor.

[0075] (2) Preparation of zinc manganese pyrophosphate powder: The zinc manganese pyrophosphate precursor was pre-calcined at a calcination temperature of 750° C. and a calcination time of 2 h, respectively. After the product was cooled to room temperature, it was secondary calcined at a calcination temperature of 850° C. and a calcination time of 2 h, respectively. After cooling, the calcined product was ground according to the method of step (1) to obtain a negative thermal expansion filler zinc manganese pyrophosphate powder with an average particle size of 10 μm.

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

[0077] The steps for preparing the low thermal expansion coefficient cured product are as follows:

[0078] The epoxy resin composite material is subjected to a curing treatment, wherein the curing conditions are pre-curing at 100° C. for 1 hour and then curing at 180° C. for 5 hours, to obtain a cured product with a low thermal expansion coefficient.

[0079] Example 5

[0080] The epoxy resin composite material with low thermal expansion coefficient provided in this embodiment comprises 50 parts by weight of zinc iron pyrophosphate powder (Zn 1.4 Fe 0.6 P2O7), 20 parts of spherical alumina, 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 10μm and 15μm respectively.

[0081] The preparation steps of the above-mentioned epoxy resin composite material with low thermal expansion coefficient 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, and then the mixed powder was evenly 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 a zinc iron pyrophosphate precursor.

[0083] (2) Preparation of zinc iron pyrophosphate powder: The zinc iron pyrophosphate precursor is pre-calcined at a temperature of 800° C. and a calcination time of 1 h, respectively. After the product is cooled to room temperature, it is secondary calcined at a temperature of 900° C. and a calcination time of 4 h, respectively. After cooling, the calcined product is ground according to the method of step (1) to obtain a negative thermal expansion filler zinc iron pyrophosphate powder with an average particle size of 10 μm.

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

[0085] The steps for preparing the low thermal expansion coefficient cured product are as follows:

[0086] The epoxy resin composite material is subjected to a curing treatment, wherein the curing conditions are pre-curing at 80° C. for 2 hours and then curing at 120° C. for 6 hours, to obtain a cured product with a low thermal expansion coefficient.

[0087] Example 6

[0088] The epoxy resin composite material with low thermal expansion coefficient provided in this embodiment comprises, by weight, 5 parts of zinc cobalt pyrophosphate powder (Zn 0.5 Co 1.5 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 5μm and 1μm respectively.

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

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

[0091] (2) Preparation of zinc cobalt pyrophosphate powder: The zinc cobalt pyrophosphate precursor was pre-calcined at a calcination temperature of 600° C. and a calcination time of 4 h, respectively. After the product was cooled to room temperature, it was secondary calcined at a calcination temperature of 950° C. and a calcination time of 1 h, respectively. After cooling, the calcined product was ground according to the method of step (1) to obtain a negative thermal expansion filler zinc cobalt pyrophosphate powder with an average particle size of 5 μm.

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

[0093] The steps for preparing the low thermal expansion coefficient cured product are as follows:

[0094] The epoxy resin composite material is subjected to a curing treatment, wherein the curing conditions are pre-curing at 60° C. for 2 hours and then curing at 170° C. for 3 hours, to obtain a cured product with a low thermal expansion coefficient.

[0095] Example 7

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

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

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

[0099] (2) Preparation of nickel zinc pyrophosphate powder: The nickel zinc pyrophosphate precursor is pre-calcined at a calcination temperature of 700° C. and a calcination time of 2 h, respectively. After the product is cooled to room temperature, it is secondary calcined at a calcination temperature of 1000° C. and a calcination time of 1 h, respectively. After cooling, the calcined product is ground according to the method of step (1) to obtain a nickel zinc pyrophosphate powder having an average particle size of 10 μm as a negative thermal expansion filler.

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

[0101] The steps for preparing the low thermal expansion coefficient cured product are as follows:

[0102] The epoxy resin composite material is subjected to a curing treatment, wherein the curing conditions are 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 thermal expansion coefficient.

[0103] Example 8

[0104] The epoxy resin composite material with low thermal expansion coefficient provided in this embodiment comprises 45 parts by weight of barium zinc pyrophosphate powder (Zn 1.6 Ba 0.4 P2O7), 20 parts of spherical alumina, 5 parts of nearly spherical boron nitride, 27 parts of bisphenol F epoxy resin and 3 parts of 2-phenylimidazole, wherein the average particle sizes of barium zinc pyrophosphate powder, alumina and boron nitride are 2μm, 0.1μm and 1μm respectively.

[0105] The preparation steps of the above-mentioned epoxy resin composite material with low thermal expansion coefficient 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, and then the mixed powder was mixed with agate grinding balls and ethanol in a mass ratio of 1:8:1, and sand-milled at a speed of 300 rpm for 4 h. Finally, the sand-milled product was dried to obtain a barium zinc pyrophosphate precursor.

[0107] (2) Preparation of barium zinc pyrophosphate powder: The barium zinc pyrophosphate precursor was pre-calcined at a temperature of 650° C. and a calcination time of 3 h, respectively. After the product was cooled to room temperature, it was secondary calcined at a temperature of 850° C. and a calcination time of 2 h, respectively. After cooling, the calcined product was ground according to the method of step (1) to obtain a negative thermal expansion filler barium zinc pyrophosphate powder with an average particle size of 2 μm.

[0108] (3) Preparation of epoxy resin composite material: The above-mentioned barium zinc pyrophosphate powder, spherical alumina, nearly spherical boron nitride and bisphenol F epoxy resin are mixed according to the ratio, and then 2-phenylimidazole is added, mixed and degassed to obtain an epoxy resin composite material with a low thermal expansion coefficient.

[0109] The steps for preparing the low thermal expansion coefficient cured product are as follows:

[0110] The epoxy resin composite material is subjected to a curing treatment, wherein the curing conditions are 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 thermal expansion coefficient.

[0111] Example 9

[0112] The epoxy resin composite material with low thermal expansion coefficient provided in this embodiment comprises 70 parts by weight of strontium zinc pyrophosphate powder (Zn 1.2 Sr 0.8P2O7), 5 parts of spherical alumina, 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 strontium zinc pyrophosphate powder and alumina are 20μm and 30μm respectively.

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

[0114] (1) Preparation of strontium zinc pyrophosphate precursor: Strontium oxide, zinc oxide and diammonium hydrogen phosphate were mixed at a molar ratio of 0.8:1.2:2, and then the mixed powder was evenly mixed with agate grinding balls and ethanol at 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 a strontium zinc pyrophosphate precursor.

[0115] (2) Preparation of strontium zinc pyrophosphate powder: The above-mentioned strontium zinc pyrophosphate precursor was pre-calcined at a calcination temperature and a calcination time of 800°C and 3 h, respectively. After the product was cooled to room temperature, it was secondary calcined at a calcination temperature and a calcination time of 950°C and 3 h, respectively. After cooling, the calcined product was ground according to the method of step (1) to obtain a negative thermal expansion filler strontium zinc pyrophosphate powder with an average particle size of 20 μm.

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

[0117] The steps for preparing the low thermal expansion coefficient cured product are as follows:

[0118] The epoxy resin composite material is subjected to a curing treatment, wherein the curing conditions are pre-curing at 100° C. for 2 hours and then curing at 150° C. for 5 hours, to obtain a cured product with a low thermal expansion coefficient.

[0119] Comparative Example 1

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

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

[0122] Bisphenol F epoxy resin, methyl hexahydrophthalic anhydride and 2,4-dimethylimidazole are mixed and degassed according to a ratio to obtain an epoxy resin composite material, and then the epoxy resin composite material is cured, wherein the curing conditions are 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 includes, by weight, 60 parts of spherical alumina (same as in Example 1), 23 parts of bisphenol F epoxy resin, 16.98 parts of methylhexahydrophthalic anhydride and 0.02 parts of 2,4-dimethylimidazole.

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

[0126] Spherical alumina, bisphenol F epoxy resin, methyl hexahydrophthalic anhydride and 2,4-dimethylimidazole are mixed and degassed according to a ratio to obtain an epoxy resin composite material, and then the epoxy resin composite material is cured, wherein the curing conditions are pre-curing at 100° C. for 2 hours and then curing at 150° C. for 5 hours to obtain a cured product.

[0127] Comparative Example 3

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

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

[0130] Magnesium zinc pyrophosphate powder, bisphenol F epoxy resin, methyl hexahydrophthalic anhydride and 2,4-dimethylimidazole are mixed and degassed according to a ratio to obtain an epoxy resin composite material, and then the epoxy resin composite material is cured, wherein the curing conditions are pre-curing at 100° C. for 2 hours and then curing at 150° C. for 5 hours to obtain a cured product.

[0131] The viscosity of the epoxy resin composite materials prepared in Examples 1 to 9 and Comparative Examples 1 to 3 was tested using AntonPaar MCR302 at a shear rate of 10 s -1 The test temperature was controlled at 25°C by a circulating constant temperature water bath system. Further, the linear thermal expansion coefficient of the sample was tested by TMA Q400EM, the heating rate was 10°C / min, and the test temperature range was 20-200°C. The results are shown in Table 1.

[0132] Table 1 Viscosity and thermal expansion coefficient

[0133] Viscosity (Pa·s) <![CDATA[Coefficient of thermal expansion (ppm·K -1 )]]> 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] The experimental results show that the viscosity of the epoxy resin composite materials prepared in Examples 1 to 9 of the present application is less than 20 Pa·s, and the thermal expansion coefficient is less than 40 ppm·K -1 The epoxy resin composite material prepared in the present application has a wide process operation window, which is conducive to ensuring that the epoxy resin composite material has good fluidity and filling properties during plastic packaging, better performing packaging operations, and improving packaging effects.

[0135] Figure 1 1 is a graph showing the relationship between the apparent viscosity and shear rate of the epoxy resin composite materials prepared in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present 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 smaller than that of Comparative Example 3 and slightly higher than that of Comparative Example 2. -1 When the viscosity of Example 1 is 65% lower than that of Comparative Example 3, the processing fluidity is significantly improved.

[0136] Figure 2 The thermal conductivity and thermal expansion coefficient performance of the cured products prepared by Comparative Examples 1, 2, 3 and Example 1 of the present application are shown. It can be seen that the thermal expansion coefficient of the cured product prepared by Example 1 is significantly lower than that of Comparative Examples 1 and 2, and the thermal conductivity is significantly higher than that of Comparative Examples 1 and 3. The present application can effectively improve the comprehensive performance of the cured product through the synergistic effect between the components by compounding the negative thermal expansion filler, the thermal conductive filler, the epoxy resin and the curing agent, so that the cured product has low thermal expansion coefficient, high thermal conductivity and good fluidity, can effectively improve the working stability of electronic components and extend the working life, and has broad application prospects in the field of electronic packaging materials.

[0137] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. An epoxy resin composite material with a low thermal expansion coefficient, characterized in that: Calculated by weight, the epoxy resin composite material includes 5 to 50 parts of negative thermal expansion filler, 5 to 70 parts of thermal conductive filler, 12 to 35 parts of epoxy resin, and 0.3 to 18 parts of curing agent.

2. The epoxy resin composite material according to claim 1, characterized in that: The chemical formula of the negative thermal expansion filler is Zn (2-x) M x P2O7, wherein M is a transition metal element and 0<x<2.

3. The epoxy resin composite material according to claim 2, characterized in that: The M element is selected from any one of Cu, Mg, Ca, Mn, Fe, Co, Ni, Ba, and Sr.

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

5. The epoxy resin composite material according to claim 1, characterized in that: The thermal conductive filler is spherical or nearly spherical particles with an average particle size of 0.1 μm to 30 μm, and is selected from one or more of aluminum oxide, aluminum nitride and boron nitride.

6. The epoxy resin composite material according to claim 1, characterized in that: The epoxy resin is one or more of bisphenol A epoxy resin, bisphenol S epoxy resin, bisphenol F epoxy resin, novolac epoxy resin and liquid crystal epoxy resin.

7. The epoxy resin composite material according to 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 isophoronediamine.

8. Use of the epoxy resin composite material according to any one of claims 1 to 7 in encapsulation of electronic components.

9. A solidified product, characterized in that: The cured product comprises the epoxy resin composite material according to any one of claims 1 to 7.

10. A packaged device, characterized in that: The encapsulated device comprises the cured object as claimed in claim 9.

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