Resin for electronic component packaging and method for producing the same

Abstract

The present application relates to a kind of electronic component encapsulation resin and its preparation method, belong to polymer material technical field, resin raw material includes epoxy resin, organic silicon prepolymer, polyamide acid solution, modified core-shell structure filler, polydimethylsiloxane alcohol-methyl silanol-silicate crosslinking polymer and silane coupling agent etc. Component.The resin matrix of the present application adopts organic silicon-epoxy-polyimide-crosslinking polymer quaternary interpenetrating network, functional filler adopts the special modified core-shell heterostructure functional filler, realizes performance breakthrough by new composite system and step controllable process, with good filling, thermal conductivity, stability, can realize the good encapsulation of electronic component, long service life.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer materials, and particularly relates to a resin for electronic component packaging and a preparation method thereof. BACKGROUND

[0002] With the rapid development of electronic information technology, electronic devices are moving towards miniaturization, lightweight, high performance and multi-function. In this development process, electronic component packaging technology as a key link to ensure the stable operation of electronic devices, its importance is increasingly prominent, and the resin for electronic component packaging is the core material of packaging technology, playing an irreplaceable role.

[0003] Under the trend of miniaturization of electronic devices, the integration of electronic components is continuously improved, and the size is continuously reduced. This requires packaging materials to adapt to smaller spaces and have good filling performance to ensure effective protection of small components. For example, the size of chips in smartphones is getting smaller and smaller, and the internal structure is becoming more complex. The resin for electronic component packaging needs to be accurately filled into each tiny gap to avoid voids or bubbles, thereby providing reliable physical protection for components such as chips and preventing them from being eroded by the external environment.

[0004] The high performance of electronic devices also puts strict requirements on the resin for packaging. Electronic components will generate a large amount of heat during high-speed operation, which will seriously affect the performance and life of the components if not effectively dissipated in time. Therefore, the resin for packaging needs to have excellent thermal conductivity to quickly conduct heat away and achieve good heat dissipation effect. At the same time, with the continuous improvement of electronic signal transmission speed, the resin for packaging also needs to have low dielectric constant and low dielectric loss to reduce the delay and attenuation in the signal transmission process and ensure stable signal transmission.

[0005] In addition, electronic devices may face high temperature, high humidity, chemical corrosion and other harsh conditions in different working environments. This requires the resin for electronic component packaging to have excellent chemical stability, corrosion resistance and weather resistance. In high temperature environment, the resin will not decompose, deform or deteriorate in performance; in high humidity environment, it can effectively block the intrusion of water to prevent the components from being damaged by moisture; when facing chemical erosion, it can still maintain the stability of structure and performance to ensure the long-term reliable operation of electronic components in complex environments.

[0006] At present, although various types of electronic component packaging resins such as epoxy resin, silicone resin, phenolic resin, etc. have been widely used, and they play an important role in their respective fields, with the continuous innovation of electronic technology, the performance requirements of the packaging resin are also increasing. The comprehensive performance gradually cannot meet the higher use requirements, and new type of packaging resin with better comprehensive performance and adapting to the development trend of precision electronics needs to be developed. SUMMARY

[0007] In order to further improve the filling property, thermal conductivity, stability and other comprehensive performance of the electronic component packaging resin, and adapt to the precision electronic packaging application, the present application provides an electronic component packaging resin and a preparation method thereof. The resin matrix adopts a quaternary interpenetrating network of silicone-epoxy-polyimide-crosslinked polymer, and the functional filler adopts a specially modified core-shell heterogeneous structure functional filler. The performance breakthrough is realized through a new type of composite system and a step-by-step controllable process, and the resin has good filling property, thermal conductivity and stability, can realize good packaging of electronic components, and has long service life. The specific technical scheme is as follows:

[0008] An electronic component packaging resin, the resin comprises the following raw materials in mass fraction: 40-50 parts of epoxy resin, 20-30 parts of silicone prepolymer, 10-20 parts of polyamide acid solution, 15-20 parts of modified core-shell structure filler, 1-2 parts of polydimethylsiloxane alcohol-methylsilanol-silicate crosslinked polymer and 1.5-3 parts of silane coupling agent.

[0009] In the above raw materials, the silicone prepolymer is the A component main agent part of Sylgard 184; the silicone prepolymer is a silicone prepolymer containing vinyl and Si-OH, the vinyl content is 5wt%-8wt%, and the Si-OH content is 3wt%-5wt%.

[0010] In the above raw materials, the epoxy resin is a hydrogenated epoxy resin of bisphenol F type.

[0011] In the above raw materials, the solid content of the polyamide acid solution is 20%-30%, and the solvent is N-methyl pyrrolidone.

[0012] In the above raw materials, the silane coupling agent is silane coupling agent KH-792.

[0013] In the above raw materials, the surface of the core-shell structure filler is modified by γ-aminopropyl triethoxysilane and perfluorooctyl triethoxysilane to obtain; the inner core of the core-shell structure filler is silver nanowire; and the outer shell of the core-shell structure filler is boron nitride.

[0014] In the modified core-shell structure filler, the surface of the silver nanowire is coated with two layers of boron nitride by chemical vapor deposition, each layer of boron nitride has a thickness of 3-5 nm, to obtain a core-shell structure filler; the process parameters of the chemical vapor deposition method are as follows: the reaction temperature is 1000-1100°C, the reaction gas is diborane and ammonia, the volume ratio of diborane to ammonia is 1:(1.5-3), and the pressure is 5-10 Pa.

[0015] In the modified core-shell structure filler, the surface modification method of the modified core-shell structure filler includes the following steps:

[0016] N1: Mix γ-aminopropyltriethoxysilane, anhydrous ethanol and deionized water in a volume ratio of (1-1.5):(5-6):(1-2), adjust the pH value to 4-5 with hydrochloric acid, stir at room temperature, hydrolyze the γ-aminopropyltriethoxysilane, and form a hydrolysis product containing silanol groups Si-OH, which is material A;

[0017] N2: Mix perfluorooctyltriethoxysilane, anhydrous ethanol and deionized water in a volume ratio of (1-1.5):(8-10):(1-2), adjust the pH value to 4-5 with hydrochloric acid, stir at room temperature, and complete the hydrolysis of perfluorooctyltriethoxysilane to obtain material B;

[0018] N3: Mix the core-shell structure filler with material A in a mass ratio of (1-3):(15-20), ultrasonic dispersion until uniform, then stir and react in a water bath at 60-70°C, so that the γ-aminopropyltriethoxysilane hydrolysis product and the hydroxyl groups on the surface of the boron nitride undergo condensation reaction to realize the grafting of γ-aminopropyltriethoxysilane on the surface of the core-shell structure filler; centrifuge and separate the upper liquid to obtain solid product A, wash it with anhydrous ethanol for 3-5 times to remove unreacted γ-aminopropyltriethoxysilane and impurities; then redisperse the solid product A in anhydrous ethanol in a mass ratio of (1-1.5):(8-10), ultrasonic dispersion until uniform; then add material B in a mass ratio of (1-1.5):(10-20), stir and react in a water bath at 60-65°C, so that the perfluorooctyltriethoxysilane hydrolysis product and the filler surface with grafted γ-aminopropyltriethoxysilane undergo further condensation reaction; centrifuge and separate the upper liquid to obtain solid product B, wash it with anhydrous ethanol and deionized water alternately for a total of 4-6 times to completely remove unreacted perfluorooctyltriethoxysilane and other impurities, then vacuum dry the solid product B to constant weight to obtain the modified core-shell structure filler.

[0019] In the surface modification method N1 of the modified core-shell structure filler, the stirring speed is 200 r / min to 400 r / min, and the stirring time is 2 h to 3 h.

[0020] In the surface modification method N2 of the modified core-shell structure filler, the stirring speed is 200 r / min to 400 r / min, and the stirring time is 3 h to 4 h.

[0021] In the surface modification method N3 of the modified core-shell structure filler, the ultrasonic dispersion frequency is 40 kHz to 50 kHz, the ultrasonic dispersion time is 15 min to 20 min, the stirring speed is 300 r / min to 400 r / min, the stirring time is 3 h to 5 h, the centrifugal speed is 8000 r / min to 10000 r / min, the centrifugal time is 10 min to 20 min, the vacuum drying temperature is 50℃ to 60℃, and the vacuum drying time is 12 h to 24 h.

[0022] The preparation method of the resin for electronic component packaging comprises the following steps:

[0023] S1, resin matrix prepolymerization:

[0024] Under nitrogen protection, the silicone prepolymer, the polydimethylsiloxane alcohol-methylsilanol-silicate crosslinking polymer, and the epoxy resin are added into a reaction kettle according to the mass fraction, then the tetrabutyl titanate catalyst is added, and stirring reaction is carried out at 120℃ to 125℃ for 2 h to 3 h to form a semi-interpenetrating network structure; after the reaction is completed, the system is cooled to 50℃ to 60℃, the polyamide acid solution is added, and ultrasonic dispersion is carried out until uniformity to obtain a resin matrix prepolymer;

[0025] S2, filler directional assembly:

[0026] The modified core-shell structure filler and the silane coupling agent are added into ethanol according to the mass fraction, ball milling is carried out to obtain a ball milling material; the ball milling material is transferred into an electric field induction device, an electric field strength of 500 V / cm to 550 V / cm is applied, the induction time is 30 min to 40 min, the axial directional arrangement of the silver nanowire is realized, and freeze-drying is carried out to obtain a loose and accumulated directional filler composite;

[0027] S3, step-by-step composite curing and packaging:

[0028] S3.1: The directional filler composite is added into the resin matrix prepolymer, shear mixing is carried out to obtain a mixture, at this time, the viscosity of the mixture is less than 800 cP, and the product before electronic component packaging is obtained.

[0029] S3.2: Pour the mixture into the encapsulation mold until 1 / 2-2 / 3 height of the mold, place the electronic component, continue to pour the mixture until covering the electronic component, discharge the air bubbles, and perform programmed temperature curing, first curing at 80-90 DEG C for 2-3 hours, then heating to 180-190 DEG C, curing for 3-4 hours, finally heating to 210-220 DEG C, curing for 1-1.5 hours, cooling to room temperature, completing the encapsulation of the electronic component, and obtaining the resin after encapsulation molding.

[0030] In S1 of the above preparation method, the amount of the tetrabutyl titanate catalyst is 0.4-0.6 wt% of the total mass of the organosilicon prepolymer and the epoxy resin, the flow rate of the nitrogen is 4-5 L / min, the stirring speed is 200-250 r / min, the ultrasonic power is 200-250 W, and the ultrasonic time is 30-50 min.

[0031] In S2 of the above preparation method, the amount of the ethanol is 2-3 times of the total mass of the modified core-shell structure filler and the silane coupling agent, the ball milling speed is 200-300 r / min, the ball milling time is 2-2.5 h, and the ball milling ball-to-material mass ratio is (5-8):(1-1.5).

[0032] In S3.1 of the above preparation method, the parameters of the shear mixing are as follows: temperature 50-55 DEG C, vacuum degree 3-10 Pa, shear rate 1000-1200 s -1 -1200 s -1 , and time 30-40 min.

[0033] In S3.2 of the above preparation method, the temperature is raised to 180-190 DEG C at a rate of 3-5 DEG C / min, and raised to 210-220 DEG C at a rate of 2-3 DEG C / min, the temperature is lowered in a stepwise manner to eliminate internal stress, the temperature is lowered at a rate of 20-30 DEG C / step, each temperature stage is maintained for 30-40 min, and the temperature is lowered to room temperature.

[0034] The resin for electronic component encapsulation and the preparation method thereof have the following beneficial effects:

[0035] I. The molecular chain of the silicone prepolymer has certain flexibility and cohesion. After cross-linking with other components to form a network structure, it can effectively disperse stress and avoid stress concentration leading to rapid material rupture, thereby improving tensile strength. Silicone itself has certain heat conduction capacity, and the chemical bonds formed between silicon atoms and surrounding atoms can transfer heat and participate in the heat conduction process in the entire system. It has good insulation, which helps to improve the volume resistivity of the material. The vinyl and Si-OH groups can cross-link with other substances containing active groups to form chemical bonds at the interface and enhance the adhesion to other materials. The molecular chain of silicone has good flexibility, which can adjust its structure to adapt to thermal expansion and cold shrinkage when the temperature changes, reducing the accumulation of internal stress and improving thermal cycle stability. The silicon-oxygen bond of silicone has a certain repulsion to water molecules, and it is chemically stable and not easily eroded by water, improving the moisture resistance of the material.

[0036] II. The epoxy resin forms a tight three-dimensional network structure after curing. This structure can effectively resist external tensile force, making the material less likely to deform and break under stress, thereby significantly improving the tensile strength. The molecular structure is relatively regular, and the chemical bond vibration between atoms can transfer heat, which helps to conduct heat in the system and improve the thermal conductivity of the material. It has a highly cross-linked insulating molecular network, and there are no free-moving charge carriers, which can effectively prevent current from passing through and significantly improve the volume resistivity. The epoxy groups in its molecules have strong reactivity and can chemically react with active groups on the surface of various materials to form strong chemical bonds, thereby providing excellent adhesion strength. The three-dimensional network structure after cross-linking has high rigidity and stability, and can maintain the integrity of the structure during thermal cycling, reducing structural damage caused by temperature changes and improving thermal cycle stability. The dense cross-linked structure can effectively block the penetration of water molecules, reduce the water absorption of the material, and improve the moisture resistance. In addition, the hydrogenated epoxy resin of bisphenol F type has low viscosity, and the viscosity of the prepared resin matrix prepolymer is less than 800 cP, which has good filling properties and is easy to expel bubbles.

[0037] III. After imidization, the polyamide acid forms a polyimide with a highly conjugated molecular structure. There is a strong interaction force between the molecular chains, including hydrogen bonding and π-π interaction. These forces make the material have high tensile strength. The electron cloud distribution in the conjugated structure is conducive to heat transfer, and the ordered arrangement of the molecular chain also helps to improve the thermal conductivity of the material. The polyimide molecule lacks conductive ions and free electrons, has good insulation performance, and can improve the volume resistivity. The carboxyl and amino groups in the polyamide acid molecule can chemically react with the active groups on the surface of other materials or form hydrogen bonds, enhancing the adhesion. The high temperature resistance and stable molecular structure of polyimide enable it to maintain relatively stable performance during thermal cycling, improving the thermal cycle stability of the material.

[0038] IV. Although silver nanowires have high strength, they are prone to slipping in composite materials. The boron nitride shell has high hardness and is tightly combined with silver nanowires, which can limit the movement of silver nanowires, making silver nanowires work better together when under stress and share the external force, thereby improving the tensile strength of the material. Silver nanowires are excellent thermal conductors, but the interfacial thermal resistance between them and the surrounding medium in the composite material will affect the heat conduction efficiency. Boron nitride also has high thermal conductivity, and the interface formed with silver nanowires can effectively transfer heat. The synergistic effect of the two forms an efficient heat conduction channel, greatly improving the thermal conductivity of the material. Silver nanowires have good electrical conductivity, and if they directly contact each other in the composite material, they will form a conductive path, reducing the insulation performance of the material. Boron nitride, as an insulating material, wraps silver nanowires, effectively isolating the conductive path between silver nanowires, thereby improving the volume resistivity of the material. There are some active groups on the surface of the boron nitride shell, which can chemically react with the active ingredients in the resin matrix or form physical adsorption, enhancing the interfacial bonding force between the core-shell structure filler and the resin matrix and improving the adhesion strength. There is a certain difference in the thermal expansion coefficient between silver nanowires and boron nitride, but after combining, they can restrain each other during thermal cycling, reducing structural deformation and damage caused by thermal expansion and contraction. At the same time, the high stability of boron nitride can also protect silver nanowires from oxidation and other changes at high temperatures, thereby improving the thermal cycle stability of the material. Boron nitride has certain chemical stability and hydrophobicity, and its shell can prevent water from contacting silver nanowires, preventing silver nanowires from being corroded by water, thereby improving the moisture resistance of the material.

[0039] The ethoxy groups in the molecule of γ-aminopropyl triethoxysilane form silanol groups (Si-OH) after hydrolysis, which can condense with the hydroxyl groups on the surface of the boron nitride shell to graft organic groups containing amino groups on the surface of the core-shell structured filler. Amino groups have strong reactivity and can chemically react with active groups in the resin matrix, including reacting with epoxy groups in the epoxy resin, thereby forming chemical bonds between the filler and the matrix and enhancing the bonding force between them. When the material is subjected to tensile force, this chemical bond can effectively transfer stress, making the filler and the matrix work together to resist external force and improve the tensile strength of the material. After modification by γ-aminopropyl triethoxysilane, chemical bonds and organic transition layers are formed between the filler and the matrix, improving the affinity and heat transfer performance of the interface. Heat can be more smoothly transferred from the silver nanowires and boron nitride through the interface to the resin matrix, reducing the interface thermal resistance and improving the thermal conductivity of the material. γ-aminopropyl triethoxysilane itself does not have electrical conductivity, and after grafting onto the surface of the core-shell structured filler, it does not introduce conductive impurities. On the contrary, by enhancing the bonding force between the filler and the matrix, it reduces the leakage channels caused by interface defects, which helps to maintain and improve the volume resistivity of the material. In addition to the chemical reaction with the resin matrix to form chemical bonds, the organic layer formed on the surface of the filler after grafting of γ-aminopropyl triethoxysilane can also produce physical entanglement and van der Waals force with the resin matrix. These various forms of interaction collectively enhance the bonding strength between the filler and the matrix, making the filler less likely to fall off from the matrix when the material is subjected to external force. The enhanced interface bonding force after modification by γ-aminopropyl triethoxysilane can effectively relieve thermal stress and reduce interface separation and internal damage of the material caused by thermal expansion and contraction. At the same time, the organic transition layer formed by it has a certain flexibility and can to some extent buffer thermal stress, improving the thermal cycle stability of the material. The amino groups in γ-aminopropyl triethoxysilane can interact with water molecules to form hydrogen bonds and other weak interactions, thereby fixing some water molecules on the surface of the filler and reducing the penetration of water molecules into the material. In addition, the organic layer after grafting can also block the invasion of water to some extent, improving the moisture resistance of the material.

[0040] The silanol groups formed after the hydrolysis of perfluorooctyltriethoxysilane further condense with the surface of the core-shell structured filler that has been grafted with γ-aminopropyltriethoxysilane, introducing fluorine-containing organic groups onto the surface of the filler. Fluorine-containing groups have high cohesive energy and chemical stability, which can enhance the strength and stability of the filler surface. At the same time, these fluorine-containing groups can also produce certain interactions with the resin matrix, including van der Waals forces and hydrogen bonds, further enhancing the bonding force between the filler and the matrix, allowing the material to better deform cooperatively when subjected to tensile force, improving tensile strength. The introduction of perfluorooctyltriethoxysilane does not affect the thermal conductivity of silver nanowires and boron nitride itself. On the contrary, due to its further improvement of the interfacial affinity between the filler and the matrix, heat transfer between the filler and the matrix is smoother, which helps to reduce the interfacial thermal resistance and improve the thermal conductivity of the material. Perfluorooctyl has strong electronegativity, which can effectively prevent the movement of electrons and has good insulating properties. After grafting it onto the surface of the core-shell structured filler, the insulating properties of the filler are further improved, which helps to improve the volume resistivity of the entire material and prevent leakage caused by the conductivity of the filler. The reaction of perfluorooctyltriethoxysilane with the surface of the filler and its interaction with the resin matrix form a tighter bond between the filler and the matrix. The presence of fluorine-containing groups increases the intermolecular interaction force, not only including chemical bonds, but also stronger van der Waals forces and possible hydrogen bonding, thereby significantly improving the bonding strength. The chemical and thermal stability of fluorine-containing groups is high, which can stabilize the structure of the filler surface during thermal cycling and reduce the damage to the surface structure caused by temperature changes. At the same time, the enhanced interfacial bonding force can also better resist thermal stress and maintain the tight bond between the filler and the matrix, improving the thermal cycling stability of the material. Perfluorooctyl has strong hydrophobicity, which can form a hydrophobic layer on the surface of the filler, effectively preventing water absorption and penetration. Water is difficult to access the interior of the filler and the resin matrix, thereby improving the moisture resistance of the material and reducing the performance degradation caused by water intrusion.

[0041] V. In the pre-polymerization process of the resin matrix, the active groups in the polydimethylsiloxanol-methylsilanol-silicate cross-linked polymer cross-link with silicone pre-polymers, epoxy resins, etc., forming a complex semi-interpenetrating network structure. This network structure can connect different polymer molecules together, increasing the intermolecular interaction force and the overall material integrity. When the material is subjected to tensile force, the network structure can evenly disperse the stress, avoiding stress concentration in local areas, thereby improving the tensile strength of the material. The silicon-oxygen bond in its molecular structure has certain heat conduction capacity, and in the formed semi-interpenetrating network structure, it can synergize with other components with heat conduction capacity (including silicone pre-polymers, epoxy resins, etc.) to participate in the heat conduction process. At the same time, due to its participation in cross-linking reaction, the structure of the whole system is more uniform, reducing the increase of thermal resistance caused by uneven structure, which is conducive to improving the thermal conductivity of the material. Polydimethylsiloxanol-methylsilanol-silicate cross-linked polymer itself is a polymer with good insulation, and there are no free-moving conductive ions or electrons in its molecules. After forming a semi-interpenetrating network structure with other components, it further fills the voids in the system, reducing the conductive channels, thereby improving the volume resistivity of the material. Through cross-linking reaction, polydimethylsiloxanol-methylsilanol-silicate cross-linked polymer forms chemical bonds and physical entanglements between different polymer molecules. This action enhances the interfacial bonding force between different components, so that the material can better adhere to other materials when in contact, improving the adhesion strength. Polydimethylsiloxanol-methylsilanol-silicate cross-linked polymer has good flexibility and thermal stability. In the thermal cycle process, its flexibility can buffer the internal thermal stress of the material caused by temperature changes, reducing the material structure damage caused by thermal expansion and contraction. At the same time, the semi-interpenetrating network structure formed by it also has high stability, which can maintain the integrity of the material at different temperatures, thereby improving the thermal cycle stability of the material. The chemical bond between silicon atoms and oxygen atoms in the siloxane structure has a certain repulsion effect on water molecules, and the network structure formed by polydimethylsiloxanol-methylsilanol-silicate cross-linked polymer can block the penetration of water. When the material is in contact with water, it can effectively prevent water from entering the interior of the material, reduce the water absorption of the material, and improve the moisture resistance of the material.

[0042] VI. Stepwise composite curing encapsulation: The directional filler composite is added to the resin matrix pre-polymer for shearing mixing, so that the directional filler is uniformly dispersed in the resin matrix, and the two are closely combined. In the curing process, the ring-opening reaction of epoxy resin, the imidization of polyimide, and the condensation reaction of silicone are carried out in turn, forming a highly cross-linked complex structure. This structure enhances the intermolecular interaction force within the material, and when subjected to tensile force, it can effectively resist deformation and fracture, improving the tensile strength and other comprehensive properties. DETAILED DESCRIPTION

[0043] The application will be further described in connection with specific implementation cases, but the application is not limited to these examples.

[0044] Example 1

[0045] A resin for electronic component packaging, the resin comprising the following raw materials in mass parts: 45 parts of an epoxy resin, 25 parts of a silicone prepolymer, 15 parts of a polyamide acid solution, 18 parts of a modified core-shell structure filler, 1.5 parts of a polydimethylsiloxane alcohol-methylsilanol-silicate crosslinking polymer, and 2 parts of a silane coupling agent. The modified core-shell structure filler is obtained by modifying the surface of a core-shell structure filler with γ-aminopropyl triethoxysilane and perfluorooctyl triethoxysilane; the inner core of the core-shell structure filler is silver nanowire; and the outer shell of the core-shell structure filler is boron nitride. The silicone prepolymer is the A component main agent part of Sylgard 184. The silicone prepolymer is a silicone prepolymer containing vinyl and Si-OH, with a vinyl content of 6 wt% and a Si-OH content of 4 wt%. The epoxy resin is a hydrogenated epoxy resin of bisphenol F type. The solid content of the polyamide acid solution is 25%, and the solvent is N-methyl pyrrolidone. The silane coupling agent is silane coupling agent KH-792.

[0046] In the modified core-shell structure filler described above, the surface of the silver nanowire is coated with two layers of boron nitride by chemical vapor deposition, with a thickness of 4 nm for each layer of boron nitride, to obtain the core-shell structure filler; the process parameters of the chemical vapor deposition method are: a reaction temperature of 1050°C, a reaction gas of diborane and ammonia, a volume ratio of diborane to ammonia of 1:2.2, a pressure of 8 Pa, and a time of 40 min each time.

[0047] The surface modification method of the modified core-shell structure filler described above includes the following steps:

[0048] N1: Mix γ-aminopropyl triethoxysilane, anhydrous ethanol, and deionized water in a volume ratio of 1.2:5.5:1.5, adjust the pH value to 4.5 with hydrochloric acid, and stir at a speed of 300 r / min at room temperature for 2.5 h to hydrolyze the γ-aminopropyl triethoxysilane and form a hydrolysis product containing silanol groups Si-OH, which is counted as material A;

[0049] N2: Mix perfluorooctyl triethoxysilane, anhydrous ethanol, and deionized water in a volume ratio of 1.2:9:1.5, adjust the pH value to 4.5 with hydrochloric acid, and stir at a speed of 300 r / min at room temperature for 3.5 h to complete the hydrolysis of the perfluorooctyl triethoxysilane and obtain material B;

[0050] N3: by mass ratio, core-shell structure filler: material A = 2:17, the core-shell structure filler is added to material A, and ultrasonic dispersion is carried out for 18 min at 45 kHz until it is uniform. Then, under the condition of a water bath at 65 DEG C, stirring is carried out at 350 r / min for 4 h to make the hydrolysis product of gamma-aminopropyl triethoxysilane and the hydroxyl group on the surface of boron nitride undergo condensation reaction, realizing the grafting of gamma-aminopropyl triethoxysilane on the surface of the core-shell structure filler. Centrifugation is carried out at 9000 r / min for 15 min to separate the upper liquid, and solid product A is obtained. Solid product A is washed with anhydrous ethanol for 4 times to remove unreacted gamma-aminopropyl triethoxysilane and impurities. Then, solid product A and anhydrous ethanol are dispersed in anhydrous ethanol again at a mass ratio of 1.2:9. Ultrasonic dispersion is carried out for 18 min at 45 kHz until it is uniform. Then, material B is added at a mass ratio of solid product A: material B = 1.2:15. Stirring is carried out at 350 r / min for 4 h under the condition of a water bath at 62 DEG C to make the hydrolysis product of perfluorooctyl triethoxysilane and the filler surface to which gamma-aminopropyl triethoxysilane has been grafted undergo further condensation reaction. Centrifugation is carried out at 9000 r / min for 15 min to separate the upper liquid, and solid product B is obtained. Solid product B is washed with anhydrous ethanol and deionized water alternately for a total of 4 times (anhydrous ethanol 2 times + deionized water 2 times) to completely remove unreacted perfluorooctyl triethoxysilane and other impurities. Then, solid product B is vacuum dried at 55 DEG C for 20 h until the weight is constant, and modified core-shell structure filler is obtained.

[0051] The above method for preparing the resin for electronic component packaging comprises the following steps:

[0052] S1, resin matrix prepolymerization:

[0053] Under the protection of nitrogen at a flow rate of 4.5 L / min, the silicone prepolymer, the polydimethylsiloxane alcohol-methylsilanol-silicate cross-linked polymer, and the epoxy resin are added to a reaction kettle according to the mass fraction. Then, 0.5 wt% of tetrabutyl titanate catalyst based on the total mass of the two is added. Stirring is carried out at 220 r / min for 2.5 h at 123 DEG C to form a semi-interpenetrating network structure. After the reaction is completed, the system is cooled to 55 DEG C, and the polyamide acid solution is added. Ultrasonic dispersion is carried out for 40 min at 220 W until it is uniform, and the resin matrix prepolymer is obtained.

[0054] S2, filler directional assembly:

[0055] The modified core-shell structure filler and the silane coupling agent are added to ethanol at 2.5 times the total mass of the two according to the mass fraction. Ball milling is carried out at a rotation speed of 250 r / min for 2 h, and the ball-to-material mass ratio is 6:1.3. After ball milling for 2 h, the milled material is obtained. The milled material is transferred to an electric field induction device, and an electric field strength of 520 V / cm is applied for 35 min to realize the axial directional arrangement of the silver nanowires. Freeze-drying is carried out to obtain a loose and accumulated directional filler composite.

[0056] S3, stepwise composite curing encapsulation:

[0057] S3.1: The directional filler composite is added to the resin matrix prepolymer, and shearing mixing is performed with the parameters of temperature 52℃, vacuum degree 6Pa, and shearing rate 1100s -1 , time 35min, to obtain a mixture, and the viscosity of the mixture is less than 800cP at this time, and the product before encapsulation of the electronic component is obtained;

[0058] S3.2: The mixture is poured into the encapsulation mold until the height of the mold is 1 / 2, the electronic component is placed, the mixture is continuously poured until the electronic component is covered, and the bubbles are discharged. Programmed temperature curing is performed, first curing at 85℃ for 2.5h to make the epoxy resin open ring reaction, then increasing the temperature to 185℃ at a rate of 4℃ / min, curing for 3.5h to realize the imidization of the polyimide, and finally increasing the temperature to 215℃ at a rate of 3℃ / min, curing for 1h to complete the condensation reaction of the silicone, and the internal stress is eliminated by using a stepwise cooling method, and the cooling rate is 25℃ / step, and each temperature stage is maintained for 35min, and the temperature is reduced to room temperature, and the encapsulation of the electronic component is completed, and the resin after encapsulation and molding is obtained.

[0059] Example 2

[0060] A resin for electronic component encapsulation, the resin comprising the following raw materials in mass fraction: 40 parts of epoxy resin, 20 parts of silicone prepolymer, 10 parts of polyamide acid solution, 15 parts of modified core-shell structure filler, 1 part of polydimethylsiloxane alcohol-methylsilanol-silicate crosslinked polymer, and 1.5 parts of silane coupling agent. Among them, the modified core-shell structure filler is obtained by surface modification of the core-shell structure filler surface with γ-aminopropyl triethoxysilane and perfluorooctyl triethoxysilane; the inner core of the core-shell structure filler is silver nanowire; and the outer shell of the core-shell structure filler is boron nitride. The silicone prepolymer is the A component main agent part of Sylgard 184. The silicone prepolymer is a silicone prepolymer containing vinyl and Si-OH, the vinyl content is 5wt%, and the Si-OH content is 3wt%. The epoxy resin is a hydrogenated epoxy resin of bisphenol F type. The solid content of the polyamide acid solution is 20%, and the solvent is N-methyl pyrrolidone. The silane coupling agent is silane coupling agent KH-792.

[0061] In the above modified core-shell structure filler, the silver nanowire surface is coated with two layers of boron nitride by chemical vapor deposition method, and the thickness of each layer of boron nitride is 3nm, to obtain a core-shell structure filler; the process parameters of the chemical vapor deposition method are: reaction temperature 1000℃, reaction gas boron hydride and ammonia, volume ratio boron hydride:ammonia=1:1.5, and pressure 5Pa.

[0062] The surface modification method of the modified core-shell structure filler includes the following steps:

[0063] N1: mixing γ-aminopropyl triethoxysilane, anhydrous ethanol and deionized water in a volume ratio of 1:5:1, adjusting the pH value to 4 with hydrochloric acid, stirring at room temperature at a speed of 200 r / min for 2 h to hydrolyze the γ-aminopropyl triethoxysilane and form a hydrolysis product containing silanol groups Si-OH, which is counted as material A;

[0064] N2: mixing perfluorooctyl triethoxysilane, anhydrous ethanol and deionized water in a volume ratio of 1:8:1, adjusting the pH value to 4 with hydrochloric acid, stirring at room temperature at a speed of 200 r / min for 3 h to complete the hydrolysis of perfluorooctyl triethoxysilane, and obtaining material B;

[0065] N3: mixing the core-shell structure filler and material A in a mass ratio of 1:15, ultrasonic dispersing for 15 min to be uniform, then stirring at 300 r / min under the condition of a water bath at 60°C for 3 h to make the γ-aminopropyl triethoxysilane hydrolysis product and the hydroxyl group on the surface of boron nitride react by condensation, realize the grafting of γ-aminopropyl triethoxysilane on the surface of the core-shell structure filler, centrifuging at 8000 r / min for 10 min to separate the upper liquid and obtain solid product A, washing the solid product A with anhydrous ethanol for 3 times to remove unreacted γ-aminopropyl triethoxysilane and impurities, then dispersing the solid product A and anhydrous ethanol in a mass ratio of 1:8 in anhydrous ethanol, ultrasonic dispersing for 15 min to be uniform, then adding material B in a mass ratio of solid product A:material B = 1:10, stirring at 300 r / min under the condition of a water bath at 60°C for 3 h to make the perfluorooctyl triethoxysilane hydrolysis product and the filler surface grafted with γ-aminopropyl triethoxysilane react by further condensation, centrifuging at 8000 r / min for 10 min to separate the upper liquid and obtain solid product B, washing the solid product B with anhydrous ethanol and deionized water alternately for a total of 4 times (anhydrous ethanol 2 times + deionized water 2 times) to completely remove unreacted perfluorooctyl triethoxysilane and other impurities, then vacuum drying the solid product B at 50°C for 12 h until the weight is constant, and obtaining the modified core-shell structure filler.

[0066] The preparation method of the resin for electronic component packaging includes the following steps:

[0067] S1, resin matrix prepolymerization:

[0068] Under the protection of nitrogen gas with a flow rate of 4 L / min, the silicone prepolymer, polydimethylsiloxane alcohol-methylsilanol-silicate cross-linked polymer, and epoxy resin were added into a reaction kettle according to the mass fraction, and then 0.4 wt% of tetrabutyl titanate catalyst based on the total mass of the two was added. The reaction was carried out at 120°C under stirring at 200 r / min for 2 h to form a semi-interpenetrating network structure. After the reaction, the system was cooled to 50°C, and the polyamic acid solution was added. The mixture was uniformly dispersed by ultrasonic dispersion at a power of 200 W for 30 min to obtain a resin matrix prepolymer.

[0069] S2, filler directional assembly:

[0070] The modified core-shell structure filler and silane coupling agent were added into ethanol with a total mass of 2 times according to the mass fraction, and ball milling was carried out at a speed of 200 r / min for 2 h with a ball-to-material mass ratio of 5:1. After ball milling for 2 h, a ball milling material was obtained. The ball milling material was transferred to an electric field induction device, and an electric field strength of 500 V / cm was applied for an induction time of 30 min to realize axial directional arrangement of silver nanowires. After freeze-drying, a loose and accumulated directional filler composite was obtained.

[0071] S3, step-by-step composite curing and packaging:

[0072] S3.1: The directional filler composite was added to the resin matrix prepolymer, and shearing mixing was carried out at a temperature of 50°C, a vacuum degree of 3 Pa, and a shearing rate of 1000 s -1 , for 30 min to obtain a mixture. At this time, the viscosity of the mixture was less than 800 cP, and the product was an electronic component packaging product.

[0073] S3.2: The mixture was poured into a packaging mold to a height of 2 / 3 of the mold, an electronic component was placed in the mold, and the mixture was continuously poured until the electronic component was covered. After the bubbles were discharged, programmed temperature curing was carried out. First, the epoxy resin was subjected to ring-opening reaction at 80°C for 2 h, and then the temperature was increased to 180°C at a rate of 3°C / min and cured for 3 h to realize imidization of polyimide. Finally, the temperature was increased to 210°C at a rate of 2°C / min and cured for 1 h to complete the condensation reaction of silicone. The temperature was decreased in a stepwise manner to eliminate internal stress at a rate of 20°C / step, and each temperature stage was maintained for 30 min. After the temperature was decreased to room temperature, the electronic component packaging was completed, and a resin after packaging and molding was obtained.

[0074] Example 3

[0075] A resin for electronic component packaging, the resin comprising the following raw materials in mass parts: 40 parts of an epoxy resin, 30 parts of a silicone prepolymer, 20 parts of a polyamide acid solution, 15 parts of a modified core-shell structure filler, 2 parts of a polydimethylsiloxane alcohol-methylsilanol-silicate crosslinking polymer, and 1.5 parts of a silane coupling agent. The modified core-shell structure filler is obtained by modifying the surface of a core-shell structure filler with γ-aminopropyl triethoxysilane and perfluorooctyl triethoxysilane; the inner core of the core-shell structure filler is silver nanowire; and the outer shell of the core-shell structure filler is boron nitride. The silicone prepolymer is the A component main agent part of Sylgard 184. The silicone prepolymer is a silicone prepolymer containing vinyl and Si-OH, with a vinyl content of 8 wt% and a Si-OH content of 3 wt%. The epoxy resin is a hydrogenated epoxy resin of bisphenol F type. The polyamide acid solution has a solid content of 30%, and the solvent is N-methyl pyrrolidone. The silane coupling agent is silane coupling agent KH-792.

[0076] In the modified core-shell structure filler described above, the silver nanowire surface is coated with two layers of boron nitride by chemical vapor deposition, with each layer of boron nitride having a thickness of 3 nm, to obtain a core-shell structure filler; the process parameters of the chemical vapor deposition method are: a reaction temperature of 1100℃, a reaction gas of diborane and ammonia, a volume ratio of diborane to ammonia of 1:1.5, and a pressure of 10 Pa.

[0077] In the modified core-shell structure filler described above, the surface modification method of the modified core-shell structure filler comprises the following steps:

[0078] N1: Mix by volume ratio γ-aminopropyl triethoxysilane: anhydrous ethanol: deionized water = 1:6:1.5, adjust the pH value to 4.2 with hydrochloric acid, and stir at room temperature at a speed of 400 r / min for 2 h to make the γ-aminopropyl triethoxysilane fully hydrolyzed to form a hydrolysis product containing silanol groups Si-OH, which is counted as material A;

[0079] N2: Mix by volume ratio perfluorooctyl triethoxysilane: anhydrous ethanol: deionized water = 1.5:8:1.5, adjust the pH value to 4.6 with hydrochloric acid, and stir at room temperature at a speed of 400 r / min for 4 h to complete the hydrolysis of perfluorooctyl triethoxysilane to obtain material B;

[0080] N3: by mass ratio, core-shell structure filler: material A = 2:15, the core-shell structure filler is added to material A, and ultrasonic dispersion is carried out for 15 min to be uniform, then in the condition of water bath at 70 DEG C, 300 r / min stirring reaction 3h, make gamma-aminopropyl triethoxysilane hydrolysis product and the condensation reaction of the hydroxyl group on the surface of boron nitride, realize gamma-aminopropyl triethoxysilane on the surface of the core-shell structure filler grafting; centrifugation 10 min at 8000 r / min, separate the upper liquid, obtain solid product A, wash 3 times with anhydrous ethanol to remove unreacted gamma-aminopropyl triethoxysilane and impurities; then the solid product A and anhydrous ethanol are dispersed in anhydrous ethanol at a mass ratio of 1.5:8, ultrasonic dispersion is carried out for 20 min to be uniform; then according to the mass ratio, solid product A: material B = 1:15, material B is added, and stirring reaction is carried out at 400 r / min for 3h under the condition of water bath at 65 DEG C, so that the hydrolysis product of perfluorooctyl triethoxysilane and the filler surface grafted with gamma-aminopropyl triethoxysilane further condense; centrifugation 20 min at 8000 r / min, separate the upper liquid, obtain solid product B, wash with anhydrous ethanol and deionized water alternately for a total of 6 times (anhydrous ethanol 3 times + deionized water 3 times) to completely remove unreacted perfluorooctyl triethoxysilane and other impurities, then the solid product B is vacuum dried at 60 DEG C for 18h until the constant weight, to obtain the modified core-shell structure filler.

[0081] The above method for preparing the resin for electronic component packaging comprises the following steps:

[0082] S1, resin matrix prepolymerization:

[0083] Under the protection of nitrogen at a flow rate of 4 L / min, the silicone prepolymer, the polydimethylsiloxane alcohol-methylsilanol-silicate cross-linked polymer and the epoxy resin are added into a reaction kettle according to the mass fraction, then 0.4wt% of tetrabutyl titanate catalyst is added, stirring reaction is carried out at 125 DEG C and 200 r / min for 3h to form a semi-interpenetrating network structure; after the reaction, the system is cooled to 50 DEG C, the polyamide acid solution is added, and ultrasonic dispersion is carried out at 200 W for 30 min until uniform to obtain the resin matrix prepolymer;

[0084] S2, filler directional assembly:

[0085] The modified core-shell structure filler and the silane coupling agent are added into ethanol with a total mass of 3 times according to the mass fraction, and ball milling is carried out at a rotation speed of 200 r / min for 2.5h, the ball-to-material mass ratio is 6:1, and the ball milling is carried out for 2h to obtain the ball milling material; the ball milling material is transferred to an electric field induction device, an electric field strength of 500 V / cm is applied, and the induction time is 40 min to realize the axial directional arrangement of the silver nanowires, and the freeze-drying is carried out to obtain a loose and accumulated directional filler composite;

[0086] S3, stepwise composite curing encapsulation:

[0087] S3.1: The directional filler composite is added to the resin matrix prepolymer, and shearing mixing is performed with the parameters of temperature 55℃, vacuum degree 5Pa, and shearing rate 1000s -1 , time 30min, to obtain a mixture, and the viscosity of the mixture is less than 800cP, which is the product before encapsulation of the electronic component;

[0088] S3.2: The mixture is poured into the encapsulation mold until the height of the mold is 1 / 2, the electronic component is placed, the mixture is continuously poured until the electronic component is covered, and the bubbles are discharged. The programmed temperature curing is performed. First, the epoxy resin is cured at 90℃ for 3h to make ring-opening reaction, then the temperature is raised to 180℃ at a rate of 5℃ / min, and cured for 3h to realize imidization of polyimide, finally the temperature is raised to 220℃ at a rate of 3℃ / min, and cured for 1h to complete the condensation reaction of silicone. The stepwise cooling method is used to eliminate internal stress, and the cooling rate is 30℃ / step, and each temperature stage is maintained for 30min. The temperature is lowered to room temperature, and the encapsulation of the electronic component is completed, and the resin after encapsulation is obtained.

[0089] Example 4

[0090] A resin for electronic component encapsulation, the resin comprising the following raw materials in mass fraction: 50 parts of epoxy resin, 30 parts of silicone prepolymer, 20 parts of polyamide acid solution, 20 parts of modified core-shell structure filler, 2 parts of polydimethylsiloxane alcohol-methylsilanol-silicate crosslinked polymer, and 3 parts of silane coupling agent. The surface of the modified core-shell structure filler is modified by γ-aminopropyl triethoxysilane and perfluorooctyl triethoxysilane. The inner core of the core-shell structure filler is silver nanowire. The shell of the core-shell structure filler is boron nitride. The silicone prepolymer is the A component main agent part of Sylgard 184. The silicone prepolymer is a silicone prepolymer containing vinyl and Si-OH, the vinyl content is 8wt%, and the Si-OH content is 5wt%. The epoxy resin is a hydrogenated epoxy resin of bisphenol F type. The solid content of the polyamide acid solution is 30%, and the solvent is N-methyl pyrrolidone. The silane coupling agent is silane coupling agent KH-792.

[0091] In the above modified core-shell structure filler, the surface of the silver nanowire is coated with two layers of boron nitride by chemical vapor deposition, and the thickness of each layer of boron nitride is 5nm, to obtain a core-shell structure filler. The process parameters of the chemical vapor deposition method are: reaction temperature 1100℃, reaction gas boron ethane and ammonia, volume ratio borane:ammonia=1:3, and pressure 10Pa.

[0092] The surface modification method of the modified core-shell structure filler includes the following steps:

[0093] N1: Mix γ-aminopropyl triethoxysilane, anhydrous ethanol and deionized water in a volume ratio of 1.5:6:2, adjust the pH value to 5 with hydrochloric acid, and stir at room temperature at a speed of 400 r / min for 3 h to make the γ-aminopropyl triethoxysilane fully hydrolyzed to form a hydrolysis product containing silanol groups Si-OH, which is counted as material A;

[0094] N2: Mix perfluorooctyl triethoxysilane, anhydrous ethanol and deionized water in a volume ratio of 1.5:10:2, adjust the pH value to 5 with hydrochloric acid, and stir at room temperature at a speed of 400 r / min for 4 h to complete the hydrolysis of perfluorooctyl triethoxysilane to obtain material B;

[0095] N3: Mix the core-shell structure filler and material A in a mass ratio of 3:20, ultrasonically disperse for 20 min to make the core-shell structure filler uniform, then stir at 400 r / min under the condition of a water bath at 70°C for 5 h to make the γ-aminopropyl triethoxysilane hydrolysis product and the hydroxyl group on the surface of boron nitride undergo condensation reaction, realizing the grafting of γ-aminopropyl triethoxysilane on the surface of the core-shell structure filler; centrifuge at 10000 r / min for 20 min to separate the upper liquid to obtain solid product A, wash with anhydrous ethanol for 5 times to remove unreacted γ-aminopropyl triethoxysilane and impurities; then disperse the solid product A and anhydrous ethanol in a mass ratio of 1.5:10 in anhydrous ethanol, ultrasonically disperse for 20 min to make them uniform; then add material B in a mass ratio of 1.5:20, stir at 400 r / min under the condition of a water bath at 65°C for 5 h to make the perfluorooctyl triethoxysilane hydrolysis product and the filler surface grafted with γ-aminopropyl triethoxysilane undergo further condensation reaction; centrifuge at 10000 r / min for 20 min to separate the upper liquid to obtain solid product B, wash with anhydrous ethanol and deionized water alternately for a total of 6 times (3 times with anhydrous ethanol + 3 times with deionized water) to completely remove unreacted perfluorooctyl triethoxysilane and other impurities, then vacuum dry the solid product B at 60°C for 24 h until the weight is constant to obtain the modified core-shell structure filler.

[0096] The preparation method of the above-mentioned resin for electronic component packaging includes the following steps:

[0097] S1, resin matrix prepolymerization:

[0098] Under the protection of nitrogen gas with a flow rate of 5 L / min, the silicone prepolymer, polydimethylsiloxane alcohol-methylsilanol-silicate cross-linked polymer, and epoxy resin were added into a reaction kettle according to the mass fraction, and then 0.6 wt% of the total mass of the two of tetrabutyl titanate catalyst was added. The reaction was carried out at 125℃ with stirring at 250 r / min for 3h to form a semi-interpenetrating network structure. After the reaction, the system was cooled to 60℃, and the polyamic acid solution was added. The resin matrix prepolymer was obtained by ultrasonic dispersion at 250W for 50min until uniform.

[0099] S2, filler directional assembly:

[0100] The modified core-shell structure filler and silane coupling agent were added into ethanol with a total mass of 3 times according to the mass fraction, and ball milling was carried out at a speed of 300 r / min for 2.5h with a ball-to-material mass ratio of 8:1.5. After ball milling for 2.5h, the ball milling material was obtained. The ball milling material was transferred to an electric field induction device, an electric field strength of 550V / cm was applied, and the induction time was 40min to realize the axial directional arrangement of silver nanowires. The loose packed directional filler composite was obtained by freeze-drying.

[0101] S3, step-by-step composite curing and packaging:

[0102] S3.1: The directional filler composite was added to the resin matrix prepolymer, and shearing mixing was carried out with the parameters of temperature 55℃, vacuum degree 10Pa, and shearing rate 1200s -1 , time 40min to obtain a mixture. At this time, the viscosity of the mixture was less than 800cP, and the product before electronic component packaging was obtained.

[0103] S3.2: The mixture was poured into a packaging mold until the height of 2 / 3 of the mold, and an electronic component was placed in. The mixture was continued to be poured until covering the electronic component, and the bubbles were discharged. The programmed temperature curing was carried out. First, the epoxy resin was cured at 90℃ for 3h to make ring-opening reaction, then the temperature was increased to 190℃ at a rate of 5℃ / min, and cured for 4h to realize the imidization of polyimide. Finally, the temperature was increased to 220℃ at a rate of 3℃ / min, and cured for 1.5h to complete the condensation reaction of silicone. The stepwise cooling method was used to eliminate internal stress, and the cooling rate was 30℃ / step. Each temperature stage was maintained for 40min, and the cooling was carried out to room temperature. The electronic component packaging was completed, and the resin after packaging and molding was obtained.

[0104] In the above examples: the silicone prepolymer is from Dow Corning, model Sylgard 184, base glue part, i.e. component A, which has a low glass transition temperature, good flexibility, a low coefficient of thermal expansion (CTE) of less than 35 ppm / ℃, and can effectively buffer the thermal stress of electronic components during operation. The epoxy resin is a hydrogenated epoxy resin of bisphenol F type from Guangzhou Dongzhen New Materials Co., Ltd., Mitsubishi JER epoxy resin 1750, which has a low viscosity and is easy to mix with other components and package. Its molecular structure also gives the resin high moisture resistance. The polyamide acid is from Wuhan Huaxiang Kejebio Technology Co., Ltd., model HXKJ98745. The silane coupling agent KH-792 is from Dongguan Shanyi Plastic Co., Ltd. The polydimethylsiloxane alcohol-methylsilanol-silicate cross-linked polymer is from Shenzhen Ruigite Biotechnology Co., Ltd., model RGT20623. The silver nanowire is from Nanjing Hongde Nanometer Material Co., Ltd., model 0475NW3W, D25-30 nm. The γ-aminopropyl triethoxysilane is from Shandong Moore Chemical Co., Ltd., molecular weight 221.4. The perfluorooctyl triethoxysilane is from Jiangsu Puleisi Biotechnology Co., Ltd. The tetrabutyl titanate catalyst is from Shandong Lingguan Fine Chemical Co., Ltd., purity 99%.

[0105] In the above examples: the hydrochloric acid is an aqueous solution of hydrochloric acid with a concentration of 0.5 mol / L.

[0106] Comparative Example 1

[0107] No polydimethylsiloxane alcohol-methylsilanol-silicate cross-linked polymer is added to the raw material of the resin; other parameters and methods are the same as in Example 1.

[0108] Comparative Example 2

[0109] No perfluorooctyl triethoxysilane is added during the modification process of the modified core-shell structure filler; other parameters and methods are the same as in Example 1.

[0110] Comparative Example 3

[0111] The modified core-shell structure filler is not modified, and the modified core-shell structure filler is replaced by a core-shell structure filler; other parameters and methods are the same as in Example 1.

[0112] Comparative Example 4

[0113] The modified core-shell structure filler is replaced by silver nanowires; other parameters and methods are the same as in Example 1.

[0114] The resins of the above examples and comparative examples are detected.

[0115] I. Tensile strength: The tensile strength test specimen (pure resin specimen, not containing electronic components) was prepared according to GB / T 1040.2 "Determination of tensile properties of plastics - Part 2: test conditions for moulded and extruded plastics". The specimen was installed on the clamp of the universal material testing machine, the initial gap was adjusted to 50 mm, the center line of the specimen was aligned with the center line of the clamp, and the specimen was stretched at a speed of 5 mm / min until it broke. The maximum load F at the time of specimen breakage was recorded to 0.1 N. The cross-sectional area S of the specimen was measured, and the tensile strength σ = F / S was calculated, with the unit of MPa, and the result was rounded to two decimal places. The test results are shown in Table 1 below.

[0116] II. Thermal conductivity: The thermal conductivity test specimen (pure resin specimen, not containing electronic components) was prepared according to ASTM E1461-13 "Standard Test Method for Thermal Diffusivity of Solids by the Flash Method". The specimen was placed in the sample cell of the thermal constant analyzer, and the thermal diffusivity α was measured at each temperature point under the condition of 50 mL / min helium gas flow and a temperature rise rate of 10 ℃ / min from 25 ℃ to 150 ℃. The thermal conductivity λ = α x p x C p was calculated, where p is the density (measured by the specific gravity bottle method) and C p is the specific heat capacity (measured by DSC). The test results are shown in Table 1 below.

[0117] III. Volume resistivity: The volume resistivity test specimen (pure resin specimen, not containing electronic components) was prepared according to GB / T 1410 "Test method for volume and surface resistivity of solid insulating materials". The specimen was installed on the high resistance meter, and the resistance value R after 1 min was measured under the condition of applying a direct current voltage of 500 V to the sample. The volume resistivity p v = R x S / d was calculated, where S is the effective current cross-sectional area of the electrode and the specimen in contact, and d is the length of the specimen in the current direction. The test results are shown in Table 1 below.

[0118] IV. Shear strength: The shear strength test specimen (containing electronic components) was prepared according to GB / T 7124 "Determination of tensile shear strength of adhesives". The specimen was installed on the shear clamp of the electronic universal testing machine, and the shear force was applied to the interface between the resin and the electronic components at a shear speed of 1 mm / min until the resin and the electronic components separated. The maximum shear force F was recorded, and the shear strength τ = F / S was calculated, where S is the bonding area. The test results are shown in Table 1 below.

[0119] V. Thermal cycle stability: Put the packaged electronic component test piece into a high-low temperature test box for thermal cycle test. Refer to the thermal cycle test conditions in GJB 128A "Semiconductor Discrete Device Test Method". The thermal cycle conditions are as follows: from -55°C to 125°C at a rate of 5°C / min, and keep at 125°C for 30 min; then from 125°C to -55°C at a rate of 5°C / min, and keep at -55°C for 30 min, which is one cycle; a total of 1000 cycles. Before and after the cycle, use an X-ray flaw detector to detect whether the package has cracks or voids and other defects. Record the structural changes of the package before and after thermal cycling, and evaluate its thermal cycle stability. The test results are shown in Table 1 below.

[0120] VI. Moisture resistance: Put the packaged electronic component test piece into a constant temperature and humidity chamber, and set the temperature of the constant temperature and humidity chamber to 85°C and the relative humidity to 85% according to GB / T 2423.3 "Environmental Testing Part 2: Test Methods Test Cab: Constant Temperature and Humidity Test". Put the electronic component into the chamber and keep it for 1000 hours. After taking it out, use a multimeter to measure the electrical performance of the electronic component, check whether there is a short circuit or open circuit, and record the electrical performance changes of the electronic component before and after the moisture resistance test. Evaluate its moisture resistance. The test results are shown in Table 1 below.

[0121] Table 1 Test Results

[0122]

[0123]

[0124] From the above results, it can be seen that the resins of Examples 1 to 4 have higher tensile strength, shear strength and resistivity, and can better conduct heat, have better thermal cycle stability and moisture resistance, and have long service life.

[0125] The resin raw material of Comparative Example 1 does not add a polydimethylsiloxanol-methylsilanol-silicate crosslinking polymer. This polymer can enhance the overall network structure of the resin through crosslinking in the system. Without it, the intermolecular forces within the resin are weaker, and the molecular chain segments are relatively more free. During the stretching process, the molecular chains are prone to slip and break. This crosslinking polymer helps to build more continuous heat conduction channels, and after its absence, the connection between the heat conduction particles becomes worse, and the thermal conductivity efficiency decreases. During the thermal cycle process, due to the unstable network structure, it cannot effectively buffer thermal stress, resulting in cracks. In the moisture resistance test, water molecules are more likely to invade the inside of the resin, damaging its electrical insulation performance and causing electrical leakage.

[0126] No perfluorooctyl triethoxysilane was added in the modification process of the modified core-shell structure filler of Comparative Example 2. Perfluorooctyl triethoxysilane can improve the interfacial compatibility between the filler and the resin matrix, making the combination between the two more compact. Without it, there are more interfacial defects between the filler and the resin matrix, and the interfacial bonding force is insufficient. These defects are prone to become stress concentration points, leading to premature failure of the material and a decrease in tensile strength. In the process of heat conduction, the interfacial thermal resistance increases, and the thermal conductivity decreases. In the process of thermal cycling and moisture resistance, due to the weak interfacial bonding, moisture and thermal stress are more likely to cause interfacial debonding, resulting in more cracks and obvious electrical leakage.

[0127] The modified core-shell structure filler of Comparative Example 3 was not modified and was directly replaced by a core-shell structure filler. The interaction between the unmodified core-shell structure filler and the resin matrix is mainly physical adsorption, and the bonding force is far inferior to that of the filler after surface modification. This makes the material prone to relative sliding between the filler and the matrix when stressed, and unable to effectively transfer stress, resulting in a significant decrease in tensile strength. For thermal conduction, due to the lack of effective interfacial connection, it is difficult to form an efficient heat conduction network, and the thermal conductivity decreases significantly. Weak bonding force leads to easy destruction of the internal structure of the material during thermal cycling and moisture resistance, resulting in serious cracking and short circuiting.

[0128] The modified core-shell structure filler of Comparative Example 4 was replaced by silver nanowires. Silver nanowires are prone to agglomeration in the resin, with poor dispersibility, and cannot be uniformly distributed and form an effective strengthening and heat conduction network like the modified core-shell structure filler. Agglomerated silver nanowires not only cannot effectively enhance the mechanical properties of the material, but also become weak points in the internal structure of the material, resulting in a decrease in tensile strength. In terms of heat conduction, due to uneven dispersion, it is difficult to form a continuous heat conduction path, and the thermal conductivity decreases. In the process of thermal cycling and moisture resistance, the material performs very poorly, with serious damage and short circuiting.

Claims

1. A resin for electronic component packaging, characterized by comprising: The resin comprises the following raw materials in mass fraction: 40-50 parts of epoxy resin, 20-30 parts of silicone prepolymer, 10-20 parts of polyamide acid solution, 15-20 parts of modified core-shell structure filler, 1-2 parts of dimethicone-methylsilanol-silicate cross-linked polymer, and 1.5-3 parts of silane coupling agent; The silicone prepolymer is the A component main agent part of Sylgard 184; the silicone prepolymer is a silicone prepolymer containing vinyl and Si-OH, the content of vinyl being 5wt%-8wt%, and the content of Si-OH being 3wt%-5wt%; The modified core-shell structure filler is obtained by surface modification of the core-shell structure filler using γ-aminopropyl triethoxysilane and perfluorooctyl triethoxysilane; the inner core of the core-shell structure filler is silver nanowire; and the outer shell of the core-shell structure filler is boron nitride; The dimethicone-methylsilanol-silicate cross-linked polymer is of type RGT20623.

2. The resin for electronic component packaging according to claim 1, wherein The epoxy resin is hydrogenated epoxy resin of bisphenol F type; the solid content of the polyamide acid solution is 20%-30%, and the solvent is N-methyl pyrrolidone; and the silane coupling agent is silane coupling agent KH-792.

3. The resin for electronic component packaging according to claim 1, wherein The silver nanowire is coated with two layers of boron nitride by chemical vapor deposition, each layer of boron nitride having a thickness of 3-5 nm, to obtain a core-shell structure filler; the process parameters of the chemical vapor deposition are as follows: reaction temperature 1000-1100℃, reaction gas being ethyl borane and ammonia, volume ratio of borane to ammonia being 1: (1.5-3), and pressure being 5-10 Pa.

4. The resin for electronic component packaging according to claim 1, wherein The surface modification method of the modified core-shell structure filler comprises the following steps: N1: mixing γ-aminopropyl triethoxysilane, anhydrous ethanol and deionized water in a volume ratio of (1-1.5):(5-6):(1-2), adjusting the pH value to 4-5 with hydrochloric acid, stirring at room temperature, hydrolyzing the γ-aminopropyl triethoxysilane to form a hydrolysis product containing silanol group Si-OH, and counting as material A; N2: mixing perfluorooctyl triethoxysilane, anhydrous ethanol and deionized water in a volume ratio of (1-1.5):(8-10):(1-2), adjusting the pH value to 4-5 with hydrochloric acid, stirring at room temperature, and completing the hydrolysis of perfluorooctyl triethoxysilane to obtain material B; N3: according to the mass ratio, core-shell structure filler: material A = (1-3):(15-20), the core-shell structure filler is added to material A, ultrasonic dispersion is uniform, then under the condition of water bath at 60-70 DEG C, stirring reaction, centrifugal separation, separation of the upper liquid, to obtain solid product A, washed with anhydrous ethanol 3-5 times, then the solid product A and anhydrous ethanol according to the mass ratio (1-1.5):(8-10), re-dispersed in anhydrous ethanol, ultrasonic dispersion is uniform; then according to the mass ratio, solid product A: material B = (1-1.5):(10-20), material B is added, under the condition of water bath at 60-65 DEG C, stirring reaction, centrifugal separation, separation of the upper liquid, to obtain solid product B, washed with anhydrous ethanol and deionized water alternately for a total of 4-6 times, then the solid product B is vacuum dried to constant weight, to obtain the modified core-shell structure filler.

5. The resin for electronic component packaging according to claim 4, wherein In N1, the stirring speed is 200-400 r / min, and the stirring time is 2-3 h; in N2, the stirring speed is 200-400 r / min, and the stirring time is 3-4 h; in N3, the ultrasonic dispersion frequency is 40-50 kHz, the ultrasonic dispersion time is 15-20 min, the stirring speed is 300-400 r / min, the stirring time is 3-5 h, the centrifugal speed is 8000-10000 r / min, the centrifugal time is 10-20 min, the vacuum drying temperature is 50-60 DEG C, and the vacuum drying time is 12-24 h.

6. A method for producing a resin for electronic component packaging, for producing the resin for electronic component packaging according to Claim 1, characterized by, The preparation method comprises the following steps: S1, resin matrix prepolymerization: Under the protection of nitrogen, according to the mass fraction, the organosilicon prepolymer, the polydimethylsiloxane alcohol-methylsilanol-silicate crosslinked polymer, and the epoxy resin are added to the reaction kettle, then the tetrabutyl titanate catalyst is added, and stirring reaction is carried out at 120-125 DEG C for 2-3 h; after the reaction is completed, the system is cooled to 50-60 DEG C, the polyamide acid solution is added, and ultrasonic dispersion is carried out until uniform, to obtain a resin matrix prepolymer; S2, filler directional assembly: According to the mass fraction, the modified core-shell structure filler and the silane coupling agent are added to ethanol, ball milling is carried out to obtain a ball milling material; the ball milling material is transferred to an electric field induction device, an electric field strength of 500-550 V / cm is applied, the induction time is 30-40 min, the axial directional arrangement of silver nanowires is realized, and freeze-drying is carried out to obtain a loose and accumulated directional filler composite; S3, step-by-step composite curing and packaging: S3.1: the directional filler composite is added to the resin matrix prepolymer, shear mixing is carried out to obtain a mixture, at this time the viscosity of the mixture is less than 800 cP, and an electronic component packaging product is obtained. S3.2: Pour the mixture into the packaging mold until 1 / 2~2 / 3 height of the mold, place the electronic components, continue to pour the mixture until covering the electronic components, expel the bubbles, and perform programmed temperature curing, first at 80~90℃ for 2~3h, then at 180~190℃ for 3~4h, finally at 210~220℃ for 1~1.5h, and cool to room temperature, to complete the electronic component packaging, to obtain the resin after packaging and molding.

7. The method of producing a resin for electronic component packaging according to claim 6, wherein In S1, the amount of the tetrabutyl titanate catalyst is 0.4wt%~0.6wt% of the total mass of the organosilicon prepolymer and the epoxy resin, the flow rate of the nitrogen is 4L / min~5L / min, the stirring speed is 200r / min~250r / min, the ultrasonic power is 200W~250W, and the ultrasonic time is 30min~50min; in S2, the amount of the ethanol is 2~3 times of the total mass of the modified core-shell structure filler and the silane coupling agent; the ball milling speed is 200r / min~300r / min, the ball milling time is 2h~2.5h, and the ball-to-material mass ratio is (5~8):(1~1.5).

8. The method of producing a resin for electronic component packaging according to Claim 6, wherein In S3.1, the parameters of the shear mixing are: temperature 50-55℃, vacuum degree 3-10Pa, shear rate 1000-1200s -1 -1 -1 , time 30-40min; in S3.2, the temperature is raised to 180-190℃ at a rate of 3-5℃ / min, and then to 210-220℃ at a rate of 2-3℃ / min, the internal stress is eliminated by using a stepwise cooling method, the temperature is lowered at a rate of 20-30℃ / step, and each temperature stage is kept for 30-40min until the temperature is lowered to room temperature.

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