Resin for packaging electronic component and preparation method thereof

Abstract

The invention relates to resin for electronic component packaging and a preparation method thereof, and belongs to the technical field of high polymer materials, the resin raw materials comprise epoxy resin, an organosilicon prepolymer, a polyamide acid solution, a modified core-shell structure filler, a polydimethylsiloxane alcohol-methylsilanol-silicate ester cross-linked polymer, a silane coupling agent and the like. The resin matrix adopts an organosilicon-epoxy-polyimide-cross-linked polymer quaternary interpenetrating network, the functional filler adopts a specially modified core-shell heterostructure functional filler, the performance breakthrough is realized through a novel composite system and a step-by-step controllable process, and the composite material has good filling property, thermal conductivity and stability, and is suitable for large-scale production. Good packaging of electronic components can be realized, and the service life is long.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a resin for electronic component packaging and a preparation method thereof. Background Art

[0002] With the rapid development of electronic information technology, electronic equipment is moving towards miniaturization, lightness, high performance and multifunctionality. In this development process, electronic component packaging technology, as a key link to ensure the stable operation of electronic equipment, has become increasingly important, and electronic component packaging resin is the core material of packaging technology, playing an irreplaceable role.

[0003] With the trend of miniaturization of electronic devices, the integration of electronic components is constantly increasing and their size is constantly shrinking. This requires packaging materials to be able to adapt to smaller spaces and have good filling properties to ensure effective protection of tiny components. For example, the size of chips in smartphones is getting smaller and smaller, and the internal structure is becoming more and more complex. The resin used to encapsulate electronic components needs to be accurately filled into each tiny gap to avoid voids or bubbles, thereby providing reliable physical protection for chips and other components to prevent them from being eroded by the external environment.

[0004] The high performance of electronic devices also places stringent requirements on encapsulation resins. Electronic components will generate a lot of heat during high-speed operation. If it cannot be dissipated in a timely and effective manner, it will seriously affect the performance and life of the components. Therefore, encapsulation resins need to have excellent thermal conductivity, be able to quickly conduct heat away, and achieve good heat dissipation effects. At the same time, as the transmission speed of electronic signals continues to increase, encapsulation resins are also required to have low dielectric constants and low dielectric losses to reduce delays and attenuation during signal transmission and ensure stable signal transmission.

[0005] In addition, electronic devices may face a variety of harsh conditions such as high temperature, high humidity, and chemical corrosion in different working environments. This requires the resin used to encapsulate electronic components to have excellent chemical stability, corrosion resistance, and weather resistance. In high-temperature environments, the resin will not decompose, deform, or deteriorate in performance; in high-humidity environments, it can effectively block the intrusion of moisture and prevent components from being damaged by moisture; when faced with chemical erosion, it can still maintain the stability of structure and performance, ensuring that electronic components can work reliably for a long time in complex environments.

[0006] At present, although there are many types of electronic component encapsulation resins that are widely used, such as epoxy resins, silicone resins, phenolic resins, etc., they all play an important role in their respective fields, but with the continuous innovation of electronic technology, the requirements for the performance of encapsulation resins are also constantly increasing. The comprehensive performance of each product gradually cannot meet the higher requirements of use, and it is necessary to continuously develop new encapsulation resins with better comprehensive performance and adapt to the development trend of precision electronics. Summary of the invention

[0007] In order to further improve the comprehensive performance of electronic component packaging resins such as filling, thermal conductivity, and stability, and adapt to precision electronic packaging applications, the present invention provides an electronic component packaging resin and a preparation method thereof. The resin matrix adopts a quaternary interpenetrating network of organic silicon-epoxy-polyimide-cross-linked polymer, and the functional filler adopts a specially modified core-shell heterostructure functional filler. A performance breakthrough is achieved through a new composite system and a step-by-step controllable process. It has good filling, thermal conductivity, and stability, can achieve good packaging of electronic components, and has a long service life. The specific technical scheme is as follows:

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

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

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

[0011] Among the above raw materials, the solid content of the polyamic acid solution is 20% to 30%, and the solvent is N-methylpyrrolidone.

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

[0013] Among the above raw materials, the modified core-shell structure filler is obtained by modifying the surface of the core-shell structure filler with γ-aminopropyltriethoxysilane and perfluorooctyltriethoxysilane; the core of the core-shell structure filler is silver nanowire; and the shell of the core-shell structure filler is boron nitride.

[0014] In the above-mentioned 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 3nm to 5nm to obtain a core-shell structure filler; the process parameters of the chemical vapor deposition method are: reaction temperature 1000℃~1100℃, reaction gas is diborane and ammonia, the volume ratio is borane:ammonia=1:(1.5~3), and the pressure is 5Pa~10Pa.

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

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

[0017] N2: Mix perfluorooctyltriethoxysilane: anhydrous ethanol: 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 to complete the hydrolysis of perfluorooctyltriethoxysilane, and obtain material B;

[0018] N3: According to the mass ratio, core-shell structure filler: material A = (1-3): (15-20), add the core-shell structure filler to material A, ultrasonically disperse until uniform, then stir and react in a water bath at 60°C to 70°C to make the hydrolyzate of γ-aminopropyltriethoxysilane react with the hydroxyl group on the surface of boron nitride to achieve the grafting of γ-aminopropyltriethoxysilane on the surface of the core-shell structure filler; centrifuge to separate the upper liquid to obtain a solid product A, wash with anhydrous ethanol for 3 to 5 times to remove unreacted γ-aminopropyltriethoxysilane and impurities; then mix the solid product A with anhydrous ethanol in a mass ratio of (1-1.5): (8-10 ), redispersed in anhydrous ethanol, and ultrasonically dispersed until uniform; then, according to the mass ratio of solid product A: material B = (1-1.5): (10-20), material B is added, and the reaction is stirred in a water bath at 60°C-65°C to allow the hydrolyzate of perfluorooctyltriethoxysilane to undergo further condensation reaction with the filler surface grafted with γ-aminopropyltriethoxysilane; centrifugation is performed to separate the upper liquid to obtain a solid product B, and the solid product B is washed alternately with anhydrous ethanol and deionized water for a total of 4-6 times to completely remove unreacted perfluorooctyltriethoxysilane and other impurities, and then the solid product B is vacuum dried to constant weight to obtain a 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 of the modified core-shell structure filler in N2, the stirring speed is 200r / min to 400r / min, and the stirring time is 3h to 4h.

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

[0022] The above-mentioned method for preparing the resin for electronic component packaging comprises the following steps:

[0023] S1, resin matrix prepolymerization:

[0024] Under nitrogen protection, add silicone prepolymer, polydimethylsiloxane alcohol-methylsilanol-silicate cross-linked polymer, and epoxy resin into a reaction kettle according to mass fractions, then add tetrabutyl titanate catalyst, and stir the reaction at 120° C. to 125° C. for 2 h to 3 h to form a semi-interpenetrating network structure; after the reaction, cool the system to 50° C. to 60° C., add polyamic acid solution, and ultrasonically disperse until uniform to obtain a resin matrix prepolymer;

[0025] S2, packing oriented assembly:

[0026] The modified core-shell structure filler and the silane coupling agent are added to ethanol according to the mass fraction, and ball-milled to obtain a ball-milled material; the ball-milled material is transferred to an electric field induction device, and an electric field strength of 500V / cm to 550V / cm is applied for an induction time of 30min to 40min to achieve axial directional arrangement of the silver nanowires, and freeze-dried to obtain a loosely stacked directional filler composite;

[0027] S3, step-by-step composite curing package:

[0028] S3.1: adding the directional filler composite to the resin matrix prepolymer, shearing and mixing, to obtain a mixed material, wherein the viscosity of the mixed material is lower than 800 cP, and the product before electronic component packaging;

[0029] S3.2: Pour the mixed material into the packaging mold until it reaches 1 / 2 to 2 / 3 of the height of the mold, place the electronic components, and continue to pour the mixed material until the electronic components are covered. Expel the bubbles and perform programmed temperature curing. First, cure at 80°C to 90°C for 2h to 3h, then heat to 180°C to 190°C and cure for 3h to 4h, and finally heat to 210°C to 220°C and cure for 1h to 1.5h. Cool to room temperature to complete the electronic component packaging and obtain the encapsulated resin.

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

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

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

[0033] In S3.2 of the above preparation method, the temperature is increased to 180°C to 190°C at a heating rate of 3°C / min to 5°C / min, and the temperature is increased to 210°C to 220°C at a heating rate of 2°C / min to 3°C / min. The cooling adopts a step-by-step cooling method to eliminate internal stress, and the temperature is cooled at a rate of 20°C / step to 30°C / step. Each temperature stage is maintained for 30min to 40min until it drops to room temperature.

[0034] The present invention provides a resin for electronic component packaging and a preparation method thereof, and the beneficial effects are as follows:

[0035] 1. The molecular chain of 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 fracture of the material, thereby improving the tensile strength. Silicone itself has a certain thermal conductivity. The chemical bonds formed by silicon atoms and surrounding atoms can transfer heat and participate in the heat conduction process in the entire system. It has good insulation and helps to improve the volume resistivity of the material. The vinyl and Si-OH can undergo cross-linking reactions with other substances containing active groups to form chemical bonds at the interface and enhance the bonding force with other materials. The molecular chain of silicone has good flexibility. When the temperature changes, it can adapt to thermal expansion and contraction through its own structural adjustment, reduce the accumulation of internal stress, and thus improve the thermal cycle stability. The silicon-oxygen bond of silicone has a certain repulsive effect on water molecules, and its chemical stability is high, it is not easily eroded by water, and improves the moisture resistance of the material.

[0036] 2. After curing, epoxy resin forms a tight three-dimensional network structure, which can effectively resist the stretching of external forces, making the material less likely to deform and break when subjected to force, thereby significantly improving the tensile strength. The molecular structure is relatively regular, and the vibration of chemical bonds 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 freely moving charge carriers, which can effectively prevent the passage of current and greatly improve the volume resistivity. The epoxy groups in its molecules have strong reactivity and can react chemically with the active groups on the surfaces of various materials to form strong chemical bonds, thereby providing excellent bonding strength. The cross-linked three-dimensional network structure has high rigidity and stability, can maintain the integrity of the structure during the thermal cycle, reduce structural damage caused by temperature changes, and improve thermal cycle stability. The dense cross-linked structure can effectively block the penetration of water molecules, reduce the water absorption rate of the material, and improve moisture resistance. In addition, the hydrogenated epoxy resin of bisphenol F type has low viscosity, and the viscosity of the resin matrix prepolymer prepared is less than 800cP, has good filling properties, and is easy to discharge bubbles.

[0037] 3. Polyimide is formed after imidization of polyamic acid. Polyimide has a highly conjugated molecular structure. There are strong interactions between molecular chains, including hydrogen bonds and π-π interactions. These forces give the material a high tensile strength. The distribution of electron clouds in the conjugated structure is conducive to heat transfer, and the orderly arrangement of molecular chains also contributes to heat conduction, improving the thermal conductivity of the material. The lack of conductive ions and free electrons in polyimide molecules has good insulation properties and can improve volume resistivity. Groups such as carboxyl and amino groups in polyamic acid molecules can react chemically with active groups on the surface of other materials or form hydrogen bonds to enhance adhesion. The high temperature resistance and stable molecular structure of polyimide enable it to maintain relatively stable performance during thermal cycling, improving the thermal cycling stability of the material.

[0038] 4. Although silver nanowires have high strength, they are prone to slippage in composite materials. The boron nitride shell has high hardness and is tightly combined with the silver nanowires, which can limit the movement of the silver nanowires, allowing the silver nanowires to work better together when subjected to force and jointly bear external forces, thereby improving the tensile strength of the material. Silver nanowires are excellent thermal conductors, but in composite materials, the interfacial thermal resistance between them and the surrounding medium will affect the thermal conduction efficiency. Boron nitride also has high thermal conductivity, and the interface formed with silver nanowires can effectively transfer heat. The two work together to form an efficient heat conduction channel, greatly improving the thermal conductivity of the material. Silver nanowires have good electrical conductivity. If they are in direct contact with each other in a composite material, a conductive path will be formed, reducing the insulation performance of the material. Boron nitride, as an insulating material, wraps up the silver nanowires, effectively isolating the conductive path between the 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 react chemically or form physical adsorption with the active ingredients in the resin matrix, enhancing the interfacial bonding force between the core-shell structure filler and the resin matrix, and improving the bonding strength. There is a certain difference in the thermal expansion coefficients of silver nanowires and boron nitride, but when the two are combined, they can restrain each other during the thermal cycle process, reducing structural deformation and damage caused by thermal expansion and contraction. At the same time, the high stability of boron nitride can also protect the 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 block moisture from contacting silver nanowires, preventing the silver nanowires from being corroded by moisture, thereby improving the moisture resistance of the material.

[0039] The ethoxy groups in the γ-aminopropyltriethoxysilane molecules form silanol groups (Si-OH) after hydrolysis. These silanol groups can undergo condensation reactions with the hydroxyl groups on the surface of the boron nitride shell, and organic groups containing amino groups are grafted onto the surface of the core-shell structure filler. The amino group has strong reactivity and can react chemically with the active groups in the resin matrix, including the epoxy groups in the epoxy resin, thereby forming a chemical bond between the filler and the matrix, and enhancing the bonding force between the two. When the material is subjected to tensile force, this chemical bond can effectively transfer stress, so that the filler and the matrix can cooperate to resist external forces and improve the tensile strength of the material. After modification with γ-aminopropyltriethoxysilane, 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 interfacial thermal resistance and improving the thermal conductivity of the material. γ-aminopropyltriethoxysilane itself is not conductive, and after being grafted to the surface of the core-shell structure filler, no conductive impurities are introduced. On the contrary, by enhancing the bonding force between the filler and the matrix, the leakage channel caused by interface defects is reduced, which helps to maintain and improve the volume resistivity of the material. In addition to chemically reacting with the resin matrix to form chemical bonds, the organic layer formed on the filler surface after γ-aminopropyltriethoxysilane grafting can also produce physical entanglement and van der Waals force with the resin matrix. These various forms of interaction jointly enhance the bonding strength between the filler and the matrix, making it difficult for the filler to fall off from the matrix when the material is subjected to external force. The enhanced interfacial bonding force after modification with γ-aminopropyltriethoxysilane 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, which can buffer thermal stress to a certain extent and improve the thermal cycling stability of the material. The amino group in γ-aminopropyltriethoxysilane can interact with water molecules to form weak interactions such as hydrogen bonds, thereby fixing some water molecules on the surface of the filler and reducing the penetration of water molecules into the material. In addition, the grafted organic layer can also block the intrusion of water to a certain extent, improving the moisture resistance of the material.

[0040] The silanol groups formed after the hydrolysis of perfluorooctyl triethoxysilane undergo further condensation reaction with the surface of the core-shell structure filler grafted with γ-aminopropyl triethoxysilane, and fluorine-containing organic groups are introduced on the surface of the filler. The 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, which further enhance the bonding force between the filler and the matrix, so that the material can better synergistically deform when subjected to tensile force, and improve the tensile strength. The introduction of perfluorooctyl triethoxysilane will not affect the thermal conductivity of silver nanowires and boron nitride itself. On the contrary, because it further improves the interfacial affinity between the filler and the matrix, the 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. The perfluorooctyl group has a strong electronegativity, can effectively prevent the movement of electrons, and has good insulation properties. After it is grafted onto the surface of the core-shell structure filler, the insulation performance of the filler is 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 perfluorooctyl triethoxysilane with the filler surface and its interaction with the resin matrix form a tighter bond between the filler and the matrix. The presence of fluorinated groups increases the interaction force between molecules, including not only chemical bonds, but also stronger van der Waals forces and possible hydrogen bonds, thereby significantly improving the bonding strength. The fluorinated groups have high chemical and thermal stability. During the thermal cycle, they can stabilize the structure of the filler surface and reduce the surface structure damage caused by temperature changes. At the same time, the enhanced interfacial bonding force can better resist thermal stress, maintain a close bond between the filler and the matrix, and improve the thermal cycle stability of the material. Perfluorooctyl has extremely strong hydrophobicity and can form a hydrophobic layer on the filler surface, effectively preventing the adsorption and penetration of moisture. It is difficult for moisture to contact the inside of the filler and the resin matrix, thereby improving the moisture resistance of the material and reducing the degradation of material performance caused by moisture intrusion.

[0041] 5. During the prepolymerization of the resin matrix, the active groups in the polydimethylsiloxane alcohol-methylsilanol-silicate crosslinked polymer undergo crosslinking reactions with silicone prepolymers, epoxy resins, etc. to form a complex semi-interpenetrating network structure. This network structure can connect different polymer molecules together, increasing the interaction force between molecules and the integrity of the material. When the material is subjected to tensile force, the network structure can evenly disperse the stress and avoid stress concentration in local areas, thereby improving the tensile strength of the material. The silicon-oxygen bonds in its molecular structure have a certain thermal conductivity. In the semi-interpenetrating network structure formed, it can synergize with other components with thermal conductivity (including silicone prepolymers, epoxy resins, etc.) to participate in the thermal conduction process. At the same time, due to its participation in the crosslinking reaction, the structure of the entire system is more uniform, reducing the increase in thermal resistance caused by structural inhomogeneity, which is beneficial to improving the thermal conductivity of the material. The polydimethylsiloxane alcohol-methylsilanol-silicate crosslinked polymer itself is a polymer with good insulation properties, and there are no freely moving conductive ions or electrons in its molecules. After forming a semi-interpenetrating network structure with other components, the gaps in the system are further filled, the conductive channels are reduced, and the volume resistivity of the material is improved. Through the cross-linking reaction, the polydimethylsiloxane alcohol-methylsilanol-silicate cross-linked polymer forms chemical bonds and physical entanglements between different polymer molecules. This effect enhances the interfacial bonding force between different components, so that the material can be better bonded together when in contact with other materials, thereby improving the bonding strength. The polydimethylsiloxane alcohol-methylsilanol-silicate cross-linked polymer has good flexibility and thermal stability. During the thermal cycle process, its flexibility can buffer the internal thermal stress of the material caused by temperature changes and reduce the structural damage of the material 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 bonds between the silicon atoms and oxygen atoms in the siloxane structure have a certain repulsive effect on water molecules, and the network structure formed by the polydimethylsiloxane alcohol-methylsilanol-silicate cross-linked polymer can block the penetration of water. When the material comes into contact with moisture, it can effectively prevent moisture from entering the interior of the material, reduce the water absorption rate of the material, and improve the moisture resistance of the material.

[0042] 6. Step-by-step composite curing and encapsulation: Add the directional filler composite to the resin matrix prepolymer for shear mixing, so that the directional filler is evenly dispersed in the resin matrix, and the two are closely combined. During the curing process, the epoxy resin ring-opening reaction, the imidization of the polyimide, and the condensation reaction of the silicone are carried out in sequence, forming a highly cross-linked complex structure. This structure enhances the intermolecular force inside the material, and when subjected to tensile force, it can effectively resist deformation and fracture, improve tensile strength, and other comprehensive properties. DETAILED DESCRIPTION

[0043] The present invention is further described below in conjunction with specific implementation cases, but the present invention is not limited to these embodiments.

[0044] Example 1

[0045] A resin for electronic component packaging, the resin comprises the following raw materials in parts by mass: 45 parts of epoxy resin, 25 parts of organosilicon prepolymer, 15 parts of polyamic acid solution, 18 parts of modified core-shell structure filler, 1.5 parts of polydimethylsiloxane alcohol-methylsilanol-silicate crosslinked polymer and 2 parts of silane coupling agent. Among them, 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 core of the core-shell structure filler is silver nanowire; and the shell of the core-shell structure filler is boron nitride. The organosilicon prepolymer is the main agent part of component A of Sylgard 184. The organosilicon prepolymer is an organosilicon prepolymer containing vinyl and Si-OH, with a vinyl content of 6wt% and a Si-OH content of 4wt%. The epoxy resin is a hydrogenated epoxy resin, bisphenol F type. The solid content of the polyamic acid solution is 25%, and the solvent is N-methylpyrrolidone. The silane coupling agent is silane coupling agent KH-792.

[0046] In the above-mentioned 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 4 nm to obtain a core-shell structure filler; the process parameters of the chemical vapor deposition method are: reaction temperature 1050°C, reaction gas is diborane and ammonia, the volume ratio is borane: ammonia = 1:2.2, the pressure is 8 Pa, and each time is 40 minutes.

[0047] In the modified core-shell structure filler, the surface modification method of the modified core-shell structure filler comprises the following steps:

[0048] N1: Mix γ-aminopropyltriethoxysilane: anhydrous ethanol: 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 300 r / min for 2.5 h at room temperature to fully hydrolyze the γ-aminopropyltriethoxysilane to form a hydrolysis product containing a silanol group Si-OH, which is counted as material A;

[0049] N2: Mix perfluorooctyltriethoxysilane: anhydrous ethanol: 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 room temperature at a speed of 300 r / min for 3.5 h to complete the hydrolysis of perfluorooctyltriethoxysilane to obtain material B;

[0050] N3: According to the 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 at 45kHz for 18min until uniform, and then stirred at 350r / min for 4h in a water bath at 65℃ to make the hydrolysis product of γ-aminopropyltriethoxysilane condense with the hydroxyl group on the surface of boron nitride to achieve the grafting of γ-aminopropyltriethoxysilane on the surface of the core-shell structure filler; centrifuge at 9000r / min for 15min, separate the upper liquid, and obtain solid product A, which is washed with anhydrous ethanol for 4 times to remove unreacted γ-aminopropyltriethoxysilane and impurities; then the solid product A and anhydrous ethanol are redispersed in anhydrous ethanol at a mass ratio of 1.2:9, and 45k Hz ultrasonic dispersion for 18 min until uniform; then, material B was added according to the mass ratio of solid product A: material B = 1.2:15, and the mixture was stirred and reacted at 350 r / min for 4 h in a 62°C water bath to allow the hydrolyzate of perfluorooctyltriethoxysilane to undergo further condensation reaction with the filler surface grafted with γ-aminopropyltriethoxysilane; centrifuged at 9000 r / min for 15 min, and the upper layer liquid was separated to obtain solid product B, which was washed alternately with anhydrous ethanol and deionized water for a total of 4 times (anhydrous ethanol 2 times + deionized water 2 times) to completely remove unreacted perfluorooctyltriethoxysilane and other impurities, and then the solid product B was vacuum dried at 55°C for 20 h to constant weight to obtain a modified core-shell structure filler.

[0051] The above-mentioned 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 4.5L / min, add the silicone prepolymer, polydimethylsiloxane alcohol-methylsilanol-silicate crosslinked polymer, and epoxy resin into the reaction kettle according to the mass fraction, and then add 0.5wt% of the total mass of tetrabutyl titanate catalyst, and stir at 123°C and 220r / min for 2.5h to form a semi-interpenetrating network structure; after the reaction, cool the system to 55°C, add the polyamic acid solution, and ultrasonically disperse at 220W power for 40min until uniform, to obtain a resin matrix prepolymer;

[0054] S2, packing oriented assembly:

[0055] The modified core-shell structure filler and the silane coupling agent were added to ethanol 2.5 times the total mass of the two by weight, and ball-milled at a speed of 250 r / min for 2 hours, with a ball-to-material mass ratio of 6:1.3. After ball-milling for 2 hours, a ball-milled material was obtained; the ball-milled material was transferred to an electric field induction device, an electric field strength of 520 V / cm was applied, and the induction time was 35 min to achieve axial oriented arrangement of silver nanowires, and freeze-dried to obtain a loosely stacked oriented filler composite;

[0056] S3, step-by-step composite curing package:

[0057] S3.1: Add the directional filler composite to the resin matrix prepolymer and shear mix. The parameters are: temperature 52°C, vacuum degree 6Pa, shear rate 1100s -1 , time 35min, to obtain a mixed material, at which the viscosity of the mixed material is lower than 800cP, the product before electronic component packaging;

[0058] S3.2: Pour the mixed material into the packaging mold until it reaches 1 / 2 of the height of the mold, place the electronic components, continue to pour the mixed material until the electronic components are covered, expel the bubbles, and perform programmed temperature curing. First, cure at 85°C for 2.5 hours to allow the epoxy resin to ring-open. Then, heat to 185°C at a heating rate of 4°C / min and cure for 3.5 hours to achieve imidization of polyimide. Finally, heat to 215°C at a heating rate of 3°C / min and cure for 1 hour to complete the condensation reaction of silicone. Use a step-by-step cooling method to eliminate internal stress. Cool at a rate of 25°C / step, maintain each temperature stage for 35 minutes, cool to room temperature, complete the packaging of electronic components, and obtain the encapsulated resin.

[0059] Example 2

[0060] A resin for electronic component packaging, the resin comprises the following raw materials in parts by mass: 40 parts of epoxy resin, 20 parts of organosilicon prepolymer, 10 parts of polyamic 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 using γ-aminopropyl triethoxysilane and perfluorooctyl triethoxysilane; the core of the core-shell structure filler is silver nanowire; and the shell of the core-shell structure filler is boron nitride. The organosilicon prepolymer is the main agent part of component A of Sylgard 184. The organosilicon prepolymer is an organosilicon prepolymer containing vinyl and Si-OH, with a vinyl content of 5wt% and a Si-OH content of 3wt%. The epoxy resin is a hydrogenated epoxy resin, bisphenol F type. The solid content of the polyamic acid solution is 20%, and the solvent is N-methylpyrrolidone. The silane coupling agent is silane coupling agent KH-792.

[0061] 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, 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°C, reaction gas is diborane and ammonia, the volume ratio is borane: ammonia = 1:1.5, and the pressure is 5Pa.

[0062] In the modified core-shell structure filler, the surface modification method of the modified core-shell structure filler comprises the following steps:

[0063] N1: γ-aminopropyltriethoxysilane: anhydrous ethanol: deionized water = 1:5:1 by volume, mixed, adjusted to pH 4 with hydrochloric acid, stirred at 200 r / min for 2 h at room temperature to fully hydrolyze γ-aminopropyltriethoxysilane to form a hydrolysis product containing silanol group Si-OH, which is counted as material A;

[0064] N2: Mix perfluorooctyltriethoxysilane: anhydrous ethanol: deionized water in a volume ratio of 1:8:1, adjust the pH value to 4 with hydrochloric acid, and stir at 200 r / min for 3 h at room temperature to complete the hydrolysis of perfluorooctyltriethoxysilane to obtain material B;

[0065] N3: According to the mass ratio, core-shell structure filler: material A = 1:15, the core-shell structure filler is added to material A, and ultrasonic dispersion is carried out at 40kHz for 15min until uniform, and then stirred at 300r / min for 3h in a water bath at 60℃ to make the hydrolysis product of γ-aminopropyltriethoxysilane condense with the hydroxyl group on the surface of boron nitride to achieve the grafting of γ-aminopropyltriethoxysilane on the surface of the core-shell structure filler; centrifuge at 8000r / min for 10min, separate the upper liquid, and obtain solid product A, which is washed with anhydrous ethanol for 3 times to remove unreacted γ-aminopropyltriethoxysilane and impurities; then the solid product A and anhydrous ethanol are redispersed in anhydrous ethanol at a mass ratio of 1:8, and 40k Hz ultrasonic dispersion for 15 min until uniform; then, material B was added according to the mass ratio of solid product A: material B = 1:10, and the mixture was stirred and reacted at 300 r / min for 3 h in a 60°C water bath to allow the hydrolyzate of perfluorooctyltriethoxysilane to undergo further condensation reaction with the filler surface grafted with γ-aminopropyltriethoxysilane; centrifuged at 8000 r / min for 10 min, and the upper layer liquid was separated to obtain solid product B, which was washed alternately with anhydrous ethanol and deionized water for a total of 4 times (anhydrous ethanol 2 times + deionized water 2 times) to completely remove unreacted perfluorooctyltriethoxysilane and other impurities, and then the solid product B was vacuum dried at 50°C for 12 h to constant weight to obtain a modified core-shell structure filler.

[0066] The above-mentioned method for preparing the resin for electronic component packaging comprises the following steps:

[0067] S1, resin matrix prepolymerization:

[0068] Under the protection of nitrogen at a flow rate of 4 L / min, add the silicone prepolymer, polydimethylsiloxane alcohol-methylsilanol-silicate crosslinked polymer, and epoxy resin into the reaction kettle according to the mass fraction, and then add 0.4wt% of the total mass of tetrabutyl titanate catalyst, and stir at 120°C and 200r / min for 2h to form a semi-interpenetrating network structure; after the reaction, cool the system to 50°C, add the polyamic acid solution, and perform ultrasonic dispersion at 200W power for 30min until uniform, to obtain a resin matrix prepolymer;

[0069] S2, packing oriented assembly:

[0070] The modified core-shell structure filler and the silane coupling agent were added to ethanol twice the total mass of the two by weight, and ball-milled 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-milled material was obtained; the ball-milled material was transferred to an electric field induction device, an electric field strength of 500 V / cm was applied, and the induction time was 30 min to achieve axial directional arrangement of silver nanowires, and freeze-dried to obtain a loosely stacked directional filler composite;

[0071] S3, step-by-step composite curing package:

[0072] S3.1: Add the directional filler composite to the resin matrix prepolymer and shear mix. The parameters are: temperature 50°C, vacuum degree 3Pa, shear rate 1000s -1 , time 30min, to obtain a mixed material, at which the viscosity of the mixed material is lower than 800cP, the product before electronic component packaging;

[0073] S3.2: Pour the mixed material into the packaging mold until it reaches 2 / 3 of the height of the mold, place the electronic components, continue to pour the mixed material until the electronic components are covered, expel the bubbles, and perform programmed temperature curing. First, cure at 80°C for 2 hours to make the epoxy resin ring-opening reaction, then heat to 180°C at a heating rate of 3°C / min and cure for 3 hours to achieve imidization of polyimide. Finally, heat to 210°C at a heating rate of 2°C / min and cure for 1 hour to complete the condensation reaction of silicone. Use a step-by-step cooling method to eliminate internal stress. Cool at a rate of 20°C / step, maintain each temperature stage for 30 minutes, cool to room temperature, complete the electronic component packaging, and obtain the encapsulated resin.

[0074] Example 3

[0075] A resin for electronic component packaging, the resin comprises the following raw materials in parts by mass: 40 parts of epoxy resin, 30 parts of organosilicon prepolymer, 20 parts of polyamic acid solution, 15 parts of modified core-shell structure filler, 2 parts 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 using γ-aminopropyl triethoxysilane and perfluorooctyl triethoxysilane; the core of the core-shell structure filler is silver nanowire; and the shell of the core-shell structure filler is boron nitride. The organosilicon prepolymer is the main agent part of component A of Sylgard 184. The organosilicon prepolymer is an organosilicon prepolymer containing vinyl and Si-OH, with a vinyl content of 8wt% and a Si-OH content of 3wt%. The epoxy resin is a hydrogenated epoxy resin, bisphenol F type. The solid content of the polyamic acid solution is 30%, and the solvent is N-methylpyrrolidone. The silane coupling agent is silane coupling agent KH-792.

[0076] 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, 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 1100°C, reaction gas is diborane and ammonia, the volume ratio is borane: ammonia = 1:1.5, and the pressure is 10Pa.

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

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

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

[0080] N3: According to the 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 at 40kHz for 15min until uniform, and then stirred at 300r / min for 3h in a water bath at 70℃ to make the hydrolysis product of γ-aminopropyltriethoxysilane condense with the hydroxyl group on the surface of boron nitride to achieve the grafting of γ-aminopropyltriethoxysilane on the surface of the core-shell structure filler; centrifuge at 8000r / min for 10min, separate the upper liquid, and obtain solid product A, which is washed with anhydrous ethanol for 3 times to remove unreacted γ-aminopropyltriethoxysilane and impurities; then the solid product A and anhydrous ethanol are redispersed in anhydrous ethanol at a mass ratio of 1.5:8, and 40 kHz ultrasonic dispersion for 20 min until uniform; then, material B was added according to the mass ratio of solid product A: material B = 1:15, and the mixture was stirred and reacted at 400 r / min for 3 h in a 65°C water bath to allow the hydrolyzate of perfluorooctyltriethoxysilane to undergo further condensation reaction with the filler surface grafted with γ-aminopropyltriethoxysilane; centrifuged at 8000 r / min for 20 min, and the upper layer liquid was separated to obtain a solid product B, which was washed alternately with anhydrous ethanol and deionized water for a total of 6 times (anhydrous ethanol 3 times + deionized water 3 times) to completely remove unreacted perfluorooctyltriethoxysilane and other impurities, and then the solid product B was vacuum dried at 60°C for 18 h to constant weight to obtain a modified core-shell structure filler.

[0081] The above-mentioned 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, add the silicone prepolymer, polydimethylsiloxane alcohol-methylsilanol-silicate crosslinked polymer, and epoxy resin into the reaction kettle according to the mass fraction, and then add 0.4wt% of the total mass of tetrabutyl titanate catalyst, and stir and react at 125°C and 200r / min for 3h to form a semi-interpenetrating network structure; after the reaction, cool the system to 50°C, add the polyamic acid solution, and ultrasonically disperse at 200W power for 30min until uniform, to obtain a resin matrix prepolymer;

[0084] S2, packing oriented assembly:

[0085] The modified core-shell structure filler and the silane coupling agent were added to ethanol 3 times the total mass of the two by weight, and ball-milled at a speed of 200 r / min for 2.5 h, with a ball-to-material mass ratio of 6:1. After ball-milling for 2 h, a ball-milled material was obtained; the ball-milled 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 40 min to achieve axial directional arrangement of silver nanowires, and freeze-dried to obtain a loosely stacked directional filler composite;

[0086] S3, step-by-step composite curing package:

[0087] S3.1: Add the directional filler composite to the resin matrix prepolymer and shear mix. The parameters are: temperature 55°C, vacuum degree 5Pa, shear rate 1000s -1 , time 30min, to obtain a mixed material, at which the viscosity of the mixed material is lower than 800cP, the product before electronic component packaging;

[0088] S3.2: Pour the mixed material into the packaging mold until it reaches 1 / 2 of the height of the mold, place the electronic components, continue to pour the mixed material until the electronic components are covered, expel the bubbles, and perform programmed temperature curing. First, cure at 90°C for 3 hours to make the epoxy resin ring-opening reaction, then heat to 180°C at a heating rate of 5°C / min and cure for 3 hours to achieve imidization of polyimide. Finally, heat to 220°C at a heating rate of 3°C / min and cure for 1 hour to complete the condensation reaction of silicone. Use a step-by-step cooling method to eliminate internal stress. Cool at a rate of 30°C / step, maintain each temperature stage for 30 minutes, cool to room temperature, complete the packaging of electronic components, and obtain the encapsulated resin.

[0089] Example 4

[0090] A resin for electronic component packaging, the resin comprises the following raw materials in parts by mass: 50 parts of epoxy resin, 30 parts of organosilicon prepolymer, 20 parts of polyamic 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. Among them, 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 core of the core-shell structure filler is silver nanowire; and the shell of the core-shell structure filler is boron nitride. The organosilicon prepolymer is the main agent part of component A of Sylgard 184. The organosilicon prepolymer is an organosilicon prepolymer containing vinyl and Si-OH, with a vinyl content of 8wt% and a Si-OH content of 5wt%. The epoxy resin is a hydrogenated epoxy resin, bisphenol F type. The solid content of the polyamic acid solution is 30%, and the solvent is N-methylpyrrolidone. The silane coupling agent is silane coupling agent KH-792.

[0091] In the above-mentioned 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°C, reaction gas is diborane and ammonia, the volume ratio is borane: ammonia = 1:3, and the pressure is 10Pa.

[0092] In the modified core-shell structure filler, the surface modification method of the modified core-shell structure filler comprises the following steps:

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

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

[0095] N3: According to the mass ratio, core-shell structure filler: material A = 3:20, the core-shell structure filler is added to material A, and ultrasonic dispersion is carried out at 50kHz for 20min until uniform, and then stirred at 400r / min for 5h in a water bath at 70℃ to make the hydrolysis product of γ-aminopropyltriethoxysilane condense with the hydroxyl group on the surface of boron nitride to achieve the grafting of γ-aminopropyltriethoxysilane on the surface of the core-shell structure filler; centrifuge at 10000r / min for 20min, separate the upper liquid, obtain solid product A, wash with anhydrous ethanol 5 times, remove unreacted γ-aminopropyltriethoxysilane and impurities; then the solid product A and anhydrous ethanol are re-dispersed in anhydrous ethanol at a mass ratio of 1.5:10, and ultrasonic dispersion is carried out at 50kHz for 20min until uniform; then according to the mass ratio, solid product A: material B = 1.5:20, add material B, stir and react at 400r / min for 5h in a water bath at 65℃ to make perfluorooctyl triethoxy The hydrolysis product of the perfluorooctyltriethoxysilane undergoes further condensation reaction with the filler surface grafted with γ-aminopropyltriethoxysilane; the mixture is centrifuged at 10000 r / min for 20 min, the supernatant is separated to obtain a solid product B, which is washed alternately with anhydrous ethanol and deionized water for a total of 6 times (anhydrous ethanol 3 times + deionized water 3 times) to completely remove unreacted perfluorooctyltriethoxysilane and other impurities, and then the solid product B is vacuum dried at 60°C for 24 h to constant weight to obtain a modified core-shell structure filler.

[0096] The above-mentioned method for preparing the resin for electronic component packaging comprises the following steps:

[0097] S1, resin matrix prepolymerization:

[0098] Under the protection of nitrogen at a flow rate of 5 L / min, add the silicone prepolymer, polydimethylsiloxane alcohol-methylsilanol-silicate crosslinked polymer, and epoxy resin into the reaction kettle according to the mass fraction, and then add 0.6wt% of the total mass of tetrabutyl titanate catalyst, and stir at 125°C and 250r / min for 3h to form a semi-interpenetrating network structure; after the reaction, cool the system to 60°C, add the polyamic acid solution, and ultrasonically disperse at 250W power for 50min until uniform to obtain a resin matrix prepolymer;

[0099] S2, packing oriented assembly:

[0100] The modified core-shell structure filler and the silane coupling agent were added to ethanol three times the total mass of the two by weight, and ball-milled at a speed of 300 r / min for 2.5 hours, with a ball-to-material mass ratio of 8:1.5. After ball-milling for 2.5 hours, a ball-milled material was obtained; the ball-milled material was transferred to an electric field induction device, an electric field strength of 550 V / cm was applied, and the induction time was 40 minutes to achieve axial oriented arrangement of silver nanowires, and freeze-dried to obtain a loosely stacked oriented filler composite;

[0101] S3, step-by-step composite curing package:

[0102] S3.1: Add the directional filler composite to the resin matrix prepolymer and shear mix. The parameters are: temperature 55°C, vacuum degree 10Pa, shear rate 1200s -1 , time 40min, to obtain a mixed material, at which the viscosity of the mixed material is lower than 800cP, the product before electronic component packaging;

[0103] S3.2: Pour the mixed material into the packaging mold until it reaches 2 / 3 of the height of the mold, place the electronic components, continue to pour the mixed material until the electronic components are covered, expel the bubbles, and perform programmed temperature curing. First, cure at 90°C for 3 hours to make the epoxy resin ring-opening reaction, then heat to 190°C at a heating rate of 5°C / min and cure for 4 hours to achieve imidization of polyimide. Finally, heat to 220°C at a heating rate of 3°C / min and cure for 1.5 hours to complete the condensation reaction of silicone. Use a step-by-step cooling method to eliminate internal stress. Cool at a rate of 30°C / step, maintain each temperature stage for 40 minutes, cool to room temperature, complete the packaging of electronic components, and obtain the encapsulated resin.

[0104] In the above embodiments: the silicone prepolymer comes from Dow Corning, the base glue part of model Sylgard 184, that is, the main agent of component A, has a low glass transition temperature, gives the resin good flexibility, and the coefficient of thermal expansion (CTE) is lower than 35ppm / ℃, which can effectively buffer the thermal stress of electronic components when working. The epoxy resin is a hydrogenated epoxy resin, bisphenol F type, from Guangzhou Dongzhen New Materials Co., Ltd., Mitsubishi JER Epoxy Resin 1750, with low viscosity characteristics, easy to mix with other ingredients and encapsulate operations, and its molecular structure gives the resin high moisture resistance. Polyamic acid comes from Wuhan Huaxiang Kejie Biotechnology Co., Ltd., model HXKJ98745. Silane coupling agent KH-792 comes from Dongguan Shanyi Plastic Co., Ltd. Polydimethylsiloxane alcohol-methylsilanol-silicate cross-linked polymer comes from Shenzhen Ruijit Biotechnology Co., Ltd., model RGT20623. Silver nanowires come from Nanjing Hongde Nanomaterials Co., Ltd., model 0475NW3W, D25-30nm. γ-Aminopropyltriethoxysilane comes from Shandong Moore Chemical Co., Ltd., with a molecular weight of 221.4. Perfluorooctyltriethoxysilane comes from Jiangsu Pules Biotechnology Co., Ltd. Tetrabutyl titanate catalyst comes from Shandong Linguan Fine Chemical Co., Ltd., with a purity of 99%.

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

[0106] Comparative Example 1

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

[0108] Comparative Example 2

[0109] During the modification process of the modified core-shell structure filler, no perfluorooctyltriethoxysilane was added; other parameters and methods were 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 the 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-mentioned embodiments and comparative examples were tested.

[0115] 1. Tensile strength: Use a universal material testing machine and test according to GB / T 1040.2 "Determination of tensile properties of plastics Part 2: Test conditions for molded and extruded plastics". The tensile strength test specimen (pure resin specimen, without electronic components) is installed on the fixture of the universal material testing machine. The initial spacing is adjusted to 50mm, so that the center line of the spline coincides with the center line of the fixture. The spline is stretched at a stretching speed of 5mm / min until it breaks. The maximum load F when the spline breaks is recorded, accurate to 0.1N. The cross-sectional area of ​​the spline is S, and the tensile strength σ = F / S, in MPa, and the result is rounded to two decimal places. The test results are shown in Table 1 below.

[0116] 2. Thermal conductivity: Using the laser flash method and a thermal constant analyzer, refer to ASTM E1461-13 "Standard test method for determination of thermal diffusivity of solids by laser flash method" to make a thermal conductivity test specimen (pure resin specimen, without electronic components). The specimen is placed in the sample cell of the thermal constant analyzer. In a helium atmosphere with a flow rate of 50mL / min, the temperature is raised from 25℃ to 150℃ at a heating rate of 10℃ / min. The thermal diffusion coefficient α is measured at each temperature point, and the thermal conductivity λ = α×ρ×C is calculated. p , ρ is the density (determined by the pycnometer method), C p is the specific heat capacity (measured by DSC). The test results are shown in Table 1 below.

[0117] 3. Volume resistivity: According to GB / T 1410 "Test Method for Volume Resistivity and Surface Resistivity of Solid Insulating Materials", use a high resistance meter. Make a resistivity test specimen (pure resin specimen, without electronic components), install the specimen on the high resistance meter, apply a 500V DC voltage to the sample, measure the resistance value R after 1 minute, and calculate the volume resistivity ρ v =R×S / d, S is the effective current cross-sectional area of ​​the electrode in contact with the sample, and d is the length of the sample in the current direction. The test results are shown in Table 1 below.

[0118] 4. Shear strength: Use an electronic universal testing machine and according to GB / T 7124 "Determination of tensile shear strength of adhesives". Prepare the shear strength test specimen (including electronic components) and install it on the shear fixture of the electronic universal testing machine. Apply shear force to the interface between the resin and the electronic components at a shear speed of 1mm / min until the resin and the electronic components separate. Record the maximum shear force F and calculate the shear strength τ=F / S, where S is the bonding area. The test results are shown in Table 1 below.

[0119] 5. Thermal cycle stability: Place the packaged electronic component specimens in a high and low temperature test chamber for thermal cycle testing. Refer to the thermal cycle test conditions in GJB 128A "Test Methods for Discrete Semiconductor Devices". The thermal cycle conditions are heating from -55°C to 125°C, the heating rate is 5°C / min, and keeping at 125°C for 30 minutes; then cooling from 125°C to -55°C, the cooling rate is 5°C / min, and keeping at -55°C for 30 minutes. This 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 defects such as cracks or voids. Record the structural changes of the package before and after the thermal cycle to 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. According to GB / T 2423.3 "Environmental testing Part 2: Test method Test Cab: Constant humidity test", set the temperature of the constant temperature and humidity chamber to 85°C and the relative humidity to 85%. Put the electronic components into the chamber and keep them for 1000 hours. After taking them out, use a multimeter to measure the electrical performance of the electronic components to check whether there is a short circuit or open circuit, etc., record the changes in the electrical performance of the electronic components before and after the humidity test, and evaluate their humidity resistance. The test results are shown in Table 1 below.

[0121] Table 1 Test results

[0122]

[0123]

[0124] It can be seen from the above results that the resins of Examples 1 to 4 have higher tensile strength, shear strength and resistivity, and at the same time have better thermal conductivity, better thermal cycle stability and moisture resistance, and longer service life.

[0125] The resin raw material of Comparative Example 1 does not contain polydimethylsiloxane alcohol-methylsilanol-silicate crosslinked polymer. The polymer can enhance the overall network structure of the resin through crosslinking in the system. In the absence of it, the intermolecular forces inside the resin are weak, and the movement of the molecular segments is relatively freer. During the stretching process, the molecular chains are prone to slippage and breakage. This crosslinked polymer helps to build a more continuous heat conduction channel. After its absence, the connection between the heat-conducting particles becomes poor and the heat conduction efficiency is reduced. During the thermal cycle, due to the unstable network structure, thermal stress cannot be effectively buffered, resulting in cracks. In the moisture resistance test, water molecules are more likely to invade the interior of the resin, destroying its electrical insulation properties and causing leakage.

[0126] Perfluorooctyl triethoxysilane is not added during 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 tighter. In the absence of it, there are more interface defects between the filler and the resin matrix, and the interface bonding force is insufficient. These defects easily become stress concentration points, causing premature damage to the material and reduced tensile strength. During the heat conduction process, the interfacial thermal resistance increases and the thermal conductivity decreases. During the thermal cycle and moisture resistance process, due to the weak interfacial bonding, moisture and thermal stress are more likely to cause interfacial debonding, resulting in more cracks, and obvious leakage.

[0127] The modified core-shell structure filler of comparative example 3 is not modified, and the core-shell structure filler is directly used instead. The interaction between the unmodified core-shell structure filler and the resin matrix is ​​mainly physical adsorption, and the binding force is far less than that of the filler after surface modification. This makes it easy for the filler and the matrix to slide relative to each other when the material is subjected to force, and the stress cannot be effectively transferred, and the tensile strength is greatly reduced. For heat conduction, due to the lack of effective interface connection, it is difficult to form an efficient heat conduction network, and the thermal conductivity is significantly reduced. The weak binding force causes the internal structure of the material to be easily damaged during thermal cycling and moisture resistance, resulting in serious cracking and short circuit phenomena.

[0128] The modified core-shell structure filler of Comparative Example 4 is replaced by silver nanowires. Silver nanowires are prone to agglomeration in the resin and have poor dispersibility. They cannot be evenly distributed like the modified core-shell structure filler and form an effective reinforcement and heat conduction network. Agglomerated silver nanowires not only fail to effectively enhance the mechanical properties of the material, but instead become the weak points inside the material, reducing the tensile strength. In terms of heat conduction, due to uneven dispersion, a continuous heat conduction path cannot be formed, and the thermal conductivity decreases. During the thermal cycle and moisture resistance process, the material performance is extremely poor, and severe damage and short circuits occur.

Claims

1. A resin for encapsulating electronic components, characterized in that: The resin includes the following raw materials in parts by mass: 40 to 50 parts of epoxy resin, 20 to 30 parts of silicone prepolymer, 10 to 20 parts of polyamic acid solution, 15 to 20 parts of modified core-shell structure filler, 1 to 2 parts of polydimethylsiloxane alcohol-methylsilanol-silicate crosslinked polymer and 1.5 to 3 parts of silane coupling agent.

2. The electronic component encapsulation resin according to claim 1, characterized in that: The organosilicon prepolymer is the main agent part of component A of Sylgard 184; the organosilicon prepolymer is an organosilicon prepolymer containing vinyl and Si-OH, with a vinyl content of 5wt% to 8wt% and a Si-OH content of 3wt% to 5wt%.

3. The electronic component encapsulation resin according to claim 1, characterized in that: The epoxy resin is hydrogenated epoxy resin, bisphenol F type; the solid content of the polyamic acid solution is 20% to 30%, and the solvent is N-methylpyrrolidone; the silane coupling agent is silane coupling agent KH-792.

4. The electronic component encapsulation resin according to claim 1, characterized in that: The modified core-shell structure filler is obtained by modifying the surface of the core-shell structure filler with γ-aminopropyltriethoxysilane and perfluorooctyltriethoxysilane; the core of the core-shell structure filler is silver nanowire; and the shell of the core-shell structure filler is boron nitride.

5. The electronic component encapsulation resin according to claim 4, characterized in that: 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 3nm to 5nm, so as to obtain a core-shell structure filler; the process parameters of the chemical vapor deposition method are: reaction temperature 1000°C to 1100°C, reaction gas is diborane and ammonia, the volume ratio is borane: ammonia = 1: (1.5 to 3), and the pressure is 5Pa to 10Pa.

6. The electronic component encapsulation resin according to claim 4, characterized in that: The surface modification method of the modified core-shell structure filler comprises the following steps: N1: Mix γ-aminopropyltriethoxysilane: anhydrous ethanol: deionized water in a volume ratio of (1-1.5): (5-6): (1-2), adjust the pH value to 4-5 with hydrochloric acid, and stir at room temperature to fully hydrolyze the γ-aminopropyltriethoxysilane to form a hydrolysis product containing a silanol group Si-OH, which is counted as material A; N2: Mix perfluorooctyltriethoxysilane: anhydrous ethanol: 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 to complete the hydrolysis of perfluorooctyltriethoxysilane, and 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, ultrasonically dispersed until uniform, then stirred in a water bath at 60°C to 70°C, centrifuged, separated the upper liquid to obtain solid product A, washed with anhydrous ethanol 3 to 5 times, then the solid product A and anhydrous ethanol are redispersed in anhydrous ethanol at a mass ratio of (1-1.5): (8-10), and ultrasonically dispersed until uniform; then according to the mass ratio, solid product A: material B = (1-1.5): (10-20), material B is added, stirred in a water bath at 60°C to 65°C, centrifuged, separated the upper liquid to obtain solid product B, washed alternately with anhydrous ethanol and deionized water for a total of 4 to 6 times, and then the solid product B is vacuum dried to constant weight to obtain a modified core-shell structure filler.

7. The electronic component encapsulation resin according to claim 6, characterized in that: In N1, the stirring speed is 200r / min~400r / min, and the stirring time is 2h~3h; in N2, the stirring speed is 200r / min~400r / min, and the stirring time is 3h~4h; in N3, the frequency of ultrasonic dispersion is 40kHz~50kHz, the time of ultrasonic dispersion is 15min~20min, the stirring speed is 300r / min~400r / min, the stirring time is 3h~5h, the centrifugal speed is 8000r / min~10000r / min, the centrifugal time is 10min~20min, the vacuum drying temperature is 50℃~60℃, and the vacuum drying time is 12h~24h.

8. A method for preparing an electronic component encapsulation resin, used for preparing the electronic component encapsulation resin according to claim 1, characterized in that: The preparation method comprises the following steps: S1, resin matrix prepolymerization: Under nitrogen protection, add the organosilicon prepolymer, polydimethylsiloxane alcohol-methylsilanol-silicate crosslinked polymer and epoxy resin into a reaction kettle according to the mass fraction, then add tetrabutyl titanate catalyst, and stir and react at 120°C to 125°C for 2h to 3h; after the reaction, cool the system to 50°C to 60°C, add the polyamic acid solution, and ultrasonically disperse until uniform to obtain a resin matrix prepolymer; S2, packing oriented assembly: The modified core-shell structure filler and the silane coupling agent are added to ethanol according to the mass fraction, and ball-milled to obtain a ball-milled material; the ball-milled material is transferred to an electric field induction device, and an electric field strength of 500V / cm to 550V / cm is applied for an induction time of 30min to 40min to achieve axial directional arrangement of the silver nanowires, and freeze-dried to obtain a loosely stacked directional filler composite; S3, step-by-step composite curing package: S3.1: adding the directional filler composite to the resin matrix prepolymer, shearing and mixing, to obtain a mixed material, wherein the viscosity of the mixed material is lower than 800 cP, and the product before electronic component packaging; S3.2: Pour the mixed material into the packaging mold until it reaches 1 / 2 to 2 / 3 of the height of the mold, place the electronic components, and continue to pour the mixed material until the electronic components are covered. Expel the bubbles and perform programmed temperature curing. First, cure at 80°C to 90°C for 2h to 3h, then heat to 180°C to 190°C and cure for 3h to 4h, and finally heat to 210°C to 220°C and cure for 1h to 1.5h. Cool to room temperature to complete the electronic component packaging and obtain the encapsulated resin.

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

10. The method for preparing a resin for electronic component encapsulation according to claim 8, characterized in that: In S3.1, the shear mixing parameters are: temperature 50°C to 55°C, vacuum degree 3Pa to 10Pa, shear rate 1000s -1 ~1200s -1 , time 30min~40min; in S3.2, the temperature is increased to 180℃~190℃ at a heating rate of 3℃ / min~5℃ / min, and the temperature is increased to 210℃~220℃ at a heating rate of 2℃ / min~3℃ / min. The cooling adopts a step-by-step cooling method to eliminate internal stress, and the temperature is reduced at a rate of 20℃ / step~30℃ / step. Each temperature stage is maintained for 30min~40min until it drops to room temperature.

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