Low-expansion moisture-resistant electronic component packaging resin adhesive and preparation method thereof

Abstract

The invention relates to a low-expansion moisture-resistant electronic component packaging resin adhesive and a preparation method thereof, and belongs to the technical field of high polymer materials. The resin adhesive comprises the following components: modified resin, phenyl methyl organic silicon resin, epoxy vinyl resin, a dynamic functional curing agent, a microencapsulated dicyandiamide curing agent, perfluorooctyltriethoxysilane, functional filler and the like; the modified resin is obtained by modifying hydrogenated bisphenol A epoxy resin with hydrogen-terminated polydimethylsiloxane and trimethylsiloxy silicate ester, adding a silane coupling agent and mixing; the dynamic function curing agent is obtained by reacting hexamethylenediamine and intermediate powder obtained by reacting 2, 3-dihydroxy benzaldehyde with pinacol borane; the functional filler comprises silicon dioxide and boron nitride which are subjected to surface treatment by a silane coupling agent. The low-expansion and high-moisture-resistance electronic component packaging resin adhesive is prepared from the components according to a specific ratio and a specific method, the components have a synergistic effect and play advantages, and the packaging reliability and the service life of an electronic component are guaranteed.

Description

TECHNICAL FIELD

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

[0002] In modern electronic industry, packaging technology of electronic components is crucial, which not only relates to the performance, reliability and service life of electronic components, but also affects the miniaturization, lightweight and high performance development of electronic products. As a key material for electronic component packaging, packaging resin plays an important role in protecting electronic components from external environment, providing mechanical support and electrical insulation. With the rapid development of electronic technology, the performance requirements of electronic component packaging resin are increasingly stringent.

[0003] The miniaturization trend of electronic devices leads to the continuous improvement of the integration of electronic components, the increase of the number of electronic components per unit area, and the smaller spacing between components. In this case, if the thermal expansion coefficient of the packaging resin does not match the electronic components, thermal stress will be generated at the interface due to the different expansion or shrinkage degrees of the two when the temperature changes. Under the long-term action of this thermal stress, cracking and debonding may occur between the components and the packaging resin, which will affect the performance and reliability of the electronic device. For example, in portable electronic devices such as mobile phones and tablet computers, the internal space is compact, and the low expansion performance of the packaging resin is extremely high to ensure that the electronic components can work stably under the temperature change environment in daily use.

[0004] In addition, electronic components are often affected by various complex environmental factors during use, among which moisture is an important destructive factor. Moisture can enter the packaging interior through diffusion and other ways, when the water contacts the metal pins, lines and other parts of the electronic components, it may cause electrochemical corrosion, leading to the damage of metal materials and the decline of electrical performance of electronic components. For some humidity-sensitive chips, such as integrated circuit chips, moisture may also cause the performance change of semiconductor materials inside the chip, affecting the normal operation of the chip. In some humid industrial environments or outdoor application scenarios, such as industrial automation equipment, outdoor monitoring cameras, etc., the moisture resistance performance of electronic component packaging resin is particularly critical.

[0005] Traditional encapsulation resins for electronic components have limitations in terms of coefficient of thermal expansion and moisture resistance. Some traditional encapsulation resins have a high coefficient of thermal expansion, making it difficult to meet the thermal expansion matching requirements of high-precision electronic components. Regarding moisture resistance, the protective performance of ordinary encapsulation resins gradually decreases under long-term humid environments, failing to provide durable and effective protection for electronic components. With the rapid development of emerging technologies such as communication, artificial intelligence, and the Internet of Things, higher demands are placed on the performance and stability of electronic components, urgently requiring the development of new encapsulation resin materials with low expansion and high moisture resistance. Summary of the Invention

[0006] To further improve the moisture resistance of resins and reduce the thermal expansion of electronic component resin encapsulation, this invention provides a low-expansion, moisture-resistant electronic component encapsulation resin and its preparation method. The resin utilizes modified resin, phenylmethyl silicone resin, epoxy vinyl resin, dynamic functional curing agent, microencapsulated dicyandiamide curing agent, perfluorooctyltriethoxysilane, and functional fillers, prepared according to a specific ratio and method, to produce an electronic component encapsulation resin with low expansion and high moisture resistance. The various raw materials work synergistically and leverage their advantages to ensure the reliability and lifespan of the electronic component encapsulation. The specific technical solution is as follows:

[0007] A low-expansion, moisture-resistant encapsulating resin for electronic components comprises the following raw materials in parts by weight: 35-40 parts modified resin, 10-15 parts phenylmethyl silicone resin, 12-18 parts epoxy vinyl resin, 5-8 parts dynamic functional curing agent, 8-12 parts microencapsulated dicyandiamide curing agent, 2-3 parts perfluorooctyltriethoxysilane ethanol solution, 40-45 parts functional filler, with the balance being solvent, and a viscosity of 6000 mPa·s to 8000 mPa·s;

[0008] The modified resin is a hydrogenated bisphenol A type epoxy resin modified by hydrogen-terminated polydimethylsiloxane and trimethylsiloxysilicate, and then mixed with silane coupling agent KH-560; the dynamic functional curing agent is an intermediate powder obtained by reacting 2,3-dihydroxybenzaldehyde and pinacol borane at a mass ratio of 1:(1~1.1), and then reacting the intermediate powder with hexamethylenediamine at a mass ratio of 1:(0.23~0.25); the mass ratio of the functional filler components is silicon dioxide:boron nitride = (5~6):(3~4); the silicon dioxide is pretreated with silane coupling agent KH-560; the boron nitride is pretreated with silane coupling agent KH-550.

[0009] The modified resin in the above-mentioned resin adhesive is prepared by mixing hydrogenated bisphenol A epoxy resin, hydrogen-terminated polydimethylsiloxane, and trimethylsiloxysilicate in a ratio of 100:(12-15):(3-4), stirring at 200-250 rpm under nitrogen protection and heating to 110-115°C, adding 0.03%-0.05% ethynylcyclohexanol by mass of hydrogen-terminated polydimethylsiloxane, stirring at 200-250 rpm for 5-10 minutes, adding 0.2%-0.3% chloroplatinic acid catalyst by mass of hydrogen-terminated polydimethylsiloxane, reacting for 2-3 hours, cooling to 50-60°C, adding 3%-5% silane coupling agent KH-560 by mass of hydrogen-terminated polydimethylsiloxane, stirring at 200-250 rpm for 30-40 minutes to obtain the modified resin.

[0010] The preparation method of the dynamic functional curing agent in the above resin adhesive includes: reacting 2,3-dihydroxybenzaldehyde:pinacol borane in a mass ratio of 1:(1-1.1) in THF solvent under nitrogen protection with stirring at room temperature for 2-3 hours; removing the THF solvent by vacuum distillation to obtain an intermediate powder; reacting the intermediate powder:hexamethylenediamine in anhydrous isopropanol solvent under nitrogen protection with stirring at 55-58°C for 1.5-2 hours; removing the anhydrous isopropanol solvent by rotary evaporation to obtain a dynamic functional curing agent with terminal amino groups.

[0011] In the above-mentioned method for preparing the dynamic functional curing agent, the amount of THF solvent is 6 to 8 times the total mass of 2,3-dihydroxybenzaldehyde and pinacol borane; the amount of anhydrous isopropanol solvent is 6 to 8 times the total mass of the intermediate powder and hexamethylenediamine; and the rotary evaporation is reduced pressure rotary evaporation at a temperature below 58°C.

[0012] The preparation method of microencapsulated dicyandiamide in the above-mentioned resin adhesive includes: dicyandiamide: gelatin: gum arabic: glutaraldehyde aqueous solution: deionized water in a mass ratio of 100:(10-15):(5-8):(3-5):(300-400); dissolving gelatin and gum arabic in deionized water at 55℃-60℃, adding 10wt%-12wt% acetic acid aqueous solution to adjust the pH to 4.0-4.5, cooling to 40℃-45℃, adding dicyandiamide with a particle size D50 of less than 5μm, and emulsifying at 40℃-45℃ and 7000rpm-8000rpm for 10-15 minutes to obtain an emulsion; stirring and cooling to 10℃-12℃, maintaining for 30-40 minutes, allowing the gelatin-gum arabic phase to separate and precipitate on the dicyandiamide surface and coat the dicyandiamide; and then using 0.05M-0.06M... Adjust the pH to 8.0–8.2 with Tris-HCl buffer. Add 18 wt%–20 wt% glutaraldehyde aqueous solution dropwise at a rate of 0.5 mL / min–1 mL / min at 25 °C–30 °C. Stir the reaction at 25 °C–30 °C for 2.5–3 h, then allow it to stand at 25 °C–30 °C for 1–1.5 h to mature. Filter the precipitate, wash it 3–4 times with 0.18 wt%–0.20 wt% glycine aqueous solution, freeze-dry it, and pass it through a 325–400 mesh sieve to obtain microencapsulated dicyandiamide.

[0013] In the above-mentioned resin adhesive, the D50 of silica is less than 5 μm; the method of surface pretreatment of silica with silane coupling agent KH-560 includes: mixing silane coupling agent KH-560: ethanol: deionized water in a mass ratio of 1:(40~50):(6~10), adjusting the pH to 4.5~5.0 with acetic acid, and stirring and hydrolyzing at 40℃~45℃ for 30min~40min; adding silica in a solid-liquid mass ratio of 1:(10~12), and ultrasonically dispersing at 40℃~45℃, 300W~350W, and 35kHz~40kHz for 20min~30min; removing ethanol by vacuum distillation, drying at 100℃~110℃ to constant weight, and passing through a 325-400 mesh sieve to obtain pretreated silica.

[0014] In the above resin adhesive, the D50 of boron nitride is less than 15 μm; the method of surface pretreatment of boron nitride with silane coupling agent KH-550 includes: mixing silane coupling agent KH-550: ethanol: deionized water in a mass ratio of 1:(24~26):(3~5), adjusting the pH to 4.5~5.0 with acetic acid, and stirring and hydrolyzing at 40℃~45℃ for 30min~40min; adding boron nitride in a solid-liquid mass ratio of 1:(8~10), and ultrasonically dispersing at 40℃~45℃, 300W~350W, and 35kHz~40kHz for 20min~30min; removing ethanol by vacuum distillation, drying at 100℃~110℃ to constant weight, and passing through a 325-400 mesh sieve to obtain pretreated boron nitride.

[0015] In the above resin adhesive, the perfluorooctyltriethoxysilane ethanol solution is prepared by diluting perfluorooctyltriethoxysilane with 2 to 2.5 times its mass of ethanol and stirring at room temperature at 200 to 250 rpm for 10 to 15 minutes.

[0016] In the above resin adhesive, the mass ratio of the solvent components is propylene glycol methyl ether acetate: cyclopentanone: acetone = 1:(0.5~0.7):(0.2~0.3).

[0017] The preparation method of the above-mentioned low-expansion, moisture-resistant electronic component encapsulating resin includes the following steps:

[0018] Add modified resin, phenylmethyl silicone resin, and epoxy vinyl resin to the solvent, and stir at 150 rpm to 200 rpm for 30 to 40 minutes. Then, add dynamic functional curing agent, microencapsulated dicyandiamide curing agent, trifluoropropyl polydimethylsiloxane, and perfluorooctyltriethoxysilane ethanol solution sequentially, and stir at 150 rpm to 200 rpm for 20 to 30 minutes. Add the functional filler in three equal portions sequentially. After each portion is added, stir at 200 rpm to 250 rpm for 10 to 15 minutes, pause for 5 to 8 minutes, and then add the next portion until all portions are added and mixed. While continuously stirring at 100 rpm to 150 rpm, adjust the viscosity to 6000 mPa·s to 8000 mPa·s with the solvent. Homogenize at high speed of 1500 rpm to 2500 rpm for 3 to 5 minutes, defoam under vacuum, allow to stand to defoam, and pass through a 100-120 mesh sieve to obtain the finished product.

[0019] In the above-mentioned method for preparing resin adhesive, the homogenizer is equipped with a cooling circulation system to ensure that the temperature is below 40°C; the entire preparation process is carried out at a temperature below 40°C; and the finished product is stored in a sealed container under nitrogen purging at an ambient temperature below 20°C, away from light.

[0020] The present invention provides a low-expansion, moisture-resistant electronic component encapsulating resin and its preparation method, the beneficial effects of which include:

[0021] I. Synergistic Improvement of Resin Structure and Performance: The modified resin is prepared by reacting hydrogenated bisphenol A epoxy resin, hydrogen-terminated polydimethylsiloxane, and trimethylsiloxysilicate. The siloxane segments, due to their unique molecular structure, possess an extremely low coefficient of thermal expansion. During temperature changes, their flexible segmental structure acts as a buffer, effectively cushioning the expansion and contraction of the molecular chains caused by thermal motion, greatly reducing volume expansion caused by temperature fluctuations and thermal stress, providing stable encapsulation protection for electronic components in complex temperature environments. Trimethylsiloxysilicate promotes cross-linking, increases the cross-linking density of the resin, and enhances the interaction forces between molecular chains. This makes it difficult for the molecular chains to undergo relative displacement during temperature changes, effectively suppressing expansion. Simultaneously, the dense network structure acts as a powerful barrier, significantly hindering the penetration of moisture molecules into the resin, greatly improving the resin's moisture resistance, and effectively preventing short circuits and corrosion of electronic components due to moisture erosion.

[0022] II. Precise Control of the Reaction Process: Adding an appropriate amount of ethinylcyclohexanol is a crucial step in the preparation of the modified resin. It precisely controls the activity of the chloroplatinic acid catalyst, thereby precisely controlling the rate of the hydrosilylation reaction between hydrogen-terminated polydimethylsiloxane and hydrogenated bisphenol A epoxy resin. This precise control effectively avoids overly vigorous or uneven reactions. If the reaction gets out of control, it can easily lead to uneven distribution of siloxane segments in the epoxy resin, resulting in excessive or insufficient cross-linking in certain areas. Ultimately, this broadens the molecular weight distribution of the modified resin, severely affecting its overall performance. The addition of ethinylcyclohexanol ensures that the siloxane segments are uniformly distributed in the epoxy resin matrix, forming a structurally stable and uniformly performing modified resin, laying a solid foundation for the stable performance of the subsequent encapsulating resin.

[0023] III. Synergistic Performance Optimization of Multi-Resin Compounds: The appropriate addition of suitable proportions of phenylmethyl silicone resin and epoxy vinyl resin can deeply optimize the cured cross-linking network structure. The phenyl side groups of phenylmethyl silicone resin possess a unique spatial structure, significantly increasing the molecular chain packing density, effectively blocking the diffusion path of water molecules and enhancing the resin's moisture resistance at the molecular level. Epoxy vinyl resin, with its unique functional group structure, endows the resin with excellent rapid curing, high-temperature aging resistance, and high insulation resistance. The synergistic effect of both compounds with the modified resin cleverly balances the rigidity and flexibility of the cured resin. This combination of rigidity and flexibility not only allows the resin to effectively resist thermal expansion under temperature changes but also absorbs energy through the deformation of flexible segments when subjected to external impacts, preventing cracking due to excessive rigidity and comprehensively improving the overall performance of the encapsulating resin.

[0024] IV. Intelligent Response of Dynamic Curing System: Dynamic functional curing agents contain dynamic covalent bonds such as acylhydrazone bonds and borate ester bonds. These special chemical bonds endow the resin adhesive with intelligent responsiveness. In a humid environment, when water molecules invade the resin, the dynamic covalent bonds can rapidly undergo a reversible exchange reaction, actively combining with water molecules and consuming them, acting as a "moisture consumption defense line" to effectively prevent further moisture diffusion and provide long-lasting moisture protection for electronic components. Simultaneously, under thermal stress, the dynamic covalent bonds can exert their unique reversible change characteristics, dissipating heat stress through a cracking-recombination process. This self-regulating mechanism can prevent cracking between the encapsulation resin and electronic components due to thermal stress accumulation, ensuring the long-term stable operation of electronic components. Microencapsulated dicyandiamide, through its special encapsulation structure, effectively avoids the problem of moisture absorption before curing, ensuring the stability of the curing agent's performance. The combined use of dynamic functional curing agents and microencapsulated dicyandiamide curing agents allows for precise control of the curing process and crosslinking density based on different environmental conditions and reaction processes. This achieves a perfect balance between rigidity and flexibility, minimizes stress concentration, and enhances the reliability and durability of the encapsulated resin.

[0025] V. Surface Modification of Fillers to Enhance Interfacial Properties: Pre-treating silica and boron nitride with silane coupling agents is an important method to improve the performance of resin adhesives. Silane coupling agent molecules have a special amphiphilic structure; one end can chemically react with the active groups on the filler surface to form a strong chemical bond; the other end can interact with the functional groups in the resin matrix, achieving chemical bonding between the filler and the resin matrix. This strong interfacial bonding greatly reduces the interfacial voids between the filler and the resin matrix, improving the homogeneity of the system. In practical applications, it can effectively reduce stress concentration points, avoiding problems such as resin swelling and increased water absorption caused by stress concentration. Simultaneously, good interfacial bonding can also promote the uniform dispersion of fillers in the resin matrix, fully utilizing the reinforcing and modifying effects of the filler, and further improving the mechanical properties, thermal properties, and moisture resistance of the resin adhesive.

[0026] VI. Enhanced Protection with a Hydrophobic Surface Layer: When perfluorooctyltriethoxysilane is diluted with ethanol, its molecular morphology and surface properties change, significantly improving its compatibility with resins. During resin curing, perfluorooctyltriethoxysilane migrates to the resin surface, forming a dense hydrophobic layer due to the low surface energy of its fluorinated groups. This hydrophobic layer, similar to the nanostructure of a lotus leaf, effectively repels water molecules, making it difficult for water droplets to adhere to and penetrate the resin surface, further enhancing the resin's moisture resistance. Simultaneously, the hydrophobic layer reduces contact between dust, contaminants, and the resin surface, minimizing their impact on resin performance and extending the lifespan of electronic component packaging.

[0027] VII. In the preparation of the resin adhesive, a step-by-step addition of raw materials is adopted. First, a portion of the solvent base is added, followed by the modified resin, phenylmethyl silicone resin, and epoxy vinyl resin in sequence. This gradual addition order facilitates the full dispersion and dissolution of the resin raw materials in the solvent. Subsequent addition of other components such as the dynamic functional curing agent and microencapsulated dicyandiamide curing agent avoids the problems of agglomeration and uneven mixing caused by the simultaneous addition of multiple raw materials. In particular, the functional filler is added in three equal parts, with stirring and pausing after each part is added. This allows the filler to gradually and evenly disperse in the resin matrix, avoiding agglomeration caused by adding a large amount of filler at once. It ensures full contact between the filler and the resin matrix, forming a uniform and stable mixture, thereby fully utilizing the performance advantages of each raw material and improving the overall performance of the resin adhesive. Detailed Implementation

[0028] The present invention will be further described below with reference to specific implementation examples, but the present invention is not limited to these embodiments.

[0029] Example 1

[0030] A low-expansion, moisture-resistant encapsulating resin for electronic components comprises the following raw materials in parts by weight: 35 parts modified resin, 10 parts phenylmethyl silicone resin, 12 parts epoxy vinyl resin, 5 parts dynamic functional curing agent, 8 parts microencapsulated dicyandiamide curing agent, 2 parts perfluorooctyltriethoxysilane ethanol solution, 40 parts functional filler, and the balance being solvent, with a viscosity of 6000 mPa·s. The functional filler has a mass ratio of silica:boron nitride = 5:3; the silica is pretreated with silane coupling agent KH-560; and the boron nitride is pretreated with silane coupling agent KH-550. The perfluorooctyltriethoxysilane ethanol solution is prepared by diluting perfluorooctyltriethoxysilane with 2 times its mass of ethanol and stirring at 200 rpm for 10 min at room temperature. The solvent has a mass ratio of propylene glycol methyl ether acetate:cyclopentanone:acetone = 1:0.5:0.2.

[0031] The preparation method of the above modified resin includes: pre-dehydration treatment of all raw materials; mixing hydrogenated bisphenol A epoxy resin: hydrogen-terminated polydimethylsiloxane: trimethylsiloxysilicate = 100:12:3, stirring at 200 rpm and heating to 110°C under nitrogen protection, adding 0.03% (by weight) ethynylcyclohexanol of hydrogen-terminated polydimethylsiloxane, stirring at 200 rpm for 5 min, adding 0.2% (by weight) chloroplatinic acid catalyst of hydrogen-terminated polydimethylsiloxane, reacting for 2 h, cooling to 50°C, adding 3% (by weight) silane coupling agent KH-560 of hydrogen-terminated polydimethylsiloxane, stirring at 200 rpm for 30 min, to obtain the modified resin.

[0032] The preparation method of the above-mentioned dynamic functional curing agent includes: reacting 2,3-dihydroxybenzaldehyde:pinacol borane at a mass ratio of 1:1 and a liquid-to-material mass ratio of 1:6 in THF solvent under nitrogen protection with stirring at 100 rpm for 2 h at room temperature; removing the THF solvent by vacuum distillation to obtain intermediate powder; reacting the intermediate powder:hexamethylenediamine at a mass ratio of 1:0.23 and a liquid-to-material mass ratio of 1:6 in anhydrous isopropanol solvent under nitrogen protection with stirring at 100 rpm for 1.5 h at 55 °C; and removing the anhydrous isopropanol solvent by rotary evaporation under vacuum at 55 °C to obtain a dynamic functional curing agent with terminal amino groups.

[0033] The preparation method of the above-mentioned microencapsulated dicyandiamide includes: dicyandiamide: gelatin: gum arabic: glutaraldehyde aqueous solution: deionized water in a mass ratio of 100:10:5:3:300; dissolving gelatin and gum arabic in deionized water at 55℃, adding a 10wt% acetic acid aqueous solution to adjust the pH to 4.0, cooling to 40℃, adding dicyandiamide with a particle size D50 of 3μm, and emulsifying at 40℃ and 7000rpm for 10min to obtain an emulsion; stirring and cooling to 10℃, maintaining for 30min, allowing the gelatin-gum arabic phase to separate and precipitate on the surface of the dicyandiamide and coat the dicyandiamide; and then using 0.05M... The pH was adjusted to 8.0 with Tris-HCl buffer. 18 wt% glutaraldehyde aqueous solution was added dropwise at 0.5 mL / min under stirring at 100 rpm at 25 °C. The reaction was stirred at 200 rpm at 25 °C for 2.5 h, and then allowed to stand at 25 °C for 1 h to mature. The precipitate was filtered, washed three times with 0.18 wt% glycine aqueous solution, freeze-dried, and passed through a 325 mesh sieve to obtain microencapsulated dicyandiamide.

[0034] The method for surface pretreatment of silica with silane coupling agent KH-560 includes: mixing silane coupling agent KH-560:ethanol:deionized water in a mass ratio of 1:40:6, adjusting the pH to 4.5 with acetic acid, and hydrolyzing at 40°C and 100 rpm for 30 min; adding silica at a solid-liquid mass ratio of 1:10, and ultrasonically dispersing at 40°C, 300 W, and 35 kHz for 20 min; removing ethanol by vacuum distillation, drying at 100°C to constant weight, and passing through a 325-mesh sieve to obtain pretreated silica.

[0035] The above-mentioned method for surface pretreatment of boron nitride with silane coupling agent KH-550 includes: mixing silane coupling agent KH-550: ethanol: deionized water in a mass ratio of 1:24:3, adjusting the pH to 4.5 with acetic acid, and hydrolyzing by stirring at 40°C and 100 rpm for 30 min; adding boron nitride in a solid-liquid mass ratio of 1:8, and ultrasonically dispersing at 40°C, 300 W, and 35 kHz for 20 min; removing ethanol by vacuum distillation, drying at 100°C to constant weight, and passing through a 325-mesh sieve to obtain pretreated boron nitride.

[0036] The preparation method of the above-mentioned low-expansion, moisture-resistant electronic component encapsulating resin includes the following steps:

[0037] Add a portion of solvent base material to the reactor, followed by modified resin, phenylmethyl silicone resin, and epoxy vinyl resin, and stir at 150 rpm for 30 min. Then, add dynamic functional curing agent, microencapsulated dicyandiamide curing agent, trifluoropropyl polydimethylsiloxane, and perfluorooctyltriethoxysilane ethanol solution sequentially, and stir at 150 rpm for 20 min. Add the functional filler in three equal portions sequentially, stirring at 200 rpm for 10 min after each portion, pausing for 5 min, and then adding the next portion until all portions are added and mixed. While continuously stirring at 100 rpm, adjust the viscosity to 6000 mPa·s with solvent, homogenize at 1500 rpm for 3 min using a homogenizer equipped with a cooling circulation system to ensure the temperature is below 40℃, vacuum defoam for 10 min, allow to stand for defoaming for 20 min, and pass through a 100-mesh sieve to obtain the finished product. The entire preparation process is carried out below 40℃. The finished product is stored in a sealed, nitrogen-filled environment below 20℃, protected from light.

[0038] Example 2

[0039] A low-expansion, moisture-resistant encapsulating resin for electronic components comprises the following raw materials in parts by weight: 37 parts modified resin, 13 parts phenylmethyl silicone resin, 15 parts epoxy vinyl resin, 6 parts dynamic functional curing agent, 10 parts microencapsulated dicyandiamide curing agent, 2.5 parts perfluorooctyltriethoxysilane ethanol solution, 42 parts functional filler, and the balance being solvent, with a viscosity of 7100 mPa·s. The functional filler has a mass ratio of silica:boron nitride = 5.5:3.5; the silica is pretreated with silane coupling agent KH-560; and the boron nitride is pretreated with silane coupling agent KH-550. The perfluorooctyltriethoxysilane ethanol solution is prepared by diluting perfluorooctyltriethoxysilane with 2.2 times its mass of ethanol and stirring at 220 rpm for 12 minutes at room temperature. The solvent components are in the following mass ratio: propylene glycol methyl ether acetate: cyclopentanone: acetone = 1:0.6:0.25.

[0040] The preparation method of the above modified resin includes: pre-dehydration treatment of all raw materials; mixing hydrogenated bisphenol A epoxy resin: hydrogen-terminated polydimethylsiloxane: trimethylsiloxysilicate = 100:13:3.5, stirring at 220 rpm and heating to 112°C under nitrogen protection, adding 0.04% (by weight) of ethynylcyclohexanol of hydrogen-terminated polydimethylsiloxane, stirring at 220 rpm for 8 min, adding 0.25% (by weight) of chloroplatinic acid catalyst of hydrogen-terminated polydimethylsiloxane, reacting for 2.5 h, cooling to 55°C, adding 4% (by weight) of silane coupling agent KH-560 of hydrogen-terminated polydimethylsiloxane, stirring at 220 rpm for 35 min to obtain the modified resin.

[0041] The preparation method of the above-mentioned dynamic functional curing agent includes: reacting 2,3-dihydroxybenzaldehyde:pinacol borane at a mass ratio of 1:1.05 and a liquid-to-material mass ratio of 1:7 in THF solvent under nitrogen protection with stirring at 120 rpm for 2.5 h at room temperature; removing the THF solvent by vacuum distillation to obtain intermediate powder; reacting the intermediate powder:hexamethylenediamine at a mass ratio of 1:0.24 and a liquid-to-material mass ratio of 1:7 in anhydrous isopropanol solvent under nitrogen protection with stirring at 120 rpm for 1.5 h at 56 °C; removing the anhydrous isopropanol solvent by rotary evaporation under vacuum at 56 °C to obtain a dynamic functional curing agent with terminal amino groups.

[0042] The preparation method of the above-mentioned microencapsulated dicyandiamide includes: dicyandiamide: gelatin: gum arabic: glutaraldehyde aqueous solution: deionized water in a mass ratio of 100:13:7:4:350; dissolving gelatin and gum arabic in deionized water at 58℃, adjusting the pH to 4.2 with 11wt% acetic acid aqueous solution, cooling to 42℃, adding dicyandiamide with a particle size D50 of 3.8μm, and emulsifying at 42℃ and 7500rpm for 12min to obtain an emulsion; stirring and cooling to 11℃, maintaining for 35min, allowing the gelatin-gum arabic phase to separate and precipitate on the surface of the dicyandiamide and coat the dicyandiamide; and then using 0.05M... The pH was adjusted to 8.1 with Tris-HCl buffer. A 19wt% glutaraldehyde aqueous solution was added dropwise at 0.8 mL / min under stirring at 120 rpm at 28 °C. The reaction was stirred at 250 rpm at 28 °C for 2.5 h, and then allowed to stand at 28 °C for 1 h to mature. The precipitate was filtered and washed three times with a 0.19wt% glycine aqueous solution. The precipitate was then freeze-dried and passed through a 400-mesh sieve to obtain microencapsulated dicyandiamide.

[0043] The method for surface pretreatment of silica with silane coupling agent KH-560 includes: mixing silane coupling agent KH-560: ethanol: deionized water in a mass ratio of 1:45:8, adjusting the pH to 4.7 with acetic acid, and hydrolyzing by stirring at 42°C and 120 rpm for 35 min; adding silica in a solid-liquid mass ratio of 1:11, and ultrasonically dispersing at 42°C, 300 W, and 35 kHz for 25 min; removing ethanol by vacuum distillation, drying at 105°C to constant weight, and passing through a 400-mesh sieve to obtain pretreated silica.

[0044] The above-mentioned method for surface pretreatment of boron nitride with silane coupling agent KH-550 includes: mixing silane coupling agent KH-550: ethanol: deionized water in a mass ratio of 1:25:4, adjusting the pH to 4.8 with acetic acid, and hydrolyzing by stirring at 42°C and 120 rpm for 35 min; adding boron nitride in a solid-liquid mass ratio of 1:9, and ultrasonically dispersing at 42°C, 350W, and 40kHz for 25 min; removing ethanol by vacuum distillation, drying at 105°C to constant weight, and passing through a 325-mesh sieve to obtain pretreated boron nitride.

[0045] The preparation method of the above-mentioned low-expansion, moisture-resistant electronic component encapsulating resin includes the following steps:

[0046] Add a portion of the solvent base to the reactor, followed by the modified resin, phenylmethyl silicone resin, and epoxy vinyl resin, and stir at 180 rpm for 35 min. Then, add the dynamic functional curing agent, microencapsulated dicyandiamide curing agent, trifluoropropyl polydimethylsiloxane, and perfluorooctyltriethoxysilane ethanol solution sequentially, and stir at 180 rpm for 25 min. Add the functional filler in three equal portions sequentially, stirring at 220 rpm for 12 min after each portion, pausing for 6 min, and then adding the next portion until all portions are added and mixed. While continuously stirring at 120 rpm, adjust the viscosity to 7100 mPa·s with solvent, homogenize at 2000 rpm for 4 min using a homogenizer equipped with a cooling circulation system to ensure the temperature remains below 40℃, vacuum defoam for 12 min, allow to stand for 25 min for further defoaming, and pass through a 120-mesh sieve to obtain the finished product. The entire preparation process is carried out below 40℃. The finished product is stored in a sealed, nitrogen-filled environment below 20℃, protected from light.

[0047] Example 3

[0048] A low-expansion, moisture-resistant encapsulating resin for electronic components comprises the following raw materials in parts by weight: 40 parts modified resin, 15 parts phenylmethyl silicone resin, 18 parts epoxy vinyl resin, 8 parts dynamic functional curing agent, 12 parts microencapsulated dicyandiamide curing agent, 3 parts perfluorooctyltriethoxysilane ethanol solution, 45 parts functional filler, and the balance being solvent, with a viscosity of 8000 mPa·s. The functional filler has a mass ratio of silica:boron nitride = 6:4; the silica is pretreated with silane coupling agent KH-560; and the boron nitride is pretreated with silane coupling agent KH-550. The perfluorooctyltriethoxysilane ethanol solution is prepared by diluting perfluorooctyltriethoxysilane with 2.5 times its mass of ethanol and stirring at 250 rpm for 15 min at room temperature. The solvent has a mass ratio of propylene glycol methyl ether acetate:cyclopentanone:acetone = 1:0.7:0.3.

[0049] The preparation method of the above modified resin includes: pre-dehydration treatment of all raw materials; mixing hydrogenated bisphenol A epoxy resin: hydrogen-terminated polydimethylsiloxane: trimethylsiloxysilicate = 100:15:4, stirring at 250 rpm and heating to 115°C under nitrogen protection, adding 0.05% (by weight) ethynylcyclohexanol of hydrogen-terminated polydimethylsiloxane, stirring at 250 rpm for 10 min, adding 0.3% (by weight) chloroplatinic acid catalyst of hydrogen-terminated polydimethylsiloxane, reacting for 3 h, cooling to 60°C, adding 5% (by weight) silane coupling agent KH-560 of hydrogen-terminated polydimethylsiloxane, stirring at 250 rpm for 40 min to obtain the modified resin.

[0050] The preparation method of the above-mentioned dynamic functional curing agent includes: reacting the mixture of 2,3-dihydroxybenzaldehyde and pinacol borane at a mass ratio of 1:1.1 and a liquid-to-material mass ratio of 1:8 in THF solvent under nitrogen protection with stirring at 150 rpm for 3 h at room temperature; removing the THF solvent by vacuum distillation to obtain an intermediate powder; reacting the mixture of the intermediate powder and hexamethylenediamine at a mass ratio of 1:0.25 and a liquid-to-material mass ratio of 1:8 in anhydrous isopropanol solvent under nitrogen protection with stirring at 150 rpm for 2 h at 58 °C; and removing the anhydrous isopropanol solvent by rotary evaporation under vacuum at 57 °C to obtain a dynamic functional curing agent with terminal amino groups.

[0051] The preparation method of the above-mentioned microencapsulated dicyandiamide includes: dicyandiamide: gelatin: gum arabic: glutaraldehyde aqueous solution: deionized water in a mass ratio of 100:15:8:5:400; dissolving gelatin and gum arabic in deionized water at 60℃, adding 12wt% acetic acid aqueous solution to adjust the pH to 4.5, cooling to 45℃, adding dicyandiamide with a particle size D50 of 4.6μm, and emulsifying at 45℃ and 8000rpm for 15min to obtain an emulsion; stirring and cooling to 12℃, maintaining for 40min, allowing the gelatin-gum arabic phase to separate and precipitate on the surface of the dicyandiamide and coat the dicyandiamide; and using 0.06M... The pH was adjusted to 8.2 with Tris-HCl buffer. A 20wt% glutaraldehyde aqueous solution was added dropwise at a rate of 1 mL / min under stirring at 150 rpm at 30 °C. The reaction was stirred at 300 rpm at 30 °C for 3 h and then allowed to stand at 30 °C for 1.5 h to mature. The precipitate was filtered and washed four times with a 0.20wt% glycine aqueous solution. The precipitate was then freeze-dried and passed through a 400-mesh sieve to obtain microencapsulated dicyandiamide.

[0052] The method for surface pretreatment of silica with silane coupling agent KH-560 includes: mixing silane coupling agent KH-560:ethanol:deionized water in a mass ratio of 1:50:10, adjusting the pH to 5.0 with acetic acid, and hydrolyzing by stirring at 45°C and 150 rpm for 40 min; adding silica in a solid-liquid mass ratio of 1:12, and ultrasonically dispersing at 45°C, 350 W, and 40 kHz for 30 min; removing ethanol by vacuum distillation, drying at 110°C to constant weight, and passing through a 400-mesh sieve to obtain pretreated silica.

[0053] The above-mentioned method for surface pretreatment of boron nitride with silane coupling agent KH-550 includes: mixing silane coupling agent KH-550: ethanol: deionized water in a mass ratio of 1:26:5, adjusting the pH to 5.0 with acetic acid, and hydrolyzing by stirring at 45°C and 150 rpm for 40 min; adding boron nitride in a solid-liquid mass ratio of 1:10, and ultrasonically dispersing at 45°C, 350 W, and 40 kHz for 30 min; removing ethanol by vacuum distillation, drying at 110°C to constant weight, and passing through a 400-mesh sieve to obtain pretreated boron nitride.

[0054] The preparation method of the above-mentioned low-expansion, moisture-resistant electronic component encapsulating resin includes the following steps:

[0055] Add a portion of the solvent base to the reactor, followed by the modified resin, phenylmethyl silicone resin, and epoxy vinyl resin, and stir at 200 rpm for 40 min. Then, add the dynamic functional curing agent, microencapsulated dicyandiamide curing agent, trifluoropropyl polydimethylsiloxane, and perfluorooctyltriethoxysilane ethanol solution sequentially, and stir at 200 rpm for 30 min. Add the functional filler in three equal portions sequentially, stirring at 250 rpm for 15 min after each portion, pausing for 8 min, and then adding the next portion until all portions are added and mixed. While continuously stirring at 150 rpm, adjust the viscosity to 8000 mPa·s with solvent, homogenize at 2500 rpm for 5 min using a homogenizer equipped with a cooling circulation system to ensure the temperature remains below 40℃, vacuum defoam for 15 min, allow to stand for 30 min for further defoaming, and pass through a 100-mesh sieve to obtain the finished product. The entire preparation process is carried out below 40℃. The finished product is stored in a sealed, nitrogen-filled environment below 20℃, protected from light.

[0056] The raw materials used in the above embodiments are as follows: Hydrogenated bisphenol A epoxy resin is from Xiamen Aikema Chemical Co., Ltd., model BE115. Hydrogen-terminated polydimethylsiloxane is from Wuhan Hongde Yuexin Pharmaceutical Technology Co., Ltd. Trimethylsiloxane silicate is from Shantou Bangde Chemical Co., Ltd. Ethynylcyclohexanol is from Guangzhou Daxi Chemical New Materials Co., Ltd., 1-ethynylcyclohexanol. Chloroplatinic acid catalyst is from Shanghai Jiuyue Chemical Co., Ltd. Silane coupling agent KH-560 is from Henan Yaoxing Chemical Products Co., Ltd. Phenylmethyl silicone resin is from Hubei Longsheng Sihai New Materials Co., Ltd., model SH1153. Epoxy vinyl resin is from Langfang Hangsen Anticorrosion Materials Co., Ltd., epoxy vinyl resin 901. 2,3-Dihydroxybenzaldehyde is from Hubei Tuobang Chemical Co., Ltd. Pinacol borane is from Shanghai Aladdin Biochemical Technology Co., Ltd. THF solvent is from Shandong Jiaying Chemical Technology Co., Ltd. Hexamethylenediamine is from Jinan Langsheng New Materials Co., Ltd. Isopropanol is from Shandong Changyuan Chemical Co., Ltd. Dicyandiamide is from Jinan Liyang Chemical Co., Ltd. Gelatin is sourced from Hengshui Qianlong Gelatin Technology Co., Ltd. Gum arabic is sourced from Taian Dingli Adhesive Industry Co., Ltd., model DL-AAI. Glutaraldehyde is sourced from Shandong Jiu'an Chemical Co., Ltd. Glycine is sourced from Shijiazhuang Demou Chemical Technology Co., Ltd. Perfluorooctyltriethoxysilane is sourced from Guangdong Chuanliu Chemical Reagent Co., Ltd. Silica is fused silica micropowder, sourced from Lingshou County Marble Mineral Products Processing Plant, with a D50 of less than 5μm. Boron nitride is sourced from Zhengzhou Keqi Chemical Products Co., Ltd., with a D50 of less than 15μm. Silane coupling agent KH-550 is sourced from Henan Yaoxing Chemical Products Co., Ltd.

[0057] Comparative Example 1

[0058] The difference from Example 1 is that hydrogenated bisphenol A epoxy resin is used instead of modified resin.

[0059] Comparative Example 2

[0060] Trimethylsiloxane silicate is not added during the preparation of the modified resin.

[0061] Comparative Example 3

[0062] Ethynylcyclohexanol is not added during the preparation of the modified resin.

[0063] Comparative Example 4

[0064] The difference from Example 1 is that the phenylmethyl silicone resin is changed to 5 parts and the epoxy vinyl resin is changed to 25 parts.

[0065] Comparative Example 5

[0066] The difference from Example 1 is that the phenylmethyl silicone resin is changed to 25 parts and the epoxy vinyl resin is changed to 5 parts.

[0067] Comparative Example 6

[0068] The difference from Example 1 is that the dynamic functional curing agent is changed to 3 parts.

[0069] Comparative Example 7

[0070] The difference from Example 1 is that the microencapsulated dicyandiamide is replaced with dicyandiamide.

[0071] Comparative Example 8

[0072] The difference from Example 1 is that the silica and boron nitride are not subjected to silane coupling agent surface pretreatment.

[0073] Comparative Example 9

[0074] The difference from Example 1 is that perfluorooctyltriethoxysilane ethanol solution is not added.

[0075] Comparative Example 10

[0076] The difference from Example 1 is that 0.7 parts of perfluorooctyltriethoxysilane were added directly without dilution with ethanol.

[0077] I. Coefficient of Thermal Expansion (CTE) Testing:

[0078] The encapsulating resin was poured into a mold measuring 50mm × 5mm × 2mm and cured at 120℃ for 1 hour, then at 150℃ for 2 hours, and finally at 150℃ for 3 hours. After demolding, a long strip sample was obtained, with 3 parallel samples. A thermomechanical analyzer (TMA) was used to measure the linear expansion of the sample from 25℃ to 200℃ at a heating rate of 5℃ / min, and the coefficient of thermal expansion was calculated. The coefficient of thermal expansion CTE = (ΔL / L0) / ΔT; ΔL is the change in length, L0 is the original length, and ΔT is the change in temperature.

[0079] II. Moisture Resistance Test:

[0080] The encapsulating resin was poured into a mold measuring φ50mm×2mm and cured at 120℃ for 1 hour, followed by curing at 150℃ for 3 hours. After demolding, three parallel circular samples were obtained. The samples were weighed and then placed in a constant temperature and humidity chamber at 85℃ and 85% relative humidity for 1000 hours. After removal, the moisture resistance was evaluated by measuring the water absorption rate and surface resistivity of the samples (using a high-resistivity meter, test voltage 500V, resistivity equilibrated at 23℃ and 50%RH for 24 hours before the test). Water absorption rate = (weight after test - weight before test) / weight before test × 100%.

[0081] Table 1. Test Results (Average)

[0082]

[0083] The results above show that the encapsulating resins of Examples 1 to 3 exhibit excellent anti-swelling and moisture resistance. The modified resins are prepared by reacting hydrogenated bisphenol A epoxy resin, hydrogen-terminated polydimethylsiloxane, and trimethylsiloxysilicate. The siloxane segments have a low coefficient of thermal expansion, and their flexible structure can buffer the thermal motion of molecular chains during temperature changes, reducing volume expansion caused by temperature variations. The filler is pretreated with a silane coupling agent, which improves the interfacial bonding between the filler and the resin matrix, resulting in more uniform dispersion of the filler in the resin and a more stable structure, further reducing the coefficient of thermal expansion. Perfluorooctyltriethoxysilane results in extremely low surface energy, forming a hydrophobic layer that prevents moisture adsorption and penetration. The siloxane segments in the modified resin themselves have a certain degree of hydrophobicity, which, combined with the good interfacial bonding between the filler and the resin matrix, reduces the channels for moisture penetration. Simultaneously, the appropriate ratio of phenylmethyl silicone resin and epoxy vinyl resin forms a dense cross-linked network structure, further blocking moisture intrusion and thus improving moisture resistance.

[0084] Comparative Example 1 used hydrogenated bisphenol A epoxy resin to replace the modified resin. Hydrogenated bisphenol A epoxy resin has a rigid molecular chain and lacks the flexible buffering structure of siloxane segments. When the temperature changes, the rigid epoxy molecular chains undergo intense thermal motion, reducing their compatibility with the filler's thermal expansion and leading to a significant increase in the material's coefficient of thermal expansion.

[0085] Compared to modified resins, hydrogenated bisphenol A epoxy resin has poor hydrophobicity, lacks hydrophobic groups in its organosilicon structure, and has more polar groups in its molecular structure. The hydroxyl groups in polar epoxy resins readily adsorb water molecules. When moisture enters the resin system, it disrupts the resin structure, leading to a decrease in surface resistivity and deterioration of insulation properties.

[0086] In Comparative Example 2, trimethylsiloxane silicate was not added during the preparation of the modified resin. Trimethylsiloxane silicate promotes the crosslinking reaction, forming a Si-O-Si network structure. The absence of this component reduces the crosslinking density between siloxane segments and between siloxanes and epoxy resin, weakens the intermolecular forces, increases the molecular chain's activity space, and increases the degree of freedom of molecular chain thermal motion. This makes the chain more prone to expansion under temperature changes, leading to an increased coefficient of thermal expansion. The reduced crosslinking network density decreases the density of the resin matrix, resulting in more pores and channels. The loosening of the crosslinking network expands the water molecule diffusion channels, allowing moisture to penetrate more easily into the resin, leading to increased water absorption. The incomplete crosslinking network also results in increased micropores after curing, facilitating moisture penetration and ionization.

[0087] Comparative Example 3 did not include etynylcyclohexanol. Ethynylcyclohexanol is an inhibitor of chloroplatinic acid catalysts. Without it in the preparation of the modified resin, the hydrosilylation reaction rate between hydrogen-terminated polydimethylsiloxane and hydrogenated bisphenol A epoxy resin becomes difficult to control, leading to overly vigorous or uneven reactions. This results in uneven distribution of siloxane segments in the epoxy resin, with excessive or insufficient local crosslinking, and a wider molecular weight distribution in the modified resin. This uneven structure causes inconsistent expansion of the material upon heating, increasing the overall coefficient of thermal expansion. The uneven reaction also leads to defects in the resin matrix structure, which become channels for moisture penetration, thus affecting the material's moisture resistance, increasing water absorption, and decreasing surface resistivity.

[0088] In Comparative Example 4, the phenylmethyl silicone resin was changed to 5 parts, and the epoxy vinyl resin to 25 parts. The epoxy vinyl resin has a higher coefficient of thermal expansion than the phenylmethyl silicone resin. Increasing the proportion of epoxy vinyl resin and decreasing the proportion of phenylmethyl silicone resin results in insufficient silicone content weakening flexibility, while high epoxy content increases rigidity. This leads to an increase in components with high coefficients of thermal expansion in the system, resulting in an overall higher coefficient of thermal expansion. Phenylmethyl silicone resin has good hydrophobicity; reducing its proportion decreases the overall hydrophobicity of the system. Simultaneously, increasing the proportion of epoxy vinyl resin alters the cross-linked network structure, forming more polar regions and pores, making it easier for moisture to penetrate, increasing water absorption, and decreasing surface resistivity.

[0089] In Comparative Example 5, the phenylmethyl silicone resin was changed to 25 parts, and the epoxy vinyl resin was changed to 5 parts. Although phenylmethyl silicone resin has low expansion characteristics, excessive silicone leads to insufficient crosslinking density and loose molecular chains. Insufficient crosslinking density weakens the interaction forces between molecular chains, making them more prone to movement and expansion when heated, thus increasing the coefficient of thermal expansion. Although phenylmethyl silicone resin has good hydrophobicity, insufficient crosslinking results in insufficient density of the resin matrix, with many voids. Moisture can still penetrate into the material through these voids. Silicone has higher conductivity than epoxy resin, and excessive addition reduces overall insulation, with limited improvement in water absorption and surface resistivity.

[0090] In Comparative Example 6, the dynamic functional curing agent was reduced to 3 parts. Insufficient dynamic functional curing agent leads to incomplete cross-linking of the resin system. Lower cross-linking density reduces the binding between molecular chains, decreases stress relaxation ability, and allows molecular chains to move and expand more freely when heated, resulting in an increased coefficient of thermal expansion. Insufficiently cross-linked resin matrices have a loose structure, weakened cross-linking network repair ability, increased moisture absorption pathways, and numerous pores and channels. Moisture easily penetrates into the resin interior, damaging the resin structure, leading to increased water absorption and decreased surface resistivity.

[0091] In Comparative Example 7, microencapsulated dicyandiamide was used instead of regular dicyandiamide. Microencapsulated dicyandiamide achieves a more uniform curing reaction through controlled release and prevents moisture absorption during preparation and before curing. With ordinary dicyandiamide, the reaction rate is difficult to control during curing, easily leading to localized excessively fast or slow curing and the formation of an uneven cross-linked structure. This uneven structure causes inconsistent expansion of the material upon heating, increasing the coefficient of thermal expansion. Unencapsulated dicyandiamide is hygroscopic and deliquescent, dissolving and forming pores. The uneven cured structure contains numerous defects and pores, allowing moisture to easily penetrate the resin, leading to increased water absorption and decreased surface resistivity. Furthermore, the easily ionized products of dicyandiamide (cyanide ions) form conductive channels.

[0092] In Comparative Example 8, the silica and boron nitride were not pretreated with silane coupling agents. The untreated fillers exhibited poor interfacial bonding with the resin matrix, resulting in significant interfacial voids. These voids become stress concentration points during temperature changes, affecting uniform heat transfer and leading to uneven thermal expansion and an increased coefficient of thermal expansion. Furthermore, the weak filler-resin interfacial bonding under thermal stress makes the fillers prone to debonding and forming voids. These interfacial voids become channels for moisture penetration, and the untreated filler surface easily adsorbs moisture, facilitating moisture entry into the resin system. Interfacial defects become preferential pathways for water molecule diffusion, leading to increased water absorption and decreased surface resistivity.

[0093] In Comparative Example 9, without the addition of perfluorooctyltriethoxysilane ethanol solution, the resin surface lacked a hydrophobic protective layer. The polar groups in the resin matrix were directly exposed to the environment, easily absorbing moisture. Moisture could directly penetrate into the resin interior, leading to a significant increase in water absorption and a marked decrease in surface resistivity. Since the coefficient of thermal expansion is primarily determined by the inherent properties of the resin matrix and fillers, the absence of this component had a relatively small impact on the coefficient of thermal expansion, resulting in minimal change in CTE.

[0094] In Comparative Example 10, perfluorooctyltriethoxysilane was not diluted and protected with ethanol. The perfluorooctyltriethoxysilane has poor compatibility with the organosilicon polar resin components and is prone to precipitation, resulting in uneven modification and protection, which reduces the overall hydrophobicity and the index.

Claims

1. A low-expansion, moisture-resistant encapsulating resin for electronic components, characterized in that, The raw materials include the following parts by weight: 35-40 parts modified resin, 10-15 parts phenylmethyl silicone resin, 12-18 parts epoxy vinyl resin, 5-8 parts dynamic functional curing agent, 8-12 parts microencapsulated dicyandiamide curing agent, 1-3 parts perfluorooctyltriethoxysilane ethanol solution, 40-45 parts functional filler, and the balance being solvent, with a viscosity of 6000 mPa·s to 8000 mPa·s; The modified resin is obtained by mixing hydrogenated bisphenol A type epoxy resin with hydrogen-terminated polydimethylsiloxane and trimethylsiloxysilicate, and then adding silane coupling agent KH-560. The dynamic functional curing agent is an intermediate powder obtained by reacting 2,3-dihydroxybenzaldehyde and pinacol borane at a mass ratio of 1:(1-1.1), and then reacting the intermediate powder with hexamethylenediamine at a mass ratio of 1:(0.23-0.25). The component mass ratio of the functional filler is silicon dioxide:boron nitride = (5-6):(3-4); the silicon dioxide is pretreated with silane coupling agent KH-560; the boron nitride is pretreated with silane coupling agent KH-550.

2. The low-expansion, moisture-resistant electronic component encapsulating resin according to claim 1, characterized in that, The method for preparing the modified resin includes: mixing hydrogenated bisphenol A epoxy resin, hydrogen-terminated polydimethylsiloxane, and trimethylsiloxysilicate in a ratio of 100:(12-15):(3-4), stirring at 200-250 rpm under nitrogen protection and heating to 110-115°C, adding 0.03%-0.05% ethynylcyclohexanol by mass of hydrogen-terminated polydimethylsiloxane, stirring at 200-250 rpm for 5-10 minutes, adding 0.2%-0.3% chloroplatinic acid catalyst by mass of hydrogen-terminated polydimethylsiloxane, reacting for 2-3 hours, cooling to 50-60°C, adding 3%-5% silane coupling agent KH-560 by mass of hydrogen-terminated polydimethylsiloxane, stirring at 200-250 rpm for 30-40 minutes to obtain the modified resin.

3. The low-expansion, moisture-resistant electronic component encapsulating resin adhesive according to claim 1, characterized in that, The preparation method of the dynamic functional curing agent includes: reacting 2,3-dihydroxybenzaldehyde:pinacol borane in a mass ratio of 1:(1-1.1) in THF solvent under nitrogen protection with stirring at room temperature for 2-3 hours; removing the THF solvent by vacuum distillation to obtain an intermediate powder; reacting the intermediate powder:hexamethylenediamine in anhydrous isopropanol solvent under nitrogen protection with stirring at 55-58°C for 1.5-2 hours; removing the anhydrous isopropanol solvent by rotary evaporation to obtain a dynamic functional curing agent with terminal amino groups.

4. The low-expansion, moisture-resistant electronic component encapsulating resin adhesive according to claim 3, characterized in that, The amount of THF solvent used is 6 to 8 times the total mass of 2,3-dihydroxybenzaldehyde and pinacol borane; the amount of anhydrous isopropanol solvent used is 6 to 8 times the total mass of intermediate powder and hexamethylenediamine; the rotary evaporation is carried out under reduced pressure at a temperature below 58°C.

5. The low-expansion, moisture-resistant electronic component encapsulating resin according to claim 1, characterized in that, The preparation method of the microencapsulated dicyandiamide includes: dicyandiamide: gelatin: gum arabic: glutaraldehyde aqueous solution: deionized water in a mass ratio of 100:(10-15):(5-8):(3-5):(300-400); dissolving gelatin and gum arabic in deionized water at 55℃-60℃, adding 10wt%-12wt% acetic acid aqueous solution to adjust the pH to 4.0-4.5, cooling to 40℃-45℃, adding dicyandiamide with a particle size D50 of less than 5μm, and emulsifying at 40℃-45℃ and 7000rpm-8000rpm for 10-15 minutes to obtain an emulsion; stirring and cooling to 10℃-12℃, maintaining for 30-40 minutes to allow the gelatin-gum arabic phase to separate and precipitate on the surface of the dicyandiamide and coat the dicyandiamide; and using 0.05M-0.06M... Adjust the pH to 8.0–8.2 with Tris-HCl buffer. Add 18 wt%–20 wt% glutaraldehyde aqueous solution dropwise at a rate of 0.5 mL / min–1 mL / min at 25 °C–30 °C. Stir the reaction at 25 °C–30 °C for 2.5–3 h, then allow it to stand at 25 °C–30 °C for 1–1.5 h to mature. Filter the precipitate, wash it 3–4 times with 0.18 wt%–0.20 wt% glycine aqueous solution, freeze-dry it, and pass it through a 325–400 mesh sieve to obtain microencapsulated dicyandiamide.

6. The low-expansion, moisture-resistant electronic component encapsulating resin according to claim 1, characterized in that, The silicon dioxide has a D50 of less than 5 μm; the boron nitride has a D50 of less than 15 μm.

7. The low-expansion, moisture-resistant electronic component encapsulating resin according to claim 1, characterized in that, The perfluorooctyltriethoxysilane ethanol solution is prepared by diluting perfluorooctyltriethoxysilane with 2 to 2.5 times its mass of ethanol and stirring at 200 to 250 rpm for 10 to 15 minutes at room temperature.

8. The low-expansion, moisture-resistant electronic component encapsulating resin according to claim 1, characterized in that, The solvent has the following composition by mass ratio: propylene glycol methyl ether acetate: cyclopentanone: acetone = 1:(0.5-0.7):(0.2-0.3).

9. The method for preparing a low-expansion, moisture-resistant electronic component encapsulating resin according to claim 1, characterized in that, The preparation method includes the following steps: Add modified resin, phenylmethyl silicone resin, and epoxy vinyl resin to the solvent, and stir at 150 rpm to 200 rpm for 30 to 40 minutes. Then, add dynamic functional curing agent, microencapsulated dicyandiamide curing agent, trifluoropropyl polydimethylsiloxane, and perfluorooctyltriethoxysilane ethanol solution sequentially, and stir at 150 rpm to 200 rpm for 20 to 30 minutes. Add the functional filler in three equal portions sequentially. After each portion is added, stir at 200 rpm to 250 rpm for 10 to 15 minutes, pause for 5 to 8 minutes, and then add the next portion until all portions are added and mixed. While continuously stirring at 100 rpm to 150 rpm, adjust the viscosity to 6000 mPa·s to 10000 mPa·s with the solvent. Homogenize at high speed of 1500 rpm to 2500 rpm for 3 to 5 minutes, defoam under vacuum, allow to stand to defoam, and pass through a 100-120 mesh sieve to obtain the finished product.

10. The method for preparing a low-expansion, moisture-resistant electronic component encapsulating resin according to claim 9, characterized in that, The entire preparation process is carried out at a temperature below 40°C; the finished product is stored in a sealed container under nitrogen purging at an ambient temperature below 20°C, protected from light.

Images