Heat-conducting epoxy resin molding compound for packaging material and preparation method of heat-conducting epoxy resin molding compound

Abstract

The invention discloses a heat-conducting epoxy resin molding compound for a packaging material and a preparation method of the heat-conducting epoxy resin molding compound, and belongs to the technical field of epoxy resin material preparation. The preparation method comprises the following steps: mixing polyurethane coated silicon carbide, a curing agent composition and an epoxy resin composition according to a weight part ratio of (15-21): (20-23): (30-36), carrying out vacuum defoaming treatment, heating to 90-100 DEG C, and curing for 3-4 hours to obtain the heat-conducting epoxy resin molding compound. The heat-conducting epoxy resin molding compound obtained by mixing and curing the polyurethane coated silicon carbide, the curing agent composition and the epoxy resin composition has good heat-conducting property and mechanical property.

Description

Technical Field

[0001] This invention belongs to the field of epoxy resin material preparation technology, specifically relating to a thermally conductive epoxy resin molding compound for encapsulation materials and its preparation method. Background Technology

[0002] With the rapid development of electronic technology and the increasing integration of electronic devices, packaging technology, as a crucial link connecting chips to the external environment, is receiving increasing attention. Packaging materials play a vital role in ensuring the performance of electronic components, extending their lifespan, and improving production efficiency. Electronic packaging materials refer to the outer sealing layer of electronic components. This sealing layer plays a key role in supporting electronic components and interconnecting wires, isolating them from the external environment, and conducting and dissipating heat from the electronic components. Based on these functions, excellent electronic packaging materials must possess excellent thermal conductivity and heat dissipation performance, good matching of thermal expansion coefficients, and functions such as insulation and flame retardancy. According to the differences in material composition, electronic packaging materials can be broadly classified into metal-based electronic packaging materials, ceramic-based electronic packaging materials, and polymer-based electronic packaging materials. Metal-based electronic packaging materials were developed earlier and have characteristics such as high thermal conductivity and high strength. However, the high density and processing difficulty of traditional metal-based packaging materials have affected their widespread application. Ceramic-based electronic packaging materials are hermetically sealed electronic packaging materials, mainly including alumina and aluminum nitride. Polymer-based electronic packaging materials are currently the most widely used and fastest-growing type of electronic packaging material. They have advantages such as low density, fast molding, and low manufacturing cost, and can adapt to various complex packaging structures. They are an important type of electronic packaging material for realizing the miniaturization, lightweighting, and cost reduction of electronic products.

[0003] Epoxy molding compound is a polymer-based electronic packaging material with epoxy resin as its matrix, widely used in semiconductor device packaging. It has advantages such as stable reliability, low cost, simple production process, and suitability for large-scale production. However, due to the low thermal conductivity of epoxy resin, the heat generated by electronic components is difficult to dissipate quickly, which can easily lead to overheating of electronic components, thereby affecting their performance, stability, and lifespan.

[0004] Patent CN112409757A discloses a high thermal conductivity epoxy molding compound for high-power module packaging and its preparation method. This invention utilizes inexpensive urea, boric acid, and commonly used spherical silica as raw materials to prepare large-particle-size SiO2@BN particles with a core-shell structure and high thermal conductivity. Applying these particles to the preparation of high thermal conductivity EMC significantly reduces manufacturing costs, and the resulting EMC exhibits excellent thermal conductivity. While thermally conductive fillers such as silica can improve the thermal conductivity of epoxy resin, their surface inertness leads to poor interfacial bonding with the epoxy resin, easily weakening the performance of the prepared epoxy molding compound.

[0005] Therefore, improving the interfacial bonding between thermally conductive fillers and epoxy resin can not only enhance the thermal conductivity of epoxy molding compounds, but also give them good mechanical properties. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a thermally conductive epoxy molding compound obtained by mixing and curing a polyurethane-coated silicon carbide, a curing agent composition, and an epoxy resin composition. This solves the technical problems mentioned in the prior art. Specifically, the technical solution of this invention includes the following: One objective of this invention is to provide a method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials, the method comprising the following steps: Polyurethane-coated silicon carbide, curing agent composition and epoxy resin composition are mixed in a weight ratio of 15~21:20~23:30~36, then vacuum degassed and then heated to 90℃~100℃ for 3h~4h to obtain thermally conductive epoxy resin molding compound.

[0007] Furthermore, the method for preparing the polyurethane-coated silicon carbide includes the following steps: Modified silicon carbide, dimethylolpropionic acid, EDC hydrochloride and 1-hydroxybenzotriazole were mixed in a weight ratio of 1:10~13:15~18:15~18 and reacted at 25℃ for 20h~24h to obtain dihydroxy modified silicon carbide; Dihydroxy-modified silicon carbide, diisocyanate, polypolyol and dibutyltin dilaurate are mixed in a weight ratio of 10:20~30:10~15:0.06~0.07 and heated to 80℃~85℃ for 2h~3h to obtain polyurethane-coated silicon nitride.

[0008] Furthermore, the method for preparing the modified silicon carbide includes the following steps: Pretreated silicon carbide is obtained by plasma treatment. A hydrolysate is obtained by mixing silane coupling agent, water, and anhydrous ethanol in a weight ratio of 10:60~68:20~28 and pre-hydrolyzing the mixture. Modified silicon carbide is obtained by mixing and dispersing pretreated silicon carbide and hydrolysate.

[0009] Furthermore, the conditions for plasma treatment include an oxygen plasma source, a gas flow rate of 200 mL / min to 250 mL / min, a processing power of 150 W to 170 W, and a processing time of 100 s to 120 s.

[0010] Furthermore, the silane coupling agent includes γ-aminopropyltrimethoxysilane or γ-aminopropyltriethoxysilane. The silane coupling agent needs to contain an amino group for subsequently introducing dimethylolpropionic acid onto the modified silicon carbide through an amidation reaction, and then dispersing the silicon carbide in the polyurethane through a polymerization reaction to achieve polymeric coating of the silicon carbide.

[0011] Furthermore, the conditions for the mixed pre-hydrolysis include a pre-hydrolysis pH of 4 to 4.5, a pre-hydrolysis time of 40 to 50 minutes, and a pre-hydrolysis temperature of 30°C to 40°C.

[0012] Furthermore, the weight ratio of the pretreated silicon carbide to the silane coupling agent is 5-6:1.

[0013] Furthermore, the conditions for the mixing and dispersion reaction of the pretreated silicon carbide and the hydrolysate include a reaction temperature of 60℃~70℃ and a reaction time of 80min~90min.

[0014] Furthermore, the diisocyanate includes isophorone diisocyanate.

[0015] Furthermore, the polypolyol includes polypropylene glycol 1000 or polycaprolactone diol 2000, where polypropylene glycol 1000 refers to polypropylene glycol with an Mn of 1000, and polycaprolactone diol 2000 refers to polycaprolactone diol with an Mn of 2000.

[0016] Furthermore, the curing agent composition consists of DMP-30 and methylhexahydrophthalic anhydride in a weight ratio of 1:50.

[0017] Furthermore, the epoxy resin composition is composed of phenolic epoxy resin and epoxy resin E-44 in a weight ratio of 1:4.

[0018] Furthermore, the degassing treatment conditions include a degassing temperature of 50°C and a degassing time of 30 to 40 minutes.

[0019] A second objective of this invention is to provide a thermally conductive epoxy resin molding compound prepared by a method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention first uses plasma to oxidize and modify the surface of silicon carbide with good thermal conductivity to obtain pretreated silicon carbide. High-energy oxygen atoms, oxygen ions and free radicals in the oxygen plasma bombard the surface of silicon carbide, triggering an oxidation reaction and introducing oxygen-containing groups such as hydroxyl groups, thereby improving the surface activity of silicon carbide. Next, pretreated silicon carbide was surface-grafted with an amino-containing silane coupling agent to obtain modified silicon carbide. Modified silicon carbide and dimethylolpropionic acid underwent an amidation condensation reaction of amino and carboxyl ester bonds in the catalysis of EDC hydrochloride and 1-hydroxybenzotriazole to obtain dihydroxy modified silicon carbide. Dihydroxy modified silicon carbide, diisocyanate, and polypolyol were polymerized and encapsulated in silicon carbide under the catalysis of dibutyltin dilaurate, resulting in polyurethane-coated silicon carbide. The polyurethane-coated silicon carbide was then crosslinked with epoxy resin to obtain a thermally conductive epoxy resin molding compound. On the one hand, the surface grafting modification of silicon carbide achieves polymeric encapsulation of silicon carbide, allowing it to be uniformly dispersed in polyurethane, thus enhancing the interfacial bonding between silicon carbide and epoxy resin. On the other hand, the flexible long chains of polyurethane can improve the brittle stress of the cured epoxy resin. Through the synergistic effect of silicon carbide and polyurethane, not only are the thermally conductive properties of the prepared thermally conductive epoxy resin molding compound achieved, but its mechanical properties also exhibit excellent performance. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below through embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Unless otherwise stated, all raw materials and reagents used in this invention are commercially available or can be prepared by known methods.

[0023] The phenolic epoxy resin was purchased from Jinan Shengxing Group Co., Ltd., model number SQPN-051.

[0024] Preparation Example 1: The preparation method of modified silicon carbide specifically includes the following processes: Silicon carbide powder with a particle size of 0.85 μm was mixed with anhydrous ethanol and placed in an ultrasonic cleaner at 300 W for 15 min. The silicon carbide was then filtered out, and deionized water was added, followed by ultrasonic cleaning at 300 W for 15 min. After filtration, it was vacuum dried until its weight remained constant. The cleaned and dried silicon carbide was placed in the reaction chamber of a plasma reactor. Oxygen was then introduced into the reaction chamber to purge the air, with the oxygen flow rate controlled at 200 mL / min. The power supply was turned on to discharge the silicon carbide at a power of 150 W, inducing a discharge phenomenon in the reaction chamber. The process was then timed for 100 s. After treatment, the pretreated silicon carbide was stored at room temperature under vacuum for later use. Weigh 60 parts by weight of deionized water and 20 parts by weight of anhydrous ethanol, mix and stir until homogeneous. Then add 10 parts by weight of γ-aminopropyltrimethoxysilane and mix and stir until homogeneous. Adjust the pH of the dispersion to 4 with dilute hydrochloric acid, and place in a water bath at 30°C for pre-hydrolysis treatment for 40 min to obtain hydrolysate. Add 50 parts by weight of pretreated silicon carbide to the hydrolysate and disperse using ultrasonic power at 400W for 10 min. After homogeneous dispersion, heat to 60°C and react for 80 min. After the reaction, filter, wash with anhydrous ethanol, then wash with deionized water, and finally dry in a drying oven at 50°C for 6 h. Cool to room temperature to obtain modified silicon carbide, seal and store for later use.

[0025] Preparation Example 2: The preparation method of modified silicon carbide specifically includes the following processes: Silicon carbide powder with a particle size of 0.85 μm was mixed with anhydrous ethanol and placed in an ultrasonic cleaner at 300 W for 15 min. The silicon carbide was then filtered out, and deionized water was added, followed by ultrasonic cleaning at 300 W for 15 min. After filtration, it was vacuum dried until its weight remained constant. The cleaned and dried silicon carbide was placed in the reaction chamber of a plasma reactor. Oxygen was then introduced into the reaction chamber to purge the air, with the oxygen flow rate controlled at 230 mL / min. The power supply was turned on to discharge the silicon carbide at a power of 160 W, inducing a discharge phenomenon in the reaction chamber. The process was then timed for 110 s. After treatment, the pretreated silicon carbide was stored at room temperature under vacuum for later use. Weigh 64 parts by weight of deionized water and 24 parts by weight of anhydrous ethanol, mix and stir until homogeneous. Then add 10 parts by weight of γ-aminopropyltrimethoxysilane and mix and stir until homogeneous. Adjust the pH of the dispersion to 4.5 with dilute hydrochloric acid and place in a water bath at 35°C for 45 min to pre-hydrolyze and obtain a hydrolysate. Add 55 parts by weight of pretreated silicon carbide to the hydrolysate and disperse using ultrasonic power at 400W for 10 min. After homogeneous dispersion, heat to 65°C and react for 85 min. After the reaction, filter, wash with anhydrous ethanol, then wash with deionized water, and finally dry in a drying oven at 50°C for 6 h. Cool to room temperature to obtain modified silicon carbide, seal and store for later use.

[0026] Preparation Example 3: The preparation method of modified silicon carbide specifically includes the following processes: Silicon carbide powder with a particle size of 0.85 μm was mixed with anhydrous ethanol and placed in an ultrasonic cleaner at 300 W for 15 min. The silicon carbide was then filtered out, and deionized water was added, followed by ultrasonic cleaning at 300 W for 15 min. After filtration, it was vacuum dried until its weight remained constant. The cleaned and dried silicon carbide was placed in the reaction chamber of a plasma reactor. Oxygen was then introduced into the reaction chamber to purge the air, with the oxygen flow rate controlled at 250 mL / min. The power supply was turned on to discharge the silicon carbide at a power of 170 W, inducing a discharge phenomenon in the reaction chamber. The process was then timed for 120 s. After treatment, the pretreated silicon carbide was stored at room temperature under vacuum for later use. Weigh 68 parts by weight of deionized water and 28 parts by weight of anhydrous ethanol, mix and stir until homogeneous. Then add 10 parts by weight of γ-aminopropyltriethoxysilane and mix and stir until homogeneous. Adjust the pH of the dispersion to 4.5 with dilute hydrochloric acid and place in a water bath at 40°C for 50 min to pre-hydrolyze and obtain a hydrolysate. Add 60 parts by weight of pretreated silicon carbide to the hydrolysate and disperse using ultrasonic power at 400W for 10 min. After homogeneous dispersion, heat to 70°C and react for 90 min. After the reaction, filter, wash with anhydrous ethanol, then wash with deionized water, and finally dry in a drying oven at 50°C for 6 h. Cool to room temperature to obtain modified silicon carbide, which is then sealed and stored for later use.

[0027] Preparation Example 4: The preparation method of modified silicon carbide specifically includes the following processes: In Preparation Example 3, γ-aminopropyltriethoxysilane was replaced with silane coupling agent KH560, and the rest of the preparation process was the same as in Preparation Example 3.

[0028] Preparation Example 5: The preparation method of modified silicon carbide specifically includes the following processes: Weigh 68 parts by weight of deionized water and 28 parts by weight of anhydrous ethanol, mix and stir until homogeneous. Then add 10 parts by weight of γ-aminopropyltriethoxysilane and mix and stir until homogeneous. Adjust the pH of the dispersion to 4.5 with dilute hydrochloric acid and place in a water bath at 50°C for 80 min to pre-hydrolyze and obtain a hydrolysate. Add 60 parts by weight of the pretreated silicon carbide obtained in Preparation Example 3 to the hydrolysate and disperse it using ultrasonic power of 400 W for 10 min. After homogeneous dispersion, heat to 70°C and react for 90 min. After the reaction is complete, filter, wash with anhydrous ethanol, then wash with deionized water, and finally dry in a drying oven at 50°C for 6 h. Cool to room temperature to obtain modified silicon carbide, seal and store for later use.

[0029] Preparation Example 6: The preparation method of modified silicon carbide specifically includes the following processes: The 0.85 μm silicon carbide powder in Preparation Example 3 was replaced with 0.3 μm silicon carbide powder, and the rest of the preparation process was the same as in Preparation Example 3.

[0030] Preparation Example 7: The preparation method of polyurethane-coated silicon carbide specifically includes the following steps: 10 parts by weight of dimethylolpropionic acid, 15 parts by weight of EDC hydrochloride, and 15 parts by weight of 1-hydroxybenzotriazole were weighed and placed in a flask. Then, 100 parts by weight of anhydrous dichloromethane were added to form a reaction system. The reaction system was pretreated at 0°C for 15 min (10 parts by weight of triethylamine can be added to improve the pretreatment effect). Then, 1 part by weight of the modified silicon carbide obtained in Preparation Example 1 was added, and the mixture was stirred at 400 r / min and heated to 25°C. The reaction was carried out at this temperature for 20 h. After the reaction was completed, the solid particles were obtained by filtration. The solid particles were washed with saturated sodium carbonate solution, then washed with deionized water, and then dried under reduced pressure to obtain dihydroxy modified silicon carbide. After drying and dehydrating isophorone diisocyanate and polypropylene glycol 100, 10 parts by weight of dihydroxy modified silicon carbide, 20 parts by weight of isophorone diisocyanate, 10 parts by weight of polypropylene glycol 1000 and 0.06 parts by weight of dibutyltin dilaurate were weighed and added to a reactor. The reactor was then heated to 80°C and reacted for 2 hours to obtain polyurethane-coated silicon nitride.

[0031] Preparation Example 8: The preparation method of polyurethane-coated silicon carbide specifically includes the following steps: Weigh 12 parts by weight of dimethylolpropionic acid, 16 parts by weight of EDC hydrochloride, and 16 parts by weight of 1-hydroxybenzotriazole and place them in a flask. Then add 100 parts by weight of anhydrous dichloromethane to form a reaction system. Pre-treat the reaction system at 0°C for 15 min (10 parts by weight of triethylamine can be added to improve the pre-treatment effect). Then add 1 part by weight of the modified silicon carbide obtained in Preparation Example 2, stir and mix at 400 r / min and heat to 25°C. Stir and react at this temperature for 22 h. After the reaction is complete, filter to obtain solid particles. Wash the solid particles with saturated sodium carbonate solution, then wash with deionized water, and then dry under reduced pressure to obtain dihydroxy modified silicon carbide. After drying and dehydrating isophorone diisocyanate and polypropylene glycol 1000, 10 parts by weight of dihydroxy modified silicon carbide, 25 parts by weight of isophorone diisocyanate, 13 parts by weight of polypropylene glycol 1000 and 0.065 parts by weight of dibutyltin dilaurate were weighed and added to a reactor. The reactor was then heated to 80°C and reacted for 2.5 h to obtain polyurethane-coated silicon nitride.

[0032] Preparation Example 9: The preparation method of polyurethane-coated silicon carbide specifically includes the following steps: Weigh 13 parts by weight of dimethylolpropionic acid, 18 parts by weight of EDC hydrochloride, and 18 parts by weight of 1-hydroxybenzotriazole and place them in a flask. Then add 100 parts by weight of anhydrous dichloromethane to form a reaction system. Pre-treat the reaction system at 0°C for 15 min (10 parts by weight of triethylamine can be added to improve the pre-treatment effect). Then add 1 part by weight of the modified silicon carbide obtained in Preparation Example 3, stir and mix at 400 r / min and heat to 25°C. Stir and react at this temperature for 24 h. After the reaction is complete, filter to obtain solid particles. Wash the solid particles with saturated sodium carbonate solution, then wash with deionized water, and then dry under reduced pressure to obtain dihydroxy modified silicon carbide. After drying and dehydrating isophorone diisocyanate and polycaprolactone diol 2000, 10 parts by weight of dihydroxy modified silicon carbide, 30 parts by weight of isophorone diisocyanate, 15 parts by weight of polycaprolactone diol 2000 and 0.07 parts by weight of dibutyltin dilaurate were weighed and added to a reactor. The reactor was then heated to 85°C and reacted for 3 hours to obtain polyurethane-coated silicon nitride.

[0033] Preparation Example 10: The preparation method of polyurethane-coated silicon carbide specifically includes the following steps: The modified silicon carbide in Preparation Example 9 was replaced with the modified silicon carbide obtained in Preparation Example 4, and the rest of the preparation process was the same as in Preparation Example 9.

[0034] Preparation Example 11: The preparation method of polyurethane-coated silicon carbide specifically includes the following steps: The modified silicon carbide in Preparation Example 9 was replaced with the modified silicon carbide obtained in Preparation Example 5, and the rest of the preparation process was the same as in Preparation Example 9.

[0035] Preparation Example 12: The preparation method of polyurethane-coated silicon carbide specifically includes the following steps: The modified silicon carbide in Preparation Example 9 was replaced with the modified silicon carbide obtained in Preparation Example 6, and the rest of the preparation process was the same as in Preparation Example 9.

[0036] Preparation Example 13: The preparation method of polyurethane-coated silicon carbide specifically includes the following steps: The modified silicon carbide in Preparation Example 9 was replaced with the pretreated silicon carbide obtained in Preparation Example 6, and the rest of the preparation process was the same as in Preparation Example 9.

[0037] Example 1: A method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials, specifically including the following steps: 15 parts by weight of the polyurethane-coated silicon carbide obtained in Preparation Example 7, 20 parts by weight of the curing agent composition (composed of DMP-30 and methylhexahydrophthalic anhydride in a weight ratio of 1:50) and 30 parts by weight of the epoxy resin composition (composed of phenolic epoxy resin of type SQPN-051 and epoxy resin E-44 in a weight ratio of 1:4) were weighed, mixed, heated to 50°C, and then subjected to vacuum degassing treatment for 30 min. After that, the mixture was heated to 90°C and cured for 3 h to obtain a thermally conductive epoxy resin molding compound.

[0038] Example 2: A method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials, specifically including the following steps: 18 parts by weight of the polyurethane-coated silicon carbide obtained in Preparation Example 8, 21 parts by weight of the curing agent composition (composed of DMP-30 and methylhexahydrophthalic anhydride in a weight ratio of 1:50) and 33 parts by weight of the epoxy resin composition (composed of phenolic epoxy resin of type SQPN-051 and epoxy resin E-44 in a weight ratio of 1:4) were weighed, mixed, heated to 50°C, and then subjected to vacuum degassing treatment for 35 min. After that, the mixture was heated to 95°C and cured for 3.5 h to obtain a thermally conductive epoxy resin molding compound.

[0039] Example 3: A method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials, specifically including the following steps: 21 parts by weight of the polyurethane-coated silicon carbide obtained in Preparation Example 9, 23 parts by weight of the curing agent composition (composed of DMP-30 and methylhexahydrophthalic anhydride in a weight ratio of 1:50) and 36 parts by weight of the epoxy resin composition (composed of phenolic epoxy resin of type SQPN-051 and epoxy resin E-44 in a weight ratio of 1:4) were weighed, mixed, heated to 50°C, and then subjected to vacuum degassing treatment for 40 min. After that, the mixture was heated to 100°C and cured for 3 h to obtain a thermally conductive epoxy resin molding compound.

[0040] Comparative Example 1: A method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials, specifically including the following steps: The polyurethane-coated silicon carbide in Example 3 was replaced with the polyurethane-coated silicon carbide obtained in Preparation Example 10, and the rest of the preparation process was the same as in Example 3.

[0041] Comparative Example 2: A method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials, specifically including the following steps: The polyurethane-coated silicon carbide in Example 3 was replaced with the polyurethane-coated silicon carbide obtained in Preparation Example 11, and the rest of the preparation process was the same as in Example 3.

[0042] Comparative Example 3: A method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials, specifically including the following steps: The polyurethane-coated silicon carbide in Example 3 was replaced with the polyurethane-coated silicon carbide obtained in Preparation Example 12, and the rest of the preparation process was the same as in Example 3.

[0043] Comparative Example 4: A method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials, specifically including the following steps: The polyurethane-coated silicon carbide in Example 3 was replaced with the polyurethane-coated silicon carbide obtained in Preparation Example 13, and the rest of the preparation process was the same as in Example 3.

[0044] Comparative Example 5: A method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials, specifically including the following steps: 21 parts by weight of the polyurethane-coated silicon carbide obtained in Preparation Example 9, 23 parts by weight of the curing agent composition (composed of DMP-30 and methylhexahydrophthalic anhydride in a weight ratio of 10:40) and 36 parts by weight of the epoxy resin composition (composed of phenolic epoxy resin of type SQPN-051 and epoxy resin E-44 in a weight ratio of 1:4) were weighed, mixed, heated to 50°C, and then subjected to vacuum degassing treatment for 40 min. After that, the mixture was heated to 100°C and cured for 3 h to obtain a thermally conductive epoxy resin molding compound.

[0045] Comparative Example 6: A method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials, specifically including the following steps: The polyurethane-coated silicon carbide in Example 3 was replaced with the modified silicon carbide obtained in Preparation Example 3, and the rest of the preparation process was the same as in Example 3.

[0046] According to GB / T 29313-2012 Test Method for Thermal Conductivity of Electrical Insulation Materials, the thermal conductivity of the thermally conductive epoxy resin molding compounds obtained in Examples 1-3 and Comparative Examples 1-5 was tested, and the results are shown in Table 1 below.

[0047] Table 1 Thermal conductivity

[0048] According to GB / T 1843-2008 Determination of Impact Strength of Plastic Cantilever Beams, the impact strength of the thermally conductive epoxy resin molding compounds obtained in Examples 1-3 and Comparative Examples 1-5 was tested. The sample size was 80mm×10mm×4mm, with a notch of 2mm. The results are shown in Table 2 below.

[0049] Table 2 Impact Strength

[0050] The following conclusions can be drawn from the test results in Tables 1 and 2 above: (1) As can be seen from Examples 1 to 3, the thermally conductive epoxy resin molding compound obtained by mixing and curing polyurethane-coated silicon carbide, curing agent composition and epoxy resin composition has good thermal conductivity and mechanical properties.

[0051] (2) Comparative Example 1 shows that the thermal conductivity and mechanical properties of the prepared thermally conductive epoxy resin molding compound are poor. This may be because the silane coupling agent KH560 lacks the reactive amino group compared to γ-aminopropyltriethoxysilane, making it difficult to be coated by polyurethane polymerization, thus making it difficult to improve the interfacial bonding between silicon carbide and epoxy resin, resulting in poor performance.

[0052] (3) Comparative Example 2 shows that the thermal conductivity and mechanical properties of the prepared thermally conductive epoxy resin molding compound are poor. This may be because the hydrolysis time of γ-aminopropyltriethoxysilane is too long, which makes it easy to self-polymerize and form a polysiloxane structure, making it difficult to modify silicon carbide, and ultimately resulting in poor performance of the thermally conductive epoxy resin molding compound.

[0053] (4) Comparative Example 3 shows that the thermal conductivity and mechanical properties of the prepared thermally conductive epoxy resin molding compound are poor. This may be because in this system, the silicon carbide with too small a particle size is further processed, and the plasma treatment effect on the silicon carbide is poor, resulting in poor pretreatment effect on the silicon carbide surface, which in turn leads to poor performance of the final prepared thermally conductive epoxy resin molding compound.

[0054] (5) Comparative Example 4 shows that the thermal conductivity and mechanical properties of the prepared thermally conductive epoxy resin molding compound are poor. This may be because, in this system, although the pretreated silicon carbide obtained by plasma oxidation treatment has active surfaces with oxygen-containing groups such as hydroxyl groups, if it is not further dispersed, the agglomeration phenomenon may still be obvious, affecting its uniform dispersion performance in the polymerization reaction, and thus affecting the preparation of polyurethane-coated silicon carbide, resulting in poor performance of the final prepared thermally conductive epoxy resin molding compound.

[0055] (6) Comparative Example 5 shows that the thermal conductivity and mechanical properties of the prepared thermally conductive epoxy resin molding compound are poor. This may be because in this system, DMP-30 in the curing agent composition is used as a curing accelerator. If too much is used, it may cause the surface layer to cure too quickly, while the inner layer is not fully cross-linked and cured, and the resin matrix is ​​damaged, resulting in poor performance of the final prepared thermally conductive epoxy resin molding compound.

[0056] (7) Comparative Example 6 shows that the thermal conductivity and mechanical properties of the prepared thermally conductive epoxy resin molding compound are poor. This may be because in this system, there is no polyurethane coating treatment and modified silicon carbide is used directly. The resin matrix may have excessive brittle stress, resulting in poor performance of the final thermally conductive epoxy resin molding compound.

[0057] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials, characterized in that, The preparation method includes the following steps: Polyurethane-coated silicon carbide, curing agent composition and epoxy resin composition are mixed in a weight ratio of 15~21:20~23:30~36, then vacuum degassed and then heated to 90℃~100℃ for 3h~4h to obtain thermally conductive epoxy resin molding compound.

2. The method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials according to claim 1, characterized in that, The method for preparing polyurethane-coated silicon carbide includes the following steps: Modified silicon carbide, dimethylolpropionic acid, EDC hydrochloride and 1-hydroxybenzotriazole were mixed in a weight ratio of 1:10~13:15~18:15~18 and reacted at 25℃ for 20h~24h to obtain dihydroxy modified silicon carbide; Dihydroxy-modified silicon carbide, diisocyanate, polypolyol and dibutyltin dilaurate are mixed in a weight ratio of 10:20~30:10~15:0.06~0.07 and heated to 80℃~85℃ for 2h~3h to obtain polyurethane-coated silicon nitride.

3. The method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials according to claim 2, characterized in that, The method for preparing the modified silicon carbide includes the following steps: Pretreated silicon carbide is obtained by plasma treatment. A hydrolysate is obtained by mixing silane coupling agent, water, and anhydrous ethanol in a weight ratio of 10:60~68:20~28 and pre-hydrolyzing the mixture. Modified silicon carbide is obtained by mixing and dispersing pretreated silicon carbide and hydrolysate.

4. The method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials according to claim 3, characterized in that, The conditions for plasma treatment include an oxygen plasma source, a gas flow rate of 200 mL / min to 250 mL / min, a processing power of 150 W to 170 W, and a processing time of 100 s to 120 s.

5. The method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials according to claim 3, characterized in that, The silane coupling agent includes γ-aminopropyltrimethoxysilane or γ-aminopropyltriethoxysilane.

6. The method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials according to claim 3, characterized in that, The conditions for the mixed pre-hydrolysis include a pre-hydrolysis pH of 4 to 4.5, a pre-hydrolysis time of 40 to 50 minutes, and a pre-hydrolysis temperature of 30°C to 40°C.

7. The method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials according to claim 3, characterized in that, The weight ratio of the pretreated silicon carbide to the silane coupling agent is 5-6:

1.

8. The method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials according to claim 3, characterized in that, The conditions for the mixing and dispersion reaction of the pretreated silicon carbide and the hydrolysate include a reaction temperature of 60℃~70℃ and a reaction time of 80min~90min.

9. The method for preparing a thermally conductive epoxy resin molding compound for encapsulation materials according to claim 1, characterized in that, The epoxy resin composition is composed of phenolic epoxy resin and epoxy resin E-44 in a weight ratio of 1:

4.

10. A thermally conductive epoxy resin encapsulant prepared by the preparation method of a thermally conductive epoxy resin encapsulant for encapsulation materials according to any one of claims 1 to 9.

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