Epoxy molding compound and preparation method thereof

Abstract

The epoxy molding compound is prepared from the following components in parts by mass: 38 to 89 parts of negative thermal expansion filler, 30 to 55 parts of heat-conducting filler, 5 to 30 parts of epoxy resin, 2 to 15 parts of a curing agent, 0.1 to 2 parts of a curing accelerator, 0.1 to 5 parts of a coupling agent, 0.1 to 0.6 part of a release agent, 0.1 to 0.6 part of a coloring agent and 0.1 to 0.4 part of a degassing agent. The negative thermal expansion filler is Zn < 1.5 > Ni < 0.5 > P2O7 and Cu < 2 > PVO < 7 >, and the volume ratio of the Zn < 1.5 > Ni < 0.5 > P2O7 to the Cu < 2 > PVO < 7 > is (10-25): (15-30). A controllable thermal expansion compensation mechanism is constructed through double negative thermal expansion fillers, the overall thermal expansion coefficient of the system is remarkably reduced by utilizing the difference and offset effect of Zn1. 5Ni0. 5P2O7 and Cu2PVO7 with a resin matrix and other fillers in thermal expansion behavior, the thermal expansion compensation amplitude is larger than that of a single negative expansion filler system, and the thermal expansion coefficient of the system is greatly improved. Meanwhile, due to the addition of the double negative expansion filler, thermal expansion is regulated and controlled, the accumulation mode of the heat-conducting filler is changed, the heat-conducting filler is easier to form a continuous heat path under the limitation of a negative expansion filler framework, and considerable heat conductivity is allowed to be maintained under the condition of low addition amount of the heat-conducting filler.

Description

Technical Field

[0001] This invention belongs to the field of encapsulation materials technology, specifically relating to an epoxy molding compound and its preparation method. Background Technology

[0002] The chip manufacturing process typically includes three main stages: chip design, wafer fabrication, and packaging and testing. Over the past few decades, improvements in chip performance have primarily relied on advancements in wafer fabrication processes, centered around advanced lithography. With the continuous evolution of lithography technology, feature sizes have shrunk from the hundreds of nanometers to the current 2nm node. However, the traditional scaling path is gradually approaching its physical limits, and the industry has generally entered the "post-Moore's Law era." Against this backdrop, to perpetuate Moore's Law and further improve the system-level performance of chips, advanced packaging technologies (such as 2.5D packaging, 3D stacked packaging, and wafer-level packaging) have become key drivers for the industry's continued development.

[0003] Meanwhile, the electronics and information industry as a whole is rapidly evolving towards miniaturization, high integration, and high power density. This leads to a significant increase in the heat generated by chips during operation, placing more stringent demands on the overall performance of packaging materials. Packaging materials must not only fulfill the following functions: 1. Provide structural and mechanical protection, isolating them from moisture, oxygen, and chemical environments; 2. Achieve efficient thermal management, promptly dissipating the heat generated by the chip and electronic devices; 3. Maintain dimensional stability during thermal cycling, with their coefficient of thermal expansion (CTE) matching that of the silicon chip as closely as possible to avoid warping, interface debonding, and even device failure caused by alternating hot and cold temperatures.

[0004] Among various packaging material systems, plastic packaging remains the most widely used packaging form in the industry due to its low cost, mature technology, and high reliability. Epoxy molding compounds (EMC) based on epoxy resin have long dominated the integrated circuit packaging field due to their excellent electrical insulation, good moldability, high mechanical strength, moisture and chemical resistance, and low cost. However, epoxy resin itself still has two key shortcomings: 1. Extremely low thermal conductivity, making it difficult to meet the ever-increasing heat dissipation requirements of high-power devices; 2. High coefficient of thermal expansion, significantly different from key chip materials such as silicon, which easily generates large thermal stress during thermal cycling, leading to failure problems such as package cracking and interface debonding.

[0005] To address these shortcomings, existing epoxy resin molding compounds typically adjust the coefficient of thermal expansion (CTE) by filling with conventional inorganic fillers such as silica powder. However, since these inorganic fillers are themselves positively expanding materials, and their filler content is limited by factors such as flowability and moldability, the overall CTE of the system remains significantly higher than that of the encapsulated components such as the chip and leadframe. Under thermal cycling or power surge conditions, this results in substantial thermal mismatch stress between the two components, easily leading to reliability issues such as package warpage, interface delamination, and crack initiation. In other words, existing molding compounds still have shortcomings in terms of dimensional stability and thermal cycling reliability.

[0006] To improve the heat dissipation performance of devices, inorganic thermally conductive fillers such as alumina, silicon nitride, and aluminum nitride are often introduced into epoxy resin systems. However, most of these thermally conductive fillers also exhibit positive thermal expansion behavior, and the improvement in thermal conductivity usually depends on a high filling ratio. As a result, within a limited formulation window, on the one hand, the improvement in the system's thermal conductivity is limited, and the heat accumulated inside the device is still difficult to release in time; on the other hand, the introduction of thermally conductive fillers further increases or fails to effectively reduce the overall coefficient of thermal expansion of the system, exacerbating the thermal expansion mismatch between the system and the chip and substrate. In other words, existing epoxy molding compounds generally suffer from the contradiction of "limited improvement in thermal conductivity and difficulty in achieving low thermal expansion" in engineering applications.

[0007] In summary, existing technologies primarily rely on positive thermal expansion inorganic fillers to regulate thermal expansion and thermal conductivity, making it difficult to simultaneously achieve: on the one hand, significantly reducing the system's coefficient of thermal expansion to alleviate thermal mismatch stress; and on the other hand, maintaining a certain level of thermal conductivity to improve package heat dissipation. Therefore, existing technologies still have significant shortcomings in the synergistic regulation of low thermal expansion and thermal conductivity, and cannot fully meet the comprehensive requirements of high-reliability electronic packaging for dimensional stability and heat dissipation capabilities. Summary of the Invention

[0008] To overcome the problems of high thermal expansion coefficient, limited improvement in thermal conductivity, and difficulty in synergistic optimization of the two in the prior art, the present invention aims to provide an epoxy molding compound and its preparation method, which improves thermal conductivity while reducing the thermal expansion coefficient.

[0009] This invention is achieved through the following technical solution: An epoxy molding compound, by weight, comprises 38-89 parts of negative thermal expansion filler, 30-55 parts of thermally conductive filler, 5-30 parts of epoxy resin, 2-15 parts of curing agent, 0.1-2 parts of curing accelerator, 0.1-5 parts of coupling agent, 0.1-0.6 parts of release agent, 0.1-0.6 parts of colorant, and 0.1-0.4 parts of degassing agent; wherein the negative thermal expansion filler is Zn. 1.5 Ni 0.5 P2O7 and Cu2PVO7, the Zn 1.5 Ni0.5 The volume ratio of P2O7 to Cu2PVO7 is 10-25:15-30.

[0010] Furthermore, the particle size range of the negative thermal expansion filler is 0.5-150μm, and the particle size range of the thermally conductive filler is 0.5-225μm.

[0011] Furthermore, the thermally conductive filler is Al2O3, AlN, SiC, BN, or diamond.

[0012] Further, the epoxy resin is at least one of o-cresol epoxy resin, biphenyl type epoxy resin, aralkyl type epoxy resin, ester ring type epoxy resin, heterocyclic type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, dicyclopentadiene type epoxy resin, naphthalene ring type epoxy resin, or multifunctional type epoxy resin.

[0013] Furthermore, the curing agent is at least one of amine curing agents, acid anhydride curing agents, phenolic resin curing agents, and their modified products; the curing accelerator is at least one of tertiary amines, imidazoles, organophosphorus compounds, quaternary ammonium salts, quaternary phosphonium salts, metal complexes, and their derivatives.

[0014] Further, the coupling agent is at least one selected from γ-aminopropyltriethoxysilane (KH-550), N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792), γ-aminopropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), and γ-methacryloyloxypropyltrimethoxysilane (KH-570).

[0015] Furthermore, the release agent is at least one of palm wax, paraffin wax, polyethylene / olefin synthetic wax, or oxidized polyethylene synthetic wax, and the colorant is at least one of carbon black, titanium dioxide, or zinc oxide.

[0016] Furthermore, the degassing agent is at least one of polysiloxane degassing agents, modified polysiloxane degassing agents, and non-organosilicon degassing agents.

[0017] A method for preparing an epoxy molding compound includes the following steps: S1. Heat and melt the epoxy resin and curing agent according to the ratio at 150-200℃ for 2-5 minutes to obtain a uniform and transparent liquid; S2. Negative expansion packing Zn 1.5 Ni 0.5 P2O7, Cu2PVO7, thermally conductive filler, mold release agent, and colorant are mixed in the specified proportions to obtain a uniform powder mixture. S3. Mix the uniform transparent liquid obtained in step S1 with the powder mixture obtained in step S2, add an organic solvent to make the uniform transparent liquid and the powder mixture evenly dispersed, and add a degassing agent and a coupling agent to mix evenly; when the temperature drops to below 120°C, add a curing accelerator and mix evenly. S4. Place the material obtained in step S3 into a vacuum degassing machine, mechanically mix at 500-1000 r / min for 2-5 min, vacuum degas at 800-1200 r / min for 10-15 min, then remove it from the vacuum degassing machine, spread it evenly and place it in a vacuum oven at 60-70℃ for 15-90 min for degassing treatment. S5. Place the material obtained in step S4 into a mold, pre-press 5-10 kPa / 2-5 min, hot press 170-180℃ / 10-30 min to form the sample. The curing procedure for the formed sample is as follows: heat up to 100-120℃ and hold for 2-3 h, heat up to 140-150℃ and hold for 2-3 h, heat up to 170-180℃ and hold for 2-3 h, and finally cool to room temperature to obtain epoxy molding compound.

[0018] Furthermore, the organic solvent is one of acetone, dichloromethane, ethyl acetate, and diethyl ether.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention constructs a controllable thermal expansion compensation mechanism using "double negative thermal expansion filler," utilizing Zn 1.5 Ni 0.5 The differences and offsetting effects of the thermal expansion behavior of P2O7 and Cu2PVO7 with the resin matrix and other fillers significantly reduce the overall thermal expansion coefficient of the system, resulting in a CTE1 of 2.17 × 10⁻⁶. -6 The thermal expansion compensation is greater than that of a single negative expansion filler system, and the expansion curves in different temperature zones can be adjusted, forming a "wide-temperature-zone expansion suppression" effect. This broadens the formulation window, allowing for compensation of the significant positive expansion behavior of epoxy resin with a relatively low amount of negative thermal expansion filler, thus reserving some formulation space for introducing other functional fillers. This invention, by rationally setting the ratio of dual negative thermal expansion fillers to thermally conductive fillers, ensures that the compensation effect of negative thermal expansion precisely offsets the positive thermal expansion of the thermally conductive filler. Simultaneously, the addition of dual negative expansion fillers not only regulates thermal expansion but also alters the stacking pattern of the thermally conductive filler. Under the constraint of the negative expansion filler skeleton, the thermally conductive filler more easily forms a continuous thermal path, allowing for the maintenance of a comparable thermal conductivity (2.48 W / (m·K) in this invention) with a relatively low amount of thermally conductive filler. This invention improves heat dissipation performance without increasing the filler ratio. This invention overcomes the industry contradiction of being unable to simultaneously achieve "low thermal expansion" and "high thermal conductivity," effectively reducing the thermal expansion mismatch stress between the packaging material and the chip, lead frame, etc., during device operation and thermal cycling, improving the dimensional stability and thermal cycling reliability of the package.

[0020] This invention reduces the coefficient of thermal expansion (CTE1 of this invention: 2.17 × 10⁻⁶). -6 / K) to matching silicon chip (2.6×10 -6 With a high thermal conductivity (2.48 W / (m·K) in this invention), the present invention breaks the "performance coupling contradiction" that is currently prevalent in the industry. The thermal conductivity of this invention is close to or even lower than that of silicon chips (2.6 × 10⁻⁶ W / (m·K)). -6 The range of / K) can significantly reduce package warpage, significantly reduce thermal stress at the chip / substrate interface, and improve thermal cycling reliability. Attached Figure Description

[0021] Figure 1 This is a comparison chart of the thermal expansion curves of Examples 1-2 and Comparative Examples 1-3; Figure 2 This is a comparison chart of the thermal conductivity of Examples 1-2 and Comparative Examples 1-3. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0023] This invention provides an epoxy molding compound, the main components and specific weight percentages of which are: 38-89 parts of negative thermal expansion filler, 30-55 parts of thermally conductive filler, 5-30 parts of epoxy resin, 2-15 parts of curing agent, 0.1-2 parts of curing accelerator, 0.1-5 parts of coupling agent, 0.1-0.6 parts of release agent, 0.1-0.6 parts of colorant, and 0.1-0.4 parts of degassing agent; the specific chemical formula of the negative thermal expansion filler is: Zn 1.5 Ni 0.5 P2O7 and Cu2PVO7; the negative thermal expansion filler Zn 1.5 Ni 0.5 The volume ratio of P2O7 and Cu2PVO7 in the epoxy molding compound is 10-25:15-30; the particle size range of the negative thermal expansion filler is 0.5-150μm, and the particle size range of the thermally conductive filler is 0.5-225μm.

[0024] The thermally conductive filler is a commonly used thermally conductive filler in the field, including but not limited to: Al2O3, AlN, SiC, BN, and diamond.

[0025] The epoxy resin mentioned is a commonly used epoxy resin in the field, including but not limited to one or more of o-cresol epoxy resin, biphenyl type epoxy resin, aralkyl type epoxy resin, ester ring type epoxy resin, heterocyclic type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, dicyclopentadiene type epoxy resin, naphthalene ring type epoxy resin and multifunctional group type epoxy resin.

[0026] The curing agent is a commonly used epoxy resin curing agent in the field, including but not limited to one or more of amine curing agents, acid anhydride curing agents, phenolic resin curing agents, and their modified products. Among them, it includes, but is not limited to, aliphatic amines: such as diethylenetriamine, triethylenetetramine, and hexamethylenediamine; aromatic amines: such as m-phenylenediamine, diaminodiphenylmethane (DDM), and diaminodiphenyl sulfone (DDS); and modified amines such as polyetheramines and ketimides. Acid anhydrides: methyltetrahydrophthalic anhydride, methylnadic anhydride, phthalic anhydride, and tetrahydrophthalic anhydride. Phenolic resins: methyl phenolic resins and linear phenolic resins.

[0027] The curing accelerator mentioned is a commonly used epoxy resin curing accelerator in the field, including but not limited to tertiary amines, imidazoles, organophosphorus compounds, quaternary ammonium salts, quaternary phosphorus salts, metal complexes and their derivatives such as: 2-methylimidazole, 2-ethyl-4-methylimidazole, triphenylphosphine, triethanolamine, benzyldimethylamine, dimethylaminomethylphenol, iron acetylacetone, zinc acetylacetone, manganese acetylacetone, and cobalt acetylacetone, one or more of these.

[0028] The coupling agent is a silane coupling agent commonly used in the field to improve the interfacial compatibility between inorganic fillers and organic resins. In preferred embodiments, it includes, but is not limited to, one or more of γ-aminopropyltriethoxysilane (KH-550), N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792), γ-aminopropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), and γ-methacryloyloxypropyltrimethoxysilane (KH-570).

[0029] The release agent is a commonly used release agent in the field, including but not limited to one or more of palm wax, paraffin wax, polyethylene / olefin synthetic wax or oxidized polyethylene synthetic wax.

[0030] The colorant mentioned is a commonly used colorant in the field, including but not limited to one or more of carbon black, titanium dioxide, and zinc oxide.

[0031] The degassing agent is at least one of polysiloxane degassing agents, modified polysiloxane degassing agents, and non-organosilicon degassing agents.

[0032] A method for preparing an epoxy molding compound, specifically including the following steps: S1. Heat and melt the epoxy resin and curing agent according to the ratio at 150-200℃ for 2-5 minutes to obtain a uniform and transparent liquid; S2. Negative expansion packing Zn 1.5 Ni 0.5 P2O7, Cu2PVO7, thermally conductive filler, mold release agent, and colorant are mixed in the specified proportions to obtain a uniform powder mixture. S3. Mix the uniform transparent liquid obtained in step S1 with the powder mixture obtained in step S2, add an organic solvent to make the uniform transparent liquid and the powder mixture evenly dispersed, and add a degassing agent and a coupling agent to mix evenly; when the temperature drops to below 120°C, add a curing accelerator and mix evenly. S4. Place the material obtained in step S3 into a vacuum degassing machine, mechanically mix at 500-1000 r / min for 2-5 min, vacuum degas at 800-1200 r / min for 10-15 min, then remove it from the vacuum degassing machine, spread it evenly and place it in a vacuum oven at 60-70℃ for 15-90 min for degassing treatment. S5. Place the material obtained in step S4 into a mold, pre-press 5-10 kPa / 2-5 min, hot press 170-180℃ / 10-30 min to form the sample. The curing procedure for the formed sample is as follows: heat up to 100-120℃ and hold for 2-3 h, heat up to 140-150℃ and hold for 2-3 h, heat up to 170-180℃ and hold for 2-3 h, and finally cool to room temperature to obtain epoxy molding compound.

[0033] The organic solvent is one of acetone, dichloromethane, ethyl acetate, and diethyl ether.

[0034] Example 1 The raw material for preparing epoxy molding compound is negative expansion filler Zn. 1.5 Ni 0.5 The resin consists of P2O7 and Cu2PVO7, with Al2O3 (average particle size 1 μm) as the thermally conductive filler, a trifunctional high-temperature resistant epoxy resin, diaminodiphenylmethane (DDM) as the curing agent, iron acetylacetonate as the accelerator, γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560) as the coupling agent, palm wax as the release agent, carbon black as the colorant, and polyether-modified heptamethyltrisiloxane as the degassing agent. Specific contents are shown in Table 1.

[0035] A method for preparing an epoxy molding compound includes the following steps: S1. Heat and melt the epoxy resin and curing agent according to the ratio at 150-200℃ for 2-5 minutes to obtain a uniform and transparent liquid; S2. Negative expansion packing Zn 1.5 Ni 0.5 P2O7, Cu2PVO7, thermally conductive filler, mold release agent, and colorant are mixed in the specified proportions to obtain a uniform powder mixture. S3. Mix the uniform transparent liquid obtained in step S1 with the powder mixture obtained in step S2, add an appropriate amount of diethyl ether to make the uniform transparent liquid and the powder mixture evenly dispersed, and add a degassing agent and a coupling agent, and mix evenly; when the temperature drops to below 120°C, add a curing accelerator and mix evenly. S4. Place the material obtained in step S3 into a vacuum degassing machine, mechanically mix at 1000 r / min for 2 min, vacuum degas at 1000 r / min for 15 min, then remove it from the vacuum degassing machine, spread it evenly and place it in a vacuum oven at 70°C for 15 min for degassing. S5. Place the material obtained in step S4 into a special mold, pre-press 10 kPa / 2 min, hot press 175℃ / 15 min to form, and the curing procedure of the sample after molding is as follows: heat up to 120℃ and keep warm for 2 h, heat up to 150℃ and keep warm for 2 h, heat up to 180℃ and keep warm for 3 h, and finally cool to room temperature to obtain epoxy molding compound.

[0036] Example 2: The raw material for preparing epoxy molding compound S2 is negative expansion filler Zn. 1.5 Ni 0.5 The resin consists of P2O7 and Cu2PVO7, with Al2O3 (average particle size 1 μm) as the thermally conductive filler, a trifunctional high-temperature resistant epoxy resin, diaminodiphenylmethane (DDM) as the curing agent, iron acetylacetonate as the accelerator, γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560) as the coupling agent, palm wax as the release agent, carbon black as the colorant, and polyether-modified heptamethyltrisiloxane as the degassing agent. Specific contents are shown in Table 1.

[0037] The epoxy molding compound was prepared according to the preparation method in Example 1.

[0038] Comparative Example 1: Comparative Example 1 was prepared in the same manner as in Example 1, except that angular fused silica micropowder (SiO2) was used instead of negative thermal expansion material filler and thermally conductive filler, with a particle size of 300-400 nm.

[0039] Comparative Example 2: Comparative Example 2 was prepared in the same manner as in Example 1, except that negative thermal expansion filler and thermally conductive filler were not used. Instead, the epoxy resin was cured to prepare the sample, and its huge positive expansion phenomenon was observed.

[0040] Comparative Example 3: Comparative Example 1 was prepared in the same manner as in Example 1, except that only one type of negative thermal expansion filler, Zn, was used. 1.5 Ni 0.5 P2O7, without using other fillers.

[0041] Table 1 Table 2 shows the average linear thermal expansion coefficient (α) of Examples 1-2 and Comparative Examples 1-3 in different temperature ranges. L(Data). CTE1 and CTE2 represent the average linear thermal expansion coefficients for 25-180℃ and 180-200℃ respectively, where 180℃ is the glass transition temperature of the epoxy molding compound; CTE3-5 are based on... Figure 1 The average linear thermal expansion coefficients for different temperature ranges (25-105℃, 105-145℃, 145-200℃) were obtained from the thermal expansion curves.

[0042] Table 2 By comparing the CTE1 and CTE2 test data of Examples 1-2 with those of Comparative Examples 1 and 2, it can be seen that the introduction of negative thermal expansion filler Zn... 1.5 Ni 0.5 P2O7 and Cu2PVO7 can significantly reduce the linear expansion behavior of epoxy resin systems, with effects that are significantly better than those of traditional SiO2 fillers. In particular, Example 1 achieved a CTE1 value of 2.17 × 10⁻⁶. -6 / K, and the coefficient of thermal expansion of silicon chips (approximately 2.6 × 10⁻⁶). -6 The high degree of matching between the Zn and K atoms helps reduce interfacial stress caused by thermal mismatch during encapsulation, demonstrating good application potential. Meanwhile, the negative thermal expansion filler Zn... 1.5 Ni 0.5 The introduction of P2O7 and Cu2PVO7 also significantly suppressed thermal expansion after the glass transition temperature (CTE2). Compared with Comparative Example 1 using SiO2 filler, the CTE2 of Example 1 was reduced to 12.11 × 10⁻⁶. -6 / K, which obviously improves the temperature resistance and reliability of epoxy molding compounds.

[0043] By comparing the CTE3 test data of Examples 1-2 with those of Comparative Examples 1 and 3, or Figure 1 The thermal expansion curves show that only a single negative thermal expansion filler (Zn) is used. 1.5 Ni 0.5 P2O7 and Cu2PVO7) cannot achieve the low thermal expansion properties of Examples 1-2; the CTE3 of Comparative Example 3 is 11.63 × 10⁻⁶. -6 / K is higher than that of Examples 1-2 using two types of negative expansion fillers, but not as low as that of Comparative Example 1 using SiO2 filler, and therefore does not offer any application advantages. The corresponding conclusion can also be drawn from... Figure 1 Therefore, the synergistic use of two negative expansion packing materials, Zn, is the optimal approach. 1.5 Ni 0.5 P2O7 and Cu2PVO7 are important. Moreover, the low thermal expansion characteristics shown in Examples 1 and 2 can only be achieved when the two fillers work synergistically in an appropriate ratio, so that the expansion behavior of the composite material is highly matched with the thermal expansion coefficient of the silicon chip, thus showing excellent application potential.

[0044] Figure 2 The room temperature thermal conductivity test results of Examples 1-2 and Comparative Examples 1-3 are shown. As can be seen from the figures, the room temperature thermal conductivity of pure epoxy resin in Comparative Example 2 is only 0.21 W / (m·K). After adding fillers (whether negative thermal expansion fillers or SiO2 fillers), the thermal conductivity of the composite system is significantly improved. Furthermore, the thermal conductivity of Examples 1 and 2 prepared in this invention is higher than that of Comparative Example 3 with only Zn added. 1.5 Ni 0.5 P2O7, compared to the thermal conductivity of the filler material and thermally conductive filler replaced by angular fused silica powder (SiO2) in Comparison 1.

[0045] Compared with existing technologies, this invention achieves a high thermal conductivity gain while significantly reducing the amount of thermally conductive filler. Existing commercial epoxy molding compounds typically require 85-95 wt.% alumina filler; however, with alumina filler particle size levels roughly consistent, this invention achieves a thermal conductivity increase of approximately 2.48 W / (m·K) in epoxy molding compounds using only 35-45 wt.% alumina thermally conductive filler. This effect is mainly attributed to: the introduction of negative thermal expansion filler effectively suppresses the thermal expansion behavior of the resin matrix, reduces the interfacial thermal mismatch stress between filler and matrix, and between filler fillers, which facilitates the formation of a more stable and continuous heat conduction path in the system; simultaneously, the synergistic effect of multiple fillers improves the internal microstructure of the system, and the thermally conductive filler, constrained by the negative expansion filler framework, more easily forms a continuous thermal pathway, improving the utilization efficiency of the thermally conductive filler, thus achieving an effective increase in thermal conductivity without relying on ultra-high filler content. Therefore, this invention breaks through the limitation of "high thermal conductivity depends on high filler content" in the prior art, and significantly expands the formulation design space of epoxy molding compounds.

[0046] Example 3 An epoxy molding compound, by weight, comprises 38 parts of negative thermal expansion filler, 30 parts of thermally conductive filler, 5 parts of epoxy resin, 2 parts of curing agent, 0.1 parts of curing accelerator, 0.1 parts of coupling agent, 0.1 parts of release agent, 0.1 parts of colorant, and 0.1 parts of degassing agent; wherein the negative thermal expansion filler is Zn. 1.5 Ni 0.5 P2O7 and Cu2PVO7, the Zn 1.5 Ni 0.5 The volume ratio of P2O7 to Cu2PVO7 is 10:30; The particle size range of the negative thermal expansion filler is 0.5-50μm, and the particle size range of the thermally conductive filler is 0.5-75μm.

[0047] The thermally conductive filler is AlN, the epoxy resin is o-cresol epoxy resin, the curing agent is diethylenetriamine and triethylenetetramine among amine curing agents; and the curing accelerator is 2-methylimidazole among imidazoles. The coupling agent is γ-aminopropyltriethoxysilane (KH-550); the release agent is palm wax; the colorant is carbon black; and the degassing agent is a polysiloxane degassing agent.

[0048] The preparation method of the above-mentioned epoxy molding compound includes the following steps: S1. Heat and melt the epoxy resin and curing agent at 150°C for 2 minutes according to the specified ratio to obtain a uniform and transparent liquid; S2. Negative expansion packing Zn 1.5 Ni 0.5 P2O7, Cu2PVO7, thermally conductive filler, mold release agent, and colorant are mixed in the specified proportions to obtain a uniform powder mixture. S3. Mix the uniform transparent liquid obtained in step S1 with the powder mixture obtained in step S2, add an appropriate amount of acetone to make the uniform transparent liquid and the powder mixture evenly dispersed, and add degassing agent and coupling agent, and mix evenly; after the temperature drops to below 120℃, add curing accelerator and mix evenly. S4. Place the material obtained in step S3 into a vacuum degassing machine, mechanically mix at 500 r / min for 2 min, vacuum degas at 800 r / min for 10 min, then remove it from the vacuum degassing machine, spread it evenly and place it in a vacuum oven at 60°C for 15 min for degassing. S5. Place the material obtained in step S4 into the mold, pre-press 5 kPa / 2 min, hot press 170℃ / 10 min to form, and the curing procedure of the sample after forming is as follows: heat up to 100℃ and keep warm for 2 h, heat up to 140℃ and keep warm for 2 h, heat up to 170℃ and keep warm for 2 h, and finally cool to room temperature to obtain epoxy molding compound.

[0049] Example 4 An epoxy molding compound, by weight, comprises 60 parts of negative thermal expansion filler, 40 parts of thermally conductive filler, 18 parts of epoxy resin, 9 parts of curing agent, 1 part of curing accelerator, 2 parts of coupling agent, 0.4 parts of release agent, 0.4 parts of colorant, and 0.2 parts of degassing agent; wherein the negative thermal expansion filler is Zn. 1.5 Ni 0.5 P2O7 and Cu2PVO7, the Zn 1.5 Ni 0.5 The volume ratio of P2O7 to Cu2PVO7 is 20:20; The particle size range of the negative thermal expansion filler is 50-100μm, and the particle size range of the thermally conductive filler is 50-100μm.

[0050] The thermally conductive filler is SiC; the epoxy resin is a biphenyl-type epoxy resin and an aralkyl-type epoxy resin; the curing agent is methyltetrahydrophthalic anhydride, a type of acid anhydride curing agent; the curing accelerator is triethanolamine, a type of tertiary amine; the coupling agent is N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792) and γ-aminopropyltrimethoxysilane; the release agent is paraffin wax; the colorant is titanium dioxide; and the degassing agent is a modified polysiloxane degassing agent.

[0051] The preparation method of the above-mentioned epoxy molding compound includes the following steps: S1. Heat and melt the epoxy resin and curing agent at 180°C for 3 minutes according to the specified ratio to obtain a uniform and transparent liquid; S2. Negative expansion packing Zn 1.5 Ni 0.5 P2O7, Cu2PVO7, thermally conductive filler, mold release agent, and colorant are mixed in the specified proportions to obtain a uniform powder mixture. S3. Mix the uniform transparent liquid obtained in step S1 with the powder mixture obtained in step S2, add an appropriate amount of dichloromethane to make the uniform transparent liquid and the powder mixture evenly dispersed, and add a degassing agent and a coupling agent, and mix evenly; when the temperature drops to below 120°C, add a curing accelerator and mix evenly. S4. Place the material obtained in step S3 into a vacuum degassing machine, mechanically mix at 800 r / min for 3 min, vacuum degas at 1000 r / min for 12 min, then remove it from the vacuum degassing machine, spread it evenly and place it in a vacuum oven at 65°C for 60 min for degassing treatment. S5. Place the material obtained in step S4 into the mold, pre-press 8 kPa / 3 min, hot press 175℃ / 25 min to form, and the curing procedure of the sample after forming is as follows: heat up to 110℃ and keep at 2.5 h, heat up to 145℃ and keep at 2.5 h, heat up to 175℃ and keep at 2.5 h, and finally cool to room temperature to obtain epoxy molding compound.

[0052] Example 5 An epoxy molding compound, by weight, comprises 89 parts of negative thermal expansion filler, 55 parts of thermally conductive filler, 30 parts of epoxy resin, 15 parts of curing agent, 2 parts of curing accelerator, 5 parts of coupling agent, 0.6 parts of release agent, 0.6 parts of colorant, and 0.4 parts of degassing agent; wherein the negative thermal expansion filler is Zn. 1.5 Ni 0.5 P2O7 and Cu2PVO7, the Zn 1.5 Ni 0.5 The volume ratio of P2O7 to Cu2PVO7 is 25:15; The particle size range of the negative thermal expansion filler is 80-150μm, and the particle size range of the thermally conductive filler is 150-225μm.

[0053] The thermally conductive filler is diamond; the epoxy resin is at least one of ester-cyclic epoxy resin, heterocyclic epoxy resin, bisphenol A epoxy resin, bisphenol F epoxy resin, dicyclopentadiene epoxy resin, naphthalene-cyclic epoxy resin, or multifunctional epoxy resin. The curing agent is at least one of hexamethylenediamine, m-phenylenediamine, diaminodiphenyl sulfone (DDS), polyetheramine, ketimine, methylnadic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, methyl phenolic resin, and linear phenolic resin.

[0054] The curing accelerator is at least one of 2-ethyl-4-methylimidazolium, triphenylphosphine, benzyldimethylamine, dimethylaminomethylphenol, zinc acetylacetonate, manganese acetylacetonate, and cobalt acetylacetonate.

[0055] The coupling agent is at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560) and γ-methacryloyloxypropyltrimethoxysilane (KH-570).

[0056] The release agent is at least one of polyethylene / olefin synthetic wax or oxidized polyethylene synthetic wax, and the colorant is at least one of zinc oxide.

[0057] The degassing agent is a non-organosilicon degassing agent.

[0058] A method for preparing an epoxy molding compound includes the following steps: S1. Heat and melt the epoxy resin and curing agent at 200°C for 5 minutes according to the specified ratio to obtain a uniform and transparent liquid; S2. Negative expansion packing Zn 1.5 Ni 0.5 P2O7, Cu2PVO7, thermally conductive filler, mold release agent, and colorant are mixed in the specified proportions to obtain a uniform powder mixture. S3. Mix the uniform transparent liquid obtained in step S1 with the powder mixture obtained in step S2, add an appropriate amount of ethyl acetate to make the uniform transparent liquid and the powder mixture evenly dispersed, and add a degassing agent and a coupling agent, and mix evenly; when the temperature drops to below 120°C, add a curing accelerator and mix evenly. S4. Place the material obtained in step S3 into a vacuum degassing machine, mechanically mix at 1000 r / min for 5 min, vacuum degas at 1200 r / min for 15 min, then remove it from the vacuum degassing machine, spread it evenly and place it in a vacuum oven at 70°C for 90 min for degassing treatment. S5. Place the material obtained in step S4 into the mold, pre-press 10 kPa / 5 min, hot press 180℃ / 30 min to form, and the curing procedure of the sample after molding is as follows: heat up to 120℃ and keep warm for 3 h, heat up to 150℃ and keep warm for 3 h, heat up to 180℃ and keep warm for 3 h, and finally cool to room temperature to obtain epoxy molding compound.

Claims

1. An epoxy encapsulant, characterized by, By mass parts, including negative thermal expansion filler 38-89 parts, thermal conductive filler 30-55 parts, epoxy resin 5-30 parts, curing agent 2-15 parts, curing accelerator 0.1-2 parts, coupling agent 0.1-5 parts, release agent 0.1-0.6 parts, colorant 0.1-0.6 parts, degassing agent 0.1-0.4 parts; the negative thermal expansion filler is Zn 1.5 Ni 0.5 P2O7 and Cu2PVO7, the Zn 1.5 Ni 0.5 P2O7 and Cu2PVO7 volume ratio is 10-25:15-30.

2. The epoxy encapsulating material according to claim 1, wherein The particle size of the negative thermal expansion filler ranges from 0.5 to 150 μm, and the particle size of the thermal conductive filler ranges from 0.5 to 225 μm.

3. The epoxy encapsulating material of claim 1, wherein the epoxy encapsulating material is characterized by: The thermal conductive filler is Al2O3, AlN, SiC, BN or diamond.

4. The epoxy encapsulating material of claim 1, wherein the epoxy encapsulating material is characterized by: The epoxy resin is at least one of ortho-cresol formaldehyde epoxy resin, biphenyl type epoxy resin, aralkyl type epoxy resin, ester ring type epoxy resin, heterocyclic type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, dicyclopentadiene type epoxy resin, naphthalene ring type epoxy resin or multifunctional type epoxy resin.

5. The epoxy encapsulating material of claim 1, wherein the epoxy encapsulating material is characterized by: The curing agent is at least one of amine curing agent, acid anhydride curing agent, phenolic resin curing agent and modified products thereof; and the curing accelerator is at least one of tertiary amine, imidazole, organic phosphine, quaternary ammonium salt, quaternary phosphonium salt, metal complex and derivatives thereof.

6. The epoxy encapsulating material of claim 1, wherein the epoxy encapsulating material is characterized by: The coupling agent is at least one of γ-aminopropyl triethoxysilane (KH-550), N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane (KH-792), γ-aminopropyl trimethoxysilane, γ-(2,3-epoxypropoxy) propyl trimethoxysilane (KH-560) and γ-methacryloyloxy propyl trimethoxysilane (KH-570).

7. The epoxy encapsulating material of claim 1, wherein the epoxy encapsulating material is a two-part epoxy encapsulating material. The release agent is at least one of palm wax, paraffin wax, polyethylene / olefin synthetic wax or oxidized polyethylene synthetic wax, and the colorant is at least one of carbon black, titanium dioxide or zinc oxide.

8. The epoxy encapsulating material of claim 1, wherein the epoxy encapsulating material is a two-part epoxy encapsulating material. The degassing agent is at least one of polysiloxane degassing agent, modified polysiloxane degassing agent and non-silicone degassing agent.

9. The method for preparing the epoxy molding compound according to any one of claims 1-8, characterized in that, The method comprises the following steps: S1. Heating and melting the epoxy resin and the curing agent at a ratio of 150-200 ℃ for 2-5 min to obtain a uniform transparent liquid; S2. The negative expansion filler Zn 1.5 Ni 0.5 P2O7 and Cu2PVO7, heat-conducting filler, release agent, colorant are mixed according to the proportion to obtain a uniform powder mixture; S3. Mixing the uniform transparent liquid obtained in step S1 with the powder obtained in step S2, adding an organic solvent to uniformly disperse the uniform transparent liquid and the powder mixture, and adding a degassing agent and a coupling agent and mixing uniformly; when the temperature is reduced to below 120 ℃, a curing accelerator is added and mixed uniformly; S4. Placing the material obtained in step S3 in a vacuum degassing machine, mechanically mixing at 500-1000 r / min for 2-5 min, and vacuum pumping at 800-1200 r / min for 10-15 min, then taking out from the vacuum degassing machine, uniformly spreading and placing in a vacuum oven at 60-70 ℃ for 15-90 min for degassing treatment; S5. Placing the material obtained in step S4 in a mold, pre-pressing at 5-10 kPa for 2-5 min, hot-pressing at 170-180 ℃ for 10-30 min for molding, and then performing a curing program of the sample: heating to 100-120 ℃ for 2-3 h, heating to 140-150 ℃ for 2-3 h, heating to 170-180 ℃ for 2-3 h, and finally cooling to room temperature to obtain an epoxy plastic sealing material.

10. The method for preparing the epoxy molding compound according to claim 9, characterized in that, The organic solvent is one of acetone, dichloromethane, ethyl acetate and diethyl ether.

Images