Preparation method of epoxy packaging material based on liquid metal morphology regulation and control

Abstract

The invention belongs to the field of manufacturing of heat-conducting thermosetting epoxy resin composite materials, and particularly discloses a preparation method of an epoxy packaging material based on liquid metal morphology regulation. Diamond micro-powder and two-dimensional lamellar heat-conducting filler are cooperatively compounded through covalent modification; liquid metal is subjected to chemical treatment through a modifier and a liquid cavitation effect, thermal interface'transition bridges' are formed between inorganic heat-conducting fillers with different dimensions and between the fillers and epoxy resin through morphology regulation and chemical grafting modification, heat transfer channels between the inorganic heat-conducting fillers are lapped, and the heat transfer performance of the inorganic heat-conducting fillers is improved. The construction of a solid-liquid double-phase heat transfer passage in the epoxy composite material is realized. The cured composite material has high heat-conducting property, insulating property, dimensional stability and mechanical property, and the preparation method of the epoxy packaging material is provided for relieving thermal mismatch, heat accumulation and stress accumulation in the field of high-power chip packaging.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of manufacturing heat-conducting thermosetting epoxy resin composites, in particular to a preparation method of an epoxy packaging material based on liquid metal morphology regulation. BACKGROUND

[0002] The continuous expansion of the market demand for high-performance electronic products promotes the development of high-efficiency semiconductor devices, and puts forward higher requirements for advanced semiconductor device packaging technology. Packaging materials with good thermal stress and mechanical stress management functions become important factors for realizing stable, reliable and effective semiconductor devices. In semiconductor packaging materials, mainly including epoxy plastic packaging materials and underfill adhesives, the rheological properties, mechanical properties, thermal management properties and electrical insulation of the materials are required. At present, the semiconductor packaging materials mainly use epoxy resin as the base resin, add silica powder and other fillers and various additives for mixing, and the thermal conductivity of the materials is low. In the case of maintaining a low thermal expansion coefficient under a high filler amount, the thermal accumulation of stress and strain is caused, and then the warping failure of the device is caused.

[0003] In the research of high-thermal-conductivity composites, carbon-based fillers such as graphene, carbon fiber and carbon nanotube are widely used in composites to improve the thermal conductivity. However, the insulation property of the material is sacrificed when the thermal conductivity of the material is improved, and it is difficult to balance the thermal conductivity and the insulation property. The electrical conductivity of the filler limits the application of high-thermal-conductivity composites in the field of semiconductor packaging.

[0004] In view of the challenges faced by the above packaging materials, it is the goal of researchers to develop epoxy resin composites with good thermal conductivity and insulation property. In recent years, aluminum oxide, aluminum nitride and boron nitride are widely used in the preparation of epoxy resin composites. However, how to use the thermal conductive filler to improve the thermal conductivity of the composite and balance the mechanical properties is still a challenge in the preparation of epoxy-based packaging materials.

[0005] The patent for invention with the patent publication number CN 116004159 A discloses an underfill adhesive suitable for intelligent vehicles and a preparation method thereof. The invention proposes an underfill adhesive suitable for intelligent vehicles in the field of semiconductor adhesives, which has high flowability, low thermal expansion coefficient, drop resistance and excellent aging resistance. The invention provides a solution for balancing the flowability and the thermal expansion coefficient, but the material mainly uses spherical silica powder as the main filler, which cannot relieve the thermal accumulation and meet the practical demand for thermal management.

[0006] Therefore, a preparation method of an epoxy packaging material based on liquid metal morphology regulation is provided. SUMMARY

[0007] The present application aims at the problem of low thermal conductivity of epoxy-based packaging materials and the accumulation of thermal stress caused by high filling and dimensional stability, and provides a preparation method of epoxy-based packaging materials based on liquid metal morphology regulation. On the one hand, the thermal conductivity is improved by the morphology regulation of liquid metal combined with fillers of different dimensions, which can relieve the problem of thermal accumulation caused by environmental temperature change and improve the thermal management capability of the material. On the other hand, the problem of high modulus of the material under high filling and the accumulation of thermal stress caused by temperature change is solved by the characteristics of liquid metal.

[0008] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a preparation method of epoxy-based packaging materials based on liquid metal morphology regulation, Step 1: regulating the morphology of liquid metal by liquid cavitation effect and surface modification to obtain liquid metal microspheres; Specifically, the following steps are included: Step 1.1: γ-glycidoxypropyltrimethoxysilane is used as a modifier, and the mass of the modifier is 1-5% of the mass of the liquid metal. The modifier is hydrolyzed in an alcohol-water solution for 15-30 min to obtain a modified solution; Step 1.2: liquid metal is added to the modified solution, and the morphology of the liquid metal is regulated in an ultrasonic cell crusher at a power of 200-600 W and a treatment time of 30-300 min; Step 1.3: unreacted modifier is removed, and the liquid metal microspheres are obtained by repeated washing with ethanol and heat treatment at 60-120℃; Step 2: a chemical bridging layer is formed between the binary thermal conductive fillers by covalent modification grafting to obtain composite binary fillers; Specifically, the following steps are included: γ-glycidoxypropyltrimethoxysilane is used as a modifier, and the mass of the modifier is 0.5-3% of the total mass of the binary fillers. The binary fillers are added to the modified solution for chemical grafting, and the composite binary fillers are obtained after washing and heat treatment at 120℃; Step 3: a thermal conductive skeleton and a thermal conductive path are constructed in the epoxy system by morphology regulation and mechanical shearing to obtain epoxy-based packaging materials based on liquid metal morphology regulation; Specifically, the following steps are included: Step 3.1: the composite binary fillers and the liquid metal microspheres are mixed by mechanical shearing at a mass ratio of 4:5 to obtain homogeneous fillers; Step 3.2: the homogeneous fillers and the epoxy system are mixed by mechanical shearing at a mass ratio of 4:1 to obtain a composite slurry; Step 3.3: the composite slurry system is subjected to debubbling treatment under vacuum to obtain epoxy-based packaging materials based on liquid metal morphology regulation.

[0009] Further, the liquid metal in step 1 is at least one of gallium-based liquid metal, gallium-indium alloy and gallium-indium-tin alloy.

[0010] Further, the binary filler in step 2 comprises diamond micro powder and hexagonal boron nitride cooling filler sheet crystal, and the average particle size and the average size are 5-20 μm and 12 μm respectively, and the mass ratio is (5-10):1.

[0011] Further, the epoxy system in step 3 comprises the following components: bisphenol F type epoxy resin, acid anhydride curing agent and epoxy curing accelerator, and the mass fraction ratio of the three is 17:14:2.

[0012] Further, the epoxy equivalent of the bisphenol F type epoxy resin is 160.0-180.0 g / eq, the viscosity at 25℃ is 2000-5000 cps, and the structural formula is as follows: .

[0013] Further, the acid anhydride curing agent is at least one of methyl tetrahydrophthalic anhydride and methyl hexahydrophthalic anhydride.

[0014] Further, the epoxy curing accelerator is at least one of 2,4,6-tris(dimethylaminomethyl) phenol, benzyl dimethylamine and o-hydroxybenzyl dimethylamine.

[0015] Compared with the prior art, the beneficial effects of the present application are: The present application adopts diamond micro powder and two-dimensional sheet layer heat-conducting filler to form a thermal interface "transition bridge" between different dimension inorganic heat-conducting fillers and between the filler and the epoxy resin through covalent modification, morphology control and chemical grafting modification, and the heat-conducting channel between the inorganic heat-conducting fillers is bridged to realize the construction of solid-liquid dual-phase heat-conducting path in the epoxy composite material. The cured composite material has high heat-conducting performance, insulation performance, good dimensional stability and good mechanical properties, and provides an epoxy-based packaging material preparation method for relieving thermal mismatch, thermal accumulation and stress accumulation in the high-power chip packaging field. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is the preparation process schematic diagram of the liquid metal microspheres of the present application; Figure 2 is the preparation process schematic diagram of the epoxy packaging material of the present application; Figure 3 is the scanning electron microscope graph of the diamond micro powder in example 1 of the present application; Figure 4is a scanning electron microscope image of the hexagonal boron nitride cooling filler flake in Example 1 of the present application; Figure 5 is a scanning electron microscope image of the composite material in Example 1 of the present application. DETAILED DESCRIPTION

[0017] The preferred embodiments of the present application are described in detail below with reference to the accompanying drawings, so that the advantages and features of the present application can be more easily understood by those skilled in the art, and the scope of protection of the present application can be more clearly defined.

[0018] As shown in Figures 1-2 The present application provides a preparation method of an epoxy encapsulating material based on liquid metal morphology regulation, which specifically comprises the following steps: Step 1: regulating the morphology of liquid metal by liquid cavitation effect and performing surface modification to obtain liquid metal microspheres; Step 1.1: taking γ-glycidoxypropyltrimethoxysilane as a modifier, the mass of which is 1-5% of the mass of the liquid metal, hydrolyzing in an alcohol-water solution for 15-30 min to obtain a modified solution; Step 1.2: adding the liquid metal into the modified solution, and regulating the morphology of the liquid metal in an ultrasonic cell crusher at a power of 200-600 W and a processing time of 30-300 min; Step 1.3: removing the unreacted modifier, repeatedly washing with ethanol, and obtaining the liquid metal microspheres after heat treatment at 60-120°C; Step 2: forming a chemical bridging layer between the binary thermal conductive fillers by covalent modification grafting to obtain a composite binary filler; Taking γ-glycidoxypropyltrimethoxysilane as a modifier, the mass of which is 0.5-3% of the total mass of the binary filler, hydrolyzing in an alcohol-water solution for 15-30 min, adding the binary filler into the modified solution for chemical grafting, and obtaining the composite binary filler after washing and heat treatment at 120°C; Step 3: constructing a thermal conductive skeleton and building a thermal conductive path in the epoxy system through morphology regulation and mechanical shearing to obtain an epoxy encapsulating material based on liquid metal morphology regulation; Step 3.1. mixing the composite binary filler and the liquid metal microspheres in a mass ratio of 4:5 by mechanical shearing to obtain a homogeneous filler; Step 3.2. mixing the homogeneous filler and the epoxy system in a mass ratio of 4:1 by mechanical shearing to obtain a composite slurry; Step 3.3. performing defoaming treatment on the composite slurry system under vacuum to obtain the epoxy encapsulating material based on liquid metal morphology regulation.

[0019] Example 1: The epoxy system consists of the following components: bisphenol F type epoxy resin, methyltetrahydrophthalic anhydride curing agent, and 2,4,6-tris(dimethylaminomethyl)phenol epoxy curing accelerator, with a mass fraction ratio of 17:14:2.

[0020] The liquid metal used in this embodiment is a gallium indium tin alloy. The preparation method of the liquid metal microspheres specifically includes the following steps: using γ-glycidoxypropyltrimethoxysilane as a modifier, its mass is 1% of the mass of the liquid metal, hydrolyzing it in an alcohol-water solution for 15 min to obtain a modified solution; adding liquid metal to the modified solution, and controlling the morphology of the liquid metal in an ultrasonic cell disruptor with a power of 200 W and a processing time of 30 min; removing unreacted modifier, repeatedly washing with ethanol, and obtaining liquid metal microspheres after heat treatment at 80℃.

[0021] The binary filler in this embodiment comprises diamond micropowder with an average particle size of 10 μm and hexagonal boron nitride cooled filler lamellars in a mass ratio of 7:1. The composite binary filler is prepared by using γ-glycidyl etheroxypropyltrimethoxysilane as a modifier, with a mass of 1.5% of the total mass of the binary filler, hydrolyzing it in an alcohol-water solution for 15 min, then adding the modifier solution to the binary filler for chemical grafting, followed by washing and heat treatment at 120°C to obtain the composite binary filler.

[0022] The preparation method of epoxy encapsulation material based on liquid metal morphology control in this embodiment includes the following steps: S1: The composite binary filler and liquid metal microspheres are mixed at a mass ratio of 4:5 by mechanical shearing to obtain a homogeneous filler; S2: The homogeneous filler and the epoxy system are mixed at a mass ratio of 4:1 by mechanical shearing to obtain a composite slurry; S3: Degas the composite slurry system under vacuum conditions.

[0023] The prepared composite slurry was coated onto the mold, and the sample was cured at 120℃ for 2 h and 150℃ for 1 h.

[0024] pass Figure 3 It can be seen that the diamond used in the examples exhibits micron-sized particulate filler, providing good mechanical support and improving the flowability of the composite material; through Figure 4 It can be seen that the boron nitride used in the examples exhibits a sheet-like packing structure with a good aspect ratio, which is beneficial for the overlapping of the thermal conductivity pathways in the composite packing; through Figure 5 As can be seen from the electron microscope images of the solidified composite material in the examples, the spherical components are liquid metal, reflecting the morphological characteristics of liquid metal in the material.

[0025] Example 2: The epoxy system is composed of the following components: bisphenol F type epoxy resin, methyl tetrahydrophthalic anhydride curing agent, 2,4,6-tris(dimethylaminomethyl) phenol epoxy curing accelerator, and the mass fraction ratio of the three is 17:14:2.

[0026] The liquid metal used in this embodiment is a gallium-indium-tin alloy. The preparation method of the liquid metal microspheres specifically comprises the following steps: γ-glycidyl ether oxypropyl trimethoxysilane is used as a modifier, the mass of the modifier is 1% of the mass of the liquid metal, the modifier is hydrolyzed in an alcohol-water solution for 15 min to obtain a modified solution; the liquid metal is added to the modified solution, and the morphology of the liquid metal is controlled in an ultrasonic cell crusher at a power of 300 W and a treatment time of 30 min; unreacted modifier is removed, and the liquid metal microspheres are obtained after repeated washing with ethanol and heat treatment at 80°C.

[0027] The binary filler of this embodiment comprises diamond micro-powder with an average particle size of 10 μm and hexagonal boron nitride cooling filler platelets, and the mass ratio is 7:1. The preparation method of the composite binary filler is as follows: γ-glycidyl ether oxypropyl trimethoxysilane is used as a modifier, the mass of the modifier is 1.5% of the total mass of the binary filler, the binary filler is added to the modified solution for chemical grafting after the modifier is hydrolyzed in an alcohol-water solution for 15 min, and the composite binary filler is obtained after washing and heat treatment at 120°C.

[0028] The preparation method of the epoxy packaging material based on morphology control of liquid metal of this embodiment comprises the following steps: S1: The composite binary filler and the liquid metal microspheres are mixed by mechanical shearing at a mass ratio of 4:5 to obtain a homogeneous filler; S2: The homogeneous filler and the epoxy system are mixed by mechanical shearing at a mass ratio of 4:1 to obtain a composite slurry; S3: The composite slurry system is subjected to a degassing treatment under vacuum conditions.

[0029] The prepared composite slurry is coated into a mold, and the sample is cured under the conditions of 120°C / 2 h and 150°C / 1 h.

[0030] Example 3: The epoxy system is composed of the following components: bisphenol F type epoxy resin, methyl tetrahydrophthalic anhydride curing agent, 2,4,6-tris(dimethylaminomethyl) phenol epoxy curing accelerator, and the mass fraction ratio of the three is 17:14:2.

[0031] The liquid metal used in this embodiment is a gallium-indium-tin alloy, and the preparation method of the liquid metal microspheres specifically comprises the following steps: taking γ-glycidoxypropyltrimethoxysilane as a modifier, the mass of the modifier is 3% of the mass of the liquid metal, hydrolyzing in an alcohol-water solution for 15 min to obtain a modified solution; adding the liquid metal into the modified solution, and controlling the morphology of the liquid metal in an ultrasonic cell crusher at a power of 300 W and a treatment time of 30 min; removing the unreacted modifier, repeatedly washing with ethanol, and obtaining the liquid metal microspheres after heat treatment at 80°C.

[0032] The binary filler of this embodiment comprises diamond micro-powder with an average particle size of 10 μm and hexagonal boron nitride cooling filler platelets, and the mass ratio is 7:1. The preparation method of the composite binary filler is as follows: taking γ-glycidoxypropyltrimethoxysilane as a modifier, the mass of the modifier is 1.5% of the total mass of the binary filler, hydrolyzing in an alcohol-water solution for 15 min, and chemically grafting the binary filler in the modified solution, and obtaining the composite binary filler after washing and heat treatment at 120°C.

[0033] The preparation method of the epoxy packaging material based on morphology control of liquid metal of this embodiment comprises the following steps: S1: mixing the composite binary filler and the liquid metal microspheres at a mass ratio of 4:5 by mechanical shearing to obtain a homogeneous filler; S2: mixing the homogeneous filler and the epoxy system at a mass ratio of 4:1 by mechanical shearing to obtain a composite slurry; S3: performing a defoaming treatment on the composite slurry system under vacuum conditions.

[0034] Coating the prepared composite slurry into a mold, and performing sample curing at 120°C / 2 h and 150°C / 1 h.

[0035] Embodiment 4: The epoxy system is composed of the following components: bisphenol F type epoxy resin, methyl tetrahydrophthalic anhydride curing agent, 2,4,6-tris(dimethylaminomethyl) phenol epoxy curing accelerator, and the mass fraction ratio of the three is 17:14:2.

[0036] The liquid metal used in this embodiment is a gallium-indium-tin alloy, and the preparation method of the liquid metal microspheres specifically comprises the following steps: taking γ-glycidoxypropyltrimethoxysilane as a modifier, the mass of the modifier is 3% of the mass of the liquid metal, hydrolyzing in an alcohol-water solution for 15 min to obtain a modified solution; adding the liquid metal into the modified solution, and controlling the morphology of the liquid metal in an ultrasonic cell crusher at a power of 300 W and a treatment time of 120 min; removing the unreacted modifier, repeatedly washing with ethanol, and obtaining the liquid metal microspheres after heat treatment at 80°C.

[0037] The binary filler of this example comprises 10 μm diamond micropowder and hexagonal boron nitride cooling filler platelets with a mass ratio of 7:1. The preparation method of the composite binary filler is as follows: 1.5% of γ-glycidoxypropyltrimethoxysilane is used as a modifier, hydrolyzed in an alcohol aqueous solution for 15 min, and the binary filler is added to the modified solution for chemical grafting, and the composite binary filler is obtained after washing and heat treatment at 120℃.

[0038] The preparation method of the epoxy encapsulating material based on liquid metal morphology regulation of this example comprises the following steps: S1: The composite binary filler and the liquid metal microspheres are mixed in a mass ratio of 4:5 by mechanical shearing to obtain a homogeneous filler; S2: The homogeneous filler and the epoxy system are mixed in a mass ratio of 4:1 by mechanical shearing to obtain a composite slurry; S3: The composite slurry system is subjected to a degassing treatment under vacuum conditions.

[0039] The prepared composite slurry is coated onto a mold, and the sample is cured under the conditions of 120℃ / 2 h and 150℃ / 1 h.

[0040] Comparative Example 1: The other conditions and operations are the same as those of Example 4, except that γ-glycidoxypropyltrimethoxysilane is not used as a modifier in the preparation of the liquid metal microspheres, i.e., the morphology of the liquid metal microspheres is directly regulated in an alcohol aqueous solution.

[0041] Comparative Example 2: The other conditions and operations are the same as those of Example 4, except that 10 μm diamond micropowder is used as a single filler instead of the composite binary filler.

[0042] The performance of the epoxy encapsulating material is tested according to the following method in the embodiments of the present application: Thermal conductivity: measured by laser flash method (LFA), and the thermal conductivity of the cured epoxy composite material is taken. The size of the test sample is 10 mm×10 mm×2 mm.

[0043] Storage modulus: tested by dynamic mechanical analysis (DMA) under the conditions of an amplitude of 30 μm, a frequency of 1 Hz, a temperature rising rate of 3℃ / min, and a temperature range of room temperature to 200℃. The size of the test sample is 35 mm×10-12 mm×2-3 mm.

[0044] Glass transition temperature: The glass transition temperature was tested by dynamic mechanical analysis (DMA) under the conditions of an amplitude of 30 μm, a frequency of 1 Hz, a temperature rising rate of 3℃ / min, and a temperature range of room temperature to 200℃, and was obtained by taking the loss factor curve as a reference. The size of the tested sample was 35 mm x 10-12 mm x 2-3 mm.

[0045] Volume resistivity: The volume resistivity was tested by an intelligent volume surface resistivity tester under the conditions of room temperature and a working voltage of 500 V. The size of the tested sample was 10 mm x 10 mm x 2 mm.

[0046] Table 1: Performance test table of the epoxy encapsulating materials obtained in Examples 1-4 and Comparative Examples 1-2

[0047] In summary, as shown in Table 1, the thermal conductivity, the storage modulus, the glass transition temperature, and the volume resistivity of the epoxy encapsulating material prepared by the method of the present application are all superior to those of Comparative Examples 1-2.

[0048] The above examples only express the embodiments of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled persons in the art, some modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. A method for preparing epoxy encapsulation materials based on liquid metal morphology control, characterized in that, Step 1: The morphology of liquid metal is controlled by the liquid cavitation effect and its surface is modified to obtain liquid metal microspheres; Specifically, the following steps are included: Step 1.1: Using γ-glycidoxypropyltrimethoxysilane as a modifier, its mass is 1~5% of the mass of the liquid metal, it is hydrolyzed in an alcohol-water solution for 15~30 min to obtain a modified solution; Step 1.2: Add liquid metal to the modified solution, and adjust the morphology of the liquid metal in an ultrasonic cell disruptor with a power of 200-600 W and a processing time of 30-300 min. Step 1.3: Remove unreacted modifier, wash repeatedly with ethanol, and obtain liquid metal microspheres after heat treatment at 60~120℃; Step 2: A chemical bridging layer is formed between the binary thermally conductive fillers by covalent modification grafting to obtain a composite binary filler; Specifically, the following steps are included: Using γ-glycidyl etheroxypropyltrimethoxysilane as a modifier, its mass is 0.5~3% of the total mass of the binary filler. It is hydrolyzed in an alcohol-water solution for 15~30 min. The binary filler is added to the modification solution for chemical grafting. After washing and heat treatment at 120℃, a composite binary filler is obtained. Step 3: By controlling the morphology and mechanical shearing action, a thermally conductive skeleton and a thermally conductive path are constructed in the epoxy system to obtain an epoxy encapsulation material based on the morphology control of liquid metal; Specifically, the following steps are included: Step 3.

1. The composite binary packing material and liquid metal microspheres are mixed at a mass ratio of 4:5 by mechanical shearing to obtain a homogeneous packing material; Step 3.

2. Mix the homogeneous filler and epoxy system at a mass ratio of 4:1 by mechanical shearing to obtain a composite slurry; Step 3.

3. Degas the composite slurry system under vacuum conditions to obtain an epoxy encapsulation material based on liquid metal morphology control.

2. The preparation method according to claim 1, characterized in that, The liquid metal in step 1 is a gallium-based liquid metal, at least one of gallium-indium alloy and gallium-indium-tin alloy.

3. The preparation method according to claim 1, characterized in that, The binary filler in step 2 consists of diamond micron powder and hexagonal boron nitride cooling filler flakes, with an average particle size of 5~20 μm and an average size of 12 μm, and a mass ratio of (5~10):

1.

4. The preparation method according to claim 1, characterized in that, The epoxy system in step 3 includes the following components: bisphenol F type epoxy resin, acid anhydride curing agent and epoxy curing accelerator, with a mass ratio of 17:14:

2.

5. The preparation method according to claim 4, characterized in that, The bisphenol F type epoxy resin has an epoxy equivalent of 160.0-180.0 g / eq, a viscosity of 2000-5000 cps at 25℃, and the structural formula is as follows: 。 6. The preparation method according to claim 4, characterized in that, The anhydride curing agent is at least one of methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride.

7. The preparation method according to claim 4, characterized in that, The epoxy curing accelerator is at least one of 2,4,6-tris(dimethylaminomethyl)phenol, benzyl dimethylamine, and o-hydroxybenzyl dimethylamine.

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