High-strength epoxy molding compound for aluminum capacitor and preparation method of high-strength epoxy molding compound

Abstract

The invention relates to the technical field of electronic packaging, in particular to a high-strength epoxy molding compound for an aluminum capacitor and a preparation method of the high-strength epoxy molding compound for the aluminum capacitor, and the high-strength epoxy molding compound for the aluminum capacitor at least comprises the following preparation raw materials: 3-5 parts of epoxy resin 1, 1-3 parts of epoxy resin 2, 3-5 parts of a curing agent, 80-89 parts of silicon dioxide, 0.1-0.5 part of a coupling agent and 0.1-0.5 part of a release agent, the epoxy resin 2 has the structure shown in the formula (2), the actual application requirement of thinner and thinner aluminum capacitor products is met, the product strength is high, the cracking problem is effectively avoided, and the high market application value is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of electronic packaging, and in particular to a high-strength epoxy plastic packaging material for aluminum capacitors and a preparation method thereof. Background Art

[0002] As the design of aluminum capacitors becomes smaller and thinner, the problem of cracking becomes more and more serious. The reason is that there are some liquid electrolytes inside the aluminum capacitors. Some of the electrolytes will volatilize at high temperatures. If the strength of the plastic packaging material is insufficient, cracking will occur. The Chinese patent (authorization announcement number is CN114276651B) discloses an epoxy resin composition suitable for low-voltage packaging and its preparation method. The product provided has excellent crack resistance under low packaging pressure (30-40 kg) by optimizing the epoxy resin, phenolic resin, silicon micropowder filler, and reinforcing filler in the system. However, the spiral flow length of the obtained epoxy resin composition needs to be further improved to meet the actual injection molding requirements, and the bending strength of the product needs to be further improved. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a high-strength epoxy molding compound for aluminum capacitors, which meets the practical application needs of increasingly thin aluminum capacitor products. The product has high strength, effectively avoids cracking problems, and has high market application value.

[0004] On the one hand, the present invention provides a high-strength epoxy molding compound for aluminum capacitors, wherein the raw materials for its preparation include at least: 3-5 parts of epoxy resin 1, 1-3 parts of epoxy resin 2, 3-5 parts of curing agent, 80-89 parts of silicon dioxide, 0.1-0.5 parts of coupling agent, and 0.1-0.5 parts of release agent, wherein: epoxy resin 1 has a structure shown in formula (1), epoxy resin 2 has a structure shown in formula (2),

[0005] Formula (1):

[0006] Formula (2):

[0007] As a preferred technical solution, the curing agent at least includes the curing agent described in formula (3),

[0008] Formula (3): n=2-10.

[0009] As a preferred technical solution, the curing agent further comprises the curing agent described in formula (3),

[0010] Formula (4): n=2-6.

[0011] As a preferred technical solution, the maximum particle size of the silicon dioxide is 45 μm.

[0012] As a preferred technical solution, the silane coupling agent is selected from at least one of γ-glycidyloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, and γ-aminopropyltriethoxysilane, preferably γ-glycidyloxypropyltrimethoxysilane.

[0013] As a preferred technical solution, the release agent at least includes high-density oxidized polyethylene wax.

[0014] The present invention adopts an epoxy resin combination of 3-5 parts by weight of epoxy resin 1 and 1-3 parts by weight of epoxy resin 2, which has good matching with the curing agent in the system, so that the provided product has suitable fluidity, and the product after curing in a short time has high bending strength and bending modulus, and the cracking problem of thin aluminum capacitors is avoided during subsequent applications. Furthermore, the present invention further shortens the curing time and avoids the problem of mold sticking by controlling the curing agent to at least include the curing agent described in formula (3), thereby meeting the application requirements of thin packaging.

[0015] Furthermore, the present invention introduces silicon dioxide with a maximum particle size of 45 μm into the system, and with the cooperation of a silane coupling agent and a high-density oxidized polyethylene wax in the system, the provided product has good fluidity and high bending strength, as well as a relatively low thermal expansion coefficient.

[0016] Another aspect of the present invention provides a method for preparing a high-strength epoxy molding compound for aluminum capacitors, comprising at least the following steps:

[0017] (1) mixing epoxy resin 1 and epoxy resin 2 and then crushing them to obtain epoxy resin powder, and crushing a curing agent to obtain curing agent powder;

[0018] (2) stirring and mixing the raw materials except the epoxy resin and the curing agent, and then adding the epoxy resin mixture and the curing agent powder and stirring and mixing to obtain a mixture;

[0019] (3) The mixed material is extruded, cooled and crushed to obtain the epoxy molding compound.

[0020] As a preferred technical solution, in step (1), a resin crusher is used for crushing, the crushing temperature is ≤25°C, and the crushing fineness is less than 3.0 mm.

[0021] As a preferred technical solution, in step (2), a high-speed stirrer is used for stirring and mixing at a speed of 150-250 rpm for 20-40 min, and the stirring and mixing temperature is controlled to be ≤25°C.

[0022] As a preferred technical solution, in step (3), a twin-screw extruder is used for extrusion, and the extrusion temperature is controlled at 90-120°C;

[0023] As a preferred technical solution, the particle size of the epoxy molding compound in step (3) is 0.5-2.0 mm.

[0024] Beneficial Effects

[0025] 1. The present invention provides a high-strength epoxy molding compound for aluminum capacitors. The present invention provides a high-strength epoxy molding compound for aluminum capacitors, which meets the actual application needs of increasingly thin aluminum capacitor products. The product has high strength, effectively avoids cracking problems, and has high market application value.

[0026] 2. The present invention adopts an epoxy resin combination of 3-5 parts by weight of epoxy resin 1 and 1-3 parts by weight of epoxy resin 2, which has good matching with the curing agent in the system, so that the provided product has suitable fluidity, and the product after curing in a short time has higher bending strength and bending modulus, avoiding the cracking problem of thin aluminum capacitors in subsequent applications.

[0027] 3. The present invention further shortens the curing time and avoids the problem of mold sticking by controlling the curing agent to at least include the curing agent described in formula (3), thereby meeting the application requirements of thin packaging.

[0028] 4. The present invention introduces silicon dioxide with a maximum particle size of 45 μm into the system. With the cooperation of the silane coupling agent and the high-density oxidized polyethylene wax in the system, the provided product has good fluidity and high bending strength as well as a relatively low thermal expansion coefficient. DETAILED DESCRIPTION

[0029] Examples 1-4

[0030] On the one hand, embodiments 1-4 of the present invention provide high-strength epoxy molding compounds for aluminum capacitors. The formulas are shown in Table 1 in parts by weight.

[0031] Table 1

[0032]

[0033]

[0034] On the other hand, embodiments 1-4 of the present invention provide a method for preparing a high-strength epoxy molding compound for aluminum capacitors, comprising the following steps:

[0035] (1) mixing epoxy resin 1 and epoxy resin 2 and then crushing them to obtain epoxy resin powder, and crushing a curing agent to obtain curing agent powder;

[0036] (2) stirring and mixing the raw materials except the epoxy resin and the curing agent, and then adding the epoxy resin mixture and the curing agent powder and stirring and mixing to obtain a mixture;

[0037] (3) The mixed material is extruded, cooled and crushed to obtain the epoxy molding compound.

[0038] In the step (1), a resin crusher is used for crushing, the crushing temperature is ≤25°C, and the crushing fineness is less than 3.0.

[0039] In the step (2), a high-speed stirrer is used for stirring and mixing at a speed of 180 rpm for 30 min, and the stirring and mixing temperature is controlled to be ≤25°C.

[0040] In step (3), a twin-screw extruder is used for extrusion, and the extrusion temperature is controlled to be 100° C.;

[0041] The particle size of the epoxy molding compound in step (3) is 0.5-2.0 mm.

[0042] Performance Testing

[0043] The epoxy molding compounds provided in Examples 1-4 were subjected to the performance tests shown in Table 2. The test methods are as follows. The test results are shown in Table 2.

[0044] (1) With reference to GB / T40564-2021, the spiral flow length of the epoxy molding compound of the test example was tested.

[0045] (2) With reference to GB / T40564-2021, the curing time of the epoxy molding compound of the test example at 175°C was tested.

[0046] (3) With reference to GB / T40564-2021, the flexural strength and flexural modulus of the epoxy molding compound of the embodiment were tested.

[0047] (4) With reference to GB / T40564-2021, the glass transition temperature of the epoxy molding compound of the embodiment was tested.

[0048] (5) At a molding temperature of 175°C, injection pressure: 6.86 MPa (70 kgf / cm 2 ) conditions, the epoxy resin composition was added to an injection molding cylinder and compression molded into a cylinder with a diameter of 5 mm and a height of 5 mm. After post-curing at 175°C for 6 hours, the thermal expansion coefficient 1 (temperature range of 40 to 80 deg-c) and the thermal expansion coefficient 2 (200 to 240 deg-c) were tested using PerkingElmer TMA4000.

[0049] (6) With reference to GB / T40564-2021, the molding shrinkage of the powder epoxy molding compound of the embodiment was tested.

[0050] Table 2

[0051]

[0052] From the analysis of the above table, it can be seen that the epoxy molding compound product provided in Example 1 has balanced bending strength and bending modulus, spiral flow length, curing time, glass transition temperature, thermal expansion coefficient and molding shrinkage rate relative to Examples 2, 3 and 4, and better meets the actual application requirements.

Claims

1. A high-strength epoxy molding compound for aluminum capacitors, characterized in that: The raw materials for its preparation include at least 3-5 parts of epoxy resin 1, 1-3 parts of epoxy resin 2, 3-5 parts of curing agent, 80-89 parts of silicon dioxide, 0.1-0.5 parts of coupling agent, and 0.1-0.5 parts of release agent, wherein: epoxy resin 1 has a structure shown in formula (1), epoxy resin 2 has a structure shown in formula (2), Formula (1): Formula (2):

2. The high-strength epoxy molding compound for aluminum capacitors according to claim 1, characterized in that: The curing agent at least comprises the curing agent described in formula (3), Formula (3): n=2-10.

3. The high-strength epoxy molding compound for aluminum capacitors according to claim 1, characterized in that: The curing agent also includes the curing agent described in formula (3), Formula (4): n=2-6.

4. The high-strength epoxy molding compound for aluminum capacitors according to claim 1, characterized in that: The maximum particle size of the silicon dioxide is 45 μm.

5. The high-strength epoxy molding compound for aluminum capacitors according to claim 1, characterized in that: The silane coupling agent is selected from at least one of γ-glycidyloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane.

6. The high-strength epoxy molding compound for aluminum capacitors according to claim 1, characterized in that: The release agent at least includes high-density oxidized polyethylene wax.

7. A method for preparing a high-strength epoxy molding compound for aluminum capacitors according to any one of claims 1 to 6, characterized in that: At least the following steps are included: (1) mixing epoxy resin 1 and epoxy resin 2 and then crushing them to obtain epoxy resin powder, and crushing a curing agent to obtain a curing agent powder; (2) stirring and mixing the raw materials except the epoxy resin and the curing agent, and then adding the epoxy resin mixture and the curing agent powder and stirring and mixing to obtain a mixture; (3) The mixed material is extruded, cooled and crushed to obtain the epoxy molding compound.

8. The method for preparing a high-strength epoxy molding compound for aluminum capacitors according to claim 7, characterized in that: In the step (1), a resin crusher is used for crushing, the crushing temperature is ≤25°C, and the crushing fineness is less than 3.0 mm.

9. The method for preparing a high-strength epoxy molding compound for aluminum capacitors according to claim 7, characterized in that: In the step (3), a twin-screw extruder is used for extrusion, and the extrusion temperature is controlled at 90-120°C.

10. The method for preparing a high-strength epoxy molding compound for aluminum capacitors according to claim 7, characterized in that: The particle size of the epoxy molding compound in step (3) is less than 3.0 mm.

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