Two-component epoxy electronic pouring sealant and preparation method thereof

Abstract

The invention discloses a two-component epoxy electronic pouring sealant, which is prepared by mixing a component A and a component B according to a weight ratio of (3-5): 1, and is characterized in that the component A is prepared from the following raw materials in parts by weight: 100 parts of epoxy resin; 5 to 15 parts of a reactive diluent; 150 to 300 parts of a composite heat-conducting filler; 20 to 50 parts of a flame retardant; 1-3 parts of a coupling agent; 0.1 to 0.5 part of a defoaming agent; the component B is prepared from the following raw materials in parts by weight: 80-120 parts of a curing agent; 0.5 to 5 parts of a curing accelerator; and 10 to 20 parts of a toughening agent. The invention also discloses a preparation method of the composition. The two-component epoxy electronic pouring sealant disclosed by the invention has the advantages of high thermal conductivity, low stress, high flame retardance and excellent electrical insulation performance on the premise of keeping moderate viscosity (17,000-23,000) and good operability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic chemical materials, in particular to a two-component epoxy electronic potting adhesive and a preparation method thereof. BACKGROUND

[0002] Epoxy resin potting adhesive is widely used in the packaging protection of transformer, power module, sensor, automobile electronics and other components in the electronic industry, which plays the role of insulation, moisture-proof, dust-proof, corrosion-resistant, chemical medium-resistant and mechanical support.

[0003] With the development of electronic devices towards miniaturization and high power, a large amount of heat will be generated during the operation of components, which will seriously affect the reliability and service life if not timely removed. Therefore, higher requirements are put forward for the thermal conductivity of the potting adhesive.

[0004] The commonly used thermal conductive fillers such as alumina and aluminum hydroxide can achieve ideal thermal conductivity when the addition amount is high, but this will cause the viscosity of the system to rise sharply, the fluidity to become poor, which is not conducive to construction and filling of complex modules, and may introduce large internal stress due to the mismatch of thermal expansion coefficient between the filler and the resin matrix, resulting in cracking or damage of the welding point of the components.

[0005] In addition, the safety of electronic devices requires that the potting adhesive must have good flame retardant performance, which usually needs to reach UL94 V-0 level.

[0006] Although the traditional halogen-based flame retardant has high flame retardant efficiency, it has environmental pollution and toxicity problems, and has been gradually replaced by halogen-free flame retardant system.

[0007] However, the addition amount of halogen-free flame retardant (aluminum hydroxide, magnesium hydroxide) is usually large, which further deteriorates the rheological properties and mechanical properties of the system.

[0008] Therefore, it is a technical problem to be solved in the art to develop an epoxy electronic potting adhesive that can balance high thermal conductivity, low internal stress, excellent flame retardancy and good processability. SUMMARY

[0009] In order to overcome the above-mentioned defects of the prior art, the purpose of the present application is to provide a two-component epoxy electronic potting adhesive with high thermal conductivity, low stress, excellent flame retardant performance and process adaptability, and a preparation method thereof.

[0010] In order to achieve the purpose of the present application, the technical scheme adopted is: A two-component epoxy electronic potting adhesive is formed by mixing A component and B component in a weight ratio of (3-5):1, wherein the A component is composed of the following raw materials in parts by weight: Epoxy resin: 100 parts; Active diluent: 5-15 parts; Composite heat-conductive filler: 150-300 parts; Flame retardant: 20-50 parts; Coupling agent: 1-3 parts; Defoaming agent: 0.1-0.5 parts; The B component is composed of the following raw materials in parts by weight: Curing agent: 80-120 parts; Curing accelerator: 0.5-5 parts; Toughening agent: 10-20 parts.

[0011] In a preferred embodiment of the present application, the epoxy resin is a mixture of both hydrogenated bisphenol A type epoxy resin and bisphenol F type epoxy resin.

[0012] Preferably, the mixture of both hydrogenated bisphenol A type epoxy resin with an epoxy equivalent weight EEW of 230-240 and bisphenol F type epoxy resin with an epoxy equivalent weight EEW of 160-170 is in a mixed weight ratio of 5-6:3-5.

[0013] In a preferred embodiment of the present application, the active diluent is glycidyl ether. Preferably, butyl glycidyl ether.

[0014] In a preferred embodiment of the present application, the composite heat-conductive filler is a mixture of both spherical alumina and flaky aluminum nitride. Preferably, the mixed weight ratio is 140-180:30-60.

[0015] The median particle size D50 of the spherical alumina is 1-10 μm, and the median particle size D50 of the flaky aluminum nitride is 10-30 μm.

[0016] In a preferred embodiment of the present application, the flame retardant is superfine aluminum hydroxide surface-treated with a silane coupling agent, and the particle size D50 thereof is 1-3 μm.

[0017] In a preferred embodiment of the present application, the coupling agent is a silane coupling agent. Preferably, the silane coupling agent KH-560.

[0018] In a preferred embodiment of the present application, the defoaming agent is BYK1810.

[0019] In a preferred embodiment of the present application, the curing agent is phthalic anhydride type curing agent. Preferably, methylhexahydrophthalic anhydride.

[0020] In a preferred embodiment of the present application, the curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

[0021] In a preferred embodiment of the present application, the toughening agent is a nitrile rubber. Preferably, a carboxyl-terminated liquid nitrile rubber.

[0022] A method for preparing a two-component epoxy electronic potting adhesive, comprising: A component preparation step: Stirring and dehydrating the epoxy resin and active diluent under vacuum at 100-110°C; Maintaining the vacuum and temperature, adding the composite heat-conducting filler and the flame retardant, and dispersing at high speed until uniform; Adding the defoaming agent and the coupling agent, stirring and defoaming at low speed under vacuum, and discharging after cooling to obtain the A component; B component preparation step: Stirring and mixing the curing agent, the toughening agent, and the curing accelerator under vacuum at 40-50°C until uniform and transparent, and discharging after cooling to obtain the B component; Mixing step: Mixing the A component and the B component at a weight ratio of (3-5):1 to obtain the two-component epoxy electronic potting adhesive.

[0023] The present application has the following advantages: The two-component epoxy electronic potting adhesive of the present application has moderate viscosity (17,000-23,000) and good operability, while simultaneously having high heat conductivity, low stress, high flame retardancy, and excellent electrical insulation performance. DETAILED DESCRIPTION

[0024] To make the purpose, technical solutions, and advantages of the present application clearer and more explicit, the present application is further described in detail below through examples. However, it should be understood that the specific examples described herein are merely used to explain the present application and do not limit the scope of the present application. In addition, descriptions of well-known structures and technologies are omitted in the following structures to avoid unnecessary confusion of the concept of the present application. Example 1

[0025] Preparation of the A component: 60 parts by weight of hydrogenated bisphenol A type epoxy resin (epoxy equivalent weight EEW: 230-240) and 40 parts by weight of bisphenol F type epoxy resin (epoxy equivalent weight EEW: 160-170) were added to a reaction kettle, and 10 parts by weight of butyl glycidyl ether was added.

[0026] Stirring and dehydrating at 100°C and a vacuum degree of -0.098 MPa for 30 minutes. Maintaining the conditions, slowly adding 210 parts by weight of a composite heat-conducting filler (175 parts by weight of spherical aluminum oxide and 35 parts by weight of flaky aluminum nitride) and 30 parts by weight of a flame retardant, i.e., superfine aluminum hydroxide treated with a silane coupling agent on the surface.

[0027] The median particle size D50 of the spherical alumina is 1-10 μm, and the median particle size D50 of the flaky aluminum nitride is 10-30 μm.

[0028] The particle size D50 of the superfine aluminum hydroxide treated with a silane coupling agent is 1-3 μm.

[0029] After the feeding is completed, high-speed dispersion is performed for 45 minutes. Finally, 0.3 parts by weight of a defoaming agent (BYK 1810) and 2 parts by weight of a silane coupling agent (KH-560) are added, and low-speed stirring is performed for 15 minutes to remove bubbles. After cooling, the A component is discharged.

[0030] Preparation of the B component: Take 100 parts by weight of the curing agent methyl hexahydrophthalic anhydride, 15 parts by weight of the toughening agent carboxyl-terminated liquid nitrile rubber, and 2 parts by weight of the curing accelerator 2,4,6-tris(dimethylaminomethyl)phenol into a reaction kettle. Stir at 45°C and a vacuum degree of -0.098 MPa for 40 minutes until uniform and transparent. After cooling, the B component is discharged.

[0031] Preparation and performance testing of the potting compound: The prepared A component and B component are mixed uniformly at a weight ratio of 4:1, vacuum degassing is performed, and then poured into a standard mold. The curing process is 80°C / 2 hours + 110°C / 3 hours. The performance of the cured sample is tested, and the results are shown in Table 1 below. Example 2

[0032] Preparation of the A component: Similar to Example 1, but the composite heat-conducting filler is adjusted to 250 parts by weight (of which, 200 parts by weight of spherical alumina and 50 parts by weight of flaky aluminum nitride), and the flame retardant superfine aluminum hydroxide treated with a silane coupling agent is 40 parts by weight. Other components and preparation processes remain unchanged.

[0033] Preparation of the B component: The same as Example 1.

[0034] Preparation and performance testing of the potting compound: The A and B components are mixed at a ratio of 4:1, and the curing process is the same as in Example 1. The performance test results are shown in Table 1 below.

[0035] Comparative Example 1 A commercially available general-purpose epoxy potting compound (thermal conductivity coefficient of about 1.2 W / (m·K)) is used as a comparative example. The mixing and curing are performed according to the product instructions, and the performance is tested.

[0036] Comparative Example 2 The commercial flame-retardant epoxy potting adhesive (thermal conductivity about 1.0 W / (m·K)) using traditional halogen-free flame retardant (aluminum hydroxide, magnesium hydroxide) as a comparative example was mixed and cured according to the product instructions, and performance tests were conducted.

[0037] The performance test results are summarized in Table 1

[0038] From the above results, the two-component epoxy potting adhesive provided by the present application has good processability (sufficient operable time) and viscosity (17,000-23,000) while.

[0039] The thermal conductivity of the present application is significantly higher than that of the comparative example, the electrical performance (high volume resistivity indicates good electrical insulation performance, high dielectric strength and pressure resistance), and the heat resistance (mainly represented by the glass transition temperature (Tg)) are all significantly better than those of the commercial ordinary product, and the thermal expansion coefficient is low, the comprehensive performance is excellent, and it can meet the requirements of high-power and high-reliability electronic components for potting protection.

[0040] The above shows and describes the basic principles and main features of the application and the advantages of the application.

[0041] Those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A two-component epoxy electronic potting compound, comprising component A and component B mixed in a weight ratio of (3-5):1, characterized in that, Component A is composed of the following raw materials in parts by weight: Epoxy resin: 100 parts; Reactive diluent: 5-15 parts; Composite thermally conductive filler: 150-300 parts; Flame retardant: 20-50 parts; Coupling agent: 1-3 parts; Defoamer: 0.1-0.5 parts; Component B is composed of the following raw materials in parts by weight: Hardener: 80-120 parts; Curing accelerator: 0.5-5 parts; Toughening agent: 10-20 parts.

2. The two-component epoxy electronic potting compound as described in claim 1, characterized in that, The epoxy resin is a mixture of hydrogenated bisphenol A type epoxy resin and bisphenol F type epoxy resin.

3. The two-component epoxy electronic potting compound as described in claim 2, characterized in that, The epoxy resin is a mixture of hydrogenated bisphenol A type epoxy resin with an epoxy equivalent (EEW) of 230-240 and bisphenol F type epoxy resin with an epoxy equivalent (EEW) of 160-170, with a mixing weight ratio of 5-6:3-5.

4. The two-component epoxy electronic potting compound as described in claim 1, characterized in that, The active diluent is glycidyl ether.

5. The two-component epoxy electronic potting compound as described in claim 1, characterized in that, The composite thermally conductive filler is a mixture of spherical alumina and plate-shaped aluminum nitride, with a mixing weight ratio of 140-180:30-60. The median particle size D50 of the spherical alumina is 1-10 μm, and the median particle size D50 of the plate-shaped aluminum nitride is 10-30 μm.

6. The two-component epoxy electronic potting compound as described in claim 1, characterized in that, The flame retardant is ultrafine aluminum hydroxide surface-treated with a silane coupling agent, with a particle size D50 of 1-3 μm.

7. The two-component epoxy electronic potting compound as described in claim 1, characterized in that, The coupling agent is a silane coupling agent; The defoamer is BYK1810.

8. The two-component epoxy electronic potting compound as described in claim 1, characterized in that, The curing agent is a phthalic anhydride-based curing agent, and the curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

9. The two-component epoxy electronic potting compound as described in claim 1, characterized in that, The toughening agent is nitrile rubber.

10. A method for preparing a two-component epoxy electronic potting compound according to any one of claims 1-9, comprising: Preparation steps for component A: The epoxy resin and reactive diluent were stirred and dehydrated under vacuum at 100-110°C. Maintaining vacuum and temperature, add the composite thermally conductive filler and the flame retardant, and disperse them at high speed until uniform; Add the defoamer and the coupling agent, stir at low speed under vacuum to defoam, cool and discharge to obtain component A; Preparation steps for component B: The curing agent, the toughening agent and the curing accelerator are stirred and mixed at 40-50°C under vacuum until they are uniform and transparent. After cooling, the mixture is discharged to obtain component B. Mixing steps: The components A and B are mixed and cured at a weight ratio of (3-5):1 to obtain a two-component epoxy electronic potting compound.

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