CN101735619B - Halogen-free flame-retarded heat-conducting organic silicon electronic potting adhesive and preparation method thereof - Google Patents

Abstract

The invention discloses a halogen-free flame-retardant heat-conducting silicone electronic potting glue and a preparation method thereof. Vinyl polydimethylsiloxane, reinforcing material, heat-conducting filler and halogen-free flame retardant are added into a vacuum kneader , at a temperature of 100-150° C., a vacuum of 0.06-0.1 MPa, dehydration and blending for 30-120 minutes to obtain a base material. At room temperature, add hydrogen-containing silicone oil cross-linking agent and cross-linking inhibitor to the base material, stir well for 10-30 minutes to make component A; add platinum catalyst to the base material, stir well for 10-30 minutes to make component B . Then take equal weight parts of component A and component B and blend them evenly, and defoam in a vacuum of 0.06-0.1 MPa for 5-10 minutes to obtain a halogen-free flame-retardant and heat-conducting silicone electronic potting compound. The encapsulant has good fluidity, is easy to use, and can be cured at room temperature or high temperature. The cured product has excellent flame retardancy and thermal conductivity, and can be widely used in electronic appliances, chip packaging, LED packaging and other fields.

Description

A kind of halogen-free flame-retardant heat-conducting silicone electronic potting glue and preparation method thereof

technical field

The invention relates to the technical field of electronic potting materials, in particular to a halogen-free flame-retardant heat-conducting silicone electronic potting compound and its preparation technology.

Background technique

With the further realization of high performance, high reliability and miniaturization in electronic components, power circuit modules, large integrated circuit boards, LED and other high-tech fields, and the harsher working environment, it is required that the potting parts must be between low temperature and high temperature, Operating under conditions such as high-speed rotation requires potting materials not only to have excellent high and low temperature resistance, mechanical properties, electrical insulation properties, etc., but also to have good thermal conductivity and flame retardancy.

At present, the most widely used potting materials are various synthetic polymers, among which epoxy resin, polyurethane and synthetic rubber are widely used. Silicone rubber can maintain elasticity in a wide temperature range for a long time, does not absorb or release heat during vulcanization, and has excellent electrical properties and chemical stability. It is the preferred material for potting electronic and electrical assemblies. However, the thermal conductivity of typical unfilled silicone rubber is very poor, the thermal conductivity is only 0.2W/m·K, and the flame retardancy is poor, and it can burn completely once it is ignited. Therefore, in order to obtain electronic potting materials with better thermal conductivity and flame retardancy, it is often necessary to modify silicone rubber. At present, although there are some domestic research reports on halogen-free flame-retardant and heat-conducting potting compounds, most of them focus on a single heat conduction or flame retardancy. For example, Chinese patent application CN 101054057A discloses a high thermal conductive silicone potting compound, and CN 101407635A discloses an addition type thermal conductive silicone rubber with excellent fluidity and high thermal conductivity, but neither of these two patents mentions silicon Flame retardant properties of rubber. And the Chinese patent application CN 101121820A discloses a kind of flame-retardant grade is the halogen-free flame-retardant silicone rubber of FV-0 level, but this patent does not mention the thermal conductivity of silicone rubber. Chinese patent application CN 101402798A discloses a heat-conducting and flame-retardant liquid silicone rubber for electronics. Although it has high thermal conductivity and flame-retardant properties, it cannot be used as Electronic potting compound.

Contents of the invention

The purpose of the present invention is to address the deficiencies in the prior art, to provide a halogen-free flame-retardant heat-conducting silicone electronic potting compound and its preparation method, which is characterized in that the halogen-free flame-retardant heat-conducting silicone electronic potting compound not only has excellent Flame retardant and thermal conductivity and excellent flow properties, but also environmentally safe and easy to operate.

The preparation method of the halogen-free flame-retardant heat-conducting silicone electronic potting compound of the present invention comprises the following steps:

(1) Preparation of base material: Add vinyl polydimethylsiloxane, reinforcing material, thermally conductive filler and halogen-free flame retardant into the vacuum kneader, at 100-150°C, vacuum degree 0.06-0.1MPa , blended for 30 to 120 minutes to obtain the base material;

The parts by weight of raw materials are as follows:

Vinyl Dimethicone 100 parts

Reinforcement material 2～20 parts

Thermally conductive filler 100-300 parts

Halogen-free flame retardant 50-100 parts;

(2) Preparation of component A: at room temperature, add a hydrogen-containing silicone oil crosslinking agent and a crosslinking inhibitor with a hydrogen content of 0.3 to 1.6 wt% to the base material prepared in step (1), and stir thoroughly 10 to 30 minutes to prepare component A,

The parts by weight of raw materials are as follows:

Base material 100 parts

Hydrogen silicone oil 0.2～45 parts

Cross-linking inhibitor 0.002～0.01 parts;

(3) Preparation of component B: at room temperature, take the base material prepared in step (1), add a platinum catalyst with a platinum content of 1000 to 5000 ppm, and fully stir for 10 to 30 minutes to prepare component B; The weight ratio of material and platinum catalyst is 100: 2.0～100: 0.01;

(4) Preparation of halogen-free flame-retardant and heat-conducting silicone electronic potting compound: at room temperature, take equal weights of component A prepared in step (2) and component B prepared in step (3) and mix evenly, Degassing for 5 to 10 minutes under a vacuum degree of 0.06 to 0.1 MPa to obtain a halogen-free flame-retardant and heat-conducting silicone electronic potting compound.

The vinyl polydimethylsiloxane described in step (1) is one or more of linear vinyl polydimethylsiloxane or branched vinyl polydimethylsiloxane The mixture of vinyl polydimethylsiloxane has a vinyl content of 0.3-3.0 wt%, and a viscosity of 200-3000 mPa·s at 25°C.

The reinforcing material described in step (1) is a methyl vinyl MvQ resin with a vinyl content of 0.1-5 wt%. The thermally conductive filler described in step (1) is one of aluminum oxide, aluminum nitride, aluminum boride, silicon carbide or silicon nitride treated with a coupling agent surface with an average particle size of 2 to 20 μm or a mixture of two or more. The halogen-free flame retardant in the step (1) is one or more mixtures of aluminum hydroxide, magnesium hydroxide or zinc borate with an average particle size of 2-10 μm and surface-treated with a coupling agent. The surface treatment by the coupling agent can adopt the surface treatment method commonly used in the technical field. The present invention preferably dilutes the coupling agent with a suitable solvent, mixes it with a thermally conductive filler or a halogen-free flame retardant, and then heats and dries it. . The present invention has no limitation on the type of coupling agent, and coupling agents commonly used in the technical field can be used, for example: isopropyl distearoyloxyaluminate and γ-methacryloxypropyl trimethoxysilane .

The catalyst is an alcohol solution of chloroplatinic acid or a vinyl siloxane complex of chloroplatinic acid.

The crosslinking inhibitor is 2-methyl-3-butynyl-2-alcohol, 2-methyl-1-hexynyl-3-alcohol, 3,5-dimethyl-1-hexynyl -3-alcohol, 1-ethynyl-1-cyclohexanol, methyl(trimethylbutynyloxy)silane, phenyl(trimethylbutynyloxy)silane, vinyl(trimethylbutynyloxy)silane at least one of oxy)silane and phenylacetylene.

A halogen-free flame-retardant heat-conducting silicone electronic potting compound prepared by the preparation method described in the present invention.

The halogen-free flame-retardant and heat-conducting silicone electronic potting compound prepared by the above method shall be tested for viscosity according to GB/T 10247-2008, and shall be tested for Shore A hardness according to GB/T 531-2008; tested for tensile strength according to GB/T 528-1998 Tensile strength and elongation at break; test dielectric strength according to GB/T1408.1-2006; test volume resistivity according to GB/T 1410-2006; test thermal conductivity according to GB/T11205-2009; test flame retardant according to UL 94 level.

Compared with the prior art, the present invention has the following advantages:

1. The halogen-free flame-retardant heat-conducting silicone electronic potting compound of the present invention is added with an appropriate amount of heat-conducting fillers and halogen-free flame retardants with excellent electrical properties, so that it has excellent thermal conductivity and high flame retardancy ;

2. Using methyl vinyl MvQ resin instead of white carbon black as a reinforcing material not only reduces the viscosity of silicone potting adhesive, but also facilitates the filling and dispersion of thermally conductive fillers and flame retardants;

3. The halogen-free flame-retardant and heat-conducting silicone electronic potting adhesive of the present invention does not contain halogens and harmful heavy metals, and does not produce toxic substances or irritating odors during production and curing, and has no by-products, which is environmentally friendly and safe.

Detailed ways

Example 1:

Weigh 200 parts by weight of aluminum oxide and add it into a high-speed kneader, and slowly add 1 part by weight of isopropyl distearoyloxyaluminate completely dissolved in white oil in advance under the condition of high-speed stirring. Then heat up to 120°C and continue to stir at high speed for 2 hours, discharge the material, put the obtained filler in a vacuum drying oven to remove the residual white oil, and sieve to obtain isopropyl distearoyl aluminum with an average particle size of 5 μm Ester surface treated aluminum oxide.

Weigh 200 parts by weight of aluminum hydroxide and add it into a high-speed kneader, slowly add 1 part by weight of γ-methacryloxypropyl trimethoxysilane diluted with ethanol alcohol solution of water in advance under the condition of high-speed stirring, drop After the addition, raise the temperature to 120°C and continue stirring at high speed for 2 hours, discharge the material, put the obtained filler in a vacuum drying oven to remove residual water and ethanol, and sieve to obtain γ-methacryloyl with an average particle size of 2.7 μm Aluminum hydroxide surface treated with oxypropyltrimethoxysilane.

100 parts by weight of straight-chain vinyl polydimethylsiloxane with a viscosity of 500mPa·s and a vinyl content of 0.45 wt%, and 7.14 parts by weight of methyl vinyl MvQ resin with a vinyl content of 3.5%, the above-mentioned treatment 140 parts by weight of the processed aluminum oxide and 60 parts by weight of the above-mentioned treated aluminum hydroxide were put into a vacuum kneader, and dehydrated and blended for 60 minutes at a temperature of 120° C. and a vacuum of 0.08 MPa to obtain a base material.

Mix 4.1 parts by weight of a hydrogen-containing silicone oil crosslinking agent with a hydrogen content of 0.5%, 0.0065 parts by weight of a crosslinking inhibitor 1-ethynyl-1-cyclohexanol, and 100 parts by weight of a base material for 20 minutes to obtain Group A point. 0.25 parts by weight of a vinyl siloxane complex of chloroplatinic acid with a platinum content of 2600 ppm and 100 parts by weight of a base material were stirred and mixed for 20 minutes under a mixer to obtain component B.

Take equal parts of component A and component B and blend them uniformly at room temperature, then defoam for 8 minutes at a vacuum of 0.1 MPa to obtain a halogen-free flame retardant and thermally conductive silicone electronic potting compound. The performance test results are shown in the table 1. It can be seen that the encapsulant has good flame retardant thermal conductivity, fluidity, electrical properties and mechanical properties.

Example 2:

The preparation method and conditions of the halogen-free flame-retardant heat-conducting silicone electronic potting compound of the present invention are as in Example 1, and the heat-conducting filler is changed to the average The average particle diameter of 105 parts by weight of aluminum oxide with a particle diameter of 5 μm and the surface treatment of the coupling agent isopropyl distearoyloxyaluminate (using the same surface treatment method as in Example 1) is 19 μm Using 35 parts by weight of Al2O3, a halogen-free flame-retardant and heat-conducting silicone electronic potting compound was prepared, and the performance test results are shown in Table 1. It can be seen that compared with Example 1, its thermal conductivity increased from 0.65W/m K to 0.75W/m K, while other properties did not change much. It can be seen that the compounding of fillers with different particle sizes is beneficial to improve Thermal conductivity of potting compound.

Example 3:

The preparation method and conditions of the halogen-free flame-retardant heat-conducting silicone electronic potting compound of the present invention are as in Example 1, and the vinyl polydimethylsiloxane is changed to a polydimethylsiloxane with a viscosity of 300mPa·s and a vinyl content of 0.72wt%. Straight-chain vinyl polydimethylsiloxane, correspondingly increase the hydrogen-containing silicone oil crosslinking agent with a hydrogen content of 0.5% to 5.6 parts by weight to prepare a halogen-free flame-retardant and heat-conducting silicone electronic potting compound, performance test The results are shown in Table 1. It can be seen that compared with Examples 1 and 2, although the thermal conductivity of the encapsulant is reduced, its fluidity is significantly improved, and its viscosity is only 2600 mPa·s.

Example 4:

The preparation method and conditions of the halogen-free flame-retardant heat-conducting silicone electronic potting compound of the present invention are as in Example 1, the methyl vinyl MvQ resin with a vinyl content of 3.5% of the reinforcing filler is increased to 14.28 parts by weight, and the content of The hydrogen-containing silicone oil crosslinking agent with a hydrogen content of 0.5% was increased to 5.5 parts by weight to prepare a halogen-free flame-retardant and heat-conducting silicone electronic potting compound. The performance test results are shown in Table 1. It can be seen that increasing the content of methyl vinyl MvQ resin in an appropriate range is beneficial to the improvement of the tensile strength of the potting compound, but has little effect on other properties.

Example 5

Weigh 200 parts by weight of silicon carbide and add it into a high-speed kneader, slowly add 1 part by weight of isopropyl distearoyloxyaluminate completely dissolved in white oil in advance under the condition of high-speed stirring, and heat up after the addition is completed Continue high-speed stirring at 120°C for 2 hours, discharge, put the obtained filler in a vacuum drying oven to remove residual white oil, and sieve to obtain isopropyl distearoyloxyaluminate with an average particle size of 2 μm Surface-treated silicon carbide.

Weigh 200 parts by weight of zinc borate and add it into a high-speed kneader, and slowly add 1 part by weight of γ-methacryloxypropyltrimethoxysilane diluted with ethanol alcohol solution with water under the condition of high-speed stirring, dropwise After completion, heat up to 120°C and continue stirring at high speed for 2 hours, discharge the material, place the obtained filler in a vacuum drying oven to remove residual water and ethanol, and sieve to obtain γ-methacryloyloxy with an average particle size of 10 μm. Zinc borate surface treated with propyltrimethoxysilane.

20 parts by weight of a branched vinyl polydimethylsiloxane with a viscosity of 3000 mPa·s and a vinyl content of 3 wt%, and a linear vinyl polydimethylsiloxane with a viscosity of 300 mPa·s and a vinyl content of 0.72 wt%. 80 parts by weight of dimethylsiloxane, 2 parts by weight of methylvinyl MvQ resin with a vinyl content of 5wt%, 100 parts by weight of the above-mentioned treated silicon carbide, and 100 parts by weight of the above-mentioned treated zinc borate are added to the vacuum kneader , at a temperature of 100° C. and a vacuum of 0.06 MPa, dehydration and blending for 30 minutes to obtain a base material.

12.6 parts by weight of a hydrogen-containing silicone oil crosslinking agent with a hydrogen content of 0.3%, 0.002 parts by weight of a crosslinking inhibitor vinyl (trimethylbutynyloxy) silane and 100 parts by weight of a base material were fully stirred and mixed for 10 minutes to obtain A component. 2 parts by weight of an isopropanol solution of chloroplatinic acid with a platinum content of 1000 ppm and 100 parts by weight of base material were stirred and mixed under a mixer for 10 minutes to obtain component B.

Take equal parts of component A and component B and blend them uniformly at room temperature, then defoam for 5 minutes under a vacuum of 0.06 MPa to obtain a halogen-free flame retardant and thermally conductive silicone electronic potting compound. The performance test results are shown in the table 1. It can be seen that the encapsulant has good comprehensive properties, and the addition of an appropriate amount of branched vinyl silicone oil helps to improve the tensile strength of the encapsulant.

Example 6

Weigh 200 parts by weight of aluminum nitride and add it into a high-speed kneader, and slowly add 1 part by weight of isopropyl distearoyloxyaluminate completely dissolved in white oil in advance under the condition of high-speed stirring. Heat up to 120°C and continue stirring at high speed for 2 hours, discharge the material, put the obtained filler in a vacuum drying oven to remove the residual white oil, and sieve to obtain isopropyl distearoyloxyaluminate with an average particle size of 2 μm Aluminum nitride with ester surface treatment.

Weigh 200 parts by weight of magnesium hydroxide and zinc into a high-speed kneader, slowly add 1 part by weight of gamma-methacryloxypropyltrimethoxysilane diluted with ethanol-alcohol solution of water in advance under the condition of high-speed stirring, After the dropwise addition, raise the temperature to 120°C and continue stirring at a high speed for 2 hours, discharge the material, place the obtained filler in a vacuum drying oven to remove residual water and ethanol, and sieve to obtain γ-methacryloyl with an average particle size of 10 μm. Oxypropyltrimethoxysilane surface treated magnesium hydroxide.

100 parts by weight of linear vinyl polydimethylsiloxane with a viscosity of 200 mPa·s and a vinyl content of 0.8 wt%, and 20 parts by weight of methyl vinyl MvQ resin with a vinyl content of 0.1 wt%. 300 parts by weight of the treated aluminum nitride and 50 parts by weight of the above-mentioned treated magnesium hydroxide were put into a vacuum kneader, and dehydrated and blended for 120 minutes at a temperature of 150° C. and a vacuum of 0.1 MPa to obtain a base material.

1.0 parts by weight of a hydrogen-containing silicone oil crosslinking agent with a hydrogen content of 1.6 wt%, 0.01 parts by weight of a crosslinking inhibitor phenylacetylene and 100 parts by weight of a base material were thoroughly stirred and mixed for 30 minutes to obtain component A. 0.01 parts by weight of vinyl siloxane complex of chloroplatinic acid with a platinum content of 5000 ppm and 100 parts by weight of base material were stirred and mixed under a mixer for 30 minutes to obtain component B.

Take equal weight parts of component A and component B and blend them uniformly at room temperature, then defoam for 10 minutes under a vacuum of 0.1 MPa to obtain a halogen-free flame retardant and thermally conductive silicone electronic potting compound. The performance test results are shown in the table 1. It can be seen that after adding a large amount of aluminum nitride with a high thermal conductivity, the thermal conductivity of the potting compound has been significantly improved, reaching 1.12W/m K, and the potting compound still maintains good flame retardancy , flow properties, electrical properties and mechanical properties.

Table 1

performance Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Viscosity (mPa·s) 4500 4400 2600 4650 3900 5060 Density (g/cm ³ ) 1.86 1.86 1.85 1.85 1.81 2.1 Hardness (Shore A) 55 56 60 59 58 75 Tensile strength (MPa) 2.76 2.70 2.8 2.94 2.88 3.3 Elongation at break (%) 45 40 30 38 28 20 Dielectric strength (KV/mm) 20 20 twenty two twenty one twenty two 18 Volume resistivity (Ω·cm) 1.1×10 ¹⁵ 1.1×10 ¹⁵ 1.2×10 ¹⁵ 1.2×10 ¹⁵ 1.3×10 ¹⁵ 9.8×10 ¹⁴ Thermal conductivity (W/m K) 0.65 0.75 0.62 0.67 0.54 1.12 Flame retardant level (UL 94) V-0 V-0 V-0 V-0 V-0 V-0

Claims (7)

1. the preparation method of a halogen-free flame-retarded heat-conducting organic silicon electronic potting adhesive is characterized in that specifically may further comprise the steps:

(1) preparation of base-material: vinyldimethicone, supporting material, heat conductive filler and halogen-free flame retardants are added in the vacuum kneader, at 100～150 ℃, under vacuum tightness 0.06～0.1MPa, 30～120 minutes acquisition base-materials of blend;

Raw materials in part by weight is as follows:

(2) preparation of A component: at normal temperatures, in the base-material that step (1) makes, adding hydrogen content is containing hydrogen silicone oil linking agent and the cross-linked inhibitor of 0.3～1.6wt%, fully stirs and made the A component in 10～30 minutes,

Raw materials in part by weight is as follows:

100 parts of base-materials

0.2～45 part of containing hydrogen silicone oil

0.002～0.01 part of cross-linked inhibitor;

(3) preparation of B component: at normal temperatures, get the base-material that step (1) makes, adding platinum content is the platinum catalyst of 1000～5000ppm, fully stirs and makes the B component in 10～30 minutes; The weight ratio of described base-material and platinum catalyst is 100: 2.0～100: 0.01;

(4) preparation of halogen-free flame-retarded heat-conducting organic silicon electronic potting adhesive: at normal temperatures, the B component that A component that the step (2) of weight makes and step (3) make such as getting mixes, deaeration is 5～10 minutes under vacuum tightness 0.06～0.1MPa, obtains halogen-free flame-retarded heat-conducting organic silicon electronic potting adhesive;

Supporting material described in the step (1) is that contents of ethylene is the methyl ethylene MvQ resin of 0.1～5wt%.

2. preparation method according to claim 1, it is characterized in that vinyldimethicone described in the step (1) is one or more the mixture in straight chain type vinyldimethicone or the branched chain type vinyldimethicone, the contents of ethylene of vinyldimethicone is 0.3～3.0wt%, and the viscosity in the time of 25 ℃ is 200～3000mPas.

3. preparation method according to claim 1 is characterized in that heat conductive filler described in the step (1) is that median size is one or more the mixture in the surface-treated aluminium sesquioxide of coupling agent, aluminium nitride, aluminum boride, silicon carbide or silicon nitride of 2～20 μ m.

4. preparation method according to claim 1, it is characterized in that halogen-free flame retardants described in the step (1) be median size be 2～10 μ m through coupling agent surface-treated aluminium hydroxide, magnesium hydroxide or zinc borate in one or more mixture.

5. preparation method according to claim 1 is characterized in that described catalyzer is the alcoholic solution of Platinic chloride or the vinylsiloxane complex compound of Platinic chloride.

6. preparation method according to claim 1, it is characterized in that described cross-linked inhibitor is 2-methyl-3-butynyl-2-alcohol, 2-methyl isophthalic acid-hexin base-3-alcohol, 3, one or more mixture in 5-dimethyl-1-hexin base-3-alcohol, 1-ethynyl-1-hexalin, methyl (trimethylammonium fourth alkynyloxy group) silane, phenyl (trimethylammonium fourth alkynyloxy group) silane, vinyl (trimethylammonium fourth alkynyloxy group) silane or the phenylacetylene.

7. halogen-free flame-retarded heat-conducting organic silicon electronic potting adhesive that makes by the described preparation method of claim 1.