First, the background
Potting materials are varied, but the most widely used ones are mainly synthetic polymers. Among them, epoxy resin, polyurethane elastomer and silicone polymer are the most widely used polymers. Faced with moisture resistance, heat resistance, internal stress problems, etc., the problem that polyurethane has difficulty in application is that the surface of the potting compound is too soft, easy to foam, insufficient curing and brittle when cured at high temperature, in harsh conditions. Polyurethane potting materials in the working environment are often difficult to meet the requirements of resistance to humidity, heat, aging and high temperature. Silicone polymer materials are widely used in electronic appliances due to their unique silicone-bonded backbone structure, unique weather resistance, aging resistance, excellent high and low temperature resistance, good hydrophobic mechanical properties, electrical insulation, etc. Potting protection of components; this scheme selects silicone potting (inorganic electronic potting, which belongs to other materials, such as low-melting glass powder application technology, and will be shared separately).


Second, silicone potting glue
2.1 Composition and classification of silicone potting compound
The silicone potting compound is composed of a silicone resin, a crosslinking agent, a catalyst, a heat conductive material and the like. Silicone rubber potting compound can be divided into room temperature vulcanized silicone rubber according to molecular structure and crosslinking method; two-component plus forming silicone rubber potting compound (ARC silicone rubber); two-component condensation type silicone rubber potting compound (RTV silicone rubber) )
ARC silicone rubber adhesive cures without small molecules, and the crosslinked structure is easy to control. The shrinkage rate is below 0.2%. The electrical properties and elasticity are better than RTV silicone rubber, and the process performance is superior. It can be cured at room temperature or at the same time. Cured in a short time after heating. Therefore, ARC silicone rubber potting compound is recognized as a new material for the electronics industry with great development at home and abroad.


2.2 Two-component plus forming silicone rubber potting compound
Common two-component and formed silicone rubber potting compound: composed of terminal vinyl silicone oil as base rubber, hydrogen-containing silicone oil as crosslinking agent, and aluminum oxide (A l2O3 ) as heat conductive filler. Methacryloxypropyltrimethoxysilane (KH570) may be added as a coupling agent, and a platinum catalyst (PL-2600) may be used as a catalyst.
The main content of this paper is based on vinyl silicone oil, which contains ammine micron brand 507 anhydrous transparent silicon micropowder as the main functional filler. Amy micro-nano Q702 nano-light silicon powder can be added to prevent sinking, thixotropic and thickening functions, so as to reduce the amount of base rubber material and reduce the proportion of finished products. The organic solvent may be diluted with an appropriate alcohol during the experiment.


2.2.1 Realizing product indicators






Third, the formula reference
A, B components (match according to the use)
ingredient
Mass percentage
Indicator reference requirements
Vinyl silicone oil
About 35%
Viscosity 300 mPa s (Note: viscosity is as low as possible, according to formulation cost and market factors); specific gravity is about 0.9, lower.
507 (or 602 or 125 if it is a high-end material)
About 62%
Functional filler
Q702
About 3%
Anti-settling, density about 0.1
Alcohol thinner
0.1-0.5%
Moderate fine-tuning
Toner


Add as needed to reduce the corresponding filler share
Through formulation testing and process realization, the product achieves low viscosity, high fluidity and low specific gravity. Have any questions during the test and communicate with the company's technical engineers.


Fourth, the product formula ingredients description
1. The main characteristics of vinyl silicone oil are colorless, odorless, non-toxic, non-volatile liquid, insoluble in water, miscible with benzene, dimethyl ether, methyl ethyl ketone, tetrachlorocarbon or kerosene, slightly soluble Acetone, ethanol. It has a small vapor pressure, a high flash point and a flash point, and a lower freezing point. As the number of segments n differs, the molecular weight increases and the viscosity increases. Thus, the vinyl silicone oil can have various viscosities. Widely used in the production of silicone rubber to enhance the strength and hardness of silicone rubber. It is used to make liquid silicone rubber. It is the main material for injecting thermoformed silicone rubber and additive electronic potting glue, and making ink, adding sealant and so on.
2, T507 anhydrous transparent powder, is made of high-purity magnesium aluminosilicate crystalline ore by deep processing, effective element Al / Si / O, crystal structure, effective composition > 99.8%, the product has passed in SGS “European RoHS Six Tests”, which does not contain heavy metals, is a new type of environmentally friendly inorganic non-metallic functional powder.
[Description of particle size] D50≈20um, 700 mesh, normal distribution, uniform particle size and concentrated distribution.
[Instructions for use] For marble glue, in addition to improving the mechanical strength of the colloid, increasing the filling rate, reducing the curing heat and prolonging the construction time, preventing collapse, the most competitive is the transparent color, high transmittance, and more Suitable for transparent marble glue and toning base glue.
[T507B features] Hue transparent: low iron content, soft hue, high light transmittance, suitable for transparent glue and color base rubber; complete specifications: 200 mesh, 400 mesh, 600 mesh, 800 mesh, 1000 mesh, 1250 mesh Etc.; low oil absorption: high filling, good fluidity, good anti-sinking; hardening and anti-wear: hardness 7.3, improve the mechanical strength and wear resistance of the colloid; low thermal expansion: resistance to thermal shock, low shrinkage, anti- Collapse; good fluidity: uniform particle size distribution, smooth spherical shape, low viscosity; stable physical properties: no crystal water, no water, white water, fog, acid and alkali corrosion.


3, product brand "Q702 nano light silicon powder" commonly known as "white carbon black", "nano-silica", is an environmentally friendly new nano-hollow spherical functional powder material, is a stable substrate material for transparent white phase materials . The product has multiple functions of light filling, matte finish, reinforcement, thixotropic, anti-settling, thickening and dispersion. The product has the characteristics of low specific gravity, superfine and granular, and has good compatibility with resin, plastic and rubber. It improves the overall function of the material, such as toughness, tear resistance, weather resistance and resistance, without impairing the material properties. Yellowing, acid and alkali resistance. The product is cost-effective and versatile. It uses Q702 nano-light silicon powder to reduce the cost of the formula and increase the efficiency of the enterprise. The product is best suited for use in high-end waterborne coatings, inks, paints, silicone rubber, plastics, adhesives and paper.


[Q702 nano light silicon powder features]
◆ Inorganic ultra-fine powder, low carbon environmental protection, stable and light weight (bulk density 0.13), good hue, blue transparent phase;
◆ Granules, hollow spheres, excellent physical and chemical properties;
◆ Free of crystal water, smooth and dry, low oil absorption, good fluidity and easy to disperse;
◆ The product has high weather resistance, yellowing resistance, acid and alkali resistance and high temperature resistance.
[Advantages of using Q702 nano-light silicon powder]
1. Cost advantage: The unit price of resin products is high and fluctuating, and the use of 15~30% filling can bring greater profits.
2, improve the toughness: can comprehensively improve the original tear strength performance of the material more than 30%.
3, improve the function: thixotropic, anti-settling, thickening and matte functions, can comprehensively improve the material comprehensive parameters more than 30%.
[Physical and Chemical Indicators] (main element Si/O)
project
index
project
index
project
index
% reduction
≤0.3
Average particle size um
7.09
Refractive index
1.46
Active ingredients
≥99.0
Scraper, um
23.00
Bulk density
0.13
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