According to the reaction mechanism of the silicone rubber main body, the silicone electronic potting compound is mainly divided into a condensation type silicone electronic potting compound and an additive forming silicone electronic potting glue.
Composition and characteristics of silicone electronic potting compound:
◆Condensation type silicone electronic potting compound, mainly composed of 107 silicone rubber (α,ω-dihydroxypolydimethylsiloxane), methyltrimethoxysilane, dimethyldiethoxysilane, γ - A silane coupling agent such as aminopropyltriethoxysilane or tetraethyl orthosilicate is used as a crosslinking agent, and is prepared by using dibutyltin dilaurate as a catalyst.
Features: Volatile low molecular substances will be produced during the curing process, and there will be a significant shrinkage rate after curing.
◆Additional silicone electronic potting compound, based on vinyl silicone oil, hydrogen-containing silicone oil as cross-linking agent, Karstedt reagent as catalyst, with tackifier and inhibitor.
Features: There is no small molecular substance in the curing process, and the shrinkage rate is small.
Types and characteristics of functional fillers:
◆ Flame-retardant and heat-conductive filler: Silicone electronic potting compound with heat conduction and flame retardant function. Currently, the functional fillers commonly used are mainly heat conductive fillers and flame retardant fillers. There are many kinds of commonly used heat-conducting and flame-retardant fillers. At present, the main heat conductive filler is alumina, and the flame retardant filler is magnesium hydroxide.
Features: These fillers are excellent in heat conduction and flame retardancy, and have small particle size and are easily dispersed evenly in the silicone system.
The preparation of heat-conducting and flame-retardant silicone electronic potting glue is usually carried out by making A and B components. When using, a certain proportion of A and B components are thoroughly mixed by high-speed dispersing machine, and defoaming treatment is carried out. It is then used for potting of electronic components and then curing at room temperature or under heating.