When using silicone potting compounds to seal electronic components, we will find that there are two types of condensation and addition, the following are for condensation and addition silicone potting compounds to compare and explain.
Generally, condensation silicone potting compound will have stronger adhesion, waterproof level up to IP68, widely used in electronic components with high requirements for waterproof performance. The addition silicone potting compound has better thermal and electrical insulation properties, non-corrosive to electronic components, low shrinkage rate, more environmentally friendly.
Addition silicone potting compound in the waterproof performance has been a problem, while it is easier to appear not to cure, and N, S, P, As, organic tin and other compounds are very easy to react, at present can only be solved by the help of primer.
2. Curing Principle
The condensation silicone potting compound is through the part A liquid silicone and part B curing agent to absorb the moisture in the air, the active groups are condensed to release small molecules for cross-linking and curing, the curing process will shrink and there are by-products released.
The addition silicone potting compounds is cross-linked and cured by the addition reaction of silicon hydrogen bonding and ethylene double bonding. After AB mixing, even in a closed container, it does not need to absorb moisture in the air to assist curing, and no by-products are released in the reaction process, which determines the difference in their performance.
The curing speed of the addition silicone potting compound is not affected by the thickness, this is especially obvious in the clear silicone potting compound, condensation clear silicone potting compound more than 3mm thickness will be difficult to cure, addition clear silicone potting compound is not affected by the thickness.
The above is the analysis of the difference between addition and condensation silicone potting compounds, through the above study I believe you also have a certain understanding.