Proximity sensor encapsulation - in silicone rubber mould by polyurethane foam injection

摘要

Electronic components, e.g. proximity sensors and modules, are encapsulated by injecting into the split mould, produced from casting resin, a multi-component plastic material which is converted into a foam, esp. integral polyurethane foam, and forms a solid coating when the pores break up on contact with the mould. A retarding agent ensures that foaming is delayed until the liq. material has filled the mould. Glass fibres can be blown into the mould before the injection to form a deposit on the walls. This is a simple low-cost process which permits thinner walls and requires little fettling.