Resins used for these applications are generally one of four types, epoxy, polyester, polyurethane and silicone.Epoxy resins have been widely used for many years – they are generally hard and tough and exhibit low shrinkage on cure. They are characterized by an excellent level of mechanical properties, good high temperature performance and good adhesion to a wide variety of substrates, and show excellent chemical resistance across a wide range of chemicals. The cross-linking or curing process generally takes place slowly especially where small volumes of resin are involved. Fast cure hardeners can be used but these generate a lot of heat during cure, giving rise to a high exotherm which can damage electronic components and cause high mechanical stresses on both components and the circuit.

Polyurethane resins are elastomeric or rubbery in their cured state and are preferred where circuits to be potted contain delicate components such as ferrites or those with fragile legs. It is much easier to tailor the cure speed with urethane systems and the usable life and gel time of these can be adjusted to suit customer requirements, leading to faster process times and less work in progress. Generally polyurethanes show lower exotherm during cure than epoxies – the heat generated is not usually a problem, even for fast cure systems.

There are silicone’s for high temperature application, but are costly. Poly ester based resins are more exothermic

Resin casting is inevitable for the electronic systems where the system undergoes usage in rugged, humid and rainy environments.

Oven with 200 liters volume capacity was installed for curing of resin. Filling of the resin will be done manually. The facility shall be used for low volume production.