Processing and properties of silicon-carbon liquid encapsulants

In 1992, SYCAR resin, a new silicon-carbon thermosetting resin, was introduced to the electronics industry. Characteristics of the resin include excellent moisture resistance, ionic purity, low dielectric constant, and good-thermal properties. This combination of properties makes the resin particularly suited for encapsulant applications. In this paper, the processing and properties of silicon-carbon liquid encapsulants are presented in detail. Production of quality parts requires the use of proper dispensing and cure conditions. The rheology of the silicon-carbon liquid encapsulant as a function of filler level, shear, time, and temperature has been characterized as a guide in selecting proper processing conditions. The development of properties during cure for a range of cure temperatures has been studied to provide recommendations for curing conditions. In addition, the shelf life of the liquid encapsulants has been monitored at temperatures of -20/spl deg/C to ambient temperature over six months. The impact of these results on the processing, curing, and storage of SYCAR resin encapsulant is presented.<>