Polyurethane foams for environmental protection

A great deal of importance has been placed on electronics during the age of automation and the ever increasing requirement for high reliability of electronic packages. Numerous problems have been encountered in assuring the successful and continuous operation of electronics in different environments. Temperature variations both high and low, humidity changes, shock and vibration are some of the major problems that have been encountered. Until a decade ago, the most widely accepted solutions for these problems was the use of epoxy resins. The biggest disadvantage of epoxy´s is their high weight. Excess poundage added by epoxies is undesirable for airborne electronic units and ground computor installations. Many manufacturers began searching for a new material that would meet their specifications and have a lower density than the epoxies. The proper selection and correct applications of polyurethane foams seemed to be the logical answer. A tyical example is found in Remington Rand´s Univac where a 10 pound PCF density polyurethane replaced a 120 pound PCF epoxy. The use of Urethanes can mean a reduction of a half ton in a large computor.