PURPOSE

This test is conducted for the purpose of determining the resistance of a component part to exposures at ! extremes of high and low temperatures in air, and to the shock of alternate exposures to these extremes. Permanent changes in operating characteristics and physical damage produced during thermal shock result principally from variations in dimensions and other physical properties. Effects of thermal shock include cracking and delamination of finishes, cracking and crazing of embedding and encapsulating compounds, opening of terminal seals and case seams, leakage of filling materials, and change in electrical characteristics- due to mechanical displacement or rupture of conductors or of insulating materials.