Contamination control coatings for hybrids

Conductive particles unexpectedly present in hermetically sealed hybrid microcircuit packages pose a high risk of shorting the closely spaced planar conductors within the package, causing failure of the device. The present work evaluates commercially available organic coating materials and determines the most promising ones for protection of complex microcircuits against entrapped particulate contaminants. The candidate materials were exposed to a series of physical and electrical screening tests, the results of which were used as a basis for the final coating selection. Silicones and high-purity epoxies are found to not only display excellent compatibility with microcircuits but to improve the performance of microcircuits as to voltage breakdown between adjacent conductors.