Encapsulation of Integrated Circuits Containing Beam Leaded Devices with a Silicone RTV Dispersion

This paper reviews the results of a number of investigations which have been performed to evaluate the use of an RTV silicone rubber dispersion for the encapsulation (conformal coating) of integrated circuits containing beam leaded silicon integrated circuit (SIC) devices. The dispersion consists of approximately 67-percent xylene and 33-percent solids by weight. The investigations described include: 1 ) measurement techniques for and typical values of the properties of the as-received dispersion and of the material after curing; 2) the determination of the suitability of the dispersion to be applied to integrated circuits containing SlC's by a flowcoat technique, and of its capability to completely fill under SlC's after curing; and 3) the performance of encapsulated test specimens and circuits in some initial accelerated bias-humidity and temperature cycling tests. In addition, several other factors relevant to determining the suitability of the dispersion for particular circuit applications are briefly dis- cussed.