Development of Technology for Estimating Sulfide Corrosion Lifetime of Coated Electronic Compornents with Conformal Coating

Abstract

In order to stably operate electronic equipment in environments where sulfide-corrosion-induced failures occur, we investigated the effectiveness of a coating process as a countermeasure against the corrosion of electronic components mounted on printed circuit boards. We have clarified that the sulfide corrosion behavior of coated electronic components with conformal coating is dependent on the transmission of reduced sulfur. Further, we established a new gas transmission test method and a sulfide corrosion life estimation method. The sulfide corrosion lifetime of a chip resistor with high sulfide corrosivity was estimated using the diffusion coefficient and the solubility coefficient of the conformal coating calculated using the gas transmission test. Based on the estimate of the sulfide corrosion lifetime, we have created an anticorrosive design diagram to determine the coating thickness needed to satisfy the design life target.