Failure of Thick-Film Chip Resistors in Sulfur-Containing Environments

摘要

Thick-film chip resistors are a high volume commodity product used in a variety of electronic equipment. These resistors are used in a number of industries including communications, automotive, agricultural and consumer electronics. A common conductive material used in the conductor of these resistors is silver. When exposed to sulfur-containing environments, chip resistors with a silver-base conductor are susceptible to becoming electrically open. Vishay investigated a number of open circuit boards located in the operators control console of agricultural equipment. It was determined that each failure was the result of a reaction between the sulfur from the environment and the silver in the conductor to form non-conductive silver sulfide. The results of this investigation, including details of the failure mechanism and the identification of the sulfur source, are presented. Vishay has developed a new series of chip resistors, designated RCA, which is robust to the degradation of the conductor in sulfur-containing environments. Information regarding the RCA series of resistors is presented.