Testing method for measuring corrosion resistance of surface mount chip resistors

Surface mount chip resistors are amongst the simplest and most inexpensive of all components used in electronic circuits and systems. Typically, resistor failure modes include open circuits, resistive shorts or variations in resistance indicating parametric drift or intermittent failure, which in some applications result in overall system failure. Corrosion is currently believed to be the number one failure mechanism for chip resistors deployed in developing markets such as Central and Latin America, Asia, India and Pacific regions where aggressive corrosive conditions are prevalent. The objective of this study is to develop a test to identify or screen out corrosion-susceptible parts. Ten precision chip resistors types representative of resistors in contemporary printed circuit board assemblies are subjected to a well-defined multi-stress screen which comprises thermal cycling and mixed flowing gas exposure. The combination of thermal cycling and corrosive gas exposure is shown to provide an acceptable acceleration test to identify corrosion-susceptible parts by replicating field failures. Currently, no other test method exists which is capable of replicating field failures.