Understanding Creep Corrosion Field Fails

Abstract

Dendrites, Electrochemical Migration (ECM) and parasitic leakage, are usually caused by process related contamination. For example, excess flux, poor handling, extraneous solder, fibers, to name a few. One does not normally relate these fails with environmental causes. However, creep corrosion is a mechanism by which electronic products fail in application, primarily related to sulfur pollution present in the air.1 The sulfur reacts with exposed silver, and to a lesser extent, exposed copper. This paper will explore various aspects of the creep corrosion chemical reaction: 1.What is driving the creep corrosion reaction? 2.Why is drying the product a necessary precursor to obtaining creep corrosion in tests?2, 3 3.Test methods with Flowers of Sulfur, FoS, and sulfur rich clay. 4.Discussion of creep corrosion related field fails. 5.When does creep corrosion become ECM. 6.Sources of sulfur containing pollution. 7.Methods to take to avoid creep corrosion. While there are places with sulfur containing pollution, creep corrosion will be a factor which will impact reliability. Creep corrosion will need to be understood and handled.