Accelerated Life Testing of Flexible Printed Circuits

Part I of this paper describes a facility which has recently been developed to conduct accelerated life tests on-printed wiring products. Procedures developed for the evaluation of flexible printed circuits are outlined, and a representative set of life test data is reviewed to illustrate the kinds of information obtainable with this facility. In conducting accelerated life tests on fineline flexible printed circuits coated with UV-cured resins, failures have been observed to occur in virtually every part of the circuit structure. In Part II, the various failure modes are described and are categorized according to the principal structural element involved (e.g., cover-coat, substrate, etc.). In many cases environmental domains have been identified, within which there is a clear predominance of a specific failure mode.