Fatigue model based on average cross-section strain of Cu trace cyclic bending

Abstract

This study focuses on quasi-static mechanical cycling durability of copper traces on printed wiring assemblies (PWAs). PWA specimens populated with Land Grid Array (LGA) components on copper-defined pads were cycled to failure under zero-to-max, three-point bending. Failure is defined in terms of electrical opens due to fatigue damage propagation through the entire cross-section of the trace. Failure statistics were collected and failure analysis was conducted to identify fatigue failures in the copper traces, near the connection to the solder pad.