A new power cycling technique for accelerated reliability evaluation of plated-through-holes and interconnects in PCBs

Abstract

A simple PCT (power cycling technique) that can rapidly assess the reliability of copper-plated-through-holes and associated interconnects in complex PCBs (printed circuit boards) has been developed. This PCT has been found to have the ability to quickly discriminate between barrels of good and poor reliability. Failure modes observed in PCT and MIL-T-shock test are identical; thus, a correlation between the two test techniques is valid. For PTH (plated-through-hole) barrels of poor quality, the correlation between the two methods regarding the number of cycles to failure is almost 1:1. This establishes the fact that PCT can, because of its avalanching effect, reliably screen PCBs of inferior quality in a short period of 100-120 cycles (15-20 h). A PCB passing 100-120 PCT cycles consistently passes 100 cycles of MIL-P-55110. The converse is also true. A near 2:1 correlation has been found between PCT and MIL-T-shock for PTH copper barrels of good quality. The design of a standard PCT coupon which will facilitate the use of fixed current levels for given barrel and track resistances and will allow comparison of reliability data from different sources is presented.<>