A novel soldering method to evaluate PCB pad cratering for pin-pull testing

摘要

The pin-pull test has attracted attention because it can detect a high percentage of laminate cracking failures. In this study, a novel pin-pull test method is proposed to simplify pin soldering and the pin-pull test. The test method utilizes existing tools to perform the soldering and to collect quantitative data on the strength of printed circuit board (PCB) pad. The proposed procedure can be implemented with low cost and be adopted easily using any material or surface mounted technology (SMT) test laboratory. The procedure only requires a common tensile tester with regular copper pins and an external heat element to solder the pin to the pad. The impact of PCB pad design, manufacturing processes (including reflow and rework), thermal cycling, and long-term field usage on pad cratering are explored systematically based on the proposed method. The test result indicates that the high number of traces attached to the pad may significantly increase pad strength such that resistance to pad cratering is improved. Furthermore, pad strength dramatically declines when PCB pads are subjected to thermal stress or are used in the field for long periods.