Failure analysis on cracking of blind and buried vias of printed circuit board for high-end mobile phones

Abstract

Purpose The submitted paper is mainly concerned with the cracking of blind and buried vias of printed circuit board (PCB) for smartphones which were encountered with abnormal display problems like scramble display or no display during service and had to be recalled. Design/methodology/approach To found out the root causes of this failure and dissolve this commercial dispute, comprehensive failure analysis was performed on the printed circuit board assemblies (PCBAs) and PCBs of the failed smartphone, such as macrograph and micrograph observation, chemical compositions analysis, thermal performance testing and blind via pull-off experiment, which finally helped to determine the causes. Besides that, the failure mechanisms were discussed in detail, and pertinent countermeasures were proposed point by point. Findings It was found that the PCB blind vias cracking was the main reason for the scramble display or no display of the smartphone, and the incomplete cleaning process before copper plating was the root cause of the blind vias cracking. Practical implications Achievement of this paper would not only help to provide the solid evidence for determining the responsibility of this commercial dispute but also lead to a better understanding of the failure mechanisms and prevention methods for similar failure cases of other advanced mobile phones. Originality/value Most failure analysis researches of PCBAs only focused on the unqualified products from manufacturing, while this paper addressed a failure analysis case of PCBAs products for smartphones from actual services, which was relatively rarely reported in the past.