Root Causes Analysis on Malfunction of PCBA in Smartphone

In this paper, a failure case of the smartphones with an internationally renowned brand has been reported. In detail, after this batch of smartphones have been launched to the market, they encounter with the problems of scrambling display or no display frequently, and therefore have to be recalled and cause economic losses as high as nearly 4 million dollars. Through the preliminary analysis, the printed circuit board assembly (PCBA) has been determined as the faulty component. But what is the root cause and which process has the causes occur in should be further clarified, i.e., in the manufacturing of the printed circuit board (PCB) or in the assembling of PCBA? In this context, comprehensive failure analysis has been performed on the PCBA and PCB of the failed smartphones. Based on the results, the root causes of this failure have been determined, the failure mechanisms have been discussed and the pertinent countermeasures have also been proposed.