PCBA开路失效案例研究

A Case Study of Open Circuit Failure of PCBA

介绍了一例由于孔铜断裂而导致PCBA开路失效的案例,利用金相切片、扫描电子显微镜和热机械分析仪对样品进行了分析,找到了故障原因。研究发现失效PCBA过孔存在腐蚀使得孔铜偏薄或开裂,同时PCB的Z轴热膨胀系数高于规范上限,进一步地加剧了孔铜断裂现象的发生。

A case of open circuit failure of PCBA due to the fracture of copper layer of hole wall is introduced. The samples are analyzed by means of metallographic section, SEM and TMA, and the causes of the failure are found. Through the research, it is found that the corrosion of the plated-through hole of the failure PCBA makes the hole thinner or crack. At the same time,the thermal expansion coefficient of Z axis of PCB is higher than the upper limit of specification,which further aggravates the fracture phenomenon of copper layer of hole wall.