PCBA失效中的电化学迁移与腐蚀研究

Research on the Corrosion and Electrochemical Migration Failure of PCBA

从实际的案例出发,分析了无铅制程中助焊剂的酸性残留物及卤素离子对组装可靠性带来的潜在风险:一方面,残留离子会直接腐蚀PCBA组件中的焊点、 PCB焊盘或元器件引脚;另一方面,残留离子在水汽、电场的作用下会发生电化学反应,造成腐蚀及电化学迁移,导致开路或短路失效。在PCB走向高密化的条件下,腐蚀和电迁移的风险提高,相应地对PCBA组件清洁状况的要求和管控也会变得更加严格。

Based on practical cases,the potential risks of acid residues of flux and halogen ions for assembly reliability in lead-free process are introduced.On the one hand,residual ions will directly corrode solder joints,PCB pads or device pins in PCBA assemblies.On the other hand,the electrochemical reaction of the residual ions occurs under the action of water vapor and electric field,which will result in corrosion and electrochemical migration and lead to open circuit or short circuit failure.Under the condition of high density of PCB,the risk of corrosion and electromigration increases,and the requirement and control of cleaning condition of PCBA assemblies become more strict.