PCBA失效中的电化学迁移与腐蚀研究
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摘要
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.
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.
引文
[1]罗道军,贺光辉,邹雅冰.电子组装工艺可靠性技术与案例研究[M].北京:电子工业出版社, 2015:271-287.
[2]徐冬霞,雷永平,张冰冰,等.无VOC免清洗助焊剂焊后残留物的可靠性评价[J].电子元件与材料,2008, 27(3):68-71.
[3]孙广辉.助焊剂残留对PCB的影响[J].印制电路信息,2011(S1):209-213.
[4] VERDINGOVAS V, JELLESEN M S, AMBAT R. Influence of sodium chloride and weak organic acids(flux residues)on electrochemical migration of tin on surface mount chip components[J]. British corrosion Journal, 2013, 48(6):426-435.
[5] RATHINAVELU U, JELLESEN M S, AMBAT R. Effect of solder flux residue on the performance of silicon conformal coatings on printed circuit board assemblies[J]. British corrosion Journal, 2013, 48(6):436-444.
[6]钱雨鑫,钟鸣,袁保玉,等.压力变送器PCB腐蚀失效分析案例研究[J].电子产品可靠性与环境试验,2017, 35(2):19-23.
[7]王新娟,饶丹丹. PCBA失效原因分析[J].电子产品可靠性与环境试验, 2017, 35(3):7-13.
[8]楼倩,李晓倩.铅离子迁移导致PCBA失效的机理分析[J].电子产品可靠性与环境试验, 2017, 35(6):16-18.
[2]徐冬霞,雷永平,张冰冰,等.无VOC免清洗助焊剂焊后残留物的可靠性评价[J].电子元件与材料,2008, 27(3):68-71.
[3]孙广辉.助焊剂残留对PCB的影响[J].印制电路信息,2011(S1):209-213.
[4] VERDINGOVAS V, JELLESEN M S, AMBAT R. Influence of sodium chloride and weak organic acids(flux residues)on electrochemical migration of tin on surface mount chip components[J]. British corrosion Journal, 2013, 48(6):426-435.
[5] RATHINAVELU U, JELLESEN M S, AMBAT R. Effect of solder flux residue on the performance of silicon conformal coatings on printed circuit board assemblies[J]. British corrosion Journal, 2013, 48(6):436-444.
[6]钱雨鑫,钟鸣,袁保玉,等.压力变送器PCB腐蚀失效分析案例研究[J].电子产品可靠性与环境试验,2017, 35(2):19-23.
[7]王新娟,饶丹丹. PCBA失效原因分析[J].电子产品可靠性与环境试验, 2017, 35(3):7-13.
[8]楼倩,李晓倩.铅离子迁移导致PCBA失效的机理分析[J].电子产品可靠性与环境试验, 2017, 35(6):16-18.