锡-铅共晶焊料与镀金层焊点的失效机理研究

Solder Joints Failure Mechanisms Research of Sn-Pb Eutectic Soldering on Gold Plated Surface

总结了某电子产品故障的失效分析工作。针对锡-铅共晶焊料在表面镀金的印制电路板焊盘上焊接电子元器件或导线的焊点,研究了印制板金镀层厚度、焊料中金成分含量及焊接后时效温度和时间对焊点抗拉强度的影响,并对焊点产生金脆失效的机理进行了分析。研究结果表明,在锡-铅共晶焊料中金的含量达到10%后,焊料的强度会急剧减弱;焊接完成后,在一定的贮存条件下,会在界面生成弱化层,使焊点与焊盘结合强度减小,是导致金脆失效的主要原因。

This is a summary of a failure analysis of an electronic product. For the solder joints,at which the component leads or the wires are soldered with Sn-Ph eutectic solder to gold plated pad of printed circuit board, the factors that effect the pulling strength of the solder joints are investi gated, such as thickness of plated gold layer, gold content in the solder and storage temperature and time after soldering, and the failure mechanisms of the gold embrittlement of the solder joints is investigated. The results reveal that the pulling strength of the solder joints dramatically de crease only when the gold content in the solder is up to 10% or more. The main cause of the gold embrittlement failure is the forming of the weak layer between the solder and the pad which is formed after soldering when the solder joints are stored in some condition and makes the connec tion strength between the solder joints and the pad really small.