微量元素锗对无铅焊料的影响及实际应用研究

Influence of trace element ge on lead-free solder and practical application

近年来,热风整平无铅焊料作为一种无铅化的表面处理方式,因其低廉的加工成本及较好的表面润湿性而受到很多PCB生产厂家的青睐。同时,无铅焊料在应用过程中也暴露了诸多的问题,比如无热风整平无铅焊料产品在下游客户端做回流焊接工艺时,经过一两次的高温回流后,锡面会出现一定程度的发黄现象。本文主要针对此类发黄情况,深入研究探讨了微量元素Ge对无铅焊料的影响以及对发黄改善的机理,通过理论与实践相结合,研究并得出了在热风整平无铅焊料过程中,Ge(锗)浓度的变化规律及其合理的控制方法、以及Ge浓度对无铅焊料性能的具体影响情况。

In recent years, HASL as a surface treatment of lead-free, favored by many PCB manufacturers because of its low cost and good surface wettability. At the same time, in the application process , lead-free solder also exposed many problems, such as lead-free HASL products in the lower reaches of the client to do the relfow soldering process, after 1~2 times of high temperature relfow, tin surface will become yellow in certain degree. This paper mainly aims at this kind of yellow, in-depth study of the effects of Ge element on the regularity of lead-free HASL products become yellow after relfow, through the combination of theory and practice, research in lead-free HASL process, the changes of Ge content and its reasonable control methods, as well as the inlfuence of Ge content on the lead-free HASL products become yellow after relfow.