材料期刊网

尽管无铅电镀已经在电子工业中得到了广泛的应用,但是目前无铅电镀的实施仍然面临着很大的挑战.概述了无铅电镀技术的现状,重点介绍了现在流行的几种无铅镀层及性能.无铅镀层目前主要有纯锡和合金体系.合金元素的加入与铅的加入起同样作用,即抑制了锡晶须的发生.尽管有许多元素都能起到这种作用,但目前在电子电镀工业中所采用的无铅合金体系主要是Sn-Ag、Sn-Cu和Sn-Bi.无铅电镀的实施过程正好与电子工业中封装的高密度化发展同时进行,因此许多问题不断出现,最突出的问题是锡晶须问题,此外还有电迁移、焊点空洞、界面反应、回流温度及成本等问题.总结了无铅电镀存在的主要问题,同时展望了无铅电镀未来的发展前景.现在尚没有一种能够完全取代锡铅电镀且几乎在任何场合都能通用的无铅电镀材料,所以现在实施无铅电镀需要事先进行评估和选择,根据工厂自身所用电子器件的不同使用条件、成本及其电镀产品的应用领域,选用不同的无铅电镀类型.未来需要在无铅电镀材料、试验及工艺技术方面持续进行研究.

Although lead-free electroplating has been widely used in electronic industry, the application of lead-free elec-troplating is still faced with some challenges. Current situation in the field of lead-free electroplating was overviewed, with an emphasis of several popular Sn and Sn alloy lead-free platings and corresponding properties. The lead-free platings currently consisted of pure Sn and Sn alloy systems. The addition of alloying elements had the same effect as that of Pb, i.e., inhibiting presence of tin whiskers. Although various elements had such effects, the lead-free alloy systems now used in electronics elec-troplating were mainly Sn-Ag, Sn-Cu and Sn-Bi. The application process of lead-free electroplating happened to coincide with densification development of packaging in electronic industry. Thus, many problems associated with lead-free electroplating emerged continuously. A prominent problem was tin whisker. Besides, there were electromigration, void formation at solder joints, interfacial reactions, reflow temperature and cost. Key problems regarding lead-free electroplating were summarized and future development prospect of lead-free electroplating technology were forecasted. There was still no universal lead-free elec-troplating material that could take the role of Sn-Pb. Therefore, the choice of a lead-free electroplating must be made by manu-facturers upon service conditions, cost and application field of electroplate products. In the future, further study shall be per-formed in respect of lead-free electroplating material, test and technology.