锡锌钎料的腐蚀行为

CORROSION BEHAVIOR OF TIN-ZINC BASED ALLOY SOLDER

在传统的SnZn共晶钎料中加入微量稀土元素获得含稀土的SnZnRE钎料 .采用失重法、扫描电镜腐蚀形貌观察及电化学分析技术对钎料在不同环境下的腐蚀行为进行分析 ,研究SnZn系钎料的抗腐蚀性能 ,并与SnPb钎料进行了比较 .

Environmental concerns drive market to find environment-friendly solder to replace the lead-bearing solder for microelectronic joining.In this paper,the corrosion behavior of Sn-37Pb and SnZn based lead-free solders(including Sn-9Zn,Sn-9Zn-0.25RE) has been investigated.Mass loss evaluation,observation of corrosion morphology by scanning electron microscope(SEM) and electrochemical testing has been conducted on.The corrosion experiments were undertaken in tap water(room temperature),tap water(70℃),in air with high humidity at high temperature(70℃) and in 3% NaCl solution at room temperature separately.The results reveal that:SnPb solder was corroded uniformly under the all corrosion conditions mentioned in the paper.The corrosion products are likely to peeling off from the matrix for their weak joining.SnZn based solder is characteristics with chosen corrosion of zinc for the low standard potential of zinc,resulting in pitting of the alloy.The corrosion mechanism of this zinc-bearing solder is a mixing of pitting and entire corrosion,leading to fast corrosion rate.Minimal rare-earth elements in SnZnRE solder improve the compactness of the microstructure of SnZn alloy and its corrosion products,resulting in the slow corrosion rate and stronger corrosion-resistance of SnZnRE solder.Based on the above experiments,Sn-Zn based solder will be expected to replace the SnPb solder when its competitive properties meet the required touchstones.