(大连理工大学 材料工程系， 大连 116024)
摘 要: 研究了(Sn-9Zn)-xCu无铅钎料的微观组织、润湿性能和力学性能。 Cu的加入使得Sn-9Zn钎料中针状富Zn相逐渐转变为Cu-Zn化合物， 当Cu含量为8%时， Cu6Sn5相生成。 Sn-Zn-Cu合金熔点随着Cu含量增加而升高， 同时润湿性随Cu的加入得到显著改善。 使用中性活性松香钎剂，钎料与Cu箔钎焊时的润湿角显著减小。 Sn-9Zn的润湿角为120°， 而(Sn-9Zn)-10Cu的润湿角为54°。 这是由于Cu的加入降低了Zn的活性， 减少了Zn在钎料表面氧化， 降低了液态钎料表面张力， 使得钎料能获得较好的润湿性。合金在2%Cu时获得较高的强度， 随着Cu含量的增加， Cu-Zn化合物相对增多， 抗拉强度有所下降；而合金的塑性随着Cu的加入迅速下降。
关键字: 无铅钎料；Sn-Zn-Cu；微观组织；润湿性；抗拉强度
（ Department of Materials Engineering， Dalian University of Technology， Dalian 116024， China）
Abstract: The microstructures， wettability and mechanical properties of (Sn-9Zn)-xCu lead free solders were investigated. The addition of Cu element leads the needle Zn rich phase to transform into Cu-Zn compounds and when Cu is 8%， Cu6Sn5 phase emerges. The melting point increases with increasing Cu content; while the wetting properties is improved dramatically. When the solder reflows on Cu substrate， the wetting angle decreases greatly using mildly active rosin (RMA) flux. The wetting angle of Sn-9Zn is 120°; while that of (Sn-9Zn)-10Cu is 54°. The improvement on wettability is due to the addition of Cu which decreases the activity of Zn and refrains the oxidation of Zn atoms at the surface of liquid solder. Better wetting behavior is gotten because of the lower surface tension of liquid solder. And the solders get the higher tensile strength when Cu content is 2%. With more Cu addition， more Cu-Zn compounds formation deteriorates the solder strength and the ductility decreases greatly with Cu addition.
Key words: lead free solder; Sn-Zn-Cu; microstructure; wettability; tensile strength
