不同钎剂对Sn-Zn系无铅钎料润湿特性的影响

Effects of different fluxes on the characteristics of Sn-Zn solders

关键词:  无铅钎料  Sn-Zn  钎剂  润湿性

Key words:  lead-free solder  Sn-Zn  flux  wettability

摘要:

采用润湿平衡法研究了在ZnCl₂-NH₄Cl、中等活性松香(RMA)和免清洗三种不同钎剂作用下,Sn-Zn无铅钎料在Cu基板上的润湿特点.结果表明,使用ZnCl₂-NH₄Cl钎剂时,Sn-Zn钎料具有良好的润湿性能;研究了不同钎剂下,Sn-9Zn钎料在Cu基板上的铺展情况,并分析比较了焊点界面金属间化合物层的特征.Sn-Zn钎料与Cu基板界面形成的金属间化合物在靠近Cu基板一侧较为平坦,而在钎料一侧呈扇贝状,而且,不同钎剂能影响钎料在Cu基板上的润湿、铺展性能,界面金属间化合物特征及焊点外观;Sn-Zn钎料表面存在大量ZnO,去除钎料表面ZnO是开发针对Sn-Zn系无铅钎料专用钎剂的关键。

Abstract:

The wetting characteristics of Sn-Zn solders with three different types of flux were researched by wetting balance method. Results indicated that Sn-Zn solders exhibited excellent wettability using ZnCl₂-NH₄Cl flux.Additionally, the spreading of Sn-9Zn solder on Cu substrate with different types of flux was investigated, and the characteristics of the intermetallic compounds (IMC) between the solder and substrate were also analyzed and compared, results showed that a flat IMC layer was present adjacent to the Cu substrate while a scallop IMC layer was close to the solder.Moreover, the characteristics of IMC and the appearances of soldered joints varied by using different fluxes.Plenty of ZnO exists on the surface of Sn-Zn solders, thus removing the ZnO is critical for the flux of Sn-Zn solders.