摘要:
在钎焊和时效条件下,研究了Sn-3.5Ag无铅钎料中添加0.2%的Zn元素后对钎料/铜界面组织形貌的影响.结果表明,钎焊条件下,将0.2%的Zn元素加入到Sn-3.5Ag钎料中对Cu-Sn间的金属间化合物及其扇贝形形状不产生影响.时效处理后,0.2%Zn元素的加入对界面IMC层的厚度、组成及形态都有影响.在Sn-3.5Ag-0.2Zn/Cu接头中,IMC层的长大得到了明显的抑制,并且与Sn-3.5Ag/Cu接头相比,IMCCu3Sn层的形成完全得到了抑制.在无锌的接头中,还观察到了IMC形态由扇贝形向层状转变,而在含锌的接头中,扇贝形组织在时效过程中没有发生变化.微量Zn元素的加入对IMC层的增长和组织形态的改变取决于IMC层内元素之间的相互扩散.
Abstract:
0.2% Zn element was added into Sn-3.5Ag Pb-free solder, and the interfacial microstructure at solder/Cu has been studied under as-soldered and as-aged condition. During soldering, the Cu-Sn intermetallic and its scallop-type structure are not changed by the small amount addition of Zn. However, in the Zn-contained solder joint, the scallops are found to be smaller but more compared with Zn-free solder joint. After thermal aging, the growth thickness, compositions and morphology of the IMCs at the interface are affected by the 0.2% Zn addition. In the Sn-3.5Ag-0.2Zn/Cu joints, the growth of IMC layer is evidently retarded and the Cu3Sn IMC layer is completely inhibited. Furthermore, compared with the change from scallop-type to flaky-type morphology observed in Zn-free solder joints, scalloptype structure is still the predominant morphology in Zn-contained solder joints during solid-state aging. The inhibitation of small amount of Zn addition on the IMC growth and change of morphology is attributed to the retarding effect of interdiffusion coefficient of the IMCs.
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