Influence of Mn on wettability and microstructure of low-silver lead-free solders

The influence of Mn on wettability and microstructure of low-silver solders was investigated.Mn degrades the wettability of low-silver solders,while the wettability of the Mn doping solders does not change with Mn content in a linear way.As a result of Mn doping,the cellular/dendritic B-Sn and the eutectic phase are refined.It indicates that Mn promotes the spontaneous and heterogeneous nucleation process of the solder alloys.The growth of intermetallic compound on the joint interface during soldering is also restrained.Aging experiment shows that Mn suppresses the growth of Cu₃Sn and Cu₆Sn₅ layers at the joint interface.