Investigation of Metallographic Etchants Selectivity for Tin Solder Alloys

The main aim of this work was to determine and summarize the applicability of etching solutions for the preparation of examined solder joint samples after metallographic cross-sections. Each etchant has different etching rate for every element and compound thereby highlighting various information about the solder joint inner structure. These findings were subsequently used to recommend the choice of a given solution for certain information about the properties of the inner structure of the SAC305 solder joint. Four types of solutions with strong acid were used. The results showed that all etchants could be used for interfacial intermetallic compounds. However, only Etchant A and Etchant D were the most suitable for comprehensive examination of the SAC305 solder ball inner structure.