The correlation between the mechanical and electrochemical properties of solder joints

The mechanical properties of a solder joint is partially determined by the microstructure of the solder. This microstructure is formed during the soldering process and it highly depends on the technological parameters. We have introduced a new selective electrochemical sample preparation method in which the tin phases can be removed from a cross-section of a solder joint, while the intermetallic phases stay intact. For the quantitative characterization of the revealed intermetallic microstructure we also introduced a novel method. We compare the electrochemical impedance spectrum of the polished surface of the cross-sectioned sample to the spectrum measured after the selective material removal. The peak shear force values of components soldered with different cooling rates are compared to a composed arbitrary unit which is proportional to the total surface of the intermetallic compounds in the solder bulk.