Electrochemical Migration of Micro-alloyed Low Ag Solders in NaCl Solution

Abstract

The reliability investigation of the lead-free solders is still a current issue. In this paper, Electrochemical Migration (ECM) behavior of novel lead-free micro-alloyed low Ag content solders were investigated by water drop test in NaCl solution. The results were compared to commonly used lead-free and lead bearing solder alloys. It was found that some micro-alloyed solders can have similar low ECM susceptibility than lead bearing ones. X-ray photoelectron spectroscopy was also carried out to find the root cause of different ECM behaviour of micro-alloyed solders. The results of water drop test and x-ray photoelectron spectroscopy were in good agreement relating electrochemical migration susceptibility. Since SAC0807 solder alloy has shown higher corrosion rate than SAC0307 and has also higher ability for ECM as well. It is concluded, that some lead-free micro-alloyed low Ag content solder alloy (e.g.: SAC0807) could have a high reliability risk in the electronic devices during operation.