Conventional methods of evaluating ionic migration have been confined to evaluating electrical characteristics such as changes in insulation resistance. However, this type of evaluation cannot provide the initiation process by ionic migration. This research has focused on the AC impedance method to study the process of ionic migration for various types of lead-free solder. As a result, the migration generation process is composed of the charge transfer process and the mass transfer process. Moreover, two semicircles in the charge transfer process appeared before the short circuiting between electrodes. The migration generation can be forecast by monitoring the charge transfer resistance of two semicircles.
