Study of Joule heating effects in lead-free solder joints under Electromigration

Basic understanding of heating conduction in lead-free solder joints due to the Joule heating effect was carried out by using the infrared (IR) microscopy. In order to interpret the corresponding mechanism and provide a better understanding to Electromigration (EM) studies, a newly developed ID solder joint with same cross-sectional area in solder alloy and Cu electrodes was employed in our thermal imaging analysis. Both eutectic SnBi and SnAgCu solder alloy were used to fabricate the joints due to their distinct electrical resistivity and thermal conductivity. Various electrical current inputs combined with joints' thickness of 500 μm were investigated. Accordingly, transient and steady-state heat conduction were identified and compared with different experimental conditions.