Optimization of soldering experiments for power devices interconnection and packaging

In this study, soldering experiments with low aspect ratio have been investigated. This constraint is setup for process reasons such as following the soldering by the Transient Liquid Phase Bonding process. Two bump sizes have been used for the soldering experiments: 1mm and 90μm. The target height of deposited Cu pillars is 20μm and the thickness of deposited Sn-2wt%Ag alloy varies from 5 to 30μm. Firstly, the deposited thickness and topology of Cu and SnAg alloy has been evaluated for both bump sizes. Then, the soldering experimental results for different SnAg thicknesses are presented and discussed based on the initial conditions and the deposition parameters. Finally, an additional step of reflow process is suggested and investigated for obtaining low porosity joints after the soldering experiments.