Various Defect Mechanism Analysis for Optimization of Vacuum Fluxless Solder Reflow Performance Using 10 μm or Below Microbumps

With advanced packaging technology's development, leading foundries and OSATs are pushing the bumping process to a finer pitch of less than 15um. The advantage of doing that leverages existing Cu pillar microbump structures, while providing opportunities to equipment suppliers to provide technical solutions. In this paper, an effort was made to develop an experimental characterization method to differentiate reflow performance for advanced bumping and solder joint processes. This study focused on micro bumps within a pitch of 10μm and below, and it correlated reflow performance with defect mapping to formic acid reflow process parameters.