EFFECT OF VACUUM REFLOW ON SOLDER JOINT VOIDING IN BUMPED COMPONENTS

摘要

Voids affect the thermal characteristics and mechanical properties of a solder joint, thereby affecting the reliability of the solder interconnect. The automotive sector in particular is requiring the mitigation of solder voids in various electronic control modules to the minimum possible level. Earlier research efforts performed to decrease voids involved varying the reflow profile, paste deposit, paste alloy composition, stencil aperture, and thickness. Due to the various advantages they offer, the use of Ball Grid Array packages is common across all industry sectors. They are also prone to process voiding issues. This study was performed to determine if vacuum assisted reflow process can help alleviate the voids in area array solder joints. Test parameters in this study largely focused on vacuum pressure level and vacuum dwell time. Experiments were also performed on a bench top oven to investigate the behavior of voids under vacuum. Tests were carried out at various pressure levels with samples solidified under vacuum to lock in the voids, which wouldn't be possible in an in-line convection vacuum reflow oven. Test boards were also assembled on convection reflow oven using a linear ramp to peak reflow profile to provide comparative analysis.