Tombstoning Investigation of Ultra-small Chip Passive Components on eMMC Products

This work investigated the countermeasures to high tombstone failures in embedded multimedia card (eMMC) products using 0201 multilayer ceramic capacitors (MLCC) from the perspectives of reflow profiles, MLCC physical dimensions, and pad designs. Factors like prolonged preheating time in the reflow process, long terminal length of MLCCs, and a different land pattern can all help improve the high defect rate to zero reject. As the land pattern was observed as the essential factor, a novel pad design was introduced in this latter part of the work for future tombstone prevention.