Interfacial Reaction Between 95Pb-5Sn Solder Bump and 37Pb-63Sn Presolder in Flip-Chip Solder Joints

摘要

Interdiffusion and interfacial reaction of 95Pb-5Sn solder bumps and 37Pb-63Sn presolder in flip-chip solder joints during high-temperature storage were studied. Reaction temperatures included 100 deg C, 130 deg C, 150 deg C, and 175 deg C. It was found that Cu_(6)Sn_(5) and Cu_(3)Sn formed on the board side and (Ni,Cu)_(3)Sn_(4) formed on the chip side after 100 h of aging. After 2000 h of aging at 175 deg C, the Ni under-bump metallization (UBM) was exhausted. This caused the (Ni,Cu)_(3)Sn_(4) layer at the chip-side interface to be gradually converted into (Cu_(0.6)Ni_(0.4))_(6)Sn_(5). It was also found that the consumption of the Ni UBM was faster than the case where eutectic Sn-Pb solder was used for the entire joint. Nevertheless, the consumption of the Cu on the substrate side was slower than the case where pure eutectic Sn-Pb solder was used for the entire joint.