Void of leaded and lead-free solder paste on different PCB surface pad finish under various reflow conditions - further investigation on void of SnInAgBi lead-free soldering paste

Elimination of lead in electronic industry has become a reality and is expected to be universal in the next 1-2 years. SnAgCu series of alloy has been widely accepted as the recommended lead-free alloy in consumer electronics. However, due to its high reflow peak, which may destroy the sensitive components, various kinds of alloys are also introduced to the market. Our previous studies on Sn88In8Ag3.5Bi0.5 (SInAB) alloy has show the possibility of implementing this alloy into solder paste, which provides good solderability and reliability. In this report, further investigation on void of this paste in different reflow atmosphere (Air, N₂, vapor) has been carried out. Under different reflow conditions, a comparison between SAC and SInAB pastes has been done. The eutectic Sn63Pb37(SnPb) solder paste was included as the baseline. The results show that under certain reflow condition, paste contains SInAB alloy can achieve better void, which compatible to that of the paste contains SnPb alloy. Several main factors, which cause void are discussed and explained as well