Influence of vapor phase soldering fluid Galden on wetting forces (tombstone effect)

Vapour phase soldering brings besides many advantages for reliability in electronic production an increased incidence of tombstoning errors. The imbalance of wetting forces has a decisive effect on the tombstoning phenomena, and the changes in wetting forces during the vapour phase soldering are therefore analyzed and evaluated. Two types of solders (leaded Sn63Pb and lead-free SAC387 alloy) and two types of heat transfer fluids (Galden LS 230 and Galden HS 240) were used. The use of soldering fluids changes the surface tension equilibrium vectors for both used solders and changes the measured wetting force by up to 20%. The measurement was performed by wetting balance method using non-wetting sample.