Palladium enhanced dry soldering process

The authors report an enhancement technique for promoting a dry soldering process without the use of the wet chemical flux. A thin layer of Pd (about 1000 AA) on the surface of the areas to be soldered was found to be effective in promoting the solder wetting and joining. The effectiveness of the PD coating was studied at temperatures from 215 to 350 degrees C in hydrogen and forming gas ambient. Both a low-temperature solder (eutectic PbSn) and a high-temperature solder (Pb5Sn) were tested. The structure and the effectiveness of palladium coatings prepared by the immersion plating and the evaporation were compared. Applications would be in the SMT (surface mounting technology), pin brazing, pin soldering, and other soldering/bonding operations.<
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