Pd-PPFプロセスに用いられるPdめっき液への新規添加剤の効果

抄録

Conventionally, IC packaging uses spot-silver plating, die-bonding, wire-bonding and resin molding on copper lead frame materials, along with solder plating of the lead parts to be soldered onto a printed board. This conventional method, however, has some serious problems that need to be addressed, such as Pb in the solder plating. Consequently, Pd-PPF has received attention for both environmental and technical reasons and has been practically applied in lead frame packages. Environmentally, it is Pb-free and the cyan consumption is reduced by the elimination of silver plating, which consumes large amounts of cyan. A number of technical benefits also can be achieved, in addition to the environmental improvement. Currently, it is important to make the Pd-PPF plating thinner, both to improve its properties and to reduce costs in the face of soaring precious metal prices. Thus, a crystalline adjuster was added to a palladium plating solution with a view to improving film quality and solder wettability was examined in order to improve the high-temperature resistance of palladium plated film. With the new additive, solder wettability was dramatically improved, and good solder wettability was obtained even from a thinner Pd-film. Moreover, other properties proved to be equivalent to or better than those achieved with the conventional process.