Studies have been conducted to show the effects of Pd film thickness on the solder ball jet nozzle joint reliability. The subject of the survey was electroless Ni/Pd/Au plating on an Sn-3.0Ag-0.5Cu (SAC305) solder ball jet nozzle joint. The study used a solder ball jet nozzle shear test.
After multiple reflow cycles, the Pd film thickness between 0.05-0.02 microns was the optimum for solder joint reliability. Studies have also shown that solder ball jet nozzle joints are more reliable when using 0.02 micron thick electrodes.
This result is even better than that obtained using electroless Ni/ Au plating.
The study also shows that the shape and thickness of the intermetallic compounds (IMCs) determine a solder ball jet nozzle’s reliability. In particular, the degree of adhesion at the dendrite layer of the IMCs/solder interface immensely influenced a solder ball jet nozzle’s reliability.
It was also shown that (Cu, Ni, Pd)6Sn5 IMCs containing minute Pd yield excellent solder ball jet nozzle joint reliability mainly because Pd inhibited the growth of IMC.