Electroless Nickel / Electroless Palladium (ENEP) with pure Pd for Soldering

With regard to solder joint reliability a Cold Ball Pull Test comparison was conducted between ENIG and ENEP with pure palladium.

The ENEP surface finish shows consistently good pull strength results and a significant lower number of fractures in the intermetallic compound compared to ENIG.

Wetting Performance Comparison

Furthermore with ENEP the occurrence of "Black Pad" and "Brittle Fracture" is practically ruled out as displacement reactions as with immersion gold are not present.

For the ENEP Surface Finish Atotech uses the pure Pd deposition. Pure Palladium shows significant advantages over Palladium-Phosphorus alloys when it comes to solder wetting performance and copper wire bonding.

In terms of solder wetting it outperforms immersion silver (I-Ag )and OSP. After one reflow cycle the wetting angle is lower than with immersion tin. In the direct comparison between the wetting performance of pure Pd and Pd-P, the pure palladium performs clearly better.