Nowadays, ENEPIG has a great potential to replace the traditional ENIG, because it can solve the ‘‘black pad’’. Herein, we investigated two different surface finishes PCB for ENEPIG technology, and the interfacial reaction between solders and PCB should be concerned.
In this study, sample A and sample B boards were surface finished by different conditions. We considered that the effects of phosphorous contents for each Palladium and Nickel layer may influence the morphology of them and the atom diffusion path.
During reflow process, we observed that solder joints reacted with two conditions ENEPIG surface-finished PCBs had different IMCs growth evolution. For sample B board, it has some voids occurred and Ni3P, (Cu, Ni)6Sn5 IMC grown. After the High-Speed Ball Shear Test, sample B has the higher failure possibility than sample A. Therefore, we believe that the contents of phosphorous for each layer play an important role on interfacial reaction.