A study on solder-joints fall-off failure of electroless nickel/immersion gold pad

Solder joints which had fell from the electroless nickel/immersion gold (ENIG) pads during the assembly process after reflow were studied in this paper. In order to probe the root cause of the failure in solder joints, cross section and Scanning Electron Microscopy/Energy Dispersive X-ray (SEM&EDS) techniques were applied. In addition, solderability test was also put forward to verify the failure phenomenon. Results showed that, because of the serious corrosion of Ni layer on pad, the interface intermetallic compound (IMC) layer of test samples formed badly, which resulted in the insufficient mechanical strength of solder joints and caused crack or fell off. The Ni-corrosion resulted from poor ENIG process.