Effect of Different Aging Temperatures on Interfacial Reaction between SAC305 and ENEPIG Surface Finish

In electronic packaging industry, they are now driven technology to green product by
replacing leaded-solder with lead-free solder in order to fulfill the European Restriction of Hazardous
Substance (RoHS) compliance. Thus, Sn-Ag-Cu lead-free solder family is one of candidates can
fulfill this requirement. This study investigates the interfacial reactions during reflow soldering and
isothermal aging between Sn-3.0Ag-0.5Cu (SAC305) and electroless nickel/ immersion
palladium/immersion gold (ENEPIG). Reliability of solder joint is also examined by performing solid
state isothermal aging at 125˚C and 150˚C for up to 2000 hours. The results revealed that after reflow
soldering, (Cu, Ni)6Sn5 IMC is formed between solder and substrate while after aging treatment
another IMC was found between (Cu, Ni)6Sn5 and substrate known as (Ni, Cu)3Sn4. Aging time and
temperature of solder joints results in an increase of IMC’s thickness and changes their morphologies
to become more spherical, dense and with larger grain size. In addition, the results also revealed that
the thickness of intermetallics formed is proportional to the aging duration and temperature.