Reliability testing of SnAgCu solder surface mount assembly

Accelerated reliability tests have been performed on a number of lead-free SMT soldering assembly configurations and have shown that lead-free reflow soldering is a viable option compared to conventional lead based reflow soldering. For the selected ternary eutectic solder alloy SnAg3.5Cu0.7 higher processing temperatures might require some component re-specifications, but other than that no major modifications seem necessary. In general, quite similar reliability results were obtained as found for the near eutectic lead based solders. Dependent on board and component metallisations and use environment the reliability of the lead-free solders could perform better or worse than the lead based solders. Temperature dependent aspects such as solderability and mechanical behaviour of the lead-free assemblies could play a role in this.