> IBIS Models Pb-Free Solder Joint Evaluation

Abstract- Removal of lead (Pb) from finished integrated circuit (IC) packages and the assembly processes used to make them is an ongoing effort by many manufacturers. The removal of Pb in consumer paint products and gasoline has already been undertaken. Many evaluations are underway now in the electronics manufacturing industry to find a suitable substitute for Sn/Pb solder. The goal of this study was to evaluate a totally Pb-free solder joint formed by using TI 4-layer Ni/Pd finish IC components, CASTIN Pb-free solder paste, and ENTEK ® PLUS Organic Solderability Preservative (OSP) as the PWB surface finish. Mechanical tests performed included contact angle measurements and lead pull. Temperature cycle testing was performed to evaluate the package integrity after cycling through temperature extremes. The wetting balance test was used as a tool to determine the solder wetting time for the individual IC components. The results show that the contact angles do increase with Ni/Pd and Ni/Pd/Au finishes. However, Ni/Pd and Ni/Pd/Au finishes achieve equivalent or better lead pull and temperature cycle testing results versus Sn/Pb. This indicates that any difference i