Mechanical Characterization of Sn-Ag-Cu Solder With Gold Addition Under Tensile Loading

Abstract

Lead (Pb)-free implementation for electronic assembly has created a stir in electronic packaging industry during the last five years since Europe and eastern Asian countries decided to restrict the use of lead in electronic packages. Lead (Pb) content in solders is mandated to be less than 0.2 wt % (USA) and 0.1 wt % (EU). Sn-Ag-Cu (Tin, Silver, and Copper) solder is selected as one of the options to replace tin-lead solders. This solder is a preferred option as it comes closest to tin-lead solder in terms of parameters such as melting temperature (∼217°C), wettability, cost, availability, and reliability. Various agencies like NEMI, JEIDA and IDEALS recommend Tin-rich Lead (Pb) free solders as the possible alternatives to Pb-Sn solder [1]. Addition of elements like Au, Co, Fe, Ni, etc in small quantities can affect the properties of Sn-Ag-Cu solder. It has been reported that the addition of Au in small quantities improves the properties of lead-free solder. Au has very high reactivity with Sn and also improves the wettability of solder. Au forms a β-phase with Sn at the interface. This phase is considered beneficial in terms of improving fatigue life and fracture toughness as this β phase acts as a crack arrester thereby improving its strength Addition of Au also reduces the liquidus temperature to 204 °C. In this paper we tested and compared the strength of pure Sn-Ag-Cu solder and Sn-Ag-Cu solder with Au addition and it was concluded that the strength of material increases from 50 MPa to 70 MPa under tensile loading.