Advanced alloy for lead‐free solder balls

A new alloy for lead‐free solder balls is introduced combining the advantages of a smooth surface after production and a uniform reflectivity after the ball attach process. This property significantly simplifies the inspection process during ball grid array (BGA) processing. By adding small amounts of Indium and Lanthanum to the ternary eutectic SnAgCu‐alloy a pentary, virtually eutectic composition with a melting point of 214°C is realised. It is shown that the processability in terms of reflow behaviour and the shear strength of BGA spheres made of this alloy is comparable to or better than that of ternary SnAgCu‐balls.