Relation between Impurities (Au Plating) and Joints Quality

Influence of Plating on Micro Joints Quality

Abstract

Parallel gap resistance welding of Ag plated 0.18 mm diameter oxygen free copper wires to Au+ Ni plated of Printed circuit boards (P/B) was investigated (concerning Au plating). The results are summarized as follows.
(1) Au plating bath for Good Micro Welding is composed Cobaltion 0.35-3 gf/l [5.9-51 mol/m³] and Nickelion 0.02-0.5 gf/l [0.34-8.5 mol/m³], after Au plate it's composition of Co 0.2-3% and Ni 0.4-2% except Au :
(2) Cobalt content and Nickel content beyond the allowable limit are Bad Welding for Au plating, they cause Blow hole in the weld fillet and decrease weld strength.