Defects in optoelectronic materials due to phosphorus-containing underlayer

We report the new observation that the crack formation mechanism in a laser-welded Au-coated optoelectronic material is due to the existence of P-containing underlayer and is not due to the thickness of the Au plating layer. Therefore, to solve the problem of crack formation in laser-welded Au-coated optoelectronic materials, it is strongly recommended that a Ni underlayer with P-free electroplating instead of P-containing electroless plating should be used prior to plating Au on optoelectronic materials.