Effect of Ag on oxidation of Cu-base leadframe

It was found that trace Ag on surface has great effect on the oxidation failure of Cu-base lead frame. Trace Ag on the surface increases its peeling resistance in dry condition, while decreases that under hygrothermal aging treatment. The oxide thickness, morphology and compositions were examined to understand the key factor of peeling of oxide film. It becomes evident that Ag has ability to block the diffusion of copper atoms, and so hold back the oxidation of copper. But adhesive strength between copper and oxide layer has little relation with oxide thickness but more important influence comes from internal compressive stress which has great relations with initial structure of the copper lead frame.