Die attach adhesion on leadframes treated with antioxidants

Antioxidant treatment of leadframes can reduce the initial die attach adhesion if the deposit creates an excess unbonded layer. The benzotriazole class of antioxidants can reduce the die attach adhesion over time by undergoing reactions that disrupt the leadframe/adhesive interface. The surface analysis techniques AES and ToF-SIMS were used to characterize the difference between good and bad leadframes. Other leadframe treatments were evaluated which have no effect on adhesion. These include the hindered phenol, hydrazine and thioester antioxidant compounds, as well as the inorganic A2 treatment. Cleaning methods for leadframes are proposed which are compatible with electronic packaging assembly lines.