Studies of polyimide/copper interface and its improvement by a two-component primer

The inhibition of the imidization of polyamic acid, a precursor of polyimide, in the presence of Cu, was confirmed by the incorporation of Cu²⁺ ions in polyamic acid films. It was found that the imidization reaction was incomplete below 300°C but decomposition took place when heating above 300°C. Pretreating the Cu surface with a two-component primer solution containing polybenzimidazole and 2-mercaptobenzimidazole can make the imidization proceed without retardation and avoid the decomposition above 300°C. By choosing appropriate surface treatment systems, one can achieve the improvement of adhesion between PI and Cu substrate.