Comparison of processes for selective electroless copper plating on 96% alumina photo-selectively activated using chlorinated and non-chlorinated photochemical coatings: photoactivity and reliability studies

Abstract

Photo-activation processes using a wide variety of photochemical coatings as activation precursors have been reported in recent years. This work presents a comparison of a series of chlorinated and non-chlorinated photochemicals in a photo-activation process for electroless copper metallization on alumina ceramic substrates. A purpose-built KrCl * excimer lamp contact mask aligner was used for the photo-selective activation step. UV spectral studies show that two chlorinated photochemicals are less susceptible to photolysis in a 222 nm excimer lamp contact mask aligner than the non-chlorinated photochemical. Evidence has been found that the photolysis process is temperature assisted and requires elevation of the substrate to temperatures in the range 60–80 °C for decomposition to take place on a time scale of the order of tens of minutes. Adhesion, resistivity and sawability test results for the electroless copper metallizations on 96% alumina activated are presented.