Effect of thermal treatment on adhesion strength of Cu/Ni–Cr/polyimide flexible copper clad laminate fabricated by roll-to-roll process

In this study, the effect of a Ni–Cr seed layer on the adhesion strength of flexible copper clad laminate (FCCL) was evaluated after thermal treatment. The changes in the chemical composition, morphology and adhesion property were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), electron probe micro analyzer (EPMA), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and 90° peel test. The peel strength of the FCCLs was significantly affected by the thermal treatment and the FCCL with a higher peel strength had a higher thermal stability than that with a lower peel strength. The roughness of the fracture surface for the FCCLs decreased with increasing thermal treatment temperature and holding time. The thermal treatment of the FCCL increased the ratio of the C–N bonds and reduced that of the C–O and carbonyl (CO) bonds in the polyimide.