Fabrication of two-layer flexible copper clad laminate by electroless-Cu plating on surface modified polyimide

A flexible copper clad laminate(FCCL) was fabricated using electroless- and electro-Cu plating processes and the effects of pre-treatment time on the adhesion strength of the FCCL were evaluated based on interfacial morphology. The neutralization and catalyst time were varied in the range of 0-20 min and 0.1-10 min, respectively, and the interfacial condition of the FCCL was characterized by atomic force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS). It is observed that the peel strength increases significantly as the neutralization and catalyst time increase. Peel strength as high as 7.2-7.3 N/cm is obtained as the neutralization and catalyst time increase up to 20 min and 10 min, respectively, which is comparable to the strength achieved by the conventional laminating and sputtering processes. These improvements are probably due to an increase in the surface roughness of polyimide (PI), the activated surface condition, and the adsorption of palladium ions/atoms (Pd) on the PI surface which act as nucleation sites for Cu.