Development Of Flexible Copper / Nickel Plate Based On Self - Assembled Electroless Plating

A novel, simple method based on molecular self-assembly electroless plating was developed to improve the adhesion strength between the substrate and the copper foil, which could simplify the procedure to prepare flexible copper laminates (FCCL).Polyethylene terephthalate (PET) was used as substrate to prepare FCCL via substrate modification, metal catalytic activation and electroless copper plating. Prcoess developed in this study had advantages of gaining high adhension strength between the copper layer and the substrate, excellent smoothness of copper coating and good conductivity of FCCL, Two reagents were used for substrate modification:(1)3-aminopropyltriethoxysilane (APTES) and (2) ethylenediamine (EDA). These two reagents can react with PET and graft amino group on the surface of PET, which makes the substrate surface more hydrophilic.The catalytic activication of the modified PET sheets included two ways:(1) adsorption of gold, silver and palladium nanoparticles in solution as the catalytic activiation center;(2) adsorption of non-noble metal ions on the modified PET sheets in solution, such as copper, iron, nickel, cobalt, manganese and aluminum ions, then the adsorbed metal ions on the PET surface were reduced to metal atoms by sodium borohydride, which were used as the catalytic activiation center. Finally, FCCL was prepared by elctroless copper plating. In addition, flexible nickel clad laminates based on electoless nickel plating was also studied with the similar procedure.The organic groups on the substrate, the hydrophilic of PET surface, the structure of the modified substrate, the elements, flatness, conductivity and adhesiveness of FCCL were tested by infrared spectroscopy (IR), the contact angle, X-ray photoelectron spectroscopy (XRS), X-ray diffraction (XRD), atomic force microscopy (AFM), resistance tester, and Scotch tape.For the preparation of FCCL, the optimum conditions are:room temperature,50%EDA in DMSO as modifying reagent, modification time:6hours, gold nanoparticles as catalyst, the concentration of copper ion in bath:0.02mol/L. The obtained copper layer has following proprties:thickness of50-1200nm, roughness of14nm (surfces area:10×10μm), conductivity of13.4μΩ·cm and adhesion of passing Scotch tape test.For the flexible nickel clad laminate, the following the process was performed, EDA modification, iron activiation and electroless nickel plating. The obtained nickel layer has following proprties:thickness of50～200nm, roughness of20nm (surfces area:10×10μm), conductivity of550μΩ·cm and adhesion of passing Scotch tape test.