Low distortion cold rolled clad sheets for PWB

New cladding process has been developed by means of a surface activated bonding (SAB) technique. In this process, surfaces of materials to be bonded are cleaned, activated by Ar ion sputter etching, and rolled with low distortion at room temperature in vacuum. This is available for cladding not only between heterogeneous metals but also between metal and polymer film. The clad sheets manufactured by this process have advantages over conventional clad sheets. For instance, they have a clean and flat interface without alloy layer. In addition, thickness of each layer is constant, even thin metal foil can be bonded with the metal foil or polymer film. In such respects the clad sheets with those features have been applied to PWB. Metal/metal clad sheets are suitable for selective wet etching working. The developed Cu/Ni/Cu 3-layer clad material makes it possible to form the 3D structure, containing the bumps and circuits, only by means of wet etching process. Metal/polymer clad materials composed of very thin rolled Cu foil and LCP Liquid Crystalline Polymer) film, are superior to the conventional materials from the point of fine etching property and high frequency property because of their smooth bonding interface. This paper reports the features of clad sheets manufactured by SAB and their applications to PWB.