Surface characterization of pre-treated copper foil used for PCB lamination

Properly micro-roughened electrodeposited copper foil is used in the conventional lamination process in order to improve its bond strength. In this investigation other treatments, including pumice scrubbing, chemical etching and brush scrubbing methods, were employed in order to obtain strong bonding. The effects of these treatments are investigated in terms of copper surface morphology using optical profilometry (OP), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The microstructure of the electrodeposited copper foil surface and its bonding properties are discussed in terms of various experimental results, in order to compare it with rolled annealed copper foil. Various surface morphologies of copper foil corresponding to different treatments are observed. The pumice scrubbing showed the largest increase in copper surface roughness, which leads to the highest improvement in bonding properties. The bond strength between copper and FR-4 resin substrate was analyzed by peel strength measurements, and based on this, the optimized process to treat the copper surface is proposed.