An investigation on artwork image mis-alignment in printed circuit board manufacturing

Printed circuit boards (PCBs) or printed wired boards (PWBs) are basically made by transferring circuitry artworks on to each layer of the boards with photolithography and chemical etching processes, then hot-pressing all layers of circuitry together to form the final product. In order to protect the outer layer circuitry from solder bridging and foreign contamination, a layer of solder mask is applied to cover the board surface, leaving only the necessary area, such as lead pads and fingers, exposed. The registration or alignment between each layers becomes more and more critical for the quality of the final product as the circuit density increases. This problem is most severe in the dry film artwork transfer and wet-film solder mask, 15-20% defect rates were reported. The project in investigates the entire artwork transferring process and operation with an objective to identify the major process parameters acid to develop a process improvement model to reduce the defect rate. The investigation process and findings of Phase I are presented in this paper