Optimization of desmear process for high adhesion of insulating film in printed circuit boards (PCBs) via Taguchi method

In order to achieve a high peel strength (above 1.2 kgf cm−1) for the insulating layer in printed circuit boards (PCBs), the conditions of the desmear process (swelling, etching, reduction, and acid dip) and curing time were optimized via the Taguchi method. The desmear parameters governing the adhesion of plated metals to insulating epoxy layers were evaluated by measuring the ultimate peel strength. The signal-to-noise (S/N) ratio was maximized under the optimized precuring and desmear conditions. The expected value at the maximum S/N ratio was correlated well with the actual experimental results. The peel strength under the optimized experimental conditions was between 1.2 and 1.4 kgf cm−1, which is approximately two times greater than that obtained one when using the general wet chemical treatment.