Effect of backstitch tool path on micro-drilling of printed circuit board

As electronic components have become smaller, micro-drilling tools have been developed and used to drill holes in the hundred-micrometer range on printed circuit boards. To improve the productivity of the drilling process, printed circuit boards are generally stacked in several layers and drilled simultaneously. In this process, however, misalignment of the drilled holes on the top and bottom layers occurs, and this consequently degrades the overall product quality. To solve this problem, a new tool path strategy is proposed, which we refer to as the backstitch tool path. The basic scheme of the suggested strategy is to make a balance on the substrate. We compared this approach with a conventional tool path by examining the hole positioning error, drilling thrust force, drilling torque, and drilling duration under various drilling conditions. The effects of each process parameters were analyzed, and the suggested backstitch tool path has a positive effect on low bending stiffness tool, too much adjacent holes, and higher in-feed rate, respectively. Applying the backstitch tool path strategy to a micro-drilling operation improved the productivity and product quality.