Optimizing drilling conditions in printed circuit board by considering hole quality: Optimization from viewpoint of drill-movement time

In recent years, the production of printed circuit boards (PCBs) has not only increased in quantity but also improved in quality. One requirement has been that the packaging density of PCBs be improved. High packaging density technology has allowed downsizing. The actual time required for drill processing and movement on PCBs has grown longer due to the higher densities. Attention was focused on movement time. The order in which holes are made on PCBs was considered for the purpose of improving productivity. The results are shown below.(1)In cases where the same hole grouping is repeated, the shortening ratio to the whole is understood by applying TSP to the group, because the results obtained for both the whole and the group are similar.(2)It was assumed that the distribution of the hole arrangement on the PCB was related to this shortening ratio. Here, the hole distribution was calculated using fractal analysis. As a result, the decentralized index using the fractal analyses and the shortening ratio have a positive correlation.