Drillability Study of Glass Fibre Rienforced Plastics

Abstract

In recent years, the production of printed wiring board (PWB) has not only increased in quantity but also improved in quality. One requirement has been that the packaging density technology has allowed downsizing. For instance, from a general public point of view, television and telephones are typical cases of downsizing- that their use has changed from stationary to portable. From an industrial point of view, computing speed and memory size are increasing. Thus, high-quality micro machining is necessary for PWB. Specifically, the small diameter drilling PWD has attracted because the packaging density must be improved. On the other hand, a great number of holes in PWB have to be drilled and drilled holes require the reliability of through-hole plating. Even if only one hole in the production has failed to be drilled, the whole production has to be abandoned. Consequently, in order to improve the reliability of small diameter drilling in PCB, it is necessary that the relation between the tool wear and the hole quality is grasped and drilling conditions are developed in the case of present drilling machine. In addition a new drilling process which does not rely on tool life is to be researched because it is difficult to predict the tool life. Recently, there have been few studies which have mainly dealt with the machined surface conditions of FRP and there are few studies that deal with the drilling process at a certain tool condition. However, it isn’t quite sufficient to estimate the small diameter drilling process of PWB from the results of theses studies, because it is important to relate the number of drilled holes in the case of PCB. In the presented work, the drilled hole quality of the panel, made of GFRP, is evaluated by investigating the damage to the drilled holes. In conclusion, it is shown that, in the case of the present drilling machine, the anisotropy of the hole surface roughness can be developed by the tool tip profile.