Abstract
In the current manufacturing of printed circuit boards (PCBs), micro-drills are generally used to make smaller diameter through-holes in PCBs. Recently, DLC (Diamond Like Carbon) coated drill is used in the area of micro drilling of PCBs because of low friction of DLC. The purpose of this paper is to clarify the effect of the droplets on the surface of the groove of DLC coated drill. Series of drilling tests of PCBs have been carried out to investigate the drilling performance with DLC coated drill with droplets and without droplets, and with non-coated carbide drill. The cutting energy and the size of a chip when drilled with DLC coated drill without the droplets are smaller than when drilled with the non-coated carbide drill. On the other hand, when drilled with the DLC coated drill with the droplets, they are almost equivalent to when drilled with the non-coated carbide drill. It is important to eliminate the droplets on the groove of DLC coated drill to reduce the cutting energy when drilling PCBs.
