Blind via Hole Drilling for Multi-Layers Printed Wiring Board Using Laser Beam (Comparison between Aramid and Glass Fiber Reinforced PWB-
Hirogaki Toshiki; Aoyama Eiichi; Inoue Hisahiro; Ogawa Keiji; Nobe Hiromichi; Katayama Tsutao
Abstract:In recent years, it has been required for the packaging density of PWB to be improved. It is necessary that the holes are made smaller in drilling and that the circuit patterns are made fine and multi layer. Therefore, laser drilling is paid attention as a new method of the smaller diameter drilling in PWB. This study describes the characteristics of the blind via hole for multi layers PWB by laser drilling using CO2 laser beam. Specially, aramid fiber reinforced plastics (AFRP) for laser drilling is compared with glass fiber reinforced plastics (GFRP). As results, it is clear that irradiation time has influence on the damage width around the hole for both PWBs. It takes shorter time to drill the blind via holes on PWB for AFRP than GFRP. Additionally, the taper angle of laser drilled hole is an important factor of copper plating of blind via hole after drilling. Key Words:printed wiring board, GFRP, AFRP, laser drilling, hole quality, multi-layer, copper plating