Elucidation of Process Mechanisms of Cu-Direct Laser Drilling in Printed Wiring Boards Based on Monitoring Method with a High Speed Camera

Abstract

Nowadays, electric circuits on Printed Wiring Boards (PWBs) are becoming high-density and its layers are increasing more and more. Micro-via drilling technology using a laser has become the dominant method for drilling blind via-holes (BVHs) in the PWBs manufacturing fields. Especially, Cu-direct laser drilling has attracted attention as a novel method, which is a process to remove the surface copper circuit and the isolative resin using a CO2 laser beam at the same time. In the present report, we attempt to monitor the micro-via drilling process with a high speed camera. First, we investigated the influence of fillers in insulation layer on the drilling process and the quality around drilled hole. Second, we elucidated the removal process of surface copper circuit at the beginning of laser irradiation. Finally, we performed to observe drilling process using pulse irradiation. As a result, we clarified process mechanisms of Cu-direct laser drilling in the PWB based on monitoring method with a high speed camera.