Estimation of monitoring image in laser blind via-hole drilling process of printed wiring boards with a high speed video camera and temperature visualization from obtained image by two-color method

Abstract

In the present report, we attempted to construct a useful monitoring method to control laser via-hole drilling process of multi-layer printed wiring boards with a high speed video camera.Cu direct laser drilling was performed for the FR-4 type insulation layer, which made of glass fiber reinforced epoxy resin plastics, with a CO₂ laser beam. First, we discussed the influence of laser irradiating conditions on the drilled via-hole quality based on estimating the visible video camera images. Second, we focused on two-color method to visualize the temperature distribution in monitoring image. As a result, the high speed video monitoring and the temperature visualization in video image are found to be effective to control the via-hole quality in laser processing.