Abstract
A CO_2 laser is used to drill blind via holes (BVHs) in printed wiring boards for circuit connections. Thermal input from the laser drilling causes deterioration in the quality of the material around the hole. Therefore, we propose a method to set the minimum cooling time between pulses without lowering the drilled hole quality using a high-speed camera image monitor. As for the results, from the change in the luminance value of each pulse, we were able to use this method to set a cooling time between pulses to minimize the drilling and irradiation times when forming BVHs.
