Abstract
In recent years, portable information devices have rapidly advanced in performance and miniaturization. The build-up process is often used in the manufacture of printed wiring boards (PWBs) for high-density circuits. Presently, CO2 laser beams are generally used in the build-up process to drill blind via holes (BVHs) that connect copper foils. Cu direct-laser involves complex phenomenon as a result of drilling copper and resin, with different decomposition points, at the same time. However, only few studies have been made in this field. This report focuses on monitoring Cu direct-laser drilling with a high speed camera. We have drilled with 2 different laser power outputs of 75 W, 95 W, and analyzed the temperatures of the scatter of the resin during drilling process. In this report, image two-color method was used. As a result, we have established a method to determine inflection point of hole diameter and inner layer penetration time.
