Abstract
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 drilling process, which does not require etching the copper foil, has been receiving considerable attention for the next-generation high density PWB manufacturing. However, Cu-direct drilling is problematic in that it produces a copper overhang. However, only few studies have been made in this field. This report focuses on monitoring Cu direct-laser drilling with a high speed camera. Temperature analysis can be performed by determining the two-color ratio of RGB image. In this report, the temperature of the shot image was measured by the two-color image method, and the influence of the shape of the processed hole on the temperature distribution was considered. We also proposed a method to model the cross-sectional shape of the hole by the area ratio of the holes by performing CFD analysis of the melt ejection using the thermo-fluid analysis software PHOENICS.
