Quality control method of blind via hole based on monitoring Cu direct laser processing in high heat radiation printed circuit board with a high speed camera

Abstract

Recently, printed circuit boards (PCBs) have become multi-layered and complex. It is to provide both multiple functions and to be compact with the development of electronic device such as smartphones. Processing by CO₂ laser is frequently used as an effective method of generating blind via holes (BVHs) to connect the circuit layers of multi-layer board. However, there are some kinds of laser drilling methods in this manufacturing field. Among them, Cu direct laser processing is attracted attention, which is a drilling method of both the surface Cu circuit layer and insulation substrate layer at the same time. In the present report, we propose a laser irradiating controlling method based on monitoring the variation of processing luminance when generating the BVH. Especially, we perform the BVH drilling of high heat radiation PCBs, which becomes to be use for high performance electronic devices, and investigate the influence of laser irradiation condition on the drilled hole quality. As a result, the proposed method is found out to be effective to achieve the high BVH quality in the PCB manufacturing fields.