プリント基板におけるCuダイレクトバイアホールレーザ加工に関する研究 : 高速度カメラ画像に基づく除去プロセスの可視化(機械要素,潤滑,設計,生産加工,生産システムなど)

概要

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Micro-via drilling technology using a laser has become the dominant method for drilling blind via-holes (BVHs) of multi-layer Printed Wiring Boards (PWBs). Cu-direct laser drilling has attracted attention as a new method. However, the Cu-direct drilling is problematic in that it produces a copper overhang as a result of copper and resin, which have different decomposition points, being melted simultaneously. In addition, the state of PWB surface after the laser drilling is very important quality. Therefore, first, we observed the appearance of a removal which was not clear up to now because it is a momentary process. We elucidated the removal process using a high-speed camera. Second, we examined the influence that the build-up layer gave removal process. Finally, we produced the prototype PWBs which was aimed to reduce the overhang length and sputter deposition, and the effect was demonstrated. As results, the removal process in Cu-direct drilling was visualized and revealed. It was found that sputter deposition on the PWB surface after drilling increased with inorganic substance in build-up layer. Using the prototype PWBs, we achieved the suppression of overhang length and sputter deposition. PWBs which was aimed to reduce the overhang length and sputter deposition, and the effect was demonstrated.
2010-11-25