Laser keyhole micro welding of aluminum foils to lap joints even with large gap sizes

The increasing miniaturization of components leads to increasing demands on manufacturing processes. High-brilliance lasers allow fast, low-heat deep penetration laser welding to produce narrow seams even in metal foils. In micro-joining, adjusting comparatively small gaps is a major challenge. Here, the welding of 100 µm thick aluminum foils in lap joints is investigated. Gaps of > 80% of the foil thickness were bridged. The results show that the seam width can be used to detect not only the gap size but also inner connection defects for quality control purposes. The explanation for this is the increasing gap-bridging keyhole depth, and thus heat input with increasing gap size.