Picosecond laser welding of similar and dissimilar materials

Abstract

We report picosecond laser welding of similar and dissimilar materials based on plasma formation induced by a tightly focused beam from a 1030 nm, 10 ps, 400 kHz laser system. Specifically, we demonstrate the welding of fused silica, borosilicate, and sapphire to a range of materials including borosilicate, fused silica, silicon, copper, aluminum, and stainless steel. Dissimilar material welding of glass to aluminum and stainless steel has not been previously reported. Analysis of the borosilicate-to-borosilicate weld strength compares well to those obtained using similar welding systems based on femtosecond lasers. There is, however, a strong requirement to prepare surfaces to a high (10-60 nm Ra) flatness to ensure a successful weld.

Avoiding the requirement for pre-existing optical contact during picosecond laser glass-to-glass welding

“…At this point the formation terminates and the process begins again at the geometric focus as the laser is translated laterally. During this process material in the plasma affected region mixes and a true weld is formed in this area [15]. Thermal diffusion generates a HAZ but the limited mixing of material is insufficient to form a true weld [ Fig.…”

“…All experiments were carried out with constant laser spot scanning speed of 2 mm s −1 . In this experiment we used fused silica rather than borosilicate, however from our previous work [15] we expect the results to be comparable to borosilicate, although with a slightly higher pulse energy required for successful welding.…”

Laser-Welded Steel Foils with Sapphire Substrates

“…The outer region represents the width of the modified sapphire, while the inner region indicates the width of the modified stainless steel, similar to that reported in Ref. [20] for glass-to-aluminum welds. This double seam was confirmed by the cross-sectional inspection below.…”

“…[20] also for sapphire/stainless steel joints. The generated heat is not enough to bond the lower sapphire located in the setup as stabilizator (Fig.…”

“…One of the possible applications would be the production of electrically conducting steel structures on sapphire substrates. Laser welding of the stainless steel with transparent materials, like polymers [19] and sapphire, has been reported only in a few works [20,21]. In the latter references, a picosecond pulsed laser and a continuous-wave laser were used, respectively.…”