Ultrashort Laser Welding of Highly Dissimilar Materials

We report on our recent research developing a novel technique to weld highly dissimilar materials e.g. optical glasses to metals. The technique is based on the use of an ultrashort (5.9ps) 400 kHz Trumpf pulsed laser operating at 1030 nm. Tight focussing of the light at, or near, to the interface of the two materials generates a highly localised plasma through simultaneous absorption in both materials. Provided that two components are in close contact, the plasma is confined and as it mixes and cools it forms a weld between the two materials.
This process is possible within materials with highly dissimilar thermal properties due to the use of ultrashort, ps, pulses. This enables a short interaction time limiting the heat affected zone (HAZ) to a region of only a few hundred micrometres around the weld.
We will report on our results for bonding of a range of material combinations including, Al-BK7, Al-SiO2 and Nd:YAG-AlSi. Particular emphasis will be laid on the technical requirements for bonding, specifically; mating of the two materials, laser parameters, and laser stability requirements. The quality of the resulting bonds will also be discussed with reference to the shear strength, thermal properties and accelerated lifetime tests will be presented