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Dissimilar laser welding of aluminium and copper alloys

TWI worked for its members to solve the technical problems of joining aluminium to copper using laser welding technology. An increasing number of enquiries over the past two years from members asking for support in this area led to the successful development of a high-speed laser-technology-based solution.

An increase in manufacturing demand in the automotive industry, for example, for products with high capacity battery cells is leading to interest in the technical solutions. High capacity battery cells use aluminium and copper, as the anode and cathode terminals respectively, to improve electric current flow and boost a vehicle’s performance. Existing electrical connection joining technologies, such as ultrasonic welding and the use of direct conductive adhesives, are deemed too slow for the high demand in a manufacturing situation.

Laser welding is considered an attractive process to industry due to its high processing speed and highly repeatable, fully automated, process. However, laser welding of copper to aluminium presents several challenges. Because of the high surface reflectivity and thermal conductivity of copper, and the poor miscibility of aluminium and copper, keyhole instability and brittle intermetallic formation are common issues found when laser welding these metals.

TWI identified a successful laser-technology-based approach to address the technical challenges, and developed a high-speed (up to 20 m/min) laser welding technique that uses a high brightness laser and a narrow beam width. The project team demonstrated successful welds in a range of material thicknesses, ranging from 0.2mm up to 1mm.

The team then micro analysed the welds in-house, with positive results showing that a high-speed laser welding approach was capable of minimising the formation of the brittle intermetallic phases, and improving the electrical performance of the dissimilar joints.

For more information, please email contactus@twi.co.uk.

Avatar Paola De Bono Section Manager – Laser and Sheet Processes

Paola De Bono is Section Manager in the Laser and Sheet Processes Section at TWI Ltd. Paola has over eight years of specific experience in laser processing for micro-scale applications, including the welding of highly reflective metals and applications using dissimilar materials.

Having gained her master’s degree in chemical engineering from the University of Palermo in Italy, Paola continued her studies with the Italian Engineering Association, becoming a Chartered Engineer.

Moving to the UK, Paola studied for an engineering doctorate with Birmingham University, where her investigation focused on the topic of ‘Laser Welding of Copper and Aluminium Alloys for electrical Interconnects’.

Originally joining TWI as a Project Leader in 2007, Paola went on to become a Senior Project Leader and then the Team Manager for the Lasers and Sheet Processes section, before becoming the section manager. Her current role involves day-to-day operational management, supporting the delivery of the section strategy, in line with TWI’s corporate plan.

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