Created in tandem with academic partners in Japan and Malaysia, the solder includes nanoparticles and micro-alloying elements that help prevent cracking and failure at the high temperatures EV electronics operate under. By improving the durability of the underpinning electronics found in EVs, the research team hopes to enhance the overall image of EVs as reliable alternatives to combustion engine vehicles.
“Everyone is advocating EVs but we still have a growing need in reliability for long term survivability,” said David Harvey, Emeritus Professor of Electronic Engineering at LJMU. “The weakest link for these electronics devices are usually the solder interconnects.”
Traditionally, lead has been widely used as the base metal of solder. However, due to its toxicity it has largely phased out by legislation including The Restriction of Hazardous Substances (RoHS) Directive 2002/95/EC, and the EU’s Waste of Electrical and Electronic Equipment (WEEE) Directive 2012/19/EU.
The most common replacement for lead is an alloy of tin, silver and copper, but this presents a big technical challenge in the type of power-electronics products that operate under extreme temperatures in EVs.
“What we’re working on is a lead-free solder that doesn’t degrade under high temperature by adding nanoparticles and micro-alloying,” said Dr Ming Zhang, lead researcher at LJMU’s General Engineering Research Institute. “The new materials should be more resistant to cracking over a product’s lifetime operating in a harsh environment, enabling longer lifetimes and impacting significantly a reduction in energy and materials required for product manufacture.
“Current alloys are prone to the formation of brittle intermetallic compounds which limit the reliability of solder joints. Our initial solution is to refine their microstructure by adding minor microalloying elements and nanoparticles, enhancing the properties of solder and reliability of solder joints.”
The research is a collaboration with Gunma University (Japan) and Universiti Malaysia Perlis (Malaysia) and is one of four projects currently funded through The British Council’s COP26 Trilateral Research Initiative 2021-22.