This is the claim of researchers from Liverpool John Moores University and its partners in Japan and Malaysia whose early results show the solder to be more durable with reduced cracks over a products lifetime.
“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.”
Lead has traditionally been the base metal of solder but, due to its toxicity, is nearly 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.
Its most common replacement – an alloy of Tin, Silver and Copper – currently presents a big technical challenge in power-electronics products due to the high operating temperature 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 products 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.
Entitled Go-GREEN: Next Generation Solder Materials for Power Electronics and Green Electric Transport, the British Council project aims to establish research collaborations in the field of climate change between the UK, Japan and ASEAN member countries.