A new collaboration between electrical and chemical engineers at Newcastle University in England has led to the development of “reversible” glue.

Aimed at tackling the global electronic waste (e-waste) crisis, this innovation offers a sustainable alternative to permanent joining methods such as solder and screws.

Although standard lead-based solder still offers superior electrical conductivity, its high environmental toxicity has forced companies to reconsider manufacturing choices.

This dilemma led industries to re-evaluate how to join electrical components. The need has created an ideal opportunity to adopt greener, reversible alternatives.

“Electrically conductive adhesives have been around for a long time, and making them reversible provides the solution to a very real problem that urgently needs addressing,” said Bassam, a Ph.D. student at the School of Engineering. 

Sustainable method

Building on their existing reversible packaging glue, the team has developed a new version that is electrically conductive for joining electronic components just like solder.

However, unlike permanent solder, this new adhesive can be easily dissolved in an alkaline solution or a green solvent such as acetone. It could allow electronic parts to be cleanly separated for reuse and recycling.

This “one-pot,” water-based glue is manufactured just like standard paint, but it swaps out color pigments for conductive silver particles to achieve its unique electrical properties. 

Other silver-based conductive glues already exist on the market; this new formulation stands entirely alone in its ability to be easily dissolved and unbonded on demand.

Developed from inexpensive materials and standard paint manufacturing processes, this glue can be easily scaled up for mass production.

Moreover, this new glue sticks beautifully to metals, plastics, and printed circuit boards. Yet, unlike previous water-based adhesives, it does not fail when exposed to humid environments. It holds strong until you tell it not to.

“One of the reasons that conducting glues are rarely used is because silver is expensive and toxic in the environment. Being reversible, our glue means that the silver can be recovered and reused, which is important to keep costs down and the environment clean,” noted Mark Geoghegan, the lead investigator on the project. 

Solving e-waste problem

The electronics industry’s reliance on permanent assembly methods goes beyond solder. Even mechanical fixtures, such as screws, severely hinder automated recycling processes. However, there is a growing industry shift toward water-based formulations as a viable path to more sustainable electronics. 

The global electronic waste crisis is huge. Annually, 62 billion kilograms of e-waste are generated, equivalent to one million semi-detached houses. 

Unfortunately, less than 25 percent of it is currently being recycled. This massive volume of discarded tech represents a severe waste of minerals, which are finite, highly sought-after resources mined in only a handful of regions worldwide, some of which suffer from severe political instability. 

This reversible conductive glue offers a direct solution to the e-waste epidemic. It allows electronic parts to be cleanly disassembled, making it easier to harvest and recycle these precious, hard-to-source materials.

The study was published in the journal Advanced Electronic Materials on May 14.