Electronic waste is an increasing issue, but this degradable material could enable the recycling of components from numerous single-use and wearable devices.

Electronic waste (e-waste) is a rapidly escalating global issue, and the situation is anticipated to worsen with the rise of new flexible electronics for robotics, wearable devices, health monitors, and single-use applications.

A novel flexible substrate material developed by researchers at MIT, the University of Utah, and Meta could address this challenge. This material not only facilitates the recycling of components at the end of a device's life but also supports the scalable manufacturing of more complex multilayered circuits than current substrates.

Figure 1. New Flexible Electronics Substrate May Reduce E-Waste

The development of this new material is detailed in a recent paper published in the journal RSC: Applied Polymers by MIT Professor Thomas J. Wallin, University of Utah Professor Chen Wang, and seven other co-authors. Figure 1 shows New Flexible Electronics Substrate May Reduce E-Waste.

“We recognize that electronic waste is an ongoing global crisis that will only intensify as we continue to build more devices for the Internet of Things and as global development progresses,” says Wallin, an assistant professor in MIT’s Department of Materials Science and Engineering. Much of the current academic research on this issue has focused on developing alternatives to conventional substrates for flexible electronics, which mainly use a polymer called Kapton, a trade name for polyimide.

Most research has explored entirely different polymer materials, but Wallin notes that this approach overlooks the commercial reasons for choosing existing materials. Kapton is favored for its excellent thermal and insulating properties and the ready availability of its source materials.

The polyimide market is expected to reach $4 billion globally by 2030. “It’s everywhere, in virtually every electronic device,” including components like flexible cables that connect parts inside cellphones and laptops, Wang explains. It’s also widely used in aerospace applications due to its high heat tolerance. “It’s a classic material, but it hasn’t been updated in three or four decades,” he adds.

However, Kapton is nearly impossible to melt or dissolve, which prevents it from being reprocessed. This same characteristic also complicates the manufacture of advanced architectures, such as multilayered electronics. Traditional processing of Kapton involves heating it to 200-300 degrees Celsius, a slow process that takes hours, according to Wang.

The alternative material developed by the team is a form of polyimide, which should integrate well with existing manufacturing processes. It’s a light-cured polymer similar to those used by dentists for quick-setting fillings that cure in seconds with ultraviolet light. This method not only speeds up the hardening process but also operates at room temperature.

This new material could serve as a substrate for multilayered circuits, allowing for a significant increase in component density within a compact form factor. Unlike Kapton, which requires gluing layers together, adding steps and costs, the new material can be processed at low temperatures and hardened quickly on demand, potentially enabling more advanced multilayer devices.

For recyclability, the team has incorporated subunits into the polymer backbone that can be rapidly dissolved with an alcohol and catalyst solution. This allows for the recovery and reuse of precious metals and entire microchips from the solution for new devices.

“We designed the polymer with ester groups in the backbone,” unlike traditional Kapton, Wang explains. These ester groups can be easily broken down by a mild solution, allowing the substrate to be removed while leaving the rest of the device intact. Wang also notes that the University of Utah team has co-founded a company to commercialize this technology.

“We break the polymer back into its original small molecules, which allows us to collect and reuse the expensive electronic components,” Wallin adds. “Given the current supply chain shortages for chips and certain materials, and the high value of rare earth minerals in these components, there’s a strong economic as well as environmental incentive to develop processes for recapturing these materials.”

The research team included Caleb Reese and Grant Musgrave from the University of Utah, along with Jenn Wong, Wenyang Pan, John Uehlin, Mason Zadan, and Omar Awartani from Meta’s Reality Labs in Redmond, Washington. The work was supported by a startup fund from the Price College of Engineering at the University of Utah.

Source:MIT News

Cite this article:

Janani R (2024), New Substrate Material for Flexible Electronics Could Aid in Reducing E-Waste, AnaTechMaz, pp. 39