Toward an Internet of Things Circular Economy Using Printed Circuits on Reusable Steel Substrates

There is a pressing need to reduce electronic waste, which along with government edicts and national time-bound policy directives are shaping the drive toward circular economy solutions in electronics. However, there is no industrially standardized approach for fabricating high-throughput recyclable and reusable electronic assemblies. Herein, we present the functionalization of steel over large areas with low-cost insulative intermediate layers as Printed Circuit Boards (PCBs), enabling an electronics circular economy. Roll-to-roll-friendly reusable steel substrates are coated using Sol–gel-based low-roughness insulative layers, with conductive tracks and solder pads additively manufactured with direct-write printing. To demonstrate how degradable 3D scaffolds could enable wireless applications, RF components, and wi-fi nodes are demonstrated with 3D-printed antennas showing the feasibility of broadband Internet of Things applications up to 6 GHz. At their end-of-life, the steel-based PCBs are sonicated in non-hazardous solvents allowing for the rapid recovery of components and precious metals. The environmental benefits of our approach are discussed using Life Cycle Assessments (LCA) and a comparative LCA between these scenarios has been undertaken. Consideration of the final product cost is given and potential business models to enter the electronics market are identified.