Enabling the recycling of 3D printed electronics in a circular economy

Abstract

This thesis describes the research on design measures and new recycling methods to enable the recycling of 3D printed electronics. By looking into methods to release metals from polymer substrate and design interventions to enable predictable fracturing of 3D printed structures in a shredder, a step towards the recycling of valuable metals from future electronics is made.

Recent rapid technological advancements in the production of electronics have created a vast and increasing stream of electronic waste. Not only is this is this waste a source of toxic pollutants when inappropriately processed, billions worth of valuable metals are squandered as the products are not recycled.

Current technological advancements are made in the development of additive manufacturing techniques that enable the 3D printing of structural electronics. This novel production technique promises enormous possibilities when it is matured as manufacturing method for embedded electronics in consumer products. However, 3D printing of electronics will leave components and circuitry made from valuable metals embedded between fused layers of one or more other materials. This results in the whole piece becoming electronic waste at the product’s end of life, with no fitting processes in place to retrieve the value embedded in the product.

Literature research and field studies led to the conclusion that designers should be supported in the design of recyclable 3D printed electronics. Complications in the access to the embedded components and circuitry and liberation of dissimilar materials were identified as main concerns in the recycling process. Explorative studies to solve these two problems were conducted parallelly. One study aimed at the design of 3D printed structures that enable predictable fracturing of the object in a shredder, which facilitates access to the circuit and components in the recycling process. The second study focussed on new methods to achieve the release of silver circuitry from PLA substrate, aiding in the liberation of the this metal in a recycling process.

In the first study several design interventions were found that allow controlled fracturing in a shredder. The best results were obtained with modifications that led to fracture in a horizontal plane, in the direction that the object is build. In the second study promising results were obtained by heating the substrate and circuitry by submerging the object in hot liquid and moving the circuitry and substrate relatively to each other. Ultrasound was investigated as a method to induce this relative movement in the product while it was submerged in hot water. Both methods require further investigation before definitive conclusions can be drawn.

Based on the results of the two studies and a literature study on the current recycling processes for electronics, guidelines for the design of recyclable 3D printed electronics were established. Through a flow chart designers can find the fitting guidelines for their product based on the key characteristics of the product. To enhance and elaborate the formed guidelines, it is recommended to proceed with further research in selected aspects of the studies as presented in the last chapter of this thesis.