Electric wiring is present in electronic household devices, cars, and buildings. A mid-range car contains multiple kilometers of copper cables, and their integration could save up to 70 kg in weight.[1] Promising strategies for integration include “in-mold electronics” and similar routes where conductive leads are directly incorporated into polymer parts. This integration results in composite materials with very limited recyclability which conflicts with regulation and sustainability goals.[2] The project for Recyclable Integrated Electronics (ReIn-E) addresses this issue by focusing on the separation of polymer materials and metals.
We present a cost-efficient and scalable method for preparation of polymer separation layers for printed electronics. Slot-die coating is used to prepare water-soluble polymer films with a dry thickness below 10 µm on commodity polymer substrates. Conductive inks based on metallic micro- or nanoparticles are printed and sintered at polymer-compatible temperatures. The separation layer does not compromise the adhesion of inks and has a positive influence on the bending stability of printed circuits. We study the material recovery and demonstrate that the integrated metal can be released within a few minutes by dissolving the separation layer in water.

References
[1] https://www.vdi-nachrichten.com/technik/automobil/automobilen-droht-der-nerveninfarkt/ accessed on 27.05.2022.
[2] Wiklund et al., J. Manuf. Mater. Process. 2021, 5(3), 89.

Acknowledgements. We acknowledge funding by the BMWK via CORNET/IGF international (project No. 288 EN). We thank our partners from Hahn-Schickard-Gesellschaft für angewandte Forschung e.V. (Germany), SIRRIS – The Collective Center of the Belgian technological industry (Belgium), and Centre Terre & Pierre (CTP, Belgium).