In-situ Embedding of Isotropic Conductive Adhesives in FFF : (A Single-step Approach to Additively Manufactured Electronics)

Multimaterial additively manufactured electronics (AME) describes the technology of printing conductive and dielectric materials within a single processing system. Commonly used conductive materials, such as metallic nano particle inks, require a subsequent sintering process. This research introduces a novel approach by embedding an isotropic conductive adhesive (ICA) during the fused filament fabrication (FFF) process, involving the dispensing of an ICA into a printed channel and the subsequent deposition of molten thermoplastic on top. Utilizing the heat of the molten thermoplastic, this approach enables the fabrication of low-resistance conductor paths in a single process step. Employing a full factorial design of experiments (DOE), the process parameters effects on the ICAs conductivity and the thermoplastic temperature profile were investigated. The maximum conductivity of 8.27×10⁵ S/m was achieved for the conductor path embedded with a liquefier temperature of 300 °C, an embedding speed of 100 mm/sec, and a deposition height of 300 µm. While liquefier temperature and print speed affect the thermoplastics temperature profile, the deposition height affects the cross-sectional geometry of the conductor path, altering its surface-to-volume ratio. This study successfully demonstrates the in-situ fabrication of low-resistance conductor paths in a single process step by utilizing an ICA.