Flash ablation metallization of conductive thermoplastics

Fused filament fabrication (FFF) is the most widely available 3D printing technology. Recently, a variety of conducive thermoplastic filaments have become commercially available, allowing printing of electronic structures using the technology. However, the contact interface and conductivity of these filaments after printing remains relatively poor, the latter of which is typically at least four orders of magnitude lower than bulk metal conductors. While several post-processing approaches exist to enhance conductivity, they are either user-intensive, time consuming, or cannot easily be integrated in-line with the rest of the printing process. In this work, we demonstrate that exposing conducive composite thermoplastic films (3D printed or solution-cast) to high-intensity pulsed light increases their conductance by up to two orders of magnitude in a manner that is fast, noncontact, and potentially in-line. This process, referred to as flash ablation metallization (FAM), is found to vaporize the thermoplastic matrix on the top surface of a composite film, leaving behind a metal-dense surface layer. The technique was found to be effective for a variety of commercial and custom-made conducive thermoplastic composites, with the largest response found in Electrifi, a commercial filament consisting of copper particle loading in a biodegradable polyester. 3D-printed circuit boards were constructed with and without FAM exposure, with exposed circuits exhibiting reduced operating voltages as well as improvements in reliability.