Low-Roughness 3D-Printed Surfaces by Ironing for the Integration with Printed Electronics

The roughness of 3D-printed surfaces poses a challenge when integrating fused filament fabrication (FFF) printing with printed electronics, leading to inconsistencies and breaks in the circuit traces. To improve the surface roughness, an ironing toolpath is proposed. The ironing toolpath involves the hot nozzle going over the printed surface with finer line spacing, remelting the surface to fill gaps, and creating a smooth finish. For further optimization, various ironing parameters are investigated including flow, speed, line spacing, and temperature. A wide range of materials is tested, including commonly used low-temperature filaments (polylactic acid, polyethylene terephthalate, acrylonitrile butadiene styrene) and high-temperature filaments (polysulfone, polyetherimide, polyether ether ketone) suitable for integration with printed electronics and medical applications. To collect the extensive datasets, an automated measurement system is deployed. With this method, surface roughness reductions of up to 96.6% are achieved and significant trends are identified. Lastly, the integration of 3D printing with electronics is demonstrated by printing a high-resolution strain gauge structure on top of an ironed surface and embedding it into fully printed tweezers which can be used in medical robotics. The insights on ironing extend beyond electronics and can also be valuable in other areas where low surface roughness of FFF-printed parts is required. Ironing toolpaths improve the roughness of 3D-printed surfaces and can enable the integration of fused filament fabrication (FFF) prints with printed electronics. Herein, important ironing parameters and materials are analyzed and quantified extensively for optimization. The findings have wide applications for achieving smooth surface finishes in FFF prints, including accurate electronic circuit printing.image (c) 2024 WILEY-VCH GmbH