Hybrid additive manufacture: Surface finishing methods for improving conductivity of inkjet printed tracks on non-planar substrates fabricated using fused deposition modeling

This study investigates the impact of the surface quality of 3D printed non-planar surfaces on the conductivity of an inkjet-printed silver nano-particle ink, in the context of fused deposition modeling; a type of additive manufacture (3D pritnting). It was observed that the as-printed surface finish resulted in continuity breaks together with reduced and overall poor batch consistency of conductivity (SDbatch = 16.51 mS/ mm). Therefore, to pave the way for high density, consistent and repeatable electronic tracks, the surface finish of as-printed 3D printed parts must be improved. To mitigate this, several finishing methods were investigated, CNC machining, non-planar nozzle ironing and the technique of burnishing with a custommade heated tool. Of all the investigated finishing techniques, burnishing was identified as the most effective solution that ensured a high and consistent conductivity across the surface for subsequently printed nanoparticle tracks (SDbatch = 2.88 mS/mm). The combination of non-planar burnishing and non-planar printed electronics is key to unlocking the possibility of completely embedded 3D electronics and sensors in 3D printed objects and components.(C) 2021 Elsevier B.V. All rights reserved.