# Additively Manufactured Polymers for Electronic Components
## 5 Current Limitations and Overcoming Strategies
Surface roughness induced by layer-by-layer deposition can also degrade device performance, as it was demonstrated that AJP-printed Ag transmission lines can perform competitively with PCB copper traces, if roughness does not exceed a few micrometres [192]. Hence, optimisation of printing parameters becomes crucial to minimise surface roughness and improve the performance of electronic devices. Moreover, cracking and void formation during drying and sintering of metallic inks are common defects that emerge from shrinkage-induced stress and poor wetting on substrates, leading to discontinuities that break electrical pathways and increase the series resistance of printed traces. [PERSON] et al. reported cracks in silver inkjet-printed tracks on plasma-treated glass-reinforced epoxy substrates, where microvoids resulting from substrate roughness reduced conductivity and adhesion [193]. Achieving low defect, reliable electrical contacts in printed electronics requires careful management of ink formulation, substrate preparation, and sintering conditions. Addressing these issues, robust material-process integration is essential to translate additively manufactured devices from lab prototypes to dependable real-world systems. A higher material throughput was demonstrated only on a lab scale. Hardware with multiple printheads needs to be developed to compete with the industrial machines available nowadays for industrial applications. Furthermore, certain technologies impose stringent limitations on the types of materials that can be utilised, consequently restricting the available options. During vat photopolymerisation (SL/DLP), conductive fillers like CNTs, graphene, or MXenes can significantly interfere with UV-curing by either absorbing or scattering incident light, leading to incomplete cross-linking of the polymer matrix. [PERSON] et al. demonstrated that even at low loading (0.25 wt%), CNTs reduced cure depth, necessitating post-UV or thermal treatments to achieve mechanical integrity and reliable conductivity [194]. Similarly, [PERSON] et al. reviewed vat photopolymerisation of nanocomposite resins and highlighted the need for a trade-off between filler content and photo-curing due to UV attenuation [195]. As a result, poor curing leads to defects, such as weak interlayer adhesion, dimensional inaccuracy, and zones of mechanical brittleness, which undermine electrical continuity and device robustness. For these reasons, post-processing treatments, such as thermal post-curing, become crucial to improve interlayer bonding. Moreover, it is essential to expand the versatility of many AM platforms, which still restrict usable materials. In light of this, technologies like LIFT and AJP offer the opportunity to handle diverse inks with different rheological behaviours. However, novel concepts applied to existing technologies, as well as emerging additive manufacturing techniques, so far primarily used for metals and their oxides [196; 197], can be explored for polymers in future research, thereby broadening the possibilities. In addition, future developments should not only address current processing limitations but also focus on creating a fully digital, feedback-driven AM workflow. This includes in situ monitoring of print quality, real-time property mapping, and adaptive printing strategies to enable quality assurance and complex device fabrication.