Drop-on-demand metal jetting of pure copper: On the interaction of molten metal with ceramic and metallic substrates

Abstract

Copper, renowned for its exceptional electrical and thermal conductivity at a low cost, holds great promise in electronic applications. While additive manufacturing of copper has attracted interest, the exploration of applying Drop-on-demand Metal Jetting (DoD-MJ) to 3D print pure copper remains uncharted. To fill this research gap, we employed an in-house DoD-MJ platform, MetalJet, to generate Cu microdroplets and deposit them onto ceramic and metallic substrates, a first-time achievement in this research context. Our study demonstrates the successful generation of uniform Cu microdroplets, emphasising the pivotal role of oxygen content control in preventing nozzle-level reactions, a factor that can disrupt droplet formation. Both alumina and aluminium nitride substrates exhibited poor wettability with molten Cu droplets, and no interface formed between these surfaces due to thermodynamically unfavourable reactions. Nevertheless, the irregular surface of alumina displayed an interesting capability to enable the adhesion of Cu droplets to the substrate through an interlocking mechanism. Lastly, the electrical resistivity of MetalJet printed pillars was measured as low as 6.75×10-8Ωm without any post-treatment, offering exciting possibilities for applications in 3D electronics.

Keywords

• Additive Manufacturing
• Drop-on-demand Metal Jetting
• Metal and Ceramic Interface
• Copper Microdroplet
• MetalJet