Microscale metal additive manufacturing by solid-state impact bonding of shaped thin films

The deposition of device-grade inorganic materials is one key challenge towards the implementation of additive manufacturing in microfabrication, and to that end, a broad range of physico-chemical principles has been explored for 3D fabrication with micro- and nanoscale resolution. Yet, for metals, we still lack a process that achieves material quality rivaling that of established thin-film deposition methods and at the same time has potential to combine high throughput production with a broad palette of processable materials. Here we introduce the kinetic, solid-state bonding of metal thin films for the additive assembly of high-purity, high-density metals with micrometer-scale precision. Indirect laser ablation accelerates micrometer-thick gold films to hundreds of meters per second without their heating or ablation. Their subsequent impact on the substrate above a critical velocity forms a permanent, metallic bond in the solid state. Stacked layers are of high density (>99%). By defining thin-film layers with established lithographical methods prior to launch, we demonstrate a variable feature size (2-50 μm), arbitrary shape of bonded layers and parallel transfer of up to 36 independent film units in a single shot. We thus establish the solid-state kinetic bonding principle as a viable and potentially versatile route for micro-scale AM of metals.