Development of a Facility for Molten Metal Micro-droplets Generation. Application to Microfabrication by Deposition

The development of a facility for the generation and deposition of molten metal droplets of small size (on the order of 1 mm) is described. The facility will allow accurately synchronize the instants at which the micro droplets are generated and fall in the vertical deposition direction (Z axis) with the movement (X and Y axes) of the substrate located below the micro-droplet generator. A great challenge of this type of processes is to find optimal operating conditions that allow us to manufacture with sufficient accuracy tridimensional metallic micro structures, more or less complex, which can be of interest in the electronic or additive manufacturing industry. These optimal conditions are affected by many factors including the oxidation phenomena that usually occur in many liquid metals. These oxidation phenomena tend to form an oxide layer on the molten metal surface exposed to the ambient air, which may greatly modify the viscosity, wetting capability or surface tension of the liquid droplet. A detailed analysis of the effect of the oxygen content in the atmosphere where the experiments are made on the outcome of the droplet impact on a solid surface is carried out in this work. The results of this analysis show a strong influence of the surface oxidation on the droplet dynamics before and after the impact.