DROPLET WELDING, A NEW TECHNIQUE FOR WELDING ELECTRICAL AND ELECTRONIC CONTACTS

FROM SPOT WELDING TO SOLDERING, JOINING METAL WIRES TO ONE ANOTHER OR TO SUBSTRATES IS A MAJOR PART OF THE ASSEMBLY PROCESS FOR ELECTRICAL AND ELECTRONIC DEVICES. THIS PROGRAM IS DEVELOPING AN ENTIRELY NEW METHOD FOR WELDING SUCH JOINTS USING FILLER METALS. IN THIS NOVEL METHOD, 50-500 MUM DIAM MONODISPERSE DROPLETS OF HIGH TEMPERATURE FILLER METAL ARE GENERATED REMOTELY AND THEN TRANSPORTED AND DEPOSITED AT THE JOINT TO BE WELDED. SINCE THERE IS NO DIRECT CONTACT BETWEEN THE ENERGY SOURCE AND WELD SITE, THERMAL OR ELECTRICAL DAMAGE TO COMPONENTS IS ELIMINATED. DROPLET SIZE AND TEMPERATURE CAN BE CONTROLLED SO THAT THE WELD CAN BE TAILORED TO SPECIFIC REQUIREMENTS. ALMOST ANY METAL CAN SERVE AS A WELD FILLER, INCLUDING REFRACTORIES. WELDS OF COPPER AND ALUMINUM WIRES TO ALUMINUM AND SILICON PLATES (COPPER OR ALUMINUM FILLER) AND OF TUNGSTEN WIRES TO TUNGSTEN OR MOLYBDENUM PLATES (TUNGSTEN OR MOLYBDENUM FILLER) ARE BEING MADE. THE WELD STRENGTHS ARE MEASURED AND CORRELATED WITH EXPERIMENTAL PARAMETERS SUCH AS DROPLET METAL IDENTITY, SIZE, AND TEMPERATURE.