HIGH-SPEED FABRICATION OF HIGHLY UNIFORM ULTRA-SMALL METALLIC MICROSPHERES

In a high-speed fabrication process for producing highly uniform ultra-small metallic micro-spheres, a molten metal (16) is passed through a small orifice (30), producing a stream of molten metal (32) therefrom. A series of molten metal droplets forms from the breakup of this capillary stream. Appli...

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Bibliographic Details
Main Authors SMITH, ROBERT, ORME-MARMERELIS, MELISSA
Format Patent
LanguageEnglish
French
German
Published 05.03.2003
Edition7
Subjects
CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS
CASTING
ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
ELECTRICITY
MAKING METALLIC POWDER
MANUFACTURE OF ARTICLES FROM METALLIC POWDER
MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
PERFORMING OPERATIONS
POWDER METALLURGY
PRINTED CIRCUITS
TRANSPORTING
WORKING METALLIC POWDER
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Summary:In a high-speed fabrication process for producing highly uniform ultra-small metallic micro-spheres, a molten metal (16) is passed through a small orifice (30), producing a stream of molten metal (32) therefrom. A series of molten metal droplets forms from the breakup of this capillary stream. Applied harmonic disturbances are used to control and generate satellite (35) and parent (37) droplets. Significantly, the satellite droplets formed are smaller than the orifice, allowing for the production of smaller metal balls and finer pitch conductive traces and ball grid arrays with larger orifices. The satellite droplets are separated from the parent droplets by electrostatic charging (40) and deflection or by aerodynamic or acoustic sorting. In one embodiment, the satellite droplets are cooled before being collected to avoid defects and achieve high uniformity of the resulting metal balls. In another embodiment, the satellite droplets are electrostatically charged on a droplet-by-droplet basis and are then deflected by, e.g., an electric field to predetermined locations on a substrate. The satellite droplets can be placed in individual locations on the substrate or can be overlapped to form conductive traces.
Bibliography:Application Number: EP20010937626