Incremental printing of symbolic information – Ink jet – Combined
Reexamination Certificate
1997-02-21
2001-05-01
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Combined
C347S075000, C347S078000, C347S081000
Reexamination Certificate
active
06224180
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to a method and apparatus for jetting liquid metal, and ore specifically to a continuous mode solder jetting system and method.
Various soldering schemes have been developed for electrically bonding semiconductor integrated circuit (IC) chips to a substrate (e.g., a printed circuit board). In some schemes, a semiconductor IC chip is bonded to a substrate by applying a small solder bump to the bottom surface of the chip, aligning the solder bump with a bond pad on the surface of the substrate, and heating the solder bump until it reflows. In some other schemes, solder bumps are applied to bonding pads on a substrate; afterwards, electronic components are bonded to the substrate by positioning the components over the solder bumps and by heating and reflowing the solder bumps. In some schemes IC chips are bonded to a patterned layer of solder created by applying a thin layer of solder paste to a substrate through holes in a stencil, leaving a selected solder pattern on the substrate. Recently, solder jet systems have been proposed for depositing molten solder droplets onto a substrate in a selected pattern. Such systems include a solder droplet ejector, which may eject solder droplets on-demand or continuously.
SUMMARY OF THE INVENTION
Embodiments of the present invention are directed to an apparatus for providing continuous jetting of liquid metal droplets. In one embodiment, a jetting apparatus includes a liquid metal ejector for providing a continuous stream of charged droplets, a deflection device, a print chute and a collection reservoir. During operation of the jetting apparatus, the droplets are either deflected by the deflection device to cause the droplets to pass through the print chute and be deposited on a substrate, or the droplets are deposited into the collection reservoir. In embodiments of the invention, the jetting system includes control systems for calibrating and controlling the continuous stream of droplets to ensure that the selected droplets are placed at desired locations on a substrate.
In one embodiment, the ejector of the liquid metal dispensing system has a replaceable cartridge with an orifice-defining structure, a vibration device, and a charging device. As the liquid metal leaves the ejector, a standing wave is produced in the stream by the vibration device to break the stream into individual droplets. These droplets are surrounded by an inert gas from a gas delivery system to prevent oxidation of the droplets. As the droplets separate from the stream, an electric charge is selectively applied by the charging device on a droplet-by-droplet basis. This charge enables the deflection device to adjust the position of the droplets.
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Johnson William
Main Melvin
Muntz E. Philip
Orme-Marmarelis Melissa E.
Pham-Van-Diep Gerald
Barlow John
Hallacher Craig A.
Mintz Levin Cohn Ferris Glovsky and Popeo P.C.
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