Interconnected printhead die and carrier substrate system

#The present invention relates generally to certain construction and construction methods for making printheads of hard-copy-producing devices such as computer printers, graphics plotters and facsimile machines. More particularly, the present invention concerns the construction of a printhead of a thermal inkjet printer that includes one or more printhead dies, each with a stepped shape, interconnected to a carrier substrate that also has a stepped shape.

#Ink-jet technology is employed in hard-copy-producing devices such as computer printers, graphics plotters and facsimile machines. By way of background, a description of ink-jet technology is provided in various articles in the Hewlett-Packard Journal such as those in the following editions: Vol. 36, No. 5 (May 1985), Vol. 39, No. 4 (August 1988), Vol. 39, No. 5 (October 1988), Vol. 43, No. 4 (August 1992), Vol. 43, No. 6 (December 1992) and Vol. 5, No. 1 (February 1994).

#An inkjet pen typically includes an ink reservoir and an array of inkjet printing elements, or nozzles. The array of printing elements is formed on a printhead. Each printing element includes a nozzle chamber, a firing resistor and a nozzle opening. Ink is stored in an ink reservoir and passively loaded into respective firing chambers of the printhead via an ink refill channel and ink feed channels. Capillary action moves the ink from the reservoir through the refill channel and ink feed channels into the respective firing chambers. The printing elements are formed on a common, so-called carrier substrate.

#FIG. 1 is a fragmentary, sectional view of an interconnected stepped printhead die and carrier substrate system in accordance with a first embodiment of the present invention.

#FIG. 2 is similar to FIG. 1 showing a second embodiment of the invention.

#FIG. 3 is similar to FIGS. 1 and 2 showing a third embodiment of the invention.

#From an overview, there will be discussed below various embodiments of the present invention, and it should be understood that a preferred one of the various disclosed embodiments will depend upon the particular application and will be apparent to those skilled in the art.

#Referring to FIG. 1, a first embodiment of the invention is shown at 10 including a stepped printhead die 12 interconnected to a stepped carrier substrate 14. Die 12 includes the various components (undepicted) discussed in the above Background section. Fabrication of the stepped shape of the die and substrate is accomplished according to any suitable method, and preferably according to the method described in co-pending U.S. patent application Ser. No. 09/070,864 entitled Inkjet Printhead for Wide Area Printing, filed Apr. 30, 1998, which application is incorporated herein by reference. Suitable electrical connectors such as wirebonds, schematically depicted at 16, provide electrical connection or communication between printer-operational integrated circuitry located on die 12 and printer-operational integrated circuitry located on substrate 14. That electrical connection is shown schematically by die-connection points 18 and substrate-connection points 20. Those points may take the form of gold-to-gold metal bonds, solder joints or diffusion bonds under suitable temperature and pressure.

#The combination of wirebonds 16, die-connection points 18 and substrate-connection points 20 make up what may be thought of as an electrical-connection region of the interconnected printhead die and substrate system of the present invention. A suitable ink slot 22 is formed in the die and substrate to provide a channel for ink to flow from a suitable ink delivery system, shown schematically at 24. Suitable ink delivery systems typically attach ink containers in an on- or off-axis orientation to direct ink into the ink slot via tubes or other suitable conduits. Ultimately, ink droplets are ejected from an operative (or outer) face 12a of die 12 via suitable ink-flow architecture (including nozzles), depicted schematically at 26, to print media shown schematically at 28.