(12) United States Patent
`Waller et al.
`
`(10) Patent N0.:
`
`(45) Date of Patent:
`
`US 6,250,738 B1
`Jun. 26, 2001
`
`US006250738B1
`
`INKJET PRINTING APPARATUS W'ITH INK
`MANIFOLD
`
`Inventors: David J Waller; Timothy E Beerling;
`Melissa D Boyd; James W Pearson,
`Marvin G Wong, all of Corvallis, OR
`(US)
`
`Assignee: Hewlett-Packard Company, Palo Alto,
`CA (US)
`
`Itoh, Sasaki, Uda, Yoneda, Honmou, Fukushima, “Use of
`AuSn Solder Bumps in Three—dimensional Passive Aligned
`Packaging of LD/PD Arrays on Si Optical Benches”, IEEE
`Electronic Components and Technology Conference, 1996,
`pp. 1-7.
`
`Deshmukh, Brady, Roll, King, Shmulovic, Zolnowski,
`“Active Atmosphere Solder Self-Alignment and Bonding of
`Optical Components”, The International Journal of Micro-
`circuits and Electronic Packaging, vol. 16, #2, second quar-
`ter 1993, pp. 97-107.
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`structures with
`plane
`focal
`“Multilayered
`Ludwig,
`self—aligning detector assembly”, Infrared Readout Elec-
`tronics III, SPIE, vol. 2745, 1996, pp. 149-158.
`
`Appl. No.: 09/216,601
`
`Filed:
`
`Dec. 17, 1998
`
`Related U.S. Application Data
`
`Continuation—in—part of application No. 08/959,376, filed on
`Oct. 28, 1997, now Pat. No. 6,123,410, and a continuation-
`in—part of application No. 09/216,606, filed on Dec. 17,
`1998.
`
`Int. Cl.7 ..............................
`U.S. Cl.
`Field of Search
`
`B41J 2/155
`347/42; 347/13
`347/7, 13, 15,
`347/40, 42, 43, 44
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`4,578,087
`4,620,198
`4,917,286
`5,010,023
`5,1 24,717
`5,150,945
`5,473,350
`5,500,661
`
`347/44
`3/1986 Cloutier ct al.
`. 347/43
`10/1986
`228/110
`4/1990 Pollacek ................... ..
`5/1991 Chan et al.
`.......................... .. 347/42
`6/1992 Campanelli et al.
`. 347/93
`' 11/1992 Drake .............
`. 347/42
`12/1995 Mader et al.
`347/7
`3/1996 Matsubara et al.
`.................. .. 347/40
`OTHER PUBLICATIONS
`
`Imler, Scholz, Cobarruviaz, Nagesh, Chao, Haitz, “Precision
`Flip—Chip Solder Bump Interconnects for Optical Packag-
`ing”, IEEE Transactions on Components, Hybrids, and
`Manfacturing Tech., vol. 15, #6, Dec. 1992, pp. 997-982.
`
`Kallmayer, Oppermann, Kloeser, Zakel, Reichl, Experimen-
`tal Results on the Self—Alignment Process Using Au/Sn
`Metallurgy and on the Growth of the C—Phase During the
`Rellow, ’95 Flip Chip, BGA, TAB & AP Symposium, 1995,
`pp. 225-237.
`
`Linder, Baltes, Gnaedinger, Doering, “Photolithography in
`Anisotropically Etched Grooves”, IEEE 9th Intl. Workshop
`on MEMS, 1996, pp. 38-43.
`
`* cited by cxamincr
`
`Primary Exami11er—N. Le
`Assistant Exczminer—Lamson D. Nguyen
`
`(57)
`
`ABSTRACT
`
`An inkjet printing system includes a scalable printhead with
`an ink manifold. The scalable printhead is formed by mount-
`ing an ink manifold and multiple thermal inkjet printhead
`dies to a carrier substrate. The carrier substrate is machined
`to include through—slots. There is a through—slot for each
`refill slot among the multiple printhead dies. A first end of
`a given through—slot connects to a refill slot of a correspond-
`ing printhead die. An opposite, second end of the through-
`slot connects to the ink manifold. The ink manifold includes
`an inlet for coupling to an ink supply reservoir. The ink
`manifold also includes one or more channels and a plurality
`of feed openings. Each feed opening connects to a printhead
`die refill slot by way of a substrate through—slot.
`
`28 Claims, 6 Drawing Sheets
`
`HP 1005
`Page 1 of 13
`
`

`
`U.S. Patent
`
`Jun. 26, 2001
`
`Sheet 1 of 6
`
`US 6,250,738 B1
`
`INK SUPPLY
`ASSEMBLY
`
`RESERVOIR
`
`(15)
`
`PRINTHEAD
`ASSEMBLY
`
`ELECTRONIC
`CONTROLLER
`
`MEDIA TRANSPORT ASSEMBLY
`
`HP 1005
`Page 2 of 13
`
`

`
`U.S. Patent
`
`1002(092n.uJ
`
`Sheet 2 of 6
`
`US 6,250,738 B1
`
`HP 1005
`Page 3 of 13
`
`

`
`U.S. Patent
`
`Jun. 26, 2001
`
`Sheet 3 of 6
`
`US 6,250,738 B1
`
`HP 1005
`Page 4 of 13
`
`

`
`U.S. Patent
`
`Jun. 26, 2001
`
`Sheet 4 of 6
`
`US 6,250,738 B1
`
`HP 1005
`Page 5 of 13
`
`

`
`U.S. Patent
`
`Jun. 26, 2001
`
`Sheet 5 of 6
`
`US 6,250,738 B1
`
`HP 1005
`Page 6 of 13
`
`

`
`U.S. Patent
`
`Jun. 26, 2001
`
`Sheet 6 of 6
`
`US 6,250,738 B1
`
`54a 54b 540
`
`To
`OUTLET 39b "
`
`TO
`OUTLET 39¢"
`
`'
`
`FROM
`WLET 37“
`
`33
`
`FROM
`“‘“nNLET 37¢
`
`HP 1005
`Page 7 of 13
`
`

`
`US 6,250,738 B1
`
`1
`INKJET PRINTING APPARATUS WITH INK
`MANIFOLD
`
`CROSS REFERENCE TO RELATED
`APPLICATION
`
`This is a continuation in part of commonly-assigned U.S.
`patent application Ser. No. 08/959,376, “Scalable Wide-
`Array Inkjet Printhead and Method for Fabricating Same,”
`filed on behalf of Timothy E. Beerling et al. on Oct. 28, 1997
`now U.S. Pat. No. 6,123,410. This also is a continuation in
`part of commonly-assigned U.S. patent application Ser. No.
`09/216,606 entitled ‘Multilayered Ceramic Substrate Serv-
`ing As Ink Manifold and Electrical Interconnection Platform
`for Multiple Printhead Dies,’ filed on behalf of Melissa Boyd
`et al. on Dec. 17, 1998.
`BACKGROUND OF THE INVENTION
`
`This invention relates generally to inkjet printhead
`construction, and more particularly, to a wide-array inkjet
`printhead construction.
`There are known and available commercial printing
`devices such as computer printers, graphics plotters and
`facsimile machines which employ inkjet technology, such as
`an inkjet pen. An inkjet pen typically includes an ink
`reservoir and an array of inkjet printing elements, referred to
`as 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 the ink
`reservoir and passively loaded into respective firing cham-
`bers 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. Conventionally,
`the printing
`elements are formed on a common substrate.
`
`I
`
`For a given printing element to eject ink a drive signal is
`output
`to such element’s firing resistor. Printer control
`circuitry generates control signals which in turn generate
`drive signals for respective firing resistors. An activated
`firing resistor heats the surrounding ink within the nozzle
`chamber causing an expanding vapor bubble to form. The
`bubble forces ink from the nozzle chamber out the nozzle
`opening.
`A nozzle plate adjacent to the barrier layer defines the
`nozzle openings. The geometry of the nozzle chamber, ink .
`feed channel and nozzle opening defines how quickly a
`corresponding nozzle chamber is refilled after firing. To
`achieve high quality printing ink drops or dots are accurately
`placed at desired locations at designed resolutions. It is
`known to print at resolutions of 300 dots per inch and 600 _
`dots per inch. I-Iigher resolution also are being sought.
`There are scanning—type inkjet pens and non-scanning
`type inkjet pens. A scanning—type inkjet pen includes a
`printhead having approximately 100-200 printing elements.
`A non-scanning type inkjet pen includes a wide-array or
`page—wide—array printhead. A page—wide—array printhead
`includes more than 5,000 nozzles extending across a page-
`width. Such nozzles are controlled to print one or more lines
`at a time.
`
`In fabricating wide—array printheads the size of the print-
`head and the number of nozzles introduce more opportunity
`for error. Specifically, as the number of nozzles on a sub-
`strate increases it becomes more di icult to obtain a desired
`processing yield during fabrication. Further,
`it
`is more
`difflcult to obtain properly sized substrates of the desired
`material properties as the desired size of the substrate
`increases.
`
`2
`In the related matters, cross—referenced above, a scalable
`wide-array printhead structure is described in which mul-
`tiple inkjet printhead dies are mounted to a carrier substrate.
`One of the challenges in forming a wide array printhead with
`multiple printhead dies is the number of interconnections
`which occur. Many electrical interconnections are needed. In
`addition, many ink connections are required to deliver the
`inks. In a three-color, four inch, wide-array printhead having
`34 printhead dies, for example, there are at least 102 fluid
`interconnections (i.e., 3x34=102). This invention is directed
`toward an inkjet printing device having an ink manifold.
`SUMMARY OF THE INVENTION
`
`According to the invention, an inkjet printing system
`includes a scalable printhead with an ink manifold. The
`scalable printhead is formed by mounting an ink manifold
`and multiple thermal
`inkjet printhead dies to a carrier
`substrate. Each printhead die includes a plurality of printing
`elements. Each printing element includes a nozzle chamber,
`a firing resistor and a nozzle opening. The nozzle openings
`are located along one surface of each die. One or more refill
`slots are located along an opposite surface of each printhead
`die. The refill slot
`is fluidly connected to each nozzle
`chamber allowing ink to flow into the die through the refill
`slot(s),
`then into the nozzle chambers. By prescribing a
`di erent number of printhead dies to a carrier substrate for
`di ‘erent embodiments, diiferent sized printhead embodi-
`ments are achieved.
`
`According to one aspect of the invention, the ink manifold
`is coupled to the carrier substrate. The carrier substrate is
`machined to include through-openings. There is a through-
`opening for each refill slot among the multiple printhead
`dies. A first end of a given through-opening connects to a
`refill slot of a corresponding printhead die. An opposite,
`second end of the through-opening connects to the ink
`manifold. Thus, the ink manifold is coupled to the carrier
`substrate at
`the respective second ends of the through-
`openings.
`the ink
`According to another aspect of this invention,
`manifold includes an inlet for coupling to an ink supply
`reservoir. In some embodiments the ink manifold includes a
`plurality of inlets for coupling to a plurality of ink supply
`reservoirs, (e.g., reservoirs of different color ink, such as
`black, cyan, magenta and yellow ink reservoirs). In still
`other embodiments, there also is an outlet for each inlet. Ink
`flows into the manifold through an inlet, travels through
`channels within the manifold, then is cycled out through the
`corresponding outlet. Some of the ink, however, exits the
`manifold through fill openings adjacent the carrier substrate
`through—openings so that
`ink may travel to the printing
`element nozzle chambers. Ink leaves the manifold outlet and
`fill openings.
`ln varying embodiments the carrier substrate is formed of
`silicon or a multilayer ceramic. The carrier substrate
`includes the through—openings, and also includes electrical
`interconnection pathways for routing signals among the
`plurality of printhead dies. In the multilayer ceramic sub-
`strate embodiment, the carrier substrate includes multiple
`electrical interconnection planes for routing the electrical
`signals.
`According to another aspect of the invention, the inkjet
`printing system includes multiple ink reservoirs, one for
`each color of ink. Separate inlets, manifold channels, outlets,
`and fill openings are formed in the ink manifold to flow ink
`from a respective reservoir through the manifold to the
`carrier substrate and printhead dies. A first fluid path occurs
`
`HP 1005
`Page 8 of 13
`
`

`
`US 6,250,738 B1
`
`3
`from a first inlet of the manifold through a first set of the fill
`openings through corresponding carrier substrate through-
`openings to corresponding printhead die ink refill slots. A
`second fluid path occurs from a second inlet of the manifold
`through a second set of the fill openings through correspond— 5
`ing carrier substrate through-openings to oorresponding
`printhead die ink refill slots.
`The inkjet printing system also includes a housing, a
`mounting assembly, a media transport assembly, and a
`controller. The inkj et printhead is positioned at the mounting
`assembly and includes a plurality of printing elements. A
`print zone occurs adjacent to tl1e plurality of printing ele-
`ments along a media path. The media transport assembly
`moves a media sheet along the media path into the print
`zone. The controller determines a timing pattern for ejecting
`ink from the plurality of printing elements onto the media
`sheet.
`
`According to another aspect of the invention, one method
`for loading the plurality of inkjet nozzles includes replacing
`the internal reservoir of the pen, and flowing ink from the
`internal reservoir into the ink manifold. The manifold has an ‘
`inlet coupled to the internal reservoir. The ink manifold
`fluidly connects the inlet to a plurality of through-openings
`of the carrier substrate, which in turn are coupled to respec-
`tive ink refill slots of a plurality of printhead dies. Ink flows
`into the respective ink refill slots, then into a plurality of
`nozzle chambers. Ink is fired from the nozzle chambers to
`print onto a media sheet.
`One advantage of the invention is that a manifold formed
`separate from the carrier substrate and mounted to the
`carried substrate is that new printhead designs may be more
`rapidly prototyped and tested. In addition, for a multilayer
`ceramic carrier substrate, because layers for ink communi-
`cation are not needed, fewer substrate layers may be used,
`thereby reducing the complexity of the carrier substrate and
`reducing the cost of fabricating the carrier substrate. Some
`of such cost reduction is offset by the fabrication of the
`manifold. However, for a precision molded or machined
`manifold, significant savings accrue. Another advantage
`includes a more rigid printhead assembly and added stability
`to the carrier substrate by excluding large internal cavities.
`Another possible advantage is relaxed ink corrosion require-
`ments of the substrate material. These and other aspects and
`advantages of the invention will be better understood by
`reference to the following detailed description taken in /
`conjunction with the accompanying drawings.
`BRIEF DESCRIPTION OF TIIE DRAWINGS
`
`_
`
`FIG. 1 is a block diagram of an inkjet printing system
`according to an embodiment of this invention;
`FIG. 2 is a perspective view of the printhead assembly of ‘
`FIG. 1 according to an embodiment of this invention;
`FIG. 3 is a diagram of ink flow through the ink manifold
`of FIG. 2 to a given printing element of a given printhead
`die;
`FIG. 4 is a diagram of the carrier substrate of FIG. 2 with
`mounted printhead dies;
`FIG. 5 is another perspective view of the printhead
`assembly of FIG. 2;
`FIGS. 6A—C are diagrams of respective ink flow path-
`ways for ink from respective ink reservoirs;
`FIG. 7 is a diagram of a printhead die, partial carrier
`substrate and partial manifold illustrating ink receipt from
`three ink sources; and
`FIG. 8 is a cross-sectional View of a portion of the
`printhead assembly according to another embodiment of the
`invention.
`
`4
`DESCRIPTION OF SPECIFIC EMBODIMENTS
`Printing System
`Referring to FIG. 1, a thermal inkjet printing system 10
`includes an inkjet printhead assembly 12, an ink supply
`assembly 14, a mounting assembly 16, a media transport
`assembly 18, a housing 20 and an electronic controller 22.
`The inkjet printhead assembly 12 is formed according to an
`embodiment of this invention, and includes one or n1ore
`printheads having a plurality of inkjet nozzles 17 which eject
`ink onto a media sheet M. The printhead assembly 12
`receives ink from the ink supply assembly 14. The ink
`supply assembly 14 includes a reservoir [5 for storing the
`ink. Ink is supplied to the printhead assembly 12 in either a
`recirculating or a closed end delivery system.
`In some
`embodiments the ink supply assembly 14 and inkjet print-
`head assembly 12 are housed together in an inkjet pen or
`cartridge. In other embodiments the ink supply assembly 14
`is separate from the inkjet printhead assembly 12 and feeds
`ink to the printhead assembly through an interface
`connection, such as a supply tube. For either approach the
`ink supply may be removed, replaced and/or refilled. For
`example, in an inkjet pen having an internal reservoir, the
`pen may be disassembled and the internal reservoir
`removed. A new, filled reservoir then is placed within the
`pen, and the pen reassembled for re—use. Alternatively, the
`prior reservoir may be refilled and reinstalled in the pen or
`filled in place without removal from the pen (and in some
`embodiments without even disassembling the pen). In some
`embodiments there is a local reservoir within the pen along
`with a larger reservoir located separate from the pen. The
`separate reservoir serves to refill
`the local reservoir. In
`various embodiments, the separate reservoir and/or the local
`reservoir may be removed, replaced and/or refilled.
`The inkjet printhead assembly 12 is mounted relative to
`the housing 20 to define a print zone 19 adjacent to the
`printhe ad nozzles 17in an area which is to receive the media
`sheet M. The media sheet M is moved into the print zone 19
`by the media transport assembly 13. The mounting assembly
`16 positions the printhead assembly 12 relative to the media
`transport assembly 18. For a scanning type inkjet printhead
`assembly, the mounting assembly 16 includes a carriage for
`moving the printhead assembly 12 relative to a media
`transport path to scan the printhead assembly 12 relative to
`the media sheet. For an indexing type inkjet printhead
`assembly, the mounting assembly 16 includes a mechanism
`for indexing movement of the printhead assembly 12 rela-
`tive to the media transport path. For a non-moving inkjet
`printhead assembly,
`the mounting assembly 16 fixes the
`inkjet printhead assembly 12 at a prescribed position along
`the media transport path.
`The electronic controller 22 receives documents, files or
`other data 21 to be printed from a host system, such as a
`computer. Typically, a print job is sent to the inkjet printing
`system 10 along an electronic,
`infrared, optical or other
`information transfer path. The print job includes data and
`one or more commands or command parameters. The elec-
`tronic controller 22 includes memory for temporarily storing
`the data. The electronic controller 22 provides timing control
`for firing respective inkjet nozzles 17 to define a pattern of
`ejected ink drops which form characters, symbols or other
`graphics on the media sheet M. The pattern is determined by
`the print job data and print job commands or command
`parameters.
`Upon activation of a given firing resistor 50, ink within
`the surrounding nozzle chamber 46 is ejected through the
`nozzle opening 48 onto a media sheet M. The electronic
`controller 22 selects which firing resistors 50 are active at a
`
`HP 1005
`Page 9 of 13
`
`

`
`US 6,250,738 B1
`
`5
`given time by activating corresponding drive signals to heat
`the corresponding firing resistors 50. In one embodiment
`logic circuits and drive circuits forming a portion of the
`controller 22 are mounted to the substrate 32 of the printhe ad
`assembly 12. In an alternative embodiment logic circuitry
`and drive circuitry are located olfthe printhead assembly 12.
`Referring to FIG. 2, according to a preferred embodiment
`the printhead assembly 12 includes a plurality of inkjet
`printhead dies 30 mounted to a first face 31 of a carrier
`substrate 32. An ink manifold 33 is mounted to a second face
`35 of the carrier substrate 32. Illustrated is a wide array
`inkjet printhead assembly.
`The ink manifold 33 includes one or more inlets 37 and
`one or more corresponding outlets 39 coupled to corre-
`sponding ink reservoirs l5. In one embodiment each pair of
`one inlet 37 and one outlet 39 is coupled to a corresponding
`reservoir 15. The manifold 33 includes a channel for flowing
`ink received from a given reservoir 15 at one inlet 37
`through the channel to the outlet 39 and back to the reservoir.
`Ink also flows from the manifold 33 through the carrier
`substrate 32 and into refill slots of the printhead dies 30. In
`alternative embodiments, the manifold 33 does not include
`outlets 39 for cycling ink back to the reservoir. In such case,
`ink flows into the manifold 33 from the ink reservoir 15 and
`exits through the carrier substrate 32 to the printhead dies’
`refill slots.
`The one or more reservoirs 15 are part of the ink supply
`assembly 14. The printhead assembly 12 may span a nomi-
`nal page width or a shorter or longer width, and may be of
`the scanning type, indexing type or non—moving type. In
`various embodiments, as described above, the reservoirs are
`replaceable or refillable reservoirs. In one embodiment the
`reservoirs are coupled to corresponding external reservoirs
`which supply the local reservoirs. In another embodiment
`the reservoirs are non-refillable.
`Printhead Dies
`Referring to FIG. 2, the printhead dies 30 are aligned in
`one or more rows 38 on a first surface 31 of the carrier
`substrate 32. In the embodiment illustrated dies are spaced
`apart and the rows are staggered so that the spacings are
`oifset. Each one of the printhead dies 30 includes a plurality
`of rows 42 of inkjet printing elements 44, also referred to as
`nozzles. Preferably, the respective rows of printing elements
`44 also are aligned.
`Each printhead die 30 includes an array of printing /
`elements 44. Referring to FIG. 3, each printing element 44
`includes a nozzle chamber 46 having a nozzle opening 48.
`A firing resistor 50 is located within the nozzle chamber 46.
`W'iring lines 52 electrically couple the firing resistor 50 to a
`drive signal and ground. Each printhead die 30 also includes _
`a refill channel 54. Ink flows from the internal reservoir 15
`into inlet 37 of the ink manifold 33 along path 59, through
`a manifold channel 60, out a manifold 33 feed opening 61,
`through the corresponding through—opening 63 of the carrier
`substrate 32, and into the refill channels 54 of the printhead
`dies 30. Ink flows through each printhead refill channel 54
`into the a plurality of printhead nozzle chambers 46 via
`respective ink feed channels 56.
`In one embodiment one or more of the printhead dies 30
`is a fully integrated thermal inkjet printhead formed by a
`silicon die 62, a thin film structure 64 and an orifice layer 66.
`Glass or a stable polymer are used in place of the silicon in
`alternative embodiments. The thin film structure 64 is
`formed by one or more passivation or insulation layers of
`silicon dioxide, silicon carbide, silicon nitride,
`tantalum,
`poly silicon glass; or another suitable material. The thin film
`structure also includes a conductive layer for defining the
`
`6
`firing resistor 50 and the wiring lines 52. The conductive
`layer is formed by aluminum, gold,
`tantalum,
`tantalum-
`aluminum or other metal or metal alloy.
`Detailed descriptions of the method for mounting and
`interconnecting the printhead dies 30 to the substrate 32 are
`described in the related application of Beerling et al. (Ser.
`No. 08/959,376, “Scalable Wide—Array Inkjet Printhead and
`Method for Fabricating Same,” filed on Oct. 28, 1997),
`cross-referenced above and included herein by reference.
`Carrier Substrate
`In varying embodiments, the carrier substrate 32 is made
`of silicon or a multilayered ceramic material. The carrier
`substrate 32 serves to carry the plurality of printhead dies 30,
`provide electrical interconnection among the printhead dies
`30, and provide electrical interconnection between the print-
`head dies 30 and the electronic controller 22 (see FIG. 1).
`One of the advantages of the carrier substrate is that a thin
`film layer of metal or metal pads (e.g., gold) are accurately
`sized and placed on the substrate. Such metalization allows
`for precise positioning and alignment of the printhead dies
`30.
`The carrier substrate includes through—channels or
`through-openings 63 for passing ink from the ink manifold
`33 to the printhead dies 30. For the multilayer ceramic
`embodiment the substrate 32 is formed of similar material as
`used in forming hybrid multichip modules, although other
`materials may be used.
`The ceramic substrate preferably has a coefficient of
`thermal expansion matching that of silicon, is able to receive
`solder and interconnect layers, and is able to receive mount-
`ing of integrated circuits. Referring to FIG. 4, the substrate
`32 includes a top layer 70 upon which the printhead dies 30
`are mounted, a bottom layer 72 and several intermediary
`layers 74. The intermediary layers provide electrical inter-
`_ connection and include one or more signal distribution
`layers 78, a power plane layer 80, and a ground plane layer
`82.
`Each of the ceramic layers 70-74 has a thickness ranging
`from 5—25 mils. The signal distribution layers 78 include
`circuit patterns. Conductive vias pierce the layers 78, 80, 82
`forming electrical interconnects between circuits. In one
`fabrication methodology, circuit patterns are formed in lay-
`ers of unfired tape (referred to as a green sheet) using a
`screen printing process. The green sheet is made of ceramic
`particles in a polymer binder. Alumina, although not having
`the same coellicient of thermal expansion as silicon, may be
`used for the particles, although other oxides, nitrides,
`carbides, or other ceramics various glass/ceramic blends
`also may also be used.
`Each green sheet layer receives conductor lines and other
`metallization patterns as needed to define the signal distri-
`bution planes 78, the power plane 80, and the ground plane
`82. Such lines and patterns are formed with a refractory
`metal, such as tungsten, by screen printing on the corre-
`sponding green sheet
`layer. Electrical
`interconnects are
`made from one layer to the next through via holes punched
`out from the green sheet and filled in with tungsten.
`The through openings 63 within the substrate 32 are
`formed by punching holes and cavities of desired size and
`shape through the alumina tape. Although only one through-
`opening 63 is shown for a given printhead die 30, there may
`be additional through-openings to the same printhead die to
`provide ink of respective differing colors. Once each layer
`l1as received the desired metallization, vias and openings,
`the layers are stacked in the desired configuration and
`laminated under pressure. The substrate then is shaped to a
`desired outer dimension size allotting for shrinkage during a
`
`HP 1005
`Page 10 of 13
`
`

`
`US 6,250,738 B1
`
`7
`subsequent processing. Next, the ceramic and metallization
`materials are cosintered at approximately 1600° C., creating
`a monolithic carrier substrate structure having a
`three
`dimensional wiring system. Metal parts such as 1/0 pins and
`seal rings are attached with a molten brazing process, such
`as a silver-copper eutectic brazing or a pure silver brazing.
`Exposed metal and metallization surfaces then are covered
`in a plating process, such as a nickel plating process and a
`finish plating, such as a gold plating with nickel undercoat-
`ing. The finish plating serves to hermetically seal
`the
`ceramic substrate. The top layer 70 typically is metallized in
`preparation for surface mounting the printhead dies 30. The
`bottom layer 72 is adapted to receive drive and control
`circuits and connectors 75 (see FIG. 5).
`Ink Manifold
`the ink manifold 33 includes a
`Referring to FIG. 5,
`housing 82, one or more inlets 37 and one or more outlets
`39. Each one or more pairs of an inlet 37 and an outlet 39
`are coupled to a corresponding reservoir. For example, one
`pair of an inlet 37 and an outlet 39 is coupled to a reservoir
`of cyan ink. Another pair of an inlet 37 and an outlet 39 is
`coupled to a reservoir of magenta ink. Yet another pair of an
`inlet 37 and an outlet 39 is coupled to a reservoir of yellow
`ink. The number of pairs 37/39, reservoirs I5 and colors of
`ink may vary. Illustrated is a manifold for a printhead
`assembly supporting three colors of ink. In some embodi-
`ments a fourth color ink (e .g., black) also is supported by
`including additional pathways and an inlet/outlet pair.
`FIGS. 6A—C show respective pathways through the ink
`manifold 33 for corresponding inlet/outlet pairs. Note that
`the housing is removed and that the other pathways and
`inlet/outlet pairs are omitted for illustrative clarity. FIG. 6A
`shows the pathway for one inlet/outlet pair 3751/39a. FIG. 6B
`shows the pathway for one inlet/outlet pair 37b/39b. FIG. 6C
`shows the pathway for one inlet/outlet pair 37c/39c. Refer-
`ring to FIG. 6A, ink is received at inlet 37a, then travels
`through a channel 60a. The channel 60:: extends from the
`inlet 37a to the outlet 390. Along the channel 600 are a
`plurality of fill openings 61a. Each fill opening 61a fluidly
`couples to a corresponding through—opening 63 (see FIGS.
`3 and 7) in the carrier substrate 32. In one embodiment there
`is a fill opening 61a for each printhead die 30 which is to
`print ink from the source reservoir feeding the inlet 37:1. Ink
`is cycled through the channel 600 from inlet 37a to outlet
`39a. Along the way, some ink flows out the manifold 33 /
`through the carrier substrate 32 to the printhead dies 30.
`Similarly, referring to FIG. 6B, ink is received at inlet
`37b, then travels through a channel 601). The Channel 6013
`extends from the inlet 37]) to the outlet 39b. Along the
`channel 60b are a plurality of fill openings 61b. Each fill
`opening 61b fluidly couples to a corresponding through-
`opening 63 (see FIGS. 3 and 7) in the carrier substrate 32.
`In one embodiment there is a fill opening 61b for each
`printhead die 30 which is to print ink from the source
`reservoir feeding the inlet 37b. Ink is cycled through the
`channel 6017 from inlet 37b to outlet 3917. Along the way,
`some ink flows out the manifold 33 through the carrier
`substrate 32 to the printhead dies 30.
`then
`Referring to FIG. 6C, ink is received at inlet 37c,
`travels through a channel 60c. The channel 60c extends from
`the inlet 37c to the outlet 39c. Along the channel 600 are a
`plurality of fill openings 61c. Each fill opening 6lb fluidly
`couples to a corresponding through—opening 63 (see FIGS.
`3 and 7) in the carrier substrate 32. In one embodiment there
`is a fill opening 61c for each printhead die 30 which is to
`print ink from the source reservoir feeding the inlet 37c. Ink
`is cycled through the channel 60C from inlet 37c to outlet
`
`_
`
`8
`390. Along the way, some ink flows out the manifold 33
`through the carrier substrate 32 to the printhead dies 30.
`In an embodiment each printhead die 30 includes respec-
`tive sets of nozzles for printing ink of a corresponding color.
`Such printhead dies include three ink refill slots 54cz—c, one
`for receiving ink from each of the respective manifold
`channels 60a—c. In an exemplary embodiment,
`the three
`channels 60cz—c carry ink of respective colors (e.g., cyan,
`magenta, and yellow). FIG. 7 shows a given printhead die 30
`with the three ink refill slots 54a—c receiving ink through the
`carrier substrate 32 from the ink manifold channels 60£Z—C.
`The ink manifold channels 60a—c are formed by a mold-
`ing process in one embodiment and attached to the carrier
`substrate 32 using an ink-resistant epoxy or other adhesive.
`In another embodiment the channels 60a—c are machined to
`the desired shape and assembled, then attached to the carrier
`substrate 32 using an ink-resistant epoxy or adhesive. In still
`another embodiment the channels 60cz—c are assembled and
`compressed using gaskets. The manifold 33, including the
`channels 60 are formed from plastic, metal, ceramic or
`another suitable material. Although, the embodiment of FIG.
`5 only shows the inlets 37 and outlets 39 extending from the
`housing 33, in other embodiments other portions may extend
`outside the housing. For example, in some embodiments a
`tube or other external communication channel connects a
`portion of channel 60 serving one row to another portion of
`channel 60 serving another row. Fluid interconnects are
`achieved as described in the related application of Beerling
`et al. (Ser. No. 08/959,376, “Scalable Wide-Array Inkjet
`Printhead and Method for Fabricating Same,” filed on Oct.
`28, 1997), cross-referenced above and included herein by
`reference.
`Alternative Embodiment
`Referring to FIG. 8, in an alternative embodiment the
`_ printhead dies 30 are carried by the manifold 33, rather than
`the substrate 32. An electrical signal carrier 86 embodies the
`substrate 32 or electrically connects the dies 30 the substrate
`32. In the embodiment illustrated, the signal carrier 86 is in
`the form of a mask which is mounted to the manifold 33 on
`the same side of the manifold 33 as the printhead dies 30.
`There are openings in the signal carrier 86 which allow the
`printhe ad dies 30 to be mounted in Contact with the manifold
`33. In one embodiment the dies 30 are electrically coupled
`to the signal carrier 36 by interconnection tabs 38, 90 and a
`wire bond 92, although other electrical bonding, wire bond-
`ing or TAB interconnection processes may be used.
`Meritorious and Advantageous Eflfects
`One advantage of the invention is that a manifold formed
`separate from the carrier substrate and mounted to the carrier
`substrate is that new printhead designs may be more rap