(12) United States Patent
`Boyd et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 6,322,206 B1
`Nov. 27, 2001
`
`US006322206B1
`
`MULTILAYERED PLATFORM FOR
`MULTIPLE PRINTHEAD DIES
`
`Inventors: Melissa D Boyd; Timothy E Beerling;
`Timothy L Weber, all of Corvallis, OR
`(US)
`
`Assignee: Hewlett-Packard Company, Palo Alto,
`CA (US)
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`Appl. No.: 09/216,606
`Filed:
`Dec. 17, 1998
`
`Related U.S. Application Data
`
`Continuation-in-part of application No. 08/959,376, filed on
`Oct. 28, 1997.
`
`............... .. B47] 2/175
`
`U.S. Cl.
`
`.............................................................. .. 347/85
`
`Field of Search ..................... .. 347/85, 86, 87,
`347/20, 40, 41, 71, 72
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,917,286
`5,016,023
`5,489,930 *
`5,808.635 *'
`5,939,206 *
`
`4/1990 Pollacek ............................. .. 228/110
`5/1991 Chan et al.
`.
`347/42
`2/1996 Anderson
`. 347/71
`9/1998 Kneezel et al.
`347/41
`8/1999 Kneezed et al.
`................... .. 428/480
`OTHER PUBLICATIONS
`
`.
`
`Imler, Scholz, Cobarruviaz, Nagesh, Chao, Haitz, “Precision
`Flip—Chip Solder Bump Interconnects for Optical Packag-
`ing”, IEEE Transactions on Components, Hybrids, and
`Manufacturing Tech., Vol. 15, #6, Dec. 1992, pp. 997-982.
`
`Itoh, Sasaki, Uda, Yoneda, Honmou, Fukushima, “Use of
`AuSn Solder Bumps in Three—dimensional Passive Aligned
`Packaging of LD/PD Arrays on Si Optical Benchesj’, IEEE
`Electronic Components and Technology Conference, 1996,
`pp. 1-7.
`Deshniukh, Brady, Roll, King, Shniulovic, 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.
`Ludwig, “Multilayered focal plane structures with self-
`aligning detector assembly”, Infrared Readout Electronics
`III, SPIE, vol. 2745, 1996, pp. 149—158.
`Primary Extzmirzer—Anh T. N. Vo
`
`(57)
`
`ABSTRACT
`
`An inkjet pen includes a multilayered platform and a plu-
`rality of printhead dies each mounted on the multilayered
`platform. The multflayered platform includes a first layer
`having an ink inlet defined therein, a second layer having a
`plurality of ink feed slots defined therein, and at least one
`third layer having an ink manifold defined therein. As such,
`the ink manifold of the at least one third layer fluidically
`couples the ink inlet of the first layer with the ink feed slots
`of the second layer. Each of the printhead dies are mounted
`on the second layer of the multilayered platform and include
`an array of printing elements and an ink refill slot commu-
`nicating With the array of printing elements, with each of the
`printing elements including a firing chamber and a feed
`channel communicating with the firing chamber. As such,
`the ink refill slot of each of the printhead dies communicates
`With at least one of the ink feed slots of the multilayered
`platform and the feed channel of each of the printing
`elements communicates With the ink refill slot of one of the
`printhead dies. Thus, a first of the ink feed slots ofthe second
`layer of the multilayered platform communicates with a first
`of the printhe ad dies and a second of the ink feed slots of the
`second layer of the multilayered platform communicates
`with a second of the printhead dies.
`
`20 Claims, 10 Drawing Sheets
`
`200
`
`HP 1004
`Page 1 of 18
`
`

`
`US 6,322,206 B1
`Page 2
`
`OTHER PUBLICATIONS
`
`Kallmayer, Oppermann, Kloeser, Zakel, Reichl, Experimen-
`tal Results on the Se1f—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
`Anistropically Etched Grooves”, IEEE 9th Intl. Workshop
`on MEMS, 1996, pp. 38-43.
`
`* cited by examiner
`
`HP 1004
`Page 2 of 18
`
`

`
`U.S. Patent
`
`Nov. 27, 2001
`
`Sheet 1 0f 10
`
`US 6,322,206 B1
`
`MOUNTING
`ASSEMBLY
`
`INK SUPPLY
`A33EM3Ly
`
`R
`
`RESERVOIR
`
`(15)
`
`PRINTHEAD
`ASSEMBLY
`
`ELECTRONIC
`CONTROLLER
`
`MEDIA TRANSPORT ASSEMBLY
`
`HP 1004
`Page 3 of 18
`
`

`
`U.S. Patent
`
`Nov. 27, 2001
`
`Sheet 2 0f 10
`
`US 6,322,206 B1
`
`fl_Q
`
`44
`
`‘ 4
`
`::~
`
`HP 1004
`Page 4 of 18
`
`

`
`U.S. Patent
`
`Nov. 27, 2001
`
`Sheet 3 0f 10
`
`US 6,322,206 B1
`
`44
`
`8 /
`‘1
`
`HP 1004
`Page 5 of 18
`
`

`
`U.S. Patent
`
`Nov. 27, 2001
`
`Sheet 4 0f 10
`
`US 6,322,206 B1
`
`84
`
`FIG.6
`
`<::>:<:>
`
`C>:>C>
`
`84
`
`HP 1004
`Page 6 of 18
`
`

`
`Nov. 27, 2001
`
`Sheet 5 of 10
`
`US 6,322,206 B1
`
`860
`
`202
`
`88a
`
`86b
`
`204
`
`88b
`
`86c
`
`20
`
`HP 1004
`Page 7 of 18
`
`

`
`U.S. Patent
`
`10027»2V.0N
`
`Sheet 6 of 10
`
`US 6,322,206 B1
`
`$
`
`$
`
`HP 1004
`Page 8 of 18
`
`

`
`U.S. Patent
`
`1002W2m0N
`
`Sheet7 0f10
`
`US 6,322,206 B1
`
`g
`
`......V».......
`
`Y
`
`oooooogfooooooo5—
`
`
`$H+%WHMH
`
`
`
`ooooooooooooooo.\lU
`
`ooooooooooooooo3lS
`
`8—
`
`HP 1004
`Page 9 of 18
`
`

`
`U.S. Patent
`
`10027»2V.0N
`
`Sheet 3 of 10
`
`US 6,322,206 B1
`
`m®\|\‘OOOIOOCCCCICO.
`
`OOCCCCCOOOCOCCC
`
`HP 1004
`Page 10 of 18
`
`

`
`U.S. Patent
`
`1002am2m0mm
`
`Sheet 9 of 10
`
`US 6,322,206 B1
`
`mm.\.C.OCOCCOCCCC:O
`
`
`
`..............
`
`aw?ow
`
`HP 1004
`Page 11 of 18
`
`

`
`HP 1004
`Page 12 of 18
`
`

`
`US 6,322,206 B1
`
`1
`MULTILAYEREI) PLATFORM FOR
`MULTIPLE PRINTHEAD DIES
`
`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 Beerling et al. on Oct. 28, 1997.
`BACKGROUND OF THE INVENTION
`
`This invention relates generally to inkjet printhead
`construction, and more particularly,
`to 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
`printhe ad. 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.
`
`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. Higher resolution also are being sought.
`There are scanning—type inkjet pens and non—scanning
`type inkjet pens. A scanning—type inkjet pen includes a
`printhe ad 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 printhead is 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 difficult to obtain a desired
`processing yield during fabrication. Further,
`it
`is more
`diflicult to obtain properly sized substrates of the desired
`material properties as the desired size of the substrate
`increases.
`In the related matter, 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
`
`_
`
`,
`
`,
`
`2
`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=l02).
`SUMMARY OF THE INVENTION
`
`According to the invention, a multilayer ceramic substrate
`includes many ink channels for routing ink from a reservoir
`to a plurality of printhead dies. The ceramic substrate serves
`as a carrier substrate for the dies and as an ink manifold for
`routing ink. The ceramic substrate also serves to intercon-
`nect the printhe ad dies and provide electrical signal routing.
`According to one aspect of the invention, an inkjet pen
`includes the multilayered ceramic substrate. Ink is received
`from an ink reservoir at an inlet opening. The ink flows
`through a manifold to a plurality of ink feed slots adjacent
`to corresponding printhead dies. The printhead dies are
`mounted to a first side of the carrier substrate. Each print-
`head die includes an array of printing elements and an ink
`refill slot. Each one of the plurality of printhead dies receives
`ink at the ink refill slot from the reservoir by Way of the
`carrier substrate’s ink feed slot. Ink flows from the die’s
`refill slot to the printing elements. For a recirculating ink
`system, ink leaves the manifold back toward the reservoir
`through an outlet opening.
`According to another aspect of the invention, the inkjet
`manifold is formed within the carrier substrate. Layers of the
`carrier substrate include overlapping slots which, when the
`layers are stacked, define ink channels which carry ink from
`one side of the carrier substrate (e.g., adjacent
`the ink
`reservoir) to the other side of the carrier substrate (e.g., to the
`printhead dies). The reservoir is fluidly coupled to one side
`of the carrier substrate. The printhead dies are fluidly
`coupled to the other side of the carrier substrate.
`According to another aspect of the invention, layers of the
`carrier substrate include slots which define a portion of one
`or more manifold channels and electrical wiring lines for
`interconnecting the printhead dies.
`According to another aspect of the invention, a manifold
`channel may be of various shapes, such as a large cavity or
`a serpentine channel. The ink inlet opening occurs in one
`layer of the substrate. For a recirculating system the outlet
`opening back to the reservoir also occurs in such one layer.
`The manifold channel extends through the layers of the
`substrate to a plurality of ink feed slots open in another layer
`of the substrate. The printhead dies are mounted adjacent to
`such ink feed slots in such other layer.
`the pen
`According to another aspect of the invention,
`includes multiple reservoirs, one for each color of ink.
`Separate inlet openings and manifold channels are formed in
`the carrier substrate to pass ink from a respective reservoir
`to the printhead dies. A first fluid path occurs from a first
`inlet opening to a first set of the ink feed slots and a second
`fluid path occurs from a second inlet opening to a second set
`of ink feed slots.
`
`The inkjet pen is part of a printing system which also
`includes a housing, a mounting assembly, a media transport
`assembly, and a controller. The inkjet pen is positioned at the
`mounting assembly and includes a plurality of printing
`elements. A print zone occurs adjacent to the plurality of
`printing elements 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.
`
`HP 1004
`Page 13 of 18
`
`

`
`US 6,322,206 B1
`
`3
`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 of the carrier sub-
`strate. The carrier substrate has an inlet opening coupled to
`the internal reservoir. The ink manifold fluidly connects the
`inlet opening to a plurality of ink feed slots at the carrier
`substrate. The ink feed slots are positioned adjacent to ink
`refill slots of printhead dies which are mounted to the carrier
`substrate. 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 for
`handling multiple colors of ink is formed in an unitary
`printhe ad assembly. 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.
`One aspect of the present invention provides an inkjet
`pen. The inkjet pen includes a multilayered platform and a “
`plurality of printhead dies each mounted on the multilayered
`platform. The multilayered platform includes a first layer
`having an ink inlet defined therein, a second layer having a
`plurality of ink feed slots defined therein, and at least one
`third layer having an ink manifold defined therein. As such,
`the ink manifold of the at least one third layer fiuidically
`couples the ink inlet of the first layer with the ink feed slots
`of the second layer. Each of the printhead dies are mounted
`on the second layer of the multilayered platform and include
`an array of printing elements and an ink refill slot commu-
`nicating with the array of printing elements with each of the
`printing elements including a firing chamber and a feed
`channel communicating with the firing chamber. As such,
`the ink refill slot of each of the printhead dies communicates
`with at least one of the ink feed slots of the multilayered
`platform and the feed channel of each of the printing
`elements communicates with the ink refill slot of one of the
`printhe ad dies. Thus, a first of the ink feed slots of the second
`layer of the multilayered platform communicates with a first
`of the printhead dies and a second of the ink feed slots of the
`second layer of the multilayered platform communicates
`with a second of the printhead dies.
`BRIEF DESCRIPTION OF THE 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 an inkjet pen according to
`an embodiment of this invention;
`FIG. 3 is a perspective view of a portion of an inkjet
`printhead assembly according to an embodiment of this
`invention;
`FIG. 4 is a partial cross-sectional view showing an ink
`flow path from a reservoir to an inkjet nozzle according to
`the printing system of FIG. 1;
`FIG. 5 is a diagram of multiple layers of a ceramic carrier
`substrate of FIG. 4;
`FIG. 6 is a planar view of a top layer of the ceramic
`substrate of FIG. 5;
`FIG. 7 is a planar View of a bottom layer of the ceramic
`substrate of FIG. 5;
`FIG. 8 is a planar view of a manifold layer of the ceramic
`substrate of FIG. 5;
`FIG. 9 is a planar view of a manifold layer of the ceramic
`substrate of FIG. 5 according to an alternative embodiment
`of this invention,
`
`4
`FIG. 10 is a diagram of a manifold channel and multiple
`printhead dies according to an embodiment of this invention;
`FIG. 11 is a planar view of a top layer of the ceramic
`substrate of FIG. 5 according to a 2-color embodiment of
`substrate of FIG. 4;
`FIG. 12 is a planar view of a layer of the ceramic substrate
`of FIG. 5 according to a 3-color embodiment;
`FIG. 13 is a planar view of another layer of the ceramic
`substrate of FIG. 5 according to a 3-color embodiment;
`FIG. 14 is a planar view of another layer of the ceramic
`substrate of FIG. 5 according to a 3—color embodiment;
`FIG. 15 is a planar view of another layer of the ceramic
`substrate of FIG. 5 according to a 3-color embodiment;
`FIG. 16 is a planar view of another layer of the ceramic
`substrate of FIG. 5 according to a 3-color embodiment; and
`FIG. 17 is a diagram of a 3—color inkjet pen according to
`an embodiment of this invention.
`
`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 more
`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 15 for storing the
`ink. The ink supply assembly 14 and printhead assembly 12
`form either a one—way ink delivery system or a recirculating
`ink delivery system. For the recirculating ink delivery
`system,
`ink flows from the reservoir into the printhead
`assembly. Some of the ink travels into printhead dies and
`nozzle chambers, while other portions of ink return to the
`ink reservoir.
`In some embodiments the ink supply assembly 14 and
`inkjet printhead assembly 16 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 rein-
`stalled in the pen or filled in place without removal from the
`pen (an 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
`printhead nozzles 17 in 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 18. 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
`
`HP 1004
`Page 14 of 18
`
`

`
`US 6,322,206 B1
`
`5
`transport path to scan the printhead assembly 12 relative to
`the media sheet. For a non—scanning type inkjet printhead
`assembly, the mounting assembly 16 fixes the inkjet print-
`head 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
`given time by activating correspondin g 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 printhead
`assembly 12. In an alternative embodiment logic circuitry
`and drive circuitry are located 0
`the printhead assembly 12.
`Referring to FIG. 2, according to a preferred embodiment
`the printhead assembly 12 includes a plurality of inkjet
`printhe ad dies 30 mounted to a multilayered ceramic carrier
`substrate 32. Illustrated is a pagewide array inkjet pen. The
`substrate 32 is affixed to a pen body 34. Within the pen body
`34 is a reservoir 36 which serves as, or is part of the ink
`supply assembly 14. The printhead assembly 12 may span a
`nominal page width or a shorter or longer width, and may be
`of the scanning type or non-scanning type.
`In various
`embodiments, as described above, the reservoir is a replace-
`able or refillable reservoir. In one embodiment the reservoir
`is coupled to an external reservoir which supplies the local
`reservoir.
`In another embodiment
`the reservoir is non-
`refillable.
`Referring to FIG. 3, the printhead assembly 12 may be
`formed by a plurality of printhead subassemblies 13. Each
`subassembly 13 includes a plurality of inkjet printhead dies
`30 mounted to a multilayered ceramic carrier substrate 32.
`The substrate 32 has stairstep edges 24 allowing the subas-
`semblies 13 to be mounted end to end to form the printhead
`assembly 12. Each subassembly 13 has multiple rows 38 of
`printhead dies 30. Such rows 38 are staggerred to the .
`stairstep design of the carrier substrate 32. In a preferred
`embodiment the printhead dies are spaced at a distance d.
`The printhead dies closest to the edges 24 are spaced a
`distance d/2 from the edge 24. When the carrier substrates
`are mounted end to end, continuous rows of dies 30 are ..
`formed with each die evenly spaced (e.g., at a spacing
`distance ‘d’).
`Printhead Dies
`The printhead dies 30 are aligned in one or more rows 38
`on a first surface 40 of the carrier substrate 32. Referring to
`FIG. 2, each one of the printhead dies 30 includes a plurality
`of rows 42 of inkjet printing elements 44, also referred to as
`nozzles. Each printhead die 30 includes an array of printing
`elements 44. Referring to FIG. 4, 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.
`Wiring lines 52 electrically couple the firing resistor 50 to a
`
`6
`drive signal and ground. Each printhead die 30 also includes
`a refill channel 54. Ink flows from the internal reservoir 36
`through one or more carrier substrate refill channels 60 to the
`refill channels 54 of the printhead dies 30. Ink flows through
`each printhead refill channel 54 into the printhead nozzle
`chambers 46 via 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
`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.
`Carrier Substrate
`The carrier substrate 32 in a preferred embodiment is
`made of a multilayered ceramic material, such as used in
`forming hybrid multichip modules. The substrate 32 pref-
`erably has a coefiicient of thermal expansion approximating
`that of silicon, is able to receive solder and interconnect
`layers, and is able to receive mounting of integrated circuits.
`Referring to FIG. 5, the substrate 32 includes a top layer 70
`upon wl1icl1 the printhead dies 30 are mounted, a bottom
`layer 72 upon which an integrated circuit 79 may be
`mounted, and several intermediary layers 73. The interme-
`diary layers 73 may be allocated into one set 74 for electrical
`interconnection and another set 76 for ink manifold distri-
`bution. The electrical interconnection layers include one or
`more signal distribution layers 78, a power plane layer 80,
`and a ground plane layer 82 as well as interconnection to the
`printheads and integrated circuits. Even the electrical inter-
`connection layers, however, may include slots for allowing
`ink to move vertically from one layer to another.
`In a preferred embodiment, electrical
`interconnection
`layers and manifold layers are embodied in common layers.
`Thus, many of the intermediary layers 73 serve to provide
`wiring lines and to define portions of one or more ink
`manifold channels. The ink manifold channels 60 (see FIG.
`4) receive ink from the reservoir 36. The ink flows through
`the manifold channels to respective slots 54 (see FIG. 4) for
`each printhead die 30. For multi-colored printhead
`assemblies, there are isolated manifold channels for each ink
`color and separate output slots for dies receiving a respective
`color.
`Each of the ceramic layers 70-73 has a thickness ranging
`from 0.004 inches to 0.030 inches. The layers 73 which
`include circuit patterns include condu ctive vias which pierce
`the layers 73 to form electrical interconnects between cir-
`cuits. In one fabrication methodology, circuit patterns are
`formed in layers 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 preferably is
`used for the particles, although other oxides or various
`glass/ceramic blends also may be used. The green tape has
`the texture of flexible vinyl.
`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, for example, with a
`tungsten paste.
`
`HP 1004
`Page 15 of 18
`
`

`
`US 6,322,206 B1
`
`7
`The ink channels 60 are formed by punching holes and
`cavities of desired size and shape through the alumina tape.
`Once each layer has received the desired metallization, vias
`and openings, the layers 70-73 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 subsequent processing. Next, the ceramic
`and metallization materials are cosintered at approximately
`1600° C., creating a monolithic structure having a three
`dimensional wiring system and internal ink manifold. Metal
`parts such as I/O 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 metal-
`lization 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 undercoating. The finish plating provides
`a surface which may receive solder or wire bonding material
`allowing electrical connections to the substrate 32. The top
`layer 70 typically is metallized in preparation for surface
`mounting the printhead dies 30.
`Embodiments of the ink manifold now are described with
`respect to FIGS. 6-17. FIGS. 6-9 refer to a single color ink
`manifold. The top layer 70 of the ceramic substrate 32
`includes an ink feed slot 84 for each printhead die 30.
`Referring to FIG. 7, the bottom layer 72 includes at least one
`inlet opening 86 for receiving ink from the reservoir 36. In
`some embodiments the ink cycles through the substrate 32
`back to the reservoir 36. In such an embodiment the bottom
`layer 72 also includes at least one outlet opening 88. For a
`non-cycling embodiment there is no need for an ink outlet
`opening at the bottom layer 72. The flow path for the ink
`through the substrate 32 between the top layer 70 and bottom
`layer 72 is defined primarily by the set of layers 73.
`In one embodiment, a large cavity 90 as shown in FIG. 8
`serves as the manifold for fluidly coupling the inlet openings
`86 to the outlet opening 88 and the ink slots 84. In another
`embodiment a serpentine path 92 as shown in FIG. 9 serves
`as the manifold for fluidly coupling the inlet openings 86 to
`the outlet opening 88 and the ink slots 84. It is desired that
`the flow path 90 or 92 minimize flow resistance, avoid
`bubble traps and achieve a desired ink flow rate. The cavity
`90 or the serpentine path 92 may be formed in one or more
`layers 73. Vertical openings are formed in the intervening
`layers to complete a channel from the top layer 70 to the
`bottom layer 72.
`the manifold channels 60 are
`In another embodiment,
`formed by slots in the various layers 73. When the layers 73
`are stacked a three-dimensional channel 60 is formed having
`a desired shape and path. A given layer 73 may include ink
`slots along with electircal interconnection vias or wiring _
`lines. FIG. 10 shows an exemplary manifold channel 60. For
`purposes of illustration the channel 60 is shown without the
`defining walls of the forming layers 73. Ink [lows from an
`inlet opening 86 through the channel 60 to a return outlet
`opening 88 and to several ink feed slots 84 adjacent respec-
`tive printhead dies 30. In the embodiment illustrated there
`are two major trunks 61, 63 of the manifold channel 60. One
`trunk feeds the other. Each trunk 61, 63 serves one or more
`rows 38 of printhead dies 30. Subchannels 65 extend to and
`from a trunk to a corresponding feed slot 84.
`For printhe ad dies 30 which concurrently handle multiple
`colors of ink, there are separate slots in the die 30 for each
`color of ink. Such slot is connected to inkjet nozzles which
`eject ink of the same color, and is isolated from nozzles
`which eject ink of different color. For such an embodiment
`the ceramic substrate 32 includes corresponding slots 84 in
`the top layer 70. FIG. 11 shows an embodiment of a top layer
`
`.
`
`.
`
`8
`70' with slots 84', 84" for each die 30. Slot 84' handles ink
`of one color. Slot 84" handles ink of another color. The
`bottom layer includes an inlet opening and an outlet opening
`for each color ink (in similar manner as shown for a single
`color ink system in FIG. 7). The inlet opening and outlet
`opening for a given color are coupled to a reservoir of ink
`for such color.
`FIGS. 12-16 show respective layers forming a substrate
`32 for a three oolor printing system. Referring to FIG. 12,
`layer 72 includes three respective inlet openings 86a-c, one
`for each color of ink and three respective outlet openings
`88:1-c, one for each color of ink. Also shown are a plurality
`of vias 89 for electrical interconnection. Referring to FIG.
`13, a layer 73a for being mounted adjacent to layer 72,
`includes a plurality of slots 100-111 and the vias 89.
`Referring to FIG. 14, a layer 73b for being mounted adjacent
`to layer 73:1 opposite layer 72), includes a plurality of slots
`112-135, the vias 89 and several wiring lines 136. Referring
`to FIG. 15, a layer 73c for being mounted adjacent to layer
`73b (opposite layer 73(1),
`includes a plurality of slots
`137-166, the vias 89 and several wiring lines 167. Referring
`to FIG. 16, a layer 70 for being mounted adjacent to layer
`73c (opposite layer 7317), includes a plurality of slots 84',
`84", and 84'", the vias 89 and several wiring lines 168. Each
`slot 84‘ corresponds to a feed slot for feeding one color of
`ink. Each slot 84" corresponds to a feed slot for feeding a
`second color of ink. Each slot 84“' corresponds to a feed slot
`for feeding a third color of ink. The slots 84 are arranged in
`groups of three slots 84', 84" and 84"‘. A given printhead die
`30 is mounted to fluidly couple to a corresponding group of
`three slots for a die 30 which prints three colors of ink. When
`these layers 70, 73a-C and 72 are stacked in the order
`presented, one channel is formed which connects inlet 86a
`to feed slots 84' and outlet 88a. An independent channel is
`formed which connects inlet 86]) to feed slots 84" and outlet
`88b. A third channel is formed which connects in