Title of Invention

METHOD OF BONDING SUBSTRATES

Abstract

A method of bonding a first substrate to a second substrate is provided. The method comprises the steps of: (a) providing a first substrate having a plurality of etched trenches defined in a first bonding surface; (b) providing a second substrate having a second bonding surface; and (c) bonding the first bonding surface and the second bonding surface together using an adhesive. During bonding, the adhesive is received, at least partially, in the plurality of etched trenches, thereby increasing the adhesive bond strength whilst avoiding surface roughening. The method is particularly suitable for bonding semiconductor chips using liquid adhesives.

Full Text

METHOD OF BONDING SUBSTRATES ■ Field of the Invention This invention relates to a method of bonding substrates together, and a substrate adapted therefore. It has been developed primarily for maximizing bonding of microscale substrates to other substrates, whilst avoiding traditional surface abrasion techniques. Cross References to Related Applications The following patents or patent applications filed by the applicant or assignee of the present invention are hereby incorporated by cross-reference. 6795215 10/884881 PECOINP 09/575109 10/296535 09/575110 6805419 09/607985 6398332 6394573 6622923 6747760 10/189459 10/943941 10/949294 10/727181 10/727162 10/727163 10/727245 10/727204 10/727233 10/727280 10/727157 10/727178 10/727210 10/727257 ' 10/727238 10/727251 10/727159 10/727180 10/727179 10/727192 10/727274 10/727164 10/727161 10/727198 10/727158 10/754536 10/754938 10/727227 10/727160 10/934720 10/854521 10/854522 10/854488 10/854487 10/854503 10/854504 10/854509 10/854510 10/854496 10/854497 10/854495 10/854498 10/854511 10/854512 10/854525 10/854526 10/854516 10/854508 10/854507 10/854515 10/854506 10/854505 10/854493 10/854494 10/85489 10/854490 10/854492 10/854491 10/854528 10/854523 10/854527 10/854524 10/854520 10/854514 10/854519 PLT036US 10/854499 10/854501 10/854500 10/854502 10/854518 10/854517 PLT043US 10/728804 10/728952 10/728806 10/728834 10/729790 10/728884 10/728970 10/728784 10/728783 10/728925 10/728842 10/728803 10/728780 10/728779 10/773189 10/773204 10/773198 10/773199 10/773190 10/773201 10/773191 10/773183 10/773195 10/773196 10/773186 10/773200 10/773185 10/773192 10/773197 10/773203 10/773187 10/773202 10/773188 10/773194 10/773193 10/773184 10/760272 10/760273 10/760187 10/760182 10/760188 10/760218 10/760217 10/760216 10/760233 10/760246 10/760212 10/760243 10/760201 10/760185 10/760253 10/760255 10/760209 10/760208 10/760194 10/760238 10/760234 10/760235 10/760183 10/760189 10/760262 10/760232 10/760231 10/760200 10/760190 10/760191 10/760227 10/760207 10/760181 6746105 6623101 6406129 6505916 6457809 6550895 6457812 6428133 U52NP 10/407212 10/407207 10/683064 10/683041 10/882774 10/884889 10/922890 JUM008US 10/922885 10/922889 10/922884 10/922879 10/922887 10/922888 10/922874 10/922873 10/922871 10/922880 10/922881 10/922882 10/922883 10/922878 JUM023US 10/922876 10/922886 10/922877 10/815625 10/815624 10/815628 10/913375 10/913373 10/913374 10/913372 10/913377 10/913378 10/913380 10/913379 10/913376 10/913381 10/986402 09/575187 6727996 6591884 6439706 6760119 09/575198 09/722148 09/722146 09/721861 6290349 6428155 6785016 09/608920 09/721892 09/722171 09/721858 09/722142 10/171987 10/202021 10/291724 10/291512 10/291554 10/659027 10/659026 10/831242 10/884885 10/884883 10/901154 10/932044 10/962412 10/962510 10/962552 10/965733 10/965933 10/974742 10/986375 10/659027 09/693301 09/575197 09/575195 09/575159 09/575132 09/575123 09/575148 09/575130 09/575165 6813039 09/575118 09/575131 09/575116 6816274 09/575139 09/575186 6681045 6728000 09/575145 09/575192 09/575181 09/575193 09/575183 6789194 09/575150 6789191 6549935 09/575174 09/575163 6737591 09/575154 09/575129 09/575124 09/575188 09/575189 09/575170 09/575171 09/575161 6644642 6502614 6622999 6669385 11/003786 11/003354 CAA003US 11/003418 11/003334 CAA006US 11/003404 11/003419 11/003700 CAAOIOUS CAAOllUS CAA012US 11/003337 CAA014US 11/003420 CAA016US CAA017US 11/003463 CACOOIUS 11/003683 CAEOOIUS 11/003702 11/003684 CAF003US CAF004US 10/760254 10/760210 10/760202 10/760197 10/760198 10/760249 10/760263 10/760196 10/760247 10/760223 10/760264 10/760244 10/760245 10/760222 10/760248 10/760236 10/760192 10/760203 10/760204 10/760205 10/760206 10/760267 10/760270 10/760259 10/760271 10/760275 10/760274 10/760268 10/760184 10/760195 10/760186 10/760261 10/760258 RRBOOIUS RRB002US RRB003US RRB004US RRB005US RRB006US RRB007US RRB008US RRB009US RRBOIOUS RRBOllUS RRB012US RRB013US REB014US RRB015US KRB016US RRB017US RRB018US RRB019US RRB020US RRB021US RRB022US RRB023US RRB024US RJRB025US RRB026US RRB027US RRB030US RRB031US RRB032US. RRB033US RRCOOIUS RRC002US KRC003US RRC004US RRC005US RRC006US RRC007US RRC008US RRC009US RRCOIOUS RRCOllUS RRC012US RRC013US RRC014US KRCO15US RRC016U^S RRCO17US RRCO18US RE.CO 19US RRC020US RRC021 US Some applications have been listed by docket numbers. These will be replaced when application numbers are known. Background of the Invention It is well known that surfaces bond better using liquid adhesives if the surfaces are first roughened. Surface roughening increases the surface area available for bonding to the liquid adhesive, which significantly increases the adhesive bond strength. Typically, surface roughening is achieved by abrading either or both of the surfaces to be bonded. For example, simply abrading one of the surfaces with emery cloth can achieve significant improvements in adhesive strength when compared with non-abraded surfaces. However, when bonding microscale substrates, such as semiconductor integrated circuits ("chips"), it is generally not desirable to abrade a surface of the substrate. Indeed, it is highly desirable for semiconductor chips to have very smooth surfeces. Any defects on the surface of the integrated circuit can result in crack propagation and significantly weaken the device. With a drive towards thinner and thinner integrated circuits (e.g. less than 200 micron ICs), there is a corresponding need to reduce surface roughness, in order to maintain acceptable mechanical strength in devices. With surface roughness being of primary importance, silicon wafers are typically thinned using a two-step process. After front-end processing of the wafer, the wafer is usually first thinned by backgrinding in a mechanical grinding tool. Examples of wafer grinding tools are the Strasbaugh 7AF and Disco DFG-841 tools. Mechanical grinding is a quick and inexpensive method of grinding silicon. However, it also leaves a back surface having a relatively high surface roughness (e.g. Rmax of about 150 nm). Moreover, mechanical grinding can result in defects (e.g. cracks or dislocations), which extend up to about 20 μm into the back surface of the wafer. La terms of mechanical strength, surface roughness and surface defects are unacceptable in integrated circuits. Accordingly, back-end thinning is typically completed by a technique, which removes these defects and provides a low surface roughness. Plasma thinning is one method used for completing wafer thinning. Typically, plasma thinning is used to remove a final 20 μm. of silicon to achieve a desired wafer thickness. Whilst plasma thinning is relatively slow, it results in an extremely smooth back surface with virtually no surfece defects. Typically, plasma thinning provides a maximum surface roughness (Rmax) of less than 1 nm. Hence, plasma thinning is a method of choice for back-end processing in integrated circuit fabrication Integrated circuits, such as KIEMS de\ices, often need to be bonded to other substrates. In the fabrication of the Applicant's MEMS printheads, for example, printhead integrated circuits bonded side-by-side onto a moulded ink manifoid to form a printhead assembly. (For a detailed description of the Applicant's printhead fabrication process, see the Detailed Description below and US Patent Application no. 10/728,970, the contents of which is incorporated herein by cross-reference). However, it will be appreciated that integrated circuits have contradictory requirements of their backside surfaces. On the one hand, the backside surfaces of integrated circuits should have a low surface roughness and be devoid of any cracks, in order to maximize their mechanical strength. This is especially important for thin (e.g. less than 250μm integrated circuits). On the other hand, the backside surfaces of integrated circuits often need to be suitable for bonding to other substrates using adhesives or adhesive tape. As discussed above, adhesive strength is usually maximized by increasing the surface roughness of a surface to be bonded, thereby maximizing contact with the intermediate adhesive. It would be desirable to provide an improved method of bonding substrates using adhesives, which avoids increasing the surface roughness of the substrate. It would also be desirable to provide a thin substrate (e.g. Summary of the Invention In a first aspect, there is provided a method of bonding a first substrate to a second substrate, the method comprising the steps of: (a) providing a first substrate having a plurality of etched trenches defined in a first bonding surfece; (b) providing a second substrate having a second bonding surface; and (c) bonding the first bonding surface and the second bonding surface together using an adhesive, wherein the adhesive is received, at least partially, in the plurality of etched trenches during bonding. In a second aspect, there is provided a first substrate suitable for bonding to a second substrate using an adhesive, said first substrate having a plurality of etched trenches defined in a first bonding surface, the etched trenches being configured for receiving the adhesive during bondiag. In a third aspect, there is provided a bonded assembly comprising: (a) a first substrate having a plurality of etched trenches defined in a first bonding surface; (b) a second substrate having a second bonding surface; and (c) an adhesive bonding the first bonding surface and the second bonding surface together, whereiQ the adhesive is sandwiched between the first and second substrates, and is received in the plurahty of etched trenches. In a fourth aspect, there is provided a printhead assembly comprising: (a) a plurality of printhead integrated circuits, each printhead integrated circuit comprising: a plurality of nozzles formed on a firontside of the printhead integrated circuit; a plurality of ink supply channels for supplying ink from a backside of the printhead integrated circuit to the nozzles; and a plurality of etched trenches defined in the backside; and (b) an ink manifold having a mounting surface, the backside of each printhead integrated circuit being bonded to the mounting surface with an adhesive, wherein the adhesive is received, at least partially, in the plurality of etched trenches. la a fifth aspect, there is provided a printhead integrated circuit suitable for bonding to a mounting surface of an ink manifold using an adhesive, said printhead integrated circuit comprising: a plurality of nozzles formed on a firontside of the printhead integrated circuit; a plurality of ink supply channels for supplying ink from a backside of the printhead integrated circuit to the nozzles; and a plurality of etched trenches defined in the backside, the etched trenches being configured for receiving the adhesive during bonding. Hitherto, surface roughening was the only method used for improving the surface characteristics of substrates to be bonded. However, as explained above, surface roughening is Altematively, the first boadiag surface may have an average surface roughness (Re) of less than 20 nm, optionally an Ra of less than 5 run, or optionally an R of less than 1 nm. The adhesive is typically a liquid-based adhesive, or an adhesive which becomes liquid when heated for bonding. Optionally, the adhesive is an adhesive tape comprising an adhesive on one or both sides. Double-sided adhesive fihns or tapes are well known in the semiconductor art. Optionally, the first substrate cools during the bonding process. This is usually achieved by heating the first substrate (which may also melt the adhesive), and then allowing it to cool whilst bonding to the second substrate. An advantage of this option is that a partial vacuum is created in the trenches, above the adhesive, which helps to hold the substrates together during bonding. In a further aspect there is provided method wherein the first is substrate suitable for bonding to a second substrate using an adhesive, said first substrate having a plurality of etched trenches defined in a first bonding surface, the etched trenches being configured for receiving the adhesive during bonding. In another aspect there is provided a bonded assembly comprising: (a) a first substrate having a plurality of etched trenches defined in a first bonding surface; and (b) a second substrate having a second bonding surface, the second bonding surface being bonded to the first bonding surface with an adhesive, wherem the adhesive is received, at least partially, in the plurality of etched trenches. In another aspect there is provided a printhead assembly comprising: (a) a plurality of printhead integrated circuits, each printhead integrated circuit comprising: a plurality of nozzles formed on a frontside of the printhead integrated circuit; a plurality of ink supply channels for supplying ink from a backside of the printhead integrated circuit to the nozzes; and a plurality of etched trenches defined in the backside; and (b) an ink manifold having a mounting surface, the backside of each printhead mtegrated circuit being bonded to the mounting surface with an adhesive, wherein the adhesive is received, at least partially, in the plurality of etched trenches. In a further aspect there is provided a printhead integrated circuit suitable for bonding to a mounting surface of an ink manifold using an adhesive, said printhead integrated circuit compising: a plurality of nozzles formed on a frontside of the printhead integrated circuit; a plurality of ink supply channels for supplying ink from a backside of the printhead integrated circuit to the nozzles; and a plurality of etched trenches defined in the backside, the etched trenches being configured for receiving the adhesive during bonding. In another aspect there is provided a method of bonding a first substrate to a second substrate, the method comprising the steps of: (a) providing a first substrate having a plurality of etched trenches defined in a first bonding surface; (b) providing a second substrate having a second bonding surface; and (c) bonding the first bonding surface and the second bonding surface together using an adhesive, wherein the adhesive is received, at least partially, in the plurality of etched trenches during bonding. In another aspect there is provided a bonded assembly comprising: (a) a first substrate having a plurality of etched trenches defined in a first bonding surface; and (b) a second substrate having a second bonding surface, the second bonding surface being bonded to the first bonding surface with an adhesive, wherein the adhesive is received, at least partially, in the plurality of etched trenches. In a further aspect there is provided a method of bonding a first substrate to a second substrate comprising the steps of: (a) providing a first substrate having a plurality of etched trenches defined in a first bonding surface; (b) providing a second substrate having a second bonding surface; and (c) bonding the first bonding surface and the second bonding surface together using an adhesive, wherein the adhesive is received, at least partially, in the plurality of etched trenches during bonding. In another aspect there is provided a first substrate suitable for bonding to a second substrate using an adhesive, said fust substrate having a pluralits' of etched trenches defined in a first bonding surface, the etched trenches being configured for receiving the adhesive during bonding. In a further aspect there is provided a method of bonding a first substrate to a second substrate, the method comprising the steps of: (a) providing a first substrate having a plurality of etched trenches defined in a first bonding surface; (b) providing a second substrate having a second bonding surface; and (c) bonding the first bonding surface and the second bonding surface together using an adhesive, wherein the adhesive is received, at least partially, in the plurality of etched trenches during bonding. In a further aspect there is provided a first substrate suitable for bonding to a second substrate using an adhesive, said first substrate having a plurality of etched trenches defined in a first bonding surface, the etched trenches being configured for receiving the adhesive during bondiog. In another aspect there is provided a bonded assembly comprising: (a) a first substrate having a plurality of etched trenches defined in a first bonding surface; and (b) a second substrate haviag a second bonding surface, the second bonding surface being bonded to the first bonding surface with an adhesive, wherein the adhesive is received, at least partially, in the plurality of etched trenches. In a further as[ect there is provided a printhead integrated circuit suitable for bonding to a mounting surface of an ink manifold using an adhesive, said printhead integrated circuit comprising: a plurality of nozzles formed on a frontside of the printhead integrated circuit; a plurality of ink supply channels for supplying ink from a backside of the printhead mtegrated circuit to the nozzles; and a plurality of etched trenches defined in the backside, the etched trenches being configured for receiving the adhesive during bonding. Li further aspect there is provided a method of bonding a first substrate to a second substrate, the method comprising the steps of: (a) proomg a printthead integrated circuit accordmg to claim 1; (b) providing a second substrate having a second bonding surface; and (c) bonding the first bonding surface and the second bonding surface together using an adhesive, wherein the adhesive is received, at least partially, in the plurality of etched trenches during bonding. In another aspect there is provided a first substrate suitable for bonding to a second substrate using an adhesive, said first substrate having a plurality of etched trenches defined in a first bonding surface, the etched trenches being configured for receiving the adhesive during bonding; and wherein the first substrate is a printhead integrated circuit according to claim 1. In a further aspect there is provided a bonded assembly comprising: (a) a printhead integrated circuit according to claim 1; and (b) a second substrate having a second bonding surface, the second bonding surface being bonded to the first bonding surface with an adhesive, wherein the adhesive is received, at least partially, in the plurality of etched trenches. In another aspect there is provided a printhead assembly comprising: (a) a plurality of printhead integrated circuits, each printhead integrated circuit comprising: a plurality of nozzles formed on a frontside of the printhead integrated circuit; a plurality of ink supply channels for supplying ink firom a backside of the printhead integrated circuit to the nozzles; and a plurality of etched trenches defined in the backside and each printhead integrated circuit being in accordance with claim 1; and (b) an ink manifold having a mounting surface, the backside of each printhead integrated circuit being bonded to the mounting surface with an adhesive, wher inthe adhesive is received, at least partially, in the plurality of etched trenches. Brief Description of the Drawings Fig. 1 shows a front perspective view of a printer with paper in the input tray and the collection tray extended; Fig. 2 shows the printer unit of Fig. i (without paper in the input tray and with the collection tray retracted) with the casing open to expose the interior; Fig. 3 shows a perspective view of a cradle unit with open cover assembly and cartridge unit removed therefrom; Fig. 4 shows the cradle unit of Fig. 3 with the cover assembly in its closed position; Fig. 5 shows a front perspective view of the cartridge unit of Fig, 3: Fig. 6 shows an exploded perspective view of the cartridge unit of Fig. 5; Fig. 7 shows a top perspective view of the prinfhead assembly shown in Fig. 6; Fig. 8 shows an exploded view of the prinfhead assembly shown in Fig. 7; Fig. 9 shows an inverted exploded view of the printhead assembly shown in Fig. 7; Fig. 10 shows a cross-sectional end view of the printhead assembly of Fig. 7; Fig. 11 shows a magnified partial perspective view of the drop triangle end of a printhead integrated circuit module as shown in Figs. 8 to 10; Fig. 12 shows a magnified perspective view of the join between two printhead integrated circuit modules shown in Figs, 8 to 11; Fig. 13 shows an underside view of the printhead integrated circuit shown in Fig. 11; Fig. 14 shows a perspective transverse sectional view of an ink supply channel shown in Fig. 13; Fig. 15A shows a transparent top view of a printhead assembly of Fig.7 showing in particular, the ink conduits for supplying ink to the printhead integrated circuits; Fig. 15B is a partial enlargement of Fig. 15A; Fig. 16 shows a vertical sectional view of a single nozzle for ejecting ink, for use with the invention, in a quiescent state; Fig. 17 shows a vertical sectional view of the nozzle of Fig. 16 during an initial actuation phase; Fig. 18 shows a vertical sectional view of the nozzle of Fig. 17 later in the actuation phase; Fig. 19 shows a perspective partial vertical sectional view of the nozzle of Fig. 16, at the actuation state shown in Fig. 18; Fig. 20 shows a perspective vertical section of the nozzle of Fig. 16, with ink omitted; Fig, 2rshows a vertical sectional view of the of the nozzle of Fig. 20; Fig. 22 shows a perspective partial vertical sectional view of the nozzle of Fig. 16, at the actuation state shown in Fig. 17; Fig. 23 shows a plan view of the nozzle of Fig. 16; Fig. 24 shows a plan view of the nozzle of Fig. 16 with the lever arm and movable nozzle removed for clarity; Fig. 25 shows a perspective vertical sectional view of a part of a printhead chip incorporating a plurality of the nozzle arrangements of the type shown in Fig. 16; Fig. 26 shows a schematic cross-sectional view through an ink chamber of a single nozzle for injecting ink of a bubble forming heater element actuator type. Figs. 27 A to 27C show the basic operational principles of a thennal bend actuator; Fig. 28 shows a three dimensional view of a single Inkjet nozzle arrangement constructed in accordance with Fig. 27; and Fig. 29 shows an array of the nozzle arrangements shown in Fig. 28. Detailed Description of a Specific Embodiment A specific form of the invention is described below in the context of fabricating a printhead assembly for an inkjet printer. However, it will be appreciated that the invention may be used in coimection with bonding any two substrates together and is not in any way limited to the specific embodiment of printhead fabrication. Inkjet Printer Unit Fig. 1 shows a printer unit 2 comprising a media supply tray 3, which supports and supplies media 8 to be printed by the print engine (concealed within the printer casing). Printed sheets of media 8 are fed from the print engine to a media output tray 4 for collection. User interface 5 is an LCD touch screen and enables a user to control the operation of the printer unit 2. Fig. 2 shows the lid 7 of the printer unit 2 open to expose the print engine 1 positioned in the internal cavity 6. Picker mechanism 9 engages the media in the input tray 3 (not shown for clarity) and feeds individual streets to the print engine 1. The print engine 1 includes media transport means that takes the individual sheets and feeds them past a printhead assembly (described below) for printing and subsequent delivery to the media output tray 4 (shown rietracted). Print Engine Tbe print engine 1 is shown in detail in Figs. 3 and 4 and consists of two main parts: a cartridge unit 10 and a cradle unit 12. The cartridge unit 10 is shaped and sized to be received within the cradle unit 12 and secured in position by a cover assembly 11 mounted to the cradle unit. The cradle unit 12 is in turn configured to be fixed within the printer unit 2 to facilitate printing as discussed above. Fig. 4 shows the print engine 1 in its assembled form with cartridge unit 10 secured in the cradle unit 12 and cover assembly 11 closed. The print engine 1 controls various aspects associated with printing in response to user irsputs from the user interface 5 of the printer unit 2. These aspects include transporting the media past the printhead in a controlled manner and the controlled ejection of ink onto the surface of the passing media. Cartridge unit The cartridge unit 10 is shown in detail in Figs. 5 and 6. With reference to the exploded view of Fig, 6, the cartridge unit 10 generally consists of a main body 20, an ink storage module assembly 21, a printhead assembly 22 and a maintenance assembly 23. Each of these parts are assembled together to form an integral unit which combines ink storage means together with the ink ejection means. Such an arrangement ensures that the ink is directly supplied to the printhead assembly 22 for printing, as required, and should there be a need to replace either or both of the ink storage or the printhead assembly, this can be readily done by replacing the entire cartridge unit 10. However, the operating life of the printhead is not limited by the supply of ink. The top surface 42 of the cartridge unit 10 has interfaces 61 for docking with a refill supply of ink to replenish the ink storage modules 45 when necessary. To further extend the life of the printhead, the cartridge unit carries an integral printhead maintenance assembly 23 that caps, wipes and moistens the printhead Printhead Assemblv The printhead assembly 22 is shown in more detail in Figs. 7 to 10, and is adapted to be attached to the underside of the main body 20 to receive ink from the outlets molding 27. The printhead assembly 22 generally comprises an elongate upper member 62 which is configured to extend beneath the main body 20, between the posts 26. A plurality of U-shaped clips 63 project from the upper member 62. These pass through the recesses 37 provided in the rigid plate 34 and become captured by lugs (not shown) formed in the main body 20 to secure the printhead Assembly 22. The upper element 62 has a plurality of feed tubes 64 that are received within the outlets in the outlet molding 27 when the printhead assembly 22 secures to the main body 20. The feed tubes 64 may be provided with an outer coating to guard against ink leakage. The upper member 62 is made from a liquid crystal polymer (LCF) which offers a number of advantages. It can be molded so that its coefficient of thermal expansion (CTE) is similar to that of silicon. It will be appreciated that any significant difference in the CTE's of the printhead integrated circuit 74 (discussed below) and the underlying moldings can cause the entire structure to bow. However, as the CTE of LCP in the mold direction is much less than that in the non- mold direction (~5ppmy°C compared to -20ppm/oC), care must be take to ensure that the m.old direction of the LCP moldings is unidhrectional with the longitudinal extent of the printhead integrated circuit (IC) 74. LCP also has a relatively high stif&ess with a modulus that is typically 5 times that of 'normal plastics' such as polycarbonates, styrene. nylon, PET and polypropylene. As best shown in Fig. 8, upper member 62 has an open channel configuration for receiving a lower member 65, which is bonded thereto, via an adhesive film 66. The lower member 65 is also made from an LCP and has a plurality of ink channels 67 formed along its length. Each of the ink channels 67 receive ink from one of the feed tubes 64, and distribute the ink along the length of the printhead assembly 22. The channels are 1 mm wide and separated by 0.75 mm thick walls. In the embodiment shown, the lower member 65 has five channels 67 extending along its length. Each channel 67 receives ink from only one of the five feed tubes 64, which in turn receives ink from one of the ink storage modules 45 (see Fig. 9) to reduce the risk of mixing different coloured inks. In this regard, adhesive film 66 also acts to seal the individual ink channels 67 to prevent cross channel mixing of the ink when the lower member 65 is assembled to the upper member 62. In the bottom of each channel 67 are a series of equi-spaced holes 69 (best seen in Fig. 9) to give five rows of holes 69 in the bottom surface of the lower member 65. The middle row of holes 69 extends along the centre-line of the lower member 65, directly above the printhead IC 74. As best seen in Fig. 15, other rows of holes 69 on either side of the middle row need conduits 70 from each hole 69 to the centre so that mk can be fed to the printhead IC 74. Referring to Fig. 10, the printhead IC 74 is mounted to the underside of the lower member 65 by a polymer sealing film 71. This film may be a thennoplastic film such as a PET or Polysulphone film, or it may be in the form of a thermoset film, such as those manufactured by AL technologies and Rogers Corporation. The polymer sealing film 71 is a laminate with adhesive layer on both sides of a central film, and laminated onto the imderside of the lower member 65. As shown in Figs. 9,14 and 15, a plurality of holes 72 are laser drilled through the adhesive film 71 to coincide with the centrally disposed ink delivery points (the middle row of holes 69 and the ends of the conduits 70) for fluid communication between the printhead IC 74 and the channels 67. The thickness of the polymer sealing film 71 is critical to the effectiveness of the ink seal it provides. As best seen in Figs. 13 and 15, the polymer sealing film seals the etched channels 77 on the reverse side of the printhead IC 74, as well as the conduits 70 on the other side of the film. requirements are less critical, shapes other than a triangle can be used, for example, the dropped rows may take the form of a trapezoid. The upper surface of the printhead ICs have a number of bond pads 75 provided along an edge thereof which provide a means for receiving data and or power to control the operation of the nozzles 73 from the SoPEC device., To aid in positioning the ICs 74 correctly on the surface of the adhesive layer 71 and aligning the ICs 74 such that they correctly align with the holes 72 formed in the adhesive layer 71, fiducials 76 are also provided on the surface of the ICs 74. The fiducials 76 are in the form of markers that are readily identifiable by appropriate positioning equipment to indicate the true position of the IC 74 with respect to a neighbouring IC and the surface of the adhesive layer 71, and axe strategically positioned at the edges of the ICs 74, and along the length of the adhesive layer 71. In order to receive the ink from the holes 72 formed in the polymer sealing film 71 and to distribute the ink to the ink inlets 73, the underside of each printhead IC 74 is configured as shown in Fig 13. A number of etched channels 77 are provided, with each channel 77 in fluid communication with a pair of rows of inlets 73 dedicated to delivering one particular colour or type of ink. The channels 77 are about 80 microns wide, which is equivalent to the width of the holes 72 in the polymer sealing film 71, and extend the length of the IC 74. The channels 77 are divided into sections by silicon walls 78. Each sections is directly supplied with ink, to reduce the flow path to the inlets 73 and the likelihood of ink starvation to the individual nozzles 801. In this regard, each section feeds approximately 128 nozzles 801 via their respective inlets 73. Fig. 15B shows more clearly how the ink is fed to the etched channels 77 formed in the underside of the ICs 74 for supply to the nozzles 73. As shown, holes 72 formed through the polymer sealing film 71 are aligned with one of the channels 77 at the point where the silicon wall 78 separates the channel 77 into sections. The holes 72 are about 80 microns in width which is substantially the same width of the channels 77 such that one hole 72 supplies ink to two sections of the channel 77. It will be apredated that this halves the density of holes 72 required in the polymer sealing film 71. Following attachment and alignment of each of the printhead ICs 74 to the surface of the polymer sealing film 71, a flex PCB 79 (see Fig. 18) is attached along an edge of the ICs 74 so that control signals and power can be supplied to the bond pads 75 to control and operate the nozzles 801. As shown more clearly in Fig. 15, the flex PCB 79 extends from the printhead assembly 22 and folds around the printhead assembly 22. The flex PCB 79 may also have a plurality of decoupling capacitors 81 arranged along its length for controlling the power and data signals received. As best shown in Fig. 8, the flex PCB 79 has a plurality of electrical contacts 180 formed along its length for receiving power and or data signals from the control circuitry of the cradle unit 12. A plurality of holes 80 are also formed along the distal edge of the ilex PCB 79 which provide a means for attaching the flex PCB to the flange portion 40 of the rigid plate 34 of the main body 20. The maimer in which the electrical contacts of the flex PCB 79 contact the power and data contacts of the cradle unit 12 will be described later. As shown in Fig. 10, a media shield 82 protects the printhead ICs 74 from damage which may occur due to contact with the passing media. The media shield 82 is attached to the upper member 62 upstream of the printhead ICs 74 via an appropriate clip-lock arrangement or via an adhesive. When attached in this manner, the printhead ICs 74 sit below the surface of the media shield 82, out of the path of the passing media. A space 83 is provided between the media shield 82 and the upper 62 and lower 65 members which can receive pressurized air from an air compressor or the like. As this space 83 extends along the length of the printhead assembly 22, compressed air can be supplied to the space 56 from either end of the printhead assembly 22 and be evenly distributed along the assembly. The inner surface of the media shield 82 is provided with a series of fins 84 which define a plurality of air outlets evenly distributed along the length of the media shield 82 through which the compressed air travels and is directed across the printhead ICs 74 in the direction of the media delivery. This arrangement acts to prevent dust and other particulate matter carried with the media from settling on the surface of the printhead ICs, which could cause blockage and damage to the nozzles. INK Delivery Nozzles Examples of a type of ink delivery nozzle arrangement suitable for printhead ICs 74 will now be described with reference to Figures 16 to 25. Figure 25 shows an array of ink delivery nozzle arrangements 801 formed on a silicon substrate 8015. Each of the nozzle arrangements 801 are identical, however groups of nozzle arrangements 801 are arranged to be fed with different colored inks or fixative. In this regard, the nozzle arrangetments are arranged in rows and are staggered with respect to each other, allowing closer spacing of ink dots during printing than would be possible with a single row of nozzles. Such an arrangement makes it possible to provide a high density of nozzles, for example, more than 5000 nozzles arrayed in a plurality of staggered rows each having an interspacing of about 32 microns between the nozzles in each row and about 80 microns between the adjacent rows. The multiple rows also allow for redundancy (if desired), thereby allowing for a predetermined failure rate per nozzle. Each nozzle arrangement 801 is the product of an integrated circuit fabrication technique, hi particular, the nozzle arrangement 801 defines a micro-electromechanical system (IslEMS). twisting movement that causes the lever and 8018 to move generally downwards. The movement is effectively a pivoting or hinging motion. However, the absence of a true pivot point means that the rotation is about a pivot region defined by bending of the passive beams 806. The downward movement (and slight rotation) of the lever arm 8018 is amplified by the distance of the nozzle wall 8033 from the passive beams 806. The downward movement of the nozzle wails and roof causes a pressure increase within the chamber 8029, causing the meniscus to bulge as shown in Fig. ] 7. It will be noted that the surface tension of the ink means the fluid seal 8011 is stretched by this, motion without allowing ink to leak out. As shown in Fig. 18, at the appropriate time, the drive current is stopped and the actuator beam 807 quickly cools and contracts. The contraction causes the lever arm to commence its return to the quiescent position, which in turn causes a reduction in pressure in the chamber 8029. The interplay of the momentum of the bulging ink and its inherent surface tension, and the negative pressure caused by the upward movement of the nozzle chamber 8029 causes thinning, and ultimately snapping, of the bulging meniscus to define an ink drop 802 that continues upwards until it contacts adjacent print media. arrangement having a nozzle chamber containing ink and a thennal bend actuator connected to a paddle positioned within the chamber. The thermal actuator device is actuated so as to eject ink from the nozzle chamber. The preferred embodiment includes a particular thermal bend actuator which includes a series of tapered portions for providing conductive heating of a conductive trace. The actuator is connected to the paddle via an arm received through a slotted wall of the nozzle chamber. The actuator arm has a mating shape so as to mate substantially with the surfaces of the slot ia the nozzle chamber wall. Turning initially to Figs. 27(a)-(c), there is provided schematic illustrations of the basic operation of a nozzle arrangement of this embodiment. A nozzle chamber 501 is provided filled the ink outside the nozzle rim and the corresponding backflow results in a general necking and brealdng off of the drop 512 which proceeds to the print media. The collapsed meniscus 505 results in a general sucking of ink into the nozzle chamber 502 via the ink flow channel 503. In time, the nozzle chamber 501 is refilled such that the position in Fig. 27(a) is again reached and the nozzle chamber is subsequently ready for the ejection of another drop of ink-Fig. 28 illustrates a side perspective view of the nozzle arrangement. Fig. 29 illustrates sectional view through an array of nozzle arrangement of Fig. 28. In these figures, the numbering of elements previously introduced has been retained. Firstly, the actuator 508 includes a series of tapered actuator units e.g. 515 which comprise an upper glass portion (amorphous silicon dioxide) 516 formed on top of a titanium nitride layer 517. Alternatively a copper nickel alloy layer (hareinafter called cupronickel) can be utilized which will have a higher bend efficiency. ink ejection nozzle arraagements laid out in interleaved lines so as to form a printhead array. Of course, different types of arrays can be formulated including full color arrays etc. The construction of the printhead system described can proceed utilizing standard MEMS techniques through suitable modification of the steps as set out in US 6,243,113 entitled "Image Creation Method and Apparatus (TJ 41)" to the present applicant, the contents of which are fully incorporated by cross reference. CLAIMS 1. A method of bonding a first substrate to a second substrate, the method comprising the steps of: (a) providing a first substrate having a plurality of etched trenches defined in a first bonding surface; (b) providing a second substrate having a second bonding surface; and (c) bonding the first bonding surface and the second bonding surface together using an adhesive, wherein the adhesive is received, at least partially, in the plurality of etched trenches during bonding. 2. The method of claim 1, wherein the first substrate has a thickness of less than 1000 microns. 3. The metiiod of claim 1, wherein the first substrate has a thickness of less than about 250 microns. 4. The method of claim 1, wherein the first substrate is an integrated circuit. 5. The method of claim 1, wherein the first substrate is a printhead integrated circuit 6. The method of claim 5, wherein the second substrate is a molded ink manifold configured for mounting a plurality of printhead integrated circuits thereon. 7. The method of claim 1, wherein the etched trenches have a diameter or a width sufficient to draw in a liquid adhesive by capillary action, 8. The method of claim 1, wherein the etched trenches have a diameter or a width of less than about 10 microns. 9. The method of claim 1, wherein the etched trenches have a depth of at least 20 microns. 10. The method of claim 1, wherein the etched trenches have an aspect ratio of at least 3:1. 11. The method of claim 1, wherein the etched trepches increase the effective surface area of the first bonding surface by at least 20%, 12. The method of claim 1, wherein the first bonding surface has a maximum surface roughness max of less than about 20 nm. 13. The method of claim 1, wherein the first bonding surface has a maximum surface roughness Rmax of less than about 5 run. 14. The method of claim 1, wherein the first bonding surface has an average surface roughness Ra of less than about 20 nm. 15. The method of claim 1, wherein the first bonding surface has an average surface roughtness Rfl of less than about 5 nm. 16. The method of claim 1, wherein the first substrate has a Total Thickness Variation (TTV) of less than about 5 microns. 17. The method of claim 1, wherein the adhesive is a liquid-based adhesive. 18. The method of claim 1, wherein the adhesive is an adhesive tape comprising a liquid-based adhesive. 19. The method of claim 1, wherein at least the first substrate cools during bonding, thereby generating a partial vacuum in the etched trenches above the adhesive. 20. The method of claim 1, wherein at least the first substrate is heated prior to bonding, and allowed to cool during bonding. 21. The method of claim 19, wherein the partial vacuum holds, at least partially, the first and second substrates together during bonding. 22. A first substrate suitable for bonding to a second substrate using an adhesive, said first substrate having a plurality of etched trenches defined in a first bonding surface, the etched trenches being configured for receiving the adhesive during bonding. 23. The first substrate of claim 22, having a thickness of less than 1000 microns. 24. The first substrate of claim 22, having a thickness of less than 250 microns. 25. The first substrate of claim 22, which is a semiconductor integrated circuit. 26. The first substrate of claim 22, which is a MEMS integrated circuit. 27. The first substrate of claim 22, which is a printhead integrated circuit. 28. The first substrate of claim 22, wherein the etched trenches have a diameter or a width sufficient to draw in a liquid adhesive by capillary action. 29. The first substrate of claim 22, wherein the etched trenches have a diameter or a width of less than about 10 microns. 30. The first substrate of claim 22, wherein the etched trenches have a depth of at least 20 microns. 31. The first substrate of claim 22, wherein the etched trenches have an aspect ratio of at least 3:1. 32. The first substrate of claim 22, wherein the etched trenches increase the effective surface area of the first bonding surface by at least 20%. 33. The first substrate of claim 22, wherein the first bonding surface has a Tnaximnm surface roughness Rmax of less than about 20 nm. 34. The firat substrate of claim 22, wherein the first bonding surface has a maximum surface roughness Rmax of less than about 5 nm. 35. The first substrate of claim 22, wherein the first bonding surface has an average surface roughness R3 of less than about 20 nm. 36. The Sxst substrate of claim. 22, wherein the first bonding surface has an average surface roughness R3 of less than about 5 mn. 37. The first substrate of claim 22, wherein the first substrate has a Total Tbickness Variation (TTV) of less than about 5 microns. 38. The first substrate of claim 22, wherein the adhesive is a liquid-based adhesive. 39. The first substrate of claim 22, wherein the adhesive is an adhesive tape comprising a liquid-based adhesive, 40. A bonded assembly comprising: (a) a first substrate having a plurality of etched trenches defined in a first bonding surface; and (b) a second substrate having a second banding surface, the second bonding surface being bonded to the first bonding surface with an adhesive, wherein the adhesive is received, at least partially, in the plurality of etched trenches. 41. The bonded assembly of claim 40, wherein the first substrate has a thickness of less than 1000 microns. 42. The bonded assembly of claim 40, wherein the first substrate has a thickness of less than 250 microns. 43. The bonded assembly of claim 40, wherein the first substrate is a semiconductor integrated circuit. 44. The bonded assembly of claim 40, wherein the first substrate is a MEMS integrated circuit. 45. The bended assembly of claim 40, wherein the first substrate is a printhead integrated circuit. 46. The bonded assembly of claim 40, wherein the second substrate is a polymer. 47. The bonded assembly of claim 45, wherein the second substrate is a molded ink manifold configured for mounting a plurality of printhead integrated circuits thereon. 48. The bonded assembly of claim 40, wherein the etched trenches have a diameter or a width sufficient to draw in a liquid adhesive by capillary action. 49. The bonded assembly of claim 40, wherein the etched trenches have a diameter or a width of less than about 10 microns. 50. The bonded assembly of claim 40, wherein the etched trenches have a depth of at least 20 microns. 51. The bonded assembly of claim 40, wherein the etched trenches have an aspect ratio of at least 3:1. 52. The bonded assembly of claim 40, wherein the etched tranches increase the effective surface area of the first bonding surface by at least 20%. 53. The bonded assembly of claim 40, wherein the first bonding surface has a maximum surface roughness Rmax of less than about 20 nm. 54. The bonded assembly of claim 40, wherein the first bonding surface has a maximum sm:fece roughness RMAX of less than about 5 nm- 55. The bonded assembly of claim 40, wherein the first bonding surface has an average surface roughness Ra of less than about 20 nm. 56. The bonded assembly of claim 40, wherein the first bonding surface has an average surface roughness Ra of less than about 5 nm. 57. The bonded assembly of claim 40, wherein the firstsubstrate has a Total thickness Variation (TTV) of less than about 5 microns. 58. The bonded assembly of claim 40, wherein the adhesive is a liquid-based adhesive. 59. The bonded assembly of claim 40, wherein the adhesive is an adhesive tape comprising a liquid-based adhesive. 60. A printhead assembly comprising: (a) a plurality of printhead integrated circuits, each printhead integrated circuit comprising: a plurality of nozzles fonned on a front side of the printhead integrated circuit; a plurality of ink supply channels for supplying ink from a backside of the printhead integrated circuit to the nozzles; and a plurality of etched trenches defined in the backside; and (b) an ink manifold having a mounting sur face the backside of each printhead integrated circuit being bonded to the mounting surface with an adhesive, wherein the adhesive is received, at least partially, in the plurality of etched trenches. 61. The printhead assembly of claim 60, wherein each printhead integrated circuit has a thickness of less than 250 microns. 62. The printhead assembly of claim 60, wherein the ink manifold is a molded ink manifold fonned from a polymer. 63. The printhead assembly of claim 60, wherein the etched trenches have a diameter or a width sufficient to draw in a liquid adhesive by capillary action. 64. The printhead assembly of claim 60, wherein the etched trenches have a diameter or a width of less than about 10 microns. 65. The printhead assembly of claim 60, wherein the etched trenches have a depth of at least 20 microns. 66. The printhead assembly of claim 60, wherein the etched trenches have an aspect ratio of at least 3: L 67. The printhead assembly of ciaini 60, wherein the etched trenches increase the effective surface area of each backside surface by at least 20%. 68. The printhead assembly of claim 60, wherein each backside surface has a maximum surface roughness Rmax of less than about 20 mn. 69. The prinfhead assembly of claim 60, wherein each backside surface has a maximum surface roughness RMAX of less than about 5 nm. 70. The printhead assembly of claim 60, wherein each backside surface has an average surface roughness Ra of less than about 20 nm. 71. The printhead assembly of claim 60, wherein each backside surface has an average surface roughness Ra of less than about 5 nm. 72. The printhead assembly of claim 60, wherein each printhead integrated circuit has a Total Thickness Variation (TTV) of less than about 5 microns. 73. The printhead assembly of claim 60, wherein the adhesive is a liquid-based adhesive. 74. The printhead assembly of claim 60, wherein the adhesive is an adhesive tape comprising a liquid-based adhesive. 75. A printer comprising the printhead assembly of claim 60. 76. The printer of claim 75, which is a pagewidth inkjet printer. 77. A printhead integrated circuit suitable for bonding to a mounting surface of an ink manifold using an adhesive, said printhead integrated circuit comprising: a plurality of nozzles formed on a front side of the printhead integrated circuit; a plurality of ink supply channels for supplying ink from a backside of the printhead integrated circuit to the nozzles: and a plurality of etched trenches defined in the backside, the etched trenches being configured for receiving the adhesive during bonding. 78. The printhead integrated circuit of claim 77, having a thickness of less than 250 microns. 79. The printhead integrated circuit of claim 77, wherein the etched trenches have a diameter or a width sufficient to draw in a liquid adhesive by capillary action. 80. The printhead integrated circuit of claim 77, wherein the etched trenches have a diameter or a width of less than about 10 microns. 81. The printhead integrated circuit of claim 77, wherein the etched trenches have a depth of at least 20 microns. 82. The printhead integrated circuit of claim 77, wherein the etched trenches have an aspect ratio ofat least 3:1. 83. Tie printhead integrated circuit of claim 77, wherein the etched trenches increase the effective surface area of the first bonding surface by at least 20%, 84. The printhead integrated circuit of claim 77, wherein the first bonding surface has a maximum in surface roughness Rmax of less than about 20 nm. 85. The printhead integrated circuit of claim 77, wherein the first bonding surface has a maximum surface roughness Rmax of less than about 5 nm. 86. The printhead integrated circuit of claim 77, wherein the first bonding surface has an average surface roughness Ra of less than about 20 nm. 87. The printhead integrated circuit of claim 77, wherein the first bonding surface has an average surface roughness Ra of less than about 5 nm. 88. The printhead integrated circuit of claim 77,.having a Total Thickness Variation (TTV) of less than about 5 microns. 89. The first substrate of claim 77, wherein the adhesive is a hquid-based adhesive. 90. The first substrate of claim 77, wherein the adhesive is an adhesive tape comprising a liquid-based adhesive.

Documents:

3768-CHENP-2007 AMENDED CLAIMS 27-05-2011.pdf

3768-CHENP-2007 OTHER PATENT DOCUMENT 27-05-2011.pdf

3768-chenp-2007 form-3 27-05-2011.pdf

3768-CHENP-2007 CORRESPONDENCE OTHERS 08-10-2010.pdf

3768-CHENP-2007 EXAMINATION REPORT REPLY RECEIVED 27-05-2011.pdf

3768-chenp-2007-abstract.pdf

3768-chenp-2007-claims.pdf

3768-chenp-2007-correspondnece-others.pdf

3768-chenp-2007-description(complete).pdf

3768-chenp-2007-drawings.pdf

3768-chenp-2007-form 1.pdf

3768-chenp-2007-form 18.pdf

3768-chenp-2007-form 26.pdf

3768-chenp-2007-form 3.pdf

3768-chenp-2007-form 5.pdf

3768-chenp-2007-pct.pdf