Patent Publication Number: US-6902260-B2

Title: Fluid ejection device adherence

Description:
BACKGROUND 
     A typical inkjet printer usually has a carriage that contains one or more fluid-ejection devices, e.g., print heads, capable of ejecting fluid, such as ink, onto media, such as paper. Print heads usually include a carrier and a fluid-ejecting substrate (or print die), e.g., formed from silicon or the like using semiconductor processing methods, such as photolithography or the like. 
     The print die is typically affixed to the carrier by an adhesive. In many applications, the carrier includes a plurality of ink delivery channels for directing the ink from the ink reservoir to the print die. A surface of the carrier surrounds each of the ink delivery channels and forms ribs on either side of each of the ink delivery channels. Moreover, print dies usually include a plurality of slots that receive the ink from the ink delivery channels and direct the ink to resistors of the print die. A portion of a surface of the print-die surface surrounds each of the slots and forms ribs on either side of each of the slots. The slots of the print die are typically aligned with the ink delivery channels, and each of the ribs of the print die respectively abuts one of the ribs of the carrier. 
     To affix a print die to a carrier, an adhesive is typically applied to ribs of the carrier and/or the ribs of the print die, e.g., using a capillary tube of a syringe. The ribs of the print die are aligned with the ribs of the carrier and are pressed into abutment with the ribs of the carrier. One problem with this is that adhesive can be forced from between the abutting ribs and into the ink delivery channels of the carrier and/or the slots of print die, causing a blockage to the flow of ink. To correct for this, the amount of adhesive applied to the ribs is often reduced, which can undesirably allow ink to pass from one slot to another or to leak from the print cartridge. Moreover, print dies are becoming smaller and thus print-die and carrier ribs are becoming smaller. For some applications, print-die and carrier-rib sizes are on the order of, or are smaller than, the diameter of the capillary tubes of the syringes used to apply the adhesives, making it difficult to apply adhesive to the ribs. For many applications, capillary tube diameters cannot be reduced any further because increased fluid flow friction associated with reducing the diameter will make it extremely difficult to produce adhesive flow through the capillary tube. 
     After the print die is affixed to the carrier, the electrical contacts of the print die are electrically connected to the electrical connectors of the carrier using the electrical interconnects. Since many types of ink are corrosive to the electrical contacts, connectors, and interconnects, an encapsulant is usually disposed on the electrical contacts, connectors, and interconnects to protect them from the ink. However, the electrical contacts, connectors, and interconnects are often located adjacent the orifices, and the encapsulant often flows over the orifices, causing the orifices to become clogged. Moreover, many inkjet printers employ a wiper for wiping ink residue from the orifices to prevent the residue from clogging the orifices or from misdirecting ejected ink drops. However, encapsulants often flow to and solidify at a location such that the encapsulant prevents the wiper from effectively cleaning some of the orifices. 
     SUMMARY 
     One embodiment of the present invention provides a method for manufacturing a fluid-ejection device capable of ejecting fluid onto media. The method includes adhering a fluid-ejecting substrate of the fluid-ejection device to a carrier of the fluid-ejection device by drawing an adhesive between the fluid-ejecting substrate and the carrier using capillary action. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a carrier of a fluid-ejection device according to an embodiment of the present invention. 
         FIG. 2  is a cross-sectional view of a fluid-ejection device according to another embodiment of the present invention. 
         FIG. 3  is a cross-sectional view illustrating dispensing an adhesive between a carrier of the fluid-ejection device of  FIG. 2 and a  fluid-ejecting substrate of the fluid-ejection device of  FIG. 2  according to another embodiment of the present invention. 
         FIG. 4  is a view taken along line  4 — 4  of FIG.  3 . 
         FIG. 5  is a view taken along line  5 — 5  of FIG.  3 . 
         FIG. 6  is a view taken along line  6 — 6  of FIG.  3 . 
         FIG. 7  is a cross-sectional view illustrating an adhesive disposed between a carrier of the fluid-ejection device of  FIG. 2 and a  fluid-ejecting substrate of the fluid-ejection device of  FIG. 2  according to another embodiment of the present invention. 
         FIG. 8  is a view taken along line  8 — 8  of FIG.  7 . 
         FIG. 9  is a view taken along line  9 — 9  of FIG.  7 . 
         FIG. 10  is a cross-sectional view illustrating dispensing an adhesive between a carrier of the fluid-ejection device of  FIG. 2 and a  fluid-ejecting substrate of the fluid-ejection device of  FIG. 2  according to another embodiment of the present invention. 
         FIG. 11  is a view taken along line  11 — 11  of FIG.  10 . 
         FIG. 12  is a view taken along line  12 — 12  of FIG.  10 . 
         FIG. 13  is a perspective view illustrating a carrier of a fluid ejection device according to another embodiment of the present invention. 
         FIG. 14  is a perspective view illustrating an adhesive disposed in a moat of the carrier of FIG.  13 . 
         FIG. 15  is a perspective view illustrating a fluid-ejection device according to another embodiment of the present invention. 
         FIG. 16  is a cross-sectional view illustrating positioning a fluid-ejecting substrate of a fluid-ejection device on a carrier of the fluid-ejection device according to another embodiment of the present invention. 
         FIGS. 17 and 18  are cross-sectional views illustrating an adhesive being drawn between the fluid-ejecting substrate of FIG.  16  and the carrier of  FIG. 16  according to another embodiment of the present invention. 
         FIG. 19  is a perspective view of a fluid-ejection device according to another embodiment of the present invention. 
         FIG. 20  is an enlarged view of region  2000  of FIG.  19 . 
         FIG. 21  is a view taken along line  21 — 21  of FIG.  20 . 
         FIG. 22  is a view taken along line  22 — 22  of  FIG. 20  illustrating another embodiment of the present invention. 
         FIG. 23  illustrates channels disposed on a surface of a fluid-ejecting substrate of the fluid-ejection device of  FIG. 19  according to another embodiment of the present invention. 
         FIG. 24  illustrates a channel disposed on a surface of a fluid-ejecting substrate of the fluid-ejection device of  FIG. 19  according to yet another embodiment of the present invention. 
         FIG. 25  illustrates a fluid-ejection cartridge according to another embodiment of the present invention. 
         FIG. 26  illustrates a fluid deposition system according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description of the present embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that process, electrical or mechanical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims and equivalents thereof. 
       FIG. 1  illustrates a carrier  100  of a fluid ejection device, such as a print head, according to an embodiment of the present invention. Carrier  100  has a recess (or well)  102  in a surface  104 . A surface  110  and walls  112  bound recess  102 . For one embodiment, surface  110  is substantially parallel to surface  104 , and walls  112  are substantially perpendicular to surfaces  104  and  110 . In other embodiments, walls  112  are inclined between surfaces  102  and  110 . For one embodiment, a flow passage  114  passes through a portion of carrier  100  and opens into recess  102  at one of walls  112 . Surface  110  surrounds flow channels  116 , e.g., ink delivery channels, of carrier  100  that open into recess  102  at surface  110 . Carrier  100  can be fabricated from plastic, ceramic, silicon, or the like. 
       FIGS. 2-12  illustrate adhering a fluid-ejecting substrate  202  (e.g., a print-head die or substrate) to carrier  100  to form a fluid-ejection device  200  according to an embodiment of the present invention. Fluid-ejection device  200  is capable of ejecting fluid, e.g., ink, onto media, such as paper. For one embodiment, a gap  204  is formed between fluid-ejecting substrate  202  and carrier  100  by disposing spacers (or standoffs)  206  between a surface  212  fluid-ejecting substrate  202  and surface  110  of carrier  100 . Examples of spacers  206  include permanent shims, removable shims, thin films disposed on carrier  100  by thin-film processing techniques, standoffs integral with carrier  100  formed by plastic injection or the like, small adhesive dots cured in place, metal posts, solder bumps, polymide tape, etc. For some embodiments, naturally occurring projections, e.g., that constitute roughness, on a surface  212  fluid-ejecting substrate  202  and surface  110  of carrier  100  can form gap  204 . In some embodiments, gap  204  ranges from about 0.5 to about 150 microns. 
     Fluid-ejecting substrate  202  includes slots  210  ( FIG. 4 ) that respectively align with channels  116  ( FIG. 5 ) when fluid-ejecting substrate  202  is disposed on carrier  100 , as shown in FIG.  6 . Moreover, surface  212  of fluid-ejecting substrate  202  surrounds each of slots  210 , as shown in FIG.  4 . For various embodiments, fluid-ejecting substrate  202  is formed from a semiconductor material, such as silicon or the like using semiconductor processing methods, such as photolithography or the like. Note that fluid-ejecting substrate  202  is shown as a dashed line on carrier  100  in  FIGS. 5 ,  9 , and  12  to illustrate positioning of fluid-ejecting substrate  202  on carrier  100 . 
     An adhesive  220  is disposed between fluid-ejecting substrate  202  and carrier  100  for adhering fluid-ejecting substrate  202  to carrier  100 . For one embodiment, adhesive  220  is directed into recess  102  through flow passage  114 , as shown in FIG.  2 . In other embodiments, adhesive  220  is dispensed into recess using a syringe or the like. One suitable adhesive is available from Emerson &amp; Cuming, Inc., Billerica, Mass., USA, as part numbers E1172 or E1216. 
     For one embodiment, capillary action draws adhesive  220  through gap  204  between fluid-ejecting substrate  202  and carrier  100  from one of edges  222  of fluid-ejecting substrate  202 , as illustrated in  FIGS. 3-5 . For other embodiments, capillary action draws adhesive  220  through gap  204  from all of edges  222 , as illustrated in  FIGS. 10-12 . Adhesive  220  flows over surface  212  of fluid-ejecting substrate  202  without flowing into slots  210 . Adhesive  220  also flows over surface  110  of carrier  100  without flowing into channels  116 . 
     Adhesive  220  continues to flow on surfaces  110  and  212  until surface  212  and the portion of surface  110  corresponding to surface  212  are coated with adhesive  220 , as shown in  FIGS. 7-9  for the situation of  FIGS. 3-5 , i.e., where adhesive  220  is drawn from one of edges  222 . For the situation of  FIGS. 10-12 , i.e., where adhesive  220  is drawn from all of edges  222 , surfaces  110  and  212 , for one embodiment, will be completely coated with adhesive  220  when adhesive  220  stops flowing. At this point, adhesive  220  is allowed to cure and/or solidify, thereby adhering fluid-ejecting substrate  202  to carrier  100 . 
     An attractive force between molecules of adhesive  220  and surfaces  110  and  212  causes adhesive  220  to wet surfaces  110  and  212  and produces the capillary action that draws adhesive  220  through gap  204 . The surface tension of adhesive  220  acts to prevent adhesive  220  from flowing into channels  116  and slots  210 . 
     For one embodiment, the surface tension of adhesive  220  provides a self-alignment feature. That is, as adhesive  220  wets surfaces  110  and  212 , the surface tension causes wetted surfaces  110  and  212  to align with each other, causing slots  210  to respectively self-align with channels  116 . 
     For some embodiments, before drawing adhesive  220  through gap  204 , adhesive  220 , fluid-ejecting substrate  202 , and carrier  100  are heated to a temperature, e.g., about 80° C., where the viscosity of adhesive  220  is such that the adhesive  220  flows with less resistance through gap  204  when drawn therethrough. For some embodiments, the viscosity of adhesive  220 , when heated, ranges from about 30 to about 2500 centipoise. Heating can also improve the wetting of surfaces  110  and  212  by adhesive  220 , thereby enabling adhesive  220  to flow better through gap  204 . 
       FIG. 13  illustrates a carrier  1300  of a fluid ejection device according to another embodiment of the present invention. Elements common to  FIGS. 1 and 13  are numbered as in FIG.  1  and are as described above. Carrier  1300  includes a channel (or moat)  1310  disposed around surface  110  of carrier  1300 . For some embodiments, moat  1310  and surface  110  are located within in a recess (or well), such as shown in  FIG. 1  for carrier  100  and as described above. For other embodiments, the moat is located below surface  110  of carrier  1300 , as shown in FIG.  13 . 
       FIGS. 14-18  illustrate adhering fluid-ejecting substrate  202  to carrier  1300  to form a fluid-ejection device  1500  according to another embodiment of the present invention. Elements common to  FIGS. 2-12  and  FIGS. 14-18  are numbered as in  FIGS. 2-12  and are as described above. Adhesive  220  is disposed in moat  1310  as shown in FIG.  14 . For one embodiment, a portion of adhesive  220  protrudes above surface  110  of carrier  1300 , as shown in  FIG. 16 , due to the surface tension of adhesive  220 . For another embodiment, adhesive  220  is directed into moat  1310  through a flow passage, such as flow passage  114  shown in FIG.  2 . In other embodiments, adhesive  220  may be dispensed into moat  1310  using a syringe or the like. 
     Fluid-ejecting substrate  202  is positioned on spacers  206  to form gap  204 , as shown in  FIGS. 15-18 . When fluid-ejecting substrate  202  contacts adhesive  220 , adhesive is drawn into gap  204  from all of edges  222  of fluid-ejecting substrate  202  by capillary action, e.g., as described above and shown in  FIGS. 10-12  for fluid-ejection device  200 . For one embodiment, the surface tension of adhesive  220  causes slots  210  to respectively self-align with channels  116 , as described above. 
       FIG. 19  is a perspective view of a fluid-ejection device  1900 . Elements common to  FIGS. 1-12  and  FIG. 19  are numbered as in  FIGS. 1-12 . Fluid-ejection device  1900  includes fluid-ejecting substrate  202  disposed on a carrier  1902 . For one embodiment, carrier  1902  is as described above for carrier  100  or carrier  1300 , and fluid-ejecting substrate  202  is adhered to carrier  1902  as described above for forming fluid-ejection device  200  or  1500 . For one embodiment, fluid-ejecting substrate  202  includes orifices  214  in a surface  216  of fluid-ejecting substrate  202 . Surface  216  is opposite surface  212 , as shown in FIG.  3 . For one embodiment, resistors  217  are disposed in fluid-ejecting substrate  202  adjacent each of orifices  214 , as shown in  FIGS. 25 and 26 . 
     After adhering fluid-ejecting substrate  202  to carrier  1902 , electrical contacts  250  of fluid-ejecting substrate  202  are electrically connected to electrical connectors  1950  of carrier  1902  using electrical interconnects  252 , such as wires. Electrical contacts  250  are electrically connected to resistors  217  of fluid-ejecting substrate  202 . An encapsulant  254  is disposed on electrical contacts  250 , electrical connectors  1950 , and electrical interconnects  252  to protect them from fluid that is ejected through orifices  214 . Electrical connectors  1950  are electrically connected to an electrical terminal  1960 . Electrical terminal  1960  is connected to a power source (not shown), e.g., included as a part of a printer (not shown). Electrical signals for energizing resistors  217  are conveyed from the power source to resistors  217  via electrical terminal  1960 , electrical connectors  1950 , electrical interconnects  252 , and electrical contacts  250 . 
     Channels  260  are disposed in surface  216  of fluid-ejecting substrate  202  between electrical connectors  250  and orifices  214 , as shown in  FIGS. 19 and 20 , e.g., using semiconductor fabrication methods, such as etching, photolithography, or the like. Each of ribs  262  respectively separates successively adjacent channels  260 . Ribs  262  extend from a base  264  of each of channels  260  to surface  216 , as shown in  FIGS. 21 and 22 . 
     As encapsulant  254  is dispensed on electrical contacts  250 , electrical connectors  150 , and electrical interconnects  252  by directing a flow of encapsulant  254  thereon, e.g., using a syringe or the like, encapsulant  254  can spread (or flow) toward orifices  214 . As encapsulant  254  flows toward orifices  214 , encapsulant  254  flows over ribs  262  and in channels  260 , as shown in  FIGS. 20 and 21 . This acts to prevent encapsulant  254  from spreading, e.g., beyond a distance d from orifices  214  located closest to channels  260 , as shown in FIG.  20 . 
     For one embodiment, encapsulant  254  includes resin and filler components. For another embodiment, the filler includes particles of silica, alumina, calcium carbonate, fumed SiO 2  of a controlled particle size, etc. For other embodiments, filler particle sizes can range from about 1 micron to about 50 microns. The filler acts generally to increase the viscosity of encapsulant  254 . That is, the higher the filler concentration, the more viscous the encapsulant  254 . For one embodiment, and as best understood with reference to  FIG. 20 , an attractive force between molecules of encapsulant  254  and ribs  262  produces capillary action that draws the resin from encapsulant  254 , causing the resin to flow through channels  260  substantially parallel to surface  216  and away from a boundary (or front)  266  of encapsulant  254 , as indicated by arrow  268  in FIG.  20 . This increases the filler concentration and thus the viscosity of encapsulant  254  adjacent the boundary  266 . The increased viscosity acts to control the spread of encapsulant  254 . In one embodiment, the increased viscosity acts to stop the flow of encapsulant  254  at the distance d from orifices  214  located closest to channels  260 . In another embodiment, the increased viscosity acts to slow the flow of encapsulant  254  so that encapsulant  254  solidifies at the distance d from orifices  214  located closest to channels  260 . 
     For some embodiments, and as best understood with reference to  FIG. 22 , ribs  262  are spaced so that the width w of each of channels  260  is too small for encapsulant  254  to flow into channels  260 , e.g., owing to surface tension, viscosity, etc. of encapsulant  254 . In these embodiments, encapsulant  254  flows over segments of surface  216  (i.e., segments corresponding to surfaces of the ribs  262 ) located between channels  260  toward orifices  214 , as indicated by arrow  268  in FIG.  22 . Further, in these embodiments, capillary action draws resin away from a boundary  270  of encapsulant  254  that is substantially parallel to surface  216  into channels  260  toward base  264  so that the resin flows substantially perpendicular to surface  216 , as indicated by arrows  272  in FIG.  22 . This increases the filler concentration and thus the viscosity of encapsulant  254  adjacent the boundary  270 . The increased viscosity acts to control the spread of encapsulant  254  by slowing or stopping the flow of encapsulant  254 . 
     For another embodiment, channels  2360  are disposed in surface  216  of fluid-ejecting substrate  202  between electrical connectors  250  and orifices  214 , as shown in FIG.  23 . Channels  2360  include channel segments  2362  and  2364  connected by a taper  2366 . In this way, channel segment  2362  has a larger flow cross-section than channel segment  2364 . For one embodiment, channel segment  2364  is sized so that channel segment  2364  acts to prevent particles of the filler of encapsulant  254  from flowing through channel segment  2364 . For another embodiment, this is accomplished by making the flow cross-section of channel segment  2364  smaller than the particles of the filler. For other embodiments, an inlet  2368  to channel segment  2364  is at the distance d from orifices  214  located closest to channels  2360 . 
     Encapsulant  254  flows over surface  216  in the vicinity of channels  2360  and through channel segments  2362 . When encapsulant  254  encounters channel segment  2364 , the filler stops generally at inlet  2368 , and the resin is drawn through channel segment  2364  by capillary action. This increases the filler concentration and thus the viscosity of encapsulant  254  adjacent a boundary  2370  of encapsulant  254 . Channel segments  2364  and the increased viscosity act to control the spread of encapsulant  254  by slowing or stopping the flow of encapsulant  254 . In particular, for one embodiment, channel segments  2364  and the increased viscosity act to stop the flow of encapsulant  254  at the distance d, where, in other embodiments, encapsulant  254  solidifies. 
     In another embodiment, the channels disposed in surface  216  of fluid-ejecting substrate  202  are as shown for channel  2460  in FIG.  24 . Channel  2460  includes channel segments  2462  and  2464  connected by a step  2466 . In this way, channel segment  2462  has a larger flow cross-section than channel segment  2464 . For one embodiment, channel segment  2464  is sized so that channel segment  2464  acts to prevent particles of the filler of encapsulant  254  from flowing through channel segment  2464 . For another embodiment, this is accomplished by making the flow cross-section of channel segment  2464  smaller than the particles of the filler. For other embodiments, an inlet  2468  to channel segment  2462  is at the distance d from orifices  214  located closest to the channels disposed in surface  216 . Channel  2460  functions generally as described above for channels  2360 . That is, when encapsulant  254  encounters channel segment  2464 , the filler stops generally at inlet  2468 , and the resin is drawn through channel segment  2464  by capillary action. 
     For one embodiment, the resin separates from the filler and continues to flow ahead of the concentrated filler region until the capillary force reaches equilibrium, thereby stopping resin flow. In effect, there is a resin/filler gradient, and the resin advances to create a thin, tapered layer that eventually stops because there is no additional resin supply. 
       FIG. 25  illustrates a fluid-ejection cartridge  2500 , e.g., a print cartridge, according to another embodiment of the present invention. Elements common to  FIGS. 1-19  and  FIG. 25  are as described above for  FIGS. 1-19 . Fluid-ejection cartridge  2500  includes a fluid reservoir  2510 , e.g., an ink reservoir, integral with a carrier  2530  of a fluid-ejection device  2540 . For one embodiment, carrier  2530  is as described for carriers  100 ,  1300 , or  1902 , respectively of  FIGS. 1 ,  13 , and  19 . For another embodiment, fluid-ejection device  2540  is as described above for fluid-ejection devices  200 ,  1500 , or  1900 , respectively of  FIGS. 2 ,  15 , and  19  and thus includes the fluid-ejecting substrate  202  described above. A flow passage  2550  fluidly couples fluid-ejection device  2540  to reservoir  2510 . 
     In operation, fluid reservoir  2510  supplies fluid, such as ink, to fluid-ejection device  2540 . Channels of carrier  2530 , such as channels  116  of carrier  100  or carrier  1300 , deliver the fluid to slots  210  of fluid-ejecting substrate  202 . The fluid is channeled from slots  210  to resistors  217 . Resistors  217  are selectively energized to rapidly heat the fluid, causing the fluid to be expelled through orifices  214  in the form of droplets  2560 . For some embodiments, droplets  2560  are deposited onto a medium  2570 , e.g., paper, as fluid-ejection cartridge  2500  is fixedly or movably positioned adjacent medium  2570  in an imaging device (not shown), such as a printer, fax machine, or the like. 
       FIG. 26  illustrates a fluid deposition system  2600 , e.g., an ink deposition system, according to another embodiment of the present invention. Elements common to  FIGS. 1-19  and  FIG. 26  are as described above for  FIGS. 1-19 . Fluid deposition system  2600  includes a fluid-ejection device  2610  fluidly coupled to an outlet port  2620  of a fluid reservoir  2630 , e.g., ink reservoir, by a flexible conduit  2640 , such as plastic or rubber tubing or the like. For one embodiment, fluid-ejection device  2610  includes a carrier  2650  that for another embodiment is as described for carriers  100 ,  1300 , or  1902 , respectively of  FIGS. 1 ,  13 , and  19 . For other embodiments, fluid-ejection device  2610  is as described above for fluid-ejection devices  200 ,  1500 , or  1900 , respectively of  FIGS. 2 ,  15 , and  19  and thus includes the fluid-ejecting substrate  202  described above. 
     In operation, fluid reservoir  2630  supplies fluid, such as ink, to fluid-ejection device  2610  via flexible conduit  2640 . Channels of carrier  2650 , such as channels  116  of carrier  100  or carrier  1300 , deliver the fluid to slots  210  of fluid-ejecting substrate  202 . The fluid is channeled from slots  210  to resistors  217 . Resistors  217  are selectively energized to rapidly heat the fluid, causing the fluid to be expelled through orifices  214  in the form of droplets  2660 . For some embodiments, droplets  2660  are deposited onto a medium  2670 , e.g., paper, as fluid-ejection device  2610  is fixedly or movably positioned adjacent medium  2670  while fluid reservoir  2630  remains stationary. Flexible conduit  2640  enables fluid-ejection device  2610  to move relative to fluid reservoir  2630  in some embodiments. 
     CONCLUSION 
     Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement that is calculated to achieve the same purpose may be substituted for the specific embodiments shown. Many adaptations of the invention will be apparent to those of ordinary skill in the art. Accordingly, this application is intended to cover any adaptations or variations of the invention. It is manifestly intended that this invention be limited only by the following claims and equivalents thereof.