Patent Publication Number: US-11390081-B2

Title: Fluid ejection device with a carrier having a slot

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Stage Application of PCT Application No. PCT/US2019/016759, filed Feb. 6, 2019, entitled “FLUID EJECTION DEVICE WITH A CARRIER HAVING A SLOT.” 
     BACKGROUND 
     An inkjet printing system, as one example of a fluid ejection system, may include a printhead, an ink supply which supplies liquid ink to the printhead, and an electronic controller which controls the printhead. The printhead, as one example of a fluid ejection device, ejects drops of ink through a plurality of nozzles or orifices and toward a print medium, such as a sheet of paper, so as to print onto the print medium. In some examples, the orifices are arranged in at least one column or array such that properly sequenced ejection of ink from the orifices causes characters or other images to be printed upon the print medium as the printhead and the print medium are moved relative to each other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating a fluid ejection die according to one example. 
         FIG. 2  is a diagram illustrating a fluid ejection device according to one example. 
         FIGS. 3A-3C  are diagrams illustrating a method of forming the fluid ejection device shown in  FIG. 2  according to one example. 
         FIG. 4  is a diagram illustrating the application of an upper mold chase to a fluid ejection die according to one example. 
         FIGS. 5-7  are diagrams illustrating a top view of a portion of the fluid ejection device shown in  FIG. 2  according to one example. 
         FIG. 8  is a block diagram illustrating a fluid ejection system according to one example. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific examples in which the disclosure may be practiced. It is to be understood that other examples may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims. It is to be understood that features of the various examples described herein may be combined, in part or whole, with each other, unless specifically noted otherwise. 
     Examples of the present disclosure are directed to a fluid ejection device, and a method of manufacturing a fluid ejection device in a manner that reduces or eliminates the formation of epoxy molding compound (EMC) on contact pads positioned near ends of the fluid ejection die. This unintended EMC formation on the contact pads is referred to as EMC flash. During the process, an upper mold chase is applied to the back-side surface of the fluid ejection die. The EMC is then applied to the fluid ejection die using a transfer molding process. The upper mold chase includes a slot forming feature that covers ink feed holes of the fluid ejection die during the application of the EMC, and defines a slot in the resulting EMC panel for providing fluid to the ink feed holes. The length of the feature of the upper mold chase defines the length of the slot, and this length is less than the length of the fluid ejection die. Reducing the space between an end of the feature and an end of the fluid ejection die can reduce or eliminate EMC flash on the contact pads. In one example, the process results in a fluid ejection device with a length between an end of the slot and an end of the fluid ejection die that is less than 1.5 mm. 
       FIG. 1  is a diagram illustrating a fluid ejection die  100  according to one example. Die  100  includes a first longitudinal end portion  102  that includes a plurality (e.g., six in the illustrated example) of contact pads  108 , a second longitudinal end portion  104  that includes a plurality (e.g., six in the illustrated example) of contact pads  108 , and a fluid ejection portion  106  that includes a plurality of fluid actuation devices  107 . The contact pads  108  in the second longitudinal end portion  104  are longitudinally aligned with the contact pads  108  in the first longitudinal end portion  102 , and are positioned at a distance  152  (i.e., along the Y axis) from the contact pads  108  in the first longitudinal end portion  102 . 
     The plurality of fluid actuation devices  107  is disposed longitudinally to the contact pads  108  in the first longitudinal end portion  102  and the contact pads  108  in the second longitudinal end portion  104 . The plurality of fluid actuation devices  107  is also arranged between the contact pads  108  in the first longitudinal end portion  102  and the contact pads  108  in the second longitudinal end portion  104 . In the illustrated example, the contact pads  108  in the first longitudinal end portion  102 , the contact pads  108  in the second longitudinal end portion  104 , and the plurality of fluid actuation devices  107  are each arranged in a column, and the three columns are longitudinally aligned (i.e., not laterally offset from one another). In one example, fluid actuation devices  107  are nozzles or fluidic pumps to eject fluid drops. 
     Die  100  includes an elongate semiconductor (e.g., silicon) substrate  140  having a length  142  (along the Y axis) between lateral ends  148  and  150 , a thickness  144  (along the Z axis), and a width  146  (along the X axis) between lateral ends  103  and  105  of the die  100 . In one example, the length  142  is at least twenty times the width  146 . The width  146  may be 1 mm or less and the thickness  144  may be less than 500 microns. The fluid actuation devices  107  and the contact pads  108  are provided on the elongate substrate  140  and are arranged along the length  142  of the elongate substrate. The fluid actuation devices  107  have a swath length  152  less than the length  142  of the elongate substrate  140 . In one example, the swath length  152  is at least 1.2 cm. The contact pads  108  in the first longitudinal end portion  102  may be arranged near a first longitudinal end  148  of the elongate substrate  140 . The contact pads  108  in the second longitudinal end portion  104  may be arranged near a second longitudinal end  150  of the elongate substrate  140  opposite to the first longitudinal end  148 . 
       FIG. 2  is a diagram illustrating a fluid ejection device  200  according to one example. Fluid ejection device  200  includes a fluid ejection die  100  attached to a carrier  202 . In one example, the carrier  202  is a rigid, molded carrier that is formed by a transfer molding processes. A slot  204  is formed in the carrier  202  to provide fluid to the back side of the fluid ejection die  100 . In one example, the slot  204  extends longitudinally along the fluid ejection die  100 , and is longitudinally aligned (i.e., not laterally offset) with the plurality of fluid actuation devices  107  ( FIG. 1 ). 
       FIGS. 3A-3C  are diagrams illustrating a method of forming the fluid ejection device  200  shown in  FIG. 2  according to one example. As shown in  FIG. 3A , fluid ejection die  100  is positioned on a release tape layer  308 , which is positioned on a die carrier  310 . More specifically, fluid ejection die  100  is positioned with a front-side surface  307  facing the release tape layer  308  and the die carrier  310 . A nozzle layer  309  is formed on the front-side surface  307  of the fluid ejection die  100 . Upper mold chase  302  is positioned over fluid ejection die  100  (and die carrier  310 ). More specifically, upper mold chase  302  is positioned over fluid ejection die  100  with back-side surface  305  of fluid ejection die  100  facing upper mold chase  302 . Upper mold chase  302  includes a slot forming feature  306  that seals fluid feed holes formed in fluid ejection die  100  to protect the fluid feed holes during molding. Upper mold chase  302  includes a bottom surface that defines cavities  312 ( 1 ) and  312 ( 2 ) (collectively referred to as cavities  312 ) between upper mold chase  302  and die carrier  310 . 
     In one example, a release liner  304  is positioned along the bottom surface of upper mold chase  302  so as to be positioned between fluid ejection die  100  and upper mold chase  302 . Release liner  304  helps to prevent contamination of upper mold chase  302  and minimize flash during the molding process. 
     As shown in  FIG. 3B , cavities  312  are filled with mold material  320 , such as an epoxy mold compound, plastic, or other suitable moldable material. Filling cavities  312  with mold material  320  forms a carrier  202  around fluid ejection die  100 . In one example, the molding process is a transfer molding process and includes heating the mold material  320  to a liquid form and injecting or vacuum feeding the liquid mold material into cavities  312  (for example, through runners that communicate with cavities  312 ). The feature  306  of the upper mold chase  302  (as positioned along back-side surface  305  of fluid ejection die  100 ) helps to prevent the mold material from entering the fluid feed holes of die  100  as cavities  312  are filled. 
     As shown in  FIG. 3C , after the mold material cools and hardens to a solid, upper mold chase  302  and liner  304  are removed, and fluid ejection die  100  and carrier  202  are removed or released from die carrier  310 . Thus, carrier  202  is molded to include molded back-side surface  330  and molded front-side surface  332 , with molded front-side surface  332  substantially coplanar with front-side surface  307  of fluid ejection die  100 , and molded back-side surface  330  extending beyond back-side surface  305  of fluid ejection die  100 . As such, carrier  202  has a thickness that is greater than the thickness of fluid ejection die  100 . In addition, front-side surface  307  of fluid ejection die  100  and a portion of back-side surface  305  of fluid ejection die  100  both remain exposed from carrier  202  (i.e., are not covered by mold material of carrier  202 ). While one fluid ejection die  100  is illustrated in  FIGS. 3A-3C  as being molded into carrier  202 , a greater number of fluid ejection dies  100  may be molded into carrier  202 . 
     The shape of the slot  204  is usually a result of particular slotting process (e.g., laser, anisotropic wet etch, dry etch, or a combination of these), and these processes may have a limited influence on the profile of the slot  204  that can be produced. Examples disclosed herein enable a transfer mold process with slot molding by reducing or eliminating the contact pad EMC flash issue, as described in further detail below. 
       FIG. 4  is a diagram illustrating the application of an upper mold chase  302  to a fluid ejection die  100  according to one example. As shown in  FIG. 4 , a nozzle layer  309  is formed on the front-side surface  307  of the fluid ejection die  100 , and the die  100  and the nozzle layer  309  are positioned on a release tape layer  308 . The release tape layer  308  is positioned on die carrier  310 . Feature  306  of upper mold chase  302  is positioned over fluid ejection die  100  with back-side surface  305  of fluid ejection die  100  facing feature  306 . A plurality of fluid feed holes  406  extend through the fluid ejection die  100 . Although two fluid feed holes  406  are shown in  FIG. 4  to simplify the Figure, the fluid ejection die  100  may include more or less than two fluid feed holes  406 , and the fluid feed holes  406  may be positioned across the length of the fluid ejection portion  106  of the die  100 . The feature  306  seals the fluid feed holes  406  formed in fluid ejection die  100  to protect the fluid feed holes  406  during molding. Release liner  304  is positioned along the bottom surface of feature  306  so as to be positioned between fluid ejection die  100  and feature  306 . 
     One challenge in the slot molding process is keeping the contact pads  108  at the longitudinal ends  148  and  150  of the die  100  free from the EMC flash. The fluid ejection die  100  sits on top of the release tape layer  308 , which, in one example, is a compliant layer that is about 100 um thick. The feature  306  of the upper mold chase  302  contacts and applies force to the fluid ejection portion  106  of the fluid ejection die  100 , but not the end portions  102  and  104  of the die  100 . This force can cause the fluid ejection portion  106  of the die  100  to sink into the release tape layer  308 , and cause the end portions  102  and  104  to tilt up toward the upper mold chase  302  during the molding process. This tilting can cause a gap  408  that results in EMC flash in the regions of the contact pads  108 . 
     The length  404  between the end of the feature  306  and the end  150  of the die  100  is referred to herein as the cantilever length, which plays a role in addressing the contact pad EMC flash issue. Examples of the present disclosure use a short cantilever length  404  to reduce or eliminate the contact pad EMC flash issue. In one example, one or both of the end portions  102  and  104  have a cantilever length  404  that is less than 1.5 mm. In another example, one or both of the end portions  102  and  104  have a cantilever length  404  that is less than 1.3 mm. In yet another example, one or both of the end portions  102  and  104  have a cantilever length  404  that is less than 1.1 mm. 
       FIGS. 5-7  are diagrams illustrating a top view of a portion of the fluid ejection device  200  shown in  FIG. 2  according to one example. As shown in  FIG. 5 , contact pads  108  are positioned on the front side  307  of the die  100 . Slot  204  is positioned on the back side  305  of the die, and is, therefore, shown with dashed lines in  FIG. 5 . The slot  204  has a uniform width or a substantially uniform width along its length. The length between the longitudinal end  148  of the die and the longitudinal end  502  of the slot  204  defines the cantilever length  404 . 
     Extending the length of the feature  306  ( FIG. 4 ) of the upper mold chase  302  results in an increase in the slot length of the slot  204  and a reduction in the cantilever length  404 . Increasing the slot length helps to reduce or eliminate the contact pad EMC flash issue. However, increasing the slot length may result in an increase in the distance between the longitudinal end  502  of the slot  204  and the fluid actuation device  107  ( FIG. 1 ) that is closest to the end  502 . This portion of the slot  204  that extends beyond that fluid actuation device  107  may be referred to herein as dead space, since there are no fluid actuation devices  107  positioned directly above that space. Some examples of the present disclosure modify the shape of the slot  204  near the longitudinal end  502  to reduce the volume of the dead space. Two such examples are shown in  FIGS. 6 and 7  and described below. 
     As shown in  FIG. 6 , the slot  204  includes a narrower slot portion  504  longitudinally extending from a wider slot portion  505  near the longitudinal end  502  of the slot  204 . The narrower slot portion  504  has a uniform width or a substantially uniform width that is less than a uniform width or substantially uniform width of the wider slot portion  505 . In one example, the width of the narrower slot portion  504  is about 25-35% of the width of the wider slot portion  505 . In one example, there are no fluid actuation devices  107  positioned directly above (i.e., along the Z axis in  FIG. 1 ) the narrower slot portion  504 . 
     As shown in  FIG. 7 , the slot  204  includes slot portion  508  longitudinally extending from slot portion  510 , and slot portion  506  longitudinally extending from slot portion  508  near the longitudinal end  502  of the slot  204 . Slot portions  506  and  508  each have a uniform width or a substantially uniform width that is less than a uniform width or substantially uniform width of the slot portion  510 . In one example, the width of the slot portion  508  is about 25-35% of the width of the slot portion  510 , and the width of the slot portion  506  is about 40-60% of the width of the slot portion  510 . In one example, there are no fluid actuation devices  107  positioned directly above (i.e., along the Z axis in  FIG. 1 ) the slot portions  506  and  508 . 
       FIG. 8  is a block diagram illustrating a fluid ejection system  800  according to one example. Fluid ejection system  800  includes a fluid ejection assembly, such as printhead assembly  802 , and a fluid supply assembly, such as ink supply assembly  810 . In one example, printhead assembly  802  may include a fluid ejection device  200  of  FIG. 2 . In the illustrated example, fluid ejection system  800  also includes a service station assembly  804 , a carriage assembly  816 , a print media transport assembly  818 , and an electronic controller  820 . While the following description provides examples of systems and assemblies for fluid handling with regard to ink, the disclosed systems and assemblies are also applicable to the handling of fluids other than ink. 
     Printhead assembly  802  includes at least one printhead or fluid ejection die  100  previously described and illustrated with reference to  FIG. 1 , which ejects drops of ink or fluid through a plurality of orifices or nozzles  107 . In one example, the drops are directed toward a medium, such as print media  824 , so as to print onto print media  824 . In one example, print media  824  includes any type of suitable sheet material, such as paper, card stock, transparencies, Mylar, fabric, and the like. In another example, print media  824  includes media for three-dimensional (3D) printing, such as a powder bed, or media for bioprinting and/or drug discovery testing, such as a reservoir or container. In one example, nozzles  107  are arranged in at least one column or array such that properly sequenced ejection of ink from nozzles  107  causes characters, symbols, and/or other graphics or images to be printed upon print media  824  as printhead assembly  802  and print media  824  are moved relative to each other. 
     Ink supply assembly  810  supplies ink to printhead assembly  802  and includes a reservoir  812  for storing ink. As such, in one example, ink flows from reservoir  812  to printhead assembly  802 . In one example, printhead assembly  802  and ink supply assembly  810  are housed together in an inkjet or fluid-jet print cartridge or pen. In another example, ink supply assembly  810  is separate from printhead assembly  802  and supplies ink to printhead assembly  802  through an interface connection  813 , such as a supply tube and/or valve. 
     Carriage assembly  816  positions printhead assembly  802  relative to print media transport assembly  818 , and print media transport assembly  818  positions print media  824  relative to printhead assembly  802 . Thus, a print zone  826  is defined adjacent to nozzles  107  in an area between printhead assembly  802  and print media  824 . In one example, printhead assembly  802  is a scanning type printhead assembly such that carriage assembly  816  moves printhead assembly  802  relative to print media transport assembly  818 . In another example, printhead assembly  802  is a non-scanning type printhead assembly such that carriage assembly  816  fixes printhead assembly  802  at a prescribed position relative to print media transport assembly  818 . 
     Service station assembly  804  provides for spitting, wiping, capping, and/or priming of printhead assembly  802  to maintain the functionality of printhead assembly  802  and, more specifically, nozzles  107 . For example, service station assembly  804  may include a rubber blade or wiper which is periodically passed over printhead assembly  802  to wipe and clean nozzles  107  of excess ink. In addition, service station assembly  804  may include a cap that covers printhead assembly  802  to protect nozzles  107  from drying out during periods of non-use. In addition, service station assembly  804  may include a spittoon into which printhead assembly  802  ejects ink during spits to ensure that reservoir  812  maintains an appropriate level of pressure and fluidity, and to ensure that nozzles  107  do not clog or weep. Functions of service station assembly  804  may include relative motion between service station assembly  804  and printhead assembly  802 . 
     Electronic controller  820  communicates with printhead assembly  802  through a communication path  803 , service station assembly  804  through a communication path  805 , carriage assembly  816  through a communication path  817 , and print media transport assembly  818  through a communication path  819 . In one example, when printhead assembly  802  is mounted in carriage assembly  816 , electronic controller  820  and printhead assembly  802  may communicate via carriage assembly  816  through a communication path  801 . Electronic controller  820  may also communicate with ink supply assembly  810  such that, in one implementation, a new (or used) ink supply may be detected. 
     Electronic controller  820  receives data  828  from a host system, such as a computer, and may include memory for temporarily storing data  828 . Data  828  may be sent to fluid ejection system  800  along an electronic, infrared, optical or other information transfer path. Data  828  represent, for example, a document and/or file to be printed. As such, data  828  form a print job for fluid ejection system  800  and includes at least one print job command and/or command parameter. 
     In one example, electronic controller  820  provides control of printhead assembly  802  including timing control for ejection of ink drops from nozzles  107 . As such, electronic controller  820  defines a pattern of ejected ink drops which form characters, symbols, and/or other graphics or images on print media  824 . Timing control and, therefore, the pattern of ejected ink drops, is determined by the print job commands and/or command parameters. In one example, logic and drive circuitry forming a portion of electronic controller  820  is located on printhead assembly  802 . In another example, logic and drive circuitry forming a portion of electronic controller  820  is located off printhead assembly  802 . 
     Examples disclosed herein provide the following features: (1) Enable the use of a slot molding process by reducing or eliminating the contact pad EMC flash issue; (2) use a robust mold process that is less sensitive to slot misalignment; (3) eliminate the silicon slotting process, which reduces the die cost; (4) minimize die cracking by avoiding mechanical/laser damage to the silicon; and (5) superior slot sidewall quality/smoothness to avoid particle shedding issues. 
     One example of this disclosure is directed to a fluid ejection device, which includes a fluid ejection die including a first end portion positioned adjacent a first end of the fluid ejection die, and a fluid ejection portion positioned adjacent the first end portion. The fluid ejection die includes a contact pad positioned in the first end portion, and a fluid actuation device positioned in the fluid ejection portion. A carrier is attached to the fluid ejection die. The carrier includes a slot to provide fluid to the fluid actuation device. The slot extends longitudinally along the fluid ejection portion to a first slot end. A length from the first slot end to the first end of the fluid ejection die is less than 1.5 mm. 
     The first end may be a first longitudinal end of the fluid ejection die. The length from the first slot end to the first end of the fluid ejection die may be less than 1.3 mm. The length from the first slot end to the first end of the fluid ejection die may be less than 1.1 mm. The slot may decrease in width from a first width along the fluid ejection portion to a second, smaller width along an end portion of the slot adjacent the first slot end. The fluid ejection die may include a second end portion positioned adjacent a second end of the fluid ejection die. The fluid ejection die may include a contact pad positioned in the second end portion. The slot may extend longitudinally along the fluid ejection portion to a second slot end. A length from the second slot end to the second end of the fluid ejection die may be less than 1.5 mm. The second end may be a second longitudinal end of the fluid ejection die. The carrier may be a rigid carrier. The carrier may be a molded carrier, and the slot may be a molded slot. 
     Another example of this disclosure is directed to a fluid ejection device, which includes a fluid ejection die including a first end portion positioned adjacent a first end of the fluid ejection die, a second end portion positioned adjacent a second end of the fluid ejection die, and a fluid ejection portion positioned between the first and second end portions. The fluid ejection die includes a fluid actuation device positioned in the fluid ejection portion. A rigid carrier is attached to the fluid ejection die. The rigid carrier includes a slot to provide fluid to a back side of the fluid ejection die. The slot extends longitudinally along the fluid ejection portion to a first slot end adjacent the first end portion. A length from the first slot end to the first end of the fluid ejection die is less than 1.5 mm. 
     The fluid ejection die may include a first contact pad positioned in the first end portion, and a second contact pad positioned in the second end portion. The slot may extend longitudinally along the fluid ejection portion to a second slot end adjacent the second end portion, and a length from the second slot end to the second end of the fluid ejection die may be less than 1.5 mm. 
     Yet another example of this disclosure is directed to a method, which includes applying a mold chase to a fluid ejection die, wherein the mold chase at least partially defines at least one cavity, and wherein the mold chase includes a slot forming feature having a first longitudinal end positioned less than 1.5 mm from a first longitudinal end of the fluid ejection die. The method includes filling the at least one cavity with a mold compound to generate a carrier to support the fluid ejection die, wherein the carrier includes a slot defined by the slot forming feature. 
     The slot forming feature may cover fluid feed holes of the fluid ejection die. The slot forming feature may have a second longitudinal end positioned less than 1.5 mm from a second longitudinal end of the fluid ejection die. 
     Although specific examples have been illustrated and described herein, a variety of alternate and/or equivalent implementations may be substituted for the specific examples shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific examples discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.