Abstract:
A fluid ejecting device including a die including a perimeter defined by a first edge, a second edge opposing the first edge, a third edge, and a fourth edge opposing the third edge, wherein the third and fourth edges are disposed at an angle to the first and second edges to form angular corners, an active area including circuitry for controlling the fluid ejecting device to eject fluid, an inactive area positioned between the perimeter and the active area, and a termination ring encircling the active area, the termination ring including sides extending parallel to the first, second, third, and fourth edges and corners coupling adjacent sides, the corners having a corner radius greater than a first distance between the first edge and one of the sides of the termination ring, and a nozzle to eject fluid.

Description:
BACKGROUND 
       [0001]    Fluid ejection devices, such as printheads in inkjet printing systems, use die to control the ejection of printing fluid onto media. The die can have a termination ring that encompasses an active area on the die. The termination ring serves to protect circuitry in the active area from ionic contamination and moisture penetration. The termination ring also helps prevent cracks and chips from propagating to the active area and can also be referred to as a guard ring. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]      FIG. 1  is a block diagram illustrating an example inkjet printing system including a printhead implemented as an example of a fluid ejection device. 
           [0003]      FIG. 2  is a schematic diagram illustrating a print cartridge implemented as an example of a fluid supply device for use in an inkjet printing system in accordance with aspects of the present disclosure. 
           [0004]      FIG. 3  is a schematic diagram illustrating a top view of a wafer containing a plurality of die in accordance with aspects of the present disclosure. 
           [0005]      FIG. 4  is a schematic diagram illustrating a top view of a die including a termination ring in accordance with aspects of the present disclosure. 
           [0006]      FIG. 5  is an exploded schematic diagram illustrating a termination ring corner in accordance with aspects of the present disclosure in a corner portion of a die. 
           [0007]      FIG. 6  is a schematic illustration of a top view of the die of  FIG. 4  having corner chips in accordance with aspects of the present disclosure. 
           [0008]      FIG. 7  is a flow diagram of a method of manufacturing a die for a fluid ejection device in accordance with aspects of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    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. 
         [0010]    In general, printheads implemented as examples of fluid ejection devices can use an end connect design including flex traces or bond wires connecting to bond pads located along a narrow die edge at a top and a bottom of a die. To protect these connections from ink and moisture attack, bond beams/wires are covered by a bead of encapsulant, which generally extends to cover the entire top and bottom edges of the die including the corners. The encapsulant protects the corners of the die from chipping after application of the encapsulant and reduces the probability that chips occurring prior to encapsulation will be exposed to moisture and result in reduced die reliability. Some die, such as thermal ink jet (TIJ) die, are used in an array architecture and use a side connect bonding scheme (i.e., the die is configured for electrical connection along at least one side of the die). As a result, the corners of these die are not covered by bond beam encapsulant and remain unprotected throughout the manufacturing process and life of the die. On these TIJ die, corner chipping and cracking damage can pose an increased reliability risk as compared to end connect die. 
         [0011]      FIG. 1  is a block diagram illustrating one example of an inkjet printing system  100 . In the illustrated example, inkjet printing system  100  includes a print engine  102  having a controller  104 , a mounting assembly  106 , one or more replaceable fluid supply devices  108  (e.g., print cartridges), a media transport assembly  110 , and at least one power supply  112  that provides power to the various electrical components of inkjet printing system  100 . Inkjet printing system  100  further includes one or more printheads  114  (i.e., fluid ejection devices) that eject droplets of ink or other fluid through a plurality of nozzles  116  (also referred to as orifices or bores) toward print media  118  so as to print onto print media  118 . In one example, printhead  114  can be an integral part of an ink cartridge supply device  108 , while in another example, printhead  114  can be mounted on a print bar (not shown) of mounting assembly  106  and coupled to a supply device  108  (e.g., via a tube). Print media  118  can be any type of suitable sheet or roll material, such as paper, card stock, transparencies, Mylar, polyester, plywood, foam board, fabric, canvas, and the like. 
         [0012]    In one example, as discussed below and illustrated herein, printhead  114  comprises a thermal inkjet (TIJ) printhead that ejects fluid drops from nozzle  116  by passing electrical current through a thermal resistor ejection element to generate heat and vaporize a small portion of the fluid within a firing chamber. Printhead  114 , however, is not limited to being implemented as a TIJ printhead. For example, printhead  114  can be implemented as a piezoelectric inkjet (PIJ) printhead that uses a piezoelectric material ejection element to generate pressure pulses to force fluid drops out of nozzle  116 . In either example, nozzles  116  are typically arranged in one or more columns or arrays along printhead  114  such that properly sequenced ejection of ink from the nozzles causes characters, symbols, and/or other graphics or images to be printed on print media  118  as printhead  114  and print media  118  are moved relative to each other. 
         [0013]    Mounting assembly  106  positions printhead  114  relative to media transport assembly  110 , and media transport assembly  110  positions print media  118  relative to printhead  114 . Thus, a print zone  120  is defined adjacent to nozzles  116  in an area between printhead  114  and print media  118 . In one example, print engine  102  is a scanning type print engine. As such, mounting assembly  106  includes a carriage for moving printhead  114  relative to media transport assembly  110  to scan print media  118 . In another example, print engine  102  is a non-scanning type print engine. As such, mounting assembly  106  fixes printhead  114  at a prescribed position relative to media transport assembly  110  while media transport assembly  110  positions print media  118  relative to printhead  114 . 
         [0014]    Electronic controller  104  typically includes components of a standard computing system such as a processor, memory, firmware, and other printer electronics for communicating with and controlling supply device  108 , printhead(s)  114 , mounting assembly  106 , and media transport assembly  110 . Electronic controller  104  receives data  122  from a host system, such as a computer, and temporarily stores the data  122  in a memory. Data  122  represents, for example, a document and/or file to be printed. As such, data  122  forms a print job for inkjet printing system  100  that includes one or more print job commands and/or command parameters. Using data  122 , electronic controller  104  controls printhead  114  to eject ink drops from nozzles  116  in a defined pattern that forms characters, symbols, and/or other graphics or images on print medium  118 . 
         [0015]      FIG. 2  is a schematic illustration of one example of a print cartridge  200  implemented as an example of fluid supply device  108  for use in inkjet printing system  100 . Print cartridge  200  includes a cartridge body  202 , printhead  114 , and electrical contacts  204 . Cartridge body  202  supports printhead  114  and electrical contacts  204  through which electrical signals are provided to activate ejection elements (e.g., resistive heating elements) that eject fluid drops from select nozzles  116 . Fluid within cartridge  200  can be any suitable fluid used in a printing process, such as various printable fluids, inks, pre-treatment compositions, fixers, and the like. In some examples, the fluid can be a fluid other than a printing fluid. Cartridge  200  can contain a fluid supply within cartridge body  202 , but can also receive fluid from an external supply (not shown) such as a fluid reservoir connected through a tube, for example. 
         [0016]      FIG. 3  schematically illustrates a top view of a wafer  300  containing a plurality of die  310   a - f  useful for printhead  114  in accordance with aspects of the present disclosure. In one example, wafer  300  is formed of silicon substrate and, in some implementations, can comprise a crystalline substrate such as doped or non-doped monocrystalline silicon or doped or non-doped polycrystalline silicon. Other examples of suitable substrates include gallium arsenide, gallium phosphide, indium phosphide, glass, silica, ceramics, or a semiconducting material. During a cutting process, wafer  300  is cut (e.g., sawed or otherwise suitably cut) along cut lines  320  to separate each of die  310   a - f . The resulting cut edges define perimeter sides of each die  310   a - f . The perimeter sides define a generally rectangular or square shape with the sides intersecting to form angular corners of die  310   a - f . The corners are particularly vulnerable to chipping damage. 
         [0017]    Each die  310   a - f  includes a termination ring  330  encompassing an active area  340 . Termination ring  330  is formed between cut lines  320  and a periphery, or inactive area  350  of each die  310  on wafer  300 . In the example of  FIG. 3 , termination ring  330  completely surrounds active area  340 . Active area  340  contains circuitry (see, e.g.,  FIG. 4 ) for controlling printhead  114 . Termination ring  330  can provide electrostatic discharge (ESD) protection and terminates the thin film layers close to the die edges. Termination ring  330  helps protect active area  340  from ionic contamination and moisture penetration that can result from chips or other damage to die  310  edges, for example. Termination ring  330  can also help prevent cracks or chips originating from one of the edges formed along cut line  320  of die  310  from propagating into active area  340 . The cracks or chips can occur during the cutting process or stress testing, for example. Thermal ink-jet (TIJ) dies, for example, are exposed to ink and moisture throughout their life and the design and location of termination ring  330  can limit chip damage that reaches or extends past termination ring  330  that can lead to reduced printhead reliability resulting from moisture related attack of the borophosphosilicate glass (BPSG) and/or metal layers in termination ring  330  that can eventually propagate past termination ring  330  and into active area  340  including circuitry. 
         [0018]    Termination ring  330  can be formed by alternatively laminating dielectric layers and metal layers which interconnect by vias through the dielectric layers. Termination ring  330  serves to properly terminate the thinfilm layers to minimize the risk of chips and cracks from the cutting process and other manufacturing processes can expose the internal die thinfilms and circuitry to moisture ingress and attack. When a wafer is cut along cut lines  320 , termination ring  330  can reduce or prevent unintended stress cracks from occurring along cut lines  320  to the integrated circuits within active area  340 . Also, termination ring  330  can reduce or prevent moisture penetration or chemical damage like acid, alkaline containing or diffusion of contaminating species. 
         [0019]    In a general example, a die for a fluid ejection device is defined by a perimeter defined by edges (e.g., cut edges) intersecting at corners. The general example die can include a termination ring encompassing an active area. The termination ring is generally rectangular and has a shape similar to the perimeter. The termination ring is often located within several microns of the edges that define the perimeter of the die. The active area includes a variety of circuitry. As the size of die is small, an inactive area of the die encompassing the termination ring is often minimized to maximize the area available for the circuitry in the active area. Circuitry is often positioned closely together and occupies the majority of the active area due to the limited space on the die. An inactive area of the general example die can be narrow, having a distance (x 1 ) between one of the edges and one of the sides of the termination ring extending along the associated edge. The inactive area is also relatively narrow adjacent to corners where corners of termination ring can be angular or slightly rounded (with radius r 1 ) in order to closer mirror the corners of the die and maximize the active area. In one general example, distance x 1  is 30 μm and the width of the cut lines is 60 μm. As a result, in this general example, corner chips can have a significant probability of intersecting the termination ring where they can lead to reduced reliability, especially where corners are exposed through the life of the die. 
         [0020]      FIG. 4  illustrates a schematic top view of a die  510  in accordance with aspect to the present disclosure. Die  510  is defined by a perimeter  520  defined by edges  522  intersecting at corners  524 . Die  510  includes a termination ring  530  encompassing, or surrounding, an active area  540 . Active area  540  includes a variety of circuitry  550 . Circuitry  550  can also be positioned closely together and can occupy a majority of active area  540  due to the limited space on die  510 . 
         [0021]    Termination ring  530  is generally rectangular having sides  532  and corners  534 . In one example, termination ring  530  is centered between edges  522  on die  510 . At least one of corners  534  has a radius r 2 . In one example, each of corners  534  has radius r 2 . In one example, radius r 2  is at least 90 μm. For example, radius r 2  of corner  534  can be between 90-100 μm. Sides  532  extend generally parallel to edges  522 . In the example of  FIG. 4 , termination ring  530  is pulled back, or recessed from corner(s)  524  and edges  522  of die  510  a greater distance than a termination ring is generally recessed in typical die for a fluid ejection device. In one example, termination ring  330  can be beveled at corners  534 . 
         [0022]    Distances between termination ring  530  and edges  522  and corners  524  are selected to serve as a physical barrier to reduce or prevent chip and crack propagation into active area  540 . In one example, the distance x 3  between the corner  524  of die  510  and corner  534  of termination ring  530  positioned adjacent the respective corner  510  is at least three times the distance x 2  between one of edge  522  of die and side  532  of termination ring  530  adjacent to the associated edge  522 . In another example, a distance x 3  between one of angular corners  524  of die  510  and rounded corner  534  of termination ring  530  positioned adjacent the respective angular corner  524  is more than twice distance x 2  between one of perimeter edges  522  of die  510  and one of sides  532  of termination ring  530  extending adjacent the one of perimeter edges  522 . With additional reference to  FIG. 3 , in one example, a width of cut lines  320  is 70 μm resulting in a wider inactive area  560  between termination ring  530  and die edge  522 . For example, an additional 5 μm of silicon substrate is provided between termination ring and sawn die edge  522 . Additionally, circuitry  550 ,  555  is positioned such that the termination ring  530  can be rounded at corners  534 . This increased inactive area can reduce the risk of chipping damage and improve robustness against die edge damage. 
         [0023]      FIG. 5 , is a schematic illustration of a corner of a die  610  including a termination  630 , in accordance with the present disclosure.  FIG. 5  also diagrammatically illustrates in dashed lines an overlay of where a termination ring  430  of a typical die for a fluid ejection device is generally located. As illustrated in  FIG. 5 , corner radius r 3  of termination ring  630  is greater than corner radius r 1  of diagrammatically illustrated termination ring  430 . An active area  640  including circuitry  650  is encompassed by termination ring  630 . Termination ring  630  does not mirror a corner  624 , unlike diagrammatically illustrated termination ring  430  that closely mirrors corner  624 . A distance from a rounded corner  634  to angular corner  624  is correspondingly increased with termination ring  630 . In other words, radius r 3  of corner  634  of termination ring  630  creates an inactive area  660  outside termination ring  630  that is greatest at corner  624 . Active area  640  inside termination ring  630  is reduced correspondingly to the increased inactive area  660 . The larger radius r 3  of termination ring  630  at adjacent corner  624  creates an increased inactive area  660  at corner  624  where chips often occur. 
         [0024]      FIG. 6  illustrates die  510  of  FIG. 4  including example chips  570   a ,  570   b  on corners  524   a ,  524   b . Due to the fragility of the sharp, angular corners  524  of die  510 , chips  570   a ,  570   b  occurring at corners  524  can extend  10 &#39;s of microns into die  510  from edge  522 . Due to the crystalline nature of silicon used in the substrate of die  510 , chips  570   a ,  570   b  often occur having a similar size. Chips  570   a ,  570   b  can remove corner sections of die  510  without intersecting termination ring  530 . Chips  570   a ,  570   b  along corners  524  and edges  522  of die  510  are generally small, extending only a few microns toward a termination ring  530  and have a relatively low probability of intersecting termination ring  530  and exposing the thinfilms and circuitry  550 ,  555  to moisture attack. Chips  570   a ,  570   b  are contained within inactive area  560  are benign defects. In other words, chips  570   a ,  570   b  do not extend within active area  540  and do not affect the reliability of die  510  and the functionality of circuitry  550 ,  555 . 
         [0025]      FIG. 7  illustrates an example method  700  of manufacturing a die for a fluid ejection device. At  710 , a wafer as a substrate including a plurality of die circuitry and a plurality of termination rings is fabricated. Each termination ring generally defines a rectangular boundary having rounded corners and surrounds an active area where the die circuitry is positioned. At  720 , the wafer is cut into individual die along cut lines. Each individual die includes one of the plurality of termination rings encompassing and surrounding the respective die circuity within the respective active area. Portions of the termination rings extend generally parallel to the cut lines and intersect to form rounded corners having radiuses greater than a first distance from a first cut line to a portion of the termination ring extending generally parallel to the cut line. The cut lines are formed a distance from the termination ring and define inactive areas encompassing the termination ring on each of the respective die. 
         [0026]    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.