Patent Publication Number: US-2012024471-A1

Title: Nozzle plate for improved post-bonding symmetry

Description:
This application claims priority and benefit as a divisional application of parent U.S. patent application Ser. No. 12/131,953, filed Jun. 30, 2008, having the same title. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The invention relates generally to printheads in printing devices, and, more particularly, to a nozzle plate for bonding to a chip for configuring a printhead of a printing device. 
     2. Description of the Related Art 
     Printing devices commonly referred to as printers, are widely used in offices, in homes and in business enterprises. The printing devices output information displayed on a screen of a data processing device onto a media sheet such as a sheet of paper. The information may be output onto the media sheet by impacting desired information elements, such as characters, onto the media sheet, or alternatively, the printing devices may propel droplets of liquid medium, such as ink, onto the media sheet for outputting the information onto the media sheet. Commonly used printing devices, such as inkjet printers, propel ink droplets onto the media sheet for transferring the information onto the media sheet. The inkjet printers typically use print cartridges having printheads for directing the ink droplets onto the media sheet in patterns corresponding to the information to be printed onto the media sheet. 
     A typical print cartridge of an inkjet printer includes an ink container and a printhead. The printhead includes a chip and a nozzle plate bonded to the chip. The nozzle plate includes a plurality of nozzle holes. During a printing operation, the printhead is moved relative to the media sheet and the ink droplets are released through nozzle holes of the plurality of nozzle holes for transferring the information onto the media sheet. 
     Referring now to drawings and more specifically to  FIG. 1 , a cross-sectional view of a portion of a prior art nozzle plate  10  attached to a chip  12  prior to bonding nozzle plate  10  to chip  12  is depicted. Nozzle plate  10  includes a substrate layer  14  and an adhesive layer  16 . Adhesive layer  16  comprises a first surface (not shown) attached to substrate layer  14  and a second surface (not shown) attached to a planarizing layer  18  for attaching nozzle plate  10  to chip  12 . Planarizing layer  18  provides a planar surface on chip  12  for attaching nozzle plate  10  to chip  12 . A plurality of nozzle holes, such as a nozzle hole  20   a  and a nozzle hole  20   b , may be perforated into substrate layer  14  and adhesive layer  16 . Nozzle holes, such as nozzle hole  20   a  and nozzle hole  20   b , may hereinafter be collectively referred to as a plurality of nozzle holes  20  (not shown). It will be evident to those skilled in the art that  FIG. 1  depicts the cross-sectional view of the portion of nozzle plate  10  and that nozzle plate  10  includes plurality of nozzle holes  20  (not shown) perforated in substrate layer  14  and adhesive layer  16 . 
     Each nozzle hole of plurality of nozzle holes  20  configures an ink flow chamber, such as an ink flow chamber  22   a  and an ink flow chamber  22   b , for receiving ink from an ink container (not shown). A structural configuration, i.e., configuration of wall, of each ink flow chamber defines a flow-feature for respective nozzle hole for directing the ink towards an opening of the respective nozzle hole. The flow-feature for the each nozzle hole is configured to be substantially symmetrical about a central axis of the each nozzle hole for facilitating movement of ink droplets towards the opening. For instance, the flow-feature associated with nozzle hole  20   a  may be substantially symmetrical about a central axis  24   a  for facilitating movement of the ink droplets towards an opening (not shown) of nozzle hole  20   a.    
     Chip  12  includes a plurality of energizing elements such as an energizing element  26   a  and an energizing element  26   b . Energizing elements, such as energizing element  26   a  and energizing element  26   b , will hereinafter be collectively referred to as a plurality of energizing elements  26  (not shown). An example of an energizing element of plurality of energizing elements  26  may be a resistive heating element. Chip  12  is attached to nozzle plate  10  prior to bonding chip  12  to nozzle plate  10 , such that the each nozzle hole is associated with an energizing element. For instance, nozzle hole  20   a  is associated with energizing element  26   a , and, nozzle hole  20   b  is associated with energizing element  26   b.    
     Prior to attaching nozzle plate  10  to chip  12 , nozzle plate  10  may be prestretched, i.e., aligned such that the each nozzle hole of plurality of nozzle holes  20  is configured to align a central axis of the each nozzle hole at a pre-defined distance from a central axis of the energizing element of the plurality of energizing elements associated with the each nozzle hole. On aligning nozzle plate  10  with chip  12 , nozzle plate  10  may be bonded to chip  12  using one or more thermal processes such as Thermal Compression Bonding (TCB), bake and the like. Nozzle plate  10  bonded to chip  12  is depicted in  FIG. 2 . 
       FIG. 2  depicts a schematic depiction of a cross-sectional view of the portion of prior art nozzle plate  10  bonded to chip  12 . Prestretching nozzle plate  10  prior to bonding to chip  12  may substantially align a central axis of the each nozzle hole with a central axis of a corresponding energizing element during the bonding of nozzle plate  10  to chip  12 , such that the each nozzle hole may be centered over the corresponding energizing element. For instance, an alignment of central axis  24   a  of nozzle hole  20   a  is substantially aligned with a central axis (not shown) of energizing element  26   a . During bonding of nozzle plate  10  with chip  12  using thermal processes such as TCB, bake and the like, substrate layer  14  and chip  12  undergo varying levels of expansion. Adhesive layer  16  which is attached to substrate layer  14  at the first surface and attached to chip  12  at the second surface is forced to stretch and conform to the varying levels of expansion, resulting in asymmetrical flow-features for ink flow chambers associated with plurality of nozzle holes  20 . For instance, flow-features for ink flow chambers, such as ink flow chamber  22   a  and ink flow chamber  22   b  corresponding to nozzle hole  20   a  and nozzle hole  20   b , respectively, are asymmetrical respect to respective central axes, on bonding nozzle plate  10  to chip  12 . 
     The asymmetrical flow-features for the each nozzle hole may impact a directionality of ink droplets to be ejected from of plurality of nozzle holes  20 . Moreover, asymmetrical flow-features may also result in expanding a swath area, i.e., an area traced on the media sheet by the printhead, during a particular unidirectional scan of a printhead onto the media sheet. 
     Based on the foregoing, there is a need for compensating for deformation of a nozzle plate during the bonding of the nozzle plate to a chip. Further, there exists a need for configuring a nozzle plate with improved post-bonding symmetry, i.e., substantially symmetrical flow-feature for nozzle holes, subsequent to the bonding of the nozzle plate to the chip. Furthermore, there exists a need to substantially reduce swath area expansion resulting from deformation caused to a nozzle plate during the bonding of the nozzle plate to the chip. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing disadvantages inherent in the prior art, the present invention provides an improved nozzle plate for bonding to a chip and improved methods for bonding a nozzle plate and chip. 
     In one aspect, embodiments of the present invention provide a nozzle plate for bonding to a chip for configuring a printhead of a printing device. The chip comprises a plurality of energizing elements. The nozzle plate comprises a substrate layer, an adhesive layer and a plurality of nozzle holes perforated in the substrate layer and the adhesive layer. The adhesive layer comprises a first surface for attaching to the substrate layer and a second surface capable of bonding to the chip. Each nozzle hole is capable of being associated with an energizing element of the plurality of energizing elements. Each nozzle hole comprises an asymmetric flow-feature configured by ablating at least a portion of a wall of the each nozzle hole prior to bonding the nozzle plate to the chip. The asymmetrical flow-feature for the each nozzle hole, prior to bonding the nozzle plate to the chip, results in a near-symmetrical flow-feature for each nozzle hole once the bonding process has completed. 
     In another aspect, embodiments of the present invention provide a method for preparing a nozzle plate for bonding to a chip for configuring a printhead of a printing device. The chip comprises a plurality of energizing elements. The nozzle plate includes a plurality of nozzle holes, such that each nozzle hole of the plurality of nozzle holes is capable of being associated with an energizing element of the plurality of energizing elements. The method comprises ablating at least a portion of a wall of each nozzle hole for configuring an asymmetrical flow-feature for the each nozzle hole. The nozzle plate may be disposed on the chip for aligning a central axis of the each nozzle hole at a pre-defined distance from a central axis of the energizing element associated with the each nozzle hole. The asymmetrical flow-feature for each nozzle hole, prior to bonding the nozzle plate to the chip, provides a substantially symmetrical post-bonding process flow-feature. 
     The substantially symmetrical flow-feature, i.e., improved post-bonding symmetry, for the each nozzle hole provides the desired directionality to the ink droplets ejected from an opening in the each nozzle hole. In an aspect of the present invention, the at least a portion of the wall of the each nozzle hole may be ablated using laser ablation technique with grayscale mask for configuring the asymmetrical flow-feature for the each nozzle hole. The asymmetrical flow-feature structure of the each nozzle hole in the pre-bonding stage compensates for deformation of a nozzle plate during the bonding of the nozzle plate to the chip and reduces substantially the swath expansion that results from the deformation of the nozzle plate during the bonding process. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and advantages of this present invention, and the manner of attaining them, will become more apparent and the present invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a schematic depiction of a cross-sectional view of a portion of prior art nozzle plate attached to a chip for bonding the nozzle plate to the chip; 
         FIG. 2  is a schematic depiction of a cross-sectional view of a portion of the prior art nozzle plate bonded to the chip; 
         FIG. 3  is a schematic depiction of a cross-sectional view of a portion of a nozzle plate embodying the present invention; 
         FIG. 3A  is a schematic depiction of a cross-sectional view of a nozzle hole of a plurality of nozzle holes of the nozzle plate embodying the present invention; and 
         FIG. 4  is a schematic depiction of a cross-sectional view of a portion of the nozzle plate of  FIG. 3 , bonded to the chip. 
     
    
    
     DETAILED DESCRIPTION 
     It is to be understood that the present invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. 
     In addition, it should be understood that embodiments of the present invention include both hardware and electronic components or modules that, for purposes of discussion, may be illustrated and described as if the majority of the components were implemented solely in hardware. However, one of ordinary skill in the art, and based on a reading of this detailed description, would recognize that, in at least one embodiment, the electronic based aspects of the present invention may be implemented in software. As such, it should be noted that a plurality of hardware and software-based devices, as well as a plurality of different structural components may be utilized to implement the present invention. Furthermore, and as described in subsequent paragraphs, the specific mechanical configurations illustrated in the drawings are intended to exemplify embodiments of the present invention and that other alternative mechanical configurations are possible. 
     Some embodiments of the present invention provide an improved nozzle plate for bonding to a chip and new methods for building a nozzle plate that will be bonded to the chip. The chip comprises a plurality of energizing elements. The nozzle plate comprises a substrate layer, an adhesive layer and a plurality of nozzle holes perforated in the substrate layer and the adhesive layer. The adhesive layer comprises a first surface for attaching to the substrate layer and a second surface capable of bonding to the chip. Each nozzle hole of the plurality of nozzle holes comprises an asymmetric flow-feature configured by ablating at least a portion of a wall of the each nozzle hole. Each nozzle hole is capable of being associated with an energizing element of the plurality of energizing elements and configured to align a central axis of the each nozzle hole at a pre-defined distance from a central axis of the energizing element of the plurality of energizing elements. The asymmetrical flow-feature for each nozzle hole, prior to bonding the nozzle plate to the chip, provides a substantially symmetrical flow-feature for the each nozzle hole on bonding to the chip. 
     Referring now to  FIG. 3 , there is shown a schematic depiction of a cross sectional view of a portion of a nozzle plate  30  embodying the present invention. Further, a method of preparing nozzle plate  30  for bonding to a chip  32  may be described with reference to  FIG. 3 . 
     Nozzle plate  30  includes a substrate layer  34  and an adhesive layer  36 . Adhesive layer  36  comprises a first surface (not shown) for attaching to substrate layer  34  and a second surface (not shown) capable of bonding to chip  32 . Adhesive layer  36  may be used to attach nozzle plate  30  to chip  32  prior to bonding nozzle plate  30  to chip  32 . A planarizing layer  38  may be used to provide a planar surface on chip  32  for attaching nozzle plate  30  to chip  32 . It will be evident to those skilled in the art that substrate layer  34  may be composed of a polymeric material such as a polyimide, a polyester, a fluorocarbon polymer, a polycarbonate and the like. Further, adhesive layer  36  may be composed of phenolic butyral adhesive composite material and such adhesive composite material. In an embodiment of the present invention, chip  32  may be composed of silicon. 
     A plurality of nozzle holes, such as a nozzle hole  40   a  and a nozzle hole  40   b , are perforated into substrate layer  34  and adhesive layer  36 . Nozzle holes, such as nozzle hole  40   a  and nozzle hole  40   b , will hereinafter be collectively referred to as a plurality of nozzle holes  40  (not shown). Each nozzle hole of plurality of nozzle holes  40  configures an ink flow chamber, such as ink flow chamber  42   a  and an ink flow chamber  42   b , for receiving ink from an ink container (not shown). It will be evident to those skilled in the art that the ink may at least be one of a pigment based ink and a dye based ink. Each ink flow chamber is configured at a chip-side of nozzle plate  30  and may be bounded by wall with an increased taper as compared to a wall taper near an opening-side (opposite to the chip-side) of nozzle plate  30 . A structural configuration, i.e., configuration of a wall, of the each ink flow chamber defines a ‘flow-feature’, for a respective nozzle hole, for directing ink towards an opening of the respective nozzle hole. Each nozzle hole of plurality of nozzle holes  40  comprises an asymmetric flow-feature, i.e., asymmetrical structural configuration of walls of an ink flow chamber about a central axis of each nozzle hole. The asymmetric flow-feature for each nozzle hole may be configured by ablating at least a portion of a wall of each nozzle hole, i.e., at least a portion of the wall of an ink flow chamber associated with each nozzle hole. In one embodiment of the present invention, at least a portion of the wall of some or all of the nozzle holes are ablated using laser ablation with a grayscale mask, resulting in an asymmetrical flow-feature structure prior to the nozzle plate being bonded to the heater chip. 
     The grayscale mask may be used to reduce an intensity of energy directed during the laser ablation towards the portion of the wall, hereinafter referred to as an outboard chamber wall, and further may be used to increase intensity towards a portion of the wall opposite to the outboard chamber wall, hereinafter referred to as an inboard chamber wall, thereby creating increased wall angle at the outboard chamber wall. The increased wall angle at the outboard chamber wall of each ink flow chambers creates an asymmetric flow-feature for each nozzle hole. For instance, for nozzle hole  40   a , a portion of an outboard chamber wall  44  of ink flow chamber  42   a  may be laser ablated using the grayscale mask for configuring an asymmetrical flow-feature for ink flow chamber  42   a.    
     Chip  32  includes a plurality of energizing elements such as an energizing element  46   a  and an energizing element  46   b . Energizing elements, such as energizing element  46   a  and energizing element  46   b , will hereinafter be collectively referred to as plurality of energizing elements  46  (not shown). An example of an energizing element may be a heating resistive element. Chip  32  may be attached to nozzle plate  30  prior to bonding chip  32  to nozzle plate  30 , such that the each nozzle hole is associated with an energizing element of plurality of energizing elements  46 . For instance, nozzle hole  40   a  is associated with energizing element  46   a , and, nozzle hole  40   b  is associated with energizing element  46   b . Nozzle plate  30  may be aligned prior to attaching nozzle plate  30  to chip  32  such that a central axis of the each nozzle hole is at a predefined distance from a central axis of a corresponding energizing element. For instance, for nozzle hole  40   a , central axis  48  may be aligned such that central axis  48  lies at a predefined distance from central axis  50  of energizing element  46   a  associated with nozzle hole  40   a . In one embodiment of the present invention, the predefined distance may be based on one or more dimensions of nozzle plate  30  such as a pre-bonding length of nozzle plate  30  and an average length of stretched nozzle plate  30  on completion of the bonding. 
     In some embodiments, the process for using asymmetrical flow-features in a nozzle and an alignment of a nozzle plate  30  such that the central axis of each nozzle hole is at the predefined distance from the central axis of the corresponding energizing element (or heater chip) uses predetermined values (described below) so that the deformation that occurs as the nozzle plate is bonded to the heater chip is compensated for and results in a nozzle plate with a flow feature that is substantially aligned with the center of the heating element. This is explained in more detail below, and is illustrated in  FIG. 3A . 
       FIG. 3A  depicts nozzle hole  40   a  attached to chip  32  for preparing nozzle plate  30  for bonding to chip  32 . It will be evident to those skilled in the art that nozzle hole  40   a  is depicted for exemplary purposes and that the example applies to plurality of nozzle holes  40  for preparing nozzle plate  30  for bonding to chip  32 . As explained in conjunction with  FIG. 3 , the at least a portion of a wall of nozzle hole  40   a  may be laser ablated using the grayscale mask to configure asymmetrical flow-feature for nozzle hole  40   a , and, central axis  48  of nozzle hole  40   a  may be positioned at a predefined distance from central axis  50  of energizing element  46   a  prior to bonding nozzle plate  30  to chip  32 . Nozzle plate  30  may stretch, i.e., expand, during the bonding on account of the thermal processes. Each nozzle hole may no longer be aligned to be centered over corresponding energizing element on account on stretching of nozzle plate  30  during the bonding. Accordingly, the central axis of the each nozzle hole may be aligned at a predefined distance from the central axis of the corresponding energizing element to compensate for stretching of nozzle plate  30  during the bonding, such that the central axis of the each nozzle hole is substantially aligned with the central axis of the corresponding energizing element on the bonding of nozzle plate  30  to chip  32 . 
     The predefined distance for positioning central axis  48  from central axis  50  may be based on one or more dimensions of nozzle plate  30 . An average stretch factor for nozzle plates may be determined using formula 
     
       
         
           
             
               Stretch 
                
               
                   
               
                
               Factor 
             
             = 
             
               x 
               y 
             
           
         
       
     
     Where x denotes average length of a nozzle plate after manufacture and y denotes average length of the nozzle plate after the TCB process and the bake process. For a given length of nozzle plate  30 , a stretch factor may be determined for nozzle plate  30 . Central axis  48  of nozzle hole  40   a  may be positioned at a distance ‘a’ from central axis  50  of energizing element  46   a  to accommodate for expansion of nozzle plate  30  during the bonding. The distance ‘a’ may be based on the stretch factor of nozzle plate  30  determined using the formula. Nozzle plate  30  may expand during the TCB process and the bake process thereby aligning central axis  50  with central axis  48  to configure a position of nozzle hole  40   a  centered on energizing element  46   a  for achieving desired directionality of the ink droplets. 
     A location of central axis  48 , hereinafter referred to as Trestretch Nozzle Center&#39;, at distance ‘a’ from central axis  50  may be used to determine requisite wall angles for configuring asymmetric flow-feature for nozzle hole  40   a.    
     In  FIGS. 3 and 3A , nozzle holes such as nozzle hole  40   a  include increased wall angles towards a chip-side for configuring ink flow chambers such as ink flow chamber  42   a . In the cross-sectional view depicted in  FIG. 3A , edge portions such as a first edge portion  52   a  and a second edge portion  52   b  serve as transition surfaces for transition from a wall angle at a top portion (not shown) of nozzle hole  40   a  to a wall angle, with increased taper, at the chip-side of nozzle hole  40   a . Ink flow chamber  42   a  includes an inboard chamber wall  54  (closer to the Prestretch Nozzle Center) and an outboard chamber wall  56  (farther from the Prestretch Nozzle Center as compared to inboard chamber wall  54  and depicted as outboard chamber wall  44  in  FIG. 3 ). Inboard chamber wall  54  and outboard chamber wall  56  extend from edge portions  52   a  and  52   b  respectively in nozzle hole  40   a  to planarizing layer  38  on chip  32 . Inboard chamber wall  54  includes a first end-portion towards first edge portion  52   a  and hereinafter referred to as inboard first end  54   a , and a second end-portion towards the chip-side and hereinafter referred to as inboard second end  54   b . Outboard chamber wall  56  similarly includes an outboard first end  56   a  and an outboard second end  56   b  configuring end-portions of outboard chamber wall  56  towards second edge portion  52   b  and the chip-side of outboard chamber wall  56 , respectively. A distance between inboard first end  54   a  and outboard first end  56   a  may be referred to as ‘chamber width’ and may be denoted by ‘C w ’. It will be evident to those skilled in the art that a distance from the Prestretch Nozzle Center to inboard first end  54   a  may be equal to a distance from the Prestretch Nozzle Center to outboard first end  56   a  and may be equal to ‘C w /2’. 
     A perpendicular projection from inboard first end  54   a  to planarizing layer  38  may configure a ‘channel height’ of ink flow chamber  42   a  and may be denoted by ‘C h ’. A horizontal distance from inboard second end  54   b  to the perpendicular projection from inboard first end  54   a  may be referred to as ‘inboard chamber taper’ and may be denoted by ‘b’. Similarly, a horizontal distance from outboard second end  56   b  to the perpendicular projection from outboard first end  56   a  onto planarizing layer  38  may be referred to as ‘outboard chamber taper’ and may be denoted by ‘c’. A distance, hereinafter referred to as GAP inboard , inboard, of inboard second end  54   b  from central axis  50 , may be obtained as: 
     
       
         
           
             
               GAP 
               inboard 
             
             = 
             
               b 
               + 
               
                 Cw 
                 2 
               
               + 
               a 
             
           
         
       
     
     A distance of outboard second end  56   b  from central axis  50 , hereinafter referred to as GAP outboard , may be obtained as: 
     
       
         
           
             
               GAP 
               outboard 
             
             = 
             
               c 
               + 
               
                 Cw 
                 2 
               
               - 
               a 
             
           
         
       
     
     To obtain the desired substantially symmetrical, post-bonding flow-feature of nozzle hole  40 , the GAP inboard  should be approximately equal GAP outboard , such that central axis  48  is coincidental with central axis  50  and wall angles of inboard chamber wall  54  and outboard chamber wall  56 , are symmetrical about central axis  48 . 
     Thus, on equating GAP inboard =GAP outboard , the following relation is obtained: 
         c=b+ 2 a    
     For a given value of inboard chamber taper ‘b’ and value of ‘a’ determined using stretch factor for nozzle plate  30 , outboard chamber taper ‘c’ may be determined. Further, using techniques known in the art, channel height ‘C h ’ may be obtained. Channel height ‘C h ’ may be used to obtain a wall angle ‘θ’, subtended by outboard chamber wall  56  with planarizing layer  38 , i.e., with chip  32 , using formula: 
     
       
         
           
             θ 
             = 
             
               
                 tan 
                 
                   - 
                   1 
                 
               
                
               
                 ( 
                 
                   
                     C 
                     h 
                   
                   c 
                 
                 ) 
               
             
           
         
       
     
     Values of wall angle ‘θ’ and outboard chamber taper ‘b’ may then be used to laser ablate a portion of the wall, i.e., outboard chamber wall  56 , for obtaining desired increased wall angle for configuring asymmetrical flow-feature for nozzle hole  40   a . On configuring the asymmetrical flow-features for each nozzle hole of plurality of nozzle holes  40  and aligning nozzle plate  30  such that central axis of each nozzle hole is at a distance ‘a’ from central axis of an energizing element corresponding to the each nozzle hole, nozzle plate  30  may then be bonded to chip  32  using the thermal processes. 
     It will be evident to those skilled in the art that the example explained in conjunction with  FIG. 3A  is described for exemplary purposes, and that nozzle plate  30  may be prepared, i.e., the asymmetrical flow-feature for the each nozzle hole of the plurality of nozzle holes  40  may be configured using different techniques for improving a post-bonding symmetry. An improved post-bonding symmetry, i.e., a substantially symmetrical flow-feature for the each nozzle hole, of nozzle plate  30  for nozzle holes, such as nozzle hole  40   a  is depicted in  FIG. 4 . 
       FIG. 4  is a schematic depiction of a cross-sectional view of a portion of nozzle plate  30  bonded to chip  32 . As explained in conjunction with  FIGS. 3 and 3A , each nozzle hole of plurality of nozzle holes  40  may be configured with asymmetrical flow-features using laser ablation with the grayscale mask, and further attached to chip  32  such that the central axis of each nozzle hole is aligned at a predefined distance from the central axis of respective energizing element, prior to bonding nozzle plate  30  to chip  32 . Nozzle plate  30  may be prepared with asymmetrical flow-features for plurality of nozzle holes  40 , which compensates for at least some of the deformation that occurs during bonding. During the thermal processes, substrate layer  34  of nozzle plate  30  and chip  32  expand to varying degrees, and adhesive layer  36  attached to substrate layer  34  and chip  32  expands to conform to the varying degrees of expansion. 
     As depicted in  FIG. 4 , outboard chamber walls of nozzle holes, such as outboard chamber wall  56  of nozzle hole  40   a , expand on account of expansion of adhesive layer  36  to conform to expansion in substrate layer  34  and chip  32 . Expansion of outboard chamber wall displaces an energizing element such that the central axis of the energizing element such as energizing element  46   a  is substantially coincidental with central axis of respective nozzle hole such as nozzle hole  40   a . Moreover, the expansion of outboard chamber wall  56  configures a substantially symmetrical flow-feature structure along a central axis of nozzle hole and moreso, centered over energizing element. Thus, ablating at least a portion of a wall of the each nozzle hole to create asymmetrical flow-features, prior to the bonding of the nozzle plate to the chip, results in improved post-bonding symmetry of nozzle plate  30 . 
     Nozzle plate  30  as prepared herein includes asymmetric flow-features for each of plurality of nozzle holes  40  perforated in nozzle plate  30 . Furthermore, nozzle plate  30  is disposed such that the central axis of the each nozzle hole is aligned at a predefined distance from the central axis of the energizing element associated with the each nozzle hole. The asymmetric flow-features and the alignment of the nozzle plate  30  compensate for the deformation, i.e., stretching of the nozzle plate  30  during the bonding of nozzle plate  30  to chip  32 . Further, a post-bonding symmetry of the each nozzle hole is improved, i.e., a portion of wall on either side of the central axis of the each nozzle hole are substantially symmetrical and moreso, the each nozzle hole is substantially centered on the corresponding energizing element. The improved post-bonding symmetry improves a directionality of ink droplets ejected from the each nozzle hole. Furthermore, a swath area expansion resulting from deformation caused to nozzle plate  30  during bonding process is substantially reduced. 
     The foregoing description of several methods and an embodiment of the present invention have been presented for purposes of illustration. It is not intended to be exhaustive or to limit the present invention to the precise steps and/or forms disclosed, and obviously many modifications and variations are possible in light of the above description. It is intended that the scope of the present invention be defined by the claims appended hereto