Abstract:
A method for making an electromechanical device including forming an electromechanical transducer that includes a deposited metallic diaphragm, and attaching the electromechanical transducer to a fluid channel substructure.

Description:
BACKGROUND 
       [0001]    The subject disclosure is generally directed to drop emitting apparatus including, for example, drop jetting devices. 
         [0002]    Drop on demand ink jet technology for producing printed media has been employed in commercial products such as printers, plotters, and facsimile machines. Generally, an ink jet image is formed by selective placement on a receiver surface of ink drops emitted by a plurality of drop generators implemented in a printhead or a printhead assembly. For example, the printhead assembly and the receiver surface are caused to move relative to each other, and drop generators are controlled to emit drops at appropriate times, for example by an appropriate controller. The receiver surface can be a transfer surface or a print medium such as paper. In the case of a transfer surface, the image printed thereon is subsequently transferred to an output print medium such as paper. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  is a schematic block diagram of an embodiment of a drop-on-demand drop emitting apparatus. 
           [0004]      FIG. 2  is a schematic block diagram of an embodiment of a drop generator that can be employed in the drop emitting apparatus of  FIG. 1 . 
           [0005]      FIG. 3  is a schematic elevational view of an embodiment of an ink jet printhead assembly. 
           [0006]      FIGS. 4A-4G  are schematic cross-sectional views of structures that illustrate an embodiment of a procedure for making an array of drop generators. 
           [0007]      FIGS. 5A-5E  are schematic cross-sectional views of structures that illustrate another embodiment of a procedure for making an array of drop generators. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]      FIG. 1  is a schematic block diagram of an embodiment of a drop-on-demand printing apparatus that includes a controller  10  and a printhead assembly  20  that can include a plurality of drop emitting drop generators. The controller  10  selectively energizes the drop generators by providing a respective drive signal to each drop generator. Each of the drop generators can employ a piezoelectric transducer. 
         [0009]      FIG. 2  is a schematic block diagram of an embodiment of a drop generator  30  that can be employed in the printhead assembly  20  of the printing apparatus shown in  FIG. 1 . The drop generator  30  includes an inlet channel  31  that receives ink  33  from a manifold, reservoir or other ink containing structure. The ink  33  flows into an ink pressure or pump chamber  35  that is bounded on one side, for example, by a flexible diaphragm  37 . A pair of electrodes  43  that receive drop firing and non-firing signals from the controller  10 , and a piezo element  41  disposed therebetween are attached to the flexible diaphragm  37 . The electrodes  43 , the piezo element  41 , and the flexible diaphragm  37  can be considered a piezoelectric or electromechanical transducer  39  that is actuated by the controller. If the diaphragm  37  is made of a conductive material, it can comprise an electrode of the piezoelectric transducer  39 . Actuation of the electromechanical transducer  39  causes ink to flow from the pressure chamber  35  through an outlet channel  45  to a drop forming nozzle or orifice  47 , from which an ink drop  49  is emitted toward a receiver medium  48  that can be a transfer surface, for example. For convenience, the piezo element  41  and the electrodes  43  can be considered a driver of the electromechanical transducer. 
         [0010]    The ink  33  can be melted or phase changed solid ink, and the electromechanical transducer  39  can be a piezoelectric transducer that is operated in a bending mode, for example. 
         [0011]      FIG. 3  is a schematic elevational view of an embodiment of an ink jet printhead assembly  20  that can implement a plurality of drop generators  30  ( FIG. 2 ) as an array of drop generators. The ink jet printhead assembly includes a fluid channel layer or substructure  131  and a transducer layer or substructure  139  attached to the fluid channel substructure  131 . The fluid channel substructure  131  implements fluid channels and portions of chambers of the drop generators  30 , while the transducer substructure  139  implements the transducers  39  of the drop generators. The nozzles of the drop generators  30  are disposed on an outside surface  131 A of the fluid channel layer  131  that is opposite the diaphragm layer  137 , for example. 
         [0012]    By way of illustrative example, the fluid channel substructure  131  can comprise a laminar stack of plates or sheets, such as stainless steel. 
         [0013]      FIGS. 4A-4G  are schematic cross-sectional views of structures being processed that illustrate a procedure for making an array of drop generators. 
         [0014]    Referring to  FIGS. 4A and 4B , an array of portions of electromechanical transducers is formed. For example, a laminar piezoelectric assembly comprising a piezoelectric slab  141  and a relatively thin metal electrode layer  143  is attached to a rigid carrier  111  using double sided tape  113 , wherein the relatively thin metal electrode layer  143  is on the side of the piezoelectric slab  141  attached to the tape. A further relatively thin metal electrode layer can optionally be on the other side of the piezoelectric slab  141 . The relative thin metal electrode layer or layers can comprise nickel (Ni), for example, and can be formed by a variety of suitable techniques such as vacuum deposition (e.g., sputtering or chemical vapor deposition) or electroless metal plating. The piezoelectric assembly is diced or kerfed through the piezoelectric slab  141  and the electrode layer  143 , for example using a dicing saw as is conventional in the semiconductor industry, to form an array of individual electrode/piezo elements, each element comprising a metal electrode  243  and a piezoelectric element  241 . 
         [0015]    The individual piezo elements can alternatively be formed by screen printing, sol gel deposition, or other deposition techniques. 
         [0016]    The array of electrode/piezo elements of the structure of  FIG. 4B  is then planarized to produce the structure of  FIG. 4C . For example, the kerf regions between the electrode/piezo elements of the array are filled with a polymer  115  such as epoxy or polyvinyl alcohol. Following the polymer fill, the entire array of electrode/piezo elements can optionally be lapped to a desired thickness using conventional lapping or polishing equipment. 
         [0017]    The planarized structure of  FIG. 4C  is subjected to metal deposition to produce a relatively thick metal layer  237  covering the array of individual electrode/piezo elements as schematically illustrated in  FIG. 4D . The structure of  FIG. 4D  generally comprises a plurality of piezoelectric transducers disposed on a carrier substrate, wherein each piezoelectric transducer includes a relatively thick deposited metal diaphragm  237 . By way of illustrative examples, the deposited metal diaphragm  237  can comprise nickel or chromium, and can be produced by electroless deposition, electroplating, or other deposition techniques such as vacuum deposition (e.g., sputtering or chemical vapor deposition). The deposited metal diaphragm layer  237  can have a thickness that is at least about 5 microns, for example in the range of about 5 microns to about 15 microns. As another example, the thickness of the deposited metal layer  237  can be at least about 0.5 to 3 microns. As yet another example, the thickness of the deposited metal layer  237  can be no greater than 30 microns, for example in the range of about 15 microns to about 30 microns. 
         [0018]    An attachment layer  117  is formed on the relatively thick metal diaphragm layer  237  as schematically shown in  FIG. 4E . The attachment layer  117  can comprise a relatively low temperature solder layer formed by electroplating, for example. As another embodiment, the attachment layer  117  can comprise a thermoplastic adhesive layer comprising polyimide, epoxy or acrylic adhesive, for example. As a further embodiment, the attachment layer  117  can comprise a thermoplastic layer such as thermoplastic polyimide. The attachment layer  117  can also comprise a low temperature glass frit. 
         [0019]    As schematically illustrated in  FIG. 4F  by way of illustrative example, the structure of  FIG. 4E  can be attached to a fluid channel layer  131  having pressure chambers  35  by reflowing the relatively low temperature solder layer, or by curing the adhesive layer, as appropriate for the particular implementation. 
         [0020]    The carrier  111  and tape  113  are removed to produce the structure of  FIG. 4G . The planarizing polymer can be left in place, or it can be removed with an appropriate developer, for example. 
         [0021]      FIGS. 5A-5E  are schematic cross-sectional views of structures being processed that illustrate a further procedure for making a plurality of drop generators. 
         [0022]    Referring to  FIG. 5A , a laminar piezoelectric assembly comprising a piezoelectric slab  141  and a relatively thin metal electrode layer  143  is attached to a rigid carrier using double sided tape  113 , wherein the relatively thin metal electrode layer  143  is on the side of the piezoelectric slab  141  attached to the tape. By way of illustrative example, the thin metal electrode layer can comprise deposited nickel. 
         [0023]    The structure of  FIG. 5A  is subjected to metal deposition to produce a relatively thick metal layer  237  covering the piezoelectric slab  141 , as shown in  FIG. 5B . By way of illustrative examples, the deposited metal layer  237  can comprise nickel or chromium, and can be formed by electroless deposition, electroplating, or other metal deposition methods such as vacuum deposition (e.g., sputtering or chemical vapor deposition). By way of illustrative example, the metal layer  237  can have a thickness that is at least about  5  microns, for example in the range of about 5 microns to about 15 microns. As another example, the thickness of the deposited metal layer  237  can be at least about 0.5 to 3 microns. As yet another example, the thickness of the deposited metal layer  237  can be no greater than about 30 microns, for example in the range of about 15 microns to about 30 microns. 
         [0024]    The structure of  FIG. 5B  is diced or kerfed through the metal layer  237 , the piezoelectric slab  141 , and the electrode layer  143  using, for example, a dicing saw to produce an array of individual piezoelectric transducers as shown in  FIG. 5C , each transducer comprising a thin metal portion  243 , a piezoelectric element  241  and a relatively thick deposited metal portion  337 . 
         [0025]    As schematically depicted in  FIG. 5D , the structure of  FIG. 5C  is attached using a suitable adhesive to a metallized polymer diaphragm sub-layer  237 A that is attached to a fluid channel sub-structure  131  having pressure chambers  35  by glue, for example. The metallized polymer diaphragm sub-layer  237 A can comprise polyimide, for example. 
         [0026]    The carrier  111  and tape  113  are removed to produce the structure of  FIG. 5E  wherein the relatively thick deposited metal portions  337  and the metallized polymer diaphragm sub-layer  237 A form the electrodes and diaphragms of the piezoelectric transducers. 
         [0027]    The foregoing can advantageously provide for efficient manufacture of arrays of piezoelectric drop generators, as well as other electromechanical devices. 
         [0028]    The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others. Unless specifically recited in a claim, steps or components of claims should not be implied or imported from the specification or any other claims as to any particular order, number, position, size, shape, angle, color, or material.