Patent Publication Number: US-2004055873-A1

Title: Apparatus and method for improved electroforming

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
     [0001] This application claims priority to, and the benefit of, U.S. Provisional Patent Application Serial No. 60/413,083, filed on Sep. 24, 2002, the entire contents of which is hereby incorporated by reference. 
    
    
     
       TECHNICAL FIELD OF THE INVENTION  
       [0002] This invention generally relates to an apparatus and method for reliable, efficient, cost effective and repeatable electroforming of a master, and more particularly, to an apparatus and method for facilitating the uniformity of deposition.  
       BACKGROUND OF THE INVENTION  
       [0003] Electroforming generally involves the electrochemical deposition of a layer of metal or alloy from a suitable electrolyte solution onto a pattern usually comprised of a thin layer of metal substrate. More particularly, the article to be plated (“master”) is typically connected to a cathode and rotated in a cell. An anode is also typically located in the cell and usually consists of a basket containing the metal to be deposited. The cell also commonly contains an electrolytic (plating) solution which most often forms a conductive path between the basket and the part to be plated. Using this configuration, as sufficient direct current flows through the anode, metallic ions are typically pulled from the electrolytic solution surrounding the cathode and are deposited onto the part connected to the cathode. As the process continues, the deposited plating layer typically increases in thickness, while the material in the anode basket replenishes the metallic ions in the electrolytic solution.  
       [0004] The aforementioned plating process is typically used to produce a die (“stamper”, “matrix”or “father”) for injection molding of various products including, inter alia, optical discs. The stamper is typically formed (“grown”) on a metalized glass master which serves as the mandrel. In preparation for optical disc manufacturing, the surface of the glass master contains microscopic pits of varying lengths in a spiral pattern. Optimally, the surface features of the stamper are an inverse duplicate of the pits on the original glass master. Due to the need for extreme accuracy in duplicating these microscopic pits during the manufacture of optical disc media, it is often critical to strictly maintain the precision of the plating process.  
       [0005] To achieve these optimal results, the stamper is typically manufactured with a uniform thickness. Stampers typically have a nominal thickness of 290 microns (0.290 mm)+/−3 microns, such that the thickness of the stamper does not vary by more than 6 microns. However, with market demands for new higher density formats for optical discs, the thickness variation tolerance most likely will require a decreased thickness variation of +/−1 microns. To obtain a decreased thickness variation for the high density stamper, an overall increased precision in many aspects of the electroforming process will be required.  
       [0006] The thickness variation across the surface of the stamper is partly dependent upon the distance between the cathode and anode in the electroforming device. Even though the amount of overall metal typically remains constant, the thickness profile will usually vary according to the anode/cathode distance. When a cathode is moved closer to the anode, increased deposition often occurs in the center of the stamper. Conversely, with increased distance between the cathode and anode, the thickness in the center of the stamper is often reduced. Thus, an optimal orientation of the cathode to anode distance would, in an exemplary embodiment, result in a minimal thickness variation from the center of the stamper to the edge of the stamper. However, a predetermined setting for the anode/cathode distance typically does not guarantee uniform thickness because many other factors often contribute to thickness variations, i.e. fixturing device, size of baffle opening, temperature and pH.  
       [0007] Currently in the industry, electroforming equipment often provides either for no adjustment between the anode and cathode or for crude and course methods for changing the distance between the anode and cathode. For example, adjusting the distance between the anode and cathode by moving the anode basket is often impractical due to the weight of the basket when filled with the raw metals. Moreover, prior art devices which allow for the replacement of the cathode shaft with a cathode shaft of a differing length do not provide continuous adjustability and often require extra labor and excess expensive parts. Therefore, an apparatus and method for efficiently varying the distance between the anode and cathode to compensate for varying parameters.  
       [0008] As discussed above, a stamper is typically formed on a glass master because of the ionic attraction between the anode and cathode. The ionic attraction is developed from an electrical contact on the surface of the glass master. Because the front surface of the glass master is usually the only surface that is metalized, the metalized surface is typically the only point for the electrical contact. However, to prevent damage to the data which is closer to the center of the master, the electrical contact should, in an exemplary embodiment, avoid contact with the center of the master. Fortunately, ample space typically exists for making an electrical contact on the front surface of the master because the standard industry glass master is 120 mm in radius while the information area only extends from the center of the master out to a radius of about 60 mm.  
       [0009] The metalized layer which forms the electrical contact on the surface of the glass master is typically very thin, i.e. approximately 600 angstroms. To pass high current through this thin layer, a very low initial current is typically used, then the current is increased gradually until the metalized layer is built up by the newly deposited metal ions from the electrolytic solution. Building up the metalized layer of the glass master with the metal deposits is often critical because any portions of the glass master which are not plated will usually burn when the current ramps up. Thus, not only is the inner information area of the master plated, but the outer area which serves as the electrical contact is also typically plated. Plating the outside area which serves as the electrical contact usually results in part of the fixture being unintentionally plated. Plating deposits on the fixture is often undesirable because of the extra maintenance required to remove the plating from the fixture and the adverse affects on thickness variation.  
       [0010] A fixture which sufficiently seals off metal parts from the build-up of plating during the plating operation is needed. A non-metallic material is needed which is both compatible with the plating bath and includes adequate mechanical properties. Prior art clamping rings typically include a circular disc with a threaded rim which is threadedly received into the backplate. Threaded fittings are problematic because of variations in the torque applied by individual operators when rotating the clamping ring, thereby resulting in an unequal seal applied around the ring, difficulty in obtaining repeatable compression and variations in the overall contact pressure against the sides of the clamping ring. These prior art clamping rings are typically constructed of a plastic material which is not sufficiently rigid to provide an adequate seal. To obtain an adequate seal, the material should be rigid, but not brittle. Most often, CPVC or polypropylene are used for this process; however, both of these materials are somewhat soft and not dimensionally stable at the temperatures required, i.e. 20-65Â° C. Furthermore, seals on currently available fixtures typically leak and often require substantial maintenance. A fixture with increased performance, less maintenance and easier on and off loading is needed in the electroforming industry.  
       [0011] Moreover, most electroforming systems designed for producing optical disc stampers utilize a rotary cathode head and a stationary anode basket. The arrangement allows the metalized master to rotate with respect to the anode basket while the nickel plating occurs and the stamper grows. The rotation of the cathodic master typically includes the benefit of causing agitation of the solution, and helping to smooth out irregularities in the thickness of deposition of nickel. These irregularities are caused by irregularities in the electric field, which are in turn caused by unevenness in the geometry of the anode basket with respect to the cathodic master. If the anode basket and cathode could be perfectly parallel to each other, then the thickness variation would be much improved. Since the anode basket typically contains nickel anode pellets, which are almost constantly corroding as a necessary part of the process, it is not practical to expect perfect geometry on a continuous basis. Further, the sludge created by the corroding anodes adds to the inconsistency of the anode basket and causes unevenness in the electric field. Additionally, because the nickel anodes are typically continuously corroding within the anode basket, it is important to sufficiently pack and clean the anodes to maintain optimal thickness variation. If the anodes are not sufficiently packed and cleaned, voids and sludge build-up within the basket may have an adverse effect on the thickness variation due to the effect on the electrical field. More details related to electroforming devices may be found in U.S. Pat. Nos. 5,785,826 and 5,843,296 which are attached hereto and incorporated herein by reference.  
       SUMMARY OF INVENTION  
       [0012] The present invention includes an apparatus and method for providing optimal uniformity of deposition during an electroplating process. The system may include an agitating device which is configured to provide agitation to the anode basket, a bias current distributed over a control grid (e.g., titanium mesh) which is disposed between the anode and cathode, wherein the control grid is configured to substantially reduce the variation in the electric field across the cathode, a cathode which includes a backplate having a contact ring wherein the contact ring includes a device configured to increase the pressure of the contact ring against the backplate and/or a cathode mounted on a lead screw for providing axial movement of the cathode along an axis normal to the anode. The entire cathode head may be mounted on a lead screw which, when manually turned, moves the cathode head in or out in relation to the anode basket. Alternatively, the lead screw is driven by a servo motor which is controlled by a computer. 
     
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
     [0013] Exemplary embodiments of the present invention will hereinafter be described in conjunction with the appended drawing figures, wherein like numerals denote like elements and:  
     [0014]FIG. 1 shows an exemplary electroforming apparatus in accordance with the present invention;  
     [0015]FIG. 2 shows an exemplary cathode assembly in accordance with the present invention;  
     [0016]FIG. 3 shows an exemplary backplate in accordance with the present invention;  
     [0017]FIG. 4 a  shows an exemplary backplate  40  for creating a “father”from a glass master in accordance with the present invention;  
     [0018]FIG. 4 b  shows an exemplary backplate  40  for creating a “mother”from a “father”in accordance with the present invention;  
     [0019]FIG. 4 c  shows an exemplary backplate  40  for creating a stamper from a “mother”in accordance with the present invention;  
     [0020]FIG. 5 shows a detailed view of an exemplary contact ring incorporated into a backplate;  
     [0021]FIG. 6 shows an exemplary electroplating device with the location of the cathode and anode exchanged;  
     [0022]FIG. 7 shows an exemplary electroplating device having a vibration motor interfaced with the anode basket;  
     [0023]FIG. 8 shows an exemplary electroplating device having a titanium mesh disposed between a stationary cathode and anode basket;  
     [0024]FIG. 9 shows a more detailed view of an exemplary electroplating device having a titanium mesh disposed between a stationary cathode and anode basket;  
     [0025]FIG. 10 shows a detailed view of the exemplary circuitry that allows for the adjustment of the bias current on the titanium control mesh which is disposed between a stationary cathode and anode basket; and,  
     [0026]FIG. 11 shows an exemplary contact ring having exemplary spring elements. 
    
    
     DETAILED DESCRIPTION  
     [0027] Referring to FIG. 1, an apparatus and method according to various aspects of the present invention is suitably configured to continuously adjust the anode  17 -to-cathode  20  distance thereby controlling uniformity of deposition. With momentary reference to FIG. 3, the apparatus and method according to various aspects of the present invention is also suitably configured for providing a hinged, coated, metal clamping mechanism for efficiently fixturing a master into a backplate  40 . While the manner in which the electroforming is accomplished is described in greater detail below, in general with reference to FIGS. 1 and 3, clamping ring  42  secures master  90  onto backplate  40 , then screw  24  adjusts cathode assembly  20  to an optimal distance from anode basket  17  in preparation for the electroforming process.  
     [0028] With continued reference to FIG. 1, electroforming device  10 , in an exemplary embodiment, includes, cell  15 , anode basket  17  and cathode assembly  20 . In general, anode basket  17  and cathode  20  are, in an exemplary embodiment, aligned and are, in an exemplary embodiment, within cell  15 . Anode basket  17  suitably comprises any device in accordance with the present invention capable of holding a positive voltage potential and allowing metal ions to be liberated from metal pieces contained therein. In accordance with an exemplary embodiment of the present invention, anode basket  17  comprises a titanium basket substantially filled with raw nickel pellets.  
     [0029] With continued reference to FIG. 1, cathode assembly  20  suitably comprises any device in accordance with the present invention capable of holding a negative electrical potential and attracting ions at a rate which is proportional to the voltage potential across anode  17  and cathode  20  for a given resistance between anode  17  and cathode  20 . In accordance with an exemplary embodiment of the present invention, cathode assembly  20  comprises a rotatable head  22  mechanically attached to an adjustable screw  24  and slides upon rails  23 . Backplate  40  is, in an exemplary embodiment, attached to the opposite end of head  22 . Rotatable head  22 , in an exemplary embodiment, rotates at approximately 0-90 rpm.  
     [0030] With reference to FIGS. 1 and 2, cathode assembly  20  is suitably translated along the axis perpendicular to anode basket  17 . More particularly, entire cathode assembly  20  head is suitably mounted on lead screw  24  and rails  23  which, when manually turned at hexagonal bolt head  25 , in an exemplary embodiment, moves cathode assembly  20  in or out along rails  23  in relation to anode basket  17 . In an exemplary embodiment, the total travel of cathode assembly  20  along rails  23  is approximately two inches thereby providing sufficient adjustment to greatly vary the thickness uniformity of the stamper. Furthermore, once adjusted, the positioning of lead screw  24  is suitably highly repeatable, such that the dimension and quality of the parts are highly predictable, thereby increasing productivity.  
     [0031] With reference to FIGS. 1 and 2, in an exemplary embodiment, lead screw  24  is suitably manually rotated at hexagonal bolt head  25 . In an alternative embodiment, lead screw  24  is suitably driven by servo motor  26  which is suitably controlled by computer  28 . Computer  28  suitably monitors the voltage and current in electroforming cell  15  and adjusts lead screw  24  accordingly. Thus, cathode  20 -to-anode  17  distance is alternatively dynamically controlled with feedback from the voltage/current ratio across and through electroforming cell  15 . In an alternative embodiment, computer  28  suitably compensates for the feedback from the voltage/current ratio for the complex changes which take place due to anode  17  material geometric irregularities and flow patterns and micro temperature variations within electroforming cell  15 .  
     [0032] With reference to FIGS. 3 and 4, backplate  40  suitably comprises any device in accordance with the present invention capable of holding a part to be plated. In accordance with an exemplary embodiment of the present invention, backplate  40  includes a substantially circular disc with a front side  41  and a rear side  43 . Backplate  40 , in an exemplary embodiment, includes a clamping ring  42 , a base  46 , a metallic cup  48 , three buttons  50 , O-rings  52  and three recesses  54  substantially equally spaced about backplate  40 . In an exemplary embodiment, base  46  and a metallic cup  48  are substantially circular discs. Base  46  and metallic cup  48 , in an exemplary embodiment, include a rim emanating along their circumference toward front side  41 . Metallic cup  48  is comprised of any suitable material capable of conducting electricity, but, in an exemplary embodiment, is comprised of a metal. Metallic cup  48  is, in an exemplary embodiment, reciprocally received in front side  41  of base  46 , while master  90  is reciprocally received into front side  41  of metallic cup  48 . Buttons  50  are, in an exemplary embodiment, substantially equally spaced substantially near the center of backplate  40 . Buttons  50  are reciprocally received through base  46  and metallic cup  48  and abuts rear side  43  of master  90 , such that when force is applied on rear side  43  of buttons  50 , master  90  is forced away from front side  41  of backplate  40 .  
     [0033] With reference to FIG. 3, to prevent fixture leakage and to reduce maintenance requirements, clamping ring  42 , in an exemplary embodiment, includes a substantially circular ring comprised substantially of a rigid material, i.e. metal, ceramic, and/or the like. Clamping ring  42  is, in an exemplary embodiment, comprised of stainless steel, but clamping ring  42  is alternatively comprised of any suitable metal which is comparatively rigid such as aluminum, titanium and/or ordinary steel. Unlike plastic clamps, the properties of a stainless steel clamp also often enable repeatable compression and contact pressure. Clamping ring  42  suitably provides for a uniform compression of O-rings  52  thereby sealing off the metallic contacts of electroforming device  10 . Any of the aforementioned metallic surfaces would normally contaminate the solution within cell  15 ; however, the metallic surfaces are suitably coated with a non-metallic surface which avoids contact with the plating solution. To avoid plating of clamping ring  42 , clamping ring  42  is, in an exemplary embodiment, coated almost completely with a suitable substantially non-conductive, substantially non-chipping, extremely thin material. The non-conductive material is not only, in an exemplary embodiment, chemically compatible with the plating bath, but also suitably bonds to the metallic part and resists abrasion. The coating is suitably thin so as to avoid substantially increasing the dimensions of clamping ring  42 . Coating of the metallic parts substantially improves the electroforming process by reducing unwanted plating to the fixture.  
     [0034] Prior art clamping rings typically are partially or completely removed from the fixture before loading or unloading the desired part. This process is often cumbersome, time consuming and adds to the risk of damaging the glass master or metal parts. In an exemplary embodiment of the present invention, due to the strength of the stainless steel, a hinge device  60  is suitably attached between clamping ring  42  and backplate  40  to allow rotation of clamping ring  42 . Rotation of clamping ring  42  allows an operator to quickly load or unload parts because of the ease and quickness in opening and closing of backplate  40 .  
     [0035] More particularly, with continued reference to FIG. 3, clamping ring  42 , in an exemplary embodiment, includes hinge device  60  which is pivotally attached to base  46  along a predetermined length of front side  41  of backplate  40 . Clamping ring  42  a plurality of virtually identical locking devices  62  substantially equally spaced about clamping ring  42 . In an exemplary embodiment, clamping ring  42 , in an exemplary embodiment, includes three locking devices  62 . Each locking device  62  consists of a dowel  64  having a first end  65  and a second end  66 . First end  65  of dowel  64  is suitably attached to hinge  68  which is mounted on a predetermined point on clamping ring  42 . Second end  66  of dowel  64  is suitably attached to an object with a wider diameter than dowel  64 , i.e. sphere  70 . Upon rotation of hinge device  60  of clamping ring  42 , clamping ring  42  abuts backplate  40 . By rotation of locking devices  62  into recesses  54 , dowels  64  are, in an exemplary embodiment, reciprocally received into recesses  54  and spheres  70  rest upon rear side  43  of backplate  40  and on ridge of base  46 , thereby providing pressure between clamping ring  42  and front side  41  of backplate  40 .  
     [0036] With reference to FIGS. 3 and 4 a - c , O-rings  52  are, in an exemplary embodiment, set within circular channels of contact ring  80 , base  46  and plastic holder  86 . O-rings  52  provide an increased seal by substantially preventing the plating solution from exiting the cup area and attaching to electroplating device  10 .  
     [0037]FIG. 4 a  shows an exemplary backplate  40  for creating a “father” 94  from a glass master  90 . With reference to FIG. 4 a , contact ring  80  suitably comprises any device in accordance with the present invention capable of transferring current to the metallic surface on the front side  41  of glass master  90 . In accordance with an exemplary embodiment of the present invention, contact ring  80  includes a conducting material such as stainless steel and/or the like. Contact ring  80  is, in an exemplary embodiment, set below rear side  43  of clamping ring  42 , reciprocally received within the rim of base  46 , over front side  41  of the rim of metallic cup  48  and over the outer circumference of master  90 . Additionally, contact ring  80  helps prevent the plating solution from seeping out from the surface of master  90  and onto electroforming device  10 , thereby substantially limiting the region of plating to the metalized glass. Because contact ring  80  covers the outer circumference of master  90 , contact ring  80  oftentimes becomes plated to master  90 , thereby essentially becoming a part of the resulting stamper/father  94 . After removing stamper/father  94  from backplate  40 , contact ring  80  is typically separated from father  94  by a suitable means.  
     [0038] In an exemplary embodiment, contact ring  80  includes a device for increasing the pressure of the contact ring against backplate  40 . In one embodiment, and as shown in FIG. 11, a device for increasing pressure of the contact ring against backplate  40  includes a spring element. In a specific embodiment, spring element  140  may include a component  145  (e.g., rectangular component) cut out of the ring (e.g., on the outer circumference) at certain intervals, wherein component  145  is bendably attached to the contact ring  80  on one edge. In this manner, component  145  forms a resilient extension of contact ring  80  such that component  145  exerts pressure against backplate  40 .  
     [0039] With reference to FIG. 5, when clamping ring  42  exerts pressure against contact ring  80 , the rear surface  43  of contact ring  80  oftentimes experiences an uneven force, i.e. bending, against metallic cup  48  and master  90 . To allow contact ring  80  to substantially evenly abut front side of the rim of metallic cup  48  and the outer circumference of master  90 , a recess  81  is incorporated into rear surface  43  of contact ring  80  such, that contact ring  80  does not contact interface area between metallic cup  48  and master  90 .  
     [0040] With continued reference to FIG. 5, rear  43 , inner  83  surface of contact ring  80  includes beveled edge  82 . Inner surface  83  of contact ring  80 , excluding beveled edge  82 , is also, in an exemplary embodiment, coated with a suitable non-conductive material which substantially prevents plating against inner surface  83  of contact ring  80 . Consequently, beveled edge  82  abuts master  90 , so when plating is deposited around the circumference of master  90 , beveled edge causes a defined perimeter along the edge of the deposit. The defined sloping edge of the deposit allows substantially easier separation of master  90  from contact ring  80 . Beveled edge  82  also suitably allows plating on the thin metalized layer of master  90  along the area which electrically contacts contact ring  80 , thereby preventing the burning of the metalized layer during increases of current through the metalized layer.  
     [0041]FIG. 4 b  shows an exemplary backplate  40  for creating a “mother” 98  from a “father” 94 . Electrical contact for metal-to-metal parts is typically initiated from the back of the part because the entire part, including the back surface, is conductive. With reference to FIG. 4 b , the components of backplate  40  are, in an exemplary embodiment, arranged substantially similar to FIG. 4 a  except that, because the arrangement is, in an exemplary embodiment, established for creating mother  98  from father  94 , father  94  is suitably comprised of a conductive metal so contact ring  80  is not necessary for transferring current to front side  41  of father  94 . Instead, spacer  84  is, in an exemplary embodiment, reciprocally received within metallic cup  48  in place of master  90  and father  94  is, in an exemplary embodiment, set on front side  41  of spacer  84 . In accordance with an exemplary embodiment of the present invention, spacer  84  includes a circular disc comprised of stainless steel or any other suitable conductive alloy.  
     [0042] Additionally, plastic holder  86  is, in an exemplary embodiment, an L-shaped circular ring including a foot  87  and a base  88 . Base  88  of plastic holder  86  is, in an exemplary embodiment, set below rear side  43  of clamping ring  42  and foot  87  wraps around inside edge of clamping ring  42 . Rear side  43  of base  88  is also, in an exemplary embodiment, set over front side  41  of rim of metallic cup  48  and over the outer circumference of father  94  and stainless steel spacer  84 . A finger  89 , in an exemplary embodiment, emanates from rear side  43  of foot  87  and substantially along the entire circumference of foot  87 . Finger  89  is, in an exemplary embodiment, reciprocally received into one of two circular channels  85  within front side  41  of spacer  84 , thereby enabling easy location and stable support for placement father  94 . By using a rear entrance for the electrical contact (from metallic cup  48  through spacer  84  to father  94 ), electroforming device  10  is substantially sealed off from the plating material during the plating process. Thus, the plating material is substantially restricted from contact with electroforming device  10  and maintenance requirements are substantially reduced because of the reduced build-up of metal on electroforming device  10 .  
     [0043]FIG. 4 c  shows an exemplary backplate  40  for creating a stamper (not shown) from “mother” 98 . With reference to FIG. 4 c , the components of backplate  40  are arranged substantially similar to FIG. 4 b  except that mother  98 , in an exemplary embodiment, replaces father  94 . Additionally, plastic spacer  86 , in an exemplary embodiment, includes a longer base  88  such that finger  89  of plastic spacer  86  is reciprocally received into inner circular channel  85  (closer to the center of stainless steel spacer  84  because mother  98  has a smaller diameter) of stainless steel spacer  84  thereby enabling easy location and stable support for placement of father  94 .  
     [0044] As discussed above, because the nickel anodes are typically continuously corroding within the anode basket, it is important to sufficiently pack and clean the anodes to maintain optimal thickness variation. If the anodes are not sufficiently packed and cleaned, voids and sludge build-up within the basket may have an adverse effect on the thickness variation due to the effect on the electrical field. In one embodiment of the present invention, and as more fully disclosed in FIG. 6, the location of the cathode and anode are exchanged. The anode basket is configured as a disc which can be filled with anodes. The cathodic master is mounted stationary and parallel to the cathode. The anode basket rotates thereby providing similar benefits of agitation and relative motion, but with the additional benefit keeping the anodes sufficiently packed throughout the process. Further, the sludge is suitably cleaned during the process by the combination of rotation and flow. As such, the system is a substantially self-packing and self-cleaning system. Other alternative embodiments include rotating both the anode basket and the cathode relative to each other, alternating rotation of the anode basket and cathode relative to each other, simultaneously rotating the anode basket and cathode relative to each other and/or the like.  
     [0045] An alternative embodiment, as shown in FIG. 7, includes mechanically vibrating or otherwise agitating the stationary or rotating anode basket using, for example, a vibrator motor  100  which interfaces with the anode basket, to further pack and clean the anodes during the process. By substantially constantly packing and cleaning the anodes, the system provides repeatable thickness uniformity of the nickel stamper or shim. The mechanical vibration may range in frequency and power depending upon the size and shape of the anode basket and plating cell. For example, ultrasonic frequency ranges provide excellent cleaning as the sludge formed around the anodes is suitably broken up and carried off by the solution flow. By obtaining substantially clean and packed anodes, the electric field across the cathode is more uniform.  
     [0046] In another exemplary embodiment, the system and method includes any suitable hardware and/or software for reducing the variation or flattening out the electric field across the cathode, thereby allowing for better control of the thickness variation across the part. In one embodiment, as shown in FIGS. 8 and 9, the system includes a control grid  110  configured for reducing the variation or flattening out the electric field across the cathode  20 . In another embodiment, at least a portion of the control grid includes a mesh, such as, for example, a mesh comprised of titanium. In one embodiment, the control grid  110  is disposed between the anode basket and cathode. In another embodiment, the control grid  110  is disposed between the anode basket  17  and a stationary cathode  20 . Control grid  110  is disposed next to a device which is suitably configured to substantially filter at least a portion of sludge and substantially limit or restrict at least a portion of the sludge from adhering to the master. In one embodiment, the filter is polypropylene mesh  122 . Polypropylene mesh  122  is disposed next to any suitable device configured for substantially focusing and controlling the flatness of at least a portion of the electrical current field that contacts the cathode. In one embodiment, baffle  124  substantially focuses and controls at least a portion of the flatness of the electrical field.  
     [0047] In another embodiment, the system further includes a circuit configured to distributing a bias current over control grid  110 . As best shown in FIG. 10, in an exemplary embodiment, the negative end of power supply  115  is coupled to and provides a negative current to cathode plate  20 . The positive end of power supply  115  is coupled to and provides a positive current to anode basket  17 . The power supply  115  also is coupled to and provides a positive current to ammeter  117 , which is coupled to resistor  120 , which provides a positive current to titanium mesh  110 , thereby allowing for adjustment of the bias current over titanium mesh  110  and monitoring the adjustments using the ampere readout on ammeter  117 . In one embodiment, the currents are in the 1-2 ampere range which is small compared to the current in the electroplating bath. One skilled in the art will appreciate that the negative and positive ends of the power supply may be switched and the various components may be connected in series or parallel to provide the optimum circuit configuration for the various purposes of the present invention.  
     [0048] It will be apparent to those skilled in the art that the foregoing detailed description of an exemplary embodiment of the present invention is representative of an apparatus and method for a continuously manually adjustable anode  17 /cathode assembly  20  distance and a hinged, coated, metallic clamping mechanism within the scope and spirit of the present invention. Further, those skilled in the art will recognize that various changes and modifications may be made without departing from the true spirit and scope of the present invention. For example, screw  24  used to continuously adjust cathode assembly  20  may suitably be replaced with any configuration capable of adjusting cathode  20 /anode  17  distance. Those skilled in the art will recognize that the invention is not limited to the specifics as shown here, but is claimed in any form or modification falling within the scope of the appended claims. For that reason, the scope of the present invention is set forth in the following claims.