US20040055873A1 - Apparatus and method for improved electroforming - Google Patents

Abstract

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.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• 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.[0001]
TECHNICAL FIELD OF THE INVENTION
• 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.[0002]
BACKGROUND OF THE INVENTION
• 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.[0003]
• 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.[0004]
• 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.[0005]
• 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.[0006]
• 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.[0007]
• 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.[0008]
• 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.[0009]
• 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. 20-65° 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.[0010]
• 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.[0011]
SUMMARY OF INVENTION
• 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.[0012]
BRIEF DESCRIPTION OF DRAWINGS
• Exemplary embodiments of the present invention will hereinafter be described in conjunction with the appended drawing figures, wherein like numerals denote like elements and:[0013]
• FIG. 1 shows an exemplary electroforming apparatus in accordance with the present invention;[0014]
• FIG. 2 shows an exemplary cathode assembly in accordance with the present invention;[0015]
• FIG. 3 shows an exemplary backplate in accordance with the present invention;[0016]
• FIG. 4[0017]ashows anexemplary backplate40 for creating a “father”from a glass master in accordance with the present invention;
• FIG. 4[0018]bshows anexemplary backplate40 for creating a “mother”from a “father”in accordance with the present invention;
• FIG. 4[0019]cshows anexemplary backplate40 for creating a stamper from a “mother”in accordance with the present invention;
• FIG. 5 shows a detailed view of an exemplary contact ring incorporated into a backplate;[0020]
• FIG. 6 shows an exemplary electroplating device with the location of the cathode and anode exchanged;[0021]
• FIG. 7 shows an exemplary electroplating device having a vibration motor interfaced with the anode basket;[0022]
• FIG. 8 shows an exemplary electroplating device having a titanium mesh disposed between a stationary cathode and anode basket;[0023]
• FIG. 9 shows a more detailed view of an exemplary electroplating device having a titanium mesh disposed between a stationary cathode and anode basket;[0024]
• 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,[0025]
• FIG. 11 shows an exemplary contact ring having exemplary spring elements.[0026]
DETAILED DESCRIPTION
• Referring to FIG. 1, an apparatus and method according to various aspects of the present invention is suitably configured to continuously adjust the anode[0027]17-to-cathode20 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 abackplate40. While the manner in which the electroforming is accomplished is described in greater detail below, in general with reference to FIGS. 1 and 3, clampingring42 securesmaster90 ontobackplate40, then screw24 adjustscathode assembly20 to an optimal distance fromanode basket17 in preparation for the electroforming process.
• With continued reference to FIG. 1,[0028]electroforming device10, in an exemplary embodiment, includes,cell15,anode basket17 andcathode assembly20. In general,anode basket17 andcathode20 are, in an exemplary embodiment, aligned and are, in an exemplary embodiment, withincell15.Anode basket17 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 basket17 comprises a titanium basket substantially filled with raw nickel pellets.
• With continued reference to FIG. 1,[0029]cathode assembly20 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 acrossanode17 andcathode20 for a given resistance betweenanode17 andcathode20. In accordance with an exemplary embodiment of the present invention,cathode assembly20 comprises arotatable head22 mechanically attached to anadjustable screw24 and slides upon rails23.Backplate40 is, in an exemplary embodiment, attached to the opposite end ofhead22.Rotatable head22, in an exemplary embodiment, rotates at approximately 0-90 rpm.
• With reference to FIGS. 1 and 2,[0030]cathode assembly20 is suitably translated along the axis perpendicular toanode basket17. More particularly,entire cathode assembly20 head is suitably mounted onlead screw24 and rails23 which, when manually turned athexagonal bolt head25, in an exemplary embodiment, movescathode assembly20 in or out alongrails23 in relation toanode basket17. In an exemplary embodiment, the total travel ofcathode assembly20 alongrails23 is approximately two inches thereby providing sufficient adjustment to greatly vary the thickness uniformity of the stamper. Furthermore, once adjusted, the positioning oflead screw24 is suitably highly repeatable, such that the dimension and quality of the parts are highly predictable, thereby increasing productivity.
• With reference to FIGS. 1 and 2, in an exemplary embodiment,[0031]lead screw24 is suitably manually rotated athexagonal bolt head25. In an alternative embodiment,lead screw24 is suitably driven byservo motor26 which is suitably controlled bycomputer28.Computer28 suitably monitors the voltage and current inelectroforming cell15 and adjustslead screw24 accordingly. Thus, cathode20-to-anode17 distance is alternatively dynamically controlled with feedback from the voltage/current ratio across and throughelectroforming cell15. In an alternative embodiment,computer28 suitably compensates for the feedback from the voltage/current ratio for the complex changes which take place due toanode17 material geometric irregularities and flow patterns and micro temperature variations withinelectroforming cell15.
• With reference to FIGS. 3 and 4,[0032]backplate40 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,backplate40 includes a substantially circular disc with afront side41 and arear side43.Backplate40, in an exemplary embodiment, includes a clampingring42, abase46, ametallic cup48, threebuttons50, O-rings52 and threerecesses54 substantially equally spaced aboutbackplate40. In an exemplary embodiment,base46 and ametallic cup48 are substantially circular discs.Base46 andmetallic cup48, in an exemplary embodiment, include a rim emanating along their circumference towardfront side41.Metallic cup48 is comprised of any suitable material capable of conducting electricity, but, in an exemplary embodiment, is comprised of a metal.Metallic cup48 is, in an exemplary embodiment, reciprocally received infront side41 ofbase46, whilemaster90 is reciprocally received intofront side41 ofmetallic cup48.Buttons50 are, in an exemplary embodiment, substantially equally spaced substantially near the center ofbackplate40.Buttons50 are reciprocally received throughbase46 andmetallic cup48 and abutsrear side43 ofmaster90, such that when force is applied onrear side43 ofbuttons50,master90 is forced away fromfront side41 ofbackplate40.
• With reference to FIG. 3, to prevent fixture leakage and to reduce maintenance requirements, clamping[0033]ring42, in an exemplary embodiment, includes a substantially circular ring comprised substantially of a rigid material, i.e. metal, ceramic, and/or the like. Clampingring42 is, in an exemplary embodiment, comprised of stainless steel, but clampingring42 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. Clampingring42 suitably provides for a uniform compression of O-rings52 thereby sealing off the metallic contacts ofelectroforming device10. Any of the aforementioned metallic surfaces would normally contaminate the solution withincell15; however, the metallic surfaces are suitably coated with a non-metallic surface which avoids contact with the plating solution. To avoid plating of clampingring42, clampingring42 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 clampingring42. Coating of the metallic parts substantially improves the electroforming process by reducing unwanted plating to the fixture.
• 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[0034]hinge device60 is suitably attached between clampingring42 andbackplate40 to allow rotation of clampingring42. Rotation of clampingring42 allows an operator to quickly load or unload parts because of the ease and quickness in opening and closing ofbackplate40.
• More particularly, with continued reference to FIG. 3, clamping[0035]ring42, in an exemplary embodiment, includeshinge device60 which is pivotally attached tobase46 along a predetermined length offront side41 ofbackplate40. Clamping ring42 a plurality of virtuallyidentical locking devices62 substantially equally spaced about clampingring42. In an exemplary embodiment, clampingring42, in an exemplary embodiment, includes threelocking devices62. Each lockingdevice62 consists of adowel64 having afirst end65 and asecond end66. First end65 ofdowel64 is suitably attached to hinge68 which is mounted on a predetermined point on clampingring42.Second end66 ofdowel64 is suitably attached to an object with a wider diameter thandowel64, i.e.sphere70. Upon rotation ofhinge device60 of clampingring42, clampingring42 abutsbackplate40. By rotation of lockingdevices62 intorecesses54, dowels64 are, in an exemplary embodiment, reciprocally received intorecesses54 andspheres70 rest uponrear side43 ofbackplate40 and on ridge ofbase46, thereby providing pressure between clampingring42 andfront side41 ofbackplate40.
• With reference to FIGS. 3 and 4[0036]a-c, O-rings52 are, in an exemplary embodiment, set within circular channels ofcontact ring80,base46 andplastic holder86. O-rings52 provide an increased seal by substantially preventing the plating solution from exiting the cup area and attaching toelectroplating device10.
• FIG. 4[0037]ashows anexemplary backplate40 for creating a “father”94 from aglass master90. With reference to FIG. 4a,contact ring80 suitably comprises any device in accordance with the present invention capable of transferring current to the metallic surface on thefront side41 ofglass master90. In accordance with an exemplary embodiment of the present invention,contact ring80 includes a conducting material such as stainless steel and/or the like.Contact ring80 is, in an exemplary embodiment, set belowrear side43 of clampingring42, reciprocally received within the rim ofbase46, overfront side41 of the rim ofmetallic cup48 and over the outer circumference ofmaster90. Additionally,contact ring80 helps prevent the plating solution from seeping out from the surface ofmaster90 and ontoelectroforming device10, thereby substantially limiting the region of plating to the metalized glass. Becausecontact ring80 covers the outer circumference ofmaster90,contact ring80 oftentimes becomes plated tomaster90, thereby essentially becoming a part of the resulting stamper/father94. After removing stamper/father94 frombackplate40,contact ring80 is typically separated fromfather94 by a suitable means.
• In an exemplary embodiment,[0038]contact ring80 includes a device for increasing the pressure of the contact ring againstbackplate40. In one embodiment, and as shown in FIG. 11, a device for increasing pressure of the contact ring againstbackplate40 includes a spring element. In a specific embodiment,spring element140 may include a component145 (e.g., rectangular component) cut out of the ring (e.g., on the outer circumference) at certain intervals, whereincomponent145 is bendably attached to thecontact ring80 on one edge. In this manner,component145 forms a resilient extension ofcontact ring80 such thatcomponent145 exerts pressure againstbackplate40.
• With reference to FIG. 5, when clamping[0039]ring42 exerts pressure againstcontact ring80, therear surface43 ofcontact ring80 oftentimes experiences an uneven force, i.e. bending, againstmetallic cup48 andmaster90. To allowcontact ring80 to substantially evenly abut front side of the rim ofmetallic cup48 and the outer circumference ofmaster90, arecess81 is incorporated intorear surface43 ofcontact ring80 such, thatcontact ring80 does not contact interface area betweenmetallic cup48 andmaster90.
• With continued reference to FIG. 5, rear[0040]43, inner83 surface ofcontact ring80 includes bevelededge82.Inner surface83 ofcontact ring80, excludingbeveled edge82, is also, in an exemplary embodiment, coated with a suitable non-conductive material which substantially prevents plating againstinner surface83 ofcontact ring80. Consequently, bevelededge82 abutsmaster90, so when plating is deposited around the circumference ofmaster90, beveled edge causes a defined perimeter along the edge of the deposit. The defined sloping edge of the deposit allows substantially easier separation ofmaster90 fromcontact ring80. Bevelededge82 also suitably allows plating on the thin metalized layer ofmaster90 along the area which electricallycontacts contact ring80, thereby preventing the burning of the metalized layer during increases of current through the metalized layer.
• FIG. 4[0041]bshows anexemplary backplate40 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. 4b, the components ofbackplate40 are, in an exemplary embodiment, arranged substantially similar to FIG. 4aexcept that, because the arrangement is, in an exemplary embodiment, established for creatingmother98 fromfather94,father94 is suitably comprised of a conductive metal socontact ring80 is not necessary for transferring current tofront side41 offather94. Instead, spacer84 is, in an exemplary embodiment, reciprocally received withinmetallic cup48 in place ofmaster90 andfather94 is, in an exemplary embodiment, set onfront side41 ofspacer84. In accordance with an exemplary embodiment of the present invention,spacer84 includes a circular disc comprised of stainless steel or any other suitable conductive alloy.
• Additionally,[0042]plastic holder86 is, in an exemplary embodiment, an L-shaped circular ring including afoot87 and abase88.Base88 ofplastic holder86 is, in an exemplary embodiment, set belowrear side43 of clampingring42 andfoot87 wraps around inside edge of clampingring42.Rear side43 ofbase88 is also, in an exemplary embodiment, set overfront side41 of rim ofmetallic cup48 and over the outer circumference offather94 andstainless steel spacer84. Afinger89, in an exemplary embodiment, emanates fromrear side43 offoot87 and substantially along the entire circumference offoot87.Finger89 is, in an exemplary embodiment, reciprocally received into one of twocircular channels85 withinfront side41 ofspacer84, thereby enabling easy location and stable support forplacement father94. By using a rear entrance for the electrical contact (frommetallic cup48 throughspacer84 to father94),electroforming device10 is substantially sealed off from the plating material during the plating process. Thus, the plating material is substantially restricted from contact withelectroforming device10 and maintenance requirements are substantially reduced because of the reduced build-up of metal onelectroforming device10.
• FIG. 4[0043]cshows anexemplary backplate40 for creating a stamper (not shown) from “mother”98. With reference to FIG. 4c, the components ofbackplate40 are arranged substantially similar to FIG. 4bexcept thatmother98, in an exemplary embodiment, replacesfather94. Additionally,plastic spacer86, in an exemplary embodiment, includes alonger base88 such thatfinger89 ofplastic spacer86 is reciprocally received into inner circular channel85 (closer to the center ofstainless steel spacer84 becausemother98 has a smaller diameter) ofstainless steel spacer84 thereby enabling easy location and stable support for placement offather94.
• 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.[0044]
• An alternative embodiment, as shown in FIG. 7, includes mechanically vibrating or otherwise agitating the stationary or rotating anode basket using, for example, a[0045]vibrator motor100 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.
• 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[0046]control grid110 configured for reducing the variation or flattening out the electric field across thecathode20. 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, thecontrol grid110 is disposed between the anode basket and cathode. In another embodiment, thecontrol grid110 is disposed between theanode basket17 and astationary cathode20.Control grid110 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 ispolypropylene mesh122.Polypropylene mesh122 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, baffle124 substantially focuses and controls at least a portion of the flatness of the electrical field.
• In another embodiment, the system further includes a circuit configured to distributing a bias current over[0047]control grid110. As best shown in FIG. 10, in an exemplary embodiment, the negative end ofpower supply115 is coupled to and provides a negative current tocathode plate20. The positive end ofpower supply115 is coupled to and provides a positive current toanode basket17. Thepower supply115 also is coupled to and provides a positive current toammeter117, which is coupled toresistor120, which provides a positive current totitanium mesh110, thereby allowing for adjustment of the bias current overtitanium mesh110 and monitoring the adjustments using the ampere readout onammeter117. 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.
• 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[0048]adjustable anode17/cathode assembly20 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, screw24 used to continuously adjustcathode assembly20 may suitably be replaced with any configuration capable of adjustingcathode20/anode17 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.

Claims (18)

1. An apparatus for facilitating the uniformity of deposition in an electroforming process, wherein said apparatus includes an anode basket, a cathode facing said anode and a control grid between said anode and cathode, wherein said control grid is configured to substantially reduce the variation in the electric field across said cathode:

2. The apparatus ofclaim 1, wherein at least a portion of said control grid is comprised of a titanium mesh.

3. The apparatus ofclaim 1, wherein a polypropylene mesh is disposed between said control grid and said cathode, wherein said polypropylene mesh is configured to substantially filter at least a portion of sludge and substantially restrict at least a portion of said sludge from adhering to said cathode.

4. The apparatus ofclaim 1, wherein a baffle is disposed between said control grid and said cathode, wherein said baffle is configured for substantially focusing and controlling the flatness of at least a portion of an electrical current field that contacts said cathode.

5. The apparatus ofclaim 1, further including a circuit which is configured to distribute a bias current over said control grid.

6. The apparatus ofclaim 5, wherein said circuit includes a power supply, an ammeter, a resistor, wherein said power supply is coupled to said cathode and said anode and said power supply is further coupled to said ammeter, which is coupled to said resistor, thereby allowing for adjustment of said bias current over said control grid and monitoring adjustments using said ammeter.

7. An apparatus for controlling the uniformity of deposition in an electroforming process, said apparatus including an anode, a cathode assembly facing said anode, said cathode assembly comprising a backplate having a contact ring, said contact ring includes a device configured to increase the pressure of said contact ring against said backplate.

8. The apparatus ofclaim 7, wherein said device configured to increase the pressure of said contact ring against said backplate includes a spring element.

9. An apparatus for facilitating the uniformity of deposition in an electroforming process, wherein said apparatus includes a rotating anode and at least one of a stationary cathode and a rotating cathode facing said anode.

10. An apparatus for facilitating the uniformity of deposition in an electroforming process, wherein said apparatus includes an anode basket, a cathode facing said anode and an agitating device which is configured to provide agitation to said anode basket.

11. The apparatus ofclaim 10, wherein said agitating device includes a vibrator motor configured to provide vibration in the ultrasonic frequency range.

12. An apparatus for facilitating the uniformity of deposition in an electroforming process, wherein said apparatus includes:

an anode;

a cathode facing said anode;

an agitating device which is configured to provide agitation to said anode basket;

a control grid between said anode and cathode, wherein said control grid is configured to substantially reduce the variation in the electric field across said cathode, said control grid coupled to a circuit which is configured to distribute a bias current over said control grid; and,

said cathode comprising a backplate having a contact ring, said contact ring includes a device configured to increase the pressure of said contact ring against said backplate.

13. The apparatus ofclaim 12 further including said cathode being mounted on a lead screw for providing axial movement of said cathode along an axis normal to said anode to facilitate uniform deposition by optimizing said distance to compensate for factors affecting the uniformity of said electroforming process.

14. The apparatus ofclaim 13 further comprising a servo motor operatively connected to said lead screw, said servo motor communicating with a computer, said computer being adapted to control said axial movement of said cathode assembly.

15. The apparatus ofclaim 12 further including:

said backplate having a base with a recess which holds a metallic cup;

said metallic cup configured for holding a mandrel having a front face to be plated;

said clamping ring pivotally attached to said backplate, said clamping ring configured to hold said mandrel against said backplate; and

a contact ring within said backplate, said contact ring configured to transfer current to said mandrel, said contact ring adapted to abut the front face of said mandrel.

16. The apparatus ofclaim 12, wherein said base has at least one O-ring between said base and said clamping ring, said O-ring attached to said backplate and configured to impede the migration of processing solution between said clamping ring and said base.

17. The apparatus ofclaim 12, wherein said clamping ring includes at least one locking device for providing pressure between said clamping ring and said backplate.

18. The apparatus ofclaim 12, wherein said contact ring includes a beveled inner rim adjacent said front face of said mandrel to simplify separation of said contact ring from said mandrel.

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