Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
  • C25D17/10—Electrodes, e.g. composition, counter electrode
  • C25D17/12—Shape or form
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49002—Electrical device making
  • Y10T29/49117—Conductor or circuit manufacturing

Definitions

• Electrodeposited copper foil is generally formed by immersing a rotating drum cathode in an electrolyte solution containing copper ions.
• a curved anode of electrically conductive material is also immersed in the electrolyte solution and positioned adjacent the drum cathode to define an interelectrode gap therebetween.
• Copper foil is formed on the rotating drum cathode. The electrodeposited foil is continually removed from the drum cathode as it emerges from the electrolyte solution so as to permit continuous foil production.
• insoluble anodes may be used since non-uniform dissolution of soluble anodes may occur.
• Lead anodes are widely used in electroforming metal foils, but while lead anodes are commonly referred to as insoluble anodes, they are not truly insoluble.
• lead dioxide is produced at the surface of the anode and oxygen is liberated from the lead oxide surface rather than at the lead surface. Through continued usage, the lead dioxide is generally dissolved and may flake off thereby increasing the spacing between the anode and cathode. Thus, the lead anodes are at least slightly soluble in the electrolyte.
• Dimensionally stable electrodes are well known. The term "dimensionally stable" means that the electrodes are not consumed during use.
• a dimensionally stable electrode comprises a substrate and a coating on surfaces of the substrate.
• U.S. Patent No. 4,318,794 discloses a radial electrolytic cell for metal winning.
• a plurality of dimensionally stable, elongated, anode strips are positioned in the cell electrolyte spaced from a cylindrical cathode.
• the anode strips extend, longitudinally, parallel to the axis of the cathode.
• Each strip is relatively narrow in width compared to its length, being co-extensive, circumferentially, with only a small surface or arc of the cathode.
• the tolerances to which each strip is rolled become less critical.
• the strips are about 2-20 inches in width.
• apparatus for the preparation of metal foil which apparatus includes a stationary arcuate anode placed concentrically with a rotating cathode drum.
• the anode includes a plurality of circumferentially arranged electrode segments formed of a valve metal material and coated with a platinum group metal or oxide coating. The segments are removably attached and electrically connected to a base plate.
• the anode is provided in this manner partly for dimensional maintenance of the anode.
• the anode assembly is comprised of an anode base having a non-conductive surface.
• the base as a cradle, has a predetermined contour facing the cathode and a plurality of deformable metallic anodes.
• the anodes are deformed into engagement with the non-conductive surface. It would be desirable to provide an electrode assembly which achieves a very uniform fixed gap in a channel between a rotating cathode drum and a stationary arcuate anode spaced concentrically from the drum.
• the assembly includes a metallic lead element as a substrate, the assembly reduces or eliminates lead contamination in electrolyte maintained in the electrode gap.
• the invention is directed to the method of providing an assembly for the electrodeposition of a metal, which method is particularly adapted for refurbishing the assembly, the assembly having a cathode drum rotating about an axis and partially immersed in an electrolyte, which assembly also has a curved lead anode used in metal electrodeposition, such anode being spaced apart from the cathode with a gap maintained between the cathode and anode for containing the electrolyte, which method comprises: machining the lead anode to a machined radius and a freshly machined face to establish a curved support structure of predetermined surface configuration; providing holes in the machined face of the lead support structure of machined radius; providing a thin and resilient, solid and insoluble, light gauge flexible anode sheet with a broad active anode front face and broad back face, the sheet anode comprising a multitude of side-
• the invention is directed to an apparatus for electrodepositing a metal, the apparatus having a cathode drum rotating about an axis and providing an outer plating surface partially immersed in electrolyte, a curved anode spaced from the cathode providing a gap having such electrolyte therein, the anode having an active anode surface and a support structure, the improvement comprising: a perforated, stationary and rigid lead support structure, at least slightly soluble in the electrolyte, and having a curved upper surface of a first radius; a thin and resilient, solid and insoluble light gauge flexible anode sheet having a broad active anode front face and broad back face, such light gauge sheet anode comprising a multitude of side-by-side, generally elongated thin and narrow strip anodes, each of which has a formed first configuration of larger radius than the radius of the curved lead support structure, and a supported second configuration on the support structure which is different from the formed first configuration; fastening means affixed to
• the invention is directed to a thin strip anode of light gauge strip that is a precurved anode sheet. More particularly, in this aspect, the invention is directed to a generally elongated, thin and resilient, solid and insoluble light gauge flexible metallic strip anode adapted to be detachably fixed to the curved upper surface of a stationary and rigid lead support structure, with a multitude of the strip anodes forming a flexible anode sheet engaged on the curved upper surface of the lead support structure, which lead support structure is spaced apart from a cylindrical roller cathode that is rotatable about a horizontal axis, such strip anode comprising: a generally elongated, thin, narrow and resilient, solid and insoluble, light gauge and flexible metallic strip that is at least substantially curved in the width dimension of the strip to generally conform to the curved upper surface of the lead support structure, with the curving in the width direction provided by a series of chords separated on an active front face of the strip anode by break Iines and on an
• the invention is most particularly useful where a curved lead anode that has already been used in metal electrodeposition is machined to a new radius as well as the above-mentioned freshly machined face and then the flexible anode is flexed onto the face of the new radius.
• the invention is further directed to an electrode structure comprising a lead anode as a support structure having a broad, curved upper face and a multitude of strip anodes detachably secured to the curved upper face of the support structure, wherein the lead anode curved upper face is coated.
• a lead anode as a support structure having a broad, curved upper face and a multitude of strip anodes detachably secured to the curved upper face of the support structure, wherein the lead anode curved upper face is coated.
• BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a used lead electrode for serving as a support structure according to the present invention.
• Fig. 2 is a section view depicting an anode of light gauge strip flexed in its width dimension for conforming to the curved upper surface of the support structure of Fig. 1.
• Fig. 2A is a section view of an anode of light gauge strip that is precurved in its width dimension as a series of chords.
• Fig. 3 is a plan view of the front face of a generally elongated light gauge sheet anode strip with optional bias cut anode segments along the anode length.
• Fig. 4 is a cross-sectional view showing the initial engagement of a light gauge strip anode in contact with a portion of the support structure of Fig. 1.
• Fig. 5 is a cross-sectional view of the elements of Fig. 4 with the light gauge strip anode pulled into conforming engagement with the support structure.
• Fig. 6 is a perspective schematic view of a portion of an electrolytic cell having the narrow strip anodes of Fig. 2 in place on the support structure of Fig. 1.
• the electrolytic cells employing the present invention are particularly useful in an electroplating process in which a deposit of a metal, such as copper, is made onto a rotating cathode drum.
• a deposit of a metal such as copper
• An example of such a process is the production of electrodeposited foil, for instance copper foil used in the production of printed circuits for electronic and electrical equipment.
• the copper foil is electrodeposited from an electrolyte onto the surface of a rotating cathode, such as a cathode drum that can be rotatably mounted on an axial supporting shaft that spaces the drum apart from an anode.
• the foil emerges from the electrolyte and is stripped from the surface of the cathode, and is wound in the form of a coil onto a roll, ail in a known manner.
• electrolytic cells can also be used in other electrodeposition processes, including electrowinning, e.g., of copper or cobalt, and including for instance plating other metals such as zinc, cadmium, chromium, nickel, tin and metal alloys such as nickel-zinc, onto a substrate, an example of which is electrogalvanizing in which zinc is continuously galvanized onto a strip fed from a steel coil.
• electrowinning e.g., of copper or cobalt
• plating other metals such as zinc, cadmium, chromium, nickel, tin and metal alloys such as nickel-zinc
• Another electrodeposition process is surface treating foil, for instance copper foil, previously manufactured.
• a cell utilizing the present invention can also be used in non-plating processes such as electromachining, electrofinishing, anodizing, electrophoresis, and eiectropickling.
• the anode of the electrolytic cell is a lead anode, including anodes of lead and alloys of lead, such as lead alloyed with tin, silver, antimony, calcium and strontium.
• Such an anode is usually somewhat soluble in the electrolyte of the cell, e.g., at least slightly soluble, and this solubility can lead to contamination of the cathode deposit and variation in the anode-to-cathode gap during operation, providing undesirably elevated operating voltages.
• Fig. 1 depicts an electrode structure 10, which will serve in the electrodeposition apparatus as a support structure 10, comprised of a lead plate 5.
• the plate 5 may be a single, solid plate.
• the plate 5 is a lead anode which is to be placed in service, and usually has been used in service, in an electrolytic cell such as in an above described electroplating process.
• the plate 5 provides an arcuate, or curved, electrode upper surface 6, sometimes referred to herein as the "face" 6. Particularly for a used lead plate 5, this is a freshly machined face 6 machined to a radius of a predetermined surface configuration.
• This curved electrode upper surface 6 can thus be configured concentrically with a cylindrical cathode drum (not shown).
• the drum rotates about a center axis so that the outer surface of the drum maintains a constant gap with the face 6 of the plate 5.
• the plate 5 is of lead or lead alloy, as has been described hereinabove.
• a power supply means (not shown) is connected to the plate 5 through a busbar 2.
• a thin and resilient strip anode 12 can be rolled to a flat, or to a near flat configuration having a larger radius than the surface 6, as shown by the solid Iines in Fig. 2.
• This representative strip anode 12 has a short stud 13, in the nature of a boss, affixed as by threading, or other conventional metal-to-metal bonding means such as welding, e.g., friction, TIG or resistance welding, to the back face of the strip anode 12.
• the resilient strip anode 12 is thin and of a light gauge sheet, which sheet can be one to 20 millimeters (mm) thick.
• the strip anode 12 is flexible and can be flexed in its width direction into the configuration shown in phantom Iines in Fig. 2. These thin and resilient strip anodes 12 may be referred to herein for convenience as “light gauge strips” 12, or “flexible strips” 12. Alternatively, the strip anode 12 may be rolled to a target radius, providing in rolling a configuration for the anode shown in the phantom Iines in Fig. 2, which target radius is to at least substantially match or exceed the curvature of the surface 6 on a lead support structure 10 (Fig. 1 ). Such a strip 12 of target radius may also be formed using heated discs, or the strip 12 could be rolled and then creep flattened on a mandrel. Whether the strip anode 12 is at a near flat configuration or prepared to a target radius, the strip anode 12 can be expected to be formed to a larger radius than the machined radius for the curvature of the surface 6 of the lead plate 5.
• a flexible strip anode 12 can be precurved in its width direction into a series of chords 31 such as by pressing the light gauge strip 12 in a press break. Adjacent chords 31 are separated on the upper surface of the strip 12 at break Iines 32. Each adjacent anode chord 31 , e.g., having a radius resulting from bending, meets at the undersurface of the strip anode 12 at undersurface nodes 33. At the center of the undersurface, the anode plate 12 has a boss 13 affixed thereto. The strip anode 12 has been formed to a larger radius than the radius for the curvature of the surface 6 of the lead plate 5 (Fig. 1 ). Details of a variation along the length of a narrow strip anode 12 is depicted in
• Fig. 3 showing the front face of a strip anode 12.
• this strip anode 12 of thin gauge sheet is a narrow anode, providing an elongated rectangular strip anode 12.
• the strip anode 12 on its undersurface, or obverse back face has a plurality of spaced-apart short studs 13 (Fig. 2) shown in Fig. 3 in phantom Iines.
• the studs 13, as shown in the figure, can be all aligned on the center-line of the strip anode 12.
• these studs 13 need not be aligned on the center-line of the strip anode 12.
• the generally elongated anode plate in its length dimension is segmented and the segments are separated by Iines of separation 14 that are biased, e.g., biased with respect to the direction of travel of a cathode drum (not shown).
• the strip anodes 12 are solid, i.e., non ⁇ perforate, and free from bias or other cutting.
• the light gauge strip anode 12 of at least substantially uniform thickness, is brought into contact with the machined surface face 6 of the lead plate 5.
• holes 15 are first drilled through the base plate 5.
• a long stud 16 which has been affixed, as by welding, to the back of the strip anode 12.
• the body of the stud 16 proceeds through a hole 15 in the plate 5 and the stud 16 can be connected to a current lead (not shown) such as at a threaded end 17 of the stud 16. Then as shown in Fig.
• the stud 16 has been pulled through the hole 15 whereby the light gauge strip anode 12 flexes into a matching radius with the machined surface face 6 (Fig. 1) of the base plate 5.
• This base plate 5 may also serve as a current distributor for the strip anode 12.
• other serviceable fastening means that are known to those skilled in the art and which advantageously are electrically conductive, e.g., countersunk bolts or tapped holes with threaded studs. These bolts may be secured within the plate 5 whereby the holes 15 would not need to penetrate completely through the plate 5.
• fastening means are secured to the back of the strip anode 12
• any suitable means for securing metal to metal which is advantageously a metallic means for enhanced electrical conductivity between the fastening means and the strip anode 12.
• metallic means such is preferably welding, e.g., friction welding, TIG welding, resistance welding, laser welding or capacity discharge welding.
• Any surface area of the fastening means at the back of the strip anode 12, and which may be just the threaded end 17 of the fastening means, may be treated such as for enhanced electrical connection.
• Coating, e.g., metal plating can be a serviceable treatment.
• the plating may include platinum plating, which could be used at a contact area such as the threaded end 17.
• a coating treatment may also include application of a friction control coating.
• the threaded end 17 can be treated with a coating such as a polytetrafluoroethylene-based coating.
• Fig. 6 there is shown a representative assembly 20 of an electrodeposition apparatus which has been assembled, e.g., refurbished, in accordance with the present invention.
• the assembly 20 has a concave lead support plate 5 which is supported by ribs 21.
• the ribs 21 of the assembly 20 can be supported on beams (not shown) when the electrodeposition apparatus is completely assembled.
• the support plate 5 supports a multitude of parallel, generally elongated and narrow strip anodes 12 positioned side-by-side across the width of the support plate 5. For this representative assembly 20, seventeen strip anodes 12 are utilized.
• the active front faces of the strip anodes 12 are exposed to view in Fig. 6. These strip anodes 12 are in side-by-side relationship with contiguous edges in touching engagement. These can be beveled edges.
• This multitude of strip anodes 12 forms an anode sheet having characteristics of the individual strip anodes 12, e.g., thin and resilient.
• the back faces (not shown) of the strip anodes 12 are in flexed engagement with the surface 6 (Fig. 4) of the support plate 5, e.g., as by means utilizing studs 16 through base plate holes 15 (Fig. 5).
• Each strip anode 12 can be expected to have at least substantially the same thickness, with the thickness being uniform for each strip 12.
• This electrode assembly 20 comprising the support plate 5 and strip anodes 12, together form a part of a vessel serving as an electrolyte chamber.
• a sealing member such as a gasket (not shown) to further preclude electrolyte from reaching the support plate 5.
• a sealing member may be of Gore-Tex (trademark) or EPDM (terpolymer elastomer made from ethylene-propylene diene monomer) or the like.
• Other useful sealing members may be metal coatings, e.g., a thermally spray applied valve metal coating such as of niobium or titanium, or their alloys and intermetallic mixtures, applied by plasma or flame spraying.
• the lead substrate plate 5 which may have served in the electrodeposition apparatus as the anode, can be machined down to a new radius. This new radius will provide a curved, freshly machined face 6 for supporting the solid and insoluble, light gauge flexible anode sheet of the multitude of strips 12.
• holes 15 can be drilled through the substrate plate 5.
• Anode strips 12 can have studs 16 secured as by friction welding to the back of the strip anodes 12. The studs 16 are pulled through the holes 15 of the substrate plate 5. The light gauge strip anodes 12 are then flexed in place over the lead substrate plate 5. Contiguous edges of adjacent strip anodes 12 may be beveled for a tight seal.
• the procedure of assembling the electrode assembly 20 can utilize the precurved strip anodes 12 as shown in Fig. 2A.
• the principal contact area between the strip anode 12 and the substrate plate 5 can be not only at the stud 13 but also at the undersurface nodes 33.
• These strip anodes 12 are "at least substantially curved,” as the term is used herein, and the curve is in the width dimension of the anode 12.
• the curve will generally conform to the curved upper surface 6 of the lead plate 5. It is advantageous that the curve of the strip anode 12 have a larger radius than the curve for the upper surface 6 of the lead plate 5.
• the undersurface nodes 33 come into firm engagement with the malleable lead support plate 5. This can provide advantageous current connection between the support plate 5 and the strip anode 12.
• the nodes could be coated, e.g., coated with a metal such as electroplated with platinum metal.
• the strip anode 12 will be flexed into place, with the series of chords 31 providing the curve of the strip anode 12.
• the lead substrate plate 5 may also be coated, such as with a metal coating, at least on the upper surface 6. This will typically be coating of the freshly machined surface 6 of the plate 5.
• the strip anodes 12 are thin, i.e., light gauge, and are rolled or otherwise formed elongated strips having sufficient flexibility so that they can be flexed a small amount using reasonable bolting force.
• the strips 12 should have sufficient thickness to carry current, such as from a current connection to the substrate lead plate 5 serving as a current distributor throughout the total broad obverse face of the whole sheet anode, and sufficient thickness so that the strips 12 are self-supporting and capable of retaining, in the absence of applied force, the shape imparted to them by rolling or other forming.
• the strip anodes 12 have a thickness of from about 1 to usually about 10 millimeters or more, e.g., up to about 20 millimeters.
• a thin, coated imperforate titanium strip 12 rolled, or otherwise formed, preferably has a thickness of about 5 to about 10 millimeters (mm).
• the strip anodes 12 are insoluble, i.e., not even somewhat or slightly soluble as may be the case for the lead plate 5.
• the strip anodes 12 are dimensionally stable electrodes.
• the dimensionally stable electrodes have a solid, i.e., non-perforate, metallic substrate.
• the substrate is capable of withstanding the corrosive action of the electrolyte in which the strip anodes 12 are immersed, i.e., they are resistant to corrosion from the environment of the strip anodes 12.
• Materials for the anode substrate, as well as for the studs 16, or other fastening means, e.g., countersunk bolts are valve metals such as titanium, tantalum, zirconium, niobium, and tungsten.
• a preferred valve metal is titanium.
• valve metals can become oxidized on their surfaces increasing the resistance of the valve metal to the passage of current, thereby passivating the anodes. Therefore, for the active front faces of the strip anodes 12, it is customary to apply electrically conductive electrocatalytic coatings to the anode substrate which then do not become passivated.
• the anode plates 12 are usually coated before they are installed on the substrate plate 5.
• active oxide coatings such as platinum group metal oxides, magnetite, ferrite, cobalt oxide spinel or mixed metal oxide coatings. Such coatings have typically been developed for use as anode coatings in the industrial electrochemical industry.
• the mixed metal oxide coatings can often include at least one oxide of a valve metal with an oxide of a platinum group metal including platinum, palladium, rhodium, iridium and ruthenium or mixtures of themselves and with other metals.
• Further coatings in addition to those enumerated above include manganese dioxide, lead dioxide, platinate coatings such as M x Pt 3 0 4 where M is an alkali metal and X is typically targeted at approximately 0.5, nickel-nickel oxide and nickel plus lanthanide oxides.
• the anode substrate for the dimensionally stable electrodes may also be a metal such as steel or copper which is explosively clad or plated with a valve metal, such as titanium clad steel, and then coated, e.g., with an electrocatalytic surface coating.

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• Chemical & Material Sciences (AREA)
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• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electrolytic Production Of Metals (AREA)
• Electroplating Methods And Accessories (AREA)
• Primary Cells (AREA)
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• 1995
  • 1995-11-08 TW TW084111836A patent/TW318320B/zh active
• 1996
  • 1996-06-06 US US08/653,119 patent/US5783058A/en not_active Expired - Fee Related
  • 1996-07-10 CA CA002229016A patent/CA2229016A1/en not_active Abandoned
  • 1996-07-10 JP JP9508423A patent/JPH11510218A/ja active Pending
  • 1996-07-10 WO PCT/US1996/011227 patent/WO1997006291A1/en active IP Right Grant
  • 1996-07-10 EP EP96924344A patent/EP0850327B1/en not_active Expired - Lifetime
  • 1996-07-10 AT AT96924344T patent/ATE187781T1/de active
  • 1996-07-10 DE DE69605677T patent/DE69605677T2/de not_active Expired - Fee Related
  • 1996-08-06 KR KR1019960032717A patent/KR970011025A/ko not_active Withdrawn

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