US3386895A - Method and apparatus for electroplating rollable objects - Google Patents

Method and apparatus for electroplating rollable objects Download PDF

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Publication number
US3386895A
US3386895A US414310A US41431064A US3386895A US 3386895 A US3386895 A US 3386895A US 414310 A US414310 A US 414310A US 41431064 A US41431064 A US 41431064A US 3386895 A US3386895 A US 3386895A
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United States
Prior art keywords
tank
plating
objects
magnetic field
magnetic
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US414310A
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English (en)
Inventor
Meredith A Hunter
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International Business Machines Corp
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International Business Machines Corp
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Filing date
Publication date
Priority to GB1051702D priority Critical patent/GB1051702A/en
Application filed by International Business Machines Corp filed Critical International Business Machines Corp
Priority to US414310A priority patent/US3386895A/en
Priority to NL6514442A priority patent/NL6514442A/xx
Priority to FR38555A priority patent/FR1453761A/fr
Priority to DE19651496845 priority patent/DE1496845A1/de
Priority to CH1619565A priority patent/CH428370A/de
Priority to ES0320015A priority patent/ES320015A1/es
Priority to BE672945D priority patent/BE672945A/xx
Priority to ES0320101A priority patent/ES320101A1/es
Application granted granted Critical
Publication of US3386895A publication Critical patent/US3386895A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • 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
    • C25D17/02—Tanks; Installations therefor
    • 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
    • C25D17/16—Apparatus for electrolytic coating of small objects in bulk
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/007—Electroplating using magnetic fields, e.g. magnets

Definitions

  • FIG. 1 METHOD AND APPARATUS FOR ELECTROPLATING ROLLABLE OBJECTS June 4, 1968 Filed Nov. 27, 1964 FIG. 1
  • Rollable objects are electroplated in an apparatus comprising a non-magnetic electrically conductive tank acting as cathode and including an anode for passing a plating current from the anode to the cathode and having means fixedly surrounding the tank for inducing a high speed rotating magnetic field through the tank.
  • the magnetic field causes rolla'ble objects within the tank to move around the walls of the tank and thereby become plated.
  • the magnetic field means comprise a plural phase, plural oil electrical circuit.
  • This invention relates to an apparatus and process to position objects for efiicient plating or coating from a bath under the influence of electric current.
  • the invention is directly concerned with coating of the electroplating type, the means provided have to do with positioning and are not related directly to the chemical aspects of the coating process.
  • Electroplating of parts as performed in the prior art is often both excessive in cost and far less than ideal in result.
  • To plate an object with an electric current the object must be made an electrode in an electrolyte containing circuit carrying electric current.
  • the electric circuit includes the object, a plating bath, and a second electrode.
  • electric current passing between the electrodes separates elements from the plating bath.
  • metal ions are attracted from the plating bath to the object where they are neutralized to form a thin coating of the metal on the object.
  • An inherent problem in this plating is in connecting the object as an electrode. Permanent structures are easily provided to contain the plating bath, to position one electrode in the bath, and to present an energized electrical circuit to the system. A plurality of objects to be plated, however, each must be brought to the system, connected as the second electrode, and then removed after being plated.
  • the objects can simply be vigorously agitated and mixed while they are in the plating bath.
  • the tank for the bath then often takes the form of a horizontally disposed barrel, the inside of which is conductive and in the energized electrical circuit.
  • a large number of objects to be plated are deposited in the barrel, and the barrel is rotated.
  • the objects are carried up the side of the barrel until they fall back under the influence of gravity.
  • Each object is masked by other objects and the sides of the barrel during part of the time.
  • the mixing action of the moving barrel results, however, in many different positions being assumed and all of each object ultimately being exposed and plated.
  • a vigorously agitated system inherently includes discontinuities in the plating process. As objects fall or are moved away from the sides of the tank, they are no longer electrodes in the electroplating system, although they become electrodes once more when they again come in direct electrical contact with the sides of the tank. Some materials plate satisfactorily in a barrel system regardless of the discontinuities of current flow in the plating process. Other materials, an example of which is nickel, undergo an undesirable chemical change during the time that plating is discontinued. When nickel is plated, a nickel oxide film tends to form during discontinuities in plating. Further plating is on the external surface of an oxide film, and the resulting product is a laminated coating with poor adhesion between the layers of nickel.
  • Chromium can be plated in a barrel system without the resulting product being laminated. Barrel plating of chromium is not commercially practical, however, because of considerations having to do with the electrical system. Chromium ions in a plating bath are often in a hexavalent state of ionization. This requires that six electrons must be supplied by the electrical circuit to deposit a single chromium atom. Considering valence alone a ratio can be computed of atoms plated to current supplied for plating. For chromium this ratio attributable to valence is one-third of that for most other metals because most other metals are bivalent. A second factor drastically reduces the efficiency of chromium plating.
  • cathode current efficiency is a measure of the amount of useful plating current as compared to current consumed in liberating by-products such as hydrogen gas. Cathode current efficiency is often only 17% for chromium plating as compared to -100% for the plating of many other types of metal deposits.
  • This invention dispenses with the clip and furthermore eliminates any need to manually attach each object to the clip or to any other point.
  • This invention uses magnetic force to position objects properly as electrodes, and this invention is believed to be completely novel in its use of magnetism.
  • a magnetic field which passes through a tank holding an electrical plating bath.
  • One electrode may be permanently fixed within the bath.
  • At least portions of the walls of the tank are suitably conductive to provide a contact such that a conductive object resting against the side of the tank will act as an electrode in an electrical plating system.
  • the magnetic forces draw objects to be plated to the side of the tank.
  • An electrical voltage between the one electrode and the conductive tank walls passes through the objects and results in plating of the known type from a plating bath within the tank.
  • the magnetic field provided moves at least intermittently.
  • a field rotating past the vertical walls of the tank is provided by a three phase, three coil alternating current system similar to that found in many electrical motors.
  • the moving field positions the objects and also tends to carry the objects in the tank with it somewhat.
  • the objects are positioned side by side. A torque is induced upon the objects and they therefore tend to roll along the side of the tank. As the objects roll, different contact points are continuously made so that prior contact points are then exposed and will be plated.
  • FIG. 1 is a plain view of the invention showing washers positioned by the magnetic force and being rolled along the tank.
  • FIG. 2 is a cross-sectional elevation view showing the system of the invention.
  • Plating solutions are generally ionic and always conductive of electrical current.
  • a heavy direct electrical current normally flows between the object being plated to the other electrode through the plating solution. Neither of these characteristics, however, substantially impairs the action of magnetic flux directed through the tank and plating bath. This is true because an ionic solution, a1- though electrically conductive, presents neither a shunt nor a substantial bar to magnetic fiux.
  • the heavy direct current used has no unusual characteristics which would cause an interaction with a magnetic flux passing through it.
  • the system of the invention therefore consists of a tank 1 holding an electroplating bath 3.
  • An electrode 5 extends vertically into the electroplating bath 3 at the center of the tank 1.
  • the inner Wall 7 of the tank 1 is made of an electrically conductive, substantially non-ferromagnetic material such as stainless steel of a substantially non-ferromagnetic type.
  • the inner wall 7 and the electrode 5 are connected through a switch 9 to a source of direct current electrical potential V.
  • the inner wall 7 is made of stainless steel because that material is relatively unreceptive to being plated upon. Plating of conductive portions of the tank, such as the inner wall 7, is a known disadvantage in this art. The plating can be removed at intervals with a strong acid or similar techniques.
  • the bottom of the tank 1 may be perforated (FIG. 2).
  • a pipe 11 is situated over and near the center of tank 1.
  • Pump 13 connects pipe 11 to the contents of a larger tub 15, which can be called the circulating tub 15.
  • Circulating tub 15 holds relatively large quantities of plating bath solution 3.
  • the preferred embodiment includes a moving magnetic field which can induce current in the objects being plated and in other conductive portions of the system. High direct currents are also used during the plating step.
  • Circulation of plating solution 3 by pump 13 through pipe 11 and perforations in the tank 1 cools the electroplating system to prevent overheating. Circulation also refreshes the plating bath 3 with plating material at those points near the objects being plated which have been coated by the nearby portions of the bath 3.
  • the magnetic system can be the three coil, three phase system found in three phase synchronous and induction motors.
  • the stator system from a three phase induction motor has been used in a test model of the invention.
  • the flux induced was entirely satisfactory, but the heat produced was a problem.
  • the magnetic system consists of one set of coils 17' and 17", oppositely faced and wound in the same direction.
  • Coils 17 and 17" are in circuit with a source of alternating voltage 19, having a relative phase of 0.
  • Coils 17' and 17" are connected by a conductor 21 (shown in dotted outline because it is hidden by tank 1).
  • the fiux created by coils 17 and 17" is directed across a diameter of tank 1 and the flux of the two coils 17' and 17" is additive.
  • Coils 23 and 23" are in a circuit similar in every respect to the circuit of coils 17' and 17".
  • the coils 23 and 23" are displaced angularly 120.
  • Their potential source 25 leads in phase by a relative 120.
  • Conductor 27 connects the pole faces.
  • coils 29' and 29" are displaced a further 120 angular degrees and are powered by voltage source 31 which leads in phase a further 120 degrees.
  • Conductor 33 connects the two pole faces.
  • the coils 17, 17", 23', 23 and 29, 29" are preferably slightly larger than the vertical dimension of the tank 1. This is to assure that all objects in the tank are operated upon by magnetic flux.
  • a switch 34 is provided for control of the magnetic system. The switch controls all of the electrical circuits to the coils simultaneously. If the tank 1 is made of thick metal, it should be laminated to reduce eddy currents. The outside of tank 1 need not be conductive. Therefore, it is desirable to protect this side from the plating bath with an inert, plastic layer.
  • washers 40 or similar objects are simply dumped into the tank 1. There is no need to handle each washer separately. They may be piled randomly on the bottom of the tank 1. Switch 34 may be open at this time so that no magnetic elfects are present.
  • Switch 34 is then closed.
  • the magnetic field operates on each washer 40.
  • the washers are pulled to the side of the tank 1 as shown in FIG. 1 and FIG. 2.
  • Magnetism is induced into each washer.
  • the poles of magnetism induced in each washer apparently attract opposite poles in' the other washers.
  • the washers tend to line up side by side as shown in FIG. 1.
  • the major magnetic force is from the magnetic system and the washers therefore are pulled and held to the side of tank 1.
  • Electroplating is conducted while the washers 40 are magnetically positioned. Closing of switch 9 is all that is required to cause plating, since the proper circuit through the plating bath 3 is inherent in the structures.
  • Pump 13 circulates bath 3 for cooling purposes in the manner previously discussed.
  • a single batch of washers is plated with chromium sufiicient'for commercial utilization in a time period on the order of magnitude of 1 minute to 45 seconds as compared to minutes to 30 minutes to perform the same plating in a barrel system. The exact time varies, of course, with the exact conditions and components of the system.
  • the rolling or rocking of the washers can be explained by at least two, complementary theories. It will be recalled that the magnetic system effectively induces a single magnetic field rotating at high speed around the tank. The velocity of this field is proportional to the radial distance from the center of rotation. It will be clear that the washer will'act as rotors in a small induction motor because the outer side of the washer is intersected by flux moving at greater speed than the same flux as it intersects the inner side of the washer. As in any motor, a torque will be induced tending to cause the rotor to follow the moving flux.
  • a second factor would be the residual magnetism which tends to stay with the objects after the magnetic field which induced the magnetism has moved.
  • the flux from the magnetic system induces magnetism directly across the washer.
  • the flux then moves, leaving the magnetism previously induced in the washer somewhat as it was.
  • a torque will be created by the new relative positions, with the flux pulling the original outside portion of the washer (the portion in contact with tank 1) toward it, and pushing the inside portion of the washer away.
  • the washers do not move quickly. Instead they roll gently, even stopping at times. The washers might be expected to fall during those periods when the rotating magnetic field has moved from them.
  • a 60 cycle alternating current is used in the invention, however, to produce a magnetic field making 60 complete revolutions each second. Inertia in the system apparently prevents the washers from falling away during the short time which they theoretically could. Instead they extend continuallyy from the side of the tank while rolling gently.
  • An electrical plating apparatus comprising:
  • a tank for containing an electrical plating bath said tank having continuous side walls, the inside of said side walls being composed of conductive substantially non-ferromagnetic material,
  • an electrode situated within said tank for electrical plating between said electrode and objects in contact with said side walls.
  • a process of electrical plating comprising the steps of:

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electroplating Methods And Accessories (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
US414310A 1964-11-27 1964-11-27 Method and apparatus for electroplating rollable objects Expired - Lifetime US3386895A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
GB1051702D GB1051702A (enrdf_load_stackoverflow) 1964-11-27
US414310A US3386895A (en) 1964-11-27 1964-11-27 Method and apparatus for electroplating rollable objects
NL6514442A NL6514442A (enrdf_load_stackoverflow) 1964-11-27 1965-11-08
FR38555A FR1453761A (fr) 1964-11-27 1965-11-16 Procédés de galvanoplastie
DE19651496845 DE1496845A1 (de) 1964-11-27 1965-11-17 Elektroplattierungsapparat
CH1619565A CH428370A (de) 1964-11-27 1965-11-24 Elektroplattierungsapparat
ES0320015A ES320015A1 (es) 1964-11-27 1965-11-26 Un procedimiento de dar recubrimientos galvanicos.
BE672945D BE672945A (enrdf_load_stackoverflow) 1964-11-27 1965-11-26
ES0320101A ES320101A1 (es) 1964-11-27 1965-11-27 Un aparato para efectuar recubrimientos galvanicos

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US414310A US3386895A (en) 1964-11-27 1964-11-27 Method and apparatus for electroplating rollable objects

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US3386895A true US3386895A (en) 1968-06-04

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US414310A Expired - Lifetime US3386895A (en) 1964-11-27 1964-11-27 Method and apparatus for electroplating rollable objects

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US (1) US3386895A (enrdf_load_stackoverflow)
BE (1) BE672945A (enrdf_load_stackoverflow)
CH (1) CH428370A (enrdf_load_stackoverflow)
DE (1) DE1496845A1 (enrdf_load_stackoverflow)
ES (2) ES320015A1 (enrdf_load_stackoverflow)
FR (1) FR1453761A (enrdf_load_stackoverflow)
GB (1) GB1051702A (enrdf_load_stackoverflow)
NL (1) NL6514442A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050258044A1 (en) * 2004-05-21 2005-11-24 Berman Michael J Magnetic focus rings for improved copper plating
US20090050486A1 (en) * 2007-08-24 2009-02-26 International Business Machines Corporation Enhanced Magnetic Plating Method and Apparatus
US20100006444A1 (en) * 2008-07-10 2010-01-14 Ebara Corporation Plating apparatus and plating method for forming magnetic film

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1420127A (en) * 1919-01-08 1922-06-20 Arthur J Moxham Process of treating ore to produce pure iron
US1658872A (en) * 1925-01-16 1928-02-14 Henry J Yeager Electrolytic apparatus
US2397177A (en) * 1940-08-01 1946-03-26 Richard M Wick Apparatus for electroplating ball bearings
US2485628A (en) * 1947-08-09 1949-10-25 Wayne J Morrill Induction motor primary construction

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1420127A (en) * 1919-01-08 1922-06-20 Arthur J Moxham Process of treating ore to produce pure iron
US1658872A (en) * 1925-01-16 1928-02-14 Henry J Yeager Electrolytic apparatus
US2397177A (en) * 1940-08-01 1946-03-26 Richard M Wick Apparatus for electroplating ball bearings
US2485628A (en) * 1947-08-09 1949-10-25 Wayne J Morrill Induction motor primary construction

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050258044A1 (en) * 2004-05-21 2005-11-24 Berman Michael J Magnetic focus rings for improved copper plating
US20090050486A1 (en) * 2007-08-24 2009-02-26 International Business Machines Corporation Enhanced Magnetic Plating Method and Apparatus
US7964081B2 (en) * 2007-08-24 2011-06-21 International Business Machines Corporation Enhanced magnetic plating method
US20110220020A1 (en) * 2007-08-24 2011-09-15 International Business Machines Corporation Enhanced magnetic plating method
US8168045B2 (en) * 2007-08-24 2012-05-01 International Business Corporation Apparatus for an enhanced magnetic plating method
US20100006444A1 (en) * 2008-07-10 2010-01-14 Ebara Corporation Plating apparatus and plating method for forming magnetic film
US8877030B2 (en) * 2008-07-10 2014-11-04 Ebara Corporation Plating apparatus and plating method for forming magnetic film

Also Published As

Publication number Publication date
FR1453761A (fr) 1966-06-03
CH428370A (de) 1967-01-15
DE1496845A1 (de) 1969-08-14
BE672945A (enrdf_load_stackoverflow) 1966-03-16
ES320101A1 (es) 1966-05-16
GB1051702A (enrdf_load_stackoverflow)
ES320015A1 (es) 1966-05-01
NL6514442A (enrdf_load_stackoverflow) 1966-05-31

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