US3809641A - Electroplating apparatus with plating vessel having protrusions and recesses - Google Patents

Electroplating apparatus with plating vessel having protrusions and recesses Download PDF

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Publication number
US3809641A
US3809641A US00287271A US28727172A US3809641A US 3809641 A US3809641 A US 3809641A US 00287271 A US00287271 A US 00287271A US 28727172 A US28727172 A US 28727172A US 3809641 A US3809641 A US 3809641A
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United States
Prior art keywords
vessel
articles
plating
plated
fused salt
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Expired - Lifetime
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US00287271A
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English (en)
Inventor
A Miyata
H Okubo
C Tomita
A Suzuki
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JFE Engineering Corp
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Nippon Kokan Ltd
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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
    • C25D17/16—Apparatus for electrolytic coating of small objects in bulk
    • C25D17/22—Apparatus for electrolytic coating of small objects in bulk having open containers
    • C25D17/26—Oscillating baskets

Definitions

  • This invention relates to a plating apparatus, and more particularly to an apparatus for plating metals on a plurality of small articles simultaneously and uniformly in a fused salt plating bath.
  • a prior method comprises placing a large quantity of articles to be plated in a hexagonal or octagonal boxshaped cage and electroplating these articles with a water solution while rotating this cage.
  • barrel plating comprises placing a large quantity of articles to be plated in a hexagonal or octagonal boxshaped cage and electroplating these articles with a water solution while rotating this cage.
  • a large quantity of articles confusingly placed in a cage-shaped barrel are being electroplated while said barrel is being rotated, such prior art apparatus does not permit satisfactory plating of articles in the middle of the stack of articles.
  • the articles plated are thus limited to these in the vicinity of the outside of the stack of articles.
  • Articles in the middle or bottom portion of the stack are not properly plated, because they are apt to become an anode relative to those at the outside.
  • Articles can be properly plated only when they are exposed alternately to the surface of the stack by being turned over. This hampers obtaining uniform plating.
  • prior art apparatus is limited to water solution electroplating. If such prior art barrel plating is applied to fused salt electroplating, the strong corrosive action of the fused salt will dissolve ground metal. Articles, for example, in the middle or bottom portion of the stack are put in the anodic state by the plating current, or previously plated metal. These phenomena degrade the quality of plating or make articles incapable of being plated.
  • the present invention is intended to improve the above prior art of electroplating, and the primary object of the present invention is to provide apparatus having a simple structure wherein a uniform distribution of cathodic current is applied to all the articles to be plated, when electroplating a considerable number of small articles, so as to make electroplating effective at all times.
  • a further object is to provide a plating apparatus particularly suitable for use in a fused salt plating bath, and wherein part of the electrolyte in the vicinity of the articles is periodically moved.
  • the present invention adopts a special pan-shaped cathodic vessel in which a predetermined quantity of small articles are accommodated.
  • the vessel is adapted to be intermittently rotated at a circumferential speed which is suflicient to move the articles outwardly by centrifugal force.
  • the articles are spread toward the circumferential edge of the vessel.
  • the articles then roll down toward the middle portion of vessel, to form a thin layer, preferably only one layer, of articles to be plated.
  • a constantly uniform current distribution is obtained for all small articles in the vessel, and the tendency that some portion will receive an insufficient flow of plating current because of stacks of articles, as occurs in the prior art, is substantially prevented.
  • the present invention provides improved panshaped vessel structures which enable better contact between the vessel and the articles to be plated.
  • the vessel has an irregular surface configuration, with protrusions, recesses, or the like, which provide improved contact and lower plating resistances.
  • aluminum electroplating can be advantageously applied to small articles, thereby providing products having outstanding chemical and heat resistance.
  • the prior art aluminum electroplating cannot be done effectively to small articles so that almost all aluminum plated products have not been commercialized.
  • the present invention can apply fused salt electroplating effectively in the above stated way without dissolution of ground metal and plated metal.
  • FIG. 1 is a sectional view of a plating apparatus of the present invention
  • FIGS. 2 and 3 partially show the states of arrangement of small articles in a vessel, FIG. 2 showing the state when the vessel is standing still and FIG. 3 showing the state when the vessel is rotating;
  • FIGS. 4A and 4B illustrate vessel configurations in accordance with the present invention
  • FIGS. 5, 6A, 6B and 6C illustrate other vessel configurations in accordance with the present invention.
  • FIGS. 7 and 8 illustrate the contact of a bolt to be plated with a prior art vessel and with a vessel of the present invention which is illustrated in FIG. 8, respectively.
  • FIG. 1 generally shows an apparatus according to the present invention.
  • a generally pan-shaped vessel 2 with a relatively shallow and gently arcuately concave bottom and open in the upper portion is mounted in a tank 1 containing plating bath 4.
  • Vessel 2 is only generally shown in FIG. 1.
  • Detailed illustrations of improved vessels 2 in accordance with the present invention are shown, for example, in FIGS. 4-6.
  • rotary shaft 3 Connected to the center portion of vessel 2 is rotary shaft 3 which is secured to vessel 2 by a nut 32 and the flange seat 31 provided on the rotary shaft 3. Cathodic current is supplied via shaft 3.
  • Panshaped vessel 2 is curved such that articles 25 contained in the interior of the vessel gather automatically at the center portion under the action of gravity and moreover are rolled or slid by centrifugal force toward circumferential edge of vessel 2 when vessel 2 is rotated at a given speed.
  • an annular cover 22 On the opening edge 23 of vessel 2 is an annular cover 22 for checking the articles from spilling over the outer edge of vessel 2 when the vessel is rotated.
  • Vessel 2 is made of aluminum and is provided with perforations 21 over the surface thereof for in-flow and outflow of a fused salt bath therethrough. Vessel 2 is coated on the backside with chemical and heat resistant synthetic resins such as polytetrafluoroethylene.
  • the cover 22 is also formed of polytetrafluoroethylene or other material.
  • An annular aluminum anode 10 is concentrically mounted about the rotary shaft 3 over the vessel opening 24. The anode 10 is supported in place by support member 11 and supplied with anodic current.
  • Tank 1 is provided at least on its inside surface with an anticorrosive layer such as a glass lining and on the top with a first cover 12 made of phenol-formaldehyde resin or polytetrafluoroethylene.
  • a cylinder 6 made of polytetrafluoroethylene or other anticorrosive material, having an inner diameter somewhat larger than the outer diameter of pan-shaped vessel 2 is suspended in the fused salt bath 4.
  • the portion of cylinder 6 which is immersed in the fused salt bath is provided with perforations 17 for passing said bath therethrough.
  • the top opening portion of cylinder 6 is provided with a second lid 7 also made of phenolformaldehyde resin or polytetrafluoroethylene. Through opening 7' provided centrally in lid 7 are inserted the aforementioned rotary Shaft .3 and pp member as illustrated in FIG. 1.
  • the second lid 7 On one side of the second lid 7 is provided another opening 8 for inserting articles which are to be plated.
  • a gas flow curtain by jetting an inactive gas so as to stop air from intruding into the fused salt bath.
  • annular floating piece 14 made of glass or other anticorrosive material which is floated on fused salt bath 4 in cylinder 6 and prevents evaporation of bath.
  • Further evaporation preventive material 13 such as silicagel is also floated on the surface of bath 4 between cylinder 6 and tank 1 so as to cover the surface of the electroplating bath.
  • heaters 5 At the bottom portion of tank 1 and also in other sections are arranged heaters 5 so as to keep the temperature of the bath as predetermined in the interior of tank.
  • Rotary shaft 3 is designed to be given a predetermined rotary movement by a rotary mechanism such as a motor 35 shown generally in FIG. 1.
  • Inactive gas inlets 15 and 16 are provided respectively on lids 12 and 7.
  • a feeder collar or ring 26 is provided for furnishing electric current to rotary shaft 3.
  • FIGS. 4-6 illustrate a number of pan-shaped electroplating vessels according to this invention which provide improved contact with the articles to be plated, thereby resulting in improved plating uniformity.
  • FIG. 4A is a vertical sectional view of a vessel 56 according to this invention and FIG. 4B is a top plan of the same vessel.
  • the vessel 56 has perforations 52 therethrough.
  • Aluminum bars 51 arranged in a spiral-type configuration are fixed on the surface of vessel 56 by means of fixing members 53.
  • the aluminum bars 51 constitute protruding portions of the vessel structure and the spaces therebetween constitute receding portions of the vessel structure.
  • Perforations 52 provide paths for the fused salt to pass through during operation.
  • the bars 51 are shown in crosssection only by way of example, it being understood that they may take any other convenient shape.
  • the vessel may have a diameter of 365 mm. and the round aluminum bars may have a diameter of 3 mm. Articles are plated more uniformly using the vessel of FIGS. 4A and 4B, as will become more apparent from the discussions hereinbelow with reference to FIGS. 8A and 8B.
  • FIG. 5 shows a modification of FIGS. 4A and 4B wherein square aluminum bars 54 are used.
  • the square bars may be of a size of 2 In. x 5 mm., for example.
  • FIGS. 6A and 6B show sectional and top views, respectively, of a vessel 58 provided with a plurality of generally hemispherical cavities 55 having small perforations 52 over the surface thereof.
  • the perforations 52 are in the depressions or cavities 55, but may be otherwise located.
  • One typical example of the size of the cavity is 10 mm. in diameter and 5 mm. in depth, and that of the perforation is 3 mm. in diameter.
  • reference numeral 59 denotes the protruding portions of the vessel and numeral 55 (cavity) denotes the receding portions of the vessel.
  • FIGS. 4-6 are mere examples. They may vary depending on the types of articles to be plated and the conditions of treatment, as should now be apparent.
  • a shallow, gently curved panshaped vessel having protrusions and recesses is used so that a wide contact area is provided between the vessel and articles to be plated, such as bolts, thereby permitting electric current to pass more evenly between the vessel and the articles.
  • a panshaped vessel 2' having a smooth surface is used for electroplating bolts 40 and the like, the vessel 2 and the bolt 40 contact each other at substantially only two points.
  • the contacting points are few in number and narrow in area. Therefore, application of an electric current causes high contact resistance between the vessel 2' and the article 40.
  • insuflicient plating current flows from the vessel 2 to the bolt 40;
  • the bolt 40 has an electrical potential nearer to that of the anode than the vessel 2 and the aluminum film earlier deposited on the surface of the bolt 40 tends to become dissolved in the fused salt again; and
  • excessively thick aluminum films tend to be deposited at contacting points between the vessel 2' and the bolt 40.
  • FIGS. 8A and 8B illustrate the contact of a bolt 40 with vessels 57 and 58 of FIGS. 5 and 6, respectively.
  • the contact area of the bolt 40 with the vessel surface is large, thereby permitting electrical energy to flow more uniformly between the vessel and the bolt 40.
  • the articles to be placed have the portions thereof to be plated periodically changed, with the result that uniform plating all over the article is effected during the whole plating time.
  • the panshaped vessel is rotated via the rotary shaft 3 after turning off the current in the course of electrolytic operation, the articles to be plated move toward the peripheral portions of the vessel under the influence of centrifugal force.
  • the rotation of the rotary shaft 3 is stopped.
  • the articles then roll down toward the center of the vessel and rest on the bottom with the projecting portions of the articles located in the receding portions of the vessel surface, and the receding portions of the articles lying on the projecting portions of the vessel (see FIG.
  • FIG. 2 shows the arrangement of articles to be plated when the vessel stands still during plating.
  • FIG. 3 shows their state when they are spread by centrifugal force caused by the rotation of the vessel.
  • the small articles 25 are shown in a collective state, but in a thin or single layer, in FIG. 2, and in a developed state in FIG. 3 just after rotation of the rotary shaft 3.
  • an area S or S quite free of articles is developed at outer peripheral portion or the middle portion of vessel 2.
  • the repetition of these states not only rotates small articles 25 in groups but also changes their positions. While small articles such as screws or nuts transfer from the state of FIG. 2 to a developed state of FIG. 3, they roll in the vessel and are dispersed toward the periphery so as to be separated by a wider distance from each other. It is evident that the articles 25 are changed in position and coordination in the developing and gathering process, and consequently, uniform plating is obtained.
  • a feature of the present invention is that the panshaped vessels are provided with small perforations all over the surface thereof so as to shake otf the fused salt in the vicinity of the articles (21 in FIG. 1; 52 in FIGS. 4 and 5; and 52 in FIG. 6).
  • molecular aluminum salt AlCl in the bath is reduced on the surface of the article and is deposited in the form of aluminum (Al+++Al). Therefore, there must exist in the vicinity of the article sufficient aluminum salt for aluminum depositing.
  • aluminum salt is newly supplied into the vessel through said perforation as the aluminum salt loses aluminum and is pushed toward the peripheral portions of the vessel by centrifugal force caued by the rotation of the vessel.
  • the present apparatus is also provided with a cylinder 6 in FIG. 1 having perforations 17. This further facilitates circulation of the fused salt and also prevents the agitation action of the fused salt from reaching the surface of the bath where it touches the air. As described above, the fused salt where it is contacted with the article is moved by agitation but this movement does not reach the surface of the bath where it touches the air.
  • Still another feature of this invention is "that the ap paratus involved is of a simple structure. Since a fused salt (a mixture of A1Cl NaCl, and KCl) has strong corrosiveness against the apparatus, the plating apparatus mus-t be of as simple construction as possible, so as to enable economical replacement of corroded parts thereof.
  • the apparatus of the present invention clearly fulfills this object by utilizing a pan-shaped vessel which is inexpensive to fabricate and which is easily replaced.
  • the pan-shaped vessels 2, 56, 57, 58 serve as the container of articles 25 to be plated and at the same time as the cathode electrode.
  • the vessels 2, 56, 57, 58 can be made of any metal of high electric conductivity.
  • a vessel made of aluminum as ground material can be used, but also one made of a non-metal such as porcelain, glass lined with a copper net as a cathodic plate, or others can be used.
  • a non-metal such as porcelain, glass lined with a copper net as a cathodic plate, or others can be used.
  • the fact that the back side of such a vessel forms an insulating surface prevents useless flow of current from the bottom.
  • Rotary shaft 3 and support member 11 can be made of glass or porcelain hollow material, the interior of which can be used as a passage of cathodic current.
  • the annular anode is kept almost an equal distance from the surface of all articles to be plated and may be designed to stand still above the vessel.
  • the fused salt contained 60 mol percent of AlCl 25 mol percent of NaCl, and 15 mol percent of KCl.
  • the temperature applied was 160 C.
  • Electroplating was conducted by applying direct current between aluminum and the vessel, the aluminum former acting as the anode and the vessel acting as the cathode. Current was turned on to begin plating.
  • FIGS. 2 and 3 show the general position of the articles before and just after rotating the vessel, respectively.
  • a movement cycle comprising a rest of 6.5 seconds and rotation of 0.5 second was used.
  • Current for plating was 6.5 v., a.
  • Plating time was 40 minutes. The entire lot of finished products proved to be satisfactorily aluminum plated with a thickness of 15 microns.
  • Rotation of the rotary shaft 3 is conducted, for example, by continuously exciting the magnetic field of the DC shunt motor 35 and sending current intermittently to the armature circuit of the motor by a motor timer.
  • Apparatus for electroplating articles comprising:
  • a pan-shaped vessel having an upwardly curved, substantially horizontally extending, bottom and a wide upper opening and adapted to be immersed in said plating bath, the upward curvature of said vessel being upward from the center thereof toward the periphery thereof, the upwardly curved bottom of said vessel being adapted to retain articles to be plated thereon in a layer during the plating operation of said electroplating apparatus, and said vessel constituting the cathode of the electroplating apparatus, said curved bottom of said vessel being perforated and having an irregular surface configuration to provide more than point contact between the vessel and the articles to be plated;
  • a cover portion provided at the periphery of said vessel and eXtending inwardly and upwardly of said vessel at an acute angle with the horizontal for preventing said articles which are being plated from falling out of said vessel during operation of said electroplating apparatus;
  • a substantially cylindrical member surrounding at least a portion of said pan-haped vessel in said bath, said cylindrical member having a plurality of perforations therethrough for inflow and outflow of said plating bath;
  • means including a member extending substantially vertically into said tank and connected to said panshaped vessel for supporting said pan-shaped vessel completely immersed at a predetermined depth in said tank, and for imparting intermittent rotation to said pan-shaped vessel, said rotation time being short relative to the time said vessel is stationary, so as to move and spread out said articles toward the peripheral portions of said vessel to form said layer of articles;
  • Apparatus according to claim 1 further comprising a heating means at the bottom of said tank.
  • Apparatus according to claim 1 comprising a plurality of perforations all over the surface of said pan-shaped vessel.
  • Apparatus according to claim 1 including a plurality of protrusions on the upper surface of the bottom of said pan-shaped vessel.
  • Apparatus according to claim 1 comprising a floating member adapted to float on the surface of the bath contained in said tank and within the confines of the walls of said cylindrical member.
  • Apparatus according to claim 1 comprising a material adapted to float on the surface of the bath contained in said tank outside the confines of said cylindrical member.
  • Apparatus according to claim 3 wherein said anode member is an aluminum anode member.
  • Apparatus according to claim 1 wherein the curved bottom of said pan-shaped vessel has a plurality of spaced downwardly extending recesses formed therein.
  • Apparatus according to claim 12 wherein a hole is formed in the recessed portions of the bottom of said pan-shaped vessel.
  • Apparatus according to claim 1 including at least one member forming protrusions on the upper surface of the bottom of said pan-shaped vessel.
  • Apparatus according to claim 14 wherein said at least one member has a substantially circular crosssection.
  • Apparatus according to claim 14 wherein said at least one member has a substantially rectangular crosssection.
  • Apparatus according to claim 14 including a spirally formed member on the upper surface of the bottom of said pan-shaped vessel forming protrusions on said vessel.
  • Apparatus according to claim 17 comprising a plurality of perforations formed all over the surface of said pan-shaped vessel between protrusions.

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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)
  • Coating With Molten Metal (AREA)
US00287271A 1968-05-11 1972-09-08 Electroplating apparatus with plating vessel having protrusions and recesses Expired - Lifetime US3809641A (en)

Applications Claiming Priority (1)

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JP43031518A JPS4820970B1 (enrdf_load_stackoverflow) 1968-05-11 1968-05-11

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US3809641A true US3809641A (en) 1974-05-07

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US00287271A Expired - Lifetime US3809641A (en) 1968-05-11 1972-09-08 Electroplating apparatus with plating vessel having protrusions and recesses

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US (1) US3809641A (enrdf_load_stackoverflow)
JP (1) JPS4820970B1 (enrdf_load_stackoverflow)
CH (1) CH487256A (enrdf_load_stackoverflow)
DE (1) DE1804454C3 (enrdf_load_stackoverflow)
FR (1) FR1596970A (enrdf_load_stackoverflow)
GB (1) GB1223197A (enrdf_load_stackoverflow)
SE (1) SE354490B (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4182669A (en) * 1977-11-28 1980-01-08 Tetsuya Hojyo Automatic electroplating apparatus
US20090194422A1 (en) * 2008-01-31 2009-08-06 George Koltse Method and apparatus for plating metal parts
CN1576400B (zh) * 2003-07-18 2011-09-07 釜屋电机株式会社 电子部件的电镀装置和电镀方法、以及该电子部件
US20200173052A1 (en) * 2018-11-30 2020-06-04 Lam Research Corporation One-piece anode for tuning electroplating at an edge of a substrate
BE1029998B1 (nl) * 2021-12-08 2023-07-03 Duroc Nv Werkwijze en inrichting voor het verzinken van draadstangen met open trommel

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5698081A (en) * 1995-12-07 1997-12-16 Materials Innovation, Inc. Coating particles in a centrifugal bed

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4182669A (en) * 1977-11-28 1980-01-08 Tetsuya Hojyo Automatic electroplating apparatus
CN1576400B (zh) * 2003-07-18 2011-09-07 釜屋电机株式会社 电子部件的电镀装置和电镀方法、以及该电子部件
US20090194422A1 (en) * 2008-01-31 2009-08-06 George Koltse Method and apparatus for plating metal parts
US8298384B2 (en) 2008-01-31 2012-10-30 Century Plating Co. Method and apparatus for plating metal parts
US9758898B2 (en) 2008-01-31 2017-09-12 Century Plating Company Method and apparatus for plating metal parts
US20200173052A1 (en) * 2018-11-30 2020-06-04 Lam Research Corporation One-piece anode for tuning electroplating at an edge of a substrate
US10975489B2 (en) * 2018-11-30 2021-04-13 Lam Research Corporation One-piece anode for tuning electroplating at an edge of a substrate
BE1029998B1 (nl) * 2021-12-08 2023-07-03 Duroc Nv Werkwijze en inrichting voor het verzinken van draadstangen met open trommel

Also Published As

Publication number Publication date
SE354490B (enrdf_load_stackoverflow) 1973-03-12
DE1804454A1 (de) 1969-11-20
FR1596970A (enrdf_load_stackoverflow) 1970-06-22
DE1804454B2 (de) 1973-02-15
DE1804454C3 (de) 1973-09-20
CH487256A (fr) 1970-03-15
JPS4820970B1 (enrdf_load_stackoverflow) 1973-06-25
GB1223197A (en) 1971-02-24

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