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Publication numberUS2500205 A
Publication typeGrant
Publication dateMar 14, 1950
Filing dateApr 12, 1945
Priority dateApr 12, 1945
Also published asDE939416C
Publication numberUS 2500205 A, US 2500205A, US-A-2500205, US2500205 A, US2500205A
InventorsSchaefer Ralph A
Original AssigneeCleveland Graphite Bronze Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method of plating
US 2500205 A
Abstract  available in
Images(3)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

March 14, 1950 R. A. scHAEFER 2,500,205

METHOD OF PLATING V Filed April 12, 1945 3 Sheets-Sheet l TIICICNjESQ 0F PLAZE- e POSITION M011 2065' [IV DEGBEZJ INVENTOR. v RALPH A. SCHAEFER.

March 14, 1950 R. A. SCHAEFER METHOD OF PLATING 3 Sheets-Sheet 2 Filed April 12, 1945 NN OwN OOH 8 QQ Oh Q QQN QNN QQN QMWN QwN a ON v O, INVENTOR.

OQN CNN QQN OWN BWN 8N OWN O: OOH

EQNNNWON 0Q ON Oh RALPH A SCHAEFER ONO OS EN Pow Q3 om mmm .w wmw ooQ March 14, 1950 R. A. SCHAEFER 2,500,205

METHOD OF PLATING Filed April 12, 1945 3 Sheets-Sheet 3 IN VEN TOR. RA LP H A SCHAEFER.

Patented Mar. 14, 1950 METHOD or PLATING Ralph A. Schaefer, Cleveland, Ohio, assignor to The Cleveland Graphite Bronze Company, Cleveland, Ohio, a corporation of Ohio Application April 12, 1945, Serial No. 587,964

Claims.

The present invention relating, as indicated to a method of plating is more particularly directed to the provision of a method of electro-depositing a layer of metal or metallic alloy onto the concave surface of semi-cylindrical articles and to maintaining a sufiiciently uniform thickness of deposited metal so that for many articles and for many uses the variation in thickness, particularly in thin deposits, will make unnecessary or cheapen and simplify any subsequent metal re moving operations, if required. The term uniform, as used herein, is defined to mean a degree of uniformity in which the variations from the average is not more than 5% in thickness circumferentially and the variation in thickness at right angles thereto is substantially zero for approximately 90-95% of the extent of the deposit.

In electrodepositing layers of metal onto curved surfaces, it is very difficult to maintain a uniform thickness of the deposited metal. This is due to the difference in the distance between the anode and the surface of the article being plated, which is the cathode. This difference in distance results in a difference in current distribution over the surface of the article being plated. When electroplating irregular-shaped surfaces, it is a well-known fact that cathode positions nearest to the anode receive the most plate and that there is a resulting build-up on the surface nearest to the anode with the thickness of the plate decreasing progressively as the distance from the anode increases. With semi-cylindrical articles, plated on the concave face, the center of the article will have less plated metal adhering thereto than the lateral edges. The term lateral edges, as used herein, denotes the straight parallel edges of the semi-cylindrical object, the inner or concave surface of which is to be plated. Prior attempts to control the thickness of the plated layer consisted in shaping the anodes toa contour similar to that of the cathode; constructing full cylinders with a centrally located anode; using the bi-polar method in which an insoluble anode of similar contour to the cathode is used in combination with soluble anodes, and also shielding and masking. None of these lend themselves to the economies of the present method.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and pointed out in the claims; the annexed drawings and following description setting forth in detail certain structure embodying the invention, such iii 2 various forms in which the principle of the invention may be used.

In said annexed drawings:

Fig. 1 is a plan view of a semi-cylindrical article which is electroplated on its concave face;

Fig. 2 is an elevational view of the article shown in Fig. 1;

Fig. 3 is a graph showing the variation in thickness of plated metal upon a semi-cylindrical article using various current densities;

Fig. 4 is a diagrammatic view illustrating the arrangement of a semi-cylindrical object, the inner surface of which is to be plated and which itself acts as a cathode with the barrier element which controls the direct electrical circuits between the anode and the portions of the surface;

Fig. 5 is a similar front elevational view of the assembly of Fig. l;

Fig. 6 is a graph showing the variation in thickness of plated metal obtained upon a semi-cylin drical article;

Fig. 7 is another graph showing the variation in thickness of plated metal upon a semi-cylin drical article;

Fig. 8 is a graph showing the variation in thickness of plated metal upon a semi-cylindrical article;

Fig. 9 is a plan view of another means for plating a uniform layer of metal upon the concave surface of a semi-cylindrical article;

Fig. 10 is an elevational view taken along the plane 10-40 of Fig. 9;

Fig. 11 is a plan view of another means for plating a semi-cylindrical article, and

Fig. 12 is a sectional view of the arrangement shown in Fig. 11 on the plane l2--l2.

The articles which it is desired to plate are composed of steel or may be composite structures consisting of a. layer of steel and a layer of an other metal or alloy such as copper-lead or silver. These articles are shaped to finished semi-cylindrical conformity prior to the plating operation. It is desired to holdthe tolerances of the finished plated surfaces as close as possible and to obtain the same thickness of plate on each blank. The ordinary thickness which it is desired to hold is in the neighborhood of .001 inch to .005 inch.

When semi-cylindrical articles are plated in the conventional manner by simply hanging them in the electrolyte, the lateral edges plate to a considerably greater thickness than the center. In Fig. l is-shown a semi-cylindrical article with a steel backing layer i and a plated layer of metal 3. x In Fig.- 2 is shown an elevational view disclosed means constituting, however, but one of B6 of .thesamev article; -Fig.-. .315 ;a graph which shows the variation in thickness obtained at different current densities on semi-cylindrical articles plated in the conventional manner. The curves shown in Fig. 3 were obtained by plating articles similar to I in Fig. l by plating on chromeplated steel blanks. These shells were hung in an electrolyte with the anode a convenient distance away with no attempt to shield any part of the article. The current was passed from the anode to the cathode, using 6 volts as a standard, and the articles were plated for the same period of time. They were withdrawn fromthe bath and the plated layer was stripped from the backing I in one piece, since there is little orno adhesion between a chrome surfaceand the=plated layer. The thickness of this layer was then-carefully measured and set out on thegraphaccording to the number of degrees distant from the lateral edge, shown as 2 in Fig. 1, designated as 0,10 1580 degrees, which is the lateral edge 4. It is quite apparent from the graph :that the deposit of plated metal at the edges 2 and-4 ofitheshell Ll is excessive where a uniformzthickness' is des red. Curves A, B, C and Din .Fig. .3show1the effect ofdiiferent current densitieson the uniformity of the plate thickness. The deposit increases in uniformity as the current density decreases, and if it were practical and commercialtoreduce the current density sufficiently; it is conceivable that a nearly uniform deposit could besecured at a very low current density. -Obviously, however, this would be an extremely slow anduncommercial procedure.

For all practical purposes, the'limitsofcurrent density range from 5 amperes per square foot upward, and it is apparent from the graph of Fig. 3 that a uniform'thickness of metalicannot be plated on a semi-cylindricalarticle.at'these rates by conventional-methods'and with equivalent economy.

In practicing the principle of the invention;the following means will serve -as illustrations. One method of plating shells is shown as an assembly in Fig. 4, the slot opening 8 beingiadjustable in width and having a length'not greater thanthe width of the shell i. The article to'be plated I, which represents the cathode in the plating cell, is mounted against an insulating barrier plate I5 with the'lateral edges of the article in substantially sealing contact withthe face ofthis plate I5. The anode It may be placed in any convenient position in the electrolytic-cell in frontof the insulating barrier member I 5. 'The primary plating circuit is fromthe anode I 6 through the-slot-B to the concave surface of article I. Under these conditions, asecondary'plating circuit is'from the anode I6 to the convex surface of the article I. The thickness and uniformity of the plate on the convex surface will vary with the type of the electrolyte, current density and composition of the plating bath. 'In cases where auniform convex surface is not required, this procedure is satisfactory. If, howevena uniformly plated or nonplated convex surface is required'it is conveniently accomplished by either protecting the'convex surface with an insulating material while plating the concave surface or by introducing'controlled resistance between theanode I6 and the convex surface of the article Ito give-a. definite regulated thickness and uniformity to'thisdeposit.

One method of preventing plating on the "convex surface of the shell is byapplyingua material such as wax, or other masking compound, to the back and then performing theplating'operation away throughthe openingx39.

4 by means of the set-up described with reference to Figs, 4 and 5. After plating, the masking material can be stripped off in the conventional manner. This method involves considerable t me, however, and in order to eliminate the operation of masking and at the same time to provide a means for controlling the thickness of plated metal on theback, the set-up shown in Fig. 9 and 10 has been-devised. The article I, which is to be plated, is placed inside a box II, which is "made up of an insulating material such as hard rubber or the like, and is completely sealed electrically, except for the slot opening I8 in the face 20. 'This-slotopening is adjustable in width and is no greater in length than the length of the lateral'edges of the shell. The lateral edges of the shell I are held by means not shown securely against the face of the box and the circumferential edges of the shell are sealed by the top and bottom members ofzthe box 23 and 24. The box H "with theshell'l in place is-suspended in the electrolyte 328:.andma'de the negative side. of anelectrical circuit by meansnot shown. 'The anode-l2 isisuspended in the electrolyte *261in'the t-anlc;..251and:'made the positive terminal 'of the electrical circuit. 'Whenthe electrical current is introduced into 'the circuit, .it passes from the anode I9 through the slot I8 to the cathodic shell I, causing a uniform layer of metal to be deposited on 'the concave surface'thereof. .Since the box IT is madeof aninsulating 'materialsand is'tightly sealed electrically, 'noplating will occur 0n the backof'theshell I. Tfit is desired, however, to plate a controlled thickness of metal upon the back of the shell, it can-beaccomplished by controlling'the fit of theba'ck member of the box 22, in such a way. as to allow a portionof the electrical current to enter'through the back of box to deposit metal of the desired thickness. This fit between the back member 22 and the rest'of the box? I I controls the resistance in the electrical circuit'between the anode I9 and the back of the shell I.

Another-method whereby the plating on the :back of the'shell I is'eliminated or becomes of minor importance is illustrated inFigs. l1 and 12. In'this set-up the tank is constructed with an insulating barrier member having a slot opening 34, and the shell "33 is placed against thebarrier'member in 'such amanner that the lateral edges 36and '3'! are firmly seated against the member 3i, by means not shown. The shell '33 :should be lined up with the center line of the slot opening 34 and the length of the slot should nottto be greater than the length of the lateral edges of the shell. The anode 32 is made the positive terminal of an electrical circuit and the shell .33 is made the negative terminal. The electrolyte :35 .is introduced into the tank by means of a supply inlet 38 and rises in the tank, comingiincontact with the concave surface of the shell until it reaches the top 40 of the barrier member3I, at which point it overflows into-theother'side of the tank =4I and is carried The side of the tank 4 I iskept freeof the'electrolyte by controlling 'theroutlet' 39 "and thus there is little or no contact with the back of the shell 33 ."by the electrolyte 35 because of theweir effect :at the top of the'barrier 40. 'The'bottom of thenarticle is of 'course' sealedagainst leakage of electrolyte past theedge thereof.

Tests were 'run with :difierent electroplating .baths, :namely silver .zan'd :lead, using :a shell having :a diameter of approximately :11AM.

The opening of the slot in the barrier was changed to determine the effects on the uniformity of plate. Figs. 6, 7 and 8 show graphically how the thickness of the plated layer approached uniformity as the slot opening was narrowed. The slot opening used with the shells which is described by the graph in Fig. 6 was 4 inches; the slot opening on those described in Fig. 7 was 1.5 inches: and the slot opening on those described in Fig. 8 was 0.5 inch. The shells represented by Fig. 6 were run for four hours, those represented by Fig. 7 for three and a half hours and those represented by Fig. 8 for three and a half hours and all were plated with a current density of 20 amperes per sq. ft.

By using the present method, it is possible to produce electroplated coatings on the concave surfaces of semi-cylindrical articles to the order of .001 to .005 inch in thickness, for example, which are sufliciently uniform so that they may be termed precision surfaces and may be employed for many purposes, as for example in various machine assemblies without any further finishing operations. Actually, therefore, in the above thicknesses an electrodeposited surface can be produced which is of greater uniformity than that which is produced by electrodepositing or by casting a very considerable thicker layer and then machining it to the desired .001 to inch thickness. Thus, for example, semi-cylindrical bearing shells may be coated with an electrodeposited layer of .001 inch (to a 5% tolerance) and with a surface which does not have to be further processed after being deposited.

For any particular appl cation the tolerances o0 allow d in regard to the thickness of plated layer will det rmine the size of opening to have in the barrier element. With very th n layers of p ate, the variation will in most cases not be important but when the des red thickness ranges from .001 of an inch and above the variation may be very important. For example, if a semi-cylindrical article having an internal diameter of 2.9 inches be plated, the barrier element in front of the concave side of the article should have a slot of approximately five-e1 ghths of an inch. in width, the slot. of course, extending vertically of the barrier and in parallelism with the lateral edges of the article to be plated. This gives a ratio between the width of the slot and the diameter of the shell of approximately .215. As a second example, it has been found that a satisfactory width of slot for the plating of an article of a diameter of 4.5 inches, the slot should be one inch, which gives approximately the same ratio of and throughout a considerable range of sizes it has been found that satisfactory unifor mity, within the limits herein specified, can be secured with a ratio between the slot width and the diameter of the article of 25% or less.

It will be apparent from the foregoing description that the present method lends itself to important economies of manufacture since the thickness of a plated coating which is applied can be held to a precision thickness and all further operations which require metal removal can be eliminated. It is also possible, if it is desired, to apply say .010 of an inch of a given metal by electrodeposition and then machine this to a final thickness of .005 inch, although the savings in such an operation would not be as great as if the electrodeposited coating were employed in the condition as deposited and without further operations thereupon.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the process herein disclosed, provided the means stated by the following claims or the equivalent of such stated means be employed.

I, therefore, particularly point out and distinctly claim as my invention:

1. In a method of electroplating a uniform layer of metal of approximately .005 inch or less thick upon the concave surface of a semi-cylindrical article, the steps which consist of placing the parallel edges of the article against and with the concave side facing, an insulating barrier element having a slot opening parallel to and centrally located with respect to the lateral edges of the article and being otherwise impervious to the passage of current, the width of said slot being approximately 25% or less of the diameter of the article, immersing the article and barrier element in an electroplating bath, mounting an anode in the bath external to the article and passing a plating current from said anode to said article as a cathode through said slot.

2. In a method of electroplating a uniform layer of metal of approximately .005 inch or less thick upon the concave surface of a semi-cylindrical article, the steps which consist of placing the article against and with the concave side facing, a flat insulating barrier element having a slot opening parallel to and centrally located with respect to the lateral edges of the article and being otherwise impervious to the passage of current, the width of said slot being approximately 25% or less of the diameter of the article, immersing the article and barrier element in an electroplating bath, mounting an anode in the bath external to the article and passing a plating current from said anode to said article as a cathode through said slot.

3. In a method of electroplating a uniform layer of metal approximately .005 inch or less thick upon the concave surface of a semi-cylindrical article, the steps which consist in mounting an anode and a semi-cylindrical article as a cathode in an electroplating bath, there being interposed between them a flat insulating barrier plate disposed against the parallel edges of the article, said plate being provided with a longitudinal slot parallel with and equidistant from the parallel edges of said article and being otherwise impervious to the passage of current, with such slot having a width approximately 25% or less of the diameter of the semi-cylindrical article and having a length not greater than the length of the parallel edges of the article, and passing a plating current from said anode to the article through said slot.

4. In a method of electroplating a uniform layer of metal and controlling the thickness variation within i5% upon the concave surface of a semi-cylindrical article, the steps which consist in placing the article with its lateral edges against a flat insulating barrier member in an electroplating bath, the barrier member having a longitudinal slot but being otherwise impervious to the passage of current, the width of said slot being less than 25% of the diameter of the article and positioned centrally with respect to the lateral edges of the article, mounting an anode in said bath in a position outside the barrier member and passing a plating current from said anode to said article as a cathode through said slot.

cylindrical article, :the. steps which consist in placing the article with its lateral edges against a flat insulating barrier member in an electroplating bath, the barrier member having a longitudinal slot but being otherwise impervious to the passage of current, the Width of said slot 10 being less than 25% of'the diameter of the article and positioned centrally with respect to the lateral edges of the article, mounting an anode in said bath in a position outside the barrier member and passing a plating current from said anode to said article as a cathode through said slot.

RALPH A. SCHAEFER.

REFERENCES .CITED The following references are of record'in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,587,303 Hart June 1, 1926 1,603,951 Hitchcock --Oct. 19, 1926 1,757,671 Langseth May 6, 1930 1,765,320 Bart June 17, 1930 1,872,221 Bart Aug. 16, 1932 2,086,226 Hoff July 16, 1937 FOREIGN PATENTS 15 Number Country Date,

986 Great Britain of 1896 255,736 Great Britain of 1926 335,161 Great Britain of 1930

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1587303 *Apr 8, 1924Jun 1, 1926Rome Radiation Company IncElectrolytic coating apparatus
US1603951 *Nov 17, 1923Oct 19, 1926Pittsburgh Plate Glass CoProcess for making mirrors or reflectors
US1757671 *Mar 31, 1927May 6, 1930Ohio Brass CoMethod and means of electroplating
US1765320 *Oct 28, 1926Jun 17, 1930Bart Reflector Co IncMethod and apparatus for forming molds
US1872221 *Oct 28, 1926Aug 16, 1932Frink CorpMethod and apparatus for forming molds and articles produced thereby
US2086226 *Oct 25, 1934Jul 6, 1937Du PontPlating apparatus
GB255736A * Title not available
GB335161A * Title not available
GB189600986A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2697690 *Dec 22, 1948Dec 21, 1954Federal Mogul CorpElectroplating rack
US2751340 *Jan 5, 1953Jun 19, 1956Clevite CorpMethod of plating
US6979248May 7, 2002Dec 27, 2005Applied Materials, Inc.Conductive polishing article for electrochemical mechanical polishing
US6988942Jul 20, 2004Jan 24, 2006Applied Materials Inc.Conductive polishing article for electrochemical mechanical polishing
US6991528Jun 6, 2003Jan 31, 2006Applied Materials, Inc.Conductive polishing article for electrochemical mechanical polishing
US7014538Mar 5, 2003Mar 21, 2006Applied Materials, Inc.Article for polishing semiconductor substrates
US7029365Dec 23, 2003Apr 18, 2006Applied Materials Inc.Pad assembly for electrochemical mechanical processing
US7059948Dec 20, 2001Jun 13, 2006Applied MaterialsArticles for polishing semiconductor substrates
US7077721Dec 3, 2003Jul 18, 2006Applied Materials, Inc.Pad assembly for electrochemical mechanical processing
US7084064Sep 14, 2004Aug 1, 2006Applied Materials, Inc.Full sequence metal and barrier layer electrochemical mechanical processing
US7125477Aug 2, 2002Oct 24, 2006Applied Materials, Inc.Contacts for electrochemical processing
US7137868Mar 6, 2006Nov 21, 2006Applied Materials, Inc.Pad assembly for electrochemical mechanical processing
US7137879Mar 30, 2006Nov 21, 2006Applied Materials, Inc.Conductive polishing article for electrochemical mechanical polishing
US7207878Jan 8, 2005Apr 24, 2007Applied Materials, Inc.Conductive polishing article for electrochemical mechanical polishing
US7278911Aug 30, 2005Oct 9, 2007Applied Materials, Inc.Conductive polishing article for electrochemical mechanical polishing
US7285036Nov 21, 2006Oct 23, 2007Applied Materials, Inc.Pad assembly for electrochemical mechanical polishing
US7303462Mar 22, 2005Dec 4, 2007Applied Materials, Inc.Edge bead removal by an electro polishing process
US7303662Aug 2, 2002Dec 4, 2007Applied Materials, Inc.Contacts for electrochemical processing
US7311592Nov 2, 2006Dec 25, 2007Applied Materials, Inc.Conductive polishing article for electrochemical mechanical polishing
US7344431Jul 18, 2006Mar 18, 2008Applied Materials, Inc.Pad assembly for electrochemical mechanical processing
US7344432Oct 31, 2006Mar 18, 2008Applied Materials, Inc.Conductive pad with ion exchange membrane for electrochemical mechanical polishing
US7374644Jun 26, 2003May 20, 2008Applied Materials, Inc.Conductive polishing article for electrochemical mechanical polishing
US7427340Apr 8, 2005Sep 23, 2008Applied Materials, Inc.Conductive pad
US7446041Jun 21, 2006Nov 4, 2008Applied Materials, Inc.Full sequence metal and barrier layer electrochemical mechanical processing
US7520968Oct 4, 2005Apr 21, 2009Applied Materials, Inc.Conductive pad design modification for better wafer-pad contact
US7569134Jun 14, 2006Aug 4, 2009Applied Materials, Inc.Contacts for electrochemical processing
US7670468Sep 15, 2005Mar 2, 2010Applied Materials, Inc.Contact assembly and method for electrochemical mechanical processing
US7678245Jun 30, 2004Mar 16, 2010Applied Materials, Inc.Method and apparatus for electrochemical mechanical processing
US20040082288 *Mar 5, 2003Apr 29, 2004Applied Materials, Inc.Fixed abrasive articles
US20040082289 *Aug 15, 2003Apr 29, 2004Butterfield Paul D.Conductive polishing article for electrochemical mechanical polishing
US20040121708 *Dec 3, 2003Jun 24, 2004Applied Materials, Inc.Pad assembly for electrochemical mechanical processing
US20040134792 *Jun 26, 2003Jul 15, 2004Applied Materials, Inc.Conductive polishing article for electrochemical mechanical polishing
US20040163946 *Dec 23, 2003Aug 26, 2004Applied Materials, Inc.Pad assembly for electrochemical mechanical processing
US20040266327 *Jul 20, 2004Dec 30, 2004Liang-Yuh ChenConductive polishing article for electrochemical mechanical polishing
US20050000801 *Jun 30, 2004Jan 6, 2005Yan WangMethod and apparatus for electrochemical mechanical processing
US20050092621 *Nov 3, 2004May 5, 2005Yongqi HuComposite pad assembly for electrochemical mechanical processing (ECMP)
US20050133363 *Jan 8, 2005Jun 23, 2005Yongqi HuConductive polishing article for electrochemical mechanical polishing
US20050161341 *Mar 22, 2005Jul 28, 2005Applied Materials, Inc.Edge bead removal by an electro polishing process
US20050178666 *Jan 12, 2005Aug 18, 2005Applied Materials, Inc.Methods for fabrication of a polishing article
US20050194681 *Feb 25, 2005Sep 8, 2005Yongqi HuConductive pad with high abrasion
US20050284770 *Aug 30, 2005Dec 29, 2005Applied Materials, Inc.Conductive polishing article for electrochemical mechanical polishing
US20060030156 *Aug 1, 2005Feb 9, 2006Applied Materials, Inc.Abrasive conductive polishing article for electrochemical mechanical polishing
US20060032749 *Sep 15, 2005Feb 16, 2006Liu Feng QContact assembly and method for electrochemical mechanical processing
WO2014167366A1 *Apr 14, 2014Oct 16, 2014Mahle International GmbhElectroplating rack
Classifications
U.S. Classification205/96
International ClassificationC25D7/10, C25D17/06
Cooperative ClassificationC25D17/06, C25D7/10
European ClassificationC25D7/10, C25D17/06