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Publication numberUS3414502 A
Publication typeGrant
Publication dateDec 3, 1968
Filing dateJan 18, 1965
Priority dateJan 18, 1965
Publication numberUS 3414502 A, US 3414502A, US-A-3414502, US3414502 A, US3414502A
InventorsPorrata Louis R, Young Clive R
Original AssigneeColumbia Broadcasting Syst Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electroplating apparatus for use with a phonograph record matrix
US 3414502 A
Abstract  available in
Images(1)
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Claims  available in
Description  (OCR text may contain errors)

DeC- 3, 1968 R. Pcmmm'A ET AL 3,414,502

ELECTROPLATING APPARATUS FOR USE WITH A PHONOGRAPH R RD MATRIX Filed Jan.

meir ArrbR/VEYS United States Patent O York Filed Jan. 18, 1965, Ser. No. 426,303 7 Claims. (Cl. 204-281) ABSTRACT OF THE DISCLOSURE An electroplating fixture which masks the rim of an object to be electroplated in an electroplating bath from the bath and which includes a loop of elastomeric material formed with two opposed inner side faces which define a longitudinal recess in the loop adapted to receive the rim of the object.

This invention relates to an electroplating fixture and, more particularly, to an improved apparatus for suspending an object by its rim in an electroplating bath so that no metal is deposited on the rim and one side of theobject.

In the production of disc phonograph records, for example, several electroplating operations are performed in the manufacture of the negative matrices or stampers from which the phonograph records are formed by a molding or pressing operation. A negative metal master is first formed from the original master into which the sound groove has been cut. Then a positive mother plate is formed from the negative metal master. Finally, the stamper is formed from the mother plate. These three operations are all carried out lby electroplating.

The thin metal matrix (original master, negative metal master or mother plate) is conventionally clamped to a more sturdy backup disc at the center through the usual center hole in the matrix. The backup disc has one conductive face for making electrical contact with the matrix. A masking ring is used to hold the periphery of the matrix to the backup disc, but the conventional ring has several basic disadvantages. It permits metal to be plated around the outside edge or rim of the matrix resulting in an undesirable metal overlap. In order to permit the separation of the matrix and the derivative part, it is necessary to grind, file, Vsand or cut the overlap. A high rejection rate of the derivative matrices results from these techniques, accompanied by a corresponding increase in cost for producing matrices and therefore phonograph records. Furthermore, the conventional masking rings do not provide sufiicient clamping between the matrix and the backup disc, so that an additional clamp at the center is required.

Accordingly, it is an object of the present invention to overcome the above-mentioned difficulties of conventional electroplating fixtures for thin metal matrices such as those required in the production of phonograph records.

Another object of the invention is to provide a novel electroforming masking ring which prevents any metal overlap from being electroplated around the rim of the matrix.

A further object of the invention is to provide an improved ring which clamps the rim of a matrix so securely to a backup disc that no additional clamping is required at the center of the matrix.

These and other objects and advantages of the invention are attained by providing a ring formed with an annular recess adapted to receive the backup disc and lthe matrix. The ring is preferably of elastomeric material, and in one embodiment the recess is formed between two 3,414,502 Patented Dec. 3, 1968 rice side walls, at least one of which has an inner face sloping inwardly toward the other side wall. In another embodiment at least one of the side walls has a first inner face which slopes inwardly toward the other side wall and a second inner face which slopes from the first face inwardly away from the other side Wall. According to a third embodiment the two side walls have opposed inner faces which are substantially parallel.

All of the above is more fully explained in the following detailed description of several preferred embodiments of the invention, this description being illustrated by the accompanying drawings wherein:

FIG. 1 is a simplified perspective view, partially in schematic form, of an electroplating -bath including a fixture embodying the present invention, wherein a matrix is clamped to a backup disc by a masking ring;

FIG. 2 is an enlarged sectional view of the fixture taken along the line 2--2 of FIG. l;

FIG. 3 is an enlarged fragmentary view in section of the fixture of FIG. 2;

FIG. 4 is a fragmentary view in section of the masking ring of FIG. 3, the backup disc and the matrix Vbeing removed;

FIG. 4A is a fragmentary view in section of the matrix and the derivative part plated thereon after completing an electroplating operation employing the apparatus of FIGS. 1-4;

FIG. 5 is a fragmentary view in section illustrating another masking ring according to the invention clamping a matrix to a backup disc;

FIG. 6 is a fragmentary View in section of the masking ring of FIG. 5, the backup disc and the matrix being removed;

FIG. 6A is a fragmentary view in section of the matrix and the derivative plate after completing an electroplating operation employing the masking ring of FIGS. 5 and 6; and

FIG. 7 is a fragmentary view in section showing still another masking ring according to the invention.

In the typical embodiment of the invention shown in FIGS. 1-4, a tank 10 contains a suitable electrolyte 11. Suspended in the electrolyte are a cathode 12 and an anode 13, the anode being of the material to be deposited on the cathode. The electrodes 12 and 13 are electrically connected to a source 15 of direct current. The operation and techniques of electroplating are well known and need not be explained here.

The cathode 12 includes the matrix 16, the side 17 0f which carries the program information which is eventually to be pressed or molded into the finished phonograph record. In producing the negative matrix or stamper from which the record is formed, several derivative matrices are successively formed by electroplating. In each operation the new part is plated onto the side 17 of the original part or matrix 16.

The matrix 1-6 is clamped to a backup disc 18 which is preferably of electrically non-conductive material but has an electrically conductive face (not shown) adapted to make contact with the matrix. The backup disc is mounted at its center to a shaft 19 of an electrically conductive material such as copper which makes electrical contact at one end with the electrically conductive face, the opposite end of the shaft being adapted to be connected to the source 15. The shaft is encased in a suitable insulating cover 20, except for its free end, so that no metal is deposited on the shaft during the electroplating operation.

The rim of the matrix is clamped to the rim of the backup disc by a masking ring 21, which is preferably made of an elastomeric material such as rubber. The masking ring, when viewed in cross-section, includes a backup wall or first side wall 22 extending radially inwardly, .e., towards the center of the ring, which s adapted to abut the backup disc 18, and an end wall 23 extending substantially perpendicularly from the backup wall. The end wall is formed with a second side wall or flange 24 extending radially inwardly therefrom, so that an annular recess 25 is formed between the backup wall and the ange. The inner face 26 of the flange slopes from the end wall inwardly toward the backup wall to a rim 27. The distance from the rim to the backup wall is preferably less than the combined width of the backup disc 18 and the matrix 16, while the width of the recess at the end wall is greater than this combined width. When the masking ring is snapped over the rims of the backup disc and the matrix, the end wall and the flange are flexed slightly outwardly (see FIG. 3), and the matrix is securely clamped to the backup disc, the greatest force being applied at the rim 27. Due to the excellent clamping action at the rim of the matrix, no additional clamping is required at the center of the matrix as is necessary with conventional masking rings, so that it is possible to produce matrices Without center holes with a masking ring according to the present invention. It is apparent that this masking ring can also be used in the production of matrices with center holes, if desired.

Furthermore, there is no creep of metal deposit past the point of contact between the rim 27 and the matrix 16 to form a metal overlap around the rim of the matrix. FIG. 4A illustrates in full lines the rim of the new part or derivative matrix 30 which is electroplated onto the side 17 of the matrix 16 when the matrix is clamped by the ring 21. The metal overlap around the matrix 16 which is permitted by conventional masking rings is shown in phantom at 31. It is apparent that this overlap must be removed by grinding, filing, sandingr or cutting, which is not only costly in itself but is destructive of a considerable number of derivative matrices. In contrast, the new part 30 is readily stripped or separated from the matrix 16 by hand, no tools being required.

The derivative matrix produced by each electroplating Operation has a diameter slightly smaller than the original matrix (see FIGS. 4A and 6A), but one masking ring can be used for the several electroplating operations in the manufacture of stampers, inasmuch as the ring is of elastomeric material and is stretched around the matrix and the backup disc.

It can be seen that a small bead 32 is formed at the rim of the new part 30. This bead is caused at the region of high current density adjacent the rim 27, because of the slope of the lower face 33 of the iiange 24 outwardly from the rim. Although this bead does not impede the stripping of the original and derivative matrices, it can be eliminated, if desired, by using a masking ring 35 of the type illustrated in FIGS. 5 and 6. Like parts in these figures and in FIGS. 3 and 4 respectively, are designated by like primed reference numerals in FIGS. 5 and 6. The

iiange 36 extending from the end Wall 23 is provided i with a Shielding lip so that the flange has a first inner face 26 sloping from the end wall inwardly toward the backup Wall 22 to a rim 27, and a second inner face 37 sloping from the rim 27' inwardly away from the backup wall. The distance from the rim 27 to the backup wall and the width of the recess at the end wall are preferably less than and greater than, respectively, the combined width of the matrix and the backup disc. When the matrix and the backup disc are inserted into the recess 25 they are securely clamped as before, but there is a region of low current density adjacent the rim 27', inasmuch as the second inner face 37 slopes inwardly while the lower face 33 of the iirst embodiment slopes outwardly. FIG. 6A shows the shape of the rim 38 of the new part 39 which is formed on the matrix 16 when the matrix is `clamped to the backup disc by the ring 35. This rim 38 is shaped in conformity with the second inner face 37 of the ring 35 as viewed in FIG. 5.

FIG. 7 illustrates still another embodiment of the invention in which a masking ring 40 of generally circular cross-section is formed with two side Walls 41 and 42 spaced by an end wall 43. The inner faces 44 and 45 of the side walls 41 and 42, respectively, are substantially parallel and are so spaced that the backup disc and the matrix are snugly received in the annular recess 46 formed thereby, that is, the two side walls are slightly spread by the backup disc and the matrix. If a bead at the rim of the derivative plate is to be avoided, the ends of the side walls 41 and 42 may be formed with shielding lips similar to the one illustrated in FIGS. 5 and 6.

Although this invention has been described with reference to specific embodiments, modifications and variations will readily occur to those skilled in the art. For example, an object other than a phonograph record matrix may be clamped at its rim to the rim of an appropriate support member by any masking ring according to the present invention for suspension in an electroplating bath. Furthermore, the masking ring can be modified to take the form of a loop for use with an object Whose rim is not circular. In addition, the masking ring may be used to mask the rim of an object to be electroplated from the electroplating bath if the object is supported by means other than a backup disc, for example if the object has a suitable hole by which it may be clamped to a support member. Therefore, the invention is not to be construed as limited to the physical embodiments described, but all such variations and modifications are included within the intended scope of the invention as defined by the following claims.

We claim:

1. Apparatus for supporting a phonograph record matrix to a backup disc having an electrically conductive face engageable with the matrix comprising a ring of elastomeric material including a backup wall extending radially inwardly and an end wall extending generally perpendicularly from the backup wall, the end wall being formed with a ange extending radially inwardly therefrom, the -backup wall and the flange forming a recess in which the backup disc and the matrix are adapted to be received, the tiange having a iirst inner face sloping inwardly toward the backup wall to form a rim, the distance between the rim and the backup wall being less than the combined width of the backup disc and the matrix, whereby the backup disc and the matrix flex the ange to provide a clamping action in which the greatest force is applied at the tiange rim so that the surfaces of the matrix under the ring and the backup disc are masked from the electro-plating bath and additional clamping of the matrix to the backup disc is unnecessary.

2. Apparatus according to claim 1 wherein the ange has a second inner face sloping from the rim inwardly away from the backup wall.

3. Apparatus according to claim 1 wherein the width of the recess at the end wall is greater than the cornbined width of the backup disc and the matrix.

4. Apparatus for suspending matrix in an electroplating bath so that only one side of the matrix is electroplated comprising a backup disc of electrically non-conductive material having an electrically conductive face adapted to make contact with the matrix,

insulated means for conducting electrical current to the electrically conductive face, and

a ring of elastometric material including an end wall and two side walls which form an annular recess adapted to receive the backup disc and the matrix.

5. Apparatus according to claim 4 wherein the side walls have opposed inner faces which are substantially parallel.

6. Apparatus according to claim 4 wherein at least one of the side walls has an inner face sloping inwardly toward the other side wall.

7. Apparatus according to claim 4 wherein at least one of the side walls has a first inner face sloping from the 6 end wall inwardly toward the other side Wall and a second 2,890,160 `6/ 1959 Hunting et al. 204-281 3,239,443 3/1966 Bryan et al. 204-196 inner face sloping inwardly away from the other side wall.

FOREIGN PATENTS Referencs Cited UNITED STATES PATENTS 5 4941193 3/1930 Germany- 1,226,856 5/1917 Bradley 118-500 2,731,947 1/1956 Harder 118 500 HOWARD S. WLLIAMS,Prlma1y Exammer.

D. R. JORDAN, Assistant Examiner.

2,153,188 4/1939 Hickman.

UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 3,414,502 December 3, 1968 Louis R. Porrata et al.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 32, after "matrix" insert in an electroplating bath and adapted to clamp the matrix line 56, after "suspending" insert Signed and sealed this 17th day of March 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. F letchei', Jr.

Commissioner of Patents Attesting Ufficer

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3527679 *Jan 19, 1968Sep 8, 1970Aerodex IncMolded reusable masking for selective coating,particularly electroplating
US3682135 *Feb 27, 1968Aug 8, 1972Monsanto CoShielding apparatus for plastic articles
US3847779 *Oct 26, 1972Nov 12, 1974Dowa Mining CoAutomatic apparatus for stripping deposited metal from a cathode plate in electrowinning process
US3994784 *Apr 1, 1976Nov 30, 1976Optical Sciences Group, Inc.Metal replication of Glass dies by electroforming
US4069131 *Nov 17, 1975Jan 17, 1978Glyco-Metall-Werke Daelen & Loos GmbhMounting and holding fixture for electroplating uniform thickness metallic deposits
US4092234 *Jan 31, 1977May 30, 1978Ncr CorporationMethod of fabricating diffraction grating masters and apparatus therefor
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US5785826 *Dec 26, 1996Jul 28, 1998Digital MatrixApparatus for electroforming
US20040055873 *May 2, 2003Mar 25, 2004Digital Matrix CorporationApparatus and method for improved electroforming
WO1998029581A1 *Dec 16, 1997Jul 9, 1998Digital MatrixApparatus and method for electroforming
Classifications
U.S. Classification204/281, 204/297.5, 204/297.16, 205/68, 118/503
International ClassificationC25D17/06, C25D5/02
Cooperative ClassificationC25D5/02, C25D17/06
European ClassificationC25D5/02, C25D17/06