US3582477A - Selective electroplating method - Google Patents

Abstract

A METHOD OF SELECTIVELY PLATING A LAYER OF METAL FROM A SOLUTION OF ELECTROLYTE ONTO PREDETERMINED AREAS OF AN ELECTRICALLY CONDUCTIVE MEMBER WHICH FUNCTIONS AS A CATHODE. A FORMED, CATHODIC, AND ELECTRICALLY CONDUCTIVE MASTER IS PLACED ON THE SURFACE OF THE MEMBER TO BE SELECTIVELY PLATED, THE MASTER HAVING EXPOSED PORTIONS CORRESPONDING TO THE AREAS TO BE SELECTIVELY PLATED. AN ANODE IS SPACED FROM THE MASTER AND THE CATHODE AND AN ELECTRIC PLATING CURRENT IS APPLIED BETWEEN THE CATHODE AND THE ANODE SO THAT THE SELECTED AREAS ARE PLATED.

Description

June 1, 1971 GELB 3,582,477-

SELECTIVE ELECTROPLATING METHOD Filed Feb. 20, 1969 2 Sheets-Sheet 1 INVENTOR #40 61545 ATTORNEY;

June 1,1971 GELB 3,582,477

' SELECTIVE. ELECTROPLATING METHOD Filed Feb. 20, 1969 ZSheets-Sheet z INVENTOR ATTORNEYf 3,582,477 SELECTIVE ELECTROPLATING METHOD 6 Paul Gelb, 43--23 Coldeu St., Flushing, NY. 11355 Filed Feb. 20, 1969, Ser. No. 800,865 Int. Cl. B44c 1/04; C23b /70 U.S. 'c1. zo4-1s 3 Claims ABSTRACT OF THE DISCLOSURE A method of selectively plating a layer of metal from a solution of electrolyte onto predetermined areas of an electrically conductive member which functions as a cathode. A formed, cathodic, and electrically conductive master is placed on the surface of the member to be selectively plated, the master having exposed portions corresponding to the areas to be selectively plated. An anode is spaced from the master and the cathode and an electric plating current is applied between the cathode and the anode so that the selected areas are plated.

This invention relates to selectively plating a layer of metal onto predetermined areas of a metal cathode member.

The desirability of being able to plate a precious metal such as gold onto a metal surface, e.g., various items of silverware such as trays, plates, bowls andthe like has long been recognized. However, as far as it is known, it has not been feasible to do this by any method which is simple enough, yet accurate enough, to give an economical and commercially acceptable product. Accordingly, it is an object of the present invention to provide a method for selectively plating a layer of metal onto a metallic member which is economical, does not require large capital investment, and may be performed with a minimum of hand labor.

The foregoing and other objects and advantages of the present invention will be apparent to those skilled in the art from considering the following description of the drawings of the preferred embodiments of the invention, but such description and drawings should not be considered as limiting the scope of the invention.

In the drawings:

FIG. 1 is a top view showing a silver dish having a central bowl portion selectively plated with gold to leave a silver monogram letter;

FIG. 2 is a side schematic view showing apparatus for carrying out the present invention of selectively electroplating;

FIG. 3 is a top view of the dish to be selectively plated showing the positioning of non-conductive spacers electrolyte and a holding magnet as well as a metal master which defines the monogram letter;

FIG. 4 is a view similar to FIG. 1 of a dish wherein the monogram has been plated in gold and the bowl of the dish has been allowed to remain in silver;

FIG. 5 is similar to FIG. 2 but shows the type of master used to achieve the result of FIG. 4; and

FIG. 6 is an alternate method of providing the gold monogram of FIG. 4 but using a porous cellular carrier for the electrolyte.

Referring to the drawings, and praticularly to FIG. 1, a silver dish 10 is shown which has thereon a selected area 12 which is to be gold plated and an area 11 in the form of the letter P which is to remain unplated.

Apparatus for carrying out the present invention is illustrated in FIG. 2. A holding magnet 14 is set in place and on top of the magnet the dish 10 to be plated is placed. A metal master 16 corresponding to the area 11 to be ice unplated is then placed in the dish 10. Non-conductive spacers 18 are-spotted about the flange of the dish 10. It is to be understood that a non-conductive spacer such as a perforated plastic piece may similarly be used as a spacer and merely positioned on top of the metal master 16 if desired. Also the anode may be supported above the master by any other suitable means.

Into the dish 10 a suitable electrolyte 17 is placed. In

actual gold plating, the electrolyte used was a gold cyanide,

either patassium or sodium gold cyanide, KAu(ON) or NaAu(CN) However, a gold chloride electrolyte may be used if desired, or other plating solutions which are well known to those skilled in the art.

In the illustrated embodiment, an anode member 22 conforming to the dish 10 is placed on top of the spacers 18 and held in a spaced position relative to the dish and the master. Clips 24 are used to connect an anode lead 26 to the anode 22 and a second lead 28 is connected to the cathode 10. The leads 26 and 28 are then connected to a power source 30. Such power-sources are well known and provide low voltage, low current D.C. power.

As an example of the present invention a dish 10 was placed on a magnet 14 and a thin steel master 16 was placed on the dish so that the dish and master served as a composite cathode. The anode 22 was positioned in spaced relation to the cathode and connection made to the power source. Using a solution of potassium gold cyanide, a voltage of two and one-half volts and a current of .25 amp. for three minutes gave satisfactory plating.

It was found that the use of the composite cathode formed by the dish 10 and the metal master 16 resulted in a sharp outline defining the plated areas from the unplated areas.

In order to form a master 16 for more sophisticated detailed areas, such as the border 15 of dish 10, it is recommended that an iron plating bath be used to electrofrom about a piece, similar to that to be plated, a metal master corresponding exactly to the pieces to be plated. The thin master formed by such electroform process, which is Well known to those in the plating art, is then used in the present invention by cutting out the areas which are to be selectively plated. The use of such a formed master gives excellent registry and insures the proper cooperation between the master and the piece.

In addition, if desired, the anode may be formed by electroforming so that it corresponds substantially to the surface of the piece to be plated and more accurate control between the cathode and the anode may be obtained.

If desired, the magnetic holder can be formed by elecforming. After the holder is formed it can then be permanently magnetized or used with an energizable electric magnet.

In the embodiment of FIG. 4 the area to be selectivey plated consists of the monogram letter P 12a and the border area 15. To achieve this effect the master 16a is preferably formed so that it corresponds to the piece 10 and has cut-out portions 17 and 19 in the form of the areas to be plated. The relationship between the anode, dish, spacers and the master as shown in FIG. 5 are substantially the same as those shown in FIG. 2.

Since the present invention utilizes the principle of creating a resist to plating in the areas to be left unplated, advantageously the magnet may also be made as a plating member with the dish 10 so that a sandwich is created leaving only the areas to be plated exposed. Therefore, the sandwich of magnet, dish (piece) and master may be put into a suitable plating bath with the sandwich placed onto a cathode and any suitable anode added to these both to accomplish the plating.

In another embodiment of the invention as shown in FIG. 6, the metal master 16 is replaced with a porous cellular member constructed out of a foam material such as verysmall pore cellular rubber and. this porous member 32 serves as a carrier for the electrolyte. If a design is placed on the member 32 so that only the portions to be plated are not in contact with the dish 10, an anode 34 may be placed above the member 32 and connected by suitable means such as the stud 36 to the anode 26. By this means, a deposit of gold from a suitable electrolyte solution (such as gold cyanide) carried by the sponge member 32-may be selectively deposited on the surface of the dish beneath the raised portions.

In still another embodiment the member 32 is formed from magnetically attracted porous material. This may be accomplished by the use of ferrite powder compounded into the member when it is formed. With such a member the anode 34 may be made magnetic so as to provide a low force magnetic pull against the member 32 tending to lift it away from the surface to be plated. The base magnet 14a (as shown in FIG. 6) can be of the electrical type so that it has a magnetic pull of substantially higher force than the anode 34. By intermittently energizing the magnet 14a the anode 34 will lift the member 32 away from the surface of dish 10 for sufiicient time to release the trapped gases.

Since the magnet 14a pulls the member 32 tightly against dish 10, a slight flow of electrolyte during the lifted condition will not cause plating where not desired. The strong magnetic pull of magnet 14a causes a resist to plating where the member 32 contacts the dish 10.

It is believed that the electrical conductivity of the master 16 whereby it becomes electrically joined to the dish 10 to form a composite cathode assists in the selective plating obtained. While preferred embodiments of the present invention have been described, it is to be understood that various modifications may be made within the scope and spirit of this disclosure.

What is claimed:

1. A method of selectively plating a layer of metal onto a predetermined area of an electrically conductive member adapted to function as a cathode comprising the steps of (1) connecting said memberto a source of electrical current whereby said member is cathodic;

(2) positioning adjacent to said member a magnetically attractable formed conductive master having exposed portions therein corresponding to the areas of the member to be selectively plated;

(3) positioning a magnet adjacent said memberwhereby said master is attracted by the magnet and fixed in placerelative to the member by holding power of the magnet;

(4) spacing an anode'from the cathode member;.

(5) supplying a plating electrolyte at the selected areas of the member who plated; and

(6) applying an electric plating current between the cathodic member and the anode whereby the selected areas of the member are plated with a metal.

2. A method of selectively plating a layer of metal as defined in claim 1 wherein the member has a surface of silver in the areas to be plated and the metal plated thereon is gold or a gold containing alloy.

3. A method of selectively plating a layer of metal as defined in claim 2 wherein the electrolyte is a solution of gold cyanide or chloride.

References Cited UNITED STATES PATENTS 981,750 '1/1911 Dollinger 204-8 2,475,434 7/1949 Moss 204-15 2,890,992 6/1959 Hoehl 204-297 3,223,599 12/1965 Taylor 204--l5 3,261,769 7/1966 Coe et al. 20415 3,415,723 12/1968 Bedi et al. 204-15 FOREIGN PATENTS 417,477 2/ 1967 Switzerland.

TA-HSUNG TUNG, Primary Examiner T. TUFARIELLO, Assistant Examiner Us. 01. X.R. 204-297M

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