Chemistry: electrical and wave energy – Apparatus – Electrolytic
Reexamination Certificate
1998-10-23
2001-01-23
Gorgos, Kathryn (Department: 1741)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
Reexamination Certificate
active
06176985
ABSTRACT:
TECHNICAL FIELD
The invention relates to electroplating apparatus and in particular to apparatus for making high current connections to a workpiece which are sealed from contact with the electroplating solution.
BACKGROUND OF THE INVENTION
Electroplating is widely practiced in the printed circuit industry to add layers of various metals to other conductors. Copper may be plated to increase the thickness of conductors. Layers of nickel and gold are routinely added to copper for protection to prevent oxidation. A great variety of materials, thicknesses and layers are known in the electroplating art.
Dendrite surfaces are also applied using electroplating techniques with emphasis on pulsed high currents. Such dendrite surfaces, also referred to as “nodules” or “cones”, have many uses in the circuit board industry which by way of example are shown in U.S. Pat. Nos. 5,435,057, 5,298,685, 5,185,073, 5,190,463, 5,118,299, 5,019,944 and 5,764,071. A method of making dendrites is described in U.S. Pat. No. 5,172,473 which is incorporated herein by reference.
Workpieces to be plated may be placed on an electroplating rack which is constructed to mechanically hold and provide electrical connection(s) to the workpiece(s). For example, Coombes et al describes a molded rack in U.S. Pat. No. 4,714,535. Conventional plating racks apply pressure, generally in the form of a spring force or a gripping force at the point(s) of electrical connection. This point(s) is generally at a location on the workpiece which is not visible when the workpiece is used as a final product.
In order to have a uniform plating thickness over a relatively large area when high plating currents are involved, establishing a good electrical contact with workpieces is necessary. Making good contact, however, has been a problem in a high volume manufacturing situations because the contact must be made and removed quickly as the workpiece is transferred from tank to tank of various electroplating and rinsing solutions. Furthermore, the contact is subject to exposure to electroplating fluids many of which are acidic or alkaline. For example, nickel is usually plated at a Ph of 3.5-4, gold at 5.5 to 7, and palladium at 8-9. Usually the contact will need to be immersed in the plating bath along with the workpiece during electroplating. Continuously moving contacts such as a moving belt as described by Smith et al in U.S. Pat. No. 4,818,349 or other continuous contact arrangements in U.S. Pat. Nos. 4,885,071, 5,017,275 and 5,389,220 cannot provide the necessary high current capability in a small area of the workpiece. Such exposure to fluids may degrade the contact either during plating or prevent its re-use on subsequent workpieces.
OBJECTS AND SUMMARY OF THE INVENTION
It is therefore a principal object of the present invention to enhance the electroplating art by providing a plating rack with enhanced, reusable, high current contacting capability.
It is another object to provide a high current contacting capability over a small contact area.
It is a further object to provide an enhanced contacting capability usable at a plurality of contact spots on a workpiece.
It is yet another object of the invention to provide a method of electroplating a workpiece which can be accomplished in an improved and facile manner.
These and other objects are attained in accordance with one embodiment of the invention wherein there is provided an electroplating rack for holding a workpiece during plating, comprising a supporting structure having an electrically insulative surface positioned about an electrically conductive core with at least two openings in said insulative surface exposing at least two areas of said electrically conductive core, a plating current source contact attached to a first of the two areas of the electrically conductive core, a second contact for providing an electrical connection to a workpiece, the second contact attached to and making electrical connection to a second of the two areas of the electrically conductive core, and an electrically insulative gasket positioned about the second contact to prevent electroplating fluid from contacting the second contact when the second contact provides the electrical connection to the workpiece.
In another embodiment of the invention there is provided a connection for use in electroplating a workpiece, comprising an electrically conductive core member of elongated construction, an electrically insulative member substantially about the electrically conductive core member, the electrically insulative member including at least two openings therein for exposing respective open areas of the electrically conductive core, the first exposed area adapted for connecting to a power source and the second exposed area adapted for being electrically connected to a workpiece, and an electrically insulative member adjacent the workpiece for substantially preventing a solution from contacting the core member in the region of the second area.
In yet another embodiment there is provided a method of electroplating a workpiece, comprising the steps of providing a supporting structure having an electrically insulative surface positioned about an electrically conductive core with at least two openings in the insulative surface exposing at least two areas of the electrically conductive core, attaching a plating source contact to a first area of the electrically conductive core, attaching a second contact for making an electrical connection to a workpiece, to a second area of the electrically conductive core, the second contact making electrical connection to the electrically conductive core, positioning an electrically insulative gasket about the second contact, and bringing the workpiece into electrical connection with the second contact so that the gasket prevents electroplating fluid from contacting the second contact when the second contact provides the electrical connection to the workpiece.
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Downes, Jr. Francis J.
Galasco Raymond Thomas
Japp Robert Maynard
Surowka John Frank
Gorgos Kathryn
International Business Machines - Corporation
Pivnichny John R.
Smith-Hicks Erica
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