Chemistry: electrical and wave energy – Apparatus – Electrolytic
Reexamination Certificate
1999-04-19
2001-05-08
Valentine, Donald R. (Department: 1741)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
C204S273000, C204S275100, C204S237000
Reexamination Certificate
active
06228230
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an electroplating apparatus. More particularly, this invention relates to an apparatus for electroplating of small parts.
BACKGROUND OF THE INVENTION
In electroplating process, the parts to be plated are connected to the cathode (negative pole) of a DC power supply. An anode with the metal used in plating is connected to the anode (positive pole) of the DC power supply. The parts to be plated and the anode with the metal used in plating are immersed in an electroplating solution containing metal ions. When the power supply is turned on, the metal ions are reduced and deposited on the surface of the parts to form a metal film. The metal on the anode is oxidized and dissolved in the plating solution to replenish the metal ions in the solution.
For electroplating of large parts, the parts are typically suspended on a rack that is connected to the cathode of the power supply. However, for electroplating of small parts including electronic components, suspension of the parts on a rack often is impractical due to their small sizes and large quantities.
For electroplating of small parts, there are various disclosures in the prior art which seek to overcome the size and quantity limitations. For example, U.S. Pat. No. 5,490,017 discloses an electroplating process wherein small parts are placed in a rotating plating barrel. Another example is contained in U.S. Pat. No. 5,817,220, which discloses a rotatable cage employing a parts container. While these designs provide for agitation of the small parts in order to achieve increased uniformity of plating, rotational plating has numerous significant drawbacks.
During rotational plating, as suggested in the above-referenced examples, the parts and the conductive media tend to segregate due to differences in shape, size, and mass, which reduces the plating uniformity on the parts and the overall quality of the production run. Often, the plating solution or electrolyte, which is in contact with the parts and conductive media, is not well mixed with the bulk solution. A typical drawback of the prior art is a lack of plating uniformity along the surface area of the parts. Further, a significant portion of the metal is deposited on the media, resulting in excessive use of metal and electricity thereby causing wastage. Additionally, in plating of some soft metal parts, such as lead and tin, the tumbling with media causes smearing of the soft metals and extension of plating to the non-metalized portion of the parts. Furthermore, separation of the parts and media following rotational plating and maintenance of the media used in such plating are time consuming tasks.
In view of the aforementioned deficiencies within the prior art, it will be desirable to have an apparatus for electroplating small parts which maximizes plating uniformity. It will be further desirable to electroplate small parts in a manner which exhausts the least amount of anode metal and electricity. It will be advantageous to be able to electroplate small soft metal parts in a manner which decreases smearing and unwarranted deposit of metals on the non-metalized portions of such parts and to avoid the time consuming tasks of separating parts and media after plating and maintaining the media used in barrel plating.
SUMMARY OF THE INVENTION
According to the present invention, an electroplating apparatus for small parts is provided. The apparatus comprises an electroplating bath for holding an electrolyte and electroplating anodes, which is adaptable to be connected to a source of positive electrical charge.
The parts to be electroplated are enclosed in a container that is immersable in the electrolyte. The container has at least one screened compartment for holding the parts to be electroplated, and the compartment incorporates an electrically conductive screen as its base portion, on which the parts are settled. The conductive screen is connected to the negative pole of a power supply to function as the cathode.
A fluid transport means circulates freshly ionized electrolyte into the parts compartment and directs a flow of the electrolyte to periodically tumble the parts in the compartment. Thereafter, the parts are shaken by a shaker to level the parts to maximize the surface and electrical contact between the parts and the screen when they are settled on the screen.
In the embodiment of the invention, the tumbling and shaking of the parts can be undertaken sequentially. The tumbling can be carried out for a predetermined period of time to enable part separation from the cathode, which is then followed by the actuation of the shaker and the settlement of the parts. In alternative embodiments of the invention, the container can be of perforated panel construction. Also, the container can include a divider to provide a plurality of parts compartments for electroplating a variety of different parts.
These and other aspects and advantages of the invention will become apparent from the following detailed description, and the accompanying drawings, which illustrate by way of example the features of the invention.
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Chang Daniel H.
DeoGracias William
Hess Bruce W.
Lamayeau Tom w.
Li Xiang-Ming
AEM, Inc.
Li Kam W.
Procopio Cory Hargreaves & Savitch LLP
Valentine Donald R.
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