US20090090633A1

US20090090633A1 - Electroplating system with movable support structure providing cathode potential

Info

Publication number: US20090090633A1
Application number: US12/246,450
Authority: US
Inventors: Daniel James Gramarossa
Original assignee: Technic Inc
Current assignee: Technic Inc
Priority date: 2005-03-30
Filing date: 2008-10-06
Publication date: 2009-04-09
Also published as: US20090090632A1; US20060219562A1

Abstract

A processing system, electroplating cell, transport system, cathode contact subsystem and method of providing a cathode contact to the articles being transported within an electroplating cell. The processing system may include a loading station, pre-processing station, electroplating station, post-processing station, unloading station, and a transport system that transports the articles to the various stations. The electroplating cell comprises a container to support a plating fluid bath, and an anode electrode. In one embodiment, the cathode contact system provides a cathode contact to the articles by way of the transport system's electrically-conductive, conveyor structure. In another embodiment, the cathode contact system comprises an electrically-conductive moving conveyor structure adapted to make cathode contact to said articles and move substantially in synchronous with the articles. In yet another embodiment, the transport system comprises a plurality of multi-article carriers supported by a conveyor structure, and adapted to provide a cathode contact to the articles.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims priority to U.S. patent application Ser. No. 11/096,366, filed on Apr. 1, 2005, and entitled “SYSTEM AND METHOD OF TRANSPORTING AND PROVIDING A CATHODE CONTACT TO ARTICLES IN AN ELECTROPLATING SYSTEM,” which, in turn, claims priority to U.S. Provisional Patent Application Ser. No. 60/666,984, filed on Mar. 30, 2005, both of which are incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to electroplating systems, and in particular, to a system and method of transporting and providing a cathode contact to articles in an electroplating system.

BACKGROUND OF THE INVENTION

The electroplating of relatively small articles, such as connector pins and sockets, presents many challenges. These challenges include providing a relatively uniform metallic coating on the articles, efficiently using the amount of plating solution to plate the articles, and configuring the plating process and equipment to electroplate large quantities of relatively small articles, while maintaining plating uniformity and consistency.
There are presently many techniques for electroplating small articles. One such technique is referred to in the relevant field as “barrel plating.” In barrel plating, small articles are placed into a barrel containing plating solution and an internal lose wire, typically referred to as a “dangler”, to act as an anode. The barrel is typically positioned on its side and continuously rotated while a plating current is formed through the plating solution. A drawback of the barrel plating technique is that the entire surface of each of the articles is plated. If the entire surface need not be plated, the barrel plating technique results in a substantial excess of plating, which can be very expensive over many runs and time.
In the case where the entire surface of an article need not be plated, only the particular surface of the article that requires plating is immersed in the plating solution while undergoing an electroplating process. Such partial plating technique requires many considerations, including consistency in the amount of surface plated from article-to-article, consistency in the uniformity of the plating formed on the partial surface of the articles, and control of the demarcation lines typically formed on the articles. These considerations are further explained with reference to the following example.
FIG. 1 illustrates a side view of a relatively small article 100 undergoing an electroplating process wherein only a portion of its entire surface is being plated. In this example, the article 100 may be a contact pin or socket. The article 100 is supported in a vertical orientation by a belt 102. In particular, the article 100 includes a wider head portion that rests on the belt 102, and a narrow body portion that extend below the belt 102 through an opening thereof. The lower portion of the article 100 is immersed in plating solution 108. An anode 106 is also immersed in the plating solution, and in this example, is situated directly below the article 100. The cathode makes electrical contact to the head portion of the article 100. If the article 100 is a socket, it may include a cavity 104 with an opening situated coaxially at the lower portion of the article 100.
As discussed above, the electroplating of relatively small articles requires many considerations. For instance, there is the consideration of the consistency in the amount of surface plated from article-to-article. In this example, it is desired that the lower portion of the article 100 be plated to a height of H±ΔH, where ΔH is an acceptable error for the height H. If the electroplating process is unable to achieve the height requirement on a consistent article-to-article basis, many articles will be defective which can drive up substantially the costs of plating the articles. Thus, in order to provide consistency in the amount of surface plated from article-to-article, the height of the plating fluid and the vertical position of the article 100 should be well controlled.
Also, as discussed above, another consideration in providing desirable electroplating of relatively small articles is the uniformity of the plating formed on the partial surface of the articles. In this example, if the article 100 is a socket, it would be desirable to uniformly plate the cavity 104 of the socket because that is the region where electrical contact to the socket would normally be made. Accordingly, positioning the anode 106 directly below the article 100 optimizes the plating of the cavity 104 since the electric field (shown as arrows with dashed lines) has generally a preferred path to the cavity 104.
However, if the article is a pin, it would be more desirable to focus the plating to the outer wall of the pin; the region where electrical contact to the pin would normally be made. In this case, the positioning of the anode 106 directly below the article 100 does not optimize the plating of its outer wall since the electric field does not have a generally preferred path to the outer wall. In such a case, it would be preferable to place the anode 106 on the side of the pin. However, the positioning of the anode 106 to the side of the pin, would not be desirable for plating a socket. Thus, to provide optimal plating of different articles (e.g., sockets, pins, etc.), it would be desirable for the position of the anode relative to the article to be adjustable.
Further, as discussed above, the other consideration in providing desirable electroplating of relatively small articles is the control of the demarcation line formed on the articles. Often, during the partial plating of an article 100, a discoloration 110, often referred to as a demarcation line, forms on the article 100 near the surface of the plating solution. It has been previously theorized that the demarcation line 110 was formed by the surface of the plating solution. Through various experiments, it has been discovered by the inventors that the demarcation line 110 actually forms on the article 110 a relatively short distance above the surface of the plating solution. The inventors theorized that the demarcation line 110 is formed by ejection of the plating fluid and subsequent impingement of the plating fluid vapors onto the article. Based on this theory, the inventors have devised a system and method of preventing or reducing the occurrence of the formation of the demarcation line 110 on articles.
Also, in an electroplating system, the articles are typically transported from a loading station through various processing stations, and then to an unloading station. When the articles are within the electroplating station, a cathode contact to the articles is needed to perform the electroplating process. Accordingly, there is a need for a transport system that not only transports the articles from the loading station to the unloading station by way of the various processing stations, but there is a further need for the transport system to provide a cathode contact to the articles.
These needs and other are met by the various exemplary embodiments of the invention described in detail below.

SUMMARY OF THE INVENTION

An aspect of the invention relates to a processing system, electroplating cell, and method of electroplating only a desired portion of respective articles. The processing system comprises a pre-processing station including one or more cells to perform one or more pre-electroplating processes on the articles, for example an activation and rinse processes; an electroplating station including one or more cells to plate the articles with one or more desired materials, for example gold; and a post-processing station including one or more cells to perform one or more post-electroplating processes, for example, a dragout rinse, hot deionized rinse, and hot air dryer processes. The processing system may further include a transport system to transport the articles from a loading station to an unloading station by way of the pre-processing, electroplating, and post-processing stations.
The electroplating cell comprises a container to support a plating fluid bath and an anode electrode situated within the container and adapted to contact the plating fluid bath. The methodology of electroplating only a desired portion of the respective articles entails several aspects such as the transport system being secured to a fixed member such that the vertical position (i.e., height) of the articles remains substantially constant as the articles are transported in and out of the electroplating cell. Also, the electroplating cell includes a vertical-adjustment mechanism to adjust the height of the container such that the desired portion of the respective articles is immersed in the plating fluid bath at a precise controlled depth. The electroplating cell further includes a flow control system to control the flow rate of plating fluid into the container such that the height of the surface of the plating fluid bath is maintained substantially constant. The container additionally includes one or more bleed holes through its walls, which assist in stabilizing the surface of the plating fluid bath.
Another aspect of the invention relates to a processing system, electroplating cell, and method of adjusting the effective position of a plurality of anode electrodes to desirably electroplate different type articles. The processing system may be similar to the one described above, including a loading station, pre-processing station, electroplating station, post-processing station, unloading station, and a transport system that transports the articles to the various stations. The electroplating cell comprises a container to support a plating fluid bath, a plurality of spaced-apart anode electrodes situated within the container and adapted to contact the plating fluid bath, and a power supply system adapted to energize a first subset of the anode electrodes with an anode voltage when plating one or more first type articles, and to energize a second and different subset of the anode electrodes with an anode voltage when plating one or more second and different type articles.
Another aspect of the invention relates to a processing system, electroplating cell, and method of reducing the discoloration (i.e., demarcation line) that often forms on articles undergoing a partial plating process. The processing system may be similar to the ones described above, including a loading station, pre-processing station, electroplating station, post-processing station, unloading station, and a transport system that transports the articles to the various stations. The electroplating cell comprises a container to support a plating fluid bath, an anode electrode situated within the container and adapted to contact the plating fluid bath, a support structure, which may be part of the transport system, to support the articles such that only a portion thereof is immersed in the plating fluid bath, and a gas flow system adapted to cause gas flow (e.g., air, nitrogen gas, argon gas, etc.) proximate the interface of the articles to the plating fluid bath. The gas flow near the articles prevents or reduces plating fluid vapors from impinging the articles, thereby reducing the discoloration that would otherwise form on the articles.
Another aspect of the invention relates to a processing system, transport subsystem, cathode contact subsystem and method of providing a cathode contact to the articles being transported within an electroplating cell. The processing system may be similar to the ones described above, including a loading station, pre-processing station, electroplating station, post-processing station, unloading station, and a transport system that transports the articles to the various stations. The transport system comprises an electrically conductive, movable support structure to support the articles; and the cathode contact system is adapted to provide a cathode potential to the one or more articles by way of the electrically conductive, movable support structure.
Another aspect of the invention relates to a processing system, electroplating cell, transport system, cathode contact subsystem and method of providing a cathode contact to the articles being transported within an electroplating cell. The processing system may be similar to the ones described above, including a loading station, pre-processing station, electroplating station, post-processing station, unloading station, and a transport system that transports the articles to the various stations. The electroplating cell comprises a container to support a plating fluid bath, and an anode electrode situated within the container and adapted to contact the plating fluid bath. The transport system is adapted to transport the articles to and from the various stations. The cathode contact system comprises an electrically-conductive moving structure adapted to make cathode contact to said articles and move substantially in synchronous with the articles.
Another aspect of the invention relates to a processing system, electroplating cell, transport system, cathode contact subsystem and method of providing a cathode contact to the articles being transported within an electroplating cell. The processing system may be similar to the ones described above, including a loading station, pre-processing station, electroplating station, post-processing station, unloading station, and a transport system that transports the articles to the various stations. The transport system comprises a plurality of carriers supported by a conveyor structure. Each of the carriers are adapted to support at least one article, but may be able to support a plurality of articles configured into various patterns, such as a single row, or a plurality of rows (i.e., an array). Further, the carriers are adapted to provide a cathode contact to the articles.
Other aspects, features, and techniques of the invention will be apparent to one skilled in the relevant art in view of the following detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a side view of a relatively small article undergoing an electroplating process where only a portion of its entire surface is being plated;

FIG. 2 illustrates a side view of an exemplary electroplating system in accordance with an embodiment of the invention;

FIG. 3 illustrates a side cross-sectional view of an exemplary electroplating cell in accordance with another embodiment of the invention;

FIG. 4 illustrates a block diagram of an exemplary system for controlling the plating fluid flow into the electroplating cell in accordance with another embodiment of the invention;

FIG. 5A illustrates a side view of an exemplary anode electrode configuration operated in a first manner in accordance with another embodiment of the invention;

FIG. 5B illustrates a side view of the exemplary anode electrode configuration operated in a second manner in accordance with another embodiment of the invention;

FIG. 6 illustrates a block diagram of an exemplary anode power system in accordance with another embodiment of the invention;

FIG. 7A illustrates a side view of an exemplary cathode contact system in accordance with another embodiment of the invention;

FIG. 7B illustrates a side view of another exemplary cathode contact system in accordance with another embodiment of the invention;

FIG. 8 illustrates a side view of an exemplary cathode contact preload system in accordance with another embodiment of the invention;

FIG. 9A illustrates a side view of the exemplary cathode contact preload system in contact with a pair of articles in accordance with another embodiment of the invention;

FIG. 9B illustrates a side view of another exemplary cathode contact preload system in contact with a pair of articles in accordance with another embodiment of the invention;

FIG. 10 illustrates a block diagram of an exemplary synchronization system to synchronize the speed of the article transport conveyor belt with the cathode contact conveyor belt in accordance with another embodiment of the invention;

FIG. 11 illustrates a side view of a portion of the exemplary article transport system in accordance with another embodiment of the invention;

FIG. 12A illustrates a side view of an exemplary carrier in accordance with another embodiment of the invention;

FIG. 12B illustrates a side view of another exemplary carrier in accordance with another embodiment of the invention; and

FIGS. 13A-D illustrate front, side, top and open views of another exemplary article transport system in accordance with another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

I. Overall Electroplating System

FIG. 2 illustrates a side view of an exemplary electroplating system 200 in accordance with an embodiment of the invention. The electroplating system 200 comprises a loading station 202, a transport system 204, a pre-processing station 206, an electroplating station 208, a post-processing station 210, an unloading station 212, and a control unit 214. The loading station 202 automatically loads articles onto the transport system 204. The transport system 204 transports the articles from the unloading station 202 through the various processing stations 206, 208, and 210, and finally to the unloading station 212.
In this example, the pre-processing station 206 performs an activation (e.g., cleaning) and rinsing of the articles. The electroplating station 208 performs one or more electroplating processes to form a desired plating of the articles. The post-processing station 210 performs a dragout rinse, a hot de-ionized (DI) water rinse, and a hot air drying of the articles. The unloading station 212 unloads the articles from the transport system 204 into an output bin 244. The control unit 214 controls the operations of the electroplating system 200.
More specifically, the loading station 202 comprises a feeder hopper 220, a bowl feeder 222, an inline feeder tract 224, and a drop tube escapement 226. The feeder hopper 220 receives articles to undergo the processes provided by the electroplating system 200. In this example, the feeder hopper 220 holds approximately ½ cubic feet of articles to be processed, and dispenses articles to the bowl feeder 222 based on a signal it receives therefrom. For example, the feed hopper 220 is disabled unless it receives a low-level condition signal from the bowl feeder 222.
The bowl feeder 222 orients the articles appropriately (e.g., in a substantial vertical fashion with the portion thereof to be plated situated at the lower end of the articles), and serially provides the oriented articles to the inline feeder tract 224. The inline feeder tract 224 transports the articles in a linear fashion to the drop tube escapement 226. The drop tube escapement 226, using a pressurized air nozzle, releases single articles downward to respective carriers periodically spaced on a conveyor belt as part of the transport system 204. The drop tube escapement 226 releases articles on the basis of a position encoder which tracks the position of the carriers as the conveyor belt moves and sends signals to the drop tube escapement 226 at the proper times to cause the articles to be inserted into respective carriers.
As is discussed in more detail below, the transport system 204 includes a horizontally-oriented endless conveyor belt rotationally supported by vertically-oriented 371 and 372. As discussed above, the belt is tooled with removable carriers situated into periodic spaced-apart openings through the belt. In this example, the transport system 204 may include two independent conveyor belts each with their own loading and unloading stations 202 and 212. The belts are, however, attached to a common drive motor 373 with closed loop speed control. Each conveyor belt has an independent tensioning and disengaging device to allow the running of one conveyor belt while the other is available for servicing. It shall be understood that the belt may be replaced with other types of conveyable structures, such as a chain or cable.
As discussed above, the pre-processing station 226, in this example, includes an activate cell 230 and a flood rinse cell 232. The process performed in the activate cell 230 serves to remove contaminants, such as light surface soils and metal oxides, from the articles prior to plating. In this example, the articles may be immersed in a bath of alkaline solution. Alternatively, or in addition to, the articles may undergo an anode and/or cathode cleaning process to generate oxygen (reverse) or hydrogen (direct) on the surface of the articles. In such a case, electrodes are also immersed in the solution to generate the current needed to perform the anode and/or cathode cleaning process. There are many other processes that may be employed in the activate cell 230 in order to prepare the articles for the electroplating process.
In the flood rinse cell 232, the articles undergo a process to remove and contain residual activation chemistry (also known as “dragout”) that may be present on the surface of the articles due to the prior activation process. This prevents the activation chemistry from contaminating the electroplating cell 234. In this example, the articles may be immersed in de-ionized water reservoir and/or sprayed also with de-ionized water. The de-ionized water may be recirculated to and from a rinse reservoir. In such a case, the de-ionized water may be replaced with clean water on a time basis. Accordingly, a programmed timer may be provided to operate a valve to open a fresh DI water supply line in order to replenish the rinse reservoir.
As discussed above, the electroplating station 208 may include one or more plating cells. In this example, two gold electroplating cells 234 and 236 are shown. It shall be understood that the electroplating need not be limited to gold. Other materials may be used to plate the articles. As discussed in more detail in Section II entitled the Electroplating Station, each of the electroplating cells 234 and 236 are configured to control the amount of partial plating of the articles; adjust the effective position of the anode to improve the plating of selected regions of the articles; reduce or eliminate the demarcation line that would otherwise form on the articles; provide a cathode connection to the articles that reduces contamination of the electroplating cell.
As discussed above, the post-processing station 210, in this example, includes a dragout rinse cell 238, a hot DI rinse cell 240, and a hot air dryer cell 242. In the dragout rinse cell 238, a process may be employed to remove residual chemistry remaining on the articles due to the prior electroplating process or processes. The process may be similar to the one performed in the flood rinse cell 232 previously described. Additionally, the process may include a gold recovery chamber to collect any gold metal removed from the articles during the rinse process. In particular, the gold recovery chamber may include ion exchange resin beads, which attract the gold metal as the recirculated water passes through the chamber. After a determined time period, the resin beads are removed from the chamber, and the gold metal is recovered from the resin material.
In the hot rinse cell 240, a process may be employed to remove any remaining residues from the articles due to the prior dragout rinse process. In this example, the articles are subjected to a rinse (e.g., bath and/or spray) using hot deionized water which may also be recirculated. The hot rinse cell 240 may be equipped with a heater to raise the temperature of the water to a desired level.
In the hot air dryer cell 242, a process may be employed to substantially dry the articles. In this example, the hot air dryer cell 242 includes a metal chamber that encloses that portion of the conveyor belt and articles thereon. A thermostatically controlled hot air blower may be located at the bottom of the metal chamber. The chamber may be designed to direct a flow of temperature-controlled hot air around the articles as the conveyor belt passes through the cell 242 to substantially remove the residual water from the articles due to the prior hot DI rinse process.
As discussed above, the electroplating system 200 also includes a loading station 212 that removes the processed articles from the conveyor belt and into an output bin 244. In this example, the output bin 244 is located below the drive wheel of the conveyor belt to collect the articles as they fall from the belt in the region where the belt is being inverted. The unloading station 212 may also include a compressed air nozzle or other mechanical devices configured to assist the removal of the articles from the conveyor belt into the output bin 244. The output bin 244 may be removable by an operator when it becomes full with processed articles.
The following section entitled Electroplating Station describes in more detail an exemplary electroplating cell.

II. Electroplating Station

As discussed above, the electroplating station 208 of the exemplary electroplating system 200 may include one or more electroplating cells, such as cells 234 and 236, to form a desired partial plating of articles. The following describes a detailed embodiment of an exemplary electroplating cell that may serve as one or more cells of the electroplating station 208 of the exemplary electroplating system 200. This exemplary electroplating cell is characterized in having a system and method of controlling the amount of partial plating of the articles; a system and method of selectively adjusting the effective position of the anode; a system and method of eliminating or reducing the demarcation line that typically forms on articles above the plating fluid surface; a system and method of providing a cathode connection to the articles; and a system and method of improving the cathode contact of the articles. An overview of the exemplary electroplating cell is discussed below.
A. Overview of Electroplating Cell
FIG. 3 illustrates a side cross-sectional view of an exemplary electroplating cell 300 in accordance with another embodiment of the invention. The electroplating cell 300 comprises a container 302 for supporting a plating fluid bath. The container 302 includes lower walls 304, upper walls 306, and a sparger 308, including one or more vertically-oriented thru-holes 308 a. The sparger 308 is connected horizontally to the lower walls 304. In this example, the upper walls 306 are situated closer to each other to form a narrower upper container portion, whereas the lower walls 304 are situated farther apart to form a wider lower container portion. Also in this example, the sparger 308 traverses the lower container portion to form an upper-lower container portion and a lower-lower container portion. The container 302 further includes one or more bleed ports 310 situated between the upper walls 306 and the lower walls 304. The container 302 further includes a vertically-oriented inlet pipe 312 partially situated within the lower-lower container portion, and supported by a transverse member 314 connected horizontally to the lower walls 304.
The electroplating cell 300 further comprises an anode electrode configuration 316 including, in this example, a plurality of anode electrodes 316 a, 316 b, and 316 c situated in the upper container portion between upper walls 306. The anode electrodes 316 a, 316 b, and 316 c are respectively supported by respective members 318 a, 318 b, and 318 c. The support members 318 a, 318 b, and 318 c, in turn, enclose wiring that electrically connect the respective anode 316 a, 316 b, and 316 c to the positive terminal of a power supply. In this example, the anode electrodes 316 a and 316 c are situated near the top of the respective upper walls 306, and the anode electrode 316 b is situated approximately in the middle between the upper walls 306 and lower than the other anode electrodes 316 a and 316 c.
The electroplating cell 300 further includes one or more vertical-adjustment mechanisms 320 for adjusting the height of the plating fluid container 302. In this example, each vertical-adjustment mechanism 320 includes a threaded container member 322 connected to the exterior of the lower walls 304 of the plating fluid container 302. Each vertical-adjustment mechanism 320 further includes a bolt 324 threaded with the container member 322, and having a bottom lying on a substantially fixed member. Additionally, each vertical-adjustment mechanism 320 includes a lock nut 326 for preventing undesired rotation of the bolt 324. The lock nut 326 is threaded with the bolt 324, and lies on top of the container member 322.
The electroplating cell 300 further includes an gas-flow system 328 for directing gas flow toward (positive pressure) or away from (negative pressure) the articles while they undergo an electroplating process. Examples of gases that can be used include air, nitrogen gas, argon gas, etc. The gas-flow system 328 includes a pipe 332 for routing gas flow towards or away from a nozzle 330 that includes an opening configured to direct gas flow towards or away from the articles. As is discussed in more detail later, the continued direction of gas flow towards or away from the articles while they undergo an electroplating process prevents and/or eliminates a discoloration of the articles that typically forms above the plating fluid bath surface.
Also illustrated in FIG. 3 is portion of an exemplary article transport system 350, which may be an exemplary detailed version of the transport system 204 of the electroplating system 200. The transport system 350 comprises a frame 352 for supporting and guiding the movement of a conveyor belt 370 supporting a plurality of insert-carriers 375 which, in turn, carry respective articles 500. In this example, the frame 352 comprises upper walls 354, lower walls 356, and upper cross member 358. The conveyor belt 370 is supported and guided, in particular, by the lower walls 356 of the frame 352. The frame 352 supports other elements of the electroplating system 200 including the cathode contact system 360 and the cathode contact preload system 365, which are discussed in further detail below.
B. Controlling the Amount of Partial Plating of the Articles
The electroplating cell 300 is configured to provide a desired control of the amount of partial plating of the articles. It achieves this desired control by providing a substantially stable frame 352 that supports articles at substantially a fixed height, a vertically-adjustable plating fluid container 302, a control system for controlling the flow of plating fluid into the plating fluid container, and one or more bleed ports 310 embedded in the plating fluid container to substantially stabilize the surface of the plating fluid bath.
As discussed above, the frame 352 supports and guides the movement of the conveyor belt 370 as it moves through the various processing stations of the electroplating system 200. A plurality of insert carriers 375 are securely inserted into corresponding spaced-apart openings in the conveyor belt 370. Each of the insert carriers 375 support an article 500 in a substantially vertical orientation. A portion of the article 500 below the insert carrier 375 is immersed in the plating fluid bath supported by the container 302. It is this portion of the article 500 that is being plated. In order to achieve the desired control of the amount of partial plating of the articles, the vertical position of the articles should be controlled as well as the height of the surface of the plating fluid bath.
With regard to the control of the vertical position of the articles, the frame 352 that supports the conveyor belt 370 including the insert carriers 375 that carry the articles, is connected to a substantially fixed member of the electroplating system 200. In addition, the frame 352 is made of relatively high strength material, such as stainless steel, such that the frame 352 exhibits substantially no movement in the vertical direction during the operation of the transport system 350. These characteristics of the frame 352 ensure that the articles exhibit substantially no movement in the vertical direction while being transported through the electroplating cell 300.
With regard to the control of the height of the surface of the plating fluid bath, the electroplating cell 300 includes three elements that assist in this control. First, as previously discussed, the height of the plating fluid container 302 may be adjusted by the vertical-adjustment mechanism 320. This allows the proper setting of the height of the surface of the plating fluid bath supported by the container 302 by adjusting the bolt 324 and subsequently fixing the desired position by tightening the lock nut 326. Second, the bleed ports 310 allows plating fluid from the bath to bleed into a drain. The bleed ports 310 improve the stability of the height of the surface of the plating fluid bath. Plating fluid from the surface of the bath also continuously drains by flowing down the inclined surface of the upper walls 306 of the container 302. Third, the flow of plating fluid into the bath by way of the inlet pipe 312 is controlled with the use of a feedback control system, an example of which is discussed below.
FIG. 4 illustrates a block diagram of an exemplary system 400 for controlling the plating fluid flow into the plating fluid container 302 in accordance with another embodiment of the invention. The system 400 comprises a reservoir 402, a pump 406, a flow meter (FM) 408, a filter 410, a controller 412, and a motor 414. The reservoir 402 holds plating fluid for use in plating articles. The pump 406 causes plating fluid to flow from the reservoir 402 to the plating fluid container 302 by way of the flow meter 408, filter 410, and intake pipe 312. The flow meter 408 generates a signal indicative of the flow rate of the plating fluid into the container 302. The filter 410 removes contaminants from the plating fluid. The motor 414 drives the pump 406. The controller 412 senses the flow rate of the plating fluid by receiving the signal from the flow meter 408, and controls the motor 414 so that the desired flow rate for the plating fluid flow is established and maintained. The controlled plating fluid flow into the container 302 and the plating fluid that drains out of the container 302 from the top of the electroplating cell 300 and from the bleed ports 310 substantially stabilizes the height of the surface of the plating fluid bath.
C. Selectively Adjusting the Effective Position of the Anode As discussed in the Background section, optimal electroplating of different articles may require different anode configurations. For instance, certain articles such as pins, where the plating of their respective side walls is most desirable, the anode electrodes should be positioned such that the electric field lines have a generally direct path to the surface that requires plating, i.e., the side walls of the pins. Other articles, such as sockets, where the plating of their respective cavities is most desirable, the anode electrodes should be positioned such that the electric field lines have a generally direct path to the surface that requires plating, i.e., the cavities of the sockets. As discussed in detail below, the exemplary anode electrode configuration 316 of the electroplating system 200 allows for the effective position of the anodes to be adjusted in order to provide the desired plating of the articles.
FIG. 5A illustrates a side view of an exemplary anode electrode configuration 316 operated in a first manner in accordance with an embodiment of the invention. In this example, the article 500 is a pin, which is being held in a substantially vertical position by the insert carrier 375 which, in turn, is supported by the conveyor belt 370. As discussed above, it is desirable to focus the plating at the lower side wall portion of the pin 500. In such a case, it is preferable that an anode voltage is applied to only anode electrodes 316 a and 316 c, and that no anode voltage is applied to anode electrode 316 b. This is because the electric field lines from the anode electrodes 316 a and 316 c to the lower side wall portion of the pin 500 follow a generally direct path. Whereas the would-be electric field lines from the anode electrode 316 b to the lower side wall portion of the pin 500 do not follow a preferred path.
FIG. 5B illustrates a side view of an exemplary anode electrode configuration 316 operated in a second manner in accordance with an embodiment of the invention. In this example, the article 500 is a socket including a downward-oriented cavity 502 a positioned at the lower end of the article 500. Similarly, the socket is held in a substantially vertical position by the insert carrier 375 which, in turn, is supported by the conveyor belt 370. In this case, it is desirable to focus the plating at the internal side wall of the cavity 502 a of the pin 500. In such a case, it is preferable that an anode voltage is applied to only anode electrode 316 b, and that no anode voltage is applied to anode electrodes 316 a and 316 c. This is because the electric field lines from the anode electrode 316 b to the internal side wall portion of the cavity 502 a of the pin 500 follow a generally direct path. Whereas the would-be electric field lines from the anode electrodes 316 a and 316 b to the internal side wall of the cavity 502 a of the pin 500 do not follow a preferred path.
FIG. 6 illustrates a block diagram of an exemplary anode power system 600 in accordance with another embodiment of the invention. The anode power system 600 comprises a power supply 602 including a positive terminal and a grounded negative terminal. The positive terminal of the power supply 602 is electrically coupled to the respective inputs of controllable switching elements 602 a, 602 b, and 602 c. The switching elements 602 a, 602 b, and 602 c include respective outputs electrically coupled to the corresponding anode electrodes 316 a, 316 b, and 316 c of the anode electrode configuration 316. The anode power system 600 further comprises a controller 604 having outputs respectively coupled to control inputs of the respective switching elements 602 a, 602 b, and 602 c.
The controller 604 controls whether the switching elements 602 a, 602 b, and 602 c electrically connect the respective anode electrodes 316 a, 316 b, and 316 c to the positive terminal of the power supply 602. Based on inputs from an operator, the controller 604 can determine which of the anode electrodes 316 a, 316 b, and 316 c receives the anode voltage, and which do not. Although, in this example, three anode electrodes 316 a, 316 b, and 316 c are shown, it shall be understood that the anode electrode configuration 316 may include any number of electrodes. Although not shown, the anode power system 600 may include one or more voltage regulators to independently regulate (and/or in common) the anode voltages at the respective anode electrodes 316 a, 316 b, and 316 c. Alternatively, the anode power system 600 may have independent power supplies for the respective anode electrodes 316 a, 316 b, and 316 c.
D. Eliminating or Reducing the Demarcation Line on Articles
As discussed in the Background section, during the partial plating of an article, a ring-shaped discoloration, also referred to as a demarcation line, is often formed around the article near the surface of the plating fluid bath. It has been previously theorized by others that the demarcation line was formed at the surface of the plating fluid bath. Through various experiments, the inventors have discovered that the demarcation line actually forms on the article a relatively short distance above the surface of the plating fluid bath. The inventors theorized that the demarcation line is formed by ejection of the plating fluid and subsequent impingement of the vapors onto the article. Based on this theory, the inventors have devised a method of preventing or reducing the occurrence of the formation of the demarcation line on articles.
With reference again to FIG. 3, the electroplating cell 300 includes an gas-flow system 328 for directing gas flow toward or away from the articles while they undergo the electroplating process. As discussed above, the gas-flow system 328 includes a pipe 332 for routing gas flow towards or away from a nozzle 330 that includes an opening configured to direct gas towards or pull gas from the articles. Examples of gases that can be used include air, nitrogen gas, argon gas, etc. The continued gas flow towards or away from the articles while they undergo an electroplating process prevents and/or reduces the impingement of the vapors on the articles. Thus, with the use of the gas-flow system 328, the discoloration of the articles may be prevented or substantially reduced.
E. Providing a Cathode Connection to the Articles
FIG. 7A illustrates a side view of an exemplary cathode contact system 360 in accordance with another embodiment of the invention. The cathode contact system 360 is configured to provide a cathode contact to the articles while preventing contamination of the electroplating cell 300. The cathode contact system 360 comprises a point of electrical cathode contact 361, a resilient device 326 including a brush 363 situated at its lower end, an exterior cathode contact wheel 364, an interior cathode contact wheel 367, a drive shaft 366, and a pair of bearings 365 for the wheels 364 and 367.
The point of contact 361, which in this example is a bolt threaded into a housing and secured by a lock nut, is electrically coupled to the resilient device 362 including the brush 363. The resilient device 362 is resilient generally in the vertical direction and absorbs upward vertical energy produced by the rotating exterior cathode contact wheel 364. The brush 363 makes electrical contact to the perimeter of the exterior cathode contact wheel 364. The drive shaft 366 is rotationally coupled and makes electrical contact to the exterior cathode contact wheel 364 and the interior cathode contact wheel 367. The bearings 365 secure the wheels 364 and 367 to fixed members, such as the frame 352 of the transportation system 350, while allowing the wheels to rotate. The interior cathode contact wheel 367 is rotationally and electrically coupled to the conveyor belt 370. The conveyor belt 370, in turn, is electrically coupled to the articles 500 by way of their respective insert carriers 375.
Thus, with the exemplary cathode contact system 360 of the invention, a cathode voltage potential is applied to the articles by way of the point of contact 361, resilient device 362 including its brush 363, the exterior cathode contact wheel 364, the drive shaft 366, the interior cathode contact wheel 367, the conveyor belt 370, and the insert carriers 375. An advantage of the cathode contact system 360 is that the brush 363 makes electrical contact to the exterior cathode contact wheel 364 at a location outside of the electroplating cell 300. In this manner, particles of the brush 363 that flake off as it makes contact with the moving exterior cathode contact wheel 364 does not contaminate the plating fluid bath. Thus, a cathode contact may be provided to moving articles in a contaminant free manner because a fixed member (e.g., brush 363) makes contact with a moving member (e.g., wheel 364) outside of the electroplating cell 300.
FIG. 7B illustrates a side view of another exemplary cathode contact system 380 in accordance with another embodiment of the invention. The cathode contact system 380 comprises an electrical conduit 382 and a brush 384. The electrical conduit 382 may be routed from outside of the electroplating cell where it receives the cathode potential, through an opening within a wall of the transport system frame 352, and downwards towards the conveyor belt 370. The brush 384, electrically connected to the lower end of the electrical conduit 382, makes electrical contact to the conveyor belt 370. Thus, a cathode potential is applied to the article 500 by way of the electrical conduit 382, brush 384, conveyor belt 370, and insert carrier 375. The contact of the brush 384 to the conveyor belt 370 may be configured such that there is no or minimal contamination of the plating fluid by particles emanating from the brush 384 as a result of its frictional contact with the moving conveyor belt 370.
F. Improving the Cathode Contact to the Articles
FIG. 8 illustrates a side view of an exemplary cathode contact preload system 390 in accordance with another embodiment of the invention. The cathode contact preload system 390 applies a continuous downward force on the articles 500 to ensure that they make good electrical and physical contact with their corresponding insert carriers 375 while the articles are being plated. In particular, the cathode contact preload system 390 comprises an endless belt 392 rotationally supported by a pair of idle wheels 394 (only one shown). The cathode contact preload system 390 further comprises a drive belt 396 rotationally coupling one of the idle wheels 394 to a drive wheel 377 rotationally coupled to the conveyor belt 370. In this manner, the endless belt 392 moves at substantially the same speed as the conveyor belt 370 that transports the articles 500 through the various processing stations.
FIG. 9A illustrates a side view of the exemplary endless belt 392 of the cathode contact preload mechanism 390 in contact with a pair of articles 500 in accordance with another embodiment of the invention. The endless belt 392, being made of a resilient material (e.g., rubber), makes contact to the top regions the articles 500. The resilient nature of the belt 392 results in the belt 392 exerting a substantially downward force F against the tops of the articles 500. This downward force F forces the articles against the insert carriers 375, thereby providing a positive electrical and physical contact of the articles 500 to the insert carriers 375 as the articles 500 are transported through the various processing stations of the electroplating system 200. As discussed above, the conveyor belt 370 as well as the insert carriers 375 are electrically coupled to the cathode terminal of a power supply. Thus, the downward force F exerted by the belt 392 against the articles 500 allows a consistently good cathode contact to be made to the articles while they undergo the electroplating process.
As an alternative embodiment, the endless belt 392 may be made of an electrically conductive material (e.g., a conductive rubber or a metal band). In such a case, the cathode contact to the articles 500 may be made by way of the endless belt 392. Also, in such a case, the conveyor belt 370 and the insert carrier 375 need not be made of an electrically conductive material. Again, this is because the endless belt 392 provides the cathode contact to the articles 500. The cathode contact to the electrically-conductive, conveyor belt 392 may be made by a sliding contact member that slides against the moving belt 392 or a rotating contact member that rotates against the moving belt 392.
FIG. 9B illustrates a side view of another exemplary endless belt 398 in accordance with another embodiment of the invention. In this example, the endless belt 398 is made of an electrically conductive material (e.g., a metal). In addition, the endless belt 398 includes a plurality of spaced-apart, spring-loaded fingers 399 configured to register with the top end of the articles 500. Accordingly, the cathode contact to the articles 500 may be made by way of the endless belt 398 and the respective spring-loaded fingers 399.
FIG. 10 illustrates a block diagram of an exemplary synchronization system 1000 to synchronize the speed of the article transport conveyor belt 370 with the cathode contact conveyor belt 392 (or belt 398) in accordance with another embodiment of the invention. The synchronization system 1000 comprises the drive motor 373 for the article transport conveyor belt 370, a controller 1002, and a variable-speed or DC servo drive motor 1004 for the cathode contact conveyor belt 392. The drive motor 373 for the article transport conveyor belt 370 may include the motor portion 373 a as well as a revolution per minute (RPM) encoder 373 b which generates a signal indicative of the speed of the motor portion 373 a. It shall be understood that the RPM encoder 373 b may be integrated with the motor portion 373 a, or may be separate there from. It shall be understood that the belt 370 may be replaced with other types of conveyable structures, such as a chain or cable.
The controller 1002 receives the signal generated by the RPM encoder 373 b. Based on this signal, the controller 1002 generates a speed control signal for the cathode contact motor 1004. Since the cathode contact motor 1004 and cathode contact conveyor belt 392 may be configured to have different speed control characteristics, the controller 1002 performs the appropriate calculations to generate a speed control signal for the cathode contact motor 1004 such that the movement of the cathode contact conveyor belt 392 is substantially in synchronous with the movement of the article transport conveyor belt 370. This ensures that the preload cathode contact to the articles by the article transport conveyor belt 370 is substantially fixed as the articles are transported through the various cells of the electroplating system 200.

III. Transport System

A. FIRST EMBODIMENT

With reference again to FIGS. 1, 8 and 9, the transportation system 204 comprises an endless, electrically-conductive conveyor belt 370 that is rotationally supported by a drive wheel 371 and an idle wheel 372. The drive wheel 371 is rotationally coupled to a drive motor 373 for moving the conveyor belt 370. The transportation system 204 may further include a tension wheel 374 to keep the conveyor belt 370 desirably taut during transportation of the articles 500. The endless belt 370 further comprises a plurality of spaced-apart thru-holes 370 a configured to respectively receive insert carriers 375 that hold articles. The insert carriers 375 snap into the respective openings 370 a such that insert carriers 375 are secured to the conveyor belt 370.
FIG. 11 illustrates a side view of a portion of the exemplary article transport system 204 in accordance with another embodiment of the invention. As shown, the endless belt 370 includes an overlap region 372 where two portions of the belt overlap and are attached together to make the belt endless. In the overlap region 372, the thru-holes 370 a of the overlapping portions of the belt 370 register with each other, i.e., they are substantially coaxial. The overlapping portions of the belt 370 may be attached to each other by epoxy, mechanical or others means. Also, in the overlap region 372, the insert carriers 375 are inserted through respective registered pairs of openings 370 a.
The conveyor belt 370 is made out of relatively high tensile strength material so as to prevent unwanted flexing in the region where the articles 500 are carried. This further ensures that the vertical position of the articles 500 is substantially stable to control the amount of partial plating of the articles. Furthermore, the position of the conveyor belt 370 is such that it does not contact the plating solution. This reduces the amount of maintenance (e.g., cleaning and/or replacement) required on the conveyor belt 370. It shall be understood that the belt 370 may be replaced with other types of conveyable structures, such as a chain or cable.
FIG. 12A illustrates a side view of an exemplary carrier 375 a supporting an article 500 a in accordance with another embodiment of the invention. An advantage of the article transport system 204 of the electroplating system 200 is that it is relatively easy to configure the system to handle different types of articles. In particular, insert carriers may be designed to hold different types of articles while still being able to be properly attached to the conveyor belt 370. More specifically, the interior configurations of various types of insert carriers may be designed to properly support different articles. While, the outside configuration of such various types of insert carriers may be kept substantially the same so that they can be properly attached to the conveyor belt 370.
In this example, the interior configuration of the insert carrier 375 a is designed to support an elongated cylindrical-shaped article 500 a (e.g., a pin) that includes a ridged portion that makes contact with the interior of the insert carrier 375 a. The upper interior walls of the insert carrier 375 a is angled inward to guide the article 500 a while it is being fully inserted into the insert carrier 375 a. The external configuration of the insert carrier 375 a is designed to friction fit into the thru-holes 370 a of the conveyor belt 370. As discussed below, if a different type article is to be plated, the interior configuration of the insert carrier may be designed differently to properly accommodate the article, while the exterior configuration be kept the same so that it properly interfaces with the conveyor belt 370.
FIG. 12B illustrates a side view of another exemplary carrier 375 b supporting another article 500 b in accordance with another embodiment of the invention. In this example, the interior configuration of the insert carrier 375 b is designed to support an elongated cylindrical-shaped article 500 b that includes a cylindrical flange structure that makes contact with the interior of the insert carrier 375 b. Similar to insert carrier 375 a, the upper interior walls of the insert carrier 375 b is angled inward to guide the article 500 b while it is being fully inserted into the insert carrier 375 b. The external configuration of the insert carrier 375 b is substantially the same as that of insert carrier 375 a so that it can be friction fit into the thru-holes 370 a of the conveyor belt 370.
Thus, the plating of different articles is facilitated with the customizable insert carriers 375. The conveyor belt 370 may be populated with the first-type insert carriers 375 a to support first-type articles 500 a while they undergo the various processes performed by the electroplating system 200. Once the processes are completed on the first-type articles 500 a, the first-type insert carriers 375 a are removed from the conveyor belt 370, and the conveyor belt 370 is then populated with the second-type insert carriers 375 b to support second-type articles 500 b while they undergo the various processes performed by the electroplating system 200.

B. SECOND EMBODIMENT

FIGS. 13A-D illustrate front, side, top and open views of another exemplary article transport system 1300 in accordance with another embodiment of the invention. The article transport system 1300 comprises a conveyor belt 1302 and a multi-article carrier 1304 supported by the conveyor belt 1302. The multi-article carrier 1304 comprises a base 1306 and a cover 1308 connected to the base 1306 via a hinge 1310. The bottom of the base 1306 includes a plurality of openings 1312 to receive there thru the articles 500. The openings 1312 register with corresponding openings of the conveyor belt 1302 such that the articles 500 extend there thru below the conveyor belt 1302 and into the electroplating cell 1350. The openings 1312 may be configured into a single row, into an array consisting of a plurality of rows, or into any other pattern.
The cover 1308 of the multi-article carrier 1304 comprises a cathode contact port 1314 to receive the cathode potential. The cover 1308 further includes an internal electrical conduit 1316 which is electrically coupled to the cathode contact port 1314 and routes the cathode potential towards the articles 500. The cover 1308 further comprises a plurality of spring-loaded cathode fingers 1318 that make pressured electrical contact to the respective articles 500. The spring-loaded cathode fingers 1318 are electrically connected to the electrical conduit 1316. Thus, the articles 500 receive the cathode potential by way of the cathode contact port 1314, internal electrical conduit 1316, and respective spring-loaded cathode fingers 1318.
In operation, at a loading station, an empty carrier 1304 has its cover 1308 initially in an open position as shown in FIG. 13D. The articles 500 are then inserted into the holes 1312 of base 1306 of the empty carrier 1304 such that articles 500 extend below the conveyor belt 1302. Once the articles 500 are properly inserted into the holes 1312 and are supported by the carrier 1304 and conveyor belt 1302 in a substantially vertical orientation, the cover 1308 is then closed as shown in FIG. 13A. As discussed above, in the closed position, the spring-loaded cathode fingers 1318 make pressured electrical contact to the respective articles 500. It shall be understood that the conveyor belt 1302 may be some other type of movable supporting structure, such as a chain or cable. In addition, the conveyor belt 1302 can be an electrical conductor (e.g., a metal or conductive rubber) and/or a non-electrical conductor.
While the invention has been described in connection with various embodiments, it will be understood that the invention is capable of further modifications. This application is intended to cover any variations, uses or adaptation of the invention following, in general, the principles of the invention, and including such departures from the present disclosure as come within the known and customary practice within the art to which the invention pertains.

Claims

1. An electroplating system, comprising:

an electroplating cell including a container to support a plating fluid bath and an anode electrode situated within said container;

a transport system adapted to transport articles through said plating fluid bath, wherein said transport system comprises an electrically conductive, movable support structure to support said articles; and

a cathode contact system adapted to provide a cathode potential to said articles by way of said electrically conductive, movable support structure.

2. The electroplating system of claim 1, wherein said cathode contact system comprises a contact member adapted to slide against said electrically-conductive, movable support structure.

3. The electroplating system of claim 1, wherein said cathode contact system comprises a contact member that is rotationally coupled to said electrically-conductive, movable support structure.

4. The electroplating system of claim 3, wherein said contact member comprises a first electrically-conductive wheel rotationally coupled to said electrically-conductive, movable support structure; and wherein said cathode contact system further comprises:

a second electrically-conductive wheel rotationally coupled to said first electrically-conductive wheel; and

a brush in electrical contact with said second electrically-conductive wheel, wherein said brush is electrically coupled to a source of said cathode potential.

5. The electroplating system of claim 1, wherein said electrically-conductive, movable support structure comprises a belt, a chain, or a cable.

6. The electroplating system of claim 1, further comprising a movable preload mechanism to apply a continuous force to the articles against the electrically conductive, movable support structure to ensure a positive cathode contact to said articles.

7. The electroplating system of claim 1, further comprising a plurality of insert-carriers supported on said electrically-conductive, movable support structure, wherein said insert-carriers are adapted to respectively support said articles.

8. The electroplating system of claim 1, further comprising:

a loading station adapted to load said articles onto said electrically-conductive, movable support structure;

one or more pre-processing cells configured to perform one or more pre-processes on said articles prior to the articles undergoing one or more electroplating processes;

one or more post-processing cells configured to perform one or more post-processes on said articles after the articles have undergone the one or more electroplating processes; and

an unloading station adapted to unload said articles from said electrically-conductive, movable support structure.

9. A method of electroplating articles, comprising:

transporting said one or more articles into an electroplating cell by an electrically conductive, movable support structure, wherein said articles make contact with a plating fluid bath formed within said electroplating cell;

providing a cathode potential to said articles by way of said electrically conductive, movable support structure; and

energizing an anode electrode situated within said plating fluid bath to form a plating current through said articles.