Electroplating apparatus and method

Abstract

There is described an apparatus for electroplating preselected portions of individual articles. The apparatus comprises a track member adapted for having the articles travel therealong, a supply means for supplying the articles to the track member, a vibratory means engaged to the track member for effecting movement of said articles along the track member, a container adapted for containing a predetermined quantity of electolyte solution therein and positioned substantially below and related to the track member, means for controlling the elevation of the electrolyte solution within the container in order that the solution contacts the preselected areas on the articles as these articles travel along the track member, means for controlling the rate of travel of the articles, a first electrode means associated with the articles, and a second electrode means of opposite polarity than the first electrode means and associated with the electrolyte solution. A method for electroplating preselected areas on individual articles is also disclosed.

Description

BACKGROUND OF THE INVENTION

The invention relates to electrical deposition or plating of a metal or alloy of metals on preselected portions of individual articles in order to provide desired characteristics in these areas. More particularly, the invention relates to a method and means for achieving electrical plating of preselected portions of individual articles with precious metals thereby making it imperative that the plating be substantially confined to these portions. Even more particularly, the invention relates to a means and method for accomplishing the afore-described localized plating on large quantities of articles in relatively short periods of time.

In the manufacture of various individual articles, notably articles useful in the electronic industry, it is often desirable to plate these articles with a precious or similar type metal or alloy of metals, the purpose being to provide these articles with improved characteristics such as electroconductivity. One particular method for achieving this plating on relatively large quantities of articles is known as "barrel" plating. This process consists of placing articles in a submergible barrel-type device which is then placed in a bath of electrolyte solution. The barrel is then rotated at a predetermined speed, electrical current is applied to achieve the plating, and each article receives a substantially uniform deposition of material thereon. While "barrel" plating does achieve electrical deposition on large quantities of articles, it can be readily understood that this method does not provide a means for providing such deposition on only preselected areas of said articles. Accordingly, utilization of "barrel" plating when only preselected portions of the articles are to be plated results not only in an unnecessary waste of materials, but also proves costly by manufacturing standards.

It is believed, therefore, that an apparatus and method which could selectively electroplate preselected portions of individual articles and do so on relatively large quantities of articles in relatively short periods of time would constitute an advancement in the art.

OBJECTS AND SUMMARY OF THE INVENTION

It is therefore a primary object of this invention to provide an apparatus for electroplating preselected portions of relatively large quantities of individual articles during relatively short periods of time.

It is another object of this invention to provide a method which incorporates the above-described apparatus.

A still further object of this invention is to provide an electroplating apparatus and method which are relatively inexpensive to utilize and comparatively simple to operate.

In accordance with one aspect of this invention there is provided an apparatus for electroplating preselected portion of individual articles. The apparatus comprises a track member adapted for having these articles travel therealong, a supply means for supplying these articles to the track member, a vibratory means engaged to the track member for effecting movement of the articles along the track member, a container adapted for containing a predetermined quantity of electrolyte solution therein, means for controlling the elevation of the electrolyte solution within the container in order that this solution contacts the preselected portions of the articles as the articles travel along the track member, means for controlling the rate of travel of the articles, a first electrode means associated with the articles, and a second electrode means of opposite polarity than said first electrode means and associated with the electrolyte solution.

In accordance with another aspect of this invention, there is provided a method for electroplating preselected portions of individual articles, this method comprising the steps of: (a) supplying the articles to a track member, (b) effecting a vibratory movement to the articles while the electrolyte solution contacts these preselected portions of the articles, and (c) applying an electrical potential to the articles and an electrical potential of opposite polarity to the electrolyte solution thereby providing deposition of a metal on the preselected portions of the articles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of the apparatus in accordance with one embodiment of the present invention.

FIG. 2 is an isometric view of the container of the present invention.

FIG. 3 is a side elevational view as taken along the lines 3--3 in FIG. 1.

FIG. 4 is an isometric view illustrating the means for controlling the rate of travel of the articles which are to be electroplated by the present invention.

FIG. 5 illustrates an example of one article which may be plated by the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For a better understanding of the present invention together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims in connection with the above-described drawings.

With particular reference to FIG. 1, there is illustrated a front elevational view of the subject invention, electroplating apparatus 10 which is shown to comprise a track member 11, supply means 13, vibratory means 15, a container 17 adapted for having a predetermined quantity of electrolyte solution therein, means for controlling the rate of travel of articles as these articles travel along the track member 11, this means illustrated as a rotating disc member 19, a first electrode means 21 associated with the articles, and a second electrode means 23 associated with the electrolyte solution. Second electrode means 23 is illustrated in FIG. 2 as being affixed to the container member 17. As also can be seen in FIG. 2, apparatus 10 comprises a means for controlling the elevation of the electrolyte solution within container 17, this means illustrated as an adjustable drain member 25 positioned within container 17.

In the preferred embodiments, supply means 13 comprises a vibratory feed mechanism which is capable of supplying individual articles 27 to track member 11. Such a feed mechanism, often referred to as a rotary or bowl vibratory feeder of a rotating vibratory machine, is well known in the art and commercially available from several sources. As articles 27 are supplied to track member 11, portions of these articles protrude from beneath the track member as shown in FIG. 1. As will be explained, these portions comprise the preselected areas on the articles which are to receive electrical deposition thereon. As articles 27 travel along track member 11, these preselected areas travel through a portion of container 17 which is positioned substantially below track member 11. During their period of travel through container 17, the preselected areas of articles 27 are each contacted by the electrolyte solution within the container. Electrical current is then supplied to first electrode means 21 and second electrode means 23 to thereby achieve the deposition desired. After leaving container 17 and having this electrical deposition thereon, articles 27 are then removed from track member 11 by rotating disc member 19. The operation of this disc member will be explained with description of FIG. 4.

To provide movement of articles 27 along track member 11, vibratory means 15 is provided. Means 15 in the preferred embodiment comprises a plurality of individual vibratory members 29 spacedly positioned along and engaged to track member 11 to effect movement of the articles therealong. Each vibratory member comprises a compact self-contained magnetic motor which generates straight line vibratory motion when electrical current is passed through its internal windings. These are referred to as VibroBlock generators and may be purchased from the Arthur G. Russell Company, Incorporated, from Bristol, Conn. At least six such motors are preferably used, three on each side of track member 11. By alternating the cycles of vibration for each motor, track 11 is vibrated in such a manner that articles 27 will travel therealong in the direction indicated. Each of the vibratory members 29 are positioned on a corresponding bracket member 43 which in turn is fixedly positioned on support frame 45. Frame 45, as is reservoir 31, is positioned on surface 39. Each vibratory member 29 in turn is connected to track member 11 via a flange 47, this embodiment best shown in FIG. 3.

Positioned below container 17 is a collection reservoir 31 which serves to collect the overflow of electrolyte solution from container 17, thereafter recirculating it back to the container. To achieve this recirculating, a recirculation means 33 is provided and shown to comprise a filter 35 and a pump member 37. Reservoir 31 is positioned within apparatus 10 by simply placing the reservoir on a surface 39 of the apparatus. Container 17, on the other hand, is positioned above and partially within reservoir 31 by support members 41 (also shown in FIG. 2).

As illustrated in FIG. 3A, track member 11 is shown to comprise a pair of opposingly aligned top portions 49 and 49' and a pair of opposing aligned bottom portions 51 and 51'. Top portions 49 and 49' are secured to flanges 47 while bottom portions 51 and 51' are secured to top portions 49 and 49' respectively. A preferred material for top portions 49 and 49' is polyvinyl chloride, while a material preferred for bottom portions 51 and 51' is brass or any of the similar good electrically conductive materials. First electrode means 21 is also illustrated in FIG. 3A and is shown to comprise the cathode member 53 of the present invention. Cathode member 53 which is electrically connected to an external circuit (not shown) thereby provides negative potential to each article 27 as the article travels through a substantially centrally located slot 55 within the track member 11. Also shown in FIG. 3A and better illustrated in FIG. 2 is the second electrode means 23 which comprises the anode member of the present invention. Anode member 57, submerged within the electrolyte solution and spacedly positioned adjacent the preselected areas of articles 27 to receive deposition, comprises a platinum wire which in turn applies positive potential to the electrolyte solution to achieve a deposition during the plating step of the operation. This anode is, in general, the nonconsumable type, that is the anode does not furnish the metal to be coated. Anode member 57 is retained within container 17 in the manner indicated in FIG. 2 and is electrically connected to an external circuit (not shown) via connecting wires 59. As can be appreciated, second electrode means 23 can comprise more than a single wire. At least two wires could be utilized, each being positioned on one side of the article to be plated as the article travels through container 17.

Relatively low current densities are utilized with the present invention. For example, a desired rate for plating is approximately 140 articles per minute. With the overall average amperage at approximately 3.9 amps, a current density of about 35 amps/sq. ft. is utilized to obtain an average 40 millionths of an inch thickness of deposit on the plated area. The above example is not meant to be restrictive, however, as several alterations to the above figures are permissible.

A better view of the positioning relationship between container 17, collecting reservoir 31, track member 11 and vibratory members 29 can be seen in FIG. 3. As shown, container 17 is positioned upon support member 41 which in turn overlaps the upstanding sides of reservoir 31. As also can be seen in this Figure, brackets 43 which hold vibratory members 29 are positioned on frame 45 which in turn is fixedly attached to surface 39. There is thus shown a means by which vibrational motion is indirectly supplied to each article which is to be plated. This motion is provided by vibratory members 29 via flanges 47, top portions 49 (or 49') and bottom portions 51 (or 51') of track 11. The areas of the articles that have been successfully plated by the present invention have exhibited many improved characteristics particularly with regard to brightness and adherence. It is believed that a relationship exists between the described vibrational motion imparted and the described subsequent improved characteristics in the plated areas. It is further believed that these improvements are the result of the effect of the described vibrational motion on the settling properties of the metal ions in the electrolyte solution, that is, this settling is believed improved by providing such motion.

With reference to FIG. 2, container 17 is illustrated and shown to comprise an electrolyte solution containing portion 60 and a rinse solution containing portion 61. Thus, it can be seen that as articles 27 travel along track member 11 in the direction of travel indicated in FIG. 2, the preselected portions to receive electrical deposition are adapted for traveling through designated cutaway portions 63 within container 17. Thus, there is shown a method by which these preselected areas will first contact the electrolyte solution afterwhich they contact a rinse solution. In the preferred embodiment, the rinse solution is deionized water. The electroplating solutions that are useful in this invention are known in the art. For example, gold patterns are deposited from an electroplating solution containing a gold concentration of about 1 to 1.25 ounces per gallon. Some examples of suitable gold plating solutions are sold by the Sel-Rex Corporation under the trade names "Autronex N," "Autronex NI," "Autronex C," and "Autronex CI." Those of the above examples which contain the "N" or "NI" designate are nickel alloy solutions of varying concentrations while those containing the "C" or "CI" designate are different concentrations of co alt alloy solution. The above solutions are not meant to restrict the present invention, however, as practically any metal, such as nickel, tin and the like, that is generally deposited by the apparatus and method of the present invention.

The electrolyte solution is supplied container 17 via piping 65 which terminates in the electrolyte solution containing portion of container 17 at a T-shaped nozzle 67. Nozzle 67 as shown has its end portions sealed off and is provided with a plurality of spacedly aligned apertures 69 located along the portion of the nozzle immediately adjacent the floor 71 of container 17. In this manner, the flow of solution is directed toward the floor of the container to assure a substantially stable surface for the solution. As illustrated, drain member 25 serves to maintain the desired level of the solution within the container. There is also provided an overflow means consisting of adjacently positioned overflow portions 73 and 73' respectively. When the solution attains the desired level as established by drain member 25, the excessive solution will overflow into drain member 25 and down into collective reservoir 31 where it is then recirculated through recirculation means 33 illustrated in FIG. 1. Should the level as established by drain member 25 be such that quantities of the solution will overlfow into overflow portions 73 and 73', this solution will thereby exit these portions via established openings in the bottoms of these portions. The solution will then return to reservoir 31 and be recirculated.

The rinse solution is supplied to the rinse portion of container 17 through pipe 75 where it exits into central reservoir 77. The level within reservoir 77 is established simply by the upper surfaces of baffle members 79 located within rinse portion 61. The rinse solution simply overflows from central cavity 77 into adjoining overflow reservoirs 81 and 81' respectively whereupon it exits through designated openings 83 located in the bottom of the reservoirs. The rinse solution is then recirculated by a recirculation means 85 illustrated in FIG. 1 as comprising a filter member 87 and a pump 89. In the present embodiment, the primary function of recirculation means 85 is to recover gold from any excess solution still present on the articles as they emerge from the plating area. This is accomplished by utilizing an ion exchange resin within filter member 87 which will attract gold particles from any solution passing therethrough. This resin is changed periodically and the gold recovered. A secondary purpose for rinsing each article is of course to clean the article prior to its removal from the apparatus. Thus, it can be seen that a continuously replenished supply of rinse solution is provided for rinsing area 61. To assure that a mixing between the electrolyte solution and the rinse solution never occurs within container 17, a separation baffle member 91 is provided in the manner indicated.

With reference to FIG. 4, the means for controlling the rate of travel of articles 27 within track member 11 is illustrated as comprising a rotating disc member 19 which rotates in the direction indicated. Positioned within rotating disc member 19 are a plurality of notch portions 93 which upon rotation of the member 19 are each adapted for engaging one of the articles 27 in the manner indicated and removing this article from track member 11. The article is then rotated to a drop station 95 which is shown to comprise a collection chute 97 having a substantially upright backstop member 99 affixed thereto. When rotating disc 19 moves one of the articles to station 95, the article is removed from the corresponding notch via an air supply means 101 which directs a flow of air in the manner indicated to the station. In doing so, each article is thereby forced into the collection chute 97 and thereafter to an externally located collecting bin (not shown). Rotating disc 19 is powered as illustrated in FIG. 1 by a drive motor 103 joined to the rotating disc via a reduction gear drive 105. It can readily be understood, however, that several varieties of drive means can be utilized and the illustrated embodiment is not therefore meant in any way restrictive to the present invention.

In FIG. 5 a typical example of one of the articles which can be plated by the present invention is illustrated. As can be seen, the preselected area indicated as 107 can receive a coating thereon of precious metal by utilizing the coating apparatus and method of the present invention. Utilization of the method and apparatus described assures that only preselected portions 107 will be plated on the article. Therefore, a substantial savings of electrolyte solution results. As has been shown in the drawings, it can also be seen that a method has been provided which includes an apparatus which is readily adaptable for coating substantially large quantities of articles in relatively short periods of time. In referring back to FIG. 4, it can be seen that the rate of travel of the articles along track 11 is readily controlled by the rate of rotation of circulating disc 19. To increase the rate of travel, the rotational rate of disc 19 in turn is also increased. To reduce the rate of travel to thereby achieve a thicker coating on the articles, the rate of rotation of disc 19 is simply reduced.

Thus, there has been shown an apparatus and a method for electroplating preselected portions of relatively large quantities of individual articles. The method and apparatus as described are capable of providing this electrical deposition in a relatively simple and inexpensive manner.

While there have been shown and described what is at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

Claims

1. An apparatus for electroplating preselected portions of individual articles, said apparatus comprising:

a track member adapted for having each of said articles travel therealong;

supply means for supplying said articles to said track member;

vibratory means engaged to said track member for effecting movement of said articles along said track member;

a container adapted for containing a predetermined quantity of electrolyte solution therein, said container positioned substantially below and related to said track member;

means for controlling the elevation of said electrolyte solution within said container whereby said solution contacts said preselected portions of said articles which protrude beneath the track member as said articles travel along said track member;

means for controlling the rate of travel of said articles along said track member;

first electrode means associated with said articles as said articles travel along said track member; and

second electrode means of opposite polarity than said first electrode means and associated with said electrolyte solution, said second electrode means spacedly positioned adjacent said preselected portions of said articles as

2. The apparatus according to claim 1 wherein said vibratory means engaged to said track member for effecting movement of said articles along said track member comprises a plurality of individual vibratory members

3. The apparatus according to claim 1 wherein said supply means for supplying said articles to said track member comprises a vibratory feed

4. The apparatus according to claim 1 including a rinse means for applying rinse solution to said preselected portions of said articles after said portions have contacted said electrolyte solution within said container.

5. The apparatus according to claim 4 wherein said rinse means is

6. The apparatus according to claim 1 including a recirculation means adapted for recirculating said electrolyte solution within said container.

7. The apparatus according to claim 6 wherein said recirculation means

8. The apparatus according to claim 4 including a recirculation means

9. The apparatus according to claim 8 wherein said recirculation means

10. The apparatus according to claim 1 wherein said means for controlling the elevation of said electrolyte solution within said container comprises an adjustable drain member positioned within the portion of said container

11. The apparatus according to claim 1 wherein said means for controlling the rate of travel of said articles along said track member comprises a rotating disc member having a plurality of individual notches formed therein, each of said notches adapted for engaging one of said articles

12. The apparatus according to claim 1 wherein said first electrode means associated with said articles comprises a cathode member and said second electrode means associated with said electrolyte solution comprises an

13. A method for electroplating preselected portions of individual articles comprising:

supplying said articles to a track member;

effecting a vibratory movement to said articles along said track member while an electrolyte solution contacts preselected portions of said articles which protrude beneath the track member; and

applying an electrical potential to said articles and an electrical potential of an opposite polarity to said electrolyte solution, thereby providing deposition of a metal on said preselected portions of said

14. The method according to claim 13 wherein said electrical potential applied to said articles is provided by a cathode member and said electrical potential of opposite polarity applied to said electrolyte solution is provided by an anode member.