US2801963A - Apparatus for the determination of plating characteristics of plating baths - Google Patents

Description

Aug. 6,- 1957 o. HULL ET AL 2,801,963

R. APPARATUS FOR THE DETERMINATION OF PLATING CHARACTERISTICS OF PLATING BATHS Filed Dec. 8, 1953 2 Sheets-Sheet l INVENTOR. ,/chwea 0, Hull. JOHN B. h/IIVTEPJ Aug. 6, 1957 R. o. HULL ET AL 2,801,963

APPARATUS FOR THE DETERMINATION OF PLATING CHARACTERISTICS OF PLATING BATHS 2 Sheets-Sheet 2 Filed DeC. s, 1955 INVENTOR.

l/cx/aeo O. HUAA BY Jam/u a [MA/r525 2,801,963 Patented Aug. 6, 1957 United States atent fiice APPARATUS FOR THE DETERMINATION OF PLATING' CHARACTERISTICS OF PLATING BATHS RichardYO. Hull, RockyrRiver, and John B. Winters, Westlake, Ohio, assignors to Ann F. Hull and Adrian Medert, as cotrustees, Cleveland, Ohio Application December 8', 1953, Serial No. 396,815 7 Claims. (Cl. 204-495) This invention relates to the electrodeposition of metals and. more particularly to apparatus for the examination, e luation, and determination of the plating characteristi'cs of a plating bath or a series of plating baths used in a sequence of'plating operations.

Heretofore, it has been the practice in the electrodeposition of metals to examine or evaluate the plating characteristics-eta plating bathby taking samples thereof and-"subjecting them to examination under laboratory conditions. This practice and the apparatus employed is clearly. set forth in United States Patent No. 2,149,344 to R. O. Hulhdated March 7, 1939. It has also been the priorpractice to attempt to determine, in a limited way the behavior of a single plating bath under operating conditions simply by immersing a flat plate or bent cathode in..the platingbath, suspended from the cathode busbar. Ithas also been the practice in determining the various current densities obtained in a plating bath, or irregularly shaped articles, to use a probe electrode to measure the current passing to various parts of such an article from the cathode busbar.

Theprior practices referred to above left a great deal to-be desired in evaluating and determining the plating characteristics of a plating bath or a series of plating operations includingfor example, cleaning, pickling, and

I rinsing, followed by copper, nickel or chromium plating.

Any fault or defect in any one of such a sequence of operations, numbering in some cases as many as ten to twelve consecutive steps, will result in a defectively plated product. Moreover, it was extremely diflicult to ferret out the particular fault in the sequence of operations with the limited means available for testing, and it has been necessary to attempt. to trace the source of each fault by trial and error with the result that an excessive amount of'rejected plated products was experienced. Furthermore, it has been. difficult or impossible to establish the optimum. operating conditions, such as current density, temperature and bath compositions, in a plating bath or sequence of plating operations by simple test methods carried on-remote therefrom by reason of the failure to simulate or duplicate operating conditions under such test methods. Hence it has been difficult to control the plating operations to obtain optimum results at all times. This-has been particularly true with respect to alloy plating..such as. brass plating in which variations in current density either are single point or throughout the bath produce undesirable variations in composition of deposit. Accordingly, there has been no simple means for detecting a fault in. a. plating sequence under actual plating operating conditions so that the difficulty or difficulties resulting in unsatisfactorily plated products can be pinpointed easily and accurately.

The foregoing discussion of the prior practices is true not only of still plating, wherein the objects to be plated are immersed in a single tank of plating solution until: the. desiredthickness of deposit is obtained, but it is even more applicable to automatic or continuous plating machines wherein objects or racks of objects to be plated are mechanically transported from one tank to another and through each tank, so that a series of operations, such as cleaning, rinsing, pickling, plating, dipping, etc., can be carried out in sequence without handling the objects or racks between operations. Such automatic plating machines are extensively used in the electroplating industry, and for successful operation it is essential to know what the actual working conditions areat all times in all parts of the system, so that changes and adjustments in operating conditions within the various units may be made with respect to each other, to obtain uniform andsatisfactory plating results.

The foregoing drawbacks prevalent in prior methods oftesting plating baths have been completely surmounted by the present invention.

Our invention is designed to assure obtaining satisfactory results by providing a simple means to determine the plating characteristics of a single bath, or of a series of baths in a plating sequence, whether in a manually operated system or in a fully automatic mechanically operated plating machine. Our apparatus can be put through one or all or any number of the steps in a plating sequence to determine a single characteristic or the cumulative results produced by the system. Not only does our invention determine the plating characteristics of the baths, but also provides a means for determining the nature of the deposit, either in one bath or cumulatively through a sequence of operations. Our apparatus provides-a simple means for determining and controlling such factors as brightness of deposit, uniformity of composition of an alloy deposit, uniformity of current distribution, optimum current density range for producing a desired result, and any other factor that is essential in establishing, and maintaining optimum operating conditions in a plating bath or a sequence of plating operations.

t is among the objects of the present invention to provide apparatus for determining the plating characteristics of a plating bath under actual production conditions.

Another object of the invention is to provide apparatus to determine the characteristics of the electrodeposit upon an article at any point in a sequence of plating operations.

A further object of the invention is to provide apparatus for producing a test plate under actual operating conditions covering the entire range of current densities of theplating bath whereby the optimum current densities to be used may be determined.

A still further object of the invention is to provide apparatus adapted to be suspended from the cathode busbar of the plating bath and moved through the plating bath, to indicate the current densities existing within the plating bath at every point of its path of travel therethrough.

A still further object of the invention is to. provide apparatus to determine in the plating bath, the proper distribution andplacing of anode material with relationto the article being plated.

Another object of the invention is to provide apparatus for producing a test plate which would reflect deviations from the optimum operating condition of any plating bath relative to any other plating bath in a sequence of plating operations to produce an optimum plate.

Another object of the invention is to provide apparatus for determining the source and cause of undesirable results in a sequence of plating operations such as are encountered in an automatic continuous plating: machine These and other objects and advantageous features of the inventionnot at this time more particularly pointed out will become apparent as the nature of the invention isbetter understood. from the following detailedzdescription taken in conjunction with the accompanying drawings, wherein like reference characters denote corresponding parts, and wherein:

Figure l is a side elevational view partly broken away of a device for determining the plating characteristics of a plating bath embodying the present invention,

Figure 2 is a front elevational view with parts in section of the device illustrated in Figure 1,

Figure 3 is a view taken on the line 3-3 of Figure 1,

Figure 4 is a top plan view taken on the line 4-4 of Figure 1,

Figure 5 is a fragmentary detail view taken on the line 55 of Figure 4,

Figure 6 is a sectional view taken on the line 6-6 of Figure 5,

Figure 7 is a fragmentary detail View taken on the line 7-7 of Figure 6.

Figures 8 and 9 are transverse and longitudinal sectional views, respectively, of a plating tank illustrating the use of the present invention therein.

With reference to the accompanying drawings there is illustrated a device for determining the plating characteristics of a plating bath, constructed in accordance with the present invention and comprising a hollow container generally indicated by the number llll having a rectangular vertically disposed opening. In the embodiment illustrated the container takes the shape of a hollow trigonal prismatic figure having side walls 12 and 13 angularly disposed with respect to each other, a top wall 14 and a bottom wall 15. The walls of the container are joined together in any suitable manner being formed of a non-conducting material which is impervious to the action of a plating bath, such as a transparent synthetic resin, namely polymerized methyl methacrylate sold in the trade under the name Lucite. The top and bottom walls 14 and 15 are longitudinally slotted as at 16 and 17, respectively, adjacent the side wall 13 to receive a test plate or panel 18 arranged in a vertical position within the container, parallel to the side wall 13. Adjacent the intersection of the side walls 12 and 13 the latter is provided with an aperture 19. Secured to the outer surface of the wall 13 is a member 20 having an opening therethrough in alignment with the aperture 19. A plug 21 having a contact 22 on the outer end thereof is received in the aperture 19, the contact being arranged to engage the test plate 18 and convey current thereto as will be disclosed hereinafter. The plug 21 is maintained within the aperture 1% by means of a flexible strip member 23 having a bifurcated end 24 which slidably engages l the neck portion of plug 21. The other end of the strip is slidably mounted within a slotted block 25 secured to the outer surface of the side wall 13.

Suitable openings 13A are provided in the top and bottom walls 14 and 15, respectively, adjacent the apex between the side walls of the container to provide escape of air upon insertion of the container into the plating bath and drainage of solution from the container upon removal from the bath.

The container 10 carrying the test plate 155 is adapted to be suspended from the cathode busbar of a plating tank A diagrammatically illustrated in Figures 8 and 9 of the drawings. The tank A contains the usual anode busbars 27 from which the anode material 28 to be plated is suspended in the plating bath 29. The cathode busbar is indicated by the numeral 3 it is to be understood that the term busbar is used in the specifications and claims to indicate the means of connecting the apparatus in the electrical circuit.

The supporting assembly for the container 10 includes a hanger member 31 having a substantially horizontal portion 32 with hook members 33 formed on the ends thereof. The hanger 31 is made of any suitable current conducting material and the hooks 33 are arranged to hang over the cathode busbar. The horizontal portion 32 of the hanger seats within a horizontal slot 35' formed in the rear face of the housing 36 of an ammeter 37 provided with a dial 38 from which readings may be obtained of the current passing therethrough. The hanger is secured to the housing 36 by means of spaced bolts 39 the inner end of one bolt being connected to one terminal of the ammeter 37 by conductor 40.

A bracket member 42 is arranged to connect the ammeter 32 to the upper end of a column 43 leading to the container it}. The bracket member is in the form of a bar having one end 44 turned at an angle thereto and secured to the housing 36 by means of a bolt 45, the inner end of which is connected to the other terminal of the ammeter by means of conduit 46.

The column 43 comprises a cubical block 47 suitably nod to the upper surface of the top wall 14 of the container iii and is bored as at 48 and counter-bored as at 49 to receive the lower end of a tubular member 50. The upper end of the tube 50 receives the shank portion 51 of a cylindrical member 52. The upper surface of the member 52 is provided with intersecting transverse slots 53 which receive the free end of the bracket 42. A conductor tube 54 is mounted within the tube 50 having one end engaging within the shank 51 and the other end seating within the bore 48 of the block 47. A threaded bolt extends from the upper end of the bar 54 and is secured to the bracket engaging within one of the slots 53 of collar 52. The column 43 is constructed of sufficient rigidity and weight to assume a vertical position in the plating tank and maintain the container in a predetermined fixed position in the bath. To this end the conductor tube 54 is filled with weighted material and the cylindrical block 54A is provided in the lower end of the tube 50.

Theblock 47 is provided with a horizontal bore 56 which traverses the bore 48 and is adapted to receive a conductor member 57 which is threaded through the lower end of the bar 54. The outer end of the bore 56 is provided with a terminal outlet 5% which receives a plug 60. An insulated conductor connects the plugs 60 and 19. in using the device of the present invention current flows from the cathode bar 3%, thru hanger 31 to one of the bolts 39, conductor 4t? to one terminal of the ammeter 37, thru ammeter 37 to the other terminal thereof, thence through conductor 46, bolt 35, bracket 42, bar 54, member 57, conductor 61 to terminal contact 22 engaging the test panel 18.

This invention provides a simple means for testing a plating bath by suspending a flat test panel in the plating bath under operating conditions which, by geometric configuration in a suitable container or holder, portrays the plating characteristics of the bath over the entire range of current densities encountered in the bath. The optimum range of current densities is immediately determined by a close mathematical relationship between the location of the bright or operable range on the test panel and the current read on the ammeter of the device. Any clouds, blisters, uncovered areas or burnt deposits are immediately apparent by visual inspection of the panel. The invention when used in a plating sequence serves to record differences between operating conditions of successive plating baths as is reflected on the test panel. Where such diiferences result in an unsatisfactory product adjustments may be made in current density, temperature or bath compositions so that the operating conditions in successive baths are coordinated to produce the desired plate on the article under treatment.

Having thus described our invention what we desire to obtain by Letters Fatent is defined in the appended claims.

We cl 1. Apparatus for determining the plating characteristics of a plating bath disposed in a plating tank having anode material immersed therein and a cathode busbar comprising a supporting member suspended from the cathode busbar, a hollow trigonal prismatic container having one open side attached to the lower end of the supporting member, a test plate mounted vertically within the container angularly disposed with respect to the open side of the container, and means for conducting current between said busbar and the said test plate and means for measuring the current flowing to said test plate.

2. Apparatus for determining the plating characteristics of a plating bath disposed in a plating tank having anode material immersed therein and a cathode busbar comprising a hollow trigonal prismatic container having one open side of rectangular shape, a test plate vertically mounted within the container, means for supporting said container within said plating bath, means for conducting current between said cathode busbar and the said test plate and means for measuring the current flowing to said test plate.

3. Apparatus to be employed as a Hull cell in determining the plating characteristics of a plating bath disposed in a plating tank having anode material immersed therein and a cathode busbar comprising a hollow trigonal prismatic container having one open side to permit the flow of the plating bath into the container, a test plate vertically mounted within the container, means for supporting said container within said plating bath during the operation of the plating tank, means for conducting current between said cathode busbar and the said test plate, and means for measuring the current flowing to said test plate.

4. Apparatus for determining the plating characteristics of a plating bath disposed in a plating tank having anode material immersed therein and a cathode busbar comprising a hollow trigonal prismatic container having one open side of rectangular shape, a test plate vertically mounted within the container and angularly disposed with respect to said opening, means for supporting said container from said cathode busbar Within the plating bath, and a conductor disposed within said supporting means for transmitting current between said busbar and the said test plate and means for measuring the current passing through the test plate.

5. Apparatus for determining the plating characteristics of a plating bath disposed in a plating tank having anode material immersed therein and a cathode busbar comprising a supporting member suspended from the cathode busbar, a hollow trigonal prismatic container formed of non-conducting material having a rectangular open side to permit the introduction of plating solutions into the container, a test plate mounted vertically within the container closely adjacent one side wall, means for conducting current between said busbar and the said test plate and means for measuring the current flow to said test plate.

6. Apparatus for determining the plating characteristics of a plating bath disposed in a plating tank having anode material immersed therein and a cathode busbar comprising a hollow trigonal prismatic container formed of non-conducting material having a rectangular open side to permit the flow of electrolyte through the container, a hollow supporting member adapted to suspend the container from the cathode busbar within the plating bath, a test plate vertically mounted within the container and angularly disposed with respect to said rectangular open side, conductor means contained within said supporting member for conducting current between said busbar and the said test plate, and means for measuring the current passing through the test plate.

7. Apparatus to be employed as a Hull cell in determining under operating conditions the plating characteristics of a plating bath disposed in a plating tank including anode and cathode busbars, anodle materials suspended from said anode busbar, a hollow container made of non-conducting material suspended from said cathode busbar having a rectangular opening therein, a test plate vertically mounted in the container at an angle with respect to said opening, and means for conveying current between said cathode busbar and said test plate, said test plate adapted to receive a deposit of anode material from one end of the plate to the other which is indicative of the actual plating range present in the bath.

References Cited in the file of this patent UNITED STATES PATENTS 1,519,572 Wolf Dec. 16, 1924 2,149,344 Hull Mar. 7, 1939 2,500,206 Schaffer et a1 Mar. 14, 1950 FOREIGN PATENTS 292,417 Great Britain June 21, 1928

Claims (1)

1. APPARATUS FOR DETERMINING THE PLATING CHARACTERISTICS OF A PLATING BATH DISPOSED IN A PLATING TANK HAVING ANODE MATERIAL IMMERSED THEREIN AND A CATHODE BUSBAR COMPRISING A SUPPORTING MEMBER SUSPENDED FROM THE CATHODE BUSBAR, A HALLOW TRIGONAL PRISMATIC CONTAINER HAVING ONE OPEN SIDE ATTACHED TO THE LOWER END OF THE SUPPORTING MEMBERS, A TEST PLATE MOUNTED VERTICALLY WITHIN THE CONTAINER ANGULARLY DISPOSED WITH RESPECT TO THE OPEN SIDE OF THE CONTAINER, AND MEANS FOR CONDUCTING CURRENT BETWEEN SAID BUSBAR AND THE SAID TEST PLATE AND MEANS FOR MEASURING THE CURRENT FLOWING TO SAID TEST PLATE.

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