Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D7/00—Electroplating characterised by the article coated
  • C25D7/06—Wires; Strips; Foils
  • C25D7/0614—Strips or foils
  • C25D7/0671—Selective plating
  • C25D7/0678—Selective plating using masks
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/02—Electroplating of selected surface areas

Definitions

• the contact resistivity of the contacts of electromechanical parts operating in highly corrosive medium may change to such extent, that they become useless.
• the breakdowns may be caused by other conditions as well. Wear of the surfaces in contact is significant among the causes of breakdown in apparatuses operating similarly with low signal levels. This phenomenon occurs in the elctromechanical parts of the frequently used apparatuses.
• the various precious metal layers applied on the contacting surfaces are qualified for preventing the breakdowns arising from corrosion and wear.
• Mainly copper is used as the basic material of cantacts, for its excellent suitability to carry out the current-conduction function.
• the copper is generally used in various alloys.
• alloying elements to the copper, first of all the various mechanical properties can be altered. Increased hardness, tensile strength, elongation, etc. can be attained with the various bronze alloys, produced in the form of plate, band and rod (sometimes casting).
• a certain part of the electric contacts performs springy function, in order to bring about contact pressure of adequate extent. Regarding their shape they can be produced by milling and metal pressing.
• Silver (Ag), palladium (Pd), rhodium (Rd), gold (Au), and platinum (Pt) are generally used for precious metal coating of the electric contacts produced all over the world.
• spot plating of the bands with precious metal is a suitable technological method for the final elimination of the precious metal losses arising as described above.
• the pressing of the line of guide-holes represents extra operation, but this input is negligible compared to the attainable saving of the precious metal.
• the operation is rationally carried out on quick-pressing machine by pressing about 4-10 holes at a time.
• the ⁇ 0.005 mm hole spacing or stepping accuracy is decisive.
• precious metal can be applied not only on the working surface of the direct contact, but - first of all for corrosion reasons - it is applicable also on the small surface cut perpendicularly to it. Its advantage is, that the traces of possible corrosion can be kept away from the working surface.
• the band parts not to be plated with precious metal are led along the whole length of the bath between adjustable screening plates produced from nonconductive material (syntherics not detrimental to the precious metal baths, such as PVC, polypropylene, etc.).
• Plane of the band surface in the bath may be: horizontal and vertical.
• the band parts not to be plated with precious metal are coated with lacquers not detrimental to the precious metal baths, which screening material is removed with chemical and mechanical means after the plating.
• the lacquer for screening is applied on the band with rolls by sprinting technical method, after the described prepressing, proper cleaning, washing and drying of the surfaces.
• the screening to be printed on the band is applied on the mantle of the pressing rolls naturally with consideration to the line of guide-holes as spacing and positioning basis. Diameter of the pressing rolls is selected as to be able to apply whole divisions around the mantle (roll diameter is about 80 - 120 mm).
• Quality (consistency) of the lacquer material is selected as to attain about 0.1 mm edge accoracy at the limit of the lacquered and unlacquered surfaces. Impression of the lacquer is continuous and after the process it is dried at about 140 - 160°C temperature for 20 - 25 seconds by pulling through an electric drying oven at continuous rate, then it is wound up for plating. The plating in this case is carried out by pulling through the band in its horizontal position without bending. Thickness of the metal and precious metal layers is influenced by the parameters of the applied plating bath, length of the plating tubs and the rate of pulling through the band.
• the described band screening and selective band plating apparatuses, as well as the related technology generally fulfil the technical-economic requirements related to the use of precious metals in respect of both the qualitive and reduced quantitative utilization.
• the band plating apparatus performs the mechanical screening of any surface of the band in a relatively simple way.
• Figure 1/a Overflow plating bath circulating apparatus
• Figure 1/b Top view of Figure 1/a
• Figure 1/c Side view of Figure 1/a, partly sectional view
• Figure 2 View of metal band.
• FIG. 3 Top view of band plating apparatus
• Figure 4 View “A” of Figure 3.
• Figures 5/a,b,c Band formations.
• Figure 6 Selective plating apparatus
• Figure 7 View "A" of Figure 6
• the plating is carried out in the "overflow plating bath circulating apparatus" according to
• the build-up of the apparatus is suitable for lifting the level of the plating bath to variable height.
• Fine adjustment of the bath level 8 is accomplished with the aid of two adjustable regulating slides 11 mounted above the overflow edge at the two ends of the plating tank 1.
• the apparatus is mounted with its base plate onto a horizontal table top 12, below which a synthetic tub suitable- for receiving the plating bath is arranged with the necessary filtering, heating and circulating pump system. Length of the apparatus is determined by the exposition parameters of the plating bath, the necessary maximum layer thickness and by the speed of band conveya
• the plating and the similarly built economy-flushing and flushing apparatuses are arranged parallel with the longitudinal axis one after the other in accordance with the technological sequence in such a way, that the band with vertical surface can be pulled through in a straight line along the centreline of the apparatuses.
• the band is pulled through with driving gear driven rolls, the speed of which is adjustable with interchangeable gears 20. Should the set band pulling speed result in greater layer thickness at one of the plating apparatuses or baths within the technological sequence, while it is the required value at another one, it is possible - at identical band speed and under the same current conditions - to reduce the layer thickness (clearly shown in the drawing) by replacing the plating tank with a shorter one within a few seconds.
• the new band plating apparatus mechanically screens the. band surfaces at the required places in such a way, that the screening band moves together with the plating band at the same rate.
• the band surface(s) to be plated will be continuously screened on one or both sides until the band moves in the plating tank.
• the screening bands made suitably of synthetis material or thin metal coated with synthetic material are mounted - after blind splicing - in such a way, that the spacing of the line of guideholes pressed on at spot plating and spacing of the plating spots should be of whole size at the blind splicing.
• Suitable quality and thickness of the screening bands are the following: At strip plating:
• spot plating
• Polytetrafluorethylene is one of the best synthetic materials that meets above requirements, but there are synthetics which are also effectively applicable on the metal band, e.g. with electrostatic dusting followed with burning-in.
• the spacing accuracy of the pressing for screening bands 16, 17 - similarly to the spacing accuracy of the line of guide-holes for the spot plating bands - is generally ⁇ 0.005 mm, hence it is suitable to punch the line of guide-holes with the same tool naturally complemented with the cutout of the spot(s) to be plated (by use of interchangeable stamp in the prepunchnig tool).
• the figure shows the plain and pinned discs driving the bands to be plated and the screening bands.
• the band drive with pinned disc ensures the synchronous running of the band and screening bands, furthermore the identical height in vertical direction.
• the screening bands on the band screening devices can be tensioned as shown in the drawing (with mobile tensioning rollers).
• the apparatus is adjustably arranged on two brackets in the longitudinal axis of the plating apparatus.
• Fixed and spring-loaded 33 tensioning rollers 35 are arranged on the main support 30 of the apparatus at suitably selected distances, which prevent the lateral displacement of the synchronous running band surfaces and this way no excess precious metal is applied on the band.
• the so-called "rear" screening band is mostly a plain non-perforated synthetic material, or metal band coated with synthetic material.
• this "rear" screening band can be separated from the metal band - after running out of the bath - and can be guided back already earlier than the one on the front side. This way the cathode current can be conduct onto the band with the aid of the plain metal disc opposite the pinned conveyor disc.
• the figures show the band conveyor driving gear with the aid of which - through interchangeable gears - the speed of the band is variable. Synchronization of the speed of the screening bands and metal band is attained with further gears with the same tooth number - participating in the drive - and with chain wheels (similarly with the same tooth number).
• the band plating apparatus and related band screening device described in the foregoing are not the only possibilities for solving the task.
• a band plating apparatus was worked out - as shown in Figure 11 - with the related band screening device.
• Principle of the solution is similar to the one applied at the above described band screening device with the difference, that the metal band to be plated moves with horizontal surface in the plating bath together with the screening bands.
• the band movement from one bath into the next one is aided with guide rollers arranged between the tubs, while tensioning of the screening bands is ensured with tensioning rollers arranged on separately moving carriages.
• the plating tubs have small volume, the baths are delivered with separate pump system from the large sized tanks arranged separately. (Naturally through the necessary filtering and heating devices.)
• the band movement - at variable speeds - is carried out with the driving gear arranged after the plating tubs assembled according to the sequence of the operation.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electroplating Methods And Accessories (AREA)
• Steroid Compounds (AREA)

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• 1981
  • 1981-05-06 WO PCT/HU1981/000020 patent/WO1981003187A1/en not_active Application Discontinuation
  • 1981-05-06 EP EP19810901333 patent/EP0052125A4/de not_active Withdrawn
• 1982
  • 1982-01-06 NO NO820022A patent/NO820022L/no unknown

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