Showing papers on "Sodium hypophosphite published in 1970"

Copper plating on zinc and its alloys

Abstract: Production of a uniform, continuous corrosion resistant bonded copper coating on a zinc or zinc alloy body, by a process which comprises contacting the zinc or zinc alloy body with an electroless copper plating composition or solution consisting essentially of a soluble copper salt, e.g., copper sulfate, a complexing agent, e.g., citric acid, and a reducing agent, e.g., sodium hypophosphite. The resulting zinc or zinc alloy body can then be contacted with a copper electroplating bath, and according to one embodiment the resulting copper plated zinc or zinc alloy body is then treated in a nickel electroplating solution, followed by treatment in a chromic acid electroplating solution, to provide a corrosion resistant bright attractive metal coating on the zinc or zinc alloy body. The above noted novel electroless copper plating composition, and the zinc or zinc alloy article coated with an electroless copper plating.

Short communication a study of the mechanism of the electroless deposition of nickel

Abstract: THE rate-controlling step for the electroless deposition of nickel is not completely understood. The rate law for the process shows a first-order dependence on the hypophosphite-ion concentration (at constant pH)lsa and a negative order with respect hydrogen-ion concentration with variable PH.~ Catalytic mechanisms,” thermodynamic arguments (ULZ common ion effects),3 and slow transport of hydrogen ions3** have been offered to explain the observed results. The experiments reported here are intended to clarify the controlling step in the electroless deposition of nickel and to offer a different approach to the study of electroless plating processes in general. The basic premise of this study is that electroless plating processes are mixed electrode systems6-7 wherein the anodic partial process is the oxidation of hypophosphite and the cathodic partial processes are hydrogen evolution and nickel deposition. Thus, at low pH (<4),)the hydrogen-evolution reaction would proceed at a rate comparable to that of nickel deposition, leading to low measured plating rates; while at high pH (4 < pH < 6), the rate of hydrogen evolution would be small compared to nickel deposition, leading to larger measured plating rates. In order to test the hypothesis of the applicability of the mixed potential theory to electroless plating, it was necessary to measure simultaneously the rate of nickel plating and the electrode potential of the sample being plated. Nickel foil or wire samples were used as one arm of a Wheatstone bridge in order to detect changes in resistance of the foil during the plating operation. A second nickel sample used in the Wheatstone bridge circuit was coated with epoxy and immersed in the plating bath in order to obviate temperature corrections for the plated sample. The experimental sample was cleaned in distilled water, cathodically treated in 6 N HCI, rinsed in water, given a nickel strike, and immersed in the plating bath. The plating bath contained O-5 M sodium acetate, O-5 M acetic acid, and variable amounts of sodium hypophosphite (O-05 to l-0 M) and nickel chloride (O-05 to 1-O M). The bath was stirred by a Teflon paddle and thermostated at 90°C. In order to minimize pH changes, the ratio of solution volume to surface area was large and no experiment lasted longer than 4 h. The change in thickness of the sample was calculated from the measured resistance change?, and the plate thickened linearly with time for all experiments.

Electroless codeposition of nickel alloys

Abstract: THE INVENTION RELATES TO A METHOD FOR ELECTROLESSLY DEPOSITING A NICKEL-TIN ALLOY LAYER AND FOR DEPOSITING A NICKEL-MOLYBDENUM ALLOY LAYER AND TO BATHS THEREFOR THE ELECTROLESS PLATING BATH FOR NI-SN COMPRISES AN AQUEOUS SOLUTION CONTAINING NICKEL IONS, STANNATE IONS, SODIUM TARTRATE, SODIUM HYPOPHOSPHITE, GLYCINE AND SUFFICIENT KOH TO BRING THE BATH TO A PH OF ABOUT 135 THE ELECTROLESS PLATING BATH FOR NI-MO COMPRISES AN AQUEOUS SOLUTION CONTAINING NI IONS, GLYCINE, SODIUM HYPOPHOSPHITE, MOLYBDATE IONS, AND KOH TO BRING THE PH TO ABOUT 135

A new spot test for palladium using triphenylmethane, thiazine, and azo dyes

Abstract: A new spot test for palladium using Erioglaucine A, Eriogreen B, Xylenecyanol FF, Setoglaucine 0, Setocyanine Supra, Fast Green FCF, Methylene Blue. Thionine, or Methyl Orange is described. The method consists in treating one drop of the palladium salt solution with 2 to 2.8 ml of saturated sodium hypophosphite solution and 0.1 ml of 0.01% dye solution, making the total volume 3 ml and keeping the mixture in a boiling water bath. The color of the dye is discharged in 5 to 9 seconds in the case of the first six dyes and immediately in the case of the other dyes. The identification limits lie between 0.003 and 0.06μg in 3 ml and the dilution limits vary from 1∶5·107 to 1∶109 depending upon the dye that is employed. Iodide and most metals do not interfere in the test; alkalis and acidity beyond 0.1N decrease the sensitivity of the test.

Process for electrolessly plating magnetic thin films

Abstract: A PROCESS FOR ELECTROLESSLY PLATING SUBSTRATES WITH THIN FILMS OF MAGNETIC MATERIAL WHICH IS CARRIED OUT IN A TEMPERATURE RANGE WHICH INCLUDES ROOM TEMPERATURE. THE PROCESS INCLUDES THE IMMERSION OF SUBSTRATE IN AN AQUEOUS SOLUTION WHICH CONTAINS IRON IONS AND AT LEAST ANOTHER METAL ION SUCH AS NICKEL, WHICH UPON DEPOSITION FORM THE MAGNETIC MATERIAL. A REDUCING AGENT SUCH AS SODIUM HYPOPHOSPHITE IS PROVIDED IN THE BATH IN AN AMOUNT SUFFICIENT TO CAUSE DEPOSITION OF THE METALS IN SMALL GRAIN SIZES. SUFFICIENT HYDROXYL IONS ARE ALSO PROVIDED TO MAINTAIN THE BATH IN CONDITIONS WHICH RANGE FROM SLIGHTLY ACIDIC TO HIGHLY ALKALINE. THE BATH IS THEN MAINTAINED IN A TEMPERATURE RANGE WHICH INCLUDES ROOM TEMPERATURE OVER WHICH RANGE THIN FILMS HAVING A CHARACTERISTIC SILVERY FINISH INDICATIVE OF SMALL GRAIN SIZE ARE PRODUCED. THE PROCESS ALSO INCLUDES THE STEP OF AGING A FERROUS BATH FOR A PERIOD OF TIME SUFFICIENT TO CONVERT THE FERROUS IONS TO STABILIZE THE BATH. THE ABOVE-MENTIONED CONSTITUENTS AND OTHER COMPLEXING AND BUFFERING AGENTS WHICH PREVENT THE PRECIPITATION OF THE METALS FROM SOLUTION ARE PRESENT IN THE SOLUTION IN SELECTED CONCENTRATIONS WHICH PERMIT THE PLATING OF SMALL GRAIN SIZE MAGNETIC FILMS AT LOW TEMPERATURE.

Formation Mechanism of Electroless Plated Au Films

Abstract: The formation mechanism of single and poly-crystalline Au films, which had been obtained on iron substrate from electroless plating bath containing sodium hypophosphite as a reducing agent, was examined by direct observation and diffraction method of electron microscope.The following results were obtained:1) Au micro-particles of less than 100A in size were observed in the early stage and no coherency was found between the micro-particles and iron substrate.2) When the Au micro-particles were coalesced and grew up to the size of about 130A, coherency began to be found between Au-particles and iron substrate. However, there still remained a little misalignment of particles.3) The misalignment was gradually reduced with the growth of particles and it reached the minimum when the iron surface was completely covered with Au plate crystals, which turned into single-crystalline.4) The plate crystals again turned to poly-crystalline with the further lapse of plating time owing to the growth of particles having random crystal orientation in defects of the single crystals.5) The coherencies between the Au plate crystals and iron surface immediately after the surface was covered by the crystals were as follows:(001) Fe||(001) Au [110] Fe||[010] Au} (1) (110) Fe||(110) Au [001] Fe||[110] Au} (2)6) In the early stage, Au micro-particles were coalesced with no change of shapes: that is, they did not develop to network structure, different from those obtained by galvanic substitution.7) The maximum density of Au micro-particles in the deposits obtained by electroless plating was about 2.2×1012cm-2.

Microstructure of Electroless Plated Au Plate Crystals

Abstract: Au plate crystals were prepared on iron substrate by means of electroless plating using sodium hypophosphite as a reducing agent and their microstructure was investigated by direct electron microscopy and electron diffraction.The results obtained were as follows:1) Two kinds of rotational moire patterns were observed in the Au plate crystals. One pattern was observed on the subboundary of the crystals, and the other was observed covering fine particles which had grown up on the crystals. In the stage of crystal growth, the stress due to lattice defects in the crystals was relaxed by the rotation of these particles.2) Electroless plated Au plate crystals contained many micro-twins which contributed to relax the stress. These micro-twins were formed in the initial stage of crystal growth. The width of micro-twins increased with the thickness of the crystals, but the length was independent of the thickness.