Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/56—Electroplating: Baths therefor from solutions of alloys

Definitions

• 2,751,341 it has been proposed to effect electrodeposition of lead or a lead alloy, or of antimony or an antimony alloy, from a solution containing an alkali metal salt of ethylenediaminetetraacetic acid, which is said to give a smooth, lustrous, even, bright deposit of metal; electrodeposition of lead-indium alloys from such a solution is said to give most satisfactory results when the bath is operated with a cathode current density of 10- 20' amperes per square foot.
• the present invention is concerned with electrodeposition of alloys of lead and indium particularly at high cathode current densities, up to 120 amperes per square foot.
• controlling agents ethylenediaminetetraacetic acid which for the sake of brevity is hereinafter sometimes called enta.
• Other controlling agents suitable for our purpose are the propylenediaminetetraacetic acids and cyclohexane 1.2 diaminotetraacetic acid.
• the baths in which these controlling agents are used are preferably neutral, or nearly neutral, the controlling agents being then in fact present in the form of salts, which may be the sodium, potassium or ammonium salts, or mixtures of such salts.
• 2' zine in a solution containing enta is preferentially oxidised by an insoluble anode, thus minimising the destruction of enta.
• the decomposition products of hydrazine are not harmful in any way in contrast to the case when enta alone is oxidised. Hydrazine also destroys any formaldehyde which would otherwise gradually accumulate in the electrolyte, despite the greatly retarded oxidation of enta. It is therefore possible by the addition of hydrazine to our electrolytes to maintain the meta ion concentration at the desired value by the periodic use of insoluble anodes without excessive loss of controlling agent by oxidation.
• Electrolytes used in the practice of the present invention thus contain compounds of lead and indium, one of the above mentioned controlling agents, and also hydrazine. With advantage they also contain citric acid (or alternatively tartaric acid), a small proportion of gelatin, triethylenetetramine (or alternatively diethylenetriamine or ethylenediamine), and ammonium chloride.
• Citric acid 45-55 Hydrazine 9.5-625 Ammonium chloride 5-30 Gelatin 0.2-2.0 Triethylenetetramine 1-10 If tartaric acid is employed in place of citric acid, the
• the lead and indium may be introduced into the electrolyte as the hydroxide, sulphate, acetate, chloride or carbonate. Lead and indium nitrates may also be used but we prefer to exclude the presence of the nitrate ion from our electrolytes because of its action as a cathode inhibitor with respect to the deposition of indium.
• the bath is adjusted to have a pH value in the range 5.0 to 7.0, 6.0 being preferred, and is operated with an insoluble anode (and preferably also with a soluble anode) at a temperature in the range 45 to 70 C., about 60 C. being preferred, and with a current density in the range 60 to amperes/square foot.
• the leadindium alloy deposited contains from about 7% to about 10% indium, depending upon the precise operating conditions used. For example, raising the temperature will decrease the indium content of the alloy deposited. An increase in pH value will increase the indium content of the alloy deposited, as also will an increase in current density.
• the constituents of the bath other than lead and indium need only be added as often as is necessary to combat the effects of drag-out.
• the rate of decomposition of the controlling agent is reduced to a very small value.
• soluble anodes In order to maintain the metal content of the bath, it is preferable to use soluble anodes together with the insoluble anodes.
• the soluble anodes may be of pure indium and pure lead, or of the appropriate indium-lead alloy.
• the insoluble anodes are preferably of graphite.
• a rotating or other type of commutator may be employed, which is adjustable so that the times for which the respective anodes are connected and the frequency with which they are changed over may be varied as desired, to maintain the correct metal balance in the bath.
• the bath contains also a polyarnine selected from the group consisting of triethylenetetramine, diethylenetriamine and ethylenediamine.
• the bath contains the following constituents in quantities within the respective ranges stated, in grams per litre: lead 15 to 25; indium 10 to 15; a water-soluble salt of ethylenediaminetetraacetic acid 85 to 115; an organic acid selected from the group consisting of citric acid to and tartaric acid 35 to 45; hydrazine 9.5 to 62.5; ammonium chloride 5 to 30; gelatin 0.2 to 2 and triethylenetetramine 1 to 10.

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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 And Plating Baths Therefor (AREA)
• Electrolytic Production Of Metals (AREA)

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ID=10378017

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Country Status (7)

Cited By (3)

Citations (1)

Family Cites Families (2)

• 0
  • BE BE553110D patent/BE553110A/xx unknown
  • NL NL111650D patent/NL111650C/xx active
• 1955
  • 1955-12-02 GB GB34550/55A patent/GB799280A/en not_active Expired
• 1956
  • 1956-11-30 US US625208A patent/US2831803A/en not_active Expired - Lifetime
  • 1956-11-30 FR FR1160985D patent/FR1160985A/fr not_active Expired
  • 1956-11-30 CH CH354644D patent/CH354644A/fr unknown
  • 1956-11-30 DE DEV11591A patent/DE1053275B/de active Pending

Patent Citations (1)

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