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
• • 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
  • C25D3/60—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of tin

Definitions

• a bright tin-nickel alloy plating electrolyte consists essentially of an aqueous main plating liquid containing a stannous salt, a nickel salt and an alkali-metal pyrophosphate, with a brightener additive in such main plating liquid which is a compound having a plurality of amino groups, for example, ethylenediamine, 1,2- propanediamine, 1,3-propanediamine, l ,4- butanediamine, pentamethylenediamine, hexamethylenediamine, hydrazine, guanidine, urea or thiourea, and with a further addition of ammonia or an ammonium salt.
• the electrolyte may further have added thereto a compound having at least one SX group in this electrolyte (in which X represents hydrogen, sodium or potassium), a peptone and/or protein. or a neutral amino acid which is free of sulphur or a salt thereof.
• the present invention relates generally to a bright tin-nickel plating electrolyte, and more particularly to an aqueous pyrophosphate electroplating bath for obtaining a bright tin-nickel alloy plating.
• An acid fluoride bath- is generally used for achieving a tin-nickel alloy plating, but an electroplated layer formed from such bath is very brittle and is apt to crack when a stress is exerted thereon, for example, due to flexing of the plating substrate.
• a tin-nickel alloy acid bath including a fluoride is disadvantageous in that it requires difficult and expensive treatment of exhaust fumes and of the aqueous bath prior to discharge thereof into the atomsphere and adjacent sewer or waterway, respectively, for avoiding pollution of the environment.
• a tin-nickel alloy plating electrolyte which has, as its main component, an aqueous plating liquid containing a stannous salt, a nickel salt and an alkali-metal pyrophosphate. with the addition thereto, as a brightening agent, of ammonium citrate and/or gelatine, and ot-amino acid such as glycine, or an a-amino acid and a mercaptan derivative.
• aqueous pyrophosphate bath even when containing one or more of the mentioned brightening agents, is incapable of producing a tin-nickel alloy plating of high brightness.
• Another object is to provide a bright tin-nickel alloy plating electrolyte, as aforesaid, which is free of any fluorides so as to minimize the ecological problems resulting from its use.
• a further object is to provide a bright tin-nickel alloy plating electrolyte having, as its main component, an aqueous plating liquid containing stannous and liquid salts and an alkali-metal pyrophosphate, with a bright- "ener additive which results in a plating layer of exvention, with or without the addition may further advantageously contain a compound having SX groups in such electrolyte, in which X represents hydrogen, so-
• the stannous salt maybe present in the main plating liquid in an amount between 2 and calculated calucated as stannous ion; the nickel salt may be present in the main plating liquid in an amount between 5 and 30 g/l., calculated as nickel ion, and the alkali-metal pyrophosphate may be present in the main plating liquid in an amount between 150 and 600 g/l.
• the alkali-metal pyrophosphate of the main plating liquid may be, for example, potassium pyrophosphate or sodium pyrophosphate, while the stannous and nickel salts of such main plating liquid may be respectively stannous pyrophosphate.
• the brightener additive which is essentially added to the main plating liquid and which, in accordance with this invention, contains a plurality of amino groups may be advantageously selected from the group consisting of ethylenediamine, 1,2-propanediamine, 1,3- propanediamine, 1,4-butanediamine, pentamethylenediamine, hexamethylenediamine, hydrazine, guanidine, urea and thiourea.
• the amount of such brightener additive introduced into the main plating liquid is preferably between0.l and g/l. of the main plating liquid.
• the ammonia added to the plating electrolyte may be in the form of 28 percent aqueous ammonia solution in the amount between 5 and 100 g/l. of the main plating liquid.
• ammonium salt such addition may be ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium citrate, ammonium tartrate, ammonium acetate or the like, and is present in an amount between 1.0 and g/l. of the main plating liquid.
• the compound having SX groups in the electrolyte and which may be optionally added to the bright tinnickel alloy plating electrolyte according to this invention may be advantageously selected from among dithioammelide, 4-amino-3,5-dimercapto-l ,2,4-triazole, ethylene thiuram monosulfide, 2,5-dimercapto-1,3,4- thiadiazole, thiocarbohydrazide, hydrazodithiodicarbonamide, ethylenebis-dithiocarbamic acid sodium salt and the like, and is added in an amount between 0.01 and 5 g/l. of the main plating liquid.
• peptone and/or protein When peptone and/or protein is added to the electrolyte, the amount thereof is between 0.1 and 10 g/l. of the main plating liquid.
• the protein thus added may be, for example, glue, gelatine or gluten.
• the peptone and- /or protein is prferably dissolved in water, in an aqueous solution of potassium pyrophosphate or in an alcohol, such as, methanol or ethanol, before being added to the main plating liquid of the electrolyte.
• such additive may be advantageously selected from glycine. alanine, serine. aminobutyric acid, leucine. isoleucine. proline. hydroxyproline, phenylpalanine, thyroxine. tryptophan and the like, and is added in an amount greater than 0.01 mol/l. of the main plating liquid.
• the pH of the plating electrolyte is adjusted to within the range of 8 to 12 with aqueous ammonia solution. caustic potash, pyrophosphoric acid and the like.
• EXAMPLE 1 An aqueous main plating liquid is provided containing 200 g/l. of potassium pyrophosphate. 30 g/l. of stannous pyrophosphate and 50 g/l. of nickel pyrophosphate. Such main plating liquid has added thereto 15 g/l. of ethylenediamine, which is added as an 85 per- EXAMPLES 2,3 and 4 The procedures described above in Example l are repeated, but with the further addition to the main plating liquid of ammonium chloride (Examples'Z and 4) or aqueous ammonia (Example 3) and with the substitution of nickel chloride for the nickel pyrophosphate (Examples 3 and 4), and the results thereof are as shown on Table 1 below.
• Example 1,2,3 and 4 The procedure of Example 1,2,3 and 4 are repeated. but using, in turn, hydrazine, 1.2-propahediamine, 1,3- propanediamine, 1,4-butanediamine; guanidine, urea, thiourea, pentamethylenediamine and hexamethylenediamine. in place of the ethylene diamine, and, in each case, a bright tin-nickle alloy plating similar in appearance to the platings obtained in Examples 1,2,3 and 4 on Table 1 is obtained.
• thiodiazole g/l. 0.5 0.5 0.5 0.5 Dithioammelide g/l. 1 0.5 Hydrazodithiocarbonamide g/l. 1 pH 9 9.5 9.5 r 9 5 Temperature "C 35 35 35 3S Agitation Yes Yes Yes. Yes Yes Current density A/dm 0.5 0.2 0.5 0.5 0.5 Amount of tin contained in deposited alloy 7! 72.1 71.5 73.1 70.1 I 70.3 Appearance Bright Bri ht Bright Bright Bright Bright stainless stain ess stainless stainless stainless color color color color color color with with with with 1 with black black black black black black EXAMPLES 10.11.12.13 and 14 The procedures of Example 1 are repeated.
• Example 1 The procedures of Example 1 are repeated, but with the further addition of a neutral amino acid free of sulphur or a salt thereof, to wit. sodium glycine (Example 18) or alanine (Example 19). and also of aqueous ammonia (Example 19), and the proportions and results tions and results of such further additives are as shown of such further additions are as shown on Table 5 beon Table 3 below.
• Example 15 and 17 The P es of Example 1 are repeated, but with '45 the further addition of peptone (Examples 15 and or demed P ein in the form of glue (Example and also of ammonium chloride (Example 17) and the proportions and results of such additives are as shown black TABLE Continued Examples Reference l8 I9 I pH 9.5 9.5 9.5 Temperature C 35 35 35 Agitation Yes Yes Yes Current density A/dm 0.5 0.5 0.5 Anode carbon carbon carbon Amount of tin contained in deposited alloy 67.4 68.2 84.2 Appearance Bright Bright Grey stainless stainless with no color color brightness REFERENCE 1 In order to demonstrate the essential character of the additive compound having a plurality of amino groups, the procedure of Example 18 was repeated, but with the ethylenediamine being omitted from the plating electrolyte and, as shown on Table 5 above, the resulting plating layer was grey in color and devoid of brightness.
• the present invention produces a bright tin-nickel alloy plating layer with a brightness that cannot be obtained with prior plating electrolytes.
• the brightness of the tin-nickel alloy plating layer is further enhanced by also adding to the electrolyte a compound having one or more -SX groups in this electrolyte (in which X represents hydrogen, sodium or potassium), peptone and/or protein, or a neutral amino acid free of sulphur.
• ammonia or ammonium salt to the plating electrolyte according to this invention is shown to provide the bright plating layer with white color.
• a stannous salt selected from the group consisting of stannous pyrophosphate, stannous chloride and stannous sulfate, and which is present in said main plating liquid in an amount between 2 and 20 g/l. calculated as stannous ion;
• a nickel salt selected from the group consisting of nickel pyrophosphate, nickel chloride and nickel sulfate, and which is present in said main plating liquid in an amount between 5 and 30 g/l. calculated as nickel ion;
• an alkali-metal pyrophosphate selected from the group consisting of potassium pyrophosphate and sodium pyrophosphate, and which is present in said main plating liquid in an amount between 150 and 600 g/l;
• At least one brightener additive in said plating liquid in an amount between 0.1 and 100 g/l. of said main plating liquid and being selected from the group consisting of ethylenediamine, 1,2- 2 propanediamine, 1,3-pr0panediamine, 1,4- butanediamine, pentamethylenediamine, hexamethylenediamine, hydrazine, quanidine, urea and thiourea; and e. a further additive selected from the group consisting of ammonia and ammonium salts, and in which said further additive is present in said main plating liquid in the amount between 5 and 100 g/l. in the case of ammonia calculated as a 28 percent aqueous ammonia solution, and between 1 and 150 g/l. 30 in the case of ammonium salts.
• a stannous salt selected from the group consisting of stannous pyrophosphate, stannous chloride and stannous sulfate, and which is present in said main plating liquid in an amount between 2 and 20 g/l. calculated as stannous ion;
• a nickel salt selected from the group consisting of nickel pyrophosphate, nickel chloride and nickel sulfate, and which is present in said main plating liquid in an amount between 5 and 30 g/l. calculated as nickel ion;
• an alkali-metal pyrophosphate selected from the group consisting of potassium pyrophosphate and sodium pyrophosphate, and which is present in said main plating liquid in an amount between 150 and 600 g/l.;
• At least one brightener additive in said plating liquid in an amount between 0.1 and 100 g/l. of said main plating liquid and being selected from the group consisting of ethylene-diamine, 1,2- propanediamine, l,3-propanediamine, 1,4- butanediamine, pentamethylenediamine, hexamethylenediamine, hydrazine, guanidine, urea and thiourea; and
• a stannous salt selected from the group consisting of stannous pyrophosphate, stannous chloride and stannous sulfate, and which is present in said main plating liquid in an amount between 2 and g/l. calculated as stannous ion;
• a nickel salt selected from the group consisting of nickel pyrophosphate, nickel chloride and nickel sulfate, and which is present in said main plating liquid in an amount between 5 and g/l. calculated as nickel ion;
• an alkali-metal pyrophosphate selected from the group consisting of potassium pyrophosphate and sodium pyrophosphate, and which is present in said main plating liquid in an amount between 150 and 600 g/L;
• At least one brightener additive in said plating liquid in an amount betwen Oil and g/l. of said main plating liquid and being selected from the group consisting of ethylene-diamine, 1,2- propanediamine, 1,3-propanediamine, 1,4- butanediamine, pentamet hylenediamine. hexamethylenediamine, hydrazine, quanidine, urea and thiourea; and
• a stannous salt selected from the group consisting of stannous pyrophosphate, stannous chloride and stannous sulfate, and which is present in said main plating liquid in an amount between 2 and 20 g/l. calculated as stannous ion;
• a nickel salt selected from the group consisting of nickel pyrophosphate, nickel chloride and nickel sulfate, and which is present in said main plating liquid in an amount between 5 and 30 g/l. calculated as nickel ion;
• an alkali-metal pyrophosphate selected from the group consisting of potassium pyrophosphate and sodium pyrophosphate, and which is present in said main plating liquid in an amount between and 600 g/L;
• At least one brightener additive in said plating liquid in an amount between 0.1 and 100 g/l. of said main plating liquid and being selected from the group consisting of ethylene-diamine, 1,2- propanediamine, l,3-propanediamine, l ,4- butanediamine, pentamethylenediamine, hexamethylenediamine, hydrazine, quanidine, urea and thiourea; and e. a substance selected from the group consisting of neutral amino acids which are free of sulphur, and salts thereof, and which is present in said main plating liquid in an amount greater than 0.01 mol/l. 14.

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• 1973
  • 1973-04-19 JP JP4377673A patent/JPS5347060B2/ja not_active Expired
• 1974
  • 1974-04-12 US US460527A patent/US3887444A/en not_active Expired - Lifetime
  • 1974-04-17 GB GB1680174A patent/GB1441542A/en not_active Expired
  • 1974-04-18 CA CA197,770A patent/CA1045075A/en not_active Expired
  • 1974-04-19 DE DE2419024A patent/DE2419024A1/de not_active Withdrawn
  • 1974-04-19 NL NL7405390A patent/NL7405390A/xx not_active Application Discontinuation
  • 1974-04-19 FR FR7413754A patent/FR2226478B1/fr not_active Expired

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