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

Definitions

• a preferred aspect of this invention lies in the electrodeposition of tin-lead alloys in the presence of a combination of:
• This invention relates to the electrodeposition of an alloy of tin and lead; plating compositions; plating baths for the electrodeposition of an alloy of tin and lead, and to processes for the electrodeposition of an alloy of tin and lead in the presence of a specific combination of additives. More specifically this invention provides as a novel combination of additives for electrodepositing an alloy having about 60% tin and about 40% lead from baths containing a water soluble stannous salt and a water soluble lead salt, at least one polyether surfactant, and at least one aromatic aldehyde exhibiting at least one chloro substituent or at least one compound producing an aromatic aldehyde exhibiting at least one chloro substituent.
• solder-plate tin-lead alloy containing about 60% tin and about 40% lead by weight, commonly known as solder-plate, obtained by electrodeposition from a stannous fluoboratelead fluoborate system, has had extensive application for many years. Some of its applications have been the following:
• the alloy has been generally plated from a fiuoborate system utilizing certain additives, usually of organic nature such as peptones and animal glue, to give continuity of deposit, to refine the crystalline structure, and to eliminate the tendency toward loosely adherent, dendritic deposit growth.
• certain additives usually of organic nature such as peptones and animal glue
• the prior art deposits have been generally dull with a dark cast.
• the low current density coverage and throwing power also have been Patented July 31, 1973 generally poor which may be a serious disadvantage particularly in printed circuitry through-hole plating.
• Another disadvantage of prior art deposits has been tendency toward staining, finger-marking on handling, and decreased solderability on storage.
• This invention relates to a process of producing lustrous, continuous, ductile, fine-grained tin-lead alloy electrodeposits which comprises passing current from an anode to a metal cathode through an aqueous bath composition containing at least one water soluble stannous salt, at least one water soluble lead salt, fiuo'boric acid, boric acid, at least one polyether surfactant, and at least one aromatic aldehyde exhibiting at least one chloro substituent or at least one compound producing an aromatic aldehyde exhibiting at least one chloro substituent.
• compositions and methods herein are applicable to barrel, rack and wire electroplating processes.
• concentrations of tin and lead may be varied generally within the limits conventional in this art.
• baths with a stannous tin ion content of 5 to 55 g./l. and a lead ion content of 20 to 30 g./l. may be utilized with the additives of the invention herein.
• Type A polyether surfactants operable in the practice of this invention are polyether surfactants which may include aromatic polyethers and aliphatic polyethers.
• the wetting agent is a polyalkoxylated alkyl phenol.
• Typical polyalkoxylated alkyl phenols include polyethoxylated alkyl phenols having the formulae:
• R represents an alkyl group of from 4 to 18 carbon atoms
• R is an aliphatic radical containing 8 to 20 carbon atoms
• m is an integer of at least 4 and no more than 100
• X is selected from the group consisting of hydrogen, $0 M, and PO M where M is selected from the group consisting of sodium, potassium, ammonium, magnesium, lead, tin, calcium, rubidium, cesium, or any other bath-compatible cation.
• R R R and R represent a straight or branched chain alkyl group exhibiting 8 to 18 carbon atoms
• n is an integer of at least 4 and no more than 100
• X is selected from the group consisting of hydrogen, $0 M, P0 M where M is selected from the group consisting of sodium, potassium, ammonium, magnesium, lead, tin, calcium, rubidium, cesium, or any other bath-compatible cation.
• Polyether surfactants are employed singly in amounts of about 1 g./l. to 10 g./l., and in combination from 10 g./l. to 20 g./l.
• Typical specific compounds are the following with their concentration ranges varying singly from 1 g./l. to 10 g./l. and in combination from 10 g./l. to 20 g./l.:
• Nonyl O (CHzCH2 )l5H (sold as Tergitol Non-Ionic NP-35) l i R:
• CHO o-Chlorobenzaldehyda (a preferred compound because of its cost being relatively low and its easy availability) CHO Cl- 01 2,d-diehlorobenzaldehyde CHO -Cl 2,4-diel1lorobenzaldehyde 01 3,4-dlchlorobenzaldehydo C1 m-Chlorobenzaldehyde
• Compounds which are effective due to the release of a chlorinated aromatic aldehyde on being added to the plating bath are the following structural configurations:
• R is an aromatic moiety such as phenyl containing 1 or 2 chloro groups directly bonded to the aromatic ring.
• Compounds of Type B may be used in the form of stock solutions in appropriate organic solvents (methanol, ethanol, isopropanol, acetone, etc.) or in mixtures of organic solvents (such as methanol plus water plus compounds of Type A, the latter imparting appreciable solubilizing action).
• appropriate organic solvents methanol, ethanol, isopropanol, acetone, etc.
• mixtures of organic solvents such as methanol plus water plus compounds of Type A, the latter imparting appreciable solubilizing action.
• this invention relates to an electroplating bath for the electrodeposition of an alloy of tin and lead containing a water soluble stannous salt, a water soluble lead salt, and containing as cooperating additives:
• At least one aliphatic amine or a compound producing an aliphatic amine At least one aliphatic amine or a compound producing an aliphatic amine.
• Type C compounds which are aliphatic amines or compounds which liberate aliphatic amines on addition to the electroplating bath are of the formulae:
• the aliphatic amine or aliphatic amine producing compounds are used in concentrations ranging from 0.25 g./l. to 5 g./l. depending on their degree of bath solubility. They may be used in the form of aqueous or organic solvent stock solutions or in mixtures of water and organic solvents.
• a plating bath of the fluoborate type which may be used in the practice of this invention may consist of the following basic ingredients:
• stannous fluoborate Sn(BF lead fluoborate [Pb(BF fluoboric acid [HBF boric acid [H BO
• the stannous fluoborate is usually added as an aqueous concentrate containing typically 49.6% by weight of Sn(BF having a specific gravity of 1.60.
• the lead fluoborate is usually added as an aqueous concentrate containing typically 50% by weight of Pb(BF having a Range, g./l. Preferred, g./l.
• Anodes generally consist of a cast or extruded tinlead alloy containing 60% tin and 40% lead. In order to more consistently obtain an alloy composition at the cathode close to 6040, the following operating conditions are generally used:
• Increasing the cathode current density over 3.0 a.s.d. will tend to increase the tin content of the deposit while decreasing the cathode current density below 3.0 a.s.d. will tend to decrease the tin content of the deposit.
• a tin content of 60:10% by weight and a lead content of 40- :10% by weight are generally acceptable and this means that some variation in tin and lead concentrations and in cathode current density may be tolerated.
• This invention also lies in the adddition of an anti oxidant or oxygen acceptor for substantially decreased tendency toward formation of precipitates of stannic basic salts.
• Operable anti-oxidants or oxygen acceptors include hydroquinone or substituted hydroquinone, pyrocatechol, pyrogallol, catechol, and aromatic sulfinates such as sodium benzene monosulfinate.
• These compounds may be used singly or in combination in concentrations of about 0.5 g./l. to 5 g./l. depending on their bath solubility. They may be used in the form of aqueous or organic solvent stock solutions or they may be added directly to the plating bath with stirring to facilitate solution.
• this invention is an aqueous solution for electrodepositing a bright, sound, smooth ductile alloy of tin and lead having about 60% tin and 40% lead comprising: 110 g./l. to 135 g./l. of stannous fluoborate; 37 g./l. to 55 g./l. of lead fluoborate; 100' g./l. to 200 g./l. of fluoboric acid; 10 g./l. to 40 g./l. of boric acid; and as a novel additive system:
• R is an aliphatic alcohol moiety R'O-- where R is an aliphatic radical containing 4 to 18 carbon atoms or an aromatic alcohol moiety where R" is an aliphatic radical containing 8 to 20 carbon atoms;
• R is a branched or straight chain aliphatic group having 8 to 18 carbon atoms
• n is an integer of 4 to 100
• X is hydrogen, $0 M, or PO M
• M is hydrogen or a bath-compatible cation such as Na, K, N-H Mg, Pb Sn Ca Cs, or Rb;
• the preferred operating conditions such as pH, temperature, and current density may vary depending upon the particular bath composition and the nature of the article receiving the layer of tin-lead alloy electrodeposit. In general, good tin-lead alloy electrodeposits may be obtained within a specific range of operating conditions.
• the tin-lead alloy electroplating processes using the compositions of the invention may be carried out at temperatures of about 10 C.-60 C. (preferably 15 C.-20 C.) either with or without agitation.
• the temperature of the plating solution is usually the ambient temperature, say 35 C. or below, with lower temperatures giving optimum results, such as 15 C.20 C.
• tin-lead alloy electrodeposits having average thicknesses of 0.25-25 microns may be obtained using plating times which may average 0.1- minutes.
• the parts may be plated on racks, i.e. on fixtures holding single or multiple parts which may all be the same or which may be different in size, geometrical configuration, etc.
• Parts may also be plated in bulk in rotating barrels and in this type of plating, usually used for plating of smaller parts which lend themselves to tumbling action, the barrel loads usually consist of the same part although mixed loads are sometimes plated.
• the plating bath be so formulated as to provide the widest possible bright plate current density range.
• the limiting current density i.e. the current density at which the deposit ceases to be sound in structure and appearance, be as high as possible to allow for the wide variations in cathode current density which may be encountered due to the size and shape complexity of parts.
• Anode slab of Sn-Pb alloy (60% Sn and 40% Pb by weight)
• Cathode polished brass 10 cm. x 7.5 cm. x 1 mm. with 5 cm. immersed Cell current: 1 ampere (0 to 7 a.s.d. range)
• Anode slab of Sn-Pb cast alloy (60% Sn and 40% 'Pb by weight) 9 cm. wide, 1 cm. thick, 20.5 cm. immersed in plating bath
• Cathode polished brass 20.4 cm. long, 2.54 cm. wide, 0.5 mm. thick immersed to depth of 18 cm.maintained parallel to the anode at a distance of about 10 cm.- bottom of cathode bent to give an internal angle of 45 facing anode Agitation: moving cathode bar-length of stroke 8 cm.
• Solution volume 4 liters-cooled to compensate for heating effects of current by immersing in solution plastic cooling coils through which cold water circulated to maintain temperature at about 25 C.
• Cell polyethylene plastic Load: steel nails about 5 cm. long with a total load area of about 930 square cm.
• G./l. Stannous tin 52 Lead 30 Free fiuoboric acid 100 Boric acid 25 To 267 ml. of the above stock solution, there were added the equivalent of G./l. Tergitol Non-Ionic NP-35 l0 Triton QS-IS l0 o-Chlorbenzaldehyde 0.4
• Example 1 was repeated using 0.4 g./l. of 2,6-dichlorobenzaldehyde in place of the o-chlorobenzaldehyde with essentially the same results obtained.
• Example 1 was repeated using 0.4 g./l. of mi-chlorobenzaldehyde in place of the o-chlorobenzaldehyde with essentially the same results obtained.
• EXAMPLE 4 A barrel plating test was run using the barrel plating conditions outlined in the above and using a cell current of amperes for 30 minutes to give an average cathode current density of about 2 a.s.d. After plating the load of nails was rinsed and dried, and they had a beautifully lustrous and uniform appearance. On testing representative nails from the load the deposit ductility and adhesion to the basis metal was excellent. Because of the tumbling and some burnishing action no indication was 0btained of any of the striation or ribbing effect indicated by the Hull Cell tests of Examples 1 to 3, inclusive.
• the life test was continued for a total electrolysis time of about 300 ampere-hours with variations of current from 5 to 25 amperes per load and with times ranging from 15 minutes to 1 hour. Periodic replenishment of o-chlorobenzaldehyde easily maintained deposit luster with replenishment additions made on the basis of deposit appearance. Solderability tests were made on representative samples from a number of loads and the Solderability was found to be excellent.
• Example 5 was repeated using 2 g./l. octylamine in place of the laurylamine, with the same results obtained.
• a brass cathode was plated for 15 minutes at 3 amperes to give an average cathode current density of about 3 a.s.d.
• the deposit was uniformly lustrous, ductile, and free of striations or ribbing.
• the deposit also exhibited a remarkable degree of leveling as evidenced by the degree of obliteration of basis metal defects (pits, minor scratches, etc.) and the extraordinary smoothening of the rough sheared edges of the cathode.
• EXAMPLE 8 The Life Test of Example 7 was repeated using a freshly prepared bath but in addition adding as an anti-oxidant 1.5 g./l. hydroquinone. Excellent results were obtained as in Example 7 but after an electrolysis time of well over ampere-hours the solution remained perfectly clear and free of any opalescence or any precipitate.
• Example 9 The Life Test of Example 7 was repeated using a freshly prepared bath but in addition adding as an antioxidant 0.2 g./l. of sodium benzene monosulfinate. Excellent results were obtained as in Example 7 but after an electrolysis time of well over 100 ampere-hours the solution remained perfectly clear and free of any opalescence or any precipitate.
• a process for electrodepositing a bright, sound, smooth, ductile alloy of tin and lead which comprises passing current from an anode to a cathode through an aqueous acidic bath containing at least one water soluble stannous tin salt, at least one water soluble lead salt, and as cooperating additives:
• a process for electrodepositing a bright, sound, smooth, ductile alloy of tin and lead which comprises passing current from an anode to a cathode through an aqueous acidic bath containing at least one Water soluble stannous tin salt, at least one water soluble lead salt, and as cooperating additives:
• a process for electrodepositing a bright, sound, smooth, ductile alloy of tin and lead which comprises passing current from an anode to a cathode through an aqueous acidic bath containing at least one water soluble stannous tin salt, at least one water soluble lead salt, and as cooperating additives:
• At least one polyether surfactant is of the formula where R is an alkyl group of 8 to 20 carbon atoms, n is an integer 4 to 100, and X is selected from the group 10 consisting of hydrogen, $0 M, and PO M where M is hydrogen or a bath-compatible cation comprising Na, K, NH4, Mg, Pbz, S112, C32, CS, 01' Rb.
• At least one surfactant is a nonylphenol-ethylene oxide condensate exhibiting about 15 ethylene oxide groups per molecule.
• At least one polyether surfactant is of the formula wherein R is a branched or straight chain aliphatic radical containing 4 to 18 carbon atoms, n is an integer 4 to 100, and X is selected from the group consisting of hydrogen, $0 M, and PO M where M is hydrogen or a bath-compatible cation comprising Na, K, NH Mg, Pbg, Sn Ca Cs, or Rb.
• At least one polyether surfactant is of the formula where R" is a branched or straight chain aliphatic group of 8 to 18 carbon atoms, n is an integer 4 to 100, and X is selected from the group consisting of hydrogen, SO M, and PO M where M is hydrogen or a bath-compatible cation comprising Na, K, NH Mg, Pb Sn Ca Cs, or Rb.
• said polyether surfactant is of the formula R1 Rro-Nmo monsoma 1' where R R and R each exhibit 12 to 14 carbon atoms and n is about 15.
• a process for electrodepositing a bright, sound, smooth, ductile alloy of tin and lead which comprises passing current from an anode to a cathode through an aqueous acidic bath containing at least one water soluble stannous tin salt, at least one Water soluble lead salt, and as cooperating additives:
• a process for electrodepositing a bright, sound, smooth, ductile alloy of tin and lead having about 60% tin and about 40% lead comprising passing current from an anode to a cathode through an aqueous acidic bath containing 110 g./l. to 135 g./l. of stannous fiuoborate; 37 g./l. to 55 g./l. of lead fiuoborate; 100 g,/l. to 290 g./l. of fluoboric acid; 10 g./l. to 40 g./l. of boric acid; and as a novel additive system:
• NH(CH2CHZO)n X where R is a branched or straight chain aliphatic group having 8 to 18 carbon atoms, n is an integer of 4 to 100, and X is hydrogen, M, or PO M where M is hydrogen or a bath-compatible cation comprising Na, K, NH Mg, Pb Sn Ca Cs, or Rb;
• n 1 or 2;
• a composition for producing bright, sound, smooth, ductile tin-lead alloy electrodeposits which comprises an aqueous acidic bath composition containing at least one water soluble stannous tin salt, at least one water soluble lead salt, and as cooperating additives:
• ductile tin-lead alloy electrodeposits which comprises an aqueous acidic bath composition containing at least one water soluble stannous tin salt, at least one water soluble lead salt, and as cooperating additives:
• a composition for producing bright, sound, smooth, ductile tin-lead alloy electrodeposits which comprises an aqueous plating bath containing at least one water soluble stannous tin salt, at least one water soluble lead salt, and as cooperating additives:
• composition of claim 25 wherein said aromatic aldehyde produced is of the formula CHO where n is l to 2.
• composition of claim 26 wherein at least one surfactant is a nonylphenol-ethylene oxide condensate exhibiting about 15 ethylene oxide groups per molecule.
• composition of claim 28 wherein said polyether surfactant is of the formula R1 Rg+NH(CgH40), S OaNa Rs wherein R R and R each exhibit 12 to 14 carbon atoms and n is about 15.
• composition of claim 25 wherein at least one polyether surfactant is of the formula wherein R is a branched or straight chain aliphatic radical containing 4 to 1-8 carbon atoms, n is an integer 4 to 100, and X is selected from the group consisting of hydrogen, $0 M, and PO M where M is hydrogen or a bath-compatible cation comprising Na, K, NH Mg, Pb ,Sn Ca Cs, or Rb.
• composition of claim 25 wherein at least one polyether surfactant is of the formula wherein R is an alkyl group of 8 to 20 carbon atoms, n is an integer 4 to 100, and X is selected from the 3 group consisting of hydrogen, 80 M, and P M where M is hydrogen or a bath-compatible cation comprising Na, K, NH4, Mg, Pbg, Sbg, C32, CS, or Rb.
• composition of claim 26 wherein at least one polyether surfactant is of the formula where R is a branched or straight chain aliphatic group of 8 to 18 carbon atoms, n is an integer 4 to 100, and X is selected from the group consisting of hydrogen, $0 M, and PO M where M is hydrogen or a bath-compatible cation comprising Na, K, NH Mg, Pb Sn Ca Cs, or Rb.
• composition of claim 25 wherein said tin-lead alloy is about 60% tin and about 40% lead.
• composition of claim 25 wherein said aliphatic amine is laurylamine.
• composition of claim 25 wherein said aliphatic amine is octylamine.
• a composition for producing bright, sound, smooth, ductile tin-lead alloy electrodeposits which comprises an aqueous acidic plating bath containing at least one water soluble stannous tin salt, at least one water soluble lead salt, and as cooperating additives:
• composition of claim 37 wherein said antioxidant compound is an aromatic sulfinate.
• composition of claim 38 wherein said aromatic sulfinate is sodium benzene monosulfinate.
• composition of claim 37 wherein said antioxidant compound is hydroquinone or substituted hydroquinone.
• composition of claim 37 wherein said antioxidant compound is pyrocatechol.
• composition of claim 37 wherein said antioxidant compound is catechol.
• composition of claim 37 wherein said antioxidant compound is pyrogallol.
• R is an aliphatic alcohol moiety R'O- where R is an aliphatic radical containing 4 to 18 carbon atoms or an aromatic alcohol moiety where R" is an aliphatic radical containing 8 to 20 carbon atoms;
• R is a branched or straight chain aliphatic group having 8 to 18 carbon atoms, n is an integer of 4 to 100, and X is hydrogen, $0 M, or PO M where M is hydrogen or a bath compatible cation comprising Na, K, NH Mg, Pb Sn Ca Cs, or Rb;

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• 1971
  • 1971-12-16 US US00208885A patent/US3749649A/en not_active Expired - Lifetime
• 1972
  • 1972-11-20 DE DE2256845A patent/DE2256845A1/de not_active Ceased
  • 1972-11-22 CA CA157,164A patent/CA1115654A/en not_active Expired
  • 1972-11-27 FR FR7242053A patent/FR2163453B1/fr not_active Expired
  • 1972-12-11 GB GB5712372A patent/GB1408148A/en not_active Expired
  • 1972-12-15 IT IT9792/72A patent/IT970627B/it active
  • 1972-12-15 NL NL7217115A patent/NL7217115A/xx not_active Application Discontinuation
  • 1972-12-16 JP JP12667572A patent/JPS5629758B2/ja not_active Expired

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