DE1260916B - Acid galvanic tin-nickel bath - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

C23b

German class: 48 a - 5/38

Number: 1260 916

File number: M 73348 VI b / 48 a

Filing date: June 16, 1961

Open date: February 8, 1968

The invention relates to aqueous acidic tin-nickel electroplating baths, from which high-gloss tin-nickel alloy deposits of relatively great thickness are deposited.

Electroplating baths for the deposition of tin— Nickel have excellent throwing power. Although the deposits generated from technical baths are well usable, but the precipitates are not as bright and shiny as they are for most decorative applications is desirable. Only those deposits that are on a shiny surface deposited in thicknesses less than 6 microns still appear shiny. Essentially is this precipitate transparent. If the thickness is greater than 6 microns, the precipitate is light white to cloudy fog, which increases with increasing thickness. It is desirable to have a bare, To obtain glittering, especially high-gloss, precipitation and precipitation thicknesses over 6 microns.

It has been found that such bright, in particular high-gloss, galvanically produced tin-nickel deposits are obtained when aqueous acidic baths are used as brighteners contain l- (p-aminophenyl) -3-methylpyrazole.

Adding brighteners to galvanic baths is known in principle. A predominant part of this Brightener consists of organic chemical compounds. In individual cases there were also more or Less shiny-looking precipitates were achieved, but they were not bare in the optical sense and above all not high-gloss or shiny.

Tin - Nickel is made from acidic, mainly chlorides and / or fluoride-containing baths deposited in which 26 to 37.5 g / l tin and 60 to 82.5 g / l nickel are contained. The total amount of fluoride in the baths according to the invention is between 34 and 45 g / l. The tin concentration increases during the working process. It should at the same time the amount of fluoride can be increased so that it is at least equal to the total amount of tin in the bath. The chloride content is not critical. The pH is generally increased by adding Ammonium hydroxide or hydrofluoric acid kept between 2 and 3.5. The baths can also be a suitable one Contains agents to prevent scarring. Such agents are sulfonated cyclic fluorocarbons, z. B. Perfluoro-4-methylcyclohexylsulfonic acid, Perfluorocyclohexylsulfonic acid, perfluoro-2-methylcyclohexylsulfonic acid, perfluoro-1-methylcyclohexylsulfonic acid, Perfluor - 2,5 - dimethylcyclo-acid galvanic tin-nickel bath

Applicant:

M&T Chemicals Inc., New York, N.Y. (V. St. A, j.

Representative:

Dr.-Ing. H. Fincke, Dipl.-Ing. H. Bohr

and Dipl.-Ing. S. Staeger, Patent Attorneys ,. .

800Ö Munich 5, Müllerstr. 31

Named as inventor:

Edgar J. Seyb Jr., Oak Park, Mich .;

Augustine J. Wallace Jr.,

East Detroit, Mich. (V. St. A.)

Claimed priority:

V. St. v. America June 17, 1960 (36 750) - -

L.

hexylsulfonic acid, perfluoro - 4 - ethylcyclohexylsulfonic acid and the salts of these acids. The bath is operated at high temperatures, preferably 65-71 ⁰ C.

The tin-nickel layers galvanically deposited from the well-known standard baths can be used as matt gloss, d. H. not absolutely blank, denote, since the precipitate is whitishly fogged Has appearance. It is by no means glossy. Bare and high-gloss or glittering precipitates is obtained from conventional aqueous-acidic baths which, according to the invention, are l- (p-aminophenyi) -3-methylpyrazole as brighteners contain. Even the first layer of precipitation on shiny or matt base metals is already pretty shiny and shiny. As the electrodeposition proceeds, it assumes Gloss and finally results in a high-gloss, blank deposit.

The content of l- (p-aminophenyl) -3-methylpyrazole in the galvanic baths is in the range between 0.05 and 1 g / l, preferably between 0.2 and 0.5 g / l.

At above the specifically preferred maximum

If the concentration is low, the precipitate tends to ^{become brittle at high current densities above about 7.5 Amp./dm 2} , the brittleness can become so great that cracks and easy flaking

809 507/542

Claims (1)

3 4 occur, whereby the current density range became substantially smooth brass plate 10 minutes with a is reduced. average current density of 2.7 amps / dm ² _o . .... galvanized. The tin-nickel precipitate was over Standard bath *? · ™ ^ t t i »j ,,.,. "" The whole record high gloss. Stannous chloride 49 g / l - ^to Nickel chloride (NiCl ₂ · 6 H ₂ O) 300 g / l. Example 2 Ammonium bifluoride (NH ₄ HF ₂ ) 56 g / l The compound 1- (p-aminophenyl) -3-methylpyrazole Ammomumhydroxyd around the pH was the standard tin-nickel approach in one Bring value to 2.0 to 2.5. Hull cell added in an amount of 0.1 g / l. One l temperature 68 C ₁₀ ^ ₆ brass plate was 10 minutes at a The baths in the following examples have an average current density of 2.7 amps / dm ² Tin-nickel deposits in the ratio of about galvanized. The tin-nickel precipitate was over 65 ° / ₀ tin to 35% nickel under the specified the whole plate mirror finish. Conditions electrodeposited. '"" "*'" "" * ' All samples were treated with the standard bath galva.
nized. The electroplating was done in a Hull cell, those in "The Metal Finishing Guidebook," 27; Edition 1. Acid, galvanic tin-nickel bath for (1959), pp. 645 to 648. Deposition of shiny coatings, thereby In this process, the current density changed, characterized in that it was 0.05 to lg / 1, along the length of the metal strip, so that the 20 especially 0.2 to 0.5 g / l, l- (p-aminophenyl) - Appearance of a precipitate over a stream containing 3-methylpyrazole. Density range from about 0.5 to 8 Amp./dm ² below 2. Electroplating method could be searched for. of shiny tin-nickel alloy coatings . ■ 1 1 using a bath according to claim 1, Example! ₂₅ characterized in that with a pH The compound l- (p-aminophenyl) -3-methylpyrazole from 2 to 3.5 and a bath temperature of 65 was the standard tin-nickel approach in one to 71 ° C with a current density of about Hull cell was added in the amount of 0.5 g / l. A 2.7 amp./dm ^{2 is} worked. 809 507/542 1.68 ® Bundesdruckerei Berlin