JPS5891181A - Copper-tin alloy plating bath - Google Patents

Abstract

PURPOSE:To make good copper-tin alloy plating having brightness possible by adding thiocyanate and betaine compds. as a brightner to a copper-tin alloy plating bath of copper cyanide-alkali stannate. CONSTITUTION:Thiocyanate and betaine compds. are used as a brightner in combination in a copper-tin alloy plating bath of copper cyanide-alkali stannate. Any thiocyanate soluble in the above-mentioned plating bath is satisfactory and sodium thiocyanate is more particularly preferable. In order to provide the effect of brightening by the addition thereof, addition at about 10-60g/l is preferable. Betaine, trimethyl betaine, etc. are used for the betaine compds., and when said compds. are added at about 0.05-8g/l, the range of usable current density is increased. It is possible to improve the effect of brightening in the high current density part by adding a small amt. of nickel salt or lead salt thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copper-tin gold plating bath;
The purpose is to obtain a shiny steel-tin alloy plating.

Conventional copper bronze-stannate diluka IJ t-copper as main component-
Brighteners used in tin alloy plating baths include tartaric acid,
Organic acids such as citric acid, salicylic acid, etc. - Alcohols such as ethylene glycol, phenol, β-naphthol, hydroxyquinoline, 8-hydroxyquinoline, phenols, amines such as ethylenetriamine, pyridine, quinoline, triethanolamine, etc. Nitrogen compounds, benzenesulfonic acid, P-toluenesulfonic acid, 2.
Benzene sulfonate derivatives such as sodium 7-naphthalenedisulfonate, sulfur heterocyclic compounds such as 2-mercaptobenzthiol, 2-mercaptobenzimidazole, surfactants, and also bismuth, silver, selenium, tellurium, Metallic additives such as antimony are known, but when they are added alone or when -4x is added, they tend to produce a semi-glossy or matte finish, and they also reduce gloss. Even if there were, there were many problems such as a narrow usable current density range, making it difficult to use it industrially.

The present invention is based on the results of dormitory experiments and research conducted in order to improve the above-mentioned problems. Copper-
The object of the present invention is to provide a copper-tin plating bath based on stannic acid and alkali.

The present invention utilizes a copper-tin alkali thermosensor system by adding a thiocyanate and a betaine compound in combination, or by adding a nickel salt or a lead salt to this. By doing so, the objective is to obtain a shiny copper-tin plating bath that can be used industrially.

The thiocyanate referred to here is one that is soluble in a copper-tin alkali plating bath.
, particularly preferably sodium thiocyanate,
Although the use of this thiocyanate alone produces a certain gloss effect, problems such as a narrow usable current density range remain.

However, when used in combination with a betaine additive, the usable current density range is significantly expanded.The present invention has repeatedly conducted Hull cell tests to observe the gloss state, etc. This is what we arrived at after considering the following.

The betaine compound mentioned here includes betaine, trimethylbetaine, trimethyl-C-decyl-d-betaine, and the like.

The amount of thiocyanate added to the bath of the present invention is 10
~60 fi/l is preferred. If it is less than 101/, the gloss effect will not be overshadowed, and if it is less than 60 I
If it exceeds I/1t-, clouding occurs in the high and low current density areas. Most preferably, it is m to 559/l.

The amount of betaine compound added is 0.05 to 811/l
It is preferable that If it is less than 0.05.9/lf, the gloss effect cannot be obtained, and even if it exceeds 811/lf, no increase in the gloss effect can be expected.Most preferably, from 0.08 to
'II/l is preferable.As mentioned above, by adding thiocyanate and betainate adduct together in the m-tin plating bath of the copper-stannic acid and alkali system, industrial A bright copper-tin plating bath is obtained which can be used for the 46 current density area, but if nickel salts or lead salts are added to this bath, the brightening effect is particularly enhanced in the 46 current density area. The current density range is widened.

The nickel salts referred to here include nickel sulfate, nickel chloride, nickel citrate, nickel acetate, nickel potassium cyanide, etc., and the amount added is 20 to 20 tons as a metal salt.
If the addition range of oom/A is less than 7 degrees, the effect will be poor, and even if it is more than 100 m171, no increase in the gloss effect can be expected.

As lead salts, inorganic acid salts such as acetate, lead sulfate, lead nitrate, and lead citrate, and organic acid salts such as phenolsulfonic acid are used. ~12-/L.

The amount of the organic acid salt as a lead salt is 1 to 10 ml. If it is added outside the range, the gloss effect will be unbearable.

Next, regarding the plating conditions of the plating bath of the present invention, the bath temperature is preferably about 45 to 65 DEG C. As the anode, a water-soluble anode is preferable, and air stirring is more effective.

The present invention will be explained in more detail with reference to Examples below.

Example-1 Sodium stannate 1001/ to sodium 28, 51/ to copper 11, 51/ to sodium hydroxide 101/L sodium thiositinate 4097L betaine
31/L Plating bath as above
plating with air agitation using a carbon plate as an anode at a bath temperature of 60C1PH13.5, resulting in a silvery white gloss of 0.5-4A/dfII)11. n large obtained in the fi density range.

Example-2 Sodium stannate 1051/sodium 301/sodium copper
121/L Sodium hydroxide 101/L Sodium thiositate 351/L Betaine
2゜51/ as nickel sulfate (as gold maple salt)
80ml/L A plating bath was prepared as described above, the bath temperature was 55°C, the pH was 13.5, a carbon plate was used as an anode, and plating was performed with air stirring, resulting in a silvery white glossy plating of 0.5%.
A current density range of ~5 μm/ds” was obtained.

As described above, the present invention is an extremely excellent eye bath that has a wide gloss current density range, long-term stability, and uniform gloss, and can be used industrially. .

It goes without saying that the present invention can be practiced not only in various baths, but also in combination with brighteners as appropriate within the scope of the present invention.Applicant Daini Seikosha Co., Ltd. Patent Attorney Mogami

Claims (2)

[Claims] (1) A copper-tin alloy plating bath based on a copper cronide-stannic acid alkali system, characterized by the addition of a thiocyanate and a betaine compound. (2) A copper-tin alloy plating bath characterized in that a thiocyanate, a betaine compound, and a nickel salt or a lead salt are added to the copper-tin alloy plating bath based on a copper-stannate alkali system. .