JPS594518B2 - Copper-sparrow bath - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a copper-tin plating bath, and by adding a special brightening agent to a copper cyanide-stannate alkali plating bath,
The objective is to obtain glossy Cu-Sn alloy plating over a wide range.

Brighteners used in Cu-Sn plating baths containing alkali copper monostannate as the main component include organic acids such as tartaric acid, citric acid, and salicylic acid, ethylene glycol, phenol, β-naphthol, hydroquinone, and 8-naphthol. Alcohols such as hydroxyquinoline, phenols, amines such as ethylene triamine, pyridine, quinoline, triethanolamine, nitrogen compounds, surfactants such as polyoxyalkylphenol ether, polyethylene glycol, benzenesulfonic acid, p −
toluenesulfonic acid, benzenesulfonate derivatives such as sodium 2|7-naphthalenedisulfonate,
Sulfur-containing heterocyclic compounds such as 2-mercaptobenzthiazole and 2-mercaptobenzimidazole, as well as metal compounds such as Pb, Si, Bi, Sb, Be, Te, etc., are known. 10 However, even if these brighteners are added alone or in combination to a copper cyanide-alkali stannate plating bath, semi-gloss or matte Cu-Sn alloy plating can easily be obtained; , due to its narrow gloss range, it is difficult to use it industrially.
It was 5.

This invention provides excellent glossy Cu-Sn under a wide range of plating conditions in a copper cyanide monostannate alkali plating bath.
To provide a brightener that enables alloy plating, that is,
It is an object of the present invention to provide a copper bronze-stannate alkali Cu-Sn plating bath containing such a special brightener.

This invention was developed by selecting various combinations of heel brighteners and repeating a huge amount of experiments. A brightening agent capable of providing alloy plating over a wide range has been discovered, and a new copper cyanide-alkaline stannate Cu-Sn plating bath is provided by adding the required amount of this brightening agent to the plating bath.

30 Therefore, a copper-tin plating bath (hereinafter referred to as a Cu-Sn plating bath) consisting of an aqueous solution containing copper bronze and an alkali stannate as main components, according to the present invention, has an amount of 5 to 80 g/
soluble thiocyanate at a concentration of 20 to 100 liters
y/liter of soluble tartaric acid 35 salt.

According to the Cu-Sn plating bath according to the present invention, a bright Cu-Sn alloy plating can be provided under a wide range of plating conditions, and therefore Cu-Sn plating can be easily performed on an industrial scale.
It becomes possible to perform Sn alloy plating. For this reason, C
There is an advantage that products coated with u-Sn alloy plating can be provided inexpensively and in large quantities. This invention will be explained in more detail.

First, soluble thiocyanate and soluble tartrate are mixed as brighteners in the Cu-Sn plating bath in this invention.

Soluble thiocyanate and tartrate are both copper bronze-
It is well known that thiocyanate or tartrate is used as a brightening agent in alkaline stannate plating baths, but as is clear from Comparative Examples 4 and 6 below, when thiocyanate or tartrate is used alone, the amount added is high. It is also known that it is difficult to use industrially because it tends to form a non-uniform plating film.

However, surprisingly, when soluble thiocyanate and soluble tartrate are used in combination,
Good glossy plating surfaces can be obtained under a wide range of plating conditions, and defects such as partial striped matte areas or uneven color tone in high current density areas that occur when added alone are almost completely eliminated. Furthermore, it has been found that even if the electrolysis time is increased, the aforementioned matte areas or uneven color tone do not expand.

Moreover, it has been discovered that a good plating surface can be obtained with the addition amount of soluble thiocyanate and tartrate being half to less than half of the amount when each is used alone, especially thiocyanate, which is less than 1/10 of the amount added. Therefore, in this invention, the combination of copper cyanide-alkaline stannate aqueous solution, soluble thiocyanate and tartrate is essential, and no matter which component is dropped or replaced,
The effect of this invention cannot be achieved.

The soluble thiocyanate used in this invention may be any thiocyanate as long as it is soluble in a copper bronze-stannate alkali Cu-Sn plating bath, and in particular, an alkali metal salt, preferably potassium thiocyanate. good.

The amount of thiocyanate added to the bath varies depending on the plating conditions, the type of tartrate, and the amount added, but is 5 to 80 f/l.
It is appropriate that

If it is less than 5 f/l, no gloss improvement effect can be obtained, and if it exceeds 80 y/l, clouding occurs in high current density areas regardless of the amount of tartrate.

Most preferably, it is 40 f/l or less. As is clear from Comparative Example 4, which will be described later, when soluble thiocyanate is used alone, the addition amount may be small compared to 50 to 120 f1/l in order to obtain gloss over the entire surface. Next, the tartrate used in this invention is basically not limited as long as it is soluble in the bronze monostannate alkaline plating bath, and in particular, it is an alkali metal salt, preferably sodium potassium L monotartrate. The amount of tartrate added to the bath is suitably 20 to 100 y/l.

If it is less than 20 f/l, clouding occurs in areas where the current density is 15 A/Dm2 or more, and if it exceeds 100 f/l, it becomes semi-glossy or matte with white variations.

As is clear from Comparative Example 6, which will be described later, when tartrate is used alone as a brightener, full gloss can be obtained with an addition amount of 150 to 180 f/l, whereas good results can be obtained with an extremely small amount of addition. is obtained. Although the copper cyanide-alkaline stannate aqueous solution is not fundamentally limited in the present invention, a copper cyanide-sodium stannate aqueous solution is particularly preferred.

Generally, the concentration of alkali copper monostannate varies depending on the properties of the Cu-Sn plating surface, and also varies depending on the amount and type of brightener added. Therefore, it is determined functionally by considering the properties, thickness, etc. of the desired Cu-Sn alloy plating surface, plating conditions, type of brightener, amount added, etc. The amount of copper bronze added varies depending on the amount of alkali stannate added, but generally copper bronze is 10f/11 and alkali stannate is 1
It is desirable to use it at about 00fI/l.

There is no strict limit to the amount of these additions, but if the amount of copper cyanide is too small relative to the amount of alkali stannate, the result will be a grayish-white semi-glossy or matte finish, and if it is too large, a reddish tinge will appear from high current areas. It has a coppery color to it. If the amount of alkali stannate is too small relative to the amount of copper cyanide, a reddish copper color will appear from the high current area, and if it is too large, a grayish-white semi-gloss or matte appearance will occur. However, the ratio between the amount of free cyanide and the amount of Cu ions present in the plating bath is generally 1.6.
It is preferable that it is 2.6.

This is because if it is less than 1.6, the high current density portion will have a reddish plating, and if it exceeds 2.6, it will be a semi-gloss plating.

This free cyanide to Cu ion ratio is, for example, NaCN
It can be adjusted by adding a cyanide ion-releasing substance such as to the bath. In addition to the above components, the Cu-Sn plating bath according to the present invention contains various other components, such as Na
OH, NaCN, etc. can be added. For example, N
When adding aOH to the Cu-Sn bath, free NaO
The amount of H is preferably in the range of 5 to 30 f/l.

This is because if it deviates from this range, it tends to become matte.
Further, when adding NaCN to the Cu-Sn bath, it depends on the amount of copper cyanide added as described above. When plating is performed using the Cu--Sn plating bath according to the present invention, it is preferable to use air agitation with an appropriate strength.

If stirring is not carried out, streaks will appear on the plated surface, and if stirring is too strong, a half-gloss to matte plate with redness will be obtained. Furthermore, the bath temperature of the plating bath is preferably about 35 to 60°C, but if it exceeds 50°C, the plating surface becomes cloudy and reproducibility becomes poor.

Examples of the present invention will be shown below along with comparative examples.

The following examples do not limit the invention. Comparative Example 1 A plating solution consisting of sodium cyanide copper monostannate was prepared, and Fe, Tl, Se, Te, Pb, Sb, Ni, C
O, Cr, Sr, In, Ga, Ba, V, Be, Re,
A Hull cell test was conducted by adding metal compounds containing Cd, MO, Zn, Hg, MN, W, Ag, and Mg in small amounts to nearly 0.5 y/l.

The plating conditions were as shown below. As a result, Ni
It was observed that substances other than the compound had almost no gloss effect, or as the amount added was increased, the gloss effect was lost and the surface became dull and rough. As a result of adding 0.0003 to 0.5 f/l of potassium nickel cyanide as Nl salt, almost no effect was observed in the trace amount range, but 0.04 f/l
A gloss effect was produced in the weaker current area, and as the amount added increased, the gloss area expanded, and when adding 0.5 y/l, almost the entire surface was glossy, and a bluish-white plating surface with a slight darkness was obtained. Ta. Comparative Example 2 Under the same conditions as Comparative Example 1, potassium xanthate, sodium saccharin, thiourea, l-allyl-2-thiourea, thiomalic acid, thiolactic acid, thiosemicarbazide, Sodium diethyldithiocarbamate, thioglycolic acid, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, 2-mercaptobenzoxazole,
Potassium thiocyanate, sodium thiosulfate, benzenesulfonic acid, p-toluenesulfonic acid, p-toluenesulfonamide, p-phenolsulfonic acid, sulfanilic acid, p-N2 sodium dodecylbenzenesulfonate, sodium sulfosalicylate, sodium dioctylsulfosalicylate , disodium benzaldehyde-2-4-disulfonate, disodium 2-naphthol-3,6-disulfonate, 1-naphthol-4-sulfonic acid, disodium 1-nitrone-2-naphthol 3,6-disulfonate, Sodium naphthalene sulfonate, 7-amino-1,3-naphthalenedisulfonic acid, sodium 2,3-dihydroxynaphthalene-6-sulfonate, 2
, 7-naphthalenedisulfonic acid and naphthalene-1,3,6-trisulfonic acid were used alone to conduct a Hull cell test.

Some sulfur compounds were found to exhibit a brightening effect when added alone.

For example, those containing =SO2, -SO3 groups exhibit a brightening effect in a medium to low current density range, those containing -CN, =CN groups exhibit a brightening effect in an even wider current density range, and Gloss, =CS group showed a slight gloss effect in the low current density range.

In addition, the -NH2, Ls, "mi"± group was slightly glossy to semi-glossy. However, these gloss effects became matte from the medium to high current density region with the exception of potassium thiocyanate, and no substance that could be used alone was found. Comparative example
3 Under the same conditions as Comparative Example 1, 1,4-butynediol, sodium citrate, sodium tartrate, monoethanolamine, diethanolamine, pyridine, sodium succinate, sodium gluconate, D,L-malic acid, L-monotartrate Sodium potassium, glycine, hydroxylamine hydrochloride, 8-hydroxyquinoline, tannic acid, dextrin, gelatin, glucose, tetraethylene glycol, "Pluronik F88" (trade name of Asahi Denka Industries), "Quadrol" (trade name of Asahi Denka Industries) ),
A Hull cell test was conducted by adding polyethylene glycol, organic compounds such as "Flet Q" (trade name of NOF Corporation), "Cation PB3OO" (trade name of NOF Corporation), and an activator to the plating bath.

Regarding organic acid salts, except for sodium potassium L monotartrate, almost no effect was observed, and the characteristics due to functional groups were not clear. In addition to sodium potassium monotartrate, amines containing nitrogen atoms, six-membered ring compounds, ethylamine, pyridine, oxine, etc. were effective. As a result of the tests in Comparative Examples 1 to 3, the substances that showed a brightening effect when added alone were sodium thiocyanate, potassium sodium monotartrate, sodium saccharin, thiosemicarbazide, and benzaldehyde 2,4.
-Disodium disulfonate, disodium 1-nitrilo-2-naphthol-3,6-disulfonate, monoethanolamine, diethanolamine, pyridine, oxine, 7-amino-1,3-naphthalenedisulfonic acid, 2
, 3-dihydroxynaphthalene-6-sodium sulfonate, potassium cyanonickel, potassium ferrocyanide, and the like.

These gloss effects are not uniform, and they tend to become semi-gloss or matte plating, and even if they are glossy, they have drawbacks such as a narrow usable current density range, so they can be used practically only by adding them alone. I stopped talking. Comparative Example 4 From the results of Comparative Examples 1 to 3, the results of adding potassium thiocyanate were especially excellent, so under the same conditions as Comparative Example 1, the amount added was varied in the range of 3.5 to 160 f/l, and Hull Cell was added. I conducted a test.

As a result, the gloss effect started to appear at the addition of 15 f/2, and the cathode current density was 2.5 A/L at the addition of 30 f/l.
Other than a slight semi-gloss striped cloudy appearance near Dm2,
Addition of around 100 f/l resulted in almost full gloss, and addition of more than that extended the matte range from the high current density area, but the gloss effect was seen over a wide range.

From this result, it is thought that industrial use is possible to a certain extent even if it is added alone.However, the gloss range is not perfect in these gloss states, and for example, uneven color tone may appear in high current density areas, or 80y/l It has the disadvantage that it is not possible to achieve a full gloss range unless it is added in such a high amount. Comparative Example 5 A Hull cell test was conducted under the plating conditions of Comparative Example 1 using a combination of potassium thiocyanate and the brighteners that exhibited various gloss effects as described in the conclusion section of Comparative Example 3.

As a result, the results of the Hull Cell test using these combinations were all similar, and the expected effects were not obtained, but a synergistic effect was observed only when combined with sodium potassium L monotartrate. Example 1 Sodium stannate 100f/l Sodium cyanide 29f/l Cuprous cyanide
A plating bath containing 10 f of 12 f/l sodium hydroxide was prepared, and a Hull cell test was conducted under the conditions of a bath temperature of 40° C., a total current of 4 A, and air agitation.

Add potassium thiocyanate alone to the above bath at 20 to 240
When plating was performed by adding f/l, the entire surface became glossy at an addition amount of 80 g/l, but a reddish tinge appeared in the high current density area, and the redness became wider as the addition amount increased. Ivy.
Next, add 20 L sodium potassium monotartrate to the above bath.
When ~160 f/l was added alone and plating was performed, the entire surface became glossy at 80 to 140 y/l, and clouding occurred in low or high current density areas even if the amount was higher or lower than that.

Next, add 20f1/potassium thiocyanate to the above bath.
Add 11 and further add 20 L sodium potassium monotartrate.
~809/l was added and plating was performed.

When the amount of sodium potassium monotartrate added was 20 f/l, clouding occurred at a current density of 15 A/Dm2 or more, but when other additions were made, the entire surface became glossy and no reddish tinge appeared. When potassium thiocyanate is 40 f/l or more, regardless of the amount of potassium sodium monotartrate,
Cloudiness spread to the high current section.

From this result, the amount of potassium thiocyanate added is 5 to 3
0y/l is sufficient, and L sodium monotartrate is 40-100
I found out that f/l is fine. Comparative Example 6 A Hull cell test was conducted under the plating conditions of Comparative Example 1, varying the amount of sodium potassium L monotartrate in the range of 2 to 2009/l.

As a result, when 20 f/l was added, a glossy area appeared from the high and low current density areas, and when 150 f/l was added, almost the entire surface became glossy.

At 200 f/l, it was observed that the high current density portion became a gray-black rough surface.

As a result, when sodium potassium monotartrate is added alone, the color tone tends to be uneven in the high current area, and full gloss cannot be obtained, and full gloss cannot be obtained unless the addition amount is as high as 1009/l. I understood.

Example 2 Sodium stannate 100f/l Sodium cyanide 31f/l (Free cyanide amount 19y/l) Cuprous cyanide 13f/l Sodium hydroxide 10f/l (Free sodium hydroxide amount 17.5f/l) Thiocyanic acid Potassium: 20 f/1 L Sodium monotartrate Potassium: 80 f/L A cathode current density of 4 A/L was applied to the nickel plated plate under conditions of a bath temperature of 60°C and air agitation in a Cu-Sn plating bath consisting of potassium monotartrate and potassium 80 f/l.
Plating was carried out at Dm2 for 5 minutes.

When the air agitation was too strong, a reddish semi-gloss or matte plating was obtained, but as the agitation was weakened, a glossy plating was obtained and a steady state was reached. Without stirring, streaks were generated. Example 3 Plating was carried out using the same bath composition as in Example 2 and under the same conditions as in Example 2.

At that time, only the amount of free sodium cyanide was adjusted to O~24f/
When the surface was changed to less than 10 y/l, the surface became a yellow to brown matte surface, and when it was 20 y/l or more, the surface became grayish-white, semi-glossy or matte. Free cyanide content is 12-20
A glossy plating was obtained at f/l. Example 4 Plating was carried out with the same bath composition and the same plating conditions as in Example 2, with only the amount of free sodium hydroxide being changed from 7.5 to 27.5 f/l. Gloss was obtained, and mattness was obtained with more or less than this.

Example 5 With the bath composition and plating conditions of Example 2, the bath temperature was set to 35 to 55.
When the temperature was changed to higher than 45°C, the reproducibility was poor, such as clouding in some parts, but at around 45°C, a uniform glossy surface with good reproducibility was obtained, although the gloss range became slightly narrower.

Example 6 With the bath composition and plating conditions of Example 2, the Sn used for the anode was
When electrolyzed at a current density of 1.2A/Dm2,
An anode film was not formed on the anode surface but dissolved, and Sn++ was increased in the plating solution, resulting in a gray, matte surface.

In this state, when a small amount of hydrogen peroxide was added, the glossy surface changed, but after a while, it became matte plating again. When the anode current density was increased to 3 A/Dm2, the Sn anode dissolved while forming a film, and the glossy surface was maintained.

Example 7 Under the bath composition plating conditions of Example 2, a glossy surface was obtained when the ratio of free cyanide to copper ion content in the bath was between 1.6 and 2.6, but when it exceeded 2.6, a semi-gloss surface was obtained. Metsuki and 1 again
．． When it was less than 6, the plating had a reddish tint in the high current density area.

Claims (1)

Claims: 1. It is characterized by containing soluble thiocyanate in a concentration of 15 to 80 g/liter and soluble tartrate in a concentration of 20 to 100 g/liter. A copper-tin plating bath consisting of an aqueous solution whose main components are copper cyanide and alkali stannate.