DE2231988A1 - METHOD OF ELECTRICAL DEPOSITION OF TIN - Google Patents

Description

PATENT LAWYERS

DR.-I NG. H, FINCKE DIPL.-ING. H. BOHR DIPL.-ING. S. STAEGER

Telephone: "26 6060

8 MUNICH S, Müllerstraee 31

June 29, 1972

Folder 22908 - Dr. Case 912

M& T Chemicals Inc.
New York, NY. _$ USA

Process for galvanic deposition of tin

Priority: 1. 7 · 197 * 1 - U.S.A.

During the past 10 to 15 years there has been growing commercial interest in the electrodeposition of shiny tin from acidic electrolytes. These deposits have found many uses in electronics and other fields to produce articles with improved appearance, solderability, and stain resistance. It is

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A number of organic adjunct systems have already been developed to achieve these or other benefits * but have not yet been completely satisfactory. Some of the disadvantages are inadequate or uneven gloss »cathode current density ranges that produce too narrow, shiny deposits and difficult control of bath compositions to achieve uniform operation under technical coating conditions both in the drum and on the hanging rail« Other disadvantages are limited solubility of some of the brightening additives, which lead to tar-like deposits that adversely affect the electrodeposited deposits, as well as uncertainty in the composition and reproducibility of such deposits during production, often resulting in complicated mixtures with unknown reaction products *

An object of the invention is to provide a new bright tin system for acidic baths, in which a uniform compound is contained as the primary shimmer, whereby a considerable Improvement in work behavior compared to known systems is achieved.

Another object of the invention is to provide improved Baths or solutions for the production of tin coatings with an improved gloss. Another goal The invention is the creation of a new primary gloss for acidic gloss baths.

According to the invention, an acidic solution for the Electro-deposition of shiny well-leveled tin is proposed, which includes:

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(a) 10 to 100 g / l tin (II) sulfate;

(b) 20 to 200 g / l sulfuric acid j

(c) Ο »025 to 0.5 g / L icy aorylsurej

(d) 1 to 50 g / l of a non-ionic water-soluble alkoxylated wetting agent; and

(e) as primary shimmer 0.005 to *% ο g / l des' Reaction product from hexane ~ 2,5-dione and one of the following compounds j. '

(1) A-OHO where A is a 5-membered heterocyclic ring or a 6-membered homocyclic ring Hing stands ;, and

(2) Compounds with condensed aromatic Rings that have at least one aldehyde substituent contain.

According to the invention there is also a method of manufacture of shiny, heavily leveled, galvanic tin " Abacheidungen proposed, which is carried out by moving from an anode to a metal cathode through a aqueous acidic bath composition passing a stream, the at least one Zinu (II) compound that supplies divalent tin ions for electrodeposition, ice-like acrylic acid, at least one non-ionic water-soluble alkoxylated wetting agent and the reaction product of hexane-2,5-dione and contains one of the following compounds: 5-membered heterocyclic ring aldehydes, 6-membered homocyclic Ring aldehydes and compounds with fused aromatic rings that carry aldehyde groups.

20ΠΒ β 3/1184

The invention is applicable to a wide variety of conventional acidic tin baths, such as baths containing divalent tin salts, e.g. stannous sulphate, and an acid ν e.g. sulfuric acid :. Furthermore, the compositions and methods described herein can be applied to electrodeposition both in the drum and on the hanging rail. The concentrations of the tin and the free acid can be varied within the usual wide limits. For example, baths with a tin content of 10 to 100 g / l and a free acid concentration of 20 to 200 g / l can be used with the additives according to the invention "."

The preparation of the reaction product from hexane-2,5-dione and an aldehyde selected from 5-membered heterocyclic ring aldehydes, 6-membered homocyclic ring aldehydes or compounds with fused aromatic rings with aldehyde groups is carried out by using hexane-2 < 5-dione in a molar ratio of 1: 1 or 2: 1 aldehyde sHexane-S ^ -dione converts. The reaction is catalyzed by a catalytic Henge alkali. The presence of water in an amount of 0.5 l / hol of aldehyde gives an optimal yield. Larger amounts of water reduce the yield. Organic solvents _T such as ethylene glycol monoethyl ether or dioxane can also be used. After completion of the reaction, an acid such as SB should _v acetic acid are added to neutralize the excess alkali.

The reaction temperature should be kept in a range between -5 and 50 ⁰ G _1, preferably always = 0 to 25 ° C.

2CS883 /

Thus, according to the invention, there is also a method of manufacture a primary brightener for acidic galvanic tin baths suggested «which is carried out by» that " one hexane-2,5-dione and an aldehyde consisting of 5-membered; heterocyclic K.ingaldehydes, 6-membered homocyclic Ring aldehydes and. Compounds with condensed aromatic Rings and aldehyde groups is selected in a molar ratio of about 1: 1 to 1: 2 in the presence of a kata-? lytic acidic alkali at a temperature between -5 ° 0- and 50 ° 0, then adding an acid to the reaction mixture and separating the reaction product.

When an aldehyde, such as furfuraldehyde, is in a molar 1: 1 ratio is reacted with hexane-2,5-dione, then there is the reaction product predominantly consists of a single chemical compound, however, in the gas phase chromatogram two main peaks occur, which the cis- and represent the trans form of the product. The structure of the active ingredient was determined by nuclear magnetic resonance spectra characterized. They are recorded in the following in the form of the two possible optical isomers:

Il

H C-CH _x II ⁵ .C-CO

HgC-O-OH, 0

Il

H HpC - C -I ² I.

-c «σ ·

f 'C- CH,

Il ο

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The other additives that work with the primary shine are non-ionic alkoxylated surfactants and icy acrylic acid. The wetting agent is used to make a dense, continuous, adhesive and microcrystalline Precipitation is obtained. Without this wetting agent, a loosely adherent, blotchy, sometimes dendritic, crystalline one becomes Preserved tin precipitate * The acrylic acid probably causes an increase in the hydrogen excess at the cathode and thus favors the increase in the cathode-electric yield in the deposition of tin.

Nonionic alkoxylated wetting agents which can be used according to the invention are, for example, aromatic polyethers and aliphatic polyethers. Preferably that exists Polyalkoxylated alkylphenol wetting agent. Typical polyalkoxylated alkylphenols are polyethoxylated alkylphenols of the formula

wherein B ^ is an alkyl group having 8 to 16 carbon atoms (preferably 9 carbon atoms) and k is an integer from 2 to 50 (preferably about 10 to 30) stands"

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Other polyethers in quantities from 1 * 0 to 50 g / l (preferably about 2 to 10 g / l) can be used aliphatic polyethers, which have the following general JTorael exhibit

where R is hydrogen or Ifethyl and ρ is a Integer from about 7 to 50 (preferably about 20 to 40) stands.

Still other polyethers which can be used in amounts of 1 _% 0 to 50 g / l (preferably about 2 to 10 g / l) are nitrogen-containing aliphatic polyethers of the following general formula

RNH (CH ₂ CH ₂ O) _n H

wherein R stands for an isomer mixture having 12 to 22 carbon atoms, preferably 12 to 15 carbon atoms, and with a tertiary Is alkyl structure and η is 15.

The preferred working conditions, such as pH, temperature, and current density, can vary according to the respective bath composition and the object to be tinned by electroplating judge. In general, good shiny abacheidimgei;

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from acidic galvanic bonding baths. received when a certain range of working conditions is adhered to.

The galvanic Verzinnungeverfahren invention using the compositions of the invention can be (preferably 15 to 2O ⁰ O) carried out either with or without agitation at temperatures of about 10 to 60 ⁰ O. The temperature of the bath is usually room temperature, for example 35 ⁰ O or below. Lower temperatures, such as 15 to 20 ⁰ O, give optimal results. In some processes in which considerable cell currents are used that have a tendency to increase in temperature. can be cooled in any suitable manner, such as by circulating cooling water through submerged cooling coils or through cooling machines. If average current densities of 0.5 to 5 »0 a / dm are used, glossy Ziim depositions with an average thickness of 0.25 to 25 μb are obtained in 0.1 to 100 minutes.

If necessary, the bath came to be stirred vigorously and evenly, either by mechanical movement of the object to be coated or by stirring the bath during the electrodeposition. Such stirring can use allow higher current densities on the object to be coated "

Particularly shiny well-leveled precipitates are under Use the following representative bathroom accessories:

SnSO 30 g / l

Cone. H ₀ SO. (SG 1 _T 84) 10 _t 5% by volume

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Furfural / acetonylacetone- q _Q c _k / ^ reaction product

* Tergitol Non-Ionic NP-35 4 g / 1 ice-like acrylic acid 0.2 ml / 1

* The reaction product of 1 mol of nonylphenol and 15 mol

• Ethylene oxide sold by Union Carbide Chemical Corp.

The primary brightener can (ethylene glycol-monoethyl-ether) be used in the form of a basic solution in an organic solvent such as cellosolve containing / l, for example, \ 25 g. Such a solution would then be in a con-} concentration of 20 ml / 1 or from 2 vol -.% Are added. ! The non-ionic alkoxylated wetting agent such as Tergitol '. Non-ionic KP-35i can also be added as a concentrated aqueous basic solution with a content of, for example, 100 g / l. In this case, a concentration of, 40 ml / 1 or 4% by volume would be added.

The invention is through the. the following examples are explained in more detail.

Example 1 - Synthesis of a brightener for acidic tin-plating baths

In a 500 ml Erlenmeyer solvent containing 75 ml of water defleaded, 20 ml (0.25 mol) of furfuraldehyde and 30 ml

209883/1184

(0.25 mol) of hexane-2,5-dione. While the mixture was being stirred mechanically, a solution of 10 g (0.25 mol) of sodium hydroxide in 30 ml of water was slowly added via a dropping funnel. The addition of the sodium hydroxide solution was adjusted so that the temperature remained in a range from 22 to 29 ^° C. Stirring was continued for 2 hours.

The solution was then acidified with 20 ml (0.33 Hol) of acetic acid and the mixture was poured into a separatory funnel Transferred where the mixture separated into two layers. The lower organic layer contained 49 g of a brown one liquid product. A solution of 25 g / l of the product in ethylene glycol monoethyl ether was prepared, which could be used as a gloss base solution.

Example 2

An acid electroplating bath was produced., which contained the following components. It was electrolyzed in this bath for 4 weeks.

2 0 9 8 R 3/1 1 8 4

Table 1 component SnSO ^ Cone. HgSO ^ (S.G. 1.84) iPurf ural / hexane-2 » 5-dione reaction product

Polyethoxylated sulfonylphenol with an average of 15 hydroxyethylene groups (sold as Tergitol Non-ionic NP-35 by the Union Carbide Chemical Corp.)

icy acrylic acid 30 g / l
10.5 vol.

0.05 g / l

4 g / l

0.2 ml / 1

The durability of the deposition conditions was like is checked as follows:

Solution volume
anode

cathode

Zirmplatte (99.99% unit)

Strips of brass 25.4 mm 203 mm χ χ 0.456 mm, the (the _m of the anode face was polished on one side at the bottom in a width of 25 »4 mm, an angle of 45 ° was bent in the horizontal I & nge *

temperature
emotion

current

Tree temperature

move the cathode rod parallel to the anode and

about 10 cm from the anode

1 to 3 A on the total submerged area of 90 em

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It is necessary to keep the anode area at a reasonable value compared to the cathode area, i.e. that at least an anode / athode area ratio of 2: 1 is to be used. The life test continued for many weeks. «Bas Bad worked satisfactorily and gave shiny, well-leveled precipitates with the occasional furfural / hexane-2,5-dione reaction product was supplemented and additions of icy acrylic acid were rarely made.

Example 3

A life test was carried out under the same conditions as in Example 2, except that the reaction product of benzaldehyde and hexane-2,5-dione was used as a brightener and the reaction product of furfuraldehyde and hexane-2,5-dione was not used. The deposits from this Systems were a little less shiny and a little less uniform than those of Example 2. But they were nonetheless excellent rainfall. Virtually no surfactant supplements were required. The speed the consumption of the other additives was very slow.

Example 4 - Synthesis of a brightener for acidic galvanic strand baths with cooling

20 ml (0.25 mol) furfural and 30 ml (O ₁ 25 mol) hexane-2,5-dione were introduced into 75 ml of water. The suspension was brought to a temperature of ⁰ ° C. with an ice / salt bath

2 0 9 8 8 3/1 <e 4

cooled down. Then, 10 g of sodium hydroxide (0 _Ϋ 25 mol) were dissolved in 30 ml of water. The sodium hydroxide solution was then added dropwise to the aldehyde suspension with cooling and stirring. After the addition of the sodium hydroxide solution during which a maximum temperature of 1 ° C. was reached, stirring was continued for a further 3 hours. Then the solution was acidified with 20 ml of glacial acetic acid. The lower layer of the product was extracted with 150 ml of chloroform three times. The chloroform extract was then dried over anhydrous magnesium sulfate and filtered. Then, the low-boiling components were removed under Vasserstrahlvakuum, wherein the bath was maintained at a temperature of about 70 to 80 ⁰ C. 4-5 g of reaction product were obtained * The product was a yellow-brown liquid which appeared somewhat viscous.

Example 5

The same life test as in Example 2 was carried out, except that instead of Tergitol Non-ionic NP-35 ^ β / 1 Friminox R-15 were used. This is a nitrogen-containing aliphatic polyether sold by Rohm and Haas and the following general formula

RNH (CH ₂ CH ₂ O) _n H

where R is an isomer mixture having 12 to 14 carbon atoms with a tertiary alkyl structure and η is 15. The debris from this system was something

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less glossy than in Example 2 and showed a lower degree of leveling. Ss is still about excellent rainfall. When using Priminox R-15 responded to the system on periodic interruption of the current (10 sec flattening and 2 sec de-energized), so that the gloss of the precipitate increases significantly and the Limit current density has been significantly expanded * Here too. periodic replenishment of the furfural / hexane-2,5-dione reaction product and acrylic acid was carried out, to maintain an optimal shine.

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Claims (1)

Patent claims 1, a process for the production of shiny, heavily leveled tin deposits by galvanic means, characterized in that one goes from one anode to one Metal cathode passes a current through an acidic bath composition which contains at least one tin (II) compound, which supplies divalent tin ions for the electrodeposition of tin, ice-like acrylic acid, at least a non-ionic water-soluble oxyalkylated wetting agent and the reaction product of hexane-2,5-dione and contains any of the following compounds: 5-membered heterocyclic ring aldehydes, 6-membered homocyclic Ring aldehydes and compounds with condensed aromatic rings »which carry aldehyde groups. 2. The method of claim 1, characterized in that _s as non-ionic water-soluble wetting agents oocyalkyliertes one of the formula -0 (CH ₂ 0H ₂ 0) _k H. is used, wherein R represents an alkyl group with 8 to 16 Is carbon atoms and k is an integer from 2 to 50. 209883/1184 3 «Method according to claim 1, characterized in that that as a non-ionic water-soluble alkoxylated wetting agent one of the formula HBH (CH ₂ CH ₂ O) _n H. is used? where R. stands for a mixture of isomers which Has 12 to 22 carbon atoms and a tertiary alkyl structure "owns, and η stands for 15» 4 »Method according to claim 1, characterized in that that as a non-ionic water-soluble oxyalkylated wetting agent one of the formula is used where R is hydrogen or a methyl group and ρ stands for an integer from 7 to 60. 5. The method according to any one of claims 1 to 4, characterized characterized in that as a 5-membered heterocyclic ring aldehyde Furfuraldehyde is used. 6, method according to any one of claims 1 to 4, characterized characterized in that as a 6-membered homocyclic ring aldehyde Benzaldehyde is used. 209383/1 7 »Method according to one of the preceding claims _9, characterized in that the tin (II) compound is used in an amount of 10 to 100 g / l. 8. The method according to any one of the preceding claims, characterized in .that _s the ice-like acrylic acid in an amount of 0.025 to 0.5 g / l is used. 9 · Method according to one of the preceding claims, characterized in that the water-soluble oxyalkylated Wetting agent is used in an amount of 1 to iög / 1. 10. The method according to any one of the preceding claims, characterized in that the reaction product of hexane-r-2,5-dione and the aldehyde in an amount of 0.005 to 1.0 g / l is used. 11. The method according to any one of the preceding claims, characterized in that the bath composition the following contains: (a) 10 to 100 g / l tin (II) sulfate; (b) 20 to 200 g / l sulfuric acid j (c) 0.025 to 0.5 g / L icy acrylic acid; (d) 1 to 50 g / L of a non-ionic water soluble oxyalkylated wetting agent; and (e) as the primary glosser 0.005 to 1.0 g / l of the reaction product from Hexan ™ 2,5-dione and one of the following connections: (1) A-OHO, where A is a 5-membered heterocyclic or 6-membered homocyclic ring; and (2) Compounds with fused aromatic rings that have at least one aldehyde substituent contain. 209883/1184 12. Composition for the production of glossy, heavily leveled tin deposits by galvanic means, characterized in that it consists of a bath composition which contains »tin (II) ions, sulfate ions, icy acrylic acid and at least one non-ionic alkoxylated Wetting agent and, as a gloss, the reaction product of hexane-2ϊ5-dione and a compound * from the following is selected: homocyclic aromatic aldehydes and 5-membered heterocyclic ring aldehydes, where the aldehyde group bonded directly to the aromatic ring, conjugated aromatic riagaldehydes or 5-membered heterocyclic Ring aldehydes, being the ring or group also to be inertly substituted » 13 * Composition according to claim 12, characterized in that that the nonionic water-soluble oxyalkylated wetting agent has the formula wherein R is an alkyl group having 8 to 16 carbon atoms and k is an integer from 2 to 50. 14. Composition according to claim 12, characterized in that the non-ionic water-soluble oxyalkylated Wetting agent the formula 209883/1184 ~ 19 - HNH where R stands for an isomer mixture which has 12 to 22 carbon atoms and a tertiary alkyl structure and η stands for 15 * 15 «Composition according to claim 12, characterized in that that the water-soluble oxyalkylated wetting agent has the formula wherein R is hydrogen or a methyl group and ρ is an integer from 7 to 60. 16. Composition according to one of claims 12 to 15 « characterized in that the gloss is the reaction product of hexane-2,5-dione and furfuraldehyde. 17 * Composition according to one of claims 12 to 15, characterized in that the ₄ Glänzer is the reaction product from hexane-2,5 ~ dione and benzaldehyde. _T 18 'composition according to any one of claims 12 to 17t in that the ice-like acrylic acid in an amount of. 0 * 025 to 0 _¥ 5 g / l is present. 209883/1184 1.9 «Composition according to one of claims 12 to 18, characterized in that the non-ionic water-soluble alkoxylated wetting agent in an amount of 1 to 50 g / l is present. 20. Composition according to one of claims 12 to 19 » characterized in that the gloss is present in an amount of 0 * 005 to 1.0 g / l. 21. Composition according to one of claims 12 to 20, characterized in that it contains: (a) 10 to 100 g / l tinClI) sulfate j (b) 20 to 200 g / l sulfuric acid} (c) 0.025 to 0.5 g / L icy acrylic acid; (d) 1 to 50 g / l of a non-ionic water-soluble oxyalkylated wetting agent; and (β) as the primary shimmer 0.005 to 1.0 g / l des Reaction product of hexane-2,5-dione and a of the following connections: (1) A-CHO, where A is a 5-membered heterocyclic ring or a 6-membered one homocyclic ring stands {and (2) Compounds with fused aromatic rings that have at least one aldehyde substituent exhibit* 22. A process for the production of a brightener for acid electroplating tinning baths, characterized in that one hexane ~ 2,5 ~ dione and an aldehyde, which consists of 5-membered heterocyclic ring aldehydes, 6-membered homocyclic 209883/1184 Ring aldehydes and compounds with condensed aromatic rings and aldehyde groups is selected ₇ , in a molar ratio of about 1: 1 to about 1: 2 in the presence of a catalytic amount of an alkali at temperatures between -5 ° C and 50 ⁰ C, then an acid reacts The reaction mixture is added and the reaction product is separated off. 23 · Process according to claim 22, characterized in that an aqueous solution of sodium hydroxide is used as the alkali will* 24 _Λ . Process according to claim 22 or 23 »characterized in that glacial acetic acid is used as the acid. 25 · The method of any of claims 22 to 24, characterized in that ₄ is used as the aldehyde furfuraldehyde. 26ο Method according to one of claims 22 to 24, characterized characterized in that benzaldehyde is used as the aldehyde. 27 «Primary shimmer for galvanic deposition of shiny, well-leveled tin, characterized in that it consists of the reaction product of hexane-2,5- <lion and one of the following connections exists ι (1) A-CHO, where A is a 5-membered ' heterocyclic ring or a 6-membered homocyclic ring; and (2) Compounds with fused aromatic rings which have at least one aldehyde sub-substituent wear. 209883/1184