NL8203230A - ELECTROLYTIC DEPOSITION OF TIN / LEAD ALLOYS. - Google Patents

Description

«4 I" ί VO 362k

Electrolytic deposition of tin / lead alloys.

The present invention relates to improved electroplating baths for depositing tin / lead alloys on various substrates. More particularly, the invention relates to the deposition of shiny metallic tin / lead alloys from improved electroplating baths containing soluble tin and lead salts, preferably suitable tin and lead fluoroborates, together with a compatible acid, e.g. fluoroboric acid is used with a special combination of additives.

There is a large amount of patents relating to tin / lead alloy electroplating baths and disclosing the use thereof. Some of the more relevant patents include U.S. Pat. Nos. 3,730,853 (Sedlacek et al.); 3.7 ^ 9.6 ^ 9 (Valayil); 3,769,182 (Beckwith et al.); 3,785,939 (Hsu); 3,850,765 (Karustis, Jr. et al.); 3,875,029 (Rosenberg 15 et al.); 3,905,878 (Dohi et al.); 3,926.7 ^ 9 (Passal); 3,965,573 (Dahl-gren et al.); 3-956,123 (Rosenberg et al.); 3,977-9-9 (Rosenberg); U000.0 ^ 7 (Ostrow et al.); k.135-991 (Canaris et al.); 11182889 (Hsu); and British patents 1,351,875 and 1 ^ 08.1 ^ 8.

Despite the existence of this extensive literature and various compositions proposed for commercial applications, there is still a need for electroplating baths that will lead to an effective deposition of shiny metallic tin / lead alloys on various substrates. Other important properties are the ability to achieve very rapid deposition and the desired degree of leveling. The variety of hxertoe proposed compositions of tin / lead alloy baths further demonstrate that all were used in the bath composition. ingredients should not only be taken into account in connection with the gloss obtained mahr o.bk in connection with the other aforementioned properties.

8203230 4- * - 2 -

The object of the present invention is to provide an electroplating bath that ensures the deposition of shiny tin / lead alloys on various substrates. .

Another object of the present invention is to provide a tin / lead-5 electroplating bath capable of providing improved gloss at relatively high speeds.

Another object of the present invention is to provide an electroplating bath for the deposition of tin and lead alloys with improved equalization.

These and other objects will readily become apparent from the following description and illustrative embodiments of the present invention.

According to the present invention, it has now been found that an improved electroplating bath can be achieved by using a combination of particular additives together with soluble tin and lead salts as well as a compatible acid. The resulting bath will lead to the very rapid deposition of shiny metallic tin / lead alloys on various substrates.

The required combination of bath additives includes an aromatic amine glosser, an aromatic aldehyde glosser, an aliphatic aldehyde glosser, and a nonionic surfactant grain finer.

According to another aspect of the present invention, copper or rhodium metals can advantageously be deposited together with the tin and lead, e.g. in the form of ternary alloys, from the electroplating baths.

The electroplating baths of the present invention are combined with capable tin and lead in the form of bath-soluble salts, preferably with the same anion, most preferably tin, and lead fluoroborates. A compatible acid, most preferably fluoroboric acid of tin and lead fluoroborates, is also used in an amount sufficient to provide conductivity and keep the metal salts soluble. The amounts of tin and lead which are impurities in the bath will be at least sufficient to promote deposition of the given tin / lead alloy on a substrate, up to their maximum solubility in the bath.

Other bath-soluble divalent tin and lead salts, e.g. the chlorides, sulfamates, phenol sulfonates and the like can be used in the composition of the baths of the invention. Although tin and lead salts with different anions can be used, it is preferable to use salts with the same anions. In addition, other compatible acids can be used in place of or in conjunction with the fluoroboric acid, e.g. hydrochloric acid, sulfamic acid, phenol sulfonic acids, and the like. The acid used may have an anion other than deion and lead salts, but it is preferably the same anion. In the most preferred embodiment, the fluoroborate salts of tin and lead are used together with fluoroboric acid.

The gloss emitter system of the invention comprises a combination of an aromatic amine, an aromatics aldehyde, and an aliphatic aldehyde. These are each present in a range which is at least sufficient to impart shine to the electrolytic tin / lead deposit in combination, up to the maximum solubility of each in the bath.

In this glosser system, the weight ratio of the aromatic amine to the aromatic aldehyde should preferably be in the range from 1.25 to 20: 1 to 100: 1, with a ratio in the range from about 5: 1 to 20: 1 particularly preference is trembling.

The aromatic or aryl amines useful for the present purposes include o-toluidine, p-toluidine, m-toluldine, aniline, and o-cbloroaniline. For most purposes, the use of o-cbloro-aniline is particularly preferred. The aromatic aldehydes are e.g. compounds such as 1-naphthaldehyde, 2-hydroxy-1-naphthaldehyde, 2-methoxy-1-naphthaldehyde, and the like. The preferred aromatic aldehyde is 1-naphthaldehyde. Suitable aliphatic aldehydes are those containing 1 to 1 carbon atoms and are e.g. formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, crotonaldehyde and the like. In this invention, the preferred aldehyde is formaldehyde, which may suitably be used as formalin, a 37% solution of formaldehyde.

A nonionic surfactant must also be present in the bath as a grain refiner. It is present in an amount at least sufficient to provide grain refinement in the electrolytic 8203230 # - k - tin / lead deposit, up to its maximum solubility in the bath.

Suitable nonionic surfactants can be commercially available materials such as nonylphenoxy polyethylene oxide ethanol (ipepal CO630 and Triton QS15); ethoxylated alkylolamide (Amidox L5 and C3); alkyl polyglycol ether ethylene oxide (Neutronyx 675); and such. The nonionic surfactants particularly found effective for the present purposes are the polyoxyalkylene ethers in which the alkylene group contains from 2 to 20 carbon atoms.

Polyoxyethylene ethers with 10-20 moles of ethylene oxide per mole of lipophilic groups are preferred, and include surfactants such as polyoxyethylene lauryl ether (sold under the trade name Brij 35-SP).

Optionally, an antioxidant can be included in the plating bath to prevent the formation of tin (IV) compounds, which result from the oxidation of the tin (II) salts used to prepare the bath and in the bath, keep it to a minimum or reduce it. Any suitable antioxidant or oxidation inhibitor can be used, which is effective at the acidic pH of the plating bath and does not adversely affect the course of the deposit or the electrolytic deposit formed. Such antioxidants are typically used in amounts of about 0.5 - 50 g / dm, with amounts of about 5-10 g / dnr being preferred.

Particularly preferred antioxidants are the aromatic sulfonic acids. Typical examples of these aromatic sulfonic acids are o-25 cresol sulfonic acid, m-cresol sulfonic acid, and phenol sulfonic acid. Other phenol sulfonic acid derivatives of phenol and cresol that may be used include:.

2,6-dimethylphenol sulfonic acid, 2-chloro-6-methylphenol sulfonic acid, 2, U-dimethylphenol sulfonic acid, 2, h, 6-trimethylphenol sulfonic acid, p-creso sulfonic acid.

Siliconic acid derivatives of <K- and / -6-naphthols can also be used.

In summary, the preferred ingredients of the unsaturated 3203230-5% electroplating baths of the invention have the following ranges:

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Ingredients Amounts (g / drr) General Preference (1) Tin 5-50 15-30 5 (2) Lead. 3-20 2-8 (3) acid 100 - 250: 160 - 190 (¼) aromatise aldehyde 0.01 - 0.5 0.03 - 0., 1 (5) aromatise amine 0.3 - 15 0.5 - 1 * 5 (6) aliphatic aldehyde 0.5 - 20 0.9 - 10.0 IQ (7) non-ionic surfactant 0.1 - 20 0.5 - 2.5

At these concentrations, the pH of the bath will typically be less than about 1, generally about 0.05, however much a pH above 1 may also be used. Electroplating temperatures and current densities will generally range from about 10 to 0 ° C, respectively. from about 5 to 500 ASF (53.8 - 5382 A / m2) t file the preferred conditions 15 - 25 ° C resp. 25 - 200 ASF (269 - 2153 A / m 2). It is particularly preferred to explore at or near room temperature.

The electroplating bath and the spreader of the present invention can be used to produce a wide range of tin / lead alloy compositions. Alloy deposits with about 99% tin and 1% lead to about 99% lead and 1% tin can be obtained. Obviously, in order to obtain these various tin / lead alloy deposits, the relative proportions of the bath components must be varied slightly in order to impart the optimum shine, ductility and other properties to the respective alloy. From the point of view of commercial utility, it has been found that tin / lead alloy deposits containing about 95% tin and 5% lead and tin / lead and solder deposits containing about 60% and 40% lead are particularly useful, and these are easily produced with the baths and the sprouts of the present invention.

Most plating enhancements are preferred and often rapid agitation. On top of that, anode: cathode - "* 35 ratios of about 1 to 1: 10: 1 are used, with a ratio of about 4: 1 being preferred. The substrates used with application. The electroplating bath and the nit vending method can be plated, including copper, copper alloys, steel, nickel, and nickel alloys and the like.

As noted above, copper and rhodiun metals can be deposited on the substrates together with the tin and lead when the above-described electroplating baths are used without additional additives or complexing agents. In contrast, metals such as nickel, iron and indium did not co-settle under the same conditions.

Typically, the copper or rhodium is added to the bath as bath-soluble compounds, preferably with the same anions as the tin and lead. The amounts added of such compounds will be sufficient to cause up to about 5 wt.% Copper or rhodium to be alloyed with the tin and lead in the electrolytic deposit. Typical amounts of copper and rhodium in the electroplating baths to obtain such amounts of the metal in the electrolytic deposit. are about 0.2 - U g / dnr resp. 0.2-2 g / dm.

Another aspect of the present invention is that a corresponding aliphatic acid can be included in the bath, either in addition to or as a substitute for up to half (50%) of the aliphatic aldehyde, without any adverse effect on the solder deposit gloss. or its other desirable properties. For example, one can e.g. up to half of the formaldehyde (formalin) content is replaced by formic acid, and yet still has an electroplating bath which is performance equivalent to the base tin / lead bath of the invention with a full amount of formaldehyde. In contrast, baths of the invention containing less than half (i.e., $ 50) of the prescribed amount of formaldehyde could not give an acceptable appearance regardless of the amount of formic acid added. On the other hand, the amount of formic acid added need not be exactly equal to the amount of formaldehyde omitted, and can be added without omitting any formaldehyde. It was further found that formic acid had little or no effect on baths of the invention when the formaldehyde was completely evaporated.

The advantages of being able to replace up to 50% of the formaldehyde with formic acid are the less amount of formaldehyde consumed during the operation of the plating bath, and therefore the use of formic acid requires relatively little addition of formaldehyde.

Under certain operating conditions, it may be advantageous to formulate the bath with boric acid to prevent or greatly reduce the formation of free hydrogen fluoride in the bath.

When boric acid is used, it need only be used in amounts sufficient to greatly reduce the formation of free hydrogen fluoride. Amounts up to about βθ g / dm are typical, while amounts up to about 30 g / dm are preferred. It has been found that the tin / lead electroplating solutions of the invention contain surfactants that can cause foaming problems in certain types of commercial applications. This pro,. The problem can be overcome by including minor amounts of a suitable defoamer ("defoamer") in the bath, generally in amounts ranging from about 0.06 cm / h to the solubility limit of the defoamer. A particularly preferred anti-foaming agent has been found to be octyl alcohol which is not only chemically and electrochemically compatible with the other bath ingredients, but also does not adversely affect tin / lead deposits.

The present invention will be more fully understood from the following illustrative embodiments.

Example I

An electroplating bath was prepared from the ingredients listed below: 30 Ingredients Quantity 3 tin, added as tin (II) fluoroborate 30 g / drr

lead, added as lead fluoroborate k g / dmJ

fluoroboric acid 172 g / dm 3 o-chloroaniline 0.5 g / dm 35 formalin 20 cm ^ / dm ^ 8203230 - δ - ο polyoxyethylene lauryl ether 2.5 g / dm 1-naphthaldehyde 0.05 g / dm water, residue η p

This stable tad was operated at 20 ° C, 6θ ASF (6k6 A / m}, under agitation to flatten a copper panel. The tin / lead deposit thus formed contained 95% tin and 5% lead and had a very shiny appearance.

Example II

In the composition of Example I, copper fluoroborate was added at a concentration of 0.5 g / dm. The bath was operated at 60 ASF (6b6 A / m 2) and gave a shiny tin / lead / copper alloy deposit containing about% copper, 89% tin and 5% lead.

When nickel, iron and indium metal were used in place of the copper in the above bivalent tin / lead bath, no co-deposition of any of these metals with the tin / lead took place.

-Example III

An electroplating bath was prepared with the following ingredient and:

Ingredients Quantity 20 tin, added as tin (ll) fluoroborate 30 g / dur lead, added as lead fluoroborate 1 * g / dnr fluoroboron no 172 g / dm

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boric acid 20 g / ctar formalin 20 cm ^ / dm ^ 25 o-chloroaniline 0.5 g / dnr l-naphthaldehyde 0.05 g / dm ^

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polyoxyethylene lauryl ether 2.5 g / dnr miereznur (88 $) 2 cm ^ / dm ^

The bath was operated at room temperature, βθ ASF (6b6 A / m), with rapid agitation and tin / lead anodes. The formaldehyde concentration was as in Example 1, but with added formic acid, the need for subsequent additions of formaldehyde to keep the bath in optimum condition was eliminated. The tin / lead deposit was very shiny and contained 95% tin and 5% lead.

35 8203230.-9- ..... ----------- .--: s-Z · ·· · -

Example IV

A tin / lead electroplating bath was prepared from the following ingredients:

Ingredients Quantity 5 tin, added as tin (II) fluoroborate 30 g / ctar

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lead, added as lead fluoroborate ^ g / ctar

O

fluoroboric acid 172 g / ctar

O

boric acid 20 g / ctar formalin 10 cm / dm 10 o-chloroaniline 0.5 g / dnr

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1-Naphthaldehyde 0.05 g / dm 3 polyoxyethylene lauryl ether 2.5 g / dm formic acid ($ 88) 5 cm ^ / dm ^

This bath was operated under the same conditions as in Example III. Despite the replacement of 50% of the originally required amount of formaldehyde by formic acid, the appearance of the deposit was very glossy. The shining. was the same as obtained with the bath of Example I containing 20 cm / dm formalin and no formic acid. Example V

To electroplating baths composed as in Example I, 0.06 cm0 / dm, respectively. 0.18 cnr / ctar octyl alcohol added.

These baths were operated as in. Example I to form very shiny tin / lead deposits containing 95% tin and 5% lead.

Samples from each of these baths and from the bath of Example I.

25 were put into bottles which were closed with a stopper and then shaken. The foam height in the bottle with the sample containing 0.06 cmr / dm ° octyl alcohol was about 20 - 30% less than the

foam height in the bottle containing the sample from the bath of Example I.

3 3 contained. The foam height in the bottle with the sample containing 0.18 cm / dm octyl alcohol was approximately the same as in the bottle containing the sample from the bath of Example I. The time required for the foam in the former bottle to disappear was about $ 30 less than for the latter.

Example VI

An electroplating bath was prepared from the following ingredients: 8203230 - 10 -

Ψ Q

Ingredients Amount of tin, added as tin (II) fluoroborate 30 g / ml lead, added as lead fluorobrate 8 g / ml ^

O

fluoroboric acid 172 g / dm

O

5 o-chloroaniline 0.56 g / dm 3 3 formalin 20 cm / dnr polyoxyethylene lauryl ether. 2.5 g / dm 1-naphthaldehyde 0.11 g / dn? water residue 10 The resulting stable bath was heated at 20 ° C, 60 ASF (6k6 A / m2) under agitation to flatten a copper panel. The tin / lead deposit thus formed had a very glossy appearance and contained 60% tin and 10% lead.

Example VII

In order to illustrate the influences of the essential additive components of the present invention, five plating baths were composed as follows:

A bath of Example I

B - bath of example I with omission of non-ionic surfactant C - bath of example I with omission of aliphatic aldehyde D - bath of example I with omission of aromatic amine E - bath of example I with omission of aromatic aldehyde .

These baths were operated as in Example 1 and the following results were obtained:

Result

Bath A (all four additives): a shiny, smooth deposit

Bad B (surfactant omission): a black, spongy deposit 30 with dendritic growth

Bad C (omission of aliphatic a dull metallic white deposit aldehyde): ting

Bath D (omission of aromatic dull, slime or black haze amine): 35 8203230 * - * - 11 -

Bad E (omission of aromatic semi-gloss, with staggered plat aldehyde): consumption in the high current density regions and a white haze in the low current regions

5 Preface VIII

In order to illustrate the influence of the operation of the hedges of the invention with ratios of aromatic amine to aromatic aldehyde hulls in the ratio range of 1.25: 1 to 100: 1, electroplating hams were formulated with the following ingredients:

Ingredients Amount of tin, added as tin (II) fluorohorate 30 g / dnr lead, added as lead fluorohorate b g / dm

O

fluoroboric acid 172 g / dm 15 formalin 20 cm 2 / dm 2 polyoxyethylene-lauryl ether 2.5 g / dm o-chloroaniline varied: 1-naphth aldehyde varied.

In these tests, the tin / lead was deposited on a brass substrate 20 at a temperature of 20 C, 60 ASF (6h6 A / m), and with rapid agitation of it. The ratio of the o-chloroaniline to the 1-naphthaldehyde was varied in different hades to obtain hades in which this ratio was as follows:

Code: 25 Normal - concentration within the area of the gloss emitter ratio

High concentration courts the upper limit of the ratio hied

The low concentration concentration is the limit of the proportions.

Using this procedure, the following results were obtained: o-chloro-1-naphthaldehyde Appearance aniline high normal low current density, staggered plating 35 high high haze and staggered plating 8203230 - 12 - high low high current density, staggered plating low high glossy high current density , hazy low current density areas 5 low low zvaar Vase, especially in areas of low current density low normal heavy vase; shiny high. Current Density Areas Normal High Glossy High Current Density, Vase 10 Low Current Density Normal Low High Current Density, Staggered Plating Normal Normal Glossy Smooth Deposition "It will be appreciated that the above examples are illustrative and that variations and modifications may be incorporated therein. without leaving the scope of the invention.

% 8203230 "

Claims (10)

A tin / lead electroplating bath comprising tad soluble salts of craft tin and lead in amounts at least sufficient to promote deposition of the given tin / lead alloy on a substrate up to the maximum solubility of the ferret salts, one compatible with these salts in an amount at least sufficient to create conductivity in the bath and to keep the salts soluble in the bath, a grain-refining amount of a nonionic surfactant, and a brightener composition comprising an aromatics aldehyde, an aliphatic aldehyde and an aromatics amine, each of which is present in an amount at least sufficient to impart shine to the tin / lead alloy deposit in combination, and wherein the content ratio of the aromatics amine to aromatics aldehyde is in the range of about 1.25: 1 to 100: 1. The electroplating bath according to claim 1, characterized in that the tin and lead salts are tin (II} fluoroborate and lead fluoroborate. The electroplating bath according to claim 1, characterized in that the compatible acid is fluoroboric acid. k. Electroplating bath according to claim 1, characterized in that it also contains an alloy metal selected from the group of copper and rhodium metals. The electroplating bath according to claim 1, characterized in that boric acid is present in the bath. 6. Electroplating bath according to claim 1, characterized in that an anti-foaming agent is additively present in the bath. Electroplating bath according to claim 6, characterized in that the anti-foaming agent is additive octyl alcohol. An electroplating bath according to claim 1, characterized in that up to 50% of an aliphatic aldehyde has been replaced by the corresponding aliphatic acid. Electroplating bath according to claim 1, characterized in that the components are present in the following amounts: 8 20 3 2 3 0 3 - Tin - 5-50 g / dm3 lead 3-20 g / dm3 "compatible acid 100 - 250 g / dm • non-ionic surface-5 active agent 0.1 - 20 g / dm 3 aromatic amine 0.3 - 15 g / dm 2 aromatic aldehyde 0.01 - 0.5 g / dm O aliphatic aldehyde 0.5 - 20 g / dm 10. An electroplating bath according to claim 9, characterized in that the tin and lead are added as tin (II) fluoroborate and lead fluoroborate, the acid compatible is fluoroboric acid, the non-ionic surfactant is polyoxyethylene lauryl ether, the aromatic amine is o-chloroaniline, the aromatic aldehyde is 1-naphthaldehyde and the aliphatic aldehyde is formaldehyde. 11. An electroplating bath according to conelusion 10, characterized in that up to 50% of the formaldehyde has been replaced by formic acid. 12. Method of electrolytic deposition of shiny tin / lead alloys, characterized in that an electric current between an anode and a cathode is passed through an electroplating bath according to one or more of claims 1-11, for a sufficient period to form the best tin / lead alloy deposit. 8203230