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Publication numberUS3875029 A
Publication typeGrant
Publication dateApr 1, 1975
Filing dateFeb 19, 1974
Priority dateFeb 19, 1974
Also published asCA1046976A1, DE2506158A1, DE2506158B2
Publication numberUS 3875029 A, US 3875029A, US-A-3875029, US3875029 A, US3875029A
InventorsEckles William E, Rosenberg William E
Original AssigneeR O Hull & Company Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Plating bath for electrodeposition of bright tin and tin-lead alloy
US 3875029 A
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Description  (OCR text may contain errors)

United States Patent Rosenberg et al.

[ Apr. 1, 1975 PLATING BATH FOR ELECTRODEPOSITION OF BRIGHT TIN AND TIN-LEAD ALLOY [75] Inventors: William E. Rosenberg, Strongsville;

William E. Eckles, Cleveland Heights, both of Ohio [73] Assignee: R. 0. Hull & Company, Inc.,

Cleveland, Ohio [22] Filed: Feb. 19, 1974 [21] Appl. No.: 443,406

[52] U.S. Cl 204/43 S, 204/53, 204/54 R [51] Int. Cl. C23b 5/14, C23b 5/38, C23b 5/46 [58] Field of Search 204/43 S, 54 R, 53

[56] References Cited UNITED STATES PATENTS 3,361,652 1/1968 Korpiun et a1 204/54 R 3,471,379 10/1969 Schoot et a1. 204/54 R 3,769,182 10/1973 Beckwith et al 204/43 S 3,785,939 1/1974 Hsu 204/43 S Primary Examiner-G. L. Kaplan Attorney, Agent, or Firm-Watts, l-loffmann, Fisher & Heinke Co.

[5 7] ABSTRACT The invention disclosed herein relates to the electrolytic deposition-of bright tin and tin-lead alloy. This invention is embodied in a new plating bath and a plating bath additive. The new plating bath includes tin or tin and lead ions, sulfuric acid or fluoboric acid, and the new additive. The new additive includes an emulsified naphthalene monocarboxaldehyde with or without a substituted olefin, having the general formula:

in which R is carboxy, carboxamido, alkali carboxylate, ammonium carboxylate, ,amine carboxylate, or

alkyl carboxylate, and R R and R are hydrogen, methyl, or lower alkyl.

15 Claims, No Drawings PLATING BATH FOR ELECTRODEPOSITION OF BRIGHT TIN AND TIN-LEAD ALLOY BACKGROUND OF THE INVENTION The invention pertains to aqueous acid plating baths and additives for producing semi-bright or bright electrodeposits of tin and tin-lead alloy. I

Prior to this invention recently introduced commercially usable acid tin baths have been composed of multi-component brightening agents to produce acceptably bright electrodeposits. The essential ingredients of these baths are various combinations of certain aldehydes and ketones, imidazoline surfactants, nonionic surfactants, and amines. While these baths produce significantly bright deposits, many of them lack sufficient broad bright current density ranges. This means careful control of current and time consuming racking procedures are required to avoid dull or-coarse deposits On parts that due to their irregular shapes promote uneven current distribution.

The one thing common to all of these combinations is that the ingredients depend on one another to produce bright deposits. Being essential ingredients the lack or absence of any one of them nullifies the effect of the others.

What makes our invention unique is that the naphthalene monocarboxaldehyde produces a brightness without dependence on distinct types of emulsifiers and amines. The only essential requirement is that the naphthalene monocarboxaldehyde be made soluble in the plating bath. This can be achieved by use of coupling solvents as well as emulsifiers in .general. Prior brightener systems requirespecific surfactants to be used since their brightening ability is essential in the performance of the system as awhole.

While it is true that the addition of compounds of the general formula:

are required also for extreme luster, semi-bright to bright, uniform deposits can be obtained without them. Also with the use of this invention a very broad, bright current density range is achieved providing a means for electroplating extremely irregular shapes without stringent controls on current or racking of parts. In addition, higher current-densities can be achieved without obtaining coarse deposits, allowing an electroplater to obtain more plate thickness in a shorter time.

SUMMARY OF THE INVENTION This invention is embodied in an aqueous acid electroplating bath containing a dissolved tin salt, together with a lead salt, if an alloy is desired, an acid selected from the group consisting of sulfuric acid and fluoboric acid and a solubilized or dissolved naphthalene monocarboxaldehyde.

When compounds of the general formula:

where R, is carboxy, carboxamido, alkali carboxylate, ammonium carboxylate, amine carboxylate, or alkyl carboxylate, and R R and R are hydrogen, methyl, or lower alkyl are also added to the plating bath, they act synergistically with the naphthalene monocarboxaldehyde to give significantly brighter deposits than obtained with the dissolved naphthalene monocarboxaldehyde alone.

This invention is also a brightening agent for the aqueous acid electroplating baths described above comprised of about l to 99 percent naphthalene monocarboxaldehyde, about 0 to 99 percent emulsifier, 0 to 99 percent of a compound of the general formula:

where R, R R and R, are defined as above, and the remaining percentage being a suitable solvent.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The aqueous acid electroplating baths of the present invention generally contain stannous ion, sulfate or flouborate ions and dissolved naphthalene monocarboxaldehyde for proper operation. The stannous ion is introduced usually as stannous sulfate and the lead salt, when an alloy is'desired, is introduced as lead flouborate.

The naphthalene monocarboxaldehydes are readily available in commerce and their uniqueness as brightening agents compared to other aldehydes and ketones can be partially explained by a close study of their chemical structure.

Three resinance bond structures for naphthalene are possible, the symmetrical structure I and the two unsymmetrical, equivalent structures II and Ila; In formulations of the unsymmetrical structure s,one of the two rings is indicated as quinoid (q) because the arrangement of double bonds corresponds to that of obenzoquinone.

b I b I Various chemical reactions of naphthalene show that the bond structure of the naphthalene nucleus is not so mobile as that of benzene and that there is a relative fixation of bonds in at least part of the molecule at which substitution occurs. This is generally described as an enhanced l,2-double bond character.

A much more detailed explanation of monosubstituted naphthalenes unique chemical behavior is given in Advanced Organic Chemistry by Fieser and Fieser, page 880. As can be concluded from the above discussion, monosubstituted binuclear aromatic aldehydes will show distinctly different chemical properties such as electron donating ability and reactivity when compared to aldehydes and ketones derived from benzene, heterocyclic aromatic single ring compounds, and certainly those of cyclic and straight chained aliphatic compounds.

The naphthalene monocarboxaldehyde is used at a concentration of about 0.05 to 0.5 gms/liter and the preferred concentration is 0.2 gms/liter.

Due to its low solubility, coupling agents or emulsifying agents must be used to dissolve the naphthalene monocarboxaldehyde in the plating bath. Some of the suitable coupling agents are diethylene glycol monomethyl ether, diethylene glycol monobutylether, ethylene glycol monomethyl ether, and diethylene glycol monoethylether. 5

The emulsifying agents that have been found to work best are cationics such as the alkyl tertiery heterocyclic amines and alkyl imadazolinium salts, amphoterics such as the alkyl imidazoline carboxylates, and nonionics such as the aliphatic alcohol ethylene oxide condensates, sorbitan alkyl ester ethylene oxide condensates, and alkyl phenol ethylene oxide condensates. The nonionics are generally condensed with to moles of ethylene oxide per mole of lipophilic group. Listed in Table l are the commercial names and manufacturers of these emulsifiers. This invention is not limited to the use of these emulsifiers only, it being pointed out that this is merely a list of preferred types.

TABLE I 20 Trade name Type Manufacturer 1. Miranol HM Miranol HS Amine C Amine S Tween 40 t Triton N-lOl Tergitol TMN Amphoteric Amphoteric Cationic Cationic Nonionic Nonionic Nonionic Miranol Chemical Co.

o. Ciba-Geigy do. lCl America Rohm & Haas Co. Union Carbide where R is carboxy, carboxamido, alkali carboxylate, ammonium carboxylate, amine carboxylate, or alkyl carboxylate, and R R R are hydrogen, methyl, or lower alkyl. The olefinic compound as set forth above may be added to a plating bath using the naphthalene 0.5 gms/liter. The required amount of the naphthalene monocarboxaldehyde in this synergistic combination is the same as when it is used alone.

Other known addition agents may be used in combination with the addition agents of this invention such as other aromatic and aliphatic aldehydes and ketones, but it has been generally found that they are not neces sary. Antioxidants such as pyrocatechol and cresol sulfonic acids may be used with this invention as well as chelating agents to prevent metal sludge build-up on anodes.

The brightening agents of this invention are generally added as aqueous, or methyl alcohol solutions, but other suitable solvents can be used as long as they dont cause detrimental results during electrodeposition. In some cases the addition agents may be added in their concentrated form, provided the plating bath is thoroughly stirred.

While the brightening agents of this invention are effective in many aqueous, acid tin plating bath formulations, it is preferred to use any-of the basic baths described in the following examples. It will be understood that the following examples are just illustrations and are not meant to limit the use of the invention to these bath formulations only.

EXAMPLE 1 Bath Composition Concentration in gms/liter Stannous Sulfate 30 Sulfuric Acid 200 l-naphthalene carboxaldehyde 0.2 diethyleneglycol monomethyl ether 40 EXAMPLE ll Bath Composition Concentration in gms/liter EXAMPLE lV Bath Composition monocarboxylate to obtain a much brighter deposit gta pnousAs ljfate 238 u unc c1 than can be obtained with the naphthalene monocar .zmphthalene carboxadehyde O2 boxaldehyde alone. The olefimc compound has no Methacrylic acid 0.5 brightening ability when used by itself, and acts as a NW1 8 brightener only when used in the above mentioned ExAMpLEv combination.

Examples of some of the preferred olefmic com- Bath g Cmcenmmn" gms/me' pounds are listed in Table II. me 88 l-naphthalene carboxaldehyde 0.2 TABLE II Acrylic acid 0.4 Triton N-lOl l0 Acrylic Acid Acrylamide EXAMPLE vi Methacryl?mld e Bath Composition Concentration in gms/liter Methacfyhc acld Lead Flouborate 4.5 Crotonic acid goriglActid 10 in ou orate l4 Ethyl aFrylate 5 Flouboric Acid 90 The required concentration of the olefinic compound 2-naphthalene carboxaldehyde 0.2 Methacrylic acid 0.5 is about 0.1 to 5 gms/liter, the preferred amount being Tergitol TMN 0 Concentration in gms/liter where R is carboxy, carboxamido, alkali carboxylate,

ammonium carboxylate, amine carboxylate, or alkyl carboxylate, and R R and R are hydrogen, methyl, or lower alkyl.

4. The bath of claim 3 wherein R, is carboxy, and R R and R are hydrogen.

5. The bath of claim 4 wherein the emulsifying agent TABLE III Basic bath as described in examples but no addition group on naphthalene Position of aldehyde Olefinic compound Emulsificr or Results coupling agent agent. emulsifiers. or ring coupling agent 1. Bath of Example I l Triton N-lOl Semi-bright to bright from I to I amps/ft? 2. Bath of Example I l Methacrylic acid Miranol HM Very bright from l to 80 amps/ft. 3. Bath of Example I 2 Amine C Semi-bright from 1 to 80 amps/ft. 4. Bath of Example I l Acrylic Acid Tween 40 Very bright from 5 to 60 amps/ft.-' 5. Bath of Example I 2 Methacrylic Acid Tergitol TMN Very bright from 5 to 80 amps/ft. 6. Bath of Example VI 1 Methacrylamide Triton N-lOl Very bright de osit from to 80 amps ft. of an alloy composed of about 60% tin and 40% lead 7. Bath of Example I Acrylic Acid Very dull at all current densities 8. Bath of Example Vl Methacrylic acid Very dull at all current densities 9. Bath of Example I l diethyleneglycol Bright from 1 to I00 monomcthyl amps/ft. I ether 10. Bath of Example ll 1 Crotonic acid Tergitol TMN Bright from l0 to 100 amps/ft.

Having thus described this invention in such full, clear, concise and exact terms as to enable any person skilled in the art to which it pertains to make and use the same, and having set forth the best mode contemplated of carrying out this invention, we state that the subject matter which we regard as being our invention is particularly pointed out and distinctly claimed in what is claimed, it being understood that equivalents or modifications of, or substituitions for, parts of the above specifically described imbodiment of the invention may be made without departing from the scope of the invention as set forth in what is claimed.

What we claim is:

1. An aqueous acid tin electroplating bath containing stannous ions, at least one acid from the group consisting of sulfuric acid and flouboric acid, and having dissolved therein as a brightening agent about 0.05 to 0.5 gms/liter of a naphthalene monocarboxaldehyde.

2. The bath of claim 1 wherein about 1 to 10 gms/liter of an emulsifying agent is added to solubilize the naphthalene monocarboxaldehyde.

3. The bath of claim 2 containing about 0.1 to 0.5 gms/liter of a substituted olefin of the general formula:

is an alkyl phenol condensed with about l0 to 20 moles of ethylene oxide per mole of alkyl phenol.

6. The bath of claim 3 wherein R, is carboxy, R is methyl, and R and R are hydrogen.

7. The bath of claim 6 wherein the emulsifying agent is an alkyl phenol condensed with about 10 to 20 moles of ethylene oxide per mole of alkyl phenol.

8. The bath of claim 3 wherein there is also present a dissolved lead salt and the acid is flouboric acid.

9. The bath of claim 2 wherein the acid is sulfuric acid.

10. The bath of claim 2 wherein the acid is flouboric acid.

11. The bath' of claim 2 wherein the emulsifying agent is selected from the group consisting of cationic surfactants, nonionic surfactants, and mixtures thereof.

12. The bath of claim 2 wherein the emulsifying agent is an alkyl phenol condensed with about 10 to 20 moles of ethylene oxide per mole of alkyl phenol.

13. The bath of claim 2 wherein the naphthalene monocarboxaldehyde is 2-naphthalene monocarboxaldehyde.

14. The bath of claim 2 wherein the naphthalene monocarboxaldehyde is l-naphthalene carboxaldehyde.

15. The bath of claim 2 wherein there is also present a dissolved lead salt and the acid is flouboric acid.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3361652 *Aug 24, 1964Jan 2, 1968Max Schlotter Dr IngElectrodeposition of bright tin
US3471379 *Jan 20, 1966Oct 7, 1969Philips CorpTin plating baths
US3769182 *Jul 6, 1971Oct 30, 1973Conversion Chem CorpBath and method for electrodepositing tin and/or lead
US3785939 *Oct 22, 1970Jan 15, 1974Conversion Chem CorpTin/lead plating bath and method
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3977949 *Jul 7, 1975Aug 31, 1976Columbia Chemical CorporationAcidic plating bath and additives for electrodeposition of bright tin
US4135991 *Aug 12, 1977Jan 23, 1979R. O. Hull & Company, Inc.Bath and method for electroplating tin and/or lead
US4207148 *Feb 16, 1979Jun 10, 1980Minnesota Mining And Manufacturing CompanyAcid, nonionic surfactant, brightener system
US4263106 *Dec 31, 1979Apr 21, 1981Bell Telephone Laboratories, IncorporatedElectrodeposition of lead or tin from aqueous acid with heterocyclic additives
US4376018 *Oct 2, 1981Mar 8, 1983Bell Telephone Laboratories, IncorporatedWith phenolphthalein additive
US4377448 *Oct 2, 1981Mar 22, 1983Bell Telephone Laboratories, IncorporatedIn water bath with phenolphthalein
US4377449 *Oct 19, 1981Mar 22, 1983Bell Telephone Laboratories, IncorporatedIn water bath containing phenolphthalein
US4379738 *Oct 19, 1981Apr 12, 1983Bell Telephone Laboratories, IncorporatedElectroplating zinc
US4530741 *Jul 12, 1984Jul 23, 1985Columbia Chemical CorporationAldehyde substituted naphthalene compound
US4582576 *Mar 26, 1985Apr 15, 1986Mcgean-Rohco, Inc.Plating bath and method for electroplating tin and/or lead
US4586990 *Feb 13, 1984May 6, 1986Gsp Metals & Chemicals CorporationElectroplating terminals of integrated circuits with lead and tin
US4715894 *Aug 29, 1985Dec 29, 1987Techno Instruments Investments 1983 Ltd.Use of immersion tin and tin alloys as a bonding medium for multilayer circuits
US4816070 *Oct 29, 1986Mar 28, 1989Techo Instruments Investments Ltd.Use of immersion tin and alloys as a bonding medium for multilayer circuits
US4871429 *Apr 29, 1988Oct 3, 1989Learonal, IncLimiting tin sludge formation in tin or tin/lead electroplating solutions
US4880507 *Dec 9, 1988Nov 14, 1989Learonal, Inc.Nonionic surfactants
US4885064 *May 22, 1989Dec 5, 1989Mcgean-Rohco, Inc.Additive composition, plating bath and method for electroplating tin and/or lead
US5066367 *Sep 20, 1990Nov 19, 1991Learonal Inc.Limiting tin sludge formation in tin or tin/lead electroplating solutions
US5094726 *Sep 20, 1990Mar 10, 1992Learonal, Inc.Limiting tin sludge formation in tin or tin-lead electroplating solutions
US5174887 *May 2, 1990Dec 29, 1992Learonal, Inc.Using electrolyte containing alkylsulfonic acid, soluble tin compound, alkylene oxide condensate surfactant
US5545440 *Dec 5, 1994Aug 13, 1996At&T Global Information Solutions Company (Aka Ncr Corporation)Method and apparatus for polymer coating of substrates
US5597469 *Feb 13, 1995Jan 28, 1997International Business Machines CorporationProcess for selective application of solder to circuit packages
US5698087 *Mar 11, 1992Dec 16, 1997Mcgean-Rohco, Inc.Plating bath and method for electroplating tin and/or lead
US5814202 *Oct 14, 1997Sep 29, 1998Usx CorporationElectrolytic tin plating process with reduced sludge production
DE3228911A1 *Aug 3, 1982Mar 24, 1983Occidental Chem CoBad fuer die galvanische abscheidung einer zinn-blei-legierung
EP0196232A2 *Mar 26, 1986Oct 1, 1986Mcgean-Rohco, Inc.Plating bath and method for electroplating tin and/or lead
EP0216531A1 *Aug 28, 1986Apr 1, 1987Techno Instruments Investments 1983 Ltd.Use of immersion tin and tin alloys as a bonding medium for multilayer circuits
WO1983003266A1 *Mar 15, 1983Sep 29, 1983Gsp Metals Chemicals CorpChelating metals
Classifications
U.S. Classification205/253, 205/304, 205/302
International ClassificationC25D3/32, C25D3/60, C25D3/30
Cooperative ClassificationC25D3/32, C25D3/60
European ClassificationC25D3/60, C25D3/32