US2931760A

US2931760A - Acid copper plating

Info

Publication number: US2931760A
Application number: US686039A
Authority: US
Inventors: Leon R Westbrook
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-09-25
Filing date: 1957-09-25
Publication date: 1960-04-05
Anticipated expiration: 1977-04-05

Description

United States Patent 41c O -E K PL N Leon -R. :Westbrook, Solon, Ohio No Drawing, Application September 25, 1957 Serial No. sseow '19 Claims. c1. 294-52 The present invention relates generally to the electroplating art and is more particularly concerned with novel compositions for use in'aqueous acid copper electroplating baths,..vvith-;,novel. baths of this type having unique and b epronerliesfat d wit Process for trodepositing copper involving the use 'of said compositions and-baths and affording special new advantages and results.

Copper, plated from the usual acid bath compositions, is dull and crystalline in appearance, and exhibits poor throwing power of the bath, in that recessed areasof an irregularly-shaped surface are not uniformly covered .bymthe. coppendeppsitf l'flie principal functional difference between, cid copper baths. and coppercyahideplatv.ing formulations; is that the former havej/ery poor throw- ,ing or covering power, while the latter ar'feiice'llent j, in both of these prap'erties; My. invention provides an additivecombination' to acid copper plating baths that permits them to compete commercially with copper cy- ,anide baths v v ith respect to throwing and covering powe i while retaining the well recognized operating. advantagesbf the'f acid 'baths. Thus, my invention provides an acid copper plating bath-that isicor'nmercially competitive with the cyanide bath with respect to uniform covering power, and vthat prorluces a deposit having superior physical properties such as luster, uniformity and smoothness of' surface, ease of tbufling' to a bright finish and homogeneity of structure. ---'lhe-deposits from my new and novel bath composition are particularly suitable for use as bases for subsequent nickel plating, especially for-use prionto pla t ing from the modern bright nickel Modern chromium plated finishes are underlaid with electroplate s of copper and nickel, respectively, on the base metal such as-steel, fonexamplel I'In, this sequence it is important to ,provide a copper plate of superior ..physical properties such as ,unlformi coverage, a very fine crystal structure, smooth, lustrous siirface, dense homo- .geneous, structure,. duetility and. easeof buffing. Even :yvithall their well known deficiencies, cyanide plating baths have. generallyibeen .used for this purpose, because acid bathsjcouldihot produce the quality ofdeposit re quired. Cyanide "copper plating baths usually operate at high temperatures,' are"extremely toxic and unpleasant to operate, require additionagents that produce rinsing problems and interfere with adhesion of the subsequent nickel deposit, produce copper deposits Ithat are difficult to bulf to a satisfactory .finishand, like all cyanide.

plating baths, require expensive waste disposal systems for the destruction 'of cyanide in rinses and tank wastes to v9 str am rel stisa a d s a contamination, which is becoming" an increasingly pressing industrial problem.

BecauseYof these'difiicultie's, man'y'attempts have been made to develop an acid copper plating bath to produce 1 copper deposits or superior physical properties for .use

under nickel: plating.

None of these attempts have i been. entirely successful.

- All depend of; bath addition agents'of varioustypes, some 2,931,750 -Patented Apr. 5, 1950 ice of which produce brittle deposits, some are not stable in thebath, requiring excessive additions and breaking down .into deleterious decomposition products that must be removed from the plating bath frequently by carbon treatment, and some are not stable at temperatures much over 90 F., requiring bath cooling and thereby restricting the operating current densities and hence the producve c'apacityof the bath.

I have now found a combination of addition agents,

which, when present in commercial acid copper plating baths, produce baths of superior covering power, are

stable at high operating temperatures, form no deleterious decomposition products, and produce copper deposits of superior physical properties, as defined above, that are eminently suited for use under subsequent nickel de- .posits from either conventional or proprietary bright V ties.

nickel plating baths. For convenience and to avoid rep etition, the copper plates produced by the baths and processes. of this invention will hereinafter be referred to as copper deposits having superior physical proper- These valuable results are obtainable now for the first time because of my surprising and unpredictable discovcries upon which this invention in all its various aspects is predicated, One of the more basic of these discoveries is that certain organic compounds act synergistically in combination with chloride ion in aqueous acid copper plating baths to produce electrolytes having unique Qcharacteristics and copper depositshaving superior physicalprop'erties, 'as described above. I'have also found that this synergistic effect is not limited to a particular plating bath composition but is obtainable in all commercial acid copper plating baths. However, the con- ,centration of the chloride'ion' must be controlled within 1 a narrow range and there is a critical minimum amount of or concentration of the organic compound in these baths;

Still further, I have found that except for the bromide ion in certain bath additives and bath composiftions of this invention, the chloride ion has no equivalent inits present synergistic effect. There are, however,

. a. numberof satisfactory sources of chloride ion for this purpose although all chlorides are not suitable and some may be quite harmful to copper plating operations. Sim- 'ila'rly, I have found. that the organic compounds contem- QpIated by'thi's invention can be classified and that there are a relativelyflarge number of these compounds which may 'be used successfully in these new baths and copper plating, operations.

In fact, l have found that special advantages are to be obtained by using mixtures of these compounds in the bath additives and plating bath compositions of this invention.

These new acid copper electroplating baths, briefly and generally described, contain a bath-soluble polyalkyl- Qtives contemplated by this invention can be classified as polyalkylene oxides .with 'or without terminallysubstituted radicals. Compounds of this general type are widely used in industry and their methods of preparationare matters .of record, being disclosed in several US. patents, among. which may be cited 1,970,578; 1,922,459; 2,059,273; and 2,213,477. .They are discussed by Stau dinger in Die Hochmolekularen Organischen Verbindungen, 1932, page 287 et seq.

More specificallv the organicadditives contemplated v and undesirable copper deposits.

by this invention may be represented by the general formula R-(CH CH O),,H

in which R is the hydroxyl radical (OH) in the case of n is a numerical value greater than 5.

In order to simplify the nomenclature of this document and avoid needless repetition, the compounds represented by the above general formula that are contemplated by this invention will be referred to as polyoxyethanols,

. and will include the unsubstituted polyethylene oxides as well as those having a terminal substituent, as set forth in detail subsequently. Since the molecular weight of the ethylene oxide group (C H O) is 44, it follows that a the polyoxyethanols of this invention will have calculated molecular weights over 300, the actual figures depending on the values of n and the molecular weights of the substituent radicals.

Polyoxyethanols are stable in acid copper plating baths and form no deleterious decomposition products, thus eliminating this cause for frequent purification of the bath by carbon treatment. Similar compounds have been proposed for use in electro-plating baths, notably by Hofiman for tin plating baths in US. Patent 2,457,152 and by Rochl for lead-tin alloy baths in US. Patent 2,734,025.

Surprisingly enough, the presence of polyoxyethanols in conventional commercial acid copper plating baths produces highly undesirable results unless to these baths t is also added bath-compatible compounds that produce in solution the chloride ion within specifically controlled limits of concentration. By the term bath-compatible is meant bath soluble compounds containing chlorine combined with anions that are either inert or harmless in the acid copper plating bath, such as, for example, hydrogen chloride, sodium chloride, cupric chloride, ammonium chloride, lithium chloride, potassium chloride, and in fact the chloride of any anion that will not codeposit with copper from an acid bath nor adversely affect the deposition of copper from such a bath.

It may be noted here that the chloride ion is not a conventional constituent of commercial acid copper plating baths, nor is copper ever plated commercially from a chloride bath. In fact the chloride ion is generally considered undesirable as a constituent of commercial acid copper plating baths because it lowers the burning range, that is, it accentuates the tendency to form burned or dark, coarsely crystalline deposits at the higher current densities, thus lowering the operating current density range with consequent loss in the production capacity of the bath. For this reason, every effort is made to keep chlorides out of commercial baths. Also the chloride ion is known to act as a poison for most of the additive agents used in acid copper plating, as it partially or completely nullifies their efiects, and therefore it is generally avoided in bath using additive agents.

Thus it will be seenthat the essence of my invention resides in obtaining new, useful and unexpected results by combining in acid copper electroplating baths, two specific types of materials, either of which when present in the bath without the other, produces distinctly inferior It appears that the function of the chloride ion in the baths of this invention is to enable the polyoxyethanol to exert its beneficial efiect upon the plating reactions and the plate formation, while the polyoxyethanol ameliorates practically completely the deleterious effects of the chloride ion on the copper deposit. The novel bath addition agents or additive compositions constituting another aspect of my invention, succinctly stated, consist essentially of between about 10 and about 90 proportional parts of polyoxyethanol, which is soluble in such baths to the extent of at least 0.05 gram per liter, and between about 90 and about 10 parts, respectively, of a bath-compatible: chloride which is similarly soluble and capable of providing a chloride ion concentration in such baths of at least 0.02 gram per liter. Thus the additives of this invention can be specially designed to be used as make-up additions to baths partially depleted during plating op-' erations, and will consist of these same essential sub stances but contain them in different ratios, depending: on the identity of the polyoxyethanols used and the re-- quirements, as explained later.

My new and novel combination of additives functions equally well in the cheaper and more common acid sulfate baths as well as in the newer and more expensive acid fiuoborate baths. The general formulae for these baths are shown in Table I.

TABLE I Compositions of commercial acid copper baths Concentrations in grams per liter (A) Sullate Bath Approx. Preterred Range C S .5H 0 150-250 200 11 509. 45-110 75 (B) Fluoborate Bath Low High 225 450 ffII 15 so H1130; (optional) 15 30 As a general disclosure of my invention, I cite the addition to any acid copper plating bath of the combination of additive agents shown in Table 11 following:

Since'the operating conditions depend on the degree and nature of the agitation employed, both mechanical and air systems being used, the above figures for temperature and cathode current density will of necessity vary considerably therewith relative to' each other, all of which is conventional and well known to those skilled in the art.

Considering again the general formula for the polyoxyethanols of this invention:

in which R is a radical derived from the group comprising phenols, alcohols, ethers, acids and amines, the general relationship between the nature of R and the value for 11 requires further discussion. In these polyoxyethanols, the values for n must be increased as the bath solubility of the'compound from which R is derived decreases. This is necessary in order to provide adequate erallydesirable for my purpose.

-shark-solubi ty.-t inc ewh e trt edrfio w er rsatv tea no it; must be-sufficient to dissolve; enough polyoxyethanol to produce copper" deposits ot-superior physical properties.

' :-For example, if- R-is' derived frommethyl alcohol or ahydrochloric acid, both ofwhich are highly bath soluble, a very low value for n, such-as 6-8-is satisfactory, and wisvrequired for additive action onlyand notfor bath solubility. On the other hand, if ,Ris derived from betanaphthol, which has a definite though low bath solubility,

-n .need be only around 11-15 to produce a satisfactory zbath soluble and effectivepolyoxyethanol, while if R is derived from octylphenol, which ,is much less, bath soluble, n should be above about 15, preferably around 1 -20 to 30 to produce a-.polyoxyethanol of adequate bath solubility and effectiveness. .And ifR is' derived from a highly bath insoluble amine, suchas for example, dehydroabietylamine, n should be over about .40 toobtain a satisfactory .polyoxyethanol. .Itshould be understood of course that this discussion. applies; to polyoxyethanols (that are capable of producing optimum results in ,combinationwith the chloride ion. Less completev but still a useful results can be obtained by. using corresponding -polyoxyethanols of lower n value, in which case they may have lower bath solubility and hence'lessv activity in the bath. It is also sometimes desirable, as explained later, to use mixtures ofpolyoxyethanols in which n is lower than optimumfor a single compound, hence the difiiculty of specifying a particulanvalueor limiting range of values for n for anygiven-substanceis apparent.

It will be noted that the structure of the general formula is similar to that of commercial surfactantsofthe --nonionic type, in which thevalue for-n .is generally in I the low-range specified for the polyoxyethanols of this invention. It is also well known that as the value for n; increases in such products, their surface activity diminadvantageous in compounding additive mixtures for commercial applications to use selectedmixtures of the polyoxyethanols contemplated by this invention Thus the difficulty of specifying an exact value or a limiting range of value for n in the case. of polyoxyethanols containing substituent radicals is apparent. In such cases however,

- becaujse of the bath solubility factor, I generally prefer h to use a relatively high value for r of the order of 20-60,

although for reasons that are readily apparent, I do not desire to be so limited.

, The amount of polyoxyethanolsrequired in solution in the plating bath may vary somewhat with the nature of the substituent radical. In general it is desirable to use .theminimum concentration consistent with satisfactory results or to produce the effects .desired and maintain consistent operating conditions. In the case of polyoxytethanols containing substituent radicals this concentration has been found to be around 0.1 to 0.5 gram per liter, preferred being 0.2-0.3 gram per liter. in the case of the unsubtituted polyoxyethanols somewhat higher concentrationsmay be found desirable. In both cases, substituted and unsubstituted, a reasonable excess of polyoxyethanols in the bath does no harm. Baths containing various concentrations of various polyoxyethanols up to as high as- 30 grams per liter have been-operated successfully. "However such high concentrations are unnecessary, and might be consideredundesirable in some cases onths. generalprinciplethat; theless organic matterpresent-in; a plating bath the, better. T Oiie lof-.the desirable features of this invention, from a functional standpoint, is the low concentration of organic additive constituent required to produce satisfactory results.

Table III following illustrates some oftheorganic compoundsfrom which R of the general formula has been de rived to make polyoxyethanols containing substituent radicals and which have been found satisfactory for. the

- purposes of this invention.

TABLE III 'Approximate optimum Phenols: 1 range for n Phenol V 10-30 Octyl phenol -40 Nonylphenol -50 Beta-naphthol 12-30 Ethers:

' Biphenylether 15-40 Disecondary butyl phenyl ether 20-40 Alcohols:

Methyl alcohol 6-25 Sorbitol p 20-40 Lauryl alcohol 20-40 Acids:

Hydrochloric acid 6-20 Caproic acid 20-60 Oleic acid 20-60 .Stearic acid 7 20-60 Rosin acids 20-60 LAbietic acid 20-60 Amines:

j Ethylene. diamine -60 Rosin amines 40-60 Dehydroabietylamine 40-60 Tertiary-alkyl primary amines The foregoing-Table III is illustrative only and by no means complete as will be evident from a perusal of the references hereinbefore cited'covering the preparation of this type of compounds. It should also be noted that the values given for n are approximate optimum values only. They are shown for purposes of illustration only, and are in no way limiting for reasons already cited.

Theunsubstituted type of polyoxyethanols that have been found most satisfactory for the purposes of this invention are those in whichn of the general formula is about 10 or greater and R is the hydroxyl radical. These materials have calculated molecular weights in excess of V 600, and maygo as high as 20,000. One that I have found to be particularly satisfactory has a calculated molecular weight around 6000 and n approximates 135. As

illustrative of this type of polyoxyethanols thoseshown in Table IV compare average molecular weight with calculated approximate values for n.

It should be realized that in the case of these unsubstituted polyoxyethanols .as well asv inthe case:of-..the polyoxyethanols with a substituent radical, the'commereial ,products aremixtures of compounds the; molecular weights of which vary within commercial limits of manufacture and purification, hence the figures given in this document for molecular weights are average values only and therefore the values for n can only be approximate and also representing average values.

The particular advantage of the unsubstituted type of polyoxyethanols is that they offer all the advantages of synergistic additive action with the chloride ion without lowering the surface tension of the bath, therefore can be used either alone or in mixtures with the substituted type of polyoxyethanols, some of which do lower the surface tension of the bath, so as to regulate the surface tension effect as desired without adversely affecting additive action, as previously mentioned. This permits control of pitting on the deposit when encountered, without producing excessive foaming from air agitation.

Ingeneral, a littlemore of the unsubstituted polyoxyethanols can be used to advantage, and I prefer around 0.5 gram per liter of bath, although I have used as high as 30 grams per liter with excellent results and no ill effect.

One commercial line of the unsubstituted type of polyoxyethanols now available is offered by the Carbide and Carbon Chemicals Company under the designations polyethylene glycols and carbowaxesf Of these, I prefer to use Carbowax 6000 at a bath concentration around 0.5 gram per liter.

As for the other essential ingredient in my new and novel combination of additives for acid copper plating baths, the chloride ion and the bromide ion are practically equivalent and are unique among cations as being the only ones that work synergistically with my organic polyoxyethanols to produce the copper deposits having superior physical propertiesresulting from this invention. Further, the critical amounts of chloride ion and bromide ion are the same on a chemical equivalent or molal basis. Thus the values given for the chloride ion can be converted to values for the bromide ion by multiplying by the ratio of the chemical equivalent or molecular weights: 79.9/ 35.5 or approximately 2.25. The chemical equivalent on a molal basis in each case corresponds to a range of 0.00055 to about 0.028 mol of either chloride ion or bromide ion. The bromine salts that are bathcompatible and effective in the baths of this invention correspond to the chlorine salts stated above to be suitable or preferred for use herein, on a chemical equivalent or molal basis.

Contrary to what might be expected, none of the acids or salts of the other two halogens have the synergistic effect of this invention. However, this effect can be obtained by using mixtures of chlorides and bromides as long as the aggregate of chloride and bromide ions in the plating bath is within the aforesaid critical range for chloride alone on a molal equivalent basis and as long as there is no interaction between the chloride and bromide compounds or with other bath constituents resulting in the formation of substances having detrimental effect upon the copper plating operations or the resulting products.

In its method aspect this invention in general comprises the step of adding to an acid copper electroplating bath prior to its use a bath-compatible chloride and thereby establishing a chloride ion concentration in the bath of between 0.02 and about 1.0 gram per liter, and also adding to the bath a polyoxyethanol of molecular weight greater than 300 and thereby establishing in solution in the bath an amount of said polyoxyethanol effective to act synergistically with the. chloride ion to produce uniform copper deposits of superior physical properties.

It is also a process of this invention to maintain in the plating bath synergistic quantities or concentrations of chloride or bromide ion and polyoxyethanol. This involves the step of periodically adding to the bath a makeup quantity of one or both the synergistic constituents or compounds which function as sources of said chloride ion or polyoxyethanolin solution. In preferred practice the additions will be in the form of mixtures specially prepared for restoring depleted baths and containing therefore between about 10 and about proportional parts of polyoxyethanol and between about 90 parts and about 10 proportional parts of bath-compatible chloride.

The novel combination process or method of my. invention comprises in general the preparation of the plating bath containing the synergistic quantities of organic compound and chloride ion, electro-depositing copper from the bath, and as the bath becomes depleted of synergistic amounts of said organic compound and chloride periodically adding a make-up amount of the depleted bath' substituents.

The chloride ion can be added to the bath in theform of any bath-compatible compound as hereinbefore explained. For convenience I prefer to use hydrochloric acid, sodium chloride or cupric chloride. The chloride concentration that I prefer to maintain is around 0.1 gram of Cl per liter. This can be done by frequent bath analysis, the procedures for determining chloride being simple and well known to those skilled in the art, and a bathcompatible chloride added as required. The preferred concentration is not critical, but should not be allowed to drop below 0.02 gram of Cl per liter which I consider to be the extreme lower limit. For safe, flexible operation I prefer to keep the chloride concentration above 0.05 gram of Cl per liter, usually around 0.1 gram of Cl per liter. There is no operational advantage to be gained in maintaining the chloride concentration over 0.1 gram of Cl per liter except possibly to minimize the analytical control operations, however it does no harm to the cathode deposit to have the chloride as high as 1.0 gram of Cl perliter. However, as the chloride content of the bath exceeds (about) 0.5 gram of Cl per liter, there is a growing tendency for the anodes to polarize, especially at high current densities, and this anode effect is the limiting factor in setting and maintaining the maximum practical operating chloride concentration.

Chloride is eliminated from the bath at the anode in the form of insoluble cuprous chloride (CuCl) which precipitates in the anode sludge. The rate of chloride elimination varies greatly with chloride concentration,

anode current density and bath temperature, but once determined for a given installation, it can serve as a basis for chloride replacement, thus diminishing the number of analyses required. Under average commercial operating conditions I have found the rate of chloride precipitation to be of the order of 0.01 ounce of chloride per ampere hour per 1000 gallons of bath.

Since the polyoxyethanols of this invention are bath stable and only the chloride of my combination of additives is lost by anodic precipitation, it is possible to operate a bath containing adequate concentrations of polyoxyethanols for considerable periods of time by periodic additions of chloride to replace that which is lost. Such bath operation is considered to be within the scope of this invention.

Acid copper plating baths in which the chloride ion is maintained between 0.02 and 1.0 gram of chloride per liter in order to secure the synergistic effects of organic additive agents are new and novel and in themselves constitute one phase of this invention.

The following Examples l-7 inclusive specifically illustrate some of the preferred formulations of my invention:

'in less or greater amounts as convenient. -polyoxyethanols may be used at higher concentrations nxaitppn a .jfirarnsperfl ter CuSO .5H O 2 H2 04 V r HC1 (100%) I v v I 0.1. Polyoxyethanol in which R is the OH group and ,n approximates 135 0.5

EX MPLE 3 CuSO .5H O ,-200 H 50 V {/5 'NaCl p 0.17 Polyoxyethanol in which R=octylphenyl ands ,r approximates 30 0.3

EXAMPLE 4 CuSO SH O 200 1 2 4 '75 CuCl .2H O 0.25 --Polyoxyethanol in which R is derived from biphenyl ether and n approximates 25 0.3

EXAMPLE 5 aS, 4 i l 75 CuCl ,2H O 0.25 Polyethyleneglycol chloride 0.3

EXAMPLE 6 -H SO V -75 CUCIZZHQQ Methoxypolyethylene glycol 0.3 EXAMPLE 7 1-1-1,-fi--t--'1"f-r-1---r-*: uuqb c 1 t, -3 .Bo c a (op approximates 40 0.3

Average operating conditions for all of above, ex-

emples: --*Temperature, 0 F. 120-140 -Average cathode current-density, amperesrper -s q.' ft. 100-200 Agitation, optional.

Since commercial operators of acid copper plating baths make up their solutions from chemicals or conceninvention intproper proportions so that when added to the plating bath in correct amounts it will produce a copper deposit having superior physicalproperties. I have made a convenient liquid additive for acid copper plating baths by dissolving in water:

i Percent Polyoxyethanol in which R is derivedfrom beta-naphthol and n=15 Q,-. 6 Cupric chloride (CuCl .2H O) 6 This mixture or liquid additive was added to commer- -cial acid copper plating baths in the proportion of about 4 cc. per liter or about one-half fluid ounce per gallon.

*Itis apparent that more dilute or more concentratedsolutions of the combined additives could be made and used Since some than others, while the chloride component of the bath is best held at around 0.1 gram chloride per liter, the ratio of polyoxyethanols to chloride will vary with the identities ofthe respective ingredients and-the concentrations used.

awhile formulations of -the various polyoxyethanols and batheompatihle ehloiidessimilar to-the above-ma? be made and, sold for; initial-'installations,- it willobserved that since the chloride is lost by anode precipitation and bath drag-out while the polyoxyethanol; is l ost by drag-out only, maintenance additions shouldbe corsumption data, and such formulations will necessarily -vary considerably, but I have found that the following proportions will fit most cases, and canserve until ac- ,curate proportions are worked out.

Polyoxyethanols grams per liter HCl (cone) cc. per liter....w

one-half fluid ounce per gallon of bath, in which case the.

addition would put about 0.1, gram of chloride per liter into the bath. Wide variations may be encountered in the relative rates at which polyoxyethanols and chloride are lost and must be replaced, hence thecompositions of cult to specify exact limits of composition for such additive mixtures. However it will generally be found that for all practical purposes they will fall withinthe following range of proportionate parts:

: Parts "Polyoxyethanols 90-10 Bath-compatible chlorides ,l0 90 It should be understood that these proportionate parts represent the numerical ratio of the constituents, and if present in solution, these figures do not include the solvent, since it is apparent that the ratio of constituents is V the important factor, not the actual concentration in solution, as such mixtures may be dissolved in water to any convenient concentration and directions furnished the plater as to how to add the solution to the bath to best advantage.

If desired, combinations of additives for initial-installation .and for maintenance comprising selected ,poly- ,oxyethanols and bath-compatible chlorides may be compounded in theabove tabulated proportions and offered to the plater in concentrated or dry form so that he can ;with polyoxyethanols. For example, bath-soluble polyoxypropanols are suitable for this purpose, producing make his own additive solutions by dissolving them,in water, or he can add them directly to the bath.

The above illustrations will make clear to those skilled in the art all the principles involved in compounding ad'- ditive mixtures contemplated by this invention.

' To the extent that they are sufficiently soluble in aqueous acid copper plating baths other polyalkylene oxide compounds may be used instead of or together the synergistic results described above.

Wherever in this specification or in the appended claims parts, proportions or percentages are recited, reference is tothe weight-basis rather than the volume basis itbeing understood that equivalents or modifications of,

scribed embodiments of the invention may be made without departing from the scope of the invention as set forth 1 in what is claimed:

What is claimed is: 1. An aqueous acid copper electroplating bath containing a bath-soluble polyoxyethanol having a molecular weight greater than 300, and a bath-compatible chlophysical properties.

2. An aqueous acid copper electroplating bath containing a bath-soluble polyoxyethanol having a molecular weight greater than 300 consisting of polyethylene oxide terminally substituted with beta-naphthol, and a bath-compatible chloride providing a chloride ion concentration in the bath of between 0.02 and about 1.0 gram per liter, said polyoxyethanol being present in solution in the bath in amount effective to act synergistically with the chloride ion in the bath to produce uniform copper deposits of superior physical properties.

3. An aqueous acid copper electroplating bath containing a bath-soluble polyoxyethanol having a molecular weight greater than 300 consisting of polyethylene oxide terminally substituted with a phenol, and a bathcompatible chloride providing a chloride ion concentration in the bath of between 0.02 and about 1.0 gram per liter, said polyoxyethanol being present in solution in the bath in amount effective to act synergistically with the chloride ion in the bath to produce uniform copper deposits of superior physical properties.

4. An aqueous acid copper electroplating bath containing a bath-soluble polyoxyethanol having a molecular weight greater than 300 consisting of polyethylene oxide terminally substituted with an ether, and a bathcompatible chloride providing a chloride ion concentration in the bath of between 0.02 and about 1.0 gram per liter, said polyoxyethanol being present in solution in the bath in amount effective to act synergistically with the chloride ion in the bath to produce uniform copper deposits of superior physical properties.

5. An aqueous acid copper electroplating bath containing a bath-soluble polyoxyethanol having a molecular weight greater than 300 consisting of polyethylene oxide terminally substituted with an alcohol, and a bath-compatible chloride providing a chloride ion concentration in the bath of between 0.02 and about 1.0 gram per liter, said polyoxyethanol being present in solution in the bath in amount effective to act synergistically with the chloride ion in the bath to produce uniform copper deposits of superior physical properties.

6. An aqueous acid copper electroplating bath containing a bath-soluble polyoxyethanol having a molecular weight greater than 300 consisting of polyethylene oxide terminally substituted with an acid, and a bath-compatible chloride providing a chloride ion concentration in the bath of between 0.02 and about 1.0 gram per liter, said polyoxyethanol being present in solution in the bath in amount effective to act synergistically with the chloride ion in the bath to produce uniform copper deposits of superior physical properties.

7. An aqueous acid copper electroplating bath containing a bath-soluble polyoxyethanol having a molecular weight greater than 300 consisting of polyethylene oxide terminally substituted with an amine, and a bathcompatible chloride providing a chloride ion concen-.

I deposits of superior physical properties.

-8. An aqueous acid copper electroplating bath containing a bath-soluble polyoxyethanol consisting. of vp11 unsubstituted polyethylene oxide having a molecular weight greater than 600, and a bath-compatible chloride providing a chloride ion concentration in the bath of between 0.02 and about 1.0 gram per liter, said polyoxyethanol being present in solution in the bath in amount effective to act synergistically with the chloride ion in the bath to produce uniform copper deposits of superior physical properties. 7

9. An aqueous acid copper electroplating bath containing a mixture of bath-soluble polyoxyethanols having molecular weights greater than 300, and a bathcompatible chloride providing a chloride ion concentration in the bath of between 0.02 and about 1.0 gram per liter, said polyoxyethanols being in aggregate in solution in the bath in amount effective to act synergistically with the chloride ion in the bath to produce uniform copper deposits of superior physical properties.

10. An aqueous acid copper electroplating bath containing a bath-soluble polyoxyethanol having molecular weight greater than 300, and a bath compatible com pound providing concentration in the bath of between 0.00055 and about 0.028 gram mols per liter of an ion selected from the group consisting of chloride ion and bromide ion, said polyoxyethanol being in solution in the bath in amount effective to act synergistically with the said ion in the bath to produce uniform copper deposits of superior physical properties.

11. An aqueous acid copper electroplating bath containing a bath-soluble polyoxyethanol having molecular weight greater than 300, and a bath-compatible bromide providing a bromide ion concentration in the bath of between 0.045 and about 2.25 grams per liter, said polyoxyethanol being in solution in the bath in amount effective to act synergistically with the bromide ion in the bath to produce uniform copper deposits of superior physical properties.

12. An aqueous acid copper electroplating bath containing a mixture of bath-soluble unsubstituted polyethylene oxide having molecular weight greater than 600, and a bath-compatible bromide providing a bromide ion concentration in the bath of between 0.045 and about 2.25 grams per liter, said polyethylene oxide being in solution in the bath in amount effective to act synergistically with the bromide ion in the bath to produce uniform copper deposits of superior physical properties.

13. An addition agent composition for use in aqueous acid copper electroplating baths comprising as its essential ingredients between about 10 and about partsof a polyoxyethanol which is soluble in such baths to the extent of at least 0.05 gram per liter and has a molecular weight in excess of 300, and between about 90 parts and about 10 parts, respectively, of a bath-compatible chloride which is sufficiently soluble in such baths to provide a chloride ion concentration in the baths of at least 0.02 gram per liter.

14. An addition agent composition for use in aqueous acid copper electroplating baths comprising as its essential ingredients between about 10 and about 90 parts of a polyoxyethanol which is soluble in such baths to the extent of at least 0.05 gram per liter and has a molecular weight in excess of 300, and between about 90 parts and about 10 parts, respectively, of a bath-compatible bromide which is sufiiciently soluble in such baths to provide a bromide ion concentration in the baths of at least 0.045 gram per liter.

15. An addition agent composition for use in aqueous acid copper electroplating baths comprising as its essential ingredients between about 10 and about 90 parts of an unsubstituted polyethylene oxide which is soluble in such baths to the extent of at least 0.05 gram per liter and has a molecular weight greater than 600, and between about 90 parts and about 10 parts, respectively, of a bath-compatible chloride which is sufliciently soluble in 13 such baths to provide a chloride ion concentration in the baths of at least 0.02 gram per liter.

16. In a process for the electrodeposition of copper the step comprising effecting electrodeposition from an aqueous acid copper plating bath containing in solution 0.05 gram per liter of a polyoxyethanol and a bathcompatible chloride in suflicient amount to provide a bath concentration of from 0.02 to about 1.0 gram of chloride ion per liter.

17. In a process for the electrodeposition of copper from an aqueous acid copper plating bath containing a polyoxyethanol in an amount sufficient to produce in the presence of chloride ion a copper deposit having superior physical properties, the step of maintaining the chloride ion concentration within the range of from 0.02 to about 1.0 gram per liter by adding a bath-compatible chloride.

18. The method of electroplating copper from an aqueous acid copper plating bath which comprises the steps of adding to the bath prior to its use a bath-compatible chloride and thereby establishing a chloride ion concentration in the bath of between 0.02 and about 1.0 gram per liter, adding to the bath a polyoxyethanol of molecular weight greater than 300 and thereby establishing in solution in the bath an amount of said polyoxyethanol effective to act synergistically with the chloride ion to produce uniform copper deposits of superior physical properties,

electro-dcpositing copper from the bath, and as the btith becomes depleted of synergistic amounts of chloride ion and polyoxyethanol periodically adding to the bath a mixture containing between about 10 and about parts of the said polyoxyethanol and between about 90 and about 10 parts, respectively, of the said bath-compatible chloride and thereby maintaining the concentration of chloride ion and polyoxyethanol in solution in the bath in the synergistic range.

19. An aqueous acid copper electroplating bath containing a bath-soluble polyoxyethanol chloride having a molecular weight greater than 300, and a bath-compatible chloride providing a chloride ion concentration in the bath of between 0.02 and about 1.0 gram per liter, said polyoxyethanol chloride being present in solution in the bath in amount effective to act synergistically with the chloride ion in the bath to produce uniform copper deposits of superior physical properties.

References Cited in the file of this patent UNITED STATES PATENTS 2,472,393 Avallone et a1. June 7, 1949 2,602,774 Beaver July 8, 1952 2,742,412 Cransberg et a1 Apr. 17, 1956 2,762,762 Donahue Sept. 11, 1956

Claims

10. AN AQUEOUS ACID COPPER ELECTROPLATING BATH CONTAINING A BATH-SOLUBLE POLYOXYETHANOL HAVING MOLECULAR WEIGHT GREATER THAN 300, AND A BATH COMPATIBLE COMPOUND PROVIDING CONCENTRATION IN THE BATH OF BETWEEN 0.00055 AND ABOUT 0.28 GRAM MOLS PER LITER OF AN ION SELECTED FROM THE GROUP CONSISTING OF CHLORIDE ION AND BROMIDE ION, SAID POLYOXYETHANOL BEING IN SOLUTION IN THE BATH IN AMOUNT EFFECTIVE TO ACT SYNERGISTICALLY WITH THE SAID ION IN THE BATH TO PRODUCE UNIFORM COPPER DEPOSITS OF SUPERIOR PHYSICAL PROPERTIES.