US2612469A

US2612469A - Rapid fine-grained copper electrodeposition

Info

Publication number: US2612469A
Application number: US51639A
Authority: US
Inventors: Frederick F Reisinger
Original assignee: Wire Coating and Manuf Co
Current assignee: Wire Coating and Manuf Co
Priority date: 1948-09-28
Filing date: 1948-09-28
Publication date: 1952-09-30
Anticipated expiration: 1969-09-30

Description

Patented Sept. 30, 1952 Company; Cleveland,

Copper plating by means of copper cyanide is quite'anoldindustry; and from time to time de' tailed improvements in' bath compositions have been suggested, such as" the Rochelle salt'copper bath, pyrophosphate copper, etc., but a'fun'damental handicap has remained that plating. could notbe operated at high current'densities as desirable' for volume production. Even plating with as'low'a's 12-15 amperes per sq. ft. has'resulted'in'd'eposits moreor less rough and pitted if'a thickness 0.001" or more was required. A' bath vfor electrodeposition which can permit high operating rates, with current densities of 30 or moreamperes persq. ft., and with production of bright 'fine grained deposits has accordingly been much desired in theindustry. .In accordance with the present invention, an improved electrodeposition thus with high current density and volume production of smooth fine-grained bright deposits in suchthicknesses as may be desired, is now possible Other objects and advantages of the invention will appear in the following description.

To the'accompli'shment of the foregoingand related ends, the inventionthencomprisesfihe features hereinafter fully described, andfpj'a'rtieularly pointed out in the claims, the followin'g description setting forth in'detail certain illustrative embodiments of theinvention, these being indicative however of but a few of the various ways in which thepprinciple of theinvention may be employed.

In general, copper is supplied by a bath of copper cyanide type, and of alkaline category. Fundamentally, in the present invention the bath is provided with a reaction product of a diazo salt and sulphur, such product being dissolved and made up with the desired copper cyanide and other ingredients for the operating bath.

For the preparation of the diazo derivative, the starting point is a primary arylamine, preferably anthranilic acid, but there may be also applied aniline and its homologs, the toluidines and xylidines, also benzylamine, etc. Thus for instance the anthranilic acid or other arylamine is made up in an acid solution, for instance hydrochloric, although sulphuric or other equivalent mineral acids may be used, then sodium nitrite or equivalent diazotizing agent in solution is applied. The diazo salt as thus provided in solution is reacted with sulphur in a precipitating form, such as hydrogen sulphide, sodium sulphide, etc. Conveniently, hydrogen sulphide is passed into the solution for around two hours,

hi0; a corporation of Application spmtai2s;.1948;; Serial-No. 51,639

(;laims. (o1. em -52) or" as necessary to complete precipitation. The

resulting precipitatei which may be designated" a reaction product of asulphide on a diazosalt of a primary 'arylami'ne, is vacuum-filtered as dryaspossible; and the filter cake is dissolved and withfiurther advantage is; boiledin' water containingt triethanolamine. After cooling and filtering, theffiltr'atemixed D coppencyanide, sodium cyanide andsod'ium hy dioxide; and is boiled, cooled'and filt'eredi a' wetting agent; such'for instance as a sulphate of a longchain alcohol, preferablyof 1 0'-14- car bon atoms, dioctyl sodium sulphosuccinate, al-

karyl sodium su'lphonates; etc: is'added, and degallon or 3.785 liters.

sirably the final volume is made" up withaddi-- tionof water as necessary," to a convenient concentration stock solution. A'desired amount of this concentrationis: addedtothe cyanide coppe bath whichis to'be-op'erated;

With" such bath, high current density is 'em'-' ployed; conveniently 3Q-50' a'mperes per sq; ft: The copper'deposited" is smooth, fine-grained, and bright, and thickness of. 01001 can thus be readily obtained in: about 15' minutes. j

'FOI" example: '1'.08 kg? of anthranilic acid is dissolved inf1'.62 liters of water and 1 .19- of concentratedhydrochloric'acid. Then 810' gms: of sodium nitrite in 7.6' liters of water is added. Aiter the diazotizing action is completed, a stream of hydrogen sulphide is passed through thesolution for" about two hours; The resulting' precipitate is filtered and vacuum sucked dry as much as possible. This sulphide-precipitated diazo compound provides the active agent in my high-speed plating bath. The filter cake is then dissolved and boiled for about 30 minutes in a solution of 5.8 liters of triethanolamine in 29 liters of water. The solution is cooled and filtered. The filtrate is mixed with 10.16 liters of a solution of the following composition: 392 gms. of copper cyanide and 438 gms. of sodium cyanide and 99 gms. of sodium hydroxide per to a boil, then cooled and filtered. And to the filtrate 210 cc. of a sulphate of long chain alcohol wetting agent is added and the final volume is made up to 24 gallons or 90.84 liters. This stock solution is then employed by adding to the copper cyanide bath for operation. For instance, to cc. of the stock solution is added for each gallon of any copper cyanide electrodeposition Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the with'a solution-- of This mixture is brought,

features stated in any of the following claims, or the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention:

1. In a process of preparing a bath for electrodepositingcopper, dissolving anthranilic acid in hydrochloric acid solution, reacting upon the same with a diazotizing agent, then precipitating by Has, de-watering the precipitate, dissolving the precipitate and water, cooling, filtering, containing copper cyanide, sodium cyanide and sodium hydroxide, boiling, cooling, filtering, adding a wetting agent, making to a stock volume with water, and adding a minor proportion of such stock solution to an electrodeposition bath containing copper cyanide, sodium cyanide and sodium hydroxide.

. 2. In a process of preparing a bath for electrodepositing copper, forming a diazo salt of a primary arylamine of the group consisting of anthranilic acid, aniline, toluidines, xylidines and benzylamine, in a mineral acid solution, precipitating by hydrogen sulphide, de-watering the precipitate, dissolving the precipitate and boiling in triethanolamine and water, cooling, filtering, mixing with a solution containing copper cyanide, sodiumcyanide and sodium hydroxide, boiling,

' cooling, filtering, adding a wetting agent, making to a stock volume with water, and adding a minor proportion of. such stock solution to an electrodeposition bath containing copper cyanide, sodium cyanide and sodium hydroxide.

, 3. In a process of preparing a bath for electrodepositing copper, forming a precipitate by reacting on a solution of diazo salt of a primary arylamine of the group consisting of anthranilic acid, aniline, toluidines, xylidines and benzylamine, with a sulphide precipitant of the group consisting of hydrogen sulphide and sodium-sub boiling in triethanolamine and mixing with a solution arylamine of the group consisting of anthranilic acid, aniline, toluidines, xylidines and benzyiamine, by a sulphide precipitant of the group consisting of hydrogen sulphide and sodium sulphide, de-watering the precipitate, dissolving the precipitatein water containing triethanolamine, and supplying such solution to a'copper cyanide electrodeposition bath. 5. In a process of the character described, electrodepositing copper from a solution which contains copper cyanide, sodium hydroxide, and a reaction product of a sulphide of the group consisting of hydrogen sulphide and sodium sulphide on a diazotized primary arylamine of the group consisting of anthranilic acid, aniline, toluidines, xylidines and benzylamine, said reaction product as a precipitate being dissolved in water containing triethanolamine.

6. A plating bath of aqueous copper cyanide and sodium hydroxide, including the reaction product of a sulphide of the groupconsisting of hydrogen sulphide and sodium sulphide on diazotized anthranilic acid, said reaction product as a precipitate being dissolved in water containing triethanolamine. V v

'7. An electrodeposition bath including copper cyanide, sodium hydroxide, and the reaction product of a sulphide of the group consisting" of hydrogen, sulphide-and sodium sulphide on a diazotized primary arylamine of the group con sisting of anthranilic acid, aniline, toluidines,. xylidines, and benzylamine, said reaction product as a precipitate being dissolved in Watercontaim ing triethanolamine. f

' FREDERICK F. REISINGER;

REFERENCES CITED The following references are of record in the file of this patent:

Claims

7. AN ELECTRODEPOSITION PATH INCLUDING COPPER CYANIDE, SODIUM HYDROXIDE, AND THE REACTION PRODUCT OF A SULPHIDE OF THE GROUP CONSISTING OF HYDROGEN SULPHIDE AND SODIUM SULPHIDE ON A DIAZOTIZED PRIMARY ARYLAMINE OF THE GROUP CONSISTING OF ANTHRANILIC ACID, ANILINE, TOLUIDINES AS A PRECIPITATE BEING DISSOLVED IN WATER CONTAINING TRIETHANOLAMINE.