FR2538815A1 - PROCESS FOR FORMING, BY ELECTROLYSIS, A COPPER COATING ON A SUBSTRATE FROM A CYANIDE-FREE BATH, AND ANODE FOR CARRYING OUT SAID METHOD - Google Patents

Abstract

A CYANIDE-FREE ELECTROLYTE AND A PROCESS FOR DEPOSITING AN ADHESIVE, DUCTILE AND FINE GRAIN COPPER COATING, HAVING A THICKNESS ORDINARILY BETWEEN 0.0038 MM AND ABOUT 0.127 MM, ON FERROUS-BASED CONDUCTIVE SUBSTRATES COPPER, BASED ON ZINC AND THE ANALOGUE. THE ELECTROLYTE CONTAINS CONTROLLED EFFECTIVE AMOUNTS OF COPPER ION COMPLEX WITH AN ORGANOPHOSPHONATE CHELATION AGENT, ALKALINE CARBONATE AS BUFFER AND BATH STABILIZATION AGENT, HYDROXYL IONS TO PROVIDE PRECALIN A PH OF COTE ANCHORING AGENT. THE COPPER COATING IS APPLIED BY ELECTROLYZING THE PREVIOUSLY MENTIONED ELECTROLYTE USING A COMBINATION OF A SOLUBLE COPPER ANODE IN THE BATH AND AN INSOLUBLE FERRITE ANODE TO PROVIDE A SURFACE RATIO OF COPPER ANODE SURFACE OF FERRITE ANODE INCLUDED IN A RANGE OF ABOUT 1: 2 TO ABOUT 1: 6.

Description

25388 15

  1. The use of salts made up of cyanide

  in copper coating electrolytes has become

  environmentally unfavorable due to ecological considerations As a result, a large number of electrolytes not made up of cyanide for various metals have previously been proposed for use as substitutes for their cyanide counterparts Industrial employees in a classic way For example, the American patent n

  3,475,293 describes the use of certain diphosphona-

  tes for the electrolytic coating of divalent metal ions; US Patents 3,706,634 and 3,706,635 describe the use of combinations of ethylenediaminetetra (methylene phosphonic acid),

  1-hydroxyethylidene-1-l-diphosphonic acid, and ami

  notri (methylene phosphonic acid) as well as suitable complexing agents for metal ions in the bath; the american patent n

  3,833,486 describes the use of formal chelating agents

  water-soluble phosphonate mes for ions 2.

  metallic o the bath also contains at least one oxy-

  strong, while U.S. Patent No. 3,928,147

  describes the use of an organophos-chelating agent

  phore for the pretreatment of zinc die-cast parts before electrolytic coating with electrolytes of the type described in American patents N O

  3,475,293, N O 3,706,634 and N O 3,706-635.

  While the electrolytes and the processes-

  written in the aforementioned US patents

  have provided satisfactory electrolytic deposits

  under carefully controlled conditions, these electors

  trolytes and these processes have not received widespread industrial acceptance as a result of one or more

  several problems associated with putting them into practice.

  A main problem associated with these prior art electrolytes has been the inadequate adhesion of copper deposition to zinc and zinc alloy substrates. Another problem relates to the sensitivity of

  these electrolytes in the presence of contamination products

  tion such as cleaning products, so-

  nickel coating solution, coating solutions

  chromium and metallic zinc ions introduced

  in the electrolyte during standard industrial practice

  Yet another problem is the harmful nature of

  strong oxidants used in some of these electrolytes

your prior art.

  The present invention overcomes many pro-

  problems and disadvantages associated with coating solutions

  copper of the prior art, free

  cyanide, by proposing a process using an electro

  trolyte which is cyanide free providing an environmentally controllable system which will function to produce an adherent copper deposit on conductive substrates including steel, brass and zinc based metals only castings 3.

  under pressure in zinc and the like; which will produce effective-

  deposits of fine-grained ductile copper at thicknesses usually ranging from about 0.00038 mm to about 0.127 mm; which is more tolerant of the presence of reasonable concentrations of contamination products such as cleaning, nickel salts and chromium coating solutions,

  and metallic zinc ions as normally intro-

  duit in a coating bath in a practice

  o 10 that industrial, and which is an efficient operation

  This and economical The invention further includes a new

  old insoluble alloy anode used in the setting

in practice of the process.

  The advantages of the present invention are-

  dyed according to aspects of the process using an electro

  cyanide-free aqueous trolyte containing quantities

  controlled copper ions, a chelating agent

  lation formed of organophosphonate, a buffering agent,

  hydroxyl and / or hydrogen ions to provide p H al-

  from a moderately acidic p H to a moderately alkaline p H, and optionally, but preferably, a wetting agent Copper ions can be introduced by a copper salt compatible with the bath and soluble in the bath, to provide a concentration of cupric ion in sufficient quantity to deposit the copper electrolytically, and generally ranging from a value also

  low as about 3 to as high as-

  about 50 grams per liter (g / l) under conditions

  The chelating agent formed of organophosphona-

  te is a compound selected from the group consisting of aci-

  l-hydroxy-ethylidene-l, i-diphosphonic (HEDP) in itself

  even present in an amount of about 50 to about 500 g / l,

  a mixture of HEDP and aminotri (methylene phospho-

  nique) (ATMP) o 1 HEDP is present in an amount of at least

  about 50% by weight relative to the mixture, and a mixture

  4. ge of HEDP and ethylenediamine tetra (methylene phosphonic acid) (EDTMP) o HEDP is present in an amount of at least about 30% by weight relative to the mixture, as well as their partial salts soluble in the bath and bath compatible When mixtures of HEDP and ATMP or HEDP-and EDTMP are used as the chelating agent instead of HEDP itself, reduction of the chelating agent can be used as a result of the greater chelation capacity of ATMP compounds and

  EDTMP compared to that of 1 HEPD The concentration

  tration of the organophosphona-based chelating agent

  will be included in a range related to the quan-

  tity of copper ions present in the bath and is ordinarily

  controlled to provide an excess of the

  lation with respect to the copper ions present.

  In addition to the above, the bath contains a suitable compound such as carbonates, acetates,

  and / or alkali metal borates as stabilizing agent

  addition as well as a buffering agent which is present in

  amount usually from at least about 5 to about

  100 g / l, amounts of at least about 20 g / l being

  required in most cases The bath contains in-

  be hydroxyl and / or hydrogen ions to provide an electrolyte having a p H ranging from moderately acidic to p H

  (p H 6) to a moderately alkaline p H (p H 10.5), a p H of

  about 9 to about 10 being usually preferred The

  bath can optionally and preferably contain

  in addition, a wetting agent soluble in the bath and compatible with the bath present in an amount up to

about 0.25 g / l.

  According to the aspects of the process of the present invention

  tion, the cyanide-free electrolyte as described above

  cédemment is used for the electrolytic deposit of a thin coating of copper adherent, ductile, grain

  thin on conductive substrates comprising

  5. ferrous-based trats such as steel, -the substrates to

  copper base such as copper, bronze and milk

  tonet of zinc-based substrates comprising pie-

  these zinc die castings The substrate to be coated is impregnated

  ge in the electrolyte in the form of a cathode and an anode

  made of soluble copper in combination with an anode-ferri-

  insoluble te is used to provide a ratio of copper anode to ferrite anode of approximately 1: 2

  at approximately 1: 6 The electrolyte is subjected to electrolyte-

  se by current flow between the cathode and the anode for a period of time of approximately 1-minute up to a time as long as several hours and even days to deposit the desired thickness of copper on

  the cathode substrate The bath can be turned on

  operating at temperatures ranging from about 380 C to-

  about 711 C, temperatures from about 430 C to about

  600 C being preferred The particular temperature em-

  folded will vary depending on the specific bath composition to optimize coating characteristics The bath

  can be put into operation under a density of

  rant from about 0.1 to about 8.0 A / dm, depending on the composition

  tion of the bath, using a cathode / anode ratio

  about 1: 2 to about 1: 6

  surprisingly that uniform deposits, adhered

  rents and fine grains are obtained by electrifying the

  substrates before immersion in the electrolyte In the.

  in the case of zinc-based substrates, the electrification of the part - at a voltage of at least about 3 volts

  proved to be necessary to obtain a satisfactory adhesion

  copper deposition Function parameters

  specific and the specific composition of the elec-

  trolyte will vary according to the type of base metal coated, the desired thickness of the copper coating to be deposited, and the availability in time taking into account the others

  integrated coating and rinsing operations.

  6. According to another aspect of the process of the present invention, the cyanide-free electrolyte as described above is used for the electrolytic deposition of a thin coating of adherent, ductile and fine-grained copper on conductive substrates comprising subs - ferrous-based trats, such as steel, copper-based substrates-such as copper, bronze and brass, and zinc-based substrates comprising zinc die-cast parts The substrate to be coated is immersed in the electrolyte in the form of a cathode and an anode in

  soluble copper in combination with a nickel anode-

  insoluble iron is used to provide a ratio of over-

  copper facesanode / nickel-iron alloy anode of approx.

  1 2 to about 4: 1 The electrolyte is subjected to the elect

  trolysis by current flow between the cathode and the ano

  of for a period of time of approximately 1 minute until

  as long as several hours and even days to deposit the desired thickness of copper on the

  cathodic substrate The bath can be operated

  ment at a temperature ranging from about 380 C up to

  about 710 C, temperatures from about 430 C to about 600 C

  being preferred The particular temperature employed will

  will laugh according to the specific composition of bath for opti-

  set coating characteristics The bath can be operated at a current density of approximately 0.1 to approximately 8.0 amps per square decimetre

  (A / dm) according to the composition of the bath using a cathode ratio

  from / anode usually from about 1: 1 to about 1: 6.

  It has surprisingly been discovered that uniform or-deposits

  my members and fine grain are obtained in electrical

  the substrates before immersion in the electrolyte.

  In the case of zinc-based substrates, the electrifica-

  tion of the part under a tension of at least approximately

  3 volts was necessary to obtain adhesion

  satisfactory copper deposit parameters Parameters 7.

  of the specific composition of the electrolyte

  You will vary depending on the type of base metal coated, the desired thickness of the copper coating to be deposited, and time availability taking into account other integrated coating and rinsing operations.

  The present invention further provides a new

  velle nickel-iron insoluble anode which is used in the process in connection with a soluble copper anode,

  according to controlled anode surface ratios obtained

  thus holding the oxidizing medium desired to maintain.

  appropriate coating conditions and to obtain

  electrolytic deposits of copper having the characteristics

  desired characteristics The insoluble nickel alloy anode

  iron is preferably of a heterogeneous construction (com-

  posite) comprising a conductive-central core on which is

  linked the electrolytic deposition of nickel-iron alloy adhered

  rent, deposit containing approximately 10% to approximately 40% by weight of iron in the alloy and approximately 0.005 to approximately 0.06% of sulfur The core is composed of metals

  such as copper, aluminum, iron and other al-

  conductive bonding among which copper itself constitutes the preferred core material The coating or

  nickel-iron alloy overlay on the core is

  be characterized in that it is substantially non-porous and can have a thickness as small as 0.0254 to

0.0508 mm.

  Additional advantages of this

  invention will appear on reading the description

  tion of the preferred embodiments in relation

with the attached examples -

  The present invention will now be described in relation to the accompanying drawings in which:

  Figure 1 is a schematic perspective view

  tive, partially in section, illustrating a coating container suitable for use in the practice of the present process; Figure 2 is a side elevational view of an anode insoluble in the nickel-iron alloy used

  in practicing the process of the present invention

tion; and

  FIG. 3 is an enlarged view in cross section

  versal of the anode shown in Figure 2, and taken

  roughly along line 3-3 of this figure.

  A cyanide-free electrolyte which can be used in the practice of the present invention contains, as essential components, copper ions, a complexing agent formed from organophosphonate in an amount sufficient to complex.

  copper ions present, a stabilizing and tam-

  pon comprising a compound of carbonate, borate and / or acetate soluble in the bath incompatible with the bath, as well as their mixtures, a p H of approximately 6 to approximately

  , 5, and optionally, a wetting agent.

  Copper ions are introduced during the cons-

  titration of the electrolyte using any lequei, or mixtures, of copper salts soluble in the bath and compatible with the bath, such as sulphate, carbonates, oxides, hydroxides and the like Among the preceding products , copper sulphate in the form of a pentahydrate (Cu SO 4 5 H 20) is preferred

  copper ions are present in the bath within the range of

  about 3 to about 50 g / l, typically about 5

  -at about 20 g / l For example, when we coat subs-

  trats of steel, copper ion concentrations of about 15 to about 50 g / l are used to obtain a high rate of electrolytic deposition of copper In cases

  o the concentration of copper ions is greater than approx.

  -ron 20 g / l, we found by experimentation that to obtain-

  nir satisfactory adhesion, it is preferable that the part entering the bath is electrified On the other hand, when

2538815,

  9. Coats zinc-based substrates such as zinc die cast parts, for example, concentrations

  copper ions of approximately 3.5 to approximately 10 g / l are pre-

  In this case, the part must be electrified at the time of immersion in the bath to obtain an adherent deposit. During the use of the electrolyt a replenishment of the copper ions consumed during the

  electrolytic deposit as well as those removed by entrained-

  ment is obtained by the progressive dissolution of a

  copper anode used during the electrolysis of the bath.

  The complexing or chelating agent comprises an organophosphorus ligand of a salt

  of alkali metal and alkaline earth metal among the

  which calcium is not suitable due to pre-

  Cipitation Preferably, the transformation salt into

  complex includes an alkali metal such as sodium, potassium

  sium, lithium and their mixtures, including

  potassium is the preferred metal The processing agent

  mation in complex is present in the bath considering

  the specific concentration of copper ions present.

  The specific organophosphorus coordinate con-

  venable for use according to the practice of the present invention comprises a compound selected from the

  group consisting of l-hydroxyethylidene-l, l-diphos-

  phonic (HEDP) itself present in an amount of about to about 500 g / l, a mixture of HEDP and aminotri

  (methylene phosphonic acid) (ATMP) o HEDP is pre-

  feels in an amount of at least about 50% by weight compared to

  port to the mixture and a mixture of HEDP and ethylenedia-

  tetra mine (methylene phosphonic acid) (EDTMP) o-HEDP is present in an amount of at least about 30% by weight relative to the mixture, as well as their salts and their partial salts compatible with the bath and soluble in the bath When mixtures of HEDP and ATMP or HEDP and EDTMP are used as the chelating agent 10.

  instead of HEDP itself, a reduction in con-

  centering of chelating agent can be used due to the higher chelating capacity of compounds

  of ATMP and EDTMP compared to that of HEDP.

  Conventionally available compounds of the above types which can be used satisfactorily

  in the practice of the present invention

  take the product called Dequest 2010 (HEDP), the product says Dequest 2000 (ATMP), and the product says Dequest 2041

  (EDTMP) available from the company called Monsanto Company.

  As previously indicated, the supervisor

  HEDP can be used at a concentration

  tion of approximately 50 g / l corresponding to a concentration of ions copper of approximately 3 g / l up to a concentration of approximately 500 g / l corresponding to a concentration

  copper ions of about 50 g / l, concentrations between

  mediaries being proportionally staggered in con-

  staggering corresponding intermediate concentrations

  When using a mixture of HEDP and ATMP, preferably comprising approximately 70% HEDP and 30% by weight of ATMP, it has been found that 14 g / l

  of HEDP and 6 g / l of ATMP are satisfactory for a

  neur in copper ions of 3 g / l while 225 g / l of HEDP

  and 97 g / l ATMP are satisfactory for a concentration

  ion ion copper bath 50 g / l Correct settings

  Respondents of HEDP and ATMP concentrations are proportionally made when the copper ion concentration is intermediate between the limits of 3 and g / l to provide satisfactory chelation with a

  slight excess of chelating agent present in the bath.

  Similarly, when a mixture of HEDP and EDTMP is used, preferably comprising about 50% by weight of each compound, it has been found that 9 g / l of HEDP

  and 10 g / l of EDTMP are satisfactory for a concentration

  ion ioncopper about 3 g / l, while 145 g / l 11.

  HEDP and 166 g / l EDTMP are satisfactory for a

  ion concentration copper bath of about 50 g / l with proportional concentration settings of these two

  constituents considering the intermediate concentrations

  -5 diaries of ionscopper We will also appreciate that the melan-

  included as a variant of chelating agents

  within the specified ranges will require appropriate adjustments

  concentration of the total chelating agent present in relation to the copper ion concentration by considering the previous concentration relationships which can be easily calculated and confirmed by routine experimentation to provide optimum performance for any given condition by considering in

  in addition to the specific examples presented below.

  A third desirable constituent of the elect

  trolyte for the deposition of copper comprises a buffer agent and stabilizer soluble in the bath and compatible with the bath comprising carbonate compounds, borate compounds, acetate compounds as well as

  their mixtures Preferably, sodium carbonate and -

  potassium carbonate are used to stabilize

  the electrolyte against fluctuations in p H etapour ser-

  further support for metal ions of

  contamination introduced into the bath as a result of the

  dragging and dissolving parts in the ele-

  trolyte during electroplating Use -

  buffer agents mentioned previously was additionally.

  observed, depending on the particular chelating agent used, -

  to inhibit the formation of soiled copper deposits and remove dark copper deposits in areas

  cathodic at low current density- Ammo- ions

  nium has been shown to be undesirable in some cases as a result of loss of adhesion of electrolytic deposits while cadmium ions are undesirable as a result of

  the tendency to form precipitates in the bath

12.

* centering of the buffer can go roughly around 3 times

  only about 100 g / i calculated as the salt of

  dium, preferably from about 10 to about 20 g / l

  buffering agent concentrations below the concentration

  recommended minimum values will cause p H to fluctuate while concentrations above the specified maximum range do not appear to have an adverse effect on

  the functioning of the electrolyte.

  Since the buffering agent and the processing agent

  mation in complex are subject to exhaustion by decomposition and training-, replenishment

  of these two chemicals to maintain electro-

  lyte within appropriate composition limits is born

  stopped during industrial operation This can be conveniently done on an intermittent or continuous basis in response to an analysis of the composition of the bath by adding the two components separately or

  mixed in appropriate proportions.

  The electrolyte is adjusted to provide a p H of

  about 6 to about 10.5, a p Hi of about 9 to about

  ron 10 being preferred Typically a p H of function-

  about 9.5 has been found to be particularly satisfactory.

  The appropriate p H of the electrolyte can be maintained by adding an alkali metal hydroxide to the electrolyte in order to increase the p H, potash being preferred.

  reduce the p H to the desired range, a mineral acid

  ral or an alkali metal bicarbonate can be used, among which potassium bicarbonate is a preferred material When the operating p H decreases

  below the recommended level, it was observed that the electricity

  trolyte tends to promote poor adhesion of the copper deposit on the substrate. On the other hand, for an operating p H above the recommended range, it has been observed in certain cases that the copper deposit becomes granular and has a burnt characteristic. We found 13.

  than at p H less than about 7.5 up to approx.

  ron 6, satisfactory adhesion and an aspect of

  Satisfactory results can be obtained on copper and copper alloy substrates. However, when coating ferrous and zinc-based substrates, it has been found that a p H above about 7.5 up to around

  , 5 provided better results.

  In addition to the foregoing constituents, the bath may optionally additionally contain a wetting agent or a surfactant which is soluble

  in the bath and compatible with the other constituents.

  When such a surfactant is used, it can be used in concentrations up to about 0.25 g / l, amounts from about 0.01 to about 0.1 g / l

  being preferred Typical surfactants contain

  venables for use in the practice of

  the present invention include polyethylene oxides

  lene such as the product known as Carbowax 1000, alkyl sulfates such as 2-ethylhexyl sulfate provided that

  the bath is filtered by carbon to remove pro-

  degradation products formed during operation,

  anionic and analogous perfluoro wetting agents

ford.

  In the practice of the process of the pre-

  sente invention, the electrolyte can be turned on-

  temperatures ranging from about 38 C to about

  ron 71 C, preferably from about 43 C to about 60 C, temperatures from about 49 C to about 60 C being typical The specific temperature employed will vary according to the composition of the bath as it will appear

  in the specific examples which will be described later.

  The bath can operate with a current density ca

  about 0.1 to about 8.0 A / dm, a den-

  current site from about 0.5 to about 2.5 A / dm being

favorite.

  14. The electrolytic deposition of copper can be carried out by considering the other operating parameters of the bath with a time as low as one minute up to a time as long as several hours or nf Ne days with coating times of approximately 2 minutes to about 30 minutes being more common for thin deposits The specific deposit time

  electrolytic will vary depending on the thickness of the bath

  which is typically about 0.00038 mm approx.

ron 0.127 mm.

  The electrolytic coating is made in

  immersing the conductive substrate to be coated in the elect

  trolyte and connecting it to the cathode of a

  DC source It has been found that when the con-

  copper ion concentration is above about 20 g / l,

  it is advantageous, and ordinarily necessary, to elect

  sort the substrates before and during immersion in order to obtain a good adhesion of the copper coating on ferrous-based substrates In the case of zinc-based substrates, it has been found essential for all the concentrations of copper ions in the bath electrify the zinc-based substrate before and during entry into the bath at a minimum potential of around 3 volts to obtain satisfactory adhesion of the coating

  of copper on the zinc-based substrate.

  A combination of anodes is used for electro

  trolyze the bath and deposit a coating

  of copper on the cathode The combination of anodes includes a copper anode of any of the types

  well known in the art such as a copper anode

  high purity glass free of oxygen which is soluble and replenishes the copper ions consumed from the

  bath by electrolytic deposition and external drive

  It has been observed that when the ion concentration

  copper falls below the minimum recommended concentration

2538 15

  15. mandated, a reduction in the efficiency of the cathode occurs, accompanied by burnt deposits On the other hand, it has been found that concentrations of copper ions above

  of the maximum recommended range affected unfavorable-

  the adhesion of the copper deposit While the

  viewing of copper ions must be carried out by the ad-

  addition of copper salts to the electrolyte, ef- is preferred

  replenish by dissolving the ano-

  of copper at a rate corresponding substantially to the rate of depletion of copper ions by an appropriate adjustment of the surface of copper anode relative to the surface of insoluble anode, this insoluble anode can be

  a ferrite anode or a nickel-iron alloy anode.

  The specific copper anode / surface area ratio

  this ferrite anode can range from about 1: 2 to about

  ron 1: 6, a ratio of about 1: 3 to about 1: 5

  being preferred and a ratio of about 1: 4 being typical.

  The specific ratio of copper anode surface to nickel-iron alloy anode surface can range from approximately 1: 2

  up to approximately 4: 1, a ratio of approximately 1: 1 to approx.

  ron 2: 1 being preferred In addition, the ratio between the surface of the cathode and the total surface of the anode can range from approximately 1: 2 to approximately 1: 6,

  preferably from about 1: 3 to about 1: 5, and typical-

ment about 1: 4.

  The ferrite insoluble anode used in the controlled combination with the copper soluble anode can

  understand a composite anode construction (heter-

  homogeneous) or integral where the ferrite sections include

  a sintered mixture of iron oxides and at least one other metal oxide to produce a sintered mass

  having a crystal structure of spinel

  particularly satisfactory ferrite anode res

  include a mixture of metal oxides containing

  about 55 to about 90 mole% of iron oxide calculated 16. as Fe 203 and at least one other metal oxide present in an amount of about 10 to 45 mole% of metals selected from the group consisting of manganese , nickel, cobalt, copper, zinc and their mixtures The sintered mass is a solid solution where the atoms of

  iron are present in the ferric and ferrous forms.

  These ferrite electrodes can be produced, for example, by forming a mixture of ferric oxide (Fe 203) and one or a mixture, of metal oxides chosen from the group consisting of Mn O, Ni O , Co O, Cu O and Zn O to provide a concentration of about 55 to 90 mol% of the ferric oxide and 10 to 45% of one or more of the metal oxides which are mixed in a ball mill The mixture is heated for approximately

  one to about 15 hours in air, nitrogen or anhydrous

  carbon dioxide at temperatures of about 700 to about

  1000 C The heating atmosphere may contain hy-

  drogen in an amount up to about 10% in nitrogen gas After cooling, the mixture is sprayed to obtain a fine powder which is then transformed into a shaped mass having the configuration

  desired, by compression or extrusion molding.

  The shaped mass is then heated to a temperature

  re from about 1100 to about 14500 C in nitrogen or carbon dioxide containing up to about 20% by volume of oxygen for a period ranging from about 1

  at around 4 o'clock- The resulting sintered mass is

  slowly cooled in nitrogen or anhydride

  carbonic containing-up to about 5% by volume of oxy-

  gene by producing an electrode with the configuration

  suitable characterized in that it has a resistance

  relatively low activity, good resistance to cor-

  corrosion and good resistance to thermal shock.

  It will be appreciated that instead of using ferric oxide, metallic iron or ferrous oxide may 17.

  be used in the preparation of the initial mixture.

  In addition, instead of the other metal oxides,

  compounds of metals which subsequently produce oxy-

  of corresponding metal by heating can be used as a variant such as, for example, the compounds of carbonate or of oxalate metail. Among the preceding, ferrite anodes composed predominantly of iron oxide and oxide nickel in the proportions presented above have been found to be particularly satisfactory for practical application

of this process.

  A ferrite anode comprising a fried mixture

  iron oxide and nickel oxide tee suitable for

  use in the practice of this information

  vention is commercially available from the so-called company

TDK-Inc, under the designation F-21.

  By the proper proportioning of surfaces

  anode of ferrite and copper, the chemistry of electro-

  lyte is maintained with appropriate additions of

  the buffer and complexing agent and small

  your additions, if necessary, of copper salt.

  An insufficient ferrite anode surface results in grainy or dull deposits while an anode surface

  excessive ferrite can result in reduced efficiency

  cathode and a gradual depletion of copper anions requiring more frequent replenishment

  electrolyte with copper salts.

  Surprisingly, the use of main insoluble anodes as an alternative to the ferrite anode as described above or nickel-iron alloy anodes as described below does not provide satisfactory deposits. For example, we found that

  main anodes in insoluble graphite degrade

  pay by producing harmful byproducts in the

  bath / resulting in soiled deposits.

18.

  The insoluble nickel-iron alloy anode employs

  yée in a controlled combination with the soluble copper anode may have a composite composition

  (heterogeneous) or integral providing at least one strategy

  te on the outer surface which is composed of a nickel-iron alloy containing approximately 10% up to approximately

  % iron weight, the complement being essential-

  nickel, preferably about 15 to about 30%

  of iron According to a preferred form of the present invention

  tion, the insoluble nickel-iron alloy anode is composed

  an electrically conductive core (central part)

  tor having an adherent electrolytic deposit of the nickel-iron alloy on its surfaces of sufficient thickness to envelop the material of the core preventing its

  exposure for extended periods of use.

  The nickel-iron alloy deposit or coating is further characterized as being substantially non-porous in

  effectively sealing the inner core against any exposure

  electrolyte position In these composite or heterogeneous anode constructions, the core material can include metals such as copper, copper alloys, ferrous-based cores including iron and

  steel, aluminum and aluminum alloys, ni-

  ckel and the like Among the foregoing products, a high purity copper core similar to the copper anode used in connection with the insoluble nickel-iron anode is preferred, since inadvertent exposure of the core as a result of damage or as a result of gradual dissolution of the coating or overlay over an extended period of time does not adversely affect the operation of the bath since copper ions are introduced in a manner similar to those introduced

  by conventional soluble copper anodes By opposi-

  tion, when ferrous-based cores are used,

  inadvertent exposure of the nucleus to the electrolyte

19.

  causes a progressive dissolution of iron by introducing

  sant iron ions in the electrolyte, which affects

  ultimately unfavorably the quality of the cooking deposit

  your product by making the process industrially unsatisfactory It has been observed that concentrations of iron ions in the electrolyte of more than about 325 ppm are harmful and tend to produce grainy, dull and burnt-like copper deposits. , the ions

  contamination iron cannot be easily removed

  from the transformation agent into a complex

  in the electrolyte, which complexes these contaminated iron ions

  nation very strongly While nuclei composed of

  nickel or nickel alloys can also be used

  yeas satisfactorily, their conductivity inferior

  and their relatively higher cost price

  make them less desirable than copper cores.

  According to a preferred practice of the present invention, the anode made of an insoluble nickel-iron alloy is

  produced by electroplating a coating

  ment of nickel-iron alloy on a conductive core which has been subjected to appropriate pre-coating steps to make the substrate receptive to the deposit

  electrolytic of a nickel-iron alloy according to practices

  ques conventional pre-coating well known in the

  technique for metallic substrates When a no-

  aluminum or aluminum alloy yau is used

  pre-coating steps such as zincate, an alloy

  bronze age or anodization are used according to

  well known practices for making the nucleus receptive vis-

  with a nickel-iron coating The electrolyte for depositing the nickel-iron alloy deposit on the anode core can include any of the types well known in the art as described, for example, in US Pat. Nos. 3,806,429, NO 3,974,044, and NO 4,179,343 It will be appreciated that the compositions and 20.

  processes as described in the US patents men-

  mentioned above are mainly intended to produce

  a deposit of extremely bright and depleted nickel-iron alloy

  corative on a conductive substrate simulating that of a classic shiny nickel deposit A uniform shiny nickel-iron deposit is not essential for the

  satisfactory operation of the nickel alloy anode

  insoluble iron of the present invention, since the alloy deposit is a functional coating rather than a decorative coating and therefore semi-shiny, satin and even relatively dull nickel-iron electrolytic deposits can be employed. following the above, the particular concentration and

  the main and secondary polish types

  re employed in the aforementioned US patents

  can be changed and their concentration

  pick to provide an adherent nickel-iron coating

  and ductile having the desired alloy composition.

  The electrolyte for nickel alloy deposition-

  iron contains organic sulfur compounds for intro-

  reduce sulfur in the resulting alloy deposit in order to provide satisfactory operation and which reinforces

  also the adhesion of the coating on the anode core.

  it has been found that sulfur contents in quantity of

  about 0.005 to about 0.06% by weight, preferably about 0.01 to about 0.04% by weight, in the nickel-iron alloy deposit are necessary to provide satisfactory performance in the form of an insoluble anode

  in the practice of the present invention Typi-

  The sulfur content in the electrolytic deposition

  that nickel-iron alloy is about 0.02 to about 0.03

% in weight.

  It has been found that the composition of the alloy is

  important to obtain the appropriate oxidizing medium in the elect

  copper trolyte to provide a coating process

25388 1 5

2.1.

  copper electrolytic which is industrially accepted

  table from the point of view of ease of control, maintenance and replenishment and quality

  of the copper coating produced While concentrations

  iron trations from about 10% to about 40% by weight

  have proved satisfactory, particular results

  are satisfactorily obtained for concentra-

  iron from about 15 to about 30% iron, special-

  approximately 20 to about 25% iron, the balance being essentially nickel Surprisingly, an anode consisting essentially of pure iron does not

  not work in the practice of this process

  dice the fact that it dissolves quickly causing a rapid increase in the concentration of iorsfer by rendering the bath ineffective for the reasons previously presented Similarly, it has been found that

  substantially pure nickel anodes were unsatisfied

  despite the fact that they are relatively insoluble

  whites Substantially pure nickel anodes have formed

  found to be inadequate for providing the oxidizing medium

  hated for proper coating performance

  ble for extended periods of time Similarly, sulfur-free nickel-iron alloys

  are found to be unsatisfactory after relatively short periods

  Briefly in use such as around 8 hours.

  On the other hand, sulfur contents of more than about

  0.06% in the nickel-iron alloy is not satisfactory

  your for sustained industrial operation.

  Referring now to the drawing, and com-

  As shown in FIG. 1, a typical arrangement of electrolytic coating is schematically illustrated, which can be used in the practice of the present invention. As shown, the device comprises a tank 10 filled with the copper alkaline electrolyte 12 free of cyanide and having a bus bar 14

253 881 5

  22. anodically charged and arranged above it

  two soluble copper anodes 16 and one alloy anode

  ge insoluble nickel-iron 18 are suspended in electrical contact The ratio of the anode surface of the anode or of the soluble and insoluble anodes is important in order to obtain proper operation of the bath during a

  industrial operation maintained By the proportion

  appropriately the copper anode surface and the

  nickel-iron alloy anode surface in a range of

  about 1: 2 to about 4: 1, preferably for

  ratios of approximately 1: 1 to approximately 2 t 1, the chi-

  crumb of the electrolyte is maintained with additions

  appropriate buffering and processing agents

  copper-and small additions, if necessary, of copper salt When the ratio of copper anode surface to nickel-iron alloy anode surface drops below about 1: 2, i.e. when the total area of copper anode falls below about 33% of the

  total anode surface, it was observed that the cooking anode

  vre tended to polarize and in this condition there, it remains conductive but does not dissolve any more according to the desired rate entraining -dep 8 ts of dull copper

  and grainy This also requires a replenishment-

  copper ions increased by the addition of so-

  lubles which is associated with the formation of degradation products in the bath As a result, while the

  process can be started for short

  your time periods, for a ratio of copper anode surface to nickel-iron alloy anode surface superior

  at approximately 1: 2, this operation is not industrial-

  Also practical for extended periods of time.

  Referring now to Figure 2 of

* drawings, the insoluble nickel-iron alloy anode constructed

  te according to a preferred embodiment of the present

  The invention is a composite construction comprising

25388 1 5

  23. an elongated bar 20 securely connected to its

  upper end to a cross-shaped element 22

  chet which is preferably composed of a material

  inert conductor such as titanium, for example.

  The elongated bar 20, as best seen on the

  Figure 3, is composed of a core or central part, -

  central conductor 24 which may have a construction -

  solid or tubular having an adherent outer layer or coating 26 placed over the total outer surface The particular configuration of the nickel-iron alloy anode is not critical for obtaining satisfactory performance and the shape as well as the configuration in cross section can be modified according to known practices for

  obtain optimum projection power and uniformity

  optimum characteristics and thickness of the electrolytic deposit of copper in accordance with the nature of the

substrates to be coated.

  During an electrolytic coating, a subs-

  trat or workpiece 28 to be coated with copper is immersed

  ge in the electrolyte 12 of the tank 10 of FIG. 1

  generally supported from a bus bar

  venable 30 and cathodically charged ô current is passed between the anode and the substrate for a period of time sufficient to deposit the thickness

  desired copper on the substrate.

  While replenishing the complexing agent during the operation of the electrolyte is usually accomplished by employing

  an alkali metal salt neutralized to avoid -reduction-

  strong electrolyte operating pl, it is expected that the acid form of the product of transformation into complex can be used for the formation of the bath

  original or a new dissolving bath formation

  first of all the product of transformation into a complex of

2538815.

  24. acid form in water, followed by the addition of a base

  such as potash to increase p H to a level

  calf above about 8 Then the buffering agent can be added to the preliminary solution or neutralization of the complex transformation product has

was carried out in situ.

  To further illustrate the process and the new anode of the present invention, the following specific examples are provided. It will be understood that these examples

  are for illustration only and not for li-

mitation of the present invention.

EXAMPLE 1

  An aqueous alkaline electrolyte free of cyanu-

  re suitable for depositing a thin coating of copper on ferrous-based substrates such as steel and substrates

  based on copper such as brass is prepared in dis-

  solvent in deionized water about 60 to about 72 g / l copper sulfate pentahydrate (15 to 18 g / i

  copper ions) with agitation After dissolution

  full of salt formed from copper sulfate, about 81 to about 87 g / l of complexing agent are dissolved including the neutralized potassium salt of an aminotri (methylene phosphonic acid) (ATMP) at 30%

  by weight and 70% by weight of 1-hydroxyethylidene acid-

  1,1-diphosphonique (HEDP) The p H of the solution is adjusted by using a 50% aqueous solution of potassium hydroxide to

  provide a p H of about 8.5 Then about 15 to about

  25 g / l of potassium carbonate are added and the

  solution is stirred until dissolution is complete

  te happen The solution is then heated to an operating temperature ranging from about 43 C to about 60 C and a combination of a copper anode

  high purity, free of oxygen and an iron anode

  rite is immersed while hanging from an anode rod to provide an anode surface area 25.

  Ferrite / copper anode area of approximately 4: 1.

  While agitation is not critical, some agitation such as mechanical agitation, by cathode rod, and preferably agitation by air is employed to provide improved efficiency and spraying power of the coating. steel and brass are subjected to the electrolytic coating in the preceding electrolyte for periods of approximately 2 to 20 minutes at a cathodic current density of approximately 0.5 to 1.0 A / dm 2 and for an area ratio of cathode / anode surface from about 1: 2 to about 1: 6 The bath is maintained

  at a p H of about 8.5 to 9.5 and the solution is vigorous.

  vigorously agitated by air agitation

  -15 deposits of thin, substantially uniform copper coating-

  mes, with refined, ductile and adherent grains.

  The above electrolyte is also suitable for coating copper parts with steel and

  made of brass in a barrel covering.

EXAMPLE 2

  One prepares an electrolyte identical to that de-

  written in Example 1 Experimental zinc panels

  are coated satisfactorily using the same

  my operating parameters than those described in Example 1 except, however, that the experimental panels are electrified at a minimum voltage of 3 volts - before and during immersion in the electrolyte

  to provide deposits of thin coated copper

  rents, ductile and refined grain.

EXAMPLE 3

  An aqueous alkaline-cyanide-free electrolyte suitable for depositing a thin coating of copper on ferrous-based substrates such as steel and on copper-based substrates such as brass is prepared by dissolving in deionized water about 25 g / l 26. to 35 g / l copper sulphate pentahydrate (6.25 to

  8.75 g / l coppercopper) with stirring After dissolu-

  the complete salt formed from copper sulphate, about 62.5 g / l are added to about 78.5 g / l of l-hydroxy ethylidene-l, l-diphosphonic acid The p H of the solution is adjusted using a 50% aqueous solution of potash

  up to p H above 8.0 Then about 15 to-

  about 20 g / l of sodium carbonate are added and the

  solution is stirred until dissolution is complete

  te occurs The solution is then heated to an operating temperature of about 54 to about C and a combination of a high purity oxygen-free copper anode and a ferrite anode is immersed in the bath while hanging from an anode rod to provide surface area

  Ferrite anode / copper surface of approximately 4: 1.

  Air agitation is used to reduce burn and to improve the spraying power of the process; steel or brass panels or parts are subjected to the electrolytic coating in the previous electrolyte for periods of approximately

  2 to 20 minutes for cathodic current densities.

  about 2.0 to 3.0 A / dm and for a surface ratio of

  cathode / anode surface from about -1: 2 to about 1: 6.

  The bath is maintained in a range of p H from about 8.5 to 10.2 and the solution is vigorously stirred by

  air agitation We obtain deposits of thin coating

  uniform, fine-grained, ductile and adherent copper.

EXAMPLE 4

  An electrolyte identical to that defined is prepared.

  written in example 3 Panels or parts

  zinc coatings are coated satisfactorily

  using the same operating parameters as those described in Example 3 except, however, that 27. the cathodes (workpieces) are electrified under

  a minimum voltage of 3 volts before and during immersion

  ion in the electrolyte to provide cui deposits

  glass, ductile, adherent and fine-grained.

EXAMPLE 5

  An aqueous alkaline electrolyte free of cyanide

  suitable for depositing copper deposit on subs-

  iron-based trats such as steel and on substrates

  based on copper such as brass is prepared in dis-

  solvent in deionized water about 55 g / l to about 88 g / l of copper sulfate pentahydrate (13.5 to 22 g / 1 of copper ions) with stirring After complete dissolution of the salt formed from copper, approximately 100 to approximately 122 g / l of l-hydroxyethylidene-l, diphosphonic acid are added. The p H of the solution is adjusted using a 50% aqueous solution of potassium hydroxide to provide a p H of about 8, 0 Then about 15 to 25 g / l of sodium carbonate are added and the solution is stirred until complete dissolution occurs. The solution is then heated to about 54- C to 65 C and a

  combination of a high purity copper anode, ex-

  te of oxygen and ferrite anode is inezged while

  being suspended from an anode rod for-furnace-

  establish a ferrite anode surface / anode surface ratio

copper approximately 4: 1.

  While the agitation is not critical, a certain agitation such as mechanical agitation, by cathode rod and preferably by air is employed - to provide the efficiency and the power of projection of the process - Substrates of steel and brass are subjected to the electrolytic coating in the preceding electrolyte for periods of 2 to 60 minutes and under a cathode current density of about 1/0 to 3.0 A / dm and for a cathode surface ratio / anode surface from about 1: 2 to about 1: 6 The bath is maintained in a range

25388 1 5

28.

  of p H of approximately 8.5 to 10.2 We obtain

  uniform, fine-grained, ductile and adherent.

  The preceding electrolyte is also suitable

  ble for coating copper parts of steel and brass in a barrel coating.

EXAMPLE 6

  An aqueous alkaline cyanide electrolyte is prepared, suitable for depositing a deposit of copper on ferrous-based substrates such as steel and on

  copper-based substrates such as dissolved brass

  about 55 g / l to about g / l of copper sulphate pentahydrate (13.5 to g / l of copper ions) in deionized water, shaking After dissolution

  complete with the salt formed from copper sulphate, then add

  approximately 43.5 g / l to 52 g / l of l-hydroxyethylidene-l, l-diphosphonic acid (HEDP) and 100 to 122 g / l of ethylene diami-

  ne tetra (methylene phosphonic acid) (EDTMP) p H

  of the solution is adjusted using an aqueous solution

  se at 50% of potash to provide a p H of 8.0 Then,

  about 10 to 25 g / l of potassium carbonate are added

  tees and the solution is stirred until the dissolu-

  The complete solution is then heated.

  fairy up to an operating temperature of about 54 C up to about 60 C and a combination of high purity copper anode, free of oxygen and

  iron-rite anode is submerged while being suspended

  due to an anode bar to provide a sur-

  ferrite anode face / approx.

Ron 4: 1.

  While agitation is not critical, some agitation such as mechanical agitation, for example

  cathode rod and preferably by air is employed.

  The steel and brass experimental panels or their parts are subjected to the electrolytic coating in the preceding electrolyte for a period of 2 minutes 29. to several days (depending on the thickness of copper required under a cathode current density of approximately 1.0 to 4.0 A / dm and for a cathode surface / surface ratio

  anode about 1: 2 to about 1 6 The bath is main-

  held in the range of p H from 8.5 to 10.2 Uniform, fine-grained, ductile and adherent copper deposits are obtained. The previous electrolyte is also suitable

  for coating copper on steel and copper parts

tone in a barrel coating.

  We will appreciate that it is not essential for

  satisfactory implementation of the process and the

  position of the present invention to prepare elect

  copper trolytes according to the specific sequence and to use the specific ingredients described For example the complex transformation agent or the mixture of complex transformation agenis can be introduced in the form of an aqueous potassium salt concentrate to provide the desired concentration of the complex transformation agent Typically, the acid form of the complex transformation agent can first be neutralized by using a 50% aqueous solution of potassium hydroxide by providing a concentrate

having a p H of about 8.

EXAMPLE 7

  A composite iron-nickel alloy anode includes

  nant an iron-nickel alloy deposited electrolytically on a copper-solid core is prepared using an electrolyte having the following composition

25388 15

  30. Optimal value Ni + 2 56 g / l Fe + 2 and Fe + 3 4 g / l Ni SO 4 l 6 H 20 l 150 g / l Ni C 12 l 6 H 20 l 100 g / l H 3 B 03 45 g / l Sodium gluconate 20 g / l Saccharin sodium salt 2.5 g / l Sodium allylsulfonate 4.0 g / l Wetting agent 0.2 g / lp H 2.9 Stirring Air, cathode rod or Temperature 57 C Cathodic current density 4.0 A / dm 2 Range -100 g / l 1-10 g / l -300 g / 1 -150 g / l

Satu-

  ration -100 g / l o-10 g / l 0.5-15 g / l 0.05-1.0 g / l

2-5-4.0

rest state

38-71 C

0.5-10.0

  A / dm 2 Anodes Iron and nickel The wetting agent used comprises wetting agents of the low foaming type such as sodium octyl sulphate when used

  air agitation and formulating wetting agents

  relatively high foam content such as lauryl-

  sodium sulfate when using bar agitation

  cathodic water or baths in a resting state The glu-

  sodium conate in the electrolyte composition

  takes complex transformation agent for ferric ions and complex transformation agents

  alternatively satisfactory or their mixtures may

  may be used for this purpose; comprising citrates,

  tartrates, glucoheptonates, salicylates, as-

corbates or the like.

  Transformation agents in complex to ti-

  Variants which can be used satisfactorily include those described in the previously mentioned US patents Nos. 3,806,429, Nos. 3,974,044 and Nos. 4,179,343 The anodes employed in 31. the electrolytic nickel coating process iron are in the form of individual plates or chips

  individual iron and nickel in separate baskets.

  The composition of the electrolyte for the deposition of iron-nickel according to the optimum composition as presented in the previous table produces a deposition of iron-nickel alloy containing approximately 20% of iron, the balance being essentially nickel using a cathode rod agitation When air agitation is used, the concentration of iron in the electrolytic deposit will increase up to about 30% by

  weight When agitation is not used, the concentration

  tion of iron in the electrolytic deposit will decrease until

  only about 15% by weight According to one practice

  preferred of the present invention, agitation by bar-

  cathodic or moderate air is used because the electrolytic deposition is more uniform to the point

  composition as well as aspect.

  In the formulation of suitable electrolytes

  For iron-nickel deposition, the nickel ion / iron ion ratio is perhaps the single most important factor in determining the composition of the final alloy electrolytic deposition. According to the optimum formulation, a nickel / iron ratio of around 14 : 1 by using a stirring by a cathode rod provides a concentration of iron in the electrolytic deposit of alloy of approximately 20% in

  weight For a higher nickel / iron ratio, a concentration

  lower iron tration in the deposit is produced whereas for a lower nickel / iron ratio, a

  higher concentration of iron in the alloy is pro-

  pick In either case, the electrolyte and the

  operating ditions are controlled in order to provide

  a nickel-iron alloy deposit containing approximately 15% up to

only about 30% by weight of iron.

  An elongated copper core is used to form

32.

  sea an anode of nickel-iron composite alloy and is often

  put to a conventional pretreatment before coating in the electrolyte mentioned above The pretreatment can typically comprise an alkaline impregnation treatment for a period ranging from approximately 1 to approximately 3 minutes followed by a step cathodic electro-cleaning for a period of approximately 1 to approximately 2 minutes followed by rinsing with cold water The core

  of rinsed copper is then subjected to an

  pregnation in a sulfuric acid solution at 5 to

  % for a period of about 15 to about 30 seconds-

  des, followed by rinsing with cold water -The core of

  pre-treated copper is then immersed in an electrolyte

  te for the nickel-iron deposit mentioned above and is subjected to the electrolytic coating for a period of 1 to about 2 hours at an average cathodic current density of about 4.0 amperes per square decimeter (A / dm 2) from what the composite anode is removed,

  rinsed with cold water and dried Electro-

  nickel-iron alloy lytic has a thickness of about 0.0508 mm to about 0.1016 mm and contains about 20%

  by weight of iron and about 0.025% by weight of sulfur.

  In the manufacture of these nickel-iron alloy anodes, the electrolytic deposition of the nickel-iron alloy deposit may ordinarily have a thickness of about 0.0127 mm up to about 0.254 mm or even more to obtain a

  satisfactory operation The important criterion of the

  electrolytic deposit is that it is substantially non-porous

  and that it adheres to the nucleus and that it is furthermore

  laughed at as having good ductility and tension

  laterally weak The conditions as presented in

  Example 1 provide a deposit of nickel-iron which pos-

  seduce the previous desirable properties.

EXAMPLE 8

  A composite nickel-iron alloy anode

2538815 '.

33.

  taking an electrolytically deposited nickel-iron alloy

  tick on a solid steel core is prepared in use

  yant the same procedure as that presented in Example 7 except however that the steel core during the pretreatment before coating is subjected to an anodic electro-cleaning step instead

  a cathodic electro-cleaning step and is ultra-

  previously subjected to an impregnation treatment using a more concentrated sulfuric acid solution, at a concentration of about 25%, for a period

  of similar time as described in Example 7.

  The resulting composite anode has an electrical deposit

  nickel-iron trolytic having the same characteristics

  than those obtained in Example 7.

EXAMPLE 9

  An aqueous alkaline electrolyte free of cyanu-

  re suitable for depositing a thin coating of copper on ferrous-based substrates such as steel and on copper-based substrates such as brass is prepared by dissolving in deionized water about g / l to 35 g / l copper sulphate pentahydrate

  (6.25 to 8.75 g / 1 of copper ions) with stirring After dissolving

  complete lution of the salt formed from copper sulphate, approximately

  76.1 g / l to about 84.8 g / l of l-hydroxy ethylidene acid-

  1,1-diphosphonic are added The p H of the solution is adjusted by using a 50% aqueous potassium hydroxide solution

  up to p H above 8.0 Then about 15 to-

  about 20 g / l of sodium carbonate are added and the solution is stirred until complete dissolution occurs. The solution is then heated to an operating temperature of about 54 C to 60 C and a combination of a high purity copper anode, free of oxygen and of a nickel-iron alloy anode such as obtuselon according to example 7, is immersed in the bath while being suspended from an anode bar 34.

  to provide a copper anode to surface area ratio

  this of nickel-iron alloy anode of about 2: 1.

  Air agitation is used to reduce

  re the burn and to improve the projection power of the process The panels or pieces of steel and brass are subjected to the electrolytic coating in the preceding electrolyte for periods of approximately

  2 to 20 minutes and under cathodic current densities

  only about 1.5 to 2.0 A / dm and for an area ratio

  cathode / anode area of about 1: 2 to about 1: 6 The bath is maintained in a p Hl of about 9.5

  to 10.2 and the solution is vigorously stirred by agitation

  by air We obtain deposits of thin coating

  copper, uniform, fine-grained, ductile and

members.

EXAMPLE 10

  An aqueous alkaline electrolyte free of cyanide

  suitable for depositing copper deposit on subs-

  ferrous base trats such as steel and substrates

  based on copper such as brass is prepared in dissol

  about 55 g / l to about 88 g / l of copper sulphate pentahydrate (13.5 to 22 g / l of copper ions) in deionized water with stirring After dissolution

  complete with the salt formed from copper sulphate, then add

  about 107.9 to about 147 g / l of 1-hydroxyethylidid acid

  ne-l, l-diphosphonique The p H of the solution is adjusted by using a 50% aqueous solution of potassium hydroxide to provide a p H of approximately 8.0 Then, approximately 15 to 25 g / l

  of sodium carbonate are added and the solution is stirred

  until complete dissolution occurs.

  The solution is then heated to about 54 C

  at 60 C and a combination of a large copper anode

  of purity, free of oxygen and a nickel-iron alloy anode is immersed while hanging from an anode rod to provide a surface area 35. of copper anode / nickel alloy anode surface / iron

about 1: 1.

  While agitation is not critical, some agitation such as mechanical agitation, by cathode rod and preferably by air, is employed to provide efficiency and projection power

* of the process Steel and copper substrates are supported

  electroplated in the electrolyte pre-

  yield for a period of 2 to 60 minutes under a -

  cathode current density of approximately 1.0 to 3.0 A / dm 2 and -for a cathode surface / anode surface ratio of approximately 1: 2 to approximately 1: 6 The bath is maintained in a range of p H about 9.5 to 10.2 Uniform, ductile, fine-grained copper deposits are obtained

and members.

  The above process is also suitable for coating copper and steel and steel parts.

  brass in a barrel coating.

EXAMPLE ll

  The process as described in Example 9 is repeated for depositing a thin coating of copper on ferrous-based substrates, except that an anode made of a nickel-iron composite alloy is used.

  for the same copper anode / nickel alloy anode ratio

  ckel-iron but containing only ll% by weight of iron

  and 0.02% sulfur A uniform copper deposit is obtained

  form, fine-grained, ductile and adherent.

EXAMPLE 12

  The process of the example is repeated except that an anode made of a nickel-iron composite alloy is used containing 11% by weight of iron and 0.067% by weight of sulfur The resulting copper deposit is unacceptable, including a reddish deposit grainy which is believed to be caused by excess sulfur content in

the nickel-iron alloy of the anode.

25388 1 5

36.

EXAMPLE 13

  The process of Example 10 is repeated except, however, that a composite anode of nickel-iron alloy is used where the alloy contains 32% by weight of iron and 0.02% of sulfur. An acceptable electrolytic deposition of copper is obtained, uniform, grain

thin, ductile and adherent.

EXAMPLE 14

  The process of Example 13 is repeated

  except, however, that a composite alloy anode ni-

  ckel-fer is used containing approximately 32% by weight of

  iron and sulfur at a concentration of 0.088% We obtain

  holds an unacceptable deposit of copper, grainy and mar-

ron-reddish.

'' EXAMPLE 15

  The process of Example 13 is repeated except that a composite anode of nickel-iron alloy containing 60% by weight of iron and 0.02% of sulfur is used. An unacceptable deposit of copper, grainy and shiny, is obtained. it is believed to be due to a high iron content in the nickel-iron alloy anode.

EXAMPLE 16

  The process of Example 13 is repeated except, however, that an anode of nickel-iron alloy is used containing approximately 25% by weight of iron and

  0.02% of sulfur An acceptable copper deposit is obtained

  ble, uniform, fine-grained, ductile and adherent.

EXAMPLE 17

  An aqueous alkaline electrolyte free of cyanu-

  re suitable for depositing a thin coating of copper on ferrous-based substrates such as steel and copper-based substrates such as brass is prepared by dissolving in deionized water about 60 to about 72 g / l of copper sulfate pentahydrate 37.

  (15 to 18 g / l of copper ions) with stirring After dissolving

  complete salt formation of copper sulphate, approx.

  ron 81 to about 87 g / l of a processing agent

  complex are dissolved including the potassium salt neu-

  traced from an aminotri (methylene phosphonic acid)

  (ATMP) at 30% by weight and 70% by weight of l-hydroxy acid

  ethylidene-1,1-diphosphonic (HEDP) The p H of the solu-

  tion is adjusted using a 50% aqueous solution

  of potash to provide a p H of about 8.5 Then,

  about 15 to about 25 g / l of sodium borate are

  added and the solution is stirred until the disso-

  complete lution occurs The solution is then heated

  fairy up to an operating temperature of about

  43 C to about 54 C and a combination of a cooking anode

  high purity glass free of oxygen and a composite nickel iron alloy anode containing 25% by weight of iron and 0.02% by weight of sulfur is immersed while

  being suspended from an anode rod for furnace-

  establish a copper anode surface / anode surface ratio

  made of nickel / iron alloy of about 1: 1.

  While agitation is not critical, some agitation such as mechanical agitation,

  by cathode rod and preferably by air, is em-

  bent to provide efficiency and power

  improved projection of the pan coating process

  Experimental steel and brass rings are electrolytically coated in the previous electrolyte for periods of about 2 to 20 minutes at a cathodic current density of about 0.5 to 1.0 A / dm 2 and for a cathode surface / anode surface ratio of approximately 1: 2 to approximately 1: 6 The bath is maintained in a p H range of approximately 7.5 to 9.5 and the solution

  is vigorously agitated by air agitation We ob-

  holds deposits of thin sensitive copper coating-

  uniform, fine-grained, ductile and adherent.

  38. -The previous process is also suitable for coating copper and steel and brass parts

in a barrel coating -

EXAMPLE 18

  An electrolyte identical to that described in Example 17 is prepared except that approximately 15 to approximately 25 g / l

  potassium carbonate were used instead-

  sodium borate as a buffering agent Panels

  zinc coatings are satisfactorily coated

  health using the same operating parameters as those described in Example 17, except that the experimental panels are electrified at a minimum voltage of 3 volts before and during immersion in the electrolyte to provide deposits of thin

  adherent copper coating, fine-grained and ductile.

  The appreciation of some of the measurement values

  res indicated above must take into account that

  come from the conversion of Anglo-Saxon units

in metric units.

  The present invention is not limited to the exemplary embodiments which have just been described, it is on the contrary liable to modifications and

  variants which will appear to those skilled in the art.

39.

Claims (45)

  1 Cyanide-free alkaline aqueous electrolyte for the electrolytic deposition of a copper coating   fine, ductile and adherent grains on a conductive substrate   tor, characterized in that it comprises an alkaline solution   aqueous line containing copper ions present in quan-   enough to electrolytically deposit copper a transformation agent into a complex present in sufficient quantity to chelate the copper ions   present, the transformation agent into a complex   of a compound selected from the group consisting of   l-hydroxyethylidene-l, l-diphosphonic acid, a mixture   l-hydroxyethylidene-1,11-diphosphonic acid and aminotri (methylene phosphonic acid) o l-hydroxyethylidene-1,1-diphosphonic acid is present in an amount of at least about 50% by weight relative to at   mixture, and a mixture of l-hydroxyethylidene-l, 1- acid   diphosphonic and ethylene diamine tetra (methyl acid   phosphonic lene) o l-hydroxyethylenene acid-l, l-   diphosphonic is present in an amount of at least about% by weight relative to the mixture; as well as their salts   and their partial salts soluble in the bath and compatible   bles with the bath, a carbonate compound soluble in the bath and compatible with the bath present in an amount sufficient to stabilize the p H of the electrolyte, and hydroxyl ions present in amount to provide a p H at about 7.5 to about 10.5.   2 Electrolyte according to claim 1, character-   laughed at in the quantity of copper ions from about 3 to about 50 g / l.   3 Electrolyte according to claim 1, character-   laughed at in the quantity of copper ions from about 15 to about 50 g / l.   4 Electrolyte according to claim 1, charac-   dried in that the copper ions are present in quantity 40. from about 3.5 to about 10 g / l.   Electrolyte according to claim 1, characterized in that the hydroxyl ions are present   in quantity to provide a p I of about 9.5 to about 10.   6 Electrolyte according to claim 1, charac-   terized in that it further comprises a wetting agent   age soluble in the bath and compatible with the bath in   amount up to about 0.25 g / l.   7 electrolyte according to claim 1, charac-   terized in that it further comprises a wetting agent-   ge soluble in the bath and compatible with the pre-bath   smells in an amount of about 0.01 to about 0.1 g / l.   8 Electrolyte according to claim 1, characterized in that the carbonate compound is chosen from the group consisting of carbonate compounds and   of alkali metal and alkali metal bicarbonate earthy and their mixtures.   9 Electrolyte according to claim 1, charac-   terized in that the carbonate compound is selected from the group consisting of carbonate compounds and   bicarbonate of alkali metals and their mixtures.   Electrolyte according to claim 1, characterized in that the carbonate compound comprises potassium bicarbonate.   11 Electrolyte according to claim 1, characterized in that the carbonate compound is present in an amount of approximately 3 to approximately 100 g / 1 calculated on a basis of equivalent weight by weight in the form of carbonate sodium.   12 Electrolyte according to claim l, ca-   characterized in that the carbonate compound is present in an amount of about 10 to about 20 g / l calculated on an equivalent basis by weight in the form of sodium carbonate.   13 Electrolyte according to claim l, ca-   41. characterized in that the transformation agent into a complex   includes l-kydroxyethylidene-1,1-diphosphoni-   than present in an amount of about 50 to about '500 g / l.   14 Electrolyte according to claim 1, characterized in that the complexing agent comprises a mixture containing 70% by weight of l-hydroxyethylidene-l, l-diphosphonic acid and 30% by weight of aminotri (acid methylene phosphonic) -as well as their salts and their partial salts soluble in the bath and compatible with the bath, this mixture being present in   amount from about 20 to about 322 g / 1.   Electrolyte according to claim 1, ca-   characterized in that the complexing agent comprises a mixture containing approximately 50% by weight of 1-hydroxyethylidene-1, ldiphosphonic acid and approximately% by weight of ethylene diamine tetra (methylene phosphonic acid) as well as their salts and their partial salts which are soluble in the bath and compatible with the bath and   their mixtures, this mixture being present in quantity of about 19 to about 311 g / l.   16 Method for electrolytically depositing a thin coating of fine-grained, ductile and adherent copper on a conductive substrate characterized in that it consists in providing an aqueous alkaline electrolyte free of cyanide having a composition as defined in the   claim 1, to control the temperature of the electro-   lyte between about 38 C and about 71 C, immersing a conductive substrate-to be coated as a cathode in the electrolyte, immersing a combination of an anode   soluble on the basis of copper and an anode insoluble in ferri-   te in the electrolyte to provide a ratio of copper anode area to ferrite anode area of about 1: 2 to about 1: 6, to pass current between the anodes and the cathode for a period of time sufficient to deposit copper on the substrate up to 42. the desired thickness.   17 The method of claim 16, charac-   terrified in that the control of the temperature of the elec-   trolyte is made to provide a compressive temperature   between about 430 C and about 60 C.   18 The method of claim 16, charac-   terrified in that the control of the temperature of the electricity   trolyte is made to provide a compressive temperature   between about 49 C and about 60 C.   19 The method of claim 16, character-   laughed in that the passage of current between the anodes and   the cathode is made to provide a density of   cathode rant-from about 0.1 to about 8.0 A / dm 2.   Method according to claim 16, character-   laughed in that the passage of current between the anodes and   the cathode is made to provide a density of   cathode rant from about 0.5 to about 2.5 A / dm.   21 The method of claim 16, charac-   terized in that it further consists in maintaining the p H of   the electrolyte in a range from about 9.5 to about 10.   22 The method of claim 16, character-   laughed at in that it involves further maintaining the relationship   copper anode surface / ferrite anode surface in- about 1: 3 and about 1: 5.   23 The method of claim 16, charac-   terrified in that it also consists in maintaining the ratio   port copper anode surface / iron anode surface te at about 1: 4.   24 The method of claim 16, charac-   terized in that the flow of current is controlled to provide a deposit of copper on the substrate having a   average thickness of about 0.0038 mm and about 0.127 mm.   Process according to claim 16, charac-   terrified in that the flow of current is controlled during   for a period of time of approximately 1 minute to approximately 2 538815 43. 1 hour.   26 The method of claim 16, charac-   terized in that the flow of the current is controlled 81   in a time of about 2 to about 30 minutes.   27 A method according to claim 16 / characterized in that it also consists in restocking the transformation agent with complex and the carbonate compound to maintain the constituents of the bath in the desired operating range.   28 The method of claim 16, charac-   terized in that it also consists in controlling the report   port cathode surface / anode surface between approximately 1: 2 and approximately 1: 6.   29 The method of claim 16, charac-   terized in that it also consists in controlling the report   port cathode surface / anode surface between approximately 1: 3 and approximately 1: 5   Process according to claim 16, charac-   characterized in that it also consists in controlling the ratio of cathode surface area / anode surface area to a value about 1: 4.   31 Process for the electrolytic deposition of a thin coating of copper with refined, ductile and adherent grains on a conductive substrate based on ferrous material, characterized in that it consists in providing an aqueous alkaline electrolyte / free of cyanide, having a composition   as defined in claim 1, to check the con-   copper ion centration in a range of about 15 to   about 50 g / l, to control the temperature of the electrolyte   te at a value between about 38 C and about 71 C, immersing a ferrous-based conductive substrate to be coated as a cathode in the electrolyte, immersing a combination of a soluble anode based on   copper and an anode insoluble in ferrite in the electro   trolyte to provide a copper-surface to anode / 44 ratio. ferrite anode area of approximately 1: 2 to approximately 1: 6, to pass current between the anodes and the   cathode for a period of time sufficient to   lay copper on the ferrous base substrate to a desired thickness.   32 The method of claim 31, charac-   characterized in that it also consists in electrifying the ferrous-based substrate before and during immersion of the substrate in the electrolyte.   33 Process for electrolytically depositing   ticks a thin coating of copper with refined grains, ductile and adherent on a conductive substrate based on zinc, characterized in that it consists in providing an aqueous alkaline electrolyte free of cyanide, having a   composition as defined in claim 4, unless   control the temperature of the electrolyte between about 38 C and about 71 C, cathodically electrifying the conductive substrate based on zinc under a voltage of   minus about 3 volts and immerse the electric substrate   se in the electrolyte, immersing a combination of a soluble copper-based anode and an insoluble ferrite anode in the electrolyte to provide a ratio   copper anode surface / ferrite anode surface   about 1: 2 to about 1: 6, passing current between the anodes and the zinc-based substrate for a period of time sufficient to deposit copper on   the substrate to the desired thickness.   34 Process for electrolytically depositing   ticks a coating of copper with refined grains, ductile and adherent on a conductive substrate, characterized in that it consists in providing an aqueous electrolyte free   cyanide containing copper ions present in quanti-   sufficient to electrolytically deposit copper, a complexing agent present in sufficient quantity to chelate the copper ions present, 45. a buffer agent soluble in the bath and compatible with the bath present in sufficient quantity - to stabilize   the p H of the electrolyte, and of the hydroxyl and / or hy-   drogen present in quantity to provide a p H of approx.   ron 6 to about 10.5, to immerse a conductive substrate   to be coated as a cathode in the electrolyte, to be immersed   manage a combination of a soluble copper-based anode and an insoluble nickel-iron alloy anode containing   about 10% to about 40% by weight of iron in the elect   trolyte to provide a cooking surface anode ratio   glass / nickel-iron alloy anode surface from about 1: 2 to about 4: 1, and passing current between the anodes and the cathode for a period of time sufficient to deposit copper on the substrate to the desired thickness.   Method according to claim 34, characterized in that it further consists in controlling the   electrolyte temperature within approx. ron 38 WC to approximately 71 WC.   36 Method according to claim 34, characterized in that it further consists in controlling the   electrolyte temperature within approx. ron 430 C at around 60 C.   37 The method of claim 34, ca-   characterized in that it also consists in controlling the   electrolyte temperature within approx.   ron 49 WC at about 60 C. 38 A method according to claim 34,   characterized in that the cooking anode surface area ratio   glass / nickel-iron alloy anode surface is controlled   in a range of about 1: 1 to about 2: 1.   39 The method of claim 34, characterized in that it further comprises controlling the ratio of cathode surface / anode surface between approximately 1: 1 and approximately 1: 6.   46. The method of claim 34, characterized in that it further consists in controlling the ratio of cathode surface / anode surface between about 1: 3 and about 1: 5.   41 Method according to claim 34, characterized in that it further consists in controlling the ratio of cathode surface / anode surface to a value about 1: 4.   42 The method of claim 34, charac-   characterized in that the current flow between the anodes and the cathode is carried out to provide an average cathodic current density of about 0.1 to about 8.0 A / dm 2.   43 Method according to claim 34, charac-   terized in that the current flow between the anodes and the cathode is made to provide an average cathodic current density of about 0.5 to about 2.5 A / dm   44 The method of claim 34, charac-   terized in that it further consists in controlling the con-   centering of hydroxyl ions to provide a p Hi of about 9 to about 10.   Process according to claim 34, charac-   terized in that it further consists in electrifying the   cathodically conductive substrate before and from   the immersion of the substrate in the electrolyte.   46 The method of claim 45, charac-   terized in that the electrification of the conductive substrate is carried out at a voltage of at least about 3 volts   before and during the immersion of the substrate in the electrolyte.   47 The method of claim 34, charac-   terized in that the insoluble nickel-iron alloy anode   contains about 15% to about 30% by weight of iron.   48 The method of claim 34, charac-   terized in that the nickel-iron alloy anode contains 47. % to about 25% by weight of iron.   49 method according to claim 34, charac-   terized in that the nickel-iron alloy anode contains   additionally about 0.005 to about 0.06% sulfur.   50 Method according to re Vendication 34, characterized in that the nickel-iron alloy anode contains   additionally about 0.01 to about 0.04% sulfur.   51 Anode suitable for use in the electrolytic deposition of copper from a   cyanide-free aqueous electrolyte on a suitable substrate   conductor, characterized in that it comprises an electrically conductive core (or central part) having an adherent coating, substantially non-porous, on at least part of its external surface, the nickel-iron alloy containing about 10 to about% by weight, approximately 0.005 to approximately 0.06% by weight of sulfur, the balance being essentially nickel,   the coating having a thickness of at least about- 0.025 mm.   52 Anode according to claim 51, -   characterized in that the nickel-iron alloy contains   about 15 to about 30% by weight of iron and about 0.01 to about 0.04% by weight of sulfur   53 Anode according to claim 51, charac-   terized in that the nickel-iron alloy contains about   about 25% by weight of iron and about 0.02% 0.03% by weight of sulfur.