Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/54—Contact plating, i.e. electroless electrochemical plating
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/31—Coating with metals
  • C23C18/32—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron
  • C23C18/34—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents
  • C23C18/36—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents using hypophosphites
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/1601—Process or apparatus
  • C23C18/1617—Purification and regeneration of coating baths
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/1601—Process or apparatus
  • C23C18/1633—Process of electroless plating
  • C23C18/1655—Process features
  • C23C18/1662—Use of incorporated material in the solution or dispersion, e.g. particles, whiskers, wires

Definitions

• This invention relates to an electrolyte for electroless deposition of residual pressure nickel layers containing a metal base salt, a reducing agent, a complexing agent, an accelerator and a stabilizer.
• the electroless plating with metals is based on an autocatalytic process, so that it is also referred to as autocatalytic coating.
• the electrolyte In order to reduce the metal ions contained in the deposition bath (electrolyte) to elemental metal in such a coating process, the electrolyte must be added to a corresponding reducing agent, which is oxidized during the reaction itself.
• other components such as phosphorus and / or additional metals, such as copper, etc., are often incorporated into the coating.
• phosphorus has a significant influence on layer properties such as hardness and corrosion resistance, this is selectively introduced depending on the intended use of the coated article. For example, in the case of non-magnetic coatings with maximum hardness, a phosphorus content of ⁇ 10% by weight is desired. In addition, such electroless deposited metal-phosphorus coatings have a higher hardness and better wear resistance than electrodeposited coatings.
• hypophosphite baths for electroless deposition of metals tend to become unstable during deposition, as the concentration of metal and hypophosphite ion progressively decreases as the concentration of orthophosphite ion continues to increase and the counterions of the metal and hypophosphite ions increase Form of, for example, sodium sulfate. The electrolyte is thus consumed ".
• the lifetime of such electroless baths is thus limited because the electrolyte can only be used for a certain number of coating runs with uniform coating results.
• the age of a bath is usually given in metal turn-over (MTO), where 1 MTO is equal to the amount of metal deposited from the bath. This corresponds to the originally used concentration of the metal ions, in each case based on the total volume of the bath, in the bath.
• MTO metal turn-over
• the degradation products in the electrolyte reach such a high concentration after about 5 to 10 MTO that a high deposition rate and a consistently high quality of the deposited metal can no longer be guaranteed.
• the electrolyte is then either to replace or regenerate using appropriate tools.
• the regeneration of an electrolyte for nickel deposition means at least withdrawing the resulting orthophosphite as reaction products and optionally an addition of metal and Hypophosphitionen.
• interfering components are separated from the bath, for example by adsorption on ion exchange resins or by electrodialytic processes. Although such methods allow a significantly longer life of the baths, but they are usually connected by the complex structure, etc. with very high operating costs.
• the invention has for its object to provide an electrolyte for electroless deposition of Nichel, from the over a long period uniform, pore and crack-free metal-phosphorus coatings with constant layer properties and high phosphorus content, at an increased deposition rate, can be deposited. It is also an object of the present invention to provide an electrolyte having high stability and durability, which contains complexing agents and stabilizers which are effective in a wide volume range and greatly contribute to increasing the deposition rate and prolonging the life of the bath. Another object of the present invention is to provide a process for the electroless deposition of nickel with compressive residual stress.
• the object is achieved by means of an electrolyte according to claim 1 .
• the publication DE 40 05 088 discloses a saccarin-containing nickel plating bath for electroless deposition of uniformly blackened nickel layers.
• the patent US 3, 597, 267 discloses a nickel acetate-containing electrolyte for the electroless deposition of nickel at a high deposition rate.
• the disadvantages known in the state of the art are eliminated by providing a novel composition of the electrolyte and in this way achieving considerably better deposition conditions, thereby simplifying implementation and making it more economical.
• This is primarily due to the advantageous composition of the electrolyte.
• metal salts whose anions are volatile, preferably metal acetates as the electrolyte base salt, the life of the electrolyte at high deposition rates and uniformly deposited layers with constant layer properties can be significantly extended.
• the electrolyte of the invention is basically composed of one or more metal base salts selected from the group consisting of nickel acetate, nickel formate, nickel oxalate, nickel nitrate, nickel propionate, nickel citrate and nichel ascorbate, preferably metal acetate and a reducing agent, sodium hypophosphite.
• various additives such as complexing agents, accelerators and stabilizers, which are advantageously used in acidic electrolytes for the electroless deposition of nickel, are added to the electrolyte. Since the deposition rate is significantly higher in an acidic medium, an acid is preferably added to the electrolyte as a complexing agent.
• carboxylic acids and / or polycarboxylic acids turns out to be particularly advantageous since, on the one hand, it determines the advantageous solubility of the metal salts and the controlled control of the free metal ions and, on the other hand, prescribes the adjustment of the pH required for the process due to their acid strength . facilitated.
• the pH of the electrolyte is advantageously in the range of 4.0 to 5.2.
• the dissolved metal is particularly advantageously complexed by the use of carboxylic acids and / or polycarboxylic acids whose salts and / or derivatives, preferably hydroxy (poly) carboxylic acids, particularly preferably 2-hydroxypropanoic acid and / or propanedioic acid. At the same time, these compounds serve as activators and as pH buffers and contribute significantly to the stability of the bath by their advantageous properties.
• a sulfur-containing heterocycle is added to the electrolyte as accelerator.
• the sulfur-containing heterocycle used is saccharin, its salts and / or derivatives, particularly preferably sodium saccharin.
• the addition of saccharinate, even in higher concentrations, does not adversely affect the corrosion resistance of the deposited metal layers.
• a stabilizer is added to the electrolyte according to the invention in order to counteract a spontaneous decomposition of the metallizing bath.
• a stabilizer may be, for example, metals, halogen compounds and / or sulfur compounds, such as thioureas.
• metals as stabilizers has proved to be particularly advantageous.
• These salts are preferably one or more of the salts from the group consisting of acetates, formates, nitrates, oxalates, propionates, citrates and ascorbinates, more preferably acetates.
• the metal layers should have, besides phosphorus further components, such as, for example, additional metals, preferably cobalt, and / or finely dispersed particles are incorporated into the layer.
• additional components such as, for example, salts, preferably potassium iodide.
• the quality of the metallizing bath is surprisingly improved and the service life is considerably prolonged.
• the metallization of the surface is improved, especially by more complex substrates.
• the corrosion-resistant metal layers deposited according to the invention are suitable for coating keys or locks, valves, pipelines, etc. Due to the high phosphorus content, the layer becomes non-magnetic and is therefore ideal for coating connectors and contacts as well as housings for electronic devices, etc. Due to the very good wear resistance, the layers produced by the method according to the invention are preferably used in the field of mechanical engineering for coating running surfaces, couplings, pump housings, etc.
• the method proposed by the invention is characterized in particular by the composition of the electrolyte. It is therefore advantageously in an economical and environmentally friendly compared to the conventional methods.
• the electrolyte according to the invention can be regenerated, for example, by means of electrodialytic method.
• metal salts whose anions are volatile the separation effect of the electrodialysis plant is significantly increased.
• the number of electrolysis cells for separating Ortophosphitionen can be reduced at the same separation efficiency.
• the base electrolyte of the electrolyte according to the invention is applied.
• This contains essentially the following composition: 4 - 6 g / l nickel ions 25 - 60 g / l reducing agent 25 - 70 g / l complexing 1 - 25 g / l accelerated 0.1-2 mg / l stabilizer 0-3 g / l other ingredients
• metal salts whose anions are volatile are used as metal receivers.
• metal salts whose anions are volatile one or more salts from the group consisting of metal acetates, metal formates, metal nitrates, metal oxalates, metal propionates, metal citrates and Metallascorbinaten, more preferably exclusively metal acetate are used.
• the electrolyte according to the invention thus operates throughout the deposition process in a pH range of 4.0 to 5.2, preferably 4.3 to 4.8, without having to be additionally added larger amounts of alkaline media. Due to the extremely advantageous pH self-regulation can be dispensed with during the process on a continuous pH control and alkaline additives.
• the starting concentration of the metal-base salts is 0.04 to 0.16 mol / l, preferably 0.048 to 0.105 mol / l, based on nickel, the content of metal being between 0.068 and 0.102 mol / l, preferably 0.085 mol / l.
• the reducing agent used is preferably sodium hypophosphite having a starting concentration of 25 to 65 g / l.
• the complexing agents used are carboxylic acids and / or polycarboxylic acids, their salts and / or derivatives, preferably hydroxy (poly) carboxylic acids, particularly preferably 2-hydroxypropanoic acid and / or propanedioic acid.
• the dissolved nickel is particularly advantageously complexed, so that the deposition rate can be maintained in a corresponding interval of 7 to 14 .mu.m / h, preferably 9 to 12 .mu.m / h with continuous addition of such complexing agents.
• the starting concentration of the complexing agent in the base electrolyte is between 25 and 70 g / l, preferably 30 to 65 g / l.
• the starting concentration of the accelerator is 2.5 to 22 g / l.
• Stabilizers used are halogen compound and / or sulfur compound, preferably thiourea.
• These salts are preferably selected from the group consisting of acetates, formates, nitrates, oxalates, propionates, citrates and ascorbinates. Very particular preference is given to the nitrates of the metals used as stabilizers.
• the starting concentrations of the stabilizers are advantageously from 0.1 to 2 mg / l, preferably from 0.3 to 1 mg / l.
• further constituents for example potassium iodide, in a starting concentration of 0 to 3 g / l may also be added to the base electrolyte.
• this basic electrolyte a variety of substrates are introduced and galvanized. To support the lifetime and the stability of the electrolyte, it can be regenerated during the deposition process by means of electrodialysis and / or ion exchange resins. Likewise, supplemental solutions (as exemplified below) may be added to the electrolyte during the deposition process. These replenisher solutions are specially designed to control the individual contents of the basic components and added to the electrolyte in different amounts.
• a first replenisher solution includes, for example, the following composition: 500 - 580 g / l reducing agent 5 - 15 g / l complexing 50-150 g / l alkaline buffer 11-20 g / l accelerator 0-3 g / l other ingredients
• the same substances as in the base electrolyte are advantageously used.
• the inventive method thus has a decided material cycle, which can be the process thus more economical and environmentally conscious.
• the complexing agent content and the content of alkaline buffer are chosen so that, taking into account possible carry-over losses of not more than 40%, an increase to a total content of the complexing agents in the electrolyte to 70 to 90 g / l.
• the content of the accelerator in the electrolyte is controlled so that, for example, in the case of a nickel electrolyte with the use of sodium saccharinate as accelerator per gram of deposited nickel between 0.100 and 0.200 g, preferably 0.150 g are added, wherein the proportion of carryover losses is taken into account. This ensures at the same time a continuous increase to 7.5 - 15 g / l.
• the following composition can be used: 10 - 50 g / l complexing 0.68 - 2.283 mol / l Metallrezipient 1 - 25 g / l accelerator 40-80 mg / l stabilizer
• the complexing agent of the second replenisher solution may be the same as in the first replenisher or, if necessary, another.
• a hydroxycarboxylic acid for example 2-hydroxypropanoic acid of 60 g / l
• propanedioic acid with a content of 0.5 g / l
• the content of propanedioic acid is then increased by 0.005 to 0.015 g / g of deposited nickel, taking into account the carry-over losses. Due to the continuous increase of propanedioic acid from 0.5 g / l to about 1.2 g / l at 16 MTO equal to 80 g Ni / l, the deposition rate is maintained at the specified interval.
• metal sulfate in addition to the metal base salts described so far, a deposition of adherent metal layers with compressive residual stresses is guaranteed up to a throughput of at least 14 MTO.
• metal-base salts whose anion has at least one carbon atom and which preferably originate from the group of acetates, formates, oxalates, propionates, citrates and ascorbinates, the lifetime of the electrolyte surprisingly increases to 22 MTO.
• the already mentioned compressive residual stress is an extremely important and very desirable layer property. It positively influences the bending cycle stress and increases the ductility. So z. For example, in the case of nickel, metal layers with a ductility of> 0.5% are deposited. Likewise, the residual compressive stresses have a positive effect on the corrosion resistance of the metal-phosphorus layers.
• additional metals preferably copper
• finely disperse particles such as finely dispersed fluorine-containing thermoset or thermosetting plastic
• composition electrolyte Supplementary solution RA Supplementary solution SA Nickel acetate 4-hydrate (g / l) 12.5 - 25.5 / 200 - 212 Sodium hypophosphite (g / l) 30 - 50 515-565 / Hydroxycarboxylic acid (g / l) 32 - 55 / 25 - 35 Hydroxypolycarboxylic acid (g / l) 0,5 - 5 / / Sodium saccharin (g / l) 2.5 - 22 12.5 - 15 / Potassium iodide (g / l) 0.1 - 2 1 - 2 / Lead acetate (mg / l) 0.3-1 / 60-65 Ammonia 25% by weight (ml / l) 100-150
• Such an electrolyte has a self-regulating pH range of 4.3 to 4.8 and allows deposition rates of 8 to 12 ⁇ m / hr.
• the internal stress of the layers deposited therefrom is -10 to -40 N / mm 2 .

Landscapes

• Chemical & Material Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Dispersion Chemistry (AREA)
• Electrochemistry (AREA)
• Chemically Coating (AREA)
• Electroplating And Plating Baths Therefor (AREA)
• Manufacture And Refinement Of Metals (AREA)

Applications Claiming Priority (2)

Publications (4)

Family

ID=32010257

Family Applications (1)

Country Status (8)

Families Citing this family (29)

Family Cites Families (38)

• 2002
  • 2002-10-04 DE DE10246453A patent/DE10246453A1/de not_active Ceased
• 2003
  • 2003-06-17 AT AT03013706T patent/ATE498707T1/de active
  • 2003-06-17 DE DE50313472T patent/DE50313472D1/de not_active Expired - Lifetime
  • 2003-06-17 ES ES03013706.1T patent/ES2357943T5/es not_active Expired - Lifetime
  • 2003-06-17 EP EP03013706.1A patent/EP1413646B2/de not_active Expired - Lifetime
  • 2003-09-28 CN CNB03160241XA patent/CN100366795C/zh not_active Expired - Lifetime
  • 2003-10-02 KR KR1020030068770A patent/KR101063851B1/ko active IP Right Grant
  • 2003-10-03 US US10/678,601 patent/US7846503B2/en active Active
  • 2003-10-06 JP JP2003346929A patent/JP4091518B2/ja not_active Expired - Lifetime

Also Published As

Similar Documents

Legal Events