Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
• • 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
• • 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
  • C23C18/52—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 using reducing agents for coating with metallic material not provided for in a single one of groups C23C18/32 - C23C18/50

Definitions

• the invention relates to a method for electroless deposition of metal layers on surfaces of correspondingly less noble metals.
• Metal objects covered with metal layers play in numerous areas of technology, such as in electrical engineering, electronics, in the construction of medical devices, in restoration technology, in corrosion protection, in the jewelry industry, finishing technology, space travel, in mechanics, but also in teaching increasingly matter.
• GB-A - 1 411 971 describes a process for dip coating iron or steel with copper using an aqueous bath which contains a water-soluble copper salt, an agent capable of complexing with Cu (II) ions and a conjugated unsaturated nitrile or oxime .
• an aqueous bath containing a Cu complex which is obtained by reacting CuCl 2 with the hydrochloride of a base, is described by GB-A-1 411 971.
• the object of the present invention is to provide a method for the electroless deposition of metal layers which avoids the disadvantages shown and which enables the production of well-adhering layers with sufficient layer thicknesses. This object is achieved with the present invention.
• the invention relates to a method for the electroless deposition of metal layers of metals from groups Ib, IIb, IVb, Vb and VIII of the periodic table on correspondingly less noble metals by contacting the object to be coated with a non-aqueous coating bath which contains a metal complex which is formed by reacting a corresponding divalent or trivalent metal chloride with the hydrochloride of a base which is capable of complexing with the metal, or is obtained with the free base and hydrochloric acid.
• Electroless is understood to mean that during the deposition process, no voltage is applied to either the coating bath or the workpiece to be coated.
• Metal halide compounds can also be used for the preparation of the coating bath, or metal compounds which react easily with chlorides to form the corresponding metal chlorides, for example w-complexes of the platinum metals of the eighth group with two metal atoms, such as, for example, ⁇ -dichlorotetraethylenedirhodium (I) and ⁇ -dichlorotetracarbonyldirhodium- (1).
• the metal chlorides especially in the case of the non-platinum metals, the corresponding oxides or hydroxides can also be used together with the equivalent amount of hydrochloric acid.
• Divalent or trivalent metals of group Ib, IIb, IVb, Vb and VIII of the periodic table are preferably iron, cobalt, nickel, copper, cadmium, tin, lead, antimony, bismuth, and the platinum metals ruthenium, rhodium, palladium, osmium, iridium and platinum.
• the platinum metals are preferably deposited on copper, silver or less noble metals, the metals cobalt, nickel, copper, cadmium, tin, lead, antimony and bismuth preferably on iron, the metals antimony, nickel or bismuth preferably on copper.
• Inorganic bases e.g. B. hydrazine, hydroxylamine and especially ammonia
• organic bases preferably basic nitrogen-containing compounds, and in particular primary, secondary or tertiary amines and basic nitrogen heterocycles, such as methylamine, ethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, aniline, piperidine, morpholine , Pyridine or aminoacetic acid ethyl ester, but also for example 2-aminopropane, cyclohexylamine, benzylamine, 1-amino-4-methyl-bicyclo [2.2.2] octane, 1-aminoadamantane, glycine methyl ester or glycine ethyl ester, N-methylmorpholine, N-methyl- 2-pyrrolidinone, N-formylpyrrolidine, 1-azabicyclo [2.2.2] octane hydrochloride or quinoline
• the reaction of the metal chloride with the base and the hydrochloric acid or the hydrochloride of the base can be done by simply mixing these components together.
• the reaction can be carried out without or preferably in the presence of a solvent, and an excess of base can also serve as the solvent.
• the molar ratio of hydrochloride of the base / metal chloride is chosen at least as follows. That the entire amount of metal chloride is dissolved in the reaction. It is preferably in the range from 0.5 to 40/1, in particular from 2 to 6/1. however, the molar value of the hydrochloride can also be substantially higher and can be, for example, 180 times the molar amount. The most favorable molar ratio depends in particular on the type of implementation.
• Suitable solvents are inert to the complex formation reaction, especially aprotic organic solvents, such as dimethylformamide, dimethyl sulfoxide. Carbon tetrachloride, acetone, or mixtures thereof.
• the solvents have to be weaker basic than the base used.
• the reaction is carried out at room temperature or with heating, preferably between 20 and 150 ° C. and in particular between 70 and 150 ° C, carried out.
• basic cleavage products result, in particular in the case of bases sensitive to hydrolysis, which in turn produce hydrochloride with hydrochloric acid and complex with the metal chloride.
• formamides such as dimethylformamide are reacted with hydrochloric acid and metal chloride in the heat.
• Cleavage occurs in formic acid and amine, the latter then immediately reacts to form the hydrochloride, which is the actually complexing agent.
• the metal chloride is preferably added in finely powdered form; the hydrochloric acid can be added in liquid form or introduced in gaseous form.
• the reaction can be carried out by first forming the base hydrochloride, to which the metal chloride is then added in a suitable solvent.
• the metal salt can also be added to a mixture of base and acid without prior isolation of the hydrochloride.
• the metal chloride is reacted with a mixture of the hydrochloride and the free base, for example in a ratio of 2/1.
• the metal chloride is, for example, rhodium (III) chloride trihydrate, with mechanical stirring with 2 to 4 mol of hydrochloride (for example amine hydrochloride, ammonium chloride) or with 2 mol of hydrochloride and 1 mol of the free one Base in an organic solvent, for example dimethylformamide, reacted at 20 to 140 ° C.
• the reaction time is about 1 to 48 hours, but at least until the metal chloride and the hydrochloride have completely dissolved.
• the water used to dissolve the hydrochloride should be evaporated as far as possible. It is therefore preferable to heat slightly above 100 ° C. in an unsealed reaction vessel, with the greatest amount of water used evaporating slowly.
• a water-free reaction solution obtained can, if appropriate after dilution with a suitable solvent, such as.
• a suitable solvent such as.
• DMSO dimethyl sulfoxide
• metal plating solution metal plating solution
• the reaction solution is to be used directly without prior isolation of the metal complex compound, it is expedient, for example, to use the following process: the metal chloride, for example rhodium (III) chloride, but also, for example, ⁇ -dichlorotetraethylene dirhodium (I) or li -Dichlorotetracarbonyldirhodium- (1), with 0.5 to 5.0 times the molar amount of the base and with an excess of hydrochloric acid (or with the hydrochlorides of the base in the appropriate molar ratio) in a suitable solvent, preferably for example dimethyl sulfoxide , implemented at temperatures between 20 and 150 ° C.
• a suitable solvent preferably for example dimethyl sulfoxide
• the metal complexes are preferably isolated from their reaction solutions and only dissolved again shortly before use.
• the metal complexes can be obtained by cooling the reaction solution, for example to 20 to 0 ° C., or by diluting the reaction solutions with a solvent which is poorly soluble in the complexes, for example with acetone, acetonitrile, primary alcohols, diethyl ether, cyclohexane, chloroform or mixtures thereof, be isolated.
• the complex which precipitates on cooling when using a solvent which poorly dissolves the complex formed is expediently recrystallized before further use.
• a solvent that dissolves the complex well such as dimethylformamide
• the complex crystallizes after the solution has cooled and the addition of a multiple, for example two to ten times the amount of a poorly dissolving solvent, such as Acetone.
• a poorly dissolving solvent such as Acetone.
• the filtrate obtained can be heated again with the hydrochloride after the solvent has been distilled off, with what is still in solution Metal chloride is transferred to the complex).
• the solvent can also be distilled off in whole or in part and the residue can then be crystallized, for example by rubbing with a solvent suitable for the precipitation, for example with acetone.
• the coating bath can then be obtained from these complexes if necessary by dissolving them in a suitable solvent.
• suitable solvents are polar, non-aqueous solvents, for example formamides, such as, for example, dimethylformamide, acetamides, N-methyl-2-pyrrolidinone, cyclic ketones, such as, for example, cyclohexanone, aromatics, higher-boiling ethers, tetrahydrofuran, dioxane, alcohols, and in particular Sulfoxides, such as dimethyl sulfoxide (DMSO), and also their mixtures, in particular with dimethyl sulfoxide.
• DMSO dimethyl sulfoxide
• the dissolution can take place at room temperature or with heating, for example to 100 to 180 ° C.
• the platinum metal complexes are preferably dissolved by heating to 100 to 160 ° C. To avoid decomposition of the complex and to maintain the separation quality and stability, overheating should be avoided.
• the concentration of the metal complexes in the coating solution can be varied within wide limits. As a rule, it is 0.01 to 5.0% by weight, in particular 0.1 to 1.0% by weight.
• a complex-forming component base, metal or hydrochloric acid
• base metal or hydrochloric acid
• metal substrate onto which deposition will take place
• type used Reaction conditions such as the type of solvent. It is also possible to use two or more bases. Platinum metal mixtures can also be deposited, for example.
• the metal layers are deposited on the substrate by the methods customary for electroless deposition from coating baths, in particular by immersing the objects to be coated in the deposition bath.
• the objects to be coated can generally have any shape, which is determined in particular by the later intended use.
• the duration of the contact time depends primarily on the deposition speed and the desired layer thickness.
• the deposition process can be interrupted at any time (e.g. by removing the workpiece from the solution) and, after inspecting the coating, continued by bringing it into contact again. This process can be repeated any number of times until the desired layer thickness is reached. After reaching the desired layer thickness, residues of the coating bath with a suitable solvent, such as. B. with methanol, ethanol or acetone, removed and the workpiece dried, for. B. by wiping with a cloth.
• a suitable solvent such as. B. with methanol, ethanol or acetone
• the quality of the coating depends to a large extent on the rate of deposition. Deposition that is too rapid (reactivity that is too high) generally results in a poorly adhering “amorphous coating” than with a coating bath with lower reactivity.
• Favorable coating times are between one minute and one hour.
• the deposition rate (reactivity) of the coating bath can be adjusted by suitable selection and combination of the complex-forming components. However, it is also dependent on the concentration of the metal complex in the coating bath and / or the acid concentration. As a rule, the deposition rate increases with increasing concentration of metal complex. From very concentrated solutions, the deposition z. B. done in a few seconds.
• the complex-forming components especially base and hydrogen chloride acid
• Selectivity is also closely related to reactivity. So z. B. the deposition rate for a particular metal can be regulated by varying the amounts of acid. A change in the concentration of the metal complexes usually only affects the deposition rate.
• the deposition of the metals is usually carried out at a bath temperature of 20 to 180 ° C.
• the most favorable temperature depends in particular on the solvent used, on the type of metal deposited and primarily on the type of metal complex.
• the bath temperature is preferably 100 to 170 ° C.
• the duration of the coating process can be from one minute to several hours.
• the layer thicknesses that can be achieved are generally proportional to the metal complex concentration of the coating bath and the contact time.
• a suitable choice of the deposition conditions generally gives layer thicknesses of 0.01 to> 1 J.Lm.
• the concentration of the individual coating baths is preferably increased successively.
• the deposition of rhodium or another platinum metal is expediently carried out in succession with several, for example three, coating baths whose complex salt concentration in three coating baths is 0.6, 0.8 and 1.0% by weight, with for layer thicknesses> 1 I Lm the temperature increases from level to level, e.g. starts at a temperature of 110 ° C and then increases the temperature by 3 to 5 ° C.
• dimethyl sulfoxide is used as the solvent.
• the individual coating steps can also be carried out by working with baths which contain different complexes.
• a coating bath can also contain a mixture of two or more metal complexes, as a result of which the adhesive strength and / or layer thickness can be increased, in particular in the case of the platinum metals.
• Small layer thicknesses of up to approx. 0.05 J.Lm can be achieved, for example, in less than 5 minutes if one works with high complex salt concentrations, for example with 2% by weight, near the boiling point of the solvent.
• the invention therefore also relates to a coating bath for the electroless deposition of metal layers of metals from group Ib, Ilb, IVb, Vb and VIII of the periodic table on correspondingly less noble metals, which is characterized in that it contains a metal complex in a non-aqueous solvent which by reacting the corresponding di- or trivalent metal chloride with the hydrochloride of a base which is capable of complexing with the metal.
• 0.5 ml of concentrated hydrochloric acid (density approx. 1.19) are added to 20 ml of dimethylformamide and heated to 50 ° C. for 10 minutes. Dimethylformamide is partially hydrolyzed to dimethylamine. This solution is then mixed with 0.5 g (2 mmol) of rhodium (III) chloride trihydrate and stirred at 50 ° C for 2 hours. After cooling and diluting with 100 ml of acetone after stirring for 3 hours at room temperature, 0.7 g of red needles crystallize from the deep red solution.
• Table 1 below shows the melting point and color of some rhodium complexes prepared analogously to Examples 1 to 6.
• the layer thickness of the rhodium deposited on the copper sheet is 0.1 ⁇ m, provided a rhodium complex formed from rhodium (111) chloride trihydrate and dimethylamine hydrochloride in dimethylformamide has been used.
• This coating process is repeated two more times, each time using a new rhodium complex-dimethylsulfoxide-sodium fluoride solution to achieve greater layer thicknesses of the rhodium deposition with optimal quality of the structure of the deposited metal.
• the rhodium coating is 0.32 ⁇ m and after the third coating 0.60 wm.
• the bath temperature is increased to 125 ° C for the second coating and to 130 ° C for the third coating.
• Approx. 25 mg of a mixture of 1.04 g (4 mmol) of ruthenium (II) chloride trihydrate and 5.9 g of morpholine hydrochloride are added to 5 to 7 ml of N-methylpyrrolidin-2-one, which has been preheated to 160.degree .
• the metal to be coated preferably copper or silver, is placed in this solution and left in the bath for 15 to 20 minutes.
• Cobalt complex of cobalt (II) chloride and morpholine hydrochloride Cobalt complex of cobalt (II) chloride and morpholine hydrochloride
• Cadmium complex of cadmium chloride and morpholine hydrochloride 1.15 g CdCl 2 . 2.5 H 2 0 are added to a slurry of 1.5 g (12.5 mmol) of morpholine hydrochloride in 10 ml of dimethylformamide and stirred at 40 ° C for one hour. After cooling, it is diluted with 100 ml of acetone. Colorless plates fall out in the refrigerator, which are suctioned off after 18 hours and washed with acetone; Melting point 138 ° C.
• Bismuth complex consisting of bismuth oxychloride and morpholine hydrochloride
• Nickel complex of nickel (II) chloride and morpholine hydrochloride Nickel complex of nickel (II) chloride and morpholine hydrochloride
• Tin complex of tin (II) chloride and pyridine hydrochloride Tin complex of tin (II) chloride and pyridine hydrochloride
• Example 20 25 mg of the tin complex described in Example 20 are dissolved hot in 5 ml of dimethylformamide and 10 mg of ammonium fluoride are added. After the solution has cooled to 50 ° C., an oxide-free, ordinary iron sheet is coated for 30 minutes by immersion. A light, firmly adhering coating is created.
• Example 13 20 mg of the cobalt complex described in Example 13 are heated to 90 ° C. together with 10 mg of ammonium fluoride in 5 ml of dimethyl sulfoxide. Then an oxide-free, ordinary iron sheet (4 cm 2 ) is immersed for 30 minutes. After washing with water, the sheet is covered with a light, well-adhering cobalt layer.
• Example 14 10 mg of the cadmium complex described in Example 14 are dissolved hot in 5 ml of dimethylformamide and 5 mg of ammonium fluoride are added. After cooling to 20 ° C, an oxide-free, ordinary iron sheet (4 cm 2 ) is immersed and left for 50 minutes. It is then covered with a light, well-adhering layer of cadmium.
• a solution of 20 mg of the morpholine-copper complex given in Example 17 in 5 ml of dimethyl sulfoxide is heated to 90 ° C. and the oxide-free iron sheet is immersed. After 5 minutes, the sheet is coated with copper.
• Example 18 20 mg of the morpholine-nickel complex given in Example 18 are dissolved in 5 ml of dimethyl sulfoxide and heated to 105 ° C. together with 5 mg of ammonium fluoride in 5 mg of sodium fluoride. An oxide-free, ordinary iron sheet is immersed and left for 15 minutes. A shiny, firmly adhering nickel coating is created.
• Example 19 25 mg of the lead complex specified in Example 19 are dissolved together with 5 mg of ammonium fluoride in 5 ml of hot dimethylformamide. After cooling to 20 ° C, the oxide-free iron sheet is immersed and left at room temperature for 60 minutes. A firmly adhering lead coating forms.
• Example 18 40 mg of the nickel complex given in Example 18 are heated to 120 ° C. together with 5 mg of sodium fluoride and 5 mg of ammonium fluoride in 5 ml of dimethyl sulfoxide. Then a copper sheet cleaned by customary methods is immersed calmly for 30 minutes. A silvery, firmly adhering nickel coating forms.
• BiOCI 0.1 g of BiOCI is slurried in 50 ml of N-methylpyrrolidin-2-one and 0.25 ml of concentrated hydrochloric acid is added. The salt dissolves completely. Then the oxide-free copper sheet is immersed and left for 5 minutes. It is then covered with a firmly adhering layer of bismuth.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Electrochemistry (AREA)
• Chemically Coating (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

Family

ID=6174496

Family Applications (1)

Country Status (5)

Cited By (1)

Families Citing this family (5)

Family Cites Families (2)

• 1982
  • 1982-09-29 DE DE19823236115 patent/DE3236115A1/de not_active Withdrawn
• 1983
  • 1983-09-28 AT AT83109721T patent/ATE27468T1/de not_active IP Right Cessation
  • 1983-09-28 DE DE8383109721T patent/DE3371799D1/de not_active Expired
  • 1983-09-28 CA CA000437873A patent/CA1209412A/en not_active Expired
  • 1983-09-28 EP EP83109721A patent/EP0107801B1/de not_active Expired
  • 1983-09-29 JP JP58179460A patent/JPS5980767A/ja active Granted

Also Published As

Similar Documents

Legal Events