DE2122455C3 - Aqueous solution for the electroless deposition of a nickel-copper-phosphorus alloy with a maximum of 25% by weight copper - Google Patents

Description

pH value and contains copper ions, for the production connection is, .ta η d

Son surface coatings with an improved 50 Hy ^ rosulfidio ^ n l.efert. ^^^ _{described i}

Look. Aqueous solutions which form the basis of the invention

Solutions and methods for currentless storage dei ^ 'G ^e g ^en ^

The formation of coatings containing nickel on a solution results in _{corrosion resistance are constantly}

Substrates, for example, from the ^^ f _{2 55} ^ fri ^ are excellent as decorative protective coatings

known.

for the stron, - She ^ besTc "is, as the Lrr" sionsbes _ta ndi _gk ei, de.

tune should prevent.

stratification baths always use sulfur or sulfur compounds contained in stabilizing amounts because sulfur is known as an excellent bath stabilizer is, it is according to the application by boiling off even the last traces of sulfur compounds that are in the Solution to supply sulfide and / or hyposulfide ions, succeeded in specifying a bath, with the help of Jessen Surprisingly effective way is possible to produce bright, highly glossy, ductile coatings. A stabilization the aqueous solution according to the invention by means of sulfide ions or hydrosulfide ions is not required. It is assumed that the copper (I) ions contained in the aqueous solution according to the invention have a stabilizing effect on the aqueous solution.

From "Metallwissenschaft und Technik", February 1960, issue 2, pp. 109 to 112, it is already known that copper (I) ions in aqueous coating baths accelerate the electroless nickel deposition, of a stabilizing effect on the aqueous bath and of the use of However, it does not speak of copper (I) ions in sulfur-free coating baths.

Similar, albeit somewhat less advantageous results are obtained when using the aqueous solution of the invention, which is practically free of a sulfur compound that is sulfide and / or in the solution Provides hydrosulfide ions, adds copper (II) ions. This will also change the look of the using This solution significantly improves the nickel alloy coatings, albeit the The stability of this solution and the corrosion resistance of the coatings produced with it are somewhat lower are than when using copper (I) ions or a combination of copper (I) and copper (II) ions. When the aqueous solution of the invention contains only copper (H) ions, it is appropriate to give her one add another bath stabilizer that is not a sulfur compound contained in the Solution supplies sulfide and / or hydrosulfide ions.

The subject matter of the invention aqueous solution for the electroless deposition of a Nickel-copper-phosphorus alloy with a maximum of 25 percent by weight copper, which in addition to nickel ions, Hypophosphite, a buffer and copper (I) - and / or copper (II) -iomm optionally also a complexing agent for which may contain nickel and / or copper ions, preferably has a pH value between 4.0 and 13.0, in particular between 4.0 and 5.5, and it preferably contains 5 to 200, in particular 15 to 100 ppm copper (I) ions.

The invention is explained in more detail below with reference to the drawings. It shows

Figure 1 is a graph of copper concentration in a nickel-copper-phosphorus alloy coating as a function of the pH of the electroless aqueous coating solution with the help of which the coating has been produced,

F i g. Figure 2 is a graph of the concentration of copper in a nickel-copper-phosphorus alloy coating as a function of the copper ion concentration in the one used for its manufacture electroless aqueous coating solution,

F i g. 3 four photomicrographs of the surface of various alloy coatings with and without Copper and / or coprecipitated sulfur and

F i g. Figure 4 shows two photomicrographs of the cross-section of two using those of the invention Alloy coatings produced by aqueous solution.

As already mentioned, it is assumed that the copper (I) ions are responsible for the increased stability of the bath, which increased corrosion resistance of the deposit and the improved appearance of the deposit and that the cupric ions provide a deposit with an improved appearance. Consequently Both copper (I) and copper (II) compounds can be used to form an electroless nickel deposition solution can be added, the copper (I) compounds being preferred.

Both the simple and the complex copper compounds that are soluble in the electroless plating solution are suitable as a source of the copper ions for the purposes of the present invention. Typical examples of suitable compounds are copper (I) acetate, copper (II) acetate, copper (I) benzoate, Copper (II) benzoate, copper (I) bromide, copper (II) citra £, Copper (II) bromide, copper (I) carbonate, copper (II) carbonate, copper (I) chloride, copper (II) chloride, Copper (I) fluoride, copper (II) fluoride, copper (II) nitrate, Copper (I) hydroxide, copper (II) sulfate, copper (I) ammonium chloride and copper (II) ammonium chloride.

A complexing agent may be required to keep the copper in solution, especially if when the copper is present in relatively large quantities. Complexing agents for copper are

and is described, for example, in US Pat. Nos. 29 38 805, 33 12 430 and 33 83 224.

With regard to the copper (I) compound, it should be noted that many of these compounds are in aqueous Solution are not completely soluble and that some are even insoluble. The copper (I) compound is however for the purposes of the present invention only in such an amount required the concentrations of copper (I) ions on the order of only a few parts per million (ppm). Consequently it is sufficient if copper (I) compounds which are regarded as practically insoluble in aqueous solution are soluble to such an extent that they provide copper (I) ions, the concentration of which for the purposes of the present invention is sufficient.

Slightly soluble copper (I) compounds sine ¹ preferred.

When they are used, metal deposits build up from the coating solution Copper and nickel together form a nickel-copper-phosphorus alloy. There are several Factors related to the amount of copper co-deposited in the electroless alloy stand. One such factor is, for example, the pH of the solution, and it has been found

that a lower pH value, especially below 4.5, a higher concentration of the co-deposited Copper favors. The relationship between the pH of the solution and the concentration of the co-deposited Copper is shown in FIG. 1, in which, for explanatory purposes, the currentless solution of the Example 1 below was used under the specified conditions, the 200 ppm Copper (I) ions in the form of copper (I) chloride had been added. The pH value was increased by adding

there would be set of ammonium hydroxide. From Fig. 1 it can be seen that copper deposition increases significantly as the pH falls below 5.0.

Another factor affecting the copper concentration

What seems to affect the deposit is the copper concentration in the plating solution. This relationship is shown in FIG. 2 for an acid bath, curve A illustrating the relationship between the content of copper (I) ions in the solution and the copper content in the nickel deposit obtained, while curve B illustrates the relationship between the copper (II) content in the solution and the copper content in the deposit. The electroless deposition solution is that of Example 1 given below using the conditions given.

A third factor that appears to affect the concentration of copper in the deposit is temperature the solution. It has been found that in acid baths with a pH between about 4.0 and 5.0, the concentration of copper in the deposit increases significantly as the solution temperature drops to a value below about 88 ° C.

From the above it can be seen that the copper content in the deposit is proportionate can be high compared to the copper content in the solution, especially if the solution is at low pH, low solution temperature, or both. The above attempts show that copper deposition can and can be preferred to nickel deposition frequent regeneration with a copper salt may be necessary. Usually the copper concentration varies in the deposit between 0.1 and 12 percent by weight, but it can also be up to 25 percent by weight, especially in thin deposits, e.g. B. those with a thickness of 0.635 mm or less.

The numerical value for the copper concentration given in the deposit in the drawings can be a bit misleading. Without being bound by theory, it is believed that at least in acidic solutions with a pH value of less than 5 on a highly active surface the copper first alone or together with some nickel in the form of a thin film and then together with Nickel with the formation of a first layer, which is highly concentrated in copper, which is combined with Nickel and copper plated is deposited. It is believed that this is particularly the case at low pH of the solution and at a low bath temperature applies. As a result, it is believed that the total thickness of the deposit obtained from a boundary layer connected to the coated substrate in Contact is with the highest concentration of co-deposited copper and that of the substrate furthest surface with the lowest copper concentration, with between a copper concentration gradient exists in these two layers. If during the deposit If the solution is regenerated with copper for a certain substrate, then a Structure where the concentration is high in the part of the deposit that is at the time of regeneration is formed, whereby a new copper concentration gradient is created. This is in Figures 4A and 4B explained, which represent cross-sections through deposits, wherein in F i g. 4 A during the deposit was regenerated twice, while in Fig. 4B has not been regenerated. The layer structure is from FIG. 4 A clearly visible.

The amount of copper that can be tolerated in the solution depends on various factors. For example leads to a change in the basic solution, e.g. B. a change in relation to the complexing agent, a Change in relation to nickel or hypophosphite content. to a change in the maximum amount of copper tolerable in the solution. Besides that are the working conditions, e.g. B. the pH-Wcrt and the temperature, factors which lead to the maximum copper content in the solution in relation

ίο stand. In this regard it is preferred among Working conditions the content of copper (I) ions in the solution is preferably between 5 and 200 ppm of the solution, in particular between 15 and 100 ppm the solution, held. Working conditions preferred according to the invention are a pH between 4.0 and 7.0, preferably between 4.0 and 5.5. Within the pH range from 4.0 to 5.5 there is one preferred working temperature for the electroless solutions is at least 88 ° C. Under these conditions are at a relatively high concentration of the solution of copper (I), z. B. of more than about 200 ppm, for reasons not yet clear, deposits with a more matte than glossy appearance Appearance and a grainy structure. It should be noted that the specified here Copper ion concentration ranges are only guidelines and that the copper ion concentration in the Solution is most expediently kept at a value sufficient to achieve the goals set out above to achieve improved corrosion resistance and appearance while at the same time Avoidance of the formation of powdery, matt deposits.

As already stated above, increased bath stability is obtained when the copper is in the form of Copper (I) ions is present. Although electroless nickel solutions have been used for many years, The baths used to date have the disadvantage, as is known, that they are relatively result in low deposition rates and are unstable. It was also found that the rate of deposition to some extent on the concentration of the reducing agent or of the nickel ions present in the solution depends and that a higher concentration generally leads to a higher deposition rate leads. A higher concentration of reducing agent and / or nickel ions, however, leads to a lower bath stability. This manifests itself in a reduction in the period within which di < Solution is subject to uncontrollable decomposition. It is also known that certain additives, dii be added to an electroless nickel solution in properly controlled trace amounts as a stabilizer act and slow down the rate of bath decomposition. Generally these stabilizers represent each but are catalytic poisons and their concentration in the solution is very critical. Trace amounts, preferably within the range of a few ppr of the solution lead to stabilization depending on the special stabilizer used. An exercise The shot at the stabilizer partially or completely stops the electroless deposition of metal.

Such a stabilizer, which is also a catalytic poison. is for example in US Pat 27 62 723. In this patent eir acidic Nickclbeschichfunpslösung is described, the m Sulphide ions and a "sulphide ion regulator" are stable

is sated, which combines with the sulfide ions to prevent release from a hot or boiling solution. Such sulfide ion regulators are lead, bismuth. Tin. Selenium, tellurium. Tungsten, thorium, titanium, copper, zinc, manganese and rhenium. The sulfide ions, which are the active constituents of the stabilizing combination, are catalyst poisons and as such, slow down and prevent the deposition rate in trace amounts the deposition of larger quantities. According to the invention, small amounts of copper (I) ions become essential Better stability is achieved, and there is only a negligible effect on the rate of deposition, since copper (T) ions do not have a catalyst represent.

Regarding the use of sulfide ions as a stabilizer, as described in US Pat. No. 2,762,723 indicated, it has been found that the presence of sulfide ions or any other sulfur compound, which is deposited together with the Ni-Cu-P alloy at least partially without current and'odcr dissociates with the formation of sulfur in the solution in the form of the sulfide or hydrosulfide ion, disadvantageous both for the appearance of the deposit as well as for its other properties, such as corrosion resistance. Even though adding copper to the solution creates a nickel-copper-phosphorus alloy deposit supplies that are smooth and dense and therefore shiny in appearance and corrosion resistant, these go beneficial Properties lost when in the coating solution of the type described, sulfur is also present. Sulfur compounds found in The solution can be tolerated to a limited extent, are those that are covalently attached to carbon atoms are pcbunden, whereby the introduction of sulfur in the form of sulfide or hydrogen sulfide ions in the solution is prevented. The aqueous solution of the invention is preferably free from Sulfur compounds which dissociate in solution with the formation of disadvantageous sulfide and hydrosulfide compounds. and most preferred are those solutions that are free from all sulfur compounds are.

The effect of sulfur in the solution can be easily seen from Fig. Λ, which shows four photomicrographs illustrating the surface of four nickel flakes magnified 500O. Photomicrograph A shows a deposit of a nickel-hypophosphite solution free of both copper and sulfur compounds. From this it can be seen that the deposit has a rough, irregular appearance. Photomicrograph B shows a deposit from the same solution but containing 10 ppm thiourea based on the solution. There is little difference between the deposits in photomicrographs A and B. The photomicrograph shows a deposit made from the same solution as A , but containing 100 ppm Kiipfer (T) chloride. bczopen on the solution. A comparison of photomicrograph C with photomicrographs A and B shows the sharp contrast which consists in the fact that no imperfections at all can be seen on the surface of the deposit shown in photomicrograph Γ. Photomicrograph D shows a deposit from the same resolution as photomicrograph C. but contained 100 ppm of thiourea in the deposit. From this it can be seen that the deposit has a rough surface which is only slightly improved over the deposits shown in photomicrographs A and B.

The particular selected as the source of the copper ions for the purposes of the present invention Copper compound is not critical as long as it provides enough copper ions and as long as the anion

ίο the copper compound on the coating solution exerts no adverse influence. For example, it is known that certain anions are sufficient in large quantities, such as B. cyanide, for electroless plating solutions are harmful, and salts, which

is these anions or others known to be harmful Anions. should be avoided.

The solution according to the invention can contain hypophosphite as a reducing agent. It is known that the deposit obtained as an alloying element

ίο Removes phosphorus when the phosphorus content is in the Usually within the range of 5 to 15 percent by weight depending on numerous factors such as B. the ratio of hypophosphite to Nickel in the solution, the pH of the solution

u. the like. The most common area of such deposits using conventional known methods varies between 5 and 10 ^0. / o. although higher phosphorus contents within the range between 10 and 15 ° ο are also available if desired.

The electroless nickel alloy plating solution of the present invention is used in the same way to deposit a nickel alloy like the well-known electroless nickel solutions.

The surface of the substrate to be coated should be free from grease and contamination If the non-metallic surface is to be coated, the surface area on which the deposit is to be deposited must be should be applied, be sensitized first, to make it receptive to the inclusion of the electroless nickel alloy coating by one him in a known manner with an acidic aqueous solution of tin (II) chloride and then treated with a dilute aqueous acidic solution of palladium chloride. The awareness of non-metallic surfaces can also be achieved by using a Brings catalyst into contact by mixing tin dichloride and a noble metal chloride. preferably palladium chloride, the tin (TT) chloride in stoichiometric Excess over the amount of noble metal chloride is present.

For a better understanding, the invention is explained in more detail by means of the following examples, ir where the stability of a solution was determined by the time it took for a bath to spontaneously settle decomposed when a catalyzed fabric or activated aluminum was coated. Filing

Coating properties were determined by coating a chrome-plated steel substrate. That catalyzes " Fabric was made by treating a cotton fabric according to the following steps:

1. Rinsing the tissue for 5 minutes in a 20 weight percent ammonium hydroxide solution which was kept at room temperature from rinsing with cold water;

2. Rinsing for 5 minutes with a 20% acetic acid solution, kept at room temperature, rinsing with cold water;

3. Immerse the tissue in a sensitizing solution for 20 to 40 seconds Palladium colloid with a tin (IV) acid protective colloid kept at room temperature was rinsing with cold water;

4. Immersion for 1 to 3 minutes in a dilute hydrochloric acid solution kept at room temperature, Rinse with cold water;

5. Dry the fabric and cut it to the appropriate size.

The activated aluminum used was one obtained by immersion for 2 minutes a 37% hydrogen chloride release activated 2024 alloy.

In all examples, 930 cm ^{2 of} the catalyzed tissue or of the activated aluminum per 3.79 1 of solution were used to initiate the deposition and the spontaneous decomposition to determine the stability. To avoid contamination from contaminants, distilled water and reagent grade chemicals were used.

example 1

Nickel sulfate hexahydrate 35 g

Sodium hypophosphite monohydrate 15 g

Sodium acetate 15 g

Water ad 11

Temperature 91 to 96 ⁰ C

pH 5.0

This bath decomposed in about 20 minutes using activated aluminum. When adding 50 ppm, based on the solution, of copper (I) ions [in the form of copper (I) chloride] no decomposition occurred for 40 to 45 minutes.

Example 3

Nickel chloride hexahydrate .... 30 g

Sodium hypophosphite monohydrate 10g

Ammonium chloride 25 g

Ammonium hydroxide except for one

pH 8.5

Water ad 11

Temperature 82 ° C

The addition of the catalyzed tissue to the obi-

The solution caused its decomposition within about 1 to 2 minutes. When adding about 25 ppm of copper (I) ions in the form of copper chloride did not decompose within 4 minutes on. When the copper (l) ion content is increased

to 40 ppm based on the solution, no decomposition occurred for about 7 to 8 minutes. An increase the copper (I) ion content to 50 ppm, based on the solution, led to a decomposition within about 10 to 12 minutes. When finally the copper (I) ion content is increased to 200 ppm of the solution no decomposition occurred for 12 to 15 minutes However, the appearance of the deposited nickel was dull and had a powder structure (granular structure). From the above, zi

see that the copper (I) ion stabilizer is more effective in acidic nickel baths than in alkaline baths Baths that in the latter, however, a certain improvement is also achieved.

The activated aluminum caused the above bath to decompose within Minutes with severe build-up on the sidewalls within about 8 minutes. When 50 ppm of cuprous ions [in the form of cuprous chloride] were added to the bath, decomposed it does not change within 60 minutes.

Examples 4 to 10

Example 2

Nickel chloride hexahydrate .... 30 g

Sodium hypophosphite monohydrate 10 g

Ammonium chloride 100 g

Ammonium hydroxide except for one

pH of 9

Water ad 11

Temperature 91 to 96 ° C

Nickel sulfate hexahydrate 35 g

Sodium hypophosphite monohydrate 15 g

Sodium acetate 15 g

Sulfur stabilizer ¹ ) 5 ppm

^Wa ter _ad n

Temperature 91 to 96 ° C

pH about 5.0

') Admitted in the form of thiourea
60

The copper (I) ions were added in the form of Kup fer (I) chloride, and de A catalyzed tissue was used for stability in the manner described above. It was which is also determined by gloss and corrosion resistance, with the following results became:

y 21

22nd

Example copper (I) - gloss ^D ) Corrosion resistance ³ )

No. ') content

(ppm)

Stability (minutes)

strong gas formation within> 60 30 seconds, immediate formation of
black dirt

Gas formation in 3Va minutes, > 60

black stripes in 1 minute

Gas formation in 40 minutes,> 60

black stripes in 14 '/ ₂ minutes

no gas formation or formation of streaks> 60 within 8 hours

due to insufficient 2

Plating time failed the sample
not be rated

no gas formation or sticks-> 60 education within 72 hours

no gas formation or formation of streaks> 60 within 150 hours

') In Examples 8, 9 and 10 compositions were used in which the thiourea was omitted.

-) Arbitrary scale determined by visual inspection, the number 1 being a matt, non-reflective surface and the number 5 being a glossy, mirror-like surface; the numbers between 1 and 5 represent degrees of reflectivity.

') Determined by immersing the plated part in a 6N \ vasserstoffsäure at 38 ⁰ C.

5 5 1 6th 25th 3 7th 50 4th 8th 0 9 25th 5 10 50 5

The table above shows that thiourea is an effective stabilizer however, it does not improve the corrosion resistance or the gloss of the deposit and that it has an adverse effect on the deposit in the presence of copper (I) ions. In addition, copper (I) ions without thiourea improve gloss and corrosion resistance the deposit rank and the stability of the solution are considerable. As a result, those of sulfur are containing compounds of the type described above for free electroless alloy solutions preferred the purposes of the invention.

45 The deposits of Examples 12-15 had a glossy appearance and no gas formation or streaking was observed when the foils of the deposited alloys were immersed in 6N hydrochloric acid at 38 ° C. The deposit of Example 16 was dull in appearance and had a powdery (granular) structure.

Examples 17-22

Examples 11 to 16

To the composition of Example 1, cupric chloride was added in varying amounts and the resulting composition was used for plating chromium-plated steel . Subsequent to Example No. 5 , the deposits thus obtained were

peeled off the substrate , and each was on

analyzed their copper content. The amount of added to the solution and the amount of copper in the deposition gelundenem at each plated copper substrate are shown in the following table.

The procedure of Examples H through 16 was repeated, this time using the cupric chloride was replaced by copper (I) chloride. The results obtained are in the following table compiled.

Copper (II) content in the solution

(ppm)

Copper content in the deposit

(Weight percent)

Example no.

Copper fJD content in the solution

(ppm)

Copper content in the deposit

(Weight percent)

60

17 18 19 20 21 22

100

200

0.01 0.39 0.76 1.40 1.90 3.90

20th

40

80

100

200

0.01
0.36
0.68
1.28 1.50 3.44 The results of Examples 11 to 22 are in F i g. 2 of the drawing, in which curve A 65 represents the curve for the copper (I) addition and curve B represents the curve for the copper (II) addition. It can be seen from this that the two curves are almost parallel to one another.

" 1

Example 23

Nickel sulfate hexahydrate 35 g

Sodium hypophosphite monohydrate 15 g

Sodium acetate 15 g

Thiodiethylene glycol 25 ppm

Copper (I) chloride 100 ppm

Water ad 11

Temperature 91 to 96 ⁰ C

pH about 5.0

The corrosion resistance of the deposits with varying thicknesses was as follows:

Salt Spray Test (ASTM B-17-57T)

An electroless nickel-copper-phosphorus alloy was deposited from the above composition. She had a shiny appearance. No gas formation or streaking was found, when the foil of the alloy is in 6N hydrochloric acid at 38 ° C was immersed. This shows that certain types of sulfur compounds are present in the Solution can be tolerated without adversely affecting the deposit, the The stability of the plating solution is improved.

Example 24

Nickel sulfate hexahydrate 35g

Hydroxyacetic acid

(70% solution) 30 g

Sodium hypophosphite monohydrate 15 g

Sodium acetate 15g

Copper (I) chloride 75 ppm

Water ad 11

Temperature 93 ° C

pH about 5.0

A shiny, corrosion-resistant deposit was obtained from the above composition, containing about 3.0 weight percent co-deposited copper in a sample 0.254 mm thick. she had the following characteristics:

Specific weight .... about 8.20 g / cm ³

Melting point ( ⁰ C) about 1000

Vickers hardness (plated) 600

Maximum Vickers hardness through

Heat treatment 1100

Hydrogen content (ppm) 30 to 50

Magnetic properties ... not

magnetic *)

Specific resistance (micro

ohm-crn) 150

Thickness on the steel

Treatment time

0.0254 mm

0.0127 mm

0.0076 mm

0.0051 mm

at least 500 hours *) at least 240 hours *) at least 96 hours *) at least 48 hours *)

) After the treatment with the 5 Vo salt spray, no rust formation or discoloration could be found on the surfaces will.

♦) Magnetic moment =

1000

of pure Ni.

The provision of a new jewelry metal surface coating according to the invention provides a

also represents considerable technical progress. Currently the most widely used jewelry detail surface coating is chrome electroplating onto a substrate will. In a process for the deposition of chromium, for example for the production of smooth

th layers, corrosion-resistant layers and if a non-conductor, for example plastic. is to be plated and there are many steps required to form a conductive layer. Through Using electroless plating together

According to the invention, a jewelry metal surface coating can be used made solely by electroless deposition from the plating solution of the invention with the deposition proceeding to full thickness.

Because of their unusual properties, the electroless nickel-copper-phosphorus alloy deposits usable for many new technical purposes. Although they have a mirror-like appearance their appearance can be changed for example by a quick plating of chrome Achieving a blue-white surface appearance, which is characteristic of chrome-plated Surfaces. The alloy deposit has also been found to lend itself to soldering, brazing,

Connecting by means of ultrasound and for producing other metal-to-metal bonds according to known methods Procedure is suitable. Since the phosphorus hall is consistently above 8 and preferably above 10% can be maintained, the deposited alloy has non-magnetic properties, which makes it for a metal substrate for the subsequent deposition of magnetic coatings. The; is particularly true in view of the fact that the alloy has an unusually smooth surface which has a uniform distribution of the magnetic coating material on the non-magnet table alloy base. Another property he wanted is the hardness of the alloy which makes it suitable as a wear-resistant surface. Finally, the alloy is durcl characterized by a high degree of flexural ductility, de It is surprising in view of the high phosphorus content, which has always resulted in brittleness led. Therefore, the alloy deposit can also be used in such uses where movement of the alloy itself ode the combination of the alloy with the substrate on which it is plated. occurs. In this regard

The alloy can be used alone without a substrate, for example for making metal blowers. The ductility is maintained even if the alloy is exposed to high temperatures during use or up to about 100 minutes

is exposed to heat treatment at temperatures of up to 260 ° C for a long time. Dis ductility can be due to a low hydrogen content, which preferably does not exceed 100 ppm and usually varies between about 20 and 60 ppm.

For this purpose 3 sheets of drawings

Claims (6)

J difsriÄS ™ r,. ,. , - "·;,. Ηί.η" Ι "not for these purposes 1. Aqueous solution for electroless storage- 5 ^ ^e ^ _e £ ^ _d 't _9nBsm . To have a nickel-copper-phosphorus alloy with beirung ^ _w ^ f _d ~ r _te use of such solutions more than 25 percent by weight copper containing f * ™ ^ ™ _{Klckf. Meiz} not ights the sp.egelahn nickel ions, _{the outsid} hypophosphite as a reducing agent ^ ™ 7 _for decorative surface coverings for the nickel ions, a buffer for adjusting "^" ^ "^ rdem arise within the pH and copper ions, Ge characterized" ? ™ ^ϋη5 ° ^ _υπιε yellowish haze on the indicated that it is practically free from {"! JJ-fScelübeTzügen, which is a corrosion product of a sulfur compound, which in the solution" ^^^^ the action of air entSulfid- and / or hydrosulfide ions and provides jmellen, aas ^ ^^ _{known aqueous} copper (I) -and / or copper (II) ions containing J ^ _n JT it _is not possible, nickel coatings on 2. Solution according to claim 1, characterized marked ^L 15 ° solutions ^ls _{t match,} the records not only high that it contains 5 to 200 ppm copper (I) ions jm Su ratmzu ^ ^ _ai | _{{indicate> but also} contains one. ",, ^ Have corrosion resistance in order to 3. Solution according to claim I, characterized in that it effectively protects f "^^ _e ™ S £ _at , characterized in that it contains 15 to 100 ppm of copper (I) ions ^m g ™ ^e ff ⁶ ^ for the in the US Patent contains ^{.. Ao} O ₇ ^ ₇₂₃ described bath for the currentless Ab- 4. Solution according to any one of the preceding arrival f '° ^ ■ _nickel lüberzugs that, characterized in addition to nickel sayings that it comprises a ".gening ^ e ^ _and sulfide ions, which as a pH from 4.0 to 13.0 having. StSsator act, still contains copper ions. To 5. Solution according to claim 4 marked, Ubihsator wi Ke ^ p _ate ^ _{tschrift must be} in the characterized in that it has a pH value between 4.0 * ₅ ^ "" v £ _e rnickelungsbädern sulfide ions in a and 5.5 has. -tahilisierenden amount, ie, in an amount of 6. Solution according to one of the preceding an ™ '™ ^ _{8 ppb} free per billion) contain claims, characterized in that they except "^ ¹⁵ ^ ^ contained sulfur in the unloading a complexing agent for the nickel and / J""'^"a _{d" nickel} iüberzüge with fails, is or contains copper ions is obtained. ³ ° j ^ Use of this well-known nickel-plating bath has a brittle, matt-looking and slightly corrosive coating. The object of the invention is therefore to provide an aqueous solution for the electroless deposition of a nickel-containing coating, rad the help thereof it is possible to produce smooth, pore-free and surface-defective free coatings of nickel or Manufacture nickel alloys. 40 It has now been found that this object can be achieved by an aqueous Solution for the electroless deposition of a nickel-copper-phosphorus alloy with a maximum of 25 The invention relates to an aqueous solution for the weight percent copper used in addition to nickel · electroless deposition of a nickel-copper-phosphorus 45 ^^^^ τ ^. Setting the _P H