DE2114652A1 - Process for regenerating electrolytes for the chemical deposition of metals - Google Patents

Description

Patent department

Berlin, March 22, 1971

/ experienced in the regeneration of electrolytes for the chemical deposition of metals

The invention relates to a method for regenerating electrolytes for the chemical deposition of metals by supplementing the deposited metal.

Cheuische reducing baths are used today in many ways, so in particular for the metallization of appropriately pretreated Plastic surfaces.

The deposition of the metal which takes place here occurs naturally very quickly one. Depletion of metal ions, which greatly affects the rate of deposition of the metal will. For this reason, by adding concentrated metal salt solutions, the amount consumed by the deposition is used up Metal replenished regularly. These metal salt solutions usually also contain larger amounts of a complex-forming agent Substance.

U3R but iiachteil this usual method is α.-ite s here ■ an undesirable accumulation of acid αIonen by komplex-- the bath supplied metal salts and. ^; LcJoiiden substances comes.

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The invention therefore has the task of making it possible to supplement the metal consumed by the chemical deposition, without there being an accumulation of acid anions and complex-. forming substances.

This is achieved according to the invention by a method that thereby Is characterized in that the electrolyte solution is continuously moved through a cell in which the chemical Deposition of the amount of metal ions consumed by electro-chemical brought into solution metal ions is supplemented.

According to the invention, a regeneration cell is used here, which by means of a plate that is permeable to the electrolyte z. B. made of porous plastic, ceramic or other permeable materials, is separated into two compartments.

These two departments now each contain a cathodic or anodically polarized electrodes connected to a rectifier ..

The department with the cathodically polarized electrode is then with a suitable electrolyte, u. 'J. one-KailuMhydro: -:; .- cl- or sodium hydroxide solution, while the department is filled with the anodically polarized. Electrode that separates the ine tall Electrolyte contains »In this anode compartment, the replenishment takes place of metal ions by being depleted of metal ions Electrolyte in circulation continuously through this Ilauni, z, ß,

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by pumping, moved and then, after completion, the working container is fed back in, in which: the separation. takes place.

This supply of the supplemented or regenerated solution into the working container can be carried out in two ways, for example by means of an overflow.

The cathodically polarized electrode should advantageously be off Stainless steel exist, while the anode material naturally to be used is that of metal, which is supplemented by four be 1.

The strength of the formation of ketallion ions in the anode space can be done in the simplest way by regulating the current strength of the rectifier. A control of the rectifier, e.g. :. by means of an instrument that measures the metal ion concentration in the working container, then enables the deposited metal to be continuously replenished and thus keeping the metal ion concentration constant in the working container. This enables uninterrupted ketallization, which z. B. is particularly worldly when operating automatic systems.

The method according to the present invention is shown below on the basis of the working conditions for the operation of chemical metal baths. . BADORiGINAL

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example 1

A regeneration cell is used in which one can keep the distance as small as possible between the electrodes.

Such a cell is shown in FIG. Mean therein 1 a stainless steel electrode, 2 a porous ceramic plate, and 3 an electrode made of copper. A provides the feed for the solution to be regenerated and B the drain of the regenerated solution.

The structure of this regeneration cell can also be seen from FIGS. 2 and 3, in which the reference symbols 1, 2, j ?, A and B have the same meaning as in FIG. 5 means the container wall made of plastic and 6 represents Plates, also made of plastic, are very low Allow the electrodes to be spaced. The electrolyte solution is represented by E and the alkali hydroxide solution by F.

The anode plates naturally consist of the metal that is to be supplemented.

The anode spaces are now connected in series, e.g. with the help of hoses, whereupon the electrolyte solution to be regenerated is pumped through. For this purpose, the solution is extracted from the working container in which the chemical metal deposition takes place. sucked into the anode space of the regeneration cell

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leads and returned to the working container after the addition of metal ions. The cathode compartment is with a Filled in sodium hydroxide solution.

For regenerating a copper electrolyte of the composition

Copper sulfate (CuSO ^, 5 HgO) 5 g / liter

Complexing agent (disodium salt of ethylenediaminetetraacetic acid) 20 g / liter

Alkali hydroxide (NaOH) 3 g / liter

Stabilizer (rhodanine) .... »0.03 g / liter

Reducing agent (formaldehyde) 5 g / liter

from pH 12.5 was z. B. when applying a DC voltage of 40 volts with anodes connected in parallel, a current of 10 amperes can be achieved. This increased the copper concentration the regeneration cell by 3.5 g / liter, which is at a flow rate of 5 liters / h corresponds to a metal supplement of 11 g / hour. There is thus a continuous flow in the working tank chemical metal deposition of about 10.5 g copper / h possible, which is an area of 1.18 m / h with a layer thickness of 1 μτη corresponds.

Example 2

The regeneration cell described in Example 1 was used for regeneration an electrolyte of the following composition is used;

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Nickel chloride (NiCl _2. 6 H ₂ O) 26 g / liter

Sodium hypophosphite ". 50 g / liter

Lactic acid 27 g / liter

Propionic acid 2 g / liter

Lead chloride 0.0027 g / liter

For this purpose, this solution was sucked out of the working container, pumped into the anode chamber and, after flowing through the regeneration cell, returned to the working tank. Of the On the other hand, the cathode compartment contained an approximately 1 η sodium hydroxide solution. When a direct voltage of 40 volts was applied, a current of 8.2 amperes was achieved. An increase in concentration was obtained at a flow rate of 3 liters / h of 2.7 g nickel / liter, which corresponds to a metal addition of 8.1 g / h in the working container.

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Claims (5)

Patent claims 1.) Process for regenerating electrolytes for the kitchen Deposition of metals by supplementing the deposited metal, characterized in that the Electrolyte solution is continuously moved through a cell, in which it is consumed by chemical deposition Amount of metal ions is supplemented by metal ions brought into solution electrochemically. 2. The method according to claim 1, characterized in that a cell is used which by means of a for the
Electrolyte permeable plate, separated into 2 compartments. 3. The method according to claim 2, characterized in that a cell is used whose two departments each have a cathodic connected to a rectifier or an anodically polarized electrode. 4. The method according to claim 5, characterized in that the metal ions are replenished in the compartment containing the cathodically polarized electrode. 5. Process for regenerating chemical copper baths according to claims 1 to 4. 2098 / .1 / 0942 BAD ORIG.NAL Blank page