DE4339320A1 - Process for accelerated etching and deposition of metals in ammoniacal etching systems - Google Patents

Abstract

In a process of etching metal eg. copper using an ammonical etching agent and electrolytically regenerating the used agent with simultaneous recovery of dissolved metal prior to re-use, the nitrate content of the agent generated during the electrolysis is allowed to build up to an optimum of eg. 50 - 200 g/l. eg. by the addition of a reducing agent such as formaldehyde before electrolytic regeneration. This optimum nitrate content brings about a considerable acceleration of etching speed and adding reducing agents has the added advantage that for example in the electrolysis cell the conversion from copper II to copper I is favoured.

Description

Etching systems that work with ammoniacal etching agents are particularly good for regenerating the etchant in Re cycling process in which the etched metal in Electrolysis cells is deposited metallically.

For the economy of such recycling plants is of of great importance that the etching rate, but also the Ab cutting speed of the metal in the electrolysis cell be accelerated.

It is important that, if possible, the etching or rain nerieren and substances formed during the deposition of the metal do not lead to excessive enrichment. Annoying side reactions should be avoided if possible.

The object of the invention is to provide a method which achieved this ideal goal as close as possible.

The idea of the invention is particularly important in this regard by adding a disturbing side effect to previous ones Systems with an electrolytic cell - namely the formation of acid material and as a side reaction the oxidation of ammonium ions to Ni kicked - used positively.

So z. B. in published patent application DE 42 18 843 A1 a Ver drive described the removal of the nitrate from the Corrosive proposes by reaction with a reducing agent.  

The accelerating effect of the etching process was completely neglected by the nitrate, which at a distance from the etchant even with a residual content between 10 and 40 g / l is no longer given.

According to the invention, this is done on the electrodes of the electrolytic cell nitrate in the etchant to a value of at least 50 enriched up to 200 g / l. This can result in an essential acceleration The etching process can be achieved.

To avoid excessive nitrate concentrate it is recommended len, add reducing agent as soon as the values rise too high gene.

Formaldehyde is a particularly effective reducing agent recommended, which is proven in the electro-technical field Product is known.

An increased nitrate content in connection with reducing agents, he added according to the invention, but also improves the separation of Metals in the electrolytic cell, e.g. B. in copper the necessary reduction of copper II to copper I, the metallic Deposition of the copper is required is accelerated.

The etching proposed according to the invention with a high nitrate content also has the advantage that for certain acceleration additives, e.g. B. on the basis of compounds containing vanadium, well used is cash.

Also the addition of accelerators containing selenium or cobalt is proposed according to the invention.

Since the recommended procedures do not produce any substances that Affect etching process, the advantages are obvious.  

Examples of etching solutions according to the invention with traces of vanadium as accelerators are:

1. Solution:
60 - 120 g Cu / l
120 - 220 g SO₄ / l
70 - 100 g NO₃ / l
0.5 - 5 g Cl / l
1 - 20 mgV / l

2nd solution:
60 - 120 g Cu / l
120 - 220 g SO₄ / l
70 - 100 g NO₃ / l
0.5 - 5 g Cl / l
0.5 - 20 g PO₄ / l
1 - 20 mg V / l

Solutions 1 and 2 also contain ammonia for adjustment of the alkaline pH.

In a known manner, the etching rate is temperature and pH Value-dependent. As optimal z. B. for the invention examples the etching solutions temperatures from 35 ° C to 60 ° C determined at a pH of 8.1 to 8.8 and a nitrate content of 70-80g / l.

The reducing agents are added in order to increase the nitrate concentration Avoiding concentrations is not critical. A weekly Ana Lysis and addition are sufficient in most cases.

Of course, it is also possible to continuously add e.g. B. with dosing pumps, because the nitrate formation deposited copper quantity or the current balance of the electrolysis cell corresponds approximately proportionally and therefore easily precalculated can be net.

Especially when continuously adding reducing agents it is recommended to do this in the area of the electrolytic cell e.g. B. with the inflow, so that a better success z. B. in the conversion from copper II to copper I is achieved.

Claims (6)

1. A method for accelerated etching with ammoniacal etchants and subsequent regeneration of the etchant, the etched metal being deposited in an electrolytic cell, characterized in that the nitrate formed during the electrolysis in the etchant up to a concentration of at least 50 to 200 g / l is enriched, and that an excessive increase in the nitrate concentration above an optimal working point is prevented by the addition of reducing agents. 2. The method according to claim 1, characterized characterized in that as a reducing agent Formaldehyde is added. 3. Method according to one or more of the above Claims, characterized net that in addition a vanadium-containing accelerator is added to the etchant. 4. Method according to one or more of the above Claims, characterized net that an accelerator containing selenium was added becomes. 5. Method according to one or more of the above Claims, characterized net that an accelerator containing cobalt  is added. 6. Method according to one or more of the above Claims, characterized net that the reducing agent in the electrical field lysis cell is metered.