HU205041B - Process for regenerating copper-containing etching agents of acidic or alkaline reaction - Google Patents

Abstract

Regeneration of copper contaminated acid or alkaline etching agents: a) pH of acid etching agents is set to 3.5-4.5 and ammonium ions pref. ammonium-hydroxide is added; b) pH of alkaline etchants is set to 3.5-4.5 with chloride ions, pref. hydrochloric-acid. PPtd. copper salts are isolated in both cases, pref. by filtration. The pH of the etching agents is set to sepd. values and the etchants are recirculated e

Description

The present invention relates to a process for the regeneration of copper-containing acidic or alkaline etching solutions.

Acidic or alkaline etching solutions are used in many fields of technology, but their most common application is the production of printed wiring boards. In use, the etching agent is copper-saturated and utilizing the copper-saturated etching agent is a major technical problem. Obviously, it is advisable to regenerate this etching agent, as copper-containing etching may otherwise result in economic losses and may cause environmental problems.

A process for the regeneration of acidic etching agents is described in Galvanotechnik, 2, 126-130. (1977). The essence of this solution is to extract the copper from the etching agent used with an organic chelating agent and then to acidify the resulting solution containing copper (II) ions, preferably with sulfuric acid, and then to electrolyze this acidic solution to obtain a metal scrap. This solution has several disadvantages. One disadvantage is that the organic chelating agent is a difficult to obtain expensive material. A further disadvantage is that the extraction must be carried out in an organic solvent medium, so that the use of an organic solvent is known to present many safety and health problems.

For the regeneration of alkaline used etching agents Karelin, Ja. A. and Yakubovsky Ε. P. describes a solution in Vodosznabzsenie i Sanitamaya Tehnika, 11.5-7. (1985). The essence of this solution is that the spent etching agent is passed through a cation exchange resin which binds the copper ions. The copper is then desorbed with dilute sulfuric acid and then subjected to electrolysis to separate the metal scrap. Among the many drawbacks of this solution is that after washing the copper ions, the ion-exchange resin must be regenerated before being used again to remove copper ions from the etching agent.

Thus, there is a need for a novel solution for the simple and rapid regeneration of copper content, acidic or alkaline etching agents.

The present invention is based on the discovery that the copper ions present in the etching agents used are predominantly in the form of copper (I) ions, which can no doubt be precipitated as the chloride salt in the presence of ammonium ions as known in the art.

Accordingly, the present invention relates to a process for the regeneration of copper-containing, acidic or alkaline etching agents. In the procedure, we proceed by:

(a) during the processing of acidic etching agents, adjust the etching agent to a pH of between 3.5 and 4.5 with ammonium ions, preferably ammonium hydroxide, or

b) In the treatment of alkaline etching agents, the pH is adjusted to between 3.5 and 4.5 with chloride ion reagent, preferably hydrochloric acid, and in both cases the precipitated copper is isolated, preferably by filtration, and the etching agent is recirculated after adjusting the pH.

The process reagents used in process a) include, for example, dry ammonia gas or an aqueous ammonium hydroxide solution, preferably an industrial grade 25-37% ammonium hydroxide solution.

In the process (b), hydrochloric acid is preferably used as the chloride ion-providing reagent, for example in the form of gaseous hydrochloric acid or aqueous hydrochloric acid such as technical grade 37% hydrochloric acid. Instead of hydrochloric acid, strong organic acids such as chloroacetic acid can also be used.

Subsequent isolation of the precipitated copper salt can be carried out in a manner known per se, for example by filtration. This operation is most conveniently performed by centrifugation. The solution remaining after removal of the copper salt, i.e. the actual etching agent, is subjected to an operation to adjust the pH to a suitable level, e.g. by repeatedly adjusting the acidic or alkaline pH. The main advantages of the process of the invention will be summarized in the following paragraphs.

1. The process according to the invention can be carried out very simply without the need for any special training.

2. The process of the invention does not require the use of organic reagents or solvents, so that the process of the invention is free of all the safety and health problems inherent in the known solutions.

3. To the best of our knowledge, no solution capable of regenerating both acidic and alkaline etching agents has been known to date, so that the process of the present invention is uniquely universal.

The following examples are intended to illustrate the process of the invention in more detail.

Example 1

WO ml used copper 130-140 g / l copper etching alkaline etching agent (widely used in the manufacture of printed wire boards marketed by Shipley Europe Limited, Coventry, United Kingdom under the trade name of Neutra-Etch VI) is enamelled with agitators. fitted with a cauldron. While stirring, 35-37% hydrochloric acid was added until the pH of the mixture was 4.5. The addition of hydrochloric acid is stopped and the stirrer is stopped. After the precipitate has settled, the liquid is decanted and pressed through a filter into a container.

The precipitate was removed by centrifugation from the residual solution, which was also pressed into the container.

The resulting clear, insoluble matter-free solution was adjusted to pH 8.9 with 25% ammonium hydroxide solution.

The following procedure provides 92 liters of 5 g / l copper reusable etching agent.

HU 205 041 Β

Example 2

The procedure described in Example 1 was carried out using an alkaline etching agent having a copper content of 120 to 130 g / l (ethanol sold by Intercircuit Munich under the tradename Endura-Etch), except that the pH of the regenerated product was 9.0. is adjusted using 25% aqueous ammonium hydroxide solution.

Example 3

For a 40-60 g / l copper etching hydrochloric acid etching agent (typically an in-house ethanol-free etching agent), the pH was adjusted to 4 with ammonia gas, and then treated with hydrochloric acid as described in Example 1. it is reset to the initial value of 1.

The acidic etching agent thus regenerated contains 2-5 g of copper per liter.

Claims (4)

A process for the regeneration of copper-containing, acidic or alkaline etching agents, characterized in that: (a) adjusting the pH of the etching agent to ammonium ions, preferably ammonium hydroxide, when processing acidic etching agents, or b) In the treatment of alkaline etching agents, the pH is adjusted to between 3.5 and 4.5 with chloride ion reagent, preferably hydrochloric acid, and in both cases the precipitated copper salt is isolated, preferably by filtration, and the etching agent is recirculated after adjusting the pH. 2. A process according to claim 1 wherein the hydrochloric acid is gaseous hydrogen chloride or aqueous hydrochloric acid. 3. A process according to claim 1, wherein the chloride ionizing agent is chloroacetic acid. 4. A process according to claim 1, wherein the reagent for ammonium ions is ammonia gas or an aqueous solution of ammonium hydroxide.