SU910845A1 - Copper pickling solution - Google Patents

Description

54 SOLUTION FOR CERTAIN ELIMINATION

The invention relates to the technology of metal processing by etching and can be used in the manufacture of printed wiring boards and other similar copper products used in radio, electrical, electronic devices and devices.

In the manufacture of copper products using a method of chemical etching, on the surface areas not subject to etching, protective layers, so-called resists, are applied. In a number of cases, in particular in the manufacture of printed circuit boards, various conductive materials and metals are used as resists. and alloys, such as tin, lead, silver, tin-cobalt alloys, PIC alloys, etc. This makes it possible to simplify the production technology of printed circuit boards, improve their characteristics, and facilitate subsequent soldering. In the process of copper etching from unprotected, gap areas of the boards, metal resists should not be destroyed, e, etched} and covered with oxide and salt films, which worsen their solvency. In the latter case, satisfactory

The metal resist after etching is achieved by carrying out additional chemical operations to remove oxide and salt films by clarification.

For etching printed circuit boards using copper as a circuit material protected by a metal resist,

10 solutions based on ammonium persulfate, sodium chlorite, chromic anhydride, compounds of divalent copper and others 1, 2 and 3,

However, these solutions have inherent wealth. All of them in one degree or another oxidize commonly used metallic resists, which, after etching printed circuit boards, require clarification. In addition, compounds of chromium (, U1) are toxic in chromate solutions. In solutions based on ammonium persulfate, a metallic resist is significantly etched, the oxidizer quickly decomposes and they lose etching properties. The main disadvantage of etching solutions based on sodium chlorite and compounds of divalent copper is the instability of their composition and

30 pickling characteristics. As a rule, they contain large concentrations of ammonium hydroxide, which leads to significant evaporation of free ammonia, especially in jet-type pickling plants, and necessitates continuous adjustment of the solutions. Thus, the consumption of chemicals increases, the quality of etching of the boards decreases, the working conditions of the personnel of the serving etching unit deteriorate,

The closest in technical essence to the proposed solution is a solution containing bivalent copper ions chloride, nitrate, ammonium carbonate and alkaline agent, which is used as C1MMONIUM hydroxide and momoethanolamine 4

The disadvantages of this solution are its low stability, low rates of copper etching, significant oxidation of metal resists.

The purpose of the invention is to prevent oxidation of the conductive material, increase the etching rate of copper and the stability of the solution.

To achieve this goal, in contrast to the known copper chloride containing chloride, chloride and (or nitrate and ammonium carbonate, alkali metal hydroxide is added to the solution for etching copper in an alkaline agent in the following ratio of components, g / l: copper chloride bivalent 120 260 Chloride and (or) ammonium nitrate 25-50 Ammonium carbonate 300-470 Alkali metal hydroxide 40-80 water Up to 1 l Solution for copper etching is prepared by mixing copper salt (P, ammonium carbonate and alkali metal hydroxide with water. First mix salt of divalent copper and ammonium carbonate is sewn with water, the mixture is kept at 30-60 ° C until carbon dioxide evolution ceases, and then alkali metal hydroxide is added.

The presence of carbonate ion in the solution determines the possibility of the formation of insoluble, precipitated basic salts of copper carbonate, which leads to a decrease in the concentration of the oxidizing agent — divalent copper ions and, accordingly, to a decrease in the rates of T1 ions.

PRI m e r 1. 120 g of CoCe22HrtO, 300 (NH4 / 2CO3 and 40 g of KOH are mixed with water. The resulting solution has a copper etching rate of 1017 µm / min and a capacity of etched copper of 10 g / l.

EXAMPLE 2 120 g of CaCCj 2H (iO and 300 g (NH4 / iCO3 are mixed with 300 ml of water, the mixture is held until carbon dioxide is removed (about 12 hours), then 40 g of KOH are added. The solution is diluted t water up to 1 l. The rate of etching of copper 21 μm / min, and the capacity of the solution of the etched copper increases to 60 g / l

Example 3. Analogous application. RU 2, but the mixture is held at a temperature of 45 ° C for about 3 hours. The etching characteristics of the solution are the same as in Example 2.

Example 4. Similar to Example 2, but the mixture is kept at a temperature of about 1.5 hours. The etching characteristics of the solution are the same as in Example 2;

An increase in the temperature of the extracts above causes the destruction of the formed ammonium complex of divalent copper and, as a consequence, a decrease in the rate of etching, the capacity of the solution, leads to precipitation. Reducing the temperature. Exposure below 30 ° C is impractical because the complete removal of carbon dioxide from the solution does not occur even with prolonged exposure.

As can be seen from the examples, such a method of preparation allows to obtain a solution with an increase in the rate of etching of copper by 1.5–2 times, provides an increase in productivity of the etching plants by 1.5–2 times without additional costs, as well as a lengthening of the solution life by 3-6 time.

The results of etching printed circuit boards on a copper base, partially coated with various metal resistors (from an o-tin-lead alloy, a tin-cobalt alloy, and silver, at 40 ° C are presented in the table.

From the BHArfO tables, that the etching rate is about 2 times higher than the known solution. The prevention of oxidation is confirmed by the soldering ability and resistance of the resist;

A decrease in the alkali hydroxide content below 40 g / l causes precipitation, and an increase in its content of more than 80 g / l causes a sharp decrease in the etching rate.

The stability of the solution is confirmed by the possibility of working with it without adjustment for a long time while maintaining the pickling characteristics (about 3 months. Known solutions containing ammonium hydroxide require almost continuous adjustment.

In soldering, a score of 5 corresponds to soldering without a T1 extension, with good quality, without additional clarification of the metallic resist. A score of 1 corresponds to a poor capacity.

The application of the proposed solution in the production of copper parts by chemical size etching with partial protection by metal resistors provides a high rate of copper etching, good resist after etching, and stability of etching characteristics.

These advantages create conditions to simplify the process, i.e. eliminating the operation of clarifying metallic resist, improving product quality and equipment performance, reducing the consumption of chemicals.

Claims (4)

 1. Patent of Great Britain No. 1316030, cl. In 6 J, 1973. 2. The UK patent number 1085747, cl. In 6 J, 1967. 3. US patent number 2872302, cl. 252-792, 1959.  4. Patent of Great Britain No. 1426529, cl. In 6 J, 1976.