JPH0245713B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for maintaining and managing the capacity of an etching solution (hereinafter simply referred to as "etching solution") using an aqueous copper chloride solution and an apparatus therefor.

In the production of printed wiring boards, etc., so-called etching is performed to melt and remove copper foil from unnecessary areas other than wiring areas, and the etching equipment used for this process has come to be used repeatedly while circulating the etching solution. Copper from the material to be processed (printed wiring board) is dissolved into the etching solution and increases in proportion to the amount of etching.

As this copper increases in the etching solution, cuprous chloride is produced in the etching solution according to the following chemical reaction formula.

CuCl ₂ +Cu→Cu ₂ Cl ₂ (2CuCl) The cuprous chloride thus produced is insoluble in water and therefore adheres to the etched surface to form a film, reducing the etching rate.

Therefore, by adding hydrochloric acid as an auxiliary agent to cupric chloride, which is the main ingredient of the etching solution, the coating caused by cuprous chloride is removed.
This is expressed by the following chemical reaction formula.

CuCl ₂ +2HCl→2HCuCl ₂ (2HCl・CuCl) 2HCuCl ₂ (2HCl・CuCl) is soluble in water,
Although the intended purpose of removing the cuprous chloride film was achieved, it did not have etching ability as it was, so by adding an oxidizing agent to the etching solution, 2HCuCl ₂
(2HCl・CuCl) is oxidized and returned to cupric chloride,
A procedure to restore the etching capacity to the desired level, ie, regeneration of the etching solution, is being carried out.

The regeneration formula is as follows.

2HCuCl ₂ +1/2O ₂ →2CuCl ₂ +H ₂ O From the above facts, it is possible to avoid the decrease in the performance of the etching solution (fatigue of the etching solution) caused by cuprous chloride that occurs when the etching solution is used repeatedly, and to improve the etching performance. An essential element to maintain this level is the timely and adequate replenishment of hydrochloric acid to remove the cuprous chloride coating and hydrogen peroxide as the oxidizing agent for 2HCuCl ₂ during use of the etching solution. is understood.

In other words, maintaining the required amounts of hydrochloric acid and hydrogen peroxide in the etching solution while using the etching solution will maintain the performance of the etching solution at the desired level. .

By the way, regarding the two main elements so far,
Various methods have been proposed for replenishing the etching solution while it is in use (etching solution regeneration means).

However, out of these two elements of the etching solution, it is volatile, and there is loss due to consumption and evaporation due to etching processing operations, and quantitative fluctuations are high, making it difficult to manage. To date, there has been no proposal to directly and continuously detect the amount of hydrochloric acid present during use of the etching solution, and to replenish it based on the detected value. be.

This seriously undermines the strictness of maintaining the performance of the etching solution, and proves that there is no hope of achieving this high goal.

The present invention has been proposed in view of the above facts, and involves directly and continuously detecting the content of hydrochloric acid in the etching solution while the etching solution is being used, and based on this detected value, etching is performed. In order to maintain the concentration of hydrochloric acid in the solution within a desired range, the amount of replenishment is controlled and replenished, and hydrogen peroxide is replenished in a proportion that can be obtained relatively from the replenishment amount of hydrochloric acid based on chemical reaction theory. The purpose of the present invention is to maintain the performance of an etching solution at a desired level during use of the etching solution.

The figure is a schematic explanatory diagram of the device of the present invention, and 1 is a
The etching liquid tank 1 contains an etching liquid 100, and the etching liquid 100 contained in the liquid tank 1 is circulated through a pump 2 and a pipe 3a. That is, the etching liquid 1 introduced into the pipe 3a by the pump 2
00 is sprayed from a nozzle 4 toward a material to be processed (not shown), and the liquid that has slipped from the material to be processed is mixed into the etching solution stored below again.

As described above, a part of the etching liquid 100 led to the pipe 3a is further transferred to the pipe 3b.
The etching solution 100 is led to the hydrochloric acid concentration detection tank 50 in which the hydrochloric acid concentration detection tool 5 is immersed, and the etching solution 100 whose hydrochloric acid concentration has been detected there returns to the etching solution 100 again via the pipe 3c. ing.

The molar controller 6 is attached to the hydrochloric acid concentration detector 5.
are electrically connected to each other, and therefore, information regarding the hydrochloric acid concentration of the etching solution 100 in use, which is continuously obtained by the hydrochloric acid concentration detector 5, is continuously transmitted to the molar controller 6.

A metering pump 7 is electrically connected to this molar controller 6, and the metering pump 7 is activated based on the operation command of the molar controller 6. When the pump 7 is activated, the hydrochloric acid 80 contained in the hydrochloric acid storage tank 8 is transferred to the etching liquid 100 through the pipe 9.
A certain amount will be replenished.

Furthermore, a pump 11 is connected to the metering pump 7 via a controller 10, and the amount of operation of this pump 11 is controlled by the controller 10 with respect to the amount of operation of the pump 7 as described above. Since it is controlled so that the amount of operation corresponds to the amount ratio of hydrogen peroxide to the replenishment amount of hydrochloric acid 80 obtained by chemical reaction theory, hydrogen peroxide storage is performed in conjunction with the replenishment of hydrochloric acid 80. Hydrogen peroxide 120 contained in tank 12 is replenished via pipe 13 in an amount corresponding to the ratio of hydrogen peroxide 120 to hydrochloric acid 80 obtained by chemical reaction theory.

As described above, the concentration of hydrochloric acid in the etching solution in use is constantly detected by the hydrochloric acid concentration detector 5, and the results are immediately sent to the molar controller 6, and according to the commands of the molar controller 6, At the same time, the required amount of hydrochloric acid 80 is replenished into the etching solution 100, and at the same time, hydrogen peroxide 120 is added to the etching solution 100 in the required amount ratio to the replenishment amount of hydrochloric acid 80.
According to the present invention, rapid and accurate replenishment of hydrochloric acid based on physical values,
It simultaneously replenishes hydrogen peroxide quickly and accurately, which is a theoretical necessity, and eliminates all the ambiguity of the basis for replenishment as in conventional methods, resulting in outstanding effects. This is an epoch-making invention.

[Brief explanation of drawings]

The figure is a schematic explanatory diagram of the device of the present invention. Description of symbols, 1... Etching tank, 5... Hydrochloric acid concentration detector, 6... Molar control, 8... Hydrochloric acid storage tank, 12... Hydrogen peroxide storage tank, 50...
Tank for detecting hydrochloric acid concentration.

Claims (1)

[Claims] 1. A hydrochloric acid concentration detector is placed in the etching solution in use, and based on the hydrochloric acid concentration value continuously obtained from the detector, the acid concentration in the etching solution is determined from 0.1 mol to 0.1 mol. By controlling the amount of replenishment and replenishing hydrochloric acid to maintain the etching concentration between 5 molar and hydrogen peroxide in a ratio of hydrogen peroxide to hydrochloric acid based on chemical reaction theory, A method for maintaining and managing the capacity of an etching solution, which is characterized by maintaining the capacity at a required level. 2. A hydrochloric acid concentration detector placed in the etching solution;
It is equipped with a molar controller, a hydrochloric acid storage tank and a hydrogen peroxide storage tank connected to the etching liquid tank via a supply means, and these are connected to the molar controller based on the hydrochloric acid concentration information from the hydrochloric acid concentration detector. The hydrochloric acid supply means is controlled to replenish the required amount of hydrochloric acid from the hydrochloric acid storage tank to the etching liquid tank, and at the same time, hydrogen peroxide is added to the hydrogen peroxide storage tank in an amount ratio of hydrogen peroxide to hydrochloric acid based on chemical reaction theory. An etching solution capacity maintenance and management device characterized in that the etching solution capacity maintenance and management device is connected and arranged so that the etching solution can be refilled from the etching solution tank.