JPH0533315B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an etching solution management method using a cupric chloride solution for forming circuits on a copper-clad wiring board.

Structure of conventional example and its problems Conventionally, etching solutions such as ferric chloride solution, ammonium solution, cupric chloride solution, etc. have been used in circuit formation on copper-clad wiring boards. Among these, cupric chloride etching, which allows stable and uniform etching, is increasingly being used. However, cupric chloride etching dissolves copper, so that divalent copper ions become monovalent and suppress etching. Conventionally, isokinetic etching has been achieved by adding drugs to convert monovalent copper ions into divalent copper ions. However, the sensor for controlling drug addition is required to be complex and have a small time constant. That is, it is a sensor that controls three types: hydrochloric acid concentration, cuprous chloride, and cupric chloride. However, it has been difficult to control cuprous chloride and cupric chloride stably and with a small control time constant.

Furthermore, regeneration of the cupric chloride etching solution using a chemical solution resulted in an increase in the amount of waste solution, making it difficult to dispose of the waste solution.

OBJECTS OF THE INVENTION In view of the above-mentioned drawbacks, the present invention provides a method for managing a cupric chloride etching solution in which the etching solution is electrically regenerated and the etching solution can be adjusted by adjusting the electrode potential.

Structure of the Invention In order to achieve the above object, the etching solution management method of the present invention has a regeneration tank divided into an anode side and a cathode side by an anion permeable membrane, and controls a hydrochloric acid solution on the cathode side to a predetermined concentration. , the etching solution on the anode side is circulated and supplied while adjusting the concentration and specific gravity of hydrochloric acid, and a current is passed between the electrodes to oxidize the monovalent copper ions in the etching solution to divalent ones at the anode section, causing anion permeation. The chlorine ions are transferred from the hydrochloric acid solution on the cathode side separated by a membrane to the anode side, regenerating the etching solution,
The method is characterized in that the potential difference between the anode and the etching solution is measured and the etching in the etching bath is controlled based on the change in electrical resistance, and by this method, the cupric chloride etching solution can be managed economically. be able to.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows an etching solution management method in one embodiment of the present invention. In FIG. 1, 1 is the etching device main body;
2 is an etching waste liquid tank, 3 is an etching liquid,
4 is a hydrochloric acid tank, 5 is a hydrochloric acid tank, 6 is a regeneration tank (electrolytic tank), 7 is an anode, 8 is a cathode, and 9 is a diaphragm (anion permeable membrane). FIG. 2 shows details of the etching waste liquid tank 2 shown in FIG. In Fig. 2, 10 is a primary waste liquid storage tank, 11 is a concentration adjustment tank, and 1
2 is a water tank for specific gravity adjustment, and 13 is a hydrochloric acid tank for concentration adjustment.

The etching solution management method configured as above will be explained below.

First, the etching solution 3 used for etching
is transferred to the primary waste liquid storage tank 10, a part of which is used as waste liquid, and the remainder is sent to the concentration adjustment tank 11, where the specific gravity and hydrochloric acid concentration are adjusted, and sent to the regeneration tank 6. The etching solution sent into the regeneration tank 6 converts monovalent copper ions into divalent ones by flowing a constant current. Accordingly, chlorine ions move from the catholyte side to the anolyte side via the anion exchange membrane 9, thereby regenerating the etching solution.

At that time, there is a potential difference between the anode and the anolyte, but the potential difference between the anode and the anolyte becomes constant when monovalent copper ions disappear. However, once the monovalent copper ions are depleted, chlorine gas will be generated if the current continues to flow. Therefore, the flow rate of the etching solution to be regenerated and the regeneration current capacity are adjusted to obtain a composition that meets the etching conditions. For example, a production process in which a 35 μm thick copper foil of a single-sided copper-clad laminate is etched using a cupric chloride solution containing 1 m ³ of hydrochloric acid in an etching tank to form a conductor pattern at a conveyor speed of 2 m/min. If the line is regenerated at a liquid circulation rate of 20/min and a current of 2A, a stable etching solution can be supplied, but if the liquid circulation rate is 10/min, the regeneration will no longer be able to keep up with the etching process. In addition, the hydrochloric acid concentration of the catholyte is 1 to 35
Control by weight percentage.

As described above, according to the etching solution management method of this embodiment, monovalent and divalent copper ions can be controlled by the potential difference between the anode and the anolyte, and can be used as a sensor in conjunction with the hydrochloric acid concentration and specific gravity. In other words, by flowing a constant current, the amount of monovalent copper ions and 2
Since the potential difference in the ratio of the amount of valent copper ions depends, the total amount of copper is adjusted by controlling the specific gravity while keeping the hydrochloric acid concentration constant, and the amount of monovalent and divalent copper ions is kept constant by controlling the potential difference. Since the amount of monovalent copper ions is a factor that inhibits etching, and the concentration of hydrochloric acid and the amount of divalent copper ions are factors that promote etching, the etching power can be kept constant. Compared to conventional sensors such as ORP meters and photometers that convert chemical and physical signals into electrical signals, this sensor is more stable and has a smaller control time constant. Additionally, compared to regeneration methods using chemical solutions, the work environment is improved because no chlorine gas is generated, and the amount of chemical solution used is reduced, making it possible to reduce the amount of waste fluid.

Effects of the Invention As described above, the present invention enables electrodiaphragm dialysis to
By regenerating the cupric chloride etching solution,
Suppresses the generation of chlorine gas. At this time, by adjusting the hydrochloric acid concentration and specific gravity before the regeneration tank, the anode-anolyte potential can be expressed only by the ratio of monovalent copper ions to divalent copper ions. That is, the potential between the anode and the anolyte directly indicates the regeneration status of the etching solution. This leads to a reduction in the amount of chemical liquid used and the amount of waste liquid, and by being able to perform stable control, quality can be stabilized and improved, which has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an etching solution management method according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a waste solution tank in the same etching solution management method. 1... Etching device body, 2... Etching waste liquid tank, 3... Etching liquid, 4... Hydrochloric acid tank, 5... Hydrochloric acid, 6... Regeneration tank (electrolytic tank), 7
. . . Anode, 8 . . . Cathode, 9 . . . Diaphragm (ion conversion membrane), 10 . . . Primary waste liquid storage tank, 11 .

Claims (1)

[Claims] 1 It has a regeneration tank divided into an anode side and a cathode side by an anion permeable membrane, and controls the hydrochloric acid solution on the cathode side to a predetermined concentration, and adjusts the hydrochloric acid concentration and specific gravity while circulating the etching solution on the cathode side. Current is passed between the electrodes, oxidizing the monovalent copper ions in the etching solution to divalent ones at the anode, and moving chlorine ions from the hydrochloric acid solution on the cathode side, which is separated by an anion-permeable membrane, to the anode side. A method for managing a cupric chloride etching solution, which comprises regenerating the etching solution, measuring the potential difference between the anode and the etching solution, and controlling etching in an etching bath based on the change in electrical resistance.