JPH06299371A - Method for controlling etching solution and automatic controlling device - Google Patents

Abstract

PURPOSE:To provide a method and device for automatically controlling an etching soln. by which the service life of a copper etching soln. is prolonged and a change of etching time with the lapse of time is suppressed in the pH control of the copper etching soln. using a copper-ammine complex. CONSTITUTION:This device is composed essentially of a part 2 for automatically measuring the pH of a copper etching soln., a controlling part 15 for calculating the difference between the measured pH and the desired pH and sending a gaseous ammonia feeding signal and a part for feeding gaseous ammonia into the etching soln.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to pH control of etching solutions, and more specifically, to TAB, printed circuit boards and F
The present invention relates to a pH control method and a control apparatus for a copper ammine complex-based etching solution used for the purpose of etching copper in the manufacturing process of PC and the like.

[0002]

2. Description of the Related Art In the process of manufacturing TAB, printed circuit boards, FPCs, etc., a method of removing a part of a conductor portion by etching is often used to form an electric circuit.

When the conductor portion is copper, an etching solution containing a copper ammine complex is often used. This utilizes a reaction in which a divalent copper ammine complex is alkaline with ammonia, causes a disproportionation reaction with metallic copper, and ionizes and dissolves metallic copper. This etching solution has a problem that the time required for etching (hereinafter referred to as “etching time”) changes greatly with time because ammonia volatilizes easily into the air, which lowers the production efficiency. When used for about 2 weeks, there was a problem that etching became difficult and unusable.

As a means for solving this problem, there is a method of adding ammonia water to the etching solution when the ammonia in the etching solution is reduced. However, if ammonia water is repeatedly added, the concentration of components other than ammonia contained in the etching solution decreases, and as a result, the etching time becomes longer. In addition, the amount of ammonia in the etching solution decreases quickly due to the volatilization of ammonia. Therefore, if the decrease condition is frequently investigated and ammonia is not added frequently, in order to keep the etching time constant, It is difficult to keep the amount of ammonia constant. Moreover, doing this manually is labor intensive. Furthermore, the unit price of ammonia water is about 15 times as expensive as the unit price of the same molar amount of ammonia gas.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to provide a method and apparatus for automatically managing a copper etching solution for prolonging the life of the copper etching solution and eliminating the change with time of the etching time. is there.

[0006]

The control method of the present invention for solving the above-mentioned problems includes a step of automatically measuring the pH of a copper etching solution using a copper ammine complex, and the measured pH value and management. A step of calculating a difference from a desired pH value and outputting an ammonia gas supply signal according to the pH difference, and automatically calculating a necessary amount of ammonia gas according to the ammonia gas supply signal, The method is characterized by comprising a step of supplying a gas, and automatically blowing ammonia gas into the etching solution so that the pH of the etching solution becomes constant.

Further, the automatic management apparatus of the present invention collects a sample of an etching solution of copper using a copper ammine complex and automatically measures the pH of the etching solution sample (hereinafter referred to as "pH measuring section"). And a control part (hereinafter referred to as "control part") that calculates the difference between the measured pH value and the pH value to be managed and outputs an ammonia gas supply signal according to the pH difference, and a control part required by the ammonia gas supply signal. A pH control device for an etching solution, comprising a part for automatically calculating the amount of ammonia gas and supplying the ammonia gas to the etching solution (hereinafter referred to as "gas supply part"), wherein the pH of the etching solution is constant. Ammonia gas is automatically blown into the etching solution so that

In addition, the pH measuring section for automatically measuring the pH control of the etching liquid sample has a pH electrode that is washed and protected after the measurement is completed after each measurement, and the pH electrode is not measured before the measurement is started. It has a part to be calibrated.

Therefore, the pH measuring section is composed of a pH measuring tank, a sampling pump, a pure water supply pipe for cleaning the pH electrode, a pH calibration liquid supply device and a waste liquid treatment device.

The control unit calculates the difference between the measured pH value and the pH value to be managed, compares it with the set pH value, and calculates the portion for outputting the ammonia gas signal and the time for outputting the ammonia gas supply signal. It is composed of a part that indicates the time.

The gas supply unit is composed of a cylinder containing ammonia gas, a gas pressure regulator, a flow meter, a valve, a gas pipe, and a check valve for preventing backflow of the etching solution.

[0012]

[Function] The pH is automatically measured at the set time.
Measure H.

At the set time, the automatic control device is energized, and the pH electrode is first calibrated by the pH calibration liquid. When the calibration is completed, a pH measurement sample is collected and pH is measured with a pH electrode. After the pH measurement is completed, the pH electrode is washed with pure water and drained to complete one pH measurement step.

On the other hand, the control unit receives the signal of the pH measurement value, and the difference between the measured pH and the pH at which the etching liquid is to be controlled to that value (hereinafter referred to as "target pH") (hereinafter referred to as "pH difference"). ) Is larger than the set value, the ammonia gas supply signal is output. While this signal is being output, the valve for supplying ammonia gas is open. Ammonia gas flow rate (l (liter) / min) and the amount of ammonia gas required to raise the pH by 1 (hereinafter referred to as "ammonia gas / pH")
When is input, the time during which the ammonia gas supply signal is output (hereinafter referred to as "ammonia gas supply time")
Is automatically calculated from the following formula.

[Ammonia gas supply time] = [pH difference] × [ammonia gas / pH] ÷ [ammonia gas flow rate]

Ammonia gas / pH is calculated by the following formula from the difference in pH before and after the ammonia gas is blown into the etching solution for a certain time (minute) at a certain flow rate (l (liter) / minute) of the ammonia gas. .

[Ammonia gas / pH] = [Ammonia gas flow rate] × [Ammonia gas blowing time] ÷ [pH difference before and after blowing]

The ammonia gas is supplied to the etching solution by supplying an electric signal, which is an ammonia gas supply signal output from the control section, to the solenoid valve, which opens the solenoid valve and, as a result, the pneumatic valve. It is performed from a cylinder containing ammonia gas.

As described below, the necessity of the ammonia gas supply is judged from the pH measurement and the obtained Ph, and if necessary, the output of the ammonia gas supply signal, the ammonia gas supply signal is used to etch the ammonia gas. A series of supply processes are automatically controlled.

[0020]

EXAMPLES Examples according to the present invention will be described in detail.

FIG. 1 is a schematic system diagram of an automatic etching liquid management apparatus according to an embodiment of the present invention. The automatic management device automatically measures the pH of the etching solution, and determines from the obtained pH whether ammonia gas needs to be supplied, and if necessary, outputs an ammonia gas supply signal and ammonia gas. When the supply signal is output, it is composed of a portion for blowing ammonia gas into the etching solution.

The pH measuring unit is composed of a pH measuring tank 2, a sampling pump 1 for automatically pumping the etching solution into the pH measuring tank 2, and a pH electrode 3 attached to the center of the pH measuring tank 2.

Further, two types of p for calibrating the pH electrode 3 are used.
Each container containing H calibration solution 12 and pH calibration solution 14, pH calibration solution supply pump 13, pH calibration solutions 12 and 14
There is provided a pH measuring electrode calibration device including a three-way valve 11 for switching between. The pH of the pH calibration solutions 12 and 14 are 7.41 and 10.01, respectively.

Further, a pipe 7 and a solenoid valve 8 are provided to supply pure water for cleaning the pH measuring electrode 3, while
A pipe 5 and pipes 9 and 10 are connected to each other via a three-way cock 4 for discharging the drainage of the measuring tank 2.

In the pH measuring section, the three-way cock 4 is set to the A position, the pump 1 is used to automatically pump up the etching solution into the pH measuring tank 2 at a set time, and the pH electrode 3 is used. Measure pH. After the measurement is completed, the three-way cock 4 is changed from the position A to the position B, and the pipe 5 is passed through
The etching solution is returned to the base copper dissolving bath 6. Then, in order to wash and protect the pH electrode 3, after changing the three-way cock 4 to the position A, the solenoid valve 8 in the middle of the pure water pipe 7 is opened,
The pH measuring tank 2 is filled with pure water. Before the etching solution is pumped into the pH measuring tank 2 for the next measurement, this pure water is
The three-way cock 4 is changed to the position of C, and the three-way cock 4 is passed through the pipe 9 and discarded into the drainage pipe 10.

When the automatic control device is energized before the base copper dissolving bath 6 is operated, the three-way cock 11 is turned on.
Position, and use the pump 13 to adjust the pH calibration solution 12 to p
The pH electrode 3 is calibrated by pumping it into the H measuring tank 2.
Furthermore, the three-way cock 11 is changed to the E position, and the pH calibration solution 1
4 is pumped into the pH measuring tank 2 using the pump 13,
The electrode 3 is calibrated.

The control unit 15 receives the pH measurement value of the pH measurement electrode 3, and if the difference between the measured pH value and the pH value at which the etching liquid is to be controlled to that value is larger than the set value, the ammonia gas is discharged. Output supply signal. The ammonia gas supply signal is transmitted to the solenoid valve 23.

The gas supply unit comprises a cylinder 16 containing ammonia gas, a gas pressure regulator 17, a flow meter 18, an air pressure opening / closing valve 19, a check valve 20 and a gas pipe 21 connecting them. The check valve 20 is attached to the tip of the gas pipe 21 and is inserted into the etching solution.

The ammonia gas supply signal output from the control unit 15 is an electric signal. This electrical signal
Compressed air piping 2 supplied to pneumatic on-off valve 19
When it is sent to the solenoid valve 23 in the middle of 2, the solenoid valve 23 opens, and as a result, the pneumatic opening / closing valve 19 opens. Ammonia has a very high solubility in water, and when the supply of ammonia is stopped, the etching solution flows back through the gas pipe 21. A check valve 20 is attached to prevent this.

The automatic control apparatus of the above-described embodiment of the present invention was applied to the base melting step in the production of the two-tank TAB.

In the copper undercoating step, the copper side of the copper polymide substrate is thickly plated on the portion where the lead is to be formed, and then only the copper (underlying copper) in the unplated portion is dissolved by etching. , A step of obtaining an electric circuit wired by leads. The base copper dissolving bath 6 contains 35 g of copper /
1 (liter), 100 g / l (chlorine) of chlorine, and 15 l (liter) of a copper etching solution containing ammonia in an amount to achieve a desired pH. The bath operates for about 6 hours a day, etching 1-10 g of copper per day.

The automatic management device is operated, and at this time, the average pH of the day (hereinafter referred to as "average pH"), the difference between the maximum pH and the minimum pH of the day (hereinafter referred to as "pH fluctuation"), and etching. The change of time was investigated. The etching time is measured by Japanese Patent Application No. 4-328935 “Etching liquid property evaluation apparatus and its property evaluation method”.

That is, when the test piece is dipped in the copper base solution, the change in the electrical resistance at both ends of the test piece is measured, and the copper base is thawed and the resistance rises to 5Ω from the start of the immersion. The etching time was set as the etching time. The test piece is shown in FIG. This is a 2 tank TAB
The sample before the step of melting the underlying copper in the production of the above is cut into a U-shape, and the polymide film 24 having a thickness of 50 μm, the underlying copper 25 having a thickness of 0.6 μm, and 25
It consists of leads 26 with copper thickened to a thickness of μm.

FIG. 3 shows the daily changes in the average pH investigated.
Indicate. The average pH of the first few days is high, but this is
This is because the base copper solution having a pH higher than H was prepared. Excluding these, the average pH is almost constant, and the pH of the underlying copper solution is very well controlled. In addition,
In Fig. 3, the data □ on consecutive days are connected by a solid line.

FIG. 4 shows the daily changes in the investigated pH fluctuations.
Indicate. After not driving for several days (more than 5 days), p
The H variation may be large, ie, greater than 0.5. This is because the ammonia is not replenished and the volatilization proceeds while it is stopped, so that the pH at the beginning of the day when the operation is restarted is very low. If it is operated continuously or for only one day, the pH fluctuation will be 0.5 on the next day.
It is getting smaller. In addition, in FIG. 4, the data □ on consecutive days are connected by a solid line.

The daily change in the investigated etching time is shown by □ in FIG. It can be seen that the etching time is almost constant and the underlying copper solution is stably controlled. It should be noted that, during the operation of the automatic management device, in the two-tank TAB production, there was no defective copper melting. In addition, the continuous data □ in FIG. 5 is connected by a solid line.

[0037]

Since the present invention is constructed as described above, it has the following effects.

(1) With the control method and control apparatus of the present invention, it is possible to prolong the life of a copper etching solution using a copper ammine complex and to prevent the etching time from changing with time.

(2) Since the management is automatically performed, not only the labor by manpower is reduced, but also the unnecessary supply of ammonia gas is eliminated and the consumption of ammonia gas becomes appropriate.

[Brief description of drawings]

FIG. 1 is a schematic system diagram of an automatic etching liquid management apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a test piece used for measuring an etching time in an example according to the present invention.

FIG. 3 is a graph showing daily changes in average pH when a base copper dissolving step in a two-tank TAB production of an example according to the present invention is operated.

FIG. 4 is a graph showing a daily change in PH fluctuation when the base copper melting step in the two-tank TAB manufacturing according to the example of the present invention is operated.

FIG. 5 is a graph showing a daily change in etching time when a base copper dissolving step in a two-tank TAB production according to an example of the present invention is operated.

[Explanation of symbols]

 1 Pump 2 pH Measuring Tank 3 pH Electrode 4 Three-way Cock 5 Piping 6 Base Copper Dissolving Bath 7 Pure Water Piping 8 Solenoid Valve 9 Piping 10 Drainage Piping 11 Three-way Cock 12 pH Calibration Solution 13 Pump 14 pH Calibration Solution 15 Control Section 16 Ammonia Gas cylinder 17 Gas pressure regulator 18 Flow meter 19 Pneumatic opening / closing valve 20 Check valve 21 Gas pipe 22 Compressed air pipe 23 Solenoid valve 24 Polymide film 25 Base copper 26 Lead

Claims (2)

[Claims] 1. A step of automatically measuring the pH of a copper etching solution using a copper ammine complex, a pH difference between the measured pH value and a pH value to be controlled is calculated, and ammonia gas is calculated from the pH difference. A control step of outputting a supply signal; and a step of automatically calculating the amount of ammonia gas required by the ammonia gas supply signal and supplying the ammonia gas in the amount described above to the etching solution. A method of managing an etching solution, which comprises automatically blowing ammonia gas into the etching solution so as to be constant. 2. A measuring unit for collecting a sample of a copper etching solution using a copper ammine complex and automatically measuring the pH of the etching solution sample, and the measured pH value and the pH to be controlled.
A pH difference from the calculated value is calculated, and a control unit that outputs an ammonia gas supply signal based on the pH difference and an amount of necessary ammonia gas are automatically calculated based on the ammonia gas supply signal. A pH control device for an etching solution, which comprises a supply part for supplying gas,
An etching liquid automatic management device, wherein ammonia gas is automatically blown into the etching liquid so that the pH of the etching liquid becomes constant.