JPS5989756A - Automatic control device for plating solution - Google Patents

Abstract

PURPOSE:To enable evasion of malfunction owing to a noise signal, simplification in circuit constitution of an amplifier, ease of adjustment and spacing between specific sensor and control units by using said units to a control device and connecting both units by means of an optical fiber. CONSTITUTION:A control device consists of sensor and control units 9, 10 between which communication is accomplished by means of an optical fiber cable 8. A plating soln. is conducted to sensors S1-Sn and the outputs of the sensors are converted from analog to digital values by converters C1-Cn at every specified time. The converted values are stored in the device 1. The average value of the stored values is sent by the request of a main calculator 6 to an apparatus 6. The apparatus 6 determines the concn. of the soln. compsn. by a prescribed equation from the output values of the respective sensors and calculates deficiency by a difference from a set value. Said apparatus commands a pump switch 4 to run a pump for a required time thereby supplying the replenishing soln.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for automatically analyzing and controlling the concentration of chemical components in an electroless plating solution.

Conventionally, the concentration of the main components of electroless plating solutions has been controlled by intermittent chemical analysis to adjust the hot water temperature. However, since the properties of the plated film are significantly affected by the concentration of the main components of the plating solution, it has been difficult to satisfy the reproducibility of the physical properties of the plating and the reliability of the plated film with intermittent control.

Therefore, in order to eliminate these drawbacks, there has been a demand for continuous automatic analysis and concentration control.

When fully automating concentration management, a change in concentration is detected as a change in voltage or current value. For example, a glass electrode or an absorbance meter 1 is used to perform this detection.

However, analysis performed using these glasses, poles, or spectrophotometers suffers from interference from compounds and ions other than the target components, resulting in a decrease in analysis accuracy. For example, the detection results of a spectrophotometer for measuring ion concentration are affected by the pH of the plating solution, the concentration of ions other than copper ions, and the bubbles of hydrogen gas present in the plating solution.

In electroless copper plating solution, the main components whose concentration should be controlled are:
The pH of the plating solution is copper ion concentration and reducing agent concentration. p
For H control, the hydrogen ion concentration is generally detected as a potential through a glass electrode and a thin electrode tube using a voltmeter with high input impedance. If the detected potential is lower than the set potential, the replenishment pump operates to replenish the highly alkaline aqueous solution to increase the pH and control the pH value to fall within a predetermined control range. When the detected potential becomes larger than the set potential, the replenishment pump is stopped and replenishment of the highly alkaline aqueous solution is stopped. Other constituent chemicals are detected as potentials, and the supply of replenisher is started or stopped depending on the magnitude of the potential with respect to the set value.

However, with this conventional device, (a) the difference between the detection potential of the electrode and the first comparison is small, and noise in the factory or noise from the amplifier in the first detection box of the glass electrode causes these supplements to be lost. Sometimes the liquid was not refilled at the correct timing, and sometimes it was refilled when there was no need to refill it.

(b) The detection potential is normally 0 to 300 mV, and noise in the factory in the communication path between the sensor unit and control unit may cause the transmitted signal level to change, resulting in incorrect data or changing the replenishment amount. was there.

(c) In order to increase the signal potential and reduce the shadow 41 caused by noise on the transmission path, an amplifier is required, and the adjustment operation becomes complicated. For this reason, an amplifier that can sufficiently ensure the operational reliability of the device and the reliability of the detected potential is expensive and complicated.

2) When determining the composition concentration of the plating solution, in order to remove the influence of the pH value and temperature of the plating solution, the detection potential of each sensor is appropriately converted, and in addition to the detection potential that indicates the composition concentration to be determined, A circuit to correct the data was required. Therefore, the v14 adjustment of the amplifier for each detection potential was complicated.

(e) If the glass electrode signal amplification part and the pump operation control part are separated far apart, the current flowing through the cable required for connection will cause a potential difference between the two ends of the cable, making it impossible to control the pump with the correct measured potential. could not.

SUMMARY OF THE INVENTION An object of the present invention is to provide a plating solution internal motion control device that eliminates the conventional drawbacks such as.

According to the present invention, the compositional concentration of the plating solution in the plating tank is automatically measured, and when the concentration falls below a predetermined level, the plating replenisher is automatically replenished to automatically keep the compositional concentration along the plating within the predetermined range. The internal motion control device for the plating solution to be adjusted has a function of guiding the plating solution to the center, converting the sensor detection potential from all analog to digital, and a function of operating a pump that supplies the plating solution. Calculate the compositional concentration of the plating solution from the signal obtained from the Y-unit, and determine the amount of replenishment if the concentration is below a predetermined concentration.
There is obtained a plating solution internal movement control device characterized in that the communication between the sensor unit and the control unit is realized by an optical fiber cable.

Hereinafter, the configuration of the device of the present invention will be explained using the first drawing. Sensor 81.82. ...SN is a non-electrode that measures the pH formalin concentration of the Soresol plating solution and the concentration of other additives, a spectrophotometer that measures the copper ion concentration, and a temperature sensor such as a thermocouple.

Amplifiers AI, A2...AN adjust to the input range of the analog-to-digital converter (A/D converter) CI, C2,..., CN.Control The unit executes a certain program using a microcomputer, and the A/D
Memorize the appearance of Convaata in Memory Equipment 1. The first communication circuit 2 generates an interrupt signal to the control section when a signal is received from the control unit 10, which will be described later.

When the control unit 3 receives the interrupt signal, it decodes the signal from the control unit 1° and activates the pump switch 4.
control, or transmit the output values of the sensors (81 to SN) through the communication circuit. The output value of the sensor shall be the average value of the values measured before the request for data from the control unit 10. For example, if measurement is performed every second, the average value of the values for 10 seconds before the request is sent. send. control unit) i o c・Second communication circuit 5, main "[N
, machine 6, record #! The system 7 sends the center output value to the sensor unit 9, issues a request for pump operation, determines the plating solution composition concentration from the center output value, and determines the request for replenishment solution. In addition, the plating solution composition # and the amount of replenisher supplied are recorded in the recording device. Communication between the sensor unit 9 and the control unit 10 is via an optical fiber cable 8.Next, a method of operating the plating solution control device of the present invention will be described.

A plating solution is pumped from a plating tank (not shown) to a pump (not shown) and sensors 81, 82.・Piping team up to SN group
Each sensor 81, 82...
・A/D converts the SN output at fixed time intervals ◇A/D
The converted value is stored as 1 in the storage device. (However, the memorized value shall be the value within 1 minute from the measurement.) If there is a request from the main computer 6, the average value (output value) of these 1%/D converted memorized values will be send to Payroll W machine 6 is
From the output value of each sensor, use the following formula to determine the concentration of the plating solution composition.

pH=A IIVpH 10B ・('1'-a) 10C--
-----(1) Cu=DIIVcu 10E (pH-b
) −1−F ・−=(2) HCHO=G・Vn
cuo+H・(Il゛-a)+1・(p)j-b)+J
-(3) vpii, V HO is pi-i formalin, the potential of the electrode for concentration measurement, Vcu is the absorbance H1
(2) It shows the detected potential, and Cu and HCHO show the concentration of each composition. ,A,U,C,D,E,l
i”, G, li, l, JJ,, coefficients for subtraction,
The experimentally determined values a and b are values that serve as standards for the PH temperature of the plating solution. Using the above formulas (1) to (3), calculate the composition concentration of the plating solution, find the difference from the predetermined composition of the plating solution, and calculate the shortage.
[L, sends a command to the sensor unit to rotate the pump by ml when necessary. The sensor unit 9 executes the command to rotate the bong 7 instructed by the master unit 6, operates for a predetermined time, and then stops.

As described above, according to the present invention, (1) it is possible to correct the influence I# of each plating solution on the measured value by a total of n units, so that the output of each sensor 1- can be adjusted with each increase. There is no need to feed back to the device, and it is easy to construct an amplifier circuit or a Hayabusa Fil VL y-leg board. (11) When the composition a degree is required, the value sent to the main meter) v is the average value of the values measured within the past minute, so there may be variations in the Sentsu output due to amplifier difficulties or noise in the factory. has been reduced. (lit) Sensor unit and control unit tlj: Because they are connected by optical fiber, there is no signal disturbance due to noise in the factory, and even if there is a difference in operating potential between the sensor unit and control unit, the operating signal will not change. The sensor unit and control unit can be installed apart from each other without causing any adverse effects.

[Brief explanation of the drawing]

FIG. 1 shows an automatic plating control device according to the invention. St, Sz, -, , Sl, , , , sensor, At
,Az,・An---Amplifier, CI, C2,...
Cn...Analog/digital controller,
1...Storage device, 2...Communication circuit, 3.
・・Control unit, 4・・・・Pump switch, 5・・Communication circuit, 6・・Payment yp, tp, 7・Storage device, 8・・Optical fiber cable, 9・・...Sensor unit, 10゛°゛・control unit.

Claims (1)

[Claims] The plating solution internal movement automatically measures the composition concentration of the plating solution in the plating tank and automatically replenishes the plating replenisher when the concentration falls below a predetermined concentration, automatically adjusting the composition concentration of the plating solution within the predetermined range. In the control device, a sensor unit having a mechanism for guiding the plating solution to the SENTU and converting the SENTSU detection potential from analog to digital, and a mechanism for operating a pump that supplies the plating replenisher, and a signal obtained by the SENTSU unit. From there, the composition concentration of the plating solution is determined, and the amount of replenishment is determined if the concentration is below a predetermined concentration. Communication between the potash control unit and the sensor unit control unit is performed using an optical fiber cable. A plating solution internal motion control device characterized by: