SU1763880A1 - Device for checking anode area of galvanic pair - Google Patents

Description

one

(21) 4829832/24

(22) 04/09/90

(46) 09/23/92. Bul No. 35

(75) Yu.G.Podkin and Yu.V. Danilov

(56) Copyright Certificate of TsRB № 29380, cl. G 01 B 7/32, 1977.

Copyright Certificate Czechoslovakia № 203578, cl. G 01 R 13/02, 1980.

(54) DEVICE FOR CONTROL OF ANODE GALVANIC PAIR AREA

(57) The invention relates to measurement technology and automation. Its use to control the area in an electroplating bath improves the accuracy of measurements. The device contains a converter of 1 input signal into a sequence of pulses, a display unit 8 and a pulse counter 10. Due to the introduction of a frequency with a constant factor into the divider 7, the variable factor divider 9 and the data input unit 11, a digital feedback circuit is organized to take into account the change in the anode current during the galvanic dissolution of 1 Cp. 1 il.

Yo

Vj os

with

00 С О

The invention relates to measurement technology and automation and can be used for monitoring the areas of anodes immersed in a galvanic bath and dissolved during electrolytic deposition of coatings.

A known device for measuring the surface area of metal products, containing a bath with electrolyte, a positive electrode-anode in the form of a bath lining, a rod connected to the negative pole of the current source, on which the metal product to be measured is suspended. The area measurement is carried out by comparing the values of the currents flowing through the measured sample and the standard.

The disadvantage of this device is that the measurement algorithm includes alternating immersion of the sample and standard into the bath and comparison of the absolute values of the currents flowing in the bath. However, when periodically removing samples from the bath, the electrochemical processes in the surface layers of the electrodes are distorted, and signal processing under production conditions reduces reproducibility and measurement accuracy.

Closest to the invention is a digital planimeter containing a voltage-to-frequency converter, a relay through which pulses arrive at the counter, and a display from which the value of the measured value is read. However, the linear transformation of monitored values into output signals implemented by the planimeter does not ensure the required accuracy of measurements when monitoring the anode area.

The aim of the invention is to improve the measurement accuracy

The drawing shows a functional diagram of the device for controlling the area of the anode of the galvanic pair.

The device comprises an input signal to a pulse sequence converter 1 consisting of a current-voltage conversion unit 2, a zero-reset unit 3, an integrator 4, a setting unit 5, and a comparator 6.

In addition, the device contains a frequency divider 7 with a constant coefficient, an indication unit 8, a variable factor frequency divider 9, a pulse counter 10, and a data input unit 11.

The operation of the device is based on the dependence of the surface area of the anode, which is dissolved during the electroplating process, on the metal consumption.

In the process of galvanic metallization, the mass increment of the deposited metal Dgpc on the cathode at current I during time At is equal to

 I Dogog, (1)

where K is the electrochemical equivalent; a- current output

The mass of the substance DgPa, transferred to from the anode to the cathode when the anode is evenly dissolved is equal to

S-Ah,

(2)

where p is the density of the coating metal; S is the anode area; Ah is the thickness of the metal layer removed from the anode surface during the metallization process.

From formulas (1) and (2) it follows that

DI K- | - (3)

For non-stationary processes, the instantaneous rate of change of the anode thickness

jlH-A-Ll {l

dt-S-yO (4)

whence the thickness of the metal layer removed from the anode surface during time t is equal to

h K / I

dt

(five)

about -

The initial area of the parallelepiped anode with sides a, b, c is equal to

50 2 (ab + ac + be). (6) During the time interval 0 - tj in the process

metal halodeposition of the anode surface is reduced to

51 2 (a - 2hi) (b - 2hi) + (a - 2hi) (c - 2hi) + (b - 2hi) (c - 2hi) + ac + be - 4hi (a + b + c) + 12hi2, (7) where hi is the thickness of the metal layer removed from the anode during this time interval.

If the time interval is small, then hi a, b, c. Then, neglecting the last term in expression (7) due to its smallness, taking into account formula (6), have

51 S0-8hi (a-t b + c). (8) In the next time interval ti - t2, a layer of metal with thickness ha is removed from the anode surface;

52 So - 8 (hi - h2) (a + b + c) Si - 8gf + + b + c). (9)

Summarizing expressions (8) and (9), upon the completion of the 1st electroplating cycle for a flat anode,

S, Si-1 - 8hi (a n b + c). (10)

From formula (5), due to the smallness of the area change in the cycle, they have

t

eft

given the formula (10) receive

Si Si-1 - 8K (a + b + c) / i i.

o P ° i (12)

To convert the galvanic coupler current into a sequence of pulses, first, unit 2 converts the current of the electroplating bath I into a voltage

UI-A.I, (13)

where A is the conversion factor.

The voltage Ui is fed to the input of the integrator 4, the output of which is the voltage

iint | Uldt (14

where m is the integrator time constant. Expression (14) can be represented as a sum of integrators, for which during the integration time Ui | const

j} u, i / u., dtT.

4 2 Uii-T ,,

whereT | 1, -1i. Let be

ui

Taking into account formula (17), expression (15) degrades

   i and ,, -T, i iop

T 1

about

 N-Uon. (18)

In order to implement the conversion (18), it is necessary to compare the current voltage at the output of integrator 4 with the reference Don and periodically, with UHHT Uon, reset the integrator 4 to the zero state. For this purpose, the voltage from the output of the integrator 4 is inputted to the first input of the comparator b, at the second input of which the setting unit 5 is set, the voltage Uon. When the voltage UHHT reaches the reference value Uon, from the output of the comparator 6 to the input of the zeroing unit 3, the level of the logical unit arrives. The reset pulse generated in the nulling unit 3 arrives at the control input of the integrator 4, and during the time time n, the integrator 4 is set to the zero state; then the process is repeated

At the output of the comparator 6, during a time t, a sequence of N short pulses is formed, the number of which taking into account expressions (13), (14) and (18)

 / I

proportional to the consumption of the anode material during galvanic deposition. Thus, block 1 converts the current of the anode into a sequence of pulses at the output of the comparator 6. The normalization of the scale factor SH, convert the current value of the area of the anode into a digital code:

S1 J- (20)

Bh

0 Then the value of the area code from formula (12), taking into account expressions (19) and (20), is equal to

S,

1st I 8 K (a + b + s) t Un

SZI - v.2. one

N

/ oSS -A -Sl-i

(21)

15

Polaga

20

(22)

8K (a + b + c) r. (22) finally have from expressions (2) and

Si-Sn1N

,)

Thus, to determine the current area code, it is necessary to divide the number of 25 pulses N of the converter 1 of the input signal into a series of pulses by

п По.Зн1 (24)

and subtract the value obtained from the previous area code. To this end, the output of the comparator 6 through a frequency divider 7 with a constant coefficient, the division ratio of which is Po, and a divider 9 frequency with a variable coefficient,

OC having a division factor of 5m1. connected to the subtracting input of the counter 10 pulses. The outputs of the counter 10 are connected to the control inputs of the frequency divider 9 with a variable coefficient (despite the fact that

4Q sets its division factor) and with the inputs of the display unit 8, which displays the current area S; .

The device for controlling the area of the anode of the galvanic pair works as follows. Data input unit 11 generates and feeds the initial anode area code to the installation inputs of the pulse counter 10. From the outputs of counter 10, this code is entered into the control inputs of the divider.

CQ 9 frequencies with a variable factor, given its division factor, and to display unit 8, where it is displayed as the initial area. The current of the plating bath by the unit 2 is converted into a voltage and

cc is supplied to the integrator 4, the output voltage of which by the comparator 6 is compared with the voltage of the block 5 of the setpoint Uon. With UHHT Don, from the output of the comparator 6 to the input of the zeroing unit 3, the level of the logical unit arrives. Formed in

in the resetting unit 3, a reset pulse is supplied to the control input of the integrator 4 and sets it to the zero state. Thus, block 1 converts the current into a sequence of pulses. These pulses from the output of the comparator 6 are fed through a frequency divider 7 with a constant coefficient (division factor - n0) to the input of the frequency divider 9 with a variable factor. The control inputs of the frequency divider 9 with a variable coefficient from the outputs of the counter 10 are fed with an area code of 5 m, which determines the division factor of the frequency divider 9 with a variable coefficient in the i-th cycle. As a result, at the output of the divider 9 frequency with a variable coefficient, the number of pulses is equal to

bp Impulses from the output of divider 9

By 0 | - one

a frequency with a variable coefficient is fed to the subtracting input of the counter 10 pulses, with each pulse decreasing the area code Si-i1 recorded in the counter 10 by one. As a result, a code Si is generated in the counter 10. This code is inputted to the control inputs of the frequency divider 9 with a variable coefficient, fed to the display unit 8 and displayed as a measure of the anode area in the (1 + 1) -th cycle. Thus, in contrast to the known, the proposed technical solution contains a digital feedback branch that provides a more accurate measurement of the anode area, which makes it possible to reduce the error in setting the current density in the electroplating baths and thereby increasing the metal utilization efficiency by 10-15%.

Claims (2)

1. A device for monitoring the area of the anode of the galvanic pair, containing a converter of the input signal into a sequence of pulses, the input of which is the device input, a pulse counter whose outputs are connected to the inputs of the display unit, characterized in that, in order to improve the accuracy measurements, a frequency factor divider with a constant coefficient, a variable frequency frequency divider and a data input unit, the outputs of which are connected to the pulse counter installation inputs, are entered into the device; frequencies with variable coefficient, the control inputs and the output of which are connected respectively to the outputs and the subtracting input of the pulse counter. 2. The device according to claim 1, in which the converter of the input signal into a sequence of pulses contains an integrator, a comparator, a setpoint unit, a zeroing unit and a unit for converting current to voltage whose input is The input of the converter, the output of the current to voltage conversion unit is connected to the integrator's information input, the output of which and the output of the setpoint unit are connected to the first and second inputs a comparator, the output of which is connected to the input of the zeroing unit and is the output of the converter, the output of the zeroing unit is connected to the control input of the integrator.