RU1813814C - Apparatus to control given thickness electroplating process - Google Patents

Abstract

Use: electroplating. SUMMARY OF THE INVENTION: the device comprises a current sensor 1, a voltage-frequency converter 2, a counter 3, a digital-to-analog converter 4, a comparison circuit 5, a surface area input unit 6, a current regulator 7, a normalizing amplifier 8, a multiplier 9, and a current density adjuster 10 According to the set current density and surface area of the loaded parts, the following operations are automatically performed: the bath current is set and the set value of the amount of electricity that must pass through the electric um to obtain a predetermined thickness. The current value of the amount of -electricity is calculated using the first four nodes. When the current and calculated values are equal, the signal from the comparison circuit 5 stops the process. 1 ill.

Description

FIELD OF THE INVENTION This invention relates to electroplating and can be used in the coating of precious Rletzlides.

The purpose of the invention is to increase the accuracy of coating a predetermined thickness.

The drawing shows a functional diagram of the device.

The device comprises a current sensor 1, a voltage-frequency converter 2, a counter 3, a digital-to-analog converter 4, a comparison circuit 5, a surface area input unit 6, a current stabilizer 7, a normalizing amplifier 8, a multiplier 9, and a current density adjuster 10,

The current sensor 1 is connected through a voltage-frequency converter 2, a counter 3, and a digital-to-analog converter 4 to the first input of the comparison circuit 5. The output of the surface area gadfly block 6 is connected to the input of the normalizing amplifier 8 and to the first input of the multiplier 9, the second and the third input of which, respectively, is connected to the current density adjuster 10 and to the output of the comparison circuit 5. The second input of the comparison circuit 5 is connected to the output of the normalizing amplifier 8. The output of the current stabilizer 7 is connected to the current sensor 1, and the input is multiplied 9 th device.

Current sensor 1 is a shunt. The voltage-frequency converter 2, counter 3, digital-to-analog converter 4 and comparison circuit 5 are made on the basis of integrated circuits. The surface area input unit 6 comprises program switches for inputting the surface area and an electronic circuit for converting the code into an analog signal. The stabilizer 7 provides a constant current galvanic bath. The normalizing amplifier 8 is made on the basis of an integrated operational amplifier and has gain control. The multiplying device 9 is made on the basis of an integrated digital-to-analog converter. The current density adjuster 10 is based on a potentiometer.

The device operates as follows. To calculate the amount of electricity needed to apply a given coating thickness, a mathematical model of the form

Q K Z0 S, (1) where Q is the amount of electricity needed to achieve a given coating thickness;

Z0 is the desired coating thickness;

S is the surface area of the loaded parts;

K is the coefficient determined experimentally, for example, by

least squares.

Before loading the parts into the bath, the operator, using blocks 6 and 10, enters the surface area of the parts and the current density setting, and also sets the value «about the gain of the normalizing amplifier 8. Thus, at the output of the normalizing amplifier 8, an electric quantity setting is formed before the process starts, which must pass

through an electrolyte to achieve a predetermined coating thickness. This voltage is applied to one of the inputs of the comparison circuit 5. During the electroplating process, the amount of electricity is measured using an analog-to-digital current integrator based on current sensor 1, voltage-frequency converter 2, counter 3, and digital-to-analog converter 4. Measurement is performed in the following way. It is known that the amount of electricity Q is defined as

Q M (t) dt,

(2)

where i (t) is the dependence of the bath current on time t;

d - integration time (duration of the process), Voltage Uui (t) at the output of current sensor 1 has the form:

UUj (t) Ruj -i (t), (3) where RUI is the shunt resistance.

The output value f (t) of the voltage-frequency converter 2 is determined as follows:

f (t) Kr, H4-ich (g), (4) where Kpnch is the voltage-frequency converter conversion coefficient.

The number of pulses N, counted by the counter 3 over time g, is determined by the expression:

N /0f(t)dt.(5)

Substituting in (5) sequentially (4) and (3), we obtain $

N Rp Kpnch / Oi (t) dt.

So the number N written in

counter 3, as well as the output voltage

digital-to-analog converter 4, are proportional to the amount of electricity Q,

calculated according to (2).

The voltage from the output of the digital-to-analog converter 4 goes to the other input of the comparison circuit 5, If the current value is equal to the setting value, the comparison circuit 5 is activated. By the signal from its output, the multiplying device 9 is locked, the voltage of the current setting, and also the current of the bath, become equal to zero, and the electroplating process is interrupted. Assume that the resulting coating thickness Z is 10% greater than the nominal Z0. In order to obtain the coating thickness Zo, it is necessary to reduce the gain of the normalizing amplifier 8 by 10%, i.e. set the gain Ki such that Ki Ko is 0.1 Ko. Suppose that in the next boot, the area of the parts is changed. In this case, after entering the surface area value at the output of the current stabilizer 7 into the device, the bath current value is set to provide a predetermined current density value. In accordance with the surface of the loaded parts, a new setting will be formed for the amount of electricity that must pass through the electrolyte in order to obtain the specified coating thickness Z0. Since the gain of the normalizing amplifier 8 has already been adjusted according to the results of the previous galvanizing process, the coating thickness will correspond to the set value Z0.

Automatically calculates the bath current setting for a given current density when the loading surface changes

processed products from batch to batch, as well as adjusting the setting of the amount of electricity that must pass through the electrolyte to achieve a given coating thickness, taking into account the actual thickness of the coating, can improve the accuracy of applying the coating of a given thickness.

Claims (1)

SUMMARY OF THE INVENTION An apparatus for controlling a coating process of a given thickness, comprising a current stabilizer, a current sensor, a voltage-frequency converter, a counter, a digital-to-analog converter and a comparison circuit, a surface area input unit, characterized in that, in order to increase the accuracy of the coating, it is equipped with a multiplying device, a normalizing amplifier and a current density adjuster, and the output of the surface area input unit is connected to the norm input uyuschego amplifier and the first input of a multiplier unit, the second and third inputs of which are respectively associated with setpoint current density and comparing the output circuit, the multiplier output device connected to the current regulator, and the output of the normalizing amplifier - a second input of the comparator circuit.