SU1733513A1 - Apparatus for controlling metal electrochemical precipitation process - Google Patents

Abstract

Usage: in electrochemistry, to control the thickness of electroplating during the electrodeposition process. Essence Pdsm of invention 1 device contains differential scales 1, measuring electrode 2 immersed in bath electrolyte mechanically connected to one input of differential weights 1, two analog switches 3, 4 and exemplary electrode 5 also immersed in electrolyte connected mechanically to another differential input scales 1 and electrically via the first analog switch 3 with the current bus, with which the measuring electrode 5 is connected via the second analog switch 4. At the same time, the controller 6 is connected to the information input with the output differential weights 1, the control input — with the Start bus, the first and second outputs — with the control inputs of the first and second analog switches 3, 4. 1 sludge. (Ls

Description

The invention relates to electroplating, automation and measurement technology and can be used to control the thickness of the coating of parts during the electrodeposition of metals in the electroplating bath.

A device for controlling the thickness of the electrochemical deposition of metals is known, based on fixing the current change in the weight of the cathode.

A disadvantage of this device is the low accuracy due to the influence of the lifting force of the gas released at the cathode.

Closest to the present invention is a device containing a yoke, which is connected to the anode 2 placed in an electroplating bath and an electromagnetic equilibration system in the form of coarse and accurate compensation coils connected through amplifiers to the outputs of the first and second digital-to-analog converters, as well as , the first output of which is connected to the first input of the compensator, and the second - to the common point of the circuit, a pulse generator, the first and second keys with moving contacts, the code setter, the indicator n charge, trigger and four counters.

The disadvantage of such a device is the greater complexity of implementation and the lack of accuracy in measuring mass.

The purpose of the invention is to simplify the device and improve accuracy by eliminating the effect of changes in electrolyte concentration and voltage on the electrodes on the measurement of mass.

The goal is achieved by the fact that an electrochemical metal deposition control device containing a differential balance, a switching system, a measuring electrode immersed in a bath mechanically connected to the first input of a differential balance, is additionally equipped with two analog switches and a reference electrode, and the reference electrode is installed in the bath, mechanically connected to the second output of the differential balance and electrically through the first analog switch to the current power supply bath line, which A measuring electrode is connected via a second analog switch, the switching system is in the form of a controller, the controller is connected to an information input with a differential balance output, a control input with a bus Power supply of the bath, the first and second outputs with control inputs of the first and second analog keys.

The drawing shows a diagram of the device.

The device contains differential scales 1, measuring electrode 2, analog switches 3 and A. reference electrode 5, controller 6.

The device works as follows.

Prior to the start of coating, the difference in weights between measuring 2 and reference 5 electrodes is measured, the value of which APi is memorized by controller 6 at the moment when the Start signal is received at the control input of controller 6. In the same

The moment the galvanization process starts as a result of the current flowing through the measuring electrode 2, since the key 3 is opened by a command from the controller 6. This current also flows through the electrolyte, the third

the electrode of the electrolytic bath associated with the pole of the voltage source and the voltage source (not shown), the current bus connected with the other pole of the voltage source.

The controller 6 compares the current value of the difference D of the output signal DP2 of the differential weights 1 and the memorized value L Pi with a predetermined tolerance DI stored in its memory. When D Di, on command from controller 6, switch 4 is closed for a short time Dx1, and then keys 3 and 4 open for -J time D12. Connecting the reference electrode to the voltage source leads to the formation of

There are gas bubbles in it, and the subsequent shutdown of the current leads to a process of their dispersion, which is characterized by sufficient homogeneity, which leads to almost instantaneous leveling of the lifting forces, and, consequently, their compensation. For this reason, the effect of gassing on the results of measuring the weight of the coating is excluded.

At the end of the At2 interval,

comparing the value of D, equal to the difference of the measurement results with the differential weights 1 DP2 and the stored value of DTS with the second tolerance value D2. If the value of the difference D is less than this value

or stored in the memory of the controller 6, the key 3 is closed again and the coating process continues for a further time Dtz, after which the controller closes the key 4 again for the time Dx1, and then opens both the keys 3 and 4 for the time At2, at the end of which the difference D is estimated, is equal to the weight of the coating and, therefore, is proportional to its thickness. This process of switching, measurement, and comparison is repeated until the efficiency D becomes equal to or slightly greater than D2, and the controller 6 generates a current shut-off signal in the bath.

The value of the measurement result is generated at the information output of the controller b in the form of a code and on its reading device, calibrated in units of the thickness of the coating.

In cases where it is possible to provide the same lifting force due to gas generation on electrodes 2 and 5 when currents flow through them, key 3 can be closed during the whole galvanization time, while reading all measurement results from scales 1 to controller 6, except memorized D Pi must be made before opening key 4.

As follows from the principle of operation, the accuracy of the device does not depend, for example, on the change in voltage on the electrodes and the electrolyte concentration, since the resulting gas generation equally affects the changes in the lifting forces of electrodes 2 and 5, which are compensated for when measuring the difference between the weights of the electrodes .

Indeed, it follows from the relations

D Pi P2-PS;

D P2 Pp + P2 D G2 - Rb + D G5;

Д ДР2- ДРт Рп:

l Pn / 3d,

where is p2. PS electrode weight 2, 5. immersed in the electrolyte:

Д PI, ДР2 - the differences of the weights Pa and PS, measured by the differential weights 1 at a specified time interval;

D is the current value of the weight measurement results;

Pn is the weight of the coating with a plus sign, if electrodes 2 and 5 are cathodes, and with a minus sign, if electrodes 2 and 5 are anodes;

Dg2 Dg5 lifting force of electrodes 2 and 5 due to gas generation;

I, s, d — thickness, area, and specific gravity of the coating.

A short-term current connection through the reference electrode 5 for the time Fg2, one thousand times shorter than the galvanizing time of the electrode 2, makes it possible to neglect the change in the weight of the electrode 5 due to the deposition of the coating on it during the At2 time.

Simplified implementation is achieved by drastically reducing the requirements for accuracy and stability in the formation of the balancing forces of the weights used with electromagnetic balancing of the total weight of the electrode. Measuring 2 and reference 5 electrodes rather simply 5 are performed with a difference in weight and volume of no more than 1-5%, therefore the requirements for accuracy and stability of the generated compensating forces of the weights used are reduced 20–10 times.

0 The proposed device is especially effective with a small mass and a large surface of the electrodes 3 and 5, since in such cases the measurement errors are reduced from 20-30 to 0.2-2%,

5 In many cases, the measuring electrode 2 can be made as a smaller part of the monitored anode (or cathode) electrically connected to the same size, shape, and weight by the reference electrode and to the majority of the controlled anode (or cathode) by the current leads. This makes it possible to use standard electronic scales, including spring ones, as differential weights 1

5 low accuracy class, to simplify their maintenance, to reduce the time spent on one measurement, as it does not require precise balancing in such scales in the process of control.

0

Claims (1)

Apparatus of the Invention A device for monitoring electrochemical deposition of metals containing a differential balance, a switching system, a measuring electrode immersed in a bath mechanically connected to the first input of a differential balance, characterized in that, in order to improve accuracy by eliminating the effects of electrolyte concentration changes and on the electrodes for measuring the mass, it is equipped with two similar keys and a reference electrode, the reference electrode being installed in the bath, with a single mechanic Combined with the second input of the differential balance and electrochemically through the first analog switch with the current bus power supply to which the second analog switch is connected to 0 measuring electrode, the switching system is made in the form of a controller, while the controller is connected by an information input to the output of a differential balance, the control input is connected to the Start bus 5 power supply of the bath with the first and second outputs - with control inputs of the first and second analog switches.