SU775197A1 - Method of mean-thickness control of part galvanic plating - Google Patents

Description

one

The invention relates to the field of electrochemistry and can be used in the automatic control of coating processes in electroplating baths.

Known closest to the proposed technical essence and the achieved result is a method of controlling the average thickness of the electroplated coating on the parts in the process O of their application, including preliminary measurement of area, detail and indirect determination of the thickness of the coatings 1.

A disadvantage of the known method of $ 1 is that in order to measure the average thickness per part in the working bath it is necessary to preliminarily determine the configuration factor for parts of various shapes in a working bath with a known geometry, i.e. carry out complex and time-consuming measurements, which limits its use.

The purpose of the invention is to improve the control accuracy by automating the determination of the configuration coefficient in the working bath.

The goal is achieved by the fact that as an auxiliary elec-30

For measuring current, the measuring electrode of the thickness sensor is used, the bath current is measured in the mode of stabilization of the tube through the measuring electrode, in the operating mode the current thickness of the coating on the measuring electrode of the thickness sensor is measured and the average thickness of the coating on the part is determined using the formula

.иии

 but

bbDiV.- ° A

where is o

bath current mode

B .. stabilization when

0.:00 nut;

.. (& A) the calculated current value determined by the preliminarily removed dependence of the galvanic bath current on the load for parts with a known configuration factor in the current stabilization mode

OuE is the current value of the coating thickness at the measuring electrode;

Y- - configuration coefficient.

FIG. 1 shows the Lunctional installation diagram; in fig. Figure 2 shows the experimental dependence of the ratio of the current of the working bath to the current of the measuring sensor of the coating thickness as a function of the loading area, taken in the "corisi" mode, for parts with a configuration coefficient K, (curve O), and curves СР. and S for parts with a different configuration coefficient than K and VCjj when the galvanic bath load varies from 100 to 70%; in fig. Figure 3 shows a flowchart of the algorithm for calculating the average thickness of a coating on parts.

The installation consists of a galvanic bath 1 with electrolyte, in which the anodes 2 are permanently mounted, a sensor 3 for measuring the thickness during deposition on an auxiliary (measuring electrode 4 with a known surface area Sjj3 made of metal foil (for example, gold or other hardly soluble material) a) and cathode (suspension with details) 5, power source b, additional power source 7 for etching — a coating deposited on measuring electrode 4, shunt 8 for measuring current through a bath, shunt 9 for measuring current through a measuring electrode, a control computer (UVM; 10 containing information input device 11, information output device 12 and processor 13, coating thickness recorder 14, amplifier 15 with output in the form of contacts 16, initial coating thickness setting 17, comparison circuit 18 with a relay output in the form of contacts 1U, providing in the mode of bleeding the connection through the normally closed contacts 16, the auxiliary electrode 4 of the Sensor 3 to the additional power source 7, the device 20 for defined and the surface area of parts on the suspension 5.

At the beginning of the process, data I (see Fig. 3) is entered into the UVM-10 on the details of the coating modes.

Ii. The surface area of the parts on the suspension 5 is measured using the device 20 by means of a device 20 by any known method / for example, in an electrochemical degreasing bath, using a photoelectric method or counting

quantities of identical parts with a known area for determining the total area, etc.

III - the suspension is recorded in the working bath and the process is carried out in the mode (0 (const) of stabilizing the current through the measuring electrode of the thickness sensor; 1Y - measuring J current of Liu. At; 3 {ue) гconst.

y - is calculated by O.nch L-.6YY. (l) by the known value of the loading area vd for a given configuration of parts and, if necessary, ko. configuration factor K for these parts in the working bath as

b.bON.

TO

l.

where K is the configuration coefficient when the experimental dependence is removed

 L.B.L.B.L.CH.C P jjjj-const

YI - transition to the main mode of operation of the working bath.

YII — The current value of the coating thickness dyj at the measuring electrode of the thickness sensor is measured.

YIII — The average thickness of the coating on the parts is calculated using formula (1).

.към

U)

3

(

L.B. ATTIC 3 (b) (g, calculated according to the previously removed empirical curve in Fig. 2, which can be approximated by the following expression:

 (2)

Kb

0 gDe A, B, C - constant coefficients,

The calculated average thickness is c1de. registered with registrar 14.

Example. The method was tested in the electroplating shop engineering plant. As a thickness gauge, a radioisotope thickness gauge was used, with the coating being etched from the measuring electrode during the absence of 0 parts, in the bath by connecting to an additional power source.

The measuring electrode of the thickness sensor was located in the plane of the suspension.

The measurements were carried out as follows: previously, a suspension with parts was lowered into the working bath and curve 3 was taken.

™ 1 G 1 “V

 UAttN. (d,} at, g for a certain group of parts with a known value of the configuration coefficient. After that, a suspension with parts whose configuration ratio is not known was omitted, and in the steady-state mode it was measured. And. R values of the first case, And further the baths were put into operation, the algorithm for calculating the following was calculated, the current was calculated according to expression (2) and the following system of equations was solved:

e.yu.Rayt.-5,

WITH) . Progress 2

Where

Rdyt is the average current density over the surface S of parts for which the dependence of FIG. 2 PI - same on & 2

. Covered parts. Since it is assumed that the response of the control object (galvanic bath) with the same load S ,, j is the same, the expression:

.bww.

(four)

GR

l. nde, t. j) g

taking into account configuration factors

And, and

(five)

1D, et

 - ua / j.

(6)

Att

, Rj9 bw.

. C7)

bUSM.v ;, j),

of

 e, .1ЫЧ.Ч: Ьм) - (в)

Considering that the thickness of the coating. on parts x can be defined ps formula:

..iiBllfLl

C9)

AUT

Where

С - electrochemical equivalent of electrolyte, g / Ah;

D specific gravity of the precipitated metal, €, current efficiency,%

g process time, h

RA “Tsredn current density on the surface of parts, A / dm; From expressions (5) and (6), we obtain the relation between the configuration coefficient and the coating thickness on the measuring electrode 4 and the average thickness on the details.

c-e, -t

years old

years old

taking into account 8 and 10 average thickness on. the parts covered are defined by (1).

The method is based on the following two assumptions / tested with experimentally: the response of the control object (galvanic bath) with the same load, i.e. the area of workpieces, but the different configuration of parts is the same; average current density per

About the surface of the measuring electrode of the coating thickness sensor and on the surface of the parts to be coated, with different configurations - different.

5 It is assumed that the level, temperature, electrolyte concentration is stabilized.

It should be noted that, in spite of their different geometries, the details, however, may in some cases have the same configuration factor.

On the basis of the experimental data obtained, the following conclusion can be drawn: the thickness of the coating on the details, according to expression (1), is measured with an error of 8%; The method is applicable to the majority of electroplating processes, for example, measures of galvanizing, cadmium plating, nickel plating, etc.

Claims (1)

1. USSR author's certificate 5 I 647363 class, C 25 D 21/12, 1978. U 7G  J rig.1