EP0563137A1

EP0563137A1 - Arrangement for an installation used for the electrolytic treatment of workpieces

Info

Publication number: EP0563137A1
Application number: EP19920901291
Authority: EP
Inventors: Egon Hübel
Original assignee: Atotech Deutschland GmbH and Co KG; Schering AG
Current assignee: Atotech Deutschland GmbH and Co KG
Priority date: 1990-12-22
Filing date: 1991-12-22
Publication date: 1993-10-06
Also published as: DE4041598C1; CA2099008A1; WO1992011401A1

Abstract

L'invention prend pour base un dispositif dans une installation servant au traitement électrolytique de pièces, laquelle comporte deux barres anodiques (2) avec des anodes (A) montées en série, et une barre cathodique (3) sur laquelle sont montées en série des pièces (W). Pour assurer, avec des moyens simples et sans pertes d'énergie notables, la même tension d'élément efficace sur chaque pièce et ainsi obtenir approximativement la même épaisseur de dépôt de matière sur chaque pièce, on prévoit des rapports différents de section des barres anodiques (2) à la barre cathodique (3) et/ou des modifications de la résistance ohmique par unité de longueur de ces barres et/ou des résistances (R) entre chaque barre anodique (2) et l'anode (A) qui lui est respectivement raccordée. On obtient ainsi des alimentations en courant définies dans les barres anodiques (2) et une sortie de courant définie en provenance de la barre cathodique (3).The invention is based on a device in an installation used for the electrolytic treatment of parts, which comprises two anode bars (2) with anodes (A) connected in series, and a cathode bar (3) on which are mounted in series pieces (W). To ensure, with simple means and without significant energy losses, the same effective element voltage on each part and thus obtain approximately the same thickness of material deposition on each part, provision is made for different section ratios of the anode bars. (2) to the cathode bar (3) and / or changes in the ohmic resistance per unit length of these bars and / or the resistors (R) between each anode bar (2) and the anode (A) which is respectively connected. This produces current supplies defined in the anode bars (2) and a defined current output from the cathode bar (3).

Description

Arrangement in a system used for the electrolytic treatment of workpieces

The invention is based on an arrangement according to the preamble of claim 1. This is primarily intended for the field of electroplating, but also for other systems for the electrolytic treatment of workpieces, for example electrophoresis. The parts or workpieces to be treated usually form the cathode and are conductively connected to the cathode rail. The cathode rail usually forms the so-called product carrier. The anodes are connected to the two anode rails, which, like the workpieces, are located in the bathroom. The workpieces can be lowered into and removed from the bathroom using product carriers. The anode rails and the cathode rail are located outside the bath liquid, while the anodes connected to the anode rails and the workpieces connected to the cathode rail are located within the bath liquid. The anode rails and the cathode rail have a double function in that they must have sufficient mechanical stability to carry the anodes or the workpieces. They should also have sufficiently large cross sections with high conductivity for the supply and discharge of the usually very high electrolytic treatment currents. Even if the material copper has a very high electrical conductivity, it is generally not suitable for the production of such rails due to its susceptibility to corrosion and its low mechanical strength. For this reason, stainless steel is preferred in practice for reasons of contact security and mechanical strength. The disadvantage of a much lower conductivity than that of copper is accepted.

A bath contains a number of so-called parallel cells with the workpieces to be treated electrolytically. Doing so will be even

Strength of the electrolytic coating on all workpieces, ie aimed in all cells. This can only be achieved if the electrolytic current is approximately the same in all cells, which in turn requires a corresponding equalization of the galvanizing voltages (cell voltages) for all workpieces. Since voltage drops now occur in the anode rails and also in the cathode rail, this results in a change in the galvanotechnically effective cell voltage for each workpiece in the course of the rails, with the consequence that the thickness of the electrolytically applied layer is different for the individual workpieces . This effect is amplified in newer systems by the fact that the cell voltage U _{z is to be kept} very low, for example in that, in order to save energy in electrolytic baths

The order of magnitude of 1 V. This means that differences in the cell voltages caused by the voltage drop in the rails, which are in the millivolt range, have a negative impact.

Either you have accepted the above disadvantage or you have tried it in different ways remedy. The cross sections of the anode rails and the cathode rail have been enlarged in order to reduce undesired voltage drops ΔU. Or instead of the mechanically advantageous material stainless steel, the rails were made of copper. The then higher weights of the rails and the resulting costs set economically very narrow limits. When copper was used, it was also susceptible to corrosion by the aggressive electrolytes of, for example, electroplating baths. In practice, no improvements or only insignificant improvements have been achieved. Attempts have also been made to feed or discharge the currents from both ends of the rails, this requires constant contact resistance of the contacts at both ends, but this could not be achieved in practice. In addition, the voltage drop generated by the current required along the rail is not eliminated, but rather reduced to half, ie errors due to voltage drop are only eliminated to a limited extent. Alignment of these errors significantly or even completely

Individual voltages of all cells and thus an equalization of all cell currents could not be achieved. From DE-OS 37 32 476.4 a method for equalizing the partial currents in an electrolytic bath is known, in order to improve the layer thickness distribution, passive series resistors have been introduced into the technologically conditioned partial circuits (cells) of the total electrolytic circuit, so that the series circuit thus formed Size of the partial currents were determined by the series resistors. In DE-OS 37 32 476.4 no details are given about the number and arrangement of the anode and cathode rails. In particular, no technical teaching is given on where the respective currents are fed into the rails and where they emerge from the rails. The technical disclosure content of this Literature is therefore limited to the use of the aforementioned series resistors, these series resistors being said to be significantly larger than the technologically caused unstable electrolytic partial resistance. According to the Kirchhoff law, the aim is to ensure that the individual partial currents, ie the cell currents, become the same size if the series resistors are large enough. The use of such large resistances results in corresponding energy losses and high voltage drops in the case of correspondingly large electrolyte partial currents. Both are in contrast to the requirements of energy saving and working with voltages in the range of 1 V explained at the beginning. The dimensions of the resistors are very large due to the high currents and are therefore very difficult to use constructively. In addition, the cost is not negligible for the same reason. DE-OS 29 51 708 dealing with the same problem is far too expensive in terms of apparatus. The object or problem of the invention is, even when using electrically worse than

Copper-conducting anode and cathode rails, for example made of the mentioned stainless steel, with simple means and without substantial energy losses to ensure that the same cell voltage is effective on the individual workpieces of the cells of such a bath. This is one of the prerequisites for the desired material precipitation of approximately the same thickness on each workpiece. To solve this task and problem, starting from the preamble of claim 1, the combination of features a) and b ₁ ) of the characterizing part of claim 1 is provided. The features of section a) have the effect that the passage of current through the anode rails in the feed direction from anode to anode is reduced, since part of this current is discharged into the bath with each anode. On the other hand, the current takes on the cathode rail in the same direction until it emerges on the other side of the bath from workpiece to workpiece, since a corresponding partial flow flows to it for each workpiece (cathode). If one considers this arrangement from one side of the bath, on which the feeds are located in the anode rails, to the other side of the bath, on which the current exit from the cathode rail is provided, this has assumed a constant cross section of each of the aforementioned rails, in this direction, the voltage drop per rail length is reduced on the anode rails and the voltage drop increases on the cathode rail. Both compensate at least partially. Added to this are the effects of characteristic b.). With this ratio of the cross section of the cathode rail (Q _K ) to the cross section of the anode rails (Q.), the fact is taken into account that the cathode rail must absorb and transmit the electrolyte currents of both anode rails. The anode rails and the cathode rail can thus consist of a material which is corrosion-resistant and poorly conductive with respect to copper, for example stainless steel.

An alternative solution to the above-mentioned task and problem arises from the subject matter of the independent claim 2. The generic term and feature a) are identical to the corresponding sections of claim 1. Section b ") contains an increase in cross-section or a reduction in cross-section of the rails, which corresponds approximately to the changing sizes of the currents in the rails and thus to approximately the same cell voltage as a result of the voltage drops in the individual subsections of the rails, which are caused by Ohm's law every cell of the bathroom leads. A further, subordinate and alternative solution to the aforementioned task and problem is the subject of claim 3. Also in this are the preamble and feature a) identical to those of claim 1 and claim 2.

Characteristic b ₃ ) is different. This also achieves equalization of the partial electrolyte currents of the individual cells and thus the goal of the task, but the disadvantages explained in reference to DE-OS P 37 32 476.4 are avoided. In addition, DE-OS P

3732476.4 neither the arrangement of features of the preamble nor that of section a) of claims 1, 2 and 3. In the case of characteristic bJ, however, it is not possible

Select resistances as high as specified in DE-OS P 37 32 476.4. Rather, according to Ohm's law, the size of these resistors must be coordinated with the other electrical data, in particular the voltage drops, with the overall arrangement, so that the desired equalization of the partial currents occurs.

Advantageously, the features specified with the claims 1, 2 and 3 in the sections b ₁ ), b ₂ ) and b ₃ ) are combined with one another, the features of the preamble and section a) being shared. This is the subject of claims 4 to 7 and results in a corresponding interaction of the features of sections b ₁ ), b ₂ ) and b ₃ ). Further refinements, advantages and features of the invention can be found in the further subclaims, as well as in the following description and the associated, essentially schematic drawings. Only those features are shown in the drawings that are necessary for understanding the invention:

1: an arrangement according to the prior art, FIGS. 2 and 3: arrangements according to the invention,

Fig. 4: a basic representation of the voltage drops and voltages in a Stromver run as shown in FIGS. 2 and 3, but not taking into account the effects of features b ₁ ), b ₂ ) and b ₃ ) of the claims,

5: a basic representation of the invention with entered numbers of the currents and voltage drops in an embodiment according to FIG. 2 of the invention,

6: a diagram for explaining the embodiment according to FIGS. 2 and 5,

Fig. 7: a schematic representation of the currents and

Voltage drops in an arrangement according to FIG. 3,

8: another diagram of the rail resistance as a function of the rail profile,

8a to 8d: different versions of the in

Principle of resistors belonging to the diagram according to FIG. 6,

9: a further embodiment of the invention.

1 shows an arrangement according to the prior art with a rectifier 1 which supplies the direct voltage, two anode rails 2 and a cathode rail 3. As mentioned at the beginning, the anode rails and the cathode rail are outside the bath liquid, while the anodes connected to the anode rails and workpieces connected to the cathode rail are located within the bath liquid. However, to simplify the presentation Anodes A ₁ -A _n and workpieces W ₁ -W _{m are} only indicated in principle in FIGS. 1 and 4. Otherwise, in the drawings, the anodes and the workpieces are symbolically captured or replaced by the sole representation of the anode rails and the cathode rail. The current flow directions in the

Rails and also in the bathroom 4 are indicated schematically. It can be seen that in Fig. 1 the current feeds 5 in the anode rails and the current outlet 6 from the cathode rail are on the same side of the bath. For the reasons explained at the outset, which can be demonstrated mathematically, the voltage drops occurring along the rails 2, 3 cause unequal voltages on the individual cells which contain the workpieces W which are only indicated schematically. Corresponding to the different cell voltages, different cell currents (partial currents) and thus differences in the layer thicknesses on the goods (workpieces) W arise. Similar disadvantages resulted in a version according to the prior art, which is no longer shown separately, in the case of the rectifier voltage source 1 was fed into the anode rails and cathode rail on both sides.

The invention is initially shown, again schematically, with reference to FIGS. 2 and 3. 4 gives a basic illustration of the voltage relationships.

According to FIGS. 2 and 3, the current is fed into the ends of the anode rails 2 from a respective right-hand side 4 ′ of the bath 4 from the direct current source 1

(Section 8). It then flows according to Para. 9 from the anode rails 2 through the bath to the cathode rail 3 and emerges from this on a side 4 "of the bath (see item 10), which is opposite to the feed 8 of the anode currents. In other words: the current entry ends of the anode rails and the current exit end the cathode rail are opposite to each other. In the exemplary embodiment in FIG. 2, the respective cross section of the rails 2 and 3 is shown hatched.

It follows from this that the cross section Q _{K of} the cathode rail 3 is larger than the respective cross section Q. of each of the anode rails 2. The ratio Q _K : Q _A should not be less than 1.7: 1, but can, as soon as it is economically justifiable is arbitrarily larger than 1.7: 1. A cross-sectional ratio of 2: 1 has been found to be particularly advantageous. For this purpose, the diagram according to FIG. 6 shows in an example that the relative uniformity, which will be explained in more detail below, is the most favorable in the cross-sectional ratio of Q _K : Q _A = 2: 1 and below it will soon assume a very bad value, but above that it will still have acceptable values maintains, as the curve shown shows in the further course of the abscissa.

In the example of FIG. 3, the circuit arrangement is the same as in the example of FIG. 2. The difference is that the cross section of the anode rails 2 decreases from the feed points 8 in the further course of the current flow direction 12, i.e. the specific electrical resistance of the cross section of the anode rails increases in the direction 12. The arrangement on the cathode rail 3 is such that the cross sections of this rail increase in the direction of current flow 13, i.e. the specific electrical resistance of the cross-sections decreases in the direction 13, this idea of the invention is not limited to the step-like change of the cross-sections of the rails 2, 3 shown in FIG. 3, as is explained in more detail below from FIGS. 8 to 8d and their explanation will emerge.

Fig. 4 shows schematically the anode rails 2 and

Cathode rail 3 with the current feeds 8, the current outlet 10 and the anodes A ₁ to A _n , and the workpieces

W ₁ to W _m The letters "n" and "m" are deliberately chosen differently, since the number of anodes does not match the Number of workpieces must match. The corresponding voltage _drops at the anodes are denoted by ΔU _1V to ΔU _nV or ΔU _1R to Δ U _nR . The voltage drops on the cathode rail from workpiece to workpiece have the numbers ΔU ₁ to ΔU _m . The tensions in the bathroom at everyone

_{Cells are} named U _z1V to U _zmV or U _z1R to U _zmR .

This arrangement corresponds to the circuit or current feed and feed according to the preamble and feature a) of the claims, but the configurations according to features b ₁ ), b ₂ ) and b ₃ ) have not yet been taken into account. A theoretical calculation of the arrangement according to FIG. 4 now shows that there is already partial compensation of voltage drop-related errors, but there is still no satisfactory compensation. Since only the differences in the cell voltages required for electroplating are to be considered here, all voltage drops ΔU _m before the first item on the are eliminated

Cathode rail (point A) and ΔU _1V or ΔU _1R after the first anode on the anode rail (point B). The effective bath voltage U _{Bad V} for the front V and the back R of the goods is thus between point A and point B. Each of the four current paths drawn from A to B in FIG. 4 has different voltage drops on the rails. The sum of the voltage drops of each current path plus the associated cell voltage

U _z is the same for the distance A to B to be considered. By definition, it is U _{Bad V} for the front of the goods and U _{Bad R} for the back. Mathematically, this is expressed as follows

U _zmV = U _{Bad V} - Δ Δ _2V - Δ U _3V - Δ U _n V;

U _z3V = U _{Bad V} - Δ U _2V - Δ U _3V - Δ U ₃ ;

U _z 1V = U _{Bad V} -Δ U ₁ - Δ U ₂ - Δ U ₃ ;

Δ U _nV <Δ U ₃ and

Δ U _3V ≈ Δ U ₂ (symmetrical special case) and

Δ U _2V > Δ U ₁ from this follows: U _zmV ≠ U _z3V ≠ U _z1V ;

This is to be demonstrated with a numerical example using the voltages entered in FIG. 5. With ^U Bad = 1.4 volts the following equations result:

^U Bad = 1.4 V = U _z1V + 285 mV;

1.4 V = 95 mV + U _z2V + 266 mV;

1.4 V = 171 mV + U _{z 3 V} + 228 mV;

1.4 V = 228 mV + U _z4V + 171 mV;

1.4 V = 266 mV + U _z5V + 95 mV;

1.4 V = 285 mV + U _z6 ; thus U _z1V = 1.4 V - 0.285 V = 1.115 V = U _{z max}

U _z2V = 1.4 V - 0.361 V = 1.039 V

U _z3V = 1.4 V - 0.399 V = 1.001 V = U _{z min}

U _z4V = 1.4 V - 0.399 V = 1.001 V

U _z5V = 1.4 V - 0.361 V = 1.039 V

U _z6V = 1.4 V - 0.285 V = 1.115 V _i.e. U _z1V ≠ U _z2V ≠ U _z3V

U _z4V ≠ U _z5V ≠ U _z6V ;

U _z1V = U _z6V

U _z2V = U _{z 5 V}

U _z3V = U _z4V

The same applies to the cell voltages on the back of the goods:

5 now shows the cross-sectional ratio of the

Cathode rail to the anode rails according to FIGS. 2 and

Feature b ..) of the claim schematically (without the individual power leads) the anode rails 2 and the cathodes rail 3 with the current feeds 8 of the anode currents I. on the right bath side and the current outlet 10 of the cathode rail current I _K on the left bath side. A ratio of Q _K : Q _A of 2: 1 is assumed. The respective currents and voltage drops are entered in their numbers using an example calculated with simplifications that are permissible in the first approximation. 14 are the amounts of voltage drops on an anode bar and 15 are the amounts of voltage drops on the cathode bar.

The comparison variable is used to assess the effectiveness of the various rail arrangements introduced. The value is calculated from the maximum difference in cell voltages in relation to the minimum cell voltage. Q is the relative unevenness. In the case of one-sided feeding according to the prior art (FIG. 1), for example with the preferably stainless steel rails each having the same cross section, ie the cross section Q _{K of} the cathode rail is equal to the cross section Q _{A of} each of the anode rails, a value for

With the same parameters but with the feature b1, the cross-sectional ratio Q _K : Q _{A of} the rails being equal to 2: 1 and reduced with the opposite feed according to FIG. 2 as calculated below to 11.4%.

With this embodiment of the invention, one is already at the ideal value of came much closer than was possible with the prior art. 6 shows in the above context a diagram for the latter example, the ordinate being the unevenness represents according to the above formula. The cross-sectional ratio Q _K : Q _{A is} plotted on the abscissa. The curve shows that with a cross-sectional ratio Q _K : Q _A of 2: 1 the ideal value of

sets that, but also above this value of the curve profile 16 acceptable values of are present, while the other curve branch takes an unfavorable course at values of approximately 1.7: 1 and below.

7 shows a representation similar to that in FIG. 5 of the voltage drops and currents of a numerical example in an embodiment of the arrangement according to FIGS. 2 and 3. That is, the cross-sectional ratio Q _K : Q _A = 2: 1 is selected (FIG 2), as well as a change in the resistance values of the rails in their longitudinal direction according to FIG. 3.

With U _Bad = 1.4V the following equations result:

U _Bad = 1.4V = U _z1V + 400mV

1.4V = 95mV + U _z2V 304mV

1.4V = 171mV + U _z3V + 228mV

1.4v = 228mV + U _z4V + 171mV

1.4V = 304mV + U _z5V + 95mV

1.4V = 400mV + U _z6V ; in order to

U _z1V = 1.4V - 0.400V = 1,000V = U _{z min}

U _z2V = 1.4V - 0.399V = 1.001V = Z _{z max}

U _z3V = 1.4V - 0.399V = 1.001V

U _z4V = 1.4V - 0.399V = 1.001V

U _z5V = 1.4V - 0.399V = 1.001V

U _z6V = 1.4V - 0.400V = 1,000V this means:

U _zlV ≈ U _z2V ≈ U _z3V ≈ U _z4V ≈ U _z5V ≈ U _z6V;

The same applies to the cell voltages on the back of the goods.

The relative unevenness is

7 shows that the combination of the cross-sectional ratios of the rails according to FIG. 2 with the change in resistance in the course of the rails according to FIG. 3 and this in conjunction with the illustrated current directions or current feeds and current outlets according to number a of the claims results in an optimal adjustment of the cell voltages .

Furthermore, the above explanations show that already at

Use of the features of claim 1 or that of claim 2 each result in significantly better values compared to the prior art, since in both cases the voltage drops .DELTA.U on the anode rails and the cathode rail are changed in a defined manner compared to the prior art with the result of an approximation the amounts of all cell _voltages U _z1V to U _zmV , and

U _z1R to U _zmR . Even if the ideal case of such an approximation is the value of the relative unevenness

as stated, the invention also includes arrangements with deviating values, e.g. was exemplified with reference to FIGS. 2 and 5. There is also a significant improvement in value

if you take the example of Figures 3 and 7 for yourself (Claim 2). This happens because the change in resistance on the anode rails causes an increase in the voltage drops at the rail ends remote from the infeed, which are on the left in the drawings, while on the cathode rail results in an increase in the voltage drop at the outlet-side rail end, which is located on the right in the drawings . This results from the increase in the rail resistance in the specified ranges. 8 shows a basic diagram of the change in the rail resistance R in the course of this

Rail length L, the direction of the abscissa resulting from the above explanations for FIGS. 3 and 7 and in particular from the schematic resistance representation in FIG. 3.

As already mentioned, the anode rails 2 and the cathode rail 3 can be made of a stainless steel, e.g. a V2A steel. In this case, it is recommended that the part of the system which carries out the respective contacting with the anode rail has a contact surface made of the same stainless steel, or is made overall of the same stainless steel.

8a to 8d in practice contain possible and advantageous embodiments of the design of the rails 2, 3 to achieve the different resistance values explained over the rail length. 8a shows that the rail is provided with a larger number of bores or other recesses 16 in the area of high resistance than in sections of lower resistance. FIG. 8b shows a rail which changes continuously in cross-section in its longitudinal direction, while FIGS. 8c and 8d show rail designs whose specific resistance value decreases in a stepped manner in the longitudinal direction of the rail (17). 8c is a rail which is in one piece and FIG. 8d shows a rail composed of corresponding slats 18, 19. Especially the execution 8a are characterized by high mechanical stability. The sandwich construction according to FIG. 8d can advantageously be designed in such a way that the longest, lower layer or lamella 18 in the drawing consists of a mechanically very strong stainless steel, while the shorter layers or lamellas 19 above are made of copper, ie made of a material with very high conductivity. It can also be seen that by changing the design of the aforementioned rail examples according to FIGS. 8a to 8d, the respectively desired resistance curve (resistance curve over rail length) according to FIG. 8 can be achieved.

9 shows in a detailed representation only one of the rails 2 and 3 with feed lines 20 to the workpieces 7 and the anodes A1 to A _n . Ohmic resistors R1, R2, R3, etc. are provided in the course of these supply lines

Resistance values are relatively small, so that voltage drops occur at them with the currents that occur, which are only in the millivolt range. These resistors are chosen so that, taking into account the voltage drops in the anode rails, the cathode rail and on the anodes and workpieces themselves, the respective cell voltages become equal to one another, or at least reach values that come very close to one another. Through targeted changes to these resistors R1, etc., one can achieve the desired change in cell voltages in the sense of their approximation, but due to the very low resistance values, no significant power losses have to be accepted.

As already mentioned, an arrangement according to FIG. 9, which corresponds to feature b ₃ ) of claim 3, can also be used with the

Features b ₁ ) (FIGS. 2 and 5) and / or b ₂ ) (FIGS. 3 and 7) can be combined, but with the basic arrangement according to

Fig. 4 (preamble and feature a of the claims) is retained. If the desired approximation or equalization of the values of the cell voltages is achieved, it is within the scope of the invention to overcompensate for the voltage drop-related errors explained in relation to the prior art even within the aforementioned limits.

Claims

Claims:

Arrangement in a system serving for the electrolytic treatment of workpieces, the bath of which has two anode rails, each with a row in its

Anodes arranged one behind the other in the longitudinal direction are electrically connected, furthermore a cathode rail is provided which is electrically connected to workpieces arranged one behind the other in their longitudinal direction and to be treated electrolytically, and furthermore measures with the aim of making the

Layer thickness distribution on the workpieces of the individual cells of such a bath are provided, characterized by the combination of the following features: a) a connection of the anode rails (2) and the cathode rail (3) to the direct current source (1) in such a way that the feeds (8) the currents (I _A ) in the two anode rails (2) on the same side (4 ') of the bath (4), so that these currents in the anode rails are rectified and each exit into the bath (9), that the current feed into the Cathode rail (3) from the bath happens and the current outlet (10) from the cathode rail on the side (4 ") of the bath, which is opposite to the first-mentioned side (4 ') of the anode current feeds (8), and bl) that the cross sections (Q.) of each of the anode rails (2) are the same and that Cross section (Q _K ) of the cathode rail (3) to the cross section (Q _A ) of each of the anode rails behaves at least as 1.7: 1.0 or greater.

2. Arrangement in a system serving for the electrolytic treatment of workpieces, the bath of which has two anode rails, each with a row in its

Layer thickness distribution on the workpieces of the individual cells of such a bath are provided, characterized by the combination of the following features: a) a connection of the anode rails (2) and

Cathode rail (3) to the direct current source (1) such that the feeds (8) of the currents (I _A ) into the two anode rails (2) on the same side (4 ') of the bath (4), so that this

Currents in the anode rails are mutually rectified and each exit into the bath (9), that the current feed into the cathode rail (3) from the bath occurs and the current exit (10) from the cathode rail takes place on the side (4 ") of the bath , the opposite to the first-mentioned side (4 ') of the anode current feeds (8) lies and b2) that the ohmic resistance per unit length of the

Anode rails (2) increase in direction (12) of the current feed (8) and the ohmic resistance per unit length of the cathode rail (3) decreases in direction (13) of the current outlet (10).

3. Arrangement in a system used for the electrolytic treatment of workpieces, the bath has two anode rails, each with a row in their

Layer thickness distribution on the workpieces of the individual cells of such a bath are provided, characterized by the combination of the following features: a) a connection of the anode rails 2 and

Cathode rail (3) to the direct current source (1) such that the feeds (8) of the currents (I _A ) into the two anode rails (2) on the same side (4 ') of the bath (4), so that these currents in the Anode rails are aligned with each other and each exit into the bathroom (9), that the current is fed into the cathode rail (3) from the bathroom and the current outlet (10) from the cathode rail takes place on the side (4 ") of the bath that leads to the former Side (4 ') of the anode current feeds (8) is opposite and b3) that between the respective anode rail (2)

and the anodes (A ₁ -A _n ) ohmic resistors (R1-Rn) electrically connected to them are installed with such a resistance value that approximately the same cell voltage is applied to each cell when the values of the currents flowing through the anodes are matched.

4. Arrangement according to claim 1 and 2, characterized by the combination of the feature groups a, b ₁ ) and b ₂ ).

5. Arrangement according to claims 1 and 3, characterized by the combination of the feature groups a, b ₁ ) and b ₃ ).

6. Arrangement according to claim 2 and 3, characterized by the combination of the feature groups a, b ₂ ) and b ₃ ).

7. Arrangement according to one of claims 1 to 3, characterized by the combination of the feature groups a, b ₁ ), bp) and b ₃ ).

8. Arrangement according to one of claims 1, 4, 5 and 7, characterized in that the ratio of the cathode rail cross section (Q _K ) to the cross section (Q _A ) of each of the anode rails is 2: 1.

9. Arrangement according to one of claims 2, 4, 6 to 8, characterized in that the cross section of the anode rails (2) is reduced in the direction (12) of the current feed (8) through differently sized recesses, such as bores.

10. Arrangement according to one of claims 2, 4, 6 to 8, characterized in that the cross section of the cathodes rail (3) increases in the direction (13) of the current outlet (10) through recesses of different sizes, such as bores.

11. Arrangement according to one of claims 2, 4, 6 to 8, characterized in that the cross section of the respective rail (2, 3) decreases or increases in the direction indicated in steps (17).

12. The arrangement according to claim 11, characterized in that the number and position of the steps corresponds to the number and position of the anodes.

13. Arrangement according to claim 11 or 12, characterized in that the gradations (17) by individual layers or layers (18, 19) are achieved, which together form the rail.

14. Arrangement according to claim 13, characterized in that the longest layer (18) from a mechanically fixed

Stainless steel is made, while the other, by contrast, shorter layers or layers (19) are made of an electrically highly conductive material, such as copper.