KR20120028936A - Method and device for the electrolytic treatment of high resistant layers - Google Patents

Abstract

The present invention relates to a method and apparatus for electroplating and electroetching plate-like or strip-like material (1) in a continuous installation or bath facility with rotational conveying and contacting means (2) along a conveyor belt. According to the prior art, an electrolytic current is supplied from the edge of the material 1 or from both edges. One-sided feed causes undesirable layer thickness distribution. In the case of a two-sided feed, one format of material is produced only at right angles to the conveying direction. According to the present invention, at the center, i.e., in the useful zone, current can be supplied to the material 10 to obtain a layer thickness distribution that is as good or better as when the current is supplied from both edges. In the present invention, materials having a width of any format can be electrolytically processed in any order while contouring.

Description

Method and apparatus for electrolytic treatment of high resistance layer {METHOD AND DEVICE FOR THE ELECTROLYTIC TREATMENT OF HIGH RESISTANT LAYERS}

FIELD OF THE INVENTION The present invention relates to electrolytic treatment, and in particular, to electroplating and etching of electrically conductive layers on planar materials. The invention particularly relates to substrates, such as printed circuit boards and conductive foils, in part in continuously operating plants, and strips of metal or metallized composite films in plants for transferring material from one roll to the next. It is particularly suitable for electroplating. Here, although the base layer is very thin and thus has high resistance, it is intended to apply as high a current density as possible to deposit or etch a layer of metal of uniform thickness over the entire limit of the material surface.

It is an object of the present invention to describe the performance of electrical contact of planar materials for electroplating or electrolytic etching in a continuously operating plant and in a plant for processing material from one roll to the next. In particular, the rotating (contacting of the material) electrical contact means will also be suitable for materials of different sizes in the direction transverse to the conveying direction, with a thin base layer, for uniform electrolytic treatment. In this case, a high level of complexity in the plant can be avoided by comparison with the prior art.

This object is achieved by a method according to claim 1 and an apparatus according to claim 7. Dependent claims describe preferred embodiments of the invention.

Continuous operation plants or plants that produce material passing from one roll to the next are suitable for the production of mass production products, since there is little flexibility with respect to the process sequence. This product is called the final product as described above. For example, small printed circuit boards or conductive foils for ball grid arrays (BGA), Radio Frequency Identification Units (RFID), MP3 players, memory sticks, or for relatively large printed circuit boards such as mobile phones, PCs, etc. Are intended. On the one hand, the present invention takes advantage of this miniaturization tendency of the electronic end product to optimize the layout of the material, and on the other hand, supports the precision conductor technology required for miniaturization as a result of planar electroplating of the required thin base layer. In a continuous operating plant and, if appropriate, in another further plant, after completion, the final product is separated from the material for its use.

The material to be treated is in this case a large-scale printed circuit board or conductive foil. In practice, such large scale printed circuit boards or conductive foils are also called panels. Such panels include useful zones and non-use zones. The final product is located in the region to be used. In contrast, the edge zones in which the contact tracks are placed are generally not used for the final product. In the layout of a printed circuit board, a large amount of the same end product is arranged in the area to be used. There are many ways to arrange many end products on a printed circuit board or panel. The present invention takes advantage of this. The present invention takes as a starting point that the final product is arranged on the panel so that the contact track is formed on the material and maintained approximately or precisely in the center when viewed in the direction transverse to the conveying direction. Likewise, the electrical contact (rotational type) on each of the several contact rolls or contact wheels arranged along the conveying path, approximately or precisely in the center of the conveying track of the continuous operation plant or strip plant, so as to traverse when viewed in the conveying direction. Preferred), such a conveying path may equally be a conveying roll, conveying wheel or conveying means.

The present invention is described using electroplating of a printed circuit board, for example, to construct a conductor pattern constructed using a resistor, and to provide an unblocked contact by metallizing the entire surface. However, the present invention is also suitable without limitation for electrolytic etching and other electrolytic treatments.

According to the invention, using a central contact track, the electrical or electrolytic current required for electroplating is supplied to the material. In this case, the influence on the distribution of the layer thickness in the transverse direction as viewed in the conveying direction is as good as in the prior art with an optimally uniform supply from the two edges, or better than the prior art. However, the two inclined planes formed according to the invention face in opposite directions. The maximum layer thickness is achieved in the contact zone, ie in the center of the material. The layer thickness difference of the plane inclined to cross when viewed in the conveying direction is only about one quarter of the difference achieved when the electroplating current is supplied from only one edge, regardless of the effective contact resistance at any given moment.

The electrical contact formation in the central region of the material (ie useful zone) has the following substantial advantages over the prior art.

The present invention is suitable for different sizes of materials so that they can cross in the direction of transport without the need for re-tooling of the plant. For this reason, materials of different sizes and different layouts can be introduced into the plant and electroplated in any desired order.

Since the inclined plane is inclined from the center towards the two edges, the bone effect at this edge is not broken and in some cases has a useful effect. The thin layer at the edges is made thick by "bone formation" which is laid down by deposition, so that the difference in layer thickness from the edge towards the center is less than when fed from both edges as in the prior art. Much smaller.

-The feed and contact rolls only need one contact. This means that technical complexity is reduced.

Electrolytic currents are always reproducibly established throughout the material, starting from the center stack, giving partial sizes in the two far edge directions. For this reason, one quarter of the size of the inclined plane described above is always kept precise even when uncontrollable transfer resistances appear at the contacts.

Only one contact track is required on the material. That is, there is less loss of useful zone than when fed from both edges, resulting in a better or even better distribution of layer thickness.

The size of the useful zone can be precisely adapted to the size of the arranged final product, as a result of which an unnecessarily large amount of waste-base material can be avoided.

The current density can be selected individually according to the requirements.

Even in the case of demetallization of the sometimes inadequate rotary contact means, which will carry the board away from the track, it is impossible to realize different diameters on both sides,

For unpredictable reasons, even if the board leaves the track, the above-mentioned defects that require unplanned management of the plant will not occur. When leaving the track, electrical contact with the printed circuit board is maintained. Thus, unreliably large metallization or damage to the contacts cannot occur. In the worst case, on one side, next to the contact tracks, the amount of final product of the printed circuit board to be arranged will be divided.

If reliable electrical contacts are implemented, it is possible to prevent damage to the surface of the material on which the contact poles are located. In this case, placing the contact track on the material and setting its position in relation to the rotating contact is of little importance, since the contact can enter the zone of the final product.

The width of the contact track can be chosen smaller than in the prior art, since no safety edge is needed, which means that the useful zone of the material is made larger.

In particular, in the case of small end products, contact tracks can be completely unnecessary with separate areas on the material. The contact track extends in the central zone of the material over a portion of the final product, which is subjected to a sorting operation and rejected. In this very preferred method, the alignment station which has always been located upstream of the electroplating plant can be unnecessary. Especially for thin and flexible materials, this kind of alignment station is very complicated. In this case, according to the invention, the material is led through a continuous operating plant that is not transversely aligned. Similarly, unaligned material transfer is already carried out in a known manner in wet-chemical processing stations and washing stations, located upstream and downstream of the electroplating plant.

The format of the material may be different from conventional rectangular shapes. For example, it may be triangular, circular, or elliptical.

As an extension to the invention, it is also possible to supply an electroplating current in the useful zone of the material using a plurality of contact tracks which are offset transversely when viewed in the transport direction. Even when there are two contact tracks in the useful zone, the local difference in cell voltage can be reduced to 1/16 as compared to the one-side supply according to the prior art.

The invention will be further described below with reference to FIGS. 1 to 3 which are not drawn to scale.
1a is a cross-sectional view of a continuous operating plant or strip plant according to the prior art.
FIG. 1B is an enlarged view of a layer thickness profile that can be achieved with a configuration different from that of FIG. 1A. FIG.
2a is a cross-sectional view of a continuous operating plant or strip plant according to the invention.
2b is an enlarged view of a layer thickness profile that can be achieved according to the invention when viewed in a direction transverse to the conveying direction;
3 is a plan view of a material in which a large amount of the final product is arranged;

In FIG. 1A, the material 1 is transported vertically outward from the plane of the drawing. To this end, upper and lower conveying and contacting means 2 which are rotationally driven are configured. On the elongate contact means 2, at both ends, an annular or disc-shaped electrical contact 3 is arranged. These contacts 3 are rolled on the upper part and the lower part of the material 1 on the base layer 4. During this time, the material 1 is transported and at the same time electrical contact is made. Electrical contact is made in the two edge zones 5 of the material. On the upper and lower sides there is a soluble or insoluble anode 6. With their respective anodes 6, the base layer 4, ie the surface of the material 1, forms its own electrolytic cell located in the electrolyte 7. In each case, at least one electroplating current source 8 in the form of a direct current source or a monopole / bipolar pulse current source functions to supply current to the electrolytic cell. The current is transmitted from there to the contact 3 using the rotary contact 9 or the sliding contact 9 with respect to the rotary feeder and the contact means 2. The width of the material 1 in the direction transverse to the conveying direction should be sized so that each contact 3 can roll on a sufficiently wide contact track at the edge of the material 1. For this reason, only very specific widths of material 1 can be handled in existing plants according to the prior art.

FIG. 1B shows the profile of the layer thickness on the material 1 in the direction transverse to the conveying direction, as a result from the configuration according to FIG. 1A. Profiles of inclined planes, shown on a very large scale, are common. The minimum layer thickness of the electroplated layer 10 appears in the zone of the center of the material 1. The effective cell voltage between the cathode surface of the material 1 and the anode 6 is the smallest in this zone because of the voltage drop in the base layer 4. Thus, the local current density, and hence the layer thickness deposited, is here also the smallest. In this configuration, the following dependent relationship exists as a result. The difference in the amount deposited between the edge zone 5 and the center of the material is that when the base layer to be electroplated has a high resistance, when the width of the material is large in the direction crossing the conveying direction, and a high current density is applied to the electroplating, When used, increases.

A so-called deposition bone formation 11 is added to the profile of the inclined plane at the already high edge of the material 1, which effect is particularly strong because of the electrical edge effect in the zone of the highest local current density. This increases the difference in overall deposition on the material in a very undesirable way. In particular, in the case of the above-mentioned mass production products produced by precision conductor technology, in particular, the distribution of the layer thicknesses must be very uniform, which according to the prior art can only be achieved using low current densities.

2a is a cross-sectional view of a continuous operating plant or strip plant according to the invention for electroplating board-shaped or strip-shaped material 1. In this plant, a number of conveying and contacting means 2 for conveying the material 1 and making electrical contact are arranged along the conveying path. The roll which functions as the conveying means 2 is shown. Non-rotating sliding contacts, or rotating rolls with small wheels, may be used. In the basic construction of the invention, the electrical contact 3, which takes the form of a ring, a small wheel, a disk, a brush, or a segmented contact wheel, is positioned to traverse when viewed in the conveying direction, the center of the contact means 2 and the conveying path. It is preferable to be located at. This configuration requires only one corresponding contact track 15 on the material, which also preferably runs from the center of the material 1 inside the useful area 17, as also shown in FIG. 3. This means that the material of each useful part-zone or useful part-region 12 is located on either side of the contact track 15. The electroplating current is supplied to the material using contact tracks 15 on the material, which tracks remain free, individually or not individually in the layout, and continue within the entire useful zone. In the case of the contact tracks 15 which are free and not held separately, this extends over the final product 14 configured in the layout of the material 1.

Asymmetrical contact tracks can also be provided in the corresponding contact 3 along the conveying path of the continuous operating plant and in the layout of the strip or printed circuit board or material to be electroplated.

As a result of the configuration according to the invention in the useful zone, no serious consequences for the plant technique described above are seen, since electrical contact is still made even when the contact 3 unexpectedly leaves the track. Because of this, no safety edge is required, and the width of the contact track 15 can be narrow in the layout of the material 1 (eg 10 mm, the width of the contact wheel 3 is 5 mm). The contacts are always rolled in the useful zone 12 of material. The contact cannot fall from the material and therefore cannot lose the electrical contact. This means that the electrical contacts cannot be broken, among other things, that failure cannot occur in the case of demetallization of the contacts due to the unplanned coarse metallization layer.

In the direction transverse to the conveying direction, the distribution of layer thicknesses which can be achieved according to the invention is shown in FIG. 2B. The trough of the inclined plane is located in the zone away from the contact, ie at the two edges 13 of the material 1. These thin edge zones 13 are contiguous in the lowest current density zone by their respective deposition bone formations 11 and thus in concave in the valleys of the inclined plane. Thus, the present formation appears in the zone of the lowest current density. For this reason, compared with the supply on both sides according to the prior art in which the deposition present formation is in the zone of the highest current density, it is quite small. Thus, overall, the overall difference in layer thickness is smaller than with a feed on both sides according to the prior art. In addition to this, the above-described additional advantages of making electrical contact with the material in the central zone are described.

Other methods of the present invention are well suited to the requirements currently made with such electroplating plants in printed circuit board technology. This requirement includes a copper base layer of at least 1.5 μm thick for a 610 mm wide printed circuit board to which an electroplating layer of thickness up to 25 μm will be applied. In this case, only a difference in layer thickness of at most 1 μm is acceptable in the zone of the useful area. These requirements can be met according to the invention.

For example, in the case of a chemically-differentiated copper layer or sputtered base layer with a thickness of 0.2 μm, it helps to extend the inventive concept because of the substantially high resistance. For this purpose, it is proposed that at least two contact tracks are provided in the layout of the material and two contact tracks or contacts 3 are provided on the contact means 2. These two contact tracks are located within the useful zone of the material, approximately 1/4 and 3/4 of the width, in a direction transverse to the transverse direction when viewed in the transport direction, in approximately symmetry with respect to the transport path. Here, a total of four small inclined planes are formed on the upper side of the material and, where appropriate, also on the lower side of the material. In this case, one quarter of the total current in this contact zone flows from each contact in each of the two directions in the direction transverse to that seen in the feed direction. At the same time, the length of the current flow in the base layer of the printed circuit board is reduced to one quarter of the total width, making the electrical resistance magnitude of the associated current path one quarter. A quarter of the current flowing through the 1/4 resistor causes a voltage drop of only 1/16 by Ohm's law. The layer thickness difference on the material is reduced at about this ratio by comparison with the current supply from one side according to the prior art. In other words, the inclined plane valleys are located away from the contact in each case.

The base layer deposited by sputtering is particularly thin in the edge zone of the material, or completely free of metal coating. This is true of so-called etched-back full-surface printed circuit boards. In this case, for example, a base layer about 12 μm to 17 μm thick is etched back to about 3 μm. After that, the actual processing of the printed circuit board is performed. In particular, because of the puddling effect, the edge zone is more strongly etched than the center zone. In all such cases, it is proved to be very advantageous to supply the electrolytic current to the material center or to a plurality of tracks in the center zone according to the invention, since the nominal layer thickness for the base layer is always dominant and thus This is because reliable current supply is possible. It is preferred that a plurality of contact wheels arranged transversely when viewed in the transport direction are arranged symmetrically with respect to the transport path. With one or more contact tracks 15, when the material supply is at the center, no edge of the material is required for the contact. In this case, however, the layout of the material and the position of the contact on the contact means must be adjusted to each other. In the case where a plurality of tracks are arranged to traverse when viewed in the conveying direction, there is no complete freedom in the selection of the parameters, as provided by a single feed in the center. When using some mass-produced products produced over long periods of time, this extension according to the invention is very advantageous, especially in the electroplating of very thin, so resistive base layers onto large materials using high current densities. This is because there are no economic alternatives with comparable simplicity, that is, there are no economic alternatives that electroplat in an economical manner with very good distribution of layer thicknesses.

For example, if two contact tracks 15 are present, it is possible to place two contacts 3 on one contact means 2 there. For this purpose, when one or more individual rectifiers are correlated with each contact track, two sliding or rotary contacts 9 are required, which flow in exactly the same magnitude on all sides so as to traverse when viewed in the feed direction. This can be guaranteed to exist. However, it is also possible to have only one contacting part 3 and one rotating contacting part 9 in each contacting means 2. In this case, these contacts 3 are alternately arranged on the right and left sides of the contact means 2 when viewed in the direction of conveying the material 1. With this inexpensive solution, the contact 3 must carry twice the current, whether or not both sides are supplied by one rectifier or by an individual rectifier.

In particular, in the case of high current densities, the magnitude of the current to each contact also increases. In this case, it is important that the electrolytic treatment currents of the common rectifiers are evenly distributed over all associated contacts, respectively, to prevent damage to the surface of the material and / or the contacts. This is particularly important when the contact track of the useful zone extends over the final product. As the number of contacts correlated with the rectifier 8 decreases, the likelihood of overloading individual contacts also decreases. In the best case, there is a rectifier 8 each associated with each individual contact. The current-regulating rectifier limits the processing current to a preset current. This can reliably prevent overload of the contact.

3 is a plan view of a material 1 having a layout configured for electroplating a large amount of the final product 14 in a continuous operation plant or strip plant according to the invention. The external size of this material is, for example, 610 mm x 610 mm. The useful zone 17 edged by the double dashed line in which the final product and the at least one contact track 15 are located is as small as the size of the narrow edge zone 13. The conveying direction arrow 16 indicates the conveying direction of the material passing through the electroplating plant. The material may also include blind holes provided with an electrically conductive layer and through holes for electroplating.

For example, the useful zone for the final product 14, such as BGA, is smaller (e.g., 580 mm x 580 mm). Edge 13 is not available for end product 14. At or near the center of the material 1, the contact tracks 15 lead freely into individual shapes. This track is generally not available for the final product 14 and is available for limited use only. However, especially in the case of the small end product 14, the final product may cover the entire useful area of the layout without leaving any contact tracks on the material as separate areas. Electrical contacts are made in the central zone of the material 1 together with the final product 14. If such relatively small end products fail due to the contacts, they can be separated and discarded in the sorting operation. This process simplifies the structure of the layout of the material 1. In addition, the course of the actual contact track on the material during electroplating is not important in any way. With a small end product, the yield per panel is approximately the same in both cases, that is to say approximately the same with and without contact tracks in separate areas. In this case, there is no need for a technically complex alignment station upstream of the continuous operating plant required for precise lateral alignment of the material.

The invention is also suitable for electroplating structures formed by structural resists on materials. In this case, the contact track must be free of resistance, just like other areas to be electroplated.

The format of the material according to the invention is not limited to the rectangular form. It is also possible to have polygonal or rounded contours. In certain cases, this can result in savings in the base material.

1 substance, printed circuit board, panel
2 contact means, conveying means
3 contacts, contact ring, contact wheel, contact roll
4 base layer
5 edge zone
6 anodes, electrode
7 electrolyte
8 Electrolytic Current Source, Rectifier
9 Rotary contacts, sliding contacts
10 Electroplated Layer, Etched Layer
11 Deposition Pattern Formation
12 useful part-areas, useful part-zones
13 edges, edge area
14 final products
15 contact tracks
16 Feed direction arrow
17 useful areas

Claims (9)

In the method of electroplating or electrolytic etching of strip- or plate-shaped material 1 in a strip plant or continuous operation plant for transferring the material from one roll to the next, with the conveying and contacting means 2 along the conveying path,
The material is supplied with an electrolytic current to the material by means of a contact 3 on the conveying and contacting means 2 using at least one contact track 15 running inside the useful area 17 of the material 1. doing
A method of electroplating or electrolytic etching of strip or plate-like material (1) in a strip plant or continuous operation plant. The method of claim 1,
An electrical contact is constructed, in which electrolytic current is supplied to the material in a direction crossing the conveying direction in the center zone.
A method of electroplating or electrolytic etching of strip or plate-like material (1) in a strip plant or continuous operation plant. The method according to claim 1 or 2,
The material 1 having different contours or different dimensions, in any order in a continuous operation plant, results in an electrical contact made using at least one conductive track 15 inside the useful area 17. Provided by
A method of electroplating or electrolytic etching of strip or plate-like material (1) in a strip plant or continuous operation plant. The method according to any one of claims 1 to 3,
Using structural electroplating or structural etching, electrolytic current is supplied through at least one resistive contact track 15.
A method of electroplating or electrolytic etching of strip or plate-like material (1) in a strip plant or continuous operation plant. The method according to any one of claims 1 to 4,
The electrolytic current is at least one contact track that remains freely through at least one contact track 15 extending over the final product 14 of the layout of the material, or within the layout of the final product 14 on the material. Supplied via 15
A method of electroplating or electrolytic etching of strip or plate-like material (1) in a strip plant or continuous operation plant. 6. The method according to any one of claims 1 to 5,
A separate rectifier 8 correlated with each contact 3 supplies electrolytic current to each contact 3, or a common rectifier 8 supplies an electrolytic current to a plurality of contacts 3.
A method of electroplating or electrolytic etching of strip or plate-like material (1) in a strip plant or continuous operation plant. In the electroplating or electrolytic etching apparatus of strip- or plate-like material (1) in a strip plant or continuous operation plant, using the method according to claim 1, having a conveying and contacting means (2) along the conveying path,
Viewed across the conveying direction, at least one contacting portion 3 on each conveying and contacting means 2 and at least one corresponding contact track 15 on the material 1 are provided with Located inside the useful area 17
Electroplating or electrolytic etching of strip or plate material (1) in a strip plant or continuous operation plant. The method of claim 7, wherein
When viewed across the conveying direction, the position of the contact portion 3 on each conveying and contacting means 2 and the position of the corresponding contact track 15 on the material 1 are precisely in the center of the conveying path, Located near or
Electroplating or electrolytic etching of strip or plate material (1) in a strip plant or continuous operation plant. The method according to claim 7 or 8,
An available zone of material 1 for the final product 14 is also located in the zone of the contact track 15.
Electroplating or electrolytic etching of strip or plate material (1) in a strip plant or continuous operation plant.

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