U.S. patent application number 12/297864 was filed with the patent office on 2009-04-23 for electroplating device and method.
Invention is credited to Juergen Kaczun, Rene Lochtman, Juergen Pfister, Gert Pohl, Norbert Schneider, Norbert Wagner.
Application Number | 20090101511 12/297864 |
Document ID | / |
Family ID | 38236519 |
Filed Date | 2009-04-23 |
United States Patent
Application |
20090101511 |
Kind Code |
A1 |
Lochtman; Rene ; et
al. |
April 23, 2009 |
ELECTROPLATING DEVICE AND METHOD
Abstract
The invention relates to a device for the electrolytic coating
of at least one electrically conductive substrate (8) or a
structured or full-surface electrically conductive surface on a
nonconductive substrate (8), which comprises at least one bath, one
anode and one cathode (1), the bath containing an electrolyte
solution containing at least one metal salt, from which metal ions
are deposited on electrically conductive surfaces of the substrate
to form a metal layer while the cathode is brought in contact with
the surface to be coated of the substrate and the substrate is
transported through the bath. The cathode comprises at least one
band (2) having at least one electrically conductive section (12),
which is guided around at least two rotatable shafts (3). The
invention furthermore relates to a method for the electrolytic
coating of at least substrate, which is carried out in a device
according to the invention, the band resting on the substrate for
the coating and being circulated with a circulation speed which
corresponds to the speed with which the substrate is guided through
the bath. Lastly, the invention also relates to a use of the device
according to the invention for the electrolytic coating of
electrically conductive structures on an electrically nonconductive
support.
Inventors: |
Lochtman; Rene; (Mannheim,
DE) ; Kaczun; Juergen; (Wachenheim, DE) ;
Schneider; Norbert; (Altrip, DE) ; Pfister;
Juergen; (Speyer, DE) ; Pohl; Gert;
(Sindelfingen, DE) ; Wagner; Norbert;
(Mutterstadt, DE) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ, LLP
P O BOX 2207
WILMINGTON
DE
19899
US
|
Family ID: |
38236519 |
Appl. No.: |
12/297864 |
Filed: |
April 17, 2007 |
PCT Filed: |
April 17, 2007 |
PCT NO: |
PCT/EP07/53707 |
371 Date: |
October 20, 2008 |
Current U.S.
Class: |
205/137 ;
204/202 |
Current CPC
Class: |
C25D 17/14 20130101;
H05K 3/241 20130101; C25D 5/06 20130101; C25D 17/12 20130101; C25D
5/54 20130101; C25D 7/0621 20130101; C25D 17/005 20130101 |
Class at
Publication: |
205/137 ;
204/202 |
International
Class: |
C25D 17/28 20060101
C25D017/28; C25D 5/00 20060101 C25D005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 18, 2006 |
EP |
06112723.9 |
Claims
1-29. (canceled)
30. A device for the electrolytic coating of an electrically
conductive surface, the device comprising: a bath of an electrolyte
solution containing at least one metal salt; an anode in contact
with the bath; and a cathode comprising at least one band having at
least one electrically conductive section, the at least one band
being guided around at least two rotatable shafts, wherein while
the electrically conductive surface is transported through the bath
and the cathode is brought in contact with the electrically
conductive surface, metal ions from the metal salt are deposited on
the electrically conductive surface.
31. The device as claimed in claim 30, wherein at least one of the
shafts is electrically conductive, and voltage is supplied via the
electrically conductive shafts.
32. The device as claimed in claim 30, wherein at least two of the
bands are arranged offset in series.
33. The device as claimed in claim 32, wherein respectively
successive bands arranged offset are guided via at least one common
shaft.
34. The device as claimed in claim 30, wherein at least one of the
bands is in the form of a network.
35. The device as claimed in claim 34, wherein the band comprises
sections of at least one of different mesh widths, different mesh
shapes, and offset meshes.
36. The device as claimed in claim 30, wherein at least one of the
bands includes a plurality of holes.
37. The device as claimed in claim 34, wherein the band comprises
sections with at least one of differently sized holes, differently
shaped holes, and offset holes.
38. The device as claimed in claim 30, wherein the at least one
band alternately comprises conductive sections and nonconductive
sections.
39. The device as claimed in claim 38, wherein the band is guided
around at least one anodically connected shaft.
40. The device as claimed in claim 39, wherein a length (L) of the
conductive sections is greater than or equal to a distance (h)
between any two cathodically connected shafts and less than a
distance (d) between any cathodically connected shaft and any
neighboring anodically connected shaft.
41. The device as claimed in claim 30, further comprising an
apparatus adapted to rotate the electrically conductive surface,
the apparatus being disposed either inside or outside the bath.
42. The device as claimed in claim 30, the cathode comprising at
least two bands, wherein two of the bands are arranged so that the
substrate is guided between the two bands and the two bands
respectively contact an upper side and a lower side of the
electrically conductive surface.
43. The device as claimed in claim 30, wherein the shafts are
connectable both cathodically and anodically and are adapted to be
raised from the electrically conductive surface and lowered onto
it.
44. The device as claimed in claim 30, wherein the conductive
sections of the at least one band and the shaft surfaces are made
of an electrically conductive material which does not pass into the
bath during operation.
45. The device as claimed in claim 30, the electrically conductive
surface comprising a flexible support which is unwound from a first
roll and wound onto a second roll, and the cathode comprising a
plurality of bands guided around at least two shafts, wherein the
flexible support is passed through the bands in a meandering
fashion.
46. The device as claimed in claim 30, wherein the shafts are
constructed from a plurality of electrically conductive segments
which are respectively separated from one another by nonconductive
segments, the electrically conductive segments being connectable
both cathodically and anodically and the at least one band being
constructed from conductive sections and nonconductive sections and
being positioned on the shafts so that a nonconductive section of
the band rests on a nonconductive segment of the shaft.
47. The device as claimed in claim 30, wherein the electrically
conductive surface comprises a substrate.
48. The device as claimed in claim 30, wherein the electrically
conductive surface comprises at least one of a structured or
full-surface electrically conductive surface on a non-conductive
substrate.
49. A method for the electrolytic coating of an electrically
conductive surface, the method comprising: transporting the
electrically conductive surface through a bath of an electrolyte
solution containing at least one metal salt; placing an anode in
contact with the bath; placing a cathode in contact with the
electrically conductive surface, wherein the cathode comprises at
least one band having at least one electrically conductive section,
the at least one band being guided around at least two rotatable
shafts and being placed in contact with the electrically conductive
surface to deposit metal ions from the metal salt onto the
electrically conductive surface.
50. The method as claimed in claim 49, the at least one band being
circulated with a circulation speed which corresponds to a speed
with which the electrically conductive surface is transported
through the bath.
51. The method as claimed in claim 49, further comprising supplying
the at least one band with voltage via at least one shaft.
52. The method as claimed in claim 49, wherein at least one of the
shafts is connected cathodically, and at least one of the shafts is
connected anodically.
53. The method as claimed in claim 52, further comprising raising
cathodically connected shafts and connecting the cathodically
connected shafts anodically for demetallization.
54. The method as claimed in claim 52, raising cathodically
connected shafts and connecting the cathodically connected shafts
anodically for demetallization, and lowering anodically connected
shafts and connect the anodically connected shafts
cathodically.
55. The method as claimed in claim 52, wherein the at least one
band runs around at least one further shaft which is anodically
connected, the at least one band having alternating conductive and
nonconductive sections, the length of the conductive sections being
less than the distance between any shafts anodically connected and
any shafts cathodically connected, the band contacting the
electrically conductive surface between two cathodically connected
shafts.
56. The method as claimed in claim 49, further comprising
anodically connecting the shafts for demetallization during a
production pause.
57. The method as claimed in claim 49, further comprising
transporting the electrically conductive surface through the bath
multiple times and rotating the electrically conductive surface
through a predetermined angle after each pass.
58. The method as claimed in claim 49, further comprising adjusting
a contact time between the at least one band and the electrically
conductive surface.
59. The method as claimed in claim 58, wherein adjusting the
contact time includes adjusting a transport speed of the
electrically conductive surface through the bath.
Description
[0001] The invention relates to a device for the electrolytic
coating of at least one electrically conductive substrate or a
structured or full-surface electrically conductive surface on a
nonconductive substrate, which comprises at least one bath, one
anode and one cathode, the bath containing an electrolyte solution
containing at least one metal salt, from which metal ions are
deposited on electrically conductive surfaces of the substrate to
form a metal layer.
[0002] The invention furthermore relates to a method for the
electrolytic coating of at least one substrate, which is carried
out in a device designed according to the invention.
[0003] Electrolytic coating methods are used, for example, in order
to coat electrically conductive substrates or structured or
full-surface electrically conductive surfaces on a nonconductive
substrate. For example, these methods can produce conductor tracks
on printed circuit boards, RFID antennas, flat cables, thin metal
foils, conductor tracks on solar cells, and can electrolytically
coat other products such as two- or three-dimensional objects, for
example shaped plastic parts.
[0004] DE-B 103 42 512 discloses a device and a method for the
electrolytic treatment of electrically conductive structures
electrically insulated from one another on surfaces of a
strip-shaped object to be treated. Here, the object to be treated
is transported on a transport path and continuously in a transport
direction, the object to be treated being contacted with a
contacting electrode arranged outside an electrolysis region so
that a negative voltage is applied to the electrically conductive
structures. In the electrolysis region, metal ions from the
treatment liquid then deposit on the electrically conductive
structures to form a metal layer. Since metal is deposited on the
electrically conductive structures only so long as they are
contacted by the contact electrode, it is only possible to coat
structures which are so largely dimensioned that the electrically
conductive structure to be coated lies in the electrolysis region
while being simultaneously contacted outside the electrolysis
region.
[0005] A galvanizing apparatus in which the contacting unit is
arranged in the electrolyte bath is disclosed, for example, in DE-A
102 34 705. The galvanizing apparatus described here is suitable
for coating structures arranged on a strip-shaped support, which
are already conductively formed. The contacting is in this case
carried out via rolls which are in contact with the conductively
formed structures. Since the rolls lie in the electrolyte bath,
metal from the electrolyte bath likewise deposits on them. In order
to be able to remove the metal again, the rolls are constructed
from individual segments which are connected cathodically so long
as they are in contact with the structures to be coated, and
connected anodically when there is no contact between the rolls and
the electrically conductive structure. A disadvantage of this
arrangement, however, is that a voltage is applied only for a short
time on structures which are short as seen in the transport
direction, while a voltage is applied over a substantially longer
period of time on structures which are long, likewise as seen in
the transport direction. The layer which is deposited on long
structures is therefore substantially larger than the layer which
is deposited on short structures.
[0006] A disadvantage of the methods known from the prior art is
that they cannot be used to coat structures which are very
short--especially as seen in the transport direction of the
substrate. Another disadvantage is that many rolls connected in
series are required in order to produce sufficiently long contact
times, so that a very long device is needed.
[0007] It is an object of the invention to provide a device which
ensures a sufficiently long contact time even for short structures,
so that short structures can also be provided with a sufficiently
thick metal layer.
[0008] The object is achieved by a device for the electrolytic
coating of at least one electrically conductive substrate or a
structured or full-surface electrically conductive surface on a
nonconductive substrate, which comprises at least one bath, one
anode and one cathode, the bath containing an electrolyte solution
containing at least one metal salt. From the electrolyte solution,
metal ions are deposited on electrically conductive surfaces of the
substrate to form a metal layer. To this end, the at least one
cathode is brought in contact with the substrate's surface to be
coated while the substrate is transported through the bath.
According to the invention, the cathode comprises at least one band
having at least one electrically conductive section, which is
guided around at least two rotatable shafts. The shafts are
configured with a suitable cross section matched to the respective
substrate. The shafts are preferably designed cylindrically and
may, for example, be provided with grooves in which the at least
one band runs. For electrical contacting of the band, at least one
of the shafts is preferably connected cathodically, the shaft being
configured so that the current is transmitted from the surface of
the shaft to the band. When the shafts are provided with grooves in
which are the at least one band runs, the substrate can be
contacted simultaneously via the shafts and the band. Nevertheless,
it is also possible for only the grooves to be electrically
conductive and for the regions of the shafts between the grooves to
be made of an insulating material, so as to prevent the substrate
from being electrically contacted via the shafts as well. The
current supply of the shafts takes place via sliprings, for
example, although it is also possible to use any other suitable
device with which current can be transmitted to rotating
shafts.
[0009] Since the cathode comprises at least one band having at
least one electrically conductive section, it is possible even for
substrates with short electrically conductive structures,
especially as seen in the transport direction of the substrate, to
be provided with a sufficiently thick coating. This is possible
since owing to the configuration of the cathode as a band,
according to the invention, even short electrically conductive
structures stay in contact with the cathode for a longer time than
is the case in the methods known from the prior art.
[0010] So that is also possible to coat regions of the electrically
conductive structure on which the cathode configured as a band
rests for contacting, in a preferred embodiment at least two bands
are arranged offset in series. The arrangement is preferably such
that the second band, arranged offset behind the first band,
contacts the electrically conductive structure in the region on
which the metal was deposited when contacting with the first band.
In order to achieve a larger thickness of the coating, preferably
more than two bands are connected in series.
[0011] In one embodiment, respectively successive bands arranged
offset are guided via at least one common shaft. When the bands are
respectively guided via two shafts in this case, as seen in the
transport direction of the substrate, the rear shaft of the first
band is simultaneously the front shaft of the second band. The
advantage of this arrangement is that it is possible to economize
on shafts and the bath can be kept shorter. Besides the arrangement
in which respectively successive bands arranged offset are guided
via at least one common shaft, it is also possible to guide the
successively arranged bands via respectively independent shafts. In
such an arrangement, it is advantageous for the shafts to be
configured so that they can be raised from the substrate. During
the coating process, i.e. so long as the shafts and the bands are
connected cathodically, metal also deposits on the bands and the
shafts. In order to remove this metal again, it is necessary to
connect the shafts and the bands anodically. When the bands are
respectively arranged independently on shafts, the respectively
individual bands together with their shafts can be raised from the
substrate and connected anodically, while bands preceding or
following the raised bands simultaneously contact the substrate and
the electrically conductive structures lying on it, so that the
removal of the deposited metal from the bands and shafts can take
place during continuous operation. When the shafts cannot be
raised, or when only one group of bands connected offset in series
is provided, in which respectively successive bands arranged offset
are guided via at least one common shaft, the metal deposited on
the bands and shafts can only be removed during production
pauses.
[0012] In a further embodiment, the at least one band has a network
structure. The advantage of the network structure is that only
small regions of the electrically conductive structures to be
coated on the substrate are respectively covered by the band. The
coating takes place in the holes of the network. So that it is also
possible to coat the electrically conductive structures in the
regions on which the network rests, even for the case in which the
bands are designed in the form of a network structure it is
advantageous to arrange at least two bands respectively offset in
series, It is also possible to connect two bands designed as
networks directly in series, the networks then respectively having
different mesh widths and/or different mesh shapes so that regions
on which the front network rests can also be coated. Furthermore,
it is also possible to provide one band configured as a network,
the band having regions with a different mesh width and/or a
different mesh shape. Bands with individual holes formed in them
are also to be understood as a network in the context of the
present invention.
[0013] The advantage of a band designed in the form of a network is
that the network can extend over the entire width of the shafts. It
is not necessary for a plurality of narrow bands designed in the
form of networks to be arranged next to one another.
[0014] So that electrically conductive structures which are as
small as possible, i.e. even structures less than 500 .mu.m as are
required in printed circuit board fabrication, can also be coated
on the substrate, the width of the individual bands is selected to
be as narrow as possible when they are not designed in the form of
a network. The width of the bands in this case depends on the
fabrication possibilities. The narrower the bands can be formed,
the smaller are the conductive structures which can be coated. An
advantage of narrow bands with a small distance between them is
that the contacting probability of extremely small structures is
therefore greater than with a smaller number of wide bands. Since
the contact surface of the bands impedes the deposition by covering
the structures directly under the band, it is advantageous for this
covering effect to be minimized by narrow bands. At the same time,
the electrolyte throughput over the surfaces to be metallized is
more uniform owing to a multiplicity of smaller surface accesses
than with few surface accesses, as there are with a small number of
wide bands.
[0015] The number of bands arranged next to one another depends on
the width of the substrate. When the substrate to be coated is
wider, commensurately more bands must be arranged next to one
another. Here, care should be taken that a free gap respectively
remains between the bands, in which the metal can be deposited on
the electrically conductive substrate or the structured or
full-surface electrically conductive surface of the substrate. When
respectively at least two bands are arranged offset in series, the
gap between two bands arranged next to each other is preferably as
wide as the band arranged offset behind. Since in the case of a
band configured in the form of a network, the coating takes place
on the substrate's positions exposed by the individual holes of the
network, it is not absolutely necessary here to arrange a plurality
of narrow bands in network form next to one another. In this case,
it may be sufficient to use one band which extends over the entire
width of the substrate.
[0016] In a further embodiment, the at least one band alternately
comprises conductive sections and nonconductive sections. In this
case it is possible for the band to be additionally guided around
at least one anodically connected shaft, although care should be
taken that the length of the conductive sections is less than the
distance between a cathodically connected shaft and a neighboring
anodically connected shaft. In this way, regions of the band which
are in contact with the substrate to be coated are connected
cathodically, and regions of the band which are not in contact with
the substrate are connected anodically. The advantage of this
connection is that metal which deposits on the band during the
cathodic connection of the band is removed again during the anodic
connection. In order to remove all metal which has deposited on the
band while it was connected cathodically, the anodically connected
region is preferably longer than or at least equally long as the
cathodically connected region. This may be achieved on the one hand
in that the anodically connected shaft has a greater diameter than
the cathodically connected shafts, and on the other hand, with an
equal or smaller diameter of the anodically connected shafts, it is
possible to provide at least as many of them as cathodically
connected shafts, the spacing of the cathodically connected shafts
and the spacing of the anodically connected shafts preferably being
of equal size.
[0017] In order to achieve uninterrupted cathodic connection of the
band while it contacts the electrically conductive surfaces of the
substrate with the electrically conductive structures lying on
them, the length of the conductive sections is preferably greater
than or equal to the distance between two neighboring cathodically
connected shafts. Coating then takes place on the electrically
conductive structure of the substrate from the first contact of the
electrically conductive structure with the cathodically connected
section of the band until the time at which the contact of the
cathodically connected section of the band with the electrically
conductive structure on the substrate is ended.
[0018] As bands with alternately conductive and nonconductive
sections, for example, it is possible to use linked bands in which
the individual links are fastened to one another, for example by
brackets. A corresponding number of electrically conductive links
are mounted in succession according to the required length of the
conductive sections. In order to produce an electrically
nonconductive section, at least one nonconductive link is inserted
between two electrically conductive links. Besides the structure as
a linked chain, it is also possible to provide at least one
electrically nonconductive flexible band as a support, which
comprises electrically conductive sections fitted electrically
insulated from one another at predetermined distances. A suitable
conductive material here is, for example, wire or foils which are
wound around the support or else flexible or rigid foils which, for
example, may also be provided in the form of a network or have
holes which are connected to the support. The connection to the
support may, for example, be carried out using adhesives. Besides
the embodiment with a single support per band, for example, it is
also possible to arrange a plurality of supports next to one
another, which are connected together by common conductive
sections. A gap is preferably formed between the individual
supports in this case. Furthermore, it is also possible for the
supports to contain holes or have a structure in the form of a
network.
[0019] When the band has a network structure, for example in which
an electrically conductive network is connected to an electrically
nonconductive network in order to form the electrically conductive
sections and electrically nonconductive sections, the electrically
conductive sections in the form of a network may be connected to
the meshes of a nonconductive section, for example with the aid of
a wire which is guided through the individual meshes of the network
structure.
[0020] Besides the embodiments described here, the band may
nevertheless also have any other structure by which conductive and
nonconductive sections can be produced in alternation.
[0021] In a further embodiment, the electrolytic coating device
furthermore comprises a device with which the substrate can be
rotated. The rotation axis of the device, with which the substrate
can be rotated, is arranged perpendicularly to the substrate's
surface to be coated when electrically conductive structures which
are initially wide and short as seen in the transport direction of
the substrate are intended to be aligned by the rotation so that
they are narrow and long as seen in the transport direction after
the rotation. The rotation compensates for different coating times
which are due to the fact that coating already takes place upon the
first contact of the electrically conductive structure with the
cathodically connected band.
[0022] In order to coat on a plurality of sides of the substrate it
may preferably be rotated in the device, with which the substrate
can be rotated, so that after the rotation the surface to be coated
first points in the direction of the coating.
[0023] In order to coat both the upper side and the lower side of
the substrate simultaneously, in a further embodiment at least two
bands are respectively arranged so that the substrate to be coated
is guided through between them and the bands respectively contact
the upper side and the lower side of the substrate.
[0024] In order to coat rigid structures, the structure of the
electrolytic coating device is preferably such that the transport
plane of the substrate serves as a mirror plane. When the intention
is to coat foils whose length exceeds the length of the
bath--so-called endless foils which are first unwound from a roll,
guided through the electrolytic coating device and then wound up
again--they may for example also be guided through the bath in a
zigzag shape or in the form of a meander around a plurality of
electrolytic coating devices according to the invention, which for
example may then also be arranged above one another or next to one
another. The devices may respectively be aligned at any desired
angle in the bath. When the electrolytic coating devices are
arranged above one another, it is also possible to coat the foils
simultaneously on the upper side and the lower side by guiding them
respectively through between two devices which contact the foil on
the upper and lower sides and then deviating them around one of the
devices after passing through, so that they can then be guided
through between it and a further device arranged above or below the
device.
[0025] With the device according to the invention and the method
according to the invention, it is furthermore possible to coat
through-holes contained in the substrate, for instance bores or
slots, or even indentations such as blind holes. In the case of
through-holes of shallow depth, the coating is carried out in that
the metal layers deposited on the upper side and the lower side
grow together in the hole. In holes which are too deep for the
metal layers to grow together, a conductive hole wall is at least
partially provided which is coated by the method according to the
invention. In this way, it is then also possible to coat the entire
wall of a hole. If not all of the hole wall is electrically
conductive, here again the entire hole wall is coated by the metal
layers growing together.
[0026] So that the metal which deposits on the cathodically
connected shafts and/or bands can also be removed again during
operation of the electrolytic coating device, the shafts in a
preferred embodiment can be connected both anodically and
cathodically and can be lowered onto the substrate or raised from
the substrate. While these shafts are raised from the substrate and
are not in contact with the substrate, they can be connected
anodically. While the shafts are connected anodically, the metal
deposited thereon is removed again from them. Simultaneously, the
at least one band running around the shaft is also connected
anodically so that the metal deposited thereon is also removed from
it. The shafts which are in contact with the substrate via the at
least one band are connected cathodically.
[0027] In a further embodiment, the shafts may also contain a
plurality of electrically conductive regions, at least one of which
is connected anodically and at least one other is connected
cathodically. In this case the band running around is likewise
connected cathodically in the cathodically connected region of the
shaft, so that coating of the electrically conductive substrate or
the structured or full-surface electrically conductive surface of
the substrate takes place, while the undesired material previously
deposited in the anodic region is removed again from the shaft
and/or the at least one band. In this case, it is necessary for the
band to have sections electrically insulated from one another,
which are arranged on the shafts so that an electrically conductive
region of the band does not simultaneously touch an anodically
connected region and a cathodically connected region on the shaft,
in order to avoid a short circuit.
[0028] Other cleaning variants are also possible besides cleaning
by reversing the polarity of the shafts, for example chemical or
mechanical cleaning.
[0029] The electrically conductive sections of the at least one
band and the shaft surfaces, or the shaft regions which are in
contact with the at least one band, are preferably made of an
electrically conductive material which does not pass into the
electrolyte solution during operation of the device. Suitable
materials for making the conductive sections of the band and the
shaft surfaces, or the shaft regions which are in contact with the
at least one band, are for example metals, graphite, conductive
polymers such as polythiophenes or metal/plastic composite
materials. Stainless steel and/or titanium are preferred
materials.
[0030] With different poling of the shafts, on the one hand, the
anodically connected shafts may be used as anodes, and on the other
hand it is possible to provide additional anodes in the bath. When
only cathodically connected shafts and disks are provided, it is
necessary to arrange additional anodes in the bath. The anodes are
then preferably arranged as close as possible to the structure to
be coated. For example, the anodes may respectively be arranged
between two cathodically connected shafts. On the one hand any
material known to the person skilled in the art for insoluble
anodes is suitable as a material for the anodes. Stainless steel,
graphite, platinum, titanium or metal/plastic composite materials,
for example, are preferred here. On the other hand, soluble anodes
may also be provided. These then preferably contain the metal which
is electrolytically deposited on the electrically conductive
structures. The anodes may then assume any desired shape known to
the person skilled in the art. For example, it is possible to use
flat rods as anodes which are at a minimal distance from the
substrate surface during operation of the device, and which can be
retracted from the device in the direction of the shaft axes for a
position change of the shafts. It is also possible to use flat
metal as anodes, which can be folded by 90.degree. vertically
upward or downward between the roll displacements. A further
possibility is to provide resilient wires as anodes, for example
spiral wires, which can be drawn upward or downward out of the
device and inserted into it from winding/unwinding devices.
[0031] The electrolytic coating device can be used for any
conventional metal coating. The composition of the electrolyte
solution, which is used for the coating, in this case depends on
the metal with which the electrically conductive structures on the
substrate are intended to be coated. Conventional metals which are
deposited on electrically conductive surfaces by electrolytic
coating are, for example, gold, nickel, palladium, platinum,
silver, tin, copper or chromium.
[0032] Suitable electrolyte solutions, which can be used for the
electrolytic coating of electrically conductive structures, are
known to the person skilled in the art for example from Werner
Jillek, Gustl Keller, Handbuch der Leiterplattentechnik [handbook
of printed circuit technology], Eugen G. Leuze Verlag, 2003, volume
4, pages 332 to 352.
[0033] In order to electrolytically coat the electrically
conductive structures on the substrate, it is first delivered to
the bath of electrolyte solution. The substrate is then transported
through the bath, the at least one band of the cathode resting on
the substrate and thus contacting the electrically conductive
structures, the band preferably being moved with a circulation
speed which corresponds to the speed with which the substrate is
guided through the bath. The substrate may be transported through
the bath using a transport device, for example, as is known to the
person skilled in the art. It is nevertheless also possible to
arrange the coating device so that the substrate rests on the at
least one cathodically connected band and is transported through
the bath by the movement of the band. In particular, it is
advantageous to transport the substrate through the bath with the
at least one band of the coating device functioning as a transport
device whenever the substrate is intended to be coated on the upper
side and the lower side. In this case, the substrate rests on one
device while being pressed onto the device on which it rests by the
other device. The substrate is then transported through the device
by the movement of the bands.
[0034] Besides the bands, for example, it is nevertheless also
possible for at least one further transport roll, which preferably
consists of an electrically insulating material, to transport the
substrate through the bath. A combination of at least one band with
at least one additional transport roll is likewise possible. The
number of transport rolls required depends on the size of the
substrate to be coated. The spacing of the transport rolls must be
selected so that at least one transport roll is always in contact
with the substrate, unless the transport take places using the
bands. For the electrolytic coating of endless substrates, the
transport may also be carried out using the winding and unwinding
unit which is preferably arranged outside the bath.
[0035] When the shafts are provided with grooves in which are the
at least one band runs, the transport of the substrate by the
shafts and/or by the band takes place when they are driven.
[0036] So that the substrate is not on the one hand raised from the
electrolytic coating device and/or on the other hand pressed
against the device from below, and good contact of the substrate
with the cathodically connected regions is thereby simultaneously
ensured, at least one pressure roll or pressure band with which the
substrate is pressed against the cathodically connected regions is
preferably provided for one-sided coating.
[0037] A good contact between the cathodically connected band and
the substrate to be coated may also be achieved by pressing the
band onto the substrate via the weight of the shafts around which
it runs. It is also possible to produce an additional application
pressure by pressing the band against the substrate by spring
mounting of the shafts.
[0038] The shafts are preferably driven outside the bath. In a
preferred embodiment, all the shafts are driven. It is nevertheless
also possible to drive only some of the shafts. When a transport
device independent of the cathodes is provided, the bands may be
driven by the substrate lying in contact with them, no shaft around
which the band runs being provided with its own drive. It is
nevertheless also possible for the band to be additionally driven
by the at least one shaft around which it runs. So that a uniform
speed of all the bands is achieved, it is preferable for the shafts
to be driven via a common drive unit. The drive unit is preferably
an electric motor. The shafts are preferably connected to the drive
unit via a chain or belt transmission. It is nevertheless also
possible to provide the shafts respectively with gearwheels which
engage in one another and via which the shafts are driven. Besides
the possibilities described here, it is also possible to use any
other suitable drive known to the person skilled in the art for
driving the shafts.
[0039] In a preferred embodiment, the at least one band is supplied
with voltage via the shaft around which it runs. The shafts may in
this case be electrically conductive over the full surface or
partially on the surface, It is nevertheless also possible to make
the shafts from an insulating material and provide contact means
which, for example, are arranged between individual shafts. Such
contact means may, for example, be brushes which are in contact
with the electrically conductive sections of the band. Preferably,
however, the current supply takes place via the shafts. The voltage
supply of the shafts in this case preferably takes place outside
the bath. Suitable means for transmitting current to the shafts
are, for example, sliprings which are arranged on the shafts. For
bands whose electrically conductive section is at least as long as
the contact surface on the substrate, it is also possible to make
only some shafts electrically conductive and the remaining shafts
electrically insulating. In this case, it is also possible to
connect one shaft anodically and one shaft cathodically, while the
other shafts are insulated. In this embodiment, care must be taken
that the distance between the cathodically connected shaft and the
anodically connected shaft is greater than the length of the
electrically conductive region of the band.
[0040] In order to demetallize the cathodically connected shafts
and optionally bands, i.e. remove the metal deposited on them, they
are either connected anodically during production pauses or raised
from the substrate and then connected anodically. It is necessary
that no contact of the shafts with the structures to be coated
should occur while they are being demetallized. Otherwise, the
structures to be coated would likewise be anodically connected
anodically and the material already deposited on them would be
removed again. When the at least one band, which forms the cathode,
is constructed segmentally from conductive and nonconductive
sections which run around anodically and cathodically connected
shafts, in a preferred method variant the cathodically connected
shafts are raised from the substrate for demetallization while the
anodically connected shafts are simultaneously lowered onto the
substrate. Simultaneously with the shaft change, the shafts
previously connected cathodically are connected anodically so that
the material deposited thereon can be removed from them, and the
shafts previously connected anodically are connected cathodically
so that the electrically conductive structures on the substrate can
be coated further. Such a shaft change is preferably carried out
while the cathodically connected band section is not actually
contacting any structure to be coated. It is nevertheless also
possible to provide at least one preferably insulated shaft as a
tension shaft so that, for the shaft change, all the shafts are
first connected cathodically then the shafts previously connected
anodically are lowered onto the substrate, the shafts previously
connected cathodically are raised from the substrate and, after
they have been raised, connected anodically. When the device is
arranged below the substrate, the shafts previously connected
cathodically are lowered and subsequently connected anodically,
while the shafts previously connected anodically are raised against
the substrate and subsequently connected cathodically. When
additional insulated transport shafts or tension shafts are
provided, the lowering and raising of the shafts as well as the
polarity reversal may take place simultaneously.
[0041] Besides reversing the polarity of the shafts in order to
remove the metal deposited on them, it is also possible to provide
shielding on the cathodically connected shafts, which reduces the
metal deposition on the shafts. Such shielding is, for example,
nonconductive cladding of the shafts which covers the shafts in the
regions where they are in contact with the electrolyte solution,
the cladding being at a very small distance from the shafts surface
and the shafts being exposed only at the positions where the
substrate and/or the bands are contacted.
[0042] In a further method variant, the substrate to be coated is
rotated through a predetermined angle after passing through the
electrolytic coating device. After the rotation, the substrate
passes either through the device for a second time or through a
second corresponding device. The angle through which the substrate
is rotated preferably lies in the range of from 10.degree. to
170.degree., more preferably in the range of from 50.degree. to
140.degree., in particular in the range of from 80.degree. to
100.degree., and more particularly preferably the angle through
which the substrate is rotated is essentially 90.degree..
Essentially 90.degree. means that the angle through which the
substrate is rotated does not differ by more than 5.degree. from
90.degree.. The device for rotating the substrate may be arranged
inside or outside the bath. In order to coat the same side of the
substrate again, for example so as to achieve a greater layer
thickness of the metal layer, the rotation axis is perpendicular to
the surface to be coated. When another surface of the substrate is
intended to be coated, the rotation axis should be arranged so that
after the rotation the substrate is positioned in such a way that
the surfaced intended to be coated next points in the direction of
the cathode.
[0043] The layer thickness of the metal layer deposited on the
electrically conductive structure by the method according to the
invention depends on the contact time, which is given by the speed
with which the substrate passes through the device and the number
of bands positioned in series, as well as the current strength with
which the device is operated. A longer contact time may be
achieved, for example, by connecting a plurality of devices
according to the invention in series in at least one bath.
[0044] In one embodiment, a plurality of devices according to the
invention are connected in series respectively in individual baths.
It is therefore possible to hold a different electrolyte solution
in each bath, so as to deposit different metals successively on the
electrically conductive structures. This is advantageous, for
example, in decorative applications or for the production of gold
contacts. Here again, the respective layer thicknesses can be
adjusted by selecting the throughput speed and the number of
devices with the same electrolyte solution.
[0045] With the device according to the invention, it is possible
to coat all electrically conductive surfaces irrespective of
whether the intention is to coat mutually insulated electrically
conductive structures on a nonconductive substrate or a full
surface. The device is preferably used for coating electrically
conductive structures on an electrically nonconductive support, for
example reinforced or unreinforced polymers such as those
conventionally used for printed circuit boards, ceramic materials,
glass, silicon, textiles etc. The electrolytically coated
electrically conductive structures produced in this way are, for
example, conductor tracks. The electrically conductive structures
to be coated may, for example, be made of an electrically
conductive material printed on the circuit board. The electrically
conductive structure preferably either contains particles of any
geometry made of an electrically conductive material in a suitable
matrix, or consists essentially of the electrically conductive
material. Suitable electrically conductive materials are, for
example, carbon or graphite, metals, preferably aluminum, ion,
gold, copper, nickel, silver and/or alloys or metal mixtures which
contain at least one of these metals, electrically conductive metal
complexes, conductive organic compounds or conductive polymers.
[0046] A pretreatment may possibly be necessary first, in order to
make the structures electrically conductive. This may, for example,
involve a chemical or mechanical pretreatment such as suitable
cleaning. In this way, for example, the oxide layer which is
disruptive for electrolytic coating is previously removed from
metals. The electrically conductive structures to be coated may,
however, also be applied on the printed circuit boards by any other
method known to the person skilled in the art. Such printed circuit
boards are, for example, installed in products such as computers,
telephones, televisions, electrical parts for automobiles,
keyboards, radios, video, CD, CD-ROM and DVD players, game
consoles, measuring and control equipment, sensors, electrical
kitchen equipment, electronic toys etc.
[0047] Electrically conductive structures on flexible circuit
supports may also be coated with the device according to the
invention. Such flexible circuit supports are, for example, polymer
films such as polyimide films, PET films or polyolefin films, on
which electrically conductive structures are printed. The device
according to the invention and the method according to the
invention are furthermore suitable for the production of RFID
antennas, transponder antennas or other forms of antenna, chip card
modules, flat cables, seat heaters, foil conductors, conductor
tracks in solar cells or in LCD/plasma display screens or for the
production of electrolytically coated products in any form, for
example thin metal foils, polymer supports metal-clad on one or two
sides with a defined layer thickness, 3D-molded interconnect
devices or else for the production of decorative or functional
surfaces on products, which are used for example for shielding
electromagnetic radiation, for thermal conduction or as packaging.
It is furthermore possible to produce contact sites or contact pads
or interconnections on an integrated electronic component.
[0048] After leaving the electrolytic coating device, the substrate
may be further processed according to all steps known to the person
skilled in the art. For example, remaining electrolyte residues may
be removed from the substrate by washing and/or the substrate may
be dried.
[0049] The device according to the invention for the electrolytic
coating of electrically conductive substrates or electrically
conductive structures on electrically nonconductive substrates may,
according to requirements, be equipped with any auxiliary device
known to the person skilled in the art. Such auxiliary devices are,
for example, pumps, filters, supply instruments for chemicals,
winding and unwinding instruments etc.
[0050] All methods of treating the electrolyte solution known to
the person skilled in the art may be used in order to shorten the
maintenance intervals. Such treatment methods, for example, are
also systems in which the electrolyte solution
self-regenerates.
[0051] The device according to the invention may also be operated,
for example, in the pulse method known from Werner Jillek, Gustl
Keller, Handbuch der Leiterplattentechnik [handbook of printed
circuit technology], Eugen G. Leuze Verlag, 2003, volume 4, pages
192, 260, 349, 351, 352, 359.
[0052] The advantage of the device according to the invention and
the method according to the invention is that the at least one band
provides a greater contact area and therefore a longer contact time
per unit area than is the case with rolls such as those known from
the prior art. It is therefore possible achieve the desired layer
thicknesses of electrically conductive structures within a shorter
distance, such that the installations can also be made shorter or
operated with a high throughput, so that a lower operating costs
are or achieved. Another essential advantage is that now even very
short structures, for example those desired in the production of
printed circuit boards, can be produced more rapidly, with greater
control and above all more reproducibly and with homogeneous layer
thicknesses than is possible with the roll systems known from the
prior art.
[0053] The invention will be explained in more detail below with
the aid of the drawings. The figures respectively show only one
possible embodiment by way of example. Other than in the
embodiments mentioned, the invention may naturally also be
implemented in further embodiments or in a combination of these
embodiments.
[0054] FIG. 1 shows a plan view of a device designed according to
the invention with a plurality of bands arranged offset in
series,
[0055] FIG. 2 shows a side view of the device according FIG. 1,
[0056] FIG. 3 shows a side view of a device designed according to
the invention with bands which rest on the shaft,
[0057] FIG. 4 shows a plan view of a device according FIG. 3,
[0058] FIG. 5 shows a side view of a device designed according to
the invention with bands which rest in grooves of the shaft,
[0059] FIG. 6 shows a plan view of a device according FIG. 5,
[0060] FIG. 7 shows a side view of a device designed according to
the invention with cathodically and anodically connected
shafts,
[0061] FIG. 8 shows a detail of a band as used, for example, in
FIG. 7,
[0062] FIG. 9 shows a detail of a device designed according to the
invention, in which the anodically and cathodically connected
shafts can be raised or lowered,
[0063] FIG. 10 shows a device according to the invention in which
the upper and lower sides of a substrate can be coated,
[0064] FIG. 11 shows a device with which upper and lower sides of a
substrate can be coated, in which bands are arranged offset in
series,
[0065] FIG. 12 shows an enlarged representation of a detail of a
band in a first embodiment,
[0066] FIG. 13 shows an enlarged representation of a detail of a
band in a second embodiment,
[0067] FIG. 14 shows a plan view of a detail of a band in a third
embodiment,
[0068] FIG. 15 shows a side view of the band according to FIG.
14,
[0069] FIG. 16 shows a side view of a device according to the
invention with segmented shafts,
[0070] FIG. 17 shows a side view of anodes during the electrolytic
coating,
[0071] FIG. 18 shows a side view of the anodes according to FIG. 17
when changing the shafts.
[0072] FIG. 1 shows a plan view of a cathode designed according to
the invention, in which a plurality of bands are arranged offset in
series.
[0073] A cathode 1 comprises a plurality of bands 2, which are
respectively guided via two shafts 3. Bands 2 lying next to each
other are in this case arranged so that a gap 4 is formed between
them. The width of the gap 4 is in this case preferably greater
than or equal to the width of a band 2. In this way, the bands 2
arranged offset behind the bands 2 of a row can be guided through
the gap. In the embodiment represented in FIG. 1, one shaft 3 is in
this case respectively used as a rear shaft of the bands 2 of a
first row and as a front shaft 3 for the bands 2 of the second row.
In this way, it is possible to economize on shafts as well as space
compared to an arrangement in which the bands arranged offset
behind one row are guided around two separate shafts. The coating
in the embodiment represented in FIG. 1 respectively takes place in
the gaps 4 between the bands 2, so long as the electrically
conductive structures intended to be coated are touched by a band
2.
[0074] FIG. 2 shows a side view of the arrangement in FIG. 1.
[0075] In the side view represented in FIG. 2, it can be seen that
the bands 2 are respectively guided around two shafts 3. The shafts
are in this case arranged successively in series. The substrate to
be coated may be in contact with the cathode 1 either on the upper
side 5 or on the lower side 6. In this case, care should
respectively taken be merely that the electrically conductive
structures to be coated face toward the band 2. When the substrate
to be coated is guided along the upper side 5 of the cathode 1, the
cathode 1 may simultaneously serve as a transport device as
represented in FIG. 2. When the substrate to be coated is guided
along the lower side 6, a device is additionally provided with
which the substrate is placed against the bands 2 so that an
electrical contact is made between the lower side 6 of the cathode
1 and the substrate to be coated. This device is preferably a
transport device. Such devices are, for example, conveyor belts or
transport shafts.
[0076] For electrically contacting the bands 2 in the embodiment
represented in FIGS. 1 and 2, at least one shaft 3 around which a
band 2 runs is respectively connected cathodically. Furthermore, it
is also possible to connect each shaft 3 cathodically.
[0077] In order to permit electrolytic coating, anodes 31 in
addition to the cathode 1 must also be provided in the bath. The
cathodes 31 may be arranged either between the shafts 3, as
represented in FIG. 2, or else above or below the band 2.
[0078] A device designed according to the invention, with bands 2
which rest on the shaft 3, is represented in a side view in FIG. 3
and in a plan view in FIG. 4. The bands 2 are respectively guided
around two shafts 3. Since the shafts 3 are designed as cylindrical
rolls, the bands 2 rest on the rolls. Contact with the substrate
takes place here only through the band. In contrast to this, FIG. 5
represents a side view and FIG. 6 a plan view of an embodiment in
which the bands 2 are held in grooves 30 in the shafts 3. The width
of a groove 30 preferably corresponds to the width of a band 2 and
the depth of a groove 30 preferably to the thickness of a band 2.
By holding the bands 2 in the grooves 30, it is possible to avoid
axial displacement of the bands 2 on the shafts 3. In an embodiment
in which the depth of the groove 30 corresponds to the thickness of
a band 2, as represented here, the shaft 3 also rests on the
substrate. Additional contacting can thereby take place through the
shaft 3.
[0079] FIG. 7 shows a further embodiment of an electrolytic coating
device according to the invention in a sectional
representation.
[0080] In the embodiment represented in FIG. 7, an electrically
conductive structure 7 on a substrate 8 is coated with a device
designed according to the invention. The device comprises a band 2,
which is guided around a plurality of shafts 3. The shafts 3 are
arranged in an upper row 9 and a lower row 10. The shafts of the
lower row 10 are connected cathodically, while the shafts of the
upper row 9 are connected anodically. The voltage of the
cathodically connected shafts of the lower row 10 is transmitted to
the electrically conductive structure 7 via the band 2. By means of
this, the electrically conductive structure 7 is likewise charged
negatively so that metal ions of the electrolyte solution, in which
the substrate 8 and the device are held, deposit to form a metal
layer. Since the shafts 3 of the lower row 10 and the band 2 in the
region of the lower row 10 are negatively charged, metal ions
likewise deposit on them. So that the metal deposited on the band 2
can be removed again, the upper row 9 is connected anodically. By
means of this, the band 2 is charged positively in the region of
the upper row 9 and the metal ions pass back into the electrolyte
solution. The liquid level of the bath of electrolyte solution is
denoted by reference numeral 11 and is represented by a solid
line.
[0081] In addition to the anodically connected shafts of the upper
row 9, anodes 31 may be arranged between the cathodes as
represented here. The anodes 31 are, for example, designed as flat
rods.
[0082] So that there is no short circuit in the band 2, the band 2
in the embodiment represented in FIG. 7 is constructed as
represented in FIG. 8. Here, the band 2 comprises electrically
conductive sections 12 and electrically nonconductive sections,
i.e. insulating sections 13. The length L of an electrically
conductive section 12 is preferably greater than or equal to the
distance h between two cathodically connected shafts 3. In order to
avoid a short circuit, however, the length L of an electrically
conductive section 12 must be less than the distance d from a
cathodically connected shaft to a neighboring anodically connected
shaft.
[0083] The transport direction of the substrate 8 is represented by
the arrow 14. In order to press the substrate against the band 2,
pressure rolls 21 are arranged below the substrate 8. The substrate
8 is guided through between the pressure rolls 21 and the band 2.
The required pressure force may be achieved on the one hand in that
the pressure rolls 21 are mounted firmly and the shafts 3, around
which the band 2 runs, are sprung-mounted and pressed against the
substrate 8, or in that the shafts 3 are mounted firmly and the
pressure rolls 21 are mounted a mobile fashion and moved against
the substrate 8 with the required pressure force. When it is
intended that the shafts 3 of the upper row 9 and of the lower row
10 can change their position, it is preferable for the pressure
rolls 21 to be mounted firmly and for the required application
pressure to be applied onto the substrate 8 by the mobile shafts 3
of the lower row 10.
[0084] Instead of the individual pressure rolls 21 as represented
in FIG. 7, it is also possible to use a band which runs around
shafts and which, for example, is constructed like the cathode
represented in FIG. 2 but without being electrically
conductive.
[0085] In a further embodiment, another electrolytic coating device
may be arranged below the substrate 8 instead of the pressure rolls
21. In this case, the substrate 8 can then be coated simultaneously
on its upper side and its lower side.
[0086] FIG. 9 shows a side view of a device designed according to
the invention in a further embodiment.
[0087] In the embodiment represented in FIG. 9, the shafts of the
anodically connected upper row 9 are arranged offset with respect
to the shafts of the cathodically connected lower row 10. The
distance h between two anodically connected shafts, or between two
cathodically connected shafts, is selected respectively so that an
anodically connected shaft can be guided through between two
neighboring cathodically connected shafts and a cathodically
connected shaft between two anodically connected shafts. The arrows
15 in FIG. 9 represent the fact that the shafts of the lower row 10
can be raised and the shafts of the upper row 9 can be lowered.
This makes it possible for the metal deposited on the cathodically
connected shafts to be removed even in continuous production
operation. To this end, the cathodically connected shafts of the
lower row 10 are raised as represented by the arrows 16, while the
shafts of the upper row 9 are lowered as represented by the arrows
16. At the same time, the polarity of the shafts is reversed so
that after lowering the upper row 9, these shafts are connected
cathodically, and after raising the lower row 10, these shafts are
connected anodically. Owing to the polarity change, metal now
deposits on the shafts of the upper row 9 which were previously
connected anodically but now form the lower row 10 and are
connected anodically, while metal is removed from the shafts of the
lower row 10 which were previously connected cathodically, so long
as they form the upper row 9 and are connected anodically.
[0088] Besides the embodiment as represented in FIGS. 3 and 5, in
which all the shafts of the upper row 9 are connected anodically
and all the shafts of the lower row 10 are connected cathodically,
it is also possible to provide at least one transport shaft which
is electrically nonconductive in each row. Preferably, the
transport shafts are respectively the first and/or last shaft of a
row 9, 10.
[0089] So that all the metal can be removed again from the shafts 3
and the bands 2, at least as many shafts 3 are connected anodically
as cathodically. The number of the anodically connected shafts is
preferably greater than that of the cathodically connected shafts.
In order to achieve this, for example in the embodiment represented
in FIG. 9, the first shaft of the upper row 9 always remains
connected anodically and stays in its position.
[0090] FIG. 10 shows an electrolytic coating device in a further
embodiment.
[0091] In the device represented in FIG. 10, the substrate 8 is
coated simultaneously on the upper and lower sides. To this end,
the substrate 8 is guided through between an upper device 17 and a
lower device 18. The distance between the upper device 17 and the
lower device 18 is selected so that it corresponds precisely to the
thickness of the substrate 8.
[0092] In the embodiment represented here, the shafts 19 next to
the substrate are respectively connected cathodically, while the
shafts 20 remote from the substrate are connected anodically. In
the embodiment represented in FIG. 10 as well, the shafts 19 can
preferably be raised from the substrate 8 and the shafts 20 lowered
onto the substrate 8. The polarity of the shafts is simultaneously
reversed, so that the shafts 20 are connected cathodically as soon
as they contact the substrate 8, and the shafts 19 are connected
anodically as soon as they are raised from the substrate 8. In the
embodiment represented here, a plurality of bands 2 are arranged in
series on the upper side and the lower side of the substrate 8. The
bands 2 are respectively guided around separate shafts. The
successively arranged bands 2 are preferably arranged mutually
offset.
[0093] The embodiment represented in FIG. 11 corresponds
substantially to the embodiment represented in FIG. 10. However, a
cathodically connected shaft 19 and an anodically connected shaft
20 respectively form the rear shaft of a band 2 and simultaneously
the front shaft of a further band 22, which is represented here by
dashes. In plan view, the arrangement of the bands 2 and of the
further bands 22 represented by dashes corresponds to the
arrangement represented in FIG. 1. Here, the bands 22 are
respectively arranged offset behind the bands 2.
[0094] FIG. 12 represents an enlarged representation of a first
embodiment of a band designed according to the invention with
electrically conductive sections and electrically nonconductive
sections.
[0095] The band 2 schematically represented here is constructed
from individual conductive segments 23 and nonconductive segments
24. The individual segments 23, 24 are respectively fastened to one
another by brackets 25. The length of the conductive sections is
established by the number of conductive segments 23 which are
fastened together. An electrically nonconductive section is in each
case arranged between two conductive sections. In general, it is
sufficient merely to use a single electrically nonconductive
segment 24 for the electrically nonconductive section. It is
nevertheless also possible to arrange a plurality of nonconductive
segments 24 in series.
[0096] FIG. 13 represents a further embodiment of a band 2. The
band 2 is made from a flexible support 26, around which an
electrically conductive wire 27 is wound in order to produce an
electrically conductive section 12. A suitable flexible support 26
is, for example, a nonconductive plastic band which is optionally
made of an elastomer. Instead of the electrically conductive wire
27 represented in FIG. 13, for example, an electrically conductive
foil may be wound around the flexible support 26 in order to
produce the electrically conductive section 12.
[0097] A further embodiment of a band 2 is schematically
represented in a plan view in FIG. 14 and a side view in FIG. 15.
The band 2 represented here comprises two flexible nonconductive
supports 26, on which conductive sections 32 are fastened at a
regular spacing. The conductive sections 32 may, for example, be
fastened on the conductive supports 26 by adhesive bonding. The
conductive sections 32 may be either rigid or flexible. In the case
of rigid conductive sections 32, their width is preferably selected
so that they can run around the shafts 3. To this end, it is
necessary for the width of the conductive sections 32 to be less
than the radius of the shaft 3. If the conductive sections 32 are
intended to be made wider, they are preferably made of this
flexible material. A suitable material is, for example, a likewise
flexible metal foil. The nonconductive support 26 and/or the
conductive sections 32 of the band 2 may also be provided with
holes or designed in the form of a network.
[0098] Besides the embodiments of the bands 2 with electrically
conductive sections 12 and electrically nonconductive sections 13
as represented in FIGS. 12 to 15, any other structure known to the
person skilled in the art from which a band, which alternately has
electrically conductive and electrically nonconductive sections,
can be produced is possible. For example, it is possible to provide
a network structure as the band 2, an electrically conductive
network being connected to an electrically nonconductive network,
wire or polymer support in order to form the electrically
conductive sections 12 and electrically nonconductive sections 13.
For example, the electrically conductive sections in the form of a
network may then be connected to the meshes of a nonconductive
section with the aid of a wire which is guided through the
individual meshes of the network structure.
[0099] FIG. 16 shows an embodiment of a device designed according
to the invention, in which the shafts 3 are constructed from
individual conductive segments 35 and nonconductive segments 36.
The conductive segments 35 and the nonconductive segments 36 are
arranged alternately. This makes it possible for a conductive
segment 35 to be connected cathodically and for a neighboring
conductive segment 35, which is separated from the cathodically
connected segment 35 by a nonconductive segment 36, to be connected
anodically. In order to prevent a short circuit, it is necessary
for the band 2 running around the shafts 3 to be configured with
individual conductive 12 and electrically nonconductive sections
13. The nonconductive sections 13 of the band 2 must be arranged so
that they respectively rest on a nonconductive segment 36 of the
shaft. Removal of the metal deposited on the cathodically connected
segment 35 of the shaft and the cathodically connected section 12
of the band 2 is achieved by connecting them anodically in a
further revolution. To this end, sliding contacts 37, 38 are
preferably provided on the shafts 3. The first sliding contact 37
is used as an anode, and the second sliding contact 38 as a
cathode. So long as a conductive segment 35 is in contact with the
first sliding contact 37, this segment 35 is connected anodically,
and it is connected cathodically as soon as it comes in contact
with the second sliding contact 38. Besides the sliding contacts
37, 38 described here, it is also possible to use any other contact
which does not hinder rotation of the shafts 3, and with which the
conductive segments 35 can be selectively connected cathodically
and anodically. The distance between the anode 37 and the cathode
38 must be large enough to prevent simultaneous contact of the
anode 37 and cathode 38 with a conductive segment 35.
[0100] Owing to the anodically connected electrically conductive
segments 35, in the embodiment represented in FIG. 16 it is not
necessary to provide further additional anodes. It is nevertheless
possible to arrange further anodes between the shafts 3, for
example in the form of flat rods.
[0101] FIG. 17 shows a side view of anodes during the electrolytic
coating.
[0102] FIG. 18 shows the anodes in a position when the shafts 3
(which are not represented here) change their position.
[0103] If anodes 31 are provided in addition to the anodically
connected shafts 3 or electrically conductive segments of the
shafts 3, they may for example be constructed as represented in
FIGS. 17 and 18.
[0104] During the coating process, the anodes 31 are in their
deployed position. For a substrate 8 which is coated simultaneously
on the upper side and the lower side, they are then arranged above
and below the substrate 8. When only one side of the substrate 8 is
coated, the anode 31 is preferably arranged on the side of the
substrate 8 which is coated. In this case, care should be taken
that the anode 31 does not touch the substrate. Otherwise, on the
one hand, a short circuit could occur when the cathode touches the
same electrically conductive structure as the anode, and on the
other hand metal previously deposited on the structure would be
removed again during the contact with the anode 31.
[0105] In order to make it possible to change the shafts, the
anodes 31 can be moved parallel to the surface of the substrate 8
which is to be coated, as represented by the double arrow 41 in
FIG. 18. The movement takes place transversely to the direction in
which the substrate is transported through the bath. This makes it
possible to remove the anodes while the shafts 3 change their
position. Damage of the anodes 31 and shafts 3 is thereby avoided.
In the embodiment represented here, the anodes 31 are made of a
flexible material. This makes it possible for the anodes to be
wound in respectively allocated anode winding/unwinding devices 40
and unwound therefrom. The anode winding/unwinding devices 40 are
preferably arranged above and below the bath, as represented here.
Such windable and unwindable anodes are, for example, made in the
form of flexible metal bands or resilient spirals, If the anodes
made of resilient spirals, a plurality of the spirals are
preferably fastened next to one another.
LIST OF REFERENCES
[0106] 1 cathode [0107] 2 band [0108] 3 shaft [0109] 4 gap [0110] 5
upper side [0111] 6 lower side [0112] 7 electrically conductive
structure [0113] 8 substrate [0114] 9 upper row [0115] 10 lower row
[0116] 11 liquid level [0117] 12 electrically conductive section
[0118] 13 electrically nonconductive section [0119] 14 transport
direction [0120] 15 movement direction of the shafts [0121] 16
movement direction of the shafts [0122] 17 upper device [0123] 18
lower device [0124] 19 cathodically connected shafts [0125] 20
anodically connected shafts [0126] 21 pressure roll [0127] 22
further band [0128] 23 conductive segment [0129] 24 nonconductive
segment [0130] 25 bracket [0131] 26 flexible support [0132] 27 wire
[0133] 30 groove [0134] 31 anode [0135] 32 conductive section
[0136] 35 conductive segment [0137] 36 nonconductive segment [0138]
37 anode [0139] 38 cathode [0140] 40 anode winding/unwinding device
[0141] 41 movement direction of the anode [0142] d distance between
a cathodically connected shaft and an anodically connected shaft
[0143] h distance between two cathodically connected shafts [0144]
L length
* * * * *