U.S. patent application number 14/234080 was filed with the patent office on 2014-06-12 for apparatus for electrochemical deposition of a metal.
This patent application is currently assigned to ENTHONE INC.. The applicant listed for this patent is Christine Fehlis, Marlies Kleinfeld, Stefan Schafer. Invention is credited to Christine Fehlis, Marlies Kleinfeld, Stefan Schafer.
Application Number | 20140158545 14/234080 |
Document ID | / |
Family ID | 46584409 |
Filed Date | 2014-06-12 |
United States Patent
Application |
20140158545 |
Kind Code |
A1 |
Schafer; Stefan ; et
al. |
June 12, 2014 |
APPARATUS FOR ELECTROCHEMICAL DEPOSITION OF A METAL
Abstract
The invention as described in the following relates to an
apparatus for the electrochemical deposition of a metal on a
substrate, which apparatus is capable of refreshing an electrolyte
used for the deposition in a continuous way. Furthermore, the
invention as described relates to a method of refreshing an
electrolyte for the electrochemical deposition of a metal on a
substrate.
Inventors: |
Schafer; Stefan; (Solingen,
DE) ; Fehlis; Christine; (Langenfeld, DE) ;
Kleinfeld; Marlies; (Wuppertal, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Schafer; Stefan
Fehlis; Christine
Kleinfeld; Marlies |
Solingen
Langenfeld
Wuppertal |
|
DE
DE
DE |
|
|
Assignee: |
ENTHONE INC.
West Haven
CT
|
Family ID: |
46584409 |
Appl. No.: |
14/234080 |
Filed: |
July 20, 2012 |
PCT Filed: |
July 20, 2012 |
PCT NO: |
PCT/US2012/047535 |
371 Date: |
January 24, 2014 |
Current U.S.
Class: |
205/101 ;
204/251 |
Current CPC
Class: |
C25D 21/18 20130101;
C25D 3/54 20130101; C25D 21/14 20130101; C25D 17/12 20130101 |
Class at
Publication: |
205/101 ;
204/251 |
International
Class: |
C25D 21/14 20060101
C25D021/14; C25D 17/12 20060101 C25D017/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 20, 2011 |
EP |
11174683.0 |
Claims
1. An apparatus for the electrochemical deposition of a metal on a
substrate, the apparatus comprising: a plating tank holding a
plating electrolyte and a refreshing tank in fluidic connection to
the plating tank for refreshing the plating electrolyte, wherein
the plating tank comprises an inert electrode electrically
connected to the substrate by a rectifier, and wherein the
refreshing tank comprises a first compartment and a second
compartment, and the compartments are separated from each other by
a semi permeable separator, wherein the first compartment comprises
at least one soluble anode of a metal to be deposited on the
substrate and the second compartment comprises at least one inert
electrode, the inert electrode and the soluble anode are
electrically connected to a rectifier and wherein the at least one
soluble anode is at least during the operation of the apparatus in
a liquid state .
2. The apparatus according to claim 1, wherein the electrical
conductivity between the electrolyte in the plating tank and
electrolyte in the refreshing tank is .ltoreq.1*10.sup.-4 S.
3. The apparatus according to claim 1, wherein the refreshing tank
comprises at least two soluble anodes of two different metals to be
deposited on the substrate, and each of the soluble anodes is
connected to a separate rectifier.
4. The apparatus according to claim 3, wherein the refreshing tank
comprises a separate inert electrode per rectifier.
5. (canceled)
6. The apparatus according to claim 1, wherein the refreshing tank
comprises a kettle for holding the soluble anode, said kettle
comprising an electrical contact for contacting the soluble
anode.
7. The apparatus according to claim 1, wherein the second
compartment holds an electrolyte which is different from the
plating electrolyte.
8. The apparatus according to claim 1, wherein the semi permeable
separator is at least one of a membrane, a diaphragm, and a
micro-porous wall.
9. The apparatus according to claim 1, wherein the electrode of the
plating tank comprises at least an electrode base body and a
screen, said screen reducing the exchange of liquid in the direct
environment of the electrode.
10. The apparatus according to claim 1, wherein the apparatus
comprises a drop section for electrically isolating the electrolyte
in the plating tank from the electrolyte in the refreshing
tank.
11. The apparatus according to claim 1, said apparatus comprising
an analyzer for analyzing the concentration in the electrolyte of
the metal to be deposited on the substrate.
12. A method of refreshing an electrolyte for electrochemical
deposition of a metal on a substrate, the method comprising the
steps of: separating at least a partial stream of the electrolyte
from a plating tank and feeding said stream to a refreshing tank,
said refreshing tank comprising a first compartment and a second
compartment, the compartments are separated from each other by a
semi permeable separator, wherein the first compartment comprising
at least one soluble anode of a metal to be deposited on the
substrate and the second compartment comprises at least one inert
electrode; connecting the inert electrode and the soluble anode
electrically to a rectifier; setting the current and/or voltage of
the rectifier to a range suitable to electrochemically dissolve
metal from the soluble anode; re-feeding at least a partial stream
of the electrolyte in the refreshing tank to the plating tank.
13. The method according to claim 12, wherein the concentration in
the electrolyte of the ions of the metal to be deposited is
analyzed and the current and/or voltage of the rectifier is set to
maintain a concentration of the metal to be deposited within a
variation limit of .ltoreq.3% by weight.
14. Use of an apparatus according to any one of the claims 1 to 11
for the electrochemical deposition of a metal form an alkaline
electrolyte.
15. The use according to claim 14, wherein the metal to be
deposited is a metal of the group consisting of gallium, indium,
and thallium.
16. The apparatus according to claim 1, wherein the electrical
conductivity between the electrolyte in the plating tank and
electrolyte in the refreshing tank is .ltoreq.1*10.sup.-5 S.
17. The apparatus according to claim 1, wherein the electrical
conductivity between the electrolyte in the plating tank and
electrolyte in the refreshing tank is .ltoreq.1*10.sup.-6 S.
18. The apparatus according to claim 1, wherein: the refreshing
tank comprises at least two soluble anodes of two different metals
to be deposited on the substrate, and each of the soluble anodes is
connected to a separate rectifier, refreshing tank comprises a
separate inert electrode per rectifier, the refreshing tank
comprises a kettle for holding the soluble anode, said kettle
comprising an electrical contact for contacting the soluble anode,
the second compartment holds an electrolyte which is different from
the plating electrolyte, the semi permeable separator is at least
one of a membrane, a diaphragm, and a micro-porous wall, the
apparatus comprises a drop section for electrically isolating the
electrolyte in the plating tank from the electrolyte in the
refreshing tank, and the apparatus comprises an analyzer for
analyzing the concentration in the electrolyte of the metal to be
deposited on the substrate.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to European Application
11174683.0-1227 filed Jul. 20, 2011, the entire disclosure of which
is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention as described in the following relates to an
apparatus for the electrochemical deposition of a metal on a
substrate, which apparatus is capable of refreshing an electrolyte
used for the deposition in a continuous way. Furthermore, the
invention as described relates to a method of refreshing an
electrolyte for the electrochemical deposition of a metal on a
substrate.
BACKGROUND OF THE INVENTION
[0003] Electrochemical deposition of a metal, also referred to as
electroplating, is a well-know process used, for example, to
deposit a metal coating on a substrate surface or work-piece.
Electroplating is versatile used in many industrial fields, like
e.g. automotive industry, aerospace industry, fitting industry,
machine building, and electric/electronic industry.
[0004] In general, for the electrochemical deposition of a metal on
a substrate surface, the surface on which the metal is intended to
be deposited is brought into contact with a conductive electrolyte
comprising ions of the metal to be deposited. While the substrate
surface is brought into contact with the electrolyte an electric
current between the substrate surface and a counter-electrode is
applied. By the applied electric current the metals ions are
reduced to the metal and deposited on the substrate surface
according to the general formula:
M.sup.n++n e.sup.-.fwdarw.M.sup.0.dwnarw.,
[0005] A special field of electric/electronic industry in this
concern is solar industry producing solar cells for transforming
sunlight into electric energy. Due to boost on renewable energy,
especially the demand on solar cells has increased. A modern type
of solar cell is the so called CIGS thin film solar cell (copper,
indium, gallium, sulfur and selene thin film solar cell), which is
only about 3 .mu.m thick and can also be flexible.
[0006] For the production of such CIGS thin film solar cells, for
example a (Cu(InGa)Se.sub.2-layer is deposited on a substrate
surface, like e.g. a glass substrate, a polymer substrate, or a
metal foil. Other combinations of layers are possible, too. For
example, CIS, CuGaSe.sub.2, or CuInGaSeS layer combinations are
also known in the state of the art, as well as bypass cells. The
quality of the metal deposition is quite sensitive to the
concentration of the metal to be deposited in the electrolyte used
for the electrochemical deposition process, especially with respect
to the thickness distribution of the deposited metal layer.
[0007] US 20090315148 A1 discloses an electrochemical deposition
method to form uniform and continuous Group IIIA material rich thin
films with repeatability. Such thin films are used in fabrication
of semiconductor and electronic devices such as thin film solar
cells. In one embodiment, the Group IIIA material rich thin film is
deposited on an interlayer that includes 20-90 molar percent of at
least one of In and Ga and at least 10 molar percent of an additive
material including one of Cu, Se, Te, Ag and S. The thickness of
the interlayer is adapted to be less than or equal to about 20% of
the thickness of the Group IIIA material rich thin film.
[0008] US 20090173634 A1 discloses gallium (Ga) electroplating
methods and chemistries to deposit uniform, defect free and smooth
Ga films with high plating efficiency and repeatability. Such
layers may be used in fabrication of electronic devices such as
thin film solar cells. In one embodiment, the present invention
provides a solution for application on a conductor that includes a
Ga salt, a complexing agent, a solvent, and a Ga-film having
submicron thickness is facilitated upon electrodeposition of the
solution on the conductor. The solution may further include one or
both of a Cu salt and an In salt.
[0009] US 20100140098 A1 discloses a selenium containing
electrodeposition solutions used to manufacture solar cell absorber
layers. In one aspect is described an electrodeposition solution to
electrodeposit a Group IB-Group VIA thin film that includes a
solvent; a Group IB material source; a Group VIA material source;
and at least one complexing that forms a complex ion of the Group
IB material. Also described are methods of electroplating using
electrodeposition solutions.
[0010] US 20100059385 A1 discloses a method for fabricating CIGS
thin film solar cells using a roll-to-roll system. The invention
discloses method to fabricate semiconductor thin film Cu(InGa
(SeS).sub.2 by sequentially electroplating a stack comprising of
copper, indium, gallium, and selenium elements or their alloys
followed by selenization at a temperature between 450 C and 700
C.
[0011] US 20040206390 A1 discloses a photovoltaic cell exhibiting
an overall conversion efficiency of at least 9.0% is prepared from
a copper-indium-gallium-diselenide thin film. The thin film is
prepared by simultaneously electroplating copper, indium, gallium,
and selenium onto a substrate using a buffered electro-deposition
bath. The electrodeposition is followed by adding indium to adjust
the final stoichiometry of the thin film.
[0012] US 20100317129 A1 discloses a methods and apparatus for
providing composition control to thin compound semiconductor films
for radiation detector and photovoltaic applications. In one aspect
of the invention, there is provided a method in which the molar
ratio of the elements in a plurality of layers are detected so that
tuning of the multi-element layer can occur to obtain the
multi-element layer that has a predetermined molar ratio range. In
another aspect of the invention, there is provided a method in
which the thickness of a sub-layer and layers there over of Cu, In
and/or Ga are detected and tuned in order to provide tuned
thicknesses that are substantially the same as pre-determined
thicknesses.
SUMMARY OF THE INVENTION
[0013] Among other aspects it is an object of the invention to
provide an improved apparatus and method the deposition of metal
layers on a substrate surface. Furthermore, it is an aspect of the
invention to provide an improved apparatus and method for the
deposition of a metal layer as used in the production of thin film
solar cells.
[0014] Surprisingly, it was found that the object of the invention
with respect to the apparatus is solved by an apparatus according
to independent claim 1.
[0015] By independent claim 1, an apparatus for the electrochemical
deposition of a metal on a substrate is provided, the apparatus
comprising a plating tank holding a plating electrolyte and a
refreshing tank in fluidic connection to the plating tank for
refreshing the plating electrolyte, wherein the plating tank
comprises an inert electrode electrically connected to the
substrate by a rectifier, and wherein the refreshing tank comprises
a first compartment and a second compartment, the compartments are
separated from each other by a semi permeable separator, wherein
the first compartment comprises at least one soluble anode of a
metal to be deposited on the substrate and the second compartment
comprises at least one inert electrode, the inert electrode and the
soluble anode are electrically connected to a rectifier.
[0016] The apparatus comprises a plating tank holding a plating
electrolyte for the electrochemical deposition of a metal on a
substrate surface. The electrolyte comprises ions of at least one
metal to be deposited. The ions of the metal to be deposited are
dissolved in a solvent, like e.g. water. The ions of the metal do
be deposited are comprised in the electrolyte in an amount suitable
to allow a metal deposition on the substrate surface by applying an
electrical current between the substrate surface and a counter
electrode, e.g. an inert anode electrically connected to the
substrate by e.g. a rectifier.
[0017] The use of an inert anode in the plating tank is
advantageous, because the inert anode is dimensionally stable and
allows a constant anodic current density. Furthermore, an inert
anode allows a higher degree of freedom in the design of the
cell.
[0018] Additionally, the electrolyte may comprise additive
influencing/supporting the deposition of the metal and/or
stabilizing the electrolyte. Further additives may be comprised in
the electrolyte. Due to the appliance of the electrical current on
the substrate surface the ions of the metal the metal to be
deposited are reduced to the metal, thereby depositing a metal
layer on the substrate surface. Due to the reduction of the metal
ions to the metal and the deposition of the metal layer on the
substrate surface, the concentration of the metal ions within the
electrolyte decreases. However, the plating result depends
significantly on the concentration of the ions of the metal to be
plated within the electrolyte. It is therefore mandatory to
maintain the concentration of the ions of the metal to be deposited
in the electrolyte. For maintenance of the metal ion concentration,
a salt of the respective metal can be added to the electrolyte.
However, while the added salt will dissolve in the electrolyte and
the metal ions will be reduced to the metal and will be deposited
on the substrate surface, the anions of the metal salt will remain
in the electrolyte which subsequently influences the features of
the electrolyte with respect to, e.g. the density, or the pH-value.
However, the plating process is sensitive also to these features,
so that the plating result, especially the thickness distribution
of the deposited metal layer, may change over the aging of the
electrolyte. According to the invention, a refreshing tank in
fluidic connection to the plating tank for refreshing the plating
electrolyte is provided. The refreshing tank comprises a first
compartment and a second compartment, the compartments are
separated from each other by a semi permeable separator, wherein
the first compartment comprises at least one soluble anode of a
metal to be deposited on the substrate and the second compartment
comprises at least one inert electrode, the inert electrode and the
soluble anode of the metal to be deposited are electrically
connected to a rectifier. Soluble anode in this concern means, that
metal ions of the metal to be deposited are dissolved from the
soluble anode by applying a current between the soluble anode and
the inert electrode in the refreshing tank. Accordingly, the
concentration of the ions of the metal to be deposited in the
refreshing tank can be controlled by the current density and/or
voltage of the current applied to the electrodes in the refreshing
tank. Since the refreshing tank and the plating tank are in fluidic
connection, the concentration in the plating electrolyte of the
ions of the metal to be deposited can be maintained by dissolving
metal ions from the soluble anode. Advantageously, this allows
maintaining the ion concentration of the metals to be deposited
within a narrow range without influencing the other features of the
plating electrolyte, like e.g. pH-value, or density.
[0019] According to an embodiment of the invention, the semi
permeable separator separating the at least two compartments of the
refreshing tank from each other is at least one of a membrane, a
diaphragm, and a micro-porous wall.
[0020] According to another embodiment of the invention, the second
compartment of the refreshing tank in which the inert electrode is
located holds an electrolyte which is different from said plating
electrolyte. The electrolyte comprised in said second compartment
may be a conductive aqueous solution of a conductive salt, like
e.g. sodium hydroxide, potassium hydroxide, lithium hydroxide,
sodium chloride, potassium chloride, lithium chloride, sodium
sulfate, potassium sulfate, lithium sulfate, sodium hydrogen
sulfate, potassium hydrogen sulfate, sodium hydrogen carbonate,
potassium hydrogen carbonate, and the like. Additionally, acids
like e.g. sulfuric acid, hydrochloric acid can be used.
[0021] According to an embodiment of the invention, the electrical
conductivity between the electrolyte in the plating tank and the
electrolyte in the refreshing tank is .ltoreq.1*10.sup.-4S,
preferably .ltoreq.1*10.sup.-5S. By this, an interdependency
between the current applied in the plating tank to enable
deposition of a metal layer on the substrate and the current
applied in the refreshing tank for dissolving metal-ions from the
soluble anode can be omitted.
[0022] According to another embodiment of the invention, the low
electrical conductivity between the electrolytes in plating tank
and refreshing tank is realized by a galvanic isolation of the
electrolytes. According to a preferred embodiment of the invention,
the apparatus comprises a drop section within the fluidic
connection between the plating tank and the refreshing tank. In the
drop section, the fluidic stream of electrolyte between the
refreshing tank and the plating tank is dissipated into separated
droplets falling from an upper drop section to a lower drop
section. While the upper drop section is in electrical contact with
the one of the plating tank or refreshing tank, the lower drop
section is in electrical contact with the other tank. Due to the
separate droplets of electrolyte, the two tanks are
electrically/galvanically separated from each other.
[0023] According to another embodiment of the invention, the
fluidic connection between the plating tank and the refreshing tank
is long enough to enable an electrical conductivity of
.ltoreq.1*10.sup.-4S between the two tanks. Depending on the
relative conductivity of the electrolyte, the diameter and the
length of the fluidic connection between the refreshing tank and
the plating tank is to be chosen to generate an electrical
resistance which is high enough to assure an electrical
conductivity of .ltoreq.1*10.sup.-4S.
[0024] According to another embodiment of the invention, the
refreshing tank comprises at least two soluble anodes of two
different metals to be deposit on the substrate, each of the
soluble anodes is connected to a separate rectifier. By providing
two soluble anodes in the refreshing tank, also electrolytes used
for co-deposition of metals on a substrate surface can be
maintained by the apparatus according to the invention. For
example, in an electrolyte used for the deposition of indium and
gallium on a substrate in the process of producing a CIGS thin film
solar cell, the concentration of the indium within the plating
electrolyte as well as the concentration of the gallium within the
plating electrolyte can be maintained. Due to the separate
rectifiers used in the refreshing tank, the dissolution of the
metal from the soluble anodes can be controlled separately. This
enables an accurate control and maintenance of the metal ion
concentration of the metals to be deposited. According to another
embodiment of the invention, the refreshing tank comprises a
separate inert electrode per rectifier. By this, the accuracy of
the maintenance is further enhanced. According to another preferred
embodiment, the separate inert electrodes are located in separated
compartments, each separated from the compartment holding the
electrolyte to be refreshed by a semi permeable separator.
[0025] According to another embodiment of the invention, at least
on soluble anode is at least during the operation of the apparatus
in liquid state. Liquid state in this concern should be understood
as that the soluble anode is not dimensionally stable, e.g. is
fused. In a way of example, gallium has a melting point of
29.76.degree. C. When a plating electrolyte is operated at a
temperature of about 30.degree. C. to 40.degree. C., a soluble
gallium electrode in the refreshing tank will be fused. According
to an embodiment of the invention, the refreshing tank comprises a
kettle for holding the fused soluble anode. Said kettle comprises
an electrical contact for contacting the fused soluble anode to the
rectifier. Preferably, the kettle is located at the bottom of the
refreshing tank.
[0026] According to another embodiment of the invention, the
electrode in the plating tank comprises at least an electrode base
body and a screen, said screen reducing the exchange of liquid in
the direct environment of the electrode base body. Advantageously,
due to the reduced exchange of liquid in the direct environment of
the electrode, reactions of components of the electrolyte at the
surface of the electrode, like e.g. decomposition of organic
compounds, are reduced. Said screen can be e.g. a fabric screen or
an inert metal mesh. In a further embodiment, the screen is an
inert metal mesh which is isolated from said electrode base body
and a current is applied to the mesh. By appliance of a current, an
electrostatic barrier is formed which further reduces the exchange
of liquid in the direct environment of the electrode base body.
This further increases the stability of the electrolyte due to the
reduced decomposition of electrolyte compounds.
[0027] In another aspect, the invention relates to a method of
refreshing an electrolyte for electrochemical deposition of a metal
on a substrate, the method comprising the steps of: [0028]
separating at least a partial stream of the electrolyte from a
plating tank and feeding said stream to a refreshing tank, said
refreshing tank comprising a first compartment and a second
compartment, the compartments are separated from each other by a
semi permeable separator, wherein the first compartment comprising
at least one soluble anode of a metal to be deposited on the
substrate and the second compartment comprises at least one inert
electrode; [0029] connecting the inert electrode and the soluble
anode electrically to a rectifier; [0030] setting the current
and/or voltage of the rectifier to a range suitable to
electrochemically dissolve metal from the soluble anode; [0031]
re-feeding at least a partial stream of the electrolyte in the
refreshing tank to the plating tank.
[0032] Advantageously, by the inventive method maintenance of the
plating electrolyte with respect to the concentration of the metal
ion of the metal to be deposited is enabled with substantially not
influencing other features of the plating electrolyte, like e.g.
pH-Value or density.
[0033] According to an embodiment of the inventive method, the
concentration in the electrolyte of the ions of the metal to be
deposited is analyzed and the current and/or voltage of the
rectifier or rectifiers in the refreshing tank is set to maintain a
concentration of the metal to be deposited within a variation limit
of .ltoreq.3% by weight, preferably .ltoreq.2% by weight, most
preferred .ltoreq.1% by weight. Appropriate methods for analyzing
the concentration of the respective metal ions are, e.g.
IR-spectroscopy, AAS (atom absorption spectroscopy), UV-VIS
analysis, or titrimetric analysis.
[0034] In another aspect the invention relates to the use of an
apparatus as described above for the electrochemical deposition of
a metal form an alkaline electrolyte. Preferably, the invention
relates to the use of an apparatus as described above for the
electrochemical deposition of a metal of the group consisting of
gallium, indium, and thallium.
BRIEF DESCRIPTION OF THE FIGURES
[0035] In the following the invention is described in terms of
figures and examples, while the inventive concept is not limited
the examples as described.
[0036] FIG. 1 shows a schematic view of an apparatus according to
the invention;
[0037] FIG. 2 shows a schematic view of an apparatus according to
the invention having a screen shielded electrode;
[0038] FIG. 3 shows a drop section as it can be comprised in an
apparatus according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0039] FIG. 1 shows a schematic view of an apparatus 100 according
to the invention. The apparatus 100 for the electrochemical
deposition of a metal on a substrate 900 comprises a plating tank
110 holding a plating electrolyte 500 and a refreshing tank 400.
The refreshing tank 400 is in fluidic connection 200/210 to the
plating tank 110 for refreshing the plating electrolyte 500. The
plating tank 110 comprises an inert electrode 120 electrically
connected to the substrate 900 by a rectifier 190. For the
deposition of a metal layer on the substrate 900 a current is
applied by the rectifier 190. The refreshing tank 400 comprises a
first compartment 410 and a second compartment 420, wherein the
compartments 410/420 are separated from each other by a semi
permeable separator 430. An appropriate separator 430, e.g. a
membrane, a diaphragm, and a micro-porous wall. The first
compartment 410 comprises at least one soluble anode 440 of a metal
to be deposited on the substrate 900. The second compartment
comprises at least one inert electrode 450. The inert electrode 450
and the soluble anode 440 are electrically connected to a rectifier
490. By appliance of a current between the soluble anode 440 and
the inert electrode 450 metal ions are dissolved from the soluble
anode 440. Due to the fluidic connection 200/210 between the
plating tank 110 and the refreshing tank 400, the metal ion
concentration of the metal to be deposited can be maintained by the
metal ions dissolved from the soluble anode 440. Since the metal of
the soluble anode 440 may not maintain dimensional stability during
operation of the inventive apparatus (it may fuse due to the
operating temperature), the refreshing tank may comprise a kettle
445 to hold the fused soluble anode. The kettle comprises an
electrical contact 446 for contacting the fused soluble anode to
the rectifier 490.
[0040] FIG. 2 shows an embodiment of the inventive apparatus 100 in
which the electrode 120 on the plating tank 110 is covered by a
screen 150. The screen 150 may be a fabric reducing the liquid
exchange in the near environment of the electrode 150. Due to the
reduced liquid exchange, less electrolyte 500 is brought into
direct contact with the surface of the electrode 120. Since
decomposition of other components of the electrolyte 500 take place
on the surface of the electrode 120, the reduced liquid exchange
results in less decomposition of electrolyte components, like e.g.
organic additives. This further increases the stability of the
electrolyte and elongates the electrolytes life time.
[0041] FIG. 3 shows a drop section 800 as it may be comprised in
the fluidic connection 200 and/or 210 connecting the plating tank
110 to the refreshing tank 400. The drop section 800 is capable to
electrically isolate the plating tank 110 from the refreshing tank
400. The drop section 800 comprises an inlet connected to the
fluidic connection 200 or 210. The electrolyte entering the drop
section 800 by the inlet 810 is guided to a strainer 820 separating
the electrolyte into droplets 830. The droplets 830 are collected
in a receiving section 840, to which receiving section 840 an
outlet 850 is connected. The outlet is connected to the fluidic
connection 210 or 200, respectively. In an embodiment of the
invention the apparatus comprises two drop sections 800, one in
each of the fluidic connections 200 and 210.
[0042] When introducing elements of the present invention or the
preferred embodiment(s) thereof, the articles "a", "an", "the" and
"said" are intended to mean that there are one or more of the
elements. The terms "comprising", "including" and "having" are
intended to be inclusive and mean that there may be additional
elements other than the listed elements.
[0043] As various changes could be made in the above without
departing from the scope of the invention, it is intended that all
matter contained in the above description and shown in the
accompanying drawings shall be interpreted as illustrative and not
in a limiting sense. The scope of invention is defined by the
appended claims and modifications to the embodiments above may be
made that do not depart from the scope of the invention.
* * * * *