Plating Anodes
De Nora manufactures a variety of different anode coatings
to meet the varied and demanding performance expectations of the plating
industry. De Nora ’s DSA® anode coatings
are used in many applications, including electro-galvanizing (high speed
continuous sheet strip and wire plating), electrowinning (nickel, cobalt,
copper and zinc), copper foil production, copper plating on printed wire
boards and gravure printing cylinders, tri-valent chrome plating, balancing
anodes for soluble anode baths and in metal recovery cells for waste water
treatment. |
For more detailed information on specific applications
of De Nora anodes click on the links below:
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Electrogalvanizing (EG) Anodes
De Nora ’s DSA® anodes offer
significant advantages over competing soluble and insoluble production
systems. Compared to soluble anode systems in zinc sulfate electrolytes,
DSA® anodes: |
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- Improve plating uniformity
- Reduce energy consumption with smaller anode-to-strip
gaps
- Improve line operations due to better gap stability
- Permit higher plating current densities
Relative to other insoluble anode systems, DSA ®anodes
offer:
- Power cost savings from constant anode-to-strip gap
- Insolubility does not require expensive contaminant
removal
- Better quality product with fewer pollution problems
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| TiFace® is an anode surface treatment developed
by De Nora to repair anodes damaged during operation in
an electro-galvanizing
high-speed, continuous strip, plating line. The treatment,
recovers the integrity of the anode surface thereby allowing
the anodes to be recoated. In addition, the TiFace® treatment
doubled the surface area of the anodes prolonging the life
of the coating. This technology revolutionized the high-speed,
strip steel electrogalvanizing industry. |
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Wire Plating Anodes
DSA® anodes offer a cost effective alternative and superior
product quality for processing electrogalvanized wire. Prior
to DSA® anodes,
soluble zinc or insoluble lead anodes were the only alternatives
for wire plating lines. There were many shortcomings associated
with the use of the zinc and lead anodes. |
| During electrolysis, zinc and lead anodes change their
shape, and in doing so affect the quality and uniformity
of the zinc deposition. As the anodes wear, their geometry
changes, and this results in non-uniform plating distribution
around the circumference of the wire. In many cases, platers
are forced to over plate their product to achieve a minimum
thickness requirement. The adjacent graph, illustrates a
typical circumferential plating distribution from a zinc
anode wire plating line. |
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Due to the inherent shortcoming with the zinc and lead type
wire plating anodes, De Nora undertook an extensive Finite Element
Analysis (FEA) to determine the optimum shape for a wire-plating
anode. The graph below illustrates the results of the FEA evaluation.
The results clearly show that the DSA® channel type anode will
provide the most consistent current distribution around the wire
and hence the most uniform plating. In fact, De Nora ’s customers
have substantiated the analysis confirming that our wire-plating
anode (shown below) yields plating distributions within 0.1%
around the circumference of the wire.
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Electrowinning Anodes
DSA® anodes are gaining acceptance in the electrowinning
industry. Until recently, lead anodes were the accepted
anodes of
choice for electrowinning applications. However, as
industries become more environmentally conscious, alternate
technologies
are being sought. To that end, De Nora developed an
all titanium, DSA® anode for copper electrowinning. The
DSA® anodes also provide a practical alternative to lead
anodes for nickel, zinc, and cobalt electrowinning. The
advantages
of the DSA® anode technology are long life, clean operation,
and power savings over conventional lead anodes. |
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ACID COPPER PLATING ANODES
One of the most basic and widely practiced forms of plating
is acid copper plating. De Nora has been a leader in developing
and patenting anode structures and specialized coatings for this
diversified industry. From the copper foil industry to the rotogravure
printing industry, De Nora has been on the forefront of technological
innovation.
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Copper Foil Plating Anodes
Copper foil is a key component in the manufacture of printed
circuit board industry. Since impedance is affected by the
cross-sectional area of the copper trace, it is imperative
that the thickness of the foil is controlled to 0.1%. |
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The copper foil industry utilizes a radial cell configuration
whereby the gap between the anodes and rotating cathode drum
must be maintained to as little as 5 mm to ensure that a
uniform layer of copper is deposited onto the highly polished
drum. In the past, the copper foil industry used lead anodes
in their radial plating cells. Unfortunately, lead anodes,
while classified as insoluble anodes, are prone to surface
degradation. This irregular surface geometry manifests itself
in non-uniform copper foil deposition. |
In order to meet the stringent gap requirement, De Nora developed
the Flex-in-Place™ (FIP) anode. Unlike lead anodes, the
Flex-in-Place™ anode is dimensionally stable so it’s surface
never changes. In addition, the design of the FIP anode is
such that it allows the anode to conform to the radial configuration
of the cell during installation, and once installed will retain
its shape, and hence, the stringent gap requirement.
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SYNERGY/DT – PWB (Printed Wire Board) Plating Anodes |
| Another type of acid copper plating bath, for printed
wire board plating contain organic additives that promote
grain
refinement and leveling. These organic additives must be
maintained at optimum concentrations to produce quality
product and to thereby maximize yields. Ordinary DSA® anodes
can destroy
the organic additives. To overcome this shortcoming, De Nora
developed its proprietary SYNERGY™ and DT anode coatings.
The SYNERGY™ / DT coating has been shown to be comparable to
standard
soluble copper anodes in limiting the destruction of organic
additives. The SYNERGY™/DT anode has been accepted by the printed
circuit board industry as the only viable alternative to
soluble copper anodes. |
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Rotogravure Cylinder Plating Anodes
De Nora’s SYNERGY™ and DT anodes have also proved to be a viable
alternative, to soluble copper nuggets, in the plating of cylinders
for the
rotogravure printing industry. Today, almost all gravure printing
is done using engraved copper cylinders protected from wear by
the application of a thin electroplate of chromium. The cylinders
(image carrier) used in rotogravure printing can be from three
inches in diameter by two inches wide to three feet in diameter
by 20 feet wide. It is critical that the plated copper is a uniform
thickness across the width of a cylinder because even slight
variations in thickness can impact the way an image is transferred
to the
paper.
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| One industry expert considers the adoption of the SYNERGY™/DT anode technology to be a quantum leap in the rotogravure
industry. Unlike soluble copper anodes, SYNERGY™/DT anodes do
not polarize and can therefore operate at higher current
densities, which can reduce plating times by a factor of
three. The use of SYNERGY™/DT anodes also reduces the amount
of time spent on post plate operations. Due to the non-uniform
dissolution of the copper nuggets, platers need to over plate
in order to achieve a minimum thickness across the width
of a cylinder, thus requiring a polishing step to ensure
a uniform copper thickness. Given that SYNERGY™/DT anodes maintain
their shape, platers are now able to plate to size, thereby
drastically, reducing or eliminating the post plate polishing
operation. |
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Tri-valent Chrome Plating Anodes
In recent years, health and environmental regulations have
become more stringent regarding the use of hexavalent chrome
plating
baths. As a result, platers are being forced to convert to
tri-valent chrome baths whenever possible. SYNERGY™DT anodes are
well suited
for the tri-valent plating baths as they have long life and
are specifically designed to prevent the destruction of the organic
additives in the plating bath chemistries.
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Balancing Anodes
Soluble anodes, including copper, tin, nickel and zinc tend
to operate at less than 100% efficiency. That is, excess
metal ions enter the electrolyte than would be expected
by the faradaic oxidation of the anode. As the concentration
of the metal ion increases, plating quality can diminish
and platers are forced to either dummy plate or dilute
their
plating baths in order to return to an optimal metal ion
concentration. In either case, additional costs are incurred
due to lost production or supplementary waste treatment.
An extremely cost effective method for controlling metal
ion growth is to replace a portion of the soluble anodes
with DSA® anodes. By redirecting a portion of the anodic
current flow to the DSA® anodes, excess metal ions growth can
be controlled.
In general, a good starting point is to redirect approximately
30% of the anodic current to the DSA® anodes.
Since DSA® anodes operate at higher potentials, it may be advisable
to use separate rectification to control the current flow to
the anodes. However, platers have successfully used DSA® anodes
without separate rectification and still had some degree of
success.
Metal Recovery Anodes
In order to meet the environmental challenges that electroplaters
face, De Nora developed a system to recover metals from wastewater
streams. The RETEC™ metal recovery system was developed
to recover such metals as copper, nickel, and chrome from rinse
water streams thereby eliminating the need to precipitate,
filter, and dispose of the unwanted metal hydroxides. The RETEC
systems effectively reduced the metal content of the rinse
water so that it could be reintroduced into the plating loop
or discharged to the environment. De Nora continues to support
the metal recovery industry by supplying RETEC™ metal recovery
anodes. De Nora also manufactures anodes for other metal recovery
systems and can custom fabricate an anode to meet customer
specific needs.
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