Title of Invention

SOM PROCESS FOR FILLING MICRO-BLIND VIAS

Abstract The invention pravides a process for filling µ-blind vias in the manufacture of printed circuit boards, which process comprises the, following Steps (I) providing a dath electrolyte for galvanic plating with metallic coatings comprisings a copper metal salt and optionally organic additives, (II) Operating the bath with direct current density of 0.5 to 10 A/dm2, or current pulses at an effective current density of 0.5 to A/dm2, (III) withdrawing part of the electrolyte from the galvanic bath, (IV) adding an oxidizing agent to the part of the electrolyte which has been withdrawn, (v) optionally irradatiing the with UV light and (vi) recycling the withdrawn part to the galvanic bath and replacing the organic additives destroyed by the oxidaion treatment.
Full Text WO 2004/107834 PCT/EP2004/005874
PROCESS FOR FILLING MICRO-BLIND VIAS
Field of the Invention
The present invention relates to a new process for filling so-called p-blind vias (p-
BVs) in the production of printed circuit boards. Such p-BVs serve to create an
electrically conductive connection between at least two layers of a printed circuit
board. The expression u-BVs is used when the hole diameter of the vias is less
than 0.15 mm (according to IPC) or when the hole density is greater than 1,000
vias/dm3.
Background of the Invention
Under normal manufacturing conditions, copper plating electrolytes are subject to
gradual aging which leads to a deterioration of the quality of the copper deposition
or even to a complete breakdown of the plating process. The useful lifetime of
copper electrolytes for general copper plating ranges from weeks to years. How-
ever, currently known electrolytes used for filling p-BVs generally exhibit very short
useful lifetimes. Typical useful lifetimes may be as low as 100 Ah/I, i.e., weeks to
months. The aging of the electrolytes is generally caused by degradation products
of the additives used therein, by the entrainment of extraneous substances and by
the leaching of basic materials and photoresists.
This aging of electrolytes causes considerable costs because it necessitates the
frequent preparation of fresh solution and the costly disposal of the spent solution.
The filling of p-blind vias differs markedly from other common processes for elec-
troplating printed circuit boards, such as the copper plating of drill holes, in that it
requires enhanced performance with respect to process stability and control. In the
copper plating of drillholes, the useful lifetimes of the plating baths used may be
500 to 1,000 Ah/I. The enhanced performance with respect to process stability
required by electrolytes used not only for metal plating of drill holes and for creat-
ing circuit paths, but also for filling p-BVs may be achieved by specifically adapted
organic additives.

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With the known special copper electrolytes, however, u-BVs can already no longer
be filled after operating times of about 100 Ah/I. After such operating period, the u-
blind vias are only traced rather than filled (see Figure 2). Without further treat-
ment, the electroplating bath would have to be replaced at this stage. For standard
applications, on the contrary, the bath would still provide an acceptable plating
quality.
Several attempts have been made in the prior art to solve the problem of the short
useful lifetimes of copper electroplating baths used for filling u-blind vias:
EP 1 264 918 A1 describes the use of inert anodes in a dummy plating phase in
order to maintain and improve the filling capacity of the electrolyte.
According to EP 1 219 729 A1, chemical substances such as formaldehyde or
oxidizing agents are used in order to improve the useful lifetime of the electrolyte.
According to this document, the mode of action of the additives (in particular, for-
maldehyde) may be explained in terms of an effect on the equilibrium between
brightening agents and their degradation products.
DE 195 25 509 C2 describes the use of an UV/H2O2 oxidation treatment for the re-
use or continued use processing of a bath for electroplating articles with metallic
coatings. In this process, a bath.comprising a metal-specific basic composition and
an added organic brightening agent, which is contaminated with operational deg-
radation products, is subjected to an oxidation treatment in which the destruction
of the, organic brightening agent is accepted. After the oxidation treatment, the
organic brightening agent is re-added to the bath. However, as correctly pointed
out in DE 198 10 859 A1, DE 195 25 509 C2 does not suggest a specific method
for efficient removal of the organic degradation products from the bath. According
to Example 1 of that patent, an electrical energy consumption of about 2,000 kWh
and an amount of 250 litres of H2O2 (35% solution) is required per m3 of the bath
to be, processed in order to obtain sufficient purification. Such a high consumption
of energy and H2O2, however, jeopardizes the economic viability of the process
(see DE 19810 859 A1, column 1, lines 56 to 64).

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Therefore, DE 198 10 859 A1 proposes a process for the treatment of a galvanic
bath, in particular, a galvanic nickel bath, in which the UV oxidation process is
carried out such that a second, lighter phase is formed, which can be separated
simply by a final sorption step or by skimming in a flotation step with subsequent
clarification of the skimmed portion, such that a clear solution is recycled while the
supernatant is discarded; the cyclic process is continued until all organic sub-
stances contained in the bath have been degraded to such an extent that the bath,
after treatment in a final sorption step, has again the basic composition (see claim
1 of DE 198 10 859 A1). Due to the additional sorption step, this process is com-
plicated. Moreover, the process requires a "specific process control" (see column
2, lines 1 and 2), i.e., the process cannot easily be adapted to other baths. Rather,
the process conditions must be selected specifically and the corresponding pa-
rameters need to be determined by laborious preliminary tests.
A further disadvantage of known UV/H2O2 oxidation treatment processes fies in
the fact that they require additional treatment units of considerable volume. For
example, when filling u-blind vias in manufacturing printed circuit boards, typically
10 to 15% of the total electrolyte volume is treated. Accordingly, amounts of elec-
trolyte in the range of 3,000 to 12,000 litres must be treated in huge tanks for peri-
ods of two to three days. A large part of that time, typically about one day, is
needed in order to remove excess H2O2 by means of UV irradiation since excess
H2O2 would deteriorate the performance of the operative electrolyte.
Thus, it is an object of the present invention to provide a process for the galvanic
filling of u-BVs with metals which does not show the aforementioned disadvan-
tages of such processes known in the prior art.
In particular, it is an object of the present invention to provide an improved method
of UV/H2O2 treatment of copper electrolytes for filling u-blind vias
- which allows the treatment to be earned out in a shorter period of time,
- which can be carried out in smaller treatment units,
- which is more efficient and/or

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- which simultaneously allows the copper ion concentration to be controlled and
adjusted.
Description of the Invention
The present invention provides a process for filling u-blind vias comprising the
following steps:
(i) providing a bath electrolyte for galvanic plating with metallic coatings com-
prising a copper metal salt and optionally organic additives,
(ii) operating the bath with direct current at a current density of 0.5 to 10 A/dm2
or current pulses at an effective current density of 0.5 to 10 A/dm2,
(iii) withdrawing part of the electrolyte from the galvanic bath,
(iv) adding an oxidizing agent to the part of the electrolyte which has been with-
drawn,
(v) optionally irradiating the withdrawn electrolyte with UV light and
(vi) recycling the withdrawn* part to the galvanic bath and replacing the organic
additives destroyed by the oxidation treatment.
According to a preferred embodiment of the invention, the oxidizing agent added in
step (iv) of the process is H2O2 and the part of the electrolyte withdrawn from the
bath is passed through a metal dissolution unit containing copper metal before it is
recycled into the galvanic bath in step (vi) of the process.
The invention is explained in more detail by the drawings:
Figure 1 shows the filling capacity of the bath shortly after it has been prepared,
i.e. after an operating time of 2 Ah/I. The layer between the two arrows has been
deposited in the test electrolyte. The layers lying thereunder have been deposited
by the manufacturer of the test plate and play no role in the filling of u-blind vias.
Figure 2 shows the breakdown of the filling capacity after an operating time of
100 Ah/I. The p-blind via is only traced in its shape, i.e., like with a conventional

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electrolytic bath for surface plating, 20 um of copper are deposited in the via and
on the surface.
Figure 3 shows the filling capacity of the electrolyte after an operating time of
100 Ah/I, subsequent UV/H2O2 treatment and replenishing of organic additives to
the desired concentration range.
Figure 4 shows the copper and H2O2 concentrations measured as a function of
time in Experiment A of Example 2 (squares = H2O2; diamonds = Cu).
Figure 5 shows the copper and H2O2 concentrations measured as a function of
time in Experiment B of Example 2 (squares = H2O2; diamonds = Cu).
In the process of the invention, copper is added to the electrolyte as copper sulfate
pentahydrate (CuSO4 * 5 H2O) or as copper sulfate solution. The operational con-
centration range of copper is 8 to 60 g/l copper, preferably 15 to 60 g/l, more pref-
erably 25 to 50 g/l.
Sulfuric acid (H2SO4) is added as a 50 to 96% solution. The operational concentra-
tion range of sulfuric acid is 40 to 300 g/l H2SO4, preferably 130 to 250 g/l.
Chloride is added as sodium chloride (NaCI) or as hydrochloric acid solution (HCI).
The operational concentration range of chloride is 20 to 150 mg/l chloride, pref-
erably 30 to 60 mg/l.
Furthermore, the bath electrolyte preferably comprises brightening agents, level-
ling agents and wetting agents as organic additives.
Wetting agents are conventionally oxygen-containing high molecular weight com-
pounds used in concentrations of 0.005 to 20 g/l, preferably 0.01 to 5 g/l. Exam-
ples for wetting agents which may be used in the process of the invention are
listed in Table 1:

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Table 1. Wetting Agents

carboxymethyl cellulose
nonylphenol polyglycol ether
octandiol bis-(polyalkylene glyco! ether)
octanol polyalkylene glycol ether
oleic acid polyglycol ester
polyethylene glycol polypropylene glycol copolymer
polyethylene glycol
polyethylene glycol dimethyl ether
polypropylene glycol
polyvinyl alcohol
p-naphthol polyglycol ether
stearic acid polyglycol ester .
stearyl alcohol polyglycol ether
Brightening agents used are generally sulfur-containing substances such as those
listed in Table 2:

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Table 2. Sulfur Compounds

3-(benzthiazolyl-2-thio)-propyl suifonic acid, sodium salt
3-mercaptopropane-1-suifonic acid, sodium salt
ethylenedithiodipropyl suifonic acid, sodium salt
bis-(p-sulfophenyl) disulfide, disodium salt
bis-(w-suifobutyl) disulfide, disodium salt
bis-(w-sulfohydroxypropyi) disulfide, disodium salt
bis-(w-sulfopropyl) disulfide, disodium salt
bis-(w-sulfopropyl) sulfide, disodium salt
methyl-(w-sulfopropyl) disulfide, disodium salt
methyl-(w-sulfopropyl) trisulfide, disodium salt
O-ethyl-dithiocarbonic acid S-(w-sulfopropyl) ester, potassium salt
thioglycolic acid
thiophosphoric acid O-ethyl-bis-(w-sulfopropyl) ester, disodium salt
thiophosphoric acid tris-(w-sulfopropyl) ester, trisodium salt
As levelling agents, polymeric nitrogen compounds (for example, polyamines or
polyamides) or nitrogen-containing sulfur compounds, for example, thiourea de-
rivatives or lactam alkoxylates, as described in DE 38 36 521 C2, can be used.
The concentrations of the used substances lie in the range of 0.1 to 100 ppm.
Furthermore, oligomeric and polymeric phenazonium derivates, which are de-
scribed in DE 41 26 502 C1, can also be used. Further substances which are used
for filling p-blind vias are dyes based on an aminotriphenylmethane structure, such
as malachite green, rosalinine or crystal violet.
The bath is operated with direct current at a current density of 0.5 to 10 A/dm2,
preferably 0.5 to 2.5 A/dm2, or with current pulses at an effective current density of
0.5 to 10 A/dm2. The effective current density is calculated according to the follow-
ing formula:

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Improvements of the deposition can be achieved by complex pulse sequences or
by combined pulse- and DC-sequences.
In the process of the invention, an oxidizing agent is added to a part of the electro-
lyte withdrawn from the bath and this part is optionally irradiated with UV light. This
treatment results in a complete destruction of the organic components and,
thereby, in the purification of the basic electrolyte. By subsequently adding the
organic additives, the filling capacity of the electrolyte is maintained and the p-
blind vias can be filled. The process of the invention is significantly more efficient
than the activated charcoal treatment known in the state of the art and does not
require any waste disposal. Therefore, it is not necessary to prepare fresh electro-
lytes, which results in considerable cost savings.
Contrary to the process described in DE 198 10 859 A1, the treatment of copper
plating baths according to the-presenfcinvention does not resultein the formation of
separate phases or unwanted deposits of the reacted organic additives. The spe-
cific additives of the electrolyte allow a transformation of the organic additives to
volatile oxidation products such as CO2 and N2 without formation of residues.
Thus, the process of the invention can be carried out without any means for physi-
cal separation of the oxidization products of the organic additives, in particular, the
process can be carried out without treating the electrolyte by physical separation,
such as filtration or centrifugation, chemisorption or physisorption, either before
the oxidization treatment or thereafter.
The oxidizing agent is preferably used in an amount which is sufficient in order to
reduce the TOC concentration (i.e., the total concentration of organic components)
from 1,000 to 1,500 mg/l down to 50 to 300 mg/l. It can also be useful to use an
amount of oxidizing agent which is sufficient to reduce the TOC concentration to
50% of the value before the oxidation treatment.

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Preferably, H2O2 is used as oxidizing agent. The latter is preferably used as a 30%
aqueous solution, for example in an amount of 3 to 30 ml per litre of plating bath.
Furthermore, oxygen can be used as an oxidizing agent. This can also be the
atmospheric oxygen dissolved in the bath. In the latter case, the separate addition
of an oxidizing agent may become redundant.
In particular, the process of the invention can be carried out with H2O2 as the only
oxidizing agent; thus, it can be carried out without gaseous oxidizing agents such
as ozone.
The irradiation is carried out with devices known per se, for example, UV lamps
with a wave length range of 100 nm to 700 nm, preferably 200 nm to 550 nm. The
radiation power is generally 0.5 to 20 W per litre of bath, preferably 1 to 5 W per
litre of bath.
In the process of the invention, there are preferably used such organic additives
which, upon irradiation, decompose with formation of CO2 and/or N2. The additives
listed in Tables 1 and 2 as well as the aforementioned nitrogen compounds fulfil
tHese requirements.
The anodes used can be, for example, inert anodes without redox system (i.e.,
without Fe2+/3+ system). In the case of acidic copper, DC and AC electrolytes,
soluble anodes can also be used.
The process of the invention can be carried out according to various embodiments
which are described hereinafter:
In the first embodiment, the electrolyte is mixed in a UV chamber with small
amounts of H2O2 (i.e., amount of 0.01 to 0.1 ml/I of H2O2 (30% solution)) and irra-
diated continuously. In this case, the amount of electrolyte which is exchanged
(i.e. withdrawn) is limited because the electrolyte must be free of H2O2 when it
leaves the chamber. In this embodiment of the process of the invention, the
amount of electrolyte exchanged is 10 to 50 l/h and preferably about 30 l/h.

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In a second embodiment of the process of the invention, only a part of the electro-
lyte is withdrawn and treated in a UV chamber with H2O2 and UV light. In general,
the withdrawn part amounts to 10 to 50% of the total volume and preferably about
30% relative to the total amount of the electrolyte.
The duration of the treatment depends on the volume, the amount of oxidizing
agent, the irradiation power of the lamp and the temperature. The plant must be
designed such that the total volume of the electrolyte can be purified over its use-
ful lifetime. The useful lifetime depends on the performance required of the electro-
lyte.
In a third embodiment of the process, no H2O2 treatment is carried out. In this
embodiment, it is accepted that the purification of the electrolyte is not as effective
as in the above two embodiments. However, the process according to the third
embodiment can be carried out continuously.
The use of an oxidizing agent in the first and second embodiment described above
results in an accelerated degradation of organic additives (as compared With the
thrfti embodiment). These Additives must be replaced in order to maintain the
filling capacity of the electrolyte. However, as described above, it is an important
advantage of the process of the invention, that the bath does not need to be re-
placed completely.
According to a particularly preferred embodiment of the process of the invention,
the oxidizing agent added in step (iv) of the process is H2O2 and the part of the
electrolyte withdrawn from the galvanic bath is passed through a metal dissolution
unit containing copper metal after it is subjected to the UV/H2O2 treatment and
before if is recycled into the bath in step (vi) of the process.
A plant for carrying out the process of the invention according to the particularly
preferred embodiment comprises, inter alia, a treatment unit (wherein the UV/H2O2
treatment takes place), a H2O2 dosing unit connected to the treatment unit, and a
metal dissolution unit connected to the treatment unit. The part of the electrolyte
withdrawn from the bath first passes through the treatment unit and subsequently
passes through the metal dissolution unit before it is recycled to the galvanic bath.

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A plant for carrying out the process of the invention can also comprise a cooling
unit.
The metal dissolution unit is generally a container and contains copper metal. The
copper metal can be provided in the form of anode material, pellets, rods or parti-
cles. The metal dissolution unit is preferably a column through which the treated
electrolyte exiting the treatment unit can pass.
A part of the galvanic bath, typically 10 to 15%, is withdrawn and subjected to a
UV/H2O2 treatment, wherein comparatively large amount of H2O2 are added and
the solution is continuously irradiated with UV light in order to decompose the
organic substances in the electrolyte. The decomposition of the organic sub-
stances can be controlled by measuring the TOC concentration, i.e., the total con-
centration of organic components. After the TOC concentration has reached a
predetermined target value, the addition of H2O2 is stopped. At this stage, the
treated electrolyte contains comparatively large amounts of H2p2. The excess
H2O2 must be destroyed in order to ensure that the electrolyte functions properly in
the filling of u-blind vias. For this reason, the H2O2 concentration must typically be
lowered to values of about 0.5 g/l H2O2.
According to the particularly preferred embodiment of the invention, the H2O2
concentration is initially lowered only to a value of about-3 to 5 g/l by further irra-
diation with UV light. The treated electrolyte with an H2O2 concentration in that
range is then passed through the metal dissolution unit where excess H2O2 is
partly destroyed due to the catalytic effect of the surfaces of the copper metal
contained therein with release of oxygen. Furthermore, H2O2 is consumed in the
metal dissolution unit in a redox reaction wherein the H2O2 is reduced to water and
the copper metal is oxidized to copper ion. This latter redox reaction proceeds
according to the following equation:
H2O2 + Cu + 2H+ -> Cu2+ + 2H2O (1)
In the reaction according to this equation, 1 g/l H2O2 can release a theoretical
maximum of 1.85 g/l Cu2+.

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The catalytic destruction of H2O2 at the copper metal surface, on the other hand,
proceeds according to the following equation:
H2O2 -> % O2 + 2 H2O (2)
This reaction is much faster than the destruction of H2O2 by irradiation with UV
light.
The proportions in which H2O2 reacts according to equation (1) and according to
equation (2), respectively, depends on such factors as temperature, pressure,
purity of the electrolyte and nature of the catalytic metal surface.
Thus, passing the treated electrolyte through the metal dissolution unit containing
copper metal results in a significant acceleration of the destruction of excess H2O2
as compared to the destruction by irradiation with UV light alone. In a process
wherein excess H2O2 Is destroyed by irradiation with UV light, this process step
may typically take about one day. In the particularly preferred embodiment of the
process of the invention using the aforementioned metal dissolution unit, the time
required for the destruction of excess H2O2 can be reduced by, for example, 20 to
40%. The actual rate of H2O2 destruction achieved by employing a metal dissolu-
tion unit depends on various factors such as the initial and desired final amount of
H2O2, the nature of the catalytic metal surface, and the flow rate.
As indicated above, the reaction of H2O2 according to the above equation (1) leads
to the release of copper ions, this has the added advantage that the concentration
of copper ion is increased and that the loss of copper ion which occurs not only as
a result of the desired deposition of copper metal on the printed circuit boards to
be plated, but also as a result of the unwanted entrainment of electrolyte, is com-
pensated. This is particularly advantageous when high copper concentrations in
the plating bath, for example 35 to 60 g/l, are employed.
In order to further accelerate the destruction of excess H2O2, it is possible to pro-
vide in the metal dissolution unit or as part thereof additional catalytic surfaces of
materials which catalyse the reaction indicated above in equation (2). Suitable
materials for this purpose are, for example, titanium, ruthenium, rhodium, palla-

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dium, osmium, indium, platinum, titanium oxides, mixed titanium oxides, indium
oxides, mixed indium oxides as well as mixtures of any of these materials.
Examples
The invention will be illustrated further by the following examples:
Example 1 .
An acidic copper plating bath with the following composition is used: copper:
44 g/l, suffuric acid: 130 g/l, chloride: 40 mg/l, basic levelling agent Cupracid
HLF™ (Atotech Deutschland GmbH): 20 ml/I and brightening additive Cupracid
BL™ (Atotech Deutschland GmbH): 0.5 ml/l.
The brightening additive contains a substance from Table 2 and the basic levelling
agent consists of a wetting agent from Table 1 as well as a nitrogen compound
(polyamide).
The bath is operated up to 100 Ah/I until the filling of u-blind vtas breaks down.
Thereafter, the bath is treated with UV/H2O2 and the organic components are
replaced in order to make up the initial composition indicated above. Before and
after the treatment, a test plate is run in order to demonstrate the filling capacity.
The plates are run in a direct current process with 1.5 A/dm2 in a vertical standard
tank with soluble copper anodes. The parameters of the UV/H2O2 treatment were
as follows:
Volume: 6001 copper bath Cupracid HLF™
UVIamp: 12kW;200nm
H2O2 dosing: 27 l/h or 14 l/h
Electrolyte circulation: 10.5 m3/h
TOC before treatment: 1180 mg/l
TOC after treatment: 81 mg/l
Figures 1 to 3 show the sequence of tests.

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Example 2
A series of four experiments (A to D) was carried out as follows:
In Experiment A, 5 ml/l H2O2 solution (35%) and 1 ml/I levelling agent Cupracid
HLF™ were added to 2801 of copper electrolyte solution. In a first bypass, the
electrolyte solution was passed through a UV reactor operated at an irradiation
power of 1 kW (Enviolett S™ manufactured by A.C.K.). The turnover through the
UV reactor was 6501/h.
To evaluate the process conditions, copper and H2O2 concentrations were deter-
mined at intervals of one hour (copper was determined volumetrically with EDTA
solution and H2O2 was determined volumetrically with KMnO4 solution). The cop-
per and H2O2 concentrations measured at various times are shown in Table 3
below and in Figure 4.
In Experiment B, the process was run in the same way as in Experiment A, except,
that, in a second bypass, the electrolyte solution was additionally passed, in paral-
lel, through a copper column filled with 6 kg copper pellets (length 18 mm, diame-
ter 7 mm, total surface about 40 dm2). The copper column had a diameter of
90 mm, a length of 250 mm and a capacity of about 1.5 I. The turnover through
the copper column was 3601/h. The copper and H2O2 concentrations were meas-
ured as before and are also shown in Table 3 and in Figure 5.
Without the copper column (Experiment A), the H2O2 concentration was lowered
over a period of seven hours from 5 g/1 only to 3.2 g/l while the copper concentra-
tion remained constant at 30 g/l.
With the copper column (Experiment B), the H2O2 concentration was reduced over
a period of seven hours from 5 g/l to 1.4 g/l, whereas the copper concentration
increased from 34 g/l by 4 g/l to 38 g/l. Reducing the H2O2 concentration from 5 g/l
to 3 g/l required a total treatment time of three hours. Over this three hour period,
the copper concentration increased by 0.8 g/l.

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Thus, the time required to reduce the H2O2 concentration from 5 g/l to 3 g/l was
reduced by four hours (i.e., by 57%) when a copper column was used. Over the
same time period, a slight increase in the copper concentration was observed.
In Experiment C, the process was run in the same way as in Experiment B, except
that the amount of copper pellets was reduced to 3 kg. Furthermore, in Experiment
D, the process was run in the same way as in Experiment C, except that a titanium
grating (0.5 m2) coated with mixed iridium oxide was additionally provided inside
the copper column. The concentrations of H2O2 and copper were again measured
at regular intervals. The results are also shown in Table 3.
With the additional grating coated with mixed iridium oxide, a faster and greater
decrease in the H2O2 concentration is achieved than without the grating. At the
same time, the partial replacement of copper pellets by the titanium grating coated
with mixed iridium oxide can make the increase in the copper concentration
slower.

Table 3. Copper and H2O2 concentrations measured in Experiments A to D
Time A B c D
' (Without Cu) (6kglCu) (3kgCu) (3 kg Cu + Ti)
concentra-tion of Cu(g/l) after t*Oh 30.0 34.0 34.0 34.0
t = 3h HS 34.0 34.0
t = 7h 30.0 38.0 34.6 34.5
concentra-tion ofH2O2 (g/l)after. t==Qh 5.Q 5.0 5.0 5.0
t = 3h 3.0 3.9 3.2
t*7"h 3.2 LA 3.0 2.1

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PCT/EP2004/005874 13404WO CB/av/mi
CLAIMS
1. Process for filling u-blind vias comprising the following steps:
(I) providing a bath electrolyte for galvanic plating with metallic coatings
comprising a copper metal salt and optionally organic additives,
(ii) operating the bath with direct current at a current density of 0.5 to
10 A/dm2 or current pulses at an effective current density of 0.5 to
10 A/dm2,
(iii) withdrawing part of the electrolyte from the galvanic bath,
(iv) adding an oxidizing agent to the part of the electrolyte which has been
withdrawn,
(v) optionally irradiating the withdrawn electrolyte with UV light and
(vi) recycling the withdrawn part to the galvanic bath and replacing the or-
ganic additives destroyed by the oxidation treatment,
wherein the oxidizing agent added in step (iv) is H2O2 and the part of the
electrolyte withdrawn from the bath is passed through a metal dissolution unit
containing copper metal before it is recycled into the bath in step (vi) of the
process.
2. Process according to claim 1 wherein the bath electrolyte for galvanic plating
comprises 8 to 60 g/l copper, 40 to 300 g/l sulfuric acid and 20 to 150 mg/l
chloride, and the organic additives comprise brightening agents, wetting
agents and further additives selected from polyamides, polyamines, lactam
alkoxylates, thioureas, oligomeric and polymeric phenazonium derivates and
aminotriphenylmethane dyes.

03-02-2005 EP0405874
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3. Process according to claim 1 or 2 wherein the oxidizing agent is added in an
amount which is sufficient in order to reduce the TOC concentration from
1,000 to 1,500 mg/l down to 50 to 300 mg/l.
4. Process according to claim 1 wherein the irradiation is earned out at a wave
length in the range of 200 nm to 550 nm.
5. Process according to claim 1 wherein the irradiation power is 0.5 to 20 W per
litre of bath, preferably 1 to 5 W per litre of bath.
6. Process according to claim 1 wherein polymers which form CO2 upon irradia-
tion are used as organic additives.
7. Process according to claim 1 wherein an acidic copper electrolyte is used as
electrolyte.
8. Process according to claim 1 wherein the galvanic bath is operated with inert
anodes without redox system.
9. Process according to claim 1 wherein an acidic copper electrolyte is used as
electrolyte and soluble anodes are used as anodes.
10. Process according to claim 1 wherein the copper metal in the metal dissolu-
tion unit is in the form of anode material, pellets, rods or particles.
11. Process according to claim 1 wherein the metal dissolution unit further con-
tains catalytic surfaces comprising a material selected from the group con-
sisting of titanium, ruthenium, rhodium, palladium, osmium, iridium, platinum,
titanium oxides, mixed titanium oxides, iridium oxides, mixed iridium oxides
as well as mixtures of any of these materials.
12. Process according to claim 1 wherein the metal dissolution unit is a column
through which the treated part of the electrolyte withdrawn from the bath is
passed.

The invention pravides a process for filling µ-blind vias in the manufacture of printed circuit boards, which process
comprises the, following Steps (I) providing a dath electrolyte for galvanic plating with metallic coatings comprisings a copper metal
salt and optionally organic additives, (II) Operating the bath with direct current density of 0.5 to 10 A/dm2, or current pulses at an
effective current density of 0.5 to A/dm2, (III) withdrawing part of the electrolyte from the galvanic bath, (IV) adding an oxidizing
agent to the part of the electrolyte which has been withdrawn, (v) optionally irradatiing the with UV light and
(vi) recycling the withdrawn part to the galvanic bath and replacing the organic additives destroyed by the oxidaion treatment.

Documents:

02237-kolnp-2005-abstract.pdf

02237-kolnp-2005-claims.pdf

02237-kolnp-2005-description complete.pdf

02237-kolnp-2005-drawings.pdf

02237-kolnp-2005-form 1.pdf

02237-kolnp-2005-form 3.pdf

02237-kolnp-2005-form 5.pdf

02237-kolnp-2005-international publication.pdf

2237-KOLNP-2005-(19-12-2011)-ABSTRACT.pdf

2237-KOLNP-2005-(19-12-2011)-CORRESPONDENCE.pdf

2237-KOLNP-2005-(19-12-2011)-FORM-1.pdf

2237-KOLNP-2005-(19-12-2011)-FORM-2.pdf

2237-KOLNP-2005-(19-12-2011)-OTHERS.pdf

2237-KOLNP-2005-ABSTRACT 1.1.pdf

2237-KOLNP-2005-ABSTRACT 1.2.pdf

2237-KOLNP-2005-AMENDED CLAIMS.pdf

2237-KOLNP-2005-CANCELLED PAGES.pdf

2237-KOLNP-2005-CORRESPONDENCE 1.1.pdf

2237-KOLNP-2005-CORRESPONDENCE 1.2.pdf

2237-KOLNP-2005-CORRESPONDENCE-1.1.pdf

2237-KOLNP-2005-CORRESPONDENCE.pdf

2237-KOLNP-2005-DESCRIPTION (COMPLETE) 1.1.pdf

2237-KOLNP-2005-DRAWINGS 1.1.pdf

2237-KOLNP-2005-FORM 1-1.2.pdf

2237-KOLNP-2005-FORM 1.1.1.pdf

2237-KOLNP-2005-FORM 2-1.1.pdf

2237-KOLNP-2005-FORM 2.pdf

2237-KOLNP-2005-FORM 27.pdf

2237-KOLNP-2005-FORM 3.1.1.pdf

2237-KOLNP-2005-FORM-27.pdf

2237-KOLNP-2005-OTHERS 1.2.pdf

2237-KOLNP-2005-OTHERS-1.1.pdf

2237-KOLNP-2005-OTHERS.pdf

2237-KOLNP-2005-PA.pdf

2237-KOLNP-2005-PETITION UNDER RULE 137.pdf

2237-KOLNP-2005-REPLY TO EXAMINATION REPORT-1.1.pdf

2237-KOLNP-2005-REPLY TO EXAMINATION REPORT.pdf


Patent Number 244700
Indian Patent Application Number 2237/KOLNP/2005
PG Journal Number 52/2010
Publication Date 24-Dec-2010
Grant Date 15-Dec-2010
Date of Filing 10-Nov-2005
Name of Patentee ATOTECH DEUTSCHIAND GMBH
Applicant Address ERASMURASSE 20, 10553, BERLIN GERMANY
Inventors:
# Inventor's Name Inventor's Address
1 ROELFS BERND OTTMAR LINDENALLEE 25, 14050 BERLIN, GERMANY
2 OZKOK AKIF MULLERSTRASSE 65 A, 13349 BERLIN GERMANY
3 IGEL OSWALD KARL-LIEBKNECHT-STRASSE 100, 14612 FALKENSEE, GERMANY
4 GENTH HERKO FEWLDSTRASSE 10, 13355 BERLIN, GERMANY
5 MATEJAT KAI-JENS LAMMERWEIDE 6, 16727 VEHLEFANZ GERMANY
PCT International Classification Number H05K 3/42
PCT International Application Number PCT/EP2004/005874
PCT International Filing date 2004-06-01
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 103 25 101.4 2003-06-03 Germany