Note: Descriptions are shown in the official language in which they were submitted.
CA 02349156 2001-05-24
ELECTROPLATING METHOD USING COMBINATION OF VIBRATIONAL FLOW
l:N PLATING BATH AND PLATING CURRFNT OF PULSE
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plating method, and particularly
to a plating mei;hod using a specific combination of a physical condition
of a plating bal;h and an electric condition of plating current.
2. Description of the Related Art
l~0 An elect;roplating technique of forming a film of electrically
conductive material on the surface of an article has been broadly used in
the manufacturing industry of articles such as electronic parts, etc.
Particularly, in order to satisfy requirements of miniaturization and high
functionality to electronic parts, conductive patterns to be formed on the
l~5 surfaces (containing the inner surface of through hole, the inner surface
of blind via hole) of articles have been required to be formed finely.
For example, the microstructure design of wiring patterns is
promoted in connection with decrease of the pitches of input/output
terminals due to the high-integration design of semiconductor devices, and
a?0 in connection with this promotion, it has been required that the through
hole and the blind via hole acre designed to have an inner diameter of
100 ~,m or less, further 50 y m or less, still further 30 a m or less.
Further, a large aspect ratio of 5 or more, further 8 or more has been
required to the through hole and the blind via hole.
.?5 For example, in order to reduce the capacity between wires which
occurs due to the microstructure design of wires required in connection
with the high-integration design, copper wires are used in place of
aluminum wires which have been hitherto used, and a damascene method using
electroplating i;o form copper multi-layered wires has been used. In this
'.30 method, it has been required to perform copper deposition in very small
CA 02349156 2001-05-24
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blind via holes having the inner diameter of 1 ~,m or less.
Further, it has been required that a pair of electrode films are
formed on the surface of a chip part having a dimension of about 0.3mm.
Particularly, the applicant of this application has proposed a
plating method that is effectively applicable to articles having
microstructured parts such as fine holes, etc. (see JP(A)-11-189880).
According to this method, vibrational flow induced in a plating bath and
bubbling induced by a diffusing pipe are used in combination. This method
is also effectively applicable to electroless plating as well as
electroplating.
However, in this method, it is required to dispose the diffusing
pipe in a plating tank in which the plating bath is accommodated, and also
it is required t~o establish an air pipe to the diffusing pipe. Therefore,
the amount of the plating bath and the dimension of the plating tank must
be relatively increased, so that the plating apparatus itself must be
designed in large size.
Besides, DC power source is generally used as power source for the
electroplating. In order to enhance the quality of plating films, there has
been proposed a technique of carrying out plating while the plating current
is periodically varied. In this method, positive-polarity current and
negative-polarity current alternately flows. That is, a plating film is
temporarily formed by supplying the positive-polarity current, and then
projecting portions of minute uneven portions on the surface of the plating
film thus formed are concentratively and partially melted by supplying the
negative-polarity current. They above operation is repeated to achieve a
high-quality plating film that; has a flat surface and no defects such as
minute voids or the like. According to this method, however, the surface
portion of the plating film which is temporarily formed is removed and thus
this method has a disadvantages in enhancement of the film forming speed
3iD (that is, the enlhanc~nent of t;he plating treatment speed) .
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It is a recent tendency that conductive patterns are designed in
a further microstructure design, and when a plating film having such a
conductive pattern is formed, defects or unevenness in film thickness is
liable to occur. Therefore, it has been more and more difficult to keep the
excellent qualiity of the plating film.
The app:iicant of this application has also proposed a plating
method of carrying out chrome-plating while vibrationally stirring the
plating bath, and a plating method of accommodating many articles to be
plated (hereinafter referred to as "plating target articles") in a barrel
ll0 and carrying oui~ chrome-plating while vibrationally stirring the plating
bath (see JP(A)-7-54192 and JIP(A)-6-330395).
However, these methods use direct current as plating current, and
these publications have no specific disclosure on the application of these
methods to minute plating target articles such as articles each of which
l.5 has a width (thE~ dimension in the traverse direction to the longitudinal
direction) of 5rrun or less, for example, 0.3 to l.Omm. In the barrel plating
process for these minute plating target articles, the plating target
articles are overlapped with one another in the barrel, and thus the
distribution of plating liquid to desired plating film forming portions of
2.0 the plating target articles is extremely lowered. Therefore, there are a
lot of technical difficulty for these minute plating target articles beyond
comparison with plating targei~ articles having relatively large widths,
and a further improvement music be made in point of the film forming speed
and the evenness of film thickness.
SUI~R~1ARY OF THE INVENTION
Therefore, an object of the present invention is to provide a
plating method which can form a plating film having a microstructured
conductive pattern with high quality so that the plating film has no defect
and is not uneven in film thickness.
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Another object of the present invention is to provide a plating
method which can form a high-quality plating film having a microstructured
conductive pattern at high speed.
Another object of the present invention is to provide a plating
method which can efficiently form a high-quality plating film having a
microstructured conductive pattern by a relatively small apparatus.
In order to attain the above objects, according to the present
invention, there is provided an electroplating method, characterized in
that a plating t=arget article disposed so as to be in contact with plating
l.0 bath is set as a cathode while a metal member disposed so as to be in
contact with the plating bath is set as an anode, and a voltage is applied
between the cathode and the anode while vibrational flow is induced by
vibrating vibrat;ional vanes which are fixed in one-stage or multi-stage
style to a vibrating rod vibrating in the plating bath interlockingly with
vibration generating means, wherein plating current flowing from the anode
through the plating bath to the cathode is pulsed and alternately set to
one of a first sctate where the plating current keeps a first value I1-for a
first time T1 and a second state where the plating current keeps a second
value I2 having the same polarity as the first value Il for a second time
T2, the first value Il being five or more times larger than the secor~
value I2, and the first time 'Tl being three or more times longer than the
second time T2.
In an aspect of the present invention, the first value I1 is 6 to
times as large as the second value I2, and the first time T1 is 4 to 25
25 times as long as: the second tame T2. In an aspect of the present
invention,
the first value I1 is set to 0.01 to 300 seconds. In an aspect of the
present invention, the vibrat:ional vanes are vibrated at an amplitude of
0.05 to lO.Omm and a vibration frequency of 200 to 1500 revolutions per
minute. In an aspect of the pr~esent invention, the vibrational vanes are
vibrated so that. the vibrational flow of the plating bath has a
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three-dimensional flow rate of 150mm/second or more. In an aspect of the
present invention, the vibration generating means vibrates at 10 to 500 Hz.
In an aspect of the present invention, the plating target article
is vibrated at an amplitude of 0.05 to S.Omm and a vibration frequency of
100 to 300 revolutions per minute. In an aspect of the present invention,
the plating target article is swung at a swinging width of 10 to 100mm and
a swinging frequency of 10 to ;30 times per minute.
In an a:~pect of the present invention, the plating target article
has a face to be plated having a microstructure of a dimension of 50 a m or
ll0 less.
In an a:~pect of the present invention, a plurality of plating
target articles are accommodated in a holding container, the holding
container having small holes through which liquid of the plating bath is
allowed to pass and being equipped with an electrically conductive member
l.5 which is brought; into contact with the plating target articles to make
current flow through the plating target articles, and wherein the holding
container is rotated around the rotational center corresponding to a
non-vertical direction in the plating bath to roll the plating target
articles in said holding cont"~iner to thereby repeat the contact and
~'.0 separation betwE~en each of the plating target articles arxi the
electrically
conductive member.
In an aspect of the present invention, the width of each of the
plating target articles is equal to 5mm or less.
According to the electroplating method of the present invention,
i;5 even when a plating conductive pattern is minute, a plating film having
uniformity in thickness and no defect can be foamed with high quality.
Further, according to the preaent invention, a high-quality plating film
of microstrvctured conductive pattern can be obtained at high speed. Still
further, according to the present invention, a high-quality plating film
;t0 of microstructured conductive pattern can be efficiently obtained by a
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relatively small apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 ins a cross-sectional view showing the construction of a
plating apparatus to which a first embodiment of a plating method according
to the present invention is applied;
Fig. 2 is a cross-sectional view showing the construction of the
plating apparatus to which the first embodiment of the plating method
according to the present invention is applied;
l.0 Fig. 3 i.s a plan view showing the construction of the plating
apparatus to which the first .embodiment of the plating method according to
the present invention is applied;
Fig. 4 i.s an enlarged cross-sectional view showing the fixing
portion of a vibration transmitting rod to a vibrating member;
Fig. 5 i.s an enlarged cross-sectional view of the fixing portion
of a vibrating vane to the vilbration transmitting rod;
Fig. 6 is a diagram showing a modification of the fixing portion of
the vibrating vane to the vibration transmitting rod;
Fig. 7 i.s a cross-sectional view showing a modification of fixing
2.0 a plating target: article to a cathode bus bar;
Fig. 8 is a graph showing variation of plating current flowing
through the plating target article;
Fig. 9 is a cross-sectional view showing the construction of a
plating apparatus to which a second embodiment of the plating method of the
present invention is applied;
Fig. 10 is a cross-sectional view showing the construction of the
plating apparatus to which the second embodiment of the plating method of
the present invention is applied;
Fig. 11 is a plan view showing the construction of the plating
apparatus to which the second embodiment of the plating method of the
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present invention is applied;
Fig. 12 is a cross-sectional view showing a plating apparatus used
for the embodiment of the plating method of the present invention;
Fig. 13 is a partially-notched plan view of the plating apparatus
of Fig. 12;
Fig. 14 is a cross-sectional view showing the fixing of a
vibrational flow inducing portion constituting the plating apparatus to a
plating tank;
Fig. 15 is a cross-sectional view showing the fixing of the
~~0 vibrational flow inducing portion constituting the plating apparatus to
the plating tank;
Fig. 16 is a plan view showing the fixing of the vibrational flow
inducing portion constituting the plating apparatus to the plating tank;
Figs. li'A to 17C are plan views showing a laminated member;
l.5 Figs. 18A and 18B are cross-sectional views showing a state that
the top portion of the plating tank is closed by the laminated member;
Figs. 19A to 19E are diagrams showing the laminated memeber;
Fig. 20 is a graph showing variation of plating current flowing
through a plating target article;
i.0 Fig. 21 is a cross-secaional view showing a modification of the
vibrational flow inducing portion;
Fig. 22 is a plan view showing the vibrational flow inducing
portion of Fig. 21; and
Fig. 23 is a diagram showing an example of a power source for pulse
25 plating.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIM~~ffS
Preferred embodiments according to the present invention will be
described hereunder with reference to the accompanying drawings. In the
30 figures, the members or portions having the same functions are represented
CA 02349156 2001-05-24
by the same reference numerals.
Figs. 1 and 2 are cross-sectional views showing the construction
of a plating apparatus to which a first embodiment of a plating method
according to the present invention will be applied, and Fig. 3 is a plan
view of the plating apparatus shown in Figs. 1 and 2.
In these figures, reference numeral 12 represents a plating tank,
and plating batik 14 is stocked in the plating tank 12. Reference numeral 16
represents a vibrational flow generator or vibrational flow inducing
portion. The vibrational flow generator 16 includes a base stand 16a fixed
:l0 to the plating tank 12 through a vibration proof rubber, coil springs 16b
serving as vibration absorption members which are fixed to the base stand at
the lower ends 'thereof, a vibrating member 16c fixed to the upper ends of
the coil springy 16b, a vibrating motor 16d serving as vibration generating
means fixed to the vibrating member 16c, a vibration transmitting rod 16e
:l5 fixed to the vibrating member at the upper end thereof, and vibrating
vanes
16f fixed to the lower half portion of the vibration transmitting rod so as
to be immersed :in the plating bath 14. Further, a rod-shaped guide member
may be disposed in each of the coil springs 16b as shown in Fig. 12.
The vibrating motor 16d vibrates at frequencies of 10 to 500Hz,
a?0 preferably 20 W 60Hz, more preferably 30 to 50Hz under the control based
on an inverter, for example, 'The vibration generated by the vibrating motor
16d is transmitted through the vibrating member 16c and the vibration
transmitting rod 16e to the vibrating vanes 16f. The tip edge of each
vibrating vane :i6f vibrates at a desired oscillation frequency in the
25 plating bath 14. The vibration is generated as if each vibrating vane 16f
bends from the base portion fixed to the vibration transmitting rod 16e
toward the tip Edge thereof. 'The amplitude and frequency of the vibration
are different from those of the vibrating motor 16d, and determined in
accordance with the dynamical characteristics of the vibration transmission
30 passage and the mutual action characteristics between each vibrating vane
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and the plating bath 14. In t;he present invention, the amplitude is
preferably in the range of 0.05 to lO.Omm, for example 0.1 to lO.Omm, and
the frequency is preferably iin the range of 200 to 1500 revolutions per
minute, for example 200 to 8010 revolutions per minute.
Fig. 4 :is an enlarged cross-sectional view showing the fixing
portion of the vibration transmitting rod 16e to the vibrating member 16c.
Nuts 1611, 16i2~ 16i3, 16i4 an~e fixed through vibrational stress dispersing
members 16g1, lEig2 and washers 16h1, 16h2 to a male screw portion of the
upper portion of the vibration transmitting rod 16e from both the upper and
:~0 lower sides of i;he vibrating member 16c. The vibrational stress
dispersing
members 1681, lfig2 are formed of rubber, for example.
Fig. 5 is an enlarged cross-sectional view showing the fixing
portions of the vibrating vanes 16f to the vibration transmitting rod 16e.
Vibrating vane fixing members 16j are disposed at both the upper and lower
1.5 sides of each of seven vibrating vanes 16f. Further, a spacer ring 16k for
setting the interval between the vibrating vanes 16f is interposed between
the neighboring vibrating vanes 16f through the fixing members 16j. Nuts
16m which are fitted to male screws formed on the vibration transmitting
rod 16e are dis~bsed at the upper side of the uppermost vibrating vane 16f
~;0 and the lower side of the lowermost vibrating vane 16f.
Fig. 6 i.s a diagram showing a modification of the fixing portions
of the vibratin~; vanes 16f to the vibration transmitting rod 16e.
In this modification, each vibrating vane 16f is individually fixed
to the vibration transmitting rod 16e by nuts 16n disposed at both the
i;5 upper and lower sides of each vibrating vane 16f. An elastic member sheet
16p formed of fluororesin or fluorinated rubber may be interposed between
each vibrating wne 16f and the fixing member 16j to prevent the vibrating
vanes 16f from teeing damaged.
As shown in Fig. 6, the lower surface (press face) of the upper
~~0 fixing member 16~j is designed to have a convex cylindrical shape, and the
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upper surface (press face) of the lower fixing member 16j is designed to
have a concave <;ylindrical shape corresponding to the above convex
cylindrical shape. Therefore, a part of each vibrating vane 16f which is
pressed by the fixing members 16,j from the upper and lower sides is bent,
and the tip portion of the vibrating vane 16f intersects the horizontal
plane at an angle a. The ang:Le a may be set to a value in the range from
-30 ° to 30 ° , preferably in the range from -20° to 20
° . Particularly,
the angle a is preferably seat to a value in the range from -30 ° to -5
°
or from 5 ° to 30 ° , preferably in the range from -20°
to -10° or from 10°
to 20 ° . When t;he press faces of the fixing members 16j are the plane
face, the angle a is set to 0° . The angle a is not necessarily equal
to
the same value among all the vibrating vanes 16f. For example, as shown in
Fig. 1, a negative angle value may be set to one or two lower vibrating
vanes 16f (i.e., the vibrating vanes 16f are bent downwardly, that is, they
are bent in the opposite direcaion to that of Fig. 6) while a positive
angle value is set to the other vibrating vanes 16f (i.e., they are bent in
the same direction as that of Fig. 6).
The vibrating vanes lEif may be formed of elastic metal plates,
synthetic resin plates or rubber plates. The thickness of each vibrating
vane 16f is set so that the trip edge portion of each vibrating vane 16f
exhibits a flutter phenomenon (a state as if the vibrating vanes are
fluttered). When the vibrating vanes 16f are formed of metal plates such as
stainless steel plate or the hike, the thickness thereof may be set to 0.2
to 2mm. When the vibrating vanes 16f are formed of synthetic resin plates
or rubber plates, the thickness thereof may be set to 0.5 to lOmm.
In Figs. 1 to 3, a swinging motor 20 is connected to a swinging
frame 24 through a link rod 2~'.. The swinging frame 24 is disposed so as to
be reciprocally movable in the horizontal direction (the right-and-left
direction in Fig. 1) on rails 26. A vibrating motor 28 is fixed to the
swinging frame 24. Further, a cathode bus bar 30 and an anode bus bar 32
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are fixed to the swinging frame 24 while they are kept insulated from the
swinging frame ;?4, and they are connected to a negative-electrode terminal
and a positive-electrode terminal of a power source circuit 34. The power
source circuit 34 can generate a rectangular voltage from an AC voltage.
Such a power source circuit has a rectifying circuit using a transistor and
it is known as a pulse power ;source device.
In the present invention, a circuit for rectifying AC current
(containing adding DC components) and then outputting the rectified current
is used as the power source circuit (power source device) used to generate
:l0 plating current. As such a power source device or rectifier may be used a
transistor adjustment type power source, a dropper type power source, a
switching power source, a silicon rectifier, an SCR rectifier, a
high-frequency i:ype rectifier" an inverter digital control type rectifier
(for example, Power Master produced by Chuo Seisakusho Co., Ltd.), KTS
l.5 series produced by Sansha Denki Seisakusho Co., Ltd., an RCV power source
produced by Shii;oku Denki Co.,. Ltd., a device which comprises a switching
regulator type power source and a transistor switch and supplies
rectangular pul~~e current by switching on/off the transistor switch, a
high-frequency :;witching power saurce (in which AC current is converted to
c:0 DC current through a diode, then high frequency of 20 to 30IQ-Iz are
applied
to a transformer to carry out the rectification and smoothing again, and
then the output is taken out), a PR type rectifier, a high-frequency
control type high-speed pulse PR power source (for example, HiPR series
produced by Chiyoda Co., Ltd. or the like.
i.5 Here, the current waveform will be described. In order to implement
both the increase in plating speed and the improvement of the
characteristics of plating films, it is important to select the wave form
of plating current. The voltage and current conditions required for the
electroplating are varied in accordance with the type of plating, the
f.0 composition of plating bath arxi the dimension of the plating tank, and
thus
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they cannot be sweepingly specified. However, if the plating voltage is set
to a DC voltage of 2 to 15V, it can sufficiently cover the whole at
present. Therefore, four kinds of rated output voltage of the plating DC
current (6V, 8V" 12V, 15V) are standardized in the industry. The voltage
below the above rated can be adjusted, and thus a power source for
generating a railed voltage which has a slightly extra voltage with respect
to a desired voltage value required for plating is preferably selected. In
the industry, the rated output current from 500A, 1000A till about 2000A to
10000A are standardized as the rated output current of the power source,
1.0 and the other current values are provided in the form of production to
order. It is better that the required current capacity of the power source
is determined a~~ the desired current density of plating target article x
the surface area of the plating target article in accordance with the type
and surface area of the plating target article, and a proper standard power
source satisfying the above required current capacity is selected.
The pulse wave is originally defined as a pulse having a
sufficiently shorter width w i~tran its period T. However, this definition is
not strict. The pulse wave contains waves other than the square wave. The
operating speed of elements used in a pulse circuit is increased, and the
pulse width of ns (10-9s) or less can be treated. As the pulse width is
smaller, it is more difficult to keep the front and rear edges of the waves
sharp. This is because the pulse contains high-frequency components.
A saw-tooth wave, a ramp wave, a triangular wave, a composite
wave, a rectangular wave (square wave), etc. are known as the types of
pulse waves, and particularly the present invention preferably uses the
rectangular wave in consideration of the efficiency of electricity and
smoothing.
Fig. 23 ;shows an example of a pulse plating power source. As shown
in Fig. 23, it contains a switching regulator type DC power source and a
transistor switch, and rectangular pulse current is supplied to a load by
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switching on/off the transistor switch at high speed.
The cathode bus bar 30 is mechanically and electrically connected
to the upper portion of an electrically conductive holding member 40 for
holding a plating target article X. The lower portion of the plating target
article holding member 40 is immersed in the plating bath 14, and the
plating target article X is electrically connected to this portion and held
by a clamp or the like. As not shown, an anode metal member (for example,
which is accommodated in a plastic basket) is mechanically and electrically
connected to the anode bus ba:r 32, and the lower portion thereof is
:l0 immersed in the plating bath 14. Various well-known methods, shapes and
structures may be used as the methods of fixing the plating target article
to the cathode bus bar and fixing the anode metal member to the anode bus
bar and the shapes and structures of the cathode bus bar and the anode bus
bar.
J.5 Fig. 7 i_s a cross-sectional view showing a modification of the
fixing of the plating target article to the cathode bus bar. In this
modification, the electrically conductive holding member 40 is designed to
have a hook portion 40a which is provided at the upper portion thereof and
fitted to the cathode bus bar 30, a clamp portion 40b which is provided at
c;0 the lower portion thereof and pinches the plating target article X, and a
compression spring 40c for generating the clamp force of the clamp portion.
In Figs. 1 to 3, the swinging frame 24 and the holding member 40,
and further the plating targeit article X secured to the swinging frame 24
and the holding member 40 are swung at a swinging width of 10 to 100mm and
t.5 a swinging frequency of 10 to 30 times per minute by actuating the
swinging
motor 20. Further, the vibrating motor 28 is vibrated at a frequency of 10
to 60Hz, preferably at a frequency of 20 to 35Hz under the control using an
inverter, for example. The vibration occurring in the vibrating motor 28 is
transmitted to the plating target article X through the swinging frame 24
f.0 and the holding member 40, whereby the plating target article X is
vibrated
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at an amplitude of 0.05 to 5.0mm, for example 0.1 to S.Omm, and a vibration
frequency of lOCI to 300 revolutions per minute.
Fig. 8 is a graph showing the variation of plating current (current
density) flowing through the plating target article X due to a voltage
applied across t:he cathode bus bar 30 and the anode bus bar 32 by the power
source circuit ~~4.
As shown in Fig. 8, the plating current is shaped to have such a
rectangular pulse train that a first state where the plating current keeps
a first value I1 for a first ,time T1 and a second state where the plating
current keeps a second value :l2 (<I1) for a second time T2 appear
alternately. Here, the first value I1 and the second value I2 have the same
polarity. I1 is five or more i~times as large as I2 (for example, six or more
times, e.g. six times to 25 tames), preferably eight times to 20 times. T1
is three or more times as long as T2 (for example, four or more times,
e.g. 4 times to 25 times), preferably six times to 20 times. Such plating
current and the vibrational flow of the plating bath 14 caused by the
vibrational flow generator 16 are combined with each other, whereby
excellent quality and a high :Film forming speed can be achieved even for
the plating of minute conductive structure patterns.
The first value I1 and the first time T1 are properly determined in
accordance with the type of plating (for example, copper sulfate plating,
copper cyanide plating, copper pyrophosphate plating, nickel plating, black
nickel plating, nickel sulfam~te plating, chromium plating, zinc cyanide
plating, no cyanide zinc plating, alkaline tin plating, acidic tin plating,
silver plating, gold cyanide plating, acidic gold plating, copper-zinc
alloy plating, nickel-iron alloy plating, tin-lead alloy plating, palladium
plating, solder plating or the like), the composition of the plating bath
or the like. For example, I1 may be set to a value in the range of 0.01 to
100[A/dm2], and T1 may be set to a value in the range from 0.01 to
300[Second], e.g. from 3 to 300[Second]. However, these parameters are not
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limited to specific values. The optimum I1, I2, Tl, T2 may vary in a broad
range in accord~ince with the type of plating, the composition of the
plating bath or the like. For example, they may vary due to variation of
the composition of the plating bath in the progress of the plating
treatment.
The plating bath 14 is selected in the same way as the well-known
electroplating method in accordance with a plating film to be formed. For
example, in the case of the copper sulfate plating, the following may be
used as through hole bath:
l.0 Copper sulfate : 60 to 100g/L(liter)
Sulfuric acid: :170 to 210g/L
Brightener: proper amount
Chlorine ion: 30 to 80mL/L
The following may be used as normal bath for the copper sulfate
1.5 plating:
Copper sulfate : 180 to 250g/L
Sulfuric acid: 45 to 60g/L
Brightener: proper amount
Chlorine ion: 20 to 80mL/L
20 Further, in the case of the nickel plating, the following may be
used as barrel Lath:
Nickel sulfate: 270g/L
Nickel chloride: 68g/L
Boric acid: 40g/L
25 Magnesium sulfate: 225g/L
The following may be used as normal bath for the nickel plating:
Nickel sulfate: 150g/L
Art~nonium chloride: 15g/L
Boric acid: 15g/L
30 The following may be used as Watts bath for the nickel plating:
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Nickel sulfate: 240g/L
Ammonium chloride: 45g/L
pH: 4 to 5
bath temperature: 45 to 55°C
Further, in the case of the acidic tin plating, the following may
be used as sulfate bath:
Stannous sulfate: 50g/L
Sulfuric acid: 100g/L
Cre~;olsulfonic acid: 100g/L
1.0 Gelatin: 2g/L
a -naphthol : lg/L
Electronic parts, mechanical parts, etc. may be used as articles X
to be plated, arid the articles X are not limited to specific ones. The
present invention is remarkably effectively applied to a case where a
plating film having a microstructure is formed. Particularly, the following
cases maybe considered as the plating of these articles X: formation of a
plating conductive film onto the inner surface of a minute blind via hole
or through hole having an inner diameter of 100 ~.m or less (for example,
to 100 ~.m, or particularly 50 ~,m or less, further 30 ~.m or less, e.g.
2.0 10 ~, m, 5 ~, m, 3 ~. m, etc. ) and having a depth of 10 to 100 ~, m for
example in
a multi-layered wiring board; formation of a conductive film in a minute
groove to form a high-density wiring pattern having a pitch of 50 ~,m or
less (for example, 20 to 50 ~:m, or particularly 30 ~,m or less, further
20 ~, m or less, e~. g. 10 ~, m, 5 ~: m, etc. ) , the minute groove having a
width of
2.5 30E,em or less (particularly 20um or less, further 10 u.m or less, e. g.
5 ~,m, 3 ~,m, etc.) and depth of 7 to 70 a m for example; formation of an
embedded conductive film into an extremely minute blind via hole having an
inner diameter o~f about 0.3 ~:m or less or into an extremely minute groove
having a width o~f 0.1 ~,m and depth of 1.5 ~.m by copper damascene method
when multi-layered wires of a semiconductor device are formed; formation of
CA 02349156 2001-05-24
- 17 -
minute electrode bumps disposed in a high-density arrangement in a
semiconductor dEwice; etc. 'The improving effect of the present invention is
particularly rert~arkable when :it is applied to the structure having a high
aspect ratio, far example 3 or more, especially 5 or more.
Further, an extremely small article having an average diameter of
5 to 500 ~.m may be used as the plating target article X. Here, the average
diameter is defined as the average value of representative dimensions in
the three directions that cross to one another at right angles. As this
type of plating target article X may be provided metal powder such as
copper powder, pre-treated aluminum powder or iron powder, synthetic resin
powder such as A,BS resin powder or the like which is treated to have
electrical conduactivity, ceramic chips which are treated to have electrical
conductivity, et.c. Further, other electronic parts, mechanical parts, metal
powder alloy, minute particulate inorganic/organic pigment, metal balls,
etc. may be also provided.
For example, Ni plating films may be formed on metal particles such
as Cu particles each having a diameter of about 300 a m, or an Au plating
film or an Ag plating film may be formed on an Ni plating film to form a
composite plating film.
2',0 Further, when a plating target article is made of electrically
insulating material such as plastic or the like, a conductive base (primer)
forming treatment is carried out as a pre-treatment of the electroplating.
However, in the case of a microstructured plating face having a high aspect
ratio, an uniform and excellent conductive base could not be formed even if
the conductive base forming treatment is carried out by normal electroless
plating. Therefore, the thickness of the plating film obtained by the
electroplating is liable to be non-uniform. In order to avoid this problem,
the conductive base forming treatment may be carried out by sputtering or
vacuum deposition. However, in this case, since the treatment is carried
out in a pressure-reduced apparatus, there occur such difficulties that the
CA 02349156 2001-05-24
-18-
cost of the treatment apparatus rises up and a mass-production treatment
and a continuous treatment cannot be performed. On the other hand, if the
conductive base forming treatment using the electroless plating or the like
is carried out while vibratior~al flow is induced in treatment liquid by
using the same means as the vi_brational flow generating means used in the
present invention, a highly uniform conductive base can be formed on even
a microstructured plating face having a high aspect ratio. Accordingly,
by combining the conductive base forming treatment and the electroplating
method of the present invention, the process from the pre-treatment to the
electroplating treatment can tre continuously carried out, and thus the
productivity can be enhanced more and more.
According to the plating method of the present invention, the
distribution of the plating bath into microstructure recess portions can
be enhanced by the vibrational flow which is induced in the plating bath 14
by the vibrational flow generator 16, and also the uniformity in film
thickness can be enhanced by pulsing the plating current density so that a
first pulse state and a second pulse state where the pulsed current density
has the same polarity as that of the first pulse state although it is
sufficiently lower than that of the first state. Therefore, there can
be suppressed occurrence of non-uniformity in film thickness due to
concentrated plating film forn~ation at the projecting portions or edge
portions and also occurrence of defects such as gas pits, etc. in through
holes or via holes as in the case of the DC plating process, and high
surface glossiness can be achieved. Further, there can be prevented such
2!~ a phenomenon that a plating film which has been temporarily formed is
partially dissolved as in the case of the pulse plating current whose
polarity is inverted. Therefore, a high-speed film forming process can be
carried out and 'the construction of the manufacturing apparatus can be
simplified. Accordingly, desired plating films can be efficiently formed
with low fraction defective at. high speed on broad plating target articles.
CA 02349156 2001-05-24
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Further, according to t;he present invention, short-circuit can be
prevented by the action of the vibrational flow occurring in the plating
bath 14 even when the distance between the plating target article X and
the anode metal member is short; to increase the current density. This is
considered as a factor to form a plating film with an excellent yield and
at high speed without inducing disadvantages such as burning, scorching,
etc.
In order to attain such an excellent action, it is remarkably
preferable that the three-dimensional flow rate of the vibrational flow of
the plating bath 14 is equal t;o or greater than 150mm per second. Such a
high three-dimensional flow rate can be effectively implemented by inducing
the vibrational flow in the plating bath. It is difficult to implement this
three-dimensional flow rate by using a normal stirrer, and even when it is
implemented, an extremely large scale apparatus is needed.
In this embodiment, the effect can be further enhanced by swinging
and/or vibrating the plating target article X through the swing and/or
vibration of the swinging frame 24. However, an excellent effect can be
obtained even when the plating target article X is neither swung nor
vibrated. If the cathode bus tsar 30, the anode bus bar 32, the plating
target article X, the anode metal member, etc. are supported without using
the swinging frame 24, the swinging motor 20 and the vibrating motor 28,
the construction of the apparatus can be further simplified. When the
plating target article X has a plate shape of a relatively large dimension
or length as a whole such as a multi-layered wiring board or the like, the
effect can be enhanced by swinging the plating target article X along the
in-plane direction thereof.
Figs. 9 .and 10 are cross-sectional views showing the construction
of a plating apparatus to which a second embodiment of the plating method
according to the present invention is applied, and Fig. 11 is a plan view
showing the plating apparatus shown in Figs. 9 and 10. This embodiment is
CA 02349156 2001-05-24
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different from the first embodiment shown in Figs. 1 to 8 in the way to
hold the plating target article X and the way to supply current to the
plating target article, and iii uses a so-called barrel plating method.
In Figs. 9 to 11, a vibrating frame 44 is fitted to a plating tank
12 through a coil spring 46 as a vibration absorption member. The vibrating
frame 44 is fitted to a vibrai~i.ng motor 48 and a balance weight 49 used to
keep a weight balance with the vibrating motor 48. A barrel 52 is fitted
to the vibrating frame 44 through a support member 50. The barrel 52 is
rotatably fitted to the support member 50, and rotated in the direction
indicated by an arrow of Fig. 9 by driving means (not shown). Many minute
plating target articles X are accommodated in the barrel 52. Many small
holes are formed on the outer peripheral surface of the barrel 52 so that
the plating target articles X are prevented from passing through the small
holes, but the liquid of the plating bath 14 is allowed to pass through the
small holes. A cathode conductive member 54 is disposed in the barrel 52 so
as to extend to the lower portion of the barrel 52. The cathode conductive
member 54 is connected to a negative-electrode terminal of a power source
circuit 34 via an insulated coated wire 54' which passes through a pipe
member 52a fixed to the barre:L 52 at the rotational center of the barrel
52. The cathode conductive member 54 is not rotated even when the barrel is
rotated, and thus the plating target articles X which are rolled through
the rotation of the barrel repetitively be in contact with and separate
from the cathode conductive mmnber 54.
Reference numeral 56 represents an anode metal member having a
lower portion immersed in the plating bath 14. The anode metal member 56
is accommodated in a plastic cage, for example, and is connected to a
positive-electrode terminal of the power source circuit 34 through an
insulated coatedl wire 56'. As shown in Fig. 9, the anode metal member 56 is
disposed at both the sides of the barrel 52, however, it may be disposed at
3~0 one side of the anode metal member 56.
CA 02349156 2001-05-24
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The vibrating motor 48 is vibrated at the same amplitude and
frequency as the vibrating motor 28 described above, and the plating target
articles X are vibrated at an amplitude of 0.05 to 5.Omm, for example 0.1
to S.Omm, and a vibrational frequency of 100 to 300 revolutions per minute.
In this embodiment, the effect is also further enhanced by vibrating the
plating target articles through t;he vibration of the vibrating frame 44.
However, an excellent effect can be achieved without vibrating the plating
target articles X. The construction of the apparatus can be further
simplified by supporting the support member 50 and the barrel 52 without
using the vibrating frame 44, i;he vibrating motor 48, etc.
In this embodiment, the plating current density is set in the same
way as described. with reference to Fig. 8. In this embodiment, the plating
current in the first pulse sti~te or second pulse state or the plating
current varying in the shift process between the first pulse state and
the second pulse state is supplied to each plating target article X when
each plating target article X is brought into contact with the cathode
conductive member 54. If only the current density at the contact time is
continuously displayed, the s~~rne current density as shown in Fig. 8 is
obtained on average, and thus the same effect as the first embodiment can
2.0 be obtained.
This embodiment is more effectively applied to a case where
formation of electrode films on plating target articles X having extremely
small dimensions, for example, chip parts such as ceramic chip capacitors
of about 0.6mm x. 0.3mm x 0.2mm in dimension or the like, or formation of
f,5 plating films on pins of about 0.5mm in diameter x about 20mm in length is
carried out on a, large number of plating target articles at the same time.
As described above, when such a minute article that the dimension in the
direction traversing the longitudinal direction, that is, the width is
equal to 5mm or less, further 2mm or less, still further lmn or less is
f.0 used as the plating target article, the improving effect in the uniformity
CA 02349156 2001-05-24
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of the plating film thickness and the film forming speed is greater.
Besides, metal powder alloy, iuorganic/organic pigment particulates, metal
balls may be targeted as the plating target articles.
As a matter of course, a desired pre-treatment is carried out
before the electroplating method of the present invention is carried out.
The pre-treatment is carried out in the same manner as the well-known
electroplating method.
Further, a vibrational flow generator disclosed in JP(A)-11-189880
(in which vibrating vanes are disposed at the bottom portion of a plating
tank, and vibration is transmitted from a vibrating motor through a
vibration transmitting frame i~c~ the vibrating vanes to vibrate the
vibrating vanes in the horizontal direction, as described with reference to
Figs. ? and 8 of this publicai~ion) or ones disclosed in publications other
than the above publication maw be properly used as the vibrational flow
generator having; the vibrating vanes for generating vibrational flow in the
plating path in the method of the present invention.
For example, vibrational flow generators shown in Figs. 21 and 22
may be used. In Figs. 21 and .?2, two vibrational flow generators 16 are
supported by a .support frame :l5 fixed to a support stand 13 on which a
i;0 plating tank 12 is mounted. In each of the vibrational flow generators 16,
the upper end portion of a vibration transmitting rod 16e" extending in the
up-and-down direction is fixed to a vibrating member 16c' for receiving
vibration transmitted from a vibrating motor 16d. The vibration
transmitting rod 16e" extends into the plating tank 12, and the end portion
c;5 of the vibration transmitting rod 16e' in the horizontal direction is
fixed
to the lower end of the vibration transmitting rod 16e". The vibration
transmitting rods 16e' are commonly used by the two vibrational flow
generators 16, and vibrating 'vanes 16f extending in the up-and-down
direction are fixed to the vibration transmitting rods 16e'. The vibration
30 is transmitted from the vibrating motors 16d through the vibrating members
CA 02349156 2001-05-24
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16c' and the vibration transmitting rods 16e" and 16e' to the vibrating
vanes 16f to vibrate the vibrating vanes 16f in the horizontal direction.
Fig 12 is a cross-sect;ional view showing another embodiment of the
plating apparatus used in the embodiment of the plating method according to
the present invention, and Fib;. 13 is a partially notched plan view of the
plating apparatus of Fig. 12. In this embodiment, the construction of the
vibrational flow generator 16 is different from that of the above
embodiment. That is, the lower end of a coil spring 16d is fixed to a
fixing member 118 fixed to the upper end edge portion of the plating tank
12, and a vibrating motor 16d is fixed to the lower side of a vibrating
member 16c to which the upper end of the coil spring 16b is fixed. A lower
guide member 124 whose lower end is fixed to the fixing member 118 and an
upper guide member 123 whose upper end is fixed to the vibrating member 16c
are disposed in the coil spring 16b so as to be spaced from each other at a
proper distance.
Figs. 19 and 15 are cross-sectional views of another embodiment of
the fixing portion of the vibr-ational flow generator to the plating tank
in the plating apparatus used in the embodiment of the plating method
according to the: present invention, and Fig. 16 is a plan view of this
~,0 embodiment. Figs'.. 14 and 15 are views taken along lines X-X' and Y-Y' of
Fig. 16, respectively. In these figures, the cathode, anode, power source
circuit, etc. for plating are not; shown.
In this embodiment, a laminated member 3 made of a rubber plate 2
and metal plates. 1, 1' is used as a vibration absorbing member instead of
c;5 the coil spring 16b of the above embodiments. The laminated member 3 is
formed by fixing the metal plate 1' via a rubber vibration insulator 112
to a support member 118 conne<;t:ed to the upper end of the plating tank 12
by means of a bolt 131, disposing the rubber plate 2 on the metal plate 1',
disposing the metal plate 1 on the rubber plate 2, and fixing the metal
30 plates l, 1' and rubber plate 2 by means of a bolt 116 and nut 117 to be
CA 02349156 2001-05-24
- 24 -
integrated.
A vibrating motor 16d is fixed to the metal plate 1 via a support
member 115 by a bolt 132. The upper end portion of a vibration transmitting
rod 16e is connected via a rubber ring 119 to the laminated member 3,
especially to the metal plate 1 and rubber plate 2. That is, the upper side
metal plate 1 functions as the vibrating member 16c of the embodiment of
Fig. l, etc., and the lower side metal plate 1' functions as the base stand
16a of the embodiment of Fig. 1, etc. The laminated member 3 containing the
metal plate 1, 1', especially the rubber plate 2, has the same vibration
absorbing function as the coil spring 16b of the embodiment of Fig. 1, etc.
Figs. 1TA to 17C show schematic plan views of an embodiment of the
laminated member 3. In the embodiment of Fig. 17A corresponding to the
above embodiment. of Figs. 14 to 16, there is provided a hole 5 through
which the vibration transmitting rod 16e passes. In the embodiment of
Fig. 17B, the laminated member 3 comprises a first portion 3a and a second
portion 3b, the facing edges of which are contacted with each other.
According to this embidiment, the vibration transmitting rod 16e can be
easily set to th.e laminated member 3 through the hole 5 thereof when
assembling the apparatus. In the embodiment of Fig. 17C, the laminated
member 3 is formed so as to hive a ring shape corresponding to the shape
of the upper edge portion of the plating tank 12, and has an opening 6
positioned at th.e center therE~of.
According to the embodiments of Figs. 17A and 17B, the plating tank
12 is sealed with the laminatE~l member 3, and therefore gas evaporated from
the plating bath. 14 and plating liquid splashed from the plating bath 14
are prevented from leaking to the environment.
Figs. 18A and 18B show cross-sectional views of the above sealing
of the plating tank with the laminated member 3. In the embodiment of
Fig. 18A, the sealing of the plating tank 12 is performed by contacting
the inner surface of the hole 5 of the rubber plate 2 with the vibration
CA 02349156 2001-05-24
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transmitting rod 16e. In the embadiment of Fig. 18B, there is provided a
flexible sealing member 136 attached to the opening 6 of the laminated
member 3 and the vibration transmitting rod 16e to seal the space existing
therebetween.
Figs. 19A to 19E show examples of the laminated member 3 as the
vibration absorbing member. The laminated member 3 of Fig. 19B is the same
as that of Figs. 14 to 16. The laminated member 3 of Fig. 19A comprises
metal plate 1 and rubber plate 2. The laminated member 3 of Fig. 19C
comprises upper metal plate 1,. upper rubber plate 2, lower metal plate 1'
l.0 and lower rubber plate 2' . Thc~ laminated member 3 of Fig. 19D comprises
upper metal plate 1, upper rubber plate 2, intermediate metal plate 1",
lower rubber plate 2' and lower metal plate 1'. The number of the metal
plate or rubber plate is 1 to 5 for example. In the present invention, the
vibration absorbing member may be formed only of the rubber plate(s).
1.5 Example.c of material. of the metal plates 1, 1', 1" are stainless
steel, iron, copper, aluminum, suitable alloys, etc. The thickness of the
metal plates 1, 1', 1" is 10 to 40 mm for example. However, the metal
plate, for example the intermf~diat:e metal plate 1", which is not fixed to
any member other' than the member constituting the laminated member may be
i;0 made so thinner as to have the thickness of 0.3 to lOmm for example.
Material of the rubber plate 2, 2' is, for example, synthetic
rubber or vulcanized natural. rubber, and preferably rubber vibration
isolator defined in JIS K6386(1977), especially having static modulus of
elasticity in shear of 4 to 22 kgf/cmz, preferably 5 to 10 kgf/cm2, and
t.5 ultimate elongation of 250 °6 or more.
Examples. of synthetic rubber are chloroprene rubber, nitrile
rubber, nitrile-chloroprene rubber, styrene-chloroprene rubber,
acrylonitrile-butadiene rubber, isoprene rubber, ethylene-propylene-diene
rubber, epichlorohydrin rubber, alkylene oxide rubber, fluororubber,
3'.0 silicone rubber, urethane rubber, polysulfide rubber, phosphorus rubber
CA 02349156 2001-05-24
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(flame-retarded rubber). The 'thickness of the rubber plate is 5 to 60mm for
example.
The laminated member 3 of Fig. 19E comprises upper metal plate 1,
lower metal plate 1', and rubber plate 2 which comprises an upper solid
rubber layer 2a, sponge rubber layer 2b and lower solid rubber layer 2c.
One of the upper and lower solid rubber layers 2a, 2c may be omitted.
Alternatively, a plurality of sponge rubber layers and a plurality of solid
rubber layers may be used in the rubber plate.
Fig. 20 is a graph showing a modification of the variation of the
plating current (current density) flowing through the plating target
article X due to the voltage applied across the cathode bus bar 30 and
the anode bus ba.r 32 by the power source circuit 34. In this modification,
the current density waveforms of the first and second states are not the
rectangular forms as shown in 1~ig. 8, but contain a little pulsation as
shown in Fig. 20. Such pulsatian is based on the construction of the power
source circuit 34, and the plating current used in the present invention
may be pulsated current as shown in Fig. 20. The peak values in the first
and second states may be used as the current values I1 and I2 in the first
and second states, respectively.
In the present invention, the power source circuit 34 may comprise
a voltage supply system for the first state and another voltage supply
system for the second state. In this case, the voltages of these voltage
supply systems are alternately output (i.e., this power source circuit is
functionally equivalent to the switching operation of two power source
devices).
The combination technique of the vibrational flow of the plating
bath and the pulsed plating current as described above may be applied to an
anodizing method, an electrolytic polishing method, an electrolytic
degreasing method, etc. in which the surface treatment of target objects
is carried out by utilizing current flow in a treatment bath. The target
CA 02349156 2001-05-24
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objects are dis~~osed at the anode side or cathode side in accordance with
the treatment content. By using this combination technique, the surface
treatment on target articles having microstructures can be excellently
performed.
The present invention will be described in more detail with the
following examples.
EXAMPLE 1:
The apparatus described with reference to Figs. 1 to 3 was used.
Here, a vibrating motor of 150W x 200V x 3c~ was used as the vibrating
motor 16d, a plating tank having a volume of 300 liters was used as the
plating tank 12, and Power Master (available from Chuo Seisakusho, Co.,
Ltd.) was used as the power source circuit 34.
8-Inch (diameter of 2(IOmm) silicon wafers which were subjected to
a predetermined pre-treatment by the conventional method were used as the
plating target articles X, and a process of forming copper-embedded
conductive film in blind via holes coated with a copper seed layer in the
copper damascene method was c~~rried out. Many blind via holes were formed
in a titanium nitride insulation layer of 0.35 ~.m in thickness to have an
inner diameter of 0.24 ~.m.
The following through hole bath of copper sulfate plating was used
as the plating bath 14:
Copper sulfate: 75g/L
Sulfuric acid: 190g/L
Brightener: proper amount
Chlorine ion: 40mL/L
The vibrating motor 16d of the vibrational flow generator 16 was
vibrated at 45Hz to vibrate the vibrating vanes 16f at an amplitude of
0.2mm and a vibration frequency of 650 revolutions per minute in the
plating bath 14. Further, the vibrating motor 28 was vibrated at 25Hz to
vibrate the plating target articles X at an amplitude of 0.15mm arxi a
CA 02349156 2001-05-24
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vibration frequency of 200 revolutions per minute in the plating bath 14.
The three-dimensional flow rate in the plating bath at this time was
measured as 200mm/second by a three-dimensional electromagnetic flowmeter
ACM300-A (available from Alec Electronics Co., Ltd.).
The planing current of rectangular waveform was supplied by the
power source circuit 34 so that Il, I2, T1, T2 shown in Fig. 8 satisfied
I1=6 [A/wafer] = 3 [A/dm2] , I2=i0. 6 [A/wafer] , T1=10 [second] , T2=1
[second] .
When thE~ treatment was carried out for 10 minutes, it was found on
the basis of a current flowing test, microscopy and other tests that
excellent copper plating films of about 10 ~,m in thickness were formed and
embedded in all the blind via holes.
COMPARATIVE EXAMPLE 1-1:
The same treatment as Example 1, except for the condition:
T2=0[second], was carried out. It was proved from the current flowing test,
microscopy and other tests that excellent embedding of copper plating film
was carried out in some (58~) of the many blind via holes, however, was not
carried out in the other blind via holes.
COMPARATIVE EXAMPLE 1-2:
The same treatment as Example 1, except that the vibrational flow
generator 16 was not actuated, was carried out. It was proved from the
current flowing test, microscopy and other tests that excellent embedding
of copper plating film was carried out in some (10%) of the many blind
via holes, however, was not carried out in the other blind via holes
(defectives due 'to burning, scorching or the like occurred).
2!i EXAMPLE 2:
The plating conductive films were formed on the inner surfaces of
through holes by using the apparatus described with reference to Figs. 1
to 3 (the vibrating motor 16d, the plating tank 12 and the power source
circuit 34 were i:he same as Example 1) and using as the plating target
article X an A4-::ize multi-layered wiring board which was subjected to the
CA 02349156 2001-05-24
- 29 _
pre-treatment b;~ the conventional method. Many through holes had an inner
diameter of 30 ~,m ~ and an aspect ratio of 10.
The following normal 'bath of copper sulfate plating was used as the
plating bath 14:
Copper sulfate: 200g/L
Sulfuric acid: 50g/L
Brit;htener: proper amount
Chlorine ion: 60mL/L
The vibrating motor 16d of the vibrational flow generator 16 was
:l0 vibrated at 50Hz to vibrate the vibrating vanes 16f at an amplitude of
0.2mm and a vibration frequency of 700 revolutions per minute in the
plating bath 14. Further, the vibrating motor 28 was vibrated at 25Hz to
vibrate the plai;ing target articles X at an amplitude of 0.15mm and a
vibration frequency of 200 revolutions per minute in the plating bath 14.
iL5 Further, the swinging motor 20 was driven to swing the plating target
articles X at a swinging width of 30mm and a swinging frequency of 20 times
per minute. The three-dimensional flow rate in the plating bath at this
time was measured as ZOOmm/second by the three-dimensional electromagnetic
flowmeter ACM300-A.
20 The plai;ing current of rectangular waveform was supplied by the
power source circuit 34 so th~~t I1, I2, T1, T2 shown in Fig. 8 satisfied
I1=4 [A/dm2] , I2=~0. 4 [A/dm2] , T:1=180 [second] , T2=20 [second] .
When the treatment way carried out for 10 minutes, it was found
on the basis of a current flowing test, microscopy and other tests that
~;5 excellent copper plating filmy were formed in 99.9% through holes.
COMPARATIVE EXAMPLE 2-1:
The same treatment as Example 2, except for the condition:
T2=0[second], w~~s carried out.. It was proved from the current flowing test,
microscopy and other tests twit excellent copper plating films were formed
<<0 over the overall. length in some (50%) of the many through holes, however,
CA 02349156 2001-05-24
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no excellent copper plating film was formed in the other through hales.
COMPARATIVE EXANIPLE 2-2:
The same treatment as Example 2, except that the vibrational flow
generator 16 was. not actuated, was carried out. It was proved from the
current flowing test, microscopy and other tests that excellent copper
plating films were formed in some (10°6) of the many through holes,
however,
no excellent copper plating fiilm was formed in the other through holes
(defectives due to burning, scorching or the like occurred).
EXAMPLE 3:
The apparatus described with reference to Figs. 9 to 11 (the
vibrating motor 16d, the plating tank 12 and the power source circuit 34
were the same as Example 1), and 800 ceramic chips of 0.6mm x 0.3mm x 0.2mm
in dimension which were subjecaed to the pre-treatment by the conventional
method were used as plating target articles X. Nickel plating films to form
electrode films were formed on the end surfaces at both ends of each
ceramic chip in the longitudinal direction thereof and on a part (an area
located within O.lmm from both the end surfaces) of the 0.6mm x 0.3mm
surface adjacent to the end surfaces.
The following barrel bath was used as the nickel plating bath 14:
Nickel sulfate: 270g/L
Nickel chloride: 68g/L
Boric acid: 40g/L
Magnesium sulfate: 225g/L
The vibrating motor lEid of the vibrational flow generator 16 was
vibrated at 55Hz to vibrate the vibrating vanes 16f at an amplitude of
0.2mm and a vibration frequen<:y of 750 revolutions per minute in the
plating bath 14. 'The vibrating motor 48 was vibrated to vibrate the target
plating articles at an amplitude of 0.15mm and a vibration frequency of 250
revolutions per minute in the plating bath 14. The three-dimensional flow
rate in the plating bath at this time was measured as 210mm/second by the
CA 02349156 2001-05-24
- 31 -
three-dimension;~l electromagnetic current meter ACM300-A. The barrel 52
having a mesh opening ratio of 20% was used, and the rotational number of
the barrel was set to 10 rpm.
The plating current of rectangular waveform was supplied by the
power source circuit 34 so that I1, I2, T1, T2 shown in Fig. 8 satisfied
I l=0. 4 [A/dmZ] , f 2=0. 04 [A/dmz] , T1=20 [second] , T2=2 [second] .
When thc~ treatment was carried out at 50°C for 30 minutes, it was
found on the ba:~is of a current flowing test, microscopy and other tests
that excellent nickel plating films of about 2 ~.m in thickness were formed
:f0 in all the ceramic chips.
COMPARATIVE EXAMPLE 3-1:
The same treatment as Example 3, except for the condition:
T2=0[second], was carried out. It was proved from the current flowing test,
microscopy and other tests that excellent nickel plating films were formed
:l5 in some (12~) of the ceramic .chips, however, no excellent nickel plating
film was formed in the other .ceramic chips.
COMPARATIVE EXAMPLE 3-2:
The same treatment as Example 3, except that the vibrational flow
generator 16 wa:~ not actuated, was carried out. It was proved from the
~;0 current flowing test, microscopy and other tests that excellent nickel
plating films were formed in come (60%) of the ceramic chips, however, no
excellent nickel. plating film was formed in the other ceramic chips.
EXAMPLE 4:
In placE~ of the nickel plating, tin plating was carried out in the
25 same way as Example 3. The following sulfate bath of acidic tin plating was
used as the plating bath 14:
Stannous sulfate: 50g/L
Sulfuric acid: 100g/L
Cresolsulfonic acid: 100g/L
~~0 Gelatin: 2g/L
CA 02349156 2001-05-24
- 32 -
a -naphthol lg/L
The plating current of rectangular waveform was supplied by the
power source circuit 34 so that I1, I2, T1, T2 shown in Fig. 8 satisfied
I1=0. 4 [A/dm2] , I2=0. 04 [A/dmz] , T1=20 [second] , T2=2 [second] .
YVhen the treatment was carried out at 50°C for 60 minutes, it was
found on the basis of a current flowing test, microscopy and other tests
that excellent tin plating films were formed in all the ceramic chips.
COMPARATIVE EXAMPLE 4-1:
The same treatment as, Example 4, except for the condition:
:l0 T2=0[second], was carried out. It was proved from the current flowing
test,
microscopy and other tests that excellent tin plating films were formed in
some (10%) of the ceramic chips, however, no excellent tin plating film was
formed in the oi~her ceramic chips.
COMPARATIVE EXAMPLE 4-2:
l.5 The same treatment as Example 4, except that the vibrational flow
generator 16 wa:~ not actuated, was carried out. It was proved from the
current flowing test, microscopy and other tests that excellent tin plating
films were formed in some (5T~6) of the ceramic chips, however, no excellent
tin plating film was formed in the other ceramic chips.
20 EXAMPLE 5:
The apparatus described with reference to Figs. 9 to 11 (the
vibrating motor 16d, the plating tank 12 and the power source circuit 34
were the same a~; Example 1), ;end 30 brass pins of 0.5mm ~ in outer
diameter and 20mm in length which were subjected to the pre-treatment by
25 the conventional method were used as plating target articles X. Nickel
plating films were formed on the outer surfaces of the pins.
The following barrel bath was used as the nickel plating bath 14:
Nickel sulfate: 270g/L
Nickel chloride: 68g/L
30 Boric acid: 40g/L
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Magnesium sulfatE~: 225g/L
The vibrating motor 1.6d of the vibrational flow generator 16 was
vibrated at 45Hz to vibrate t:he vibrating vanes 16f at an amplitude of
0.2mm and a vibration frequency of 500 revolutions per minute in the
plating bath 14. The vibrating motor 48 was vibrated to vibrate the target
plating articles at an amplitude of 0.15mm and a vibration frequency of 200
revolutions per minute in the plating bath 14. The three-dimensional flow
rate in the plating bath at this time was measured as 200mm/second by the
three-dimensional electromagnetic current meter ACM300-A. The barrel 52
having a mesh opening ratio of 20% was used, and the rotational number of
the barrel was set to 10 rpm.
The plating current of rectangular waveform was supplied by the
power source circuit 34 so treat I1, I2, T1, T2 shown in Eig. 8 satisfied
I1=3 [A/dmz] , I2=0. 3 [A/dmz] , T1=30 [second] , T2=3 [second] .
When the treatment was carried out at 50°C for 20 minutes, it
was found on the basis of the measurement of the thickness of the nickel
plating films, .current flowing test, microscopy and other tests that
excellent nickel plating filtr~s having excellent uniformity in thickness
were formed in all the pins.
COMPARATIVE EXAMPLE 5-1:
The same treatment as Example 5, except for the condition:
T2=0[second], was carried out. It was proved from the measurement of the
thickness of the nickel plating films, the current flowing test, microscopy
and other tests that excellent nickel plating films were formed on some
(17~) of the pins, however, no excellent nickel plating film was formed on
the other pins.
COMPARATIVE EXAMPLE 5-2:
The same treatment as Example 5, except that the vibrational flow
generator 16 was not actuated, was carried out. It was proved from the
.30 measurement of 'the thickness of the nickel plating films, the current
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flowing test, microscopy and other tests that excellent nickel plating
films were formed in some (60~) of the pins, however, no excellent nickel
plating film wa:~ formed on the other pins (defectives due to burning,
scorching or the like occurred).
EXAMPLE 6:
The app~iratus described with reference to Figs. 9 to 11 (the
vibrating motor 16d, the plating tank 12 and the power source circuit
34 were the same as Example 1), and about 30000 spheres of
acrylonitrile-butadiene-styrene copolymer (ABS resin) each of which had a
1.0 diameter of 3mm ~ and was subjected to the pre-treatment (containing a
degreasing treatment and a ch;~rging treatment) by the conventional method
were used as plating target articles X. Copper plating films were formed on
the outer surfaces of the spheres.
The following was use~j as the plating bath 14:
Copper sulfate: 2UOg/L
Sulfuric acid: 50g/L
Brightener: proper amount
Chlorine ion: 40mL/L
The vibrating motor lfd of the vibrational flow generator 16 was
2.0 vibrated at 40Hz: to vibrate the vibrating vanes 16f at an amplitude of
0.2mm and a vibration frequency of 700 revolutions per minute in the
plating bath 14. The vibrating motor 48 was vibrated to vibrate the target
plating articles. X at an amplitude of 0.15mm and a vibration frequency of
250 revolutions per minute in the plating bath 14. The three-dimensional
flow rate in the plating bath at this time was measured as 210mm/second by
the three-dimensional electromagnetic current meter ACM300-A. The barrel 52
having a mesh opening ratio o:E 20% was used, and the rotational number of
the barrel was s;et to 10 rpm.
The plating current of rectangular waveform was supplied by the
power source circuit 34 so that I1, I2, T1, T2 shown in Fig. 8 satisfied
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I l=0. 5 [A/dm2] , I2=0. 04 [A/dmz] , Tl=30 [second] , T2=3 [second] .
VYhen the treatment was carried out at 50°C for 30 minutes, it
was found on the basis of the measurement of the thickness of the copper
plating films, current flowing test, microscopy and other tests that
excellent copper plating films having excellent uniformity in thickness
were formed in '~9. 5°6 spheres.
COMPARATIVE EXAMPLE 6-l:
The same treatment as Example 6, except for the condition:
T2=0[second], was carried out. It was proved from the measurement of the
thickness of the copper plating films, the current flowing test, microscopy
and other tests that excellent copper plating films were formed in some
(4096) of the spheres, however, no excellent copper plating film was formed
in the other spheres.
COMPARATIVE EXAMPLE 6-2:
The same treatment as Example 6, except that the vibrational flow
generator 16 was not actuated, was carried out. It was proved from the
measurement of 'the thickness of the copper plating films, the current
flowing test, microscopy and other tests that excellent copper plating
films were formed in some (50%) of the spheres, however, no excellent
copper plating film was formed in the other spheres.
EXAMPLE 7:
The apparatus described with reference to Figs. 1 to 3 was used.
Here, a vibrating motor of 150W x 200V x 3 ~ was used as the vibrating
motor 16d, a plating tank having a volume of 300 liters was used as the
2 5 plating tank 12, and Power Master PMD1 (available from Chuo Seisakusho,
Co., Ltd.) was Bused as the power source circuit 34.
A silicon wafer having a size of 40mm x 40mm and a thickness of lmm
which was subjected to a predetermined pre-treatment by the conventional
method was used as the plating target article X, on the surface of which
many blind via lholes each having an inner diameter of 20 ~.m and a depth of
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70 ~, m were formed.
The following through hole bath of copper sulfate plating was used
as the plating bath 14:
Copper sulfate: 75g/L
Sulfuric acid: 190g/L
Brightener: proper amount
Chlorine ion: 40mL/L
In the plating tank 12, an aeration tube made of ceramics having
an outer diameter of 75 mm ~ , an inner diameter of 50mm ~, a length of
500mmm, a pore aize of 50 to 60 a m and a porosity of 33 to 38% was
disposed to generate air bubbles in the plating bath 14.
The vibrating motor 16d of the vibrational flow generator 16 was
vibrated at 40Hz to vibrate the vibrating vanes 16f at an amplitude of
O.lmm and a vibration frequency of 650 revolutions per minute in the
plating bath 14. Further, the vibrating motor 28 of 75W x 200V x 3 ~ was
vibrated at 25H:z to vibrate the plating target articles X at an amplitude
of 0.15mm and a vibration frequency of 200 revolutions per minute in the
plating bath 14. The three-dimensional flow rate in the plating bath at
this time was measured as 200mm/second by the three-dimensional
electromagnetic flowmeter ACM300-A.
The plating current of rectangular waveform was supplied by the
power source circuit 34 so that I1, I2, T1, T2 shown in Fig. 8 satisfied
I1=1. 5 [A/wafer] ., I2=0.1 [A/wafer] , T1=0. 08 [second] , T2=0. 02 [second]
.
When the treatment was carried out for 2.5 hours, it was found on
2 5 the basis of the current flowing test, microscopy and other tests that
copper plating :Films having a uniform thickness of about 7 ~,m were formed
in all the inner surfaces of the blind via holes.
COMPARATIVE EXAMPLE 7:
The same treatment as Example 7, except for the condition:
T2=0[second], was carried out. It was proved from the current flowing test,
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microscopy and other tests that the openings of the blind via holes were
sealed with the copper plating films.
EXAMPLE 8:
The same treatment as Example 7, except that a high frequency
vibrating motor was used as the vibrating motor 16d, the vibrating motor
16d was vibrated at 150Hz to vibrate the vibrating vanes 16f at an
amplitude of 0.2mm and a vibration frequency of 1200 revolutions per minute
in the plating bath 14, and the treatment time was 1.5 hours.
It was proved from the current flowing test, microscopy and other
l0 tests that the copper plating films having a uniform thickness of about
7 ~,m were formed in all the inner surfaces of the blind via holes.
EXAMPLE 9:
An epoxy resin plate for wiring board was used as the plating
target article J(, on the surface of which many blind via holes each having
:l5 an inner diameter of 15 ~cm aind a depth of 40 ~,m were formed.
As the pre-treatment for the electroplating treatment, degreasing -
water washing - etching - water washing - neutralizing - water washing -
catalyst - water washing - accelarator - water washing - electroless copper
plating were conducted to make the plating target article X electically
20 conductive. Furthermore, water washing - activating - water washing -
strike plating were conducted., In the electroless copper plating and strike
plating, the vibrational flow was generated in the plating treatment liquid
by means of the same vibrational flow generator as described with reference
to Figs. 1 to 3.
~;5 The electroplating treatment was carried out in the same manner as
Example 7, except that the swinging motor 20 was actuated to swing the
plating target ~~rticle X at a swinging width of 30mm and a swinging
frequency of 20 times per minute in the plating bath 14. The
three-dimensional flow rate in the plating bath was measured as
<0 200mm/second by the three-dimensional electromagnetic flowmeter ACM300-A.
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The plai;ing current of rectangular waveform was supplied by the
power source circuit 34 so that I1, I2, Tl, T2 shown in Fig. 8 satisfied
I1=4. 5 [A/dmz] , ~f2=0. 4 [A/dmz] , 'rl=0. 08 (second] , T2=0. 015 [second] .
When the treatment was carried out for 1 hour, it was found on the
basis of the current flowing test, microscopy and other tests that copper
plating films were excellently formed and embedded in all the blind via
holes.
COMPARATIVE EXAMPLE 8:
The same treatment as Example 9, except for the condition:
1.0 T2=0[second], w~~s carried out. It was proved from the current flowing
test,
microscopy and other tests th~~t the openings of the blind via holes were
sealed with the copper plating films, however, voids remained in the
innermost of the blind via holes.
