U.S. patent application number 13/626769 was filed with the patent office on 2014-03-27 for serial plating system.
This patent application is currently assigned to ALMEX PE INC.. The applicant listed for this patent is Tomohiro Noda, Hitoshi USUDA. Invention is credited to Tomohiro Noda, Hitoshi USUDA.
Application Number | 20140083842 13/626769 |
Document ID | / |
Family ID | 50337809 |
Filed Date | 2014-03-27 |
United States Patent
Application |
20140083842 |
Kind Code |
A1 |
USUDA; Hitoshi ; et
al. |
March 27, 2014 |
SERIAL PLATING SYSTEM
Abstract
A serial plating system includes a plurality of nozzles that are
disposed in a plating tank at a position opposite to a plurality of
workpieces, and that discharge a plating solution toward the
plurality of workpieces, and a plurality of anodes that are
disposed in the plating tank at a position opposite to the
plurality of workpieces that are serially transferred in the
plating tank, one nozzle among the plurality of nozzles and at
least one anode among the plurality of anodes being alternately and
repeatedly disposed along a transfer direction in which the
plurality of workpieces are serially transferred. The plurality of
nozzles and the plurality of anodes may be disposed to overlap in a
side view along the transfer direction.
Inventors: |
USUDA; Hitoshi; (Kanuma-shi,
JP) ; Noda; Tomohiro; (Kanuma-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
USUDA; Hitoshi
Noda; Tomohiro |
Kanuma-shi
Kanuma-shi |
|
JP
JP |
|
|
Assignee: |
ALMEX PE INC.
|
Family ID: |
50337809 |
Appl. No.: |
13/626769 |
Filed: |
September 25, 2012 |
Current U.S.
Class: |
204/198 |
Current CPC
Class: |
C25D 17/06 20130101;
C25D 17/12 20130101; C25D 21/10 20130101; C25D 5/08 20130101; C25D
5/022 20130101 |
Class at
Publication: |
204/198 |
International
Class: |
C25D 17/28 20060101
C25D017/28 |
Claims
1. A serial plating system comprising: a plating tank that holds a
plating solution, and plates a plurality of workpieces that are
serially transferred while being held by a transfer jig, and are
set to as a cathode; a plurality of nozzles that are disposed in
the plating tank at a position opposite to the plurality of
workpieces, and that discharge the plating solution toward the
plurality of workpieces; and a plurality of anodes that are
disposed in the plating tank at a position opposite to the
plurality of workpieces that are serially transferred in the
plating tank, and one nozzle among the plurality of nozzles and at
least one anode among the plurality of anodes being alternately and
repeatedly disposed along a transfer direction in which the
plurality of workpieces are serially transferred.
2. The serial plating system as defined in claim 1, the plurality
of nozzles and the plurality of anodes being disposed to overlap in
a side view along the transfer direction.
3. The serial plating system as defined in claim 1, each of the
plurality of anodes having a horizontal cross-sectional profile so
that a distance from a plating target surface of each of the
plurality of workpieces increases as a distance from an electrode
centerline that divides each of the plurality of anodes into two
parts in a plan view and perpendicularly intersects the transfer
direction increases.
4. The serial plating system as defined in claim 3, each of the
plurality of anodes having a curved horizontal cross-sectional
profile.
5. The serial plating system as defined in claim 3, each of the
plurality of anodes having a circular horizontal cross-sectional
profile.
6. The serial plating system as defined in claim 1, each of the
plurality of anodes being an insoluble anode.
7. The serial plating system as defined in claim 1, each of the
plurality of nozzles having a circular horizontal cross-sectional
profile having a diameter that is smaller than a diameter of a
horizontal cross section of each of the plurality of anodes.
8. The serial plating system as defined in claim 1, a center of a
horizontal cross section of each of the plurality of nozzles being
disposed at a position closer to the plating target surface of each
of the plurality of workpieces as compared with a center of a
horizontal cross section of each of the plurality of anodes.
9. The serial plating system as defined in claim 8, a first minimum
distance .delta.1 from each of the plurality of nozzles to the
plating target surface of each of the plurality of workpieces being
less than a second minimum distance .delta.2 from each of the
plurality of anodes to the plating target surface of each of the
plurality of workpieces, and an outer diameter of each of the
plurality of nozzles being less than the second minimum distance
.delta.2.
10. The serial plating system as defined in claim 9, a third
minimum distance .delta.3 between each of the plurality of anodes
and each of the plurality of nozzles being less than the second
minimum distance .delta.2.
11. The serial plating system as defined in claim 10, the third
minimum distance .delta.3 being equal to or greater than the first
minimum distance .delta.1.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from Japanese Patent
Application No. 2011-214302, filed on Sep. 29, 2011, the entirety
of which is incorporated herein by reference.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to a serial plating
system.
[0004] 2. Description of the Related Art
[0005] A serial plating system is configured so that an electric
field is formed between a workpiece (cathode) that is suspended
from (held by) a transfer jig and serially transferred in a plating
tank, and an electrode (anode) disposed in the plating tank to
plate the plating target surface of the workpiece.
[0006] A nozzle that discharges a plating solution to the workpiece
may be provided between the workpiece and the electrode (anode
plate) (see JP-A-2000-178784, JP-A-2006-214006, and JP-A-58-6998).
In this case, a space having a dimension equal to or larger than
the diameter of the nozzle must be provided between the workpiece
and the electrode (anode plate). JP-A-2006-214006 discloses that
the distance between the cathode and the anode is equal to or more
than 100 mm.
[0007] JP-A-2006-214006 and JP-A-58-6998 disclose high-speed
plating. It is necessary to increase the current value or the
current density of current that flows between the workpiece and the
electrode through the plating solution in order to implement
high-speed plating. The current value or the current density may be
efficiently increased by reducing a current loss by reducing the
distance between the workpiece and the electrode so that the
resistance of the plating solution present between the workpiece
and the electrode decreases.
[0008] However, since the nozzle is disposed between the workpiece
and the electrode (anode plate) in JP-A-2006-214006 and
JP-A-58-6998, a reduction in distance between the workpiece and the
electrode (anode plate) is limited.
[0009] If the electrode (anode plate) is disposed close to the
workpiece, an interference between the nozzle and the anode plate
is caused, or flowability of the plating solution becomes worse due
to narrow clearance between the nozzle and the anode plate.
SUMMARY
[0010] Several aspects of the invention may provide a serial
plating system that can efficiently the current density of current
supplied to the workpiece by employing a structure that can reduce
the distance between the workpiece and the anode without causing
interference between the nozzle and the anode.
[0011] Several aspects of the invention may provide a serial
plating system that can prevent a situation in which the plating
solution cannot escape from the space between the workpiece and the
anode as a result of reducing the distance between the workpiece
and the anode, so that fresh plating solution discharged from the
nozzle cannot come in contact with the workpiece.
[0012] Several aspects of the invention may provide a serial
plating system that can prevent a situation in which the plating
solution cannot escape from the space between the workpiece and the
anode as a result of reducing the distance between the workpiece
and the anode, so that the workpiece is drawn toward the nozzle due
to a negative-pressure area that occurs around an area in which the
plating solution is discharged from the nozzle at a high speed.
[0013] According to one aspect of the invention, there is provided
a serial plating system comprising:
[0014] a plating tank that holds a plating solution, and plates a
plurality of workpieces that are serially transferred while being
held by a transfer jig, and are set to as a cathode;
[0015] a plurality of nozzles that are disposed in the plating tank
at a position opposite to the plurality of workpieces, and that
discharge the plating solution toward the plurality of workpieces;
and
[0016] a plurality of anodes that are disposed in the plating tank
at a position opposite to the plurality of workpieces that are
serially transferred in the plating tank, and
[0017] one nozzle among the plurality of nozzles and at least one
anode among the plurality of anodes being alternately and
repeatedly disposed along a transfer direction in which the
plurality of workpieces are serially transferred.
[0018] According to one aspect of the invention, at least one anode
is disposed between two nozzles by dividing an anode plate that has
been normally disposed on the back side of a plurality of nozzles.
Thus, it is able to cut waste such as having to dispose the anode
plate back side of the nozzles opposite to the workpiece, and the
plurality of anodes can be disposed close to the plating target
surface of the workpiece. This makes it possible to reduce the
distance between the plating target surface of the workpiece and
the anode, and reduce the resistance of the plating solution
present between the plating target surface of the workpiece and the
anode, so that the current density of current that flows between
the plating target surface of the workpiece and the anode can be
efficiently increased. The plating thickness of the plating target
surface of the workpiece per unit time increases (i.e., the
throughput increases) as the current density increases, so that
through-holes formed through the workpiece can be efficiently
plated. Therefore, a given plating thickness can be achieved
without increasing the total length of the plating tank. This makes
it possible to reduce the total length of the serial plating
system. Moreover, since the distance between the plating target
surface of the workpiece and the anode can be reduced, it is also
possible to reduce the size of the serial plating system in the
widthwise direction. Since one nozzle among the plurality of
nozzles and at least one anode among the plurality of anodes are
alternately and repeatedly disposed, the nozzles to the anodes can
be disposed at a sufficient density relative to the workpiece
without causing worse flowability of the plating solution due to
narrow clearance between the nozzle and the anode.
[0019] (2) In the serial plating system,
[0020] the plurality of nozzles and the plurality of anodes may be
disposed to overlap in a side view along the transfer
direction.
[0021] According to one aspect of the invention, the plurality of
anodes can be disposed close to the plating target surface of the
workpiece to a maximum extent by disposing the plurality of nozzles
and the plurality of anodes to overlap in the side view. This
layout is first accomplished by providing at least one anode
between two adjacent nozzles, but is never accomplished by a
conventional anode that has been normally formed to have a given
length and disposed on the back side of a plurality of nozzles
opposite to the workpiece.
[0022] (3) In the serial plating system,
[0023] each of the plurality of anodes may have a profile so that a
distance from a plating target surface of each of the plurality of
workpieces increases as a distance from an electrode centerline
that divides each of the plurality of anodes into two parts in a
plan view and perpendicularly intersects the transfer direction
increases.
[0024] If the anode has a rectangular profile in a plan view, since
the distance between the plating target surface of the tabular
workpiece and the anode is constant, the plating solution
discharged from the nozzle is concentrated (trapped) in a narrow
range corresponding to the constant distance. In this case, fresh
plating solution discharged from the nozzle cannot come in contact
with the workpiece, and the workpiece may be drawn toward a
negative-pressure area that occurs around the nozzle stream.
According to the above configuration, the distance between the
plating target surface of the workpiece and the anode increases as
the distance from the centerline of the anode increases, so that
the plating solution can escape from the space between the
workpiece and the anode through a wider clearance between the
nozzle and the anode.
[0025] (4) In the serial plating system,
[0026] each of the plurality of anodes may have a curved horizontal
cross-sectional profile.
[0027] Thus, each of the plurality of anodes may have a curved
horizontal cross-sectional profile having an elliptical or a
circular horizontal instead of crossing two lines at a corner.
[0028] (5) In the serial plating system,
[0029] each of the plurality of anodes may have a circular
horizontal cross-sectional profile. It is preferable that the anode
have a circular horizontal cross-sectional profile rather than an
elliptical horizontal cross-sectional profile as long as the
horizontal cross-sectional area is identical in order to dispose
the anode closer to the plating target surface of the workpiece
while preventing interference with the nozzle.
[0030] (6) In the serial plating system,
[0031] each of the plurality of anodes may be an insoluble anode.
Either one of an soluble anode and a insoluble anode may be applied
to be the anode. The soluble anode of which the electrode component
is dissolved in the plating tank is consumed rapidly when the
current density is increased. In contrast, the insoluble anode does
not pose a problem even if the current density is increased.
[0032] (7) In the serial plating system,
[0033] each of the plurality of nozzles may have a circular
horizontal cross-sectional profile having a diameter that is
smaller than a diameter of a horizontal cross section of each of
the plurality of anodes. The anode can be disposed closer to the
plating target surface of the workpiece while preventing
interference with the circular (chamfered) nozzle.
[0034] (8) In the serial plating system,
[0035] a center of a horizontal cross section of each of the
plurality of nozzles may be disposed at a position closer to the
plating target surface of each of the plurality of workpieces as
compared with a center of the horizontal cross section of each of
the plurality of anodes. Specifically, the center of the horizontal
cross section of each of the plurality of nozzles and the center of
the horizontal cross section of each of the plurality of anodes are
not disposed along a straight line that extends along the transfer
direction, but are disposed in a staggered arrangement. This makes
it possible to easily provide a minimum interval between the nozzle
and the anode that are adjacent to each other as compared with the
case where the center of the nozzle and the center of the anode are
disposed along a straight line. Specifically, interference with the
nozzle can be easily prevented while maximizing the diameter of the
anode.
[0036] (9) In the serial plating system,
[0037] a first minimum distance .delta.1 from each of the plurality
of nozzles to the plating target surface of each of the plurality
of workpieces may be less than a second minimum distance 62 from
each of the plurality of anodes to the plating target surface of
each of the plurality of workpieces, and
[0038] an outer diameter of each of the plurality of nozzles may be
less than the second minimum distance .delta.2. This makes it
possible to dispose the nozzle closer to the workpiece as compared
with the anode, and makes it unnecessary to increase the supply
pressure of the plating solution. It is also possible to prevent a
situation in which the plating solution that is discharged from the
nozzle to the workpiece at a given spray angle in a plan view is
blocked by the anode. Since the curvature of the nozzle can be
increased by setting the diameter of the nozzle that is disposed
close to the workpiece to be less than the second minimum distance
.delta.2 between the anode and the workpiece, it is possible to
easily provide an escape space for the plating solution.
[0039] (10) In the serial plating system,
[0040] a third minimum distance .delta.3 between each of the
plurality of anodes and each of the plurality of nozzles may be
less than the second minimum distance .delta.2. This makes it
possible to dispose the anode closer to the plating target surface
of the workpiece. Note that the plating solution discharged from
the nozzle toward the workpiece can escape from the space between
the nozzle (anode) and the workpiece into the wide space present in
the plating tank through the space between the nozzle and the anode
that are adjacent to each other. This makes it possible to allow
the workpiece to always come in contact with fresh plating
solution.
[0041] (11) In the serial plating system,
[0042] the third minimum distance .delta.3 may be equal to or
greater than the first minimum distance .delta.1. According to the
above configuration, since the flow resistance of the space between
the nozzle and the anode is equal to or less than the flow
resistance of the space between the workpiece and the nozzle, the
plating solution can easily escape into the wide space present in
the plating tank through the space between the nozzle and the
anode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] FIG. 1 is a schematic cross-sectional view illustrating a
serial plating system according to one embodiment of the
invention;
[0044] FIG. 2 is a schematic plan view illustrating the serial
plating system illustrated in FIG. 1;
[0045] FIGS. 3A to 3C are horizontal cross-sectional views
illustrating an anode;
[0046] FIG. 4 is a view illustrating the relationship between a
first minimum distance, a second minimum distance, and a third
minimum distance;
[0047] FIG. 5A is a view illustrating an example in which the
center of a nozzle and the center of an anode are disposed along a
straight line, and FIG. 5B is a view illustrating an example in
which a plurality of anodes are disposed between two nozzles;
and
[0048] FIG. 6 is a view illustrating an example in which an anode
has a rectangular horizontal cross-sectional profile.
DESCRIPTION OF EXEMPLARY EMBODIMENT(S)
[0049] Exemplary embodiments of the invention are described in
detail below. Note that the following exemplary embodiments do not
in any way limit the scope of the invention defined by the claims
laid out herein. Note that all of the elements described in
connection with the following exemplary embodiments should not
necessarily be taken as essential elements of the invention.
1. Overall Configuration
[0050] FIG. 1 is a cross-sectional view illustrating a serial
plating system according to one embodiment of the invention, and
FIG. 2 is a plan view illustrating the serial plating system. As
illustrated in FIG. 1, a plating tank 10 is configured so that a
workpiece 1 that is suspended from (held by) a transfer jig 20 is
immersed in a plating solution 2 to plate the workpiece 1. The
plating tank 10 has a peripheral wall 10A and a bottom wall 10B,
and holds the plating solution 2 up to a liquid level L.
[0051] The workpiece 1 is a circuit board, a flexible circuit
board, or the like, and each side of the workpiece 1 is plated, for
example. The transfer jig 20 serially transfers the workpiece 1,
and supplies current to the workpiece 1. The workpiece 1 serves as
a cathode. More specifically, a power-feeding section that may be a
transfer rail and comes in sliding contact with the transfer jig 20
is connected to a negative terminal of a power supply, and current
is supplied to the workpiece 1 via the power-feeding section and
the transfer jig 20.
[0052] The workpiece 1 that is suspended from (held by) the
transfer jig 20 is serially transferred along a transfer direction
A illustrated in FIG. 2 (i.e., along the depth direction in FIG.
1). A chain that is continuously driven using a sprocket, a
cylinder, and the like may be used as a means that serially
transfers the workpiece 1. The transfer jig 20 holds one workpiece
1. As illustrated in FIG. 2, a plurality of workpieces 1 are
serially transferred in the plating tank 10. When the workpiece 1
is a rigid body (e.g., circuit board), the transfer jig 20 can hold
the workpiece 1 in a suspended state by chucking the upper end of
the workpiece 1. When the workpiece 1 is a flexible body (e.g.,
flexible circuit board), the transfer jig 20 chucks the upper end
and the lower end of the workpiece 1 using a frame. FIG. 1
illustrates an upper frame 20A and a lower frame 20B of the
transfer jig 20.
[0053] As illustrated in FIGS. 1 and 2, a plurality of nozzles 30
that are disposed at a position opposite to the workpiece 1, and
that discharge the plating solution to the workpiece 1 are provided
in the plating tank 10. In one embodiment of the invention in which
each side of the workpiece 1 is plated, the nozzles 30 are disposed
on each side of the serial transfer path of the workpiece 1 (i.e.,
disposed in two rows). The upper end of each nozzle 30 is closed,
and the lower end of each nozzle 30 communicates with a supply
channel of a plating solution supply section 11 that is provided at
the bottom of the plating tank 10. A perforated plate 11A may be
provided in the middle of the supply channel of the plating
solution supply section 11.
[0054] A plurality of nozzle holes (not illustrated in the
drawings) are formed in the side of the nozzle 30 that faces the
workpiece 1 at intervals in the vertical direction. A fresh plating
solution that has been supplied to the nozzle 30 from the plating
solution supply section 11 is discharged to the plating target
surface of the workpiece 1 from each nozzle hole at a given spray
angle. Note that the nozzle 30 is formed of an insulator, and does
not adversely affect an electric field that is applied to the
workpiece 1.
[0055] The lower end of the nozzle 30 is secured on the plating
solution supply section 11. An upper end-securing section 31 is
secured on the upper end of the nozzle 30. The upper end-securing
section 31 is secured on a beam member 32 that extends in the
transfer direction A inside the plating tank 10. The beam member 32
is supported on the peripheral wall 10A of the plating tank 10 via
a beam support member 33.
[0056] A plurality of anodes 40 are provided in the plating tank
10, the plurality of anodes 40 being disposed at a position
opposite to the workpieces that are serially transferred in the
plating tank 10. The anodes 40 are disposed on each side of the
serial transfer path of the workpiece 1 (i.e., disposed in two
rows) for the reason described above in connection with the nozzles
30. Each anode 40 is connected to a positive terminal of a power
supply (not illustrated in the drawings). Note that each power
supply that is connected to one anode 40 can independently control
the current value.
[0057] An insulating section (e.g., insulating caps 41 and 42) may
be disposed on each end (upper end and lower end) of the anode 40.
The insulating cap 41 that is disposed on the lower end of the
anode 40 is secured on the plating solution supply section 11 via a
mounting section 43. The insulating caps 41 and 42 define an
electric field region in the vertical direction by insulating the
upper end and the lower end of the anode 40. An electrode lead
section 44 that is electrically connected to the anode 40 is
provided to the insulating cap 42 that is disposed on the upper end
of the anode 40. Each electrode lead section 44 that is connected
to each anode 40 extends upward beyond the liquid level L in the
plating tank 10, and is connected to a common electrode 45. Note
that each electrode lead section 44 may be connected to a
corresponding power supply so that the current value of each anode
40 can be independently controlled. The insulating caps 41 and 42
may be configured so that the vertical position thereof can be
adjusted corresponding to the size of the workpiece 1.
[0058] A mask member 50 may be provided directly under the
workpiece 1. The mask member 50 has a groove that is formed along
the transfer direction A (see FIG. 2). The lower end of the
workpiece 1 may be inserted into the groove of the mask member 50
to mask the lower end of the workpiece 1. In one embodiment of the
invention, the lower frame 20B of the transfer jig 20 is inserted
into (masked by) and guided by the groove of the mask member 50.
Note that the vertical position of the mask member 50 can be
adjusted corresponding to the size of the workpiece 1.
2. Positional Relationship Between Nozzle and Anode
[0059] In one embodiment of the invention, a plurality of nozzles
30 and a plurality of anodes 40 are alternately disposed along the
transfer direction A in which a plurality of workpieces 1 are
serially transferred (see FIG. 2). This makes it possible to
dispose the nozzles 30 and the anodes 40 at an sufficient
(appropriate) density relative to the plating target surface of the
workpiece 1. At least one anode 40 is disposed between two adjacent
nozzles 30 that are disposed at an appropriate interval in a plan
view. The arrangement pitch of the nozzles 30 may be set to 60 to
90 mm, for example. The serial plating system according to one
embodiment of the invention is thus characterized in that at least
one anode 40 (one anode 40 in FIG. 2) is disposed between two
nozzles by dividing an anode that has been normally formed to have
a given length and disposed on the back side of a plurality of
nozzles 30 opposite to the workpiece 1.
[0060] Specifically, a plurality of anodes 40 can be disposed close
to the plating target surface of the workpiece 1 to such an extent
that interference with each nozzle 30 does not occur (see FIG. 1).
Therefore, since the distance between the plating target surface of
the workpiece 1 and the anode 40 can be reduced, the current
density between the plating target surface of the workpiece 1
(cathode) and the anode 40 increases. The plating thickness of the
plating target surface of the workpiece 1 per unit time increases
as the current density increases. Therefore, a given plating
thickness can be achieved without increasing the total length of
the plating tank 10. This makes it possible to reduce the total
length of the serial plating system. Moreover, since the distance
between the plating target surface of the workpiece 1 and the anode
40 can be reduced, it is also possible to reduce the size of the
serial plating system in the widthwise direction.
[0061] In one embodiment of the invention, the anodes 40 can be
disposed close to the plating target surface of the workpiece 1 to
a maximum extent by disposing the nozzles 30 and the anodes 40 to
overlap in a side view (FIG. 1) along the transfer direction A (see
FIG. 2). This layout is first accomplished by providing at least
one anode 40 between two adjacent nozzles 30, but is never
accomplished by a conventional anode that has been normally formed
to have a given length and disposed on the back side of a plurality
of nozzles 30 opposite to the workpiece 1.
3. Profile of Anode
[0062] The horizontal cross-sectional profile of the nozzle 30 and
the anode 40 is not particularly limited. However, it is preferable
to ensure that the plating solution that has been discharged from
the nozzle 30 toward the workpiece 1 can escape from the space
between the plating target surface of the workpiece 1 and the anode
40 since the distance between the plating target surface of the
workpiece 1 and the anode 40 is reduced.
[0063] For example, each anode 40 may be formed to have a curved
profile so that the distance from the plating target surface of
each workpiece 1 increases as the distance from an electrode
centerline B that divides each anode 40 into two parts in a plan
view and perpendicularly intersects the transfer direction A
increases (see FIG. 2). For example, each anode 40 may have a
curved horizontal cross-sectional profile (see FIG. 2) without
having any corners. Note that each anode 40 may have an elliptical
horizontal cross-sectional profile or the like. If each anode 40
has a rectangular profile in a plan view, the distance between the
plating target surface of the tabular workpiece and each anode 40
is constant. Therefore, the plating solution discharged from the
nozzle 30 is trapped in a narrow range corresponding to the
constant distance and is hard to escape through a narrow clearance
between the nozzle 30 and the anode 40. According to one embodiment
of the invention, since the distance between the plating target
surface of the workpiece 1 and the anode 40 increases as the
distance from the electrode centerline B increases, the plating
solution can escape from the space between the plating target
surface of the workpiece 1 and the anode 40 through a wider
clearance between the nozzle 30 and the anode 40. Note that it is
preferable that each anode 40 have a circular horizontal
cross-sectional profile rather than an elliptical horizontal
cross-sectional profile as long as the horizontal cross-sectional
area is identical in order to dispose the center of each anode 40
closer to the plating target surface of the workpiece 1 while
preventing interference with each nozzle 30.
[0064] When each anode 40 has a curved horizontal cross-sectional
profile, the distance between the workpiece and the anode differs
depending on the profile position of the anode. However, since the
workpiece 1 is serially transferred, the plating thickness can be
made uniform in the serial transfer direction A of the workpiece 1.
Accordingly, the in-plane uniformity of the plating thickness of
the workpiece 1 can be ensured by managing the perpendicularity and
the like of the anode 40 so that a non-uniform plating thickness
distribution does not occur in the vertical direction of the
workpiece 1.
4. Structure of Anode
[0065] A soluble anode or an insoluble anode may be used as the
anode 40. The soluble anode is formed so that the electrode
material is dissolved and serves as a plating component. The
soluble anode is consumed, and must be exchanged. Note that the
soluble anode has a drawback in that it contains impurities (e.g.,
phosphorus (P)) in addition to the plating component. The insoluble
anode is formed so that the electrode material is not dissolved.
When using the insoluble anode, metal ions (e.g., cupric oxide)
present in the plating solution contained in the plating tank 10
serve as a plating component, and the insoluble anode is merely
used as an electrode. In one embodiment of the invention, it is
preferable to use the insoluble anode as the anode 40. In
particular, when achieving a high current density of 10 to more
than 10 A/dm2, for example, the soluble anode is consumed rapidly.
Therefore, it is preferable to use the insoluble anode as the anode
40.
[0066] As illustrated in FIG. 3A, the anode 40 that is formed using
the insoluble anode may include an anode main body 40A that is
positioned on the center side, and is formed of a metal, an alloy,
or the like, and a partition 40B that covers the anode main body
40A. The anode main body 40A is formed in the shape of a hollow
tube in order to reduce the weight of the anode 40. Note that the
anode main body 40A may be formed in the shape of a solid rod. The
partition 40B is formed of a material that does not block an
electric field (electrons), and does not allow the plating solution
to pass through. The partition 40B isolates the anode main body 40A
positioned on the center side from the plating solution. The
partition 40B thus allows the anode 40 to function as an insoluble
anode. In this case, at least the partition 40B has a circular
horizontal cross-sectional profile. It is preferable that the
partition 40B be disposed at a distance from the anode main body
40A. This is because it is necessary to provide a space that
accommodates gas generated from the anode main body 40A. The lower
end of the partition 40B that is immersed in the plating solution
contained in the plating tank 10 is liquid-tightly and air-tightly
sealed. The upper end of the partition 40B may be open to the
atmosphere.
[0067] When the partition 40B that is flexible and does not have a
shape retention capability is disposed at a distance from the anode
main body 40A, a shape retention member 40C may be disposed between
the anode main body 40A and the partition 40B (see FIG. 3B). The
partition 40B exhibits a shape retention capability by being
secured on the shape retention member 40C. As illustrated in FIG.
3C, a plurality of spacer members 40D may be disposed between the
anode main body 40A and the shape retention member 40C in order to
separate the partition 40B from the anode main body 40A.
5. Profile of Nozzle
[0068] Since the cross-sectional area of the nozzle 30 is normally
smaller than that of the anode 40, the horizontal cross-sectional
profile of the nozzle 30 is less restricted as compared with the
anode 40. The nozzle 30 may have a rectangular horizontal
cross-sectional profile. Note that it is preferable that the nozzle
30 have a chamfered profile in order to dispose the anode 40 closer
to the plating target surface of the workpiece 1 while preventing
interference with each nozzle 30. In one embodiment of the
invention, each nozzle 30 has a circular horizontal cross-sectional
profile having a diameter D1 that is smaller than the diameter D2
of the horizontal cross section of each anode 40.
6. Detailed positional relationship between nozzle and anode in
plan view
[0069] As illustrated in FIGS. 2 and 4, the center P1 of the
horizontal cross section of each nozzle 30 may be disposed at a
position closer to the plating target surface of each workpiece 1
as compared with the center P2 of the horizontal cross section of
each anode 40.
[0070] Specifically, the center P1 of the horizontal cross section
of each nozzle 30 and the center P2 of the horizontal cross section
of each anode 40 may be disposed in a staggered arrangement (see
FIGS. 2 and 4). Note that the center P1 of the horizontal cross
section of each nozzle 30 and the center P2 of the horizontal cross
section of each anode 40 may be disposed along a straight line L1
along the transfer direction A (see FIG. 5A). The above
configuration makes it possible to easily prevent interference with
the nozzle 30 while maximizing the diameter D2 of each anode 40
that is disposed between two adjacent nozzles 30 as compared with
the case where the center P1 of the horizontal cross section of
each nozzle 30 and the center P2 of the horizontal cross section of
each anode 40 are disposed along the straight line L1 (see FIG.
5A).
[0071] As illustrated in FIG. 5B, a plurality of anodes 40 may be
disposed between two nozzles 30 (i.e., an example in which at least
one anode 40 is disposed between two nozzles 30). In FIG. 5B, the
center P1 of the horizontal cross section of each nozzle 30 is
disposed at a position closer to the plating target surface of each
workpiece 1 as compared with the center P2 of the horizontal cross
section of each anode 40 in the same manner as in FIG. 4. If the
arrangement pitch of the nozzles 30 is identical in FIGS. 4 and 5B,
it is necessary to reduce the diameter D2 of the anode 40 in FIG.
5B as compared with FIG. 4. If the diameter D2 of the anode 40 is
identical in FIGS. 4 and 5B, the arrangement pitch of the nozzles
30 must be increased in FIG. 5B as compared with FIG. 4. Therefore,
the layout illustrated in FIG. 4 is better than that illustrated in
FIG. 5B.
[0072] In one embodiment of the invention, a first minimum distance
.delta.1 from each nozzle 30 to the plating target surface of each
workpiece 1 may be set to be less than a second minimum distance
.delta.2 from each anode 40 to the plating target surface of each
workpiece 1 (.delta.1<.delta.2), and the outer diameter D1 of
each nozzle 30 may be set to be less than the second minimum
distance .delta.2 (D1<.delta.2) (see FIG. 4). The first minimum
distance M may be set to 10 mm.ltoreq..delta.1.ltoreq.20 mm, and
the second minimum distance .delta.2 may be set to 15
mm.ltoreq..delta.2.ltoreq.35 mm, for example.
[0073] This makes it possible to dispose the nozzle 30 closer to
the workpiece 1 as compared with the anode 40, and makes it
unnecessary to increase the supply pressure of the plating
solution. It is also possible to prevent a situation in which the
plating solution that is discharged from the nozzle 30 to the
workpiece 1 at a given spray angle in a plan view is blocked by the
anode 40.
[0074] Since the curvature of the nozzle 30 can be increased by
setting the diameter D1 of the nozzle 30 that is disposed close to
the workpiece 1 to be less than the second minimum distance
.delta.2 between the anode 40 and the workpiece 1, it is possible
to easily provide an escape space for the plating solution.
[0075] When the minimum distance M between the nozzle 30 and the
workpiece 1 is set to 10 mm.ltoreq..delta.1.ltoreq.20 mm, for
example, the speed of a jet nozzle stream that is discharged from
the nozzle 30 and reaches the workpiece 1 increases. Since the area
of the jet nozzle stream is pressurized, a negative-pressure area
may occur around the area of the jet nozzle stream. Since a
plurality of nozzle holes are formed in the nozzle 30 at intervals
in the vertical direction, a negative-pressure area is formed
between two nozzle holes.
[0076] If the flow of the plating solution between the workpiece 1
and the nozzle 30 (anode 40) is insufficient, the plating solution
may not enter the negative-pressure area. In particular, a flexible
workpiece 1 may be drawn toward the nozzle 30. Therefore, it is
important to ensure that the plating solution discharged from the
nozzle 30 can escape from the space between the workpiece 1 and the
anode 40 in order to prevent a phenomenon in which the workpiece 1
is drawn toward the negative-pressure area.
[0077] As illustrated in FIG. 6, the anode 40 may have a horizontal
cross-sectional profile (e.g., rectangular horizontal
cross-sectional profile) other than a circular horizontal
cross-sectional profile. In FIG. 6, the relationships
".delta.1<.delta.2" and "D1<.delta.2" are satisfied. When the
anode 40 has a rectangular horizontal cross-sectional profile (see
FIG. 6), since the entire long side of the anode 40 is positioned
at the second minimum distance .delta.2 from the workpiece 1, and
the anode 40 has corners that are not chamfered, the escape space
for the plating solution is narrow as compared with the layout
illustrated in FIG. 4. Therefore, the layout illustrated in FIG. 4
is better than that illustrated in FIG. 6.
[0078] In one embodiment of the invention, a third minimum distance
.delta.3 between each anode 40 and each nozzle 30 may be set to be
less than the second minimum distance .delta.2 from each anode 40
to the plating target surface of each workpiece 1
(.delta.3<.delta.2). This makes it possible to dispose the anode
40 closer to the plating target surface of the workpiece 1. Note
that the plating solution discharged from the nozzle 30 toward the
workpiece 1 can escape from the space between the nozzle 30 (anode
40) and the workpiece 1 into the wide space present in the plating
tank 10 through the space between the nozzle 30 and the anode 40
that are adjacent to each other. This makes it possible to allow
the workpiece 1 to always come in contact with fresh plating
solution, and prevents a situation in which the workpiece 1 is
drawn toward the negative-pressure area.
[0079] The third minimum distance .delta.3 between each anode 40
and each nozzle 30 may be set to be greater than or equal to the
first minimum distance .delta.1 from each nozzle 30 to the plating
target surface of each workpiece 1 (.delta.3.gtoreq..delta.1). In
this case, since the flow resistance of the space between the
nozzle 30 and the anode 40 is equal to or less than the flow
resistance of the space between the workpiece 1 and the nozzle 30,
the plating solution can easily escape into the wide space present
in the plating tank 10 through the space between the nozzle 30 and
the anode 40.
[0080] Although only some embodiments of the invention have been
described in detail above, those skilled in the art would readily
appreciate that many modifications are possible in the embodiments
without materially departing from the novel teachings and
advantages of the invention. Accordingly, such modifications are
intended to be included within the scope of the invention. Any term
cited with a different term having a broader meaning or the same
meaning at least once in the specification and the drawings can be
replaced by the different term in any place in the specification
and the drawings.
[0081] Although the invention has been described using specific
terms, devices, and/or methods, such description is for
illustrative purposes of the preferred embodiment(s) only. Changes
may be made to the preferred embodiment(s) by those of ordinary
skill in the art without departing from the scope of the present
invention. In addition, it should be understood that aspects of the
preferred embodiment(s) generally may be interchanged in whole or
in part.
* * * * *