US20140083842A1

US20140083842A1 - Serial plating system

Info

Publication number: US20140083842A1
Application number: US13/626,769
Authority: US
Inventors: Hitoshi Usuda; Tomohiro Noda
Original assignee: Almex PE Inc
Current assignee: Almex PE Inc
Priority date: 2012-09-25
Filing date: 2012-09-25
Publication date: 2014-03-27

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.

Description

CROSS REFERENCE TO RELATED APPLICATION

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

1. Field of the Invention
The present invention relates to a serial plating system.
2. Description of the Related Art
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.
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.
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.
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.
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

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.
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.
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.
According to one aspect of the invention, there is provided 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.
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.
(2) In the serial plating system,
the plurality of nozzles and the plurality of anodes may be disposed to overlap in a side view along the transfer direction.
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.
(3) In the serial plating system,
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.
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.
(4) In the serial plating system,
each of the plurality of anodes may have a curved horizontal cross-sectional profile.
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.
(5) In the serial plating system,
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.
(6) In the serial plating system,
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.
(7) In the serial plating system,
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.
(8) In the serial plating system,
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.
(9) In the serial plating system,
a first minimum distance δ1 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
an outer diameter of each of the plurality of nozzles may be less than the second minimum distance δ2. 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 δ2 between the anode and the workpiece, it is possible to easily provide an escape space for the plating solution.
(10) In the serial plating system,
a third minimum distance δ3 between each of the plurality of anodes and each of the plurality of nozzles may be less than the second minimum distance δ2. 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.
(11) In the serial plating system,
the third minimum distance δ3 may be equal to or greater than the first minimum distance δ1. 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

FIG. 1 is a schematic cross-sectional view illustrating a serial plating system according to one embodiment of the invention;

FIG. 2 is a schematic plan view illustrating the serial plating system illustrated in FIG. 1;

FIGS. 3A to 3C are horizontal cross-sectional views illustrating an anode;

FIG. 4 is a view illustrating the relationship between a first minimum distance, a second minimum distance, and a third minimum distance;

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

FIG. 6 is a view illustrating an example in which an anode has a rectangular horizontal cross-sectional profile.

DESCRIPTION OF EXEMPLARY EMBODIMENT(S)

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

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.
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.
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.
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.
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.
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.
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.
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.
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

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.
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.
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

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.
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.
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

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.
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.
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

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
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.
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).
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.
In one embodiment of the invention, a first minimum distance δ1 from each nozzle 30 to the plating target surface of each workpiece 1 may be set to be less than a second minimum distance δ2 from each anode 40 to the plating target surface of each workpiece 1 (δ1<δ2), and the outer diameter D1 of each nozzle 30 may be set to be less than the second minimum distance δ2 (D1<δ2) (see FIG. 4). The first minimum distance M may be set to 10 mm≦δ1≦20 mm, and the second minimum distance δ2 may be set to 15 mm≦δ2≦35 mm, for example.
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.
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 δ2 between the anode 40 and the workpiece 1, it is possible to easily provide an escape space for the plating solution.
When the minimum distance M between the nozzle 30 and the workpiece 1 is set to 10 mm≦δ1≦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.
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.
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 “δ1<δ2” and “D1<δ2” 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 δ2 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.
In one embodiment of the invention, a third minimum distance δ3 between each anode 40 and each nozzle 30 may be set to be less than the second minimum distance δ2 from each anode 40 to the plating target surface of each workpiece 1 (δ3<δ2). 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.
The third minimum distance δ3 between each anode 40 and each nozzle 30 may be set to be greater than or equal to the first minimum distance δ1 from each nozzle 30 to the plating target surface of each workpiece 1 (δ3≧δ1). 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.
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.
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.

Claims

What is claimed is:

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 δ1 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 δ2 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 δ2.

10. The serial plating system as defined in claim 9,

a third minimum distance δ3 between each of the plurality of anodes and each of the plurality of nozzles being less than the second minimum distance δ2.

11. The serial plating system as defined in claim 10,

the third minimum distance δ3 being equal to or greater than the first minimum distance δ1.