Continuous plating apparatus configured to control the power applied to individual work pieces within a plating tank

A continuous plating apparatus, when the number of the workpieces simultaneously transferred in the plating tank in a completely immersed state is N, (N+1) cathode relay members that extend in a workpiece transfer direction and (N+1) power supply units being provided outside the plating tank, anode terminals of the power supply units being connected to opposed anodes that are provided in the plating tank, cathode terminals of the power supply units being respectively connected to the cathode relay members so that power is supplied to each of the workpieces transferred in the plating tank from a corresponding power supply unit among the power supply units through a corresponding cathode relay member among the cathode relay members, and each of the power supply units being able to be controlled by constant current control when being transferred in the plating tank in a completely immersed state, by current gradual increase control when being carried into the plating tank in a partially immersed state, and by current gradual decrease control when being carried out from the plating tank in a partially immersed state.

CROSS REFERENCE TO RELATED APPLICATION

Japanese Application No. 2007-284841, filed on Nov. 1, 2007, is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a continuous plating apparatus capable of continuously plating each workpiece transferred in a plating tank while supplying power to each workpiece.

InFIG. 9, workpieces50(50A to50E) are thin sheet-shaped articles (e.g., printed circuit board material), and are continuously transferred in a plating tank10P in a workpiece transfer direction (X) at constant intervals. A workpiece continuous transfer means includes a transfer rail (not shown) that is disposed above a workpiece transfer path and extends in the direction X, a plurality of sliders that are movably secured along the transfer rail (not shown; a portion that serves as a power supply path is indicated by36P (36PA to36PE)), a chain conveyer (not shown) that transfers each slider in synchronization, and the like.

Anodes15PL and15PR are commonly used for the workpieces (cathodes)50A to50E. The anodes15PL and15PR are disposed on either side (upper side or lower side inFIG. 9) of the workpiece transfer path, and extend in the direction X. The anodes15PL and15PR are connected to an anode terminal21of a power supply device20P through a power supply cable17P (17PL and17PR). A cathode terminal25of the power supply device20P is electrically connected to the workpieces50A to50E through a power supply cable37P, the transfer rail, and the sliders (power supply paths36PA to36PE).

The power supply device20P has a capacity sufficient to supply a set current value (e.g., 1 A/dm2) to sides Fr and Fl of each workpiece50, and is driven by constant current control. The workpieces50A to50E can thus be continuously plated while continuously supplying power to the workpieces50A to50E transferred in the plating tank10P. For example, JP-A-2000-226697 discloses a constant current density profile at the middle way in the plating tank (seeFIG. 3B).

The electrical resistance and the electrode-electrode distance vary corresponding to each workpiece due to the structure of the electrical path (e.g., cable17P (17PL and17R) or power supply path36P (36PA to36PE)) or assembly. This causes the following problems. Specifically, a variation in the thickness of the coating or the process quality may occur. The thickness of the coating or the process quality may differ between one side (first side) and the other side (second side) of a single workpiece. The thickness of the coating cannot be caused to differ corresponding to each workpiece. The thickness of the coating cannot be caused to differ corresponding to each side of a single workpiece. When further uniformity in the thickness of the coating and the process quality are desired, the thickness of the coating and the process quality must be made uniform along the workpiece transfer direction (front, center, and rear).

SUMMARY OF THE INVENTION

According to a firs aspect of the invention, there is provided a continuous plating apparatus capable of continuously plating workpieces transferred through a plating tank while continuously supplying power to the workpieces,

when the number of the workpieces simultaneously transferred in the plating tank in a completely immersed state is N, (N+1) cathode relay members that extend in a workpiece transfer direction and (N+1) power supply units being provided outside the plating tank, and opposed anodes that extend in the workpiece transfer direction and are commonly used for the workpieces being provided in the plating tank,

anode terminals of the power supply units being connected to the anodes and cathode terminals of the power supply units being respectively connected to the cathode relay members so that power is supplied to each of the workpieces transferred in the plating tank from a corresponding power supply unit among the power supply units through a corresponding cathode relay member among the cathode relay members, and

each of the power supply units being able to be controlled by constant current control when being transferred in the plating tank in a completely immersed state, by current gradual increase control when being carried into the plating tank in a partially immersed state, and by current gradual decrease control when being carried out from the plating tank in a partially immersed state.

According to a second aspect of the invention, there is provided a continuous plating apparatus capable of continuously plating workpieces transferred through a plating tank while continuously supplying power to the workpieces,

when the number of the workpieces simultaneously transferred in the plating tank in a completely immersed state is N, (N+1) cathode relay members that extend in a workpiece transfer direction, (N+1) first-side power supply units, and (N+1) second-side power supply units being provided outside the plating tank, and a first-side anode and a second-side anode that extend in the workpiece transfer direction and are commonly used for the workpieces being oppositely disposed in the plating tank,

anode terminals of the first-side power supply units being connected to the first-side anode, anode terminals of the second-side power supply units being connected to the second-side anode, and cathode terminals of the first-side power supply units and cathode terminals of the second-side power supply units being respectively connected to the cathode relay members so that power is supplied to each of the workpieces transferred in the plating tank from a corresponding first-side power supply unit among the first-side power supply units and from a corresponding second-side power supply unit among the second-side power supply units through a corresponding cathode relay member among the cathode relay members, and

each of the first-side power supply units and the second-side power supply units being able to be controlled by constant current control when being transferred in the plating tank in a completely immersed state, by current gradual increase control when being carried into the plating tank in a partially immersed state, and by current gradual decrease control when being carried out from the plating tank in a partially immersed state.

DETAILED DESCRIPTION OF THE EMBODIMENT

The invention may provide a continuous plating apparatus capable of plating workpieces while changing a set current value for each workpiece, and particularly a continuous plating apparatus capable of plating workpieces while changing a set current value for each side of each workpiece.

According to one embodiment of the invention, there is provided a continuous plating apparatus capable of continuously plating workpieces transferred through a plating tank while continuously supplying power to the workpieces,

when the number of the workpieces simultaneously transferred in the plating tank in a completely immersed state is N, (N+1) cathode relay members that extend in a workpiece transfer direction and (N+1) power supply units being provided outside the plating tank, and opposed anodes that extend in the workpiece transfer direction and are commonly used for the workpieces being provided in the plating tank,

anode terminals of the power supply units being connected to the anodes and cathode terminals of the power supply units being respectively connected to the cathode relay members so that power is supplied to each of the workpieces transferred in the plating tank from a corresponding power supply unit among the power supply units through a corresponding cathode relay member among the cathode relay members, and

each of the power supply units being able to be controlled by constant current control when being transferred in the plating tank in a completely immersed state, by current gradual increase control when being carried into the plating tank in a partially immersed state, and by current gradual decrease control when being carried out from the plating tank in a partially immersed state.

According to this embodiment, since each workpiece can be continuously plated at a current value set corresponding to each workpiece, a uniform, high-quality plated coating having a uniform thickness corresponding to the set current value can be formed on each workpiece.

According to one embodiment of the invention, there is provided a continuous plating apparatus capable of continuously plating workpieces transferred through a plating tank while continuously supplying power to the workpieces,

when the number of the workpieces simultaneously transferred in the plating tank in a completely immersed state is N, (N+1) cathode relay members that extend in a workpiece transfer direction, (N+1) first-side power supply units, and (N+1) second-side power supply units being provided outside the plating tank, and a first-side anode and a second-side anode that extend in the workpiece transfer direction and are commonly used for the workpieces being oppositely disposed in the plating tank,

anode terminals of the first-side power supply units being connected to the first-side anode, anode terminals of the second-side power supply units being connected to the second-side anode, and cathode terminals of the first-side power supply units and cathode terminals of the second-side power supply units being respectively connected to the cathode relay members so that power is supplied to each of the workpieces transferred in the plating tank from a corresponding first-side power supply unit among the first-side power supply units and from a corresponding second-side power supply unit among the second-side power supply units through a corresponding cathode relay member among the cathode relay members, and

each of the first-side power supply units and the second-side power supply units being able to be controlled by constant current control when being transferred in the plating tank in a completely immersed state, by current gradual increase control when being carried into the plating tank in a partially immersed state, and by current gradual decrease control when being carried out from the plating tank in a partially immersed state.

According to this embodiment, since each workpiece can be continuously plated at a current value set corresponding to each side of each workpiece, a uniform, high-quality plated coating having a uniform thickness corresponding to the set current value can be formed on each side of each workpiece.

Each of the above continuous plating apparatuses may further comprise:

a plurality of workpiece carriers that are secured on a transfer rail that extends in the workpiece transfer direction so that the workpieces can be transferred by the workpiece carriers; and

a plurality of arm members, a base of each of the arm members being secured on a corresponding workpiece carrier among the workpiece carriers, and an end of each of the arm members engaging a corresponding cathode relay member among the cathode relay members so as to allow relative movement,

wherein each of the arm members is formed to allow direct or indirect current supply; and

wherein power can be supplied to each of the workpieces transferred in the plating tank from a corresponding power supply unit among the power supply units through a corresponding cathode relay member among the cathode relay members and a corresponding arm member among the arm members.

This makes it possible to transfer each workpiece and to supply power more stably and smoothly in addition to achieving the above-described effects.

Embodiments of the invention are described below with reference to the drawings.

First Embodiment

As shown inFIGS. 1 to 6B, a continuous plating apparatus can continuously plate each workpiece50transferred in a plating tank10while supplying power to each workpiece50. The continuous plating apparatus is formed so that power can be supplied to each workpiece50from a power supply unit20through a cathode relay member31during transfer by constant current control at a set current value (A/dm2) corresponding to each workpiece50(first side Fl+second side Fr). The continuous plating apparatus can perform current gradual increase control when introducing the workpiece50into the plating tank10, and can perform current gradual decrease control when discharging the workpiece50from the plating tank10.

InFIG. 1, N (N is an integer equal to or larger than one, e.g., four) workpieces50(50A to50D or50B to50E) can be simultaneously transferred in the plating tank10in a transfer direction (X) in a completely immersed state. The term “completely immersed state” refers to a state in which the plating target sides (first side Fl+second side Fr) of the workpiece50are immersed in a plating solution Q shown inFIG. 2. Therefore, when the workpiece50A is discharged from an outlet10B of the plating tank10and the workpiece50E is introduced into an entrance10F, (N+1) (i.e., five) workpieces50(50A to50E) are immersed in the plating tank10.

In this case, the workpieces50B to50D are in a completely immersed state, and the workpieces50A and50E are in a partially immersed state. The term “partially immersed state” refers to a state in which at least of the plating target sides (first side Fl+second side Fr) of the workpiece50are partially immersed in the plating solution Q in the longitudinal direction.

When the number of workpieces50that can be simultaneously transferred in the plating tank10in a completely immersed state is N (e.g., three (five)), the numbers of cathode relay members31and power supply units20are respectively (N+1) (=four (six)).

As shown inFIG. 1, a pair of anodes15L and15R that extend in the direction X are disposed in the plating tank10(plating solution Q) so that the anodes15L and15R are opposite to each other. The anodes15L and15R are commonly used for each workpiece50(50A to50E), and have a length corresponding to the length of the plating tank. The distance (electrode-electrode distance) between each of the anodes15L and15R and each workpiece50(each of the sides10land10r) during transfer is maintained at a constant value (predetermined value).

In this embodiment, the anodes15L and15R are formed by disposing a plurality of cylindrical anode bags15LB and15RB (schematically shown inFIG. 2) that contain a number of soluble anode balls (copper balls) in the direction X. Note that not only the soluble anode balls in this embodiment, but publicly known electrodes may also be used as the anodes15L and15R.

Since the number of workpieces50that can be simultaneously transferred in the plating tank10in a completely immersed state is N (four), (N+1) (i.e., five) cathode relay members31(31A to31E) that extend in the direction X shown inFIGS. 1 and 2are disposed outside the plating tank10. The term “outside the plating tank10” may be an arbitrary location outside the plating solution Q. In this embodiment, the cathode relay members31are disposed in parallel in the direction of the width of the plating tank10(seeFIG. 2) so that the workpiece50can be transferred and power can be supplied to the workpiece50more smoothly.

Each of the cathode relay members31(31A to31E) has a copper rail structure having a depressed cross section. Each cathode relay member31is formed so that at least the inner surface that comes in contact with (the surface of) a vertical section of an arm member (e.g.,35A1) is formed of an electrical conductor (e.g., copper material).

A workpiece continuous transfer means80is a means that continuously transfers each workpiece50in the direction X. As shown inFIG. 2, the workpiece continuous transfer means80includes a transfer rail81that is disposed above the plating tank10and extends in the direction X, a plurality of workpiece carriers83(83A,83B, . . . ) that are movably secured along the transfer rail81, a chain conveyer (not shown) that transfers each workpiece carrier83in synchronization, and a plurality of arm members35(35A,35B, . . . ).

The arm member (e.g.,35A) includes a workpiece-holding arm member35A2that extends in the rightward direction inFIG. 2, and a current-supply arm member35A1that extends in the leftward direction inFIG. 2. The arm member35includes a horizontal section which extends in the horizontal direction and of which the base is attached to the workpiece carrier83, and a vertical section provided on the end of the horizontal section.

The workpiece-holding arm member35A2that forms the workpiece continuous transfer means80holds the workpiece in a transfer path (i.e., the center of the plating tank in the widthwise direction) through a power supply jig (not shown) provided on the lower end of the vertical section. Therefore, each workpiece can be continuously transferred in the direction X at a set transfer speed V.

A continuous power supply means30is a means that supplies plating power to each workpiece50(cathode) from each power supply unit20(25). In this embodiment, the continuous power supply means30is formed by effectively utilizing the elements of the workpiece continuous transfer means80. Specifically, the continuous power supply means30includes the transfer rail81shown inFIGS. 1 and 2, the workpiece carrier (e.g.,83A), a power-supply-side current supply path (current-supply arm member35A1), a workpiece-side current supply path (workpiece-holding arm member35A2; including the power supply jig), the cathode relay member (31A), a cathode-side cable (37A), an anode-side cable17(17L and17R), and the power supply unit20. The continuous power supply means30can directly supply power to each workpiece50.

Since the arm member35(power-supply-side current supply path (35A1) and workpiece-side current supply path (35A2)) that includes the workpiece-holding arm member35A2that extends in the rightward direction inFIG. 2and the current-supply arm member35A1that extends in the leftward direction inFIG. 2forms the continuous power supply means30together with the transfer rail81, the workpiece carrier83, and the like, the arm member35is formed of an electrical conductor (e.g., copper material). The power-supply-side current supply path and the workpiece-side current supply path may be formed using a bus bar or a power supply cable provided along the corresponding arm member (35A1or35A2). In this case, the continuous power supply means30indirectly supplies power to each workpiece50.

An anode terminal21of each power supply unit20is connected to the anodes15L and15R through the cable17(17L and17R). A cathode terminal25of each power supply unit20(20A to20E) is connected to the cathode relay member31(31A to31E) through the cable37(37A to37E). This makes it possible to supply power to each workpiece50that is continuously transferred in the plating tank10from the power supply unit20(25) through the cathode relay member31.

As described above, the workpiece carriers83are secured on the transfer rail81that extends in the direction X so that workpiece can be transferred, the arm member35of which the base is secured on the workpiece carrier83and the end engages the corresponding cathode relay member31so as to allow relative movement is provided, the arm member35is formed to allow direct (or indirect) current supply, and power can be supplied to each workpiece50that is continuously transferred in the plating tank10from the power supply unit20(25) through the cathode relay member31and the arm member35.

As shown inFIG. 1, the power supply units20(20A to20E) are provided in the same number (five) as the number (five) of the cathode relay members31(31A to31E). The power supply capacity is determined depending on the relationship with the workpiece50(processing target). Specifically, the current value can be changed corresponding to each workpiece (each power supply unit), and constant current control at a set current value Is can be performed.

Specifically, the power supply unit20performs constant current control in a period in which the workpiece50is transferred in the plating tank10in a completely immersed state, performs current gradual increase control in a period in which the workpiece is introduced into the plating tank in a partially immersed state, and performs current gradual decrease control in a period in which the workpiece is discharged from the plating tank in a partially immersed state.

InFIG. 6A(the vertical axis indicates current (I), and the horizontal axis indicates time (T)), a current (Iin) is gradually increased in proportion to the time (plating area) until the set current value Is is reached in a period T12(=t1to t2) in which the workpiece is introduced into the plating tank in a partially immersed state. The power supply unit20performs constant current control at the set current value Is when the workpiece has been completely immersed (t2). As shown inFIG. 6B, the power supply unit20performs current gradual decrease control instead of constant current control at the set current value Is in a period T34(=t3to t4) in which the workpiece is discharged from the plating tank in a partially immersed state. The current (Iin) is gradually decreased in inverse proportion to the time (plating area).

InFIG. 3, a computer60includes a CPU (having a clock function)61, a ROM62, a RAM63, a hard disk (HDD)64, an operation section (PNL)65, a display section (IND)66, a plurality of interfaces (I/F)71and72, and a plurality of input/output ports (I/O)75and76. The computer60forms an operation drive control device that has a setting function, a selection function, an instruction function, a drive control function, and the like, and controls the operation of the entire continuous plating apparatus.

As shown inFIG. 4, a table64M provided in the HDD64stores the type (A to E) of the workpiece50, the dimension (lengths La to Le) of each workpiece in the direction X, and the set current value (Isa to Ise). The table64M also stores the transfer speed (V) of each workpiece50by the workpiece continuous transfer means. The above-mentioned information (A, La, Isa, and V) is input using the operation section65while visually checking the input state on the display section66.

The period T12in which each workpiece50is introduced into the plating tank in a partially immersed state (=period T34in which each workpiece is discharged from the plating tank in a partially immersed state) is automatically stored as a workpiece period (times Ta to Te) that is calculated by a period calculation means (CPU61and ROM62) using the lengths La to Le and the transfer speed V.

InFIG. 3, the power supply units20A to20E are connected to the interface71, and the workpiece continuous transfer means80is connected to the interface72. An incoming workpiece identification sensor55and an outgoing workpiece identification sensor56are connected to the input/output port75. An incoming workpiece sensor58and an outgoing workpiece sensor59are connected to the input/output port76.

In this embodiment, the incoming workpiece identification sensor55(outgoing workpiece identification sensor56) is provided on the upstream side of the incoming workpiece sensor58(outgoing workpiece sensor59) in the direction X, and is disposed at a position at which the workpiece50(type) can be identified before whether or not the workpiece50is introduced (discharged) is detected. The incoming workpiece identification sensor55(outgoing workpiece identification sensor56) identifies the workpiece50by reading a mark attached to (e.g., bonded to or written on) the workpiece50when the workpiece50passes through an identification area. Note that the mark may be attached to a structure (e.g., workpiece carrier81) corresponding to each workpiece50.

The incoming workpiece sensor58(outgoing workpiece sensor59) is a photoelectric sensor. The incoming workpiece sensor58(outgoing workpiece sensor59) detects that whether or not the workpiece50passes through a partial immersion introduction (discharge) area using a detection light beam. The incoming workpiece sensor58(outgoing workpiece sensor59) is turned ON when the workpiece50has entered the partial immersion introduction (discharge) area, remains in an ON state when the workpiece50is moved in the partial immersion introduction (discharge) area, and is turned OFF when the workpiece50has exited the partial immersion introduction (discharge) area.

A workpiece information readout control means (61and62), a power supply automatic ON/OFF control means (61and62), a power supply unit selection control means (61and62), a workpiece current setting control means (61and62), a workpiece current gradual increase control means (61and62), a workpiece constant current control instruction means (61and62), and a workpiece current gradual decrease control means (61and62) are formed by a ROM that stores a control program and a CPU that executes the control program while loading the control program into a RAM.

The workpiece information readout storage control means (61and62) reads information corresponding to the workpiece50identified by the incoming workpiece identification sensor55by searching the table64M shown inFIG. 4, and stores the information in a work area of the RAM63. The power supply unit selection control means (61and62) selects (ST11) the power supply unit20corresponding to the workpiece50based on stored information when the workpiece50has been introduced into the plating tank10(YES in ST10shown inFIG. 5). The power supply automatic ON/OFF control means (61and62) outputs a power-on signal to the selected power supply unit20to activate (ST12) the power supply unit20. When the workpiece50is discharged from the plating tank10(NO in ST19), the power supply automatic ON/OFF control means (61and62) outputs a power-off signal to inactivate (ST20) the power supply unit20.

The workpiece current setting control means (61and62) outputs a current setting signal corresponding to the set current value to each power supply unit20.

The workpiece current gradual increase control means (61and62) generates a gradual increase instruction signal for gradually increasing the current value from zero (0) to the set current value Isa in a period in which the workpiece (e.g.,50A) is introduced into the plating tank in a partially immersed state (=period in which each workpiece is discharged from the plating tank in a partially immersed state=Ta) when the incoming workpiece sensor58is turned ON (i.e., the workpiece (50A) has entered a partial immersion introduction area), and outputs the gradual increase instruction signal to the power supply unit20A. Note that the workpiece current gradual increase control means (61and62) may generate the gradual increase instruction signal before the incoming workpiece sensor58is turned ON. A gradual increase control signal may be generated and output instead of the gradual increase instruction signal depending on the structure of the power supply unit20A.

The workpiece current gradual decrease control means (61and62) generates a gradual decrease instruction signal for gradually decreasing the current value from the set current value Isa to zero (0) in a period in which the workpiece (50A) is discharged from the plating tank in a partially immersed state (=Ta) when the outgoing workpiece sensor59is turned ON (i.e., the workpiece (50A) has entered a partial immersion discharge area), and outputs the gradual decrease instruction signal to the power supply unit20A. Note that the workpiece current gradual decrease control means (61and62) may generate the gradual decrease instruction signal before the outgoing workpiece sensor59is turned ON. A gradual decrease control signal may be generated and output instead of the gradual decrease instruction signal depending on the structure of the power supply unit20A.

The workpiece constant current control instruction means (61and62) generates and outputs a constant current control instruction signal to the power supply unit20in a period (transfer in a completely immersed state) from the time when the incoming workpiece sensor58is turned OFF to the time when the outgoing workpiece sensor59is turned ON.

The effects (operation) are described below.

When the workpiece50A has been transferred in the direction X by the workpiece carrier (83A (35A2)) shown inFIG. 2and reached a position in front of the entrance10F shown inFIG. 1, the incoming workpiece identification sensor55reads the mark attached to the workpiece50A. The workpiece information readout storage control means (61and62) reads the information (Isa, La, Ta, V) corresponding to the identified workpiece50A by searching the table64M shown inFIG. 4, and stores the information in the work area. When the incoming workpiece sensor58has been turned ON (YES in ST10shown inFIG. 5), the power supply unit selection control means (61and62) selects (ST11) the power supply unit20corresponding to the read mark. The power supply automatic ON/OFF control means (61and62) outputs the power-on signal to the selected power supply unit20(ST12).

The cathode (50A) and the anodes15L and15R are thus electrically connected to the power supply unit20A. The cathode terminal25is connected to the workpiece50A through the cable37A, the cathode relay member31A, and the arm member35A (power-supply-side current supply path35A1, workpiece carrier83A, and workpiece-side current supply path35A2). The stationary cathode relay member31A and the movable arm member35A (power-supply-side current supply path35A1) are electrically connected during the relative movement (when the workpiece is transferred) in the direction X. The anode terminal21is connected to the anodes15L and15R through the cable17(17L and17R). Therefore, plating power can be supplied. The workpiece current gradual increase control means (61and62) generates the gradual increase instruction signal, and outputs (ST13) the gradual increase instruction signal to the power supply unit20A. Therefore, the current value Iin supplied to the workpiece50A is gradually increased from zero (0) to the constant current value Is (seeFIG. 6A) in a period (Ta) in which the workpiece is introduced into the plating tank in a partially immersed state. Specifically, since the current value Isa supplied per unit area of each side of the workpiece50A is constant, the quality can be made uniform.

When the incoming workpiece sensor58has been turned OFF (YES in ST14), the workpiece constant current control instruction means (61and62) generates and outputs (ST15) the constant current control instruction signal corresponding to the set current value Is a that has been read and stored to the power supply unit20A. The set current value Isa (A/dm2) is supplied per unit area of the workpiece50A transferred in a completely immersed state by supplying the constant current value Is to the workpiece50A. Specifically, constant current control is performed.

The workpiece50A is continuously transferred in the plating tank10(plating solution Q) in the direction X. In this case, a current flows from the anode15L disposed on the first side Fl to the first side Fl so that a coating is precipitated on the first side Fl, and a current flows from the anode15R disposed on the second side Fr to the second side Fr so that a coating is precipitated on the second side Fr. The thickness of the plated coating increases in proportion to the plating time.

When the outgoing workpiece sensor59has been turned ON (YES in ST16), the power supply unit selection control means (61and62) selects (ST17) the power supply unit20corresponding to the mark that has been read by the outgoing workpiece identification sensor56. Since the transfer speed is constant, the workpiece50A may be identified utilizing the identification result at the entrance10F. In this case, the outgoing workpiece identification sensor56may be omitted.

The workpiece current gradual decrease control means (61and62) then generates the gradual decrease command signal, and outputs (ST18) the gradual decrease command signal to the power supply unit20A. Therefore, the current value Idg supplied to the workpiece50A is gradually decreased from the constant set current value Is (seeFIG. 6B6A) to zero (0) in a period (Ta) in which the workpiece is discharged from the plating tank in a partially immersed state. Specifically, the current value Isa supplied per unit area of each side of the workpiece50A is constant at the outlet10B in the same manner as at the entrance10F. Therefore, the quality can be made uniform.

When the outgoing workpiece sensor59has been turned OFF (YES in ST19), the power supply automatic ON/OFF control means (61and62) outputs the power-off signal to the selected power supply unit20(ST20). The power supply unit20A is then turned OFF.

The workpieces50B,50C,50D, and50E are plated in the same manner as the workpiece50A. This also applies to subsequent workpieces50A to50E. Note that the workpieces are transferred to the cathode relay members31A to31E so that two or more workpieces50do not simultaneously serve as a load.

According to this embodiment, since each workpiece50can be continuously plated at a set current value corresponding to each workpiece50, a uniform, high-quality plated coating having a uniform thickness corresponding to the set current value can be formed on each workpiece50.

Since a plurality of workpieces50that differ in plating details (e.g., the formation area and the thickness of the coating) can be continuously plated while continuously transferring the workpieces50, the productivity increases.

Since the power supply device includes the (N+1) power supply units20, the total power supply capacity and the electrical energy consumption can be reduced as compared with the related-art example.

Since the effects of a variation in the electrical resistance or the electrode-electrode distance due to the structure of the electrical path (e.g., cables17and37or power supply path (31and35)) or assembly can be removed by finely adjusting the set current value corresponding to each workpiece50, the thickness of the coating and the process quality can be made more uniform.

Since inconvenience when introducing or discharging the workpiece into or from the plating bath10can be eliminated by current gradual increase control at the entrance10fand current gradual decrease control at the outlet10B, a situation in which the thickness of the coating and the process quality differ along the workpiece50(front, center, and rear) in the direction X does not occur.

The arm member (35A (35A2)) of which the base is secured on the workpiece carrier (e.g.,83A) secured on the transfer rail81so that the workpiece can be transferred and the end engages the corresponding cathode relay member31so as to allow relative movement is provided, the arm member (35A (35A2)) is formed to allow direct (or indirect) current supply, and power can be supplied to each workpiece50that is continuously transferred in the plating tank10from the power supply unit20A through the cathode relay member31A and the arm member (35A (35A1and35A2)). Therefore, the workpiece50can be transferred and power can be supplied to the workpiece50more stably and smoothly.

In the first embodiment, instead of the incoming workpiece identification sensor55, the outgoing workpiece identification sensor56, the incoming workpiece sensor58, and the outgoing workpiece sensor59, the incoming workpiece identification sensor55may be used for example. In this case, the incoming workpiece identification sensor55is disposed at the position for the incoming workpiece sensor58to identify the workpiece50and detect the workpiece50entering the partial immersion introduction area. Then the period T12in which each workpiece is introduced into the plating tank in a partially immersed state, the time when the workpiece is completely immersed (t2), and the period T34in which each workpiece is discharged from the plating tank in a partially immersed state inFIGS. 6A and 6Bare obtained by calculation using the transfer speed V and information about the length of the identified workpiece50in the direction X by the period calculation means. By using the result of this calculation, the above-described current gradual increase control and current gradual decrease control can be implemented.

Second Embodiment

As shown inFIGS. 7 and 8, a continuous plating apparatus according to second embodiment can continuously plate each workpiece50transferred in the plating tank10while supplying power to each workpiece50in the same manner as in the first embodiment. In the second embodiment, the set current value (A/dm2) can be supplied corresponding to each side (first side Fl+second side Fr) of each workpiece50.

Specifically, when the number of workpieces50that can be simultaneously transferred in the plating tank10in a completely immersed state is N (e.g., four), (N+1) (=five) cathode relay members31that extend in the direction X and are disposed outside the plating tank10, (N+1) first-side power supply units20L, and (N+1) second-side power supply units20R are provided. A first-side anode15L and a second-side anode15R are disposed in the plating tank10so that the first-side anode15L and the second-side anode15R are opposite to each other, the first-side anode15L and the second-side anode15R extending in the direction X and being commonly used for each workpiece50. The anode terminals21of the first-side power supply units20L are connected to the first-side anode15L, and the anode terminals21of the second-side power supply units20R are connected to the second-side anode15R. The cathode terminals25of the first-side power supply units20L and the cathode terminals25of the second-side power supply units20R are connected to the cathode relay members31. Power can be supplied to each workpiece50transferred in the plating tank10from the first-side power supply unit20L and the second-side power supply unit20R through the cathode relay member31. Each of the first-side power supply units20L and the second-side power supply units20R performs constant current control in a period in which the workpiece50is transferred in the plating tank10in a completely immersed state, performs current gradual increase control in a period in which the workpiece is introduced into the plating tank in a partially immersed state, and performs current gradual decrease control in a period in which the workpiece is discharged from the plating tank in a partially immersed state.

InFIG. 8, the cathode relay members31LRA to31LRE have the structure and the function described in the first embodiment. The cathode relay members31LRA to31LRE are commonly used for the first-side power supply unit20L and the second-side power supply unit20R. As shown inFIG. 7, the cathode terminals25of the first-side power supply units20L and the second-side power supply units20R are connected to the cathode relay members31LRA to31LRE through the cables37L (37LA to37LE) and37R (37RA to37RE).

The anode terminals21of the first-side power supply units20L are connected to only the first-side anode15L through the cable17L so that power can be supplied to only the first side Fl of the workpiece50. The anode terminals21of the second-side power supply units20R are connected to only the second-side anode15R through the cable17R so that power can be supplied to only the second side Fr of the workpiece50.

According to this embodiment, since each workpiece50can be continuously plated at a set current value corresponding to each of the sides Fl and Fr of each workpiece50, a uniform, high-quality plated coating having a uniform thickness corresponding to the set current value can be formed on each side of the workpiece50.

Since a plurality of workpieces50that differ in plating details (e.g., the number of coating formation sides, and the area and the thickness of the coating corresponding to each coating formation side) can be continuously plated while continuously transferring the workpieces50, the productivity increases.

A workpiece50for which only one side (Fl or Fr) is plated can be plated. A workpiece50for which only one side is plated and a workpiece50for which each side is plated can be plated at the same time.

Since the power supply device includes the (N+1) first-side power supply units20L and the (N+1) second-side power supply units20R, the total power supply capacity and the electrical energy consumption can be reduced as compared with the related-art example.

The effects of a variation in the electrical resistance or the electrode-electrode distance due to the structure of the electrical path (e.g., cables17and37or power supply path (31and35)) or assembly can be removed by finely adjusting the set current value corresponding to each workpiece50and the set current value corresponding to each side of each workpiece50. Therefore, the thickness of the coating and the process quality can be made more uniform.

Since the cathode relay member (e.g.,31LRA) is commonly used for the first-side power supply unit20LA and the second-side power supply unit20RA, the structure is simplified and a power loss can be reduced as compared with the case of separately providing the cathode relay member for the first-side power supply unit20LA and the cathode relay member for the second-side power supply unit20RA.

The same effects as those of the first embodiment (e.g., the workpiece50can be transferred and power can be supplied to the workpiece50more smoothly and stably by supplying power through the cathode relay member31LRA and the arm member35A (35A1and35A2)) can also be achieved.

The invention is useful for forming a high-quality plated coating having a uniform thickness on a printed circuit board material and the like.