JP3921165B2 - Continuous plating equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a continuous plating apparatus that performs electrolytic plating by continuously passing a plurality of strip-shaped workpieces while immersed in a plating bath.
[0002]
[Prior art]
An example of a conventional continuous plating apparatus is shown in FIG. In FIG. 6, the chain conveyor CV circulated in an annular shape is held by the beam 18 supported by the sprocket SP and the support column 17 and continuously travels in the direction of the arrow in the figure. A workpiece that is an object to be plated is suspended from a chain conveyor CV, and sequentially passes through various processing units connected in series, whereby plating is continuously performed on the surface thereof. An example of the plating process will be described. The workpiece is hung on the chain conveyor CV via the workpiece mounting jig by the load unit LD, and passes through the pretreatment process including the pretreatment unit 11, the treatment liquid recovery unit 12, and the water washing unit 13 three times. Is degreased and activated. Next, for example, Ni plating is performed by the plating processing unit 14, the processing liquid recovery unit 12, and the water washing unit 13, and then, for example, Au plating is performed by the plating processing unit 14, the processing liquid recovery unit 12, and the water washing unit 13. Done. Thereafter, the work is dried by the drying unit 15, and the work is removed from the work attachment jig at the unloading unit UL, and the plating process for the work is completed. Thereafter, the post-processing unit 16, the processing liquid recovery unit 12, and the water washing unit 13 perform post-processing of the work attachment jig, a new work is loaded, and the next plating cycle is started. The chain conveyor CV is in a state in which a plurality of workpieces are always suspended until the plating of the workpieces of a predetermined lot is completed, and the plating processing is continuously performed on each workpiece.
[0003]
In general, when electrolytic plating is performed, the plating film forming speed changes due to a change in current density (current value per unit area) on the surface of the workpiece to be plated. Therefore, unlike the above continuous plating apparatus by horizontal running of the workpiece, in the plating apparatus of the system that moves the workpiece after being immersed in the plating bath from the upper side and performing the plating process in a stationary state and then moving upward, For the change in current density due to the change in the resistance value of the circuit due to the change in the distance between the workpiece and the plating electrode, the current control is performed using a constant current circuit so that the current value is constant, and hence the current density is constant. Has been done.
[0004]
[Problems to be solved by the invention]
However, in the continuous plating apparatus in which the workpiece as described above travels horizontally, the plating bath length is conventionally determined based on the required processing time (film thickness and throughput), and the workpiece is plated intermittently. Since it is thrown into the bath, moves through the plating bath, passes through and is carried out, the plating area in each plating bath increases and decreases continuously. In this case, even if a constant current circuit is used to control a constant current between the workpiece and the plating electrode, the processing area changes with the movement of the workpiece and the current density changes. There is a problem that the quality of the plating film varies and the plating characteristics are affected.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a continuous plating apparatus that can stabilize the current density with a simple configuration and obtain stable film formation characteristics.
[0006]
[Means for Solving the Problems and Effects of the Invention]
In order to achieve the above object, the invention of claim 1 is directed to an electrode in a plating bath filled with a plating solution, and transports a plurality of workpieces to be plated through workpiece mounting jigs, respectively. In a continuous plating apparatus that hangs on a rail to face the electrode and applies a voltage between the electrode and the workpiece while traveling while being immersed in a plating solution in the plating bath. The plurality of workpieces have the same size and shape, the workpieces are suspended from the transport rail at a constant pitch, and the length of the plating bath is an integral multiple of the suspended workpiece pitch. It is a certain continuous plating apparatus.
[0007]
In the above configuration, since the length of the plating bath is an integral multiple of the constant pitch of the workpiece, the surface area to be plated of the workpiece of the same size and shape existing in the plating bath is constant regardless of the running state of the workpiece. It becomes. For this reason, by supplying a constant current using a constant current circuit, the current density on the surface to be plated can be kept constant. Therefore, stable plating characteristics (plating thickness, plating film quality, etc.) can be obtained in the continuous plating treatment of strip-shaped (flat plate) workpieces by a constant current circuit.
[0008]
According to a second aspect of the present invention, in the continuous plating apparatus according to the first aspect, each of the workpiece mounting jigs includes a power feeding portion, and a voltage is applied to each workpiece via the power feeding portion.
[0009]
In the above configuration, each work mounting jig is provided with a power supply unit to apply a voltage to each work, so that power can be stably supplied to the work even when the work is traveling and transported. Thus, stable plating characteristics (plating thickness, plating film quality, etc.) can be obtained.
[0010]
According to a third aspect of the present invention, in the continuous plating apparatus according to the first or second aspect, the workpiece mounting jigs are electrically connected to each other by a conductor cable.
[0011]
In the above configuration, since the work attachment jigs are electrically connected to each other with a conductor cable, the work attachment jigs can complement each other to stabilize power feeding. Stable plating characteristics (plating thickness, plating film quality, etc.) can be obtained.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a continuous plating apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the structure of the transport mechanism for the strip-shaped workpiece W and the plating tank. In addition, the whole structure of the continuous plating apparatus is the same as that of the continuous plating apparatus 1 shown in FIG. 6 demonstrated as a prior art. The transport rail 21, the chain guide 22 and the power supply rail 23 shown in FIG. 1 (a) have an annular structure surrounding the continuous plating apparatus, and the chain conveyor CV shown in FIG. 1 (b) also has an annular structure. is doing. The chain conveyor CV is a flexible conveyor that is driven by a sprocket SP (see FIG. 6) and travels in an upper space in the continuous plating apparatus while being sandwiched and guided by a chain guide 22. Below the chain conveyor CV, work attachment jigs 30 are fixed at predetermined intervals, and run together with the chain conveyor CV. The workpiece attachment jig 30 sandwiches and holds the flat workpiece W on the left and right sides in the traveling direction, and conveys the workpiece.
[0013]
The workpiece W held and conveyed in this way enters the plating tank 40 from one side wall of the plating tank 40 shown in FIG. 1C and exits from the other side wall. The plating tank 40 has a front chamber 44, a plating bath 41, and a rear chamber 45 from the entry side, and has side chambers 43 on the left and right of the plating bath 41. The partition plate between the front chamber 44 and the rear chamber 45 and the plating bath 41 is provided with a slit SL, and the workpiece W enters and exits the plating bath 41 through the slit SL. The plating bath 41 is filled with a plating solution supplied from the side wall of the plating solution discharge head 50 having the plating electrode E. Further, a slat plate 42 is provided between the side chamber 43 and the plating bath 41, and the plating solution in the plating tub 41 flows over the top of the sill plate 42 into the side chamber 43. Further, the plating solution also flows out from the slit SL. The plating solution that has flowed out is collected in a reserve tank (not shown) and recycled.
[0014]
The internal structure of the plating bath 41 will be described. FIG. 2 shows a cross section of the plating tank 40. A large number of discharge holes for discharging a plating solution are provided on the side wall of the plating solution discharge head 50 facing the workpiece W, and a plating electrode E is provided in parallel to the side wall and the workpiece W. A pipe connected to a reserve tank (not shown) is provided below the plating solution discharge head 50. In addition, a plating solution sent from a reserve tank is sprayed to both sides of the workpiece W from the discharge hole by a feeding pump (not shown) provided in the middle of the piping, and a newer plating solution is always applied to both sides of the workpiece W. Is supplied as a replacement.
[0015]
Power supply will be described. FIG. 2 described above shows the structure of the power feeding section, and FIG. 3 shows the electrical connection between the workpiece mounting jigs. A power feeding portion (power feeding brush) 31 is provided on the upper side surface of the work mounting jig 30, and is urged by the urging spring 32 to be pressed against the power feeding rail 23. A constant current power source (not shown) is connected between the plating electrode E in the plating bath 41 and the power supply rail 23, and a power supply unit 31 that travels with the work attachment jig with respect to the power supply rail 23 that is stationary. A current circuit for plating is formed by sliding the side surface of the power supply rail 23. Moreover, each workpiece | work attachment jig | tool 30 is mutually electrically connected by the conductor cable 33, and electric power feeding is stabilized when each workpiece | work attachment jig | tool 30 complements each other.
[0016]
Next, stabilization of the current density when the work passes through the plating bath intermittently one after another will be described. FIG. 4 shows a workpiece passing through the plating bath. As shown in FIG. 4, the workpieces W are electrically connected to each other by the conductor cable 33 and run in the plating solution F of the plating bath 41 by the chain conveyor CV while maintaining a constant pitch P. The plating bath length of the plating bath 41 is a distance in which the plating solution F exists, and is a distance between the inner walls of the plating bath 41, which is defined as a plating bath length (plating bath length) L.
[0017]
FIG. 5 shows how the surface area of the workpiece in the plating bath varies with time depending on the relationship between the plating bath length L and the workpiece pitch P. When a constant current power source is connected to the plating electrode, the change in the work surface area corresponds to the change in the current density of the work. Here, for the sake of simplicity, the case where the length of one workpiece W is related to the plating bath length L is shown. In the upper part of each figure, the range of the plating bath length L of the plating bath that moves relative to the workpieces W1, W2, and W3 is shown by a figure in which black circles are connected by a line (the workpiece is in the left direction and is plated. The bathtub moves to the right). FIG. 5A shows a change in the surface area of the workpiece in the plating bath when the plating bath length L is equal to the workpiece pitch P (L = P). This generally indicates that the plating bath length L is an integral multiple of the pitch P. The same as in the case of equality (L = n · P). FIG. 5B shows the surface area change of the workpiece in the plating bath when the plating bath length L is smaller than the workpiece pitch P (L <P). FIG. 5C shows the plating bath length L when the plating bath length L is the workpiece. The surface area change of the workpiece | work in the plating bath when larger than the pitch P of (L> P) is shown. 5B and 5C, when a large number of workpieces W are involved in the plating bath length L, (n-1) · P <L <n · P and n · P <L <( n + 1) · P.
[0018]
In FIG. 5A, a point a1 indicates a moment when the left end of the work W1 starts to come out from the left end of the plating bath and at the same time the left end of the work W2 enters the plating bath. Point a2 indicates the moment when the workpiece W1 has finished coming out of the left end of the plating bath, and at the same time the moment when the left end of the workpiece W2 has finished entering the plating bath. Thus, when the plating bath length L is equal to the workpiece pitch P (L = P), or generally when the plating bath length L is equal to an integral multiple of the pitch P (L = n · P), the plating bath Since the surface area of the work flowing out from the surface and the surface area of the work flowing in are equal, when a constant current is supplied using a constant current circuit, the current density is always kept constant.
[0019]
In FIG. 5B, point b1 is the moment when the left end of the workpiece W1 starts to come out from the left end of the plating bath. At this time, the workpiece W2 is still outside the plating bath, and finally the workpiece W2 at the point b2. Begins to enter the plating bath. Therefore, the surface area of the workpiece in the plating bath decreases from the point b1 to the point b2. Similarly, from the point b2 to the point b3, the surface area of the workpiece in the plating bath is constant, and thereafter, the surface area increases toward the point b4 and becomes constant from the point b4 to the point b5.
[0020]
In FIG. 5C, the point c1 is the moment when the left end of the work W1 starts to come out from the left end of the plating bath. At this time, the left end of the work W2 is in the plating bath. The surface area is constant, and then at point c2, the workpiece W1 has not yet exited from the plating bath, but the workpiece W2 has entered the plating bath, and from this state, the workpiece W1 has further exited from the plating bath. Until c3, the surface area of the workpiece in the plating bath decreases. Similarly, from point c3 to point c4, the surface area of the workpiece in the plating bath is constant, and then the surface area increases toward point c5.
[0021]
As described above, when the plating bath length L is not equal to an integral multiple of the pitch P (L ≠ n · P), the surface area of the workpiece flowing out of the plating bath and the surface area of the workpiece flowing in are generally different. Even if a constant current is passed using the current circuit, the current density varies.
[0022]
The present invention is not limited to the above-described configuration, and various modifications can be made. For example, although the example of the workpiece attachment jig that holds two workpieces in parallel has been described above, the present invention can be similarly applied to holding one workpiece or holding a plurality of workpieces in parallel. Further, in the above description, the case where the work is suspended and transported in the plating bath has been described. However, the present invention is also applied to the case where the work is supported and transported from below or when the work is transported horizontally. be able to. In addition, the present invention can be similarly applied not only to film formation by electrolytic plating, but also to film reduction processing in which a plurality of workpieces are continuously conveyed and a certain film thickness is removed by the effect of electrolysis.
[Brief description of the drawings]
1A is a cross-sectional perspective view of a work conveying rail and a power supply rail of a continuous plating apparatus according to an embodiment of the present invention, FIG. 1B is a perspective view of a work mounting jig of the apparatus, and FIG. The perspective view of the plating tank of an apparatus.
FIG. 2 is a cross-sectional view taken along the line AA in FIG.
FIG. 3 is a perspective view of a work conveyance rail, a power supply rail, and a work mounting jig of the apparatus.
FIG. 4 is a schematic cross-sectional view of the plating tank during the work processing in the apparatus of the above-mentioned work direction.
5A is a time change diagram of a work surface area during plating treatment by the apparatus as described above, and FIGS. 5B and 5C are change views of a work surface area when the work pitch and the length of the bath are incompatible.
FIG. 6 is a plan view of a continuous plating apparatus to which the present invention and the present invention are applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Continuous plating apparatus 21 Conveying rail 30 Work mounting jig 31 Feeding part 33 Conductor cable 40 Plating tank 41 Plating bath E Electrode L Plating bath length P Pitch W Workpiece

Claims (3)

An electrode is exposed to a plating bath filled with a plating solution, a plurality of workpieces to be plated are respectively suspended on a transport rail via a workpiece mounting jig so as to face the electrode, and the plating bath In a continuous plating apparatus for plating the workpiece by applying a voltage between the electrode and the workpiece while running in a state immersed in the plating solution in the inside,
The plurality of workpieces have the same size and shape,
The workpiece is suspended from the transport rail at a constant pitch,
The continuous plating apparatus, wherein the length of the plating bath is an integral multiple of the pitch of the suspended workpiece.   2. The continuous plating apparatus according to claim 1, wherein each of the workpiece attachment jigs includes a power feeding unit, and a voltage is applied to each workpiece via the power feeding unit.   The continuous plating apparatus according to claim 1, wherein the workpiece mounting jigs are electrically connected to each other by a conductor cable.

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