JP2006257492A - Alloy plating method and alloy plating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alloy plating method and an alloy plating device capable of electroplating alloys different in standard electrode potential only by using soluble anodes. <P>SOLUTION: In a plating liquid 2 within a plating tank 1, the material to be plated is connected to a cathode 3, a rectifier a1 is connected to the space between the cathode 3 and a soluble anode 4 composed of a metal whose standard electrode potential is noble, and a rectifier a2 is connected to the space between the cathode 3 and a soluble anode 5 composed of a metal whose standard electrode potential is base. Electric current is alternately fed to the soluble anode 4 and the soluble anode 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an alloy electroplating method and an alloy plating apparatus for carrying out the same, and in particular, lead in exterior plating of lead frames for semiconductor devices, bump plating on semiconductor wafers, pattern plating of printed wiring boards, and the like. The present invention relates to an alloy plating method represented by free plating and an electrolytic plating apparatus for carrying out the method.

  In recent years, Sn-Pb solder plating, which has been conventionally used for surface treatment of electronic components, has been abolished in the future due to increasing interest in global environmental conservation. Instead, Sn-Zn, Sn-Ag Lead-free solder plating such as Sn-Cu and Sn-Ag-Cu alloys has become the mainstream. In the case of conventional Sn—Pb (solder) plating, a method of performing electrolytic plating using the alloy itself prepared in a predetermined composition ratio as a soluble anode, or a soluble anode made of pure materials of Sn and Pb, respectively, A method has been used in which each anode is plated by applying a current corresponding to the target alloy composition. In the case of Sn—Pb (solder) plating, the standard electrode potentials of Sn and Pb are almost equal, so that any of the above methods can be used for alloy plating.

However, in most alloys including lead-free solder plating, the standard electrode potential of each metal constituting the alloy is different, and as a result, the standard electrode potential is low in any of the above methods. Since the metal is preferentially dissolved in the plating solution and the metal having a standard electrode potential is rarely eluted, there arises a problem that the alloy cannot be deposited with a target composition on the material to be plated. For this reason, conventionally, only a metal whose standard electrode potential is base (low standard electrode potential) is supplied as pure metal, and a metal whose standard electrode potential is noble is supplied as a compound solution. (First conventional example: see, for example, Patent Documents 1 and 2). Alternatively, a metal having a standard electrode potential noble (high standard electrode potential) is supplied from a pure metal anode in an electrolytic cell, and a metal having a standard electrode potential is pure in a separate electrolytic cell or dissolution bath. A plating solution prepared by mixing a solution supplied in metal and generated in each tank is used (second conventional example: see, for example, Patent Documents 3 and 4).
Japanese Patent Laid-Open No. 10-288000 JP 2001-144240 A JP 2003-55798 A JP 2003-160900 A

In the method of the first conventional example, ions of a metal having a standard electrode potential having no standard soluble potential and noble anode are not automatically replenished by elution of the anode. The concentration in the plating solution will decrease. Therefore, in order to keep the plating quality constant by preparing a chemical solution of metal ions with a standard electrode potential noble, monitor the metal ion concentration and replenish metal ions with a standard electrode potential frequently. It is necessary to manage the concentration of the solution, which causes a problem that the management cost increases.
On the other hand, in the method of the second conventional example, a plurality of electrolytic cells must be prepared and the chemical solution must be circulated between them, which requires a lot of space and requires the construction of a chemical solution circulation system. As the apparatus becomes larger and more complicated, the apparatus becomes expensive.
An object of the present invention is to solve the above-mentioned problems of the prior art, and the purpose thereof is to manage alloy plating such as lead-free solder without requiring a large-scale and complicated apparatus. It is to be able to perform without increasing the cost.

  In order to achieve the above object, according to the present invention, there is provided an alloy plating method for plating an alloy on an object to be plated by an electrolytic plating method, wherein all metal elements constituting the alloy are the same as individual soluble solid anodes. An alloy plating method is provided, which is disposed in a plating tank and intermittently supplies a current to each soluble solid anode.

  Further, in order to achieve the above object, according to the present invention, there is provided an alloy plating method for plating an alloy on an object to be plated by an electrolytic plating method, wherein all metal elements constituting the alloy are individually soluble solid anodes. In the same plating tank, a relatively high voltage is applied to a soluble solid anode of a metal element having a high standard electrode potential, and a relatively low voltage is applied to a soluble solid anode of a metal element having a low standard electrode potential. An alloy plating method is provided that is applied.

  In order to achieve the above object, according to the present invention, an alloy plating apparatus for plating an alloy on an object to be plated by an electrolytic plating method, wherein all the metal elements constituting the alloy are separated into individual soluble solid anodes. An alloy plating apparatus comprising a power supply device that is arranged in the same plating tank and that can intermittently supply current to each soluble solid anode is provided.

  In order to achieve the above object, according to the present invention, there is provided an alloy plating apparatus for plating an alloy on an object to be plated by an electrolytic plating method, wherein each of the soluble solids is composed of each metal element constituting the alloy. The anode is disposed in the same plating tank, and a relatively high voltage power source is connected to the soluble solid anode of the metal element having a high standard electrode potential, and relatively to the soluble solid anode of the metal element having a low standard electrode potential. An alloy plating apparatus characterized by being connected to a low-voltage power source is provided.

  Since the alloy plating method according to the present invention supplies current independently to each soluble anode in a time-separated manner, or applies voltage corresponding to each standard electrode potential to each soluble anode. Only one (plating tank) can be used, and the plating apparatus can be greatly downsized and simplified. Further, according to the present invention, it is not necessary to supply a metal having a standard electrode potential noble as a compound solution, and the management of the plating solution is greatly facilitated. Therefore, according to the present invention, alloy plating can be performed easily and at low cost.

Next, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a plating apparatus according to a first embodiment of the present invention, and this embodiment relates to a binary alloy plating apparatus. Prior to the description, it is assumed that metals constituting the target alloy are M and N, and that the constituent metal M has a higher standard electrode potential than the constituent metal N.
The plating tank 1 is filled with a plating solution 2 corresponding to a target plating alloy. The plating solution 2 includes a cathode 3 made of a material to be plated and a standard electrode potential among metals constituting the alloy. The soluble anode 4 made of a pure material of the metal M having the noble metal and the soluble anode 5 made of a pure material of the metal N having a lower standard electrode potential among the metals constituting the alloy are immersed. Rectifiers a1 and a2 are arranged independently between the cathode 3 and the soluble anode 4 and between the cathode 3 and the soluble anode 5, respectively.

Here, the rectifiers a1 and a2 are rectifiers with control poles, and can supply a current having an arbitrary waveform to the soluble anodes 4 and 5, respectively. In order to supply current to each soluble anode at an integrated current value corresponding to the composition of the target alloy, the current value and the energization time can be arbitrarily controlled. The rectifiers a1 and a2 can supply current to each soluble anode while synchronizing with each other.
Using the above plating apparatus, when performing alloy plating, by controlling so that the current supplied to each soluble anode does not overlap at the same time, it is possible to prevent the current from being supplied to a plurality of soluble anodes simultaneously Can do. As described above, by independently supplying a current to each soluble anode, it becomes possible to elute a metal having a standard electrode potential noble and a metal having a standard electrode potential base in an arbitrary ratio in the plating solution. .
According to the present embodiment, it becomes possible to supply all of the metal materials M and N constituting the alloy by the soluble anode. The metal ions consumed to form the alloy plating film are compensated by elution of the soluble anode, and the metal ion concentration in the plating solution can be kept almost constant without replenishing it as a compound solution. become. Further, according to the present invention, both metal ions can be supplied in one plating tank 1, so that the plating apparatus can be configured extremely simply. Therefore, according to this invention, the apparatus cost and running cost which concern on alloy plating can be reduced significantly.

FIG. 2 is a current profile showing an example of current supply to the plating apparatus of the first embodiment shown in FIG. As shown in the figure, the rectifiers a1 and a2 are controlled so that the time during which current is supplied to each of the soluble anode 4 and the soluble anode 5 does not overlap, and each of the soluble anode 4 and the soluble anode 5 has A current having a time width according to the composition ratio between the noble metal M and the base metal N is supplied.
In the example shown in FIG. 2, a rectangular wave is applied to each anode. However, the current profile supplied to the soluble anode 4 and the soluble anode 5 is not limited to the rectangular wave, and can be changed to a waveform represented by an arbitrary curve. Good. In addition, the supplied current does not necessarily have to flow only in one direction, and may temporarily flow in the negative direction. In the present embodiment, it is fundamental that the currents supplied to the respective soluble anodes do not overlap in time, but the currents are supplied simultaneously to both electrodes for a short time. Is not to be excluded. In this case, it is desirable that the total time during which currents are simultaneously supplied to a plurality of electrodes be 1/10 or less of the total time during which currents are supplied only to one electrode. The switching of the current supply is basically performed synchronously, but it may be controlled so that no current is supplied to any anode for some time.

  FIG. 3 is a schematic configuration diagram of a binary alloy plating apparatus according to the second embodiment of the present invention. In FIG. 3, the same reference numerals are given to the same parts as those in the apparatus of the first embodiment shown in FIG. In the present embodiment, a power source b1 and a switch s1 are connected between the cathode 3 and the soluble anode 4, and a power source b2 and a switch s2 are connected between the cathode 3 and the soluble anode 5. Here, the switches s1 and s2 operate in a complementary manner. Therefore, the profile of the current supplied to the soluble anode 4 and the soluble anode 5 is as shown in FIG.

  FIG. 4 is a schematic configuration diagram of a binary alloy plating apparatus according to the third embodiment of the present invention. In FIG. 4, the same reference numerals are given to the parts equivalent to those of the apparatus of the first embodiment shown in FIG. 1, and the duplicate description is omitted. In the present embodiment, a power source b1 and a switch s3 are connected in common between the cathode 3, the soluble anode 4 and the soluble anode 5. Here, the movable contact of the switch s3 is configured to be selectively connected to either the soluble anode 4 or the soluble anode 5. Therefore, the profile of the current supplied to the soluble anode 4 and the soluble anode 5 is as shown in FIG.

FIG. 5 is a schematic configuration diagram of a binary alloy plating apparatus according to the fourth embodiment of the present invention. In FIG. 5, the same reference numerals are given to the same parts as those of the apparatus of the first embodiment shown in FIG. In the present embodiment, a power source b1 and a switch s1 are connected between the cathode 3 and the soluble anode 4, and a power source b1 and a switch s2 are connected between the cathode 3 and the soluble anode 5. That is, the power source b1 is connected to both the soluble anode 4 and the soluble anode 5 in common. Here, the switches s1 and s2 operate in a complementary manner. Therefore, the profile of the current supplied to the soluble anode 4 and the soluble anode 5 is as shown in FIG.
In the embodiment shown in FIG. 3 to FIG. 5, the current supply between the cathode 3 and the anode 4, 5 is performed by a DC power supply, but this may be replaced by a rectifier. In this case, a rectifier with a control pole is not necessarily used.

  FIG. 6: is a schematic block diagram of the plating apparatus of the 5th Embodiment of this invention, Comprising: This Embodiment concerns on the plating apparatus of a ternary alloy. Here, the ternary alloy is composed of metals M, R, and N, where M is the metal having the highest standard electrode potential and N is the metal having the lowest standard electrode potential. R is a metal that is less basic than M and noble than N. The plating tank 1 is filled with a plating solution 2 containing ions of metals M, R, and N. The plating solution 2 includes a cathode 3 made of a material to be plated and a standard of metals constituting an alloy. A soluble anode 4 made of a pure material of the metal M having the highest electrode potential, a soluble anode 5 made of a pure material of the metal N having the lowest standard electrode potential among the metals constituting the alloy, and a metal constituting the alloy Among them, a soluble anode 6 made of a pure material of metal R whose standard electrode potential is lower than M and higher than N is immersed. Rectifiers a1, a2, and a3 are disposed between the cathode 3 and the soluble anode 4, the cathode 3 and the soluble anode 5, and the cathode 3 and the soluble anode 6, respectively.

  Here, the rectifiers a1, a2 and a3 are rectifiers with control poles, and can supply a current having an arbitrary waveform to the respective soluble anodes 4, 5 and 6. And in order to supply an electric current with each integrated current value corresponding to the composition of the target alloy with respect to each soluble anode, it is possible to arbitrarily control an electric current value and energization time. Moreover, each rectifier a1-a3 can supply an electric current to each soluble anode, synchronizing with each other.

FIG. 7 is a current profile showing an example of current supply to the plating apparatus of the fifth embodiment shown in FIG. As shown in the figure, the rectifiers a1, a2, and a3 are controlled so that the time for supplying current to the soluble anode 4, the soluble anode 5 and the soluble anode 6 does not overlap with each other. The soluble anode 5 and the soluble anode 6 are supplied with a current having a time width according to the composition ratio of the metal M, the metal N, and the metal R, respectively.
In the example shown in FIG. 7, a rectangular wave is applied to each anode. However, the current profile supplied to the soluble anode 4 or the soluble anode 6 is not limited to the rectangular wave, and may be changed to a waveform represented by an arbitrary curve. Good. In addition, the supplied current does not necessarily have to flow only in one direction, and may temporarily flow in the negative direction. In the present embodiment, it is fundamental that the currents supplied to the respective soluble anodes do not overlap in time, but the currents are supplied simultaneously to both electrodes for a short time. Is not to be excluded. In this case, it is desirable that the total time during which currents are simultaneously supplied to a plurality of electrodes be 1/10 or less of the total time during which currents are supplied only to one electrode. The switching of the current supply is basically performed synchronously, but it may be controlled so that no current is supplied to any anode for some time.

  FIG. 8 is a current profile showing another example of the alloy plating method of the present invention. In this current supply mode, in order to suppress the displacement and deposition of the metal M having the standard electrode potential noble on the surface of the soluble anode of the metal N having the standard electrode potential, the soluble anode 5 composed of the metal N having the standard electrode potential is used. Supplies a weak current even when no current is supplied for plating. When the current is not supplied to the soluble anode 4, the current for plating to the soluble anode 5 is supplied. The current profile shown in FIG. 8 can be realized, for example, by connecting a direct current power source for supplying a weak current in parallel with the rectifier a2 in the plating apparatus shown in FIG.

  FIG. 9 is a schematic configuration diagram of a binary alloy plating apparatus according to the sixth embodiment of the present invention. The plating apparatus of the present embodiment is an apparatus having a configuration different from that of the above-described modification of the first embodiment for realizing the current profile shown in FIG. In FIG. 9, the same reference numerals are given to the same parts as those of the apparatus of the first embodiment shown in FIG. In the present embodiment, a power source b1 and a switch s1 are connected between the cathode 3 and the soluble anode 4. A series circuit of a power source b2 and a switch s2 and a power source b3 for supplying a weak current are connected in parallel between the cathode 3 and the soluble anode 5. Here, the switches s1 and s2 operate in a complementary manner.

  FIG. 10 is a schematic configuration diagram of a binary alloy plating apparatus according to the seventh embodiment of the present invention. The plating apparatus of the present embodiment is an apparatus having another configuration for realizing the current profile shown in FIG. In FIG. 10, the same reference numerals are given to the same parts as those of the apparatus of the first embodiment shown in FIG. In the present embodiment, a power source b1 and a switch s1 are connected between the cathode 3 and the soluble anode 4. Between the cathode 3 and the soluble anode 5, a series circuit of a power source b2 and a parallel circuit composed of a switch s2 and a resistor R is connected. Here, the circuit of the resistor R is for constantly supplying a weak current to the soluble anode 5. The switches s1 and s2 operate in a complementary manner.

FIG. 11 is a schematic configuration diagram of a binary alloy plating apparatus according to an eighth embodiment of the present invention. The plating apparatus of the present embodiment is an apparatus having still another configuration for realizing the current profile shown in FIG. In FIG. 11, the same reference numerals are given to the same parts as those of the apparatus of the first embodiment shown in FIG. In the present embodiment, the negative electrode side of the power supply b1 is connected to the cathode 3. A switch s1 is connected between the positive electrode side of the power source b1 and the soluble anode 4. Further, a parallel circuit composed of a switch s2 and a resistor R is connected between the positive electrode side of the power source b1 and the soluble anode 5. Here, the circuit of the resistor R is for constantly supplying a weak current to the soluble anode 5. The switches s1 and s2 operate in a complementary manner.
In the embodiment shown in FIG. 9 to FIG. 11, the current supply between the cathode 3 and the anode 4, 5 is performed by a DC power supply, but this may be replaced by a rectifier. In this case, a rectifier with a control pole is not necessarily used.

FIG. 12 is a schematic configuration diagram of a binary alloy plating apparatus according to the ninth embodiment of the present invention. In FIG. 12, the same reference symbols are given to the same parts as those of the apparatus of the first embodiment shown in FIG. 1, and the duplicate description is omitted.
When the object to be plated is front and back like a semiconductor lead frame and has a relatively large area, the plating apparatus of the first embodiment having one soluble anode 4 and one soluble anode 5 realizes a uniform alloy composition. It becomes difficult to do. In the present embodiment, a soluble anode for a noble metal and a soluble anode for a base metal are designated as soluble anodes 4 ₁ to 4 ₆ and soluble anodes 5 _{1 to} 5 ₆ , respectively. The anodes are divided into individual anodes, which are alternately arranged, and an anode group is arranged so as to surround the cathode 3 as a center. By comprising in this way, the dispersion | variation in the quality of the alloy plating by the site | part of to-be-plated object can be suppressed. In addition, in this Embodiment, the division | segmentation number, shape, etc. of a soluble anode can be suitably changed according to the shape etc. of to-be-plated object. Moreover, the supply system of a soluble anode can also be changed suitably. For example, a ball-like soluble anode may be placed in a titanium case, and a current may be indirectly supplied to the anode by connecting a rectifier to the case side. This also applies to the other embodiments.

FIG. 13 is a schematic configuration diagram of a binary alloy plating apparatus according to the tenth embodiment of the present invention. In FIG. 13, the same reference numerals are given to the same parts as those in the apparatus of the ninth embodiment shown in FIG.
When an electric current is applied alternately to the anode made of each metal constituting the alloy, the metal eluted from the side where the current flows is deposited on the side where the electricity does not flow (the electrode floating in the electric circuit). (That is, current flows between the anodes). If this phenomenon continues continuously, the anode, which should be made of a pure substance, will be in the same state as an alloy of two kinds of metals, and the metal concentration in the liquid cannot be kept stable. As a countermeasure, in the plating apparatus of the present embodiment, insulating walls 7 are arranged between the soluble anodes 4 ₁ to 4 ₆ and the soluble anodes 5 _{1 to} 5 ₆ made of the respective metals constituting the alloy, and the anodes are connected to each other. Current flows between them to prevent the deposition of another metal.

FIG. 14 is a schematic configuration diagram of a binary alloy plating apparatus according to an eleventh embodiment of the present invention. In FIG. 14, the same reference numerals are given to the same parts as those of the apparatus of the tenth embodiment shown in FIG.
As shown in FIG. 14, in this embodiment, a power source b1 and a switch s1 are provided between the cathode 3 and the soluble anodes 4 ₁ to 4 _6, and a cathode 3 and the soluble anodes 5 _{1 to} 5 ₆ are provided. A power supply b2 and a switch s2 are connected between them. When the standard electrode potential difference between the two kinds of metals constituting the soluble anode is large, it is desirable to apply a higher voltage to the metal side where the standard electrode potential is noble. Therefore, in this embodiment, the power supply voltage of the power supply b1 that supplies current to the noble metal soluble anodes 4 ₁ to 4 ₆ is the power supply that supplies current to the base metal soluble anodes 5 _{1 to} 5 _6. It is set higher than the power supply voltage of b2. The switches s1 and s2 may be operated complementarily. It is also possible to keep both switches closed. Furthermore, only one switch may be opened and closed (the other switch is continuously closed).
When the switch s1 is operated so as to be normally closed, if the noble metal soluble anodes 4 ₁ to 4 ₆ and the base metal soluble anodes 5 _{1 to} 5 ₆ have the same arrangement configuration, a desired composition ratio is obtained. An alloy may not be obtained. In order to cope with this point, the current may be adjusted by setting the resistance between the soluble anodes 4 ₁ to 4 ₆ and the cathode higher than that between the soluble anodes 5 _{1 to} 5 ₆ and the cathode. As a specific measure, it is conceivable to take one or both of the following (a) and (b).
(A) As shown in FIG. 14, an insulating wall is provided so as to surround the soluble anodes 4 ₁ to 4 ₆ .
(B) The shape and the number of divisions of the soluble anodes 4 ₁ to 4 ₆ are different from those of the soluble anodes 5 _{1 to} 5 ₆ .

The block diagram which shows 1st Embodiment of the alloy plating apparatus of this invention. The current profile of an example of the plating apparatus of the 1st Embodiment of this invention. The block diagram which shows 2nd Embodiment of the alloy plating apparatus of this invention. The block diagram which shows 3rd Embodiment of the alloy plating apparatus of this invention. The block diagram which shows 4th Embodiment of the alloy plating apparatus of this invention. The block diagram which shows 5th Embodiment of the alloy plating apparatus of this invention. The current profile of an example of the plating apparatus of the 5th Embodiment of this invention. The current profile of other examples of the plating method of the present invention. The block diagram which shows 6th Embodiment of the alloy plating apparatus of this invention. The block diagram which shows 7th Embodiment of the alloy plating apparatus of this invention. The block diagram which shows 8th Embodiment of the alloy plating apparatus of this invention. The block diagram which shows 9th Embodiment of the alloy plating apparatus of this invention. The block diagram which shows 10th Embodiment of the alloy plating apparatus of this invention. The block diagram which shows 11th Embodiment of the alloy plating apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plating tank 2 Plating solution 3 Cathode which consists of to-be-plated object 4, 4 ₁ to 4 ₆ Soluble anode which consists of noble metal M with standard electrode potential 5, 51 _{1 to} 5 ₆ Solubility which consists of metal N whose base electrode potential is base Anode 6 Soluble anode made of metal R with intermediate standard electrode potential 7 Insulating wall
a1-a3 rectifier b1-b3 power supply s1-s3 switch

Claims (16)

An alloy plating method in which an alloy is plated on an object to be plated by an electrolytic plating method, in which all metal elements constituting the alloy are arranged as individual soluble solid anodes in the same plating tank, and each soluble solid anode is An alloy plating method characterized by intermittently supplying current. The sum of the time during which intermittent current is supplied simultaneously to a plurality of soluble solid anodes is 1/10 or less of the sum of the time during which intermittent current is supplied to only one soluble solid anode. The alloy plating method according to claim 1. The alloy plating method according to claim 1 or 2, wherein a weak current is constantly applied to one soluble solid anode, and an intermittent current is superposed on the weak current. 2. A relatively high voltage is applied to a soluble solid anode of a metal element having a high standard electrode potential, and a relatively low voltage is applied to a soluble solid anode of a metal element having a low standard electrode potential. 4. The alloy plating method according to any one of items 1 to 3. This is an alloy plating method in which an alloy is plated on an object to be plated by the electrolytic plating method, and all the metal elements constituting the alloy are arranged as individual soluble solid anodes in the same plating tank, and a metal having a high standard electrode potential. An alloy plating method comprising applying a relatively high voltage to a soluble solid anode of an element and applying a relatively low voltage to a soluble solid anode of a metal element having a low standard electrode potential. The alloy plating method according to claim 1, wherein the alloy to be plated is lead-free solder. The alloy plating method according to any one of claims 1 to 5, wherein an alloy to be plated is any one of Sn-Bi, Sn-Ag, Sn-Cu, and Sn-Ag-Cu. An alloy plating apparatus for plating an alloy to be plated by an electrolytic plating method, in which all metal elements constituting the alloy are arranged as individual soluble solid anodes in the same plating tank, and each soluble solid anode An alloy plating apparatus comprising a power supply device capable of intermittently supplying current. The power supply device is configured by a rectifier with a control pole connected between a cathode and each soluble solid anode, or a switch for switching the connection between the rectifier and the rectifier to each soluble solid anode. The alloy plating apparatus according to claim 8. The power supply device includes a DC power source provided for each soluble solid anode, or a DC power source commonly provided for all soluble solid anodes, and a switch for controlling connection of the DC power source to each soluble solid anode. The alloy plating apparatus according to claim 8, wherein the apparatus is an alloy plating apparatus. The alloy plating method according to any one of claims 8 to 10, wherein one soluble solid anode is provided with a power source that always allows a weak current to flow. The alloy plating apparatus according to any one of claims 8 to 11, wherein an insulating wall that suppresses a current flowing between the soluble solid anodes is disposed between the soluble solid anodes. An alloy plating apparatus for plating an alloy on an object to be plated by an electrolytic plating method, wherein a soluble solid anode composed of each metal element constituting the alloy is disposed in the same plating tank and has a high standard electrode potential. Alloy plating characterized in that a relatively high voltage power source is connected to a soluble solid anode of a metal element, and a relatively low voltage power source is connected to a soluble solid anode of a metal element having a low standard electrode potential apparatus. The current flowing through each soluble solid anode is adjusted by adjusting the shape and size of each soluble solid anode and the shape of the insulating wall disposed between each soluble solid anode and the cathode. 13. The alloy plating apparatus according to 13. 15. The alloy plating apparatus according to claim 8, wherein each soluble solid anode is divided into a plurality of parts. 16. The alloy plating apparatus according to claim 8, wherein a soluble solid anode divided into a plurality of parts is disposed so as to surround the cathode.

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