JP2010065255A - Alloy plating method and alloy plating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alloy plating method and an alloy plating apparatus, by which alloy plating such as lead-free solder can be carried out without requiring a large-sized complicated apparatus or bringing about an increase in management cost, and by which measures against a substitution problem peculiar to alloy plating can be taken. <P>SOLUTION: In the alloy plating method for plating an object to be plated with an alloy by electroplating, tanks the number of which is equal to the number of the kinds of metal elements constituting the alloy are arranged; soluble solid anodes made of the respective metal elements are put in plating solutions in the respective tanks; a cathode made of the object to be plated is put in the plating solution in one of the tanks or in a plating solution in a tank disposed in addition; each of the soluble solid anodes is electrically connected to the cathode through a rectifier; and an electric current is supplied to each of the soluble solid anodes in accordance with the alloy composition. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an alloy plating method and an alloy plating apparatus, and more particularly to an alloy plating method and an alloy plating apparatus for plating an alloy composed of a plurality of metal elements having different standard electrode potentials.

  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.

  Here, in the case of conventional Sn-Pb (solder) plating, since the standard electrode potentials of Sn and Pb are substantially equal, a method of performing electroplating using the alloy itself prepared in a predetermined composition ratio as a soluble solid anode (first method) Alloy plating is possible in the conventional example).

  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, in the above method, a metal having a low standard electrode potential is preferentially plated. Since a metal having a standard electrode potential that is dissolved in the metal is hardly eluted, there arises a problem that the alloy cannot be deposited with a target composition on the material to be plated.

  That is, in the method of the first conventional example, metal ions having a standard electrode potential that is not using a soluble solid anode are not automatically replenished by elution of the anode, so that metal ions are consumed by plating. If it does, the density | concentration in a plating solution will reduce. 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.

  In order to solve this problem, in Patent Document 1 below, a metal having a standard electrode potential noble (a standard electrode potential is high) is supplied from a pure metal anode in an electrolytic cell, and a metal having a standard electrode potential is a base. A method (second conventional example) is disclosed in which a plating solution prepared by supplying pure metal in a separate electrolytic tank or dissolution tank and mixing the solutions generated in the respective tanks is used. .

  Further, in Patent Document 2 below, alloy metal plating in which all metal elements constituting an alloy are arranged as individual soluble solid anodes in the same plating tank, and current is intermittently and alternately supplied to each soluble solid anode. A method (third conventional example) is disclosed.

JP 2003-055598 A JP 2006-257492 A

  However, in the second conventional example, a cathode, an anode and a rectifier are arranged in a plurality of electrolytic cells, respectively, and an ion-selective diaphragm is arranged in the vessel. The device becomes expensive.

  In the third conventional example, if a current is simultaneously supplied to each soluble solid anode constituting the alloy, a potential difference is generated between the soluble solid anodes, and current flows between the soluble solid anodes to perform plating. Therefore, it is not possible to form a plating film having a desired composition on the original object to be plated. Therefore, it is necessary to alternately supply current to each soluble solid anode. However, in supplying current to each soluble solid anode, synchronization by switching or pulse current is required, and the power feeding system becomes complicated. Furthermore, in the time zone when the current does not flow through the soluble solid anode of the metal having a low standard electrode potential, the replacement with the metal having the standard electrode potential advances, leading to fluctuations in liquid concentration and sludge generation. appear.

  The present invention has been made in view of the above problems, and its main purpose is to increase the management cost without requiring a large-scale and complicated apparatus for plating an alloy such as lead-free solder. It is an object of the present invention to provide an alloy plating method and an alloy plating apparatus which can be carried out without incurring, and further, can take measures against substitution problems peculiar to alloy plating.

  In order to achieve the above object, the present invention provides an alloy plating method in which an alloy is plated on an object to be plated by an electrolytic plating method, and the same number of tanks as the types of metal elements constituting the alloy are provided. In the plating solution, a soluble solid anode made of each metal element is arranged, and in the plating solution in any one of the tanks or in a separately provided tank, the cathode made of the object to be plated is arranged, and each of the above-mentioned The soluble solid anode and the cathode are electrically connected via a rectifier, and a current corresponding to the alloy composition is supplied to each of the soluble solid anodes.

  Further, the present invention is an alloy plating apparatus for plating an alloy on an object to be plated by an electrolytic plating method, and has the same number of tanks as the types of metal elements constituting the alloy, and each of the plating solutions in each tank includes A soluble solid anode made of the metal element is arranged, and a cathode made of the object to be plated is arranged in a plating solution in any one of the tanks or in a separately provided tank, and each of the soluble solid anode and the cathode Are electrically connected through a rectifier, and a current corresponding to the alloy composition is supplied to each of the soluble solid anodes.

  According to the present invention, by supplying all the metal elements constituting the alloy from the soluble solid anode made of the respective pure substances, the metal ions consumed for forming the alloy plating film are supplemented by the elution of the soluble solid anode. Thereby, since the metal ion concentration in the plating solution is kept substantially constant without being replenished as a compound solution, the management of the plating solution becomes much easier. For this reason, the effect that the density | concentration management cost of a chemical | medical solution can be reduced significantly is acquired.

  Moreover, according to this invention, all the metal elements which comprise an alloy are arrange | positioned in a separate tank as an individual soluble solid anode, and it is from a to-be-plated object to the tank provided in any one tank or those separately. The cathode is arranged and no cathode is arranged in the other tank, and all the soluble solid anodes are connected to the cathode made of the object to be plated by electrical wiring through a rectifier. As a result, unlike the second conventional example, there is no need to dispose a cathode individually in each tank or an ion-selective diaphragm in the tank. Simplification is possible, and the effect that the cost reduction of an alloy plating apparatus is realizable is acquired.

  Further, according to the present invention, it is possible to prevent current from flowing between the soluble solid anodes by arranging all the metal elements constituting the alloy as separate soluble solid anodes in separate tanks. This makes it possible to stabilize the plating film composition and simultaneously supply a current corresponding to the alloy composition to each soluble solid anode, so that the substitution reaction between a noble metal and a base metal with a standard electrode potential is possible. The effect that the fluctuation | variation of a plating solution composition and generation | occurrence | production of sludge can be suppressed is not produced.

  In the present invention, in an alloy plating composed of a plurality of metals having different standard electrode potentials, all the metal elements constituting the alloy are arranged in separate tanks as individual soluble solid anodes, and one of them or any of them Alternatively, a cathode made of an object to be plated is placed in a separate tank, and all the soluble solid anodes are connected to the cathode made of the object to be plated by electrical wiring via a rectifier. In addition, while electrically insulating the plating solution in each tank, the plating solution in each tank can be circulated and mixed to maintain the same composition, and a current corresponding to the alloy composition is applied to each soluble solid anode. It can be supplied at the same time.

  As a result, the management cost can be reduced by stabilizing the plating solution concentration, and at the same time, the cost of the plating tank can be reduced by simplifying the power supply system for ion extraction of each alloy constituent element, and the replacement problem can be solved. be able to.

  In order to describe the above-described embodiment of the present invention in more detail, an alloy plating method and an alloy plating apparatus according to a first example of the present invention will be described with reference to FIGS. FIG. 1 is a diagram schematically showing a schematic configuration of an alloy plating apparatus according to a first embodiment of the present invention. FIG. 2 is a profile of current flowing through the soluble solid anode in the alloy plating apparatus of the present embodiment, and FIG. 3 is a profile of current flowing through the soluble solid anode in the conventional alloy plating apparatus.

  The present example 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 the standard electrode potential of the constituent metal M is higher than that of the constituent metal N.

  As shown in FIG. 1, the alloy plating apparatus of the present embodiment is composed of a plating tank 1 and an electrolytic tank 2, and in each tank, a plating solution 3 and a plating solution 4 (composition thereof) corresponding to the target plating alloy. And the amount of liquid is not particularly limited.) In the plating solution 3, a cathode 5 made of a material to be plated and a soluble solid anode 6 made of a pure substance of one of the metals constituting the alloy are immersed. Further, a soluble solid anode 7 made of the pure material of the other metal constituting the alloy is immersed in the plating solution 4. A rectifier a1 and a rectifier a2 are arranged independently between the cathode 5 and the soluble solid anode 6, and between the cathode 5 and the soluble solid anode 7, respectively.

  The plating solution 3 and the plating solution 4 are circulated and mixed by the overflow 8 and the pump 9 and are always kept in the same composition. However, the method of circulating / mixing the plating solution is not limited to the method using the overflow 8 or the pump 9, and it is sufficient that the compositions of the plating solution 3 and the plating solution 4 are always kept the same. Further, the circulating flow rate of the plating solution can be appropriately set according to the plating current or the like, and any flow rate may be used as long as the plating solution 3 and the plating solution 4 can be maintained at substantially the same composition.

  It is assumed that the plating solution 3 and the plating solution 4 are insulated from each other while circulating between the plating tank 1 and the electrolytic tank 2. As an example of means for realizing this, as shown in FIG. 1, at the outlet of the overflow 8 or the pump 9, the chemical solution is poured continuously without being poured into the tank. However, any method may be used as long as the purpose of insulating the plating solution 3 and the plating solution 4 is achieved.

  In the alloy plating apparatus having the above configuration, the profiles of currents flowing through the soluble solid anode 6 and the soluble solid anode 7 are as shown in FIG. 2, and no current wraps between the soluble solid anodes. On the other hand, a constant current according to the alloy composition can be applied.

  On the other hand, in the third conventional example, the profile of the current flowing through each soluble solid anode is as shown in FIG. In this method, since each soluble solid anode is arranged in the same plating tank, it is not possible to simultaneously apply current to each soluble solid anode, and it is necessary to supply current alternately and intermittently.

  Comparing FIG. 2 and FIG. 3, the current application method in this embodiment does not need to alternately apply current to each soluble solid anode, and the current supply system can be simplified.

  As described above, in this embodiment, by supplying all the metal elements constituting the alloy from the soluble solid anodes 6 and 7 made of pure substances, the metal ions consumed for forming the alloy plating film are soluble solid anodes. It is compensated by the elution of 6 and 7, and the metal ion concentration in the plating solution can be kept almost constant without being replenished as a compound solution.

  Further, in this embodiment, the cathode 5 made of an object to be plated is disposed only in the plating tank 1, and the cathode for extracting metal ions is disposed in another tank as in the second conventional example, Since it is not necessary to dispose a selective diaphragm, the number of electrodes can be reduced and the plating tank configuration can be simplified.

  Further, in this embodiment, since the plating solution 3 and the plating solution 4 are insulated, there is no current wraparound between the soluble solid anode 6 and the soluble solid anode 7, and the plating film on the cathode 5 made of the material to be plated. It becomes possible to stabilize the composition. In addition, since a current corresponding to the alloy composition can be simultaneously supplied to each of the soluble solid anodes 6 and 7, the standard electrode potential does not undergo a substitution reaction between a noble metal and a base metal, The generation of sludge can be suppressed.

  Next, an alloy plating method and an alloy plating apparatus according to a second embodiment of the present invention will be described with reference to FIGS. 4 and 5 are diagrams schematically showing a schematic configuration of the alloy plating apparatus according to the second embodiment of the present invention.

  In the first embodiment described above, the plating solution 3 and the plating solution are poured by pouring the plating solution 3 of the plating bath 1 into the electrolytic bath 2 by the pump 9 and the plating solution 4 of the electrolytic bath 2 into the plating bath 1 by the overflow 8. Although the solution 4 is circulated and mixed, this embodiment proposes another method for circulating and mixing the plating solution.

  For example, as shown in FIG. 4, a mixing tank 10 is added to the plating tank 1 and the electrolytic tank 2, and the plating solution 3 of the plating tank 1 and the plating solution 4 of the electrolytic tank 2 are poured into the mixing tank 10 by the overflow 8 and mixed. The plating solution 11 mixed in the tank 10 can be poured into the plating tank 1 and the electrolytic tank 2 by the pump 9.

  Further, in order to reliably insulate the plating solution 3 in the plating tank 1 and the plating solution 4 in the electrolytic tank 2, as shown in FIG. 1. It can also be set as the structure poured into the electrolytic cell 2. FIG.

  Thereby, the structure of the plating tank 1 and the electrolytic cell 2 can be simplified. In addition, since the plating solution in each vessel can be sufficiently mixed in the mixing vessel 10, the plating solution composition can be made uniform efficiently.

  Next, an alloy plating method and an alloy plating apparatus according to a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a diagram schematically showing a schematic configuration of an alloy plating apparatus according to a third embodiment of the present invention.

  In the first and second embodiments, the binary alloy plating apparatus has been described. However, the present invention can be similarly applied to a ternary or higher alloy plating apparatus.

  For example, as shown in FIG. 6, an electrolytic bath 12 is added to the plating bath 1, the electrolytic bath 2 and the mixing bath 10 having the configuration shown in FIG. 4, and a soluble solid anode and a cathode 5 immersed in the electrolytic bath 12 are connected by a rectifier a3. The plating solution 3 in the plating tank 1, the plating solution 4 in the electrolytic tank 2, and the plating solution 13 in the electrolytic tank 12 are poured into the mixing tank 10 by the overflow 8, and the plating solution 11 mixed in the mixing tank 10 is pumped by the pump 9. It can be set as the structure poured into the plating tank 1, the electrolytic cell 2, and the electrolytic cell 12. FIG.

  As described above, in this embodiment, since the plating solutions in the respective tanks can be simultaneously mixed in the mixing vessel 10, the plating solution composition can be made uniform efficiently.

  In FIG. 6, the case where the alloy plating apparatus having the configuration of FIG. 4 is applied to a ternary or higher alloy is described. However, the alloy plating apparatus having the configuration of FIG. 1 or 5 is applied to a ternary or higher alloy. Is also possible.

  Next, an alloy plating method and an alloy plating apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a diagram schematically showing a schematic configuration of an alloy plating apparatus according to a fourth embodiment of the present invention.

  In the first to third embodiments described above, the soluble solid anode and the cathode 5 made of a pure substance of any metal constituting the alloy are arranged in the same vessel, but the cathode 5 is different from the soluble solid anode. It can also be arranged in the tank.

  For example, as shown in FIG. 7, only the cathode 5 is disposed in the plating tank 1, the soluble solid anode 6 is disposed in the electrolytic cell 2, the soluble solid anode 7 is disposed in the electrolytic cell 12, and each of the soluble solid anodes 6 and 7 is disposed. And the cathode 5 are connected by rectifiers a 1 and a 2, and the plating solution 3 in the plating tank 1, the plating solution 4 in the electrolytic tank 2, and the plating solution 13 in the electrolytic tank 12 are poured into the mixing tank 10 by the overflow 8. The mixed plating solution 11 can be poured into the plating tank 1, the electrolytic tank 2, and the electrolytic tank 12 by the pump 9.

  As described above, the same effects as those of the first to third embodiments can be obtained by disposing the cathode 5 and the soluble solid anode in separate tanks.

  In FIG. 7, only the cathode 5 is arranged in the plating tank 1 with respect to the plating apparatus having the configuration of FIG. 4, but the same applies to the alloy plating apparatus having the configurations of FIGS. 1, 5, and 6. It is possible to apply to.

  In each of the above embodiments, the basic structure of the alloy plating apparatus of the present invention is shown. However, the present invention is not limited to the above embodiment, and the configuration thereof is not deviated from the gist of the present invention. It can be changed as appropriate. For example, since each tank is made independent in the present invention, heating means such as a heater is arranged in each tank, and the temperature of the plating solution in each tank is individually set to control the plating reaction of each metal element. You can also.

  As an application example of the present invention, it is used in general electrolytic alloy plating processes such as plating on general metal parts, plating on semiconductor lead frames, plating on electronic circuit parts such as printed boards and bump plating on semiconductor wafers. Apparatus.

It is a figure which shows typically schematic structure of the alloy plating apparatus which concerns on the 1st Example of this invention. It is a figure which shows the profile of the electric current which flows into the soluble solid anode in the alloy plating apparatus which concerns on the 1st Example of this invention. It is a figure which shows the profile of the electric current which flows into the soluble solid anode in the conventional alloy plating apparatus. It is a figure which shows typically schematic structure of the alloy plating apparatus which concerns on the 2nd Example of this invention. It is a figure which shows typically other schematic structure of the alloy plating apparatus which concerns on the 2nd Example of this invention. It is a figure which shows typically schematic structure of the alloy plating apparatus which concerns on the 3rd Example of this invention. It is a figure which shows typically schematic structure of the alloy plating apparatus which concerns on the 4th Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plating tank 2 Electrolytic tank 3 Plating liquid 4 Plating liquid 5 Cathode 6 Soluble solid anode 7 Soluble solid anode 8 Overflow 9 Pump 10 Mixing tank 11 Plating liquid 12 Electrolytic tank 13 Plating liquid a1, a2, a3 Rectifier

Claims (8)

In an alloy plating method for plating an alloy to be plated by an electrolytic plating method,
There are as many tanks as the types of metal elements that make up the alloy,
In the plating solution in each tank, a soluble solid anode made of each metal element is arranged,
In the plating solution in any one of the tanks or in a separately provided tank, the cathode made of the object to be plated is disposed,
Electrically connecting each soluble solid anode and the cathode via a rectifier;
An alloy plating method, wherein a current corresponding to an alloy composition is supplied to each of the soluble solid anodes. Circulate and mix the plating solution in each tank in an electrically insulated state.
2. The alloy plating method according to claim 1, wherein a current corresponding to the alloy composition is simultaneously supplied to each of the soluble solid anodes.   3. The alloy plating method according to claim 2, wherein the plating solution in each tank is poured into another tank in a drop state. Furthermore, a mixing tank is provided,
Plating solution in each tank is poured into the mixing tank in a drop state,
3. The alloy plating method according to claim 2, wherein the plating solution in the mixing tank is poured into each tank in a drop state. In an alloy plating apparatus that plating an alloy to be plated by electrolytic plating,
It has the same number of tanks as the types of metal elements that make up the alloy,
In the plating solution in each tank, a soluble solid anode made of each metal element is disposed,
In the plating solution in any one of the tanks or in a separately provided tank, the cathode made of the object to be plated is disposed,
Each of the soluble solid anode and the cathode is electrically connected via a rectifier,
An alloy plating apparatus, wherein a current corresponding to the alloy composition is supplied to each of the soluble solid anodes. A means for circulating and mixing the plating solution in each tank in an electrically insulated state,
6. The alloy plating apparatus according to claim 5, wherein a current corresponding to the alloy composition is simultaneously supplied to each of the soluble solid anodes.   7. The alloy plating apparatus according to claim 6, wherein said means is means for injecting the plating solution in each tank into another tank in a drop state. Furthermore, a mixing tank is provided,
The means is a means for injecting the plating solution in each tank into the mixing tank in a drop state, and injecting the plating solution in the mixing tank into each tank in a drop state. 6. The alloy plating apparatus according to 6.

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