Plating apparatus

Abstract

Provided is a plating apparatus with which the time required for plating is improved and unevenness in the thickness of the obtained plating film is minimized.　This plating apparatus comprises a plating tank storing a plating liquid, a cylindrical metal tube having a hollow part, a cylindrical mesh tube having a hollow part, and a second electrode, wherein: the metal tube is a first electrode; the mesh tube is produced from an insulating material; the metal tube, the mesh tube, and the second electrode are housed in the plating tank; the metal tube is disposed inside the hollow part of the mesh tube; a plating forming part is formed between the inner side of the mesh tube and the outer side of the metal tube; the second electrode is disposed on the outer side of the mesh tube; an upward flow lifting the plating liquid is generated inside the hollow part of the metal tube; and an object to be plated is lifted inside the hollow part of the metal tube by the upward flow of the plating liquid, is discharged to the outside of the metal tube, is stirred, then falls inside the plating forming part, and is plated through application of a current between the metal tube, i.e. the first electrode, and the second electrode during the descent of the object. There is an auxiliary electrode inside the plating part, the auxiliary electrode being electrically connected to the metal tube, i.e. the first electrode.

Description

Plating Equipment

[0001] The present invention relates to a plating apparatus.

[0002] So-called jet-type plating apparatuses are widely used for forming external electrodes of electronic components, etc. Patent Document 1 (JP 2021-138999 A) discloses a jet-type plating apparatus.

[0003] The plating apparatus disclosed in Patent Document 1 includes a plating tank containing a metal tube (cathode) as a first electrode, a mesh tube (partition) made of an insulating material, and a second electrode (anode).

[0004] A metal tube is disposed inside the mesh tube, and a plating formation portion is formed between the inside and outside of the mesh tube. The plating formation portion refers to a region (space) where plating is applied to the object to be plated. A second electrode is disposed outside the mesh tube.

[0005] A jet unit is provided below the metal tube. The jet unit is used to generate an upward flow of plating solution inside the metal tube. That is, in the device disclosed in Patent Document 1, the jet unit is the source that generates a jet of plating solution.

[0006] The plating apparatus disclosed in Patent Document 1 contains a plating solution, an object to be plated (such as an electronic component element), and conductive media in a plating tank. Furthermore, insulating balls may be contained in the plating tank as needed to increase the fluidity of the object to be plated.

[0007] The workpiece, media, and insulating balls ride on the rising current of plating solution generated inside the metal tube, rise inside the metal tube, and are ejected from the top end of the metal tube and stirred.

[0008] The stirred object to be plated, media, and insulating balls are then deposited on the upper side of the plating formation section. At this time, other object to be plated, media, and insulating balls are already packed (deposited) inside the plating formation section. The object to be plated, media, and insulating balls that have deposited on the upper side of the plating formation section then gradually descend inside the plating formation section. At this time, a current is applied between the metal tube, which is the first electrode, and the second electrode, forming a plating film in the plating formation region (the region where the base electrode, etc. is formed) on the surface of the object to be plated.

[0009] The workpiece with the plating film formed, the media, and the insulating balls are pushed out from the bottom of the plating forming section, and once again ride the rising current of plating solution generated inside the metal pipe, rise inside the metal pipe, and are ejected from the top end of the metal pipe and stirred. The workpiece is circulated through the plating device several to several thousand times until the planned plating film thickness is reached.

[0010] The media serves to electrically connect the metal pipe, which is the first electrode, and the plating formation area on the surface of the object to be plated in the plating formation section.

[0011] Japanese Patent Application Laid-Open No. 2021-138999

[0012] In the plating process, the quantity (volume) and dimensions of the media are adjusted appropriately depending on the desired state of the plating film.

[0013] When the number of media is small, the diameter of the media is small, or the plating area on the surface of the object to be plated is small, the electrical connection between the metal pipe as the first electrode and the plating area on the object to be plated may not be sufficient. If the electrical connection between the metal pipe as the first electrode and the plating area on the object to be plated is not sufficient, it may take a long time to reach the intended plating film thickness, or the thickness of the formed plating film may vary between objects to be plated.

[0014] Therefore, increasing the number of media has been considered, but increasing the number of media may result in the media shielding the electric field, which may result in longer film formation times or variations in plating thickness due to the electric field shielding by the media.

[0015] Therefore, the present invention aims to solve the above-mentioned conventional problems, and to provide a plating apparatus that improves the time required for plating and suppresses thickness variations in the formed plating film.

[0016] In order to solve the above-mentioned problems of the related art, a plating apparatus according to one embodiment of the present invention comprises a plating tank for storing plating solution, a cylindrical metal tube having a hollow portion as a first electrode, a cylindrical mesh tube having a hollow portion made of an insulating material, and a second electrode, wherein the metal tube, mesh tube, and second electrode are each contained in the plating tank, the metal tube is disposed within the hollow portion of the mesh tube, a plating formation portion is formed between the inside of the mesh tube and the outside of the metal tube, the second electrode is disposed on the outside of the mesh tube, an upward flow that raises the plating solution is generated within the hollow portion of the metal tube, the object to be plated rises within the hollow portion of the metal tube on the upward flow of the plating solution, is discharged outside the metal tube, is agitated, and then descends within the plating formation portion, and during the descent, a current is applied between the metal tube serving as the first electrode and the second electrode, thereby plating the object. An auxiliary electrode electrically connected to the metal tube serving as the first electrode is provided within the plating formation portion.

[0017] In a plating apparatus according to one embodiment of the present invention, the auxiliary electrode assists in establishing an electrical connection between the first electrode, which is a metal tube, and the plating formation area of ​​the object to be plated, thereby improving the time required to reach the desired plating thickness.

[0018] In addition, in a plating apparatus according to one embodiment of the present invention, the auxiliary electrode assists in the electrical connection between the first electrode, which is the metal tube, and the plating formation area of ​​the object to be plated, and a uniform current is supplied to the plating formation area, thereby suppressing variations in the thickness of the formed plating film.

[0019] [Correction based on Rule 91 03.10.2023] This is a cross-sectional view of the plating apparatus 100 according to the first embodiment. This cross-sectional view shows the portion A-A indicated by the dashed-dotted arrow in FIG. 1 . FIG. 3(A) is a front view of the metal tube 2 and auxiliary electrode 15 of the plating apparatus 100. FIG. 3(B) is a cross-sectional view of the metal tube 2 and auxiliary electrode 15 of the plating apparatus 100. FIG. 3(C) is a plan view of the metal tube 2 and auxiliary electrode 15 of the plating apparatus 100. FIG. 4(A) is a front view of the metal tube 2 of a plating apparatus 1100 according to a comparative example. FIG. 4(B) is a cross-sectional view of the metal tube 2 of the plating apparatus 1100. FIG. 4(C) is a plan view of the metal tube 2 of the plating apparatus 1100. FIG. 5(A) is a graph showing the thickness distribution (frequency) of the plating film in Example 1 in Experiment 1. FIG. 5(B) is a graph showing the distribution (frequency) of the thickness of the plating film of Comparative Example 1 in Experiment 1. FIG. 5(B) is a graph showing the variation in thickness of the plating film of Example 1 and Comparative Example 1 in Experiment 1. FIG. 5(B) is a front view of the main part of the plating apparatus 200 according to the second embodiment. FIG. 8(A) is a cross-sectional view of the main part of the plating apparatus 200A. FIG. 8(B) is a cross-sectional view of the main part of the plating apparatus 200B. FIG. 8(C) is a cross-sectional view of the main part of the plating apparatus 200C. FIG. 5(B) is a graph showing the variation in thickness of the plating film of Examples 21, 22, and 23 in Experiment 2.

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0021] It should be noted that each embodiment exemplifies an embodiment of the present invention, and the present invention is not limited to the content of the embodiment. Furthermore, it is possible to combine the contents described in different embodiments, and such combinations are also included in the present invention. Furthermore, the drawings are intended to facilitate understanding of the specification and may be drawn schematically, and the dimensional ratios of the depicted components or between the components may not match the dimensional ratios of those components described in the specification. Furthermore, components described in the specification may be omitted in the drawings, or the number of components may be omitted.

[0022] [First Embodiment] Figures 1, 2, and 3(A) to 3(C) show a plating apparatus 100 according to this embodiment. FIG. 1 is a cross-sectional view of the plating apparatus 100. Figure 2 is also a cross-sectional view of the plating apparatus 100, showing the portion A-A indicated by the dashed-dotted arrow in Figure 1. Figure 3(A) is a front view of a main portion of the plating apparatus 100, showing a metal tube 2 and an auxiliary electrode 15 (described later). Figure 3(B) is a cross-sectional view of a main portion of the metal tube 2 and the auxiliary electrode 15. Figure 3(C) is a plan view of a main portion of the metal tube 2 and the auxiliary electrode 15.

[0023] The plating apparatus 100 includes a plating tank 1. The plating tank 1 is open at the top. The plating tank 1 is used to store a mixture 16 of a plating solution, an object to be plated, and media, which will be described later. Insulating balls may be added to the mixture 16 as needed to increase the fluidity of the object to be plated.

[0024] The plating apparatus 100 includes a cylindrical metal tube 2 inside a plating tank 1. The metal tube 2 has a hollow portion 2a. The metal tube 2 is a first electrode, and in this embodiment, it is a cathode electrode. In this embodiment, the metal tube 2 is cylindrical. However, the metal tube 2 may also be polygonal cylindrical. The material of the metal tube 2 is arbitrary, and various metals can be used. The dimensions of the metal tube 2, such as the outer diameter, inner diameter, and length, are arbitrary and can be set as appropriate.

[0025] 3, in this embodiment, two conductive rod-shaped support parts 2b are formed integrally with the metal tube 2 on the upper part of the metal tube 2. However, the number of support parts 2b is arbitrary, and may be one or more than two.

[0026] The plating apparatus 100 includes a mesh tube 3 made of an insulating material inside a plating tank 1. The mesh tube 3 has a hollow portion 3a. In this embodiment, the mesh tube 3 is cylindrical. However, the mesh tube 3 may also be a polygonal cylindrical tube. The mesh tube 3 is formed in a mesh (mesh) shape that allows the plating solution to pass through but does not allow the object to be plated, the media, or the insulating balls to pass through. The mesh tube 3 may be made of any material, and various resins may be used, for example. The dimensions of the mesh tube 3, such as the outer diameter, inner diameter, and length, may be any dimension and may be set as appropriate.

[0027] The inner diameter of the mesh tube 3 is larger than the outer diameter of the metal tube 2. The metal tube 2 is disposed within the hollow portion 3a of the mesh tube 3. A plating formation portion 4 is formed between the inside of the mesh tube 3 and the outside of the metal tube 2. The plating formation portion 4 is a region (space) where plating is applied to the object to be plated. Note that in Figures 1 and 2, the plating formation portion 4 is depicted as a crosshatched portion. The plating formation portion 4 is the area between the outer diameter of the metal tube 2 and the inner diameter of the mesh tube 3. The dimensions of the plating formation portion 4, such as its length, are arbitrary and can be set as appropriate.

[0028] The object to be plated, the media, and the insulating balls are accumulated inside the plating forming section 4 and gradually descend downward. During this descent, the surface of the object to be plated is plated.

[0029] The plating apparatus 100 includes a second electrode 5 inside the plating tank 1. In this embodiment, the second electrode 5 is an anode electrode. In this embodiment, the second electrode 5 is made of a cylindrical metal. The second electrode 5 is disposed outside the mesh tube 3. The second electrode 5 may be made of any material, and various metals may be used.

[0030] 2, in the plating apparatus 100, the metal tube 2, the mesh tube 3, and the second electrode 5 are concentrically arranged so that their central axes coincide when viewed in a plan view. Therefore, in the plating apparatus 100, a current is applied uniformly between the metal tube 2 (the first electrode) and the second electrode 5 in any region of the plating formation section 4, thereby suppressing variations in the thickness of the plating film formed.

[0031] The plating apparatus 100 is provided with an injection unit 6 below the metal pipe 2. The injection unit 6 has an injection port 6a. The injection port 6a injects plating solution toward the hollow portion 2a of the metal pipe 2, generating an upward flow of plating solution inside the hollow portion 2a.

[0032] The plating apparatus 100 includes a circulation line 7 formed of a pipe. One end of the circulation line 7 is connected to a suction port 8 formed in the plating tank 1. The other end of the circulation line 7 is connected to an injection port 6a of the injection unit 6. A pump 9 and a filter 10 are provided midway along the circulation line 7. When the pump 9 is driven, the circulation line 7 sucks the plating solution through the suction port 8 and injects the plating solution from the injection port 6a.

[0033] The plating apparatus 100 includes a mixing section 11 below the metal tube 2 and mesh tube 3 and above the injection section 6. The mixing section 11 is an area where the plating solution injected from the injection port 6a of the injection section 6 is mixed with the workpiece, media, and insulating balls that have descended through the plating formation section 4. In this embodiment, the mixing section 11 is made of an insulating material, and a recess in the shape of an inverted truncated cone is formed on the upper surface. An inverted truncated cone is a truncated cone whose upper base is larger than its lower base. However, the shape of the recess is arbitrary, and it may be a mortar shape instead of an inverted truncated cone. The injection section 6 is formed on the bottom surface of the recess in the mixing section 11.

[0034] The plating apparatus 100 includes a guide section 12 above the metal tube 2 and the mesh tube 3. The guide section 12 is a region where the workpiece, media, and insulating balls, which rise on the upward flow of plating solution formed inside the hollow section 2a of the metal tube 2 by the injection from the injection port 6a of the injection section 6 and are discharged (ejected) from the upper opening of the hollow section 2a of the metal tube 2, are agitated and then guided to the plating formation section 4. The guide section 12 is made of an insulating material and has an inverted truncated cone shape. The upper end of the metal tube 2 protrudes from the bottom surface of the guide section 12. The upper end of the hollow section 2a of the metal tube 2 opens at the bottom surface of the guide section 12. The bottom surface of the guide section 12 is connected to the mesh tube 3.

[0035] The plating apparatus 100 is equipped with an insulating reflector 13 above the opening of the plating tank 1. The reflector 13 is sometimes called a deflector. The reflector 13 serves to prevent plating solution from scattering. The support portion 2b of the metal tube 2 is attached to the underside of the reflector 13. A cylindrical suppression plate 13a is formed on the underside of the reflector 13. The suppression plate 13a is disposed within the guide portion 12. Although the plating solution may overflow from the upper edge of the guide portion 12, the suppression plate 13a ensures that only the plating solution overflows from the guide portion 12, preventing the plating workpiece, media, and insulating balls from overflowing.

[0036] The plating apparatus 100 includes a power supply 14. One line of the power supply 14 is connected to the support portion 2 b of the metal tube 2, which serves as the first electrode, and the other line is connected to the second electrode 5. The power supply 14 applies a current between the metal tube 2, which serves as the first electrode, and the second electrode 5.

[0037] The plating apparatus 100 is provided with an auxiliary electrode 15, which is an important component of the present invention, in the plating formation section 4. The auxiliary electrode 15 is electrically connected to the metal tube 2, which serves as the first electrode. The auxiliary electrode 15 serves to support the metal tube 2, which serves as the first electrode, when the workpiece is plated in the plating formation section 4. More specifically, when the workpiece is plated in the plating formation section 4, the metal tube 2, which serves as the first electrode, is electrically connected to the plating formation area of ​​the workpiece via a conductive path formed by multiple media. However, the plating apparatus 100 includes the auxiliary electrode 15, which is electrically connected to the metal tube 2, which serves as the first electrode. This increases the number of power supply points, thereby more reliably establishing an electrical connection between the metal tube 2, which serves as the first electrode, and the plating formation area of ​​the workpiece.

[0038] In this embodiment, the auxiliary electrode 15 is plate-shaped. However, the shape of the auxiliary electrode 15 is not limited to a plate shape and may be any shape. The auxiliary electrode 15 may be, for example, rod-shaped or block-shaped.

[0039] In this embodiment, the auxiliary electrode 15 has a triangular plate shape. However, the auxiliary electrode 15 is not limited to a triangular plate shape and may have, for example, a rectangular plate shape.

[0040] In this embodiment, the auxiliary electrode 15 is attached to the outside of the metal tube 2, which is the first electrode, and is electrically connected to the metal tube 2. The triangular plate-shaped auxiliary electrode 15 is attached to the outside of the metal tube 2 with one side facing up and the vertex opposite that side facing down. Therefore, the auxiliary electrode 15 is less likely to interfere with the passage of the workpiece, media, and insulating balls through the plating formation section 4. In other words, the cross-sectional area of ​​the space excluding the portion where the auxiliary electrode 15 is present increases from the top to the bottom of the plating formation section 4, allowing the workpiece, media, and insulating balls to pass through smoothly. Note that the auxiliary electrode 15 may not be attached to the metal tube 2, but may be suspended independently from, for example, the reflector 13.

[0041] In this embodiment, when viewed in a planar direction, four auxiliary electrodes 15 are arranged radially around the metal tube 2. Therefore, the auxiliary electrodes 15 can supply current evenly within the plating formation portion 4. The number of auxiliary electrodes 15 is not limited to four, and may be less than four or more than four.

[0042] In the plating apparatus 100 of the first embodiment having the above-described structure, the auxiliary electrode 15 assists in the electrical connection between the metal tube 2, which is the first electrode, and the plating formation area of ​​the object to be plated, thereby shortening (improving) the time required to reach the desired plating thickness.

[0043] Furthermore, in the plating apparatus 100 according to the first embodiment, the auxiliary electrode 15 assists in the electrical connection between the first electrode, the metal tube 2, and the plating formation area of ​​the object to be plated, and a uniform current is supplied to the plating formation section 4, thereby suppressing variations in the thickness of the formed plating film.

[0044] (Example of Use of Plating Apparatus 100) An example of a plating process using the plating apparatus 100 will be described below.

[0045] First, a desired plating solution is charged into the plating tank 1 .

[0046] Next, the object to be plated, media, and insulating balls, each of the desired shape, size, and number, are introduced into the induction section 12 in the plating tank 1. The order of introducing the plating solution and the object to be plated, media, and insulating balls may be reversed. The introduced object to be plated, media, and insulating balls are deposited in the plating formation section 4.

[0047] Next, the pump 9 is driven to spray the plating solution from the nozzle 6a of the spray unit 6. As a result, an upward flow of plating solution is generated inside the metal tube 2. Then, some of the objects to be plated, media, and insulating balls that have accumulated inside the plating formation unit 4 are taken out from the lower end of the plating formation unit 4 to the mixing unit 11, where they mix with the sprayed plating solution and rise inside the metal tube 2 on the upward flow.

[0048] The object to be plated, media, and insulating balls that have risen inside the metal tube 2 are ejected from the upper end of the metal tube 2 and stirred.

[0049] The stirred objects to be plated, media, and insulating balls are deposited on top of other objects to be plated, media, and insulating balls that have already been deposited in the plating formation section 4.

[0050] The newly deposited objects to be plated, media, and insulating balls gradually descend as some of the objects to be plated, media, and insulating balls that had accumulated in the plating formation section 4 are removed from the lower end of the plating formation section 4 to the mixing section 11. In this way, the objects to be plated, media, and insulating balls circulate inside the plating apparatus 100.

[0051] Next, the power supply 14 is driven to apply a current between the metal tube 2, which is the first electrode, and the second electrode 5. As a result, plating of the object to be plated begins in the plating forming section 4.

[0052] After a predetermined time has passed and a plating film of the desired thickness has been formed on the object to be plated, the power supply 14 is turned off to stop plating on the object to be plated. Then, the pump 9 is stopped to stop the object to be plated, the media, and the insulating balls from circulating inside the plating apparatus 100.

[0053] The plating process is completed by removing the objects to be plated, media, and insulating balls from the plating tank 1 and sorting the objects to be plated.

[0054] (Experiment 1) In order to confirm the effectiveness of the present invention, the following experiment 1 was carried out.

[0055] For Example 1, the above-described plating apparatus 100 was prepared.

[0056] A plating apparatus 1100 was also prepared for Comparative Example 1. As shown in Figures 4(A) to 4(C), the plating apparatus 1100 did not have the auxiliary electrode 15 attached to the metal tube 2 of the plating apparatus 100 (it was structured without the auxiliary electrode 15). The other structures of the plating apparatus 1100 were the same as those of the plating apparatus 100.

[0057] In both the plating apparatus 100 and the plating apparatus 1100, the length of the plating forming portion 4 was set to 220 mm.

[0058] Mixtures of the object to be plated, media, and insulating balls were prepared for Example 1 and Comparative Example 1. The mixture for Example 1 and the mixture for Comparative Example 1 had the same composition and mixing amounts.

[0059] The total amount of the workpiece, media, and insulating balls was 1720 cc, with the mixture ratio being 1376 cc (80% by volume) of workpiece, 86 cc (5% by volume) of media, and 258 cc (15% by volume) of insulating balls.

[0060] The same plating solution was prepared for Example 1 and Comparative Example 1.

[0061] In Example 1, plating was carried out for 210 minutes on an object to be plated using the plating apparatus 100, the mixture, and the plating solution. The magnitude of the applied current was 0.17 A / dm ２ The plating solution was sprayed at a flow rate of 85 L / min. However, the plating apparatus 1100 was stopped 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, and 210 minutes after the start of plating, and 30 objects to be plated were removed from the apparatus 1100 at each time point, and the thickness of the plated film formed was measured.

[0062] Similarly, in Comparative Example 1, plating was carried out for 210 minutes on an object to be plated using the plating apparatus 1100, the mixture, and the plating solution. The magnitude of the applied current was 0.17 A / dm ２ The plating solution was sprayed at a flow rate of 85 L / min. Similarly, the plating apparatus 1100 was stopped 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, and 210 minutes after the start of plating, and 30 objects to be plated were removed from the plating apparatus 1100 at each time point, and the thickness of the formed plating film was measured.

[0063] Details of Example 1 and Comparative Example 1 are shown in Table 1.

[0064] Fig. 5(A) shows the distribution (frequency) of thicknesses of plating films formed on 30 substrates 60 minutes after the start of plating in Example 1. Fig. 5(B) shows the distribution (frequency) of thicknesses of plating films formed on 30 substrates 60 minutes after the start of plating in Comparative Example 1.

[0065] As can be seen from a comparison between FIG. 5(A) and FIG. 5(B), the plating film thickness in Example 1 tends to be generally greater than that in Comparative Example 1.

[0066] In this way, it was confirmed that by attaching the auxiliary electrode 15 to the metal tube 2 in the plating apparatus 100, the auxiliary electrode 15 assists in establishing an electrical connection between the metal tube 2 and the plating formation area of ​​the object to be plated, thereby improving the deposition rate of the plating film.

[0067] FIG. 6 shows the variation (CV (%)) in thickness of the plating film for Example 1 and Comparative Example 1 at 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, and 210 minutes after the start of plating.

[0068] As can be seen from Figure 6, Example 1 has smaller variations overall. Example 1 has smaller variations than Comparative Example 1 at 60 minutes, 90 minutes, 120 minutes, and 150 minutes after the start of plating. Comparative Example 1 has larger variations, particularly at 60 minutes after the start of plating. After 180 minutes and 210 minutes, Example 1 and Comparative Example 1 have similar variations.

[0069] In this way, it was confirmed that by attaching the auxiliary electrode 15 to the metal tube 2 in the plating apparatus 100, the auxiliary electrode 15 assists in establishing an electrical connection between the metal tube 2 and the plating formation area of ​​the object to be plated, a uniform current is supplied to the plating formation area, and thickness variations in the formed plating film are suppressed.

[0070] As described above, the present invention has unique and excellent effects.

[0071] Second Embodiment A plating apparatus 200 according to a second embodiment was fabricated. The plating apparatus 200 is obtained by adding some modifications to the configuration of the plating apparatus 100 according to the first embodiment.

[0072] Specifically, in the plating apparatus 100, four triangular auxiliary electrodes 15 were attached to the outside of the metal tube 2, which serves as the first electrode. However, in the plating apparatus 200, as shown in Figure 7, the four auxiliary electrodes 25 are detached from the metal tube 2 and are suspended within the plating formation section 4 by their own conductive rod-shaped supports 25b. In addition, the shape of the auxiliary electrodes 25 has been changed from a triangular plate to a rectangular plate. The tips of the supports 25b of the auxiliary electrodes 25 are attached to the underside of the reflector 13, for example.

[0073] The auxiliary electrode 25 is electrically connected to the metal tube 2, which is the first electrode, via the support portion 25b. The auxiliary electrode 25 supports the metal tube 2, which is the first electrode, and serves to increase the number of power supply points.

[0074] The four auxiliary electrodes 15 were arranged in three ways, as shown in Figures 8(A), (B), and (C). Each of Figures 8(A), (B), and (C) is a cross-sectional view of a main portion of a plating apparatus 200. The plating apparatus shown in Figure 8(A) is referred to as plating apparatus 200A, the plating apparatus shown in Figure 8(B) as plating apparatus 200B, and the plating apparatus shown in Figure 8(C) as plating apparatus 200C. The plating apparatus 200 shown in Figure 7 corresponds to plating apparatus 200B.

[0075] In the plating apparatus 200A, four auxiliary electrodes 25 are arranged on the side of the metal tube 2. The four auxiliary electrodes 25 are arranged radially around the metal tube 2. The auxiliary electrodes 25 may be in contact with the metal tube 2 or may be separated from the metal tube 2 with a small gap therebetween.

[0076] In the plating apparatus 200B, four auxiliary electrodes 25 are disposed between the metal tube 2 and the mesh tube 3. The four auxiliary electrodes 25 are disposed radially around the metal tube 2.

[0077] In the plating apparatus 200C, four auxiliary electrodes 25 are arranged on the mesh tube 3 side. The four auxiliary electrodes 25 are arranged so as to be parallel to the mesh surface of the mesh tube 3.

[0078] (Experiment 2) In order to compare the performance of the plating apparatus 200A, the plating apparatus 200B, and the plating apparatus 200C with each other, the following experiment 2 was carried out.

[0079] In Example 21, plating apparatus 200A was used. In Example 22, plating apparatus 200B was used. In Example 23, plating apparatus 200C was used.

[0080] The same mixtures of the substrate, media, and insulating balls as those used in Experiment 1 (Example 1 and Comparative Example 1) were prepared for Examples 21, 22, and 23. The mixtures for Examples 21, 22, and 23 had the same mixing ratios and amounts.

[0081] For Examples 21, 22, and 23, the same plating solution as that used in Experiment 1 was prepared.

[0082] In each of Examples 21, 22, and 23, the mixture and the plating solution were used to plate the object for 210 minutes. The magnitude of the applied current was 0.17 A / dm ２ The plating solution was sprayed at a flow rate of 85 L / min. As in Experiment 1, the plating apparatus 1100 was stopped 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, and 210 minutes after the start of plating, and 30 objects to be plated were removed from the plating apparatus 1100 at each time point, and the thickness of the formed plating film was measured.

[0083] Details of Examples 21, 22, and 23 are shown in Table 2.

[0084]

[0085] FIG. 9 shows the variation (CV (%)) in thickness of the plating film for each of Examples 21, 22, and 23, 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, and 210 minutes after the start of plating.

[0086] As can be seen from Figure 9, Example 21, in which four auxiliary electrodes 25 were arranged on the metal tube 2 side, had smaller variations overall. Example 21 had smaller variations than Example 22, in which four auxiliary electrodes 25 were arranged between the metal tube 2 and the mesh tube 3, and Example 23, in which four auxiliary electrodes 25 were arranged on the mesh tube 3 side, at 60 minutes, 90 minutes, 120 minutes, and 150 minutes after the start of plating. Furthermore, Example 22, in which four auxiliary electrodes 25 were arranged between the metal tube 2 and the mesh tube 3, had smaller variations overall than Example 23, in which four auxiliary electrodes 25 were arranged on the mesh tube 3 side. Example 22 had smaller variations than Example 23 at 60 minutes, 90 minutes, 120 minutes, and 180 minutes after the start of plating.

[0087] From the above, it was found that when the auxiliary electrode 25 is placed within the plating formation section 4, it is better to place it as close to the first electrode, the metal tube 2, as possible rather than on the mesh tube 3 side, in order to suppress variations in the thickness of the plating film.

[0088] The plating apparatus 100 and the plating apparatus 200 (plating apparatuses 200A, 200B, and 200C) according to the embodiments have been described above. However, the present invention is not limited to the above-described content, and various modifications can be made in accordance with the spirit of the invention.

[0089] For example, in the above embodiment, the number of auxiliary electrodes 15 and 25 is four, but the number of auxiliary electrodes 15 and 25 is arbitrary and may be less than four or more than four.

[0090] In the above embodiment, the auxiliary electrodes 15 and 25 are triangular or rectangular plates, but the auxiliary electrodes 15 and 25 may have any shape, and may have other shapes.

[0091] A plating apparatus according to one embodiment of the present invention is as described in the section "Means for Solving the Problems."

[0092] In this plating apparatus, it is also preferable that the first electrode is a cathode electrode and the second electrode is an anode electrode.

[0093] It is also preferable that the auxiliary electrode is attached to the outside of the metal tube and electrically connected to the metal tube, in which case the auxiliary electrode can be easily provided.

[0094] It is also preferable that the auxiliary electrode is suspended within the plating formation portion, in which case the auxiliary electrode can be disposed at any position within the plating formation portion.

[0095] It is also preferable that a plurality of auxiliary electrodes are provided, in which case current can be supplied more uniformly to the plating formation portion.

[0096] It is also preferable that the number of auxiliary electrodes is four, in which case the current can be supplied more uniformly to the plating formation portion.

[0097] It is also preferable that the auxiliary electrodes are arranged radially from the metal tube when viewed in a plan view, in which case current can be supplied more uniformly to the plating formation portion.

[0098] It is also preferable that the auxiliary electrode is a metal plate, in which case the auxiliary electrode can be prevented from obstructing the passage of plating formation parts such as the object to be plated, media, and insulating balls.

[0099] In this case, it is also preferable that the metal plate is a triangular plate and is placed in the plating formation section with one side of the triangle facing up and the vertex opposite that side facing down. In this case, the auxiliary electrode can be more effectively prevented from obstructing the passage of the object to be plated, media, insulating balls, etc. through the plating formation section. However, the shape of the metal plate is arbitrary, and it may be, for example, a rectangular plate.

[0100] DESCRIPTION OF SYMBOLS 1 Plating tank 2 Metal tube (first electrode; cathode) 2a Hollow portion 2b Support portion 3 Mesh tube 3a Hollow portion 4 Plating formation portion 5 Second electrode (anode) 6 Injection portion 6a Injection port 7 Circulation line 8 Liquid suction port 9 Pump 10 Filter 11 Mixing portion 12 Guidance portion 13 Reflector (deflector) 13a Suppression plate 14 Power supply 15, 25 Auxiliary electrode 25a Support portion

Claims

1. A plating tank for storing a plating solution; A cylindrical metal tube having a hollow portion as a first electrode; A cylindrical mesh tube having a hollow portion, the mesh tube being made of an insulating material; A second electrode, The metal tube, the mesh tube, and the second electrode are each contained in the plating tank, The metal tube is disposed in the hollow portion of the mesh tube, and a plating formation portion is formed between an inside of the mesh tube and an outside of the metal tube; The second electrode is disposed on the outside of the mesh tube, An upward flow that causes the plating solution to rise is generated in the hollow portion of the metal pipe, The object to be plated is The plating solution is carried upward through the hollow portion of the metal pipe by the upward flow of the plating solution, After being discharged outside the metal tube and stirred, Descending through the plating formation section, During the descent, a current is applied between the metal tube, which is the first electrode, and the second electrode, thereby plating the metal tube. An auxiliary electrode is provided in the plating formation portion and is electrically connected to the metal tube which is the first electrode. Plating equipment.

2. The first electrode is a cathode electrode, The second electrode is an anode electrode.

2. The plating apparatus according to claim 1.

3. The auxiliary electrode is attached to the outside of the metal tube and is electrically connected to the metal tube.

3. The plating apparatus according to claim 1 or 2.

4. The auxiliary electrode is suspended within the plating formation portion.

3. The plating apparatus according to claim 1 or 2.

5. The auxiliary electrode is composed of a plurality of electrodes.

3. The plating apparatus according to claim 1 or 2.

6. The auxiliary electrodes are four in number.

6. The plating apparatus according to claim 5.

7. When viewed in the planar direction, The auxiliary electrodes are arranged radially around the metal tube.

3. The plating apparatus according to claim 1 or 2.

8. The auxiliary electrode is a metal plate.

3. The plating apparatus according to claim 1 or 2.

9. The metal plate is a triangular plate, The plating forming portion is disposed with one side of the triangle facing upward and a vertex opposite to the one side facing downward.

9. The plating apparatus according to claim 8.

10. The metal plate is a rectangular plate.

9. The plating apparatus according to claim 8.