Electroplating apparatus and ultrasonic processing apparatus

Abstract

To provide an ultrasonic processing device that can extend the lifespan of ultrasonic transducers even in corrosive solutions. [Solution] An ultrasonic apparatus according to another aspect of the present disclosure comprises an ultrasonic transducer, a tank, and an ultrasonic reflector, wherein the ultrasonic frequency is 15 kHz or more and 180 kHz or less, and the acoustic impedance of the ultrasonic reflector is 1 × 10⁻⁶ 7 kg·m -2 sec -1 The above conditions apply, and 100mm ≤ L1, 10mm ≤ L2, 0

Description

Technical Field

[0001] The present disclosure relates to an electroplating apparatus and an ultrasonic processing apparatus. The present application claims priority based on Japanese Patent Application No. 2025-033826 filed in Japan on March 4, 2025 and Japanese Patent Application No. 2025-033618 filed in Japan on March 4, 2025, the contents of which are incorporated herein by reference.

Background Art

[0002] (A. Background Art of Electroplating Apparatus) According to electroplating, various metal coatings such as tin, zinc, chromium and nickel can be formed on the surface of a base material. This can improve the aesthetic appearance, corrosion resistance and the like of the base material. Therefore, electroplating is performed to achieve higher functionality of various materials such as steel.

[0003] However, in the process of electroplating, a diffusion layer is formed on the surface of the base material which is the object to be plated. The diffusion layer is a thin layer of solution that is in contact with the base material during electroplating and forms a concentration gradient with the bulk solution due to mass transfer via diffusion. The diffusion layer imposes restrictions on the plating rate and coating properties.

[0004] As a means for eliminating the restriction caused by the diffusion layer, Patent Document 1 discloses a method for producing a surface-treated steel sheet, comprising the step of using a tin electroplating solution, performing electroplating on a steel sheet moving through the tin electroplating solution, and forming a tin plating layer on at least one surface of the steel sheet, wherein the moving speed of the steel sheet is set to 1 m / min or more, and during electroplating, converted to ultrasonic oscillation intensity at a position 20 mm away from the surface of the steel sheet, 0.001 WATT / cm 2 to 100 WATT / cm 2 A method for producing a surface-treated steel sheet is disclosed, which is characterized in that ultrasonic vibration having an intensity within the range of and a frequency within the range of 10 Hz to 10 MHz is applied to the steel sheet.

[0005] Further, Patent Document 2 discloses a substrate processing apparatus that processes a substrate by immersing the substrate in a processing liquid, comprising: a processing tank that stores the processing liquid; a holding mechanism that holds the substrate in a state of being immersed in the processing liquid stored in the processing tank; an ultrasonic vibrator that generates ultrasonic vibration; a propagation tank that is disposed below the processing tank and stores propagation water for propagating the ultrasonic vibration generated from the ultrasonic vibrator to the processing tank; a processing liquid supply unit that supplies the processing liquid to the processing tank; a propagation water supply unit that supplies the propagation water to the propagation tank; an inert gas dissolving unit that dissolves an inert gas in the processing liquid in the processing liquid supply unit; and a deaeration unit that deaerates the propagation water in the propagation water supply unit.

[0006] (B. Background Art of Ultrasonic Processing Apparatus)

[0007] Ultrasonic waves cause cavitation in a solution. Cavitation refers to a phenomenon in which the pressure of a flowing liquid locally decreases to cause a phase change, generating vapor bubbles, and a phenomenon in which the pressure of a flow becomes low or the speed of the flow becomes high, forming a cavity in that portion. In the present disclosure, bubbles and cavities generated by this phenomenon are also referred to as cavitation.

[0008] Cavitation can stir a solution. Therefore, it is widely used in plating and cleaning that require stirring of a solution. Stirring by cavitation induced by ultrasonic waves is extremely powerful. Therefore, in plating and cleaning, ultrasonic waves exert a high effect.

[0009] For example, Patent Document 1 discloses that during electroplating, converted to ultrasonic oscillation intensity at a position 20 mm away from the surface of a steel sheet, 0.001 WATT / cm 2 to 100 WATT / cm 2 a method for producing a surface-treated steel sheet, characterized by applying ultrasonic vibration having an intensity within the range of and a frequency within the range of 10 Hz to 10 MHz to the steel sheet is disclosed.

Prior Art Documents

Patent Documents

[0010] [Patent Document 1] Patent No. 3206101 [Patent Document 2] Japanese Patent Publication No. 2007-173677 [Overview of the project] [Problems that the invention aims to solve]

[0011] (A. Challenges with electroplating equipment) According to the technology described in Patent Document 1, it is possible to significantly widen the gloss current density range and increase the amount of tin plating per pass without increasing the number of plating tanks. However, ultrasound is easily attenuated in liquids. For example, in large plating tanks used in steelmaking processes, it is difficult to propagate ultrasound with sufficient intensity to the surface of the substrate.

[0012] The technology described in Patent Document 2 suppresses the attenuation of ultrasonic energy by performing degassing to suppress the generation of bubbles in the propagating water. However, the technology disclosed in Patent Document 2 relates to a substrate processing apparatus that performs cleaning and other treatments on substrates such as semiconductor substrates, glass substrates for liquid crystal display devices, and glass substrates for photomasks using a treatment liquid such as pure water. Patent Document 2 does not consider at all the adverse effects that may occur when a technology relating to a non-corrosive liquid such as a cleaning liquid is applied to a corrosive liquid such as a plating bath.

[0013] The object of this disclosure is to provide an electroplating apparatus that can prevent the formation of a diffusion layer and has a long lifespan, and a method for manufacturing an electroplating member that can prevent the formation of a diffusion layer and extends the lifespan of the electroplating apparatus.

[0014] (B. Challenges of ultrasonic treatment equipment) The inventors have found that when ultrasound is used in plating and degreasing in acids or alkalis, and in pickling in acids, the lifespan of ultrasonic transducers is significantly reduced. This is presumed to be because cavitation is generated near the ultrasonic transducer, accelerating corrosion in the acid or alkali. Therefore, there is a need to develop a technology that can extend the lifespan of ultrasonic transducers even in corrosive solutions such as acids or alkalis.

[0015] The purpose of this disclosure is to provide an ultrasonic processing apparatus and an ultrasonic processing method that can extend the lifespan of an ultrasonic transducer even in corrosive solutions. [Means for solving the problem]

[0016] The gist of this disclosure is as follows:

[0017] (1) An electroplating apparatus according to one aspect of the present disclosure comprises an electroplating tank, a first ultrasonic transducer configured to emit first ultrasonic waves inside the electroplating tank, a substrate support means configured to support a substrate in a substrate placement area, and a counter electrode, wherein the frequency of the first ultrasonic waves emitted by the first ultrasonic transducer is 15 kHz or more and 80 kHz or less, the intensity of the first ultrasonic waves is 0.20 to 80 kPa / kHz at a location 5 cm away from the surface of the center in the width direction of the substrate placement area, and at a location between the center in the width direction of the substrate placement area and the counter electrode, where the distance from the substrate placement area is even closer, and the electroplating apparatus further comprises an ultrasonic attenuation means arranged in a region within 10 cm of the portion of the first ultrasonic transducer exposed to the internal space of the electroplating tank. (2) Preferably, the electroplating apparatus described in (1) above further comprises a plating bath degassing means. (3) Preferably, the electroplating apparatus described in (1) above further comprises a bubble removal means configured to remove bubbles generated on the surface of the substrate to be electroplated by the electroplating apparatus. (4) Preferably, in the electroplating apparatus according to (3) above, the bubble removing means is a liquid flow generating means. (5) Preferably, in the electroplating apparatus according to (3) above, the bubble removing means is a second ultrasonic transducer that emits a second ultrasonic wave having a frequency of more than 80 kHz and not more than 180 kHz into the interior of the electroplating tank. (6) Preferably, in the electroplating apparatus according to any one of (1) to (5) above, the ultrasonic attenuating means has an acoustic impedance of 1×10 7 kg·m -2 ·sec -1 which is an ultrasonic attenuating material of less than . (7) Preferably, in the electroplating apparatus according to (6) above, the thickness of the ultrasonic attenuating material is 5 mm or more, and the area of the ultrasonic attenuating material is 2 times or more the surface area of the portion of the first ultrasonic transducer exposed to the internal space of the electroplating tank. (8) Preferably, in the electroplating apparatus according to any one of (1) to (7) above, the number of the first ultrasonic transducers is 2 or more.

[0018] (9) An ultrasonic treatment apparatus according to another aspect of the present disclosure includes an ultrasonic transducer configured to be capable of irradiating a liquid with ultrasonic waves from a vibration surface, a tank configured to be capable of holding the liquid, and an ultrasonic reflector disposed in the liquid, wherein the liquid is acidic or alkaline, the frequency of the ultrasonic waves is 15 kHz or more and 180 kHz or less, and the acoustic impedance of the ultrasonic reflector is 1×10 7 kg·m -2 ·sec -1 or more, and satisfies the following formulas 1 to 4, 100 mm≦L1......(Formula 1) 10 mm≦L2...............(Formula 2) 0<S1≦0.5×S3...........(Formula 3) 0.1×S3≦S2max........(Formula 4) L1 is the distance measured along the direction perpendicular to the vibration surface in the space within the vibration surface when viewed in plan along the direction perpendicular to the vibration surface in the liquid, between the point on the ultrasonic reflector furthest from the vibration surface and the point on the ultrasonic reflector closest to the vibration surface; L2 is the distance measured along the direction perpendicular to the vibration surface in the space within the vibration surface when viewed in plan along the direction perpendicular to the vibration surface in the liquid, between the point on the ultrasonic reflector closest to the vibration surface and the vibration surface; S1 is the projected area of ​​the ultrasonic reflector in the liquid with respect to the vibration surface; S2max is the maximum value of the projected area of ​​the ultrasonic reflector in the liquid with respect to a plane perpendicular to the vibration surface; and S3 is the area of ​​the vibration surface. (10) Preferably, in the ultrasonic apparatus described in (9) above, the output of the ultrasonic transducer is 800 W / m 3 That's all. (11) Preferably, the ultrasonic apparatus described in (9) or (10) above comprises a plurality of ultrasonic transducers. (12) Preferably, in the ultrasonic apparatus described in (11) above, a plurality of ultrasonic transducers that emit ultrasonic waves are arranged inside the liquid, and each of the plurality of ultrasonic transducers is provided on each of two opposing wall surfaces with the ultrasonic reflector in between, and the distance between the two closest ultrasonic transducers on one of the two wall surfaces and the other wall surface is 500 mm or more.

[0019] <Additional notes> (A1) A method for manufacturing an electroplated member according to another aspect of the present disclosure comprises a step of electroplating a substrate by applying current to a substrate immersed in a plating bath and a counter electrode, wherein during the electroplating, a first ultrasonic wave having a frequency of 15 kHz or more and 80 kHz or less is applied to the substrate using a first ultrasonic transducer, the intensity of the first ultrasonic wave at a point 5 cm away from the surface of the center in the width direction of the substrate, and at a point between the center in the width direction of the substrate and the counter electrode, whichever is closer to the substrate, is set to 0.20 to 80 kPa / kHz, and ultrasonic attenuation means is used to attenuate the ultrasonic waves that reach the portion of the first ultrasonic transducer that is in direct contact with the plating bath. (A2) Preferably, in the method for manufacturing an electroplated member described in (A1) above, the plating bath is degassed to remove dissolved gases in the plating bath. (A3) Preferably, in the method for manufacturing the electroplated member described in (A1) or (A2) above, bubbles adhering to the surface of the substrate are removed during the electroplating process. (A4) Preferably, in the method for manufacturing an electroplated member described in (A3) above, during electroplating, a flow is generated in the plating bath around the substrate, thereby removing bubbles that have formed on the surface of the substrate from the substrate. (A5) Preferably, in the method for manufacturing the electroplated member described in (A3) above, during the electroplating process, a second ultrasonic wave having a frequency of more than 80 kHz and less than or equal to 180 kHz is applied to the substrate to remove bubbles that have formed on the surface of the substrate. (A6) Preferably, in the method for manufacturing an electroplated member described in any one of (A1) to (A5) above, the ultrasonic attenuation means has an acoustic impedance of 1 × 10 7 kg·m -2 sec -1 The ultrasonic attenuation material is less than 10 cm, and the ultrasonic attenuation means is positioned within 10 cm of the portion of the first ultrasonic transducer that is in direct contact with the plating bath. (A7) Preferably, in the method for producing an electroplated member according to (A6) above, the thickness of the ultrasonic attenuation material is 5 mm or more, and the area of the ultrasonic attenuation material is at least twice the surface area of the portion of the first ultrasonic transducer that is in direct contact with the plating bath. (A8) Preferably, in the method for producing an electroplated member according to any one of (A1) to (A7) above, the number of the first ultrasonic transducers is set to 2 or more, and the first ultrasonic waves are applied to the base material from two or more directions during the electroplating. (A9) Preferably, in the method for producing an electroplated member according to any one of (A1) to (A8) above, the dissolved oxygen content in the plating bath is measured, and the dissolved oxygen content is adjusted to 6 mg·L -1 or less by removing gas contained in the plating bath.

[0020] (B1) The ultrasonic treatment method according to one aspect of the present disclosure includes a step of irradiating a liquid with ultrasonic waves from a vibration surface, wherein the liquid is made acidic or alkaline, the frequency of the ultrasonic waves is 15 kHz or more and 180 kHz or less, and 1×10 7 kg·m -2 ·sec -1 An ultrasonic reflector having an acoustic impedance of not less than the above is disposed in the liquid so as to satisfy the following formulas 1 to 4, 100 mm ≦ L1 ......(Formula 1) 10 mm ≦ L2 ...............(Formula 2) 0 < S1 ≦ 0.5 × S3 ...........(Formula 3) 0.1 × S3 ≦ S2max ......(Formula 4) L1 is the distance measured along the direction perpendicular to the vibration surface in the space within the vibration surface when viewed in plan along the direction perpendicular to the vibration surface in the liquid, between the point on the ultrasonic reflector furthest from the vibration surface and the point on the ultrasonic reflector closest to the vibration surface; L2 is the distance measured along the direction perpendicular to the vibration surface in the space within the vibration surface when viewed in plan along the direction perpendicular to the vibration surface in the liquid, between the point on the ultrasonic reflector closest to the vibration surface and the vibration surface; S1 is the projected area of ​​the ultrasonic reflector in the liquid with respect to the vibration surface; S2max is the maximum value of the projected area of ​​the ultrasonic reflector in the liquid with respect to a plane perpendicular to the vibration surface; and S3 is the area of ​​the vibration surface. (B2) Preferably, in the ultrasonic treatment method described in (B1) above, a material to be treated, separate from the ultrasonic reflector, is placed in the liquid as the object to be irradiated with ultrasonic waves. (B3) Preferably, in the ultrasonic treatment method described in (B1) or (B2) above, the ultrasonic reflector is the material to be treated that is irradiated with the ultrasonic waves. (B4) Preferably, in the ultrasonic treatment method described in any one of (B1) to (B3) above, the dissolved oxygen content of the liquid is 6 mg·L. -1 Let's assume that. (B5) Preferably, in the ultrasonic treatment method described in (B2) or (B3) above, the liquid is an electroplating bath, and the step of irradiating with ultrasonic waves includes a step of electroplating the material to be treated. (B6) Preferably, in the ultrasonic treatment method described in (B2) or (B3) above, the liquid is an acid pickling bath, and the step of irradiating with ultrasound includes a step of acid pickling the material to be treated. (B7) Preferably, in the ultrasonic treatment method described in (B6) above, the pickling is electrolytic pickling. (B8) Preferably, in the ultrasonic treatment method described in (B2) or (B3) above, the liquid is a degreasing bath, and the step of irradiating with ultrasound includes a step of degreasing the material to be treated. (B9) Preferably, in the ultrasonic treatment method described in (B8) above, the degreasing is electrolytic degreasing. (B10) Preferably, in the ultrasonic treatment method described in any one of the above items (B1) to (B9), the output of the ultrasonic transducer that emits the ultrasonic waves is 800 W / m 3 That's all. (B11) Preferably, in the ultrasonic treatment method described in any one of the above items (B1) to (B10), a plurality of ultrasonic transducers that emit ultrasonic waves are placed inside the liquid. (B12) Preferably, in the ultrasonic treatment method described in (B11) above, each of the plurality of ultrasonic transducers is provided on each of the two opposing wall surfaces with the ultrasonic reflector in between, and the distance between the two closest ultrasonic transducers on one wall surface and the other wall surface is 500 mm or more. [Effects of the Invention]

[0021] (A. Effects of electroplating equipment) According to this disclosure, it is possible to provide an electroplating apparatus that can prevent the formation of a diffusion layer and has a long lifespan, and a method for manufacturing an electroplated member using the same.

[0022] (B. Effects of ultrasonic treatment device) According to this disclosure, it is possible to provide an ultrasonic processing apparatus and an ultrasonic processing method that can extend the lifespan of an ultrasonic transducer even in corrosive solutions. [Brief explanation of the drawing]

[0023] [Figure 1] This is a schematic diagram of an electroplating apparatus viewed from the width direction of the substrate. [Figure 2] This is a schematic diagram of an electroplating apparatus viewed from a direction perpendicular to the surface of the substrate. [Figure 3] This is a schematic diagram of an electroplating apparatus having a second ultrasonic transducer. [Figure 4] This is a plan view in the width direction of the substrate, showing the ultrasonic intensity measurement position when the distance between the substrate and the counter electrode is 10 cm or more. [Figure 5]This is a plan view in the width direction of the substrate, showing the ultrasonic intensity measurement position when the distance between the substrate and the counter electrode is less than 10 cm. [Figure 6] This is a plan view in the width direction of the substrate, showing the ultrasonic intensity measurement position when the distance between the substrate and the counter electrode is 10 cm or more. [Figure 7] This is a plan view in the width direction of the substrate, showing the ultrasonic intensity measurement position when the distance between the substrate and the counter electrode is less than 10 cm. [Figure 8] This is a perspective view of an example of a first ultrasonic transducer and ultrasonic attenuation means. [Figure 9] This is a perspective view of an ultrasonic treatment device. [Figure 10] This is a side view of the ultrasonic device, seen from a direction parallel to the vibration plane. [Figure 11] This is a side view of the ultrasonic device, seen from a direction parallel to the vibration plane. [Figure 12] This is a plan view of the ultrasonic device, seen from a direction perpendicular to the vibration plane. [Figure 13] This is a plan view of the ultrasonic device, seen from a direction perpendicular to the vibration plane. [Figure 14] This is a side view of an ultrasonic processing device with the ultrasonic reflector omitted. [Modes for carrying out the invention]

[0024] (A. Embodiment of an electroplating apparatus) Hereinafter, an electroplating apparatus 1 according to the first embodiment of this disclosure will be described with reference to Figures 1 and 2. The electroplating apparatus 1 according to the first embodiment comprises an electroplating tank 11, a first ultrasonic transducer 12 configured to emit first ultrasonic waves inside the electroplating tank 11, substrate support means 14, 141 configured to support a substrate 3 in the substrate placement area, and a counter electrode 15. The frequency of the first ultrasonic waves emitted by the first ultrasonic transducer 12 is 15 kHz or more and 80 kHz or less. The intensity of the first ultrasonic waves at a location 5 cm away from the center of the substrate placement area in the width direction, and at a location between the center of the substrate placement area in the width direction and the counter electrode 15, where the distance from the substrate placement area is even closer, is 0.20 to 80 kPa / kHz. The electroplating apparatus 1 further includes an ultrasonic attenuation means 121 arranged in a region within 10 cm of the portion of the first ultrasonic transducer 12 exposed to the internal space of the electroplating tank 11.

[0025] In this disclosure, the portion of the first ultrasonic transducer 12 that is exposed to the internal space of the electroplating bath 11 may be referred to as the outer casing of the ultrasonic transducer. Furthermore, the area within 10 cm of the outer casing of the first ultrasonic transducer 12 may be referred to as the vicinity of the outer casing of the first ultrasonic transducer 12.

[0026] The inventors diligently investigated means to alleviate the constraints imposed by the diffusion layer of the plating bath 2 on the plating speed and film characteristics. They found that applying ultrasonic vibration to the plating bath 2 could mitigate the adverse effects of the diffusion layer.

[0027] However, the inventors discovered that the lifespan of the ultrasonic transducer used in the plating bath 2 was significantly shortened. Specifically, they found that the outer material of the ultrasonic transducer corroded in a short period of time.

[0028] A typical ultrasonic transducer has an outer casing. The outer casing is, for example, a stainless steel box, and a piezoelectric element is housed inside. When the ultrasonic transducer is immersed in the plating bath 2, the outer casing protects the piezoelectric element from the plating bath. The outer casing is the part of the ultrasonic transducer that is in direct contact with the plating bath 2 when it is immersed in the plating bath 2. When the electroplating tank 11 is not filled with the plating bath 2, the outer casing is the part of the ultrasonic transducer that is exposed to the internal space of the electroplating tank 11.

[0029] The exterior material of a typical ultrasonic transducer is made of corrosion-resistant material such as stainless steel. However, corrosion progressed rapidly in the part of this exterior material that comes into direct contact with the plating bath. The inventor attempted to improve the lifespan of the ultrasonic transducer by applying rust-preventive treatment such as paint to the exterior material. However, the corrosion-resistant paint applied to the exterior material alters the ultrasonic oscillation characteristics of the ultrasonic transducer. This impairs the mitigation effect of the diffusion layer against the adverse effects of ultrasound.

[0030] The inventors considered that the ultrasonic waves applied to the exterior material of an ultrasonic transducer may be accelerating the corrosion of the exterior material. In the prior art, corrosion of the exterior material of an ultrasonic transducer has not been particularly considered a problem, and there have been no reported cases of a relationship between high-frequency vibration and corrosion. However, as a result of various investigations conducted by the inventors, it was considered highly likely that high-frequency vibration accelerates the corrosion of the exterior material.

[0031] The inventors have found that by providing the electroplating apparatus 1 with an ultrasonic attenuation means 121 that attenuates the ultrasonic waves reaching the portion of the ultrasonic transducer that directly contacts the plating bath, corrosion of the ultrasonic transducer can be suppressed, thereby extending the lifespan of the electroplating apparatus 1. The configuration of the electroplating apparatus 1 according to the first embodiment and its effects will be described in detail below with reference to Figure 1 and other figures. Hereinafter, the left-right direction in Figure 1 will be referred to as the X direction, and the up-down direction as the Y direction. The direction perpendicular to the X and Y directions will be referred to as the Z direction. The width direction of the substrate 3 is the Z direction.

[0032] (Electroplating tank 11) The electroplating tank 11 is a container that houses the plating bath 2. The number of electroplating tanks 11 included in the electroplating apparatus 1 may be one or two or more. For example, the electroplating apparatus 1 illustrated in Figure 1 is provided with two or more electroplating tanks 11. The substrate 3 passes through these electroplating tanks 11 in a continuous manner.

[0033] (First ultrasonic transducer 12) The first ultrasonic transducer 12 is configured to emit the first ultrasonic waves inside the electroplating bath 11. The arrangement of the first ultrasonic transducer 12 is not particularly limited. The first ultrasonic transducer 12 can be arranged in various ways depending on the arrangement of the substrate 3 and the counter electrode 15. For example, in the continuous electroplating apparatus 1 illustrated in Figures 1 and 2, the first ultrasonic transducer 12 is arranged laterally with respect to the direction of passage of the substrate 3. This is to prevent the counter electrode 15, which is arranged parallel to the surface of the substrate 3, from interfering with the irradiation of the first ultrasonic waves.

[0034] Preferably, the outer casing of the first ultrasonic transducer 12 is made of a corrosion-resistant material, at least in the portion that is in direct contact with the plating bath 2. A corrosion-resistant material is, for example, stainless steel. The "portion that is in direct contact with the plating bath 2" is, in other words, the portion that is exposed to the internal space of the electroplating tank 11.

[0035] (Ultrasonic attenuation means 121) The ultrasonic attenuation means 121 attenuates the ultrasonic waves that reach the outer casing material, i.e., the portion of the first ultrasonic transducer 12 that is exposed to the internal space of the electroplating bath 11. The ultrasonic attenuation means 121 is, for example, an ultrasonic attenuating material attached near the outer casing material of the first ultrasonic transducer 12. The vicinity of the outer casing material of the first ultrasonic transducer 12 is, as described above, the area within 10 cm of the portion of the first ultrasonic transducer 12 that is exposed to the internal space of the electroplating bath 11. The ultrasonic attenuation material is, for example, resin, FRP, and rubber. The shape of the ultrasonic attenuation means 121 and the positional relationship between the ultrasonic attenuation means 121 and the first ultrasonic transducer 12 are not particularly limited as long as the above requirements are met. The ultrasonic attenuation means 121 may be in contact with the outer casing material of the first ultrasonic transducer 12. As illustrated in Figure 8, the ultrasonic attenuation means 121 may be slightly separated from the outer casing material. Preferred configurations of the ultrasonic attenuation means 121 will be described later.

[0036] (Base material support means 14, 141) The substrate support means 14 and 141 are configured to support the substrate 3, which will be electroplated by the electroplating apparatus 1, in the substrate placement area in the plating bath 2. In this disclosure, the position where the substrate is placed is referred to as the substrate placement area. The position and shape of the substrate placement area are not particularly limited. The position and shape of the substrate placement area can be determined according to the shape of the substrate and the position and shape of the counter electrode, which will be described later. In Figures 1 to 7, the area where the substrate 3 is placed is the substrate placement area.

[0037] In this embodiment, the term "support" differs from "fixing" in that it means supporting an object so that it is contained within a certain range. For example, in the continuous plating apparatus shown in Figure 1, the substrate support means 14 and 141 are feed rollers. By rotating the feed rollers, the substrate 3 can be moved within a certain range. This allows the substrate 3 to be immersed in the plating bath 2 inside the plating tank and then lifted out. On the other hand, if the plating apparatus is a batch processing apparatus, the substrate support means 14 and 141 may be, for example, hooks and clamps.

[0038] Furthermore, the substrate support means 141 that are not immersed in the plating bath 2 are energized to the substrate 3. Therefore, at least a portion of the substrate support means 141 located outside the plating bath 2 is made of a conductive material such as copper. In addition, the substrate support means 141 located outside the plating bath 2 is configured to be connectable to a power supply, which is not shown in Figure 1, etc.

[0039] (Opposite pole 15) The counter electrode 15 is positioned near the substrate support means 14. The counter electrode 15 and the substrate support means 14 are connected to a power source. By passing current through the counter electrode 15 and the substrate support means 141, an electrolytic reaction occurs on the surface of the substrate 3 supported by the substrate support means 14 and 141. The position of the counter electrode 15 can be appropriately selected depending on the position where the substrate 3 is placed. For example, in the plating apparatus shown in Figure 1, the counter electrode 15 is positioned parallel to the substrate 3.

[0040] (Plating bath degassing means 16) Preferably, the electroplating apparatus 1 includes a plating bath degassing means 16. The plating bath degassing means 16 degasses the dissolved gas contained in the plating bath 2 that is filled inside the electroplating tank 11. An example of the plating bath degassing means 16 is, for example, a liquid degassing pump 162, or a buffer tank 161 configured to be connectable to the degassing pump 162, or piping, etc.

[0041] The electroplating apparatus 1 illustrated in Figure 1 has a buffer tank 161 connected to the electroplating tank 11 via a means for the flow of the plating bath 2, such as piping. The buffer tank 161 is equipped with a degassing pump 162. The plating bath 2 circulates between the buffer tank 161 and the electroplating tank 11. The plating bath 2 that has moved from the electroplating tank 11 to the buffer tank 161 is degassed in the buffer tank 161 by the degassing pump 162. The plating bath 2 that has moved from the buffer tank 161 to the electroplating tank 11 reduces the amount of dissolved gas in the plating bath 2 in the electroplating tank 11. Alternatively, the amount of dissolved gas in the plating bath 2 can also be reduced by connecting the piping or the electroplating tank 11 to the degassing pump 162.

[0042] The electroplating apparatus 1 shown in Figure 1 employs a so-called overflow cell system. In the electroplating apparatus 1 employing the overflow cell system, the plating bath 2 is supplied from the buffer cell to the bottom of the electroplating layer. Furthermore, the plating bath 2 is allowed to overflow from the top of the electroplating layer. The overflowed plating bath 2 is collected in the buffer tank 161. However, the method of circulating the plating bath 2 can be appropriately changed depending on the type and size of the substrate 3, etc.

[0043] (Ultrasonic frequency) The first ultrasonic transducer 12 is configured to set the frequency of the first ultrasonic wave to between 15 kHz and 80 kHz. The frequency of the first ultrasonic wave may also be between 18 kHz and above, 20 kHz and above, or 30 kHz and above. Alternatively, the frequency of the first ultrasonic wave may be between 70 kHz and below, 60 kHz and below, or 50 kHz and below. By setting the frequency of the first ultrasonic wave within the above range, the adverse effect of the diffusion layer on the electrodeposition reaction is reduced.

[0044] (Intensity of ultrasound) The ultrasonic transducer is configured to produce an ultrasonic intensity of 0.20 to 80 kPa / kHz at a predetermined ultrasonic intensity measurement position 4. The ultrasonic intensity measurement position 4 is the location among (a) and (b) below that is closest to the substrate 3 or the planned substrate placement area. (a) A location 5 cm away from the center of the width direction of the base material 3 or the area where the base material is to be placed. (b) The midpoint between the center in the width direction of the base material 3 or the area where the base material is to be placed and the counter pole 15 Examples of measurement positions are shown in Figures 5 to 7. Figures 4 to 7 are top views of the substrate 3 and counter electrode 15 in the continuous electroplating apparatus 1 of Figure 1. The vertical direction in Figures 4 to 7 is the Z direction, i.e., the width direction of the substrate 3. The width direction of the substrate 3 is perpendicular to the longitudinal direction of the substrate 3, i.e., the direction of travel, and parallel to the surface of the substrate 3. The horizontal direction in Figures 4 to 7 is the X direction.

[0045] In the continuous electroplating apparatus shown in Figure 4, both the substrate 3 and the counter electrode 15 are flat and are arranged parallel to each other. The distance D between the center surface of the substrate 3 in the width direction and the counter electrode 15 is 10 cm or more. In the continuous electroplating apparatus shown in Figure 4, the ultrasonic intensity measurement position 4 is located 5 cm away from the center surface of the substrate 3 in the width direction.

[0046] In the continuous electroplating apparatus shown in Figure 5, both the substrate 3 and the counter electrode 15 are flat and are arranged parallel to each other. The distance D between the center surface of the substrate 3 in the width direction and the counter electrode 15 is less than 10 cm. In the continuous electroplating apparatus shown in Figure 5, the ultrasonic intensity measurement position 4 is located midway between the center of the substrate 3 in the width direction and the counter electrode 15.

[0047] In the continuous electroplating apparatus shown in Figure 6, the substrate 3 is curved, while the counter electrode 15 is flat. The substrate 3 and the counter electrode 15 are not parallel. The distance D between the center surface of the substrate 3 in the width direction and the counter electrode 15 is 10 cm or more. In the continuous electroplating apparatus shown in Figure 6, the ultrasonic intensity measurement position 4 is located 5 cm away from the center surface of the substrate 3 in the width direction.

[0048] In the continuous electroplating apparatus shown in Figure 7, the substrate 3 is curved, while the counter electrode 15 is flat. The substrate 3 and the counter electrode 15 are not parallel. The distance D between the center surface of the substrate 3 in the width direction and the counter electrode 15 is less than 10 cm. In the continuous electroplating apparatus shown in Figure 7, the ultrasonic intensity measurement position 4 is set midway between the center of the substrate 3 in the width direction and the counter electrode 15.

[0049] It should be noted that if the ultrasonic intensity is less than 0.20 kPa / kHz, local agitation around the substrate 3 will be difficult to occur, and the desired effect will not be achieved. Therefore, the ultrasonic intensity at the ultrasonic intensity measurement position 4 should be 0.20 kPa / kHz or higher.

[0050] From the perspective of mitigating the adverse effects of the diffusion layer by ultrasound, there is no upper limit to the ultrasound intensity. However, if the ultrasound intensity exceeds 80 kPa / kHz, its effect will saturate, potentially leading to unnecessary deterioration of the equipment load and working environment. Therefore, the ultrasound intensity at ultrasound intensity measurement position 4 should be kept below 80 kPa / kHz. On the other hand, ultrasound within the above-mentioned range of frequency and intensity will reduce the adverse effects of the diffusion layer on the electrodeposition reaction, regardless of the type of plating bath 2.

[0051] The ultrasonic intensity at ultrasonic intensity measurement position 4 may be set to 0.40 kPa / kHz or higher, or 1.2 kPa / kHz or higher. The ultrasonic intensity at ultrasonic intensity measurement position 4 may be set to 40 kPa / kHz or lower, or 10 kPa / kHz or lower.

[0052] (power supply) The power supply is electrically connected to the counter electrode 15 and the substrate support means 141 located outside the plating bath 2. The power supply supplies current to the counter electrode 15 and the substrate support means 141, causing an electrolytic reaction on the surface of the substrate 3. The power supply may be incorporated into the electroplating apparatus 1. Alternatively, the electroplating apparatus 1 and the power supply may be provided separately and electrically connected as needed.

[0053] (Manufacturing method for electroplated components) Next, a method for manufacturing an electroplated member according to this embodiment will be described.

[0054] The method for manufacturing an electroplated member according to this embodiment (hereinafter simply referred to as the "manufacturing method") includes a step of electroplating the substrate 3 by applying an electric current to the substrate 3 and the counter electrode 15 immersed in the plating bath 2. During electroplating, a first ultrasonic wave with a frequency of 15 kHz or more and 80 kHz or less is applied to the substrate 3 using a first ultrasonic transducer 12. The intensity of the first ultrasonic wave at a point 5 cm away from the surface of the center in the width direction of the substrate 3, and at a point between the center in the width direction of the substrate 3 and the counter electrode 15, whichever is closer to the substrate 3, is set to 0.20 to 80 kPa / kHz. An ultrasonic attenuation means 121 is used to attenuate the ultrasonic waves that reach the part of the first ultrasonic transducer 12 that is in direct contact with the plating bath 2.

[0055] (immersion) First, the substrate 3, supported by substrate support means 14 and 141, is immersed in the plating bath 2 contained in the electroplating tank 11. The location where the substrate 3 is placed is determined according to the shape and size of the substrate 3. The substrate 3 may be fixed in place within the plating bath 2 or it may be moved. For example, in the continuous plating apparatus shown in Figure 1, the substrate 3 moves within the plating bath 2 along a predetermined direction after being immersed in the plating bath 2. The strength of the electrolytic reaction depends on the current density between the substrate 3 and the counter electrode 15. The type of plating bath 2 is not particularly limited. A plating bath 2 can be appropriately adopted according to the desired plating film.

[0056] (Electroplating) Next, current is applied to the substrate 3 and the counter electrode 15 immersed in the plating bath 2. This causes an electrolytic reaction on the surface of the substrate 3 supported by the substrate support means 14 and 141, thereby electroplating the substrate 3. The current application conditions are not particularly limited. Appropriate current application conditions can be adopted depending on the desired plating film. In general methods for manufacturing electroplated members, a diffusion layer is formed on the surface of the substrate 3, which reduces the limiting current density. However, in the method for manufacturing electroplated members according to this embodiment, the adverse effects of the diffusion layer are reduced, so a high current density can be adopted.

[0057] (Mitigation of adverse effects of the diffusion layer by the first ultrasound) When an electrolytic reaction progresses due to the application of electricity, plating metal adheres to the surface of the substrate 3, while metal ions are consumed in the plating bath near the substrate 3. This creates a concentration gradient of metal ions in the region near the substrate 3. The region where the concentration gradient occurs is called the diffusion layer. Since the metal ion concentration is low in the diffusion layer, the electrolytic reaction is inhibited. Therefore, the diffusion layer restricts the plating speed and film characteristics. The diffusion layer cannot be sufficiently removed by liquid flow generating means such as agitators, stirring propellers, and pumps. In the continuous electroplating apparatus 1 illustrated in Figure 1, the substrate 3 moves in the plating bath 2, which creates a liquid flow called an accompanying flow around the substrate 3. However, even with the accompanying flow, the diffusion layer cannot be sufficiently removed.

[0058] Therefore, during electroplating, a first ultrasonic wave with a frequency of 15 kHz to 80 kHz is applied to the substrate 3 using the first ultrasonic transducer 12. Furthermore, during electroplating, the intensity of the first ultrasonic wave is set to 0.20 to 80 kPa / kHz at a point 5 cm away from the surface of the center of the substrate 3 in the width direction, and at a point midway between the center of the substrate 3 in the width direction and the counter electrode 15, whichever is closer to the substrate 3. This reduces the adverse effects of the diffusion layer.

[0059] However, it should be noted that if the intensity of the first ultrasonic wave is less than 0.20 kPa / kHz, local agitation around the substrate 3 will be difficult to occur, and the desired effect will not be achieved. Furthermore, from the perspective of mitigating the adverse effects of the diffusion layer by the first ultrasonic wave, there is no upper limit to the intensity of the first ultrasonic wave. However, if the intensity of the first ultrasonic wave exceeds 80 kPa / kHz, its effect will saturate, potentially leading to unnecessary deterioration of the equipment load and working environment. Therefore, the intensity of the first ultrasonic wave should be kept below 80 kPa / kHz. On the other hand, the first ultrasonic wave, with a frequency and intensity within the above-mentioned range, will exert an effect of reducing the adverse effects of the diffusion layer regardless of the type of plating bath 2.

[0060] The frequency of the first ultrasound may be 20 kHz or higher, or 25 kHz or higher. The frequency of the first ultrasound may be 50 kHz or lower. The intensity of the first ultrasound may be 0.40 kPa / kHz or higher, or 1.2 kPa / kHz or higher. The intensity of the first ultrasound may be 40 kPa / kHz or lower, or 10 kPa / kHz or lower.

[0061] (Amplification of the first ultrasonic wave by the plating bath degassing means 16) Preferably, the plating bath 2 is degassed using the plating bath degassing means 16 to remove gases contained in the plating bath 2. This causes the gases contained in the plating bath 2 contained in the electroplating tank 11 to move to the outside of the plating bath 2. By degassing the plating bath 2, the generation of bubbles in the plating bath 2 is prevented and the energy of the ultrasonic vibration can be amplified. Degassing of the plating bath 2 and application of the first ultrasonic wave may be performed in parallel. Alternatively, the electroplating apparatus 1 may be controlled so that the plating bath 2 is degassed before application of the first ultrasonic wave and degassing is stopped when the first ultrasonic wave is applied. Degassing of the plating bath 2 contributes to increasing the size of the electroplating tank 11.

[0062] (Mitigation of corrosion of the first ultrasonic transducer 12 by ultrasonic attenuation means 121) When the first ultrasonic wave is applied to the plating bath 2, the first ultrasonic wave is also applied to the contact area between the casing material of the first ultrasonic transducer 12 and the plating bath 2. This accelerates the corrosion of the casing material. If there is only one ultrasonic transducer in the electroplating bath, the ultrasonic waves reflected by the inner wall of the electroplating bath accelerate the corrosion of the ultrasonic transducer. If there are two or more ultrasonic transducers in the electroplating bath, the ultrasonic waves irradiated from the other ultrasonic transducers also accelerate the corrosion of the ultrasonic transducers.

[0063] In conventional technology, corrosion of the exterior material of ultrasonic transducers has not been considered a particular problem. There have also been no reported cases of a relationship between high-frequency vibration and corrosion. However, based on various studies conducted by the present inventors, it is highly likely that high-frequency vibration accelerates the corrosion of the exterior material.

[0064] Therefore, the ultrasonic attenuation means 121 is used to attenuate the ultrasonic waves that reach the portion of the first ultrasonic transducer 12 that is in direct contact with the plating bath 2. This reduces cavitation generation in the vicinity of that portion. The vicinity of the portion of the first ultrasonic transducer 12 that is in direct contact with the plating bath 2 refers to the area within 10 cm of the portion of the first ultrasonic transducer 12 that is in direct contact with the plating bath 2. This suppresses corrosion of the portion of the first ultrasonic transducer 12 that is exposed to the internal space of the electroplating tank 11, and extends the lifespan of the electroplating apparatus 1.

[0065] As mentioned above, degassing the plating bath amplifies the ultrasonic waves in the plating bath. This amplification of ultrasonic waves can accelerate the corrosion of the ultrasonic transducers placed in the plating bath. However, the ultrasonic attenuation means 121 prevents the corrosion of the ultrasonic transducers from being accelerated by the degassing of the plating bath. The combination of degassing the plating bath 2 and the ultrasonic attenuation means 121 achieves both the prevention of adverse effects on the diffusion layer in the large electroplating tank 11 and the extension of the lifespan of the ultrasonic transducers.

[0066] As described above, the basic aspects of the electroplating apparatus 1 and the method for manufacturing electroplated members according to this embodiment have been explained. More preferred embodiments of the electroplating apparatus 1 and the method for manufacturing electroplated members according to this embodiment will be described below. Unless otherwise specified, the embodiments described below are applicable to both the electroplating apparatus 1 and the method for manufacturing electroplated members according to this embodiment.

[0067] (Removal of air bubbles adhering to the surface of the substrate 3 using an air bubble removal means) The electroplating apparatus 1 may have means for removing bubbles that are generated when hydrogen gas produced by a side reaction of electroplating is adsorbed onto the surface of the substrate 3. The bubble removal means is configured to remove bubbles that are generated on the surface of the substrate 3 being electroplated by the electroplating apparatus 1. Examples of bubble removal means include, for example, a stirring bar, a stirring propeller, and liquid flow generating means such as a pump. Alternatively, a second ultrasonic transducer 13, which will be described later, can be used as a bubble removal means. The liquid flow generating means and the second ultrasonic transducer 13 may be used in combination.

[0068] When an electrolytic reaction progresses due to the application of electricity, hydrogen is generated on the surface of the substrate 3. The hydrogen adheres to the surface of the substrate 3 as bubbles. In the areas where bubbles adhere, plating ions are not supplied, so the electrolytic reaction stops progressing. Therefore, during electroplating, a bubble removal means may be used to remove the bubbles adhering to the surface of the substrate 3. This promotes the electrolytic reaction on the surface of the substrate 3.

[0069] However, in an electroplating apparatus 1 in which the substrate 3 is moved in the plating bath 2, such as the continuous electroplating apparatus 1 illustrated in Figure 1, an accompanying flow is generated around the substrate 3. In such an apparatus, bubble removal means such as liquid flow generating means are not essential.

[0070] (Acoustic impedance of ultrasonic attenuation means 121) The ultrasonic attenuation means 121 is attached to the first ultrasonic transducer 12, and has an acoustic impedance of 1 × 10⁻¹⁰. 7 kg·m -2 sec -1 The ultrasonic attenuating material may be less than the specified value. By setting the acoustic impedance of the ultrasonic attenuating means 121 within the above range, corrosion of the portion of the first ultrasonic transducer 12 that is exposed to the internal space of the electroplating bath 11, or the portion of the first ultrasonic transducer 12 that is in direct contact with the plating bath 2, is further suppressed.

[0071] (Shape of ultrasonic attenuation means 121, etc.) The ultrasonic damping means 121 is, for example, an ultrasonic damping material. The ultrasonic damping material has a thickness of 5 mm or more and an area of ​​at least twice the surface area of ​​the outer casing material of the first ultrasonic transducer 12. The thickness of the ultrasonic damping material is the dimension of the ultrasonic damping material measured along a direction perpendicular to the vibration plane of the first ultrasonic transducer 12. The area of ​​the ultrasonic damping material is the area of ​​the projected portion when the ultrasonic damping material is projected onto a plane parallel to the vibration plane of the first ultrasonic transducer 12. The surface area of ​​the outer casing material of the first ultrasonic transducer 12 is the area of ​​the part of the first ultrasonic transducer 12 that is in direct contact with the plating bath 2, or the area of ​​the part of the first ultrasonic transducer 12 that is exposed to the internal space of the electroplating tank 11.

[0072] Figure 8 shows a perspective view of an example of the first ultrasonic transducer 12 and ultrasonic damping means 121. The ultrasonic damping means 121 illustrated in Figure 8 is an ultrasonic damping material. Both the first ultrasonic transducer 12 and the ultrasonic damping means 121 have a substantially rectangular parallelepiped shape and are mounted on the flat wall surface of the electroplating bath 11. The vibration surface 12S of the first ultrasonic transducer 12 is parallel to the wall surface of the electroplating bath 11 and is oriented upwards in the plane of the paper in Figure 8. There are four ultrasonic damping means. The four ultrasonic damping means are arranged to surround the first ultrasonic transducer 12.

[0073] In the first ultrasonic transducer 12 illustrated in Figure 8, the sum of the area of ​​the vibrating surface and the area of ​​the side surfaces is the surface area of ​​the outer casing of the first ultrasonic transducer 12. Since the bottom surface of the first ultrasonic transducer 12 in Figure 8 does not directly contact the plating bath 2, the area of ​​the bottom surface is not included in the surface area of ​​the outer casing of the first ultrasonic transducer 12. Also, the area of ​​the ultrasonic damping means 121 illustrated in Figure 8 is the sum of the areas of the upper surfaces of the four ultrasonic damping means 121. The thickness of the ultrasonic damping means 121 illustrated in Figure 8 is the dimension of the ultrasonic damping means 121 measured along the vertical direction of the paper in Figure 8.

[0074] The ultrasonic attenuation means 121 may be attached to the side surface of the casing material of the first ultrasonic transducer 12. The ultrasonic attenuation material may be directly attached to the casing material. For example, the ultrasonic attenuation material may be attached so as to cover a part of the casing material. Alternatively, the ultrasonic attenuation material may be attached indirectly or directly, as illustrated in Figure 8. That is, the ultrasonic attenuation material may be arranged around the casing material on the wall surface of the electroplating tank 11 in which the casing material is installed.

[0075] As illustrated in Figure 8, the ultrasonic damping material arranged around the exterior material may be installed discontinuously. That is, when the ultrasonic damping material is viewed in plan along a direction perpendicular to the wall surface of the electroplating bath 11, it may be installed discontinuously around the exterior material rather than in a continuous circular arrangement. For example, in Figure 8, the ultrasonic damping means 121 is arranged only above, below, to the left and right of the exterior material of the first ultrasonic transducer 12, and is not installed diagonally. Even if the exterior material of the first ultrasonic transducer 12 and the ultrasonic damping material are not in direct contact, the ultrasonic damping material can suppress the first ultrasonic waves applied to the exterior material. When multiple ultrasonic damping materials are installed discontinuously, it is preferable to keep the distance between the multiple ultrasonic damping materials and the first ultrasonic transducer 12 constant. Furthermore, it is preferable that the multiple ultrasonic damping materials are arranged along the outer circumferential surface of the vibration surface 12S of the first ultrasonic transducer 12. On the other hand, the ultrasonic damping material may continuously surround the outer casing of the first ultrasonic transducer 12. That is, when viewing a plane parallel to the vibration surface 12S of the first ultrasonic transducer 12 in plan view, one ultrasonic damping means 121 may completely surround the first ultrasonic transducer 12 without any gaps. However, it is undesirable for the ultrasonic damping material to prevent the first ultrasonic transducer 12 from irradiating the substrate with ultrasonic waves. Therefore, in this case, the ultrasonic damping material surrounding the first ultrasonic transducer 12 preferably has an opening. Preferably, when viewing a plane parallel to the vibration surface 12S of the first ultrasonic transducer 12 in plan view, the vibration surface 12S is positioned inside the opening of the ultrasonic damping material, and the vibration surface and the ultrasonic damping material do not overlap. When multiple first ultrasonic transducers 12 are arranged in close proximity, it is preferable to place an ultrasonic attenuating material between them.

[0076] As a result of various studies by the inventors, it is preferable to set the thickness of the ultrasonic attenuating material to 5% or more of the wavelength of the first ultrasonic wave, and the size of the ultrasonic attenuating material to an area at least twice the surface area of ​​the portion of the first ultrasonic transducer 12 that is exposed to the internal space of the electroplating bath 11, or at least twice the surface area of ​​the portion of the first ultrasonic transducer 12 that is in direct contact with the plating bath 2, and to arrange the ultrasonic attenuating material around the first ultrasonic transducer 12 on the wall surface of the electroplating bath 11 in which the first ultrasonic transducer 12 is installed. It has become clear that with such an ultrasonic attenuating means 121, the first ultrasonic wave is effectively attenuated in the first ultrasonic transducer 12, and corrosion of the first ultrasonic transducer 12 is suppressed.

[0077] From the standpoint of suppressing corrosion of the first ultrasonic transducer 12, there is no upper limit to the thickness and area of ​​the ultrasonic damping material, and various options may be selected depending on the ease of installation in the plating bath. Furthermore, the ultrasonic damping material may be placed between the first ultrasonic transducer 12 and the plating bath wall. The material of the ultrasonic damping material may have corrosion resistance to the plating bath 2 and satisfy the acoustic impedance described above. Examples of ultrasonic damping materials that satisfy these conditions include resin, FRP, and rubber.

[0078] (Second ultrasonic transducer 13) As shown in Figure 3, the bubble removal means described above may be a second ultrasonic transducer 13. The second ultrasonic transducer 13 emits a second ultrasonic wave with a frequency of over 80 kHz and up to 180 kHz into the electroplating tank 11. During electroplating, bubbles formed on the surface of the substrate 3 can also be removed from the substrate 3 by applying the second ultrasonic wave to the substrate 3 using the second ultrasonic transducer 13. Since the frequency of the second ultrasonic wave is over 80 kHz, it is not considered to have the effect of reducing the adverse effects of the diffusion layer like the first ultrasonic wave. On the other hand, the second ultrasonic wave has the effect of removing bubbles from the substrate 3.

[0079] Similar to the first ultrasonic transducer 12, the arrangement of the second ultrasonic transducer 13 is not particularly limited. The second ultrasonic transducer 13 can be arranged in various ways depending on the arrangement of the substrate 3 and the counter electrode 15. For example, in the continuous electroplating apparatus 1 illustrated in Figure 3, the second ultrasonic transducer 13 is arranged laterally with respect to the direction of substrate 3 passage. This is to prevent the counter electrode 15, which is arranged parallel to the surface of the substrate 3, from interfering with the irradiation of the second ultrasonic wave.

[0080] The frequency of the second ultrasound may be 90 kHz or higher. The frequency of the second ultrasound may be 160 kHz or lower, or 140 kHz or lower. The intensity of the second ultrasound is not particularly limited, but for example, similar to the first ultrasound, the intensity of the second ultrasound at a point 5 cm away from the surface of the center in the width direction of the substrate 3, and at the center point between the center in the width direction of the substrate 3 and the counter electrode 15, whichever is closer to the substrate 3, may be 0.20 to 80 kPa / kHz.

[0081] (Number of first ultrasonic transducers 12) The number of first ultrasonic transducers 12 is not particularly limited. In Figure 2, the first ultrasonic transducers 12 are mounted on both sides of the substrate 3 at regular intervals. This allows the first ultrasonic waves to be applied to the substrate 3 from two or more directions during electroplating. Therefore, it becomes easier to apply the first ultrasonic waves to the entire surface of the substrate 3. For this reason, it is preferable to have two or more first ultrasonic transducers 12. On the other hand, if the substrate 3 is small, it is also possible to have only one first ultrasonic transducer 12. Various numbers can be selected depending on the shape and arrangement of the substrate 3.

[0082] (Measurement and control of dissolved oxygen in the plating bath) The electroplating apparatus 1 may further include a dissolved oxygen measuring means. Using the dissolved oxygen measuring means, the amount of dissolved oxygen in the plating bath 2 is measured, and the amount of dissolved oxygen is determined to be 6 mg·L. -1The dissolved gas contained in the plating bath 2 may be removed as described below. However, a portable dissolved oxygen measuring device may be used to control the amount of dissolved oxygen within the above range. In this case, the electroplating apparatus 1 does not need to be equipped with a means for measuring dissolved oxygen.

[0083] The dissolved gases in the plating bath 2 are mainly nitrogen and oxygen, which are present in the atmosphere. It is estimated that hydrogen generated by the electrolytic reaction hardly dissolves in the plating bath 2. Therefore, the amount of dissolved oxygen can be used as an indicator of the total amount of dissolved gases in the plating bath 2. According to the inventor's findings, by using the plating bath degassing means 16, the amount of dissolved oxygen in the plating bath 2 can be reduced to 6 mg·L. -1 By controlling the following, the first ultrasonic wave is further amplified and the effect of the diffusion layer is further reduced: Dissolved oxygen amount in plating bath 2: 5 mg / L -1 The following is also acceptable.

[0084] (Other embodiments) While embodiments of this disclosure have been described above, this disclosure is not limited thereto and can be modified as appropriate without departing from the technical concept of the disclosure. Modifications of this disclosure are described below.

[0085] A larger electroplating tank 11 is preferable because it improves the efficiency of the electroplating work and increases the size of the substrate 3 that the electroplating apparatus 1 can electroplat. For example, the capacity of one electroplating tank 11 may be 500L or more, 1000L or more, 2000L or more, or 2500L or more. In this case, the size of the substrate 3 may be 500mm wide or more, 750mm wide or more, or 1000mm wide or more.

[0086] The first ultrasonic transducer 12 may be capable of pulse oscillation, which switches the ultrasonic oscillation on and off at a constant period, or sweep oscillation, which vibrates at a frequency in the range of several kHz. By performing pulse oscillation or sweep oscillation, the state of the ultrasonic waves inside the electroplating bath 11 changes, making it less likely for standing waves to occur, thereby further improving the quality of the plated film.

[0087] Similar to the first ultrasonic transducer 12, the number of the second ultrasonic transducers 13 is not limited, and may be 2 or more. This allows bubbles adhering to the surface of the base material 3 to be removed more efficiently. Also, similar to the first ultrasonic transducer 12, the second ultrasonic transducer 13 may also include an ultrasonic attenuation means 121 that attenuates ultrasonic waves reaching the exterior material of the second ultrasonic transducer 13. The above-described ultrasonic attenuation material can be applied to both the first ultrasonic transducer 12 and the second ultrasonic transducer 13.

[0088] The counter electrode 15 may be a soluble anode or an insoluble anode. A soluble anode dissolves during electroplating, replenishing the plating metal into the plating bath 2. An insoluble anode does not dissolve during electroplating. The use of a soluble anode is effective as a means for ensuring productivity when electroplating a large base material 3. On the other hand, when a soluble anode is used as the counter electrode 15, it becomes necessary to increase the corrosivity of the plating bath 2. In the electroplating apparatus 1 according to the present embodiment, the ultrasonic attenuation means 121 is used to improve the corrosion resistance of the ultrasonic transducer, so the counter electrode 15 can be a soluble anode.

[0089] (B. Embodiment of Ultrasonic Processing Apparatus) (1. Ultrasonic Processing Apparatus B1) An ultrasonic processing apparatus B1 according to an aspect of the present disclosure includes: an ultrasonic transducer B11 configured to be capable of irradiating a liquid B2 with ultrasonic waves X from a vibration surface B111; a tank B13 configured to be capable of holding the liquid B2; and an ultrasonic reflector disposed in the liquid B2. The liquid B2 is acidic or alkaline, the frequency of the ultrasonic waves X is not less than 15 kHz and not more than 180 kHz, and the acoustic impedance of the ultrasonic reflector is 1×10 7 kg·m -2 ·sec -1 or more, and satisfies the following formulas 1 to 4. 100mm≦L1……(Formula 1) 10mm≦L2……………(Formula 2) 0<S1≦0.5×S3………(Formula 3) 0.1×S3≦S2max……(Formula 4) L1 is the distance measured along the direction perpendicular to the vibration surface between the point on the ultrasonic reflector furthest from the vibration surface and the point on the ultrasonic reflector closest to the vibration surface, in the space within the vibration surface when viewed from above along the direction perpendicular to the vibration surface in the liquid; L2 is the distance measured along the direction perpendicular to the vibration surface between the point on the ultrasonic reflector closest to the vibration surface and the vibration surface, in the space within the vibration surface when viewed from above along the direction perpendicular to the vibration surface in the liquid; S1 is the projected area of ​​the ultrasonic reflector in the liquid with respect to the vibration surface; S2max is the maximum value of the projected area of ​​the ultrasonic reflector in the liquid with respect to a plane perpendicular to the vibration surface; and S3 is the area of ​​the vibration surface.

[0090] The ultrasonic processing apparatus B1 according to this embodiment is suitable for carrying out the ultrasonic processing method described later. An overview of the ultrasonic processing apparatus B1 according to this embodiment will be described below. Next, the ultrasonic processing method will be described.

[0091] The ultrasonic apparatus B1 includes a tank B13 for holding liquid B2. Liquid B2 can be acidic or alkaline. Preferred examples of liquid B2 are electroplating baths, pickling baths, and degreasing baths.

[0092] The ultrasonic apparatus B1 includes an ultrasonic transducer B11. The ultrasonic transducer B11 has a vibrating surface B111. The vibrating surface B111 is placed in a liquid B2. During operation of the ultrasonic transducer B11, the vibrating surface B111 vibrates and irradiates the liquid B2 with ultrasonic waves X. The ultrasonic transducer B11 is configured to have a frequency of ultrasonic waves X emitted by the vibrating surface B111 between 15 kHz and 180 kHz.

[0093] The ultrasonic treatment device B1 is further equipped with an ultrasonic reflector. The acoustic impedance of the ultrasonic reflector is 1 × 10⁻⁶. 7 kg·m -2 sec -1as described above. The ultrasonic reflector is, for example, the ultrasonic reflector B12 illustrated in FIG. 9 and the like. In addition, an object to which ultrasonic treatment is applied, that is, a material to be treated, may also be included in the ultrasonic reflector. The acoustic impedance is 1×10 7 kg·m -2 ·sec -1 The above-mentioned material to be treated is regarded as an ultrasonic reflector.

[0094] The ultrasonic reflectors are arranged so as to satisfy the following formulas 1 to 4. 100mm≦L1……(Formula 1) 10mm≦L2……………(Formula 2) 0<S1≦0.5×S3………(Formula 3) 0.1×S3≦S2max……(Formula 4) The definitions and measurement methods of the symbols L1, L2, S1, S2max, and S3 included in these formulas are the same as those of these symbols in the ultrasonic treatment method described later.

[0095] (2. Ultrasonic Treatment Method) An ultrasonic treatment method according to another aspect of the present disclosure, as illustrated in FIGS. 9 to 13, comprises a step of irradiating a liquid B2 with ultrasonic waves X from a vibration surface B111, wherein the liquid B2 is made acidic or alkaline, and the frequency of the ultrasonic waves X is set to 15kHz or more and 180kHz or less, 1×10 7 kg·m -2 ·sec -1 An ultrasonic reflector having the above acoustic impedance (for example, the ultrasonic reflector B12 and the high acoustic impedance material to be treated B4, etc.) is placed in the liquid B2 so as to satisfy the following formulas 1 to 4. 100mm≦L1……(Formula 1) 10mm≦L2……………(Formula 2) 0<S1≦0.5×S3………(Formula 3) 0.1×S3≦S2max……(Formula 4) L1 is the distance measured along the direction perpendicular to the vibration surface between the point on the ultrasonic reflector furthest from the vibration surface and the point on the ultrasonic reflector closest to the vibration surface, in the space within the vibration surface when viewed from above along the direction perpendicular to the vibration surface in the liquid; L2 is the distance measured along the direction perpendicular to the vibration surface between the point on the ultrasonic reflector closest to the vibration surface and the vibration surface, in the space within the vibration surface when viewed from above along the direction perpendicular to the vibration surface in the liquid; S1 is the projected area of ​​the ultrasonic reflector in the liquid with respect to the vibration surface; S2max is the maximum value of the projected area of ​​the ultrasonic reflector in the liquid with respect to a plane perpendicular to the vibration surface; and S3 is the area of ​​the vibration surface.

[0096] (Liquid B2) The ultrasonic treatment method includes the step of irradiating liquid B2 with ultrasonic waves X. Liquid B2 is held in a tank B13 of an ultrasonic treatment apparatus B1, for example. Liquid B2 is either acidic or alkaline. If liquid B2 is acidic, its pH is, for example, 1 to 5. If liquid B2 is alkaline, its pH is, for example, 9 to 12. Preferred examples of liquid B2 are electroplating baths, pickling baths, and degreasing baths.

[0097] (Vibration surface B111 and ultrasonic X) Ultrasonic waves X are irradiated onto liquid B2 from the vibrating surface B111 of the ultrasonic transducer B11. The ultrasonic transducer B11 can be, for example, a submersible transducer. The vibrating surface B111 is the surface that emits ultrasonic waves X when the ultrasonic transducer B11 is in operation. In Figures 10 and 11, the vibrating surface B111 is parallel to the water surface of liquid B2, but the vibrating surface B111 may be tilted relative to the water surface.

[0098] The frequency of ultrasonic X is set to be between 15 kHz and 180 kHz. The frequency of ultrasonic X may also be 20 kHz or higher, 30 kHz or higher, or 50 kHz or higher. The frequency of ultrasonic X may also be 150 kHz or lower, 130 kHz or lower, or 100 kHz or lower.

[0099] (Ultrasonic reflective material) An ultrasonic reflector is placed in liquid B2. The ultrasonic reflector is 1 × 10 7 kg·m -2 sec -1 The material has the above-mentioned acoustic impedance. Acoustic impedance is a value obtained by product of the density of the material and the speed of sound in the material. Acoustic impedance quantifies the ease with which sound propagates in the material. The acoustic impedance of a material can be determined by measuring the density of the material with a densimeter and then measuring the speed of sound in the material with a velocometer. In this disclosure, 1 × 10 7 kg·m -2 sec -1 The above acoustic impedance is called "high acoustic impedance," and 1 × 10 7 kg·m -2 sec -1 Acoustic impedance below a certain value is referred to as "low acoustic impedance."

[0100] In ultrasonic treatment, the ultrasonic reflector may take one of the following forms: (1) Only the high acoustic impedance treated material B4 itself becomes an ultrasonic reflector. (2) Both the high acoustic impedance treatment target material B4 and the ultrasonic reflector B12 (a reflector with high acoustic impedance), which is part of the ultrasonic treatment device B1, are ultrasonic reflectors. In other words, in this disclosure, the term "ultrasonic reflector" is defined as a member that reflects ultrasonic waves X in a liquid, excluding the walls and bottom of the tank B13 and the surface of the ultrasonic transducer B11, and having a high acoustic impedance. The object to be processed may be included in the ultrasonic reflector. Furthermore, the ultrasonic processing apparatus B1 may be provided with an ultrasonic reflector B12 having a high acoustic impedance. In this case, not only the object to be processed B4 with a high acoustic impedance but also the ultrasonic reflector B12 becomes an ultrasonic reflector.

[0101] (Size and placement of ultrasonic reflectors) The ultrasonic reflector is placed in liquid B2 such that it satisfies equations 1 to 4 below. 100mm≦L1……(Formula 1) 10 mm≦L2……………(Formula 2) 0<S1≦0.5×S3………(Formula 3) 0.1×S3≦S2max……(Formula 4) The symbols L1, L2, S1, S2max, and S3 included in the above formulas are described in detail below with reference to FIGS. 9 to 13.

[0102] (L1) Details of L1 are shown in FIGS. 9, 10 and 11. FIG. 9 is a perspective view of the ultrasonic treatment apparatus B1. In FIG. 9, the tank B13 and the liquid B2 are omitted for improving visibility, and in FIG. 9, all regions of the ultrasonic reflection device B12 and the low acoustic impedance treatment target material B3 are disposed in the liquid B2. FIGS. 10 and 11 are side views of the ultrasonic treatment apparatus B1. In FIG. 10, the ultrasonic reflection device B12 and the high acoustic impedance treatment target material B4 are disposed in the liquid B2. In FIG. 11, the ultrasonic reflection device B12 and the high acoustic impedance treatment target material B4 are disposed in the liquid B2. In FIGS. 10 and 11, a part of the ultrasonic reflection device B12 is disposed outside the liquid B2.

[0103] L1 is a distance measured along a direction perpendicular to the vibration surface B111 between a point P on the ultrasonic reflective material that is farthest from the vibration surface B111 and a point Q on the ultrasonic reflective material that is closest to the vibration surface B111, in a space within the vibration surface B111 when viewed in plan along a direction perpendicular to the vibration surface B111 in the liquid B2.

[0104] The "space within the vibrating surface B111 when viewed in a plan view along a direction perpendicular to the vibrating surface B111" will be explained with reference to Figure 12. Figure 12 shows the ultrasonic device B1 when viewed in a plan view along a direction perpendicular to the vibrating surface B111. In Figure 12, the space extending perpendicular to the plane of the paper along the edge of the vibrating surface B111 is the "space within the vibrating surface B111 when viewed in a plan view along a direction perpendicular to the vibrating surface B111". In Figure 12, only the hatched area of ​​the ultrasonic reflector B12 is within this space. When identifying locations P and Q in the ultrasonic reflector B12 in Figure 12, only the hatched area of ​​the ultrasonic reflector B12 is considered. The unhatched area of ​​the ultrasonic reflector B12, i.e., the area outside the space within the vibrating surface B111 when viewed in a plan view along a direction perpendicular to the vibrating surface B111, is ignored when identifying locations P and Q.

[0105] When multiple ultrasonic reflectors are present, "the point P furthest from the vibration surface B111 in the ultrasonic reflector" means the point furthest from the vibration surface B111 among all ultrasonic reflectors arranged in the space within the vibration surface B111 when viewed in a plan view along a direction perpendicular to the vibration surface B111. Similarly, when multiple ultrasonic reflectors are present, "the point Q closest to the vibration surface B111 in the ultrasonic reflector" means the point closest to the vibration surface B111 among all ultrasonic reflectors arranged in the space within the vibration surface B111 when viewed in a plan view along a direction perpendicular to the vibration surface B111.

[0106] As stated above, the term "ultrasonic reflector" is a concept that includes both the high acoustic impedance treated material B4 itself, and the ultrasonic reflector B12 (a reflector with high acoustic impedance), which is part of the ultrasonic treatment device B1.

[0107] L1 is measured along the direction perpendicular to the vibration surface B111. If the imaginary line connecting P and Q by the shortest distance is not perpendicular to the vibration surface B111, then L1 is the length of the component of that imaginary line perpendicular to the vibration surface B111. When measuring L1, it should be noted that the direction perpendicular to the vibration surface B111 may differ from the direction perpendicular to the water surface. L1 can be considered as the height of the ultrasonic reflector relative to the vibration surface B111.

[0108] However, objects outside of liquid B2 do not substantially affect the state of ultrasonic waves X inside liquid B2. Therefore, L1 does not include the size of the portion of the ultrasonic reflector that is outside of liquid B2.

[0109] As shown in Figure 9, when the entire ultrasonic reflector is immersed in liquid B2, the point P on the ultrasonic reflector furthest from the vibrating surface in the liquid is the end of the ultrasonic reflector opposite to the vibrating surface B111. In Figure 9, the end of the ultrasonic reflector opposite to the vibrating surface B111 is the upper end of the ultrasonic reflector B12 on the plane of the paper.

[0110] As shown in Figures 10 and 11, when a portion of the ultrasonic reflector is located outside the liquid B2, the point P of the ultrasonic reflector furthest from the vibration surface B111 in the liquid may not be the end opposite to the vibration surface B111 of the ultrasonic reflector. For example, in Figures 10 and 11, the point P of the ultrasonic reflector furthest from the vibration surface B111 in the liquid B2 is the surface of the liquid B2.

[0111] Furthermore, in the apparatus illustrated in Figure 10, the material to be treated is a low-acoustic-impedance material B3. The low-acoustic-impedance material B3 present inside the liquid B2 is ignored when measuring L1, and L2, S1, and S2max, which will be described later. As will be described later, in the ultrasonic treatment method according to this embodiment, it is important to reduce the reflected ultrasonic waves Y that return to the vibrating surface B111. The intensity of the reflected ultrasonic waves Y generated by the low-acoustic-impedance material B3 is small. The low-acoustic-impedance material B3 does not hinder the reduction of reflected ultrasonic waves Y that return to the vibrating surface B111. Therefore, the low-acoustic-impedance material B3 can be ignored when considering the arrangement and size of objects in the liquid B2. On the other hand, in the apparatus shown in Figure 11, the material to be treated is a high-acoustic-impedance material B4. The high-acoustic-impedance material B4 present inside the liquid B2 is taken into consideration when measuring L1, and L2, S1, and S2max, which will be described later.

[0112] (L2) Figures 9, 10, and 11 show details of L2. L2 is the distance measured along the direction perpendicular to the vibration plane B111 between the point Q closest to the vibration plane B111 of the ultrasonic reflector and the vibration plane B111 itself, in the space within the vibration plane B111 when viewed in plan along the direction perpendicular to the vibration plane B111 within the liquid B2. As with L1, both the ultrasonic reflector B12 and the high acoustic impedance treated material B4 are considered in the measurement of L2. The portion outside of the liquid B2 is ignored in the measurement of L2. The region outside the space within the vibration plane B111 when viewed in plan along the direction perpendicular to the vibration plane B111 is ignored in the measurement of L2. The low acoustic impedance treated material B3 is ignored in the measurement of L2. Furthermore, when viewing the device in plan along the direction perpendicular to the vibration plane B111, objects outside the vibration plane B111 are ignored in the measurement of L2. L2 is measured along the direction perpendicular to the vibration plane B111.

[0113] (S1) Figures 12 and 13 show details of S1. Figures 12 and 13 are plan views of the ultrasonic treatment apparatus B1. In Figures 12 and 13, the tank B13 and liquid B2 are omitted for improved visibility, but in Figures 12 and 13, the entire area of ​​the ultrasonic reflector B12 and the low acoustic impedance treatment material B3 is located in the liquid B2. In Figure 12, the ultrasonic reflector B12 and the low acoustic impedance treatment material B3 are located in the liquid B2. In Figure 13, the ultrasonic reflector B12 and the high acoustic impedance treatment material B4 are located in the liquid B2.

[0114] S1 is the projected area S1 of the ultrasonic reflector in the liquid B2 with respect to the vibrating surface B111. That is, when the ultrasonic apparatus B1 is viewed from above along a direction perpendicular to the vibrating surface B111, S1 is the area of ​​the region where the ultrasonic reflector and the vibrating surface B111 overlap. As with L1, both the ultrasonic reflector B12 and the high acoustic impedance treated material B4 are considered in the measurement of S1. The low acoustic impedance treated material B3 is ignored in the measurement of S1. The portion outside of the liquid B2 is ignored in the measurement of S1.

[0115] In Figure 12, a portion of the ultrasonic reflector B12 overlaps with the vibrating surface B111. Therefore, the area of ​​the shaded portion labeled S1 in the ultrasonic reflector B12 is included in S1. However, the area of ​​the low acoustic impedance treated material B3 shown in Figure 12 is not included in S1. Therefore, the shaded treatment is not applied to the low acoustic impedance treated material B3 in Figure 12.

[0116] In Figure 13, a portion of the ultrasonic reflector B12 overlaps with the vibrating surface B111. Therefore, the area of ​​the shaded portion labeled S1 in the ultrasonic reflector B12 is included in S1. Furthermore, in Figure 13, the high acoustic impedance treated material B4 overlaps with the vibrating surface B111. The area of ​​the shaded portion labeled S1 in the high acoustic impedance treated material B4 is also included in S1. In Figure 13, the total area of ​​the two shaded portions labeled S1 is considered to be the projected area S1 of the ultrasonic reflector in the liquid B2 relative to the vibrating surface B111.

[0117] (S2max) Figures 10 and 11 show the details of S2max. S2max is the maximum value of the projected area S1 of the ultrasonic reflector in the liquid B2 with respect to a plane A perpendicular to the vibration plane B111.

[0118] A plane A perpendicular to the vibrating plane means any virtual plane that is perpendicular to the vibrating plane B111 and lies on the vibrating plane B111. In Figures 10 and 11, the region between the dashed line R extending vertically through the left edge of the plane of the vibrating plane B111 and the dashed line S extending vertically through the right edge of the plane of the plane of the vibrating plane B111 is the plane A perpendicular to the vibrating plane. In this disclosure, when the ultrasonic apparatus B1 is viewed parallel to the vibrating plane B111, the projected area of ​​the ultrasonic reflector in the liquid B2 with respect to any plane A perpendicular to the vibrating plane B111 is defined as S2.

[0119] It should be noted here that the plane A perpendicular to the vibration plane B111 is not uniquely determined and can be freely rotated along the vertical direction of the vibration plane B111. S2 can fluctuate when the plane A perpendicular to the vibration plane B111 is rotated. Therefore, S2 may also not be uniquely determined. Accordingly, in this disclosure, the maximum value of S2 is defined as S2max, and the value of S2max is specified.

[0120] The plane A perpendicular to the vibrating surface B111, as shown in Figures 10 and 11, is selected to maximize S2. If the ultrasonic reflector B12 on a flat plate is installed perpendicular to the vibrating surface B111, it is highly likely that S2 can be maximized by setting plane A parallel to the ultrasonic reflector B12 and perpendicular to the vibrating surface B111.

[0121] Similar to L1, both the ultrasonic reflector B12 and the high acoustic impedance treated material B4 are considered in the S2max measurement. The low acoustic impedance treated material B3 is ignored in the S2max measurement. The portion outside of liquid B2 is ignored in the S2max measurement.

[0122] In Figure 10, a portion of the ultrasonic reflector B12 does not overlap with plane A perpendicular to the vibration plane B111. The area that does not overlap with plane A is not included in S2max. In Figure 10, the area that does not overlap with plane A is not shaded. Also, in Figure 10, a portion of the ultrasonic reflector B12 is outside the liquid B2. The area outside the liquid B2 is not included in S2max, and is not shaded in Figure 10. Furthermore, in the measurement of S2max, the low acoustic impedance treated material B3 shown in Figure 10 is ignored. Therefore, the low acoustic impedance treated material B3 is not shaded. In Figure 10, the area of ​​the portion of the ultrasonic reflector B12 that is in the liquid B2 and overlaps with plane A perpendicular to the vibration plane B111 is S2max.

[0123] In Figure 11, a portion of the ultrasonic reflector B12 does not overlap with plane A perpendicular to the vibration plane B111. The area that does not overlap with plane A is not included in S2max. In Figure 11, the area that does not overlap with plane A is not shaded. Also in Figure 11, a portion of the ultrasonic reflector B12 is outside the liquid B2. The area outside the liquid B2 is not included in S2max, and in Figure 11, it is not shaded. Furthermore, S2max also includes the projected area of ​​the high acoustic impedance treated material B4 shown in Figure 11. Therefore, the portion of the high acoustic impedance treated material B4 that overlaps with plane A is shaded. In Figure 11, S2max is the sum of the areas of the ultrasonic reflector B12 and the high acoustic impedance treated material B4 that are in the liquid B2 and overlap with plane A perpendicular to the vibration plane B111.

[0124] (S3) S3 is the area of ​​the vibrating surface B111. Figures 12 and 13 show details of S3. S3 is the area of ​​the region enclosed by the outer edge of the vibrating surface B111. When measuring the vibrating surface B111, the ultrasonic reflector and the material being treated are ignored.

[0125] (Effects and Benefits) In the ultrasonic apparatus B1 according to this embodiment, ultrasonic waves X with a frequency of 15 kHz to 180 kHz are irradiated onto the material to be treated. This allows the material to be efficiently ultrasonically treated. However, the ultrasonic transducer B11, when immersed in acid or alkali, is extremely susceptible to corrosion.

[0126] The inventors considered that suppressing cavitation generation near the ultrasonic transducer B11 is important in order to suppress corrosion of the ultrasonic transducer B11 and extend its lifespan. Therefore, after diligent research, the inventors discovered that the cavitation generated near the ultrasonic transducer B11 is caused by ultrasonic waves X that are reflected by an ultrasonic reflector having high acoustic impedance and irradiated onto the ultrasonic transducer B11. Hereinafter, ultrasonic waves X emitted from the ultrasonic transducer B11 and reflected by the ultrasonic reflector will be referred to as reflected ultrasonic waves Y.

[0127] The inventors hypothesized that the lifespan of the ultrasonic transducer B11 could be extended by suppressing the irradiation of reflected ultrasonic waves Y to the ultrasonic transducer B11. The inventors then found that, as schematically shown in Figure 9, by diverting the direction of propagation of reflected ultrasonic waves Y away from the ultrasonic transducer B11, cavitation in the vicinity of the ultrasonic transducer B11 was weakened, thereby extending the lifespan of the ultrasonic transducer B11. By arranging the ultrasonic reflective material to satisfy equations 1 to 4, the direction of propagation of reflected ultrasonic waves Y could be diverted away from the ultrasonic transducer B11.

[0128] L1 is the height of the ultrasonic reflector relative to the vibrating surface B111, as shown in Figures 9, 10, and 11. When L1 is sufficiently large and satisfies Equation 1, most of the component of reflected ultrasonic waves Y is directed away from the vibrating surface B111. This reduces the component of reflected ultrasonic waves Y directed towards the vibrating surface B111.

[0129] L2 is the distance between the vibrating surface B111 and the ultrasonic reflector, as shown in Figures 9, 10, and 11. When L2 is sufficiently large and satisfies Equation 2, the reflected ultrasonic waves Y reflected from the ultrasonic reflector toward the vibrating surface B111 are dispersed. This reduces the component of reflected ultrasonic waves Y directed toward the vibrating surface B111.

[0130] S1 is the projected area S1 of the ultrasonic reflector with respect to the vibrating surface B111, as illustrated in Figures 12 and 13. When S1 is sufficiently small and satisfies Equation 3, the reflected ultrasonic waves Y reflected toward the vibrating surface B111 decrease. This reduces the component of reflected ultrasonic waves Y directed toward the vibrating surface B111.

[0131] S2max is the area of ​​the ultrasonic reflector viewed from a direction parallel to the vibration surface B111, as shown in Figures 10 and 11. When S2max is sufficiently large and S2max and S3 satisfy Equation 4, most of the component of reflected ultrasonic waves Y is directed in directions other than the vibration surface B111. This reduces the component of reflected ultrasonic waves Y directed towards the vibration surface B111.

[0132] The most basic embodiment of the ultrasonic treatment method according to this embodiment has been described above. More preferred embodiments will now be described.

[0133] (Use or omission of ultrasonic reflector B12) In addition to the ultrasonic reflector, a material to be treated may be placed in the liquid B2 as the target to be irradiated with the ultrasonic X. That is, as illustrated in Figures 9 to 13, the ultrasonic reflector present in the liquid B2 may be both the ultrasonic reflector B12 and the material to be treated. In this case, the material to be treated may be either a high acoustic impedance material B4 or a low acoustic impedance material B3.

[0134] On the other hand, as illustrated in Figure 14, the ultrasonic reflector may consist only of the material to be treated, which is irradiated with ultrasonic waves X. That is, the ultrasonic reflector present in the liquid B2 may consist only of the high acoustic impedance material B4. For example, when electroplating a steel plate, the steel plate becomes the high acoustic impedance material B4. By optimizing the positional relationship between this steel plate and the vibrating surface B111, equations 1 to 4 can be satisfied without using the ultrasonic reflector B12. In this case, as illustrated in Figure 14, the ultrasonic reflector B12 may be omitted in the ultrasonic processing apparatus B1.

[0135] (Dissolved oxygen content) In the ultrasonic treatment method according to this embodiment, it is preferable to degas the liquid B2. This removes dissolved gases contained in the liquid B2, increases the propagation efficiency of ultrasonic waves X in the liquid B2, and further enhances the efficiency of the ultrasonic treatment.

[0136] In the ultrasonic treatment method according to this embodiment, the amount of dissolved oxygen is used as an indicator value for the strength of the degassing treatment. The amount of dissolved oxygen in liquid B2 is 6 mg / L. -1 By degassing liquid B2 to this extent, the efficiency of ultrasonic treatment can be further increased.

[0137] The degassing means are not particularly limited. Liquid B2 can be degassed using a conventional vacuum pump for acids or alkalis. Degassing may be performed in tank B13 where ultrasonic treatment is performed. Alternatively, the degassed liquid B2 in the degassing tank may be supplied to tank B13 where ultrasonic treatment is performed.

[0138] (Electroplating) A preferred example of liquid B2 is an electroplating bath. In this case, the material to be treated is electroplated in the process of irradiating with ultrasonic waves X. The material to be treated may be either a low acoustic impedance material B3 or a high acoustic impedance material B4. Ultrasonic waves X with a frequency of 15 kHz to 180 kHz can destroy the diffusion layer that forms near the surface of the material to be treated.

[0139] A diffusion layer is a thin layer of solution that comes into contact with the electrode during an electrolytic process, creating a concentration gradient with the main solution due to mass transfer by diffusion. In electroplating, the material being treated becomes the electrode, and a diffusion layer forms around it. Metal ions become depleted in the diffusion layer. Therefore, the diffusion layer reduces the plating efficiency. Ultrasonic X improves the efficiency of electroplating by destroying the diffusion layer.

[0140] The type of electroplating is not particularly limited. Preferred examples of electroplating baths are Ni-based, Sn-based, and Zn-based baths. The type of material to be treated as the substrate for electroplating is also not particularly limited. A preferred example of the material to be treated is steel. The electroplating conditions are also not particularly limited. Electroplating inevitably produces a diffusion layer. Therefore, the ultrasonic treatment method according to this embodiment can be suitably used in any electroplating treatment in which a diffusion layer may be produced.

[0141] (pickling) Another preferred example of liquid B2 is an acid pickling bath. In this case, the material to be treated is acid-pickled in a step of irradiating with ultrasonic X. More preferably, the material to be treated is electrolytically acid-pickled. The material to be treated may be either a low acoustic impedance material B3 or a high acoustic impedance material B4.

[0142] In pickling, as with electroplating, a concentration gradient is created on the surface of the material being treated, and the cleaning ability decreases due to hydrogen ion deficiency. Ultrasonic X improves the efficiency of pickling by eliminating this concentration gradient. In addition, ultrasonic X also has the effect of physically removing oxide films and smut stains present on the surface of the material being treated, and this effect further improves the efficiency of pickling.

[0143] (Degreasing) Another preferred example of liquid B2 is a degreasing bath. In this case, the material to be treated is degreased in the step of irradiating with ultrasonic X. More preferably, the material to be treated is electrolytically degreased. The material to be treated may be either a low acoustic impedance material B3 or a high acoustic impedance material B4.

[0144] In degreasing, ultrasonic X has the effect of physically removing dirt from the surface of the material being treated, and also the effect of quickly detaching the removed dirt from the surface of the material being treated. Due to these effects, ultrasonic X improves the efficiency of the degreasing process.

[0145] (Output of ultrasonic transducer) Preferably, the output of the ultrasonic transducer that emits ultrasound is 800 W / m 3 This concludes the explanation. This further enhances the effect of ultrasound. In conventional technology, it is believed that excessively increasing the output of the ultrasonic transducer shortens its lifespan. However, in the ultrasonic processing apparatus and ultrasonic processing method according to this embodiment, the adverse effects of ultrasound reflected from the ultrasonic reflector to the ultrasonic transducer are extremely suppressed. Therefore, the output of the ultrasonic transducer can be set to 800 W / m 3 There is no particular problem with doing the above. More preferably, the output of the ultrasonic transducer is 900 W / m3 More than 950W / m 3 Above, or 1000W / m 3 That's all.

[0146] (Number of ultrasonic transducers) In an ultrasonic treatment method, multiple ultrasonic transducers that emit ultrasonic waves may be placed inside a liquid. Alternatively, the ultrasonic treatment apparatus may be equipped with multiple ultrasonic transducers. This can further enhance the effect of the ultrasound.

[0147] (Arrangement of multiple ultrasonic transducers) When multiple ultrasonic transducers are placed inside a liquid, ultrasonic waves emitted from one transducer may irradiate other ultrasonic transducers. For example, each of the multiple ultrasonic transducers may be placed on a different wall surface, separated by an ultrasonic reflector. Such an arrangement of ultrasonic transducers is beneficial from the standpoint of enhancing the ultrasonic treatment effect on the material being treated. On the other hand, the irradiation of other ultrasonic transducers by ultrasonic waves emitted from one transducer may shorten the lifespan of the ultrasonic transducers.

[0148] Therefore, when multiple ultrasonic transducers are installed on each of two opposing wall surfaces separated by an ultrasonic reflector, it is preferable to set the distance between the two closest ultrasonic transducers on one wall surface and the other wall surface to 500 mm or more. This reduces the intensity of the ultrasonic waves irradiated onto the ultrasonic transducers, thereby further extending the lifespan of the ultrasonic transducers.

[0149] Furthermore, when multiple ultrasonic transducers are placed inside a liquid, it is preferable that each of the ultrasonic transducers satisfies Equations 1 to 4. This allows for an even longer lifespan for each ultrasonic transducer. However, even if not all ultrasonic transducers satisfy Equations 1 to 4, if even one ultrasonic transducer satisfies Equations 1 to 4, its lifespan can be extended, thus extending the overall average lifespan of the ultrasonic transducers. Here, average lifespan refers to the sum of the lives of each ultrasonic transducer divided by the number of ultrasonic transducers. This is also true, for example, when multiple ultrasonic transducers are installed on two adjacent walls.

[0150] A wall or water surface facing the vibrating surface of an ultrasonic transducer reflects ultrasound, and the reflected ultrasound is then directed back onto the transducer, creating a situation similar to that described above when two ultrasonic transducers are positioned facing each other. Even in such cases, the lifespan of an ultrasonic transducer can be extended by providing an ultrasonic reflector between the ultrasonic transducer and the wall or water surface in a manner that satisfies equations 1 to 4. For these reasons, walls and water surfaces are excluded from the ultrasonic reflector in this disclosure.

[0151] While embodiments of the present disclosure have been described above, the disclosure is not limited thereto and can be modified as appropriate without departing from the technical idea. Further preferred examples of ultrasonic treatment methods and ultrasonic treatment apparatus according to the present invention will be described below.

[0152] The liquid temperature can be appropriately selected depending on the purpose of the ultrasonic treatment and the type of liquid. For example, if the liquid is a plating bath, the liquid temperature is preferably between 30°C and 70°C. By setting the plating bath temperature to 30°C or higher, the efficiency of the electroplating process can be ensured. Furthermore, by setting the plating bath temperature to 70°C or lower, concentration fluctuations due to evaporation of the plating bath can be suppressed.

[0153] If the liquid is a plating bath, a liquid temperature in the range of 50-60°C is preferable. If the liquid is an acid pickling bath, a liquid temperature in the range of 50-80°C is preferable. If the liquid is a degreasing bath, a liquid temperature in the range of 40-80°C is preferable.

[0154] The number of ultrasonic transducers is not particularly limited. For example, by attaching ultrasonic transducers at regular intervals on both sides of the material to be treated, ultrasonic waves can be applied to the material from two or more directions. Therefore, it becomes easier to apply ultrasonic waves to the entire surface of the material to be treated. On the other hand, if the material to be treated is small, it is possible to use only one ultrasonic transducer. Various numbers of ultrasonic transducers can be selected according to the shape and arrangement of the material to be treated.

[0155] The ultrasonic apparatus may further include a dissolved oxygen measuring means. Using the dissolved oxygen measuring means, the amount of dissolved oxygen in the liquid is measured, and the amount of dissolved oxygen is determined to be 6 mg·L. -1 Dissolved gases in the liquid may be removed as described below. However, a portable dissolved oxygen measuring device may be used to control the amount of dissolved oxygen within the above range. In this case, the ultrasonic device does not need to be equipped with a means for measuring dissolved oxygen.

[0156] The dissolved gases in the liquid mainly consist of nitrogen and oxygen, which are present in the atmosphere. When the liquid is an acid pickling bath or an electroplating bath, it is presumed that the hydrogen formed on the surface of the material being treated hardly dissolves in the liquid. Therefore, the amount of dissolved oxygen can be used as an indicator of the total amount of dissolved gases in the liquid. According to our findings, the amount of dissolved oxygen in the liquid is 6 mg·L. -1 The ultrasound is further amplified by controlling the following: the amount of dissolved oxygen in the liquid to 5 mg / L. -1 The following is also acceptable.

[0157] A larger tank is preferable because it improves the efficiency of the ultrasonic treatment process and increases the number of materials that the ultrasonic treatment device can treat. For example, the capacity of a single tank may be 10L or more, 100L or more, 500L or more, or 1000L or more.

[0158] The ultrasonic transducer may be capable of pulse oscillation, which switches the ultrasonic oscillation on and off at a constant period, or sweep oscillation, which vibrates at a frequency in the range of several kHz. By performing pulse oscillation or sweep oscillation, the state of the ultrasonic waves in the liquid changes, making it less likely for standing waves to form, thereby further enhancing the effect of the ultrasound. [Examples]

[0159] The effects of one aspect of this disclosure will be further illustrated by the examples. However, the conditions in the examples are merely examples of conditions adopted to confirm the feasibility and effectiveness of this disclosure. This disclosure is not limited to these examples of conditions. This disclosure may adopt various conditions as long as they do not depart from the gist of this disclosure and achieve the objectives of this disclosure.

[0160] (A. Examples of electroplating equipment) The plating baths and sulfuric acid aqueous solutions for hydrogen generation used in the examples and comparative examples were prepared as follows. The zinc plating bath was prepared by dissolving zinc sulfate heptahydrate (200 g / L) and ammonium sulfate (30 g / L) in water. The Ni plating bath was prepared by dissolving nickel sulfate hexahydrate (240 g / L), nickel chloride hexahydrate (45 g / L), and boric acid (35 g / L) in water. The chromium plating bath was prepared by dissolving chromic anhydride (140 g / L) and ammonium fluoride (3.5 g / L) in water. The Sn plating bath was prepared by dissolving tin sulfate (40 g / L), p-phenolsulfonic acid (80 g / L), and ethoxylated α-naphtholsulfonic acid (4.0 g / L) in water. The copper plating bath was prepared by dissolving copper sulfate pentahydrate (200 g / L) and sulfuric acid (50 g / L) in water. The sulfuric acid aqueous solution for hydrogen generation was prepared by mixing water and sulfuric acid to achieve a pH of 1.0.

[0161] The corrosion resistance evaluation of the ultrasonic transducers in the examples and comparative examples was carried out as follows.

[0162] Copper wires were connected to the back surface of a SUS316L (5×10mm) piece using conductive paste, and the back surface was insulated by applying silicone resin. The surface was wet-polished with #400 grit sandpaper to serve as the measurement surface. This sample simulates the outer casing of an ultrasonic transducer. After polishing, damping material with the thickness and area ratio (damping material area / test piece area) shown in Table 1 was attached to the back surface of the sample. In the example where damping material was attached to the sample, the situation in which the ultrasonic damping means is arranged in a region within 10 cm of the part of the first ultrasonic transducer that is exposed to the internal space of the electroplating bath was simulated. However, in the examples where "None" is listed in the "Damping Material" column of the table, no damping material was used. In Comparative Examples 1-1, 1-2, and 1-3, a SUS plate was attached to the sample mimicking the exterior material instead of a damping material. In Comparative Example 1-4, a Ti plate was attached to the sample mimicking the exterior material instead of a damping material. In Comparative Example 1-5, an Al plate was attached to the sample mimicking the exterior material instead of a damping material. SUS plates, Ti plates, and Al plates do not function as damping materials.

[0163] The sample thus formed, along with the platinum counter electrode and the saturated silver chloride electrode (SSE), were placed in a plating bath degassed with argon. The substrate was held at a potential of -1200V vs. SSE for 30 seconds to perform pretreatment by cathode reduction, followed by 50mV·min. -1The system was swept up to +1200V vs. SSE at a sweep speed of . The maximum value of the active state among the measurement results was defined as the corrosion rate. In the examples and some comparative examples, ultrasonic waves were irradiated onto the substrate using an ultrasonic oscillator for evaluation of the corrosion resistance of the ultrasonic transducer, electroplating treatment, and evaluation of the bubble removal effect. Depending on the frequency of the ultrasonic waves used, the ultrasonic oscillators used were selected from QUAVA70110 (manufactured by Kaijo Co., Ltd.), S8500 (manufactured by Emerson Japan Co., Ltd.), or USV-1500Z15S (manufactured by Ultrasonic Industry Co., Ltd.). -1 Items below 1.0 mm·y were given an A grade. -1 The above 1.5mm·y -1 Items below 1.5mm·y were given a B grade. -1 The above items were given a C grade. Examples that received an A or B grade were considered pass, and examples that received a C grade were considered failing.

[0164] The pre-plating treatment of the substrates in the examples and comparative examples was carried out as follows: Cold-rolled steel sheets (100 x 100 mm) were degreased by cathodic electrolysis in a 10 wt% sodium hydroxide aqueous solution at 80°C. The current density was 10 A / dm². 2 The electrolysis time was set to 60 seconds. After that, the cold-rolled steel sheet was pickled by immersion in 10 wt% dilute sulfuric acid at 25°C for 30 seconds.

[0165] The plating tests in the examples and comparative examples were carried out as follows. A horizontal circulation cell simulating the actual machine's plate passing speed (50 mpm) was used as the plating cell. The plating bath was heated to 50°C. The substrate that had undergone the above pretreatment was placed in the horizontal circulation cell as the cathode. For nickel plating, a nickel plate was used as the anode. For other plating methods, a platinum-deposited titanium plate was used as the anode. The temperature-adjusted plating bath was then passed through the horizontal circulation cell. The electrolysis conditions were as shown in Table 2.

[0166] In the examples and some comparative examples, ultrasonic waves were irradiated onto the substrate using an ultrasonic oscillator for evaluation of the corrosion resistance of the ultrasonic transducer, electroplating treatment, and bubble removal effect. The ultrasonic oscillators used were QUAVA70110 (manufactured by Kaijo Co., Ltd.), S8500 (manufactured by Nippon Emerson Co., Ltd.), or USV-1500Z15S (manufactured by Ultrasonic Industry Co., Ltd.).

[0167] The ultrasonic intensity was measured at a predetermined ultrasonic measurement location. The predetermined ultrasonic intensity measurement location is: (A) A point 5 cm away from the center of the surface in the width direction of the substrate, or (B) The midpoint between the center of the substrate in the width direction and the opposite electrode, The location is one of the following, and is the closest to the center of the substrate in the width direction. At the ultrasonic intensity measurement location, the sound pressure (kPa) measured using a sound pressure meter (19001D: manufactured by Kaijo Co., Ltd.) was divided by the operating frequency (kHz) to calculate the ultrasonic intensity. In the examples disclosed in Table 1, the ultrasonic intensity was set to 6.0 kPa / kHz in all cases. The ultrasonic intensity in other examples is listed in the table.

[0168] Examples with a uniform film without unevenness were given an A rating. Examples with uneven film were given a B rating. And examples with plating discoloration were given a C rating. Examples rated A or B were considered pass, and examples rated C were considered fail.

[0169] The evaluation of the bubble removal effect by the second ultrasonic method in the examples and comparative examples was carried out as follows.

[0170] Copper wires were connected to the back surface of a 100 x 100 mm SUS304 (SUS304) sheet that had been cleaned with acetone, using conductive paste, and the back surface was insulated by applying silicone resin. The substrate and platinum counter electrode were placed in a sulfuric acid aqueous solution for hydrogen generation, and a current of 1 A / dm² was applied. 2Electrolysis was performed for 10 seconds at the specified current density to generate hydrogen on the substrate surface, and the number of bubbles on the substrate surface after electrolysis was evaluated as the number of remaining bubbles. In the examples and some comparative examples, ultrasonic waves were irradiated onto the substrate using an ultrasonic oscillator for evaluation of the corrosion resistance of the ultrasonic transducer, electroplating treatment, and bubble removal effect evaluation. The ultrasonic oscillator used was one of the following: QUAVA70110 (manufactured by Kaijo Co., Ltd.), S8500 (manufactured by Nippon Emerson Co., Ltd.), or USV-1500Z15S (manufactured by Ultrasonic Industry Co., Ltd.). A rating was given for zero remaining bubbles. A rating was given for 1 to 10 bubbles. A rating was given for 11 or more bubbles. However, the amount of bubbles on the substrate surface does not affect the state of the diffusion layer around the substrate or the lifespan of the ultrasonic transducer. Even in comparative examples judged as C in terms of the amount of bubbles, the technical problems of this disclosure can be solved by appropriately applying the first ultrasonic wave and appropriately using the ultrasonic attenuation means.

[0171] Examples and comparative examples of this disclosure are shown in the table. In the table, "-" means "none".

[0172] [Table 1]

[0173] The experimental results shown in Table 1 illustrate the corrosion-promoting effect of ultrasound and the corrosion-preventing effect of ultrasonic attenuation means. In the comparative examples, no object functioning as an attenuator was attached to the sample. In these comparative examples, the sample was significantly corroded when ultrasound at a frequency of 40 kHz was applied to it. On the other hand, in the examples where FRP or the like, which functions as an attenuator, was attached to the sample, corrosion of the sample was suppressed despite the application of ultrasound at a frequency of 40 kHz.

[0174] [Table 2]

[0175] The experimental results shown in Table 2 demonstrate the diffusion layer formation prevention effect of the first ultrasonic wave.

[0176] In Comparative Examples 2-1 to 2-3, ultrasound was not applied to the substrate. In these comparative examples, plating discoloration occurred.

[0177] In Comparative Examples 2-4 and 2-5, the ultrasonic frequency was inappropriate. Plating discoloration also occurred in these comparative examples.

[0178] In Comparative Example 2-6, the ultrasonic intensity was insufficient. Plating discoloration also occurred in this comparative example.

[0179] In the comparative example where plating discoloration occurred, it is presumed that the formation of the diffusion layer was not suppressed. On the other hand, in the example where ultrasound of appropriate frequency and intensity was applied to the substrate, plating discoloration was suppressed. In these examples, it is presumed that the formation of the diffusion layer was sufficiently suppressed.

[0180] [Table 3]

[0181] The experimental results shown in Table 3 demonstrate the bubble-removing effect of the second type of ultrasound.

[0182] In an example where a second ultrasonic wave of appropriate frequency and intensity was applied to the substrate, bubbles were completely removed.

[0183] On the other hand, in Example 3-2, no air bubbles were removed. As a result, a large number of air bubbles adhered to the substrate.

[0184] In Examples 3-3, 3-11, and 3-12, bubble removal was performed using a second ultrasonic wave. As a result, the number of bubbles in Examples 3-3, 3-11, and 3-12 was less than in Example 3-2. However, in Examples 3-3 and 3-11, the frequency of the second ultrasonic wave was inappropriate, so the bubbles could not be sufficiently removed. In Example 3-12, the intensity of the second ultrasonic wave was inappropriate, so the bubbles could not be sufficiently removed.

[0185] However, the amount of air bubbles on the substrate surface does not affect the state of the diffusion layer around the substrate or the service life of the ultrasonic transducer. Even for a comparative example determined as C with respect to the amount of air bubbles, the technical problem of the present disclosure can be solved by appropriately applying the first ultrasonic waves and appropriately using the ultrasonic attenuation means.

[0186] (B. Examples of sonication apparatus)

[0187] 1×10 7 kg·m -2 ·sec -1 An ultrasonic reflector having the above acoustic impedance was immersed in a liquid. Then, ultrasonic waves were irradiated into the liquid from the vibration surface of one ultrasonic transducer immersed in the liquid. The irradiation conditions are shown in Table 4.

[0188] In the "L1" column of Table 4, the distance between the point farthest from the vibration surface of the ultrasonic reflector and the point closest to the vibration surface of the ultrasonic reflector in the space within the vibration surface when viewed in plan along a direction perpendicular to the vibration surface in the liquid is described. In the "L2" column of Table 4, the distance between the point closest to the vibration surface of the ultrasonic reflector and the vibration surface in the space within the vibration surface when viewed in plan along a direction perpendicular to the vibration surface in the liquid is described. In the "S1" column of Table 4, the projected area of the ultrasonic reflector in the liquid with respect to the vibration surface is described. In the "S2max" column of Table 4, the maximum value of the projected area of the ultrasonic reflector in the liquid with respect to a plane perpendicular to the vibration surface is described. In the "S3" column of Table 4, the area of the vibration surface is described. In the "S1", "S2", "S3" and "S4" columns of Table 4, it is described whether the irradiation conditions of each example satisfy the following formulas 1 to 4 or not. 100mm≦L1……(Formula 1) 10mm≦L2……………(Formula 2) 0<S1≦0.5×S3………(Formula 3) 0.1×S3≦S2max……(Formula 4)

[0189] The conditions not listed in the table are as follows: • Liquid: 5wt% hydrochloric acid aqueous solution • Liquid temperature: 60°C • Material of ultrasonic reflector: Titanium (Acoustic impedance: 2.7 x 10 7 kg·m -2 sec -1 )

[0190] Furthermore, the lifespan of the ultrasonic transducers used in each example was evaluated. The evaluation results are listed in the "Transducer Lifespan Evaluation" column of Table 4. The evaluation method was as follows.

[0191] The lifespan of the ultrasonic transducer was evaluated by using SUS316L, the same material as the transducer's vibrating surface, as the life evaluation material. Copper wires were connected to the back surface of a SUS316L substrate (5 x 10 mm) using conductive paste. Furthermore, silicone resin was applied to the back surface of the substrate to insulate it. The surface of the substrate was wet-polished with #400 grit sandpaper. The surface of the substrate was used as the measurement surface. The polished substrate was attached to the corners of the ultrasonic transducer's vibrating surface.

[0192] The platinum counter electrode and saturated silver chloride electrode (SSE) of the sample formed in this manner were placed in a 5 wt% hydrochloric acid aqueous solution at 60°C, degassed with argon. While irradiating the ultrasonic reflector with ultrasound from an ultrasonic transducer to which the substrate was attached, the substrate was held at a potential of -1200 V vs. SSE for 30 seconds to perform pretreatment by cathode reduction. After that, while continuing to irradiate with ultrasound, 50 mV·min -1 The system was swept up to +1200V vs. SSE at the specified sweep speed.

[0193] The maximum value of the active state among the measurement results was defined as the corrosion rate. In Examples 1-5, ultrasonic waves were irradiated using an ultrasonic oscillator. The ultrasonic oscillator used was a QUAVA70110 model manufactured by Kaijo Co., Ltd. The corrosion rate was 1.5 mm.y -1 Items below 1.5mm were given a good rating. -1 The above items were deemed to be poorly received.

[0194] [Table 4]

[0195] Examples 2 through 4 did not satisfy at least one of equations 1 through 4. On the other hand, Example 1 satisfied all of equations 1 through 4. The lifespan of the ultrasonic transducer in Example 1 was superior to that of the other examples. In other words, the irradiation conditions in Example 1 allowed for a longer lifespan for the ultrasonic transducer. [Explanation of Symbols]

[0196] 1. Electroplating apparatus 11 Electroplating tank 12. First ultrasonic transducer 12S vibration surface 121 Ultrasonic attenuation means 13. Second ultrasonic transducer 14, 141 Substrate support means 15 Opposite 16 Plating bath degassing means 161 Buffer Tank 162 Degassing pump 2 Plating bath 3 Base material 4. Ultrasonic intensity measurement location B1 Ultrasonic Treatment Device B11 Ultrasonic Transducer B111 Vibration surface B12 Ultrasonic reflector B13 tank B2 liquid B3 Materials to be treated with low acoustic impedance B4 Materials to be treated with high acoustic impedance P: The point of the ultrasonic reflector furthest from the vibration plane in the liquid. Q: What is the point of an ultrasonic reflector closest to the vibration surface in a liquid? L1 is the distance between the point furthest from the vibration surface of the ultrasonic reflector and the point closest to the vibration surface of the ultrasonic reflector in the liquid. L2: The distance between the point closest to the vibration surface of the ultrasonic reflector in the liquid and the vibration surface. S1 Projected area of the ultrasonic reflector in liquid relative to the vibration surface S2max Maximum value of the projected area of the ultrasonic reflector in liquid relative to a plane perpendicular to the vibration surface S3 Area of the vibration surface A Plane perpendicular to the vibration surface X Ultrasonic wave Y Reflected ultrasonic wave

Claims

1. An ultrasonic transducer configured to irradiate a liquid with ultrasonic waves from its vibrating surface, A tank configured to hold the aforementioned liquid, An ultrasonic reflector placed in the aforementioned liquid, Equipped with, The aforementioned liquid is acidic or alkaline. The frequency of the ultrasound is between 15 kHz and 180 kHz. The acoustic impedance of the ultrasonic reflector is 1 × 10 ７ kg・m －２ sec －１ That's all. The following equations 1 to 4 are satisfied, 100mm≦L1...(Formula 1) 10mm≦L2…………(Formula 2) 0<S1≦0.5×S3……(Formula 3) 0.1×S3≦S2max……(Formula 4) L1 is the distance measured along the direction perpendicular to the vibration surface in the space within the vibration surface when viewed in plan along the direction perpendicular to the vibration surface in the liquid, between the point on the ultrasonic reflector furthest from the vibration surface and the point on the ultrasonic reflector closest to the vibration surface. L2 is the distance measured along the direction perpendicular to the vibration surface between the point in the ultrasonic reflector closest to the vibration surface and the vibration surface, in the space within the vibration surface when viewed in plan along the direction perpendicular to the vibration surface within the liquid. S1 is the projected area of ​​the ultrasonic reflector in the liquid with respect to the vibrating surface. The S2max is the maximum value of the projected area of ​​the ultrasonic reflector in the liquid with respect to a plane perpendicular to the vibration surface. The S3 is the area of ​​the vibrating surface. Ultrasonic processing device.

2. The output of the ultrasonic transducer is 800 W / m ３ The ultrasonic apparatus according to claim 1, characterized in that it is as described above.

3. The ultrasonic apparatus according to claim 1 or 2, characterized by comprising a plurality of ultrasonic transducers.

4. The plurality of ultrasonic transducers that emit ultrasonic waves are placed inside the liquid, Each of the plurality of ultrasonic transducers is provided on each of the two opposing wall surfaces with the ultrasonic reflector in between. The distance between the two closest ultrasonic transducers on one of the two walls is 500 mm or more. The ultrasonic apparatus according to claim 3.

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