Patent Application
20250116029
The present invention relates to plating apparatuses.
For formation of an external electrode of an electronic component, what is called a jet flow-type plating apparatus is widely used. Japanese Patent Laid-Open No. 2021-138999 discloses a jet flow-type plating apparatus.
The plating apparatus disclosed in Japanese Patent Laid-Open No. 2021-138999 includes a plating bath. A metal pipe (a cathode) defining and functioning as the first electrode, a partition wall pipe made of an insulating material, and the second electrode (an anode) are accommodated in the plating bath. The partition wall pipe is provided with a plurality of small holes through which a plating solution passes but through which plating targets, media and the like do not pass.
A metal pipe is disposed inside the partition wall pipe, and a plating forming portion is formed between the inside of the partition wall pipe and the outside of the metal pipe. The plating forming portion is a region (a space) in which plating is performed on a plating target which is an object to be plated. The second electrode is disposed outside the partition wall pipe.
An injection unit having an injection port for injecting the plating solution is provided below the metal pipe. The injection unit serves to generate an upward flow of the plating solution inside the metal pipe. Although not disclosed in the plating apparatus of Japanese Patent Laid-Open No. 2021-138999, a mesh member is typically provided at the injection port of the injection unit to prevent the plating targets and the media from falling into the injection unit when the injection is stopped.
In the plating apparatus disclosed in Japanese Patent Laid-Open No. 2021-138999, a plating solution is accommodated in the plating bath. Then, plating targets, electrically conductive media, and, if required, insulating balls are introduced into the plating bath accommodating the plating solution. Note that the plating solution may be accommodated in the plating bath after the plating targets, the media, and the insulating balls have been introduced into the plating bath. While the plating targets each are plated in the plating forming portion, the media serve to establish an electrical connection between the metal pipe defining and functioning as the first electrode and a plated area (a region in which a base electrode and the like are formed) on the surface of each plating target. The insulating balls serve to enhance the fluidity of each plating target circulating through the plating apparatus.
The plating targets, the media, and the insulating balls are moved upward through the metal pipe with the upward flow of the plating solution inside the metal pipe, the upward flow being generated by the injection from the injection unit, then jetted to the outside from an upper end of the metal pipe, and stirred in the plating solution.
The plating targets, the media, and the insulating balls that have been stirred are then deposited on the upper side of the plating forming portion. At this time, other plating targets, media, and insulating balls have already been deposited inside the plating forming portion. The plating targets, the media, and the insulating balls deposited on the upper side of the plating forming portion gradually fall downward through the plating forming portion. At this time, a current is applied between the metal pipe defining and functioning as the first electrode and the second electrode to form a plated film on the plated area on the surface of each plating target.
The plating targets each having the plated film formed thereon, the media, and the insulating balls are extruded from a lower end of the plating forming portion, and again moved upward through the metal pipe with the upward flow of the plating solution, the upward flow being generated inside the metal pipe, then jetted to the outside from the upper end of the metal pipe, and stirred. The plating targets, the media, and the insulating balls that have been stirred are then deposited on the upper side of the plating forming portion, as before, then gradually fall downward through the plating forming portion, and a plated film is formed on each plating target during the falling.
The plating targets may circulate several times to several thousand times through the plating apparatus until the plated films each have a predetermined thickness and the plating step ends.
Plating on plating targets should satisfy the following (a) and (b):
When the amount of time from the start of plating to the end of plating in one plating step (e.g., one lot) is defined as a “total plating time,” and given that the total plating time is constant, the thicknesses of a plated film formed on each plating target is the same or substantially the same even when the time required for a single pass of each plating target through the plating forming portion and the number of times each plating target passes through the plating forming portion are varied. This is because the thickness of the plated film formed on each plating target depends on the total time in which each plating target passes through the plating forming portion (the time required for a single pass through the plating forming portion×the number of passes). Naturally, when the total plating time is constant, increasing the time required for a single pass of each plating target through the plating forming portion results in a reduced number of times each plating target passes through the plating forming portion, and reducing the time required for a single pass of each plating target through the plating forming portion results in an increased number of times each plating target passes through the plating forming portion.
On the other hand, when the total plating time is constant, the thickness variation in the formed plated film is smaller among a plurality of plating targets when the time required for a single pass of each plating target through the plating forming portion is reduced and the number of times each plating target circulates through the plating apparatus is increased, than when the time required for a single pass of each plating target through the plating forming portion is increased and the number of times each plating target circulates through the plating apparatus is reduced. In other words, since the thickness of the plated film formed (grown) on each plating target with each pass of the plating target through the plating forming portion depends on such conditions as whether the plating target passes close to the metal pipe, passes close to the partition wall pipe, or passes close to halfway between the metal pipe and the partition wall pipe, the thickness variation in the formed plated film can be reduced by increasing and leveling out the number of passes.
Considering the productivity of the plating step, it is preferable that the total plating time is short. In the limited total plating time, a flow rate of the plating solution injected from the injector may be increased in order to increase the number of times each plating target passes through the plating forming portion, and an output of a pump connected to the injector may be increased, for example, in order to increase the flow rate of the plating solution injected from the injector.
However, when the flow rate of the plating solution injected from the injector is increased, defects may occur in the plating targets, such as “cracking” or “chipping” of the plating targets, or “peeling” of the plated films formed on the plating targets. This may be because, when the flow rate of the plating solution injected from the injector is increased, the plating targets are moved upward with too much speed through the metal pipe defining and functioning as the first electrode, and the plating targets jetted to the outside from the upper end of the metal pipe are moved upward to a high position in the plating solution stored in the plating bath and collide with a reflection plate which is called a deflector, or collide with an inner wall of the plating bath or other plating targets when falling downward (settling) from the high position in the plating solution. In other words, the plating targets are discharged along with the media and the insulating balls to the outside from the upper end of the metal pipe in order to stir them. At this time, however, if the plating targets are moved upward with too much momentum to a high position in the stored plating solution, defects may occur in the plating targets.
Therefore, example embodiments of the present invention provide a plating apparatus by which plating targets are not moved upward excessively to a high position in a stored plating solution, and the occurrence of defects in the plating targets is reduced or prevented, even when a flow rate of the plating solution injected from an injector is increased.
A plating apparatus according to an example embodiment of the present invention is able to solve the above-described conventional problems, and includes a plating bath in which a plating solution including plating targets is stored, and an injector provided in the plating bath and that injects the plating solution. The plating targets included in the plating solution are stirred by the plating solution injected from the injection unit. The injector has an inner cylindrical shape including a bottom surface extending in a horizontal direction, an inner wall extending in a height direction from the bottom surface, and an opening defined in an upper end of the inner wall. The opening is a first injection port that injects the plating solution to the plating bath. A mesh portion is provided at the first injection port. A second injection port that injects the plating solution to the injector is provided in the bottom surface. A flow velocity control plate in which a plurality of holes are defined is provided at a point in the height direction of the injector, the flow velocity control plate being in parallel with the bottom surface. The flow velocity control plate preferably includes a central portion and a circumferential portion provided outside the central portion when viewed in a planar direction. The plurality of holes are defined in each of the central portion and the circumferential portion. A cylindrical member including a hollow portion is provided between the flow velocity control plate and the mesh portion at the first injection port.
In a plating apparatus according to an example embodiment of the present invention, the size of each opening area, the total opening area of the plurality of holes per unit area, the number of holes per unit area or the like is adjusted in the holes defined in the central portion and the holes defined in the circumferential portion, so that the speed of the plating solution passing through the central portion can be reduced or prevented to be lower than the speed of the plating solution passing through the circumferential portion.
As a result, in the plating apparatus according to the above-described example embodiment of the present invention, when a metal pipe having a cylindrical shape and including a hollow portion is provided directly above the injector, for example, the speed of the plating solution passing through a central portion of the metal pipe is reduced or prevented. Thus, the plating targets are not moved upward excessively to a high position in the stored plating solution, and the occurrence of defects in the plating targets is reduced or prevented, even when a flow rate of the plating solution injected from the injector is increased. A supplemental explanation is given below.
For example, the speed of the plating solution that passes (e.g., that is moved upward) through the metal pipe defining and functioning as the first electrode is not uniform across the cross section of the metal pipe, but increases toward a central portion of the metal pipe and decreases toward a circumferential portion close to an inner wall of the metal pipe. This is because resistance (frictional resistance) is generated to a flow of the plating solution in the circumferential portion close to the inner wall of the metal pipe, which suppresses the speed of the plating solution.
In addition, when the injector having an inner cylindrical shape is provided on a bottom surface of the plating bath of the plating apparatus, the first injection port is provided on the upper side of the injector, the second injection port that injects the plating solution into the injector is provided in the bottom surface of the injector, and the diameter of the second injection port is smaller than the inner diameter of the metal pipe, the speed of the plating solution may also increase toward the central portion of the metal pipe and decrease toward the circumferential portion close to the inner wall of the metal pipe.
On the other hand, when the flow rate of the plating solution injected from the injector is increased, not all of the plating targets jetted to the outside from the upper end of the metal pipe are moved upward to a high position in the plating solution stored in the plating bath. The plating targets that are moved upward to a high position in the plating solution stored in the plating bath are considered to be mainly plating targets that have passed (that have been moved upward) all at once through the central portion of the metal pipe where the speed of the plating solution is high.
In a plating apparatus according to an example embodiment of the present invention, the speed of the plating solution passing through the central portion of the flow velocity control plate is reduced or prevented. When a metal pipe having a cylindrical shape and including a hollow portion is provided directly above the injector, for example, the speed of the plating solution passing through the metal pipe is reduced or prevented in the central portion of the metal pipe. Thus, the plating targets are not moved upward excessively to a high position in the stored plating solution, and the occurrence of defects in the plating targets is reduced or prevented, even when the flow rate of the plating solution injected from the injector is increased.
The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.
Hereinafter, example embodiments of the present invention will be described with reference to the accompanying drawings.
Each example embodiment of the present invention is not limited to contents of the specifically depicted example embodiment. Contents described in different example embodiments can also be implemented in combination, and the contents implemented in that case are also encompassed in the present invention. The accompanying drawings serve to help understanding of the specification and may schematically be drawn. A ratio of the dimensions of a drawn component or components may not be equal to a ratio of the dimensions described in the specification. Components described in the specification may be omitted in the drawings or may be drawn in reduced number.
Plating apparatus 100 includes a plating bath 1. An upper side of plating bath 1 is open. Plating bath 1 accommodates a mixture 19 of a plating solution, plating targets, media, and insulating balls, which will be described later. The insulating balls can be omitted if not required.
Plating apparatus 100 includes a cylindrical metal pipe 2 provided inside plating bath 1. Metal pipe 2 includes a hollow portion 2a. Metal pipe 2 defining and functioning as the first electrode is a cathode electrode in the present example embodiment. In the present example embodiment, metal pipe 2 has a cylindrical shape. Metal pipe 2 may alternatively have a polygonal cylindrical shape. Metal pipe 2 may be made of any material and can be made using various metals. Metal pipe 2 may have any dimensions such as an outer diameter, an inner diameter, and a length, each of which can be set as appropriate.
In the present example embodiment, two rod-shaped electrically-conductive support portions 2b are preferably integrally provided with metal pipe 2 at an upper portion of metal pipe 2. The number of support portions 2b is not limited to two and may be any number.
Plating apparatus 100 includes a partition wall pipe 3 made of an electrically insulating material and provided inside plating bath 1. Partition wall pipe 3 includes a hollow portion 3a. In the present example embodiment, partition wall pipe 3 has a cylindrical shape. Partition wall pipe 3 may have a polygonal cylindrical shape. Partition wall pipe 3 is provided with a plurality of small holes 3b through which the plating solution passes but through which the plating targets, the media, and the insulating balls do not pass. When a current is applied between metal pipe 2 defining and functioning as the first electrode and a second electrode 5, holes 3b allow the current to pass through the plating solution. Partition wall pipe 3 may be made of any material and can be made, for example, using various resins. Partition wall pipe 3 may have any dimensions such as an outer diameter, an inner diameter, and a length, each of which can be set as appropriate.
The inner diameter of partition wall pipe 3 is larger than the outer diameter of metal pipe 2. Metal pipe 2 is located inside hollow portion 3a of partition wall pipe 3. A plating forming portion 4 is provided between the inside of partition wall pipe 3 and the outside of metal pipe 2. Plating forming portion 4 is preferably a region (e.g., a space) in which the plating targets each are plated. In
The plating targets, the media, and the insulating balls are deposited inside plating forming portion 4 and gradually fall downward. At some point during this falling, the surface of each plating target is plated.
Plating apparatus 100 preferably includes second electrode 5 provided inside plating bath 1. In the present example embodiment, second electrode 5 is an anode electrode. In the present example embodiment, second electrode 5 is made of metal having a cylindrical shape. Second electrode 5 is disposed outside partition wall pipe 3. Second electrode 5 may be made of any material and can be made using various metals.
As shown in
Plating apparatus 100 includes injector 6 below metal pipe 2. Injector 6 serves to generate an upward flow of the plating solution inside metal pipe 2. In the present example embodiment, injector 6 has an inner cylindrical shape including a bottom surface extending in a horizontal direction, an inner wall extending in a height direction from the bottom surface, and an opening defined in an upper end of the inner wall. In the present example embodiment, the inner cylindrical shape of injector 6 is an inner circular cylindrical shape. Note that the inner cylindrical shape of injector 6 is not limited to the inner circular cylindrical shape and may be other shapes. Injector 6 may have any dimensions such as an inner diameter and a depth, each of which can be set as appropriate. The dimension of the inner diameter of injector 6 is preferably the same as the dimension of the inner diameter of metal pipe 2, but may be different without any disadvantage.
A first injection port 6a is defined in the opening defined in the upper end of injector 6. First injection port 6a may have any shape and dimensions, and has a circular shape with a diameter of 28 mm in the present example embodiment.
A second injection port 6b is preferably provided in the bottom surface of injector 6. The plating solution is injected into injector 6 from second injection port 6b. The plating solution is injected into plating bath 1 from first injection port 6a. In the present example embodiment, the opening area of second injection port 6b is smaller than the opening area of first injection port 6a.
When comparing the inner diameter of metal pipe 2 with the diameter of second injection port 6b, the diameter of second injection port 6b is smaller than the inner diameter of metal pipe 2. This also causes an increase in the speed of the plating solution in a central portion of metal pipe 2. Thus, measures need to be taken for suppressing the speed of the plating solution in the central portion of metal pipe 2.
A mesh portion 7 is provided at first injection port 6a of injector 6. Mesh portion 7 is provided to prevent the plating targets, the media, and the insulating balls from falling into injector 6 when the injection from injector 6 is stopped. In the present example embodiment, since first injection port 6a of injector 6 has a circular or substantially circular shape, mesh portion 7 also has a circular shape when viewed in the planar direction.
In the present example embodiment, mesh portion 7 is preferably entirely made of one layer of mesh having a mesh opening of, for example, about 900 μm. The mesh portion may include a mesh central portion 7a and a mesh circumferential portion 7b provided outside mesh central portion 7a, and mesh central portion 7a may include a plurality of (e.g., two) layers of mesh and mesh circumferential portion 7b may include one layer of mesh, like a mesh portion 7′ shown in
The “mesh opening” of a mesh means a dimension between adjacent lines (excluding the line size) in a mesh formed by vertical lines and horizontal lines intersecting each other. The mesh opening may be referred to as an opening (OP) or an opening dimension. The mesh opening generally refers to a mesh opening of one layer of mesh, but may refer, when a plurality of meshes are stacked, to an overall mesh opening of the plurality of meshes in the application document of the present invention. When comparing the mesh opening of one layer of mesh with the mesh opening of two stacked layers of that mesh (or the mesh opening of that mesh and another mesh that are stacked on each other), the latter is smaller (e.g., finer) than the former.
In mesh portions 7′ and 7″, the mesh opening of mesh central portion 7a is smaller than the mesh opening of mesh circumferential portion 7b. In mesh portions 7′ and 7″, therefore, the speed of the plating solution passing through mesh central portion 7a is reduced or prevented to be lower than the speed of the plating solution passing through mesh circumferential portion 7b.
The mesh forming mesh portions 7, 7′ and 7″ may be made of any material and can be made, for example, using nylon. When a plurality of layers of mesh are stacked for use, the meshes may be joined together by an adhesive, for example, or may be overlaid on each other and then secured at their edges.
In plating apparatus 100, flow velocity control plate 8 is provided at a point in the height direction of injector 6, the flow velocity control plate being in parallel or substantially in parallel with the bottom surface of injector 6. As can be seen particularly from
Flow velocity control plate 8 may have any shape and dimensions, and preferably has a disc shape with, for example, a diameter of about 28 mm in the present example embodiment. Central portion 8a may also have any shape and dimensions, and preferably has a circular or substantially circular shape with, for example, a diameter of about 20 mm in the present example embodiment.
Flow velocity control plate 8 may be made of any material and can be made, for example, using vinyl chloride.
A plurality of holes 9 (9a and 9b) are defined in flow velocity control plate 8 to extend through both main surfaces of flow velocity control plate 8. Holes 9 (9a and 9b) may have any shape, and each have a circular shape when viewed in the planar direction in the present example embodiment. When holes 9 (9a and 9b) each have a circular or substantially circular shape, they can be easily formed by, for example, laser beam irradiation or by drilling with a drill.
In the present example embodiment, the opening area of each hole 9a defined in central portion 8a is smaller than the opening area of each hole 9b defined in circumferential portion 8b. Specifically, the diameter of each hole 9a defined in central portion 8a is, for example, preferably about 1.2 mm, and the diameter of each hole 9b defined in circumferential portion 8b is, for example, preferably about 3.0 mm.
In the present example embodiment, a pattern shape of central portion 8a in which holes 9a are provided and a pattern shape of circumferential portion 8b in which holes 9b are provided are preferably similar in shape. More specifically, the plurality of holes 9a each having a diameter of, for example, about 1.2 mm are defined in a matrix (in a grid) with a prescribed spacing therebetween in central portion 8a. Then, the diameter of each hole is, for example, increased to about 3.0 mm, including the spacing between the holes, while the shape is maintained. The increased spacing between the holes and the increased diameter of each hole are used to form holes 9b in circumferential portion 8b. In the present example embodiment, therefore, the total opening area of the plurality of holes 9a per unit area in central portion 8a is equal to the total opening area of the plurality of holes 9b per unit area in circumferential portion 8b.
The total opening area of the plurality of holes 9a per unit area is not necessarily required to be equal or substantially equal to the total opening area of the plurality of holes 9b per unit area in circumferential portion 8b. To more effectively suppress the speed of the plating solution passing through central portion 8a, it is preferable that the total opening area of the plurality of holes 9a per unit area in central portion 8a is smaller than the total opening area of the plurality of holes 9b per unit area in circumferential portion 8b. Conversely, if the total opening area of the plurality of holes 9a per unit area in central portion 8a is larger than the total opening area of the plurality of holes 9b per unit area in circumferential portion 8b, the speed of the plating solution passing through central portion 8a can still be reduced or prevented as compared to the speed of the plating solution passing through circumferential portion 8b, if the opening area of each hole 9a defined in central portion 8a is sufficiently smaller than the opening area of each hole 9b defined in circumferential portion 8b.
In flow velocity control plate 8 of plating apparatus 100 in the present example embodiment, since the opening area of each hole 9a defined in central portion 8a is smaller than the opening area of each hole 9b defined in circumferential portion 8b, resistance acting on the plating solution passing through central portion 8a is higher than resistance acting on the plating solution passing through circumferential portion 8b. Thus, the speed of the plating solution passing through central portion 8a is reduced or prevented. In other words, when a fluid such as a plating solution passes through a hole, resistance acting on the fluid increases as the opening area of the hole decreases, and resistance acting on the fluid decreases as the opening area of the hole increases. By maximizing the opening area of each hole 9b defined in circumferential portion 8b and minimizing the opening area of each hole 9a defined in central portion 8a, the speed of the plating solution passing through central portion 8a can be reduced or prevented as compared to the speed of the plating solution passing through circumferential portion 8b.
While the total opening area of the plurality of holes 9a per unit area in central portion 8a is preferably equal or substantially equal to the total opening area of the plurality of holes 9b per unit area in circumferential portion 8b in flow velocity control plate 8 of plating apparatus 100 shown in
In modified flow velocity control plate 8′ of
As has already been described, it is not necessary that the total opening area of the plurality of holes 9a per unit area in central portion 8a is identical to or smaller than the total opening area of the plurality of holes 9b per unit area in circumferential portion 8b. If the total opening area of the plurality of holes 9a per unit area in central portion 8a is larger than the total opening area of the plurality of holes 9b per unit area in circumferential portion 8b, the speed of the plating solution passing through central portion 8a can still be reduced or prevented as compared to the speed of the plating solution passing through circumferential portion 8b, if the opening area of each hole 9a defined in central portion 8a is sufficiently smaller than the opening area of each hole 9b defined in circumferential portion 8b.
In plating apparatus 100, cylindrical portion 10 including a hollow portion is provided between flow velocity control plate 8 and mesh portion 7 at first injection port 6a. Cylindrical portion 10 may have any shape and dimensions, which are preferably the same as the shape and dimensions of central portion 8a of flow velocity control plate 8, but may be different without any disadvantage. In the present example embodiment, cylindrical portion 10 preferably has a cylindrical shape with an inner diameter of about 20 mm. In the present example embodiment, as shown in
Cylindrical portion 10 is provided to maintain the difference between the speed (slow) of the plating solution that has passed through central portion 8a and the speed (fast) of the plating solution that has passed through circumferential portion 8b, the difference being generated by flow velocity control plate 8, to first injection port 6a of injector 6 where mesh portion 7 is provided. In other words, without cylindrical portion 10, the slow plating solution that has passed through central portion 8a and the fast plating solution that has passed through circumferential portion 8b are mixed at some point, which reduces the effect of making the speed of the plating solution injected from a central portion of first injection port 6a slower than the speed of the plating solution injected from a circumferential portion of first injection port 6a at first injection port 6a of injector 6 where mesh portion 7 is provided.
It is preferable that a lower end of cylindrical portion 10 is in contact with flow velocity control plate 8. However, there may be a gap between the lower end of cylindrical portion 10 and flow velocity control plate 8 without any disadvantage. It is preferable that an upper end of cylindrical portion 10 is in contact with mesh portion 7. However, there may be a gap between the upper end of cylindrical portion 10 and mesh portion 7 without any disadvantage.
Plating apparatus 100 preferably includes a circulation line 11 defined by a pipe. Circulation line 11 includes one end connected to a liquid suction port 12 provided in plating bath 1 and another end connected to second injection port 6b of injector 6. A pump 13 and a filter 14 are provided at points in circulation line 11. When pump 13 is driven, circulation line 11 suctions the plating solution from liquid suction port 12 and injects the plating solution from second injection port 6b.
Plating apparatus 100 includes a mixer 15 below metal pipe 2 and partition wall pipe 3 and above injector 6. Mixer 15 is a region in which the plating solution injected from first injection port 6a of injector 6 is mixed with the plating targets, the media, and the insulating balls that have fallen downward through plating forming portion 4. In the present example embodiment, mixer 15 is made of an insulating material and has an upper surface having a recess defined in the shape of an inverted truncated cone. The inverted truncated cone means a truncated cone shaped such that an upper bottom surface is larger than a lower bottom surface. Note that the recess may have any shape and may have a bowl shape or the like in place of the shape of an inverted truncated cone.
First injection port 6a of injector 6 is located in a bottom surface of mixer 15. As described above, mesh portion 7 is provided at first injection port 6a of injector 6. By the provision of mesh portion 7 at first injection port 6a, the plating targets, the media, and the insulating balls do not fall into injector 6 when the injection from injector 6 is stopped.
Plating apparatus 100 preferably includes a guide portion 16 above metal pipe 2 and partition wall pipe 3. In guide portion 16, the plating targets, the media, and the insulating balls that have been moved upward with the upward flow of the plating solution and jetted (e.g., discharged) from an upper opening of hollow portion 2a of metal pipe 2 are stirred and subsequently guided to plating forming portion 4. In this case, the upward flow of the plating solution has been defined inside hollow portion 2a of metal pipe 2 by the injection from first injection port 6a of injector 6. Guide portion 16 is preferably made of an electrically insulating material and has a shape of an inverted truncated cone in the present example embodiment. Guide portion 16 includes a bottom surface through which an upper end of metal pipe 2 protrudes. An upper end of hollow portion 2a of metal pipe 2 is opened in the bottom surface of guide portion 16. The bottom surface of guide portion 16 is connected to partition wall pipe 3.
Plating apparatus 100 preferably includes an insulative reflection plate 17 above the opening of plating bath 1. Reflection plate 17 may be referred to as a deflector. Reflection plate 17 acts to suppress scattering of the plating solution. Further, reflection plate 17 has a lower surface to which support portion 2b of metal pipe 2 is attached. A cylindrical suppression plate 17a is preferably provided on the lower surface of reflection plate 17. Suppression plate 17a is located inside guide portion 16. While the plating solution may overflow to the outside beyond an upper edge of guide portion 16, suppression plate 17a allows only the plating solution to overflow from guide portion 16 but prevents overflowing of the plating targets, the media, and the insulating balls.
Plating apparatus 100 includes a power supply 18. Power supply 18 preferably includes one line connected to support portion 2b of metal pipe 2 defining and functioning as the first electrode, and another line connected to second electrode 5. Power supply 18 applies a current between metal pipe 2 defining and functioning as the first electrode and second electrode 5.
In plating apparatus 100 having the above-described structure according to the first example embodiment, the speed of the plating solution injected from first injection port 6a of injector 6 is controlled (e.g., adjusted) by the provision of flow velocity control plate 8 and cylindrical portion 10. Specifically, the speed of the plating solution that passes through central portion 8a of flow velocity control plate 8, further passes through the inside of cylindrical portion 10, and is injected from first injection port 6a of injector 6 is reduced or prevented (e.g., reduced) to be lower than the speed of the plating solution that passes through circumferential portion 8b of flow velocity control plate 8, further passes through the outside of cylindrical portion 10, and is injected from first injection port 6a of injector 6.
As described above, the speed of the plating solution that is moved upward through metal pipe 2 defining and functioning as the first electrode increases toward the central portion of metal pipe 2 and decreases toward the circumferential portion close to the inner wall of metal pipe 2. In addition, when the flow rate of the plating solution injected from injector 6 is increased, the plating targets that are moved upward to a high position in the plating solution stored in the plating bath among the plating targets jetted to the outside from the upper end of metal pipe 2 are considered to be mainly plating targets that have been moved upward all at once through the central portion of metal pipe 2 where the speed of the plating solution is high.
In plating apparatus 100, the speed of the plating solution that passes through the inside of cylindrical portion 10 and is injected from first injection port 6a of injector 6 is slower than the speed of the plating solution that passes through the outside of cylindrical portion 10 and is injected from first injection port 6a of injector 6, so that the speed of the plating solution that is moved upward through the central portion of metal pipe 2 is reduced or prevented. More specifically, in plating apparatus 100, when the amount of the plating solution injected from injector 6 is constant, the speed of the plating solution that is moved upward through the central portion of metal pipe 2 can be reduced as compared to when flow velocity control plate 8 and cylindrical portion 10 are not provided.
In plating apparatus 100, therefore, the plating targets are not moved upward excessively to a high position in the stored plating solution, even when the amount of the plating solution injected from injector 6 is increased, the time required for a single pass of each plating target through plating forming portion 4 is reduced, and the number of times each plating target circulates through the plating apparatus is increased. Thus, in plating apparatus 100, the occurrence of defects in the plating targets such as cracking, chipping, or peeling of the plated films due to the upward movement of the plating targets to a high position in the stored plating solution is reduced or prevented.
The following describes an example of a plating step performed using plating apparatus 100.
First, a desired plating solution is introduced into plating bath 1.
Then, the prescribed number of plating targets, media, and insulating balls are introduced into guide portion 16 inside plating bath 1. In this case, each of the plating targets, the media, and the insulating balls has a desired shape and desired dimensions. The introduction of the plating solution may be exchanged in order with the introduction of the plating targets, the media, and the insulating balls. The introduced plating targets, media, and insulating balls are deposited inside plating forming portion 4.
Then, pump 13 is driven to inject the plating solution from first injection port 6a of injector 6. As a result, an upward flow of the plating solution is generated inside metal pipe 2. Then, the plating targets, the media, and the insulating balls deposited inside plating forming portion 4 are partially taken out from the lower end of plating forming portion 4, introduced into mixer 15, mixed with the injected plating solution, and then moved upward with the upward flow through metal pipe 2.
The plating targets, the media, and the insulating balls that have been moved upward through metal pipe 2 are jetted to the outside from the upper end of metal pipe 2 and then stirred.
The plating targets, the media, and the insulating balls that have been stirred are deposited on upper sides of other plating targets, media, and insulating balls that have already been deposited in plating forming portion 4.
As the plating targets, the media, and the insulating balls that have been deposited in plating forming portion 4 are partially taken out from the lower end of plating forming portion 4 and introduced into mixer 15, the plating targets, the media, and the insulating balls that have been newly deposited gradually fall downward. In this way, the plating targets, the media, and the insulating balls circulate through plating apparatus 100.
Then, power supply 18 is driven to apply a current between metal pipe 2 defining and functioning as the first electrode and second electrode 5. As a result, plating on each plating target is started in plating forming portion 4.
When a prescribed time period has elapsed and a plated film having a desired thickness is formed on each plating target, power supply 18 is stopped to stop plating on each plating target. Then, pump 13 is stopped to stop circulation of the plating targets, the media, and the insulating balls through plating apparatus 100.
Then, the plating targets, the media, and the insulating balls are taken out from plating bath 1, the plating targets are then sorted out, and the plating step ends.
In order to determine the effectiveness of the present invention, the following experiment was performed. Specifically, Example 1 and Example 2 were performed using above-described plating apparatus 100, and Comparative Example 1 was performed using a plating apparatus other than the plating apparatus of the present invention. In this experiment, a plating apparatus including flow velocity control plate 8 and cylindrical portion 10 was deemed to belong to plating apparatus 100, even when the diameter of central portion 8a of flow velocity control plate 8 had a different dimension or the inner diameter of cylindrical portion 10 had a different dimension.
Plating apparatus 100 used in Example 1 and plating apparatus 100 used in Example 2 were different from each other in the dimension of the diameter of central portion 8a of flow velocity control plate 8, and the dimension of the inner diameter of cylindrical portion 10. Unlike plating apparatus 100, the plating apparatus used in Comparative Example 1 other than the plating apparatus of the present invention did not include flow velocity control plate 8 and cylindrical portion 10.
Plating apparatus 100 of Example 1, plating apparatus 100 of Example 2, and the plating apparatus of Comparative Example 1 had the same configuration except for flow velocity control plate 8 and cylindrical portion 10. For example, plating forming portion 4 had a length of, for example, about 220 mm in each case.
First, Example 1 was performed. In plating apparatus 100 used in Example 1, flow velocity control plate 8 had a circular or substantially circular shape with a diameter of, for example, about 28 mm, and central portion 8a of flow velocity control plate 8 had a circular shape with a diameter of, for example, about 15 mm. In plating apparatus 100 used in Example 1, cylindrical portion 10 had a cylindrical shape with an inner diameter of 15 mm.
In plating apparatus 100 used in Example 1, the plurality of holes 9a each having a diameter of, for example, about 1.2 mm were defined in central portion 8a of flow velocity control plate 8, and the plurality of holes 9b each having a diameter of, for example, about 3.0 mm were defined in circumferential portion 8b of flow velocity control plate 8. A pattern shape of central portion 8a in which holes 9a were formed and a pattern shape of circumferential portion 8b in which holes 9b were formed were similar in shape. In other words, the pattern shape of circumferential portion 8b in which holes 9b were formed was obtained by enlarging the pattern shape of central portion 8a in which holes 9a were formed to increase the diameter of each hole to, for example, about 3.0 mm, including the spacing between the holes.
A plating solution was accommodated in plating bath 1 of plating apparatus 100.
Plating targets, media, and insulating balls were introduced into guide portion 16 inside plating bath 1 of plating apparatus 100. The total amount of blending of the plating targets, the media, and the insulating balls was, for example, about 1720 cc. The blending ratios were set at, for example, about 1376 cc (about 80% by volume) for the plating targets, about 86 cc (about 5% by volume) for the media, and about 258 cc (about 15% by volume) for the insulating balls.
Pump 13 was driven at low output to inject the plating solution from first injection port 6a of injector 6, to cause the plating targets, the media, and the insulating balls to circulate through mixer 15, hollow portion 2a of metal pipe 2, guide portion 16, plating forming portion 4, and mixer 15 in this order. The output of pump 13 was gradually increased to increase a speed of circulation of the plating targets, the media, and the insulating balls. Then, when the plating targets that were moved upward to a relatively high position (e.g., jetted upward) in the stored plating solution among the plating targets that were discharged from the upper end of hollow portion 2a of metal pipe 2 reached a prescribed height, the increasing of the output of pump 13 was stopped to keep the output of pump 13 constant. Specifically, when the plating targets that were moved upward to a relatively high position in the stored plating solution among the plating targets that were discharged from the upper end of hollow portion 2a of metal pipe 2 reached a position corresponding to half the height between the upper end of metal pipe 2 and a fluid level of the plating solution accommodated in plating bath 1, the output of pump 13 was maintained constant.
Then, power supply 18 was driven to apply a current between metal pipe 2 defining and functioning as the first electrode and second electrode 5, and plating on each plating target was started in plating forming portion 4.
In this state, the amount of the plating solution injected from first injection port 6a of injector 6 (e.g., the flow rate of the plating solution) was measured. Additionally, in this state, the time required for a single pass of each plating target through plating forming portion 4 was measured.
In Example 1, the amount of the plating solution injected from first injection port 6a of injector 6 was, for example, about 39 L/min. The time required for a single pass of each plating target through plating forming portion 4 was, for example, about 10.5 seconds.
Next, Example 2 was performed. In plating apparatus 100 used in Example 2, flow velocity control plate 8 had a circular or substantially circular shape with a diameter of, for example, about 28 mm, central portion 8a of flow velocity control plate 8 had a circular or substantially circular shape with a diameter of, for example, about 20 mm, and cylindrical portion 10 had a cylindrical shape with an inner diameter of, for example, about 20 mm.
As in Example 1, in plating apparatus 100 used in Example 2 as well, the plurality of holes 9a each having a diameter of, for example, about 1.2 mm were defined in central portion 8a of flow velocity control plate 8, and the plurality of holes 9b each having a diameter of, for example, about 3.0 mm were defined in circumferential portion 8b of flow velocity control plate 8. As in Example 1, the pattern shape of central portion 8a in which holes 9a were formed and the pattern shape of circumferential portion 8b in which holes 9b were formed were similar in shape.
In Example 2 as well, under the same conditions as those of Example 1, a plating solution was accommodated in plating bath 1 of plating apparatus 100.
In Example 2 as well, under the same conditions as those of Example 1, plating targets, media, and insulating balls were introduced into guide portion 16 inside plating bath 1 of plating apparatus 100.
In Example 2 as well, under the same conditions as those of Example 1, pump 13 was driven at low output, and the output of pump 13 was gradually increased. Then, when the plating targets that were moved upward to a relatively high position in the stored plating solution among the plating targets that were discharged from the upper end of hollow portion 2a of metal pipe 2 reached the position corresponding to half the height between the upper end of metal pipe 2 and the fluid level of the plating solution accommodated in plating bath 1, the output of pump 13 was maintained constant. Then, power supply 18 was driven to apply a current between metal pipe 2 defining and functioning as the first electrode and second electrode 5, and plating on each plating target was started in plating forming portion 4.
In Example 2 as well, in this state, the amount of the plating solution injected from first injection port 6a of injector 6 (the flow rate of the plating solution) was measured. Additionally, in this state, the time required for a single pass of each plating target through plating forming portion 4 was measured.
In Example 2, the amount of the plating solution injected from first injection port 6a of injector 6 was, for example, about 40 L/min. The time required for a single pass of each plating target through plating forming portion 4 was, for example, about 6.1 seconds.
Next, Comparative Example 1 was performed. As described above, the plating apparatus used in Comparative Example 1 did not include flow velocity control plate 8 and cylindrical portion 10. The configuration of the plating apparatus used in Comparative Example 1 was otherwise the same as that of plating apparatus 100.
In Comparative Example 1 as well, under the same conditions as those of Examples 1 and 2, a plating solution was accommodated in plating bath 1 of plating apparatus 100.
In Comparative Example 1 as well, under the same conditions as those of Examples 1 and 2, plating targets, media, and insulating balls were introduced into guide portion 16 inside plating bath 1 of plating apparatus 100.
In Comparative Example 1 as well, under the same conditions as those of Examples 1 and 2, pump 13 was driven at low output, and the output of pump 13 was gradually increased. Then, when the plating targets that were moved upward to a relatively high position in the stored plating solution among the plating targets that were discharged from the upper end of hollow portion 2a of metal pipe 2 reached the position corresponding to half the height between the upper end of metal pipe 2 and the fluid level of the plating solution accommodated in plating bath 1, the output of pump 13 was maintained constant. Then, power supply 18 was driven to apply a current between metal pipe 2 defining and functioning as the first electrode and second electrode 5, and plating on each plating target was started in plating forming portion 4.
In Comparative Example 1 as well, in this state, the amount of the plating solution injected from first injection port 6a of injector 6 (e.g., the flow rate of the plating solution) was measured. Additionally, in this state, the time required for a single pass of each plating target through plating forming portion 4 was measured.
In Comparative Example 1, the amount of the plating solution injected from first injection port 6a of injector 6 was, for example, about 34 L/min. The time required for a single pass of each plating target through plating forming portion 4 was, for example, about 16.7 seconds.
Table 1 shows details and experimental results of Example 1, Example 2, and Comparative Example 1.
As can be seen from Table 1, under the condition that the output of pump 13 was kept constant (maintained) when the plating targets that were moved upward to a relatively high position in the stored plating solution among the plating targets that were discharged from the upper end of hollow portion 2a of metal pipe 2 reached the position corresponding to half the height between the upper end of metal pipe 2 and the fluid level of the plating solution accommodated in plating bath 1, the flow rate of the plating solution was higher and the time required for a single pass of each plating target through plating forming portion 4 was shorter in both Example 1 and Example 2 than in Comparative Example 1.
When comparing Example 1 with Example 2, the flow rate of the plating solution was higher and the time required for a single pass of each plating target through plating forming portion 4 was shorter in Example 2 in which the diameter of central portion 8a of flow velocity control plate 8 and the inner diameter of cylindrical portion 10 had larger dimensions, than in Example 1 in which the diameter of central portion 8a of flow velocity control plate 8 and the inner diameter of cylindrical portion 10 had smaller dimensions. When implementing the present invention, it is considered that employing a relative large dimension of the diameter of central portion 8a of flow velocity control plate 8 and a relative large dimension of the inner diameter of cylindrical portion 10, where the speed of the plating solution is reduced or prevented, can increase the flow rate of the plating solution, and can reduce the time required for a single pass of each plating target through plating forming portion 4.
In view of the foregoing, according to the present invention, it was found that the thickness variation in the formed plated film could be reduced or prevented by increasing the flow rate of the plating solution and increasing the number of times each plating target circulates through the plating apparatus, while suppressing the occurrence of defects in the plating targets.
Plating apparatus 200 according to the second example embodiment is preferably obtained by partially modifying the configuration of plating apparatus 100 according to the first example embodiment described above. The modifications are described below.
In flow velocity control plate 8 of plating apparatus 100 according to the first example embodiment, the opening area of each hole 9a defined in central portion 8a is smaller than the opening area of each hole 9b defined in circumferential portion 8b. In flow velocity control plate 28 of plating apparatus 200 according to the second example embodiment, on the other hand, the opening area of each hole 29a defined in a central portion 28a is identical to the opening area of each hole 29b defined in a circumferential portion 28b. In flow velocity control plate 28 of plating apparatus 200, however, the number of holes 29a per unit area defined in central portion 28a is smaller than the number of holes 29b per unit area defined in circumferential portion 28b. The configuration of the plating apparatus is otherwise the same as that of plating apparatus 100.
In flow velocity control plate 28 of plating apparatus 200 according to the second example embodiment, the total opening area of the plurality of holes 29a per unit area defined in central portion 28a is smaller than the total opening area of the plurality of holes 29b per unit area defined in circumferential portion 28b.
In plating apparatus 200 according to the second example embodiment as well, the speed of the plating solution that passes through central portion 28a of flow velocity control plate 28, further passes through the inside of cylindrical portion 10, and is injected from first injection port 6a of injector 6 is reduced or prevented (e.g., reduced) to be lower than the speed of the plating solution that passes through circumferential portion 28b of flow velocity control plate 28, further passes through the outside of cylindrical portion 10, and is injected from first injection port 6a of injector 6. Therefore, in plating apparatus 200 as well, defects are unlikely to occur in the plating targets, even when the amount of the plating solution injected from injector 6 is increased, the time required for a single pass of each plating target through plating forming portion 4 is reduced, and the number of times each plating target circulates through the plating apparatus is increased, for the purpose of suppressing the thickness variation in the plated film.
As above, the plating apparatuses according to the first example embodiment and the second example embodiment have been described. However, the invention of the subject application is not limited to the above-described details, but can be variously modified in accordance with the gist of the present invention.
For example, while mesh portion 7 is entirely defined by one layer of mesh in the above-described example embodiments, mesh portion 7′ may be made of mesh central portion 7a and mesh circumferential portion 7b provided outside mesh central portion 7a, and mesh central portion 7a may be made of a plurality of layers of mesh and mesh circumferential portion 7b may be formed of one layer of mesh, as shown in
The plating apparatus according to one example embodiment of the present invention is as described above.
In this plating apparatus, it is also preferable that an opening area of each of the holes defined in the central portion is smaller than an opening area of each of the holes defined in the circumferential portion. In this case, resistance acting on the plating solution passing through each hole defined in the central portion is higher than resistance acting on the plating solution passing through each hole defined in the circumferential portion. Thus, the speed of the plating solution passing through the central portion can be reduced or prevented as compared to the speed of the plating solution passing through the circumferential portion. In this case, it is also preferable that a total opening area of the plurality of holes per unit area defined in the central portion is identical to or smaller than a total opening area of the plurality of holes per unit area defined in the circumferential portion. In this case, the speed of the plating solution passing through the central portion can be further reduced or prevented.
it is also preferable that an opening area of each of the holes defined in the central portion is identical to an opening area of each of the holes defined in the circumferential portion, but a number of the holes per unit area defined in the central portion is smaller than a number of the holes per unit area defined in the circumferential portion. In this case, the speed of the plating solution passing through the central portion can be reduced or prevented as compared to the speed of the plating solution passing through the circumferential portion.
it is also preferable that a total opening area of the plurality of holes per unit area defined in the central portion is smaller than a total opening area of the plurality of holes per unit area defined in the circumferential portion. In this case, the speed of the plating solution passing through the central portion can be reduced or prevented as compared to the speed of the plating solution passing through the circumferential portion.
In these plating apparatuses, it is also preferable that, when the flow velocity control plate and the cylindrical portion are viewed in the planar direction, the central portion of the flow velocity control plate is located inside the cylindrical portion, and the circumferential portion of the flow velocity control plate is disposed outside the cylindrical portion. In this case, the difference between the speed of the plating solution that has passed through the central portion and the speed of the plating solution that has passed through the circumferential portion, the difference being generated by the flow velocity control plate, can be maintained to the first injection port of the injector.
It is also preferable that, when the flow velocity control plate is viewed in the planar direction, the holes defined in the central portion and the holes defined in the circumferential portion each have a circular shape. In this case, the holes can be easily defined in the flow velocity control plate.
It is also preferable that the mesh portion includes a mesh central portion and a mesh circumferential portion provided outside the mesh central portion when viewed in the planar direction, and a mesh opening of the mesh central portion is smaller than a mesh opening of the mesh circumferential portion. In this case, in the mesh portion as well, the speed of the plating solution passing through the mesh central portion can be reduced or prevented to be lower than the speed of the plating solution passing through the mesh circumferential portion. In this case, it is also preferable that the mesh portion in the mesh circumferential portion is made of one layer of mesh, and the mesh portion in the mesh central portion is made of a plurality of layers of mesh.
It is also preferable that a metal pipe having a cylindrical shape and including a hollow portion is provided directly above the injector. In this case, the speed of the plating solution that is moved upward through the metal pipe can be controlled, and in particular, the high speed of the plating solution flow that is moved upward through a central portion inside the metal pipe can be reduced or prevented (e.g., reduced).
It is also preferable that the plating apparatus includes: a partition wall pipe made of an insulating material, the partition wall pipe having a cylindrical shape and including a hollow portion, the partition wall pipe being provided with a plurality of holes through which the plating solution passes but through which the plating targets do not pass; and a second electrode. The metal pipe serves as a first electrode. The metal pipe, the partition wall pipe, and the second electrode are each accommodated in the plating bath. The metal pipe is located inside the hollow portion of the partition wall pipe, and a plating forming portion is formed between an inside of the partition wall pipe and an outside of the metal pipe. The second electrode is located outside the partition wall pipe. The injector is provided below the metal pipe. The plating targets are moved upward through the hollow portion of the metal pipe with an upward flow of the plating solution injected from the injector. The plating targets are discharged to an outside from an upper end of the hollow portion of the metal pipe and stirred in the plating solution. The plating targets subsequently fall downward through the plating forming portion. While the plating targets fall downward, the plating targets each are plated by application of a current between the metal pipe defining and functioning as the first electrode and the second electrode. In this case, the speed of the plating solution that is moved upward through the metal pipe can be controlled, and in particular, the high speed of the plating solution flow that is moved upward through a central portion inside the metal pipe can be reduced or prevented (e.g., reduced). The first electrode is a cathode electrode, for example, and the second electrode is an anode electrode, for example.
While example embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-154280 | Sep 2022 | JP | national |
This application is a Continuation application of PCT Application No. PCT/JP2023/028661, filed on Aug. 5, 2023, and claims the benefit of priority to Japanese Patent Application No. 2022-154280, filed on Sep. 27, 2022. The entire contents of each application are hereby incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2023/028661 | Aug 2023 | WO |
| Child | 18985144 | US |
