JP4433927B2 - Plating equipment - Google Patents

Description

  The present invention relates to a plating apparatus, and more particularly to a rotary plating apparatus for plating small electronic components (substances to be plated) such as chip-type multilayer ceramic capacitors.

  As a plating apparatus used for plating small electronic components (to-be-plated objects) such as chip-type multilayer ceramic capacitors, for example, as schematically shown in FIG. There is known a rotary plating apparatus in which an object to be plated 52 and a plating solution 53 are put into a substantially disc-shaped plating processing chamber 51 and plating is performed on the object to be plated 52 while rotating the plating processing chamber 51. (For example, refer to Patent Document 1).

  In this plating apparatus, the peripheral wall of the plating chamber 51 is formed from an annular cathode electrode 54 and a liquid draining portion 55 made of an annular member that allows the plating solution 53 to pass therethrough. Then, the plating solution 53 extracted from the liquid draining portion 55 is received by the container 56, and returns to the inside of the plating processing chamber 51 from the opening 57 disposed in the upper center of the plating processing chamber 51 through the circulation path 58. It is configured as follows. Further, the anode electrode 59 is inserted into the plating processing chamber 51 through the opening 57 at the upper center of the plating processing chamber 51 and immersed in the plating solution 53.

When performing plating on the workpiece 52 using this plating apparatus, the workpiece 52 is put into the plating chamber 51 together with the plating solution 53 and the anode electrode 59 and the cathode electrode 54 are rotated while rotating the plating chamber 51. By energizing during this period, the object 52 is plated.
At this time, the object 52 is efficiently brought into contact with the cathode electrode 54 by the centrifugal force generated by the rotation of the plating chamber 51, and the forward rotation, deceleration (stop), and inversion of the plating chamber 51 are repeated. Thus, the stirring of the workpiece 52 and the contact with the cathode electrode 54, that is, the energization of the workpiece 52 is repeatedly performed, and the plating is applied to the workpiece.

However, when plating is performed using the above conventional plating apparatus, the lines of electric force wrap around the ends of the cathode electrode (for example, the upper end), and the electric lines of force concentrate to increase the current density. Even when plating is performed while repeating normal rotation, deceleration (stop), and reversal of the chamber, there is a problem that the plating film thickness varies.
JP-A-7-118896

  The present invention solves the above-described problems, and forms a plating object in a rotary plating apparatus in which an object to be plated and a plating solution are charged into a plating chamber and plating is performed while rotating the plating chamber. It is an object of the present invention to provide a plating apparatus capable of reducing a variation in film thickness of a plating film to be formed and forming a plating film having a uniform film thickness on an object to be plated.

In order to solve the above problems, the plating apparatus of the present invention (Claim 1)
A plating treatment chamber that is rotatable and has a disk-shaped internal space in which an object to be plated and a plating solution are stored,
An anode electrode disposed so as to be immersed in a plating solution in the plating treatment chamber;
An annular cathode electrode disposed to form a peripheral wall of the plating chamber;
A plating solution extraction portion arranged to form a peripheral wall of the plating treatment chamber and configured to allow the plating solution to be extracted from the periphery of the plating treatment chamber without passing the object to be plated. When,
A circulation path for returning the plating solution extracted from the plating solution extraction unit to the plating treatment chamber;
An area of the cathode electrode, which is disposed in the plating process chamber, does not pass the object to be plated, passes through the plating solution, and forms a peripheral wall of the plating process chamber, and the object to be plated can come into contact with. The upper and lower ends of the cathode electrode are covered, and the object to be plated is guided so that the object to be plated does not contact the upper and lower parts of the cathode electrode, but contacts the area excluding the upper and lower parts of the cathode electrode. And a guide wall.

Moreover, the plating apparatus of claim 2 comprises:
A plating treatment chamber that is rotatable and has a disk-shaped internal space for containing an object to be plated and a plating solution, and a flat bottom surface of the internal space;
An anode electrode disposed so as to be immersed in a plating solution in the plating treatment chamber;
An annular cathode electrode disposed to form a peripheral wall of the plating chamber;
A plating solution extraction portion arranged to form a peripheral wall of the plating treatment chamber and configured to allow the plating solution to be extracted from the periphery of the plating treatment chamber without passing the object to be plated. When,
A circulation path for returning the plating solution extracted from the plating solution extraction unit to the plating treatment chamber;
An area of the cathode electrode, which is disposed in the plating process chamber, does not pass the object to be plated, passes through the plating solution, and forms a peripheral wall of the plating process chamber, and the object to be plated can come into contact with. A guide wall that covers the upper end of the guide electrode and guides the object to be plated so that the object to be plated does not contact the upper end of the cathode electrode but contacts the area excluding the upper end of the cathode electrode;
It is characterized by comprising .

The plating apparatus according to claim 3 is characterized in that the guide wall is made of a mesh-like material.

As described above, the plating apparatus according to the present invention (invention 1) has an annular cathode disposed so that the inner space forms a disk-shaped plating chamber, an anode electrode, and a peripheral wall of the plating chamber. An electrode and a plating solution extraction portion that is disposed so as to form a peripheral wall of the plating processing chamber, and extracts the plating solution from the periphery of the plating processing chamber without passing the object to be plated, and the extracted plating solution Covering the upper end and the lower end of the contact area of the object to be plated of the circulation path that circulates to the plating process chamber and the cathode electrode that forms the inner peripheral wall of the plating process chamber. Since it has a guide wall that guides the object to be plated so that it does not contact the upper end and lower end of the cathode electrode, but contacts the area excluding the upper and lower ends of the cathode electrode, it can evenly energize the object to be plated It is possible to do By reducing the film thickness variation of the plated film formed on an object, it is possible to form a plated film having a uniform thickness on the object to be plated.

  That is, in the plating apparatus of the present invention, the guide wall configured not to pass the object to be plated but to allow the plating solution to pass is used for the plating process in the region of the cathode electrode where the object to be plated can contact. Since the object to be plated is guided in such a way that the object to be plated comes into contact only in an area where the current density is almost uniform without contacting the object to be plated in an area where there is a current density difference that has an adverse effect. An object to be plated is reliably brought into contact with a region having a uniform density, and the current supplied to the object to be plated is made uniform so that uniform plating can be performed on the object to be plated.

  Note that the plating apparatus of the present invention is not limited to simply rotating the plating process chamber (continuously rotating at a constant speed in a fixed direction), but changing the rotation direction of the plating process chamber (ie, inverting it). When rotating continuously, when rotating intermittently or intermittently so that the rotation state and rotation stop state are repeated, one-direction rotation rotating in one direction and other direction rotation rotating in the other direction, The present invention can be widely applied to the case where the plating chamber is rotated in various modes, for example, by repeatedly performing the rotation stop state between them.

  Further, in the plating apparatus according to the first aspect of the present invention, an annular cathode electrode disposed so as to form a peripheral wall of the plating treatment chamber, and a plating treatment chamber disposed so as to form the peripheral wall of the plating treatment chamber. In realizing a configuration including a plating solution extraction part configured to be able to extract the plating solution to the outside without allowing the object to be plated to pass from the periphery of the chamber, for example, on the annular cathode electrode Shows a method of stacking and arranging plating solution extraction portions made of an annular porous material having substantially the same planar shape.

Further, in the case where the inner space of the plating chamber is disk-shaped and the bottom surface is flat as in the plating apparatus of claim 2, when the guide wall is disposed so as to cover the upper end portion of the cathode electrode, It is possible to prevent the object to be plated from coming into contact with the upper end portion of the cathode electrode where the current lines are likely to be concentrated due to the concentration of the force lines, and to uniformly apply the plating to the object to be plated.

The variation in the current density of the cathode electrode depends on the degree of concentration of electric lines of force from the anode electrode to the cathode electrode. In the case of a rotary plating apparatus, the internal space of the plating chamber is usually formed above the upper end of the cathode electrode, and the electric lines of force are parabolic from the anode electrode toward the cathode electrode. Since it proceeds along the path as drawn, the lines of electric force tend to concentrate on the upper end of the cathode electrode. In particular, when the inner space of the plating chamber is disk-shaped and the bottom surface is flat, the lines of electric force are concentrated on the upper end portion of the cathode electrode, and the remarkable concentration is less likely to occur at the lower end portion. Therefore, by arranging the guide wall so as to cover the upper end portion of the cathode electrode, it is possible to prevent the object to be plated from coming into contact with the upper end portion where the current density of the cathode electrode is increased, and to reliably plate the plate. It becomes possible to apply uniform plating to an object.

In addition, if the internal space of the plating chamber exists further below the lower end of the cathode electrode, the lines of electric force also concentrate at the lower end portion of the cathode electrode. Therefore, in such a case, as in claim 1 above, the guide wall, not only the upper portion of the cathode electrode, by disposing as is to cover the lower end portion of the cathode electrode, to be plated It is possible to prevent the object from coming into contact with both the upper end and the lower end where the current density of the cathode electrode is high, and to perform uniform plating on the object to be plated.
However, when the lower end of the cathode is located at the same height as the bottom of the plating chamber (internal space) , there is no particular wraparound of the lines of electric force to the lower end of the cathode electrode, and the current density is increased. Therefore, in such a case, it is usually unnecessary to cover the lower end of the cathode electrode with a guide wall.

Further, when the guide wall is formed from a mesh-like material as in the plating apparatus of claim 3, the current density is substantially uniform in the object to be plated without obstructing the flow of the plating solution in the plating treatment chamber. Therefore, it is possible to perform an efficient and stable plating process.

  Examples of the present invention will be described below to describe the features of the present invention in more detail.

  FIG. 1 is a diagram showing a configuration of a plating apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged view showing a main part of the plating apparatus of FIG. 1, and FIG. 3 is a plating apparatus according to an embodiment of the present invention. FIG. 4 is a perspective view showing a multilayer ceramic capacitor (substance to be plated) to be plated by the plating apparatus according to the example.

  In this embodiment, as shown in FIG. 4, external electrodes 42a and 42b are disposed at both ends of a multilayer ceramic element (electronic component element) 41 having a structure in which a ceramic layer and an internal electrode layer are stacked. A multilayer ceramic capacitor of (T) 0.3 mm, width (W) 0.3 mm, and length (L) 0.6 mm is used as the object to be plated 2, and the surface of the external electrodes 42 a and 42 b is plated with Ni plating or the like. An explanation will be given by taking a plating apparatus used in this case as an example.

  As shown in FIG. 1, the plating apparatus includes a plating processing chamber 1 that is rotatable and has a substantially disk-shaped internal space 1 a in which an object to be plated 2 and a plating solution 3 are accommodated. The plating chamber 1 is disposed so as to be stacked on the base member 11 constituting the bottom, the annular cathode electrode 12 forming the peripheral wall 1b of the plating chamber 1, and the annular cathode electrode 12. An annular plating solution extraction portion 13 made of a porous material that constitutes the peripheral wall 1b of the plating processing chamber 1 together with the electrode 12, and a lid having an opening 15 at the center disposed so as to cover the upper portion of the plating processing chamber 1 A member 16 and an anode electrode 17 inserted into the plating processing chamber 1 from the opening 15 of the lid member 16 and immersed in the plating solution 3 are provided.

  In addition, the annular plating solution extraction part 13 made of a porous material is configured so that the plating solution 3 can be extracted from the periphery of the plating treatment chamber 1 without passing the object 2 to be plated. The plating solution 3 extracted from the plating solution extraction unit 13 is received by the container 19 and is circulated into the plating treatment chamber 1 through the circulation path 18. Further, the plating apparatus of this embodiment is configured such that the plating treatment chamber 1 can perform the plating treatment while repeating rotation and stop at a predetermined pitch.

  Moreover, in the plating apparatus of this embodiment, the lid member 16 has a shape that is inclined so that the center side becomes higher, and the thickness of the plating treatment chamber 1 is configured to increase toward the center. In addition, a recess 11 a is formed on the upper surface side of the base member 11 that constitutes the bottom of the plating processing chamber 1, and an internal space 1 a of the plating processing chamber 1 exists below the lower end of the cathode electrode 12. The upper end portion 12a and the lower end portion 12b of the cathode electrode 12 are configured such that the electric lines of force are concentrated and the current density is increased.

  And in this plating apparatus, the guide wall 20 which guides the to-be-plated object 2 in the plating process chamber 1 so that the to-be-plated object 2 can be contacted only to the area | region where the current density of the cathode electrode 12 is uniform. (Upper guide wall 20a and lower guide wall 20b) are provided.

  That is, in the plating apparatus of this embodiment, as shown in FIGS. 2 and 3, the guide wall 20 covers the upper end portion 12a of the cathode electrode 12 where the current density is increased due to the concentration of the electric lines of force, and the object to be plated. 2 covers the upper guide wall 20a that prevents the cathode electrode 12 from coming into contact with the upper end portion 12a, and the lower end portion 12b of the cathode electrode 12 where the current density increases due to the concentration of the electric lines of force. A lower guide wall 20 b disposed so as not to come into contact with the lower end portion 12 b is disposed in the internal space 1 a of the plating treatment chamber 1. The upper guide wall 20a and the lower guide wall 20b are both made of a mesh-like material (wire net) made of stainless steel.

  According to the plating apparatus of this embodiment configured as described above, the upper end of the cathode electrode 12 where the current density of the cathode electrode 12 is high due to the function of the guide wall 20 (upper guide wall 20a, lower guide wall 20b). Without contacting the part 12a and the lower end part 12b, only the central region 12c having a substantially uniform current density is brought into contact, so that it is possible to make the current to the plating object 2 uniform, and the plating film thickness. It is possible to perform a uniform plating process with no variation.

  In addition, the case where it plated using the plating apparatus of the Example which has the guide wall 20 (upper guide wall 20a, lower guide wall 20b) comprised as mentioned above, and the conventional plating which is not equipped with the guide wall is provided. Table 1 shows the average film thickness of the plating film and the variation in film thickness when plating is performed using the apparatus.

  As shown in Table 1, when plating was performed using a conventional plating apparatus, the variation in the film thickness of the plating film was large. By using the plating apparatus according to the example of the present invention, the film of the plating film was obtained. It was confirmed that the thickness variation can be greatly reduced.

  In the above embodiment, the internal space 1a of the plating chamber 1 exists below the lower end portion 12b of the cathode electrode 12, that is, the concentration of electric lines of force also occurs at the lower end portion 12b of the cathode electrode 12. In consideration of the increase in current density, the lower guide wall 20b is disposed so as to cover the lower end portion 12b of the cathode electrode 12. For example, as shown in FIG. When the lower surface of the inner space is flat and the electric field lines are not concentrated on the lower end portion 12b of the cathode electrode 12, only the upper guide wall 20a is provided and the lower guide wall is provided as shown in FIG. It is also possible to make such a configuration.

  In the above-described embodiment, the plating object chamber 2 and the plating solution 3 are poured into the plating chamber 1 to perform plating. However, in the plating chamber 1, a conductive medium (conductive medium) is further provided. It is also possible to configure so that a more reliable plating treatment can be performed.

  In the above embodiment, the case where the guide wall 20 (upper guide wall 20a, lower guide wall 20b) is formed of a stainless steel mesh material (wire net) has been described as an example. There are no particular restrictions on the configuration or the constituent material, and for example, a plate-like member in which a large number of through holes are formed can be used.

  Moreover, in the said Example, although the case where the plating solution extraction part 13 was formed from the porous material was demonstrated as an example, in this invention, the concrete structure of the plating solution extraction part 13, its component material, etc. There are no special restrictions, and it is possible to use various materials capable of extracting the plating solution 3 to the outside without allowing the workpiece 2 to pass through.

  Further, in the above embodiment, the case where the plating solution extraction portion 13 is disposed so as to be stacked on the cathode electrode 12, that is, the case where the plating solution extraction portion 13 is disposed above the cathode electrode 12 is taken as an example. As described above, the plating solution extraction part 13 may be arranged on the lower side of the cathode electrode 12, and in some cases, the plating solution extraction part 13 is provided on the upper and lower surfaces of the cathode electrode 12. There is no particular restriction on the combination of the cathode electrode 12 and the plating solution extraction portion 13.

In the above embodiment, the case where the multilayer ceramic element is the object to be plated 2 and the surface of the external electrodes 42a and 42b is plated has been described as an example. However, in the present invention, there are special restrictions on the type of the object to be plated. However, the present invention can be widely applied when plating on various objects to be plated.
However, the present invention is particularly meaningful when plating is performed on a small object to be plated having a small size.

  The present invention is not limited to the above-described embodiments with respect to other configurations, and the specific shape and structure of the plating chamber, the specific configuration and shape of the anode electrode, the cathode electrode and the plating solution extraction portion Various applications and modifications are made within the scope of the invention regarding the shape and arrangement, the configuration of the circulation path for returning the plating solution extracted from the plating solution extraction portion to the plating treatment chamber, and the specific route. It is possible.

As described above, the plating apparatus of the present invention does not bring the object to be plated into contact with the region of the cathode electrode where the object to be plated can be contacted, where there is a current density difference that adversely affects the plating process. Since the guide wall for guiding the object to be plated is provided only in a region where the current density is substantially uniform, the object to be plated is reliably provided in the region where the current density of the cathode electrode is uniform. It becomes possible to make contact, uniformize energization to the object to be plated, and perform a stable plating process with no variation in the plating film thickness.
Therefore, the present invention can be widely used in, for example, a manufacturing process of a small electronic component having an external electrode provided with a plating film.

It is sectional drawing which shows the structure of the plating apparatus concerning one Example of this invention. It is a figure which expands and shows the principal part of the plating apparatus concerning one Example of this invention shown in FIG. It is a figure explaining the state of concentration of the electric lines of force to the cathode electrode which comprises the plating apparatus concerning one Example of this invention. It is a perspective view which shows the laminated ceramic element (to-be-plated object) plated by the plating apparatus concerning the Example of this invention. It is a figure which shows the plating apparatus which has the structure where the lower surface side of the interior space of a plating process chamber is flat. It is a figure which shows the modification of the plating apparatus of this invention. It is a figure which shows the conventional plating apparatus.

DESCRIPTION OF SYMBOLS 1 Plating process chamber 1a Internal space 1b Perimeter wall of plating process chamber 2 To-be-plated object 3 Plating solution 11 Base member 11a Indentation 12 Cathode electrode 12a Upper end part of cathode electrode 12b Lower end part of cathode electrode 12c Central area of cathode electrode 13 Extraction of plating solution Part 15 Opening part 16 Lid member 17 Anode electrode 18 Circulating path 19 Container 20 Guide wall 20a Upper guide wall 20b Lower guide wall 41 Multilayer ceramic element (electronic component element)
42a, 42b External electrode

Claims (3)

A plating treatment chamber that is rotatable and has a disk-shaped internal space in which an object to be plated and a plating solution are stored,
An anode electrode disposed so as to be immersed in a plating solution in the plating treatment chamber;
An annular cathode electrode disposed to form a peripheral wall of the plating chamber;
A plating solution extraction portion arranged to form a peripheral wall of the plating treatment chamber and configured to allow the plating solution to be extracted from the periphery of the plating treatment chamber without passing the object to be plated. When,
A circulation path for returning the plating solution extracted from the plating solution extraction unit to the plating treatment chamber;
An area of the cathode electrode, which is disposed in the plating process chamber, does not pass the object to be plated, passes through the plating solution, and forms a peripheral wall of the plating process chamber, and the object to be plated can come into contact with. The upper and lower ends of the cathode electrode are covered, and the object to be plated is guided so that the object to be plated does not contact the upper and lower parts of the cathode electrode, but contacts the area excluding the upper and lower parts of the cathode electrode. And a guide wall. A plating treatment chamber that is rotatable and has a disk-shaped internal space for containing an object to be plated and a plating solution, and a flat bottom surface of the internal space ;
An anode electrode disposed so as to be immersed in a plating solution in the plating treatment chamber;
An annular cathode electrode disposed to form a peripheral wall of the plating chamber;
A plating solution extraction portion arranged to form a peripheral wall of the plating treatment chamber and configured to allow the plating solution to be extracted from the periphery of the plating treatment chamber without passing the object to be plated. When,
A circulation path for returning the plating solution extracted from the plating solution extraction unit to the plating treatment chamber;
An area of the cathode electrode, which is disposed in the plating process chamber, does not pass the object to be plated, passes through the plating solution, and forms a peripheral wall of the plating process chamber, and the object to be plated can come into contact with. A guide wall that covers the upper end of the electrode and guides the object to be plated so that the object to be plated does not contact the upper end of the cathode electrode but contacts a region other than the upper end of the cathode electrode. Features plating equipment. Plating apparatus according to claim 1 or 2, characterized in that said guide wall and is formed from a mesh-like material.

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