JP2005146396A - Plating method and plating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plating method and a plating device which allow the components to be plated to be subjected to uniform plating by effectively stirring the components to be plated and conducting media. <P>SOLUTION: Predetermined movement is applied to a vessel 14, and while the components 10 to be plated and conducting media 19 in the vessel 14 are repeatedly subjected to forward flowing of flowing to one direction and reverse flowing of flowing to the reverse direction, an electrode 17 for a cathode is energized to perform plating. Further, a stage of temporarily stopping the rotation of the vessel is provided between the forward rotary movement and reverse rotary movement. After the rotary movement of the vessel is temporarily stopped, while the components to be plated and the conducting media are made to flow by the rotary movement of the vessel before the stop, the reverse rotary movement is applied to the vessel. Further, by repeatedly applying movement in which the locus where the vessel is moved is made almost circular to one direction and the direction reverse thereto, the components to be plated and the conducting media are allowed to perform the forward flowing and reverse flowing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a plating method and a plating apparatus. Specifically, for example, an electronic component in which an external electrode is formed on the surface of a ceramic element (chip), such as a chip-type multilayer ceramic capacitor, is plated, and the external The present invention relates to a plating method and a plating apparatus used for forming a plating film on the surface of an electrode.

  One of typical chip-type electronic components is a multilayer ceramic capacitor as shown in FIGS. In this multilayer ceramic capacitor, a plurality of internal electrodes 3 are disposed so as to face each other with the ceramic layer 2 interposed therebetween, and one end side of each of the multilayer ceramic capacitors is alternately drawn out to the end faces of different sides, It has a structure in which a pair of external electrodes 4 are disposed so as to be electrically connected to the internal electrodes 3. The external electrode 4 is formed by applying, drying and baking a conductive paste containing Ag powder as a conductive component, and the surface of the external electrode 4 is Ni-plated to prevent soldering of the Ag electrode. An Sn plating film 6 for improving the film 5 and solderability is formed.

As a method of forming a plating film on the external electrode as in this multilayer ceramic capacitor, for example, there is a method of forming a plating film on the external electrode using a plating apparatus as shown in FIGS. 3 (a) and 3 (b). Are known.
The plating apparatus used in this method includes an eccentric motor 51, an eccentric load 52 for applying an eccentric load to the eccentric motor 51, a motor support frame member 53 that supports the eccentric motor 51, a vibration receiving plate 54, and a vibration receiving plate 54. Vibration generating means 56 including a spring 55 for supporting the metal, a component to be plated 10, and a current-carrying medium (metal ball medium) 19 as a current-carrying medium are accommodated, so that at least a part passes the plating solution. And a rod-like container holding member 58 having a lower end side that holds the container 57 and an upper end side that is connected to the vibration generating means 56. (Not shown) is provided.

  In this plating method, as shown in FIGS. 3 (a) and 3 (b), the components to be plated and the energizing media (energizing media) 19 are agitated so that the components to be plated can be sufficiently agitated. The medium (insulator particles) 20 is added to the container 57, and plating is performed while vibrating the container. (Patent Document 1).

  In this plating apparatus, as described above, the part to be plated 10 and the energizing medium 19 are added to the container, and the agitating medium (insulator particles) 20 is added to the container 57. It becomes possible to effectively stir things.

  However, depending on the size and amount of the insulator particles 20, the insulator particles 20 may flow together with the component to be plated 10 and the current-carrying media 19, or the insulator particles 20 themselves may stay and be covered. In some cases, the flow of the plated component 10 and the current-carrying media 19 may be hindered, and the components to be plated 10 and the components to be plated 10 and the current-carrying media 19 may be attached (attached).

Further, when the flow of the component to be plated 10 and the energizing medium 19 is hindered, the contact state between the component to be plated 10 and the energizing medium 19 varies within the container 57, and the energization to the external electrodes becomes uneven. The film thickness of the plating film varies.
Therefore, the size and amount of the insulator particles 20 must be set as appropriate depending on the size and amount of the part to be plated 10 and the energization medium 19, and there is a problem that the process becomes complicated and the productivity is lowered.

The present invention solves the above-described problems, and can effectively perform stirring of a part to be plated and a medium for energization, and can perform uniform plating on the part to be plated and plating. An object is to provide an apparatus.
Japanese Patent Laid-Open No. 5-70999

In order to achieve the above object, the plating method of the present invention (Claim 1) comprises:
A part to be plated and a current-carrying medium are accommodated in a container equipped with a cathode, and a predetermined movement is given to the container, so that it flows in one direction to the part to be plated and the current-carrying medium in the container. The plated part is plated by energizing the cathode in the container while repeatedly performing forward flow and reverse flow flowing in the reverse direction.

  The plating method according to claim 2 is a method of repeatedly applying to the container to be plated and the energizing medium by repeatedly giving the container a forward rotational motion that rotates in one direction and a reverse rotational motion that rotates in the reverse direction. It is characterized by repeating the forward flow and the reverse flow.

  The plating method according to claim 3 is characterized in that a step of temporarily stopping the rotation of the container is provided between the forward rotational motion and the reverse rotational motion of the container.

  Further, in the plating method according to claim 4, after the rotational movement of the container is temporarily stopped, while the parts to be plated and the energizing media are flowing by the rotational movement of the container before the stop, the container is rotated in the reverse direction. It is characterized by giving exercise.

  Further, in the plating method according to claim 5, the container is supported by the container holding member at a substantially central portion of the bottom wall, and is driven by the driving means connected to the container holding member via the container holding member. A driving force is transmitted to the container, and the container itself does not rotate, and the movement of the container moving in a substantially circular shape is repeatedly applied to the container in one direction and the opposite direction. It is characterized by that.

The plating apparatus of the present invention (Claim 6)
A container for housing the parts to be plated and the energizing medium;
Drive means for repeatedly giving the container a forward rotational motion that rotates in one direction and a reverse rotational motion that rotates in the reverse direction;
And a plating tank containing a plating solution into which the container is immersed.

  The plating apparatus according to claim 7 is configured such that the container is supported by the container holding member at a substantially central portion of the bottom wall, and is driven by the driving means connected to the container holding member via the container holding member. A driving force is transmitted to the container, the container itself does not rotate, and is configured to perform forward rotation and reverse rotation so that the locus of movement of the container becomes a substantially circular shape. Yes.

  In the plating method of the present invention (Claim 1), a predetermined motion is given to the container, and the forward flow flowing in one direction and the reverse flow flowing in the reverse direction are applied to the parts to be plated and the energizing medium in the container. Since the plating is performed by energizing the cathode while repeatedly performing the above, it becomes possible to reliably stir and flow the component to be plated and the medium for energization in the container, It is possible to suppress or prevent the energization media from staying. Therefore, it is possible to prevent the parts to be plated or the adhesion of the parts to be plated and the current-carrying media (sticking) and to keep the contact state between the parts to be plated and the current-carrying media uniform and to be plated. A plated film having a uniform film thickness can be formed on the part.

In the plating method of the present invention, it is possible to perform plating by adding not only the components to be plated and the energization medium but also the agitating medium (insulator particles) to the container. It becomes possible to improve the stirring effect.
Moreover, there is no restriction | limiting in particular in the specific shape and structure of a container, and there is no special restriction | limiting in the arrangement | positioning aspect of the cathode (electrode) with which the container is equipped.

  Further, as in the plating method according to claim 2, by repeatedly giving the container a forward rotational motion that rotates in one direction and a reverse rotational motion that rotates in the reverse direction, When the forward flow and the reverse flow are repeatedly performed, it is possible to more reliably stir the component to be plated and the energization medium in the container, and the present invention can be effectively realized.

  Further, when the step of temporarily stopping the rotation of the container is provided between the forward rotational motion and the reverse rotational motion of the container as in the plating method of claim 3, the stirring efficiency when switching the rotational direction is provided. The present invention can be made more effective by increasing.

  Further, as in the plating method of claim 4, after the rotational movement of the container is temporarily stopped, the parts to be plated and the energizing medium are flowing in the reverse direction by the rotational movement of the container before the stop. The rotational direction is switched before the flow of the parts to be plated and the current-carrying media stops, so that the flow of the parts to be plated and the current-carrying media is interrupted without interruption. Stirring can be performed, and the present invention can be made more effective.

Further, as in the plating method according to claim 5, by the driving means connected to the container holding member that supports the container at the substantially central portion of the bottom wall of the container, the driving force is transmitted to the container through the container holding member, If the container itself is not rotated and the movement of the container moving in a circular shape is repeated in one direction and vice versa, the container is plated without the need for complicated structures. It is possible to cause the component and the energizing medium to efficiently repeat the forward flow and the reverse flow, and the present invention can be more effectively realized.
As the driving means used in the present invention, for example, by combining an eccentric motor, an eccentric load, a spring, etc., eccentric vibration energy is generated, and this eccentric vibration energy is transmitted to the above-described container, and the container is eccentric. By doing so, the container itself is exemplified such as a drive means that does not rotate, but gives a movement such that the locus of movement of the container becomes substantially circular.

  Further, the plating apparatus of the present invention (Claim 6) includes a container that accommodates a part to be plated and a current-carrying medium, a forward rotational motion that rotates the container in one direction, and a reverse rotational motion that rotates in the reverse direction. And a plating tank that contains a plating solution in which the container is immersed, so that the forward flow that flows in one direction and the reverse flow that flows in one direction are reversed. It is possible to reliably carry out the plating method of plating by energizing the cathode while repeatedly performing the reverse flow that flows in the direction, and to perform stable and uniform plating on the parts to be plated Can do.

  Further, as in the plating apparatus according to claim 7, the driving means connected to the container holding member supporting the container at the substantially central portion of the bottom wall of the container transmits the driving force to the container through the container holding member, If the container itself is not rotated and the movement of the container moving in a circular shape is repeated in one direction and vice versa, the container is plated without the need for complicated structures. It is possible to cause the component and the energizing medium to efficiently and repeatedly perform forward flow and reverse flow, and the present invention can be more effectively realized.

Hereinafter, the features of the present invention will be described in more detail with reference to examples of the present invention.
In the following embodiments, as shown in FIGS. 2A and 2B, when a multilayer ceramic capacitor is manufactured, a plurality of internal electrodes 3 are arranged to face each other with the ceramic layer 2 interposed therebetween. In addition, a conductive paste containing Ag as a conductive component is applied to both end portions of a ceramic element (electronic component element) 1 which is drawn to end faces on different sides alternately, and is formed by drying and firing. The case where the Ni plating film 5 formed on the surface of the external electrode 4 is a part to be plated and Sn plating is performed on the Ni plating film 5 to form the Sn plating film 6 will be described as an example.

<Configuration of plating equipment>
FIG. 1 is a diagram showing a configuration of a plating apparatus according to an embodiment of the present invention.
The plating apparatus accommodates at least one drive means 13 for generating eccentric vibration energy, a part to be plated 10, a current-carrying medium (metal ball medium) 19 that functions as a current-carrying medium, and a stirring medium 20. The container 14 is made of a material that allows the plating solution to pass therethrough (in this embodiment, a part of the bottom 16 is a wire mesh), the lower end side holds the container 14, and the upper end side is connected to the driving means 13. The container holding member 15, the electrode 17 for cathodes arrange | positioned at the bottom part 16 of the container 14, the electrode 27 for anodes, and the plating tank 18 which accommodates a plating solution are provided.

  The drive means 13 includes an eccentric motor 11, an eccentric load 21 for applying an eccentric load to the eccentric motor 11, a motor support frame member 22 that supports the eccentric motor 11, a vibration receiving plate 23, and a spring that supports the vibration receiving plate 23. 12 or the like. And this drive means 13 transmits the eccentric vibration energy to the container 14 via the container holding member 15, and does not rotate the container 14 itself. The container 14 is configured to be repeatedly applied in one direction and the opposite direction.

  According to the driving means 13, the eccentric vibration energy by the eccentric motor 11 is transmitted to the container holding member 15 through the vibration receiving plate 23 and further to the container 14. At this time, the eccentric vibration energy applied by the spring 12 supporting the vibration receiving plate 23 is somewhat absorbed and the driving state of the driving means 13 is relaxed to some extent, so that a stable driving force can be applied to the container 14. become.

Further, the container 14 has a shape in which the planar shape is circular and the upper surface side is open. The container holding member 15 is substantially circular in cross-section in the direction orthogonal to the axial direction, and the lower end side is connected to the approximate center of the bottom portion 16 of the container 14 to hold the container 14 and vibrate from the driving means 13 to the container. It is comprised so that the function which transmits may be fulfilled.
The cathode electrode 17 has a substantially circular planar shape, and a plurality of cathode electrodes 17 are arranged in the circumferential direction. Further, a power supply line is connected to the cathode electrode 17 and is connected to an external power source.

<Plating treatment and evaluation>
Using the plating apparatus configured as described above, the following method is used to form a component to be plated (external electrodes 4 are formed at both ends of the ceramic element 1, and Ni plating is applied to the surface of the external electrode 4 as shown in FIG. The ceramic element 10 on which the film 5 was formed was plated, and the Sn plating film 6 was formed on the Ni plating film 5.
The conditions such as the volume of the container, the dimensions of the parts to be plated and the amount charged into the container, the diameter of the energizing medium and the amount charged into the container, the diameter of the stirring medium and the amount charged into the container, and the stirring conditions are as follows: Street.
(1) Container volume: 1300cm ³
(2) Parts to be plated Dimensions: Length L = 1mm, Width W = 0.5mm, Height T = 0.5mm
Input amount: 100,000
(3) Current-carrying media (steel balls)
Diameter: 0.5mm
Input amount: 50cc
(4) Stirring media (silicone rubber coated iron balls)
Diameter: 10mm
Input amount: 50cc
(5) Stirring conditions (Example)
The container rotation direction is switched in the order of forward rotation → stop → reverse rotation and rotated to give forward flow and reverse flow to the parts to be plated, energization media and agitation media. And 120 minutes of Sn plating.
The time for one forward rotation and one reverse rotation (= one energization time) was 5 seconds, 10 seconds, 15 seconds, and 20 seconds, respectively. The one stop time was 1 second.
For comparison, Sn plating was performed with stirring under the following conditions.
(Comparative example 1) (Conventional example)
The rotation direction was continuous rotation only with forward rotation (no stop and reverse rotation), and the cathode was energized continuously, and Sn plating was performed for 100 minutes in all steps.
(Comparative Example 2)
The rotation direction was switched in the order of forward rotation → stop → forward rotation and rotated, and this was repeated, and Sn plating was performed for 120 minutes in all steps.
The time for one forward rotation (= one energization time) was 5 seconds, 10 seconds, 15 seconds, and 20 seconds, respectively. The one stop time was 1 second.

While measuring the film thickness (n = 20) of the Sn plating film formed by plating on said conditions, the CV value was computed by the following formula from the average value of the film thickness of Sn plating film.
CV value (%) = (standard deviation of Sn plating film thickness / Sn plating film thickness average value) × 100
Furthermore, from the amount (X) of the parts to be plated where adhesion (sticking) has occurred and the total amount (Y) of the parts to be plated subjected to plating, the rate of occurrence of adhesion (sticking) is obtained using the following formula. (N = 100,000).
Rate of occurrence of sticking (sticking) (%) = X / Y × 100

  Table 1 shows the thickness of the Sn plating film, the CV value, and the occurrence rate of adhesion (sticking) obtained as described above.

  As shown in Table 1, the rotation direction of the container (that is, the rotation direction of the component to be plated) is switched in the order of forward rotation → stop → reverse rotation in comparison with the case where only the forward rotation is performed (Comparative Example 1). In the embodiment of the present invention in which plating is performed by energizing the cathode in the container while causing the component, the energizing medium and the agitating medium to repeatedly perform forward flow and reverse flow, The incidence of sticking has decreased significantly. In particular, when the time for one forward rotation and one reverse rotation (= one energization time) is 10 seconds or less, the occurrence of adhesion of the parts to be plated (sticking) is not recognized, and the film thickness varies. Significant improvements have been observed in the CV values shown.

Thus, regarding the occurrence rate of adhesion (sticking) of parts to be plated and the film thickness variation of the plating film, good results are obtained in the examples of the present invention by switching the rotation direction ( a) The dispersibility of the parts to be plated in a large number of energizing media is improved, and the probability that the parts to be plated will flow side by side (running in parallel) is reduced. (b) The parts to be plated and the vicinity thereof Increasing the probability of contact with the current-carrying media, (c) Especially when the plating metal deposition time is finely divided (shortening the switching time) in the plating process, and the parts to be plated run side by side In addition, it is considered that the possibility of eutectizing between the parts to be plated is reduced.
In the case of Comparative Example 2 in which the rotation direction is forward rotation → stop → forward rotation, both the occurrence rate of adhesion of parts to be plated and the variation in film thickness are reduced compared to the conventional example of Comparative Example 1. However, the degree is smaller than that in the embodiment of the present invention in which the rotation direction is switched in the order of forward rotation → stop → reverse rotation.
In the above embodiment, the case where the dimension of the part to be plated is a length L = 1 mm, a width W = 0.5 mm, and a height T = 0.5 mm is described as an example, but the length L = 0. It has been confirmed that the same effect can be obtained when plating on a part to be plated having a width of 6 mm, a width W = 0.3 mm, and a height T = 0.3 mm.

As in the case of Example 1, the container rotation direction is switched in the order of forward rotation → stop → reverse rotation to rotate, and the forward flow and the reverse flow are performed on the parts to be plated, the energizing medium and the stirring medium. This was repeated and Sn plating was performed for 120 minutes in all steps.
However, in Example 2, the time of one forward rotation and the reverse rotation (= one energization time) was fixed at 5 seconds, and the stop time was set at 0 seconds, 1 second, 2 seconds, and 3 seconds. The other conditions were the same as those in Example 1 above.
Then, the occurrence rate of adhesion (sticking) of the parts to be plated, the CV value, and the variation in the thickness of the Sn plating film were examined.
The results are shown in Table 2.

  As shown in Table 2, when the stopping time between forward rotation and reverse rotation is 1 second or less, the occurrence rate of adhesion (sticking) of parts to be plated is low, and the variation in plating film thickness is also small. It can be seen that particularly favorable results are obtained.

  This is because when the stop time when switching the rotation direction is 1 second or less, the rotation direction is switched before the flow of the parts to be plated, the energizing medium and the stirring medium stops, so it is stable and reliable. (A) The dispersibility of the parts to be plated in a large number of energizing media is improved, and the probability of the parts to be plated flowing side by side (running in parallel) is reduced. (b) The probability of contact with a current-carrying medium existing in the vicinity of the part to be plated is increased. (c) The plating metal deposition is finely divided in the plating process (time for one normal rotation and one reverse rotation (= 1) This is considered to be because the possibility of eutectizing between the parts to be plated is reduced even when the parts to be plated run side by side.

  In addition, when the stop time between the forward rotation and the reverse rotation is 2 seconds and 3 seconds, the occurrence rate of adhesion (sticking) of the parts to be plated and the variation of the plating film thickness are somewhat increased. Depending on the dimensional conditions of the object to be plated and the plating conditions such as the rotation speed and rotation time, good results may be obtained even if the stop time is increased to some extent. There may be cases where it is selected.

  In the first and second embodiments, the Ni plated film 5 is formed on the surface of the external electrode 4 formed at both ends of the ceramic element 1 as a part to be plated, and Sn plating is performed on the Ni plated film 5. Although the case has been described as an example, there are no particular restrictions on the type of metal to be plated (Ni in Examples 1 and 2) and the type of metal to be plated (Sn in Examples 1 and 2). For example, the present invention can be widely applied to a case where plating is performed under various conditions, for example, when Ni plating is performed on an Ag electrode or solder plating is performed on a Ni plating film.

  In the above embodiment, the stirring medium is put into the container together with the part to be plated and the energizing medium, and the forward flow and the reverse direction flow into the stirring medium together with the part to be plated and the energizing medium in the plating solution. In this case, the plating film is formed on the part to be plated, but it is also possible to perform the plating without adding the stirring medium. Similar effects can be obtained.

  Also, in the above embodiment, the case where the plated part is plated while putting the plated part and the energizing medium into the container having an open upper surface and performing the forward flow and the backward flow is described as an example. However, it is also possible to apply the present invention to barrel plating in which a part to be plated and a current-carrying medium are placed in a rotatable barrel and plating is performed while rotating the barrel. The same effect can be obtained.

  The invention of the present application is not limited to the above embodiment in other respects, and the specific configuration of the driving means, the specific shape of the container, the arrangement of the cathode electrode, and the shape of the container holding member Various applications and modifications can be made within the scope of the invention with respect to the structure and the structure of the plating tank.

  By using the plating apparatus of the present invention, it becomes possible to reliably stir and flow the component to be plated and the energizing medium in the container, and to suppress and prevent the retention of the component to be plated and the energizing medium. It becomes possible. Therefore, it is possible to suppress and prevent the occurrence of bonding (sticking) between the parts to be plated or the parts to be plated and the current-carrying media, while maintaining a uniform contact state between the parts to be plated and the current-carrying media, A plated film having a uniform film thickness can be formed on the component to be plated. Therefore, the present invention can be widely used in the field of manufacturing technology of electronic components having external electrodes provided with plating films.

It is a figure which shows schematic structure of the plating apparatus concerning one Example of this invention. It is a figure which shows the multilayer ceramic capacitor which is a to-be-plated component, Comprising: (a) is sectional drawing, (b) is a perspective view. (a) is a figure which shows the conventional plating apparatus, (b) is the figure which expands and shows the principal part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic element 2 Ceramic layer 3 Internal electrode 4 External electrode 5 Ni plating film 6 Sn plating film 10 Parts to be plated 11 Eccentric motor 12 Spring 13 Drive means 14 Container 15 Container holding member 16 Bottom of container 17 Electrode for cathode 18 Plating tank 19 Media for energization (metal ball media)
20 Stirring medium 21 Eccentric load 22 Motor support frame member 23 Vibration receiving plate 27 Anode electrode

Claims (7)

  A part to be plated and a current-carrying medium are accommodated in a container equipped with a cathode, and a predetermined movement is given to the container, so that it flows in one direction to the part to be plated and the current-carrying medium in the container. A plating method characterized in that plating is performed on a component to be plated by energizing the cathode in the container while repeatedly performing forward flow and reverse flow flowing in the reverse direction.   By repeatedly giving the container a forward rotational motion that rotates in one direction and a reverse rotational motion that rotates in the reverse direction, the forward flow and the reverse flow are repeated in the parts to be plated and the energizing media. The plating method according to claim 1, wherein the plating method is performed.   The plating method according to claim 2, further comprising a step of temporarily stopping the rotation of the container between the forward rotational motion and the reverse rotational motion of the container.   The rotational movement of the container is temporarily stopped, and then the rotational movement in the reverse direction is given to the container while the parts to be plated and the energizing medium are flowing by the rotational movement of the container before the stop. 3. The plating method according to 3.   The container is supported by a container holding member at a substantially central portion of the bottom wall, and a driving force is transmitted to the container via the container holding member by a driving means connected to the container holding member. 5. The structure according to claim 1, wherein the container itself is configured not to rotate but to be repeatedly given to the container in one direction and in the opposite direction so that a trajectory in which the container moves is substantially circular. The plating method according to any one of the above. A container for housing the parts to be plated and the energizing medium;
Drive means for repeatedly giving the container a forward rotational motion that rotates in one direction and a reverse rotational motion that rotates in the reverse direction;
And a plating tank for containing a plating solution into which the container is immersed.   The container is supported by a container holding member at a substantially central portion of the bottom wall, and a driving force is transmitted to the container via the container holding member by a driving means connected to the container holding member. The plating apparatus according to claim 6, wherein the plating apparatus is configured to perform forward rotation and reverse rotation so that the container itself does not rotate and the locus of movement of the container is substantially circular.

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