JP4760461B2 - Plating apparatus and plating method - Google Patents

Description

  The present invention relates to a plating apparatus and a plating method performed using the same, and in particular, a plating apparatus and a plating suitable for performing plating on a small object to be plated such as a chip-shaped electronic component. It is about the method.

  For example, nickel or the like is often plated on the surface of the external electrode of the chip-shaped electronic component. Thus, when trying to perform the above plating on a small object to be plated such as a chip-like electronic component having an external electrode, the rotating barrel method is often applied. The rotating barrel method is a plating method using a barrel as a mesh-like container, and is intended to achieve desired plating while rotating a barrel containing a large number of small objects to be plated in a plating solution.

  The rotating barrel method described above is often applied when electroplating is performed, but Japanese Patent Application Laid-Open No. 5-171451 (Patent Document 1) describes that the rotating barrel method is applied to electroless plating. Yes. However, when the rotating barrel method is applied to electroless plating, the following problems may be encountered.

  In electroless plating, one of the important factors for realizing a good plating process is a bath load. The bath load is represented by the following formula.

Bath load = area to be plated / plating solution amount When the bath load increases, the change in the plating solution composition due to the plating reaction, etc., increases. Or bath decomposition occurs.

  As described in Patent Document 1, when the rotating barrel method is applied to electroless plating, the objects to be plated are overlapped in the barrel, so that the bath load is locally increased. In particular, the smaller the object to be plated, the more easily the objects to be agglomerated, so the bath load tends to increase locally. As a result, abnormal deposition or bath decomposition of the plating film as described above may occur.

  On the other hand, as a method for making it difficult to cause aggregation of the objects to be plated, a method of enlarging a barrel can be considered. However, when the barrel is enlarged, the amount of plating solution necessary for plating increases, resulting in an increase in cost.

  As a solution to the above problems, for example, a plating apparatus described in Japanese Patent Laid-Open No. 6-116795 (Patent Document 2) is noted. The plating apparatus described in Patent Document 2 includes a spiral conveyance path provided in the plating tank, and conveys the conveyance path by applying vibration to the conveyance path attached to the lower part of the plating tank. The object to be plated is transported upward along the path. According to such a plating apparatus, since a plurality of objects to be plated move in a state where the conveyance paths are aligned, it is possible to make it difficult to cause the objects to be aggregated.

However, according to the plating apparatus described in Patent Document 2, since the vibration apparatus is required, the entire apparatus becomes large, and a problem that the object to be plated is easily damaged can be encountered.
JP-A-5-171451 JP-A-6-116795

  Accordingly, an object of the present invention is to provide a plating apparatus and a plating method implemented using the plating apparatus that can solve the above-described problems.

  The plating apparatus according to the present invention is characterized by having the following configuration in order to solve the technical problem described above.

That is, the plating apparatus according to the present invention forms a bottom surface for receiving a plating bath in which a plating solution and an object to be plated are accommodated, and an object to be plated that is submerged in the plating solution at the bottom of the plating bath. A bottom surface forming member and a bottom surface forming member for transporting an object to be plated in a plating tank, and forming a transport path extending spirally around an axis line in the vertical direction. Rotation driving means for rotating the path forming member in directions opposite to each other around the axis line directed in the vertical direction.

  Then, according to the rotation drive by the rotation driving means, the conveyance path forming member scoops the object to be plated located on the bottom surface forming member on the conveyance path at the lower end thereof, and then moves the object to be plated upward along the conveyance path. After being conveyed to the bottom, at the upper end portion, the object to be plated that has passed through the end of the conveying path is dropped toward the bottom surface forming member.

  In the plating apparatus according to the present invention, it is preferable that the bottom surface formed by the bottom surface forming member is inclined so that the objects to be plated are gathered according to gravity near the lower end portion of the transport path forming member.

In the first preferred embodiment, the plating apparatus according to the present invention further includes a cylindrical drum that is disposed in the plating tank and has the axis line in the vertical direction as the central axis line. In this case, it is preferable that the conveyance path forming member is provided by a fin-like member provided on the inner peripheral surface of the drum so as to protrude like a shelf . Also, the drum, it preferably forms a plurality of pores that allow the passage of the plating solution.

In a second preferred embodiment, the plating apparatus according to the present invention further includes a columnar shaft that is disposed in the plating tank and has the axis line in the vertical direction as the central axis. In this case, it is preferable that the conveyance path forming member is provided by a fin-like member provided on the outer peripheral surface of the shaft so as to protrude like a shelf .

  The plating apparatus according to the present invention is advantageously applied when plating is performed on chip-shaped electronic components. That is, the object to be plated is a chip-shaped electronic component that includes an external electrode whose surface is scheduled to be plated. The plating apparatus according to the present invention is used for plating external electrodes.

  The present invention is also directed to a plating method including a step of performing electroless plating on an object to be plated using an electroless plating solution as a plating solution while using the above-described plating apparatus.

  The plating method according to the present invention is advantageously applied to a case where a chip-like electronic component having an external electrode whose surface is scheduled to be plated is an object to be plated and electroless plating is performed on the external electrode. .

According to the present invention, in the plating solution, the object to be plated is repeatedly conveyed from the lower end portion to the upper end portion of the conveying path extending in a spiral shape. Therefore, the objects to be plated are aggregated in the plating solution. Without being dispersed. As a result, when performing electroless plating, it can suppress that a bath load becomes large locally, and it can make it difficult to produce abnormal deposition of a plating film and bath decomposition. Further, since the power for transporting the object to be plated along the transport path as described above is obtained by the rotation of the bottom surface forming member and the transport path forming member in the opposite directions , as in the conventional case. Does not require a vibration device. Therefore, the whole apparatus does not increase in size, and the problem that the object to be plated is easily damaged can be avoided.

  Therefore, when the plating apparatus according to the present invention is applied to a process of performing electroless plating on an object to be plated using an electroless plating solution as a plating solution, more specifically, When the chip-like electronic component having an external electrode that is scheduled to be plated on the surface is to be plated, and applied to the process of applying electroless plating to the external electrode, the effects as described above are more prominent. Demonstrated.

  In the plating apparatus according to the present invention, when the bottom surface formed by the bottom surface forming member is inclined and the objects to be plated are gathered according to gravity near the lower end portion of the transport path forming member, Introduction of the object to be plated can be performed more smoothly, and as a result, the object to be plated can be moved more smoothly in the plating tank.

  In the plating apparatus according to the present invention, when the conveyance path forming member is provided by a fin-like member provided so as to protrude like a shelf on the inner peripheral surface of the cylindrical drum, the drum is driven to rotate. If it does, desired rotation can be given to a conveyance path formation member. In this embodiment, when the drum has many pores that allow the plating solution to pass therethrough, it is possible to ensure a smooth flow of the plating solution in the plating tank.

  In the plating apparatus according to the present invention, when the conveyance path forming member is provided by a fin-like member provided so as to protrude like a shelf on the outer peripheral surface of the columnar shaft, the conveyance is performed by rotationally driving the shaft. A desired rotation can be given to the path forming member.

  FIG. 1 is a plan view showing a chip-shaped electronic component 1 as an example of an object to be plated to which a plating apparatus and a plating method according to the present invention can be advantageously applied. The chip-like electronic component 1 to which the present invention can be applied is not limited in its function, but constitutes, for example, a multilayer ceramic capacitor.

  The chip-shaped electronic component 1 includes a chip-shaped component main body 2, and an external electrode 3 is formed on each end of the component main body 2. The external electrode 3 is shown with a part of the right side broken away. As shown in the broken part of the external electrode 3, the external electrode 3 is formed of, for example, a base film 4 made of a thick film by baking a conductive paste and a plating film 5 formed by plating the base film 4. It has. The plating apparatus and the plating method according to the present invention are used, for example, for forming the above-described plating film 5 by electroless plating.

  FIG. 2 is a front view schematically showing the plating apparatus 11 according to the first embodiment of the present invention. In FIG. The plating apparatus 11 is shown in a sectional view in order to clarify its internal structure.

  The plating apparatus 11 includes a plating tank 12. An electroless plating solution 13 and an object to be plated 14 are accommodated in the plating tank 12. The object to be plated 14 is a chip-like electronic component 1 including the external electrode 3 whose surface is scheduled to be plated as described with reference to FIG. In the previous stage, the plating film 5 is not formed.

  The plating apparatus 11 also includes a bottom surface forming member 16 that forms a bottom surface 15 for receiving an object 14 to be plated that is sinking in the plating solution 13 at the bottom of the plating tank 12. The bottom surface forming member 16 is disposed on the bottom surface of the plating tank 12.

  Further, a conveyance path forming member 19 is disposed in the plating tank 12 for conveying the workpiece 14 and forms a conveyance path 18 that spirally extends around an axis 17 that faces in the vertical direction. ing.

Plating apparatus 11 also comprises a rotary drive means for rotating the bottom forming member 16 and the conveyance path forming member 19 described above in opposite directions about axis 17 facing the vertical direction.

  The bottom surface forming member 16 is rotationally driven in the direction of the arrow 22 by being connected to a rotational drive shaft 21 that is rotated by a rotational drive means 20 configured with, for example, a motor.

  On the other hand, the conveyance path forming member 19 is driven to rotate by the following configuration. The plating apparatus 11 is disposed in the plating tank 12 and further includes a cylindrical drum 23 having an axis 17 facing in the vertical direction as a central axis. The conveyance path forming member 19 is provided by a fin-like member 24 provided on the inner peripheral surface of the drum 23 so as to protrude like a shelf. The drum 23 is rotationally driven in the direction of the arrow 28 by being connected via an arm 27 to a rotational drive shaft 26 that is rotationally driven by a rotational drive means 25 configured with a motor, for example. The conveyance path forming member 19 is also rotated in the same direction.

  Although not shown in FIG. 2, the drum 23 preferably has a large number of pores that allow the plating solution 13 to pass therethrough. The pores have a diameter of, for example, about 0.2 mm, although depending on the size of the workpiece 14.

  The following operations are brought about by the rotation of the bottom surface forming member 16 and the conveyance path forming member 19 as described above. FIG. 3 is for explaining such an operation, and shows the lower end portion of the transport path forming member 19 and the vicinity thereof. In FIG. 3, elements corresponding to those shown in FIG.

  As shown in FIG. 3, the bottom surface forming member 16 rotates in the direction of the arrow 22 while the transport path forming member 19 rotates in the direction of the arrow 28 according to the rotational driving by the rotational driving means 20 and 25 described above. As a result of such operation, as shown in FIGS. 3 (1) to 3 (1) in sequence, the conveyance path forming member 19 places the workpiece 14 positioned on the bottom surface forming member 16 at the lower end portion of the conveyance path 18. Then, the workpiece 14 is transported upward along the transport path 18. At this time, since the objects to be plated 14 are successively introduced into the lower end portion of the conveyance path forming member 19 in accordance with the rotational drive described above, the objects to be plated 14 after scooping on the conveyance path 18 are in a ball-thrust state. In this way, it is transported upward along the transport path 18. As shown in FIG. 2, the object to be plated 14 conveyed upward along the conveyance path 18 passes through the terminal end of the conveyance path 18 at the upper end portion of the conveyance path forming member 19, thereby forming the bottom surface forming member. Drop toward 16 Then, the above operation is repeated for each of the objects to be plated 14.

  As shown in FIG. 2, the bottom surface 15 formed by the bottom surface forming member 16 is inclined. By this inclination, the objects to be plated 14 gather near the lower end of the transport path forming member 19 according to gravity, and the introduction of the object to be plated 14 to the lower end of the transport path forming member 19 described above proceeds more smoothly. To be.

  As described above, the electroless plating solution 13 is brought into contact with the object to be plated 14 while the object to be plated 14 is conveyed along the cyclical path passing through the conveying path 18 in the plating tank 12, and is desired. Electroless plating is applied. That is, in the chip-shaped electronic component 1 as the object to be plated 14, the plating film 5 is formed on the surface of the external electrode 3.

  As Experimental Example 1 for confirming the effect of the present invention, electroless nickel plating was performed using the plating apparatus 1 according to the first embodiment described above.

  In this Experimental Example 1, as the electroless plating solution 13, nickel sulfate 0.2 mol / liter, hypophosphorous acid 0.4 mol / liter, lactic acid 0.4 mol / liter, and propionic acid 0.05 mol / liter were used. A composition having a pH adjusted to 4.5 and a bath temperature of 90 ° C. was used.

Moreover, as the to-be-plated thing 14, it was the chip-shaped electronic component 1 shown in FIG. 1, Comprising: The planar dimension has used the 0.6 mm x 0.3 mm. Then, 200,000 chip-shaped electronic components 1 were put into the drum 23 in the plating tank 12. At this time, the bath load was about 10 dm ² / liter.

  Under such conditions, the bottom surface forming member 16 and the drum 23 were rotated in opposite directions at 50 rpm, respectively, and the surface of the external electrode 3 of the chip-shaped electronic component 1 was subjected to electroless nickel plating.

  After completion of the plating process, 100 chip-shaped electronic components 1 were subjected to appearance inspection by sampling. As a result, no abnormal deposition of the plating film occurred in any of the chip-shaped electronic components 1.

  FIG. 4 is a front view schematically showing a plating apparatus 31 according to the second embodiment of the present invention. As in the case of the plating apparatus 11 shown in FIG. 2 described above, in FIG. 4, the plating apparatus 31 is shown in a sectional view in order to clarify its internal structure.

  The plating apparatus 31 includes a plating tank 32. In the plating tank 32, an electroless plating solution 33 and an object to be plated 34 such as the chip-shaped electronic component 1 shown in FIG. The plating apparatus 31 also includes a bottom surface forming member 36 that forms a bottom surface 35 for receiving an object 34 to be plated in the plating solution 33 at the bottom of the plating tank 32. The bottom surface forming member 36 is disposed on the bottom surface of the plating tank 32.

  In the plating tank 32, a conveyance path forming member 39 is arranged for conveying the workpiece 34 and forms a conveyance path 38 that spirally extends around an axis 37 that faces in the vertical direction. ing.

Plating apparatus 31 also comprises a rotary drive means for rotating the bottom forming member 36 and the conveyance path forming member 39 described above in opposite directions about axis 37 facing the vertical direction.

  That is, the bottom surface forming member 36 is rotationally driven in the direction of the arrow 42 by being connected to a rotational drive shaft 41 that is rotated by, for example, a rotational drive means 40 configured with a motor.

  On the other hand, in the plating tank 32, a columnar shaft 43 having a central axis that is the axis 37 facing in the up and down direction is disposed, and the conveyance path forming member 39 projects in a shelf shape on the outer peripheral surface of the shaft 43. Is provided by a fin-like member 44 provided to do so. The shaft 43 is rotationally driven by, for example, a rotational driving means 45 configured with a motor, so that the conveyance path forming member 39 is rotationally driven in the direction of the arrow 46.

  The plating apparatus 31 is further disposed in the plating tank 32, and further includes a cylindrical drum 47 having the axial line 37 facing in the vertical direction as a central axis line. Although not particularly shown in FIG. 4, the cylindrical drum 47 has a large number of pores that allow the plating solution 33 to pass therethrough. The pores have a diameter of about 0.2 mm, for example, as in the first embodiment. In FIG. 4, the drum 47 is mounted on the bottom surface forming member 36 and is provided to rotate integrally with the bottom surface forming member 36, but is fixed to the plating tank 32 independently of the bottom surface forming member 36. May be provided. Note that the drum 47 is not necessarily provided.

  The operation caused by the rotation of the bottom surface forming member 36 and the conveyance path forming member 39 as described above is substantially the same as the operation described with reference to FIG. 3 in the first embodiment.

  That is, according to the rotational drive by the rotational drive means 40 and 45, the transport path forming member 39 scoops the object to be plated 34 positioned on the bottom surface forming member 36 on the transport path 38 at the lower end thereof, and then transport path 38. Then, the workpiece 34 is conveyed upward. As shown in FIG. 4, the object to be plated 34 conveyed upward along the conveyance path 38 passes through the terminal end of the conveyance path 38 at the upper end portion of the conveyance path forming member 39, thereby forming the bottom surface forming member. Drop toward 36. Then, the above operation is repeated for each of the objects to be plated 34.

  As shown in FIG. 4, the bottom surface 35 formed by the bottom surface forming member 36 is inclined. This inclination is opposite to the inclination of the bottom surface 15 in the first embodiment. As a result, the objects to be plated 34 gather in the vicinity of the lower end of the conveyance path forming member 39 according to gravity, and the conveyance path described above. The introduction of the object to be plated 34 to the lower end portion of the forming member 39 proceeds more smoothly.

  Also in the second embodiment, as in the case of the first embodiment, the object to be plated is transported in the plating tank 32 while the object to be plated 34 is transported along the cyclic path passing through the transport path 38. The electroless plating solution 33 comes into contact with 34, and desired electroless plating is performed.

  As Experimental Example 2 for confirming the effect of the present invention, electroless nickel plating was performed using the plating apparatus 31 according to the second embodiment described above. The composition, pH and bath temperature of the electroless plating solution 33, the size and number of the objects to be plated 34, and the bath load were the same as in the case of Experimental Example 1 described above.

  In the plating apparatus 31, electroless plating was performed by rotating the bottom surface forming member 36 and the shaft 43 in opposite directions at 25 rpm. After the plating treatment, the appearance inspection of 100 chip-like electronic components 1 was performed by sampling, and no abnormal deposition of the plating film was observed in any of the chip-like electronic components 1.

  While the present invention has been described with reference to the illustrated embodiment, various other modifications are possible within the scope of the present invention.

  For example, in the above-described embodiment, the conveyance path forming members 19 and 39 are provided by the fin-like members 24 and 44 provided so as to protrude in a shelf shape from a predetermined surface, but are provided on the predetermined surface. It may be provided by a groove. Further, the conveyance path forming member may be provided independently of a member such as the drum 23 or the shaft 43.

  In the above-described embodiment, the plating apparatus according to the present invention is applied when performing electroless plating, but may be applied when performing electroplating.

It is a top view which shows the chip-shaped electronic component 1 as an example of the to-be-plated object to which the plating apparatus and plating method which concern on this invention can be applied advantageously. 1 is a front view schematically showing a plating apparatus 11 according to a first embodiment of the present invention. FIG. 2 is a view for explaining the operation caused by the rotation of the bottom surface forming member 16 and the transport forming member 19 shown in FIG. 2, and shows the lower end portion and the vicinity of the transport path forming member 19. FIG. 6 is a front view schematically showing a plating apparatus 31 according to a second embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chip-shaped electronic component 3 External electrode 5 Plating film 11, 31 Plating apparatus 12, 32 Plating tank 13, 33 Electroless plating solution 14, 34 To-be-plated object 15, 35 Bottom face 16, 36 Bottom face forming member 17, 37 Up and down direction Axis 18, 38 Conveying path 19, 39 Conveying path forming member 20, 25, 40, 45 Rotating drive means 23 Drum 24, 44 Fin-shaped member 43 Columnar shaft

Claims (8)

A plating tank for storing a plating solution and an object to be plated;
Forming a bottom surface for receiving the object to be plated submerged in the plating solution at the bottom of the plating tank;
A conveying path forming member for conveying the object to be plated in the plating tank, and forming a conveying path extending spirally around an axis line in the vertical direction;
Rotation driving means for rotating the bottom surface forming member and the transport path forming member in directions opposite to each other around the vertical axis;
In accordance with the rotational drive by the rotational drive means, the transport path forming member scoops the object to be plated located on the bottom surface forming member on the transport path at the lower end thereof, and then the transport path forming member along the transport path. After transporting the plated product upward, at the upper end thereof, the plated product that has passed through the terminal end of the transport path is configured to drop toward the bottom surface forming member.
Plating equipment.   The plating apparatus according to claim 1, wherein the bottom surface formed by the bottom surface forming member is provided with an inclination so that the objects to be plated are gathered according to gravity in the vicinity of the lower end portion of the transport path forming member.   It is arranged in the plating tank, and further comprises a cylindrical drum whose central axis is the axis line oriented in the vertical direction, and the transport path forming member is shelf-shaped on the inner peripheral surface of the drum The plating apparatus according to claim 1, wherein the plating apparatus is provided by a fin-like member provided so as to protrude from the surface. The plating apparatus according to claim 3, wherein the drum forms a large number of pores that allow the plating solution to pass therethrough.   It is arrange | positioned in the said plating tank, Comprising: The axis line facing the said up-down direction is made into a center axis line, It further has a cylindrical shaft, The said conveyance path formation member is shelf-shaped on the outer peripheral surface of the said shaft The plating apparatus of Claim 1 or 2 provided by the fin-shaped member provided so that it might protrude. The object to be plated is a chip-like electronic component comprising an external electrode that is scheduled to plating is applied on the surface, used for plating the external electrodes, any one of claims 1 to 5 The plating apparatus as described in.   A plating method comprising the step of applying electroless plating to the object to be plated using an electroless plating solution as the plating solution while using the plating apparatus according to any one of claims 1 to 6. The object to be plated is a chip-shaped electronic component having an external electrode that is scheduled to be plated on its surface, and the step of applying electroless plating includes the step of applying electroless plating to the external electrode. The plating method according to claim 7 provided.

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