JP2009065005A - Manufacturing method of chip-like electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce plating defects while enhancing productivity of a plating process in forming an external electrode of a chip-like electronic component such as a laminated ceramic capacitor. <P>SOLUTION: A magnetism varying part 4 is arranged on the lower side of a bottom surface 2 of a plating bath 1 provided with the bottom surface 2 without having residual magnetism, and a side surface 3 having a negative electrode 7; chip-like electronic components 15 each containing a magnetic substance such as nickel are arranged on the bottom surface 2 of the plating bath 1 without being filled with a plating liquid 18; magnetism is generated in the magnetism varying part 4; thereafter the magnetism is eliminated from the magnetism varying part 4 after filling the plating liquid 18; and an electrolytic plating process is executed by arranging the chip-like electronic components 15 on the side surface 3 of the plating bath 1 by rotating the plating bath 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a chip-shaped electronic component manufacturing method in which external electrodes of chip-shaped electronic components such as multilayer ceramic capacitors and piezoelectric components are formed by plating.

  One of the chip-shaped electronic components is, for example, a multilayer ceramic capacitor, and the multilayer ceramic capacitor is also miniaturized as electronic devices are miniaturized, and is extremely small with a length of 1.0 mm, a width of 0.5 mm, and a height of 0.5 mm or less. Multilayer ceramic capacitors are used.

  FIG. 5 is a cross-sectional view of a multilayer ceramic capacitor, and FIG. 6 is a cross-sectional view showing a state of an electrolytic plating process in a conventional electrolytic plating process.

  As shown in FIG. 5, external electrodes 34 are electrically connected to the internal electrode layers 31 at both ends of the capacitor body in which the internal electrode layers 31 and the ceramic layers 32 are laminated so that the internal electrode layers 31 are alternately opposed to each other. The laminated ceramic capacitor is provided.

  In the conventional method of forming the external electrode 34 of the multilayer ceramic capacitor, a conductive paste is applied to the capacitor body by a printing method or the like and baked to form the base electrode layer 35. Further, an intermediate layer made of nickel is formed on the base electrode layer 35. An electrode layer 36 and a tin or tin alloy plating layer 37 are sequentially formed by electrolytic plating to form the external electrode 34.

  As a conventional electrolytic plating process for chip-shaped electronic components, if the chip-shaped electronic component is extremely small, it floats on the surface of the plating solution due to buoyancy and cannot be electroplated. Therefore, as shown in FIG. There is a method in which the electroplating process is performed after the chip-like electronic component 55 is sucked by the electromagnet 44 provided on the bottom surface 42 of the bathtub 41 and provided in the bottom surface 42.

For example, Patent Document 1 is known as prior art document information related to the invention of this application.
JP 2007-16290 A

  However, in the conventional method of electrolytic plating of chip-shaped electronic components, when a ferromagnetic metal such as nickel is used for the plating solution 57, the ferromagnetic metal is applied to the external electrode 34 of the chip-shaped electronic component 55 by electrolytic plating. At the same time as the plating film is formed, a ferromagnetic metal plating film is formed on the surface of the cathode electrode 47.

  When this plating bath 41 is used repeatedly, the residual magnetism of the ferromagnetic metal plating film formed on the cathode electrode 47 is increased by the strong magnetism of the electromagnet 44, and the specific chip-like electronic component 55 is attached to the cathode electrode 47 during the electrolytic plating process. As a result, the thickness of the plating film formed on the chip-like electronic component 55 varies, resulting in an increase in defective plating or the extremely small chip-like electronic component 55 sucked by the cathode electrode 47 from the plating bath. There is a problem that productivity becomes low due to difficulty in taking out.

  Then, an object of this invention is to provide the manufacturing method which reduces the plating defect of a chip-shaped electronic component.

  In order to achieve this object, a chip having a magnetic variable portion disposed on the lower side of a plating bath provided with a bottom surface having no residual magnetism and a side surface having a cathode electrode, and containing a magnetic substance on the bottom surface of the plating bath A step of disposing a magnetic electronic component, a step of generating magnetism in the magnetic variable portion, a step of introducing a plating solution into the plating bath, a step of eliminating magnetism in the magnetic variable portion, and rotating the plating bath to It is a manufacturing method of a chip-like electronic component including the process of arranging a chip-like electronic component on the side of a plating bath, and the process of performing electrolytic plating treatment.

  According to the present invention, the bottom surface of the plating bath on which the magnetic field of the magnetic variable portion acts strongly is separated from the cathode electrode by performing the electroplating process by providing the magnetic variable portion on the lower side of the plating bath and the cathode electrode on the side surface. Since it is possible to reduce the occurrence of residual magnetism in the ferromagnetic plating film formed on the cathode electrode, it is possible to prevent a specific chip-shaped electronic component from being continuously attracted to the cathode electrode during the electrolytic plating process, A plating film can be formed uniformly, and there exists an effect which can reduce a plating defect.

(Embodiment)
A description will be given using a multilayer ceramic capacitor as the chip-like electronic component according to the first embodiment of the present invention.

  First, the configuration and manufacturing method of the multilayer ceramic capacitor will be described.

  As shown in FIG. 5, in the multilayer ceramic capacitor, the internal electrode layer 31 is made of a metal having a magnetic property of nickel or a nickel alloy, and the ceramic layer is made of a dielectric material such as barium titanate or strontium titanate. A plurality of layers are stacked so as to face each other through 32.

  The magnetic material may be a material that does not have magnetization when there is no external magnetic field and that has magnetization when a magnetic field is applied, or a material that has spontaneous magnetization without an external magnetic field. Moreover, it is not limited to the internal electrode layer 31 and may be contained in other components.

  The external electrodes 34 are electrically connected to the internal electrode layers 31 drawn at both ends so as to alternately face each other, and prevent the solder erosion with the base electrode layer 35 baked with conductive metal powder such as silver or copper. An intermediate electrode layer 36 of nickel plating and a plating layer 37 made of tin plating or tin alloy for improving solder wettability are provided.

  A method for manufacturing a multilayer ceramic capacitor is, for example, a method in which barium titanate is a main component as the dielectric material of the ceramic layer 32, and strontium carbonate, magnesium oxide, dysprosium oxide, manganese oxide, silica, etc. A dielectric slurry is prepared by adding a small amount of additive and further dispersing it in an organic vehicle containing polyvinyl butyral as a main component.

  Further, nickel paste having an average particle size of 0.1 μm to 0.5 μm as a main component is mixed with a solvent, resin, plasticizer, etc., preferably 40 wt% to 60 wt% of nickel metal powder is contained in the nickel paste Is made.

  Further, the dielectric slurry was applied on a substrate and dried to produce a green sheet, and the nickel paste was printed on the green sheet to form an internal electrode pattern, and a predetermined number of sheets were laminated and pressure-bonded. After that, it is separated into individual pieces and further fired to produce a capacitor body.

  Next, a conductive paste composed of conductive metal powder, glass frit, organic binder and solvent is applied to both ends of the capacitor body, dried, and then baked at a peak temperature of 800 ° C. to 900 ° C. Base electrode layers 35 are formed on both ends of the capacitor body.

  Further, nickel electrolytic plating is performed on the surface of the base electrode layer 35 to form an intermediate electrode layer 36 made of nickel, and tin electrolytic plating is performed on the intermediate electrode layer 36 to form a plated layer 37 to externally The electrode 34 is used to form a multilayer ceramic capacitor.

  Next, the electroplating apparatus used for the electroplating process of the intermediate electrode layer 36 of the multilayer ceramic capacitor will be described.

  FIG. 1 is a cross-sectional view showing a state during an electroplating process in an electroplating process according to an embodiment of the present invention, FIG. 2 is a top cross-sectional view of a magnetic variable portion of the electroplating apparatus, and FIG. It is sectional drawing which shows the state with which the electronic component was arrange | positioned and the plating solution was filled.

  As shown in FIG. 1, the electrolytic plating apparatus includes a plating bath 1 having a circular bottom surface 2, a cylindrical side surface 3 provided perpendicular to the outer periphery of the bottom surface 2, and an opening in the cylindrical side surface 3. In this way, the container is a trapezoidal cone-shaped container provided with a lid 8 with an open upper surface protruding obliquely.

  The bottom surface 2 of the plating bath 1 is made of a material that does not have residual magnetism and does not leave residual magnetism when there is no external magnetic field. With this configuration, no residual magnetism remains on the bottom surface 2 due to the magnetic field generated in the magnetic variable portion 4 provided on the lower side of the plating bath 1, so that the electroplating process is performed when the magnetism of the magnetic variable portion 4 is lost. As a material that prevents the chip-shaped electronic component 15 of the object to be plated from being continuously attracted to the bottom surface 2 and can form a plating film uniformly and does not have residual magnetism of the bottom surface 2, for example, polyvinyl chloride resin, epoxy resin A non-magnetic resin material such as polypropylene resin can be used, and is used as an insulating material constituting the inner surface of the bottom surface 2. Moreover, paramagnetic metals, such as aluminum and copper, can be used as another material which does not have the residual magnetism of the bottom face 2.

  A shaft 11 is fixed to the center portion of the flat inner surface of the bottom surface 2 and is led out from the opening portion of the lid 8 to above the plating bath 1. As with the bottom surface 2, the shaft 11 is preferably configured so that no residual magnetism remains.

  Further, when a conductive material such as metal is used for the bottom surface 2 and the shaft 11 immersed in the plating solution 18 of the plating bath 1, an insulating property is provided so that a current flows during the electrolytic plating process and no plating film is formed. It is desirable that the resin is coated and insulated.

  The rotating means for rotating the plating bath 1 includes a motor 12 and a shaft 11 of a rotation transmission unit connected to the motor 12.

  The side surface 3 of the plating bath 1 is a cathode electrode made of a highly conductive metal such as copper or copper alloy or a corrosion-resistant metal such as titanium on an insulating resin or metal material coated with an insulating resin and insulated. 7 is embedded, and the cathode electrode 7 is continuously exposed along the outer peripheral surface of the side surface 3 in a ring shape or separated and displayed at regular intervals. The exposed surface of the cathode electrode 7 is It is the same surface as the base material inside the side surface 3.

  In addition, it is desirable that either the base material on the side surface 3 of the plating bath 1 or the cathode electrode 7 is made of a material having no residual magnetism, like the bottom surface 2.

  From the vicinity of the center of the open part of the lid 8, the anode 1 is introduced so as not to physically contact the supply nozzle 9 for supplying the plating solution 18 and the plating bath 1.

  The magnetic variable unit 4 desirably uses an electromagnet 4a that can easily obtain a high magnetic force. Magnetic control means for generating magnetism in the electromagnet 4a includes a power supply 13 that supplies current to the electromagnet 4a, the electromagnet 4a, and the electromagnet 4a. And a current control unit 14 for controlling the current flowing through the power supply ON or OFF.

  Moreover, the electromagnet 4a is provided in the mounting base 5, and the coil which comprises the electromagnet 4a from the side surface 3 of the plating bathtub 1 centering on the location of the mounting base 5 corresponding to the position of the center part of the bottom face 2, as shown in FIG. A plurality of dots are arranged in the inner circle at substantially equal intervals.

  The magnetic variable portion 4 and its mounting base 5 are provided mechanically separated from the bottom surface 2 below the bottom surface 2 of the plating bath 1. Thus, by providing the magnetic variable portion 4 separately from the plating bath 1, maintenance of the magnetic variable portion 4 is facilitated, and since the plating bath 1 is not weighted, the rotational power is reduced and power can be saved. .

  In addition, the magnetic variable portion 4 may be embedded in the lower side of the bottom surface 2 of the plating bath 1 instead of being separated from the bottom surface 2 of the plating bath 1 and provided on the lower side.

  Next, a manufacturing method of the nickel electroplating process in forming the intermediate electrode layer 36 of the multilayer ceramic capacitor will be described.

  First, as shown in FIG. 3, a plurality of pieces of the chip-like electronic component 15 to be a multilayer ceramic capacitor in which the base electrode layer 35 is formed on the capacitor body, and the same kind of nickel plating as the nickel plating film of the intermediate electrode layer 36 After mixing the metal balls 16 having the film formed on the surface, the step of placing and placing the mixture 17 inside the bottom surface 2 of the plating bath 1 is performed. Subsequently, the current control unit 12 is turned on and the magnetic variable unit 4 is turned on. The step of generating magnetism is performed to attract and fix the mixture to the bottom surface 2 of the plating bath 1.

  Further, after the step of generating magnetism in the magnetic variable portion 4, a step of putting the mixture 17 into the plating bath 1 and arranging it on the bottom surface 2 may be performed. In this case, it is desirable to increase the magnetic strength in a stepwise manner so that the separation of the mixture 17 does not increase when it is introduced into the plating bath 1.

  Thus, before introducing the plating solution 18 into the plating bath 1, the mixture is fixed to the bottom surface 2 by the magnetism of the magnetic variable portion 4, so that a part of the chip-like electronic component 15 floats on the surface of the plating solution 18. Can be prevented.

  Next, a step of introducing the plating solution 18 into the plating bath 1 from the supply nozzle 9 is performed, and the plating solution 18 is filled so that the entire mixture 17 fixed to the bottom surface 2 of the plating bath 1 is immersed.

  The plating solution 18 only needs to be capable of forming a ferromagnetic plating film, and contains at least one ferromagnetic material such as nickel, iron, cobalt, etc., and is used for the intermediate electrode layer 36 of the multilayer ceramic capacitor. As the plating solution 18 used for the formation, a nickel plating bath which is conventionally used, such as nickel sulfate, nickel chloride, boric acid, pH 2 to pH 6 Watt bath, high chloride bath and the like containing additives can be used.

  The step of introducing the plating solution 18 into the plating bath 1 includes the step of placing the chip-like electronic component 15 containing a magnetic substance on the bottom surface 2 of the plating bath 1 and the step of generating magnetism in the magnetic variable portion 4. Can be done before. In this case, the plating solution 18 is such that the chip-like electronic component 15 floating on the surface of the plating solution 18 introduced into the plating bath 1 can be sunk on the bottom surface 2 of the plating bath 1 by magnetism by the magnetic variable portion 4. Adjust the amount of introduction.

  Subsequently, the current control unit 14 is turned OFF and the magnetic variable unit 4 is demagnetized. Then, the plating bath 1 is rotated about the shaft 11 by the motor 12 and the mixture 17 is moved to the side surface 3 by centrifugal force. As shown in FIG. 1, the mixture 17 is arranged and fixed on the cathode electrode 7 on the side surface 3 while preventing the mixture 17 and the plating solution 18 from jumping out from the upper surface opening of the plating bath 1 by the lid 8. The process is performed. Further, a current supplied from the power source 10 is supplied to the anode electrode 6 and the cathode electrode 7 to perform an electrolytic plating process.

  Moreover, the magnetism of the magnetic variable part 4 may be eliminated while gradually increasing the rotational speed of the plating bath 1, and the time for the electrolytic plating process can be shortened.

  A nickel plating film is formed on the surface of the base electrode layer 35 by the electrolytic plating treatment, and a nickel plating film is formed on the surface of the cathode electrode 7 exposed on the side surface 3 of the plating bath 1.

  Then, after discharging the plating solution 18 from the plating bath 1, the mixture 17 is taken out from the plating bath 1, and the formation of the intermediate electrode layer 36 of the multilayer ceramic capacitor is completed.

  In order to increase the productivity of the electroplating process, the series of electroplating processes from the introduction of the multilayer ceramic capacitor pieces to the electroplating process and removal, the intermediate electrode layers of the multilayer ceramic capacitors of other lots that follow. When the 36 nickel coating is formed, the nickel plating coating formed on the cathode electrode 7 of the plating bath 1 is not removed, and the plating bath 1 is repeatedly used a plurality of times. The number of times of repeatedly using the plating bath 1 is adjusted by the accumulated value of the amount of electricity required for the electrolytic plating treatment and is about 5 to 300 times.

  Moreover, the other plating apparatus used for the electrolytic plating process of this invention is demonstrated. In the other plating apparatus, the same parts as those in the plating apparatus shown in FIG.

  FIG. 4 is a cross-sectional view of another plating apparatus used in the electrolytic plating process according to the embodiment of the present invention. As shown in FIG. 4, a rotating means is provided below the bottom surface 22 of the plating bath 21 and the shaft 23 connected to the motor 24 is fixed to the center outside the bottom surface 22, and the magnetic variable portion 25 provided on the mounting base 26 is provided with the shaft 23. Are dotted in a donut shape along the bottom surface 22.

  Next, examples of the present invention and comparative examples will be described.

  In the example and the comparative example, a base electrode layer 35 made of copper and glass frit is formed at both ends of a capacitor body of a ceramic layer 32 mainly composed of barium titanate having a nickel internal electrode layer 31 shown in FIG. In this manufacturing method, the intermediate electrode layer 36 of the nickel plating film is formed by electrolytic plating using individual pieces of the laminated ceramic capacitor having a length of 1.0 mm, a width of 0.5 mm, and a height of 0.5 mm.

(Example)
In the example, a mixture 17 of a plurality of monolithic ceramic capacitors 15 and steel balls 16 having a nickel plating film formed on the surface is placed in the plating bath 1 of the plating apparatus shown in FIG. 1 described in the embodiment. Then, the current control unit 14 is turned on to generate magnetism in the electromagnet 4a, and then the nickel plating solution 18 is filled until the mixture 17 is covered, and then the current control unit 14 is turned off to zero the magnetism of the electromagnet 4a. Subsequently, the plating bath 1 was rotated to apply a current to the anode electrode 6 and the cathode electrode 7 to perform plating.

  In order to make the nickel plating film of the intermediate electrode layer 36 uniform, the rotation and operation of the plating bath 1 are stopped while the plating solution 18 is filled, and the supply of current to the anode electrode 6 and the cathode electrode 7 is stopped and applied. And the electroplating process was performed by repeating the process in synchronization with each other.

The plating conditions were a current density of 0.1 to 10 A / dm ² , a cumulative current application time of 20 to 100 minutes was performed, and an intermediate electrode layer 36 of a nickel plating film having a thickness of 3 μm was formed.

  The plating bath 1 was used by repeating a series of electrolytic plating treatment steps 100 times without removing the nickel plating film formed on the cathode electrode 7 of the plating bath 1.

(Comparative example)
In the plating apparatus of the comparative example, as shown in FIG. 6, the cathode electrode 47 is provided inside the circular bottom surface 42 of the plating bath 41, the electromagnet 44 is embedded below the bottom surface 42, and the side surface 43 is perpendicular to the outer periphery of the bottom surface 42. The other configuration is the same as that of the plating apparatus of the example.

  The same mixture 17 as in the embodiment is put into the plating bath 41, the magnetism is generated in the electromagnet 44, and then the same nickel plating solution 57 as in the embodiment is supplied from the supply nozzle 49 until the mixture is covered. The plating solution 57 was filled, and then the electromagnet 44 was magnetized to zero, and the plating bath 41 was rotated by the motor 52 through the shaft 51 to apply current from the power source 50 to the anode electrode 46 and the cathode electrode 47 to perform plating. .

  At this time, the nickel plating film formed on the cathode electrode 47 of the plating bath 41 was performed in the same manner as in the example except that the plating process was performed at a lower rotational speed than in the example so that the mixture 17 did not move to the side surface 43. The plating bath 41 was utilized by repeating a series of electrolytic plating treatment steps 100 times without removing.

  Table 1 shows the plating failure rate in the above-mentioned Examples and Comparative Examples, and the plating failure rate is after the series of electrolytic plating treatment steps is completed with respect to the total number of the 100 times multilayer ceramic capacitors put into the electrolytic plating treatment step. The ratio of the total quantity which totaled the quantity of the multilayer ceramic capacitor with which it adhered to the cathode electrode for every electrolytic plating process is shown.

  As shown in Table 1, the defective plating rate of the examples is 0.01%, and the comparative example is 0.97%. It can be seen that the defective plating rate is significantly improved in the examples as compared with the comparative example.

  As described above, by using the chip-shaped electronic component manufacturing method of the present invention, there is an effect that plating defects can be reduced.

  The method for manufacturing a chip-shaped electronic component according to the present invention is useful for an electrolytic plating process for forming a plating film having ferromagnetic properties on a small object to be plated.

Sectional drawing which shows the state in the electroplating process in the electroplating process of embodiment of this invention Top sectional drawing which shows the magnetic variable part of the electroplating apparatus of embodiment of this invention Sectional drawing which shows the state by which the chip-shaped electronic component was arrange | positioned to the plating bath in the electrolytic plating treatment process of embodiment of this invention, and the plating solution was filled Sectional drawing of the other electroplating apparatus used for the electroplating process of this invention Cross section of multilayer ceramic capacitor Sectional drawing which shows the state of the electroplating process in the conventional electroplating process

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plating bath 2 Bottom 3 Side 4 Magnetic variable part 6 Anode electrode 7 Cathode electrode 15 Chip-shaped electronic component 18 Plating solution

Claims (3)

A step of disposing a magnetic variable portion on a lower side of a plating bath provided with a bottom surface having no residual magnetism and a side surface having a cathode electrode, and disposing a chip-like electronic component containing a magnetic material on the bottom surface of the plating bath; A step of generating magnetism in the magnetic variable portion, a step of introducing a plating solution into the plating bath, a step of eliminating magnetism in the magnetic variable portion, and a chip-like electron on the side of the plating bath by rotating the plating bath A method for manufacturing a chip-shaped electronic component, comprising: a step of arranging a component; and a step of performing an electrolytic plating process. A step of introducing a plating solution into the plating bath includes a step of disposing a chip-shaped electronic component containing a magnetic material on a bottom surface of the plating bath, and a step of generating magnetism in the magnetic variable portion. The manufacturing method of the chip-shaped electronic component of Claim 1 performed later. The method of manufacturing a chip-shaped electronic component according to claim 1, wherein the electrolytic plating treatment forms a ferromagnetic plating film.

Images