JP2010093037A - Multilayer ceramic capacitor and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer ceramic capacitor that has reduced alignment precision required in a lamination process and dispenses with any special processes, such as etching processing, and to provide a method of manufacturing the multilayer ceramic capacitor. <P>SOLUTION: Internal electrodes 4a, 4b are alternately stacked inside a chip-like laminate 20, while sandwiching a ceramic layer. External electrodes 16a, 16b are formed at both the ends of the chip-line laminate 20 each. The internal and external electrodes 4a, 16a include Ag particles, and the internal and external electrodes 4b, 16b include Cu particles. The internal and external electrodes 4a, 16a including Ag particles are electrically connected each other, and the internal and external electrodes 4b, 16b including Cu particles are electrically connected each other. Different kinds of metals Ag-Cu of the internal and external electrodes 4b, 16a and 4a, 16b are separated and are not connected electrically. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multilayer ceramic capacitor and a method for manufacturing the same.

  Conventionally, ordinary multilayer ceramic capacitors have been manufactured by the following method. First, rectangular internal electrode patterns of a predetermined size are arranged on the surface of the ceramic green sheet in a vertical and horizontal manner, and then a plurality of ceramic green sheets are stacked to form a laminate. Next, the laminate is cut into a predetermined size to form a chip-like laminate. In this chip-like laminate, layers in which internal electrodes are led out at one end and layers in which internal electrodes are led out at the other end are alternately laminated. Next, external electrodes are formed on both ends of the chip-like laminate, and the internal electrodes and external electrodes are electrically connected to complete the product.

  In addition, the method for manufacturing a multilayer ceramic capacitor described in Patent Document 1 includes a first internal electrode made of a first metal material and a second internal electrode made of a second metal material, with an insulating layer interposed therebetween. In this manner, a laminated body is formed by alternately laminating. Here, the first metal material and the second metal material have different etching resistances. Next, the first internal electrode is etched using a liquid capable of etching the first metal material, and is retracted from the first end face of the stacked body. Similarly, the second internal electrode is etched using a liquid capable of etching the second metal material, and is retracted from the second end face facing the first end face of the laminate. Next, first and second external electrodes are respectively formed on the first and second end faces of the multilayer body, the first internal electrode is electrically connected to the second external electrode, and the second internal electrode The electrode is electrically connected to the first external electrode to obtain a finished product.

Japanese Patent Laid-Open No. 6-5459

  However, in the conventional method of manufacturing a multilayer ceramic capacitor, time is required for alignment when stacking the ceramic green sheets so that the rectangular internal electrode patterns arranged vertically and horizontally can be accommodated within a predetermined amount of interlayer displacement. In addition, the ceramic green sheet stacking apparatus is complicated. In particular, in a thin ceramic capacitor having a large capacity in recent years, the number of laminated layers cannot be shortened and the stacking time cannot be shortened. Further, since the stacking apparatus becomes expensive, the manufacturing cost cannot be reduced.

  Further, in the manufacturing method described in Patent Document 1, since the internal electrodes formed on the entire surface of the internal electrode layer are alternately stacked with the insulating layer in between, the advantage that it does not take time for alignment at the time of stacking is advantageous. However, since an etching process is required, there is a problem in that the manufacturing cost increases due to the etching apparatus, the management of the etching liquid, and the waste liquid treatment.

  SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide a multilayer ceramic capacitor having a low alignment accuracy required in the lamination process and not requiring a special process such as an etching process, and a method for manufacturing the same.

  The present invention includes a first insulating layer in which a first internal electrode containing first metal particles is formed, and a second insulating layer in which a second internal electrode containing second metal particles is formed. A laminated body configured by alternately laminating, and a first external electrode including first metal particles and a second external electrode including second metal particles respectively provided at both ends of the laminated body, The multilayer ceramic capacitor is characterized in that the first internal electrode and the first external electrode are electrically connected, and the second internal electrode and the second external electrode are electrically connected.

  The present invention utilizes the property that different metals have low affinity and electrical continuity between them is difficult. That is, a first insulating layer and a second insulating layer each formed with first and second internal electrodes containing different metal particles are alternately stacked to form a stacked body, and the first and second insulating layers are respectively stacked at both ends of the stacked body. A first external electrode including one metal particle and a second external electrode including second metal particles are formed. Therefore, by firing the laminate, an electrical connection is obtained by alloying at the joint interface where the internal electrode and the external electrode are of the same metal type. On the other hand, it cannot be alloyed at the joint interface where the internal electrode and the external electrode are made of different metals, and the two electrodes are separated from each other and cannot be electrically connected. As a result, the first internal electrode and the first external electrode are electrically connected, and the second internal electrode and the second external electrode are electrically connected.

  The present invention also includes a step of forming a first internal electrode including first metal particles on the surface of the first insulating layer, and a second internal electrode including second metal particles as the second insulating layer. Forming a laminated body by alternately laminating a first insulating layer and a second insulating layer, and cutting the laminated body into a predetermined size to form a chip-like laminated body A step of applying a first external electrode paste including the first metal particles to one end of the chip-shaped laminate, and a second external electrode paste including the second metal particles being stacked in the chip shape. A method of manufacturing a multilayer ceramic capacitor, comprising: a step of applying to the other end of the body; and a step of baking the first external electrode paste and the second external electrode paste.

  According to the present invention, it is possible to obtain a method for manufacturing a multilayer ceramic capacitor suitable for mass production, in which the alignment accuracy required in the multilayer process is low and a special process such as an etching process is not required.

  Then, by setting the first metal particles to Ag and the second metal particles to Cu, Ag and Cu have good conductivity and the like, so that a multilayer ceramic capacitor having excellent electrical characteristics is obtained.

  According to the present invention, the alignment accuracy required in the laminating process is loose, and a special process such as an etching process is not required, so that the laminating time can be shortened and the cost of the equipment can be reduced. . As a result, the manufacturing cost of the multilayer ceramic capacitor can be reduced.

  The above object, other objects, features, and advantages of the present invention will become more apparent from the following description of the best mode for carrying out the invention with reference to the drawings.

(First embodiment)
FIG. 1 is a flowchart showing a method for manufacturing a multilayer ceramic capacitor, and FIGS. 2 to 7 are diagrams sequentially showing respective steps for manufacturing the multilayer ceramic capacitor. Hereinafter, a multilayer ceramic capacitor according to the present invention will be described together with a manufacturing method thereof.

  First, in step S1, ceramic green sheets 2a and 2b as shown in FIG. 2 are formed on a carrier film. However, FIG. 2 shows only the ceramic green sheet 2a. A PET (polyethylene terephthalate) resin or the like is used for the carrier film. The thickness of the ceramic green sheets 2a and 2b is set to 0.3 μm or more, for example.

  Next, in step S2, an internal electrode 4a containing Ag particles is formed on the entire surface of the ceramic green sheet 2a by a printing method. For the formation of the internal electrode 4a, a paste containing Ag powder as a main component, mixed with a resin material, a solvent or the like and made into a paste by a well-known method is used. Since the internal electrode 4a is formed on the entire surface of the ceramic green sheet 2a, there is no need to worry about bleeding during printing, and there is no variation in the size of the internal electrode 4a.

  Similarly, the internal electrode 4b containing Cu particles is formed on the entire surface of the ceramic green sheet 2b. It should be noted that the Cu paste and the Ag paste are optimized in terms of the amount of co-material added, the metal particle diameter, shape, surface coating, and the like, so that the thermal shrinkage rate during firing in the subsequent process is substantially equal. Furthermore, in order to suppress interlayer delamination, the same kind of resin materials and solvents used for the Cu paste and the Ag paste are preferable.

  Next, in step S3, the ceramic green sheets 2a and 2b are respectively peeled from the carrier film, and then the ceramic green sheets 2a and 2b are alternately laminated as shown in FIG. Since the internal electrodes 4a and 4b are formed on the entire surface of the ceramic green sheets 2a and 2b, the ceramic green sheets 2a and 2b can be easily peeled from the carrier film. The positioning accuracy of the sheets 2a and 2b required at the time of lamination may be loose, and is sufficient if it is within an error range of ± 500 μm. Also, when stacking the ceramic green sheets 2a and 2b, there is no need to cause stacking misalignment, so it is not always necessary to perform temporary crimping at the time of stacking. Mu

  Further, a plurality of protective ceramic green sheets 8 are laminated on the upper and lower sides of the ceramic green sheets 2a and 2b on which the internal electrodes 4a and 4b are formed, and are pressure-bonded (mainly pressure-bonded) to obtain a laminated body 10. At this time, since the internal electrodes 4a and 4b are formed on the entire surface of the ceramic green sheets 2a and 2b, the pressure at the time of crimping is uniformly applied to the entire surfaces of the internal electrodes 4a and 4b, and distortion of the internal electrodes 4a and 4b occurs. Hateful. Then, in the conventional method for manufacturing a multilayer ceramic capacitor in which rectangular internal electrode patterns are arranged vertically and horizontally, the step problem that has occurred with the thinning of the multilayer ceramic capacitor (the internal electrode 4a on the surface of the multilayer ceramic capacitor). , 4b) is also eliminated. Furthermore, since the internal electrodes 4a and 4b are less likely to flow, the height dimension of the chip-shaped laminate 20 described later can be made uniform.

  Next, in step S4, the laminated body 10 is cut out for each predetermined size along the cut line P indicated by a one-dot chain line in FIG. Thereby, the chip-shaped laminated body 20 shown in FIG. 4 is created. At this time, the dimension in the length direction of the chip-shaped laminate 20 is set slightly larger than the product dimension in consideration of the amount of shrinkage during firing. Moreover, the dimension of the width direction of the chip-shaped laminated body 20 is set in consideration of the shrinkage amount during firing and the thickness of the protective material 12 (see FIG. 5) in the next step S5. Since the internal electrodes 4a and 4b are formed on the entire surface of the ceramic green sheets 2a and 2b, it is not necessary to detect and position the cutting position, and the cutting can be performed at a constant pitch. Therefore, it is possible to reduce the price of the cutting machine and improve the cutting speed. The internal electrodes 4a and 4b are exposed on the cut surfaces forming the four side surfaces of the chip-shaped laminate 20.

  Next, in step S5, as shown in FIG. 5, the protective material 12 is formed on each side surface facing the width direction of the chip-shaped stacked body 20 respectively. The protective material 12 is formed by applying a ceramic slurry to the side surface of the chip-like laminate 20. The ceramic slurry is preferably made of the same ceramic material as the ceramic green sheets 2a and 2b. This is because both can be fired under the same conditions during firing, and an abnormal reaction is not caused at the interface between the ceramic green sheets 2a, 2b and the ceramic slurry. The thickness of the protective material 12 shall be about 50-100 micrometers.

  Next, the chip-shaped laminate 20 is fired in step S6. The atmosphere and temperature rise conditions are set so that the internal electrodes 4a and 4b made of different metals can be fired equally.

  Next, in step S7, as shown in FIG. 6, the external electrode 16a containing Ag particles and the external electrode 16b containing Cu particles are formed on the opposite side surfaces of the chip-like laminate 20 in the length direction. The external electrodes 16a and 16b are formed by applying a paste formed by a well-known method, which is mainly composed of Ag powder or Cu powder used to form the internal electrodes 4a and 4b, mixed with a resin material or a solvent. Form.

  Next, in step S8, the external electrodes 16a and 16b are baked. At this time, as shown in FIG. 7, the joint interface between the internal electrode 4a and the external electrode 16a is the same kind of metal (Ag), and the joint interface between the internal electrode 4b and the external electrode 16b is also the same kind of metal (Cu). Therefore, alloying occurs at the bonding interface of the same kind of metals, and electrical connection is obtained.

  On the other hand, the bonding interface between the internal electrode 4b and the external electrode 16a and the bonding interface between the internal electrode 4a and the external electrode 16b are made of different metals (Ag—Cu). Since the dissimilar metals Ag and Cu are metals that hardly dissolve, the alloying does not occur at the joint interface between the dissimilar metals, and the Ag and Cu metal particles contained in the external electrodes 16a and 16b at the joint interface Are sintered while moving to the external electrodes 16a and 16b. As a result, a gap due to the movement of the Ag and Cu metal particles is generated at the bonding interface, which is a dissimilar metal. The gap is filled with the glass frit in the external electrodes 16a and 16b. Therefore, the two are separated from each other at the bonding interface, which is a dissimilar metal, and electrical connection cannot be obtained.

  Next, in step S9, the surfaces of the external electrodes 16a and 16b are plated by electrolytic plating or electroless plating.

  Thus, in the obtained multilayer ceramic capacitor, the internal electrode 4a containing Ag particles and the external electrode 16a are electrically connected, and the internal electrode 4b containing Cu particles and the external electrode 16b are electrically connected. On the other hand, the dissimilar metals (Ag—Cu) of the internal electrode 4b and the external electrode 16a, and the internal electrode 4a and the external electrode 16b are not separated and electrically connected. In the baking step S8 of the external electrodes 16a and 16b, the electrical connection and disconnection between the external electrodes 16a and 16b and the internal electrodes 4a and 4b can be controlled, so that complicated work such as an etching process is unnecessary. Become. Further, since the distance between the external electrodes 16a and 16b and the internal electrodes 4a and 4b can be minimized, even a multilayer ceramic capacitor having the same volume can be obtained with a large capacitance. Further, since the internal electrodes 4a and 4b are formed on the entire surface of the ceramic green sheets 2a and 2b, the positioning accuracy of the sheets 2a and 2b required at the time of lamination may be loose.

  As described above, the alignment accuracy required in the laminating step S3 is loose, and no special process such as an etching process is required, so that the laminating time can be shortened, and the equipment is simplified and miniaturized. Lower prices can be achieved. As a result, the manufacturing cost of the multilayer ceramic capacitor can be reduced.

(Second Embodiment)
According to the second embodiment, in the flowchart shown in FIG. 1, after the formation of the protective material 12 in step S <b> 5, in the step S <b> 10, external surfaces containing Ag particles are respectively provided on the side surfaces facing in the length direction of the chip-shaped stacked body 20. The electrode 16a and the external electrode 16b containing Cu particles are formed (see FIG. 6). The external electrodes 16a and 16b are formed by applying a paste formed by a well-known method by mixing Ag powder or Cu powder used for forming the internal electrodes 4a and 4b as a main component and mixing with a resin material or a solvent. Form.

  Next, in step S11, the chip-shaped stacked body 20 is fired. The firing conditions are set such as the atmosphere and the temperature raising conditions so that the internal electrodes 4a and 4b and the external electrodes 16a and 16b made of different metals can be fired equally. At this time, as shown in FIG. 7, the joint interface between the internal electrode 4a and the external electrode 16a is the same kind of metal (Ag), and the joint interface between the internal electrode 4b and the external electrode 16b is also the same kind of metal (Cu). Therefore, at the joint interface, which is the same kind of metal, solid solutions are formed and alloying occurs, and electrical connection is obtained.

  On the other hand, the bonding interface between the internal electrode 4b and the external electrode 16a and the bonding interface between the internal electrode 4a and the external electrode 16b are made of different metals (Ag—Cu). Since the dissimilar metals Ag and Cu are metals that hardly dissolve, alloying does not occur at the joining interface between these dissimilar metals, and they are included in the internal electrodes 4a and 4b and the external electrodes 16a and 16b at the joining interface. The sintered Ag and Cu metal particles are sintered while moving to the respective base materials (internal electrodes 4a and 4b and external electrodes 16a and 16b). As a result, a gap due to the movement of the Ag and Cu metal particles is generated at the bonding interface, which is a dissimilar metal. This gap is filled with the ceramic in the ceramic green sheets 2a and 2b. Therefore, the two are separated from each other at the bonding interface, which is a dissimilar metal, and electrical connection cannot be obtained.

  Next, in step S9, the surfaces of the external electrodes 16a and 16b are plated by electrolytic plating or electroless plating to obtain a multilayer ceramic capacitor.

  Thus, since the obtained multilayer ceramic capacitor can control electrical connection and disconnection between the external electrodes 16a and 16b and the internal electrodes 4a and 4b in the firing step S11, complicated operations such as an etching process can be performed. It becomes unnecessary. Furthermore, since the internal electrodes 4a and 4b and the external electrodes 16a and 16b are simultaneously fired after the formation step S10 of the external electrodes 16a and 16b, the gap generated at the bonding interface between different metals can be filled with ceramic, As compared with the case of filling with glass frit as in the first embodiment, delamination is less likely to occur.

(Other embodiments)
In addition, this invention is not limited to the said embodiment, In the range of the summary, it changes variously. For example, as the combination of metal particles, in the above-described embodiment, the combination of Ag particles and Cu particles has been described as an example. However, the combination is not necessarily limited to this combination, and other dissimilar metals that can be electrically connected and disconnected are obtained. A combination of these may be used.

  Further, when the chip-like laminate 20 is cut out from the laminate 10, a plurality of stripe-like structures are formed so that the width of the internal electrodes 4a, 4b of the chip-like laminate 20 is smaller than the width of the chip-like laminate 20. By forming the internal electrodes 4a and 4b patterns on the surfaces of the ceramic green sheets 2a and 2b, the step of forming the protective material 12 on the side surface of the chip-like laminate 20 may be omitted. Further, it may be an array type multilayer ceramic capacitor incorporating a plurality of capacitor elements.

It is a flowchart which shows an example of the manufacturing method of the multilayer ceramic capacitor of this invention. It is a top view which shows the ceramic green sheet and internal electrode which are used for a multilayer ceramic capacitor. It is a perspective view for demonstrating lamination | stacking of a ceramic green sheet. It is a perspective view which shows a chip-shaped laminated body. It is a perspective view which shows the chip-shaped laminated body in which the protective material was formed. It is a schematic diagram which shows the cross section in line VI-VI of FIG. FIG. 7 is a schematic cross-sectional view showing the manufacturing process following FIG. 6.

Explanation of symbols

2a, 2b Ceramic green sheet 4a, 4b Internal electrode 16a, 16b External electrode 20 Chip-shaped laminate

Claims (3)

The first insulating layer in which the first internal electrode including the first metal particles is formed and the second insulating layer in which the second internal electrode including the second metal particle is formed are alternately stacked. A laminate composed of
A first external electrode including the first metal particles and a second external electrode including the second metal particles provided at both ends of the laminate, respectively.
The first internal electrode and the first external electrode are electrically connected, and the second internal electrode and the second external electrode are electrically connected;
A multilayer ceramic capacitor characterized by Forming a first internal electrode containing first metal particles on the surface of the first insulating layer;
Forming a second internal electrode containing second metal particles on the surface of the second insulating layer;
Forming the laminate by alternately laminating the first insulating layer and the second insulating layer;
Cutting the laminate into predetermined dimensions to form a chip-like laminate;
Applying a first external electrode paste containing the first metal particles to one end of the chip-shaped laminate;
Applying a second external electrode paste containing the second metal particles to the other end of the chip-shaped laminate;
Baking the first external electrode paste and the second external electrode paste;
A method for producing a multilayer ceramic capacitor, comprising:   The method for manufacturing a multilayer ceramic capacitor according to claim 2, wherein the first metal particles are Ag, and the second metal particles are Cu.