JPH02277205A - Laminated ceramic capacitor - Google Patents

Abstract

PURPOSE:To prevent a plating liquid executed on an outer electrode from invading to the side of an inner electrode, to restrain an electrical characteristic as a capacitor from being deteriorated and to enhance reliability by a method wherein a semiconductor layer is formed between an inner-electrode layer and the outer electrode. CONSTITUTION:When a semiconductor layer 5 is formed between both end-faces of a laminated dielectric ceramic 2 and an outer electrode 6 and a plated film 7 is formed on the outer electrode 6, the plated film is shut off by the semiconductor layer 5 and this layer prevents the film from invading to the side of inner electrodes 3. Accordingly, no unnecessary object exists at the inside of the laminated dielectric ceramic 2; an electrical characteristic as a capacitor is not deteriorated; high reliability is realized. In addition, since the semiconductor layer 5 is formed at end faces of a bonding interface between the inner electrodes 3 and the dielectric ceramic 2, it protects the bonding interface; a close-contact strength at the end-face part of the bonding interface is increased. When a conductive layer (outer electrode 6) is formed, a crack or the like is not produced when a bending stress or an impact force acts; it is possible to prevent the film from being stripped off. Thereby, a deterioration of a laminated ceramic capacitor 1 is reduced and long reliability is kept.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multilayer ceramic capacitor in which conductive layers functioning as external electrodes are formed at both ends of a multilayer dielectric ceramic in which internal electrodes are embedded in layers.

A multilayer ceramic capacitor has internal electrodes embedded in layers between dielectric ceramics to form a multilayer dielectric ceramic, and then silver paste is applied to the exposed surfaces of the internal electrodes at both ends of the multilayer dielectric ceramic. Generally, external electrodes are formed by coating and baking.

By the way, when this type of multilayer ceramic capacitor is connected to a wiring board by soldering, a so-called silver crack occurs in which silver is melted and incorporated into the solder. This causes significant deterioration of the multilayer ceramic capacitor, so conventionally, a film is formed on the external electrode in the manufacturing process of the multilayer ceramic capacitor. That is, at the stage where the laminated dielectric ceramic is formed, a conductive layer containing a noble metal such as silver is formed on both end faces of the laminated dielectric ceramic, and then a conductive layer containing a noble metal such as nickel or copper, which has heat resistance such as nickel or copper, is melted into solder. It was plated with a tough metal material to prevent the silver from scratching. moreover,
Recently, attempts have been made to plate solder on this plating film for the purpose of improving solder adhesion.

However, by forming a multilayer coating on the laminated dielectric ceramic, there was a problem in that although silver corrosion and solderability were improved, the electrical characteristics deteriorated. In other words, #1 fine voids (porous pores) are normally formed in the conductive layer such as silver formed on both ends of the laminated dielectric ceramic, but in order to form a plating film on top of the #1 fine voids (porous pores), the plating bath is When the laminated dielectric ceramic is immersed in the liquid, the plating liquid enters the voids in the conductive layer, and is diffused to the bonding interface between the internal electrode and the laminated dielectric ceramic, reducing the adhesion strength of the bonding interface. Not only that, but the dielectric constant, insulation resistance, etc. changed, leading to deterioration of the electrical characteristics of the capacitor.

In addition, in conventional multilayer ceramic capacitors, the bonding interface between the internal electrodes and the multilayer dielectric ceramic is exposed to the outside in order to extract dielectric capacitance in the element state before external electrodes are formed. Since the mechanical strength of this bonding interface is low, cracks are likely to occur there, resulting in a phenomenon that the life of the multilayer ceramic capacitor itself is shortened.

That is, in the process of forming an external electrode on the end face where the bonding interface between the laminated dielectric ceramic and the internal electrode is exposed to the outside, if stress concentrates on the bonding interface, which has poor mechanical strength against stress such as bending, the bonding will deteriorate. Cracks occur at the interface,
In the worst case, the internal electrodes will peel off.

Therefore, an object of the present invention is to prevent the plating solution applied on the external electrodes from entering the internal electrodes, suppress the deterioration of the electrical characteristics of the capacitor, and create a highly reliable multilayer ceramic capacitor. It is about providing.

In order to solve the above problems, a multilayer ceramic capacitor according to the present invention includes a plurality of dielectric ceramic layers, which are arranged in a stacked state with each other via the dielectric ceramic layers, and are arranged in a state where they are laminated with each other with the dielectric ceramic layers interposed therebetween to reduce static electricity. A semiconductor layer connected to a predetermined one of the internal electrode layers is formed on the end face of the laminated dielectric ceramic consisting of a plurality of internal electrode layers for forming a capacitor, and a conductive layer is further formed on the semiconductor layer. It is characterized by being formed.

The semiconductor layer is formed, for example, using a semiconductor agent that converts the dielectric ceramic layer into a semiconductor, and is preferably formed from ceramic powder contained in the dielectric ceramic layer containing the semiconductor agent. Further, the conductive layer is formed of, for example, a baked layer of conductive paste containing conductive metal powder as a main component or a plated layer of conductive metal,
In particular, it is preferable that a plating layer is formed on the baked layer.

Due to the above structure, a semiconductor layer is formed between the internal electrode layer and the conductive layer, so the inner and outer electrode layers and the conductive layer are electrically connected, but structurally they are not semiconductor layers. It is divided into layers. As a result, when a film is formed on the conductive layer by plating to prevent silver corrosion during soldering, the plating solution is blocked by the semiconductor layer and does not enter the internal electrode side when this film is formed. do not have. Therefore, unnecessary substances will not enter the laminated dielectric ceramic layer, and the electrical characteristics of the capacitor will not deteriorate.

Taikan billion Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the multilayer ceramic capacitor according to the present invention has a multilayer dielectric ceramic capacitor on both end surfaces of a multilayer dielectric ceramic 1 obtained by stacking a plurality of dielectric ceramics 2 with internal electrodes 3 interposed therebetween. An external electrode 6, a plating film 7 of nickel, steel, etc., and a plating film 8 of solder, tin, etc. are formed through the semiconductor layer 5 described above, and it is cut into a rectangular parallelepiped chip type.

Alternatively, as shown in FIG. 5, the laminated dielectric ceramic 1
The plating films 7 and 8 may be directly formed on both end faces of the semiconductor layer 5 via the semiconductor layer 5 to function as external electrodes.

Next, the manufacturing steps will be explained in order.

First, the laminated dielectric ceramic 1 is formed. This laminated dielectric ceramic 1 is manufactured as follows. In other words,
As shown in Fig. 2 and Fig. 5, dielectric ceramic 2 (green sheet) made by slurrying material powder into a sheet form.
Prepare the internal electrode 3 by applying Pd paste on its negative side.
Form a conductive paste layer. The required number of dielectric ceramics 2 having a conductive paste layer that will become internal electrodes 3 is stacked, and as shown in FIGS. 3 and 6, they are sandwiched and crimped with dielectric ceramics 4 that do not have internal electrodes 3 to form a laminate. shall be.

Note that the conductive paste layer that becomes the internal electrode 3 is of a type in which the end that is electrically connected to the external electrode is not exposed to the end 2a of the dielectric ceramic 2, as shown in FIGS. 2 and 3. ,
Alternatively, as shown in FIGS. 5 and 6, one of the types exposed at the end 2a of the dielectric ceramic 2 may be used.

Next, semiconductor layers 5 are formed on both end faces of this laminate. This semiconductor layer 5 is made of, for example, a paste in which a binder is mixed in with a semiconductor agent that converts the dielectric ceramic into a semiconductor, or a paste in which a binder is mixed in the ceramic powder contained in the dielectric ceramic and the semiconductor agent mixed therein. It is formed by coating and firing at a predetermined temperature.

Subsequently, the laminated dielectric ceramic 1 fired as described above is
External electrodes 6 are formed on the end faces of. This external electrode 6 is
It is formed by applying and baking a conductive paste made of metal powder such as silver, and covers the surface of the semiconductor layer 5. Thereafter, the external electrode 6 is plated with nickel, steel, etc. to form a plating film 7. Finally, this plating film 7
A plating film 8 is formed by plating with solder, tin, etc., to obtain a chip-type multilayer ceramic capacitor.

[Example 1] Specifically, Ba was used as the composition material of the dielectric ceramic.
Ti0. 84.35mol1%, 13aZrOm 15
．． MnC0 for 100% of 65mo1% added
, was added at a ratio of 0.07 wt%. PVA (polyvinyl alcohol) was used as a binder, and a surfactant, a dispersant, and water were added to these raw material powders and kneaded to obtain a slurry. Subsequently, this slurry was formed into a sheet by a doctor blade method to form a green sheet with a thickness of 35 μm. Thereafter, Pd paste was printed on one side of the green sheet by screen printing to form a conductive paste layer that would become the internal electrodes 3 shown in FIG. A plurality of green sheets having conductive paste layers serving as internal electrodes 3 were laminated according to the required capacitance. At this time, one end 2a that is electrically connected to the internal electrode 3 and the other end 2b that is not connected are stacked alternately (see FIG. 3). Further, by thermocompression bonding in this state, an unfired laminate in which the internal electrodes 3 were not exposed at the ends 2a and 2b was obtained.

Next, semiconductor layers 5 electrically connected to internal electrodes 3 are formed on both end faces of this stacked body. This semiconductor layer 5 was prepared by adding and kneading a paste consisting of ethyl cellulose resin and butyl cellosolve solvent to 10 wt % La*Os as a semiconductor agent to obtain a semiconductor agent paste. This paste was then applied to both end surfaces of the laminate. Furthermore, after drying this laminate, it was heated to 1300°C in the air.
The laminate was fired for 2 hours to transform the laminate into a porcelain material and form the semiconductor layer 5 at the same time. As a result, the semiconductor forming agent was diffused into both end faces of the laminate, and a laminated dielectric having a structure in which the semiconductor layer 5 and the internal electrode 3 were electrically connected was obtained.

Subsequently, external electrodes 6 are formed on both end surfaces of the laminated dielectric. This external electrode 6 was formed by applying silver paste to both end faces on which the semiconductor layer 5 was formed and baking it in air at 800°C. Thereafter, a plating film 7 is formed on this external electrode 6.

As this plating material, a nickel plating solution consisting of nickel sulfate or nickel chloride and boric acid was prepared, and nickel was plated on the external electrode 6 by barrel plating. Finally, a plating film 8 was formed on this plating film 7. For this plating, AS bath (alkanol sulfonic acid)
A solder plating solution consisting of was prepared and solder was plated on the plating film 7 by barrel plating method. With this, the multilayer ceramic capacitor 1 shown in FIG. 1 is completed.

The multilayer ceramic capacitor formed in this way is
It is as follows.

External dimensions Width: 3.2 mm Length: 1.6 mm Thickness: 1.2 mm Ceramic unit thickness = 20 μm Total number of effective dielectrics, 19 - Opposing electrode area per layer: 1.3 mm2 By the way,
In order to understand the electrical characteristics of the multilayer ceramic capacitor of Example 1, a conventional product was used as a comparative example and tested under the same conditions. In addition, in this test, in order to measure the difference due to the presence or absence of the semiconductor layer 5, the samples were prepared after the external electrode 6 was baked and after the solder plating film 8 was formed for both the comparative example and the present invention example. It was used as

First, in order to measure the capacitance (C) and dielectric loss (tanS>), an automatic bridge-type measuring instrument was used to measure the
After applying a voltage of kHt, IVrms, a voltage of 50 V was applied for 2 minutes using an insulation resistance meter to measure the insulation resistance (R). Then, the CR product between the capacitance (C) and the insulation resistance (R) was determined.

The measurement results from the above tests are shown in Table 1 below.

[See the blank space below] As can be understood from Table 1 above, it is clear that the multilayer ceramic capacitor of the present invention has high reliability without deterioration in electrical characteristics even after the formation of the semiconductor layer 5. It became.

That is, when comparing the measurement results after silver baking and after solder plating with the comparative example, the capacitance (C) of the comparative example was 0.16.
The dielectric loss (tan
S) has increased from 1.6% to 10%.

Also, it is observed that the CR product has dropped extremely to 5000ΩF and 200ΩF. As described above, in the comparative example, the electrical characteristics were significantly deteriorated, which indicates that unnecessary substances were mixed inside the laminated dielectric ceramic. This proves that it penetrates into the porous pores of the conductive layer made of the nickel plating film 7 and further reaches the end part made of the dielectric ceramic 2 and the internal electrode 3, proving that it has completely diffused into the laminated dielectric ceramic 1. It is something.

On the other hand, in the example of the present invention, both capacitances (C) are 0.16 μF.
The dielectric loss (tanS) is also 1.7%.

Further, the CR products are both 5000 ΩF, and there is no difference. As described above, no change was observed in the electrical characteristics of the examples of the present invention. Therefore, the inner electrode 3 and the outer electrode 6
It can be seen that the electrical connection is proper. This shows that there are no unnecessary substances in the laminated dielectric ceramic 1, and silver baking does not prevent the semiconductor layer 5 from entering the conductive layer even if the plating liquid enters the porous pores of the conductive layer when solder plating is applied later. It is confirmed that the intrusion into the interior is blocked and does not reach the bonding interface between the dielectric ceramic 2 and the internal electrode 3. When this multilayer ceramic capacitor is connected to a wiring board by soldering, since the plating film 7 is applied, there is no problem of silver denting, and the connection is ensured.

Further, in the example of the present invention, by forming the semiconductor layer 5,
It was also revealed that it has excellent mechanical strength. That is, unlike conventional products, the laminated dielectric chip before forming the external electrodes 6 does not directly expose the bonding interface between the internal electrodes 3 and the dielectric ceramic 2 to the outside in order to take out the capacitance. Layer 5 is formed. Therefore, the semiconductor layer 5
protects the bonding interface between the internal electrode 3 and the dielectric ceramic 2, and at the same time improves the adhesion strength at the end of the bonding interface. As a result, even if bending stress or impact force is applied to the semiconductor layer 5 of the laminated dielectric chips to align the laminated dielectric chips when processing with an automatic machine in the process of applying and baking paste for external electrodes, Internal electrode 3 and dielectric ceramic 2
Since the adhesion strength in this area is increased, cracks do not occur, and the conventional problem of early deterioration of the capacitor is also solved.

[Example 2] In Example 2, the composition of the semiconductor layer 5 and the form of the internal electrode 3 are changed. First, BaT io *, which is the composition material of the dielectric ceramic similar to Example 1, is used.
84.35mo1%, 15.65m of BaZr0s
O1% added to 100wt%, MnCO5 was added to 0
．． Using the mixed powder added at a ratio of 0.7 wt%, a green sheet with a thickness of 35 μm was formed in the same process as in the above example. Thereafter, Pd paste was printed on one side of the green sheet by screen printing to form a conductive paste layer that would become the internal electrodes 3 shown in FIG. In this case, the conductive paste layer that will become the internal electrode 3 is exposed at the end 2a. The green sheets having the internal electrodes 3 are stacked with the ends 2a and 2b alternately stacked as shown in FIG.
A laminate in which the internal electrodes 3 were exposed at the end portions 2a was obtained by thermocompression bonding.

Next, the dielectric ceramic composition BaTiO
A raw material powder was obtained by adding (eOt) at a ratio of 0.1 mo1% to a mixed powder consisting of BaZrOs, BaZrOs, and MnCO5.

Further, an ethyl cellulose resin and a butyl cellulose solvent were added to this raw material powder and kneaded to prepare a semiconductor agent paste. Then, this paste was applied to both end faces of the laminate where the internal electrodes 3 were exposed to the outside, and dried to obtain an unfired laminate in which the internal electrodes 3 were not exposed to the outside.

Subsequently, this laminate was fired in air at 1300° C. for 2 hours to simultaneously transform the laminate into a porcelain material and form the semiconductor layer 5. As a result, a laminated dielectric having a structure in which the semiconductor layer 5 and the internal electrode 3 were electrically connected was obtained.

Thereafter, the plating film 7.
8 was formed to obtain a multilayer ceramic capacitor 1.

The multilayer ceramic capacitor manufactured in this manner is the same as that of Example 1 in terms of external dimensions and other aspects. Further, a test to determine the electrical characteristics was conducted under the same conditions as in Example 1, and the same sample was used for the conventional product adopted as a comparative example.

The measurement results from the above test are shown in Table 2 below.

[See the blank space below] As can be understood from Table 2 above, the multilayer ceramic capacitor of the present invention example in Example 2 also has high reliability without any change in electrical characteristics as in Example 1. It has become clear that it has. That is, the measurement results after silver baking and after solder plating show that in the case of Example 2, the capacitance (C) is both 0.11F, and the dielectric loss (tan
&) were both 1.6%. Also, the CR products are both 5
000ΩF, and no change was observed in these electrical characteristics.

This is because, as in Example 1, when plating is performed after silver baking, the plating solution is transferred to the internal electrodes due to the presence of the semiconductor layer 5.
The internal electrode 3 and the external electrode 6 are electrically connected without any problem, indicating that no unnecessary substances exist inside the laminated dielectric ceramic 1 without entering the bonding interface between the electrode and the dielectric ceramic 2. This shows that. Of course, the multilayer ceramic capacitor is properly connected to the substrate without the problem of silver cracking.

By the way, the multilayer ceramic capacitor according to the present invention is
Internal electrodes 3 and external electrodes 6 are electrically connected via semiconductor layer 5 without being in direct contact. Therefore, in addition to providing the above-mentioned features, the following effects are achieved.

That is, in the multilayer ceramic capacitor, in order to improve solderability, a solder plating film is formed on the external electrode via a plating film. Tin, which is mainly used in this solder, generally has the property of easily forming alloys with many metals, especially at high temperatures. This metal compound is diffused into the laminated dielectric ceramic over time and eventually spreads to the internal electrodes. In this case, a phenomenon may occur in which the electrical properties of the capacitor, such as dielectric constant and capacitance, are significantly reduced, probably due to chemical changes in the composition materials.

However, in the multilayer ceramic capacitor according to the present invention, since the semiconductor NI 5 is formed between the multilayer dielectric ceramic 1 and the external electrode 6 as described above, the solder plating film 8
Even if it is tin, it does not penetrate to the internal electrode 3 side, and its diffusion is also blocked. Therefore, the electrical characteristics of the laminated dielectric ceramic 1 as a capacitor are kept stable. Like this,
The multilayer ceramic capacitor according to the present invention is not adversely affected by the composition materials of the solder.

[Example 3] In Example 3, metal powder was added as a component of the semiconductor layer 5, and the process of forming the semiconductor layer 5 and the process of forming the external electrode 6 were performed simultaneously.

First of all, as a composition material for dielectric ceramic, it has a purity of 99%.
The above BaC0, CaCO5, ZrO, can be expressed as composition formula 4
It was weighed so that the formula (%) was obtained. The weighed raw material powders were mixed and calcined to obtain a dielectric ceramic raw material powder.

To this dielectric ceramic raw material powder, 15 wt% of a mixed aqueous solution consisting of an organic binder, a dispersant, and an antifoaming agent was added,
The mixture was mixed and ground in a ball mill with 50% water to prepare a slurry. Subsequently, this slurry was formed into a sheet by a doctor blade method to form a green sheet with a thickness of 35 μm.

Next, a paste containing nickel powder was printed on this ceramic green sheet to form a conductive paste layer that would become the internal electrodes 3 in the form shown in FIG. Then, a green sheet having a conductive paste layer that will become the internal electrode 3 is
As shown in FIG. 3, the end portions 2a and 2b were stacked one on top of the other, and a laminate in which the internal electrodes 3 were not exposed at the end portions 2a and 2b was obtained by thermocompression bonding.

Next, a raw material powder in which 5% of La1O1 was added as a semiconductor agent to 95-t% of nickel powder was made into a paste, and this paste was applied to both end faces of the laminate and dried.

The laminate thus obtained was heated at 50° in a N atmosphere.
After heating to C and burning the organic binder, the oxygen partial pressure is 1
0-” to 10-12 MPa H!Nm and HtO
A laminated dielectric having a structure in which the semiconductor layer 5 is electrically connected to the internal electrode 3 and the external electrode 6 is formed on the semiconductor layer 5 is baked at 1300° C. for 2 hours in a reducing atmosphere using a mixed gas. I got a body.

Thereafter, the plating film 7.
8 was formed to obtain a multilayer ceramic capacitor 1.

On the other hand, in order to compare the electrical characteristics of the multilayer ceramic capacitor of Example 3, a multilayer ceramic capacitor (comparative example) equivalent to the conventional product was manufactured in the following process.

A paste containing nickel powder was printed up to the end portion 2a on a ceramic green sheet having a thickness of 35 μm and made of the same material composition as in Example 3 to form a conductive paste layer that would become the internal electrode 3. The green sheets were stacked and thermocompression bonded to obtain a laminate in which conductive paste layers, which would become internal electrodes 3, were exposed on both end faces.

The laminate thus obtained was heated at 50° in a N atmosphere.
After heating to C, it was fired for 2 hours at 1300''C in the same reducing atmosphere as in Example 3 to obtain a laminated dielectric.

A conductive paste to which nickel powder and zinc borosilicate glass were added was applied to both end faces of this laminated dielectric, dried, and baked at 900° C. for 30 minutes in a N atmosphere to form external electrodes. Next, the same plating film 7 is applied on the external electrode.
, 8 was formed to obtain a multilayer ceramic capacitor.

Both the inventive example and the comparative example manufactured through the above process have the same specifications as those explained in Example 1, such as external dimensions, etc.
The capacitance (C), dielectric loss (tan δ), and insulation resistance (R) of these before and after solder plating were measured using the same method as in Example 1, and the CR product was determined.

[Left below] As is clear from Table 3 above, the multilayer ceramic capacitor of Example 3 did not suffer from any deterioration in electrical characteristics, similar to those of Examples 1 and 2 (defective rate was 0). /100
On the other hand, in the comparative example, there was a decrease in the adhesion strength between the internal electrode and the dielectric ceramic, and deterioration of the characteristics as a capacitor (defective rate: 12/1000 pieces).Similar results were obtained. The reason is the same as explained in Examples 1 and 2 above.

[Embodiment 4] In this embodiment 4, as shown in FIG. 4, plating films 7 and 8 were formed directly on the semiconductor layer 5.

As the composition material of the dielectric ceramic, the same as that of Example 3 was used, and a green sheet having a thickness of 35 μm was formed in the same manner. Similarly, the internal electrodes 3 are printed using nickel powder paste in the form shown in FIG. 2 so that the ends 2a are not exposed, and the ends 2a and 2b are overlapped with each other as shown in FIG. A laminate was obtained by laminating and thermocompression bonding, in which the conductive paste layer that would become the internal electrode 3 was not exposed at the ends 2a and 2b.

Next, a semiconductor-forming paste consisting of 10 wt % LaOi as a semiconductor-forming agent, an ethyl cellulose resin, and a butyl cellulose solvent was applied to both end faces of the laminate and dried.

The above laminate was heated to 500°C in a N atmosphere to burn off the organic binder, and then fired in a reducing atmosphere under the same conditions as in Example 3, and was electrically connected to the internal electrode 3. A laminated dielectric having a structure including a semiconductor layer 5 was obtained.

Thereafter, plating films 7 and 8 were formed in the same process as in Example 1.3 to obtain a multilayer ceramic capacitor 1.

On the other hand, in order to compare the electrical characteristics of the multilayer ceramic capacitor of Example 4, a comparative example similar to that used in Example 3 was manufactured. However, in this comparative example, a silver paste was used for the external electrode, and the silver paste was applied, dried, and then baked at 800° C. in a neutral atmosphere to form the external electrode.

Both the inventive example and the comparative example manufactured through the above process have the same specifications as those explained in Example 1, such as external dimensions, etc.
The capacitance (C), dielectric loss (tan δ), and insulation resistance (R) of these before and after solder plating were measured using the same method as in Example 1, and the CR product was determined.

As is clear from Table 4 above, the multilayer ceramic capacitor of Example 4 did not suffer from any deterioration in electrical characteristics, similar to those of Examples 1, 2 and 3. Defective rate 0/1
On the other hand, in the comparative example, there was a decrease in the adhesion strength between the internal electrode and the dielectric ceramic, and deterioration in the characteristics as a capacitor (defective rate: 13/1000 pieces).Similar results were obtained. The reason is the same as explained in Examples 1 and 2 above.

Note that the multilayer ceramic capacitor according to the present invention is not limited to the above-mentioned embodiments, and can be variously modified within the scope of the gist.

In particular, the semiconductor agent for forming the semiconductor layer 5 can have various compositions, and the same applies to dielectric ceramic materials and the like. In addition, various methods such as sputtering, vapor deposition, spraying, and dipping can be used to attach the semiconducting agent to both end surfaces of the laminate, and these methods can also be used when forming the conductive layer. It is.

As described in detail above, according to the present invention, since a semiconductor layer is formed between both end faces of the laminated dielectric ceramic and the external electrode, when forming the plating film on the external electrode, the plating film is is blocked by the semiconductor layer and is prevented from entering the internal electrode side. Therefore, there are no unnecessary substances inside the laminated dielectric ceramic, and the electrical characteristics as a capacitor do not deteriorate, resulting in high reliability. In addition, since the semiconductor layer can be formed on the end face of the bonding interface between the internal electrode and the dielectric ceramic, it protects the bonding interface, increases the adhesion strength at the end face of the bonding interface, and forms a conductive layer (external electrode). When bending stress or impact force is applied,
No cracks or the like occur at the bonding interface, and peeling of the coating is also prevented. Therefore, the deterioration of the multilayer ceramic capacitor is reduced and its life is maintained for a long time.

[Brief explanation of drawings]

The drawings show embodiments of the present invention. FIG. 1 is a central vertical sectional view showing an example of a multilayer ceramic capacitor, FIG. 2 is a plan view showing an example of a dielectric ceramic before lamination, and FIG.
FIG. 3 is an exploded perspective view of the one in the figure when dielectric ceramics are laminated. Fig. 4 is a central vertical cross-sectional view showing another example of a multilayer ceramic capacitor, Fig. 5 is a plan view showing another example of a dielectric ceramic before lamination, and Fig. 6 is a dielectric ceramic laminate of the one shown in Fig. 5. FIG. DESCRIPTION OF SYMBOLS 1... Multilayer ceramic capacitor, 2... Dielectric ceramic, 3... Internal electrode, 5... Semiconductor layer, 6...
... External electrode, 7... Plating film, 8... Plating film. Patent applicant Murata Manufacturing Co., Ltd.

Claims (6)

[Claims] 1. On the end face of a laminated dielectric ceramic consisting of a plurality of dielectric ceramic layers and a plurality of internal electrode layers arranged in a laminated state with each other via the dielectric ceramic layers to form a capacitance, A multilayer ceramic capacitor characterized in that a semiconductor layer is formed to be connected to a predetermined internal electrode layer, and a conductive layer is further formed on the semiconductor layer. 2. 2. The multilayer ceramic capacitor according to claim 1, wherein the semiconductor layer is formed of a semiconducting agent that converts the dielectric ceramic layer into a semiconductor. 3. 2. The multilayer ceramic capacitor according to claim 1, wherein the semiconductor layer is formed of ceramic powder contained in the dielectric ceramic layer containing a semiconductor agent. 4. 2. The multilayer ceramic capacitor according to claim 1, wherein the conductive layer is formed of a baked layer of conductive paste containing conductive metal powder as a main component. 5. 2. The multilayer ceramic capacitor according to claim 1, wherein the conductive layer is formed of a plating layer. 6. 5. The multilayer ceramic capacitor according to claim 4, further comprising a plating layer formed on the baked layer.