JP2003272906A - Ceramic element and manufacturing method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a deterioration in elemental ceramic body caused by a plating solution and a soldering flux. <P>SOLUTION: The elemental laminated ceramic body 1 having Pd internal electrodes 2 and 3 is formed and an AlxOy protective film is formed on the whole outer peripheral surface of the body 1. Then Ag conductor layers 14 and 15 for external electrodes are formed by applying Ag paste to both end faces of the body 1 and their vicinities and baking the paste. When the Ag paste is baked, the internal electrodes 2 and 3 cause volume expansion and are electrically connected to external electrodes 4 and 5 by penetrating the protective film 6. The protective film 6 remains under the external electrodes 4 and 5. A silicone resin layer 7 is provided on the protective film 6, and plated-Ni layers 16 and 17 and plated-Sn layers 18 and 19 are successively formed on the Ag conductor layers 14 and 15, respectively. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a ceramic element such as a ZnO laminated varistor and a method for manufacturing the same.

[0002]

2. Description of the Related Art A ZnO laminated varistor is an element body containing ZnO as a main component, one internal electrode embedded in the element body and led to one side surface of the element body, and an element body embedded in the element body. The other internal electrode led to the other side surface of the element body, the one external electrode arranged on one side surface of the element body, and the other external electrode arranged on the other side surface of the element body. The external electrodes include a conductor layer formed by applying and baking a conductive paste and a metal layer formed by plating on the conductor layer to improve solderability.

[0003]

By the way, since the ZnO particles of the ZnO laminated varistor are made into semiconductors, they are easily dissolved in acid and oxygen defects are easily generated. Therefore, the insulation resistance of the varistor, that is, IR, is deteriorated by the reduction action of the solder flux when the plating layer of the external electrode is formed and when the varistor element is mounted on the circuit board. This kind of deterioration can be prevented to some extent by forming a protective film having acid resistance, insulation and denseness on the exposed surface of the ceramic body. However, in the conventional ceramic element, since the protective film is formed only on the exposed surface of the ceramic body, the plating solution and the solder flux may enter from the boundary between the protective film and the external electrode, which may cause deterioration. there were. Although the conventional ZnO laminated varistor has been described above, similar problems occur in other ceramic elements such as a ceramic laminated capacitor and a ceramic laminated thermistor. Further, there is a problem that a good quality protective film cannot be easily formed.

Therefore, an object of the present invention is to provide a ceramic element capable of favorably preventing deterioration and a method for manufacturing the same. Another object of the present invention is to provide a ceramic element and a method for manufacturing the same, in which a good quality protective film can be easily formed.

[0005]

SUMMARY OF THE INVENTION To solve the above problems and achieve the above objects, the present invention provides a ceramic body and an end face exposed at a part of the outer peripheral surface of the ceramic body. Internal electrodes embedded in the element body and formed of a material having a property of expanding in volume by heating, and formed so as to cover the entire outer peripheral surface of the ceramic element body and broken by the protrusion of the internal electrodes A protective film having a portion, and the internal electrode disposed so as to cover a part of the outer peripheral surface of the ceramic body through the protective film and protruding from the broken portion of the protective film. The present invention relates to a ceramic element including an external electrode electrically connected to the ceramic element.

As described in claim 2, it is desirable that the protective film is made of AlxOy, where aluminum and aluminum oxide can be represented by x and y being arbitrary numerical values. Further, as described in claim 3, it is preferable that the internal electrode is a Pd electrode. Further, as described in claim 4, it is preferable that the resin film further has a resin layer that covers a portion of the protective film which is not covered by the external electrode. Further, as set forth in claim 5, a ceramic body, an internal electrode embedded in the ceramic body so as to have an end face exposed at a part of the outer peripheral surface of the ceramic body, and an outer periphery of the ceramic body. An external electrode arranged on a surface and connected to the internal electrode, and arranged to cover the ceramic body and AlxOy, where x and y can be represented by arbitrary numerical values. It is possible to form a ceramic element having a protective film made of a material and a silicone resin layer covering the protective film. Further, as described in claim 6, the external electrode is formed by applying a conductive paste and baking it, and by plating the first conductive layer on the first conductive layer. It is desirable to have the formed second conductor layer. Further, as described in claim 7, it is desirable that the ceramic body is a body containing ZnO as a main component for forming a varistor. Further, as described in claim 8, a material which is embedded in the ceramic body so as to have a ceramic body and an end face exposed at a part of an outer peripheral surface of the ceramic body and has a property of expanding in volume by heating. A step of preparing a ceramic element chip having formed internal electrodes; and a protective film having a thickness that covers the entire outer peripheral surface of the ceramic element chip and has a thickness capable of being pierced by expansion of the internal electrodes. And a step of applying an external electrode paste so as to cover a part of the outer peripheral surface of the ceramic body through the protective film, and an external electrode is formed by baking the external electrode paste. At the same time, a step of breaking a part of the protective film by the internal electrode in which the internal electrode is expanded in volume, and electrically connecting the internal electrode and the external electrode, Therefore, it is desirable to produce ceramic element. Further, as described in claim 9, it is preferable that the method further comprises a step of forming a metal layer on the surface of the external electrode by a plating method. Further, as described in claim 10, a step of further forming a resin layer so as to cover a portion of the protective film which is not covered by the external electrode, and a metal layer on the surface of the external electrode by a plating method. And the step of forming. Further, as described in claim 11, the protective film is made of AlxO.
It is desirable that y be an oxide of aluminum that can be represented by y, where x and y are arbitrary numerical values. Further, as described in claim 12, it is preferable that the protective film is formed by a high frequency sputtering method. In addition, claim 13
It is desirable that the protective film is formed by chemical vapor deposition, as shown in FIG.

The ceramic body according to the present invention is various well-known ceramic body for varistor, ceramic body for capacitor, ceramic body for thermistor and the like. The internal electrodes according to the present invention are preferably Pd or palladium electrodes, but other electrode materials such as Pd-Ag electrodes can also be used. The protective film according to the present invention is preferably an oxide of aluminum which can be represented by AlxOy, but if it has a protective function, allows the inner electrode to protrude, and remains under the outer electrode, Other materials may be used. The external electrode according to the present invention is formed of a material that does not absorb the protective film by reacting with the protective film. The resin layer according to the present invention is preferably a silicone resin layer,
A polymer resin having a similar function can also be used.

[0008]

According to the inventions of claims 1 to 4 and 8 to 13, the following effects can be obtained. (1) The entire outer peripheral surface of the ceramic body is covered with a protective film except for the portion that is broken by the protrusion of the internal electrode, and the protective film is also interposed between the external electrode and the ceramic body. For this reason, it is possible to favorably prevent the invasion of the plating liquid, the solder flux, and the like at the boundary between the external electrode and the ceramic body, which may occur in the conventional ceramic element. (2) Since the protective film is broken by the protrusion due to the expansion of the internal electrode, the protective film does not interfere with the electrical connection between the internal electrode and the external electrode. Further, according to the inventions of claims 5 to 7, it is possible to favorably prevent infiltration of a substance that causes deterioration due to a combination of the protective film made of AlxOy and the silicone resin.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a ZnO laminated varistor as a ceramic element according to an embodiment will be described with reference to FIGS.

As shown in FIGS. 1 and 2, this varistor can obtain varistor characteristics, a porcelain element body, that is, a ceramic element body 1, first and second internal electrodes 2, 3, and a first varistor element.
And the second outer electrodes 4 and 5, the protective film 6, and the silicon resin layer 7.

The ceramic body 1 is made of, for example, Pr ₆ O ₁₁ or Co with respect to a main component made of ZnO, that is, zinc oxide.
The varistor characteristics are obtained by laminating and firing a green sheet, ie, an unsintered porcelain sheet, which is formed by adding sub-components of O, CaCO ₃ , SrCO ₃ , SiO ₂ , and Al ₂ O _3. Have. The ceramic body 1 includes first and second main surfaces 8 and 9 facing each other and first, second and third main surfaces.
And a fourth side surface 10, 11, 12, 13, which is a hexahedron or a rectangular parallelepiped.

The two first internal electrodes 2 and the two second internal electrodes 3 are embedded in the ceramic body 1 so as to face each other with a part of the ceramic body 1 interposed therebetween. The first internal electrode 2 has an end face exposed from the first side face 10 of the ceramic body 1. The second internal electrode 3 is the ceramic body 1.
Has an end face exposed from the second side face 11. The first and second inner electrodes 2, 3 are made of Pd, that is, palladium.

The first and second external electrodes 4 and 5 cover the first and second side surfaces 8 and 9 of the ceramic body 1 which face each other with a protective film 6 in between and the first and second main surfaces. It is also formed so as to cover a part of 8 and 9 and a part of the third and fourth side faces 12 and 13. The first and second internal electrodes 2 and 3 rupture a part of the protective film 6 and project outward, and
Are electrically connected to the external electrodes 4, 5. The first and second external electrodes 4 and 5 include the baked conductor layers 14 and 15, the first plating layers 16 and 17, and the second plating layers 18 and 19.
It consists of and. The baked conductor layers 14 and 15 are formed by applying Ag paste and baking. First plating layer 16, 1
7 is a Ni (nickel) layer, which is a second plating layer 18,
19 is a Sn (tin) layer.

The protective film 6 protects the ceramic element body 1 from the plating liquid and the solder flux, and the whole outer peripheral surface of the ceramic element body 1, that is, the first and second main surfaces 8 and 9 and the first and second main surfaces.
~ It is formed so as to cover the fourth side surfaces 10 to 13.
The protective film 6 is made of AlxOy, where x and y are oxides of aluminum which can be represented by arbitrary numerical values. AlxOy of the protective film 6 is RF (high frequency) sputtering or CVD using Al ₂ O ₃ as a target.
That is, it can be formed by a chemical vapor deposition method, and x has a value of 2 or smaller than 2, and y has a value of 3 or smaller than 3. The protective film 6 according to the present invention has relatively good insulating properties, acid resistance, and denseness, and has a characteristic that it is not easily melted with respect to the external electrodes 4 and 5. Also,
The protective film 6 has a thickness that can be broken by the protrusion due to the expansion of the first and second internal electrodes 2 and 3 when the baked conductor layers 14 and 15 are formed, preferably 0.05 to 2 μm, and more preferably 0. 1 to 1.0 μm.

The silicone resin layer 7 is arranged so as to cover the portions of the protective film 6 which are not covered with the external electrodes 4 and 5.
As illustrated in FIG. 6 in an enlarged manner for explanation, not only on the surface of the protective film 6 but also inside the protective film 6 and the defective portion 20 of the protective film 6 are filled. The composite layer portion of the protective film 6 made of AlxOy and the silicone resin layer 7 is superior in acid resistance, insulating property and denseness to the case of only the AlxOy film.

[0016]

[First Manufacturing Method] When manufacturing the laminated varistor containing ZnO as a main component shown in FIGS. 1 and 2, first, a green sheet containing ZnO as a main component is prepared. That is, Pr ₆ O ₁₁ , C as a sub-component is added to ZnO as a main component.
_{oO, CaCO 3, SrCO 3,} SiO 2, Al 2 O 3 wet ball those added the desired amount - mixed 16 h at mill to obtain a ceramic raw material powder and dried.

Next, a slurry was prepared by mixing the above ceramic raw material powder with an organic binder, an organic solvent and an organic plasticizer for 20 hours in a ball mill.

Then, a 30 .mu.m thick green sheet was formed on the PET film by a well-known doctor blade method for making sheets using the above slurry and cut into a predetermined size.

In order to form the internal electrodes 2 and 3, a Pd paste composed of Pd powder, a solvent and an organic binder is prepared, and the Pd paste is cut into a predetermined pattern on the cut green sheet. Printed on the screen and shown in Figures 2 and 3
Pd sheet so that a laminated body of 1 and internal electrodes 2 and 3 can be obtained.
A green sheet on which a strike was printed and a green sheet on which a strike was not printed were laminated, heat-pressed and then cut into a predetermined shape to prepare a green chip.

Next, the green chip is subjected to a binder removal treatment at 300 ° C. for 2 hours, and then fired at 1200 ° C. for 2 hours in the air, that is, in an oxidizing atmosphere, and the ceramic made of sintered porcelain. The body 1 was obtained. Internal electrodes 2 and 3 are exposed on the first and second side faces 10 and 11 of the ceramic body 1 as shown in FIG.

Next, the surface of the ceramic body 1 including the internal electrodes 2 and 3 is smoothed by a well-known barrel polishing method.

Next, the ceramic body 1 is rotated by a known drum.
Put in a transfer type RF sputter device, Al ₂O₃As a target
Then, sputter is performed, and as shown in FIG.
1. A protective film 6 made of aluminum oxide on the entire outer peripheral surface of 1.
To form. The protective film 6 is made of AlxOy, where x and
y is an aluminum compound represented by an arbitrary numerical value.
Note that x and y are arbitrary values selected from x ≦ 2 and y ≦ 3.
It is desirable to be a numerical value. The protective film 6 is made of ceramic material.
It has acid resistance, insulation and compactness to protect body 1.
In addition, the protrusion of the internal electrodes 2 and 3 is allowed.
In order to satisfy the above conditions, the thickness of the protective film 6 is preferable.
0, 05-2 μm, more preferably 0.1
The range is 1.0 μm. Before the sputtering process, the ceramic
Barrel-polishing the element body 1 to obtain a surface with less unevenness
Therefore, the protective film 6 is well formed on the ceramic body 1.
It

Next, the baked conductor layers 14 of the external electrodes 4 and 5,
In order to form No. 15, a well-known Ag paste composed of Ag (silver) powder, a solvent, an organic binder, and a glass frit is prepared, and the Ag paste is passed through the protective film 6 to form the ceramic body 1. All of the first and second side faces 10 and 11, the first and second main faces 8 and 9, and the third and fourth side faces 12 and 1.
3 to a part thereof, and preferably 500 to
A baking process is performed at a temperature of 720 ° C. selected from 800 ° C. for about 8 minutes to obtain baked conductor layers 14 and 15 shown in FIG. By the way, Pd forming the internal electrodes 2 and 3 has a property that it is oxidized by heating and then reduced. Therefore, when the baking treatment of Ag paste is performed in air or in an oxidizing atmosphere, the volumetric expansion of the internal voltages 2 and 3 occurs due to the oxidation of Pd, and the internal electrodes 2 and 3 have the first and second side surfaces. Projecting from 10 and 11 and breaking the protective film 6,
The alloy layers are formed in contact with the g conductor layers 14 and 15, and the internal electrodes 2 and 3 are electrically connected to the Ag conductor layers 14 and 15. In this baking process, the protective film 6 made of AlxOy remains in the conductor layers 14 and 15 without being melted. It has been confirmed by EPMA analysis method, that is, electron probe microanalysis method that the protective film 6 remains between the Ag conductor layers 14 and 15 and the ceramic body 1.

Next, in order to enhance the denseness of the protective film 6,
The ceramic body 1 having the protective film 6 is placed in a solution obtained by diluting a resin, for example, a silicone resin with a solvent such as toluene, and the voids of the protective film 6 are filled with the resin. When there is a defective portion 19 as shown in (1), a resin is filled in this portion, and thereafter, the silicone resin layer 7 is formed by performing air drying and heat curing treatment.

Next, the silicone resin layer formed on the external electrode conductor layers 14 and 15 is removed. External electrode layer 1
When the resin layer is not formed on the layers 4 and 15, this step can be omitted.

Next, Ni is formed by the well-known barrel plating method.
The first plated layers 16 and 17 made of Sn and the second plated layer made of Sn
Plating layers 18 and 19 are sequentially formed to complete the ceramic element of FIG.

[0027]

[Second Manufacturing Method] In the first manufacturing method described above, the protective film 6 is formed by RF sputtering, but it can be formed by CVD, that is, chemical vapor deposition method. Protective film 6 by CVD
At the time of forming, the ceramic body 1 with the internal electrodes 2 and 3 is placed on a plate of a known CVD film forming apparatus, and preferably 400 to 600 ° C., more preferably 500.
Heat to about ℃, tri-poropoxyaluminum + N2
A raw material gas composed of Al 2 O 3 is sprayed to form a protective film 6 composed of AlxOy. The thickness of the protective film 6 is preferably 0.05
˜2 μm, more preferably 0.1 to 1 μm, most preferably 0.2 to 0.5 μm. The procedure is the same as that of the first manufacturing method except for the formation of the protective film 6.

In order to obtain the preferable range of the thickness of the protective film 6, the thickness of the protective film 6 is changed in the range of 0 to 2.5 μm, and the defect occurrence rate (%) of the protective film 6 and the solder reflow after the reflow are performed. The change rate (%) of IR (insulation resistance) and the failure rate (%) of connection to an external circuit were obtained. This will be described in detail below.

The occurrence of defects in the protective film 6 is caused by the first and second A
It was judged whether or not the plating liquid penetrates into the defective portion of the protective film 6 between the g conductor layers 14 and 15 and reaches the ceramic body 1. Therefore, the protective film defect occurrence rate can be called the plating elongation occurrence rate. The defect rate of this protective film is defined as the protective film 6
When the thickness was changed and the measurement was performed, the results shown in Table 1 below were obtained.

Table 1 Protective film thickness (μm) Defect occurrence rate (with resin layer) (%) 0 --------------------------- 100 0.03 ------------------------- 40 0.05 --------------------- -------- 0 0.1 ---------------------------- 0 0.3 ---------- ------------------ 0 0.5 ---------------------------- 0 0.7 ---------------------------- 0 1 -------------------- --------- 0 1.5 ---------------------------- 0 2 --------- ------------------- 0 2.5 ---------------------------- 0

When the protective film defect occurrence rate in the case where the resin layer 7 was not provided was measured while changing the thickness of the protective film 6, the results shown in the following Table 2 were obtained.

Table 2 Protective film thickness (μm) Defect occurrence rate (without resin layer) (%) 0 --------------------------- 100 0.03 ------------------------- 90 0.05 --------------------- -------- 0 0.1 ---------------------------- 0 0.3 ---------- ------------------ 0 0.5 ---------------------------- 0 0.7 ---------------------------- 0 1 -------------------- --------- 0 1.5 ---------------------------- 0 2 --------- ------------------- 0 2.5 ---------------------------- 0

First, when the laminated varistor having both the protective film 6 and the resin layer 7 is fixed to the circuit board by solder reflow.
The change rate (%) of IR (insulation resistance) between the second external electrodes 4 and 5 was measured by changing the thickness of the protective film 6, and the results shown in Table 3 below were obtained. The rate of change in IR indicates the ratio of IR before reflow and IR after reflow.

Table 3 Protective film thickness (μm) IR change rate (with resin layer) (%) 0 --------------------------- − 0.03 -------------------------- −60 0.05 ------------------- -------- −6 0.1 ---------------------------- 0 0.3 --------- ------------------- 0 0.5 ---------------------------- 0 0.7 ---------------------------- 0 1 ------------------- ---------- 0 1.5 ---------------------------- 0 2 -------- -------------------- 0 2.5 ---------------------------- 0

The rate of change in IR (%) between the first and second external electrodes 4 and 5 when the laminated varistor provided only with the protective film 6 without providing the resin layer 7 is fixed to the circuit board by solder reflow. ) Was measured while changing the thickness of the protective film 6, and the results shown in Table 4 below were obtained.

Table 4 Protective film thickness (μm) IR change rate (without resin layer) (%) 0 --------------------------- − 0.03 -------------------------- −98 0.05 ------------------- ---------- −10 0.1 ---------------------------- −0.5 0.3 ------ ---------------------- −0.5 0.5 ------------------------- --- −0.5 0.7 ---------------------------- −0.5 1 ------------- ---------------- −0.5 1.5 ---------------------------- −0.5 2 ---------------------------- −0.5 2.5 ------------------- --------- −0.5

The contact failure rate (%) of the connection of the laminated varistor having the protective film 6 and the resin layer 7 to the circuit board by solder reflow was measured by changing the thickness of the protective film 6, and the results shown in Table 5 below. was gotten.

Table 5 Protective film thickness (μm) Contact failure rate (with resin layer) (%) 0 --------------------------- -0 0.03 --------------------------- 0 0.05 ------------------ ----------- 0 0.1 ---------------------------- 0 0.3 ------- --------------------- 0 0.5 --------------------------- -0 0.7 ---------------------------- 0 1 ----------------- ------------ 0 1.5 ---------------------------- 0 2 ------ ---------------------- 0 2.5 -------------------------- -- Five

The contact failure rate (%) of the connection by solder reflow on the circuit board of the laminated varistor provided with only the protective film 6 without providing the resin layer 7 was measured by changing the thickness of the protective film 6, The results shown in Table 6 were obtained.

Table 6 Protective film thickness (μm) Contact failure rate (without resin layer) (%) 0 --------------------------- --- 0 0.03 ----------------------------- 0 0.05 -------------- --------------- 0 0.1 ---------------------------- 0 0.3 --- ------------------------- 0 0.5 ----------------------- ----- 0 0.7 ---------------------------- 0 1 ------------- ---------------- 0 1.5 ---------------------------- 0 2- -------------------------- 0 2.5 ---------------------- ------ Five

From the above Tables 1 to 6, the thickness of the protective film 6 is 0.
It is understood that the thickness is preferably 05 to 2 μm, more preferably 0.1 to 1 μm. In addition, in Tables 1 to 6 above,
Although the case where the protective film 6 is formed by RF sputtering is shown, the same results as in Tables 1 to 6 were obtained when the protective film 6 was formed by CVD.

This embodiment has the following effects. (1) The protective film 6 made of AlxOy is provided not only on the portions of the ceramic body 1 where the external electrodes 4 and 5 are not formed, but also below the external electrodes 4 and 5. Therefore,
The protection at the boundary between the portion where the external electrodes 4 and 5 are formed and the portion where the external electrodes are not formed is well achieved. That is, the processing liquid penetrates into the ceramic body 1 when forming the first and second plating layers 16, 17, 18, and 19 and the solder flux ceramic body 1 when the varistor is mounted on the circuit board. Of the ceramic body 1 is effectively prevented
It is possible to prevent deterioration of characteristics and the like. (2) The internal electrodes 2, 3 and the external electrodes 4, 5 are electrically connected to each other when the Ag conductor layers 14, 15 are baked.
This electrical connection can be easily achieved since it is achieved by the protrusion of (3) Since the silicone resin layer 7 is formed on the protective film 6 of AlxOy and the voids of the protective film 6 are filled with resin, the protective function can be greatly improved. (4) Since the protective film 6 is formed by the RF sputtering method or the CVD method, the target protective film 6 can be formed relatively easily.

[0043]

MODIFICATION The present invention is not limited to the above-described embodiment, and the following modifications are possible, for example. (1) The materials of the internal electrodes 2 and 3 may be different as long as they can obtain the same action as Pd. The internal electrodes 2 and 3 may contain Pd as a main component and another metal as an auxiliary component. (2) The protective film 6 may be a substance other than AlxOy as long as it can satisfy the requirements of the present invention. (3) The conductor layers 14 and 15 of the external electrodes 4 and 5 may be Ag-Pd paste or the like other than Ag. (4) The composite structure of the AlxOy protective film 6 and the silicone resin layer 7 can also be applied as a protective layer of a ceramic element in which the protective film 6 is not provided below the external electrodes 4 and 5. (5) The present invention can be applied to ceramic elements such as ceramic multilayer capacitors and ceramic multilayer thermistors other than ZnO varistor. (6) The resin layer 7 may be a polymer resin having a similar function other than silicone.

[Brief description of drawings]

FIG. 1 is a plan view showing a ZnO laminated varistor according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a cross-sectional view showing a ceramic body with a protective film formed thereon.

FIG. 4 is a cross-sectional view showing a structure in which an Ag conductor layer is formed.

FIG. 5 is a cross-sectional view showing the one in which a silicone resin layer 7 is formed.

FIG. 6 is an enlarged view illustrating a part of a protective film 6 and a silicone resin layer 7 of FIG. 5 in an explanatory manner.

[Explanation of symbols]

1 Ceramic body A few internal electrodes 4,5 external electrodes 6 protective film 7 Silicone resin layer 8, 9 Main surface 10, 11, 12, 13 Sides 14, 15 Ag conductor layer 16, 17 First plating layer 18, 19 Second plating layer

Continued front page    F-term (reference) 5E034 CA10 CB01 CC02 DA07 DB03                       DB05 DC03 DC05 DC09 DE07                       DE16

Claims (13)

[Claims] 1. An interior formed of a ceramic body and a material having a property of being volume-expanded by being embedded in the ceramic body so as to have an end surface exposed at a part of an outer peripheral surface of the ceramic body. An electrode, a protective film formed so as to cover the entire outer peripheral surface of the ceramic body, and having a portion broken by the protrusion of the internal electrode; and a ceramic film of the ceramic body via the protective film. A ceramic element comprising an external electrode which is arranged so as to cover a part of an outer peripheral surface and which is electrically connected to the internal electrode protruding from the broken portion of the protective film. 2. The protective film is made of AlxOy, where x
2. The ceramic element according to claim 1, wherein y and y are made of an oxide of aluminum which can be represented by any numerical value. 3. The ceramic element according to claim 1, wherein the internal electrode is a Pd electrode. 4. The ceramic element according to claim 1, further comprising a resin layer that covers a portion of the protective film that is not covered by the external electrode. 5. A ceramic body, internal electrodes embedded in the ceramic body so as to have an end surface exposed at a part of the outer peripheral surface of the ceramic body, and arranged on the outer peripheral surface of the ceramic body. An external electrode connected to the internal electrode, and AlxO arranged so as to cover the ceramic body.
y, where x and y are arbitrary numerical values, a ceramic having a protective film made of an aluminum oxide and a silicone resin layer covering the protective film. element. 6. The external electrode comprises a first conductor layer formed by applying and baking a conductive paste, and a second conductor layer formed on the first conductor layer by plating. 6. The ceramic element according to any one of claims 1 to 5, further comprising: 7. The ceramic element according to claim 1, wherein the ceramic body is a body containing ZnO for forming a varistor as a main component. 8. An interior formed of a material which is embedded in the ceramic body so as to have a ceramic body and an end face exposed at a part of an outer peripheral surface of the ceramic body and has a property of expanding in volume by heating. A step of preparing a ceramic element chip provided with an electrode, and a step of forming a protective film so as to cover the entire outer peripheral surface of the ceramic element chip and have a thickness capable of being pierced by expansion of the internal electrode. A step of applying an external electrode paste so as to cover a part of an outer peripheral surface of the ceramic body through the protective film; and an external electrode formed by baking the external electrode paste, and at the same time the internal electrode Volume-expanding to break a part of the protective film by the internal electrode, and electrically connecting the internal electrode and the external electrode. A method of manufacturing a ceramic element, comprising: 9. The method of manufacturing a ceramic element according to claim 8, further comprising the step of forming a metal layer on the surface of the external electrode by a plating method. 10. A step of forming a resin layer so as to cover a portion of the protective film which is not covered by the external electrode, and a step of forming a metal layer on the surface of the external electrode by a plating method. 9. The method for manufacturing a ceramic element according to claim 8, further comprising: 11. The protective film is AlxOy, wherein:
11. The method for manufacturing a ceramic element according to claim 8, wherein x and y are made of an aluminum oxide which can be represented by any numerical value. 12. The method of manufacturing a ceramic element according to claim 11, wherein the protective film is formed by a high frequency sputtering method. 13. The method of manufacturing a ceramic element according to claim 11, wherein the protective film is formed by a chemical vapor deposition method.