JP2002367850A - Mold type ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold type ceramic electronic component represented by a mold type ceramic capacitor that does not have any variation in electric characteristics before and after resin molding, has improved characteristic stability in a load life test, and further improved reliability as a safe standard product. SOLUTION: The mold type ceramic electronic component is a mold type ceramic electronic component where a ceramic dielectric element has been buried by an exterior finish material. In the ceramic dielectric element, the crystal phase of the main constituent is a paraelectric phase or an antiferroelectric phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is widely applied to primary and secondary snubber circuits for switching power supplies, ballast circuits for LCD backlight inverters, other high voltage circuits for surface mounting, and surge circuits for communication modems. The present invention relates to a molded ceramic electronic component represented by a molded ceramic capacitor to be used.

[0002]

2. Description of the Related Art In Europe, it has been required to use a ceramic capacitor (safety standard product) for medium and high voltage having a high reliability in a surge circuit for a communication modem in a surge circuit. This is becoming a global standard.

Under such a trend of surface mounting and high reliability, a ceramic capacitor having a resin mold has been studied. By embedding the ceramic dielectric element in the resin, the ceramic capacitor with this resin mold suppresses the creeping discharge under high voltage and the deterioration of characteristics due to humidity. It has an advantage over it. For example, a multilayer ceramic capacitor having a resin mold is disclosed in JP-A-05-226177.

[0004]

However, conventional resin-molded ceramic capacitors have been designed in consideration of fluctuations in electric characteristics before and after resin molding and adverse effects on reliability due to embedding with resin. It was hard to say. That is, the conventional resin-molded ceramic capacitor has a problem that the electric characteristics fluctuate before and after the ceramic dielectric element is molded with the resin, and the capacitance is remarkably lowered in a load life test after the molding. I was

For example, when spontaneous polarization exists in a crystal phase constituting a main component of a ceramic dielectric element molded with a resin and has ferroelectricity, the piezoelectric effect causes the crystal phase before and after the resin molding. The electrical characteristics fluctuated greatly, and the degree of the fluctuation was not constant and could not be adjusted on a mass production basis. Further, the capacitance is significantly reduced in a reliability test in a state where an electric field is applied, that is, in a so-called load life, and the reliability cannot be guaranteed for a user.

Accordingly, the present invention has been made to solve the above-mentioned problems, and there is no change in electrical characteristics before and after resin molding, has excellent characteristic stability in a load life test, and is excellent as a safety standard product. It is an object of the present invention to provide a molded ceramic electronic component represented by a molded ceramic capacitor having high reliability.

[0007]

Means for Solving the Problems In order to solve this problem, a molded ceramic electronic component of the present invention is a molded ceramic electronic component in which a ceramic dielectric element is embedded with an exterior material. The crystal phase of the main component is a paraelectric phase or an antiferroelectric phase.

As a result, a molded ceramic capacitor having no change in electrical characteristics before and after the resin molding and having excellent characteristic stability in a load life test can be obtained.

[0009] Further, by making the fine structure of the ceramic dielectric element to be molded into a core-shell structure, even if a ferroelectric portion exists in the crystal phase of the main component, before and after the resin molding and a load life test. Thus, a molded ceramic capacitor having excellent stability can be obtained.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a mold-type ceramic electronic component in which a ceramic dielectric element is embedded with an exterior material. A molded ceramic electronic component characterized by being a paraelectric phase or an antiferroelectric phase, wherein a difference between an electrical characteristic after molding the ceramic dielectric element and an electrical characteristic before molding is obtained. In addition, since it has excellent characteristic stability in a load life test, it has an effect of realizing a molded ceramic electronic component typified by a molded ceramic capacitor which is excellent in mass productivity and can guarantee high reliability.

This is because when the crystal phase constituting the main component of the ceramic dielectric element is a paraelectric phase, there is no spontaneous polarization which causes a piezoelectric effect in the crystal, and the crystal phase has an anti-strong phase. In the case of the dielectric phase, spontaneous polarization is present but cancels each other out due to the directional effect, so that the spontaneous polarization is equal to zero as a whole. Therefore, even if a stress is applied to the ceramic dielectric element by resin molding, a piezoelectric phenomenon does not occur, so that there is no change in electrical characteristics, and stable load life characteristics and high reliability can be obtained. is there.

According to a second aspect of the present invention, there is provided a molded ceramic electronic component in which a ceramic dielectric element is embedded with an exterior material, wherein the fine structure of the ceramic dielectric element is a core-shell structure. This is a molded ceramic electronic component characterized by the following characteristics, which has the effect of realizing a molded ceramic electronic component typified by a high-performance and high-reliability molded ceramic capacitor without variation in electrical characteristics before and after molding. .

Although the details will be described later, when the fine structure of the ceramic dielectric element has a core-shell structure as shown in FIG. 1, the ferroelectric phase forming the core portion of the crystal particle is the same as the crystal particle. Since the structure is covered with the paraelectric phase or the antiferroelectric phase forming the shell portion of the above, the piezoelectric phenomenon caused by the ferroelectric phase hardly occurs.

According to a third aspect of the present invention, in the first and second aspects, the ceramic dielectric element is a single-plate type ceramic dielectric element having a pair of electrodes formed on both surfaces thereof. A molded ceramic electronic component characterized by having a certain characteristic, and can correspond to a low capacity.

According to a fourth aspect of the present invention, in the first and second aspects of the present invention, in the ceramic dielectric element, the ceramic dielectric layers and the internal electrode layers are alternately laminated to expose the internal electrode layers. This is a laminated ceramic electronic component characterized by being a laminated ceramic dielectric element having a pair of external electrodes formed on both end surfaces, and can correspond to a high capacity.

The ceramic dielectric element can be selectively used according to the nominal capacitance value in the product development. A single-plate type ceramic dielectric element is used for a low-capacity product, and a laminated ceramic dielectric element is used for a high-capacity product. Use ceramic dielectric elements. Therefore, it is needless to say that a molded ceramic capacitor having no variation in electrical characteristics before and after the molding and having excellent characteristic stability in a load life test can be realized, but a product lineup according to a user's request is possible. .

The ceramic dielectric element constituting such a molded ceramic electronic component of the present invention will be described.

The crystal phase of the main component of the ceramic dielectric element is a paraelectric phase or an antiferroelectric phase. For example, a dielectric composition such as strontium titanate-calcium titanate can be used, and SrTiO ₃ —Ca
TiO ₃ -based powder and additives Dy ₂ O ₃ , Y ₂ O ₃ , Zr
O _2, can be obtained by firing at least one or more and BaO-CaO-SiO ₂ based sintering aid component selected from among MgO and Mn ₃ O _4, conventionally known crystalline phase always A dielectric ceramic which is a dielectric phase or an antiferroelectric phase can be used.

Alternatively, in the ceramic dielectric element constituting the molded ceramic electronic component of the present invention, the fine structure of the ceramic dielectric element is such that the ferroelectric phase forming the core portion of the crystal grains has:
Similarly, it has a core-shell structure covered with a paraelectric phase or an antiferroelectric phase forming a shell part of crystal grains. That is, even if the crystal phase of the main component of the ceramic dielectric element is not a paraelectric phase or an antiferroelectric phase, the core part is a ferromagnetic phase and the shell part is a paraelectric phase or an antiferroelectric phase. Any core-shell structure made of a ferroelectric phase may be used. For example, a dielectric composition such as barium titanate is used, and specifically, BaTiO as a main component is used.
₃ powder and at least one selected from additives Dy ₂ O ₃ , MgO and Mn ₃ O ₄ , and BaO—CaO—
It can be obtained by sintering the SiO ₂ -based sintering aid component, but it is a dielectric material that becomes crystal grains composed of a ferroelectric phase part in the core and a paraelectric phase (or antiferroelectric phase) part in the shell Ceramic can be used.

The core-shell structure will be described.
Here, FIG. 1 is a schematic diagram showing a core-shell structure in the ceramic dielectric element of the present invention.
Reference numeral 11 denotes a crystal grain, 12 denotes a paraelectric phase, and 13 denotes a ferroelectric phase.

As shown in FIG. 1, in the case of having a core-shell structure, the ferroelectric phase 13 forming the core of the crystal grain 11 always forms the shell of the crystal grain 11. The structure is covered with the dielectric phase 12 (or antiferroelectric phase), so that the piezoelectric phenomenon caused by the ferroelectric phase 13 is hardly developed.

Hereinafter, the molded ceramic electronic component of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG. 2 is a sectional view showing a molded ceramic electronic component according to Embodiment 1 of the present invention. In FIG. 2, reference numeral 20 denotes a molded ceramic electronic component, 21 denotes a ceramic dielectric element, 22
Reference numerals a, 22b, and 22c denote internal electrode layers; 23, a ceramic dielectric layer; 24, a lower external electrode; 25, an upper external electrode;
6 is an exterior material, and 27 is a terminal.

As shown in FIG. 2, the molded ceramic electronic component 20 is an effective capacitance acquisition layer formed by alternately stacking ceramic dielectric layers 23 and internal electrode layers 22a, 22b, 22c. A ceramic dielectric layer 23 is laminated as an ineffective layer above and below the layers, and furthermore, an internal electrode layer 2 is formed.
Internal electrode layers 22 are provided on both end surfaces where 2c and 22b are exposed.
A lower external electrode 24 electrically connected to the upper and lower electrodes 22b and 22c is provided. An upper external electrode 25 is provided on the lower external electrode 24, and the ceramic dielectric element 21 is formed. Then, conductive terminals 27 are drawn out from both ends of the ceramic dielectric element 21 embedded in the exterior material 26 made of a thermosetting resin, and can be surface-mounted on a circuit board via the terminals 27. Is done.

As described above, the ceramic dielectric layer 23 has a crystal phase of a main component being a paraelectric phase or an antiferroelectric phase, or has a core portion made of a ferromagnetic phase and a shell portion made of a ferromagnetic phase. A dielectric ceramic having a core-shell structure composed of a paraelectric phase or an antiferroelectric phase is used.

The internal electrode layers 22a, 22b, 22c
Precious metals such as g and Pd, or base metals can be used. Cu, Ni, or the like can be used as the base metal, and Ni or a Ni alloy is preferable.

The lower external electrode 24 is also made of Ni or Ni.
Preferably, it is an alloy.

The upper external electrode 25 is preferably made of Ag, and Ni and Sn may be sequentially plated and laminated on the upper external electrode 25.

As the exterior material 26, a material having an insulating property is used, and glass, an insulating resin, or the like can be used. Among these, an insulating resin is preferable because it is suitable for processing and inexpensive, and a thermosetting resin is more preferable because it is suitable for processing, and a thermosetting epoxy resin is particularly preferable because it is excellent in strength and moisture resistance. Epoxy resins such as optocresol novolak, biphenyl, pentadiene and the like can be used.

As the terminal 27, a conductive material can be used, but a metal material that is preferably selected from at least one of Fe, Cu, and Ni is preferably used. It is advantageous in terms of.

(Embodiment 2) FIG. 3 is a sectional view showing a molded ceramic electronic component according to Embodiment 2 of the present invention. In FIG. 3, reference numeral 30 denotes a molded ceramic electronic component, and reference numeral 31 denotes a ceramic dielectric component. A body element, 32 is an electrode, 33 is an exterior material, and 34 is a terminal.

As shown in FIG. 3, electrodes 32 are formed on both main surfaces of the ceramic dielectric element 31. And
Conductive terminals 34 are drawn out from electrodes 32 formed on both main surfaces of the ceramic dielectric element 21 embedded in the exterior material 33, and are configured to be surface-mounted on a circuit board via the terminals 34.

As described above, in the ceramic dielectric element 31, the crystal phase of the main component is a paraelectric phase or an antiferroelectric phase, or the core is a ferromagnetic phase and the shell is a ferromagnetic phase. Core composed of dielectric or antiferroelectric phase
A dielectric ceramic having a shell structure is used.

As the electrode 32, for example, Ag,
At least one metal selected from Cu, Ni, and Zn can be used, and a multilayer structure of these metals may be used.

As the exterior material 33, a material having an insulating property is used, and glass, an insulating resin, or the like can be used. Among these, an insulating resin is preferable because it is suitable for processing and inexpensive, and a thermosetting resin is more preferable because it is suitable for processing, and a thermosetting epoxy resin is particularly preferable because it is excellent in strength and moisture resistance. Epoxy resins such as optocresol novolak, biphenyl, pentadiene and the like can be used.

As the terminal 34, a conductive material can be used, but a metal material that is preferably selected from at least one of Fe, Cu, and Ni is suitably used, and the electrical characteristics and workability are preferably used. It is advantageous in terms of.

[0037]

Next, the present invention will be described in detail with reference to examples. The present invention is not limited at all by the following examples and the like.

Example 1 In Example 1, a molded ceramic capacitor in which a laminated ceramic dielectric element, which is a typical example of a molded ceramic electronic component, was embedded in a resin was manufactured and evaluated. In addition, regarding the manufacturing method of the molded ceramic capacitor, and the variation of the electrical characteristics before and after the molding and the result of the load life test,
The description will be made in connection with the crystal phase constituting the main component of the ceramic dielectric element.

First, the main component SrTiO ₃ —CaT
iO ₃ -based powder and additives Dy ₂ O ₃ , Y ₂ O ₃ , Zr
A predetermined amount of at least one or more selected from O ₂ , MgO and Mn ₃ O ₄ and a BaO—CaO—SiO ₂ sintering aid component is weighed by an electronic balance, and a 5 mmφ ZrO ₂ ball is obtained. It was thrown into the contained monomalon pot mill. Next, after mixing at a rotation speed of 100 rpm for 20 hours, the mixture was filtered through a 150 mesh silk screen,
It was put into a stainless steel vat covered with a Teflon (registered trademark) sheet and dried at a temperature of 120 ° C. The dried mass was pulverized in an alumina mortar and then passed through a 32 mesh nylon sieve to obtain a slurry powder.

Next, a predetermined amount of the slurry powder was wetted by mixing with a solvent and a plasticizer. After wetting, a vehicle made of polyvinyl butyral resin was mixed to prepare a sheet forming slurry.

Next, the slurry was filtered through a 150-mesh silk screen and then formed into a film having a predetermined thickness to obtain a ceramic green sheet. Then, after the ceramic raw sheet and the internal electrode sheet manufactured from the Ni paste are laminated based on a predetermined lamination specification by a transfer method,
It was cut to obtain a green chip.

Next, after chamfering the obtained green chip, a Ni paste is applied to both end surfaces and dried,
Defatted. Then, firing in a reducing atmosphere was performed using a rotary atmosphere furnace. The calcination was maintained at a temperature of 1275 ° C. for 2 hours in an oxygen partial pressure atmosphere lower than the equilibrium oxygen partial pressure of Ni adjusted by green gas, CO ₂ and N ₂ by about two orders of magnitude.
Then, an Ag paste serving as an upper layer external electrode was applied to both end surfaces of the fired chip, baked in the air, and then Ni plating and Cu plating were applied thereon to complete a ceramic dielectric element. Next, after soldering metal terminals to both end surfaces of the ceramic dielectric element, the main parts of the ceramic dielectric element and the metal terminals are embedded in an epoxy-based thermosetting resin, and the terminal processing is performed. Completed a molded ceramic capacitor. The completed molded ceramic capacitor satisfies the standard value of 4532 size, the rated voltage is 2 KVDC, and the nominal capacitance value is 47 PF.

As shown in FIG. 2, the molded ceramic capacitor of Example 1 was formed by alternately laminating ceramic dielectric layers 23 and internal electrode layers 22a, 22b and 22c containing Ni. A ceramic dielectric layer 23 is laminated as an ineffective layer above and below an effective layer serving as a capacitance acquisition layer, and is electrically connected to the internal electrode layers 22b, 22c at both end surfaces where the internal electrode layers 22C, 22b are exposed. Is provided with a lower layer external electrode 24 made of Ni.
And a ceramic dielectric element 21 was formed. Then, conductive metal terminals 27 are drawn out from both ends of the ceramic dielectric element 21 embedded in the thermosetting resin 26, and are configured to be surface-mounted on a circuit board via the metal terminals 27.

Next, the electrical characteristics of the prototyped molded ceramic capacitor were evaluated in comparison with the electrical characteristics of the dielectric ceramic element before molding. Capacitance (Cap) and dielectric quality factor (Q value) are L made by YHP
The measurement was performed under a signal voltage of 1 V / 1 MHz using a CR meter 4284A. Insulation resistance (IR) is 500VDC using Advantest insulation resistance meter R8340A.
For 1 minute. The dielectric breakdown voltage (BDV) was obtained by measuring the DC breakdown voltage in silicone oil using a Kikusui Electronics pressure gauge. Temperature change rate of capacitance (Cap-T
C) was measured within the range of +10 to + 125 ° C. by connecting a YHP LCR meter 4284A to the thermostat. Capacitance and dielectric loss were each measured for 20 pieces, insulation resistance value and insulation breakdown voltage were each 10 pieces, and temperature change rate was measured for 2 pieces. It was shown to. FIG. 4 shows the temperature change rate of the capacitance (Cap-TC). FIG. 4 is a graph showing a temperature change rate curve of the capacitance of the molded ceramic electronic component in Example 1 of the present invention.

[0045]

[Table 1] As is clear from Table 1, the molded ceramic capacitor of Example 1 was very stable with no change in electrical characteristics before and after the molding.

As is clear from FIG. 4, the shape of the temperature change rate curve of the capacitance hardly fluctuates before and after the mold, and the piezoelectric phenomenon caused by the ferroelectric phase does not appear. found. Furthermore, since the crystal phase constituting the main component is a SrTiO ₃ —CaTiO ₃ system, and the temperature change rate of the capacitance increases to the minus side almost straight with the rise in temperature, In the ceramic dielectric element of the molded ceramic capacitor of Example 1, the crystal phase constituting the main component is a paraelectric phase or an antiferroelectric phase.

Further, when a voltage of 2 KVDC is applied to the molded ceramic capacitor of the first embodiment,
When a load life test was performed in which the capacitor was left at 5 ° C., the rate of change after 1000 hours from the initial value of each of the capacitance value and the insulation resistance value was within ± 5%, indicating perfect reliability. Was.

As described above, according to the present invention, there is no difference between the electric characteristics after molding the ceramic dielectric element and the electric characteristics before molding, and excellent characteristic stability in the load life test. Thus, a molded ceramic electronic component typified by a molded ceramic capacitor that can guarantee high reliability can be realized.

Example 2 In Example 2, as in Example 1, a molded ceramic capacitor in which a laminated ceramic dielectric element, which is a typical example of a molded ceramic electronic component, was embedded in a resin was manufactured. An evaluation was performed.

A BaTiO ₃ powder as a main component, at least one selected from Dy ₂ O ₃ , MgO and Mn ₃ O ₄ as additives and a BaO—CaO—SiO ₂ sintering aid component Is weighed by an electronic balance, and a 5 mmφ Zr
It was thrown into a monomalon pot mill containing O ₂ quality balls. Next, after mixing at a rotation speed of 100 rpm for 20 hours, the mixture was filtered through a 150-mesh silk screen, put into a stainless steel vat covered with a Teflon sheet, and dried at a temperature of 120 ° C. The dried mass was pulverized in an alumina mortar and then passed through a 32 mesh nylon sieve to obtain a slurry powder.

Next, a predetermined amount of the slurry powder was wetted by mixing with a solvent and a plasticizer. After wetting, a vehicle made of polyvinyl butyral resin was mixed to prepare a sheet forming slurry.

Next, the slurry was filtered through a 150-mesh silk screen, and then formed into a film having a predetermined thickness to obtain a ceramic green sheet. Then, after the ceramic raw sheet and the internal electrode sheet manufactured from the Ni paste are laminated based on a predetermined lamination specification by a transfer method,
It was cut to obtain a green chip.

Next, after chamfering the obtained green chip, Ni paste was applied to both end surfaces and dried,
Defatted. Then, firing in a reducing atmosphere was performed using a rotary atmosphere furnace. The firing was maintained at a temperature of 1250 ° C. for 2 hours in an oxygen partial pressure atmosphere lower by about two orders of magnitude than the equilibrium oxygen partial pressure of Ni adjusted by the green gas, CO ₂ and N ₂ .
Then, an Ag paste serving as an upper layer external electrode was applied to both end surfaces of the fired chip, baked in the air, and then Ni plating and Cu plating were applied thereon to complete a ceramic dielectric element. Next, after soldering metal terminals to both end surfaces of the ceramic dielectric element, the main parts of the ceramic dielectric element and the metal terminals are embedded in an epoxy-based thermosetting resin, and the terminal processing is performed. Completed a molded ceramic capacitor. The completed molded ceramic capacitor has a shape satisfying the standard value of 5750 size, and the rated voltage is 250 VAC.
And the nominal capacitance value is 1500 PF.

The fabricated molded ceramic capacitor of the second embodiment has the same structure as that shown in FIG. 2 as in the first embodiment.

The electrical characteristics of the molded ceramic capacitor of Example 2 were evaluated in comparison with the characteristics of the dielectric ceramic element before molding. The capacitance (Cap) and the dielectric loss coefficient (tan δ) are L
The measurement was performed under a signal voltage of 1 V / 1 kHz using a CR meter 4284A. Insulation resistance (IR) is 500VDC using Advantest insulation resistance meter R8340A.
For 1 minute. The dielectric breakdown voltage (BDV) was obtained by measuring the DC breakdown voltage in silicone oil using a Kikusui Electronics pressure gauge. Temperature change rate of capacitance (Cap-T
C) was measured in the range of -55 to + 125 ° C by connecting a YHP LCR meter 4284A to the thermostat. Capacitance and dielectric loss were each measured for 20 pieces, insulation resistance value and insulation breakdown voltage were each 10 pieces, temperature change rate was measured for 2 pieces, average value was calculated and the results are shown in Table 2. Was. FIG. 5 shows the temperature change rate (Cap-TC) of the capacitance. FIG. 5 is a graph showing a temperature change rate curve of the capacitance of the molded ceramic electronic component in Example 2 of the present invention.

[0056]

[Table 2] As is clear from Table 2, the molded ceramic capacitor of Example 2 was very stable with no change in electrical characteristics before and after the molding.

Further, as is apparent from FIG. 5, both the temperature change rate curves of the capacitance before and after the mold show the behavior supporting the typical core-shell structure.
The shape of the curve hardly changes before and after the mold, and the ferroelectric phase core is covered by the paraelectric phase shell. Turned out not to be. Regarding the behavior of the temperature change rate curve of the capacitance, if the crystal phase of the main component is constituted only by the core portion which is a ferroelectric phase, the behavior as shown in FIG. , A sharp peak appears. On the other hand, when the crystal phase of the main component is constituted only by the shell portion which is a paraelectric phase, a fine peak around 125 ° C. as shown in FIG. 5 does not appear. Therefore, it is clear that the fine structure of the ceramic dielectric element of the molded ceramic capacitor of this example has a core-shell structure.

Further, when a voltage of 250 VAC is applied to the molded ceramic capacitor of the second embodiment,
When a load life test was performed in which the capacitor was left at 25 ° C., the rate of change after 1000 hours from the initial value of each of the capacitance value and the insulation resistance value was within ± 6%, indicating perfect reliability. Was.

As described above, according to the present invention, there is no difference between the electric characteristics after molding the ceramic dielectric element and the electric characteristics before molding, and the characteristics are excellent in the load life test when AC is applied. Therefore, a molded ceramic electronic component represented by a molded ceramic capacitor that can guarantee a high degree of reliability as a safety standard product for a high voltage can be realized.

Comparative Example 1 In Comparative Example 1, similarly to Examples 1 and 2, a molded ceramic capacitor in which a laminated ceramic dielectric element, which is a typical example of a molded ceramic electronic component, was embedded in a resin was used. It was fabricated and evaluated.

BaTiO ₃ powder as a main component, CaO, ZrO ₂ and MnO _{2 as} additives and BaO—CaO—S
A predetermined amount of the iO ₂ -based sintering aid component is weighed with an electronic balance,
It was thrown into a monomalon pot mill containing 5 mmφ ZrO ₂ quality balls. Next, after mixing at a rotation speed of 100 rpm for 20 hours, the mixture was filtered through a 150-mesh silk screen, put into a stainless steel vat covered with a Teflon sheet, and dried at a temperature of 120 ° C. The dried mass was pulverized in an alumina mortar and then passed through a 32 mesh nylon sieve to obtain a slurry powder.

Next, a predetermined amount of the slurry powder was wetted by mixing with a solvent and a plasticizer. After wetting, a vehicle made of polyvinyl butyral resin was mixed to prepare a sheet forming slurry.

Next, the slurry was filtered through a 150-mesh silk screen and then formed into a film having a predetermined thickness to obtain a ceramic green sheet. Then, after the ceramic raw sheet and the internal electrode sheet manufactured from the Ni paste are laminated based on a predetermined lamination specification by a transfer method,
It was cut to obtain a green chip.

Next, after the obtained green chip was chamfered, Ni paste was applied to both end surfaces and dried,
Defatted. Then, firing in a reducing atmosphere was performed using a rotary atmosphere furnace. Firing, green gas, and held for 2 hours at a temperature of 1300 ° C. in about two orders of magnitude lower oxygen partial pressure atmosphere than the equilibrium oxygen partial pressure of Ni adjusted by CO ₂ and N _2.
Then, an Ag paste serving as an upper layer external electrode was applied to both end surfaces of the fired chip, baked in the air, and then Ni plating and Cu plating were applied thereon to complete a ceramic dielectric element. Next, after soldering metal terminals to both end surfaces of the ceramic dielectric element, the main parts of the ceramic dielectric element and the metal terminals are embedded in an epoxy-based thermosetting resin, and the terminal processing is performed. Completed a molded ceramic capacitor. The completed molded ceramic capacitor satisfies the standard value of 5750 size, the rated voltage is 50 VDC, and the nominal capacitance value is 10,000 PF.

The manufactured molded ceramic capacitor of Comparative Example 1 has the same structure as that shown in FIG.

The electrical characteristics of the molded ceramic capacitor of Comparative Example 1 were evaluated in comparison with the characteristics of the dielectric ceramic element before molding. The temperature change rate of the capacitance (Cap-TC) was measured in the range of −55 to + 125 ° C. by connecting a YHP LCR meter 4284A to the thermostat. FIG. 6 shows the temperature change rate of the capacitance (Cap−
TC). FIG. 6 is a graph showing a temperature change rate curve of the capacitance of the molded ceramic electronic component in Comparative Example 1 of the present invention.

As is clear from FIG. 6, the shape of the temperature change rate curve of the capacitance before and after the mold fluctuates as compared with Examples 1 and 2, and the piezoelectricity caused by the ferroelectric phase. A phenomenon has also been manifested.

Example 3 In Example 3, a molded ceramic capacitor in which a disc-shaped ceramic dielectric element, which is a typical example of a molded ceramic electronic component, was embedded in a resin was manufactured and evaluated.

A disk-shaped compact was prepared from a powder containing SrTiO ₃ as a main component, and the compact was fired at a predetermined temperature. Electrodes were applied to both surfaces of the fired body to form a disc-shaped ceramic. A dielectric element was obtained. Next, after metal terminals are provided on both end surfaces of the ceramic dielectric element, the main parts of the ceramic dielectric element and the metal terminals are embedded in an epoxy-based thermosetting resin, and terminal processing is performed. A molded ceramic capacitor was completed. The completed molded ceramic capacitor has a rated voltage of 3 KVDC and a nominal capacitance of 22 PF.

As shown in FIG. 3, the molded ceramic capacitor according to the present embodiment has a structure in which conductive metal terminals are connected to electrodes 32 provided at both ends of a ceramic dielectric element 31 embedded in an exterior material 33. 34 is drawn out, and is configured to be surface-mounted on a circuit board via the metal terminal 34.

The molded ceramic capacitor of Example 3 was very stable with no change in electrical characteristics before and after the molding. In addition, it was found that the shape of the temperature change rate curve of the capacitance hardly fluctuated before and after the mold, and that the piezoelectric phenomenon caused by the ferroelectric phase did not appear. Further, the crystal phase constituting the main component is Sr
The ceramic dielectric element of the molded ceramic capacitor according to the present embodiment is a TiO ₃ -based material, and the rate of temperature change of the capacitance increases to the minus side almost directly with the rise in temperature. The crystal phase constituting the main component is a paraelectric phase or an antiferroelectric phase.

Further, with the voltage of 3 KVDC applied to the molded ceramic capacitor of the third embodiment, 125
When a load life test was performed in which the capacitor was left at ℃, the rate of change after 1000 hours from the initial value of each of the capacitance value and the insulation resistance value was within ± 5%, indicating perfect reliability. .

As described above, according to the present invention, there is no difference between the electric characteristics after molding the disk-shaped ceramic dielectric element and the electric characteristics before molding, and the characteristics are excellent in the load life test. It is possible to realize a molded ceramic electronic component represented by a molded ceramic capacitor having stable stability and high reliability.

[0074]

As described above, according to the present invention, a ceramic dielectric element whose main component is composed of a paraelectric phase or an anti-ferroelectric phase is molded in a resin, thereby obtaining a piezoelectric element. No phenomena occur, no fluctuations in electrical characteristics before and after molding, high breakdown voltage, and excellent characteristic stability in load life tests, so low heat generation in high voltage circuits, surge suppression circuits, etc. Thus, an effect is obtained that a molded ceramic electronic component represented by a highly reliable molded ceramic capacitor applied as a safety standard product can be realized.

Further, by molding a ceramic dielectric element having a core-shell structure in a resin into a resin, a piezoelectric phenomenon caused by a ferroelectric phase in a core portion is less likely to be exhibited, and before and after the molding and a load life. Because it has excellent stability in tests, it is possible to realize molded ceramic electronic components typified by highly reliable molded ceramic capacitors that are applied as safety standard products for noise absorption in high voltage circuits, surge suppression circuits, etc. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a core-shell structure of the present invention.

FIG. 2 is a cross-sectional view showing a molded ceramic electronic component according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing a molded ceramic electronic component according to a second embodiment of the present invention.

FIG. 4 is a graph showing a temperature change rate curve of the capacitance of the molded ceramic electronic component in Example 1 of the present invention.

FIG. 5 is a graph showing a temperature change rate curve of the capacitance of the molded ceramic electronic component in Example 2 of the present invention.

FIG. 6 is a graph showing a temperature change rate curve of capacitance of a molded ceramic electronic component in Comparative Example 1 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Crystal particle 12 Paraelectric phase 13 Ferroelectric phase 21 Ceramic dielectric element 22a, 22b, 22c Internal electrode layer 23 Ceramic dielectric layer 24 Lower external electrode 25 Upper external electrode 26 Exterior material 27 Terminal 31 Ceramic dielectric element 32 Electrode 33 Exterior material 34 Terminal

 ──────────────────────────────────────────────────の Continued on the front page (72) Kumayama Kaneyama, Inventor 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Masuhiro Yamamoto 1006 Odaka Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. F term (reference) 5E001 AB01 AB03 AD00 AF06 AG01

Claims (4)

[Claims] 1. A molded ceramic electronic component in which a ceramic dielectric element is embedded with an exterior material, wherein the ceramic dielectric element has a main component crystal phase of a paraelectric phase or an antiferroelectric phase. A molded ceramic electronic component, characterized in that: 2. A molded ceramic electronic component in which a ceramic dielectric element is embedded with an exterior material, wherein the fine structure of the ceramic dielectric element is a core-shell structure. . 3. A molded ceramic electronic device according to claim 1, wherein said ceramic dielectric device is a single-plate ceramic dielectric device having a pair of electrodes formed on both surfaces thereof. parts. 4. The ceramic dielectric element according to claim 1, wherein a ceramic dielectric layer and an internal electrode layer are alternately laminated, and a pair of external electrodes are formed on both end surfaces where the internal electrode layer is exposed. The molded ceramic electronic component according to claim 1, wherein the molded ceramic electronic component is an element.