JP4752327B2 - Dielectric ceramic composition and multilayer ceramic capacitor - Google Patents

Description

  The present invention relates to a dielectric ceramic composition and a multilayer ceramic capacitor. More specifically, the present invention relates to a dielectric ceramic composition and a multilayer ceramic that have high reliability for use under a direct current high voltage or a high frequency alternating current high voltage. Concerning capacitors.

  Conventionally, multilayer ceramic capacitors have often been used under low frequency AC low voltage or DC low voltage. However, along with the development of electronics, in recent years, electronic components have been rapidly downsized, and multilayer ceramic capacitors have been reduced in size and capacity. Therefore, the electric field applied between a pair of counter electrodes of a ceramic capacitor tends to be relatively high. Under such conditions, the capacity is increased, the loss is reduced, the insulation is improved, and the reliability is improved. Is strongly demanded.

  Thus, for example, Patent Document 1 proposes a dielectric ceramic composition and a multilayer ceramic capacitor that can withstand use under a high frequency / high voltage AC high voltage or a DC high voltage.

The reduction-resistant dielectric ceramic described in Patent Document 1 is represented by the general formula ABO ₃ + aR + bM (ABO ₃ is a general formula representing a barium titanate solid solution, R is La, Ce, Pr, Nd, Sm, Eu, Gd. , Tb, Dy, Ho, Er, Tm, Yb and Lu, M is at least one oxide selected from Mn, Ni, Mg, Fe, Al, Cr and Zn), A / B (molar ratio), a and b are in the range of 1.000 <A / B ≦ 1.035, 0.005 ≦ a ≦ 0.12, 0.005 ≦ b ≦ 0.12 It contains 0.2 to 4.0 parts by weight of a sintering aid with respect to 100 parts by weight. The dielectric ceramic composition further comprises X (Zr, Hf) O ₃ (X is at least one selected from Ba, Sr and Ca) in an amount of 0.20 mol part or less with respect to 1 mol part of the barium titanate solid solution, and / Or D (D is at least one oxide selected from V, Nb, Ta, Mo, W, Y, Sc, P, Al, and Fe) in an amount of 0.20 mole part per mole of barium titanate solid solution. The following may be included. Further, this dielectric ceramic composition has a crystal axis ratio c / a obtained by X-ray diffraction in the temperature range of −25 ° C. or higher of 1.000 ≦ c / a ≦ 1.003 and 2 Vrms / at a frequency of 1 kHz. The maximum value of the relative permittivity with respect to temperature change when an AC electric field of less than or equal to mm is less than −25 ° C., and low loss and low heat generation under high frequency and / or high voltage AC high voltage, Stable insulation resistance with AC or DC voltage load.
JP 2002-50536 A

  The dielectric ceramic composition proposed in Patent Document 1 is excellent in reliability under high frequency AC high voltage or DC high voltage.

  However, the demand for further miniaturization and larger capacity of the multilayer ceramic capacitor will continue to increase, and it is expected that the applied electric field will be higher in frequency and higher in use than ever before. Therefore, it is an urgent issue to improve characteristics and reliability under such use conditions.

  In particular, the demand for higher guaranteed maximum temperature of multilayer ceramic capacitors is stronger than ever, and the dielectric ceramic composition described in Patent Document 1 has an insufficient insulation resistivity ρ at 150 ° C. It is also an important issue to improve.

  The present invention has been made in view of the above-described circumstances, and its purpose is to be used under high-frequency AC high voltage or DC high voltage even if miniaturization and capacity increase further proceed in the future. An object of the present invention is to provide a dielectric ceramic composition that generates little heat, has a high insulation resistivity ρ at a high temperature, and has a dielectric constant that is not inferior to that of the prior art, and a multilayer ceramic capacitor using the dielectric ceramic composition.

That is, the dielectric ceramic composition of the present invention has a general formula: (Ba _1−x Ca _x ) _m TiO ₃ −t (Ba _1−x Ca _x ) _m ZrO ₃ (where 0 ≦ x ≦ 0.20, 99 ≦ m ≦ 1.05, 0.2 ≦ t ≦ 0.4) as a main component, and with respect to 100 mol parts of (Ba _1-x Ca _x ) _m TiO _{3 in the} main component. , Mn is 0.5 to 3.5 mol part, Re (Re is at least selected from Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. 1 to 3 mol parts, 1 to 7 mol parts of Mg, and 0.8 parts of SiO ₂ with respect to 100 parts by weight of (Ba _1-x Ca _x ) _m TiO _{3 in the} main component. comprising 5 parts by weight, further characterized in that has no free of Sr.

  The present invention is further directed to a multilayer ceramic capacitor configured using the dielectric ceramic composition as described above.

  The multilayer ceramic capacitor of the present invention includes a plurality of laminated dielectric ceramic layers, internal electrodes disposed between the dielectric ceramic layers, and external electrodes electrically connected to the internal electrodes. The dielectric ceramic layer is formed of the dielectric ceramic composition of the present invention.

  In the multilayer ceramic capacitor, it is preferable that the internal electrode is formed of a conductive material mainly composed of Ni or an alloy thereof, or Cu or an alloy thereof.

  According to the dielectric ceramic composition of the present invention, even if the size and capacity are further increased in the future, the heat generation under use under a high DC voltage or high frequency AC high voltage is small, and at a high temperature. It is possible to provide a multilayer ceramic capacitor having a high insulation resistivity and a dielectric constant that is not inferior to that of the prior art.

  First, a multilayer ceramic capacitor, which is the main use of the dielectric ceramic of the present invention, will be described. FIG. 1 is a cross-sectional view showing a general multilayer ceramic capacitor 1.

  The multilayer ceramic capacitor 1 includes a rectangular parallelepiped ceramic multilayer body 2. The ceramic laminate 2 includes a plurality of laminated dielectric ceramic layers 3 and a plurality of internal electrodes 4 and 5 formed along an interface between the plurality of dielectric ceramic layers 3. The internal electrodes 4 and 5 are formed so as to reach the outer surface of the ceramic laminate 2, but are drawn to the internal electrode 4 and the other end surface 7 that are drawn to one end face 6 of the ceramic laminate 2. The internal electrodes 5 are alternately arranged inside the ceramic laminate 2 so that electrostatic capacity can be obtained via the dielectric ceramic layer 3.

  The conductive material of the internal electrodes 4 and 5 is preferably a base metal material that is low cost, that is, nickel or a nickel alloy, copper or a copper alloy.

  In order to take out the above-described capacitance, on the outer surface of the ceramic laminate 2 and on the end faces 6 and 7, so as to be electrically connected to any one of the internal electrodes 4 and 5, External electrodes 8 and 9 are respectively formed. As the conductive material contained in the external electrodes 8 and 9, the same conductive material as that of the internal electrodes 4 and 5 can be used, and silver or a silver alloy can also be used. The external electrodes 8 and 9 are formed by applying and baking a conductive paste obtained by adding glass frit to such metal powder.

  Further, first plating layers 10 and 11 made of nickel, copper or the like are formed on the external electrodes 8 and 9 as required, and a second plating layer made of solder, tin or the like is further formed thereon. Plating layers 12 and 13 are formed, respectively.

  Next, the composition of the dielectric ceramic composition of the present invention will be described.

The main component of the dielectric ceramic composition of the present invention is the general formula: (Ba _1−x Ca _x ) _m TiO ₃ −t (Ba _1−x Ca _x ) _m ZrO ₃ (where 0 ≦ x ≦ 0 .20, 0.99 ≦ m ≦ 1.05, 0.2 <t ≦ 0.4). The compound represented by this general formula is a solid solution mainly composed of a perovskite structure. That is, in the Ti site in the same ceramic particle, Ti and Zr are almost uniformly mixed so that Zr becomes t mol part with respect to Ti 1 mol part. However, ceramic particles made of (Ba _1-x Ca _x ) _m TiO ₃ and ceramic particles made of (Ba _1-x Ca _x ) _m ZrO ₃ are partially mixed within a range not impairing the object of the present invention. You may be in the state.

In addition, the dielectric ceramic composition of the present invention has, as an accessory component, Mn of 0.5 to 3.5 mol parts, Re (Re is Y) with respect to 100 mol parts of (Ba _1-x Ca _x ) _m TiO _3. , La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) 3-12 mol parts, Mg 1-7 mol Contains. Further, 0.8 to 5 parts by weight of SiO ₂ is contained with respect to 100 parts by weight of (Ba _1-x Ca _x ) _m TiO ₃ .

  The position of these subcomponents is not particularly limited. That is, it may exist at the grain boundary or may be dissolved in the solid solution of the main component. When present at the grain boundary, it exists mainly in the form of an oxide.

Furthermore, the dielectric ceramic composition of the present invention is substantially free of Sr. “Substantially not contained” indicates that it may be contained as long as it is mixed as an unavoidable impurity. Specifically, the content of Sr is preferably less than 1 mol part with respect to 100 mol parts of the main component. In the dielectric ceramic of the present invention, when the content of Sr is 1 mol part or more with respect to 100 mol parts of (Ba _1-x Ca _x ) _m TiO ₃ , the insulation resistivity ρ at 150 ° C. is less than 10 ⁹ Ωm. Become. In addition, this Sr has the effect | action which reduces (rho) irrespective of the presence position.

  From the above, the dielectric ceramic of the present invention is characterized by a high content ratio of Zr to Ti in the main component. The coexistence of Zr and Mg is considered to act to maintain a high insulation resistivity even at high temperatures.

In addition, since the effect | action of this Mg will be inhibited if there exists a CaO component in a grain boundary, it is desirable that CaO does not exist. If the content of CaO is 1 mol part or more with respect to 100 mol parts of (Ba _1-x Ca _x ) _m TiO ₃ , the insulation resistivity ρ at 150 ° C. is less than 10 ⁹ Ωm. However, Ca substituted for the Ba site of the main component does not participate in the above inhibitory action.

  Next, the reason for limiting the composition range of the dielectric ceramic composition of the present invention will be described.

The molar ratio m of Ba site to Ti site in the main component of the dielectric ceramic composition satisfies 0.99 ≦ m ≦ 1.05. When m is less than 0.99, the insulation resistivity ρ at 150 ° C. is as low as less than 10 ⁹ Ω · m. When m exceeds 1.05, the mean failure time (MTTF) in a high temperature load test (170 ° C., DC electric field strength 40 kV / mm) is as short as less than 100 hours.

  The Ca content ratio x in the Ba site of the main component satisfies 0 ≦ x ≦ 0.2 in terms of molar ratio. When x exceeds 0.20, the dielectric constant ε becomes as low as less than 300.

The molar ratio t of (Ba, Ca) ZrO ₃ to 1 mol part of (Ba, Ca) TiO ₃ satisfies 0.2 ≦ t ≦ 0.4. When t is less than 0.2, the insulation resistivity ρ at 150 ° C. is as low as less than 10 ⁹ Ω · m. When t exceeds 0.4, the dielectric constant ε is as low as less than 300.

The content a of Mn with respect to 100 mol parts of (Ba _1-x Ca _x ) _m TiO ₃ satisfies 0.5 ≦ a ≦ 3.5 in molar ratio. When a is less than 0.5, the MTTF in the high temperature load test is as short as less than 100 hours. On the other hand, if a exceeds 3.5, the insulation resistivity ρ at 150 ° C. becomes as low as less than 10 ⁹ Ω · m.

The Mg content b with respect to 100 mol parts of (Ba _1-x Ca _x ) _m TiO ₃ satisfies 1 ≦ b ≦ 7 in terms of molar ratio. When b is less than 1, the insulation resistivity ρ at 150 ° C. is as low as less than 10 ⁹ Ω · m. On the other hand, when b exceeds 7, the dielectric constant becomes as low as less than 300, and the MTTF in the high temperature load test becomes as short as less than 100 hours.

The content c of Re with respect to 100 mole parts of (Ba _1-x Ca _x ) _m TiO ₃ satisfies 3 ≦ c ≦ 12 in terms of molar ratio. When c is less than 3, the MTTF in the high temperature load test is shortened to less than 100 hours. When c exceeds 12, the dielectric constant is as low as less than 300, the insulation resistivity ρ is as low as less than 10 ⁹ Ω · m, and the MTTF in the high temperature load test is as short as less than 100 hours. In addition, this Re is composed of at least one element selected from Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and two kinds. There may be a case where the above elements are appropriately selected and combined, and any of these may be used.

In addition, the dielectric ceramic composition of the present invention contains parts by weight of SiO ₂ satisfying 0.8 ≦ d ≦ 5.0 with respect to 100 parts by weight of (Ba _1-x Ca _x ) _m TiO ₃ described above. ing. When d is less than 0.8, stable sintering becomes difficult, and when d exceeds 5.0, the insulation resistivity ρ at 150 ° C. is as low as less than 10 ⁹ Ω · m, and the MTTF in the high temperature load test is 100. Less than less time. Since SiO ₂ acts as a sintering aid, it exists mainly as a glass component at the grain boundary.

The dielectric ceramic composition of the present invention preferably further contains at least one selected from Ni and Zn. The presence of these elements further improves the insulation resistivity ρ at 150 ° C. As for the content with respect to 100 mol parts of (Ba _1-x Ca _x ) _m TiO ₃ , the total amount e of Ni, Zn and Mg is preferably 7 mol parts or less. When the total of Ni, Zn, and Mg exceeds 7 mol parts, the dielectric constant ε becomes as low as less than 300.

  A part of the Zr component in the main component of the present application may be substituted with Hf. This is because the action of Hf in the dielectric ceramic composition of the present invention is almost equivalent to Zr.

  Next, the manufacturing method of the dielectric ceramic composition of this invention is demonstrated.

The method for producing the main component powder of the dielectric ceramic composition is not particularly limited as long as it can realize the ceramic composition represented by the composition formula. For example, a dry synthesis method in which a mixture of starting materials is calcined and subjected to a solid phase reaction can be used. In addition, a wet synthesis method such as a hydrothermal synthesis method, a hydrolysis method, or a sol-gel method can be used. In addition, (Ba _1-x Ca _x ) _m TiO ₃ powder and (Ba _1-x Ca _x ) _m ZrO ₃ powder are separately prepared, and a mixture thereof may be used as the main component raw material powder. , Ca, Ti, and Zr starting materials may be mixed at the same time and synthesized to be used as the main component raw material powder. These starting materials are generally oxides, carbonates and the like, but are not limited to these as long as they can constitute the dielectric ceramic composition according to the present invention.

In addition, oxide powders are mainly used as starting materials for the subcomponents Re, Mn, Mg, Ni, Zn, and SiO ₂ , which can constitute the dielectric ceramic composition according to the present invention. If present, the oxide powder is not particularly limited. For example, carbonate powder or a solution of an alkoxide or an organic metal may be used as a starting material.

  Subcomponents can be added to and mixed with the main component raw material powder as described above to form a ceramic raw material powder. Moreover, as long as the object of the present invention is not impaired, the starting material of the subcomponent may be mixed simultaneously with the starting material of the main component raw material powder.

  Using the ceramic raw material powder prepared as described above, the multilayer ceramic capacitor 1 as shown in FIG. 1 can be manufactured by the same method as the method for manufacturing a ceramic multilayer capacitor that is usually performed. That is, ceramic raw material powder is mixed and dispersed in a solvent together with a binder to form a slurry, and this slurry is formed into a sheet by a method such as a doctor blade method to obtain a ceramic green sheet. A paste containing the component of the internal electrode is applied to this ceramic green sheet, and this is stacked and pressure-bonded to obtain a raw laminate. By firing this raw laminate, the ceramic laminate 2 is obtained. Thereafter, as described above, an external electrode paste is applied and baked, and a plating film is formed thereon as necessary to form an external electrode. The multilayer ceramic capacitor 1 is obtained as described above.

As described above, the multilayer ceramic capacitor using the dielectric ceramic composition of the present invention has a dielectric constant of 300 or more, an insulation resistivity at 150 ° C. of 10 ⁹ Ωm or more, and when a high-frequency AC high voltage is applied (300 kHz The dielectric loss at 10 kVp-p / mm is 0.5% or less, and the average failure time in the high-temperature load test (170 ° C., DC electric field strength 40 kV / mm) is 100 hours or more, and the reliability is high.

  Example 1 In this example, a multilayer ceramic capacitor 1 as shown in FIG. 1 was produced.

First, as starting materials for (Ba _1-x Ca _x ) _m TiO ₃ and (Ba _1-x Ca _x ) _m ZrO ₃ as the main components, each of high-purity BaCO ₃ , CaCO ₃ , TiO ₂ and ZrO ₂ is used. Powders were prepared, and the respective starting material powders were prepared so that a Ca modification amount x shown in Table 1 below and a molar ratio m of (Ba, Ca) to Ti were obtained.

  The blended powder was wet-mixed using a ball mill and uniformly dispersed, and then subjected to a drying treatment to obtain a adjusted powder.

The obtained adjusted powder is calcined at a temperature of 1000 ° C. or higher, and satisfies (Ba _1-x Ca _x ) _m TiO ₃ powder satisfying x and m in Table 1, and (Ba _1-x Ca _x ) _m ZrO _3. A powder was obtained.

Further, the (Ba _1-x Ca _x ) _m TiO ₃ powder and the (Ba _1-x Ca _x ) _m ZrO ₃ powder were prepared so as to satisfy a ratio satisfying t in Table 1. At the same time, as starting materials for the auxiliary components, MnCO ₃ , MgCO ₃ , NiO, ZnO, SiO ₂ , Y ₂ O ₃ , La ₂ O ₃ , CeO ₂ , Pr ₅ O ₁₁ , Nd ₂ O ₃ , Sm ₂ O ₃ , Prepare powders of Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ and Lu ₂ O ₃ The composition represented by a, b, c, d and e shown in Table 1 was prepared.

  Next, this blended powder was wet-mixed using a ball mill and uniformly dispersed, and then subjected to a drying treatment to obtain a ceramic raw material powder of a dielectric ceramic composition.

  Next, a polyvinyl butyral binder and an organic solvent mainly composed of ethanol were added to the ceramic raw material powder, and wet mixed by a ball mill to prepare a ceramic slurry.

  The ceramic slurry is formed into a sheet by a doctor blade method to obtain a ceramic green sheet having a thickness of 14 μm, and a conductive paste mainly composed of Ni is printed on the ceramic green sheet by a screen printing method to constitute an internal electrode. A conductive paste film was formed.

Next, a plurality of ceramic green sheets were laminated so that the side from which the conductive paste film was drawn out was staggered as shown in FIG. 1 to obtain a laminate before firing. The laminate before firing was heated to a temperature of 350 ° C. in a nitrogen gas atmosphere to burn the binder, and then mixed with H ₂ —N ₂ —H ₂ O having an oxygen partial pressure of 10 ⁻⁹ to 10 ⁻¹² MPa. The laminate before firing was fired at a temperature shown in Table 2 for 2 hours in a reducing atmosphere composed of gas, whereby a ceramic laminate 2 was obtained.

On the other hand, an Ag paste containing B ₂ O ₃ —SiO ₂ —BaO-based glass frit was prepared and applied to both end surfaces of the laminate where the internal electrodes 8 and 9 were exposed. Next, the Ag paste is baked at a temperature of 600 ° C. in an N ₂ atmosphere, and the first and second external electrodes 4 and 5 electrically connected to the first and second internal electrodes 8 and 9 are stacked. 3 is formed on both end faces, and then the first and second external electrodes 4 and 5 are plated in two stages to form the first plating layers 6 and 7 and the second plating layers 10 and 11. A multilayer ceramic capacitor 1 was obtained.

The outer dimensions of the multilayer ceramic capacitor 1 thus obtained are 3.2 mm in width, 4.5 mm in length, and 0.5 mm in thickness, and the thickness of the dielectric ceramic layer interposed between adjacent internal electrodes. Was 10 μm. In addition, the total number of dielectric ceramic layers effective in obtaining the capacitance was 5, and the area of the counter electrode per layer was 2.5 × 10 ⁻⁶ m ² . The following electrical characteristics were evaluated for the multilayer ceramic capacitors of Sample Nos. 1 to 65 obtained as described above, and the results are shown in Table 2.

  In Tables 1 and 2, samples marked with * are outside the scope of the present invention. When there were two or more types of Re element, the element name and the breakdown of the content molar ratio were described. Similarly, when Ni and Zn were contained at the same time, the breakdown of the content was described.

Next, an evaluation method and an evaluation result of the electrical characteristics of the multilayer ceramic capacitor will be shown.
A) Dielectric constant (ε) and dielectric loss (tan δ)
For the samples shown in Table 1, each of the capacitance (C) and dielectric loss (tan δ) was measured by applying a signal voltage of 50 Vrms / mm at 1 kHz using an automatic bridge-type measuring device. The dielectric constants (ε) were calculated based on the measured values and the structure of each multilayer ceramic capacitor, and the results are shown in Table 2.
B) Insulation resistivity at 150 ° C. (ρ)
For the samples in Table 1, using an insulation resistance meter, each sample was applied with a DC voltage of 300 V for 1 minute to obtain an insulation resistance value at 150 ° C., and an insulation resistivity (ρ) was calculated. It was shown in 2.
C) Mean failure time (MTTF)
As a high-temperature load test for the samples in Table 1, a DC voltage of 400 V was applied to each sample at a temperature of 170 ° C., and the change over time in each insulation resistance was measured. At this time, in the high-temperature load test, when the insulation resistance value of each sample was 10 ⁶ Ω or less, it was determined that a failure occurred, and the average failure time of each was determined. The results are shown in Table 2.
D) Dielectric loss (tanδ) when high frequency AC high voltage is applied
For the samples shown in Table 1, dielectric loss (tan δ) was measured by applying a signal voltage of 10 kVp-p / mm at 300 kHz in order to evaluate the heat generation when a high frequency was applied. The results are shown in Table 2.

In the sample of Sample No. 1, since the molar ratio m of Ba site to Ti site is less than 0.990, the insulation resistivity ρ at 150 ° C. is as low as less than 10 ⁹ Ω · m, and the MTTF in the high temperature load test is 100 It was less than an hour. In the sample of Sample No. 7, since m exceeded 1.050, MTTF in the high temperature load test was less than 100 hours, and tan δ under an alternating electric field of 300 kHz was larger than 0.5%.

  The sample No. 13 has a Ca content molar ratio x of more than 0.20 at the Ba site, so that the dielectric constant ε is less than 300, the MTTF in the high-temperature load test is less than 100 hours, and an alternating current of 300 kHz. The tan δ under electric field was greater than 0.5%.

Since the sample of sample number 14 did not contain Mn, the insulation resistivity ρ at 150 ° C. was very low, and characteristics such as capacitance could not be measured. Sample No. 15 had an MTTF of less than 100 hours in the high temperature load test because the molar part a of Mn was less than 0.5 with respect to 100 parts by mole of (Ba _1-x Ca _x ) _m TiO ₃ . Further, in the sample of sample number 19, since a exceeded 3.5, the insulation resistivity ρ at 150 ° C. was very low, and characteristics such as capacitance could not be measured.

In the sample No. 20, the molar ratio t of (Ba, Ca) ZrO _{3 to} (Ba, Ca) TiO ₃ is 0.20 or less, so that the insulation resistivity ρ at 150 ° C. is less than 10 ⁹ Ω · m. The MTTF in the low and high temperature load test was less than 100 hours. Further, the sample of sample number 25 had a dielectric constant ε as low as less than 300 because t exceeded 0.40, and the MTTF in the high temperature load test was less than 100 hours.

The sample No. 26 had an MTTF in a high temperature load test of less than 100 hours because the Re mole part c was less than 3 with respect to 100 mole parts of (Ba _1-x Ca _x ) _m TiO ₃ . In the sample of sample number 31, since c exceeds 12, the dielectric constant ε is as low as less than 300, the insulation resistivity ρ at 150 ° C. is as low as less than 10 ⁹ Ω · m, and the MTTF in the high temperature load test is 100. It was less than an hour.

Sample No. 32 has a Si weight part d of less than 0.8 with respect to 100 parts by weight of (Ba _1-x Ca _x ) _m TiO ₃ , and thus does not sinter sufficiently even when the firing temperature is 1300 ° C. It was. In the sample of sample number 37, since d exceeds 5, the insulation resistivity ρ at 150 ° C. is as low as less than 10 ⁹ Ω · m, and the MTTF in the high temperature load test is less than 100 hours.

The sample No. 55 has a very low insulation resistivity ρ at 150 ° C. because the molar part b of Mg is less than 1 with respect to 100 molar parts of (Ba _1-x Ca _x ) _m TiO ₃ , capacitance, etc. It was not possible to measure the characteristics. Further, the sample of sample number 59 had a dielectric constant ε as low as less than 300 because b exceeded 7, and the MTTF in the high temperature load test was less than 100 hours.

Sample No. 63 has a dielectric constant of less than 300 because the total molar part e of Ni, Zn, and Mg exceeds 7 molar parts relative to 100 molar parts of (Ba _1-x Ca _x ) _m TiO _3. It was.

Sample No. 64 contains Sr as an impurity in an amount of 1 mol part per 100 mol parts of (Ba _1-x Ca _x ) _m TiO _3, so that the insulation resistivity ρ at 150 ° C. is less than 10 ⁹ Ω · m. And tan δ under an alternating electric field of 300 kHz was greater than 0.5%.

Sample No. 65 contains 1 mole part of CaO with respect to 100 mole parts of (Ba _1-x Ca _x ) _m TiO _3, so the insulation resistivity ρ at 150 ° C. is as low as less than 10 ⁹ Ω · m. Tan δ under an AC electric field of 300 kHz was greater than 0.5%.

Other samples within the scope of the present invention have a dielectric constant ε of 300 or more, an insulation resistivity ρ at 150 ° C. of 10 ⁹ Ω · m or more, and an MTTF in a high temperature load test of 100 hours or more. The tan δ under an alternating electric field of 300 kHz was 0.5% or less.

  In addition, this invention is not restrict | limited at all to the said Example.

It is sectional drawing which shows one Embodiment of the multilayer ceramic capacitor of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multilayer ceramic capacitor 2 Dielectric ceramic layer 3 Laminated body 4, 5 1st, 2nd external electrode 6, 7 1st plating layer 8, 9 1st, 2nd internal electrode 10, 11 2nd plating layer

Claims (4)

General formula: (Ba _1−x Ca _x ) _m TiO ₃ −t (Ba _1−x Ca _x ) _m ZrO ₃ (where 0 ≦ x ≦ 0.20, 0.99 ≦ m ≦ 1.05, 0.0 2 ≦ t ≦ 0.4) as a main component,
With respect to 100 mol parts of (Ba _1-x Ca _x ) _m TiO ₃ in the main component, 0.5 to 3.5 mol parts of Mn and Re (Re is Y, La, Ce, Pr, Nd, Sm, Eu) , Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu), 3-12 mol parts, Mg 1-7 mol parts,
And 0.8 to 5 parts by weight of SiO ₂ with respect to 100 parts by weight of (Ba _1-x Ca _x ) _m TiO ₃ in the main component,
Further, containing no dielectric ceramic composition Sr. It contains at least one of Ni and Zn, and the total content of Ni, Zn and Mg with respect to 100 mol parts of (Ba _1-x Ca _x ) _m TiO _{3 in the} main component is 7 mol parts or less. Item 2. The dielectric ceramic composition according to Item 1. A multilayer ceramic capacitor comprising a multilayer body including a plurality of multilayered dielectric ceramic layers and internal electrodes formed along interfaces between the plurality of dielectric ceramic layers,
3. The multilayer ceramic capacitor according to claim 1, wherein the dielectric ceramic layer is made of the dielectric ceramic according to claim 1. The multilayer ceramic capacitor according to claim 3, wherein the internal electrode is formed of a conductive material mainly composed of Ni or Ni alloy, or Cu or Cu alloy.