JP2004107202A - Dielectric porcelain composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonreducing dielectric porcelain composition for temperature compensation, which can be stably fired even under a reducing atmosphere of 1,100-1,300°C, gives markedly increased Q value, and is small in dispersion of the characteristic such as capacitance Cap, dielectric constant ε<SB>s</SB>, temperature characteristic TC or insulating resistance ρ, and which is able to prevent flocculation of glass components. <P>SOLUTION: The dielectric composition contains 1-5 pts. wt. of MnCO<SB>3</SB>, and 0.5-5 pts. wt. of a glass component expressed by general formula: aSiO<SB>2</SB>-bLi<SB>2</SB>O-cB<SB>2</SB>O<SB>3</SB>-dCaO-eBaO (wherein, 0.25≤a≤0.45; 0.05≤b≤0.35; 0.05≤c≤0.15; 0.10≤d≤0.35; 0.10≤e≤0.35, and a + b + c + d + e =1) to 100 pts. wt. of a base component expressed by general formula: (CaO)<SB>x</SB>(Zr<SB>1-y</SB>-Ti<SB>y</SB>)O<SB>2</SB>(wherein, 0.95≤x≤1.05; and 0.01≤y≤0.10). <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a dielectric ceramic composition suitable for a dielectric layer used for a temperature-compensating multilayer ceramic capacitor or the like having a base metal such as Ni as an internal electrode layer.

FIG. 1 is an external perspective view of a general multilayer ceramic capacitor, and FIG. 2 is a cross-sectional view thereof.

Conventionally, when manufacturing a multilayer ceramic capacitor 10, a conductive paste of a noble metal such as Pd or Ag / Pd is printed in a desired pattern on a ceramic green sheet made of a dielectric raw material powder, and a plurality of such pastes are laminated and heated. Crimping, baking in an oxidizing atmosphere at 1200 to 1300 ° C., applying an Ag base electrode, baking at 600 to 800 ° C., applying a plating layer having a two-layer structure of Ni and Sn, Was composed.

However, since the price of Pd has been surprisingly increasing in recent years, the cost of the multilayer ceramic capacitor 10 for temperature compensation, which uses a relatively small amount of Pd, is beginning to affect the cost. For this reason, the base metalization of the internal electrode layers 3 and 4 has conventionally been limited to a large-capacity type such as the BF characteristic in which the number of the internal electrode layers 3 and 4 is large. Is also required.

However, in the structure of the multilayer ceramic capacitor 10 in which the dielectric layers 2 and the internal electrode layers 3 and 4 are alternately stacked, since the Ni internal electrode layers 3 and 4 and the dielectric layer 2 are integrally fired, oxidation of Ni or the like is performed. To prevent the dielectric layer 2 from being reduced even when co-fired in a neutral atmosphere (atmosphere: N ₂ 100%) or a reducing atmosphere (atmosphere: N ₂ + H ₂ several%). Therefore, it is necessary to develop a dielectric material that satisfies various requirements and reliability such as voltage load life.

Therefore, a non-reducing temperature-compensating dielectric ceramic composition in which a glass component (sintering aid) composed of Si-Li-alkaline earth metal is added to a basic component composed of CaZrO ₃ and CaTiO ₃ is proposed. (For example, see Patent Document 1).
Japanese Patent Publication No. 5-52604

However, according to the above-mentioned dielectric porcelain composition, sintering becomes insufficient unless firing treatment is performed at a high temperature of 1350 ° C. to 1380 ° C., and electrical satisfactory characteristics cannot be obtained. However, in the monolithic ceramic capacitor 10, since the dielectric layer 2 and the internal electrode layers 3 and 4 have a monolithic structure, when the firing treatment is performed at such a high temperature, the internal electrode layers 3 and 4 made of Ni or the like are formed. Melting and aggregation occur, and metals such as Ni are distributed in a ball shape. In addition, due to the high-temperature firing, a metal such as Ni diffuses into the dielectric porcelain, causing the insulation resistance of the dielectric layer 2 to deteriorate. As a result, it was difficult to obtain a multilayer ceramic capacitor 10 having a desired capacitance and insulation resistance. In order to solve such a problem, in the material system disclosed in Patent Document 1, a sintering aid composed of Si—Li ₂ O—alkaline earth is used at a temperature of 1200 ° C. or less. At a low temperature up to the sintering temperature range described above to obtain a TC-based Ni multilayer ceramic capacitor satisfying desired characteristics.

However, in the sintering aid composed of this composition system, Li, which is a low-melting element, evaporates remarkably, and unevenness of the porcelain composition generated during firing is remarkably generated, resulting in variations in individual electric characteristics. In addition, as shown in FIG. 3, agglomeration 20 of the glass component is generated inside the dielectric ceramic at almost the same temperature as the evaporation start temperature of the Li element, and as a result, in the operation test in a wet atmosphere, There is a problem that causes deterioration of the Q value.

More specifically, in a temperature range of 1000 ° C. or more under a neutral or reducing atmosphere, Li begins to evaporate, and at the same time, aggregates 20 of glass components begin to exist in the porcelain. This phenomenon is particularly remarkable in a bulk body having a small shape conforming to JIS standard 3216 type or less. Therefore, it has been extremely difficult to perform stable firing with respect to composition fluctuation in porcelain.

The present invention has been made in view of the above circumstances, and has as its object to enable stable firing even in a reducing atmosphere at 1100 ° C. to 1300 ° C., significantly increase the Q value, and increase the capacitance Cap, It is an object of the present invention to provide a non-reducing temperature-compensating dielectric ceramic composition which has a small characteristic variation such as a dielectric constant ε _s , a temperature characteristic TC, and an insulation resistance ρ and can prevent aggregation of glass components.

The dielectric ceramic composition of the present invention has a general formula (CaO) _x (Zr _1-y · Ti _y ) O ₂ (where x and y are expressed in terms of mol, and 0.95 ≦ x ≦ 1.05). , 0.01 ≦ y ≦ 0.10), and 100 parts by weight of the basic component represented by
1 to 5 parts by weight of MnCO ₃ ,
General formula aSiO ₂ -bLi ₂ O-cB ₂ O ₃ -dCaO-eBaO (where a to e are expressed in terms of mol, and 0.25 ≦ a ≦ 0.45, 0.05 ≦ b ≦ 0.35, The glass component represented by 0.05 ≦ c ≦ 0.15, 0.10 ≦ d ≦ 0.35, 0.10 ≦ e ≦ 0.35, a + b + c + d + e = 1) is 0.5 to 5 And the relationship between b and c of the glass component is 0.9 ≦ b / c, and the relationship between d and e is 0.33 ≦ d / e ≦ 3.00. .

The dielectric porcelain of the present invention includes a glass component having a low softening point composed of SiO ₂ —Li ₂ O—B ₂ O ₃ —CaO—MgO (a sintering aid) as a basic component comprising CaZrO ₃ and CaTiO _3. ) Can significantly increase the Q value during firing in a neutral or reducing atmosphere, reduce the variation in capacitance, and further increase the relative dielectric constant ε _s and temperature characteristics. The TC, the insulation resistance ρ, and the like are also sufficiently satisfied.

Therefore, by applying the non-reducing dielectric ceramic composition of the present invention, temperature compensation which is extremely stable in quality and sufficiently satisfies the capacitance Cap, the temperature characteristic TC, the Q value, the insulation resistance ρ, etc. It is possible to provide a multilayer ceramic capacitor for use.

Which is the main component of the non-reducing dielectric ceramic composition of the present invention _{(CaO) x (Zr 1-} y · Ti y) O 2 ( here, x and y are represented on a molar basis, 0.95 ≦ x ≦ 1.05, 0.01 ≦ y ≦ 0.10) perovskite-type compounds when titanate is the main component when fired in a neutral or reducing atmosphere. By comparison, it is difficult to be reduced, and as a result, since the content of TiO ₂ is very small in the present main component system, stable electric characteristics can be obtained even when firing in the above atmosphere.

理由 The reasons for limiting the composition ratio are as follows.

That is, when the ratio x of Ca as the basic component is less than 0.95, the Q value decreases, and when it exceeds 1.05, the characteristics such as the Q value deteriorate due to insufficient sintering at 1100 to 1300 ° C. . In other words, the ratio of the A site / B site of the perovskite compound is most preferably 1: 1. When the A site / B site ratio deviates from the above range, the problem becomes apparent.

で は If the ratio y of Ti is less than 0.01, the dielectric constant becomes 25 or less, and the target is not satisfied. Further, when y exceeds 0.10, the absolute value of the temperature characteristic of the dielectric constant becomes larger than 30 ppm.

Ｍｎ Further, Mn as an additive has a role of a sintering aid and a role of charge compensation. This is a phenomenon in which a space charge is formed by lattice defects generated by some factor during porcelain generation, and the dielectric constant and tan δ increase at high temperature and low frequency due to space charge polarization generated by this. More specifically, when the addition amount z of Mn is less than 1 part by weight, the dielectric constant / Q value is reduced by insufficient sintering at 1100 to 1300 ° C., and when z exceeds 5 parts by weight, In addition, the insulation resistance value deteriorates.

The composition of the glass component of the present invention is represented by the general formula (1)
_{aSiO 2 -bLi 2 O-cB 2} O 3 -dCaO-eBaO ······· (1)
(Where a + b + c + d + e = 100)
When expressed in terms of mol, 0.25 ≦ a ≦ 0.45, 0.05 ≦ b ≦ 0.35, 0.05 ≦ c ≦ 0.15, 0.10 ≦ d ≦ 0.35, 0. It is composed of a composition in the range of 10 ≦ e ≦ 0.35 and a + b + c + d + e = 1.

This glass component is indispensable for realizing low-temperature sintering in the range of 1100 ° C. to 1300 ° C. with respect to the sintering temperature of the porcelain. Calcium acid can be sintered at a low temperature. However, depending on the composition of the glass, the sintering temperature of the porcelain deviates from the predetermined temperature range.In the case of forming a multilayer ceramic capacitor, the aggregation of glass components particularly occurring near the internal electrode layer occurs. , Q value and the like are caused to deteriorate. In the present invention, the latter problem is particularly focused.

Further, the composition form will be described in detail.

In this glass component, the Si component, that is, SiO ₂ in the glass component has a role of promoting sintering. Therefore, if the ratio a is less than 0.25, sintering is not sufficiently performed. On the other hand, when a exceeds 0.45, a crystal peak is generated in the glass component, and further, aggregation of the glass component of Li ₂ SiO ₃ occurs, so that the Q value decreases.

Further, since Li ₂ O has an essential role in low-temperature sintering, if its ratio b is less than 0.05, it will not be sufficiently sintered. On the other hand, since Li ₂ O is a light element and easily evaporates at the time of firing, when b exceeds 0.35, capacity variation tends to occur depending on the position in the furnace at the time of firing.

_Further, B 2 _{O 3} is Li ₂ O Similarly, to have a role to lower the sintering temperature, when the ratio c becomes less than 0.05, not sufficiently sintered at 1100 to 1300 ° C.. On the other hand, if B ₂ O ₃ is excessively prepared, it is a light element like Li ₂ O, so that it is easy to cause evaporation during firing. That is, if c exceeds 0.15, the inside of the furnace during firing or firing Depending on the position in the use setter, capacity variation is likely to occur.

Further, when the ratio d of CaO or the ratio e of BaO is below a predetermined range, if d is less than 0.10 or e is less than 0.10, sufficient sinterability of the porcelain cannot be obtained. This causes the insulation resistance to deteriorate. Further, when the ratio d of CaO or the ratio e of BaO exceeds a predetermined range, if d exceeds 0.35 in molar ratio, or if e exceeds 0.35, similarly, the sintering temperature is 1300 ° C. or higher. And causes insufficient sintering.

Here, it has been confirmed that a component represented by the composition formula Li ₂ SiO ₃ and a component containing B as a main component are contained in the aggregation of the glass component, and Li ₂ O, SiO ₂ By lowering the B ₂ O ₃ ratio, it is possible to prevent agglomeration of the glass component and further prevent deterioration of the Q value.

Further, by lowering the ratio of SiO ₂ and increasing the ratio of BaO and CaO within a predetermined range, the transition temperature (Tg) of the glass component is lowered, so that sintering can easily proceed and the Q value can be improved. Increase.

The most desirable ranges are 0.98 ≦ x ≦ 1.00, 0.02 ≦ y ≦ 0.03, 2.0 ≦ z ≦ 4.0, 0.30 ≦ a ≦ 0.40, 0.20 ≦ b ≦ 0.30, 0.08 ≦ c ≦ 0.12, 0.10 ≦ d ≦ 0.20, 0.10 ≦ e ≦ 0.20.

Preferably, the glass component is in the range of 0.9 ≦ b / c. That is, when the molar ratio b / c ratio of Li ₂ O and B ₂ O ₃ is smaller than 0.9, the excess of B ₂ O ₃ during the preparation of the raw materials causes aggregation of the glass component, so that the Q value is increased. Decreases.

The glass component is characterized by being in the range of 0.33 ≦ d / e ≦ 3.00. That is, when one of CaO and BaO deviates from the above range, sinterability is reduced, and as a result, a Q value or poor insulation property is caused. Further, it is desirable that the above glass component is in the range of 1 / 1.5 ≦ d / e ≦ 1.5, and it is more desirable that the molar ratio is d / e = 1. For the above reason, it is preferable that the above molar ratio is not the molar ratio of the dielectric ceramic composition after sintering but the molar ratio at the time of mixing the raw materials.

The glass component configured as described above is a basic component of (CaO) _x (Zr _1-y · Ti _y ) O ₂ (where x and y are expressed in terms of mol and 0.95 ≦ x ≦ 1.05, a numerical value in the range of 0.01 ≦ y ≦ 0.10), the desired properties can be obtained only by adding 0.5 to 5% in terms of parts by weight.

Here, the glass component is added at a relatively low temperature of 1100 ° C. to 1300 ° C. to complete the sintering of the main component, and the amount added to the basic component is 0.5% by weight in terms of parts by weight. If the amount of the glass component is less than the above, the sintering of the dielectric porcelain becomes insufficient, and as a result, the insulation resistance value is reduced and the Q value is significantly deteriorated. On the other hand, if the addition exceeds 5% in terms of parts by weight, the glass component excessively present in the grain boundary phase is the cause. Inhibition by excess glass components in the phase leads to a decrease in the dielectric constant. Therefore, the most preferable range of the addition amount is 1.5% to 2% in terms of parts by weight.

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

Calcium carbonate (CaCO ₃ ), titanium dioxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), and manganese carbonate (MnCO ₃ ) were prepared as starting materials and weighed so as to have the ratios shown in Table 1. In this weighing, impurities unavoidably mixed were weighed without being included in the weight. Next, these weighed raw materials were put into a pot mill, and further, alumina balls and 2.5 liters of water were put therein. After wet stirring for 15 hours, the stirred product was put in a stainless steel vat and heated at 150 ° C. with a hot air dryer. Dried for 4 hours. Next, the dried product was coarsely pulverized, and the coarsely pulverized product was fired in a tunnel furnace at 1300 ° C. for 2 hours in the air to obtain a basic component having an average particle size of about 1 μm in the composition formula shown in Table 1. .

On the other hand, in order to obtain a glass component, silicon dioxide (SiO ₂ ), lithium carbonate (Li ₂ CO ₃ ), boron oxide (B ₂ O ₃ ), calcium carbonate (CaCO ₃ ), and barium carbonate (BaCO ₃ ) are appropriately weighed. Then, 300 cc of water was added thereto, and the mixture was stirred for 10 hours using an alumina ball in a polyethylene pot, and then temporarily calcined at 1300 ° C. for 2 hours in the atmosphere. The mixture was pulverized for an hour, and then dried at 150 ° C. for 4 hours to obtain a glass component powder having an average particle size of about 1 μm shown in Table 1.

Next, 1.2 parts by weight of the glass component powder was added to 100 parts by weight of the basic component powder, and an organic binder composed of an aqueous solution of an acrylate polymer, glycerin, and condensed phosphate was used as the basic component. It was added so as to be 15% by weight with respect to the total weight of the additional components, and 50% by weight of water was further added. These were put into a ball mill and ground and mixed for about 20 hours to prepare a slurry of a porcelain raw material.

Next, the slurry is put into a vacuum defoaming machine to remove bubbles. The slurry is put into a reverse roll coater, and a thin film based on the slurry is formed on a polyester film using the slurry. C. and dried to obtain a ceramic green sheet having a thickness of about 25 μm. This sheet was long, and was used by punching it into a 10 cm square.

On the other hand, the conductive paste for the internal electrode layer is prepared by dissolving 10 g of Ni powder having an average particle size of 1.5 μm and 0.9 g of ethyl cellulose dissolved in 9.1 g of butyl carbitol in a stirrer and stirring for 10 hours. It was obtained by doing. This conductive paste was printed on one side of the ceramic green sheet through a screen having 50 patterns having a length of 14 mm and a width of 7 mm, and then dried.

Next, two ceramic green sheets were laminated with the printing surface facing up. At this time, the printing surfaces of the adjacent upper and lower sheets were arranged such that the printing surfaces were shifted by about half in the longitudinal direction of the pattern. Further, four ceramic green sheets each having a thickness of 60 μm were laminated on each of the upper and lower surfaces of the laminate. Next, the laminate was pressed at a temperature of about 50 ° C. by applying a pressure of about 400 kN in the thickness direction. Thereafter, the laminate was cut into a lattice to obtain about 100 laminates.

Next, this laminate was placed in a furnace capable of firing in an atmosphere, heated to 300 ° C. at a rate of 100 ° C./h in an air atmosphere, and held for 2 hours to burn the organic binder. Thereafter, the atmosphere of the furnace was changed from the atmosphere to an atmosphere of ₂ % by volume of H ₂ + 98% by volume of N ₂ . Then, while maintaining the furnace in the reducing atmosphere as described above, the heating temperature of the laminate was increased from 600 ° C. to the sintering temperature at a rate of 100 ° C./h, and 1100 to 1300 ° C. (maximum temperature) × After holding for 3 hours, the temperature was lowered to 600 ° C. at a rate of 100 ° C./h, the atmosphere was changed to an air atmosphere (oxidizing atmosphere), the oxidation treatment was performed by holding at 600 ° C. for 30 minutes, and then cooled to room temperature. Thus, a sintered body was produced.

Next, a conductive paste composed of Cu, glass frit and vehicle is applied to the side surface of the sintered body where the internal electrode layer is exposed and dried, and baked at a temperature of 800 to 900 ° C. for 15 minutes in the air. A Cu base conductor film was formed, Ni was applied thereon by electroless plating, and a Sn solder layer was further provided thereon by electroplating to form a pair of external electrodes.

Thus, a multilayer ceramic capacitor 10 including the dielectric layer 2, the internal electrode layers 3, 4 and the external electrodes 5, 6 shown in FIGS. 1 and 2 was obtained. The size of the multilayer ceramic capacitor 10 is 2.0 mm × 1.25 mm, and the multilayer specification is 15 μm × 40 layers.

Next, the capacitance Cap, the relative dielectric constant ε _s , the temperature coefficient TC, the capacitance variation (CV value), the Q value, and the insulation resistance ρ of the completed multilayer ceramic capacitor were measured.

上 記 The above electrical characteristics were measured as follows.

(1) The relative dielectric constant ε _s is as follows: temperature 25 ° C., frequency 1 MHz, AC voltage [effective value]
The capacitance was measured under the condition of 0 V, and the capacitance was calculated from this measured value, the facing area of the pair of internal electrode layers of 1.5 mm ² and the thickness of the dielectric layer of 0.01 mm. The capacitance Cap was determined in the same manner.

(2) Capacitance variation (CV value) = (standard deviation × 100) / (Cap average value).

(3) calculated in the temperature coefficient _{(TC) = ((C 85} -C 25) × 10 6) / C 25 × (C 85 -C 25). C ₈₅ is the dielectric constant at 85 ° _{C., C 25} is the dielectric constant at 25 ° C..

(4) The resistivity ρ (Ω · cm) was obtained by measuring the resistance value between a pair of external electrodes after applying DC 50 V for 1 minute at a temperature of 20 ° C., and calculating based on the measured value and the dimensions.

(5) The Q value was measured with a Q meter at a temperature of 25 ° C. and an alternating current of 1 MHz and a voltage [effective value] of 0.5 V.

These results are shown in Table 2.

As shown in Table 2, in the samples according to the present invention (sample Nos. 2 to 5, 8 to 11, 14 to 17, 20 to 21, 24, 26 to 30, 34 to 35, 40, 42 to 43), capacitance Cap is 950～1050PF, the dielectric constant epsilon _s is 28 to 33, CV value of 2.0% or less, within the temperature coefficient TC of ± 30 ppm in the dielectric constant, Q value of 1000 or higher, the insulation resistance ρ of 1 × It was 10 ¹¹ Ω · cm or more, and a capacitor for temperature compensation having desired characteristics could be obtained.

On the other hand, when x was 0.90 (sample No. 1), the Q value was reduced to 880. On the other hand, when x was 1.10 (Sample No. 6), the Q value was 940, and the insulation resistance ρ was 4.19 × 10 ⁸ Ω · cm.

Further, y is a case of 0 (Sample No.7), an electrostatic capacitance Cap is 865, the dielectric constant epsilon _s is 22, CV value becomes 2.3%. On the other hand, when y was 0.15 (Sample No. 12), the capacitance Cap was 1315, the absolute value of the temperature characteristic TC of the dielectric constant was 57 ppm, and the CV value was 2.2%.

Further, when z was 0.5 (Sample No. 13), the insulation resistance ρ was reduced to 2.5 × 10 ⁷ Ω · cm, and the Q value was reduced to 890. On the other hand, also in the case of 5.5 parts by weight (Sample No. 18), the insulation resistance ρ decreased to 4.23 × 10 ⁷ Ω · cm, and the Q value decreased to 780.

That is, when the basic component is represented by the general formula (CaO) _x (Zr _1−y · Ti _y ) O ₂ , if x is less than 0.95, the Q value is less than 1000, and x is greater than 1.05. In this case, it can be seen that the Q value is less than 1000 and the insulation resistance ρ is less than 1 × 10 ¹¹ Ω · cm. Further, if y is less than 0.01, the capacitance Cap is less than 950PF, the dielectric constant epsilon _s is less than 25, greater than the CV value of 2.0% if y is larger than 0.10, electrostatic It can be seen that the capacitance Cap is larger than 1050 pF, the temperature coefficient TC of the dielectric constant is larger than -30 ppm, and the CV value is larger than 2.0%.

Furthermore, when the addition amount of MnCO ₃ is z parts by weight, the insulation resistance ρ is less than 1 × 10 ¹¹ Ω · cm when z is less than 1 part by weight or when z is more than 5 parts by weight. .

When a was 0.2 (Sample No. 19), the Q value was 880, and the insulation resistance ρ was 3.65 × 10 ⁷ Ω · cm. On the other hand, when a was 0.5 (Sample No. 22), the Q value decreased to 820, and the insulation resistance ρ decreased to 3.35 × 10 ⁹ Ω · cm.

Furthermore, when b was 0.045 (sample No. 23), the insulation resistance ρ was 1.82 × 10 ⁷ Ω · cm. On the other hand, when b was 0.36 (sample No. 31), the CV value was 2.5%.

When c was 0.045 (Sample No. 38), the insulation resistance ρ was 2.55 × 10 ⁷ Ω · cm. On the other hand, when c was 0.16 (sample No. 39), the CV value was 2.3%.

Here, when b / c was 0.85 (Sample No. 25), the insulation resistance ρ was 2.58 × 10 ¹⁰ Ω · cm, and the Q value was 560.

When d was 0.095 (Sample No. 32), the insulation resistance ρ was 3.2 × 10 ⁷ Ω · cm. On the other hand, in the case of 0.4 (sample No. 33), the insulation resistance ρ was 2.55 × 10 ⁷ Ω · cm.

Furthermore, when e was 0.095 (sample No. 36), the insulation resistance ρ was 2.52 × 10 ⁷ Ω · cm. On the other hand, in the case of 0.4 (sample No. 37), the insulation resistance ρ was 3.2 × 10 ⁷ Ω · cm.

Here, when d / e is 0.286 (Sample No. 41), the insulation resistance ρ is 1.82 × 10 ⁷ Ω · cm, and when d / e is 3.043 (Sample No. 44). Has an insulation resistance ρ of 3.2 × 10 ⁷ Ω · cm.

In other words, when the composition of the glass component is represented by the general formula aSiO ₂ -bLi ₂ O-cB ₂ O ₃ -dCaO-eBaO, if the ratio a of SiO ₂ is less than 0.25, the composition is not sufficiently sintered. When the Q value is less than 1000 and the insulation resistance ρ is less than 1 × 10 ¹¹ Ω · cm, and when a is greater than 0.45, the glass component is aggregated, so that the Q value is less than 1000 and the insulation resistance ρ is 1 × 10 11 It turns out that it becomes less than ¹¹ ohm * cm.

When the ratio b of Li ₂ O is less than 0.05, the sintering is not sufficiently performed, so that the insulation resistance ρ is less than 1 × 10 ¹¹ Ω · cm. It can be seen that the capacity variation tends to occur depending on the position inside, so that the CV value becomes larger than 2.0%.

Further, when the ratio c of B ₂ O ₃ is less than 0.05, the sintering is not sufficiently performed, so that the insulation resistance ρ is less than 1 × 10 ¹¹ Ω · cm. It can be seen that the capacity variation tends to occur depending on the position in the furnace, so that the CV value is larger than 2.0%.

Here, if the molar ratio b / c ratio of the raw material mixture of Li ₂ O and B ₂ O ₃ is less than 0.9, the glass component is agglomerated, so that the Q value is less than 1000 and the insulation resistance ρ is It turns out that it becomes less than 1 × 10 ¹¹ Ω · cm.

Also, when the CaO ratio d is less than 0.10 or greater than 0.35, the insulation resistance ρ is less than 1 × 10 ¹¹ Ω · cm because the sintering is not sufficiently performed at 1100 to 1300 ° C. I understand.

Furthermore, when the BaO ratio e is less than 0.10 or greater than 0.35, the insulation resistance ρ is less than 1 × 10 ¹¹ Ω · cm because the material is not sufficiently sintered at 1100 to 1300 ° C. I understand.

Here, when the molar ratio d / e ratio at the time of mixing the raw materials of CaO and BaO is larger than 3.00 or smaller than 0.33, it is not sufficiently sintered at 1100 to 1300 ° C. It can be seen that the insulation resistance ρ is less than 1 × 10 ¹¹ Ω · cm.

Further, when the aggregation in the cross section of the sintered body was examined by EPMA, the dielectric ceramic composition of the present invention (Sample No. 10) did not show aggregation of the glass component, but the comparative example (Sample No. 22). In the dielectric ceramic composition of ( ₂ ), aggregation of the glass component represented by the composition formula Li ₂ SiO ₃ was observed. In the dielectric ceramic composition of the comparative example (sample No. 25), aggregation of a glass component containing B as a main component was observed.

Further, when the transition temperature (Tg) of the glass component was examined, the Tg of the glass component of the present invention (Sample No. 10) was 483 ° C., but the Tg of the glass component of Comparative Example (Sample No. 22) was 534. ° C, it was confirmed that the transition temperature (Tg) of the glass component was lowered by lowering the ratio of SiO ₂ and raising the ratio of BaO and CaO.

The glass component is added in an amount of 0.5 to 5% in terms of parts by weight based on the main component. This glass component is added at a relatively low temperature of 1100 ° C. to 1300 ° C. to complete the sintering of the main component system. If the amount added is less than 0.5% in terms of parts by weight, the glass component is added. Irrespective of the composition, the sintering of the dielectric porcelain becomes insufficient, and as a result, the insulation resistance value is lowered, and the Q value is remarkably deteriorated. On the other hand, if it is added in excess of 5% in terms of parts by weight, regardless of the value of b / c and d / e of the glass component, the glass component excessively present in the grain boundary phase is the cause. The dielectric properties of a certain calcium zirconate are hindered by the excess glass component present in the grain boundary phase, resulting in a decrease in the dielectric constant, and sample numbers 7, 39 which do not reach the practical revel level (the present invention). (Out of range). The most desirable range of the glass component is 1.5% to 2% in terms of parts by weight.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments, and for example, the following modifications are possible.

(1) A trace amount (preferably 0.05 to 0.1% by weight) of a mineralizer may be added to the basic components within a range that does not impair the purpose of the present invention to improve sinterability.

(2) The starting material for obtaining the basic component may be, for example, an oxide or hydroxide such as CaO or another compound other than those shown in the examples. The starting material of the additional component may be another compound such as an oxide or a hydroxide.

(3) The oxidation temperature may be lower than the sintering temperature other than 600 ° C (preferably in the range of 500 ° C to 1000 ° C). That is, various changes can be made in consideration of the electrode of Ni or the like and the oxidation of the porcelain.

(4) The firing temperature in the non-oxidizing atmosphere can be variously changed in consideration of the electrode material. When Ni is used as the internal electrode layer, almost no melt aggregation occurs in the range of 1050 ° C to 1200 ° C.

(5) Sintering may be performed in a neutral atmosphere.

(6) The present invention is applicable to general ceramic capacitors other than the multilayer ceramic capacitor.

(7) It is applicable to other glass components having a low melting point.

1 is an external perspective view of a general multilayer ceramic capacitor. It is sectional drawing of the laminated ceramic capacitor of FIG. It is a figure which shows the problem of the conventional dielectric ceramic composition.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 10 Laminated ceramic capacitor 1 Laminated body 2 Dielectric layer 3, 4 Internal electrode layer 5, 6 External electrode 5a, 6a Base conductive film 5b, 6b Plating layer 20 Aggregation part of glass component

Claims (1)

General formula (CaO) _x (Zr _1-y · Ti _y ) O ₂ (where x and y are expressed in terms of mole, and 0.95 ≦ x ≦ 1.05, 0.01 ≦ y ≦ 0.10) With respect to 100 parts by weight of the basic component represented by
1 to 5 parts by weight of MnCO ₃ ,
It is represented by the general formula aSiO ₂ -bLi ₂ O-cB ₂ O ₃ -dCaO-eBaO (where a to e are in terms of moles), and the values of a to e are 0.25 ≦ a ≦ 0.45 and 0. 05 ≦ b ≦ 0.35, 0.05 ≦ c ≦ 0.15, 0.10 ≦ d ≦ 0.35, 0.10 ≦ e ≦ 0.35, and the relationship between b and c is 0. 0.9 ≦ b / c, and 0.5 to 5 parts by weight of a glass component in which the relationship between d and e is 0.33 ≦ d / e ≦ 3.00 (a + b + c + d + e = 1). Dielectric porcelain composition.

Images