JP5035278B2 - Dielectric porcelain composition and electronic component - Google Patents

Description

  The present invention relates to a dielectric ceramic composition. More specifically, the present invention shows a relatively high relative dielectric constant (for example, 600 or more), a small dielectric loss (for example, 0.3% or less at 100 KHz), and a capacitance-temperature characteristic. The present invention relates to an excellent dielectric ceramic composition (for example, satisfying JIS standard SL characteristics). The present invention also relates to an electronic component, particularly a ceramic capacitor, using the dielectric ceramic composition.

  In recent years, along with rapid progress in performance of electrical equipment, miniaturization and complexity of electrical circuits are also progressing rapidly. For this reason, electronic components are required to be further reduced in size and performance. That is, there is a demand for a dielectric ceramic composition and an electronic component having a high dielectric constant in order to maintain capacitance even in downsizing while maintaining good temperature characteristics.

High dielectric constant systems such as barium titanate (BaTiO ₃ ) are known as dielectric ceramic compositions used for ceramic capacitors and the like. In this type of composition, the relative dielectric constant εr can be increased, but the capacitance temperature change rate is large.

The dielectric ceramic composition includes calcium zirconate (CaZrO ₃ ), strontium zirconate (SrZrO ₃ ), calcium titanate (CaTiO ₃ ), strontium titanate (SrTiO ₃ ), and strontium calcium zirconate (CaSrZrO ₃ ). It is also known for temperature compensation. This main composition has a very small capacity-temperature change rate, and can be used for a coupling circuit, an acoustic circuit, an image processing circuit, or the like. However, since it is a paraelectric material, the relative dielectric constant εr is as low as 30 to 200, and it is difficult to obtain a high-capacity capacitor.

For example, Patent Document 1 discloses a temperature compensating porcelain composition comprising (SrCa) (TiZr) O ₃ having a specific composition, Li ₂ SiO ₃ and an alkaline earth fluoride.

JP-A-5-17222

  However, the dielectric ceramic composition described in Patent Document 1 has a relative dielectric constant εr of about 310 at the maximum, which is still insufficient for downsizing.

  The present invention has been made in view of the prior art as described above, and exhibits a relatively high relative dielectric constant (for example, 600 or more) and a small dielectric loss (for example, 0.3% or less at 100 KHz). An object of the present invention is to provide a dielectric ceramic composition having excellent capacity-temperature characteristics (for example, satisfying JIS standard SL characteristics).

The present invention for solving the above-mentioned problems includes the following matters as a gist.
(1) SrTiO ₃ : 50.47 to 55.48% by weight,
CaTiO ₃ : 14.30 to 21.36% by weight,
Bi ₂ O ₃ : 16.70 to 19.40% by weight,
TiO ₂ : 8.29 to 10.01% by weight,
CeO ₂ : 0.24 to 0.50% by weight,
CuO: 0.027 to 0.347% by weight, and a dielectric ceramic composition containing a Mn compound at a ratio of 0.16 to 0.46% by weight in terms of MnO.

(2) The dielectric ceramic composition according to (1), further containing Nb ₂ O ₅ at a ratio of 0.750% by weight or less.

(3) An electronic component using the dielectric ceramic composition as described in (1) or (2) above.

(4) A leaded capacitor using the dielectric ceramic composition as described in (1) or (2) above.

  According to the present invention, the dielectric constant is relatively high (for example, 600 or more), the dielectric loss is small (for example, 0.3% or less at 100 KHz), and the capacitance-temperature characteristics are excellent (for example, JIS standard SL) Satisfying properties) A dielectric porcelain composition is provided.

FIG. 1A is a front view of a ceramic capacitor according to an embodiment of the present invention, and FIG. 1B is a side sectional view of the ceramic capacitor according to an embodiment of the present invention.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1A is a front view of a ceramic capacitor according to an embodiment of the present invention, and FIG. 1B is a side sectional view of the ceramic capacitor according to an embodiment of the present invention.

Ceramic capacitor 2
As shown in FIGS. 1A and 1B, a ceramic capacitor 2 according to this embodiment includes a dielectric layer 10, a pair of terminal electrodes 12 and 14 formed on the opposing surface thereof, and the terminals. The lead terminals 6 and 8 are respectively connected to the electrodes 12 and 14, and these are covered with the protective resin 4. The shape of the ceramic capacitor 2 may be appropriately determined according to the purpose and application, but is preferably a disk-type capacitor in which the dielectric layer 10 has a disk shape. The size may be appropriately determined according to the purpose and application, but the diameter is usually about 5 to 20 mm, preferably about 5 to 15 mm.

Dielectric layer 10
The dielectric layer 10 contains the dielectric ceramic composition of the present invention. The dielectric ceramic composition of the present invention contains a main component containing Sr, Ca, Ti and Bi and a subcomponent containing Ce, Cu and Mn, and the subcomponent may contain Nb. .

The compounding amount of each element constituting the main component is shown by the following oxide or composite oxide equivalent amount. That is, in the dielectric ceramic composition of the present invention, SrTiO ₃ is contained at 50.47 to 55.48% by weight, preferably 51.44 to 55.01% by weight,
CaTiO ₃ is contained at 14.30 to 21.36 wt%, preferably 14.39 to 21.22 wt%,
Bi ₂ O ₃ is contained in an amount of 16.70 to 19.40% by weight, preferably 16.78 to 19.36% by weight,
TiO ₂ is contained in an amount of 8.29 to 10.01% by weight, preferably 8.30 to 10.00% by weight.

The compounding quantity of each element which comprises a subcomponent is shown by the following oxide conversion amount. That is, CeO ₂ is contained at 0.24 to 0.50% by weight,
CuO is contained at 0.027 to 0.347% by weight,
Further, the Mn compound is contained at 0.16 to 0.46% by weight in terms of MnO.

  A dielectric ceramic composition containing the main component and the subcomponent in the above composition exhibits a relatively high relative dielectric constant (for example, 600 or more) and a small dielectric loss (for example, 0.3% or less at 100 KHz). ) Excellent in capacity-temperature characteristics (for example, satisfying JIS standard SL characteristics).

Moreover, the dielectric ceramic composition of the present invention may contain Nb ₂ O ₅ at a ratio of 0.750% by weight or less as necessary. By blending Nb ₂ O ₅ , the dielectric loss can be further reduced even when the main component and the subcomponent having substantially the same composition are contained.

  The thickness of the dielectric layer 10 is not particularly limited, and may be appropriately determined according to the use or the like, but is preferably 0.3 to 2 mm. By setting the thickness of the dielectric layer 10 in such a range, it can be suitably used for medium to high pressure applications. In addition, according to the dielectric ceramic composition of the present invention, since the dielectric constant is high, the device can be miniaturized.

Terminal electrodes 12, 14
The terminal electrodes 12 and 14 are made of a conductive material. Examples of the conductive material used for the terminal electrodes 12 and 14 include Cu, Cu alloy, Ag, Ag alloy, and In—Ga alloy.

Next, a method for manufacturing a ceramic capacitor according to this embodiment will be described.
First, a dielectric ceramic composition powder that will form the dielectric layer 10 shown in FIG. 1 after firing is manufactured.

First, a predetermined amount of raw materials for the main component and raw materials for each subcomponent are prepared. The main component materials are SrTiO ₃ , CaTiO ₃ , Bi ₂ O ₃ and TiO ₂ , and the subcomponent materials are CeO ₂ , CuO and Mn compounds. The Mn compound is preferably MnO, but may be other oxides, hydroxides, carbonates or the like. It may also be added Nb ₂ O ₅ as an auxiliary component.

  The main component raw material may be manufactured by a solid phase method or a liquid phase method such as a hydrothermal synthesis method or an oxalate method. It is preferable to manufacture.

  Next, the raw materials of the main component and the subcomponent are blended so as to have the above-described predetermined composition, and wet-mixed using a ball mill or the like at a concentration of about 75% by weight using water as a dispersion medium.

  Next, a binder resin is added, further wet-mixed, granulated by a general-purpose method such as spray drying, and the resulting granulated product is formed into a disk shape having a predetermined size, thereby forming a green A molded body. The obtained green molded body is fired to obtain a sintered body of the dielectric ceramic composition. In addition, although it does not specifically limit as conditions for baking, Preferably holding temperature is 1160-1220 degreeC and it is preferable to make a baking atmosphere into the air.

  And terminal electrodes 12 and 14 are formed by printing a terminal electrode on the main surface of the sintered body of the obtained dielectric ceramic composition, and baking it as necessary. Thereafter, the lead terminals 6 and 8 are joined to the terminal electrodes 12 and 14 by soldering or the like, and finally, the element main body is covered with the protective resin 4 so as to be shown in FIGS. 1 (A) and 1 (B). Such a single plate type ceramic capacitor is obtained.

  The ceramic capacitor of the present invention thus manufactured is mounted on a printed circuit board or the like via lead terminals 6 and 8, and is used for various electronic devices.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, Of course, it can implement in a various aspect within the range which does not deviate from the summary of this invention. .

  For example, in the embodiment described above, a single plate type ceramic capacitor having a single dielectric layer is exemplified as the electronic component according to the present invention. However, the electronic component according to the present invention is limited to the single plate type ceramic capacitor. Alternatively, it may be a multilayer ceramic capacitor produced by a normal printing method or sheet method using a dielectric paste and an electrode paste containing the above dielectric ceramic composition.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

Examples First, SrTiO ₃ , CaTiO ₃ , Bi ₂ O ₃ and TiO ₂ were prepared as main component materials, and CeO ₂ , CuO, MnO and Nb ₂ O ₅ were prepared as subcomponent materials. The prepared raw materials were each weighed so as to have the weight composition shown in Table 1, and wet-mixed by a ball mill at a concentration of 75 wt% solid content using water as a dispersion medium.

Next, an aqueous polyvinyl alcohol solution as a binder is added and mixed so that the solid content concentration becomes 1.93 wt%, granulated by spray drying, passed through a mesh pass, and the obtained granulated powder is 3 t. By molding at a pressure of / cm ² , a disk-shaped green molded body having a diameter of 12 mm and a thickness of about 1.2 mm was obtained.

  Next, the obtained green molded body was fired in air at 1160 to 1220 ° C. for 2 hours to obtain a disk-shaped sintered body. And the Ag electrode was apply | coated to the main surface of the obtained sintered compact, and also the sample of the disk-shaped ceramic capacitor as shown in FIG. 1 was obtained by performing the baking process in air at 650 degreeC for 20 minutes. . The thickness of the dielectric layer 10 of the obtained capacitor sample was about 1 mm. Each of the obtained capacitor samples was evaluated for dielectric constant, dielectric loss, and capacitance-temperature characteristics by the following methods. The evaluation results are shown in Table 1.

Dielectric constant ε and dielectric loss (tan δ)
The disc-shaped sample was measured for its capacitance and dielectric loss (tan δ) under the conditions of 1 kHz and 1 Vrms at 25 ° C. with an LCR meter. The relative dielectric constant (εr) was calculated from the obtained capacitance, electrode dimensions, and sample thickness.

Capacitance-temperature characteristics Use a LCR meter to measure the capacitance at a voltage of 1 V, and measure the JIS standard SL characteristics (capacity change rate at 85 ° C when the reference temperature is 20 ° C). did.

From the above results, the dielectric ceramic composition containing the main component and the subcomponent in the composition defined in the present invention exhibits a relatively high relative dielectric constant (for example, 600 or more) and a small dielectric loss (for example, 100 KHz). 0.3% or less) and excellent capacity-temperature characteristics (for example, satisfying SL characteristics of JIS standard). On the other hand, it can be seen that the composition outside the range defined by the present invention impairs the relative permittivity, dielectric loss, or capacitance-temperature characteristics. In addition, by blending Nb ₂ O ₅ , even when the main component and subcomponent of substantially the same composition are contained, the dielectric loss can be further reduced, but if the blending amount is excessive, the capacity It can be seen that the temperature characteristics are impaired.

2 ... Ceramic capacitor 4 ... Protective resin 6, 8 ... Lead terminal 10 ... Dielectric layer 12, 14 ... Terminal electrode

Claims (3)

SrTiO ₃ : 50.47 to 55.48% by weight,
CaTiO ₃ : 14.30 to 21.36% by weight,
Bi ₂ O ₃ : 16.70 to 19.40% by weight,
TiO ₂ : 8.29 to 10.01% by weight,
CeO ₂ : 0.24 to 0.50% by weight,
CuO: 0.027 to 0.347% by weight,
0.16 to 0.46% by weight of Mn compound in terms of MnO, and
A dielectric ceramic composition containing Nb ₂ O ₅ in a proportion of 0.750% by weight or less .   An electronic component using the dielectric ceramic composition according to claim 1.   A leaded capacitor using the dielectric ceramic composition according to claim 1.

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