JP5012932B2 - Dielectric porcelain composition and electronic component - Google Patents

Description

  The present invention relates to a dielectric ceramic composition used for a dielectric layer of an electronic component. More specifically, the dielectric loss can be reduced in a high frequency region, and the temperature characteristic is exhibited while exhibiting a higher relative dielectric constant. The present invention relates to an excellent dielectric ceramic composition and an electronic component using the same.

  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. For example, a dielectric ceramic composition having a good temperature characteristic of dielectric constant (capacitance) in a predetermined temperature range is required.

There are various standards for the dielectric temperature characteristics depending on the required characteristics. For example, there are SL characteristics of JIS standards. Examples of the dielectric ceramic composition satisfying this SL characteristic include SrTiO ₃ —CaTiO ₃ —Bi ₂ O ₃ —TiO ₂ based dielectric ceramic compositions, etc., but the relative dielectric constant is as low as about 200 to 300. However, there is a problem that it cannot cope with downsizing and high performance.

On the other hand, Patent Document 1 describes a dielectric ceramic composition based on SrTiO ₃ —Bi ₂ O ₃ —TiO ₂ —MgO. This dielectric ceramic composition has a relatively high dielectric constant, but tends to have a poor dielectric constant temperature characteristic.

Japanese Patent Laid-Open No. 50-68000

  The present invention has been made in view of such a situation, and its object is to be used for a dielectric layer of an electronic component such as a ceramic capacitor, which can reduce dielectric loss in a high frequency region, and has a dielectric constant temperature characteristic. An object of the present invention is to provide an excellent dielectric ceramic composition having a high relative dielectric constant. Another object of the present invention is to provide an electronic component obtained using such a dielectric ceramic composition.

In order to achieve the above object, the dielectric ceramic composition according to the present invention comprises:
Strontium oxide is 29.34 to 44.70% by weight in terms of SrTiO ₃ ,
Bismuth oxide, 22.56 to 28.48% by weight in terms of Bi ₂ O ₃ ,
Titanium oxide, in terms of TiO ₂ , 26.36-30.27% by weight,
Magnesium oxide in terms of MgO, 3.61 to 5.56% by weight,
1.86 to 3.42% by weight of neodymium oxide in terms of Nd ₂ O ₃ ,
Manganese oxide is 0.21 to 0.99% by weight in terms of MnO,
Silicon oxide, in terms of SiO _2, characterized in that it contains 0.06 to 0.50 wt%.

  The dielectric ceramic composition according to the present invention has a high dielectric constant and good temperature characteristics while reducing dielectric loss in a high frequency region by setting each component to the above composition and content. A composition can be obtained.

  According to the present invention, there is provided an electronic component having a dielectric layer made of the above dielectric ceramic composition. Although it does not specifically limit as an electronic component which concerns on this invention, For example, the components for backlight of a liquid crystal panel, the surface mounting components resin-molded, etc. are illustrated.

  In the dielectric ceramic composition of the present invention, the ratio of each component is in the predetermined range. As a result, it is possible to obtain a dielectric ceramic composition having a low dielectric loss in a high frequency region and having excellent dielectric constant temperature characteristics and a high relative dielectric constant.

  By using such a dielectric ceramic composition of the present invention in a dielectric layer of an electronic component such as a ceramic capacitor, an electronic component that achieves miniaturization (low profile) while achieving high performance is provided. Can do.

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.

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. In the present embodiment, the ceramic capacitor 2 is a disk-type capacitor in which the dielectric layer 10 has a disk shape. Further, the size may be appropriately determined depending on the purpose and application, but the diameter is usually about 2.5 to 14.5 mm, preferably about 3.0 to 4.0 mm.

Dielectric layer 10
The dielectric layer 10 is composed of a dielectric ceramic composition according to the present embodiment, and the dielectric ceramic composition according to the present embodiment includes strontium oxide, bismuth oxide, titanium oxide, magnesium oxide, Contains neodymium oxide, manganese oxide, and silicon oxide. The content of each component is as follows.

Strontium oxide is contained in an amount of 29.34 to 44.70% by weight, preferably 33.12 to 41.62% by weight, more preferably 37.83 to 39.99% by weight in terms of SrTiO ₃ .

Bismuth oxide is contained in an amount of 22.56 to 28.48% by weight, preferably 23.66 to 27.30% by weight, more preferably 26.06 to 26.15% by weight in terms of Bi ₂ O ₃ .

Titanium oxide is contained in an amount of 26.36 to 30.27% by weight, preferably 27.18 to 29.52% by weight, more preferably 27.86 to 27.99% by weight in terms of TiO ₂ .

  Magnesium oxide is contained in an amount of 3.61 to 5.56% by weight, preferably 4.19 to 5.14% by weight, more preferably 4.71 to 4.75% by weight in terms of MgO.

Neodymium oxide is contained in an amount of 1.86 to 3.42% by weight, preferably 2.13 to 3.02% by weight, more preferably 2.62 to 2.64% by weight in terms of Nd ₂ O ₃ .

  Manganese oxide is contained in an amount of 0.21 to 0.99% by weight, preferably 0.29 to 0.99% by weight, more preferably 0.38 to 0.39% by weight in terms of MnO.

Silicon oxide in terms of SiO _2, 0.06 to 0.50 wt%, preferably from 0.10 to 0.49 wt%, more preferably containing 0.19 to 0.21 wt%.

  The dielectric ceramic composition containing each component with the above composition exhibits a relatively high relative dielectric constant (for example, 650 or more) and has a small dielectric loss in a high frequency region (for example, 0.30% or less at 100 KHz). ) Excellent dielectric constant temperature characteristics (for example, satisfying JIS standard SL characteristics).

  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.

Terminal electrodes 12, 14
The terminal electrodes 12 and 14 are made of a conductive material. The conductive material used for the terminal electrodes 12 and 14 includes, for example, Cu, Cu alloy, Ag, Ag alloy, In—Ga alloy or the like as a main component. In these, Cu and Cu alloy are preferable. The terminal electrodes 12 and 14 may have a single layer structure of these metals or alloys, or may have a multilayer structure.

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, raw materials for each component constituting the dielectric ceramic composition are prepared. The raw material of each component is not particularly limited, and the above-described oxides and complex oxides of each component, or various compounds that become these oxides and complex oxides upon firing, such as carbonates, nitrates, hydroxides, organics It can be appropriately selected from metal compounds and the like. For example, a carbonate such as MnCO ₃ or MgCO ₃ or an oxide such as TiO ₂ can be used. In addition, the raw material of strontium titanate 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 by.

  Next, the raw materials of each component are blended so as to have the above-described predetermined composition, and wet-mixed using water as a dispersion medium at a concentration of about 75% by weight using a ball mill or the like. The slurry after wet mixing is dried to obtain a dielectric ceramic composition powder.

  Subsequently, a binder or the like is added to the obtained dielectric ceramic composition powder and granulated, and the obtained granulated product is formed into a disk shape having a predetermined size to obtain a green molded body. . And the dielectric ceramic composition as a sintered compact is obtained by baking the obtained green molded object. The firing conditions are not particularly limited, but the holding temperature is preferably 1200 to 1340 ° C., and the firing atmosphere is preferably in 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 above-described embodiment, the single plate type ceramic capacitor is exemplified as the electronic component according to the present invention. However, the electronic component according to the present invention is not limited to the single plate type ceramic capacitor, and the dielectric ceramic composition described above. A multilayer ceramic capacitor manufactured by a normal printing method or a sheet method using a dielectric paste containing an object powder and an electrode paste may be used.

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

Example 1
First, SrTiO ₃ , Bi ₂ O ₃ , TiO ₂ , MgCO ₃ , Nd (OH) ₃ , MnCO ₃ and SiO ₂ were prepared as raw materials. The prepared raw materials were each weighed so as to have the weight composition shown in Table 1, and wet-mixed with a ball mill using water as a dispersion medium to prepare a slurry. The solid content concentration of the slurry was 75% by weight. This slurry was dried to obtain a dielectric ceramic composition powder.

In addition, MgCO ₃ , Nd (OH) ₃ and MnCO ₃ will be contained as oxides after firing.

Next, an aqueous polyvinyl alcohol solution as a binder is added and mixed to the obtained dielectric ceramic composition powder so as to have a solid content concentration of 1.93% by weight, granulated by a spray dryer, and passed through a mesh pass. Granulated powder was obtained. Thereafter, the obtained granulated powder was molded at a pressure of 3 t / cm ² to obtain a disk-shaped green molded body having a diameter of 12 mm and a thickness of about 1.2 mm.

  Next, the obtained green molded body was fired in air at 1200 to 1340 ° 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 dielectric constant temperature characteristics by the following methods. The evaluation results are shown in Table 1.

Dielectric constant ε
The relative dielectric constant ε was measured on a capacitor sample at a reference temperature of 25 ° C. using a digital LCR meter (4274A manufactured by YHP) under the conditions of a frequency of 1 kHz and an input signal level (measurement voltage) of 1.0 Vrms. Calculated from the electric capacity (no unit). It is preferable that the relative dielectric constant is high. In this example, 650 or more was considered good. The results are shown in Table 1.

Dielectric loss (tan δ)
Dielectric loss (tan δ) is measured with a digital LCR meter (YHP 4274A) at a reference temperature of 25 ° C. and at a frequency of 1 kHz and 100 kHz and an input signal level (measurement voltage) of 1.0 Vrms with respect to a capacitor sample. did. The dielectric loss is preferably as low as possible. In this example, 0.30% or less was considered good at a frequency of 100 kHz. The results are shown in Table 1.

Dielectric constant temperature characteristics Capacitor samples were measured for capacitance at a voltage of 1 V in the temperature range of −25 to 85 ° C., and the change rate of dielectric constant with respect to the capacitance at + 20 ° C. (unit: ppm / ° C.) Was calculated. In this example, a sample having a change rate in the range of +350 to −1000 ppm / ° C. was regarded as good (SL characteristic of JIS standard). The results are shown in Table 1. Table 1 shows the change rate at 85 ° C., and all the samples having this change rate in the above range satisfied the SL characteristics.

  From Table 1, when the composition of the dielectric ceramic composition is within the scope of the present invention (sample numbers 2 to 4, 7 to 10, 13 to 16, 19 to 21, 24 to 26, 29 to 32, 36 to 40) includes a relative dielectric constant of 650 or more, a dielectric loss (100 kHz) of 0.30% or less, and a change rate of dielectric constant with respect to 20 ° C. in the entire range of −25 ° C. to 85 ° C. + 350 to −1000 ppm / ° C. (SL of JIS standard) It was confirmed that the characteristics were satisfied.

  On the other hand, when the composition of the dielectric ceramic composition is out of the scope of the present invention (sample numbers 1, 5, 6, 11, 12, 17, 18, 22, 23, 27, 28, 33-35 and 41), it was confirmed that at least one of the dielectric constant, dielectric loss (100 kHz), and dielectric constant temperature characteristic was deteriorated.

Example 2
A capacitor sample was prepared in the same manner as in Example 1 except that the oxide shown in Table 2 was contained in the amount shown in Table 2 instead of Nd ₂ O ₃ , and the same characteristic evaluation as in Example 1 was performed. Went. The results are shown in Table 2.

From Table 2, when using the oxide shown in Table 2 instead of Nd ₂ O ₃ (Sample Nos. 51 to 66), at least one of relative dielectric constant, dielectric loss (100 kHz), and dielectric constant temperature characteristics is significantly It was confirmed that it was getting worse. This tendency was the same even when the oxide content was changed.

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

Claims (2)

Strontium oxide is 29.34 to 44.70% by weight in terms of SrTiO ₃ ,
Bismuth oxide, 22.56 to 28.48% by weight in terms of Bi ₂ O ₃ ,
Titanium oxide, in terms of TiO ₂ , 26.36-30.27% by weight,
Magnesium oxide in terms of MgO, 3.61 to 5.56% by weight,
1.86 to 3.42% by weight of neodymium oxide in terms of Nd ₂ O ₃ ,
Manganese oxide is 0.21 to 0.99% by weight in terms of MnO,
A dielectric ceramic composition comprising 0.06 to 0.50% by weight of silicon oxide in terms of SiO ₂ .   The electronic component which has a dielectric material layer comprised with the dielectric material ceramic composition of Claim 1.

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