JP3179119B2 - Dielectric porcelain composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric porcelain composition, and more particularly, to a small change rate of capacitance with respect to temperature, a high non-dielectric constant, and a low dielectric loss. The present invention relates to a dielectric ceramic composition having a small life property . 2. Description of the Related Art A method for manufacturing a laminated ceramic capacitor widely used for an IC circuit element or the like used for a communication device, an electronic computer, a television receiver or the like is roughly classified into a printing method and a sheet method.
There are seeds. In the printing method, a dielectric slurry is printed in a predetermined shape, and after drying, an electrode paste is printed thereon and dried.
On this, a method of printing a dielectric slurry again is repeated to laminate. [0004] In the sheet method, a dielectric sheet is prepared, an electrode paste is printed thereon, a plurality of these layers are stacked, thermally pressed and laminated, and the laminated body is fired in a natural atmosphere to form a sintered body. An external lead-out electrode which is electrically connected to the internal electrode is burned on this. In this case, since the electrode paste and the dielectric which are to be the internal electrodes of the capacitor are fired simultaneously, the material of the internal electrodes is that the electrodes can be formed within the temperature at which the dielectric sinters. Must not oxidize or react with the dielectric. Conventionally, noble metals such as platinum and palladium have been mainly used to satisfy these conditions. However, these precious metals are very stable, but expensive, and have been the biggest cause of the increase in the cost of the laminated ceramic capacitor. For this reason, attempts have been made to use inexpensive base metals such as nickel as internal electrodes. However, nickel is oxidized when heated in an oxidizing atmosphere and reacts with a dielectric to make electrode formation impossible. Therefore, when firing in a neutral or reducing atmosphere, the dielectric material is reduced this time, resulting in a very low specific resistance, and cannot be used as a dielectric material for capacitors. In order to improve such disadvantages, BaTiO ₃ , CaTiO ₃ , and the like have conventionally been used as dielectric ceramic compositions.
Various dielectric porcelain compositions containing CaZrO ₃ , MnO, SiO _{2 and the} like have been proposed (for example, Japanese Patent Application Laid-Open No. SHO 61-61).
155255, JP-A-62-2408). However, these dielectric ceramic compositions are not always satisfactory because of their large temperature characteristics. Accordingly, an object of the present invention is to provide a laminated ceramic capacitor using a base metal such as nickel as an internal electrode, so that it has good temperature characteristics and good relative dielectric constant even when fired in a neutral or reducing atmosphere. An object of the present invention is to provide a dielectric porcelain composition having a high dielectric loss, a high dielectric loss, and a good life characteristic . [0011] SUMMARY OF] To achieve the above object, the present invention BaTiO ₃ 94.65 mol% to 98.50 mol% CaZrO ₃ 0.50 mole% ～2.32 mol% CaTiO ₃ 0.50 mole% ～3.03 mol% MnO 0.50 mol% to 2.00 mol% Y ₂ O ₃ 0.05 mol% to 0.25 mol% (Baα, Ca (1-α)) SiO ₃ (where 0.43 ≦ α
≦ 0.62) The present invention provides a dielectric ceramic composition having a composition in the range of 1 to 10.00 mol%. The dielectric porcelain composition of the present invention has a sufficiently high specific resistance even when fired in a reducing atmosphere, has a small rate of change in capacitance with respect to temperature, and has a low relative dielectric constant. A material having high dielectric loss and good life characteristics can be obtained. Thus, a dielectric ceramic composition particularly useful for forming a laminated ceramic capacitor having nickel as an internal electrode can be obtained. An embodiment of the present invention will be described with reference to FIG. FIG. 1 is an explanatory view of a manufacturing process of the present invention. FIG. 1 (a) is an explanatory view of a material manufacturing process of a dielectric porcelain composition, and FIG. FIG. 4 is an explanatory view of a forming process of a laminated ceramic capacitor which has been used. As starting materials, commercially available BaCO ₃ and TiO 2 are used.
₂ and calcined to synthesize BaTiO ₃ , CaC
O _3, the CaZrO ₃ with ZrO _2, CaCO _3,
Using TiO ₂ , CaTiO ₃ , CaCO ₃ , BaCO 3
_3. (Baα, Ca1-α) SiO ₃ using SiO ₂
Are respectively synthesized and pulverized. BaTiO ₃ , CaZ
rO ₃ , CaTiO ₂ , (BaαCa1-α) SiO ₃
Synthesis composition of fine powder and MnCO _3, Y ₂ O _3, respectively after final firing is formulated were weighed so as to as shown in Table 1 to Table 3 (see 1 in Figure 1 (a)). The above BaTi
There is no problem even if O ₃ , CaTiO ₃ , and CaZrO ₃ are synthesized by a liquid phase method. Next, these fine powders are wet-mixed and pulverized together with a dispersant, and dehydrated and dried (see 2, 3 in FIG. 1A). The dehydrated and dried composition is crushed into powder (see 4 in FIG. 1 (a)). The thus obtained fine powder is mixed with a dispersant or the like to prepare a raw material slurry. Next, an organic binder is added to this raw material slurry together with a plasticizer,
Mix well and enamel (see 1 in FIG. 1 (b)). The enameled raw material is formed into a sheet by a doctor blade method to obtain a dielectric sheet (see 2 in FIG. 1 (b)). A nickel paste as an internal electrode material is printed on the obtained dielectric sheet (see 3 in FIG. 1B), and a plurality of these are stacked and thermocompressed to form a laminate (FIG. 1). (See 4 of (b)). The formed laminate is cut with a cutter to a size of, for example, 4 × 2 millimeters (5 in FIG. 1B).
reference). Next, this sample was heated at 250 ° C. to 400 ° C. for 15 minutes.
After destabilizing for a time, the binder is removed (see 6 in FIG. 1B). Thereafter, the oxygen partial pressure is from 7 × 10 ^{-9 to} 9 × 10
^-13 atm. And the firing temperature is 1200 ° C. to 1300
Firing is performed at a temperature of 2 ° C. for 2 hours (see 7 in FIG. 1B). The fired body thus obtained is further reoxidized in a neutral atmosphere at a temperature of 700 ° C. to 1100 ° C. for a stabilization time of 9 hours (see 8 in FIG. 1B). A terminal electrode made of an indium-gallium alloy is applied and formed on both upper and lower surfaces of the finally formed body.
A multilayer capacitor type measurement sample is completed (see 9 in FIG. 1B). This test sample was subjected to a frequency of 1 KHz and a room temperature of 20
The measurement was performed under the condition of ° C., and the measurement results as shown in Tables 1 to 3 were obtained (see 10 in FIG. 1B). The life test conditions were an applied voltage of 200 V,
It is an evaluation result at a measurement temperature of 200 ° C. The insulation resistance is a value after a measurement voltage of 50 V, a room temperature of 20 ° C. and 30 seconds. Table 1 shows the measurement results obtained in this manner.
It is shown in Table 3. Sample Nos. 12 and 13 in Table 1 and Sample Nos. 14, 15, and 16 in Table 2 and Sample Nos. 1, 2, and 2 in Table 3
3, 5, and 6 are examples of the present invention, and * before the sample No.
Samples marked are outside the scope of the present invention. [Table 1] [Table 2] [Table 3] Tables 4, 5 and 6 show the oxide-converted values of the compositions shown in Tables 1, 2 and 3, respectively. [Table 4] [Table 5] [Table 6] As is clear from Tables 1 to 3, the composition according to the present invention has a high relative dielectric constant of 2000 or more and a small change in the capacitance from -25 ° C. to 85 ° C. within ± 15%. The dielectric loss is as small as 3.3 or less, and the average life is as large as 50 hours. Next, the reasons for limiting the composition range of the dielectric ceramic composition of the present invention will be described. When the content of BaTiO ₃ is less than 94.65 mol%, the relative dielectric constant becomes extremely low, and the capacitance change rate shows a high value exceeding 15% (for example, sample No. 1 in Table 1).
See 3,5 ). When the content of BaTiO ₃ exceeds 98.50 mol%, the relative dielectric constant decreases (for example, sample No. 1 in Table 1).
reference). When CaZrO ₃ is less than 0.50 mol%,
The relative dielectric constant becomes lower (for example, see Sample No. 1 in Table 1). When the content of CaZrO ₃ exceeds 2.32 mol%, the rate of change in capacitance shows a high value of ± 15% or more (see, for example, sample Nos. 4 and 5 in Table 1). When the content of CaTiO ₃ is less than 0.50 mol%,
The relative dielectric constant is low and the capacitance change rate is a high value of ± 15% or more (for example, see Sample Nos. 1, 2 , and 4 in Table 1). When the content of CaTiO ₃ exceeds 3.03 mol%, the relative dielectric constant becomes extremely low (for example, sample No. 1 in Table 1).
3 ). When the MnO content is less than 0.50 mol%, the dielectric loss is extremely high, the insulation resistance is reduced to 1 × 10 ¹⁰ or less, and the average life is extremely small, 5 hours or less (for example, sample No. 1 in Table 1). 6, 7 ). When the content of MnO is more than 2.00 mol%, the insulation resistance becomes as low as 1 × 10 ¹⁰ or less, and practical dielectric properties cannot be obtained (for example, see Sample No. 11 in Table 1). That is, when MnO is in the range of 0.50 mol% to 2.00 mol%, the insulation resistance is large and the temperature characteristics are good. If the content of Y ₂ O ₃ is less than 0.05 mol%, the average life is extremely short at 5 hours or less, which is not suitable for practical use (for example, see Samples Nos. 8 and 9 in Table 1). When the content of Y ₂ O ₃ is more than 0.25 mol%, the dielectric loss becomes extremely large, ie, a value of two digits, and the insulation resistance becomes one.
× 10 ¹⁰ or less, and the average life is extremely short, such as 5 hours or less, so that practical dielectric properties cannot be obtained (for example, the sample shown in Table 1).
No. 6, 10 ). Next, {Baα, Ca (1-α)} SiO ₃
The temperature characteristics are greatly improved by adding
If it is less than 1.00 mol%, the dielectric loss may increase.
(Nos. 6, 7, 10), the insulation resistance also decreases (No.
8, 11). If it exceeds 10.00 mol%, the relative dielectric constant becomes extremely low at 2000 or less (for example, sample No.
17 references. However, in this example, α = 0.58). Further, {Baα, Ca (1-α)} SiO
_{Even if} the content of ₃ is 10.00 mol% or less, if α is less than 0.43 or more than 0.62, sintering becomes difficult and the composition itself cannot be produced (for example, sample No. 4 in Table 3).
7). When put to practical use as a capacitor material, there is a problem in terms of life (reliability) in addition to the electrical characteristics described in JP-A-62-2408. In particular, in the case of the reduction-resistant material as in the present invention, when fired in an atmosphere, the dielectric generally undergoes reduction and the life is generally shortened. The present invention focuses on this point, which was subjected to the addition of Y ₂ O _3, and Y ₂ O ₃ is less than 0.05 mol% mean life becomes 5 hours or less, a point to be a practical problem It can be greatly improved. The dielectric porcelain composition of the present invention has a high relative dielectric constant, a small dielectric loss, a small change rate of capacitance with respect to temperature, and a stable life characteristic. A highly reliable dielectric ceramic composition can be obtained. Such a dielectric porcelain composition has excellent characteristics particularly for a laminated porcelain capacitor having nickel as an internal electrode.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of a production process of a dielectric ceramic composition of the present invention.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor: Soma Ide, 1-13-1 Nihombashi, Chuo-ku, Tokyo Inside TDK Corporation (56) References JP-A-62-278163 (JP, A) JP-A-2 -83256 (JP, A) JP-A-63-221505 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01B 3/12 303 C04B 35/46 H01G 4/12 358

Claims (1)

(57) All Claims composition BaTiO ₃ 94.65 mol% to 98.50 mol% CaZrO ₃ 0.50 mole% ～2.32 mol% CaTiO ₃ 0.50 mole% ～3.03 mol% MnO 0.50 mol% to 2.00 mol% Y ₂ O ₃ 0.05 mol% to 0.25 mol% {Baα, Ca (1-α)} SiO ₃ (where 0.43 ≦ α
≦ 0.62) A dielectric porcelain composition characterized by being in the range of 1 to 10.00 mol%.