JP2584985B2 - Semiconductor porcelain composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a porcelain composition suitable for a semiconductor porcelain capacitor as a passive electronic component in an electronic machine or a device, particularly a reduced reoxidation type semiconductor porcelain capacitor.

[Conventional technology]

Semiconductor ceramic capacitors as passive electronic components include a grain boundary insulating type as a grain boundary layer type, and are roughly classified into a surface layer type into a weir layer capacity type and a reduction / reoxidation type.

In general, the grain boundary insulating type has a smaller capacity than the weir layer capacity type, and has a smaller withstand voltage than the reduced reoxidation type. The weir layer capacitance type has poor frequency characteristics, a large dielectric loss tan δ, and a small withstand voltage. The reduction-reoxidation type has a problem in that if the capacitance per unit area (μF / cm ² ) is increased, the breakdown voltage value becomes smaller, the dielectric loss becomes larger, or the temperature characteristic of the capacitor becomes larger. there were.

[Problems to be solved by the invention]

The present invention is directed to a reduction-re-oxidation type semiconductor ceramic capacitor which eliminates the above-mentioned disadvantages and has a capacitance per unit area C μF / cm.
^The object of the present invention is to obtain a semiconductor ceramic composition having a large value of ² , a high withstand voltage, and a good temperature characteristic.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a semiconductor ceramic composition containing BaTiO ₃ as a main component and niobium as a subcomponent.
Colt is added to components containing 0.2 to 3.0 mol% in terms of Nb ₂ O ₅ and 0.2 to 3.0 mol% in terms of CeO ₂ in terms of CeO _2.
0.8% by weight or less in terms of ₃ O ₄ , manganese in terms of MnCO ₃ is 0.25% by weight or less, silicon oxide SiO ₂ is 0.25% by weight or less, and SrTiO ₃ is 0.5 to 20.0% by weight. (100-xy) BaTiO ₃ + xNb ₂ O ₅ + yCeO ₂ based semiconductor ceramic composition is used.

 Here, x and y are respectively 0.2 ≦ x ≦ 3.0 and 0.2 ≦ y ≦ 3.0 mol%.

Further, the present invention further comprises yttrium in the above composition.
A semiconductor porcelain composition added with 0.1 to 3.0% by weight in terms of Y ₂ O ₃ can be used.

〔Example〕

BaCO ₃ , TiO ₂ , Nb ₂ O ₅ , CeO ₂ ,
Using Co ₃ O ₄ , MnCO ₃ , SiO ₂ , SrCO ₃ , and Y ₂ O ₃ , weigh them so as to have the compounding ratio shown in Table 1, and wet-mix and stir these raw materials for 20 hours with a synthetic resin ball mill. After that, it is dehydrated and dried, and temporarily calcined at 1200 ° C. for 2 hours, and this is rotationally pulverized with a synthetic resin ball mill for 20 hours. 2% by weight
The organic binder polyvinyl alcohol (PVA) is added and granulation and sizing is performed to obtain a granular powder, and a powder having a diameter of 10 mm and a thickness of 0.5 mm is formed from the powder at a molding pressure of about 3 ton / cm ^2. . The molded article is subjected to a binder removal treatment at 800 ° C. for 1 hour, and thereafter, is calcined at 1300 ° C. for 2 hours. This is reduced in a reducing atmosphere (H ₂ gas atmosphere) at 800 ° C. for about 2 hours to produce a reduced semiconductor porcelain, which is then placed in an oxidizing atmosphere (in air).
Heat treatment at 800 ° C for 2 hours to re-oxidize only the surface of the semiconductor porcelain, then print and apply Ag paste on both sides of this porcelain element and bake at 800 ° C to form electrodes to form a reduced reoxidized semiconductor porcelain capacitor Obtained.

Table 1 shows the results of measuring the electrical characteristics of the samples thus obtained.

Here, the capacitance C and the dielectric loss tan δ are frequency 1 kHz,
Measured at 1V. Insulation resistance IR is 20 V at room temperature by applying DC 25 V
Measured in ° C.

In Table 1, the device according to the present invention has a large capacitance C, a high DC breakdown voltage _Vb , and a large insulation resistance IR, and has an excellent temperature characteristic.

Next, the reasons for limiting the composition ratio in the present invention will be described. When Nb ₂ O ₅ is less than 0.2 mol% or more than 3.0 mol%, the capacity C per unit area (μF / cm ² ) is small. ,
The dielectric loss tanδ is large. In addition, IR and _Vb also become lower (Sample Nos. 1, 2, 3, 17, 18, and 19).

If CeO ₂ is less than 0.2 mol%, C is small and tan δ is large, and if it exceeds 3.0 mol%, tan δ is large. Also, the temperature characteristic TC deviates from the D characteristic standard (Sample Nos. 1, 3, 8, 1
3,17,19).

When Co ₃ O ₄ exceeds 0.8 wt%, C becomes smaller (Sample No. 2
Four).

When MnCO ₃ exceeds 0.25 wt%, _Vb decreases (Sample No. 2
7).

When SiO ₂ exceeds 0.25 wt%, C is small and IR and _Vb are low (Sample No. 30).

If SrTiO ₃ is less than 0.5% by weight, tan δ does not decrease significantly. On the other hand, when the content exceeds 20.0 wt%, TC largely deviates from the D characteristic, and V _b and IR become small (samples No. 31, 36, 38, 39, 40, 43,
44,47,49).

When Y ₂ O ₃ is less than 0.1% by weight, _Vb is low, and when Y ₂ O ₃ is more than 3.0% by weight, C decreases (Sample Nos. 37 and 48).

〔The invention's effect〕

The present invention relates to a BaTiO ₃ + Nb ₂ O ₅ + CeO ₂ based semiconductor porcelain composition comprising BaTiO ₃ as a main component, Nb ₂ O ₅ , CeO ₂ , Co ₃ O ₄ , MnC
By containing O ₃ , SiO ₂ and SrTiO ₃ as sub-components, when this is used for a reduction-re-oxidation type semiconductor ceramic capacitor, a capacitor having a large capacity, a high withstand voltage, and a good temperature characteristic can be obtained. It is a thing. In addition, Y ₂ O ₃
By adding, the insulation resistance and the DC breakdown voltage are improved, and a good temperature characteristic is obtained, so that the performance of the conventional reduced re-oxidation type semiconductor ceramic capacitor can be improved.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuaki Kikuchi 1-1-13 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation (56) References JP-A-61-193419 (JP, A) JP-A-51 -10814 (JP, A) JP-A-52-92399 (JP, A)

Claims (4)

(57) [Claims] 1. A component containing BaTiO ₃ as a main component, niobium as a sub component in an amount of 0.2 to 3.0 mol% in terms of Nb ₂ O ₅ , and cerium in an amount of 0.2 to 3.0 mol% in terms of CeO ₂ . 0.8% by weight or less of cobalt in terms of Co ₃ O ₄ , 0.25% by weight or less of manganese in terms of MnCO ₃ , 0.25% by weight or less of silicon oxide SiO ₂ , and 0.5 to 20.0% by weight of SrTiO ₃ (100-xy) BaTiO ₃ + x · Nb ₂ O ₅ + y · Ce
O ₂ based semiconductor porcelain composition. However, x and y are respectively 0.2 ≦ x ≦ 3.0 and 0.2 ≦ y ≦ 3.0 mol%. 2. The (100-xy) BaTiO ₃ + x according to claim 1, wherein the surface layer of the semiconductor porcelain obtained by molding and sintering the composition comprising said components is insulated.・ N
_{b 2 O 5 + y · CeO} 2 based semiconductor ceramic composition. _{3. A} composition containing BaTiO ₃ as a main component, niobium as an auxiliary component in an amount of 0.2 to 3.0 mol% in terms of Nb ₂ O ₅ , and cerium in an amount of 0.2 to 3.0 mol% in terms of CeO ₂ . Cobalt is converted to Co ₃ O ₄ at 0.8% by weight or less, manganese is converted to MnCO ₃ at 0.25% by weight or less, silicon oxide SiO ₂ is 0.25% by weight or less, SrTiO ₃ is 0.5 to 20.0% by weight, and yttrium is Y ₂ O ₃ in terms of and wherein 0.1 to 3.0 that have wt% respectively added _{(100-xy) BaTiO 3 +} x · Nb 2 O 5 + y · CeO 2 based semiconductor ceramic composition. However, x and y are respectively 0.2 ≦ x ≦ 3.0 and 0.2 ≦ y ≦ 3.0 mol%. 4. The (100-xy) BaTiO ₃ + x according to claim 3, wherein the surface layer of the semiconductor porcelain obtained by molding and sintering the composition comprising the components is insulated.・ N
_{b 2 O 5 + y · CeO} 2 based semiconductor ceramic composition.