JPH0265214A - Porcelain composition and porcelain for reduction reoxidation type semiconductor capacitor - Google Patents

Abstract

PURPOSE:To contrive accomplishment of a large capacitance all the more with high withstand voltage being maintained by a method wherein the title porcelain composition is composed of the main components of specific parts by weight, Mn compound and SiO2, and said main components are composed of BaTiO3, La2O3, an oxide of the rare-earth element consisting at least of a kind selected from among Ce, Pr, Nd, Sm and Y, TiO2 and CaZrO3. CONSTITUTION:The title porcelain composition is composed of the main components of 100.00 pts.wt., an Mn compound of 0.03 to 0.30 pts.wt. in terms of Mn, and SiO2 of 0.05 to 0.50 pts.wt. The main components are composed of BaTiO3 of 81.5 to 96.5mol.%, La2O3 of 1.0 to 4.0mol% in terms of La, an oxide of the above-mentioned rare-earth element of 0.5 to 3.0mol% in terms of rare-earth element consisting at least of a kind selected from Ce, Pr, Nd, Sm and Y, TiO2 of 1.9 to 10.0mol%, and CaZrO3 of 0.1 to 1.5mol%. When a reduction reoxidation type semiconductor capacitor is manufactured using the above-mentioned porcelain composition, the electrostatic capacitance C of 0.6/cm<2> or more per unit area and dielectric breakdown voltage C of 500V or higher can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ceramic composition and ceramic for reduction and reoxidation type semiconductor capacitors.

[Prior Art] A reduction and reoxidation type semiconductor ceramic capacitor is known as a type of semiconductor ceramic capacitor. The dielectric of this reduction-reoxidation type semiconductor ceramic capacitor is made of barium titanate ceramic, and as disclosed in Japanese Patent Publication No. 63-28492, for example, it is made of barium carbonate (B a CO2) and titanium oxide (TiO2). Oxides of rare earth elements (Nd, P
Mixture eA (raw material composition) consisting of at least one oxide of r, 3m, Bu, Gd, Dy, La) and at least one oxide of Cr, Mn, , Fe, Co and Ni is prepared, this molded body is formed, this is sintered in an oxidizing atmosphere, the obtained sintered body is heat-treated in a reducing atmosphere, and further heat-treated in an oxidizing atmosphere (re-oxidation treatment).
and get it.

[Problems to be solved by the invention] The reduction and reoxidation type semiconductor ceramic capacitor described above has the following problems:
It has the advantage of being able to increase capacity and obtain a high withstand voltage. However, with conventional ceramic compositions, it has been difficult to increase the capacity while maintaining a high withstand voltage. That is, the dielectric breakdown voltage Vbd is set to 600 cm, for example.
If you try to make it more than that, the capacitance per unit area C becomes 0.
．． If the capacitance C is reduced to 3 to 0.6 μF/cm2 or more, and if the capacitance C is increased to 0.7 μF/cm2 or more, the dielectric breakdown voltage Vbd will decrease to about 300 to 400 μF.

Therefore, an object of the present invention is to reduce the dielectric breakdown voltage Vbd to 500
V or more, capacitance per unit area C or 06μF/cm2
The object of the present invention is to provide a ceramic composition and ceramic that can produce the above-mentioned reduction and reoxidation type semiconductor ceramic capacitor.

[Means for Solving the Problems] The present invention for achieving the above object includes 10,000 parts by weight of the main component and 0.03 to 0 in terms of Mn (manganese).
．． It consists of 30 parts by weight of Mn compound, 0.05 to 0.50 parts by weight of 8102 (silicon 'ei), and the main components include 81.5 to 965 mol% of Ba (barium titanate) and La. (calculated as lanthanum), 1.0 to 4.0 mol% of La 203 <lanthanum oxide), Ce (cerium), Pr (praseodymium), Nd (neodymium),
05 to 3.0 in terms of rare earth element consisting of at least one of Sm (samarium) and Y (yttrium)
mol % of said rare earth element oxide, and 1.9 to 10.0
mol % of T i O2 (titanium oxide) and 0.1 to 1.
The present invention relates to a ceramic composition for a reduction and reoxidation type semiconductor ceramic capacitor characterized by comprising 5 mol% of Ca Z r O3 (calcium zirconate).

Incidentally, the porcelain according to claim 2 can be obtained by firing and heat-treating the above-mentioned porcelain composition.

[Function] When a reduced and reoxidized semiconductor ceramic capacitor is manufactured using the ceramic composition according to the present invention, it has a dielectric breakdown voltage Vbd of 500 V or more and a capacitance C per unit area of 0.6 μF/cm2 or more. be able to.

[Example] Next, the present invention will be explained in detail.

In order to obtain the main component of the composition of Sample No. 1 in Table 1, B a T i O3 was mixed at 2000. OOg (90,8
mol%), 29.23g of La2O3 (19mol% in terms of La), 12.71g of Nd2O3 (0°8 mol% in terms of Nd), 11.38g of CeO2 (in terms of Ce) 0°7 mol%), 9.34 g of Pr2o3 (0°6 mol% in terms of Pr), 31.69 g of TiO2 (4.2 mol%), Ca
16.93 g (1.0 mol %) of Z r O3 was weighed. That is, 90.8 mol% of B a T iO3 and L
1.9 mol% of a, 0.8 mol% of Nd, and 0 of Ce.
．． 7 mol%, 0.6 mol% of Pr, and 4 of T 102
, 2 mol% and 1.0 mol% of CaZrO3 is 1
B a T iOL a O so that it becomes 00 mol%
Weighing N d 203, CeO3・2 3゛Pr OTiO2,, CaZrO3 2-23
゛Shina.

In addition, M n C03 (manganese carbonate) is added as an additive component.
and 4.22 g of S i 02 were weighed. In addition, the total weight of the above main components and 4.42 g of M n
, C03 is 100 parts by weight of the above main component and 0 parts by weight.
．． This corresponds to a ratio of 1 part by weight of Mn. Also, the ratio between the total weight of the above main components and 4.22 g of SiO2 is 10
This corresponds to a ratio of 0 parts by weight of the main component and 02 parts by weight of SjO2. In short, 1. Weigh Mn, CO, and 5102 so that the amount of Mn is 0.1 part by weight and the amount of S102 is 0.2 part by weight based on the main component of O0 parts by weight.

Next, the above main components and additive components are wet-mixed, and after dehydration and drying, an organic binder is added and kneaded.
11111, obtain a cylindrical molded body with an inner diameter of 0.9 mm, a thickness of 0.3 null, and a length of 3.71 mm.

Next, the obtained molded body is fired at 1320°C in the air for 2 hours to obtain a sintered body of dielectric (insulator) porcelain, and this dielectric porcelain is heat-treated at 1050°C for 2 hours in a reducing atmosphere ( The obtained semiconductor porcelain is further treated in the atmosphere at 970°C for 1 hour (reoxidation treatment) to form the surface of the semiconductor porcelain 1 as shown in principle in the drawing. Dielectric layer 2 was created. Note that the composition of the semiconductor ceramic 1 corresponds to the raw material composition. Further, the surface dielectric layer 2 is made of an oxide of the semiconductor ceramic 1.

Next, silver (Ag) pastes 1 to 1 were coated on the surface dielectric layer 2 and baked at 850° C. for 10 minutes to form a pair of electrodes 3.4, thereby completing a semiconductor ceramic capacitor.

Lead wires were soldered to the electrodes 3.4 of the obtained capacitor, and the capacitance per unit area C2 tan δ and insulation resistance IR1 dielectric breakdown voltage Vbd were measured, and as shown in Table 2, C was 0.゜80JJ, F/cm2, t
anδ is 3.2%, IR is 1.9X104MΩ, Vbd
was 750■.

Note that C and tan δ were measured under the conditions of a measurement voltage of 0.1■ and a measurement frequency of 1kHz, and IR was measured at a DC voltage of 50V at 15V.
The voltage was applied for a second and then measured, and Vbd was measured using a DC boost breakdown method.

In order to confirm that there is little variation in characteristics due to changes in temperature during firing in the atmosphere (-second firing), the -second firing temperature was set to 13.
A semiconductor capacitor was made under the same conditions as in the case of 1320°C except that the temperature was changed to 10°C and 11300°C, and its characteristics were measured.As shown in Table 2, C was 0.78 and 0.77μF/cm2. tan δ is 31% each
, IR is 1°9X104 and 1.8X104MΩ, Vb
d was 700V each.

Capacitors for Samples Nos. 2 to 44 were made in the same manner as in Sample No. 1, except that the compositions were changed as shown in Table 1, and the electrical characteristics were measured in the same manner.

In Table 1 showing the composition of the porcelain composition, the main component B
a T io 3 and La and X and TiO2 and CaZr O
3 is given in mole %. X contained in the main component is a rare earth element consisting of at least one of Ce, Pr, Nd, Sm, and Y. Additional components Mn and S 10
2 is shown in parts by weight added to 100 parts by weight of the main component.

Table 2 (Continued)] Table 2 (Continued) Table 2 (Continued) Table 2 (Continued) As is clear from Tables 1 and 2, According to the composition according to the invention, the dielectric breakdown voltage Vbd is 500 to 800
, the capacitance per unit area is 06~0.8μF/c
m'' capacitor can be obtained.

On the other hand, sample No. 2.6.20.21.23.26.
27.30.31.34.35.39.40.44 cannot achieve the purpose of the present invention.

Therefore, these are outside the scope of the present invention and are listed as ratio axis examples.

Next, the reason for limiting the composition will be explained.

When La is less than 1.0 mol%, the effect of adding La becomes too small, and the dielectric breakdown voltage Vbd of the capacitor becomes lower than the target value. On the other hand, when L and a exceed 4.0 mol%, the dielectric constant of the surface dielectric layer 2 decreases,
The capacitance C per unit area becomes smaller than the target value.

Therefore, the preferred range of La is 10 to 4.0 mol%.

X (at least one of Ce, Pr, Nd, Sm, Y)
When the total of one or more types is less than 0.5 mol%,
It becomes impossible to obtain a sufficient effect of increasing the dielectric constant of the surface dielectric layer 2, and the capacitance C becomes less than the target value. On the other hand, when X exceeds 3.0 mol%, the breakdown voltage V
bd becomes lower than the target value. Therefore, the preferred range of X is 0.5 to 3.0 mol%.

When B a T jO3 is outside the range of 81.5 to 96.5 mol % and T 102 is outside the range of 1.9 to 10.0 mol %, sinterability deteriorates, and capacitance C and dielectric breakdown occur. Voltage Vbd decreases.

Does CaZrO3 have the effect of improving sinterability?01 mol%
If it is less than 1.5, you will hardly get the effect.
If the amount exceeds mol%, the dielectric constant of the surface dielectric layer 2 decreases. Therefore, the preferred range of Ca Z r 03 is 0.1 to 1
．． It is 5 mol%.

If Mn is less than 0.03 parts by weight, it becomes difficult to uniformly form the surface dielectric layer 2, and the dielectric breakdown voltage Vbd
or decrease. When Mn is increased more than 0.30 parts by weight,
It becomes difficult to form the surface dielectric layer 2 thinly, and it is impossible to increase the capacitance C while keeping the dielectric breakdown voltage Vbd high.

Therefore, the preferred range of Mn is 0.03 to 0.30 parts by weight.

SiO□ has the effect of widening the range of primary firing temperature, but if this SiO2 is less than 0.05 weight, hardly any effect can be expected. If SiO2 exceeds 0.5 parts by weight, the dielectric constant and capacitance of the dielectric layer 2 will decrease, the sintering condition will deteriorate, and the dielectric breakdown voltage will decrease. Therefore, the preferred range for S102 is 0.
05 to 0.50 parts by weight.

[Modifications] The present invention is not limited to the above-described embodiments, and, for example, the following modifications are possible.

(1) MnO2 may be used instead of MnC0.

(2) The temperature during firing (sintering) in an oxidizing atmosphere is set to 1
260-1400°C1 Reducing atmosphere heat treatment temperature 900-1180°C1 Re-oxidation treatment temperature 900-1
It can be changed within a range of 100°C.

(3) B a CO3 instead of B a T iO3
and TiO2 may be used as starting materials.

(4) The dielectric layer 2 under one of the electrodes 3, 4 can be omitted.

[Effects of the Invention] As described above, according to the present invention, the dielectric breakdown voltage is 500V.
Above, the capacitance per unit area is 0.6μF/c
It becomes possible to provide a semiconductor ceramic capacitor of m 2 or more.

[Brief explanation of the drawing]

The drawing is a sectional view showing the principle of a ceramic capacitor according to an embodiment of the present invention. 1... Semiconductor ceramic, 2... Surface dielectric layer, 3.4.
··electrode.

Claims (1)

[Scope of Claims] [1] 100.00 parts by weight of the main component, 0.03 to 0.30 parts by weight of Mn compound in terms of Mn (manganese), and 0.05 to 0.50 parts by weight SiO_2 (silicon oxide), the main component of which is 81.5 to 96.5 mol% BaTiO_
3 (barium titanate), 1.0 to 4.0 mol% La_2O_3 (lanthanum oxide) in terms of La (lanthanum), Ce (cerium), Pr (praseodymium), N
0.5 to 3.0 mol % of the rare earth element oxide, calculated as a rare earth element, consisting of at least one of d (neodymium), Sm (samarium), and Y (yttrium); 10.0 mol% TiO_2 (titanium oxide)
and 0.1 to 1.5 mol% of CaZrO_3 (calcium zirconate). [2] 100 parts by weight of the main component, 0.03 to 0.30 parts by weight of Mn, and 0.05 to 0.5 in terms of SiO_2
It consists of a semiconductor ceramic containing 0 parts by weight of Si, and a dielectric layer made of an oxide of the semiconductor ceramic formed on the surface of the semiconductor ceramic, and the main component is 81.5 to 96. 5 mol% BaTiO_
3, 1.0 to 4.0 mol% La, and 0.5 to 3.0
Mol% of X (where X is Ce, Pr, Nd, Sm and Y
at least one rare earth element), 1.9 to 10.0 mol% Ti in terms of TiO_2, and 0.1 to 1
．． A reduction and reoxidation type semiconductor capacitor porcelain characterized by containing 5 mol% of CaZrO_3.