JPH0645104A - Manufacture of semiconductor procelain with positive temperature coefficient of resistance - Google Patents

Abstract

PURPOSE:To provide the manufacturing method for a BaTiO3 semiconductor porcelain having a high resistance temperature coefficient at room temperature and a positive resistance temperature coefficient with which a high reliability can be accomplished on an element. CONSTITUTION:After the material, which is indicated by the formula Ba4(Ti13-xMnx)O30 (X=0.1 to 2) has been added to the material which is mainly composed of barium titanate containing the semiconductor element such as rare earth element of Y and the like, Nb, Sb etc., they are fired.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a barium titanate (BaTiO ₃ ) based semiconductor ceramic having a positive temperature coefficient of resistance, and a method for improving the temperature coefficient of resistance.

[0002]

2. Description of the Related Art In recent years, barium titanate (BaTiO ₃ ) based semiconductor ceramics having a large positive temperature coefficient of resistance have been developed. This barium titanate-based semiconductor porcelain rapidly increases in resistance when it exceeds the Curie point and reduces the amount of current passing through it, so it is used for circuit overcurrent protection and for degaussing the CRT frame of TV receivers. Widely used for purposes. As a barium titanate-based semiconductor ceramic having a positive temperature coefficient of resistance having such characteristics, for example, a barium titanate (BaTiO ₃ ) -based main component material containing Sb,
At least one of Bi, Nb, Ta or rare earth elements
It is known that a small amount of seed is added to form a semiconductor. As the range of applications and demands for performance have become more severe, various researches have been conducted to further increase the positive temperature coefficient of resistance in order to meet the demands, and have reached the present day.

As a result of such research, as a method of improving the temperature coefficient of resistance of a BaTiO ₃ -based semiconductor ceramic having a positive temperature coefficient of resistance, BaTiO ₃ -based semiconductor was
After immersing in a solution containing u, Fe, Mn, etc., heat treatment is applied to Cu, Fe, M only at the grain boundaries of the sintered body.
A method of diffusing n or the like (Japanese Patent Publication No. Sho 50-36035), or a method of calcination to prepare BaTiO ₃ powder and then mixing Mn ₂ O ₃ etc. and performing main calcination has been proposed. There is.

[0004]

However, in the former method among the above-mentioned conventional methods, since the solution does not easily penetrate into the inside of the sintered body, Cu, Although Fe, Mn, and the like diffuse, they do not easily diffuse to the grain boundaries inside the fired body, which makes it difficult to obtain a homogeneous semiconductor porcelain.

Further, the latter method has a problem that the room temperature resistance increases because Mn and the like diffuse into the crystal grains.

The present invention solves the above problems and has a high temperature coefficient of resistance at room temperature and a positive temperature coefficient of resistance that can realize high reliability of the device.
It is an object of the present invention to provide a method for manufacturing an aTiO ₃ based semiconductor ceramic.

[0007]

In order to achieve the above object, a method for manufacturing a semiconductor ceramic having a positive temperature coefficient of resistance according to the present invention is a rare earth element such as Y or Nb, Sb.
To the barium titanate-based main component material containing a semiconducting element such as the formula: Ba ₄ (Ti _13-X Mn _X ) 0 ₃₀ (X =
0.1 to 2) is added and mixed, and then this is fired.

The semiconductor having the positive temperature coefficient of resistance is
In the method for manufacturing body porcelain, the barium titanate-based main component is used.
Formula for material: Ba_Four(Ti_13-XMn_X) 0₃₀(X =
The addition ratio of the materials shown in 0.1-2) is 0.1-2
% Is preferable. Positive resistance temperature coefficient of the present invention
In a method of manufacturing a semiconductor porcelain having a number of Four
(Ti_13-XMn_X) 0₃₀(X = 0.1-2) during firing
Becomes a liquid phase and becomes BaTiO 3.₃Of the crystal particles of the main component material
In order to surround the surroundings, around the particles after firing,
Then, a high concentration layer of Mn is formed near the grain boundary, and the PTC is increased.
It becomes possible to do.

[0009]

EXAMPLES The features of the present invention will be described in more detail below by showing Examples and Comparative Examples of the present invention.

(Example 1) First, BaCO ₃ , TiO ₂ ,
Each of SrCO ₃ , TiO ₂ , Y ₂ O ₃ , and SiO ₂ has a predetermined composition represented by the following formula (1): (Ba _0.946 Sr _0.05 Y _0.004 ) TiO ₃ + 0.01SiO ₂ (1) Mix in different proportions.

Then, this is put in a polyethylene pot together with pure water and zirconia balls, pulverized and mixed for 5 hours, and then calcined at 1100 ° C. for 2 hours to prepare a barium titanate-based main component material.

Furthermore, BaCO ₃ , TiO ₂ , and Mn ₂
0 ₃ each was mixed in the following formula (2): Ba ₄ (Ti _13-X Mn _X ) 0 ₃₀ (2) in a prescribed composition ratio,
Put it in a polyethylene pot with pure water and zirconia balls, pulverize and mix for 5 hours, then dry, 1300 ° C
Calcination for 2 hours. Then, the calcined powder, together with pure water and zirconia balls, was placed in a polyethylene pot and ground for 10 hours to adjust the particle size to an average particle size of about 1 μm, and then dried to obtain the above formula (2). ) To obtain a material (additive substance). The value of Mn amount X is 0
It was changed in the range of ~ 5.

The above (Ba _0.946 Sr _0.05 Y _0.004 ) T
TiO ₃ + 0.01SiO ₂ (formula (1)) barium titanate-based main component material and Ba ₄ (Ti _13-X Mn _X ) 0
₃₀ (equation (2)) and the material represented by Ba ₄ (Ti _13-X M
n _X) content of 0 ₃₀ is formulated such that 0.5 mol%, further added a binder 5 wt% of vinyl acetate. Then, this is put in a polyethylene pot together with pure water and zirconia balls, pulverized and mixed for 5 hours, dried, and press-molded by a press molding machine to obtain a diameter of 17 m.
Create a disk-shaped molded body with m and a thickness of 3 mm. then,
The molded body was fired at 1350 ° C. for 1 hour to obtain a semiconductor ceramic. Next, an In—Ga alloy is applied to both main surfaces of this semiconductor porcelain to form electrodes, which are used as samples for room temperature (2
The specific resistance and the temperature coefficient of resistance at 5 ° C.) were measured.

Comparative Example 1 For comparison, Ba ₄ (Ti
Without adding (post-adding) _13-X Mn _X ) 0 ₃₀ separately,
_{BaCO 3, TiO 2, SrCO 3} , TiO2, Y 2 O 3, S
Mn ₂ O ₃ was mixed with iO _{2 in} a proportion such that the final composition of the barium titanate-based semiconductor ceramic of Example 1 was the same, and the mixture was fired to prepare a barium titanate-based semiconductor ceramic. That is, the semiconductor porcelain of the comparative example was produced by the same method as in Example 1 except that there was no step of adding Ba ₄ (Ti _13-X Mn _X ) 0 ₃₀ afterwards separately. The final composition of the porcelain, the method for preparing the sample, and the like are the same as in Example 1 above.

In the above Example 1 and Comparative Example 1, Mn
FIG. 1 shows the change in the temperature coefficient of resistance when the amount X is changed. As is clear from FIG. 1, the temperature coefficient of resistance of Example 1 is higher than that of Comparative Example 1, and in particular, by setting the Mn content X to be 0.1 or more, 10% / ° C. or more which is practically required. It was found that a high temperature coefficient of resistance of was obtained.

The resistance temperature coefficient is a value calculated by the following equation (3). Resistance temperature coefficient = {2.303 / (T2-T1)} × 100 (3) where T1: temperature when resistance becomes 10 times room temperature resistance (° C) T2: resistance becomes 100 times room temperature resistance When temperature (℃)

Further, FIG. 2 shows room temperature specific resistances of Example 1 and Comparative Example 1. The specific resistance is a value calculated by the following equation (4). Specific resistance = R × (S / L) (4) where R is the resistance value, S is the surface area, and L is the thickness.

From FIG. 1, the room temperature resistivity increases as the Mn content X increases, and comparing Example 1 with Comparative Example 1, Example 1 has a lower room temperature resistivity, and Example 1 shows , Mn amount X was 2 or less, it was found that a particularly low specific resistance value was obtained.

Example 2 Except that the Mn amount X was kept constant at 0.5 mol% and the addition amount of Ba ₄ (Ti _{13 -X} Mn _X ) 0 ₃₀ was changed within the range of 0 to 5 mol%. Barium titanate-based semiconductor porcelain was prepared by the same method as in Example 1, and the specific resistance and the temperature coefficient of resistance at room temperature (25 ° C.) were measured.

(Comparative Example 2) Ba ₄ (Ti _13-X Mn _X ) 0 ₃₀
Without adding (post-adding) separately, BaCO ₃ , Ti
SiO _2, Mn ₂ O ₃ , together with O ₂ , SrCO ₃ , TiO ₂ , and Y ₂ O ₃ , were mixed in a ratio such that the final composition of the barium titanate-based semiconductor ceramic of Example 2 was the same, and the mixture was fired. By doing so, a barium titanate-based semiconductor ceramic was prepared. Therefore, the final composition of the semiconductor porcelain, the method for preparing the sample, and the like are the same as in Example 2 above.

In Example 2 above, Ba ₄ (Ti _13-X
FIG. 3 shows changes in the temperature coefficient of resistance when the amount of Mn _X ) 0 ₃₀ added was changed. As is clear from FIG. 3, the temperature coefficient of resistance of Example 2 is higher than that of Comparative Example 2, and in particular, Ba
It was found that a high temperature coefficient of resistance of 10% / ° C. or more can be obtained by setting the addition amount of ₄ (Ti _13-X Mn _X ) 0 ₃₀ to 0.1 mol% or more.

Further, FIG. 4 shows room temperature specific resistances of Example 2 and Comparative Example 2. From FIG. 4, the room temperature resistivity is Ba ₄ (Ti
_13-X Mn _X) increases with increasing 0 ₃₀ amount of, also, Example 2 and is compared with Comparative Example 2 towards the second embodiment is low room temperature resistivity, for Example 2, Ba ₄ ( Ti
It was found that a particularly low specific resistance value was obtained when the amount of _13-X Mn _X ) 0 ₃₀ added was 2 mol% or less.

[0023]

As described above, according to the method of manufacturing a semiconductor ceramic having a positive temperature coefficient of resistance of the present invention, a barium titanate-based main component containing a rare earth element such as Y or a semiconducting element such as Nb or Sb is used. For the constituent materials, the formula: Ba ₄ (Ti _13-X M
n _X ) 0 ₃₀ (X = 0.1-2) is added and mixed, and then the composition is fired, so that a barium titanate-based semiconductor ceramic having a positive resistance temperature characteristic can be obtained. The temperature coefficient of resistance at room temperature can be significantly increased.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the Mn content X and the temperature coefficient of resistance of Example 1.

FIG. 2 is a graph showing the relationship between the Mn content X and the room temperature specific resistance of Example 1.

FIG. 3 shows Ba ₄ (Ti _13-X Mn _X ) 0 _{30 of} Example 2.
It is a diagram which shows the relationship between the amount of addition and a temperature coefficient of resistance.

FIG. 4 shows Ba ₄ (Ti _13-X Mn _X ) 0 _{30 of} Example 2.
It is a diagram which shows the relationship between the amount of addition and room temperature specific resistance.

Claims (2)

[Claims] 1. A barium titanate-based main component material containing a rare earth element such as Y or a semiconducting element such as Nb or Sb is added to the formula: Ba ₄ (Ti _13-X Mn _X ) 0 ₃₀ (X = 0. 1 ~
A method for manufacturing a semiconductor ceramic having a positive temperature coefficient of resistance, which comprises adding and mixing the materials represented by 2) and then firing the mixture. 2. The formula: Ba ₄ (Ti _{13 -X} Mn _X ) 0 ₃₀ (X = 0.1) for the barium titanate-based main component material.
2. The method for producing a semiconductor porcelain having a positive temperature coefficient of resistance according to claim 1, wherein the addition ratio of the material represented by 2) is 0.1 to 2 mol%.