JPH0773081B2 - Method for manufacturing oxide semiconductor porcelain for thermistor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing an oxide semiconductor porcelain for a thermistor which requires high reliability and is used in a combustion control circuit or the like in a temperature range of 150 to 500 ° C. It is a thing.

Conventional Technology Conventionally, semiconductor materials for general-purpose thermistors are mainly Mn-Co-
It is an oxide material of a combination of 2 to 4 components of Ni-Cu system and is mainly used as a disk type thermistor, and its operating temperature range is limited to 150 ° C or less. Further, even if it is a glass-encapsulated type or a glass-coated type, the operating temperature range is 300 ° C. at most.

On the other hand, as a material that can be used at a high temperature of 700 to 1000 ° C,
Stabilized zirconia (ZrO ₂ -Y ₂ O ₃ , ZrO ₂ -CaO), Mg-Al-Cr-F
e Oxide spinel system etc. have been developed and used for automobile sensors.

Problems to be Solved by the Invention In such a conventional configuration, in the semiconductor material for general-purpose thermistors, the resistance value variation under high temperature use is large,
It could not be used at a high temperature exceeding ℃. Moreover, in order to obtain a high temperature thermistor, the firing temperature is as high as 1600 ° C or higher, and a normal electric furnace (high temperature 1600 ° C) is used.
(° C) cannot be used for firing. In addition, even with sintered bodies of these oxides, the resistance value changed greatly with time, and even extremely stable ones had a problem of stability with time of about 10% (after 1000 hours).

The present invention solves such a problem, and it is 300-500.
Provided is a method for obtaining an oxide semiconductor porcelain for a thermistor which exhibits an appropriate resistance value even at ° C and can be stably used.

Means for Solving the Problems In order to solve the problems, the present invention has been variously studied, and as a result, the present inventors have already proposed (Japanese Patent Application No. 59-235716).
As metallic elements of Mn 60.0 to 98.5 atomic%, Ni 0.1 to 5.0 atomic%, Cr 0.3 to 5.0 atomic%, Y 0.2 to 5.0 atomic% and Zr 0.
It has a composition containing five kinds of 05 to 28.0 atomic% in total of 100 atomic%, and after sintering at a temperature of 1350 to 1550 ° C, re-burning at a temperature 100 to 300 ° C lower than the above temperature and under pressure. It is the one to conclude. Here, the treatment temperature is limited to 100 to 300 ° C. because the difference from the firing temperature is 100 ° C. or less, the re-sintering is accelerated by pressure, grain growth or pore growth occurs, and the deterioration of the element strength or the aging occurs. It leads to deterioration of stability. Also, if the difference from the firing temperature is 300 ° C. or more, re-sintering does not occur and the effect of pressing does not appear. Similarly, Mn 60.0-98.5 atomic%, Ni 0.1-5.0 atomic%, Cr 0.3-
5.0 atomic%, Y 0.2 to 5.0 atomic% and Zr 0.05 to 28.0 atomic% are contained in total of 100 atomic%, and Si is 2.0 atomic% (excluding 0 atomic%) in proportion to the main component. An oxide semiconductor porcelain for a thermistor, which has a composition containing and is sintered at a temperature of 1350 to 1550 ° C. and then re-sintered at a temperature 100 to 300 ° C. lower than the above temperature and under pressure. The present invention provides a method for manufacturing the same.

Action With this configuration, the ceramic becomes more dense and the resistance aging rate during use at high temperature as a thermistor becomes smaller.

Examples Examples of the present invention will be described below.

ZrO ₂ containing commercially available raw materials MnCO ₃ , NiO, Cr ₂ O ₃ and Y ₂ O ₃
As shown in the table below so as to have a composition of each metal atom%. Mix this in a ball mill and dry,
Calcination in air at 00 ° C for 2 hours. This is ground again with a ball mill, and the obtained slurry is dried. Polyvinyl alcohol is added to this as a binder and mixed, and the required amount is formed into a block of 30 mmφ × 15 mmt. And
The compact is fired in air at 1500 ° C. for 2 hours. The apparent porosity of the sintered body thus obtained is 3% or less. Further, this sintered body was processed using a hot isostatic pressing apparatus. That is, it was re-sintered at 1300 ° C. for 1 hour under a pressure of 1000 atm using an inert gas. Moreover, it heat-processed in the air as needed. The block thus obtained is sliced into wafers having a thickness of 200 μm, platinum electrodes are provided on both surfaces of the wafer, and chips having desired dimensions are processed. This was sealed and sealed in a glass tube with a slag lead as a terminal to obtain a glass-sealed thermistor.

The rate of change with time of resistance of this thermistor after 1500 ° C. and 1500 hours is also shown in the following table.

As can be seen from the above table, according to the embodiment of the present invention,
In both cases, the rate of change in resistance with time is 0.5 to 3.0% smaller than that in the case where re-sintering treatment under pressure and high temperature is not performed, and the effect is recognized. Also, the ceramic itself had a porosity of about 0.4% or less, and was extremely dense and homogeneous with almost no porosity. Furthermore, the reason why the composition range is limited here is that the resistance value as a sensor in the temperature range of 300 to 500 ° C. falls within the range of 100 Ω to 500 KΩ.

50 of the thermistor using the material shown in the drawing as sample No. 3
The change with time of the resistance value at 0 ° C is shown. In the figure, the solid line shows the change according to this embodiment, and the broken line shows the change according to the conventional example in which the hot isostatic pressing process is not performed. As is clear from the figure, the one using the thermistor magnet according to the present invention is very stable.

EFFECTS OF THE INVENTION As described above, according to the present invention, the sintered body of the oxide semiconductor for thermistor is re-sintered under pressure and at a high temperature, so that it is finer and more uniform than conventional products. It is considered to be most suitable for a temperature sensor that has a structure and requires high reliability for a long time at temperatures up to 500 ° C.
In particular, a thermistor manufactured by processing from a block into a chip shape has a small coefficient of variation in the resistance value of the chip-shaped element and is excellent in mass productivity, so it can be expected to be applied to high value-added products. .

[Brief description of drawings]

FIG. 1 is a diagram showing a resistance value aging rate characteristic at 500 ° C. of a glass-filled type thermistor using an oxide semiconductor ceramic for a thermistor according to the present invention and a conventional method.

Claims (2)

[Claims] 1. As a metal element, manganese 60.0 to 98.5 atomic%, nickel 0.1 to 5.0 atomic%, chromium 0.3 to 5.0 atomic%,
Yttrium 0.2-5.0 atomic% and zirconium 0.05-
It has a composition containing 58.0% of 58.0% in total, and after sintering at a temperature of 1350 to 1550 ° C, it is re-sintered at a temperature 100 to 300 ° C lower than the above temperature and under pressure. Manufacturing method of oxide semiconductor porcelain for thermistor. 2. As a metal element, manganese 60.0 to 98.5 atomic%, nickel 0.1 to 5.0 atomic%, black scale 0.3 to 5.0 atomic%,
Yttrium 0.2-5.0 atomic% and zirconium 0.05-
28.0 at.% 5 kinds in total 100 at.%, And a composition containing 2.0 at.% (Not including 0 at.%) Of silicon with respect to the main component, and a temperature of 1350 to 1550 ° C. A method for producing an oxide semiconductor porcelain for a thermistor, which is performed by sintering at 100 to 300 ° C. lower than the above temperature and re-sintering under pressure.