JPS63315550A - Thermistor porcelain composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition having small variability of resistance value and thermistor constant and small change of resistance value with time, by adding Bi as a secondary component to a main component consisting of Mn, Ni, Cu, Co and Zr. CONSTITUTION:A main component consisting of oxide solid solutions of Mn, Ni, Cu, Co and Zr is blended with 0.1-10mol% Bi element as a secondary component and, if necessary, 0.1-10atom.% one or more elements selected from Li, B, Mg, Al, Si, Ti, V, Cr and Zn.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to an oxide thermistor containing Mn, Ni, Cu, Go and Zr as main components, a so-called spinel thermistor.
The present invention relates to a thermistor ceramic composition that has recently come to be used in many devices such as liquid thermometers, switching power supply protection, etc., for temperature detection of ~15C) or as an inrush current prevention element.

Conventional technology Conventionally, this type of Mn-Ni-Cu-10-Zr based thermistor has been able to control the specific resistance and thermistor constant (B constant) over a wide range by changing the ratio of each element, and has been found to be highly compatible with the circuit. This composition is widely used because it is easy to match.

Problems to be Solved by the Invention However, this thermistor also has drawbacks in manufacturing, with large variations in characteristics (resistance value, B constant) during the completion process. Although aging treatment for about 3 to 7 days was required, even this was not sufficient. However, finished products still undergo significant changes over time, making it difficult to manufacture highly accurate thermistors.

The cause of this is not clear, but it is thought to be caused by a complex interaction of scattering of elemental components during firing, stability of cation distribution, sintering reactivity, etc.

The present invention solves these problems, and is aimed at solving these problems.
To provide a stable thermistor ceramic composition which reduces variations (coefficient of variation) in the resistance value and B constant of a thermistor ceramic whose main components are an oxide solid solution of i, Cu, Go, and Zr, and whose resistance value changes over time. The purpose is to

Means for Solving the Problem In order to solve this problem, the present invention provides a thermistor porcelain composition as follows.

(1) The main component is an oxide solid solution of Mn, Ni, Cu, Go, and Zr, and Bil' is added as a subcomponent.

(2) In the above structure, L is added as an elemental component to the main component.
i, B, Mg, Al, Si, Ti, V', Cr, Zn
Add one or more of the following.

Effect: Due to the above (1), variations in resistance value and B constant are reduced, and changes in resistance value over time are also significantly reduced. Moreover, according to the above (2), the change over time can be further suppressed, and a highly accurate thermistor porcelain can be provided. Hereinafter, the present invention will be explained based on specific examples.

First, using commercially available manganese oxide, nickel oxide, copper oxide, cobalt oxide, zirconium oxide, bismuth oxide, etc., predetermined amounts were blended to have the composition shown in Table 1 below.
Mixing was carried out for 20 hours using a ball mill. This is 15
After drying at 0 to 250°C, it was calcined at 700 to 800°C for 2 hours, and the calcined product was ground in a ball mill for 20 hours, and then dried. A 10% p, v, mu (polyvinyl alcohol) solution with a concentration of 10% was added to this calcined powder and mixed to perform granulation. Then, this granulated powder was pressure-molded into a disk shape with a diameter of 10 wm and a thickness of 1.6 cm.
After baking at a temperature of 000 to 1200°C for 2 hours, a silver electrode was provided.

After leaving each disk-shaped thermistor element thus obtained at room temperature for one day, the specific resistance value was measured in an oil bath at 26° C. and 60° C., and the B constant between these temperatures was calculated. The results are shown in Table 2 below. However, these coefficients of variation are also listed at the same time. Furthermore, each thermistor element was left in air at 160° C. for 1000 hours, and the results of determining the resistance value change rate Rt (resistance value after time) are shown in the figure.

For comparison with the thermistor according to the present invention, a thermistor element made of a conventional composition was manufactured using the same method, and the resistance value, B constant, coefficient of variation thereof, and rate of change in resistance value were measured in the same manner and are also listed. did.

(Left below) Table 2 (*: Conventional example) Here, regarding Li, Mg, B, mulch, etc. added to the main components, only one type of specific elements or a combination of two types are listed. However, the inventors have determined that Li,
By adding a predetermined amount of one or more of the elements B, Mg, Mud, Si, Ti, V, Cr, and Zn,
It was confirmed that effects similar to those shown in Table 2 above could be obtained.

Effects of the Invention As is clear from the above results, the thermistor according to the present invention has small variations in resistance value and B constant, is stable in manufacturing, and has small changes in resistance value over time. This can greatly contribute to the demand for higher precision.

Note that in the present invention, Bi oxide is o, 1 mol%
If it is less than 10 mol %, no effect on the coefficient of variation and changes over time of electrical properties will be observed, and if it exceeds 10 mol %, the coefficient of variation will become large and therefore outside the scope of the present invention.

In addition, in the amount of added elements such as Li and Mg shown in the second claim, if it is less than 0.1 atomic %, no effect will be seen as with B1 oxide, whereas if it exceeds 10 atomic % Since the coefficient of variation of the electrical characteristics became large, it was excluded from the scope of the present invention.

[Brief explanation of the drawing]

The figure is a diagram showing the rate of change in resistance value over time of the thermistor element according to an embodiment of the present invention and the conventional thermistor element 1501 when left in air.

Claims (2)

[Claims] (1) Mn, Ni, Cu, Co and Zr as metal elements
as the main component and 0.1 to 10 m of Bi element as a subcomponent.
A thermistor porcelain composition characterized by adding ol%. (2) Mn, Ni, Cu, Co and Zr as metal elements
The main component is Li, B, Mg, Al, Si, Ti.
, V, Cr, and Zn elements.
．． 1. A thermistor ceramic composition containing 1 to 10 atomic % of Bi as a main component and 0.1 to 10 mol % of Bi as a subcomponent.