JPH0354150A - Thermistor porcelain composition - Google Patents

Abstract

PURPOSE:To obtain a spinel-based thermistor porcelain composition having extremely high strength of porcelain without changing electrical properties comprising Mn, Ni and Co as main components and Pb as an auxiliary component. CONSTITUTION:A composition comprising main components of Mn, Ni and Co as metallic elements is blended with 0.1-10.0 atomic % Pb as an auxiliary component and optionally further 0.1-10.0 atomic % based on the main components of at least one of B and Si to give a high-strength thermistor porcelain composition. In the composition, a liquid-phase reaction partially occurs at a point of sintering, a spinel phase of main component elements is precipitated during cooling, then Pb, B and Si of addition elements remain in a grain boundary and a glass phase is formed to contribute to increase in strength.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thermistor porcelain assembly having a summer temperature coefficient used for temperature measurement, temperature compensation, etc.

Conventional technology In recent years, oxide-based thermistor ceramics, so-called spinel-based thermistor ceramics whose main components are Mn, Ni, and Co, have been made into chips in line with the trend of becoming lighter, thinner, shorter, and smaller, and the requirements for ceramic elements are also increasing in precision. In addition to this, high strength has become a necessary condition.

Problems to be Solved by the Invention When using Subinel-based thermistor porcelain whose main components are Mn, Ni and Co as described above, the form and method of use vary depending on the product. The loads placed on the ceramic element include spring pressure in the type that holds the ceramic element, fitting pressure in the type that fits the cassob-shaped electrodes on both ends of the cylindrical ceramic element, and even heat shock during soldering. There was quite a lot. For this reason, although the high strength of ceramic porcelain greatly influences not only the work efficiency in the process but also the reliability of the product, conventional spinel-based thermistor porcelain does not necessarily have high strength. , a reasonable compromise had to be made.

For this reason, it has been desired to produce high-strength thermistor porcelain.

The present invention is intended to solve these problems, and aims to improve workability during mass production and reliability as a product by increasing the strength of the porcelain itself.

Means for Solving the Problems In order to solve the above problems, the thermistor ceramic composition of the present invention contains Mn, Ni, and Co as main components as metal elements, and Pb element as a subcomponent in a range of 0.1 to 10. 0 atomic%
It is made by adding.

Furthermore, at least one of B and St elements is added in an amount of 0.1 to 10.0 atomic % based on the main component to the above ceramic composition.

Function The thermistor porcelain according to the present invention is a crystal having a Subinel structure, and it is known that the sintering process thereof generally takes a solid phase reaction. Electrical properties are due to crystal grains (semiconductors), whereas the strength of porcelain does not depend on the strength of the particles themselves, as the fracture surface is grain boundary fracture, just like alumina porcelain. , it can be seen that this is due to the strength of the grain boundaries, which is weaker than this. Furthermore, these two events are considered to be independent events.

According to the structure of the present invention, Mn, Ni and Co
By adding Pb or further adding B and Si to a composition whose main component is Pb, a liquid phase reaction occurs partially at the time of sintering, and the Subinel phase of the main component element is precipitated during cooling. , after that, Pb, B, and Si, which are the additive elements of the present invention, remain in the grain boundaries and form a glass phase,
This contributes to a significant increase in strength. As a result, high-strength thermistor porcelain can be obtained.

Example Examples of the present invention will be described below.

First, each material was weighed to have the composition shown in Tables 1 and 2 below, mixed in a wet bowl for 20 hours, dried, and then held at 800°C in the air for 2 hours. A calcining treatment was performed. At this time, as starting materials, commercially available MnO2, NiO, Co:+04, PbO, B20
:l, SiO2 was used. Next, the calcined material was wet-pulverized again in a ball mill, dried, and
%PVA (polyvinyl alcohol) 10 wt
% added and granulated using a Raikai machine to produce 1000kg/
A shape of 40 mIllφ x 2 mm was formed by applying pressure of c&. Next, this rod was heated in the atmosphere at 1100°C for 2 hours.
The electrodes were baked at 750° C. and baked on both sides.

The electrical characteristics were measured by measuring the resistance value (R25) at 25°C in the oil bath, converting it to a specific resistance value (ρ), and further measuring the resistance value (Rso) at 50°C. Then, the thermistor constant (B) was calculated from these two points. This calculation formula is B=3854×I n (R25/R50)
was used. Furthermore, the strength of the porcelain is determined by
Polished to n+m (#800), then cut into 25 mm x 5 mm using a dicing machine,
This sample was subjected to a three-point bending test to measure the bending strength. These measurement results are also shown in Tables 1 and 2 below. Here, the measured value is an average value of five samples.

Table 1 above. As is clear from the results shown in Table 2, the thermistor compositions of the examples of the present invention can significantly increase the porcelain strength without changing the electrical characteristics (specific resistance value ρ and thermistor constant B).

Here, in the present invention, when Pb, B, and Si are each less than 0.1 atomic % with respect to the main components, the effect of the present invention of increasing the porcelain strength is not observed; If it exceeds .0 atomic %, the specific resistance value ρ will be large and the thermistor constant B will be small, making it useless as a thermistor ceramic, and therefore it is outside the scope of the claims.

Effects of the Invention As described above, according to the thermistor porcelain composition of the present invention, the strength of the porcelain can be significantly increased without changing the electrical properties, as shown in Tables 1 and 2 above. . Therefore, by using this porcelain, not only the production efficiency can be improved, but also the reliability of the product can be dramatically improved. In addition, the thermistor porcelain of the present invention is a breakthrough, as the strength of the porcelain has been significantly improved, making it possible to apply it to even thinner and smaller products, as well as products with improved responsiveness. It is possible to provide material assembly.

Claims (2)

[Claims] (1) A thermistor ceramic composition characterized in that the main components are Mn, Ni, and Co as metal elements, and 0.1 to 10.0 atom % of Pb element is added as a subcomponent. (2) A thermistor porcelain composition characterized in that 0.1 to 10.0 atomic % of at least one of B and Si elements is added to the porcelain composition according to claim 1, based on the main component.