JP2715567B2 - Thermistor porcelain composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermistor ceramic composition having a negative temperature coefficient used for temperature measurement, temperature compensation, and the like.

2. Description of the Related Art In recent years, oxide-based thermistor porcelains containing Mn and Ni as main components, so-called spinel-based thermistor porcelains, have been made into chips along with the trend toward lighter, thinner and smaller, and the items required for ceramic elements are not only highly accurate but also It is becoming a necessary condition to have high strength.

Problems to be Solved by the Invention When using the above-described spinel-based thermistor porcelain containing Mn and Ni as main components and developing it for various uses, the use form and method vary depending on the product. The load applied to the ceramic element is considerable, such as the spring pressure of the type that retains the pressure, the fitting pressure of the type that fits the cap-shaped electrodes to both ends of the cylindrical ceramic element, and the heat shock during soldering. was there. For this reason, the high strength of ceramic porcelain not only affects the work efficiency in the process, but also greatly affects the reliability as a product, but the conventional spinel-based thermistor porcelain does not always have high strength. Had to be moderately compromised.

For these reasons, it has been desired to produce a high-strength thermistor porcelain.

The present invention solves such a problem, and an object of the present invention is to improve workability during mass production and reliability as a product by increasing the strength of porcelain itself.

Means for Solving the Problems In order to solve the above problems, the thermistor porcelain composition of the present invention has Mn and Ni as main components as metal elements and a Pb element as an auxiliary component added at 0.1 to 10.0 atomic%. Things. Further, the ceramic composition is obtained by adding at least one of B and Si elements to the main component in an amount of 0.1 to 10.0 atomic%.

Operation The thermistor porcelain according to the present invention is a crystal having a spinel structure, and it is known that the sintering process generally takes a solid-phase reaction. The electrical characteristics are attributed to crystal grains (semiconductors). On the other hand, the strength of porcelain does not depend on the strength of the grains themselves, because the fracture surface is grain boundary fracture like alumina porcelain. It can be understood that this is due to the weaker grain boundary strength. Also,
It is considered that these two events are independent.

According to the structure of the present invention, Pb is added to a composition containing Mn and Ni as main components, or B, Si
Is further added, a liquid phase reaction occurs partially at the time of sintering, and a spinel phase as a main component element is precipitated during cooling, and thereafter, the added elements of the present invention, Pb, B, Si, are added to the grain boundaries. This forms a glass phase and contributes to a significant increase in strength. Thus, a high-strength thermistor porcelain can be obtained.

Examples Hereinafter, examples of the present invention will be described.

First, each material was weighed so as to have the composition shown in Tables 1 and 2 below, mixed with a wet ball for 20 hours, dried, and then kept at 800 ° C. for 2 hours in the atmosphere. A calcination treatment was performed. At this time, commercially available starting materials
MnO ₂ , NiO, PbO, B ₂ O ₃ , and SiO ₂ were used. Next, the calcined product was wet-pulverized again by a ball mill, dried, added with 10% by weight of 5% PVA (polyvinyl alcohol), and granulated with a raikai machine, and added at 1000 kg / cm ² . By pressure
It was formed into a size of 40 mmφ × 2 mm. Next, the molded body was held in the atmosphere at 1200 ° C. for 2 hours and fired, and a baked silver electrode was applied to both surfaces at 750 ° C. for the electrode.

Then, for the measurement of the electrical characteristics, the resistance value (R ₂₅ ) is measured at 25 ° C. in an oil bath, and converted into a specific resistance value (ρ).
Further, the resistance value (R ₅₀ ) at 50 ° C. was further measured, and the thermistor constant (B) was calculated from these two points. This formula is:
B = 3854 × In (R ₂₅ / R ₅₀ ) was used. Furthermore, the porcelain strength was first polished to a thickness of 0.5 mm (# 800), and then
The sample was cut into 25 mm × 5 mm by a dicing machine, and the sample was measured by a three-point bending test method to measure the bending strength. The measurement results are shown in Tables 1 and 2 below. Here, the measured value is an average value of five samples.

As is clear from the results shown in Tables 1 and 2,
According to the thermistor composition of the embodiment of the present invention, the strength of the porcelain can be significantly increased without changing the electrical characteristics (specific resistance value ρ and thermistor constant B).

Here, in the present invention, when each of Pb, B, and Si is less than 0.1 atomic% with respect to the main component, the effect of the present invention of increasing the porcelain strength is not observed.
When the content exceeds 0.0 atomic%, the specific resistance value ρ is large and the thermistor constant B is small, so that the thermistor does not need to be used as a thermistor ceramic.

As described above, according to the thermistor porcelain composition of the present invention, the porcelain strength can be significantly increased without changing the electrical characteristics as shown in Tables 1 and 2. . Therefore, by using this porcelain, not only can the production efficiency be improved, but also the reliability as a product can be dramatically improved. The thermistor porcelain of the present invention is an epoch-making material, as the strength of porcelain has been remarkably improved, making it possible to apply it to thinner and smaller products and to develop products with improved responsiveness. It can provide a composition.

Claims (2)

(57) [Claims] (1) Mn and Ni as main components as metal elements;
A thermistor porcelain composition to which 0.1 to 10.0 atomic% of Pb element is added as an auxiliary component. 2. The porcelain composition according to claim 1, further comprising at least one of B and Si elements in an amount of 0.1 to 10.0 atomic% based on the main component.
A thermistor porcelain composition, wherein the composition is added.