JPH053103A - Thermistor porcelain - Google Patents

Abstract

(57) [Abstract] [Purpose] In a thermistor porcelain mainly composed of Cu-added 3d transition metal oxide used for temperature compensation of circuits and temperature sensors, it is left at high temperature such as 150 ℃ for a long time. To solve the fluctuations in electrical characteristics such as
An object is to provide a highly stable thermistor porcelain. [Structure] In an oxide containing 3d transition metal oxide as a main component to which Cu is added, V ₂ O ₅ is 30 to 95 mol%, MoO ₃ is 55 to 80 mol%, or WO ₃ is 30 to 30 mol%. 8
The glass powder containing 0 mol% is 0.1 to 0.1% with respect to the oxide.
Addition of 10.0% by weight prevents grain boundary diffusion of oxygen and adsorbed water in the crystal, and thus a stable thermistor porcelain with little change in characteristics even when left at high temperature for a long time can be obtained. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermistor porcelain used for temperature compensation of a temperature sensor, a power thermistor or a circuit.

[0002]

2. Description of the Related Art Conventionally, in the thermistor porcelain composed of this kind of 3d transition metal oxide, the specific resistance and the thermistor constant (B constant) can be controlled in a wide range by changing the respective element ratios. In particular, by adding Cu, a resistance element having a specific resistance of 10 to 1000 Ω · cm can be obtained, and it is used for a power thermistor, a chip thermistor, a glass-enclosed thermistor and the like.

[0003]

However, the thermistor porcelain to which Cu is added has a large change in electric resistance with time at high temperature as compared with the thermistor porcelain without adding Cu. For example, elements other than oxygen include Mn of 75 atomic% and Ni of 20%. Atomic%, C
When a disk type thermistor with a diameter of 5 mm and a thickness of 1 mm made of u5 atom% porcelain is left at 85 ° C for 1000 hours, the specific resistance at 25 ° C is 10% of the initial value.
However, there is a problem in that it is difficult to achieve high accuracy because it changes by more than%.

The cause of such a change with time in characteristics is not clear because the conduction form is complicated, but it is considered to be due to a change in the concentration of oxygen defects in the crystal and adsorption of water.

The present invention solves the above-mentioned conventional problems, and provides a thermistor porcelain that can obtain a highly stable thermistor element with a small change over time.

[0006]

In order to achieve the above object, the thermistor porcelain of the present invention contains 3d containing Cu.
V ₂ O ₅ is added to an oxide containing a transition metal as a main component in an amount of 30 to 95
Mol% or 55-80 mol% MoO ₃ , or W
O _3, is obtained by adding 0.1 to 10.0% by weight based on the oxide glass containing 30 to 80 mol%.

[0007]

With this structure, by adding the glass of the above-mentioned components, the glass component is precipitated at the grain boundaries after sintering, and oxygen and adsorbed oxygen in the crystal, which is considered to be a factor of characteristic changes such as resistivity and B constant. The grain boundary diffusion of water can be prevented.

Further, the glass of the above components has a specific resistance of 10
³ to 10 ¹⁰ Ω · cm, which has a smaller specific resistance than ordinary glass,
The addition of these does not affect the electrical characteristics of the main component of the thermistor. As described above, by adding glass having a low specific resistance and depositing it on the grain boundaries, it is possible to obtain a thermistor porcelain with a small change over time and high stability.

[0009]

(Embodiment 1) A first embodiment of the present invention will be described below.

A predetermined amount of 3d transition metal oxide such as Cu is blended so that the composition ratio other than oxygen is the composition shown in (Table 1), and the mixture is mixed in a ball mill for 16 hours and dried, and then 800 It was calcined at ℃ for 2 hours. After calcination, glass powder containing V ₂ O ₅ as a main component shown in (Table 2) was added, crushed in a ball mill for 18 hours, dried, and then 10% by weight of PVA (polyvinyl alcohol). 8% by weight of the aqueous solution of was added to the pulverized powder to granulate.
Further, it was pressure-molded into a disk shape having a diameter of 5 mm and a thickness of 1 mm, followed by firing at 1100 ° C. for 2 hours to obtain a sintered body, and silver electrodes were baked on both surfaces thereof to prepare a disk-shaped sample.

The glass powder added here is V ₂ O ₅ , P
₂ O ₅ , BaO, and Na ₂ O were mixed in predetermined amounts as shown in (Table 2), mixed and pulverized by, for example, a ball mill, then melted in a platinum crucible at 1100 ° C. and rapidly cooled to vitrify. The specific resistance of the glass at 25 ° C at this time is 10 ⁴
It was about 10 ⁷ Ω · cm. After roughly crushing this glass,
Finely pulverized with a ball mill to obtain glass powder.

[0012]

[Table 1]

[0013]

[Table 2]

In Table 3, the number indicating the composition of the metal oxide obtained through the above steps, the number indicating the composition of the glass, the added amount of glass and the specific resistance of the disk type sample, the B constant and 1
The rate of change of the specific resistance and the B constant with respect to the initial values after being left at 50 ° C. for 1000 hours is shown. For comparison, the characteristics of the sample without glass are also marked with *.

[0015]

[Table 3]

As shown in (Table 3), the resistance change rate of all the samples to which glass was not added after standing at 150 ° C. for 1000 hours was 10% or more, whereas the sample to which glass was added was improved to 10% or less. Has been done. Further, the rate of change of B constant is extremely smaller in the sample to which glass is added than in the sample to which glass is not added.

As described above, according to the first embodiment,
0.1 to 1 of glass powder containing 30 to 95% of V ₂ O ₅
By adding 0.0% by weight, it is possible to provide a stable thermistor porcelain with a small change in characteristics even after being left at high temperature for a long time.

(Second Embodiment) A second embodiment of the present invention will be described below.

A disk-shaped sample having a glass component different from that of Example 1 was prepared in the same manner as in Example 1. here,
The composition studied was the same as in Example 1 except that the oxide of the 3d transition metal element shown in (Table 1) was the main component, and glass containing MoO ₃ as the main component was added.

The glass added here is MoO ₃ , P ₂ O.
₅ , BaO was blended in a predetermined amount as shown in (Table 4), and was mixed and crushed in a ball mill, for example, as in Example 1, and then
It was melted at 1050 ° C. in a platinum crucible and rapidly cooled to be vitrified. At this time, the specific resistance of the glass at 25 ° C. is 10
^{It was 9} Ω · cm to ^{10 10} Ω · cm. This glass was roughly crushed and then finely crushed with a ball mill to obtain glass powder.

[0021]

[Table 4]

In Table 5, the numbers showing the compositions of the metal oxide and glass, the amount of glass added, the specific resistance of the disk type sample,
The B constant and the rate of change of the specific resistance after standing for 1000 hours at 150 ° C. and the B constant with respect to the initial value are shown. For comparison, the characteristics of the glass-free sample shown in Example 1 are also marked with *.

[0023]

[Table 5]

As shown in (Table 5), the resistivity of MoO ₃ glass is higher than that of V ₂ O ₅ glass, so that the resistivity of the sample is increased by about 10% as compared with the sample without glass addition. However, the sample without glass was added at 150 ° C, 100
The rate of change in resistance after standing for 0 hour is all 10% or more, whereas the sample to which MoO ₃ glass is added is improved to 10% or less as in Example 1. The B constant is also improved.

As described above, according to this second embodiment,
The glass powder containing 30 to 80% of MoO ₃ is 0.1 to
By adding 10.0% by weight, it is possible to provide a stable thermistor porcelain with a small change in characteristics even after being left at high temperature for a long time.

(Third Embodiment) A third embodiment of the present invention will be described below.

A disk-shaped sample having a glass component different from that of Example 1 was prepared in the same manner as in Example 1. here,
The composition studied was based on the oxides of the 3d transition metal elements shown in (Table 1) as in Examples 1 and 2, and WO ₃
The glass containing glass as a main component is added.

The glass added here is WO ₃ , P
₂ O ₅ , BaO and Na ₂ O were mixed in predetermined amounts as shown in (Table 6), mixed and pulverized by, for example, a ball mill, then melted in a platinum crucible at 1250 ° C. and rapidly cooled to vitrify. At this time, the specific resistance of the glass at 25 ° C. is 10 ⁵
Ω · cm to 10 ⁸ Ω · cm. This glass was roughly crushed and then finely crushed with a ball mill to obtain glass powder.

[0029]

[Table 6]

In Table 7, the numbers showing the compositions of the metal oxide and glass, the amount of glass added, the specific resistance of the disk type sample,
The B constant and the rate of change of the specific resistance after standing for 1000 hours at 150 ° C. and the B constant with respect to the initial value are shown. For comparison, the characteristics of the glass-free sample shown in Examples 1 and 2 are also marked with *.

[0031]

[Table 7]

As shown in (Table 7), the resistance change rate of the sample to which no glass was added after leaving it at 150 ° C. for 1000 hours was 10% or more, whereas in Examples 1 and 2, WO ₃ glass was used. The sample added with is improved to 10% or less. The B constant is also improved.

As described above, according to the third embodiment,
0.1 to 1 of glass powder containing 30 to 80% of WO ₃
By adding 0.0% by weight, it is possible to provide a stable thermistor porcelain with a small change in characteristics even after being left at high temperature for a long time.

As described above, in the glass of this embodiment, P ₂ O ₅ was used as the glass forming substance, and BaO and Na _{2 were} used as the glass adjusting substances.
O was used, but as other glass-forming substances, B ₂ O ₃ ,
SiO ₂ , glass-adjusting substances CaO, Al ₂ O ₃ , G
eO ₂ , Bi ₂ O ₃ , TeO ₂ , Li ₂ O, K ₂ O, Ag
The same effect can be obtained by using ₂ O, PbO, SrO, CdO, ZnO, BeO or the like. Further, when V ₂ O ₅ which is the main component of glass exceeds 95 mol%, MoO ₃ exceeds 80 mol%, and WO ₃ exceeds 80 mol%, vitrification does not occur,
On the other hand, V ₂ O ₅ is 30 mol%, MoO ₃ is 55 mol%, WO ₃
Is less than 30 mol%, the specific resistance of the glass rapidly increases, and when it is added to the thermistor main component, it becomes difficult to control the electrical characteristics, and the variation thereof also rapidly increases. Furthermore, with respect to the amount of glass added, if it is less than 0.1% by weight, there is no effect of reducing the change over time and obtaining a highly stable thermistor porcelain.
If it exceeds 0.0% by weight, the resistance of the oxide, which is the main component, increases rapidly, and the variation in electrical characteristics also increases rapidly, which is not practical and is outside the scope of the present invention.

In the above embodiments, the case where one type of V ₂ O ₅ , MoO ₃ and WO ₃ is used as the main components of the glass has been described.
The same effect can be obtained by using glass in which a small amount of another one or two kinds is added.

[0036]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, V ₂ O ₅ is added to an oxide containing Cu-containing 3d transition metal as a main component.
0 to 95 mol%, or 55 to 80 mol% MoO ₃ ,
Or glass powder containing WO ₃ 30 to 80 mol%, by the addition of 0.1 to 10.0% by weight based on the oxides, small aging, as it can realize a highly stable thermistor ceramic, industrial Is of great value.

Claims (3)

[Claims] 1. A metal element comprising Cr, Mn, Fe, Co,
0.1% of glass containing 30 to 95 mol% of V ₂ O ₅ is added to an oxide containing at least one component of Ni and Cu.
A thermistor porcelain, which is characterized by adding up to 10.0% by weight. 2. Metal elements such as Cr, Mn, Fe, Co,
A glass containing 55 to 80 mol% of MoO ₃ is added to an oxide containing at least one component of Ni and Cu.
A thermistor porcelain, characterized in that 1 to 10.0% by weight is added. 3. Metal elements such as Cr, Mn, Fe, Co,
0.1% of glass containing 30 to 80 mol% of WO ₃ is added to an oxide containing at least one component of Ni and Cu.
A thermistor porcelain, which is characterized by adding up to 10.0% by weight.