JPH02272701A - Ceramic fixed resistor - Google Patents

Abstract

PURPOSE:To enhance durability against a high-tension pulse and big power surge by mixing a ceramic material consisting of MgO and SiO2, a conductive material consisting of SnO2, Sb2O3 and alkaline-earth metal oxide at specific ratios. CONSTITUTION:A ceramic fixed resistor consists of a ceramic insulating material consisting of MgO and SiO2, a conductive material consisting of SnO2 and Sb2O3 and an additive consisting of an alkaline-earth metal oxide of at least one kind of BeO, CaO, SrO and BaO. And, a compounding ratio is 0.1<=x<=85[wt.%], 30<=y<=75[mol%], 90<=z<=99.9[mol%] in the formula I, and the additive is 0.1 to 20mol%. Thereby, as compared with a carbon distributed ceramic resistor, durability against high pulse and a high power surge is improved and a resistance value range is widened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a SnO□-based ceramic fixed resistor used, for example, in high-voltage pulse circuits of televisions, noise prevention in automobiles, and the like.

(Prior art) Conventional ceramic fixed resistors are made by mixing carbon powder as a conductive material with aluminum silicate material (clay, SiO□, AJ2 (h, etc.), adding a binder, and molding. A carbon-dispersed ceramic resistor is known in which the molded body is then fired in a non-oxidizing atmosphere furnace and electrodes made of aluminum or the like are provided at both ends.

(Problem to be solved by the invention) However, in carbon-dispersed ceramic resistors, carbon has poor wettability with water and has a lower bulk density than ceramic raw materials, making it difficult to mix uniformly and causing resistance values to vary. .

In addition, carbon dispersed ceramic resistors have poor density, so
Since a discharge occurs between the carbon particles when absorbing a surge, the discharge resistance is low and the high-voltage pulse and high-power surge characteristics are poor.

Furthermore, since carbon is easily oxidized, firing is required in a non-oxidizing atmosphere, which increases firing cost.

Furthermore, in carbon-dispersed ceramic resistors, if the blending ratio of carbon and ceramic is less than 5v1%, the resistance value will vary greatly, and if it is more than 15vt%, dense sintering will be difficult, so the practical range is 5 to 1%. There is a problem that the resistivity is limited to 15w1% and the specific resistance is in a narrow range of 1 to 103Ω.

In view of the above-mentioned problems, an object of the present invention is to provide a ceramic resistor that is more durable against high-voltage pulses and large power surges than carbon-dispersed ceramic resistors, has a wider resistance value range, and uses a non-oxidizing atmosphere furnace during firing. The purpose of the present invention is to provide a ceramic fixed resistor that can be manufactured without any problems and can have a wide resistance value range of about 10-'' to 10<6>Ω.

[Structure of the Invention] (Means for Solving the Problems) The ceramic fixed resistor of the present invention includes a ceramic insulating material made of JO and SiO□, 5n02, sb, o,
and an additive made of at least one kind of alkaline earth metal oxide such as BeO, CaO, and 5rOBaO, and the compounding ratio is x fr (MgO}+ (10G-r) in the following formula (1). )(Si(h
) 10 additives} + (100-I) fz (SnOz }
+(10G-2) (Sb203)1......(
1) 0.1 ≦X≦85 (vj%) 30≦y≦75
C+++oj%] 9G≦Z≦99.9 (mo1%), and the additive is 11.1 to 20 mo1%.

(Function) The ceramic fixed resistor of the present invention contains a ceramic insulating material composed of MgO and SiO2 in an amount of 0.1v1% to 85vt%.
, 15 wj% of conductive material consisting of SnO2 and 5b2o
By blending in a wide range of 1% to 99.9w1%, it is possible to obtain a wide range of solid resistors with resistance values of about 10 -1 Ωan to 10 6 Ωcm using the same material.

Furthermore, by adding at least one of BeO, CaO, SrO, and Ba0 as an additive, the firing temperature can be lowered, making it possible to fire resistors with a wide range of compounding ratios within a practical temperature range.

(Example) Example 1 70vtXf(65mojXMg(OH)z + 35
moj%SiO2+7moL%BxCOs +3noj
%CxC0t)1+30v1%f(97,5noj
The raw materials were prepared to have a blending ratio of %SnO□+2.5mo(XSb203)1 and mixed in a ball mill for 20 hours. This mixture is held at 1100° C. for 2 hours to calcinate. This calcined powder is mixed again in a ball mill for 20 hours.

A polyvinyl alcohol solution is added to this mixture and granulated. This granulated powder is compression molded. This molded body is 134
It is kept at a temperature of 0° C. for 2 hours and fired. The obtained sintered body was 70W(%t(65moj%MgO+35nol%S
in, +7+oj%BaO+ 3mo 1%C
a0)l+30v1511(97,5mo(% SnO
It has a blending ratio of □+2.5+++oj%sb2 03 )1. Electrodes are formed on both ends of this sintered body to form a resistor. The resistance value of the obtained resistor was 1.2Ω, and the TCR was -1440 ppm/°C.

Example 2? Ovj%((35moj%Mg (01() 2 +
65noA'%Sin□+3moj%BaC0t+
7noj%5rCOq)1+30w1%f(95m
oj%SnO□+5mo7%5b203) Prepare at a blending ratio of 1 and mix in a ball mill for 2 hours.

A polyvinyl alcohol solution is added to this mixture and granulated. This granulated powder is compression molded. This molded body is 138
Baking is performed by holding at a temperature of 0° C. for 2 hours. The obtained sintered body was 70w1% [(35moj%MgO+65moj%Si
O+ 3moj%BaO+7noj%5rO)l+30
vt%I(95moj%SnO2+5moj%Sb2
03) It has a blending ratio of 1. Electrodes are formed on both ends of this sintered body,
Use it as a resistor. The resistance value of the obtained resistor was 430Ω,
TCR was -1420 ppm/°C.

Example 3 xvt%1 (97.5mo1% 51102 +2.
5moj%sb203)1+(100-1)W1%
[(10[1mo1%214g0・SiO□+5moj
%BaC0,+3moj%SrCO3+2n+o1%C
Resistors were made in the same manner as in Example 1 by changing the X in the range of 15≦X≦99.9 using raw materials with a compounding ratio of aCO5)1, and the results of measuring the specific resistance of each were shown in the first table. As shown in the figure.

From Figure 1, the blending amount of the conductive material is 15w1% to 99,9
wt%, insulating material 0. IW1%~85w1% (D
By changing the specific resistance within the range from 106Ωcm to 1
This shows that it can be varied over a wide range on the 0Ω side.

Example 4 70wt% ((YlllIO1%MgO+ (100-
r) mo 1%5i02+3ma1%B@CQ3)l
+aθv1%(('15mo(%SnO,+5mo(%
5b203)1 The raw materials with a blending ratio of
Resistors were made by firing at the maximum temperature for 2 hours, and the resistivity of each resistor was measured. The results are shown in FIG.

From Figure 2, MgO is 30moj% ~ 75+oj94,
By changing the blending amount of SiL in the range of 25no1% to 79mot%, the specific resistance can be increased from 102ΩCm to 106
Ω can be varied to a range of countries, and MgO60m
It is shown that the specific resistance becomes the minimum at oj51 and SiO□40a+oJ%.

Example 5 75w(%(5Qn+oj%MgO+50moj%Si
n□+5moj%BICO3+8moj%5rCO,+
2+++oj%C5C(h l+(25wt%) (9
7.5moj%SnO□+2.5@oj%5b2Q,)
Using raw materials with a mixing ratio of
This resistor is used for the Rx of the electric circuit shown in Figure 3, and the shape and size are 5.5 mm x 25 mm and the resistance is 10 Ω and 30 K.
V (A) and shape and dimensions 4. OMφ×1511II1
A high voltage pulse is applied with a resistance value of 10KQG: 15KV (B), and the number of high voltage pulses and the rate of change in resistance value (△R/R
) is shown in Figure 4.

From Figure 4, (^) (B) is a high voltage pulse of 20 in both cases.
Even after 000 cycles, the resistance value change rate was 1% or less, indicating that the resistance value was highly stable against high voltage pulses.

〔Effect of the invention〕

According to the present invention, by widening the blending ratio of the ceramic insulating material made of MgO and SiO□ and the conductive material made of SnO□ and 5b203, the resistance value range can be increased from 10-1Ωcm to 106Ωcm using the same raw materials. You can get a wide range of degrees.

BeO, CaO1SrO, which can also be added as additives,
At least one type of B2O lowers the firing temperature, allowing for a wide range of insulating and conductive material formulations.

Furthermore, since it contains MgO and SiO□ as ceramic insulating materials and SnO2 and 5b203 as conductive materials, it can withstand high voltage and high-voltage pulses and can reduce the rate of change in resistance value.

[Brief explanation of drawings]

Fig. 1 is a chart showing the relationship between specific resistance when the mixing ratio of insulating material and conductive material of the ceramic fixed resistor of the present invention is changed, and Fig. 2 is a chart showing the relationship between specific resistance when the mixing ratio of MgO and Sin is changed. FIG. 3 is a circuit diagram for a high-voltage pulse test using the resistor of the example, and FIG. 4 is a characteristic diagram of resistance value change rate with respect to high-voltage pulses. X @ Lili storage 15- 'ICMO1 % 7 Significer presentation

Claims (1)

[Claims] (1) A ceramic insulating material made of MgO and SiO_2, and a conductive material made of SnO_2 and Sb_2O_3,
It consists of an additive consisting of at least one kind of alkaline earth metal oxide of BeO, CaO, SrO, and B_2O, and the compounding ratio is x{y(MgO)+(100-y)(SiO_2) in the following formula (1). )+additive}+(100-x){Z(SnO_2)+(100
-Z)(Sb_2O_3)}...(1) 0.1≦x≦85 [wt%] 30≦y≦75 [mol%] 90≦Z≦99.9 [mol%], A ceramic fixed resistor characterized in that the additive content is 0.1 to 20 mol%.