Manufacturing method of negative temperature coefficient ceramic thermistor

Abstract

The utility invention relates to a manufacturing method of a negative temperature coefficient ceramic thermistor, which comprises the following steps of: doping a trace of ZnO into Mn3O4, Co3O4 and Fe2O3, uniformly mixing, forming after ball-milling, pre-burning, spraying and granulating, putting into a hot-pressing furnace, pressure-boosting while the temperature rises, sintering at a constant temperature of 1050-1150 DEG C and a constant pressure of 10 MPa and pressure-reducing while the temperature drops; and preparing a surface electrode on the surface of a ceramic body in a vacuum evaporation coating manner. The manufacturing method has the beneficial effects that through a hot-pressing sintering process that the pressure is boosted while the temperature rises, the constant pressure is kept while the constant temperature is kept, and the pressure is reduced while the temperature drops, the sintering constant temperature is 1050-1200 DEG C and is lower than 1400 DEG C, so that the compactness and the heat conduction coefficients of materials are greatly improved; the ceramic surface electrode is prepared by adopting an evaporation coating process, and the surface metal electrode is better combined with the ceramic body, so that the heat conduction coefficients are improved, and further, the dissipation coefficients and the volt-ampere characteristic values of the negative temperature coefficient ceramic thermistor are improved; and the tolerable maximum direct current voltage is improved, so that the self-heating phenomena caused by poor heat radiation under the large working voltage impact is avoided, and the accuracy of temperature measurement and control of the thermistor is improved.

Description

technical field [0001] The invention relates to a method for manufacturing a negative temperature coefficient (NTC) ceramic thermistor. Background technique [0002] Among the semiconductor negative temperature coefficient thermistors, the commonly used negative temperature coefficient (NTC) thermistor is composed of transition metal oxides such as manganese, cobalt, iron, nickel, etc. This kind of negative temperature coefficient thermistor (NTC) has resistance The property that the value decreases exponentially with increasing temperature. Because the thermistor has the characteristics of small chip size, flexible change in size and shape, and large absolute resistance, it has the characteristics of sensitive response, high precision, and low cost when measuring temperature, and can use very long connecting wires and allow large high contact resistance. Due to its unique characteristics, it is widely used in temperature measurement control, temperature compensation, indi...

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Problems solved by technology

[0005] After the traditional NTC thermistor material is formed, it is sintered under normal pressure and high temperature. The sintering temperature is as high as 1400°C, which consumes a lot of energy. Due to the lack of uniformity of firing and infiltration heat transfer, the ceramic body is easy to crack and the density is not high. The thermal chip Low thermal conductivity; the surface electrode is prepared by screen printing process and sintered at high temperature, the adhesion between the surface metal electrode and the porcelain body is not good, and the contact resistance is large, which also affects the heat conduction of the material, resulting in a low dissipation coefficient. When passing current, The maximum DC voltage that can withstand is low, and the heat dissipation ability is not good, which will cause self-heating to affect the measurement accuracy

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