With the continuous innovation of electronic products, more and more electronic products have added the function of temperature sensing or temperature detection, and the core component of temperature detection is the high-accuracy NTC thermistor chip. Due to it has the characteristic that the resistance value varies with temperature, therefore, the temperature at the position of the thermistor chip can be determined according to the resistance value of the NTC thermistor chip, to achieve the purpose of temperature induction or temperature detection.
General NTC thermistor chips include thermal ceramic wafers and metal electrodes printed on two surfaces of thermal ceramic wafers. The method of production is generally: thermal ceramic powder preparation - sintered ceramic ingots - slicing - metal electrodes printing - sintering - calculation of dimensions - dicing. The temperature characteristic curve of general NTC thermistor chip is basically determined by the formulation of the thermal ceramic material used, which is difficult to meet different usage needs and special production requirements, and can not bring new functions and applications. EXSENSE Electronics introduces a composite NTC thermistor chip, which has the advantages of adjustable temperature curve, simple structure and low cost.
Composite NTC thermistor chip includes thermal ceramic wafers, metal electrodes and glass-glaze resistors. Its thermal ceramic wafers has a front and back; The metal electrode comprises the first end electrode and the second end electrode, wherein the first end electrode and the second end electrode are set at the front or back of the thermal ceramic wafers at both ends; The glass-glaze resistors is arranged on the front or back of the thermal ceramic wafers.
The preparation method for composite NTC thermistor chip includes the following steps:
First, raw materials mixed according to the general NTC thermal ceramic material formula, ball milling, drying, sieving, pre-sintering, grinding, drying, sieving in turn, then get a prepared NTC thermal ceramic powder;
Second, the prepared NTC thermal ceramic powder is put into the mold, then put the mold in an isostatic pressing machine to press, after release pressure from the mold to remove the molded ceramic ingots, then the ceramic ingots are sintered at high temperature, and slice it, to obtain ceramic thermal substrate;
Third, the surfaces of the ceramic thermal substrate are printed metal electrode layer;
Fourth, the slurry of glass-glaze resistors is printed on the surface of the ceramic thermal substrate, sintering at high temperature after drying, the glass-glaze resistor printed on ceramic thermal substrate is obtained;
Fifth, dice the ceramic thermal substrate, to obtain single composite NTC thermistor chip.
Among them, the pressure of the isostatic pressing machine in step two is 200~400MPa, and the pressured time is 10~50 seconds. The temperature of the high temperature sintering in step four is 800~900℃, the sintering time is 10~30 minutes, this step is the metal electrode layer and the slurry of glass-glaze resistors sintered at the same time.
By adding the glass-glaze resistors to form new composite NTC thermistor chip, the material of the glass-glaze resistors is different from the thermal ceramic wafer’s. Its temperature coefficient is small, which can be regarded as a fixed resistance and can make the composite NTC thermistor chip obtain a different temperature curve from the general thermal chip. The temperature curve is related not only to the formulation of the thermal ceramic material used, but also to the added resistance value of glass-glaze resistors, the setting position of the glass-glaze resistor and the placement of the metal electrodes. Therefore, the temperature curve of the composite NTC thermistor chip is adjustable to meet the different use needs and special production requirements that general NTC thermistor chips cannot meet.
The high-accuracy NTC thermistor chip (accuracy can up to ±0.5%, ±1%, ±2%, ±3% ) produced by EXSENSE Electronics Technology Co., Ltd. has the characteristics of high sensitivity, great reliability and rapid response, which is widely used in various occasions of temperature monitoring, temperature control and temperature compensation.