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1.What is an NTC Thermistor?

    An NTC thermistor, or Negative Temperature Coefficient thermistor, is a semiconductor component whose resistance decreases as temperature increases. It is made from materials like manganese, cobalt, nickel, and copper oxides, using traditional ceramic manufacturing processes.

    NTC thermistors can be classified based on their structure (discs, cylinders, rings), sensitivity to temperature changes (high sensitivity, low sensitivity), heating methods (direct heating, side heating), and temperature characteristics (positive or negative temperature coefficient).

2.Key Parameters of NTC Thermistors

①　Measurement Power: The power consumed when the resistance change due to heating is negligible. Typically, 10% of the dissipated power is considered measurement power.

②　 Material Constant (B-Value): Indicates thermal sensitivity. Higher values mean greater sensitivity and resistivity.

③　 Resistance Temperature Coefficient: The relative change in resistance with a 1°C change in temperature under zero power conditions.

④　 Thermal Time Constant: The time it takes for the thermistor to reach 63.2% of the total temperature change when the ambient temperature suddenly changes.

⑤　Dissipation Factor: The power consumed for each 1°C increase in temperature.

3.Composition of NTC Thermistors

    NTC thermistors are made from transition metal oxides like manganese, cobalt, nickel, iron, and copper. These materials are molded and sintered into semiconductor ceramics. At low temperatures, these oxides have higher resistance due to fewer charge carriers. As temperature increases, resistance decreases. Additional elements like yttrium oxide, vanadium pentoxide, and lanthanum oxide may be added to adjust resistivity and improve stability.

4.Applications of NTC Thermistors

    NTC thermistors are widely used for temperature measurement, control, and compensation. In AC or DC circuits, they can suppress startup surge currents. When the power is switched on, the thermistor is cold and has high resistance, limiting surge current. As it heats up, resistance drops sharply, minimizing power consumption and maintaining efficiency. Series like MF72, MF73, and MF74 are commonly used for surge suppression.