What is the thermistor composed of? Notes

Thermistor is a type of resistor whose resistance is strongly dependent on temperature, including two basic types, namely positive temperature coefficient thermistor and negative temperature coefficient thermistor. In order to help you have a deeper understanding, this paper will summarize the relevant knowledge of thermistors. If you are interested in the content to be covered in this article, please read on.

1、 Composition material of thermistor

What is the resistance related to temperature in electronic components? The resistance related to temperature is thermistor, which is very sensitive to temperature. Within a certain temperature range, the resistance value of thermistor will change with the change of temperature. Thermistors belong to semiconductor resistors because they are made of semiconductor materials. In addition to semiconductors, there are also thermistors made of metal materials and alloy materials.

1. Thermistor composed of semiconductor materials

Semiconductor materials include single crystal semiconductor, polycrystalline semiconductor, glass semiconductor, metal oxide, etc. Because of their high resistance temperature coefficient, high resistivity and high sensitivity of thermistors made of semiconductor materials, they can quickly identify different temperatures when used on sensors, and are widely used in temperature measurement, temperature control, temperature compensation, switching circuit, overload protection, etc., such as thermistor thermometers, thermistor switches, thermistor thermometers, thermistor switches, etc.

2. Thermistors made of metal materials

Thermistors made of metal materials are widely used in temperature measurement, current limiter and automatic thermostatic heating elements, such as platinum resistance thermometer, nickel resistance thermometer, copper resistance thermometer, etc. Among them, the platinum side temperature sensor shows the characteristics of high accuracy and high stability in various media (including corrosive media). However, due to the small output and high price of platinum, their wide application is limited. Copper temperature sensors are cheaper, but long-term use in corrosive media can lead to changes in static characteristics and resistance values. Nickel temperature sensor has high sensitivity and stability, and it is considered that nickel is an ideal material.

3. Thermistor composed of alloy material

The thermistor composed of alloy material is called thermistor alloy. The resistivity is high, and the resistance value is sensitive to the change of temperature. It is a good material for manufacturing temperature sensitive sensors.

Thermistors made of different materials have different performances and advantages, and have different requirements for the working environment. When selecting thermistors, it is necessary to select appropriate thermistors according to the actual needs.

2、 Precautions for use of thermistor

1. The thermistor and its temperature sensor should be avoided from being exposed to the environment of rapid temperature change as far as possible to avoid aging.

2. The current flowing through the thermistor and its temperature sensor will cause the component to heat itself and generate temperature difference, so please consider this factor before selection. (The heating value of the element itself is the dissipation coefficient δ (mW/℃), the temperature difference is 0.1 ℃, δ 1/100, the temperature difference is 0.01 ℃.)

3. Due to the poor insulation of the electric furnace, electrostatic induction and wrong wiring, the current flowing through the thermistor and temperature sensor will be too large to damage it. Attention must be paid to the connection method, and no excessive current flowing through the thermistor or temperature sensor.

4. After 5S (second), it is better to start the measurement after more than 7S (second).

5. When the use environment requires rapid measurement and high accuracy, the specification and model with small volume and small time constant should be selected.

6. If there are water droplets, dust or ionic compounds generated by condensation on the surface of the insulator and between the leads, the resistance value will drop or become unstable, resulting in measurement error. Therefore, moisture-proof and insulation treatment should be carried out to keep it dry.