Surface mount thermistors are mainly used to measure the surface temperature of objects and are frequently used in current electrical appliances. When the ambient temperature changes, their resistance value will change, thereby changing the working state of the circuit. They are widely used in temperature sensors and control systems.

Surface mount thermistors can be divided into two types based on the relationship between their resistance value and temperature change: positive temperature coefficient (PTC) and negative temperature coefficient (NTC). The positive temperature coefficient refers to the decrease in resistance value as the ambient temperature increases.

The nominal resistance value of a patch thermistor refers to the resistance value in an environment at 25 ℃. Therefore, when measuring resistance values, attention should be paid to the influence of ambient temperature. When the ambient temperature is 25 ℃, the resistance value of the thermistor measured by the multimeter is its nominal resistance value. If the ambient temperature is not 25 ℃. It is normal for the measured resistance value to not match the nominal resistance value of the thermistor.

If it is necessary to detect and determine whether the surface mount thermistor has a positive or negative temperature coefficient, surrounding heating can be used, such as placing a high-temperature object near the surface mount thermistor. The increase in temperature and resistance value is the positive temperature coefficient. On the contrary, it is a negative temperature coefficient. If there is no change in the prevention, it indicates that the surface mount thermistor has been damaged.