Characteristics of damage to semiconductor devices such as diodes and transistors

Characteristics of damage to semiconductor devices such as diodes and transistors

The damage of the transistor is generally due to PN junction breakdown or open circuit, with breakdown and short circuit being the most common.

In addition, there are two types of damage:

One is the deterioration of thermal stability, manifested as normal startup and soft breakdown after working for a period of time;

The other is the deterioration of PN junction characteristics, using a multimeter R × 1k test, all PN junctions are normal, but they cannot work properly after being installed. If R is used × 10 or R × When measuring at a low range, it will be found that the PN junction forward resistance value is higher than the normal value.

Measuring diodes and transistors can be measured on the circuit using a pointer multimeter, and the more accurate method is:

Set the multimeter to R × 10 or R × 1st gear (generally using R × 10th gear, use R when not obvious × During the road test of the PN junction of the second and third transistors, if the forward resistance is not too large (relative to normal value) and the reverse resistance is large enough (relative to positive value), it indicates that the PN junction is normal. Otherwise, it is questionable and needs to be welded down before testing. This is because the peripheral resistance of diodes and transistors in general circuits is mostly several hundred or several thousand ohms or above. When measuring with a multimeter in the low resistance range, the influence of peripheral resistance on PN junction resistance can be basically ignored.