The main reason for diode failure

1. Voltage breakdown (overvoltage)

For ordinary rectifier diodes, as long as there are fluctuations in the power grid, turning on and off of high-power equipment in the same network, lightning strikes, switch sparks, large capacity inductive loads, and large capacity capacitive loads in the application circuit, when the instantaneous voltage is higher than the reverse breakdown voltage value of the diode, voltage damage parameter attenuation or complete breakdown short circuit open circuit may occur. For a protective diode, it means that there is a voltage in the circuit that is higher than the protection voltage of the device, causing continuous conduction of the protective device and permanent damage that cannot be recovered, which may result in voltage damage parameter attenuation or complete breakdown, short circuit, and open circuit. The failure time of voltage breakdown has no fixed pattern, but it is more likely to occur at the moment of power on/off.

2. Current breakdown (overcurrent)

When the application selection margin is insufficient, other components in the application circuit experience short circuits, resulting in sudden increases in current, or when the load in the application circuit is abnormal, the instantaneous high current causes the diode chip to carbonize at high temperature in a very short period of time, or the instantaneous high temperature causes the chip to explode, resulting in serious damage to the PN junction of the chip and causing short circuits or open circuits. The higher probability of current breakdown occurs during power on testing or normal use.

3. Temperature breakdown (over temperature)

When the application selection margin is insufficient, the device design position is close to high-power heating elements, and the application environment temperature is too high, the junction temperature of the diode chip exceeds its current decay temperature, causing a linear decrease in the diode's overcurrent capability. However, when the current in the circuit remains constant, the junction temperature of the diode chip will rapidly increase. After reaching the limit temperature of the material, the silicon-based material will melt and carbonize, resulting in short circuits or open circuits. Temperature breakdown often occurs during aging or user use.

4. Stress damage (stress)

Due to the high hardness of silicon-based chips, their ability to resist mechanical stress is weak. In the process of diode sealing and testing, such as plastic sealing, cutting and bending of application end pins, shaping and bending of pins, locking of heat dissipation fins by electric batch, mechanical collision, etc., the diode chip is damaged or mechanically cracked, and its various electrical parameters decay or fail when powered on. Serious injuries often occur at the moment of power on/off or shortly after power on, while the failure time after minor injuries is irregular, posing a significant safety hazard.

5. Overload breakdown

The issues of application selection margin, consistency of diode parameters in multi diode parallel circuits, and power increase caused by external environmental factors can lead to one or more situations such as diode overvoltage, overcurrent, and overheating occurring simultaneously, resulting in diode breakdown, short circuit, or open circuit in a short period of time.