Overcurrent and overvoltage interference of LED and its protective measures

Overvoltage and overcurrent damage of LED components is independent of the number of occurrences or duration of interference energy, as any overvoltage and overcurrent disturbances can cause LED damage. This damage can manifest as an immediate failure of the device or a long time after the overvoltage and overcurrent disturbances have occurred. The miniaturization of LED chips and the complication of the electrical structure of LED lamps are making this problem even worse.

First, LED overvoltage and overcurrent fault phenomenon

When overvoltage and overcurrent disturbances occur, component performance may be impaired or damaged. Overvoltage and overcurrent damage of LED components is independent of the number of occurrences or duration of interference energy, as any overvoltage and overcurrent disturbances can cause LED damage. This damage can manifest as an immediate failure of the device or a long time after the overvoltage and overcurrent disturbances have occurred. The miniaturization of LED chips and the complication of the electrical structure of LED lamps are making this problem even worse. There are two main phenomena in the overvoltage and overcurrent faults of the LED chip in the lamp:

a, the chip internal welding line is damaged

The first failure mode caused by overvoltage and overcurrent interference is damage to the weld line inside the LED package. This damage usually manifests as a broken wire. In addition, overvoltage and overcurrent disturbances can also cause damage to other materials (such as sealing materials or phosphors) that are close to the weld line.

b, the chip pad position is damaged

Another failure mode caused by overvoltage and overcurrent interference is that the position of the LED chip body near the pad is damaged.

Second, the main cause of overvoltage and overcurrent interference in LED

There are many reasons for overvoltage and overcurrent interference in LED chips, such as surge, static electricity, pulse signal interference from other equipment, improper working methods when the lamp is assembled, and insufficient grounding point, causing rapid switching of current and high voltage. Causes overvoltage and overcurrent interference. However, the following two cases are the main causes of overvoltage and overcurrent interference during the production and use of LED lamps.

a, electrostatic discharge ESD

Electrostatic discharge is an unavoidable risk in the production, transportation and processing of most electronic components. Although most of the current LED chips have anti-static interference design is generally 2kV, but electrostatic discharge is still the main reason for LED chip damage in the production of lamps.

b, short-term overload

Short-term overload, that is, the input voltage or current of the LED exceeds its rated value such as surge voltage or lightning strike in a short time. Overloading generally lasts for only a very short period of time and typically does not exceed 500ms. A similar voltage or current is called a spike or spike current. Short-term overload is the main reason for the damage of the LED chip during normal use of the luminaire.