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What is an electrostatic discharge (ESD) event?

ESD is generally considered to be a common hazard in the manufacturing, transportation, and handling of many semiconductor devices. They are also listed as the second category "human body electrostatic discharge mode" of the MIL-STD-883 standard, which means that they can withstand 2kV electrostatic discharge. Although the LED is equipped with a protective device, it is still possible to damage the EOS during electrostatic discharge.
What is a transient overcurrent event?

When a transient overcurrent event occurs, the current through the LED will be higher than the maximum rated current in the LED technical data sheet, which may be directly generated by high current or indirectly generated by high voltage.

These events are transient, which means that they only last for a very short time when they occur, usually no more than one second.

Sometimes they are also called "spikes", such as "current spikes" or "voltage spikes." If an over-current event occurs immediately when the LED is powered on or plugged into an energized power source (also known as "plug and unplug"), this over-current event is called "surge current."
What is overdrive?

When overdrive occurs, the LED continues to be driven by the maximum rated current, which may be caused by the design of the drive circuit, whether intentional or unintentional. As this is a design choice in the LED drive circuit, this application note will not repeat the corresponding protection circuit of EOS caused by this reason.
LED overcurrent shock

1. The welding wire is damaged

One of the common failure modes caused by EOS is damage to the bonding wires inside the LED package, as shown in Figure 1 below. This kind of damage usually manifests itself as a burned or blown connection. In addition, EOS events can cause damage to other materials close to the welding line, such as sealing materials or phosphors.

2. Damage near the pad

Another common failure mode caused by EOS is damage to the LED chip body near the pad, as shown in Figure 2 below
to sum up

Correct luminaire design is the key to launching successful products in the ever-evolving LED lighting market. Most LED circuit designers know good thermal, optical and electrical design principles, but they may not have considered adding protection circuits to prevent damage caused by improper use or live plugging. Not every application requires surge protection, and adding such protection will increase design costs and may reduce efficiency. It is recommended to add a certain level of protection to LED modules without onboard power supply to minimize the risk of inrush current due to separate power supplies. Installers who are accustomed to installing traditional lighting products that can withstand live plugging and unplugging may accidentally plug and unplug the LED array when the power is on, causing the LED lamps to fail. Low cost of use