release time：2020-05-16 source：Shenzhen TOFOLED Lighting Technology Co., Ltd.
With the popularization and use of LED lights, the problems of LED lights also follow. Let's talk about the causes of damage to LED lights.
The failure of LED lamps comes from the failure of power supply and drive, and the second comes from the failure of the LED device itself. Usually the damage to the LED power supply and driver comes from the over-current surge (EOS) of the input power supply and the open circuit fault at the load end. The over-current impact of the input power supply often causes damage to the driver chip in the drive circuit, as well as breakdown damage to passive components such as capacitors. A short-circuit fault at the load end may cause overcurrent driving of the drive circuit, and the drive circuit may be short-circuit damaged or overheated due to a short-circuit fault. The failure of the LED device itself mainly has the following situations.
1. Electrostatic discharge event
Electrostatic discharge (ESD) damage is currently the most common type of transient overvoltage hazard in the manufacture, transportation and application of highly integrated semiconductor devices, and LED lighting systems must meet the "human body electrostatic discharge mode" of IEC61000-4-2 8kV contact discharge to prevent the system from over-current impact failure which may be caused by electrostatic discharge.
The performance of the LEDPN junction array will be reduced or damaged. The internal failure of the LED chip caused by the discharge path of the ESD event may be only partial functional damage. In severe cases, it will also cause permanent damage to the LED light bar.
2. Transient overcurrent event
Transient overcurrent event means that the current flowing through the LED exceeds the maximum rated current in the technical data manual of the LED. This may be caused directly by the large current or indirectly by the high voltage, such as transient lightning strikes, switching power supply transients Overcurrent caused by overvoltage events such as high-level switching noise and grid fluctuations. These events are transient and have a very short duration. Usually, we call them peaks, such as "current spikes" and "voltage spikes." The conditions that cause transient overcurrent events also include transient overcurrents when the LED is turned on or when it is plugged and unplugged.
For LED light bars in automobiles, the transient load dump surge of ISO7637-2 is an important threat to its normal operation.
The failure mode of an LED after an electrical shock is not fixed, but it usually results in damage to the solder wire. This damage is usually caused by extremely large transient overcurrents. In addition to causing the welding wire to burn out, it may also cause damage to other parts near the welding wire, such as the sealing material.
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