Technology | LED static failure principle and detection method（1）

607 views admin 2020-04-10

As the competition in the LED industry continues to intensify, LED quality has received unprecedented attention. During the manufacturing, transportation, assembly, and use of LEDs, production equipment, materials, and operators may cause static electricity (ESD) damage to the LED, resulting in premature LED leakage current increase, increased light attenuation, and even dead lights. Phenomenon, static electricity has a very important influence on the quality of LED. The anti-static index of LED is not only a simple expression of its anti-static strength. The anti-static capability of LED has a great relationship with its leakage value and overall reliability, but also a comprehensive manifestation of overall quality and reliability. Because LEDs with high antistatic properties tend to have good optical and electrical properties.

LED static failure principle

Due to the different levels of static electricity in the environment, a certain amount of electrostatic charges of opposite polarities will accumulate at both ends of the PN junction of the LED chip through static induction or direct transfer, forming different levels of electrostatic voltage.

When the electrostatic voltage exceeds the maximum withstand value of the LED, the electrostatic charge will be discharged between the two electrodes of the LED chip in a very short time (nanoseconds), thereby generating heat. The conductive layer and the PN junction light-emitting layer inside the LED chip form a high temperature above 1400 ° C. The high temperature causes local melting into small holes, which causes LED leakage, dimming, dead lights, and short circuits.

LEDs damaged by static electricity often cause dead lights and electric leakage. With slight electrostatic damage, the LED is generally not abnormal, but at this time, the LED has certain hidden dangers. When it is subjected to secondary electrostatic damage, there will be increased chances of dimming, dead lights, and leakage. Through a case analysis, when the LED chip is slightly and undetected by electrostatic damage, it is necessary to enlarge the scanning electron microscope to more than 10,000 times to further confirm the diagnosis in order to prevent a higher probability of failure accidents.

The antistatic index depends on the LED chip, but the LED lamp is more susceptible to electrostatic damage

The LED lamp bead's antistatic index depends on the LED light-emitting chip itself, which is basically irrelevant to the packaging material expected packaging process, or the influence factor is very small and very small; LED lamps are more susceptible to electrostatic damage, which is related to the distance between the two pins The relationship between the two electrodes of the bare die of the LED chip is very small, generally within 100 microns, and the LED pin is about two millimeters. When the electrostatic charge is to be transferred, the larger the distance, the easier it is to form a large potential difference , That is, high voltage. Therefore, after being sealed into LED lights, electrostatic damage accidents are more likely to occur.