With the increasing competition in the LED industry, LED quality has received unprecedented attention. During the manufacturing, transportation, assembly, and use of LEDs, production equipment, materials, and operators may cause electrostatic (ESD) damage to LEDs, causing LEDs to prematurely increase leakage current, increase light attenuation, and even die lights. Phenomenon, static electricity has a very important impact on LED quality. The antistatic index of LED is more than simply reflecting its antistatic strength. The antistatic ability of LED has a great relationship with its leakage value and overall reliability. It is also a comprehensive reflection of overall quality and reliability. Because often anti-static LED, its light and electrical characteristics will be good.

LED static failure principle:

Due to the existence of different degrees of static electricity in the environment, a certain amount of electrostatic charges of opposite polarities can accumulate at both ends of the PN junction of the LED chip through electrostatic induction or direct transfer, forming different degrees 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 an extremely short time (nanoseconds), thereby generating heat. The conductive layer and 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, darkening, dead lights, short circuits, etc.

LEDs that are damaged by static electricity often cause dead lights and leakage. With slight static damage, the LED is generally not abnormal, but at this time, the LED has certain hidden dangers. When it is damaged by secondary static electricity, the probability of dim light, dead lights, and leakage will increase. Through case analysis and summary, when the LED chip is subject to slight, undetected electrostatic damage, the scanning electron microscope needs to be magnified to more than 10,000 times for further diagnosis to prevent a higher probability of failure.

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

The antistatic index of LED lamp beads depends on the LED light-emitting chip itself, which is basically not related to the packaging material's expected packaging process, or the influencing factors are small and subtle; LED lamps are more vulnerable to electrostatic damage, which is related to the distance between the two pins The relationship between the two electrodes of the bare chip of the LED chip is very small, generally within 100 micrometers, 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 an LED lamp, electrostatic damage accidents are more likely to occur.

Good antistatic index is a comprehensive reflection of the comprehensive performance of LED

The antistatic index of LED is more than simply reflecting its antistatic strength. Anyone who understands the design and manufacture of LED chip epitaxy knows that the antistatic ability of LED chips has a lot to do with its leakage value and overall reliability. A comprehensive manifestation of comprehensive quality and reliability, because LEDs with high antistatic capabilities often have good optical and electrical characteristics.

The good antistatic index of LED not only means that it can be applied to various products and various environments, but also a reliable reflection of the comprehensive performance of LED. According to different brands of LED antistatic indicators, the LED antistatic of various international LED manufacturers is generally better, and some B products, miscellaneous brands, Korean chip antistatic is still very low. The level of antistatic ability of LED is the core manifestation of LED reliability. Even if the brightness and electrical indicators of the LED are very good, once its antistatic index is low, it is easy to die the lamp due to electrostatic damage.

Enterprises familiar with LED manufacturing are well aware that the current product quality in China's LED industry is uneven, and the stability of different quality LEDs is very different, which makes many LED users confused and even suffer. Among them, the dark and bright, dead light, leakage and other quality accidents caused by the low antistatic LED are the most serious losses. Especially, there are some inferior Taiwanese products with low quality and the influx of chips from Korean companies. Large-scale products, intermediate sellers are often sub-optimal, and many companies are facing huge risks. Industry experts believe that as long as LED packaging companies choose LED chips with higher static resistance and better packaging procedures, the products must be reliable and stable.

Detection method:

Many companies evaluate the anti-static performance of LEDs by 'trying a batch to see the consequences'. In fact, this is an evaluation method with a long cycle, large error, high cost and high risk.

Electrostatic breakdown of LEDs is a very complex process. In the antistatic test of LED, static electricity must be directly applied to the two pins of the LED. The discharge waveform of the instrument has strict standards. There are two modes, human mode and mechanical mode, which are used to measure the antistatic ability of the measured object.

Human body mode: When static electricity is applied to the measured object, a 330 ohm resistor is applied in series. This is to simulate the charge transfer when the human is in contact with the device. The human-to-object contact usually acts at 330 ohms, so it is called human body mode.

Mechanical mode: Static electricity is directly applied to the device under test. Analog tool machinery directly transfers electrostatic charges to the device, so it is called mechanical mode.

There are also some differences between the electrostatic charge storage energy and the discharge waveform in the two test instruments. The results of using the human body model are generally 8-10 times that of the mechanical model. The LED industry, as well as many companies today, use human body indicators.

Testing standards:

IEC61000-4-2 by the International Electrotechnical Commission

ANSI-ESDSTM5.1.2-1999 by the International Electrostatic Association

《ANSI / ESDA / JEDEC JS-001》

JESD22-A114 / 115c by the International Joint Committee on Electronic Devices

Test sample types:

Chip bare chip, pin-type lamp beads, conventional patch lamp beads, piranha, high-power lamp beads, modules and digital tubes, LED lamps.