What is electrostatic damage? Which types of LEDs are susceptible to electrostatic damage and fail?
Static electricity is actually composed of charge accumulation. In daily life, especially in the dry weather environment, people will feel "electric shock" when they touch the doors and windows with their hands, which is the "discharge" to the human body when the static electricity of the doors and windows accumulates to a certain extent. For wool fabrics and nylon chemical fiber articles, the voltage accumulated by static electricity can be as high as more than 10,000 volts. The voltage is very high, but the electrostatic power is not large and will not threaten life. However, for some electronic devices, it can be fatal and cause the device to fail.
GaN-based devices in LEDs have high resistivity because they are wide-bandgap semiconductor materials. For InGaN/AlGaN/GaN double heterojunction blue LEDs, the thickness of the InGaN active layer is generally only a few Ten nanometers, and because the two positive and negative electrodes of this LED are on the same side of the chip, and the distance between them is very small, if the electrostatic charge at both ends accumulates to a certain value, this electrostatic voltage will break down the PN junction, causing Its leakage increases, and in severe cases, the PN junction breaks down and short-circuits, and the LED fails.
Because of the threat of static electricity, for the LED chips and devices of the above structure, static electricity measures should be taken to the processing site, machines, tools, instruments, including staff clothing during the processing to ensure that the LED is not damaged. In addition, anti-static materials should also be used on the packaging of chips and devices.
Some people have also improved from the substrate material, epitaxial structure and chip structure to solve the problem of anti-static breakdown to a large extent. To solve this problem to a large extent, another example is to use Flip-Chip to make two back-to-back voltage regulator tube clamps on the silicon wafer at both ends of the LED PN junction to protect the LED PN junction from the threat of static electricity. Of course, from the application point of view In other words, a protection circuit can also be added when using LEDs.
