First, the chip anti-static ability is poor The anti-st […]
First, the chip anti-static ability is poor
The anti-static target bump of the LED lamp bead depends on the LED light chip itself, and is basically irrelevant to the package data estimation packaging process, or the impact factor is very small and very slim; the LED lamp is more vulnerable to electrostatic damage, which is a distance from the two pins. Contact, the distance between the two electrodes of the LED chip bare crystal is very small, usually within a hundred microns, while the LED pin is about two millimeters, when the electrostatic charge to be transferred, the greater the distance, the more likely to constitute a large potential difference , which is the high voltage. Therefore, after being sealed into LED lights, it is often more prone to electrostatic damage.
Second, chip epitaxy defects
In the process of high-temperature crystal growth of LED epitaxial wafers, the substrate, residual deposits in the MOCVD reaction cavity, peripheral gas, and Mo source will all introduce impurities. These impurities will enter the epitaxial layer and hinder the nucleation of the gallium nitride crystal to form various types. All kinds of epitaxial defects will eventually form fine pits on the epitaxial layer, which will also seriously affect the crystal quality and performance of the epitaxial wafers.
Third, the chip chemical residue
Electrode processing is a key process for manufacturing LED chips, including cleaning, vapor deposition, yellow light, chemical etching, fusion, and grinding. It will come into contact with many chemical cleaning agents. If the chip cleaning is not clean, harmful chemicals will remain. These harmful chemicals will electrochemically react with the electrodes when the LED is energized, resulting in the appearance of dead lights, light decay, darkness, and blackening. Therefore, it is very important for the LED packaging plant to determine the residue of the chemical on the chip.
Fourth, the incompatibility of the new structural process chip and the light source material
The new structure of the LED chip electrode has a layer of aluminum. Its role is to form a mirror in the electrode to improve the light output power of the chip, and secondly to reduce the use of gold when evaporating the electrode to a certain extent and then reduce the cost. However, aluminum is a kind of vivid metal. Once the packing plant has strict control over incoming materials, the use of chlorine-clad over-charged glue will cause the aluminum reflective layer in the gold electrode to react with the chlorine in the glue and then cause corrosion.