The big data shows that there may be more than a hundred reasons for the dead LED lamp, which is limited to time. Today, we only take the LED light source as an example, starting from one of the five main raw materials of LED light source -- chip, and introduce some possible causes of the dead lamp.

01 Chip has poor antistatic capability

The antistatic index of LED lamp bead depends on the LED light chip itself, and the packaging material is expected to package the process is basically irrelevant, or the influencing factors are very small, very subtle; LED lamp is more likely to suffer electrostatic damage, which is related to the distance between the two pins. The distance between the two electrodes of the bare crystal of LED chip is very small, generally within 100 microns, while the LED pin is about 2 mm. When electrostatic charge is to be transferred, the greater the distance, the more likely to form a large potential difference, that is, high voltage. Therefore, sealed LED lights are often more prone to electrostatic damage accidents.

02 Chip epitaxial defect

During the crystallization process of LED epitaxial sheet at high temperature, impurities will be introduced into the substrate, residual sediment in MOCVD reaction cavity, peripheral gas and Mo source. These impurities will penetrate into epitaxial layer, prevent the nucleation of gallium nitride crystal, form various epitaxial defects, and eventually form tiny pits on the surface of epitaxial layer. These will also seriously affect the crystal quality and properties of epitaxial film materials.

03 Chip chemical residue

Electrode processing is the key process of making LED chips, including cleaning, evaporation, yellow light, chemical etching, fusion, grinding, will come into contact with a lot of chemical cleaning agents, if the chip cleaning is not clean enough, it will make harmful chemical residue. These harmful chemicals will occur electrochemical reaction with the electrode when the LED is energized, resulting in dead lamp, light decay, dark light, black and other phenomena. Therefore, it is very important to identify chip chemical residue for LED packaging plant.

04 Chip damage

LED chip damage will directly lead to LED failure, so it is important to improve the reliability of LED chip. Sometimes a spring clamp is needed to hold the chip in the process of evaporation, so the clamp marks will be produced. If the development of yellow light is incomplete and there are holes in the mask, there will be residual metal in the luminous area. In the process of grain in the front section, the process such as cleaning, evaporation, yellow light, chemical etching, fusion, grinding and other operations must use tweezers and flower baskets, carriers, so there will be grain electrode scratch.

Influence of chip electrode on welding spot: the chip electrode itself is not secure evaporation, resulting in loss or damage of electrode after welding line; Poor weldability of chip electrode will lead to virtual welding of welding ball. Improper storage of chip will lead to oxidation of electrode surface, surface staining, etc. Slight contamination of bonding surface may affect the diffusion of metal atoms between the two, resulting in failure or virtual welding.

The chip of the new structure process is incompatible with the material of the light source

The new structure of the LED chip electrode has a layer of aluminum, which is used to form a layer of mirrors in the electrode to improve the chip's light output efficiency. Secondly, it can reduce the use of gold in the evaporation electrode to a certain extent, thus reducing the cost. But aluminum is a relatively lively metal, once the packaging factory incoming material control is not strict, the use of glue containing excessive chlorine, the aluminum reflection layer in the gold electrode will react with the chlorine in the glue, resulting in corrosion phenomenon.

                                                                            Source from Huicong LED screen network