I believe that almost everyone has encountered the leakage of SMD LED lamp beads, but the reasons for leakage are different. The leakage of some SMD LED lamp beads is caused by the test after the LED lamp beads are packaged, some are caused by long-term placement, some are generated after aging, and some are generated after welding. Expansion of LED Today, what are the specific reasons for the leakage of SMD LED lamp beads?

1. The leakage stress caused by the stress of the SMD LED lamp bead is caused by the thermal expansion and contraction of the material. In LED lamp beads, different materials have different thermal expansion coefficients. In the process of repeated temperature changes, it is impossible for the substances to return to the original contact state, and a certain stress will be generated between them. But not necessarily harmful. Only when the coefficient of expansion is too different and the process conditions are not suitable, a large amount of stress will be left. This severe stress will crush the chip, causing damage to the chip, resulting in leakage, cracking in some areas, or complete disconnection. When the stress is not too great, sometimes there are serious consequences. It turns out that there are dangling keys on the side of the SMD LED lamp beads. The stress causes micro-displacements of surface atoms. The electric field of these dangling bonds is more in an unbalanced state, resulting in a change in the energy level state of the end-face PN junction. , resulting in a leak. 2. The leakage phenomenon caused by improper use of SMD LED lamp beads rarely occurs. When a high reverse voltage is applied to the LED lamp bead, it may damage the PN junction and cause leakage. 3. Improper p process leads to chip cracking, uneven colloid at the bottom of the SMD LED lamp bead chip, or holes under the pad, which may damage the chip and cause liquid leakage or failure during wire bonding. Improper adjustment of the wire bonder may damage the chip, resulting in leakage or malfunction. Fourth, the problem of static electricity The problem of static electricity cannot be ignored. Electrostatic discharge must have a conductive loop, which does not mean electrostatic damage. When the LED lamp bead has only a small amount of leakage problem, the accidental damage of static electricity can be considered. If it occurs in large numbers, it is more likely to be a chip contamination or stress problem. 5. The leakage of silver glue is too high, and the deviation of the wire causes water leakage. The leakage of silver glue is too high, and the deviation of the wire causes water leakage. It is a common problem in the LED lamp bead packaging industry. 6. The chip is polluted The leakage caused by the contamination of the leakage chip is a very worthy of attention: the LED chip is very small, and dust can easily shield it. The most important thing is that dust, water vapor and various impurity ions will adhere to the surface of the chip. , it will not only affect the inside of the LED chip on the surface, but also spread to the inside of the LED chip. For example, copper and sodium ions diffuse easily into semiconductor materials, and very small amounts can severely degrade the performance of semiconductor devices.