I believe that almost everyone has encountered the leakage of SMD LED lamp beads, but the reasons for leakage are different. Some SMD LED lamp bead leakage occurs during the test after the LED lamp bead is packaged, some occur after long-term placement, some occur after aging, and some occur after soldering. Hollylight LED today talked about the reasons for the leakage of the detailed SMD LED lamp beads?

       1. The leakage stress of the chip LED lamp beads formed by the stress is caused by the thermal expansion and contraction of the material. In LED lamp beads, there are different materials, and the coefficient of thermal expansion is different. In the process of repeated temperature changes, it is impossible for the substances to return to the state they were in when they were initially touched, and there will be a certain amount of stress between them. But it doesn’t have to be harmful. Only when the coefficient of expansion differs too much and the process conditions are inappropriate, a lot of stress may be left. This severe stress will crush the chip, cause the chip to be damaged, cause leakage, and part of the area will be cracked but not bright or completely open. When the stress is not great, severe consequences sometimes occur. Originally, there are dangling bonds on the side of the SMD LED lamp bead. The stress causes micro-displacement of the outer atoms. The electric field of these dangling bonds is even more in an unbalanced state, and the energy level at the end face PN junction is changed. , The formation of leakage.

       2. improper use of the chip LED lamp beads, this situation rarely occurs. When a higher reverse voltage is applied to the LED lamp beads, it may damage the PN junction and cause leakage. ,

       3. The process is improper, causing the chip to crack and the glue at the bottom of the SMD LED lamp bead chip is uneven, or there is a cavity under the pad, which may endanger the chip's leakage or failure during wire bonding. Improper adjustment of the wire bonder will damage the chip, cause leakage or failure. ,

       4. the static electricity problem The static electricity problem cannot be ignored either. Electrostatic discharge requires a conductive circuit, not to say that static electricity is harmful. When the LED lamp beads have only a small amount of leakage problems, you can consider the accidental damage caused by static electricity. If it happens a lot, it may be more of a chip contamination or stress problem. ,

       5, the leakage of silver glue and the leakage of wire bonding are formed by excessively high silver glue and the leakage of wire bonding. It is a common sense problem that can be seen in the LED lamp bead packaging industry.

       6. Leakage caused by contamination of the chip is a problem worthy of attention: the LED chip is very small, and dust, etc., can easily shield it. The most important thing is dust, water vapor, and other materials. This kind of impurity ions will adhere to the surface of the chip, and not only have an effect on the inside of the LED lamp bead chip on the outside, but also disperse into the inside of the LED lamp bead chip to have an effect. For example, copper ions and sodium ions are easily dispersed into semiconductor materials, and a very small amount can severely deteriorate the function of semiconductor devices.