I believe that almost all of you have encountered the leakage of patch LED beads, but the reasons for leakage are different. Some chip LED leakage is caused by the test when the LED bead is finished. Some of them are produced after a long period of time. Some of them are produced after aging. Some are generated after welding. Expanding LED today to talk about the specific reasons for the leakage of patch LED beads?
1. Leakage of patch LED beads caused by stress
Stress is produced by thermal expansion and contraction of materials. There are different materials and thermal expansion coefficients in LED beads. In the process of repeated temperature changes, it is impossible for each substance to return to its original state of contact, and there will be a certain amount of stress between them.
But it's not necessarily harmful. Only when the expansion coefficients are too different and the process conditions are not suitable, a great deal of stress may be left behind. This serious stress will crush the chip, cause the chip to break, cause leakage, part of the area to crack and not bright or completely open the circuit. When the stress is not very large, sometimes serious consequences will occur.
Originally, there are suspension bonds on the side of patch LED beads. The stress causes micro-displacement of surface atoms. The electric field of these suspension bonds is more unbalanced, which results in the change of energy level at the end PN junction and the leakage of electricity.
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