别墅里的肉奴不准穿衣服_免费观看又色又爽又黄的韩国_双乳被一左一右的吸着_亚洲愉拍99热成人精品热久久_全是肉的高h短篇列车_精品无码国产污污污免费_国产一区二区三区在线视頻_继夫开荤粗肉hhhh_穿书之辣宠文里当女配

It is believed that almost everyone has encountered a situation where patch LED lamp beads leak electricity, but the reasons for the leakage vary. Some SMD LED lamp beads leak due to testing after packaging, some due to long-term storage, some due to aging, and some due to welding.

1. The stress generated by the leakage stress of the LED lamp beads is caused by the thermal expansion and contraction of the material. There are different materials with different thermal expansion coefficients in LED lamp beads. In the process of repeated temperature changes, it is impossible for substances to return to their initial contact state, and certain stresses will be generated between them. But not necessarily harmful. Only when the difference in expansion coefficients is too large and the process conditions are not suitable, can large stresses be left behind. If the stress is severe, it can crush the chip, damage the chip, cause electrical leakage, crack some areas, or completely crack the chip. Even if the pressure is low, it can sometimes have serious consequences. The side of the original patch LED lamp beads has a hanging key. Stress causes slight displacement of surface atoms. The electric field of these dangling bonds is even more in an unbalanced state, leading to changes in the energy level state at the end PN junction, resulting in leakage.
2. Improper use leads to leakage of LED beads on the chip, which rarely occurs. When applying a high reverse voltage to an LED bead, it may damage the PN junction and cause electrical leakage.
3. Improper workmanship can lead to chip cracking, uneven gel at the bottom of the LED bead chip, or holes under the pad, which can damage the chip, causing electrical leakage or failure during wiring. Improper adjustment of the wire bonder can damage the chip, causing electrical leakage or malfunction.
4. Electrostatic problems Electrostatic problems cannot be ignored. Electrostatic discharge must have a conductive circuit, which does not mean there must be damage if there is static electricity. When there is only a small amount of leakage of LED lamp beads, the problem of accidental electrostatic damage can be considered. If it occurs in large quantities, it is more likely to be a problem of chip contamination or stress.
5. Too much silver glue leads to bias welding leakage, which is a common sense problem in the LED bead packaging industry.
6. Leakage caused by chip contamination is a concern: LED chips are very small and easily covered with dust. The most important thing is that dust, water vapor, and various impurity ions will adhere to the chip surface., It will not only have an impact on the inside of the LED bead chip on the surface, but also spread to the inside of the LED bead chip to have an impact. For example, copper and sodium ions can easily diffuse into semiconductor materials, and very small amounts can seriously degrade the performance of semiconductor devices.