LED lighting and backlight technology have made remarkable progress in the past decade. As a new generation of green light source, LED light source has appeared in the field of traditional lighting, but there are still many unresolved problems in LED light source.
These include poor consistency, high cost, and poor reliability. The most important issues are stability and reliability issues. Although the life of LED light sources is currently predicted to exceed 50,000 hours. But this life refers to the theoretical life, the life of the light source at 25 ° C. In the actual use process, it will encounter harsh environments such as high temperature and high humidity, amplify LED light source defects, accelerate material aging, and make LED light source fail quickly.
Physical mechanism of failure mode
The LED lamp bead is a system consisting of multiple modules. Failure of each component will cause the LED bead to fail. From the light-emitting chip to the LED lamp bead, there are nearly 30 failure modes, as shown in Table 1, the failure mode table of the LED lamp bead. Here, the LED is divided into two parts, a chip and an external package. Then, the mode and physical mechanism of LED failure are also divided into two types: chip failure and package failure.
Table 1 LED lamp failure mode
The main factors causing LED chip failure include: static electricity, current and temperature.
Electrostatic discharge can release instantaneous ultra-high voltage, which brings great harm to LED chips. LED chip failure caused by ESD is divided into soft failure and hard failure. The high voltage/current caused by static electricity causes the LED chip to be short-circuited into a hard failure mode. The reason for the short circuit of the LED chip is that the excessive voltage causes the electrolyte to rupture, or the excessive current density is the current path generated in the chip.
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