One is overvoltage impact, that is LED on current exceeds the LED technology databooks maximum rated current, including overvoltage caused by impact; Another kind is overheating damage. The damage can be represented as a device failure, may also occur immediately after the event in current shock long before failure, shorten LED using life.
As a new type of green power white LED lighting technology, there is light conversion efficiency, low energy consumption, long life, no maintenance etc, were gradually applied in various lighting field. The LED long life is based on its safe working environment, LED lighting, basically have two kinds of threat affect its life: one is the impact, which LED to b on current exceeds the LED technology databooks maximum rated current, including overvoltage caused by impact; Another kind is overheating. The damage can be represented as a device failure, may also occur immediately after the event in current shock long before failure, shorten LED using life.
LED lamps and lanterns the cause of damage：
LED lamps and lanterns one is from a power failure and failure, the second is derived from the device itself LED. Usually LED power and drive the damage from the input power of the overvoltage impact (EOS) and the breaker failure. overvoltage impact power input impact tends to cause driving circuit of the damage, and drive chip capacitor passive components, etc. Occurs breakdown The load may cause short-circuit fault currents of driving circuit, drive circuit driver may have short-circuited or damage to overheating fault is damaged.
The device itself LED failure basically has the following kinds:
1 、The transient flow events
Transient flow incident refers to the LED current flows over the LED technology databooks maximum rated current, this may be due to large current directly produce may also be generated by high voltage indirectly, such as transient lightning, switching power supply noise, the transient switch power fluctuations caused by such event of over-voltage flow. These events are transient, extremely short duration, we usually have called rush, such as "current peak", "rush" voltage. Cause transient flow events were also include LED through power, or charged inserted the transient currents. For the automobile LED lighting, ISO7637-2 behind the transient load surge impact is the normal work of an important threats. After the impact from LED failure mode is not fixed, but usually cause welding damage. This damage normally by great transient currents cause. Besides welding wire cut outside, still can burn in other parts of the welding line near the damage, such as sealing materials.
2 、The electrostatic discharge events
Electrostatic discharge (ESD) damage is currently high integration semiconductor manufacturing, transportation and the application of the most common a transient overvoltage hazards, and LED lighting system must meet IEC61000-4-2 standard "human electrostatic discharge 8kV model", in order to prevent contact discharge in electrostatic discharge may cause the has overvoltage impact.
LED PN junction array performance will appear to reduce or damage, ESD events to discharge path LED chips, and the failure of internal failure may be severe damage, local function can also cause LED permanent damage.
For nearly 80% energy into heat LED lighting design, thermal management and fault overheating protection is a challenge. Theory and practice has proved that the LEDperformance and life is the PN junction with LED temperature is closely related to the job. When the high temperature LED chip 10 degrees, flux will decay 1%, LED the life will be reduced by 50%.
