Inherent semiconductor reliability considerations need to be taken into consideration and applied to all the existing LEDs products which are solid state devices. All LED reliability questions are divided into two main failure mode categories; one being the hard (catastrophic) failures, which implies infant mortality failures showing abrupt and complete cessation of the product’s function, the second category being the light output degradation over time due to wear out mechanisms. LEDs have a MTBF (mean time between failures) in excess of one million hours. The reliability of any LED device is strongly dependent the device characteristics, such as operating temperature, the function the optical output power versus the device current, the type of material used (InGaN, AlInGaP). The LED device degradation is directly linked to the generation or growth of dark spot/line defects which increases as the current density, the voltage or the temperature increases.
A very important factor to consider is the useful life of the light source being utilized. In comparison, the Lamp life for incandescent and compact fluorescent is usually defined as the time at which 50% of the test samples have “burned out” or failed to properly operate. The Quality and Reliability Engineering Laboratory is responsible for studying and predicting the reliability of the LED devices under defined operating conditions. All reliability assurance test programs are then designed to ensure the degradation rate is slow enough to minimize the probability the device will fail within specified "useful lifetime."
Depending on the current density or operating temperature conditions,when operated wihtin the specified parameters, Light Engines white LEDs lumens maintenance is better than 70% of the original lumens after 50 000 hours. Thanks to an improved reliability including better heat sinking methods, improved phosphors, polycarbonate encapsulation and assembly techniques.
Warranty - 5 years.
As mentioned earlier, the luminous intensity of LED lamps declines over time. The degradation factor depends on the operating temperature conditions, the humidity conditions, and some other environmental conditions including vibration, shock, gas, or ultra-violet which could affect the device encapsulant. In the case of the Light Engines LED packaging, the mechanical stress is maintained at zero by design! Extreme temperature changes cannot result as for epoxy resin based LED designs which are affected by expansion thermal coefficients and varying levels of mechanical stress. Mechanical overstress induced by temperature is the most common cause of standard LEDs failure where epoxy resin can crack at low temperatures or expand at high temperatures stressing many of the internal components...
In house reliability testing is conducted to confirm the design margin and limit levels of devices, or to maintain and confirm the quality assurance levels of mass produced devices. Standard testing such as operating accelerated life and environmental testing are conducted as generic on going verification methods. They include mechanical shock, vibration, temperature and power cycling, corrosion resistance testing
Thanks to its rugged design, all Light Engines LEDs have performed well in many different tests proving very high durability, reliability, and lumen maintenance values.
- UL, UL quarterly manufacturing inspections