The lifetime of LED components

Basically, LED is a kind of semiconductor component (diode) that can emit light, which is also a type of electrical component. Normally, the estimation of LED components should use accelerated life testing (ALT led street light pdf) method with a couple of mature samples and statistical analysis. The current LM-80 specification based experiments on three different testing temperatures, and together with the lumen maintenance regulated by the Energy Star. It is not really controversial to use it as the single standard to determine the lifetime of LED components. Especially after the launching of TM-21 life estimation solution, LED chip manufacturers no longer determine the service life of their products by themselves. But led heat dissipation problems still existed:

 

Basically, LED is a kind of semiconductor component (diode) that can emit light, which is also a type of electrical component.

 

  1. In the LM-80 specification, LED chips should be tested in three different working temperatures. In each temperature, at least 85% LED chip should pass the 6000-hour aging test, and using the lumen maintenance parameter as the only basis for judging. The problem is this is a statistic process. Within the 6000-hour test, there are still 15% LED chips cannot pass these tests. The failure of every single LED chip will cause the failure of the lamp, thus for LED application manufacturers, lumen maintenance based on the LM-80 specification is unreliable.
  2. In order to increase the accuracy of LM-80 in estimating the lifetime of LED components, clear definition of failure modes are necessary, for example: lumen maintenance rate, dead lights, burned components, color coordinate/voltage/current offset. The occurrence of any one of these faults means the death of the lamp. In addition to grain quality, including the selection of packaging materials and packaging technologies will impact the lifetime and reliability of LED elements. Therefore, LED elements insisted on LM-80 tests need to pass the tests for reliability qualification, which is necessary.
  3. In order to reduce the interruption risk during LE-80/6000 hours tests caused by the failure of LED components, usually LED manufacturers may increase the number of testing samples. According to the regulation of Energy Star, dead lights will not be included into the calculation of average lumen maintenance rate, but should be marked within the final LM-80 report. Thus, when LED application makers read about these LM-80 reports, they will learn about the failure rate as well as the average lumen maintenance rate.