Conclusions
In this paper we obtained the highest test temperature
to accelerate the life of the LED devices from the step
stress test, and the temperature could effectively shorten
the test time, without any new failure mode imported. The
higher test temperature could accelerate the degradation at
the early period of test, and with a consistent variation
between different levels at the later period of the
experiment. The high temperature test could fully explain
the degradation trend of life.