Operational thermal limit stress analysis of LED device under highly accelerated degradation testing

This work addresses the challenges related to the rapid lifespan evaluation of Light Emitting Diode (LED) packaged devices, which feature advantages such as long service life and high reliability. Traditional reliability test methods are inadequate for rapid lifespan assessment. A Highly Accelerated Degradation Test (HADT) was designed and implemented to investigate the thermal limit stress of LED devices. The results show that under specified humidity stress conditions, the operational thermal limit stress for white and blue LEDs are 105°C and 115°C, respectively. The presence of fluorescent powder is identified as the primary factor causing the difference in thermal limit stress between white and blue LEDs. Additionally, a stepwise fitting analytical method for optical parameter degradation in LEDs is proposed. This method can effectively determine the operational thermal limit stress of LEDs under given humidity stress, offering a valuable reference for the rapid lifespan evaluation of LED packaged devices.