Void Formation and Growth at Solder-Bonded Interfaces in HP LEDs
Heat flux inside the HP LED chip is also increasing with the increasing drive current, integration and miniaturization of LED chips. The junction temperature of LED strongly depended on the heat transmission capacity of die attach layer, which provided the heat dissipation channel between the heat generating LED chips and the heat slug. The voids, interrmetallic compounds or a small delamination would lead to the increasing thermal resistance in the die attach layer. In this paper, the reliability of soldered-bonded interfaces was studied in high-brightness LEDs, which were prepared by Cree and currently available on the market. Results revealed that the higher drive currents would lead to the accelerated degradation or failure of treated LEDs. Additionally, the injection current had an important effect on void formation and growth at the solder-bonded interfaces. The larger drive current would induce the delamination between LED die and heat slug. This study provided some guidance for the end users and a theoretical basis for solder-bonded technologies.
W. Liu and P. Jin, "Void Formation and Growth at Solder-Bonded Interfaces in HP LEDs", Advanced Materials Research, Vol. 936, pp. 1900-1904, 2014