Influence of lens structure on the mechanical strength of high-power light emitting diodes

The paper presents the failure mode of high-power light emitting diodes (LEDs) under mechanical pressure and verifies the bonding wire as the weakest structure of LEDs. Different lens radiuses and heights are studied to demonstrate the influence of lens parameters on the mechanical strength of LEDs. The experimental results have demonstrated that a LED device has a higher failure force when the lens radius or height is larger. The loading force increases with the compressing displacement until an open circuit happens, which is caused by the bonding wire fracture detected by X-ray imaging. The fracture position lies in the part over the first bond, addressed as heat affected zone, which corresponds with the stress concentration position in the simulation.