Ralph Hubert Peters

High power LED subassemblies for automotive front light application

A high power LED platform for automotive front lighting is described. Based on small footprint ceramic LED packages customized designs can be realized in a highly flexible way. The diverse automotive applications have different requirements in terms of optical performance, i.e. assembly tolerance and package density, but also regarding the thermal performance of the boards, which are used as substrates for the LEDs. For a future design of a low beam function with a distributed multi cavity reflector concept the optical tolerances are evaluated which are required to form a beam which provides the sharp cut-off line needed to illuminate the road without glaring the oncoming traffic. For such optical concept an overall positioning tolerance below 100μm is required. The tolerances of the LED assembly process on advanced PCB solutions, including reflow soldering, are investigated and compared with alternative assembly solutions. Additionally, the thermal performance of the LED subassemblies is investigated by T3Ster measurements and finite element simulations. The advantage of special Cu-IMS is demonstrated compared to Fr4 based and Al-IMS solutions.