Analysis of new direct on PCB board attached high power flip-chip LEDs

Abstract

Recent progress in wafer level packaging technologies has enabled high power Flip Chip (FC-LEDs), Chip Scale Package (CSP-LEDs) and Wafer Level LED Packages (WLP-LEDs) for direct assembly on printed circuit boards (PCB) for lighting application. The LEDs can be soldered with a SMT compatible reflow process on PCB. Packaging simplicity and flexibility, increased position accuracy, low thermal resistance and reduced cost has been the main motivation for these developments. In addition, the small chip sized LED package can enable on board level closer placement of the light emitting surfaces without the disturbing wire bond. This is a benefit, e.g. for optical design of LED matrix applications, in which multiple high power light pixels are switched individually and sharp contrast is required, as for automotive front lighting for instance.