The large die benefits from three core features of the Plessey process; the first being the low thermal resistance of silicon, followed by a single-surface, emitter die design and 6-inch (150-mm) wafer processing. This die is initially being produced as a technology demonstrator to enable meaningful engagement with customers to determine the optimum application fit.
Large area LED dice are suitable for Chip-on-Board (CoB) products, providing a much simpler, more uniform light emitter whilst reducing die attach and wire bond overheads. The low thermal resistance of the silicon substrate makes for easier thermal management and enhanced reliability resulting from lower temperature operation. The die uses Plessey's vertical design structure that has a cathode top and anode bottom contacts, which is ideal for scaling the effectiveness in applying large die. 6-inch wafer processing coupled with high wafer uniformity, makes – Plessey says – such large die a real commercial proposition.
David Owen, Plessey’s Marketing Director, explains, “It is clear that the next wave of general lighting products will see LEDs applied in ways that truly exploit the benefits obtained through Plessey’s leading GaN-on-Si technology. This announcement marks the start of a phase where we engage with our key partner customers in defining the commercial realisation of lighting products based on Plessey’s large GaN-on-Silicon LED die.”