Wafer Bonding for LEDs
LED packaging techniques have been optimized to capture and direct otherwise-wasted light intensity. Since these photons reside at first within the chip, the strategy is to direct the photons to a useful location instead of allowing them to reflect back into the material where they are absorbed and produce waste heat.
Phosphors - materials which glow upon exposure - increase the production of the desired wavelength or color. This allows broader-band white light to be produced from simpler blue LED, similar to a fluorescent light tube. White light is much more pleasing to the eye, is necessary for general lighting applications, and is required for ultra high-efficiency LEDs.
Wafer bonders supplied by SUSS MicroTec help to address both of these issues by bonding the LED substrate to various substrates, including enhanced phosphor materials, mirrors or other optical elements which shape or guide the photon emission from the chip. Wafer bonding also helps manage thermal load by removing waste heat; this heat would otherwise reduce LED efficiency. Each incremental improvement in chip output contributes to that goal of higher device efficiency, providing higher performance and commanding a higher price. Available in either manual or automated configurations, SUSS bonders can bond LED substrates to many different materials using Au-Au thermo-compression or AuSn eutectic bonding. Bonders can also be configured to bond multiple substrates simultaneously to maximize throughput and cost effectiveness.
