A light emitting diode (LED) is a self-emitting light source that has a long life span and high luminous efficiency, and that consumes less power. LEDs offer a faster response time, and has a broader operating temperature range, which makes them ideal for lighting or display applications. Flat panel displays (FPDs) are usually manufactured on a 1–2 m² glass substrate, but LEDs are made on a smaller substrate. In the LED manufacturing process, an epi wafer is formed on a several-inch-wide sapphire or GaN substrate and is diced into individual LED chips. Then, the LED chips are inspected, picked up and transferred, and then individually packaged. Each LED chip is typically about 1 mm wide, and a display incorporating these chips can achieve a resolution of up to 100 ppi. However, each LED chip emits light at a different wavelength, so makers must conduct an inspection on all LED chips. Since the LED inspection and transfer process might cause a defect on the surface of an LED chip, LED manufacturing is considered a highly sophisticated process.