For general illumination, white LEDs are usually formed by two methods in the process structure. The first one uses "blue light technology" to form white light with phosphors; the second is a variety of monochromatic light mixing methods. Both methods have successfully produced white light devices. The first method produces a white light system. The LED GaM chip emits blue light (λp=465 nm), which is packaged with YAG (yttrium aluminum garnet) phosphor. When the phosphor is excited by blue light, it emits yellow light. As a result, blue light and The yellow light mixes to form white light. The second method uses a chip of different color light to be packaged together, and white light is generated by mixing the respective colors of light.