1), the role of the chip: Lamp chip is a major component of materials, is the LED semiconductor material.
2), the composition of the chip: the chip is used gallium phosphide (GaP), aluminum gallium arsenic (GaAlAs) or gallium arsenide (GaAs), GaN GaN) and other materials, its internal structure of single-wizard Electrical.

Figure 1, Figure 2 for the welding is a single polarity (P / N structure) chips, Figure 3, Fig 4 for the two-chip, chip solder pad for the general aluminum pad or cushion. The shape of its welding pad round, square, cross, and so on.

Chip depends on the wavelength of light color (HUE), the common visible broadly classified as: dark red (700 nm), red (640-660 nm), orange (615-635 nm), Amber (600-610 nm) , Yellow (580-595 nm), yellow-green (565-575 nm), pure green (500-540 nm), blue (435-490 nm), purple (380-430 nm).
White and light pink just a mixed effect. The most common by the Blu-ray + + yellow and blue phosphor mixture of red phosphors.