SMD LED is the meaning of surface mount light-emitting diodes, SMD chip contribute to the production efficiency, as well as the application of different facilities. Is a solid state semiconductor device that converts electricity directly to light. Its voltage is 1.9-3.2V, red, yellow minimum voltage, the heart of the LED is a semiconductor chip, one end of the wafer attached to a bracket, one end is negative, the other end connected to the positive power supply, so that the entire chip is Epoxy packaging. The semiconductor wafer is made up of two parts, one part is a P-type semiconductor, in which holes are dominant and the other end is an N-type semiconductor, mostly electrons here. However, when the two semiconductors are connected, a P-N junction is formed between them. When a current is applied to the wafer through the wire, the electrons are pushed into the P region, where the electrons recombine with the holes and then emit energy in the form of photons, which is why the LED emits light. The wavelength of light, that is, the color of light, is determined by the material that forms the P-N junction.