LED is the abbreviation of Light Emitting Diode, translated into Chinese as light-emitting diode, is a semiconductor device that can convert electrical energy into light energy. the core part of LED is a chip composed of p-type semiconductor and n-type semiconductor, there is a p-n between the p-type semiconductor and n-type semiconductor.

　　1, LED basic introduction 　　

　　LED is the abbreviation of Light Emitting Diode, translated into Chinese as light-emitting diode, is a semiconductor device that can convert electrical energy into light energy. the core of the LED is composed of p-type semiconductor and n-type semiconductor chip, there is a p-n junction between the p-type semiconductor and n-type semiconductor, when the injection of a few carriers and most carriers compound will be excess energy When the injected minority carriers are compounded with the majority carriers, the excess energy is released in the form of light, thus converting electrical energy into light energy. Different materials of the chip can be issued red, orange, yellow, green, blue, purple and other different colors of light, light-emitting diodes are also named for this. 　　

　　Compared with traditional lighting, LED has obvious advantages in energy saving, and is currently the world's advanced lighting technology. Considered by the industry as one of the great inventions of mankind after Edison invented the incandescent light bulb. 　　

　　LED is a solid-state light-emitting device, does not contain mercury, in the production and use of the rupture will not lead to toxic metal environmental pollution. 　　

　　2, LED applications and their classification 　　

　　In the global energy crisis environment, energy saving, environmental protection, colorful, safe, long life, miniaturization of semiconductor LED lighting has been recognized by the world as the third lighting revolution in the history of human lighting. With the improvement of LED technology, its application areas are expanding and extending, and are widely used in LCD backlighting, general lighting, signal display, signal lights and automotive lamps and other fields. 　

　　3、LED package and its product classification 　

　　LED packaging refers to the process of using epoxy resin or silicone and other materials to encapsulate LED chips and brackets. Specifically, it is the process of arranging, fixing and connecting the LED chip and other constituent elements on the bracket or substrate, leading to terminals, and fixing them by encapsulating the plastic light-transmitting insulator medium to form an overall three-dimensional structure, which provides protection and heat dissipation function for the normal operation of the chip. 　

　　At present, the types of LED devices are mainly direct insert type (Lamp) and surface mount type (SMD), among which, SMD type products have many unique and excellent characteristics compared with Lamp type products, such as: high assembly density, small size and light weight of electronic products, saving materials, energy, equipment, manpower and time. Specifically, they are reflected as follows 　

　　(1) Low defect rate of solder joints, good high frequency characteristics, reducing electromagnetic and radio frequency interference; 　

　　(2) High reliability and high vibration resistance; 　

　　(3) easy to achieve automation, improve production efficiency and reduce costs by up to 30%50%; 　

　　(4) The volume and weight of SMD components are only about 1/10 of traditional cartridge components, generally after the adoption of SMT, the volume of electronic products is reduced by 40%60%, and the weight is reduced by 60%80%. 　　

　　At present, SMD LEDs are mainly used in backlighting, lighting and other fields. 　

　　From the packaging form, SMD LED products include Chip, Sideview and high power products, among which Sideview and high power products are mainly white light and high brightness, mainly used in backlighting (e.g., cell phone, computer, etc.) and lighting (e.g., indoor lighting, outdoor lighting, etc.), therefore, the specific products of SMD package are usually Sideview products and high-power products, specifically white light, high brightness products. The domestic direct plug-in device market has been basically saturated, profits are declining year by year; SMD low-end device competition has become increasingly white, SMD device production capacity in the gradual release stage, product price changes. 　

　　4、LED by luminous color classification and its application 　

　　LED belongs to the category of semiconductor optoelectronic devices, according to the light color is divided into monochromatic LED, full-color LED and white LED. among them, white LED is mainly used in the backlight and lighting field, more widely used. With the improvement of luminous efficiency of white LED, semiconductor lighting has been widely used in cell phones, backlighting, special lighting and other fields, is advancing to the field of general lighting.