LED charm of the new generation of light source in the 21st century (3): epitaxial wafer growth, lamp bead packaging and lighting applications

How do LEDs have these super powers? It hides the incredible creativity of modern technology.

The LED epitaxial wafer is a compound semiconductor thin film material epitaxially grown on a sapphire substrate. The process of producing an LED epitaxial wafer is both scientific and artistic. It is intended to make a multi-layered cake, which is full of fun, and an epitaxial wafer may have ten A few twenty layers, stacking layer by layer, each layer of semiconductor on the top is a very western semiconductor layer, which can only be used in nanometer scale. This technology is very advanced and superb. LED epitaxial wafers, the production of such a cake requires a huge high-grade oven - MOCVD, MOCVD is the key core equipment for semiconductor manufacturing, the superstar of the LED industry, a magical and wonderful device, with MOVCD people can prepare LED The key raw material - epitaxial wafer, LED epitaxial wafer growth equipment, contains a very complex pneumatic system, motor system, control system, only the United States and Germany in the world monopolize this technology, with the booming LED lighting industry in recent years Development, MOCVD equipment is less in short supply in the international market. Once MOCVD equipment is localized, foreign equipment will be big. In the dust-free and anti-static workshop, the sapphire substrate is placed in the MOCVD equipment for several hours, and the LED epitaxial wafer can be grown. After 7-8 hours at high temperature, after chemical reaction. Precipitation occurs, each precipitate is very slow, in the form of atomic layers, one by one, layered on top of the sapphire substrate, each layer is very uniform, the core part of MOCVD is the reaction The cavity undergoes a physicochemical reaction in an environment of about 1000 degrees, and a film is produced on the substrate sheet. After the substrate sheet passes through the process of reflecting the cavity, it becomes a illuminable chip, and the LED epitaxial wafer which has been grown is seen. It’s still a thin piece, but in fact they have undergone tremendous changes. They have grown a variety of metal compounds of different materials, which gives her a magical magic.

The LED epitaxial wafer capable of emitting blue light is generally widely used in the field of illumination because of its high luminous efficiency. A 5 cm diameter epitaxial wafer can be finally fabricated and divided into more than 13,000 LED chiplets, each of which is Can become an independent light source.

How to turn the blue light emitted by the LED chip into the white light needed for daily lighting? According to the principle of three primary colors, after the power is turned on, the LED chip emits blue light, and then the yellow phosphor is excited to emit yellow light. After the two colors of light are mixed, the bright white light that people like is present, in order to enable the LED chip that originally emits blue light to be emitted. The white light needs to be coated with yellow phosphor powder for each LED chip waiting for packaging on a small bracket, and then through a series of complicated packaging processes, the LED chip finally completes a gorgeous transformation and becomes one by one. Beautiful and crystal-clear small lamp beads, with LED lamp beads as the light source, people can produce a variety of LED lighting products as they happen. These small LED lights are installed in the lamps. In the future, they will perform their duties and illuminate every corner of people's lives. But before they officially play their role, they must also undergo strict baptism. It is necessary to test the extremely high temperature and low temperature of LED lamps. The lighting can not work normally in various environments. If it works normally, it can guarantee normal work under normal environment.

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