The LED is a new solid-state light source, has been a great deal of attention since its inception. The luminescence mechanism is to rely on the PN junction in the electronic transitions between energy band light. The role of the external electric field, the compound of the radiation of electrons and holes occur electroluminescent, part of the energy into light energy, the radiative recombination generated lattice shock the rest of the energy into heat.
LED Floodlight 80W luminous efficiency of only 20% to 30%, most of the rest of the energy into heat, a lot of heat needs to be distributed out in a timely manner, it will be to make the life of the LED to reduce, or even permanent failure. Therefore, the rapid development of the LED at the same time, people are constantly new technology of LED strip lights heat.
Metal aluminum by virtue of the low density, high thermal conductivity, surface treatment of the advantages of mature technology, has been dominated by the LED lighting market of the host material. With the improvement of safety performance requirements, the electrical conductivity of the aluminum to become a deadly scars, in order to improve the use of LED 200W lighting (hereinafter referred to as LED lamps) security, electrical insulating materials has aroused people's attention.
Electrical insulating materials began to emerge in the plastic of ceramic materials and high thermal conductivity. For thousands of years of human use of ceramic materials, modern technology to prepare the ceramic material with good insulation, high thermal conductivity, infrared radiation rate, and low coefficient of expansion, can become the new materials of the LED lighting. At present, the ceramic material is mainly used for heat sink materials for LED Blue 150W packaging chips, circuit board materials and lighting of radiator materials. Plastic by virtue of the high thermal conductivity, excellent electrical insulation and low-value, high-profile cooling material into the markets at this stage due to high prices, the little application rates. The article focuses on the application of ceramic materials in LED lighting technology.
Heat transfer mechanism of ceramic materials
Ceramics are non-metallic materials, there are no free electrons in the crystal structure, with excellent insulating properties. Its heat transfer is part of the mechanism of phonon thermal conductivity, lattice complete no defects, the phonon mean free path, the greater the higher the thermal conductivity. The theory suggests that the maximum thermal conductivity of the ceramic crystal materials can be as high as 320W/mK.
Is generally believed that many factors affect the thermal conductivity of ceramic materials, the structural defects is the main influencing factors. In the sintering process, the oxygen impurities into the ceramic lattice, along with vacancies, dislocations, reversed-phase domain boundaries and other structural defects, significantly reduces the phonon mean free path, resulting in lower thermal conductivity. Modern ceramic technology by generating the second phase, oxygen fixed on the grain boundaries, reducing the possibility of oxygen impurities into the lattice, greatly reduce the oxygen concentration at the grain boundaries, grain internal oxygen spontaneously spread to the grain boundaries , to reduce the oxygen content of the grains within the matrix, and reduced the number and type of defects, thereby reducing the probability of phonon scattering, and to increase the phonon mean free path. Due to the different preparation techniques, the thermal conductivity of ceramic materials is not the same.
LED 400W light model for GU10 Dimensions 49.5mm × 50mm, fin radiator and lamp holder with 95 ceramic materials, and through the threaded connection.
LED light source, built-in constant current drive power, total power consumption of about 3.55W lamps installed three Handson (Henderson), using the lens with light, the total luminous flux of about 150lm.