LED lighting technology status radiating

　　LED with its small size, low power consumption, rich green, durable and light color and other characteristics. Much users of all ages. But now one of the bottlenecks facing the development of LED lighting is the heat, the paper will affect the process of analyzing the lighting of the LED heat problem, to elicit the importance of cooling technology in LED lighting, and the current and future cooling technology to do summary and analysis.

　　1, the main factors affecting the LED heat

　　The main factors affecting the heat has material properties (thermal conductivity), package, packaging material, chip size, chip material, the current density on the chip. In general, LED lamp lighting device is composed of a chip and the circuit board, an external radiator and a driver of four parts. So now there are two thermal design options: one is to reduce the LED devices from electrical energy into heat energy, need to improve the implementation process within the internal quantum efficiency of LED devices, thereby improving the efficiency of the LED light, and then from the inside to solve LED lighting (use) produced during the heat problem; two faces starting from the outside design considerations, by changing the LED lighting devices and packaging material or package, in order to achieve the purpose of reducing the package thermal resistance, and sometimes you need to configure the appropriate heat sink to solve high junction temperature issue, thus achieving prolong the service life of LED devices.

　　2, the existing cooling mode

　　Due to limitations in technology, the current use of external heat sink design or use the method to change the LED lighting devices to solve the heat problem. Cooling LED lighting devices currently there are many, can be divided into package-level cooling mode and lighting level cooling. Package level cooling mode, as the name suggests, it is by optimizing the internal LED packaging structure and materials to achieve the effect of reducing the thermal resistance of the package, the package structure is divided into a silicon substrate flip chip (FCLED) structure, the metal structure of the board and the principle of merit-based selection and paste material substrate material based on material aspects.

　　The lighting level cooling mode mainly refers to the way the heat radiating from the implementation of the package substrate to an external radiator in the transfer process, divided into passive cooling and active cooling, active cooling is driven by means of energy outside the system, the LED chip and devices dissipate heat itself, including the installation of fan forced cooling, liquid cooling, semiconductor refrigeration cooling, ion air cooling and synthetic jet cooling and other; and passive cooling is through the radiator itself, will produce in the course of only LED lighting the heat spread out, to reduce the effect of the junction temperature, there are two kinds of direct natural convection cooling and heat pipe (flat heat pipes, loop heat pipe and fin heat pipe) technology.