With global energy shortages and environmental pollution, LED displays have a broad application space due to their energy-saving and environmentally friendly characteristics. The application of LED light-emitting products in the lighting field is attracting the attention of the world. Generally speaking, the stability and quality of LED lamps are critical to the heat dissipation of the lamp body. At present, high-brightness LED lamps on the market often use natural heat dissipation, and the effect is not ideal. LED lamps made by LED light sources are composed of LEDs, heat dissipation structures, drivers, and lenses. Therefore, heat dissipation is also an important part. If the LED does not dissipate heat well, its life will be affected.
Thermal management is the main problem in high-brightness LED applications
Because the p-type doping of group III nitrides is limited by the solubility of the Mg acceptor and the higher starting energy of holes, heat is particularly easy to generate in the p-type region, and this heat must pass through the entire structure to be dissipated on the heat sink; The heat dissipation pathways of LED devices are mainly heat conduction and thermal convection; the extremely low thermal conductivity of the Sapphire substrate material increases the thermal resistance of the device, resulting in a serious self-heating effect, which has a devastating effect on the performance and reliability of the device.
The effect of heat on high-brightness LEDs
Heat is concentrated in a small chip, the chip temperature rises, causing uneven distribution of thermal stress, chip luminous efficiency and phosphor lasing efficiency decline; when the temperature exceeds a certain value, the device failure rate increases exponentially. Statistics show that for every 2°C increase in component temperature, reliability decreases by 10%. When multiple LEDs are densely arranged to form a white light illumination system, the problem of heat dissipation becomes more serious. Solving the problem of heat management has become a prerequisite for high-brightness LED applications.
The relationship between chip size and heat dissipation
The most direct way to improve the brightness of a power LED display is to increase the input power, and in order to prevent the saturation of the active layer, the size of the pn junction must be increased accordingly; increasing the input power will inevitably increase the junction temperature and thus the quantum efficiency reduce. The increase of single tube power depends on the ability of the device to derive heat from the pn junction, while maintaining the existing chip material, structure, packaging process, current density on the chip and equivalent heat dissipation conditions, the size of the chip and the junction area are increased separately The temperature will continue to rise.
