Highlight The Importance Of LED Heat Dissipation

- Aug 15, 2019-

With the global energy shortage and environmental pollution, LED has a wide application space for its energy saving and environmental protection characteristics. The application of LED lighting products in the field of lighting is attracting the attention of the world. In general, the operation of LED lights is stable, the quality is good, and the heat dissipation of the lamp body itself is very important. The heat dissipation of high-brightness LED lights on the market today often uses natural heat dissipation, and the effect is not ideal. The LED light source is composed of LED, heat dissipation structure, driver and lens. Therefore, heat dissipation is also an important part. If the LED does not dissipate heat well, its life will be affected.


1, thermal management is the main problem in high-brightness LED applications


Since the p-type doping of the group III nitride is limited by the solubility of the Mg acceptor and the higher starting energy of the hole, heat is particularly easily generated in the p-type region, and this heat must be dissipated through the entire structure on the heat sink; The heat dissipation path of LED devices is mainly heat conduction and heat convection; the extremely low thermal conductivity of Sapphire substrate materials leads to an increase in 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.


2, the impact of heat on high-brightness LED


The heat is concentrated in the chip with small size, the temperature of the chip rises, causing the non-uniform distribution of thermal stress, the luminous efficiency of the chip and the lasing efficiency of the fluorescent powder to decrease; when the temperature exceeds a certain value, the device failure rate increases exponentially. Statistics show that for every 2 °C rise in component temperature, reliability is reduced by 10%. When multiple LEDs are densely arranged to form a white light illumination system, the heat dissipation problem is more serious. Addressing thermal management issues has become a prerequisite for high-brightness LED applications.


3, the relationship between chip size and heat dissipation


The most straightforward way to increase the brightness of a power LED is to increase the input power. To prevent saturation of the active layer, the size of the p-n junction must be increased accordingly; increasing the input power necessarily increases the junction temperature, which in turn reduces the quantum efficiency. The increase in single-tube power depends on the ability of the device to derive heat from the pn junction, and to increase the size of the chip separately, while maintaining the current chip material, structure, packaging process, current density on the chip, and equivalent heat dissipation conditions. The temperature will continue to rise.