LED heat dissipation technology was born in 2000. It is […]
LED heat dissipation technology was born in 2000. It is made of semiconductor light-emitting diodes. Its working principle is radiation-composite electroluminescence. It is the most common heat-dissipation method. It uses aluminum heat-dissipating fins as part of the outer casing to increase the heat-dissipation area.
Like traditional light sources, semiconductor light-emitting diodes (LEDs) also generate heat during operation, depending on the overall luminous efficiency. Under the action of external electric energy, the radiation of electrons and holes recombines to produce electroluminescence, and the light radiated near the PN junction needs to pass through the semiconductor medium of the chip itself and the encapsulating medium to reach the outside (air). Comprehensive current injection efficiency, radiation luminescence quantum efficiency, external light extraction efficiency of the chip, etc., finally only 30-40% of the input electrical energy is converted into light energy, and the remaining 60-70% of the energy is mainly caused by non-radiative recombination lattice vibration. Formal conversion of heat.
In general, whether the LED lamp works stably, the quality is good or bad, and the heat dissipation of the lamp body itself is very important. The heat dissipation of the high-brightness LED lamp on the market often uses natural heat dissipation, and the effect is not satisfactory. 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.
The effect of heat on high-brightness LEDs
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.
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. Temperature will keep rising.