LED heating problem

With conventional light sources, semiconductor light-emitting diodes (LEDs) will generate heat during work, how much depends on the overall luminous efficiency. Plus the role of electric energy, the radiation of electrons and holes composite occurrence of electroluminescent light near the PN junction radiation needed to reach the outside (air) through the chip (chip) semiconductor media and packaging media. Integrated current injection efficiency of the luminescent quantum efficiency of the chip external light extraction efficiency, and ultimately probably only 30-40% of the input electrical energy into light energy, the remaining 60-70% of the energy of lattice vibrations occur mainly in the non-radiative recombination form of conversion of thermal energy.

LED heat on the life of

In general, the LED lights work stability, the quality is good or bad, and the lamp cooling is essential, the heat of the high brightness LED lamps on the market, often using the natural cooling effect is not satisfactory. LED lamps, LED light source to create LEDs, thermal structure, drives, lens, so the heat is also an important part, if the LED can not be a good heat, it's life will also be affected.

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

     P-type doping of III-nitride limited by the solubility of the Lord and hole higher than that of Mg activation energy and heat are particularly vulnerable in the p-type region, and this heat through the entire structure must be dissipated in the heat sink; LEDthe thermal path of the device is a thermal conduction and convection; Sapphire substrates is extremely low thermal conductivity of the device thermal resistance increase, resulting in severe self-heating effect, have a devastating impact on device performance and reliability.

2, the heat of high-brightness LED

   Heat concentrated in a small size chip, the chip temperature rises, causing non-uniform distribution of heat stress, decline in the luminous efficiency and the lasing efficiency of the phosphor;, the device failure rate increased exponentially when the temperature exceeds a certain value. The statistics show that the component temperature rise of 2 ° C, reliability decreased by 10%. When multiple LEDs are densely packed composition of white light illumination system, the heat dissipation problem is more serious. Solve the problem of thermal management has become a prerequisite for high-brightness LED applications.

3, the chip size and the cooling of relations

    The most direct way to improve the brightness of power LED is to increase the input power is bound to increase the input power in order to prevent saturation of the active layer must increase the size of the pn junction; junction temperature rise and thus make the quantum efficiency. Single-tube power increases depends on the device the ability to export heat from the pn junction to maintain the existing chip material, structure, packaging technology, the current density on the chip the same and equivalent thermal conditions, a separate increase the size of the chip junction area The temperature will rise