led热学设计 Heat Dissipation Design in LEDs

Heat Dissipation Design in LEDs
When forward current flows through an LED and the LED emits light, most of the energy consumed is converted into light. However, some of the energy is converted into heat, which causes heat to be generated from the p-n junction and the junction itself to heat up. The heat that occurs in the junction is referred to as the junction temperature, and appropriate dissipation of this heat so that the temperature rise is contained during LED use helps to prolong the lifespan of the LED. This document discusses the heat generated by the LED and some of the issues raised in dealing with it.

Maximum Junction Temperature(Tjmax)
At Stanley, the maximum junction temperature is set not merely for the element itself. It also takes into consideration a range of factors including the product lifespan and the reliability of other components such as the encapsulating resin and molding resin. The maximum junction temperature is normally one of the maximum ratings listed for a product, and the product is not guaranteed to operate when used in conditions where that temperature is exceeded. In most cases,such use results in faults and/or extreme shortening of the product lifespan.

LED Structure and Heat Dissipation

Thermal Resistance Circuits

Obtaining the Junction Temperature

Effects on Lifespan

Effects on Optical Characteristics

Effects on Electrical Characteristics

Conduction  Convection  Radiation

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