Heat Sinks

Temperature

To maximize the reliability and performance of the LED,it is essential to make a proper thermal management.Exceeding the maximum operating temperature of the LED,the light output and lumen maintenance lower and shortens the life of the lamp.Therefore,it is essential to perform the validation of the temperature of an LED by measuring the temperature for optimum performance.

Usually manufacturers define the maximum operating temperature of a semiconductor LED level (Tj = junction temperature,for its acronym in English).To ensure that this limit is not exceeded,it is necessary temperature measurements.Although the critical temperature to be measured is the junction temperature Tj,the inaccessibility of the point has been the creation of an additional measurement: temperature Tc.

This point measurement independent of temperature Tc is chosen as such because it has a direct relationship with the junction temperature Tj and must not exceed the specified limit.If the measurement of the temperature Tc is below or equal to the specified limit will be attained hours of life and luminous flux determined for an LED.Exceeding the limits for the temperature Tc negatively affect the performance of initial product as well as life. All measurements must be performed by thermocouples installed correctly points Tc.

Thermal Management

Control temperature and significantly affect the quality and life hour LED.To ensure that the LEDs operate at optimal capacity,it is essential to conduct an effective thermal management.

The primary function of thermal management is to extract heat from the LED module and dissipate into the air around it.This can be done through conduction,convection and radiation and the matter is being addressed in the sector in different ways,introducing different levels of success.

It achieves optimal thermal management when the number of interfaces reduces thermal conduction between the LED and heat sink thermal resistance is minimized between these interfaces.Also,you need to pay special attention to the material sink to its surface area,geometry and roughness,as well as managing the flow of air around the LED as a whole.

Figure 1: Heat emitted from a halogen lamp opposite the LED in the case of heat sensitive products.Figure 2: Heat emitted by a halogen lamp in front of the LED if required distance from the product.