Thermal management is the core issue throughout the entire process of LED light R&D, design, manufacturing and application. Unlike most other thermally-induced light sources (halogen, HID, MH, CFL, etc.), LED does not require extra heat to give light. In principle, LED emits photons directly when electrons and holes compound with each other, therefore, LED is known as a “cold light source”.
When LED is driven by current, 20% of the energy is successfully converted into light and the rest is converted into heat. On the other hand, LED is a temperature-sensitive device, it’s internal structure will be changed when internal temperature exceeds it’s working temperature. Therefore, proper thermal management method is critical of the quality control of LED lights.
Purpose and Methods of LED Light Thermal Management
The final purpose of LED thermal management is to reduce the junction temperature (Tj), therefore extend its lifespan and achieve good performance. The junction temperature can be decreased via following methods:
1. Reduce the thermal resistance in light-emitting diodes (encapsulation technique & material related aspects).
2. Use well designed secondary cooling structure (we will discuss in separate article).
3. Reduce the thermal resistance between LED light source and secondary cooling structure (assembly related aspects).
4. Strict control of rated input current to avoid LED being over driven.
5. Try best to decrease the ambient temperature (Ta) and improve the surrounding air flow.