EFFECT OF THERMAL INTERFACE MATERIALS FOR HIGH-POWER LED LIGHTING APPLICATIONS

The thermal effect of thermal interface materials in light emitting diode (LED) lighting applications is investigated. The LEDs are soldered to an Aluminum metal core printed circuit board and joint to an Aluminum 6061-T6 heat sink. Three different thermal interfaces are used between the metal core printed circuit board (MCPCB) and heat sink, namely, dry-contact, thermal compound and thermal pad. Preliminary thermal analyses are performed to predict the temperatures on the LED and review the design accordingly. Thermal tests are also performed. The modules are mounted on a lighting system and temperature readings of the LEDs are recorded. The results indicates that the thermal compound leads to the lowest temperature increase in the LED. This is due to the fact that compounds can easily be used in desired thicknesses, generally only filling the voids between two surfaces. Although the current MCPCB and heat sink design enables the LEDs to operate safely with all three thermal interfaces, operating the LEDs at high temperatures dramatically decreases the operational lifetime. Considering its better thermal performance and ease of application, the thermal compound is recommended as the thermal interface material.