Harsh Environment Thermal Technologies for Automotive SSL Lighting Applications

Harsh Environment Thermal Technologies for Automotive SSL Lighting Applications

Life time and performance of semiconductor junctions are affected by their junction temperature. Since in assembled SSL lighting systems including LED chips or packages, the junction point is inaccessible, measuring the temperature of the point, Tj , becomes very critical for a system’s performance. The ideal measurement of junction temperature is to monitor the device temperature as close as possible to the heat source. However, a sensor contributes in heat dissipation and the smaller the temperature measurement scale gets, the less accurate it becomes due to the finite size of the sensor and its inaccessibility to exact points of imagejunction. With most materials, there is a strong correlation between the forward voltage drop of a junction and the temperature of that junction. Thus, it makes it possible to employ the junction itself as a temperature sensor. It is safe to assume linearity for most materials in normal operating environments up to 100 °C. Nonlinearity can be determined experimentally by measuring the voltage at higher and higher ambient temperatures (>75 C), until a deviation from linearity occurs.

CFD model of a typical compact LED automotive lighting system

ARTgroup aims to measure the system thermal performance and predict the junction temperature of automotive LED lighting system. In our automotive thermal Screen Shot 2014-11-02 at 10.59.07validation system an integrated sphere (Luminous Flux Measurement System – 2 m dia.), an IR camera (high resolution microscopic thermal maps), power supplies, multimeters and also high resolution/ high magnification microscope enable us to judge our computational results with experimental studies to investigate the fundementals of LED package resistance and also to optimize the cooling capabilities of designed systems.

Infrared image of the LED automotive slighting system


Integrated sphere measurements for the LED lamp

This project is funded by Turkish Ministry of Science and Technology under SANTEZ program.