Abstract
Although LED has a lot of advantages such as high brightness and energy saving,it still have many problems to be solved. Chip junction temperature is one of the sticking point which relationship with the LED light-emitting characteristics is inseparable. If waste heat is not removed to the outside properly, it will make high power LED junction temperature affect light efficiency and lifetime. In order to improve the result of development in high power LED, a measurement system is needed to prove it. Therefore, to establish the LED thermal resistance measurement system with high reliability, repeatability, reproducibility is one of great importance. In order to get LED thermal resistance strcture,we bulid a LED thermal resistance measurement system which it’s theory is based on transient thermal resistance method(include Trend mode&Average mode). It combine National Instruments apparatus with VB6 program, a T.E.Cooler Test Board with Thermoelectric Cooling Module, which can be controlled in constant temperature by the T.E.C. Controller.And it can use VB6 program to control current supply card giving a current IH for LED.Also we use high-speed voltage capture card to get LED’s forward voltage synchronously.Then we input the forward voltage data into TTRS,Analysis (Transient Thermal Resistance Structure Analysis) software which is developed by our laboratory to build all of LED’s thermal resistance strcture.We measured two LED samples with 1W respectively. In order to measure their K factor and transient junction temperature change, we use three different kind of thermal interfacial material to do the response test and thermal resistance analysis for the LED.After performing the experiment for three times (taking 3 times experiments to confirm repeatability), the results suggested that the average relative error is less than 4% with high repeatability; this could be the basis for LED thermal resistance structure measurement system for the establishment of the LED design improvments.And it provides more important reference information for the selection of LED packaging materials in the future.