Reliability analysis of LED-based electronic devices

This work presents a methodology for reliability testing of LED portable lamps by a laboratory test. The LED was selected for this test because it is one of the most widely used electronic devices in many electronic appliances used in everyday life. This is a booming technology nowadays. Test known as “overstress life” was selected, in this test, LED's are subject to maximum energy values to determine their reliability degree, i.e. find the life-time of the LED. The applied methodology uses the chi-square distribution, in order to obtain the number of devices to be used and test duration. A supervisory failure electronic circuit was constructed to determine life-time of the LED devices. The circuit is a multiplexer and PIC microcontroller based. Multiplexers increase the inputs in which LED's are recorded, i.e. are part of the circuit that selects the device; the PIC is programmed to determine the life-time in hours and to determine exactly which device failed. This provides a reliability analysis tool that allows performance studies of LED's. This technology could be easily extended to other electronic devices in order to improve their quality