Design And Fabrication Of An Open LED Protecting Device

High-power LEDs offer long life, low power consumption, and low maintenance requirements, which make them increasingly popular for outdoor applications. In view of a single LED with low luminous efficiency, they are often designed to connect in strings. Often the failure of any single LED will take out the entire string. In any case, the failure of an LED string is often a costly maintenance issue in outdoor applications. And these problems above can be solved by using open LED protecting devices.In this thesis, a new kind of open LED protecting devices is proposed to make up the deficiency of the existing technology. Integrating SCR (Silicon Controlled Rectifier), resistor, and diode, the LED protecting device offers bidirectional ESD protection. This device provides a substitute current path so that the array continues to function, even if one of LEDs in the array fails open. This chip composed by this LED protecting device can be packaged separately and connected to LED in parallel for use; also, the chip can be packaged inside LED.The structure of SCR is at the core of this open LED protecting device. The process and constructial parameters have been proposed for the device electrical characteristics.Through the device simulation and experimental results, the connection how the processing and structural parameters affect the electrical characteristics of the device is systematically discussed. A complete manufacture set is developed based on the process optimization. And the test results show that the typical value of start-up voltage is 5.06V (the monitoring current is 0.8mA), the typical value of monitoring current is 36μA (the monitoring voltage is 3.5V), and start-up delay time is 50ns. The anti-static electric capacity is stronger than 10KV, reaching ESD tolerance standard III. After the 50 times of temperature cycles(-65～150℃) and 1000 hours of the necessary long service life test, the electrical parameters of the chip samples are of standards with normal appearance of the die.