In terms of the package, there is an important factor to affect the LED life is corrosion. In the use of LED lights, the general corrosion caused mainly due to water vapor infiltrated within the packaging material, resulting in lead deterioration, PCB copper corrosion; sometimes movable ions introduced with the water vapor resides in the chip surface, resulting in leakage. In addition, the package poor quality of the devices, encapsulated within a large number of residual bubbles, these residual bubbles would also cause corrosion of the device.
(3) thermal stress failure of led light fittings
The temperature has been an important factor of the LED optical properties, LED failure modes of the research scholars to consider the working environment temperature accelerated stress to the LED accelerated life test. This is because the LED spot lights system thermal resistance of the same premise. The welding point of the package pin temperature, junction temperature will also increase, leading to early failure of LED.
Hsu test samples provided by different vendors LED, the LED samples in the experiment were placed 80、100、120℃, 3.2V voltage drive, and provisions when the optical power of the sample decreased to the stating value of 50%, which is determined to be invalid. High power led light fittings with the accelerated life test temperature and the accelerated and the acceleration time increases and decreases. In the accelerated life test, the LED junction temperature rise will make the epoxy material mutation, thereby increasing the thermal resistance of the system between the chip and package thermal surface degradation, eventually leading to package failure.
(4) electrical overstress failure of led light fittings
If LED tunnel used under the current circumstances or electrostatic impact damage of the chip, the chip will result in open circuit, the formation of electrical overstress failures. For example, GaN is a wide band gap materials, high resistivity. If you use such chips, the induced charge due to static electricity generated in the production process which is not easy to disappear when its accumulated to considerable extent. It can produce very high electrostatic voltage, this voltage exceeds the bearing capacity of the material occurs of the material, it will occurs breakdown phenomena and discharge, and making the device failure.