| As a new solid electroluminescent source, high-power LED owns many advantages: strong security and reliability, little power consumption, high luminous efficiency, good stability, short response time, color changeability and benefit to the environment, etc., which lead to its development in recent decades. For example, white LED has entered a practical stage and become an alternative to incandescent and fluorescent light sources. However, due to the increasing integration and miniaturization of LED chips, heat flux inside the chip is also increasing, which puts the packaging into the position to meet higher requirements of heat dissipation.In this paper, a new interconnect material--nano-silver paste was used for the LED chip packaging to pursue a better photovoltaic performance, since high heat conductivity of this material can help improve the efficiency of heat dissipation for the LED chip.Adhesive reliability of high-power LED module sintered with nano-silver paste at a low temperature was studied in this paper. Shear fatigue properties and fatigue-life criterion of this connection structure were obtained from loading-control shear fatigue tests. Thermal cycling and hydrothermal aging tests were conducted to simulate real working conditions for LED modules. Thermo-mechanical reliability of nano-silver paste sintered LED modules after different aging time was studied by analyzing their shear strength and section microstructures (cavity ratio).In addition, high power LED modules connected with nano-silver paste, Sn3Ag0.5Cu solder and silver epoxy were also aged under thermal cycling and hydrothermal tests. Photoelectric performances of these LED modules were tested at different aging time, respectively. The results show that LED modules sintered with nano-silver paste had the best photovoltaic performance and stability. |
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