Study On Reliability Of Nanosilver Low Temperature Sintered COB High Power LED Modules

Along with the increasing demand of high power LED, multi-chip modules have made great progress to an inevitable trend, The impact of junction temperature on LED modules' life is more severely, we need to control the junction temperature while increase the brightness. Obviously, die-attach layer as the first-level packaging has a most significant impact on the thermal performance of high power LED.So we introduce a novel die attach material, nanosilver paste, which can be used for connecting multi-chips on the substrate because of its higher melting temperature and better thermal/electrical conductivity than conventional solders and adhesive films.First, we fabricated high-power LED modules attached by nanosilver and investigated the effects of ambient temperature on their photoelectric properties. We found that as the ambient temperature rises, the forward voltage, output power,efficiency and luminous flux decline and main wavelength red shift occurs. However,the voltage(?V) or the main wavelength(??) changes linearly with the ambient temperature T.Next, we fabricated high-power LED modules attached by three different die-attach materials, and investigated the effects of ambient temperature on their photoelectric properties. The results showed that LED modules attached by nanosilver exhibits the lowest dynamic resistance, the highest luminous flux, luminous efficiency and with the ambient temperature rises, this advantage is more significant.Finally, we studied the effect of ambient temperature and die-attach materials on the aging process of high power LED, and analyzed the aging process, thus established a mathematical model to predicate their life. We found LED modules attached by nanosilver have a better resistance against ambient temperature, further proving that nanosilver paste is a very promising die-attach material in high power multi-chip modules packaging.