Dynamic mechanical properties of the transparent silicone resin for high power LED packaging

Aiming to study dynamic mechanical properties of the transparent silicone resins for LEDs packaging and the effects of dynamic mechanical properties on the reliability of high power LEDs, dynamic mechanical analysis (DMA) has been adopted to study one silicone resin used for packaging high power white light LEDs. The viscoelastic behavior of silicone resin was obtained from multi-frequencies dynamic mechanical temperature spectra measured by dynamic mechanical analysis instrument in compression mode. The order of storage modulus was 10⁶ whether in the glassy state or rubbery state, storage modulus in glassy state was about 50 times more than that in rubber state. Glass transition was found at 40degC and the frequency had increased accompanied by growing of temperature of glass transition. The activation energy of glass transition was also calculated. A master curve of storage modulus was generalized according to time-temperature superposition principle and WLF equation. Furthermore, characteristics of storage modulus, loss factor, glass transition, etc. were used for exploring how to increase the reliability of LEDs and the reasons which led to the failure of LEDs.