The role of silica gel silica gel LED High Power-H...

Silica gel on the role of LEDs of the LED High Power silicone process, the the loss of radiative recombination to produce photons in the outward emission, mainly in three aspects: 1, the chip internal structure of the defects, and the absorption of the material; photons in the outgoinginterface due to the refractive index difference caused by the reflection losses; 3, and the angle of incidence greater than the total reflection critical angle total internal reflection losses.       Therefore, a lot of light can not reach all parts of the chip out outside. The chip surface coated with a layer of refractive index is relatively high silicone in between the chip and the air, thus effectively reduce the the loss of photons at the interface to improve the light extraction efficiency. In addition, the role of silica gel also includes mechanical protection on the chip, stress release, and as a light guide structure to enhance heat dissipation to reduce the chip junction temperature and improve the LED performance. In order to improve the reliability of the LED package, the silicone also has a low moisture absorption, low-stress, anti-aging properties. Commonly used potting epoxy and silicone. The study showed that higher silicone refractive index can effectively reduce the loss of photons by the refractive index of physical barriers and improve the external quantum efficiency, but the silica gel performance is influenced by ambient temperature. Increase with increasing temperature silicone internal thermal stress, resulting in lower refractive index of silica gel, thus affecting the efficiency of LED light and the light intensity distribution. However, the performance of silica gel was significantly superior to the epoxy resin has been widely used in LED packaging.