Can You Easily Improve The Reliability Of High Brightness LEDs?
Apparently, yes. A new low refractive index silicone encapsulating material improves the efficiency of LED light transmission by greatly reducing gas permeability
Shin-Etsu Chemical has developed a new silicone encapsulating material product for applications in packaging materials for HB-LEDs.
The "KER-7000 Series," which is a low refractive index (RI)-type greatly reduces gas permeability.
The company is beginning sample shipments, mainly for applications in LED lighting.
Low gas permeability is one of the important characteristics sought in LED encapsulating material, along with superb photo-thermal stability in withstanding high temperatures and excellent retention of its initial optical transparency throughout the lifetime of the device.
With an encapsulating material that has high gas permeability, gases such as oxygen can easily permeate and cause oxidation and sulphuration to occur. This can lead to degradation in light intensity.
Up to now, Shin-Etsu Chemical has been developing many silicone encapsulating materials that have various characteristics, such as methyl-group material that is superior in heat resistance and phenyl-group material that has a low gas permeability.
The newly developed silicone encapsulating product succeeds in greatly reducing the level of gas permeability by 1/10 while maintaining heat resistance at the same level as that of the methyl-group.
What's more, when compared with the phenyl group, this new product has the same level of gas permeability and much higher resistance to high temperatures. LED packaging materials that apply this product will achieve dramatically improved reliability of LED lighting because of its effectiveness in preventing the degradation of light intensify caused by the corrosion of the peripheral materials.
As this new product has a refractive index of 1.38, which is lower than that of the methyl-group material, and is superior in transparency, it is a particularly attractive encapsulating material for flat-package HBLEDs. There are two types of products in this new series that are formulated based on different hardness properties: "KER-7080 A/B" has a hardness level of (Durometer A) 80, and "KER-7030 A/B" has a hardness level of (Durometer A) 30.
Shin-Etsu Chemical has a group of other diverse silicone encapsulating materials for HBLED applications. Representative products in the "SCR Series" are increasingly being adopted for backlighting applications in mobile phones and notebook PCs, and products in the "ASP Series," which have excellent characteristics with regard to long-term reliability and possess greatly reduced gas permeability, also are being increasingly adopted, mainly for applications in backlighting for LCDs.