Asahi Glass (AGC) has developed quartz lens for deep ultraviolet LEDs. Reportedly, using this product, deep ultraviolet LED-manufacturing processes can be significantly simplified, and capital investment can be reduced. Prototyping will begin from the third quarter of 2018, and mass production is scheduled to begin in 2019.
At present, disinfection of water and air is done mainly using mercury lamps. However, because mercury has adverse effects on the human body and the environment, production of mercury lamps may be greatly limited in the future under the Minamata Convention on Mercury. Deep ultraviolet LEDs have a low impact on the environment and extremely strong disinfectant action, and as such are expected to be the next-generation light source that will replace the mercury lamp. Market size is projected to be 30 billion yen in 2020 (*1).
However, current deep ultraviolet LEDs have some problems. One is about the transparent adhesive joining the lens and the window material. It is expensive and is easily degraded by ultraviolet light. The other problem concerns the current solder for joining the package and window. Clients must have large-scale deoxygenation equipment at the time of hermetic sealing, and ultraviolet LED products have the risk of cracking and air leak because the current solder is so hard that thermal stress due to the difference of CTE between package and window directly attacks the interface of package and window.
To solve these problems, AGC Asahi Glass has developed quartz lens for deep ultraviolet LEDs. This product integrates the quartz window material and the lens with AGC's proprietary technology so that a transparent adhesive is not required. In addition, the "special solder" developed by AGC is already overlaid so that clients can join lens and cavity by simply heating and pressing in the atmosphere, without large-scale deoxygenation equipment. Furthermore, the "special solder" is soft to ease the thermal stress due to the difference of CTE between package and window, so it will not crack or allow air leak. By these means, deep ultraviolet LED-manufacturing processes can be greatly simplified and capital investment can be reduced.