Abstract
The concept of "Flip Glass Substrate" LED package design for white light has been reported in [1]. For emitting-intensity improvement or view-angle adjustment of the packaged LED, this study further presents the designs, such as surface-patterning and surface-trenching, on flip-glass. Measurements on the package LED demonstrate: (1) the surface-patterning of flip-glass reduce refraction at the surface, causing an increase of light emission intensity. It leads 3.8% emitting-intensity improvement in blue-light and 6.8% in white-light at chromaticity x=0.29, (2) the edge-trench of flip-glass (Fig.1e) provides tilt sidewalls to reduce internal refraction. It leads 5.5% emitting-intensity improvement in blue-light and 7.3% in white-light at chromaticity x=0.29, and (3) the central-trench of flip-glass (Fig.1f) can improve the view-angle of LED. Measurements indicate the view-angle is increased from 120° to 160° in blue-light and from 120° to 150° in white-light, however, the emitting-intensity decreases 2.7% for blue-light and 8.2% for white-light at chromaticity x=0.29. In summary, this study reports simple flip-glass surface machining approach to adjust the performances of LED for different applications. © 2012 IEEE.