This study presents the 'flip glass substrate' approach for the package of an LED chip. The transparent glass substrate covered with phosphor is employed as the carrier. This LED package scheme and its related processes have three merits: (1) light is allowed to emit in all directions for the LED packaged in a flipped glass substrate, and thus the view angle is increased, (2) the chromaticity coordinate distribution of the glass substrate coated with phosphor could be evaluated before LED chip is packaged. Thus glass substrate with wrong chromaticity coordinates could be reworked in early stage, and the color bin yield is enhanced and (3) the uniformity of angular CCT (correlated color temperature) for the LED packaged in the flip glass coated with phosphor is much better than the commercial LED packaged with random distributed phosphor. In application, the glass substrate for packaging is implemented and tested. Measurements show that the packaging technology provides a wide and symmetry view angle (140 • ± 1.5 • ) for the LED chip. In comparison, 95% of the existing commercial single-chip LED packages have a view angle of less than 125 • . The maximum deviation in angular CCT is 1300 K, whereas the CCT is 2500 K for random-distributed phosphor type LED.
This study presents a "Flip Glass Substrate" LED package design. The transparent glass is employed as the substrate. This LED package architecture and process has two merits, (1) Large view angle: Light is allowed to emit in all directions for the LED packaged in a flip glasssubstrate.(2) Color bin yield enhancement: CIE (The International Commission on Illumination) chromaticity coordinate distribution (CCx, CCy) of glass-substrate coated with phosphor could be evaluated before LED chip package. Thus glass-substrate with wrong chromaticity coordinates could be reworked in early stage (like the concept of known-good-die). Moreover, the advantage of remote phosphor is also achieved for this package architecture. In application, the glass substrate for packaging is implemented and tested. Measurements show the chromaticity relation between unpackaged-LED and packaged-LED is determined as 0.017 in CCx. The view angle of packaged device can reach 142º.
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