Development of a “Flip Glass Substrate” LED package technology for color bin yield and view angle enhancement

Abstract

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.

‘Flip glass substrate’ package technology for LED yield and performance enhancement

“…This study extends the concept of 'flip glass substrate' LED package design for white light reported in [12]. The LED chip is packaged inside the transparent glass substrate with phosphor coating, and the chromaticity coordinate distribution of the glass substrate coated with phosphor could be evaluated before the packaging of the LED chip.…”