SMTA International Conference Proceedings


Author: Shatil Haque et al.
Company: Lumileds Lighting (Malaysia)
Date Published: 9/25/2005   Conference: SMTA International

Abstract: High-power LEDs have found numerous applications into high-volume consumer markets including automotive, signaling, LED television, backlighting and portable electronics. Some of these market segments are specifically targeted by the various legal Pb-free initiatives, demanding Pb-free solutions. Furthermore, continued miniaturization of these consumer electronic components requires thinner package solutions.

To meet these demands, Lumileds Lighting has introduced a high-power, low resistance flipchip LED package called LUXEON Flash - a 100% Pb-free packaging platform. The LUXEON Flash package uses Au stud bumps as interconnects between the LED die and the substrate. Au bumps provide shorter and more thermally conductive paths for the LED heat dissipation compared to solder bumps. Experimental results show that thermal performance is improved compared to a solder-based LED package.

As a result, Au stud bump based interconnects allow higher temperature operation of LEDs compared to conventional solder and epoxy-based LEDs. This paper provides a brief background on the urgency of Pb-free packaging for high-power LEDs and presents the LUXEON Flash package platform. A few manufacturing aspects of high volume stud bumping are also addressed. Experimental results showing superior thermal performance and reliability under high temperature and high current operation of stud bump-based LUXEON Flash are illustrated.

Key words: Au stud bumps, thermosonic bonding, flipchip LED package, surface mount LED package

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