To improve heat dissipation of sapphire-based LEDs, we develop a new LED package with a dual heat spreader design. The first heat spreader is a cup-shaped copper sheet, which was directly contacted with sapphire to enhance heat dissipation of the chip itself. The second heat spreader is the die-bonding material of diamond-added AgSnCu solder and a high thermal conductive metal-core printed circuit board (MCPCB), where the conventional dielectric layer was replaced with a thin diamond-like layer. Characterization results demonstrate that the diamond-added composite solder is useful in reducing LED thermal resistance, thus avoiding the thermal accumulation phenomenon. In addition, a LED packaged on the new MCPCB exhibits smaller total thermal resistance and larger light output power
The thermal management of high-power GaN-based light-emitting diodes (LEDs) soldered with Sn-3 wt.%Ag-0.5 wt.%Cu (SAC305) solder and diamondadded SAC305 solder was evaluated. Diamond addition was found to significantly reduce the surface temperature and total thermal resistance of the LEDs, revealing that diamond-added SAC305 solder is a promising die-attach material for high-power LED packaging. Interfacial reactions in the LED solder joints were also investigated. The thin Au wetting layer in the chip's backside metallization was rapidly consumed in the initial stage of reflow, forming an AuSn 4 phase at the interface. Subsequently, the AuSn 4 phase detached from the interface, leading to dewetting of the SAC305 solder from the LED chip. To avoid dewetting, a new backside metallization of LED chips should be developed for SAC305 solder.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.