Low Thermal-Resistance Silicon-Based Substrate for Light-Emitting Diode Packaging

In this paper, a low thermal-resistance packaging substrate for white light-emitting diodes (LEDs) which used a silicon substrate with cavities and through-silicon vias was designed, fabricated, and tested. The substrate was composed of a silver-layer-coated light-reflection cup and ultrathin silicon-based with micro through-vias filled with copper for electrical interconnection and heat dissipation. The silver reflection layer increased the light output efficiency. Thermal and optical performance comparisons of the three different LED packages with different substrates were conducted. The results showed that the thermal resistance of the silicon-based substrate was reduced by 0.589 and 1.965 K/W compared with a leadframe substrate and a ceramic substrate, respectively. Taking advantage of the light-reflection cup, the light output efficiency of the silicon-based package was increased. The fabrication process for the silicon-based substrate was wafer-level and compatible with existing integrated circuit packaging processes. This feature may offer great potential to achieve low cost in the volume production of this substrate. The proposed LED packaging substrate is expected to find many applications, such as LED automotive headlight, picoprojectors, visible light communication, and so forth.