Novel polycarbonate heat sinks for efficient thermal management

摘要

The LED lighting market is growing annually, however high prices remain a barrier, especially in the incandescent replacement market [1]. Many LED bulbs, such as the A19 (the “classic” light bulb shape), MR16 (Multifaceted Reflector, 16 eights of an inch in diameter), and PAR30 (Parabolic Aluminized Reflector lamp, 30 eights of an inch in diameter) could benefit from the use of plastic materials to reduce assembly costs and weight, as well open up design freedom and part consolidation. However, current plastic solutions in the market can be expensive and have low thermal conductivities. This paper details the use of a novel polycarbonate resin with a high thermal conductivity up to 40 W/m-K. The use of polycarbonate reduces moisture uptake and enhances molding conditions, while bringing the cost efficiencies of metal to plastic conversions. In thermal simulations and actual heat sink fabrications, this novel polycarbonate offers similar or better LED case temperatures than cast aluminum. In terms of durability, temperature cycling and thermal shock cycling shows no signs of cracking or deterioration. This has helped the resin obtain a UL f1 rating for outdoor exposure and water immersion, and it should be noted that the plastic will not corrode like aluminum. The polycarbonate resin can also be powder coated with excellent adhesion. Finally, because polycarbonate is a plastic, designers can mold various features into the plastic that can reduce assembly costs and increase efficiency.