Carbon Nanotubes for thermal management of Microsystems

Kapitel i bok, 2018

One important function of electronics packaging is to remove the heat generated by the integrated circuits (ICs). Efficient cooling requires both high heat conduction within the package and efficient heat removal from the package. Elevated temperature is damaging to the chip and its package. Material mismatch causes mechanical stress leading to fatigue, creep, and finally failure; interconnects can melt, and electromigration within the IC is speeded up. Efficient heat removal is not always the case. Plastics is a common packaging material as it is electrically insulating and cheap. The thermal conductivity is, however low, about 0.2 W/mK compared to that of metals (aluminum 220 W/mK and copper 400 W/mK). Other important factors are the heat spreading and thermal interface materials. The components are often mounted on a polymer board which is only cooled by air. The heat transfer coefficient is only 5–15 W/m2 K for natural convection and 15–250 W/m2 K for forced convection in gases [1].