No abstract

No abstract

No abstract

This paper addresses thermal interface materials for thermal conduction of excess heat for microelectronic applications. Carbon black (30 nm) thixotropic paste based on polyol ethers is comparable to carbon black fluidic paste based on polyethylene glycol (PEG) in its effectiveness as a thermal paste, and in its dependence on pressure history. Prior pressure (up to 0.69 MPa) application is helpful. The optimum carbon black content is 2.4 vol.% for the thixotropic paste. The thermal contact conductance across copper surfaces is 30 ϫ 10 4 and 11 ϫ 10 4 W/m 2 -°C for surface roughness of 0.05 µm and 15 µm, respectively. The volume electrical resistivity is 3 ϫ 10 3 Ω-cm. Boron nitride (BN) (5-11 µm) and graphite (5 µm) thixotropic pastes are less effective than carbon black thixotropic paste by up to 70% and 25%, respectively, in thermal contact conductance, due to low conformability.

The use of 0.6 vol.% single-walled carbon nanotubes in a poly(ethylene glycol)-based dispersion gave a thermal paste that was as effective as solder for improving thermal contacts. A thermal contact conductance of 20 · 10 4 W m -2 K -1 was attained. An excessive amount of nanotubes (e.g. 1.8 vol.%) degraded the performance, because of conformability loss. The nanotubes were more effective than hexagonal boron nitride particles but were less effective than carbon black, which gave a thermal contact conductance of 30 · 10 4 W m -2 K -1 .