Thermal Conductivity of a Polymide Film between 4.2 and 300 K, with and without Alumina Particles as Filler

摘要

The thermal conductivity of several types of a commercial polyimide (specifically, polypyromellitimide: PPMI) film was measured over a range of temperatures from 4.2 to 300 K using an unguarded steady-state parallel-plate apparatus. Specimens were made by stacking multiple layers of film together. Conductive grease was used between layers of film to reduce thermal contact resistance. Two specimens were made from two different types of neat (unadmixed) film with a thickness of 76 micrometers, and three specimens were made from films containing two different amounts of admixed alumina filler and having thicknesses of 25 micrometers or 76 micrometers. The conductivity of PPMI film increases with the amount of alumina filler present. The thermal conductivity of specimens made from film of the same type but of different thickness is independent of film thickness, within the limits of experimental uncertainty. The thermal conductivity of a specimen subjected to a simulated curing process by being held at a temperature of 150 C for ninety minutes was indistinguishable from that of a similar, control specimen not subjected to such treatment.