Evaporation of polytetrafluoroethylene by electron bombardment of the bulk material

Abstract The evaporation of polytetrafluoroethylene (PTFE) from a normal electrongun evaporation source is described and the evaporation mechanism is discussed. It is believed that the PTFE decomposes on heating by electron bombardment and that the monomer so formed repolymerizes on the substrate as a result of bombardment by stray electrons. From infrared spectroscopy and from an analysis of the temperature coefficient of capacitance, it appears that the deposited polymer film is in an amorphous state and that many chain ends occur. Electrical measurements suggest that the dielectric is pinhole free, contains no detectable amount of mobile ions, has a permittivity of about 2.4, a dielectric loss factor tan δ of about 0.004 and a dielectric strength of 2 × 10 6 V cm .

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