Transient Current of Polyimide in the Time Range 10-4-101 Sec at Temperatures 180-280°C

The transient electric current is obtained by applying a step voltage of 167 V on Kapton(R) type H-films of 25 and 76 pm thickness. The current consists of two components: one decays fast originating from a dielectric relaxation having approximately a single relaxation time τ; and the other is almost flat due to electric conduction. We find a correlation between the conductivity σ and the relaxation parameters which is close to σ=ε0Δεϒ/τ, where ε εis the permittivity of free space and Δεϒ is the change in relative permittivity, suggesting that the present dielectric relaxation is closely associated with the conduction process. The change in σ with heat treatment time is also discussed.