Thus, the changes in resistivity during this phase are dominated by the temperature increase and the drop observed can be attributed to the increase in conductivity of the liquid epoxy, as a result of the higher mobility of migrating charges with increasing temperature. Once the reaction starts – in the second half of this stage – the resistivity increases. This increase is attributed to the effect of cross linking on the viscosity of the thermosetting polymer and the corresponding effect on the mobility of migrating charges which dominates the electrical response of the resin [38].