Method for increasing the dielectric strength of isolated base integrated circuits used with variable frequency drives

A heat sink structure increasing the dielectric strength of isolation for power integrated circuits is formed from a common layer on which laterally spaced isolated layers for each individual integrated circuit are mounted. At least the isolated layers are formed of anodized aluminum coated with aluminum oxide on exterior surfaces. The aluminum and aluminum oxide of the isolated layers provide good thermal conduction for heat dissipation while the electric isolation from the common electric potential of the common layer is improved, at least in part, by increasing the distance between the integrated circuits and the common layer. The heat sink structure may be mounted within a weatherproof enclosure with one externally exposed surface for heat dissipation.