Abstract: An ink-jet head unit includes a dielectric substrate; a heating layer formed on the dielectric substrate, the heating layer comprising a resistor for converting electricity into thermal energy; a heat dissipating layer formed on the heating layer for insulation and conduction; a working fluid chamber formed in the heat dissipating layer and corresponding to the top surface of the resistor for working fluid reservoir; a nozzle plate formed on the heat dissipating layer, the nozzle plate being formed with a nozzle; an ink chamber formed in the nozzle plate for holding ink; and a flexible membrane formed between the heat dissipating layer and the nozzle plate to separate the working fluid chamber from the ink chamber. The flexible membrane comprises a polymeric adhesive layer formed on the heat dissipation layer, a barrier metal layer formed on the polymeric adhesive layer, and a protection layer formed on the barrier metal layer.