Fluid-jet printer having printhead with integrated heat-sink

A printhead is used to eject printing fluid, such as ink, onto a printing medium. This printhead has an integrated heat-sink used to cool energy dissipation elements which propel the printing fluid from the printhead. The printhead includes an amorphous substrate carrying a structure of plural thin-film layers. Upon the substrate is defined a metallic heat sink layer covering substantially the entire plan-view shape of the substrate, and serving during operation of the printhead to distribute excess heat for dissipation. During manufacturing of the printhead, this thin-film metallic heat sink layer performs the additional function of preventing an element or compound present in the substrate from migrating into the thin-film layers.