A low temperature processable ternary gallium alloy is formulated using an appropriate mixture of liquid gallium metal with nickel and copper powders. The processability of this alloy for room temperature via filling application is demonstrated using a stencil print process. A test vehicle is fabricated using a 0.2 mm thick and 300 mm×300 mm stainless steel (SS) panel with laser-drilled vias. Parylene N is deposited on the SS panel and around the inside via walls in order to electrically isolate via filling material from the body of the SS substrate and also making the SS surface non-conductive. Filled vias were examined for electrical isolation from neighboring vias and for electrical continuity in the thickness direction. Results show that the ternary gallium alloy is a good via filling material and can be applied to vias as small as 0.25 mm. It is believed that this novel alloy can also be used for thin film process on related MCM-L (multichip module-laminate) substrates.