A method of fabrication is adapted to weld paired metal plates, particularly fuel cell bipolar plates, using a partial vacuum to hold the paired metal plates together during the welding process. Each bipolar plate has a plurality of contact surfaces for joining the paired metal plates. The contact surfaces of a first plate are co-aligned with contact surfaces of a second plate. An outer perimeter and a plurality of reactant gas channels and ports of each plate pair are sealed to form a sealable interior volume. A partial vacuum is drawn in the interior volume to clamp each plate pair together at the contact surfaces and a weld joint is made between at least a plurality of the contact surfaces. Laser welding is preferably used for its ability to fuse the contact surfaces together without perforating the plates and thereby losing the partial vacuum.