A multi-chip module (MCM) package includes an organic laminate substrate; first and second semiconductor device chips that are mounted to a top side of the substrate and that define a chip gap region between opposing edges of the chips; and a stiffener that is embedded in the bottom side of the substrate. The stiffener extends across a stiffening region, which underlies the chip gap region, and does not protrude beyond a bottom side metallization of the substrate.