Multiple integrated circuit (IC) devices are connected to a top side metallization surface of a multi IC device carrier. The carrier includes resin based substrate layers and associated wiring line layers. To reduce stain of the resin layers, especially in region(s) within the carrier between the IC devices, a stiffener or stiffeners are applied to the back side metallization (BSM) surface of the IC device carrier. The stiffener(s) reduce the amount of curvature of the IC device carrier and reduce the strain seen by the resin layer(s), thereby mitigating the risk for cracks forming and expanding within the resin layers.