Semiconductor packages that mitigate warpage and/or other types or mechanical deformation of package substrates are provided. In some embodiments, a package substrate can include a peripheral conductive region having an assembly of rigid conductive members, such as metal layers, metal interconnects, or a combination thereof. The peripheral conductive region can be integrated into the package substrate during the manufacturing of the package substrate. In some implementations, lithographically defined conductive members can be leveraged to form extended conductive layers that can provide increased stiffness compared to nearly cylindrical conductive vias. Non-peripheral conductive regions also can be integrated into a semiconductor package in order to reduce specific patterns of mechanical deformations and/or to provide other functionality, such as electromagnetic interference (EMI) shielding.