Microelectronic assemblies, and related devices and methods, are disclosed herein. For example, in some embodiments, a microelectronic assembly may include a package substrate including a dielectric material having a first surface and an opposing second surface, a first photodefinable material on at least a portion of the second surface, and a second photodefinable material on at least a portion of the first photodefinable material, wherein the second photodefinable material has a different material composition than the first photodefinable material.