The subject matter of this specification generally relates to electronic packages. In some implementations, a lidless electronic package includes a substrate having a surface and a die disposed on the surface of the substrate. The die has an outside perimeter, a bottom surface adjacent to the surface of the substrate, and a top surface. The electronic package includes a stiffener disposed on the surface of the substrate. The stiffener includes a first surface that is a first distance from the surface of the substrate and a second surface disposed between the die and the first surface. The first distance is greater than a distance between the surface of the substrate and the top surface of the die. The second surface is a second distance from the surface of the substrate that is less than the distance between the surface of the substrate and the top surface of the die.