Printed circuit board (PCB) structures and methods of assembling them are described herein. In some embodiments, a PCB structure may include a first mounting hole; first, second, and third projections radiating from the first mounting hole; and a second mounting hole adjacent to the third projection. The first and second mounting holes located at opposite ends of the third projection. The second mounting hole to cause an electrical coupling of a bottom integrated circuit (IC) module to a connection structure included in a PCB, and the first mounting hole, the first projection, and the second projection to cause positioning of a top IC module above the bottom IC module and electrical coupling of the top IC module to the connection structure.