A motherboard for an electronic device comprising a main printed circuit board (PCB) with a through-hole extending between the upper component surface and the lower surface. The motherboard includes a carrier PCB having a top surface and a bottom surface, and at least one component, e.g. an optical device, sensor, or the like, coupled to the top surface. The carrier PCB is mounted in an in an inverted orientation with respect to the main PCB such that the top surface of the carrier PCB faces the upper component surface of the main PCB. The carrier PCB is aligned with the main PCB such that the component is substantially aligned with the through hole of the main PCB and is visible from the lower surface of the PCB.