Embodiments of present invention provide various device assemblies for digital communication. The device assemblies may include a main printed-circuit-board (PCB); and an OSA-on-daughter-board (OODB) directly connected to the main PCB. The OODB has an optical sub-assembly (OSA) wire-bonded onto a daughter PCB. In one embodiment, the daughter PCB includes a flexible printed-circuit (FPC) sheet connecting the OODB directly to the main PCB. In another embodiment, the main PCB includes a FPC sheet connecting the main PCB directly to the OODB. In one embodiment, the connection may be made through an anisotropic conductive film or an anisotropic conductive adhesive.