An optical board (100) includes a base layer (1), an optical module (4) assembled to the base layer, and an optical layer (2) attached to the base layer and defining a receiving recess (23). The optical module includes a ferrule (41) received in the receiving recess and defining a number of grooves (4131), and a number of optical circuits (42) positioned in the grooves of the ferrule. The optical circuits extend outside of the ferrule and into the optical layer.