Patent ID: 8478129

Claim:
An optical communication device, comprising: a module board which includes at least an optical module for inputting and/or outputting an optical signal, and a peripheral circuit connected electrically with the optical module; a connector board which includes an electric connector for inputting and/or outputting an electric signal; and a flexible board which adjusts a relative position of the module board and the connector board, and transmits the electric signal among these boards; wherein the optical module is surface mounted on the module board, and the module board is formed of one substrate including a peripheral circuit mount part, having a thickness, which mounts the peripheral circuit, a module mount part which mounts the optical module while being formed in a substrate thickness thinner than the thickness of the peripheral circuit mount part, a first through-hole terminal which path through the peripheral circuit mount part and connects wirings of the flexible board and a terminal of the peripheral circuit, and a second through-hole terminal which path through the module board mount part and connects wirings of the flexible board and a terminal of the optical module, in order that a current loop length of a return current produced between the optical module and the peripheral circuit may become short corresponding to a difference between the thickness of the peripheral circuit mount part substrate thickness of the module mount part.