Optical transmission module

An optical transmission module, comprising:

• an optical module comprising an optical element and a receptacle portion that is a connection portion through which an optical signal output from the optical element is transmitted to other device;
• a circuit board that is electrically connected to the optical module through an electrical connection member that extends from one end of the optical module, the circuit board comprising a control circuit mounted thereon;
• and
• a housing in which the optical module and the circuit board are placed;
• wherein a predetermined surface of the optical module is in contact with a predetermined surface of the housing,
• the optical module is fixed onto the predetermined surface of the housing,
• the receptacle portion are not in contact with the housing,
• the receptacle portion is restricted in position while having a positional degree of freedom at least in a direction perpendicular to an optical axis of light emitted from the optical element,
• the circuit board is fixed to the housing at a position that is a predetermined distance in a direction of the optical axis distant from a position that the optical module is fixed to the housing, and
• the predetermined distance is determined such that a thermal stress to be generated at an electrical connection portion that the circuit board is electrically connected to the optical module when the circuit board thermally expands in the direction of the optical axis is less than a shear yield stress of the electrical connection portion.