Photoelectric conversion module

1. A photoelectric conversion module, comprising:

a transmission side photoelectric conversion part for converting an electrical signal into an optical signal;

a first base member on which the transmission side photoelectric conversion part is mounted;

a transmission side circuit board to a back surface of which a part of a top surface of the first base member is fixed such that the transmission side photoelectric conversion part is mounted on a top surface of the transmission side circuit board;

a reception side photoelectric conversion part for converting an optical signal into an electrical signal;

a second base member on which the reception side photoelectric conversion part is mounted;

a reception side circuit board to a back surface of which a part of a top surface of the second base member is fixed such that the reception side photoelectric conversion part is mounted on a top surface of the reception side circuit board; and

a housing,

wherein the transmission side circuit board and the reception side circuit board are placed such that a back surface of the first base member fixed to the transmission side circuit board is opposite to the housing and a back surface of the second base member fixed to the reception side circuit board is opposite to the housing,

wherein the first base member comprises a plate-shaped base portion, a first extension portion integrated with the base portion and having a thickness less than the base portion, a flat back surface, and a top surface including a stepwise portion between the base portion and the first extension portion,

the first base member mounts the transmission side photoelectric conversion part on the top surface thereof, the back surface of the transmission side circuit board being fixed to a top surface of the first extension portion of the first base member,

the second base member comprises a plate-shaped base portion, first extension portion integrated with the base portion and having a thickness less than the base portion, a flat back surface, and a top surface including a stepwise portion between the base portion and the first extension portion, and

the second base member mounts the reception side photoelectric conversion part on the top surface thereof, the back surface of the reception side circuit board being fixed to a top surface of the first extension portion of the second base member.

2. The photoelectric conversion module according to claim 1 , further comprising:

a spacer comprising a support base one surface of which contacts the transmission side circuit board and the other surface of which contacts the reception side circuit board, a first positioning pin that protrudes from the one surface of the support base and is inserted into a positioning hole of the transmission side circuit board and fitted into a positioning hole of the housing, and a second positioning pin that protrudes from the other surface of the support base and is inserted into a positioning hole of the reception side circuit board and fitted into a positioning hole of the housing,

wherein the first base member further comprises a second extension portion that extends from the first extension portion to a position to be sandwiched between the support base of the spacer and the housing, and

wherein the second base member further comprises a second extension portion that extends from the first extension portion to a position to be sandwiched between the support base of the spacer and the housing.

3. The photoelectric conversion module according to claim 1 , wherein the back surface of the first base member contacts the housing via a first heat-dissipating sheet, and

the back surface of the second base member contacts the housing via a second heat-dissipating sheet.

4. The photoelectric conversion module according to claim 2 , wherein the back surface of the first base member contacts the housing via a first heat-dissipating sheet, and

the back surface of the second base member contacts the housing via a second heat-dissipating sheet.