Imaging unit and endoscope apparatus

1. An imaging unit comprising:

a solid state image sensor having an electrode pad and a light-receiving surface and configured to receive light from a longitudinal direction and to perform photoelectric conversion on the received light to generate an electrical signal;

a flexible printed circuit board having an inner lead connected to the electrode pad of the solid state image sensor, a length of the flexible printed circuit board extending in the longitudinal direction from the solid state image sensor in a direction opposite to where the light-receiving surface of the solid state image sensor is provided; and

one or more electronic components mounted on a first surface of the flexible printed circuit board, the first surface being on a side where the solid state image sensor is provided, wherein

the flexible printed circuit board includes a plurality of materials, each layered in a direction perpendicular to the longitudinal direction and in a plane parallel to the first surface, the plurality of materials comprising:

an insulating base material;

a first surface-side wiring layer on the base material on a side of the first surface;

a first surface-side electrical insulating film for insulating the first surface-side wiring layer;

a second surface-side wiring layer on the base material on a side of a second surface opposite to the first surface; and

a second surface-side electrical insulating film for insulating the second surface-side wiring layer, and

wherein the inner lead extends from the first surface-side wiring layer; and

the one or more electronic components are mounted on the first surface of the flexible printed circuit board in the direction perpendicular to the longitudinal direction.

2. The imaging unit according to claim 1 , wherein

the solid state image sensor has a rectangular parallelepiped shape, and

the inner lead is bent from a side of the solid state image sensor along the light-receiving surface.

3. The imaging unit according to claim 1 , wherein

the solid state image sensor includes a notch or an opening for exposing the electrode pad on a side of the flexible printed circuit board, and an oblique electrode to be connected to the electrode pad through the notch or the opening, and

the inner lead is connected to the oblique electrode.

4. The imaging unit according to claim 3 , wherein the inner lead is bent in such a way that the flexible printed circuit board is parallel to an optical axis direction of the solid state image sensor.

5. The imaging unit according to claim 3 , wherein the flexible printed circuit board and the one or more electronic components are housed within a projected area on a surface orthogonal to an optical axis direction of the solid state image sensor.

6. The imaging unit according to claim 1 , wherein a recognition mark for an alignment is formed on the first surface-side wiring layer to perform the alignment for mounting the solid state image sensor and for mounting the one or more electronic components.

7. An endoscope apparatus comprising an insertion unit, at a distal end of which the imaging unit according to claim 1 is provided.

8. The imaging unit according to claim 3 , wherein the solid state image sensor further includes an examination pad formed on a back side of the solid state image sensor, the back side being opposite to a side of the light-receiving surface.