Optical module, optical transceiver, printed circuit board, and flexible printed circuit board

An optical module, comprising:

• a first circuit board comprising a first signal terminal part and a first ground terminal part, which are formed on a front surface of the first circuit board;
• and
• a second circuit board comprising:
• a second signal terminal part and a second ground terminal part, which are respectively connected to the first signal terminal part and the first ground terminal part in an overlapping manner, and are formed on a back surface of the second circuit board;
• a second dielectric layer;
• a second signal wire formed on a front surface of the second dielectric layer, and electrically connected to the second signal terminal part;
• a second ground conductor layer formed on a back surface of the second dielectric layer so as to include a region opposed to the second signal wire and regions extending toward both sides of the opposed region, the second ground conductor layer being electrically connected to the second ground terminal part;
• and
• a second through ground conductor, which passes through the second dielectric layer from the back surface to the front surface, and is electrically connected to the second ground terminal part,
• wherein the second ground terminal part is formed, in a plan view, in a first region and a second region respectively located on both opposing sides of the second signal terminal part in a first direction, and in a third region prescribed at a location beyond the second signal terminal part in a second direction intersecting the first direction.

An optical transceiver module, comprising:

• a first optical module comprising:
• a first circuit board comprising:
• a first signal terminal part and a first ground terminal part, which are formed on a front surface of the first circuit board;
• a first dielectric layer;
• a first signal wire formed on a front surface of the first dielectric layer, and electrically connected to the first signal terminal part;
• a first ground conductor layer formed on a back surface of the first dielectric layer so as to include a region opposed to the first signal wire and regions extending toward both sides of the opposed region;
• and
• a first through ground conductor, which passes through the first dielectric layer from the back surface to the front surface, and electrically connects the first ground conductor layer and the first ground terminal part to each other;
• and
• a second circuit board comprising a second signal terminal part and a second ground terminal part, which are respectively connected to the first signal terminal part and the first ground terminal part in an overlapping manner, and are formed on a back surface of the second circuit board;
• and
• a second optical module,
• wherein the first ground terminal part is formed, in a plan view, in a first region and a second region respectively located on both opposing sides of the first signal terminal part in a first direction, and in a third region prescribed at a location beyond the first signal terminal part in a second direction intersecting the first direction, and
• wherein one of the first optical module and the second optical module serves as an optical transmitter, and another one of the first optical module and the second optical module serves as an optical receiver.

A printed circuit board, comprising:

• a first signal terminal part and a first ground terminal part, which are formed on a front surface of the printed circuit board, and are respectively connected to a second signal terminal part and a second ground terminal part, which are formed on a back surface of another circuit board, in an overlapping manner;
• a first dielectric layer;
• a first signal wire formed on a front surface of the first dielectric layer, and electrically connected to the first signal terminal part;
• a first ground conductor layer formed on a back surface of the first dielectric layer so as to include a region opposed to the first signal wire and regions extending toward both sides of the opposed region;
• and
• a first through ground conductor, which passes through the first dielectric layer from the back surface to the front surface, and electrically connects the first ground conductor layer and the first ground terminal part to each other,
• wherein the first ground terminal part is formed, in a plan view, in a first region and a second region respectively located on both opposing sides of the first signal terminal part in a first direction, and in a third region, which is prescribed at a location beyond the first signal terminal part in a second direction intersecting the first direction and is located on an opposite side of the first signal wire across the first signal terminal part.

A flexible printed circuit board, comprising:

• a second signal terminal part and a second ground terminal part, which are formed on a back surface of the flexible printed circuit board, and are respectively connected to a first signal terminal part and a first ground terminal part, which are formed on a front surface of another circuit board, in an overlapping manner;
• a second dielectric layer;
• a second signal wire formed on a front surface of the second dielectric layer, and electrically connected to the second signal terminal part;
• a second ground conductor layer formed on a back surface of the second dielectric layer so as to include a region opposed to the second signal wire and regions extending toward both sides of the opposed region, the second ground conductor layer being electrically connected to the second ground terminal part;
• and
• a second through ground conductor, which passes through the second dielectric layer from the back surface to the front surface, and is electrically connected to the second ground terminal part,
• wherein the second ground terminal part is formed, in a plan view, in a first region and a second region respectively located on both opposing sides of the second signal terminal part in a first direction, and in a third region prescribed at a location beyond the second signal terminal part in a second direction intersecting the first direction.