Board assembly, board, and electronic device

A board comprising:

• a base;
• a signal line group on a first main surface of the base and including a plurality of lined up signal lines or a connection terminal group provided on the first main surface of the base and including a plurality of lined up connection terminals;
• and
• one or more additional signal lines provided on a second main surface of the base and extended across the signal line group or the connection terminal group.

An electronic device comprising:

• a board assembly including:
• a first board including a first signal line group including a plurality of signal lines extended in a first direction and lined up in a direction orthogonal to the first direction, and
• a second board including a second signal line group including a plurality of signal lines extended in a second direction and lined up in a direction orthogonal to the second direction,
• wherein the first board and the second board are fixed such that the signal lines included in the first signal line group and the second signal line group are connected in line, and
• wherein the second board includes an additional signal line separated from the second signal line group in a thickness direction of the second board and extended across a second connection terminal group including a plurality of connection terminals connected to the second signal line group or the first signal line group.