Printed wiring board

A printed wiring board comprising:

• a base film;
• a first conductor pattern;
• a protective layer;
• a conductive adhesive layer;
• and
• a conductor film,
• wherein the base film has a first main surface,
• the first conductor pattern is disposed on the first main surface,
• the first conductor pattern includes a signal pattern, a first ground pattern, and a second ground pattern, each of which extends along a first direction in a planar view,
• the signal pattern is disposed between the first ground pattern and the second ground pattern in a second direction orthogonal to the first direction,
• the protective layer is disposed on the first main surface so as to cover the first conductor pattern,
• the protective layer is formed with a plurality of first openings which are configured to penetrate a portion of the protective layer on the first ground pattern along a thickness direction and are arranged in a row along the first direction, and a plurality of second openings which are configured to penetrate a portion of the protective layer on the second ground pattern along the thickness direction and are arranged in a row along the first direction,
• the conductive adhesive layer includes a portion disposed on the protective layer, a portion disposed inside each of the plurality of first openings, and a portion disposed inside each of the plurality of second openings,
• the conductor film is disposed on the conductive adhesive layer, and
• a spacing between two adjacent openings of the plurality of first openings or a spacing between two adjacent openings of the plurality of second openings is equal to or smaller than one half of a wavelength of an electromagnetic wave having a frequency equal to that of a current flowing through the signal pattern.