Abstract: A flexible printed circuit board includes a base film having an insulating property, and one or more interconnects laminated to at least one surface side of the base film. At least one of the one or more interconnects includes, in a longitudinal direction, a first portion and a second portion that is a portion other than the first portion, an average thickness of the second portion being greater than an average thickness of the first portion. A ratio of the average thickness of the second portion to the average thickness of the first portion is greater than or equal to 1.5 and less than or equal to 50.

Abstract: A flexible printed circuit board includes a base film having an insulating property and a plurality of interconnects laminated to at least one surface side of the base film. The plurality of interconnects includes a first interconnect and a second interconnect in a same plane. An average thickness of the second interconnect being greater than an average thickness of the first interconnect. A ratio of the average thickness of the second interconnect to the average thickness of the first interconnect is greater than or equal to 1.5 and less than or equal to 50. The first interconnect includes a first conductive underlayer and a first plating layer, and the second interconnect includes a second conductive underlayer, a second plating layer, and a third plating layer.

Abstract: A flexible printed circuit board includes a base film having an insulating property, and multiple interconnects laminated to at least one surface side of the base film. The multiple interconnects include a first interconnect and a second interconnect in a same plane. An average thickness of the second interconnect is greater than an average thickness of the first interconnect. A ratio of the average thickness of the second interconnect to the average thickness of the first interconnect is greater than or equal to 1.5 and less than or equal to 50.

Abstract: A flexible printed circuit board includes a base film having an insulating property, and multiple interconnects laminated to at least one surface side of the base film. The multiple interconnects include a first interconnect and a second interconnect in a same plane. An average thickness of the second interconnect is greater than an average thickness of the first interconnect. A ratio of the average thickness of the second interconnect to the average thickness of the first interconnect is greater than or equal to 1.5 and less than or equal to 50.

Abstract: A flexible printed circuit board includes a base film having an insulating property, and one or more interconnects laminated to at least one surface side of the base film. At least one of the one or more interconnects includes, in a longitudinal direction, a first portion and a second portion that is a portion other than the first portion, an average thickness of the second portion being greater than an average thickness of the first portion. A ratio of the average thickness of the second portion to the average thickness of the first portion is greater than or equal to 1.5 and less than or equal to 50.

Abstract: A flexible printed circuit board includes a base film having an insulating property, and multiple interconnects laminated to at least one surface side of the base film. The multiple interconnects include a first interconnect and a second interconnect in a same plane. An average thickness of the second interconnect is greater than an average thickness of the first interconnect. A ratio of the average thickness of the second interconnect to the average thickness of the first interconnect is greater than or equal to 1.5 and less than or equal to 50.

Abstract: A printed wiring board of the present invention includes an insulating substrate layer; a first conductive layer laminated to one surface of the substrate layer; a second conductive layer laminated to another surface of the substrate layer; and a via hole formed along an inner surface of a connection hole that is provided, in a thickness direction, through the substrate layer and the first conductive layer, the via hole electrically coupling the first conductive layer and the second conductive layer. A cross-sectional shape of the connection hole along at least one surface of the substrate layer is an irregular shape.

Abstract: A printed wiring board of the present invention includes an insulating substrate layer; a first conductive layer laminated to one surface of the substrate layer; a second conductive layer laminated to another surface of the substrate layer; and a via hole formed along an inner surface of a connection hole that is provided, in a thickness direction, through the substrate layer and the first conductive layer, the via hole electrically coupling the first conductive layer and the second conductive layer. A cross-sectional shape of the connection hole along at least one surface of the substrate layer is an irregular shape.

Abstract: A method for producing a flexible printed circuit board according to an embodiment of the present invention includes a through-hole formation step of preparing a base material including a base film having insulating properties and flexibility and a pair of metal films stacked on both surface sides of the base film, and forming a through-hole in the metal film on a front surface side of the base material and the base film; a filling step of stacking, by electroplating on a front surface of the base material, stacking a conductive material on a surface of the metal film on the front surface side to form a conductive material layer and to fill the through-hole with the conductive material; and a removal step of removing, by etching the front surface of the base material, a surface layer of the conductive material layer stacked on the surface of the metal film on the front surface side and a surface layer of the conductive material filling the through-hole.

Abstract: A method for producing a flexible printed circuit board according to an embodiment of the present invention includes a through-hole formation step of preparing a base material including a base film having insulating properties and flexibility and a pair of metal films stacked on both surface sides of the base film, and forming a through-hole in the metal film on a front surface side of the base material and the base film; a filling step of stacking, by electroplating on a front surface of the base material, stacking a conductive material on a surface of the metal film on the front surface side to form a conductive material layer and to fill the through-hole with the conductive material; and a removal step of removing, by etching the front surface of the base material, a surface layer of the conductive material layer stacked on the surface of the metal film on the front surface side and a surface layer of the conductive material filling the through-hole.