Method for manufacturing embedded trace substrate

A method for manufacturing an embedded trace substrate, the method comprising:

• preparing a film;
• arranging a first electrode pad and a second electrode pad at a peripheral edge of a first main surface of the film along a first direction so as to be spaced from each other and parallel to each other;
• forming a circuit that includes a thin metal wire disposed on the first main surface and that has a functional portion having an arbitrary pattern, a first wiring portion led out from one end of both ends of the functional portion, a second wiring portion led out from another end of both ends of the functional portion, a first end portion constituting a first positional-deviation absorption region, and a second end portion constituting a second positional-deviation absorption region, the first end portion and the second end portion respectively extending from the first wiring portion and the second wiring portion in a direction away from the functional portion and partly overlapping the first electrode pad and the second electrode pad, respectively, the circuit being formed by embedding, in the first main surface of the film, the functional portion, the first wiring portion, the second wiring portion, and sections of the first end portion and the second end portion not overlapping the first electrode pad and the second electrode pad, using an ultrasonic welding machine;
• and
• electrically connecting the first electrode pad and the second electrode pad with the thin metal wire located on the first electrode pad and the second electrode pad, wherein
• the ultrasonic welding machine includes a horn that melts a contact surface of the film with the thin metal wire by applying ultrasonic vibration and that embeds the thin metal wire into the first main surface of the film, and the thin metal wire to be continuously drawn out from a tip of the horn onto the first main surface of the film through an inside of the horn, and
• the first positional-deviation absorption region and the second positional-deviation absorption region are respectively defined by the first end portion and the second end portion having a bent shape, and have a width for absorbing positional deviation of the first electrode pad and the second electrode pad in the first direction relative to the circuit.