Insulated flat conductive wire having high aspect ratio, method for manufacturing same, and coil

An insulated flat conductive wire having a high aspect ratio, comprising:

• a flat conductive wire having an aspect ratio a/b of 12 or more, wherein the aspect ratio is a ratio of a length a of a long side of a rectangular cross-section to a length b of a short side thereof;
• and
• an insulating film which consists of a polyamide-imide resin and coats the flat conductive wire, wherein
• a cross-sectional area of the flat conductive wire is set so that a diameter of a round wire having the same cross-sectional area as the rectangular cross-section of the flat conductive wire becomes 0.5 mm to 4.5 mm,
• the polyamide-imide resin has a number average molecular weight Mn of 2.0×104 to 4.0×104 when converted to standard polystyrene, and
• the insulating film has a film thickness t1 of 10 μm or more at a center portion of the long side of the rectangular cross-section, and the insulating film has a film thickness ratio t1/t2 of 0.80 to 1.35, and wherein the film thickness ratio t1/t2 is a ratio of the film thickness t1 at the center portion of the long side to a film thickness t2 at an edge portion of the long side of the rectangular cross-section.