Insulated wire and preparation method thereof, coil and electronic/electrical device

An insulated wire comprising:

• a conductor;
• and
• an insulating layer arranged at the periphery of the conductor,
• wherein:
• a cross section of the conductor takes a shape of a rectangle, a sunken part is formed in the insulating layer on at least one surface of the conductor, the sunken part extends in a whole length direction of the insulating layer, and a convex part is formed in a left and right sides of the sunken part;
• a distance between a bottommost part of the sunken part and a surface of the conductor is L1, L1 is 50 μm-300 μm, the distance between the bottommost part of the sunken part and a highest point of a convex part is L2, and the the value of (L2+L1)/L1 is 3-7;
• angles between two lateral sides of the sunken part and a bottom of the sunken part are both a, and 150°≥a≥90°;
• an upper wire and a lower wire are adhered to each other, then a channel through which a cooling medium flows is formed in a middle;
• the insulating layer comprises a combination of a thermoplastic resin layer with a bonding layer, and the thermoplastic resin layer is on an outermost side of the insulating layer;
• wherein a material of the bonding layer structurally comprises a polymerization unit as shown in formula 1 below:
• in the formula, R1 and R2 are both aryl;
• and R3 is C2-12 alkyl;
• and a polymerization unit as shown in formula 2 below, the ratio of formula 1 being 5-15%, and x+y is 10-10000;