Flexible circuit board

A flexible circuit board comprising:

• a flexible substrate having a surface separated into a working area and a nonworking area according to a cutting line;
• a chip disposed on the working area of the surface;
• and
• a patterned circuit layer disposed on the surface and including a plurality of signal transmission wires and a plurality of bypass wires, the plurality of signal transmission wires are electrically connected to the chip and the plurality of bypass wires are not electrically connected to the chip, each of the plurality of bypass wires includes a bypass transmission portion located on the working area and an anti-peeling portion located on the nonworking area, a blank area exists between the anti-peeling portion and the bypass transmission portion and the cutting line is configured to pass through the blank area, wherein a distance from the anti-peeling portion to the cutting line is between 100 um and 400 um,
• wherein each of the plurality signal transmission wires includes a transmission portion, a reduced portion and a test portion, the transmission portion is located on the working area, the test portion is located on the nonworking area, the reduced portion is connected to and located between the transmission portion and the test portion, the cutting line is configured to pass through the reduced portion, and a width of the reduced portion is less than a width of the transmission portion and a width of the test portion,
• wherein the width of the reduced portion is between 8 um and 13 um.