Flexible printed circuit board, COF module, and electronic device comprising the same

A flexible printed circuit board comprising:

• a substrate;
• a circuit pattern disposed on the substrate;
• and a protective layer disposed on the circuit pattern, wherein the circuit pattern includes a first circuit pattern and a second circuit pattern, wherein the first circuit pattern includes a first pad part, a second pad part, and a first wiring part connected to the first pad part and the second pad part, wherein the first wiring part includes a first pattern extending in contact with the second pad part, wherein the first pattern includes a first pattern part and a second pattern part disposed under the protective layer, wherein the first pattern part includes an extension area having a width greater than that of the second pattern part, wherein a maximum width of the first pattern part is greater than a maximum width of the second pad part, wherein the extension area includes a protrusion extending in the width direction of the first wiring part, wherein a width of the protrusion is 50% or less of the minimum interval of the first pattern part.

A flexible printed circuit board comprising:

• a substrate;
• a circuit pattern disposed on the substrate;
• and a protective layer disposed on the circuit pattern, wherein the circuit pattern includes a first circuit pattern and a second circuit pattern, wherein the first circuit pattern includes a first pad part, a second pad part, and a first wiring part connected to the first pad part and the second pad part, wherein the first wiring part includes a first pattern extending in contact with the second pad part, wherein the first pattern includes a first pattern part and a second pattern part disposed under the protective layer, wherein the first pattern part includes an extension area thicker than the second pattern part, wherein the second pad part is exposed to the outside at a first end of the protective layer, wherein the extension area is disposed within 5 mm from the first end.