Flexible circuit board

A flexible circuit board having a package region and a sprocket region located on two opposite side of the package region is provided. The flexible circuit board includes a flexible substrate and a patterned metallic layer. The flexible substrate has a plurality of sprocket holes located in the sprocket region. The patterned metallic layer is disposed on the flexible substrate, and exposes the sprocket holes. The patterned metallic layer includes a plurality of first circuit patterns, a plurality of second circuit patterns and a plurality of third circuit patterns. The first circuit patterns are disposed in the sprocket region and located between the sprocket holes and the package region. The second circuit patterns are disposed in the sprocket region and package region, and intersected with the first circuit patterns to define a plurality of ring-shaped areas. The third circuit patterns are disposed in the sprocket region and located between the two sprocket holes. Each third circuit pattern connects one of the first circuit patterns or the second circuit patterns.