The base sheet 410 is formed of the PP film 412 having a low dielectric constant. The base sheet 410 has an internal electrode by removing a part of the internal thin film seed layer 414 and a part of the internal plated layer 416 formed on any one surface of the upper surface and the lower surface thereof. At this time, since the flexible printed circuit board is used as a circuit using a high frequency, the base sheet 410 is preferably formed of the PP film 412 having a low dielectric constant.

The flame retardant sheet 420 is formed of the FR4 film 422 having flame retardancy and a low dielectric constant together with an excellent mechanical strength (hardness). At this time, since the printed circuit board is used as the circuit using a high frequency, the flame retardant sheet 420 is preferable formed on the FR4 film 422 having a high mechanical strength and a low dielectric constant.

As described above, it is possible for the method for manufacturing the flexible printed circuit board and the flexible printed circuit board manufactured thereby to stack the flame retardant sheet having flame retardancy and a low dielectric constant on the upper surface and the lower surface of the laminate laminated by stacking the plurality of base sheets having a low dielectric constant, respectively, thereby minimizing a dielectric loss due to the high frequency signal and preventing a loss of the high frequency signal.

In addition, it is possible for the method for manufacturing the flexible printed circuit board and the flexible printed circuit board manufactured thereby to constitute a circuit by using the thin films such as the polypropylene film and the FR4 film, thereby minimizing the thickness thereof while performing a high speed signal processing.