At this time, since the flexible printed circuit board is used as a circuit using a high frequency, the bonding sheet 220 has a low dielectric constant and is preferably formed of the PE film having the melting temperature relatively lower than the melting temperature of the PP film 212 used as the base sheet 210.

Referring to FIG. 12, the flexible printed circuit board may also be configured by stacking a plurality of base sheets 210 thereon, and stacking the heat resistant sheets 230 on the upper surface of the base sheet 210 disposed on the uppermost portion thereof and the lower surface of the base sheet 210 disposed on the lowermost portion thereof. At this time, the flexible printed circuit hoard is configured by stacking the plurality of base sheets 210 and the heat resistant sheets 230 with the bonding sheet 220 interposed between the base sheet 210 and another base sheet 210, and the base sheet 210 and the heat resistant sheets 230.

Herein, the heat resistant sheet 230 (i.e., the PI film 232) has the highest dielectric constant and heat resistance, and the base sheet 210 (i.e., the PP film 212) has the lowest dielectric constant and has the heat resistance higher than that of the bonding sheet 220 (i.e., the PE film). The bonding sheet 220 has a dielectric constant lower than that of the heat resistant sheet 230 and higher than that of the base sheet 210 and has the lowest heat resistance.