Signal transmission device and manufacturing method thereof

The invention discloses a signal transmission device and a manufacturing method thereof, the signal transmission device comprises a flexible cable, a first insulating layer, a first conductor layer and a second insulating layer of the flexible cable are stacked in sequence, and a first shielding layer is arranged on the outer side of the first insulating layer and/or the second insulating layer; the first conductor layer comprises a first wire and a first ground wire; a third insulating layer, a second conductor layer and a fourth insulating layer of the flexible circuit board are stacked in sequence, a second shielding layer is arranged on the outer side of the third insulating layer and/or the fourth insulating layer, and the second shielding layer is electrically connected with the first shielding layer; the second conductor layer comprises a second wire and a second ground wire, the second wire is electrically connected with the first wire, and the second ground wire is electrically connected with the fir