A coil carrier (1) comprising of an U shaped plastic profile has material thickness which fulfills dielectric strength requirements between the primary (2)and secondary winding. The outside applied primary ribbon turns (2) are bridging the gap of the U coil carrier. The inside fixed wound ferrite rod (3) is located close to the bottom of the U profile. The internal volumes at the closed side of the coil carrier (5) are already filled with glue. The remaining volume inside the ignition transformer can later easily been filled with encapsulating material through shown remaining penetration interstices between the primary turns (4) and two openings at the beginning and the end of the long rod ignition transformer (T) when finally being potted together with the ignition circuitry (C) in the housing (H) in one common process step.