Abstract: A transformer includes a bobbin, a primary coil, a secondary coil, and a core assembly. The bobbin has a winding portion. At least one first winding groove and at least one second winding groove are formed on the winding portion. The first winding groove and the second winding groove are separated by a barrier. A notch is formed on the fringe portion of the barrier. The primary coil is wrapped in the first winding groove, and the secondary coil is wrapped in the second winding groove. The notched barrier increases the creepage distance between the primary coil and the secondary coil in meeting the safety standards.

Abstract: A transformer includes a winding frame, a primary coil, an insulating cover, a secondary coil, and a core assembly. The winding frame has a winding portion formed with a first side portion and a second side portion oppositely. A plurality of first pins and second pins are disposed on the first and second side portions, respectively. The primary coil is wrapped around the winding portion of the winding frame and connected to the first pins. The insulating cover is fitted over the primary coil. The secondary coil is wrapped around the insulating cover and connected to the second pins. The core assembly is arranged on the winding frame. A transformer assembling method is also disclosed. The coil wrapping process for the transformer can be expedited and associated cost can be reduced.