Patent ID: 8648687

Claim:
A symmetric planar transformer comprising a circuit board having a circuit formed on the circuit board; and a mounting hole formed through the circuit board; two first bobbins mounted respectively on opposite side surfaces of the circuit board, and each first bobbin having an inner surface corresponding to the circuit board; a through hole formed through the first bobbin and aligning with the mounting hole of the circuit board; a connecting portion formed on the inner surface of the first bobbin, mounted through the mounting hole of the circuit board, attached securely to the connecting portion of the other first bobbin; and a mounting tube formed on an outer surface of the first bobbin and around the through hole of the first bobbin; two primary windings mounted respectively above and below the outer surfaces of the first bobbins, and each primary winding being a conducting wire, wound around the mounting tube of a corresponding first bobbin in a disc-like form and having two conducting terminals connected electrically to the circuit of the circuit board; two secondary windings disposed respectively between the side surfaces of the circuit board and the first bobbins, mounted around the mounting hole of the circuit board and the connecting portions of the first bobbins, and connected electrically to the circuit of the circuit board; and a magnetic core assembly mounted through the mounting tubes, the through holes and the connecting portions of the first bobbins.