A coil device includes a coil portion and a bobbin. The coil portion includes wires connectable to terminals. The bobbin includes a first terminal block and a second terminal block formed on both sides in a winding axis direction of a cylindrical portion for forming the coil portion around the cylindrical portion. A length of the first terminal block in a width direction perpendicular to the winding axis direction is larger than that of the second terminal block in the width direction.

A manufacturing method of an SMD network transformer is provided. The method includes providing a metal material sheet and a plurality of coils. The metal material sheet can include a substrate, metal PINs, and an auxiliary sheet. A left and/or right side end of the metal PINs can be connected with the auxiliary sheet. A cross-section of the metal PINs can be exposed. The coil can include a magnetic ring and a copper wire. The method can include tapping the copper wires on the coils, welding wire ends of the copper wires on the metal PINs to form welding positions, and packaging the welding positions through a glue material. The glue material can form a glue frame. The glue frame can wrap the welding positions. The method can include packaging the coils in the glue frame, cutting the auxiliary sheet, taking down the substrate and the auxiliary sheet, and bending and shaping the metal PINs to form a product.