Abstract: Disclosed is a modularized planar coil in the form of a planar coil layer and comprising a coil main body and two pads extended from both ends of the coil main body. The pads respectively locate at a first position at periphery of an imaginary geometric shape that encloses the coil main body and a second position apart from the first position at peripheral of the geometric shape. Winding assemblies of a plurality of the invented planar coil layers and transformers including the invented coil layers are also disclosed. The invention provides a planar transformer that is easy to prepare and useful in the SMT technology.

Abstract: Disclosed is a planar coil module comprising a first planar coil, a second planar coil and a connection portion to connect the first and second planar coils in series. The first and second coils respectively include an outer loop and an inner loop, connected in series and separated by a first distance, with the inner loops of the first and second planar coils connected by the connection portion. The first and second planar coils are provided in two neighboring planes and are separated by a second distance. The outer loops of the first and second planar coils respectively include an outer terminal away from the inner loop, wherein the outer terminals extend to form a pad. The pad of the first planar coil locates at a first position at peripheral of an imaginary geometric shape that encloses the two planar coils and the pad of the second planar coil locates at a second position apart from the first position at peripheral of the geometric shape.

Abstract: Disclosed is a planar coil module comprising a first planar coil, a second planar coil and a connection portion to connect the first and second planar coils in series. The first and second coils respectively include an outer loop and an inner loop connected in series, with the inner loops of the first and second planar coils being connected by the connection portion. The first and second planar coils are provided in two neighboring planes and are separated by a distance. A planar transformer including the invented planar coil module is also disclosed.