Planar Inductor

A planar transformer, comprising:

• a first planar inductor and a second planar inductor, wherein
• each of said planar inductors has, in the same manner, a plurality of flat coils, a flat coil carry layer which carries said flat coils arrayed in a plane, a first interconnection layer provided on one side of the flat coil carry layer, and a second interconnection layer provided on the other side of the flat coil carry layer, wherein
• a start point of the each flat coil is connected through the first interconnection layer and a end point of the each flat coil is connected through the second interconnection layer, and the flat coils are arrayed so that the turning direction of the adjacent flat coils is different,
• the first interconnection layer and the second interconnection are each made of a solid conductor pattern covering all the arrayed flat coils,
• the first interconnection layer positioned on the surface has an flux-passing hole corresponding to the magnetic pole position of the flat coils,
• a first insulator film layer and a second insulator film layer cover the external surfaces of the first and second interconnection layer, thereby
• a power transmission between said planar inductors using magnetic coupling is conducted by positioning the first planar inductor and the second planar inductor facing each other.