Coil device

A coil device comprising:

• a first magnetic substrate;
• a laminated body disposed on the first magnetic substrate and having insulating layers, coil patterns, and at least one through-hole;
• a magnetic layer covering the upper surface of the laminated body;
• an adhesive layer disposed on the magnetic layer;
• a cavity located at an area between the magnetic layer and the adhesive layer, the area substantially corresponding to the through-hole;
• and
• a second magnetic substrate disposed on the adhesive layer and bonded to the magnetic layer with the adhesive layer;
• wherein the insulating layers define an insulator and the coil patterns for defining coils are stacked so that the coils are disposed in the insulator, the at least one through-hole is located at substantially the center of the coils and extends from the upper surface of the laminated body to the first magnetic substrate, the magnetic layer has at least one portion extending through the through-hole to contact the first magnetic substrate and has a relative permeability of about 2 to about 7, the adhesive layer is nonmagnetic, and the laminated body is sandwiched between the first and second substrates.