Abstract: The coil component includes a coil, a first core having a first magnetic permeability, and a second core having a second magnetic permeability lower than the first magnetic permeability. The first core and the second core form a magnetic path. The coil forms two or more winding windows. The first core contacts with an entirety of one side line extending in a second direction of each of the winding windows, and protrudes from both ends of one side line of at least one of the winding windows. The second core contacts with three side lines other than the one side line of each of the winding windows. A surface resistance of the first core between two points that are 20 mm away from each other is not less than 5 ? after a high-temperature storage test. A drive frequency of the coil component is not less than 20 kHz.

Abstract: A coil component includes a coil having inner and outer circumferential surfaces, a pair of end surfaces, and a core surrounding at least a part of a periphery of the core. A cross section is where the coil component is cut by a plane, when each of coil sections is divided into eight regions by four straight lines extending along the inner circumferential surface, the outer circumferential surface and the end surfaces. In the cross section, first core members positioned at four corner regions, second core members positioned at an inner side of the inner circumferential surface and an outer side of the outer circumferential surface, and third core members, positioned at outer sides of the end surfaces form the core. At least one of the second and third core members has a magnetic permeability lower than that of the first core member in a zero magnetic field.

Abstract: A reactor comprises a first coil, a second coil and a core. Each of the first coil and the second coil is embedded in the core. The core has an outer core part, an inner core part, an upper core part, a lower core part and a middle core part. The upper core part is positioned above an upper end of a cross-section of the first coil in an up-down direction. The lower core part is positioned below a lower end of a cross-section of a second coil in the up-down direction. The core is made of a first member and a second member. The second member has a relative permeability which is greater than a relative permeability of the first member. Each of the upper core part and the lower core part is made of the second member.

Abstract: A reactor comprises a first coil, a second coil and a core. Each of the first coil and the second coil is embedded in the core. The core has an outer core part, an inner core part, an upper core part, a lower core part and a middle core part. The upper core part is positioned above an upper end of a cross-section of the first coil in an up-down direction. The lower core part is positioned below a lower end of a cross-section of a second coil in the up-down direction. The core is made of a first member and a second member. The second member has a relative permeability which is greater than a relative permeability of the first member. Each of the upper core part and the lower core part is made of the second member.

Abstract: A coil component includes a coil having inner and outer circumferential surfaces, a pair of end surfaces, and a core surrounding at least a part of a periphery of the core. A cross section is where the coil component is cut by a plane, when each of coil sections is divided into eight regions by four straight lines extending along the inner circumferential surface, the outer circumferential surface and the end surfaces. In the cross section, first core members positioned at four corner regions, second core members positioned at an inner side of the inner circumferential surface and an outer side of the outer circumferential surface, and third core members, positioned at outer sides of the end surfaces form the core. At least one of the second and third core members has a magnetic permeability lower than that of the first core member in a zero magnetic field.