Abstract: A surface-mounting choke coil has a resin coating material with magnetic powder which is filled a space between the upper flange and the lower flange of a drum-type ferrite core, while covering the circumferential of the winding. The resin coating material with magnetic powder has a glass transition temperature Tg of about ?20° C. or lower, more preferably about ?50° C. or lower in a course of transferring from a glass state to a rubber state during changing of shear modulus with respect to temperature as a physical property when hardening, and the thickness of the upper flange of the drum-type ferrite core is about 0.35 mm or less, and a value of a ratio L2/L1 of an outer diameter L2 of the upper flange to a diameter L1 of the winding core of the drum-type ferrite core is about 1.9 or more.

Abstract: A surface-mounting choke coil has a resin coating material with magnetic powder which is filled a space between the upper flange and the lower flange of a drum-type ferrite core, while covering the circumferential of the winding. The resin coating material with magnetic powder has a glass transition temperature Tg of about ?20° C. or lower, more preferably about ?50° C. or lower in a course of transferring from a glass state to a rubber state during changing of shear modulus with respect to temperature as a physical property when hardening, and the thickness of the upper flange of the drum-type ferrite core is about 0.35 mm or less, and a value of a ratio L2/L1 of an outer diameter L2 of the upper flange to a diameter L1 of the winding core of the drum-type ferrite core is about 1.9 or more.

Abstract: A surface-mounting choke coil has a resin coating material with magnetic powder which is filled a space between the upper flange and the lower flange of a drum-type ferrite core, while covering the circumferential of the winding. The resin coating material with magnetic powder has a glass transition temperature Tg of about ?20° C. or lower, more preferably about ?50° C. or lower in a course of transferring from a glass state to a rubber state during changing of shear modulus with respect to temperature as a physical property when hardening, and the thickness of the upper flange of the drum-type ferrite core is about 0.35 mm or less, and a value of a ratio L2/L1 of an outer diameter L2 of the upper flange to a diameter L1 of the winding core of the drum-type ferrite core is about 1.9 or more.

Abstract: A surface-mounting choke coil has a resin coating material with magnetic powder which is filled a space between the upper flange and the lower flange of a drum-type ferrite core, while covering the circumferential of the winding. The resin coating material with magnetic powder has a glass transition temperature Tg of about ?20° C. or lower, more preferably about ?50° C. or lower in a course of transferring from a glass state to a rubber state during changing of shear modulus with respect to temperature as a physical property when hardening, and the thickness of the upper flange of the drum-type ferrite core is about 0.35 mm or less, and a value of a ratio L2/L1 of an outer diameter L2 of the upper flange to a diameter L1 of the winding core of the drum-type ferrite core is about 1.9 or more.

Abstract: A structure of a surface-mount coil is provided which prevents a decrease in the fixing strength between the core and the lead frame of the surface-mount coil when soldering of a surface-mount coil to a mount board. Specifically, the structure of the surface mount coil of the present invention suppresses movement and diffusion of molten solder to lower faces of the core placing portions when soldering the external connection terminals to electrode lands of the mount board. The molten solder is detained on the electrode lands to form sufficient solder fillet on the external connection terminals, resulting in suppression of generation of defects in soldering and prevention of decreases in the fixing strength between the core and the lead frame by preventing heat transfer to the upper surface of the core mount portion of the surface mount coil.