ELECTRONIC CIRCUIT DEVICE AND MANUFACTURING METHOD THEREOF

PROBLEM TO BE SOLVED: To provide an electronic circuit device which can prevent short-circuit between conductors resulting from electromigration in a multilayer substrate and improve electrical characteristics of an element including a magnetic body, while enabling a reduction in thickness and size, and also to provide a manufacturing method of the electronic circuit device.SOLUTION: An electronic circuit device comprises: a transformer substrate 12 including a first insulating base material 121(2), a first conductor 128(1) provided on the front face of the first insulating base material 121(2), a second conductor 126(1) provided on the rear face of the first insulating base material 121(2), and a second insulating base material 122(1) which is bonded to the rear face of the first insulating base material 121(2) via the second conductor 126(1); a magnetic body provided on the transformer substrate 12; and a resin coating 129 having an insulation property which is provided to extend from the edge face of the first insulating base material 121(2) to the edge face of the second insulating base material 122(1) of the substrate 12.