| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact and high-performance planar coil with a small DC resistance and a high-performance transformer by making a coil conductor large in larger thickness and making each lines constituting the coil conductor small in interval. SOLUTION: A plurality of coil conductor lines 3, 3' and 3" with a thickness of 50 to 400μm are provided on one surface or both surfaces of an insulation substrate 1 with an aspect ratio (H/G) of 1 or more in the cap part, and a planar coil is covered with a metallic plating thin-film layer 2 on its surface as desired. The coil conductor lines 3, 3' and 3" have a mushroom-like cross section, where a width L of a head part thereof is two times or more than that a width 1 of a neck part, 1.5 times or less than a height H of the head part and two times or more than a minimum distance G between the coil conductor lines 3, 3' and 3". The planar coil is stacked in plural number via an insulation film interposed, and the entire body is made tight by a thin ferromagnetic core, to form a planar transformer.
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