Many electronic apparatus typically include coil components. Especially for mobile devices, coil components may have a chip form and may be surface-mounted on a circuit substrate included in the mobile devices. As an example of the prior art, Japanese Patent Application Publication No. 2006-324489 disclosed a chip coil including a helical conductor that is embedded in a hardened insulating resin and at least whose one end is coupled to an external electrode. The helical direction of the conductor is arranged in parallel with the surface of a substrate on which the coil is mounted.
As another example, Japanese Patent Application Publication No. 2014-232815 disclosed a coil component including a resin insulator, a coil-shaped inner conductor provided inside the insulator, and an external electrode electrically coupled to the internal conductor. The insulator is made in a cuboid shape with the length L, the width W, and the height H, where L>W≥H. The external electrode includes a conductor provided at each end of a plane perpendicular to the height H direction of the insulator as viewed in the length L direction. The internal conductor has a coil axis that is parallel with the width W direction of the insulator.
In the above-mentioned prior arts, insulators and conductors are alternately layered in the height direction using a photolithography and/or plating technique in order to obtain the coil component.
In recent years, miniaturization of components advances and so too with conductors and their sectional areas included in the components. As to electronic components in which insulator is made of resin, effects of stress applied from the resin to conductor cannot be ignored. For example, when an insulator and a conductor are formed of layers, a contraction stress caused by a hardening process of the insulator may act on a bonded portion between an upper conductive layer and a lower conductive layer, which may result in damage of the conductor. For this reason, miniaturization of conductors has been difficult.