Multilayer ceramic coil for wireless power transfer system by photo resist film process

This paper proposes a multilayer ceramic coil for a wireless power transfer system that fabricated by a photo resist film process. The wireless power transfer technology has been focused as power supply of miniaturized communication devices because it is not required the connecting cable, and it is suitable to carry. Moreover, the electromagnetic induction type that is usually used is constructed by only coil structure for receiver. Therefore, it will be possible to conserve space inside the devices. Conventionally, the spiral structure coil is used for the transfer coil. However, the spiral coil is including problems such as a high internal resistance and consumption of large area. Moreover, the coil requires the magnetic material to catch the magnetic flux. Therefore, in this paper, the multilayer ceramic coil for the wireless power transfer system was proposed. The coil was fabricated by the multilayer ceramic technology which is used for miniaturized electric components. This technology has the advantage that it is possible to forming a helical structure and to use a magnetic material. In addition, the coil pattern is formed by the photo resist film process. In the conventional process, deformation of the conductive pattern by screen printing method was problem. The proposed process can be solved this problem because the conductive pattern was held by the resist film. In this paper, the rectangle conductive pattern in the cross-sectional was achieved. Moreover, the cross-sectional area was changed by the thickness of the resist film, and the coil pattern that has the cross-sectional pattern with 0.85 mm × 0.022 mm was achieved. In this pattern, the multilayer ceramic coil that has the internal resistance of 1 ohm was achieved. Therefore, the helical coil structure that has the magnetic core and low internal inductance was realized.