Multilayered Spiral Coils with Air Core fabricated in LTCC technology

This paper presents a new kind of three-dimensional coil that uses a multilayered structure of low-temperature co-fired ceramic (LTCC) to increase the number of windings per length ratio as well as inductance and quality factor of the coil. Standard fabrication of LTCC materials only allows treatment of each layer separately, considering every layer as a two-dimensional structure, so the fabrication of the classical solenoid form is unachievable. In this configuration, each layer is designed as an Archimedean spiral on one LTCC tape and stacked in such a way that two neighboring layers are facing in opposite directions. Because of stepwise increment of the coil windings homogeneity of magnetic field within the coil is significantly deteriorated. Multiple types of coil regarding their size, number of windings, number of layers and track width were tested. Following paper presents mathematical basis for the coil design, fabrication details and characterization outputs.