Design and fabrication of planar inductor using a fully-additive sequential build up method

Abstract: The miniaturization of electronics packaging is an ongoing trend. The manufacturers are increasing the packaging density to accommodate for more complex designs and increase in operating frequencies. The surface mount devices (SMDs) and today's manufacturing processes are starting to become a limiting factor to this miniaturization. The solution to these problems are embedded passives and new fully-additive manufacturing processes. In this work, a planar inductor is fabricated using a fully-additive process called Sequential Build-Up - Covalent Bonded Metallization (SBU-CBM). A new grafting material for the CBM process is tested, but found to be worse than the previously used one when tested on FR4 substrates. The best design of a planar inductor for high inductance and high Q factor is found to be the circular spiral inductor. A planar circular spiral inductor with a feature size of 75 µm is successfully fabricated using the SBU-CBM process.