Additive Manufacturing of Magnetic Components for Heterogeneous Integration

In an effort to simplify the process of integrating magnetic components to power electronics circuits, an additive manufacturing (AM) process, or commonly known as 3D-printing, for fabricating magnetic components is studied in this work. A commercial multi-extruder paste-extrusion 3D printer was evaluated for making magnetic components. We developed two material systems for printing magnetic cores: (1) curable powdered iron paste system, and (2) sinterable ferrite system. We used commercial nanosilver paste for the conductive winding. A half piece of constant-flux inductor (CFI) and a planar inductor were fabricated in this study. For the half piece CFI, 3D-printing was used with nanosilver paste and low-temperature curable powdered iron paste. The printed winding was sintered at 250 deg C for 30 minutes firstly and then magnetic paste was printed to cover the sintered winding. The magnetic paste was cured at 230 deg C for one hour without any external pressure to form the structure. Two printed pieces were connected to form the full size CFI. Inductance of the CFI was measured to be about 3.5 µH. The DC resistance of the winding was 59 m. For the planar inductor, 3D printing was used with nanosilver paste and high-temperature sinterable ferrite paste. It was sintered at 920oC for 14 hours without any external pressure to form the structure. The inductance of the planar inductor was measured to be about 792 nH. The DC resistance of the winding was 15 m. Microstructures of the printed inductors were examined by scanning electron microscopy (SEM). Both the winding and core magnetic properties can be improved by adjusting the feed paste formulations and their flow characteristics and fine-tuning the printer parameters.