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 is investigated in this work for fabricating magnetic components. A paste-based 3D printer from Hyrel 3D was evaluated for making core and winding of the power magnetics. We developed two material systems for printing magnetic cores: (1) curable powdered iron paste system; and (2) sinterable ferrite system. A commercial metal paste was used for making the 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 degrees C for 30 minutes firstly and then magnetic paste was printed to cover the sintered winding. The magnetic paste was cured at 230 degrees C for one hour to form the structure without extra pressure. Two printed pieces were connected to form the full size CFI. Inductance of the CFI was measured to be about 3.5 mu H. The DC resistance of the winding was 59 m Omega. For the planar inductor, 3D printing was used with nanosilver paste and high-temperature sinterable ferrite paste. It was sintered at 920 degrees C for 14 hours to form the structure without extra pressure. The inductance of the planar inductor was measured to be about 792 nH. The DC resistance of the winding was 15 m Omega. The microstructures of the 3D-printed magnetic components were characterized by Scanning-electron-microscope (SEM). Results indicate that both the winding and core magnetic properties could be improved by adjusting the formulation and flow characteristics of the feed paste, by fine-tuning printer parameters (e.g., motor speed, extrusion rate, and nozzle size), and by updating the curing profile in the post-process.