Reliability Assessment of 3D-Printed Pot-Core Constant-Flux Inductors

Constant-flux inductors (CFIs) are designed to have more uniform flux distribution in the core for efficient use of magnetic material and higher inductance density. However, they require elaborate winding structures which pose challenges to fabrication by conventional fabrication techniques. Recently, we applied a paste-extrusion 3D printer to fabricate spiral windings with different turn-to-turn widths for a pot-core CFI. The printed windings were sintered at 850°C and then potted in a low-temperature curable magnetic composite to form inductors measured at $5 \text{mm x}\ 5 \text{mm x}\ 2\ \text{mm}$. In this work, reliability of the pot-core CFIs was evaluated by temperature cycling between −40°C and 125°C and storage testing at 125°C. After 1000 temperature cycles and 1000 hours at the storage temperature, the DC winding resistances of the pot-core CFIs had no significant change while the inductances dropped only 4.8% and 2%, respectively.