Fabrication of micro-sized piezoelectric structure using powder injection molding with separated mold system

In this research, a powder injection molding process was developed to fabricate a micro-sized piezoelectric structure with high aspect-ratio. The separated mold system was prepared by the X-ray micromachining process. The optimal solids loading was determined to be 52 vol% considering the critical solids loading. To ensure a homogeneous powder-binder mixture, the mixing process was performed three times. For complete filling in micro-powder injection molding, rheological properties of the mixture were evaluated using a capillary rheometer with various shear rates and temperatures. The measured flow index n and activation energy E were values of 0.45 and 20.11 kJ/mol, respectively. Based on the rheological analysis, complete filling into the micro-cavity of the separated mold was achieved at the injection velocity of 140 mm/s. The green part was successfully demolded from the separated mold without showing any slanted or broken structures. For extraction of binders from the green part, optimal debinding conditions were determined based on the thermal decomposition behavior of binders and lead (Pb) loss measured by thermo gravimetric analyzer (TGA). After the sintering process was completed, the high-aspect-ratio piezoelectric microstructures were precisely fabricated.