Fabrication of high-aspect-ratio micro piezoelectric array by powder injection molding

A powder injection molding process to fabricate a high-aspect-ratio piezoelectric microarray was developed. The reverse shaped sacrificial mold insert was developed by X-ray micromachining, and then insert-type injection molding was conducted to fabricate the piezoelectric microarray structure. For the micro-powder injection molding, rheological properties of the powder binder mixture were evaluated and analyzed. The measured flow behavior exponent was 0.44 and the flow activation energy was 83 kJ/mol−1. Based on the analyzed rheological property, injection molding conditions were optimized. The rheological property and the injection molding conditions were crucial to ensure complete filling. Using the optimized conditions, two high-aspect-ratio piezoelectric microarrays were fabricated: (i) 20-μm patterns with 1:5 aspect ratio and (ii) 40-μm patterns with 1:10 aspect ratio.