Fabrication of micro piezoelectric rod array using metallic mold system for mass production

LIGA process was carried out to fabricate the copper mold insert for a micro piezoelectric array. X-ray mask was fabricated using UV lithography and PMMA which is the X-ray photoresist was bonded to the titanium substrate done lapping. The bonded PMMA was exposed to X-ray exposure with the total amount of 4.0 kJ/cm3. Copper was then electroplated above the PMMA. After the post-processing, the copper mold insert with the pattern size 400 μm, the height 924 μm, was fabricated. To replicate the patterned micro rod array, PIM process was used. The entire optimized PIM process corresponding to the previous research was applied. The fabricated copper mold insert was used in injection molding process. The ejection pins were also fabricated using the same LIGA process for metal mold and used to extract the injection-molded specimens. After injection molding, two-step debinding and sintering processes were conducted and finally, micro piezoelectric rod array with a pattern size of 322 μm was fabricated without any defects such as collapse and break. The dimension accuracy was ensured through the SEM image analysis and dilatometry results. The physical and piezoelectric properties of sintered part were measured to confirm the part performance made by PIM process. Results indicated the possibility of using the metal mold for mass production system to produce the micro piezoelectric rod array.