Warpage of Powder Injection Molded Copper Structure

Abstract

Powder injection molding (PIM) is an advanced manufacturing technology with advantages including shape complexity, high production rate, and high physical/mechanical properties. However, because PIM has many sub-steps, such as mixing, injection molding, debinding, and sintering, the optimization of each process condition is important to avoid defects including warpage, crack, and blister. In this paper, the warpage, one of the most common defects in PIM, is investigated by using thin square copper structures with lengths of 10 mm and thicknesses of 600 and 190 mu m. The warpage of each structure is measured by using a white light interferometric surface profiler. The measured warpage of the structure fabricated by the standard process is 3.771 mu m. When the solvent debinding step is absent, the warpage becomes 8.052 mu m. Additionally, sensitivity analysis determines that the effect of the thermal debinding step's heating rate is dominant to warp the structure. Normalized sensitivities of the debinding heating rates are 0.58 for the structure with a thickness of 600 mu m and 0.63 for the other structure. Finally, how to optimize the processing condition is outlined.