Experimental study on the replication quality of micro-nano cross-shaped structure arrays in injection molding

As the polymer products with micro-structured surface are widely in application, a better understanding of filling behaviors and quality improvement of micro-nano structures by injection molding is strongly demanded. In this paper, a nickel mold insert containing micro-nano cross-shaped structure array has been fabricated by electron beam lithography and electroforming technology subsequently. Filling behaviors of the polymer melt in the micro-nano cross-shaped structure cavities have been investigated under three molding conditions. These conditions are molding without packing, with insufficient and sufficient packing. Without packing, there existed a great difference of filling behaviors of polymer melt along the flow direction and vertical to the flow direction. Effects of the main processing parameters on the replication quality of molded columns have been discussed. The replication quality of micro-nano cross-shaped structure array is found to be improved with the increase of the mold temperature and the cooling time. Under sufficient packing, polymer melt would first flow into the left areas of micro-nano structures. Otherwise the center regions were first filled with insufficient packing. It is shown that the packing pressure and the packing time have the optimum values in the setting ranges.