As the industry demands narrow pitch connectors for the electronic devices, the moldability of small-scale connectors is a great concern for injection molding process because of their small features. The particular defects related are weld lines, black spots, and short shots. Along with these product-level defects, the durability of the machine is also a challenge for quality control purpose. In this study, we introduced some new designs to the injection mold assembly of connectors. Our new mold assembly included gas vent system, limit switch, and modified mold blocks. As a result, we successfully remove weld lines and other defects. We were also able to find out that the new system needs less maintenance cost.