Conductive polycarbonate (PC) plastic granules are used in injection molding to produce items such as electronic turnover boxes, electronic pallets, and safety helmets. During injection molding, conductive PC plastic granules may exhibit weld lines. Weld lines are linear marks formed when molten plastic—melted at high temperature—flows into the mold cavity and converges in multiple streams upon encountering holes, inconsistent flow velocity, or interruptions in melt flow filling. Weld lines compromise the mechanical strength of injection-molded parts; the root cause lies primarily in the mold design. Therefore, we can avoid weld line issues by addressing the following four points.