Provided are a printed circuit board (PCB) capable of blocking introduction of impurities during a molding process so as to reduce damage on a semiconductor package, a method of manufacturing the PCB, and a method of manufacturing a semiconductor package by using the PCB. An embodiment includes an apparatus comprising: a substrate body comprising an active area and a dummy area on an outer portion of the active area, the substrate body extending lengthwise in a first direction; a plurality of semiconductor units mounted on the active area; and a barrier formed on the dummy area, wherein the barrier extends in the first direction.