Abstract: A composition for a coverlay having superior thermal resistance, flexibility, and electrical properties, as well as a method of producing the coverlay and a method of forming the coverlay on a PCB are provided. The composition for a coverlay according to an embodiment of the invention may include 10.0˜45.0 wt % of polyimide, 0.01˜5.0 wt % of a defoaming agent, 0.01˜5.0 wt % of a leveling agent, 0.01˜5.0 wt % of a dispersing agent, 0.1˜15.0 wt % of modified polyimide, and a remainder of a solvent. Also provided is a method for producing a composition for a coverlay for an FPCB that includes: placing amine and an acid anhydride in a reaction solvent and subjecting to first polymerization; placing an acid anhydride in a separate reaction solvent subjecting to second polymerization; forming a polyamic acid by mixing a product of the first polymerization with a product of the second polymerization; and adding a defoaming agent, a leveling agent, a dispersing agent, and modified polyimide to the polyamic acid.