A method for fabricating a lead tab, comprising: supplying a lead tab; forming concavo-convex patterns by emitting laser light onto a predetermined region of the lead tab; coating the concavo-convex patterns with a coating solution; and bonding an insulating film to the concavo-convex patterns coated with the coating solution, wherein the forming of the concavo-convex patterns comprises forming first concavo-convex patterns by emitting first laser light onto a first region in a front surface of the lead tab, and forming second concavo-convex patterns by emitting second laser light having intensity different from that of the first laser light onto a second region in a rear surface of the lead tab, wherein the first and second concavo-convex patterns are formed so that the spacings between the respective concavo-convex patterns adjacent to each other gradually decrease from a central region toward either edge region in a predetermined region of the lead tab, while the depths of the concavo-convex patterns gradually increase from the central region toward either edge region in the predetermined region of the lead tab, an area occupied by the concavo-convex patterns ranges from 10% to 95% of the entire area of the predetermined region of the lead tab, the concavo-convex patterns are formed with a depth ranging from 1% to 80% of the thickness of the lead tab, an area occupied by the first concavo-convex patterns formed on the first region of the front surface of the lead tab is different from an area occupied by the second concavo-convex patterns formed on the second region of the rear surface of the lead tab, the first region in the front surface of the lead tab, in which the first concavo-convex patterns are formed, and the second region in the rear surface of the lead tab, in which the second concavo-convex patterns are formed, partially overlap each other, and the predetermined region of the lead tab is a region to which the insulating film is bonded. supplying a lead tab; forming concavo-convex patterns by emitting laser light onto a predetermined region of the lead tab; coating the concavo-convex patterns with a coating solution; and bonding an insulating film to the concavo-convex patterns coated with the coating solution, wherein the forming of the concavo-convex patterns comprises forming first concavo-convex patterns by emitting first laser light onto a first region in a front surface of the lead tab, and forming second concavo-convex patterns by emitting second laser light having intensity different from that of the first laser light onto a second region in a rear surface of the lead tab, wherein the first and second concavo-convex patterns are formed so that the spacings between the respective concavo-convex patterns adjacent to each other gradually decrease from a central region toward either edge region in a predetermined region of the lead tab, while the depths of the concavo-convex patterns gradually increase from the central region toward either edge region in the predetermined region of the lead tab, an area occupied by the concavo-convex patterns ranges from 10% to 95% of the entire area of the predetermined region of the lead tab, the concavo-convex patterns are formed with a depth ranging from 1% to 80% of the thickness of the lead tab, an area occupied by the first concavo-convex patterns formed on the first region of the front surface of the lead tab is different from an area occupied by the second concavo-convex patterns formed on the second region of the rear surface of the lead tab, the first region in the front surface of the lead tab, in which the first concavo-convex patterns are formed, and the second region in the rear surface of the lead tab, in which the second concavo-convex patterns are formed, partially overlap each other, and the predetermined region of the lead tab is a region to which the insulating film is bonded.