A secondary battery and a method for making the secondary battery, which are capable of preventing separation between a metal plating layer and a flexible printed circuit board, and improving adhering force between a battery pack and the flexible printed circuit board, through a structure of a metal plating layer and protective layer of the flexible printed circuit board. The secondary battery includes an insulation layer with a first and second surface, a first line pattern layer formed on the first surface of the insulation layer, a first protective layer formed on the insulation layer and the first line pattern layer to define a first opening that exposes a portion of the first line pattern layer, and a first metal plating layer formed in the first opening. The first protective layer contacts the first line pattern layer and a side surface of the first metal plating layer.