An over-current protection device is disposed on a circuit board and configured to protect a battery. The over-current protection device includes a resistive device, at least one insulation layer and a weld electrode layer. The resistive device exhibits positive temperature coefficient behavior. The insulation layer has a thickness of at least 0.03 mm. The weld electrode layer is configured to weld a strip interconnect member to electrically coupled to the battery, and has a thickness of at least 0.03 mm. The insulation layer and the resistive device are disposed between the weld electrode layer and the circuit board. The circuit board, the resistive device and the weld electrode layer are electrically coupled in series. The association of the resistive device and the weld electrode layer has a thermal mass capable of withstanding welding the strip interconnect member without significant damage to the over-current protection device.