Over-current protection device

An over-current protection device, comprising:

• a first metal layer;
• a second metal layer;
• and
• a heat-sensitive layer laminated between the first metal layer and the second metal layer, the heat-sensitive layer exhibiting a positive temperature coefficient (PTC) characteristic and comprising:
• a polymer matrix comprising a polyolefin-based polymer and a fluoropolymer, wherein the fluoropolymer has a melt flow index ranges from 1.9 g/10 min to 30 g/10 min, and the polyolefin-based polymer and the fluoropolymer together form an interpenetrating polymer network (IPN), and wherein the total volume of the heat-sensitive layer is calculated as 100%, and the polyolefin-based polymer accounts for 42% to 51% and the fluoropolymer accounts for 2% to 11% by volume of the heat-sensitive layer;
• and
• a first conductive filler having an electrical resistivity lower than 500 μΩ·cm and dispersed in the polymer matrix, thereby forming an electrically conductive path in the heat-sensitive layer.