Over-current protection device

An over-current protection device, comprising:

• an electrode layer having a top metal layer and a bottom metal layer;
• and
• a heat-sensitive layer contacting the top metal layer and the bottom metal layer, and being laminated therebetween, wherein the heat-sensitive layer exhibits a positive temperature coefficient (PTC) characteristic and comprises:
• a polymer matrix comprising a first fluoropolymer and a second fluoropolymer, wherein:
• the first fluoropolymer has a first volume and a first melt flow index;
• the second fluoropolymer has a second volume and a second melt flow index, wherein the second melt flow index ranges from 0.4 g/10 min to 0.7 g/10 min and is lower than the first melt flow index, and a volume ratio by dividing the second volume by the first volume ranges from 0.4 to 0.6;
• and
• a conductive filler dispersed in the polymer matrix, thereby forming an electrically conductive path in the heat-sensitive layer.