Insertable polymer PTC over-current protection device

An insertable PPTC over-current protection device comprising:

• first and second electrodes, each of which has an outer surface and a peripheral edge;
• a solder material;
• conductive lead pins bonded to said first and second electrodes, respectively, each of said lead pins having a connecting segment extending along and bonded to said outer surface of the respective one of said first and second electrodes through said solder material, and a free segment extending outwardly from said connecting segment beyond said peripheral edge of the respective one of said first and second electrodes;
• and
• a PTC polymer matrix laminated between said first and second electrodes and having two opposite surfaces and a peripheral edge, said opposite surfaces of said PTC polymer matrix being in contact with said first and second electrodes, respectively, said PTC polymer matrix being formed with at least one hole that extends between said opposite surfaces of said PTC polymer matrix, that is spaced apart from and that is surrounded by said peripheral edge of said PTC polymer matrix, and that has an effective volume to accommodate thermal expansion of said PTC polymer matrix when temperature of said PTC polymer matrix is increased.