US 7,382,224 B2Granted

Over-current protection device

AssigneePolytronics Technology Corp.

InventorsShau Chew Wang, Fu Hua Chu, Kuo Chang Lo

Life of this patent

Estimating the term…

Loading patent…

Abstract

An over-current protection device comprises two metal foils and a positive temperature coefficient (PTC) material layer. The PTC material layer is sandwiched between the two metal foils and comprises plural crystalline polymers with at least one polymer melting point below 115° C., and a non-oxide electrically conductive ceramic powder. The non-oxide electrically conductive ceramic powder exhibits a certain particle size distribution. The PTC material layer has a resistivity below 0.1 Ω-cm. The initial resistance of the device is below 20 mΩ, and the area of the PTC material layer is below 30 mm2. The over-current protection device exhibits a surface temperature below 100° C. under the trip state of over-current protection.

Claims9

Dependent claims

An over-current protection device, comprising:

two metal foils;
and
a positive temperature coefficient (PTC) material layer sandwiched between the two metal foils, exhibiting a resistivity below 0.1 Ω-cm, and comprising:
a plurality of crystalline polymers, wherein at least one of the crystalline polymer exhibits a melting point below 115° C.;
and
a non-oxide electrically conductive ceramic powder consisting essentially of the particle size from 0.1 μm to 10 μm and having a resistivity below 500 μΩ-cm, and dispersed in the crystalline polymers;
wherein the initial resistance of the over-current protection device is below 20 mΩ, the area of the PTC material layer is below 30 mm2, and the over-current protection device exhibits a surface temperature below 100° C. under the trip state of over-current protection.

4 more elements

Dependencies are inferred from the claim text.