Patent ID: 8933775
Filing Date: 2015-01-13
Classification: H01C

Abstract:
1. A surface mountable over-current protection device, comprising: at least one PTC material layer having opposite first and second surfaces and a resistivity less than 0.2 Ω-cm, the PTC material layer comprising at least one crystalline polymer and at least one conductive filler of a resistivity less than 500μΩ-cm dispersed in the crystalline polymer; a first connecting conductor capable of effectively dissipating heat generated from the PTC material layer; a second connecting conductor capable of effectively dissipating heat generated from the PTC material layer; a first electrode electrically connected to the first surface of the PTC material layer through the first connecting conductor; a second electrode electrically connected to the second surface of the PTC material layer through the second connecting conductor; and at least one insulating layer disposed between the first electrode and the second electrode for electrically isolating the first electrode from the second electrode; wherein the over-current protection device has a heat dissipation factor (A1+A2)/A3 greater than 0.6, A1 is the sum of areas of the first electrode and the second electrode, A2 is the sum of areas of the first connecting conductor and the second connecting conductor, and A3 is the product of an area of the PTC material layer and the number of the PTC material layer; wherein the over-current protection device at 25° C., the value of hold current thereof divided by the product of the area of the PTC material layer and the number of the PTC material layer is greater than 1 A/mm