| 摘要 |
A surface mountable overcurrent protection device includes at least one PTC material layer, first and second connection conductors, a first electrode, a second electrode, and an insulation layer. The PTC material layer has a volume resistivity below 0.2Ω-cm and includes at least one crystalline copolymer and a conductive filler distributed inside. The conductive filler has a resistivity below 500μΩ-cm. The first and second connection conductors efficiently discharges heat generated from the PTC material layer. The first electrode is electrically connected to a first surface of the PTC material layer through the first connection conductor. The second electrode is electrically connected to a second surface of the PTC material layer through the second connection conductor. The insulation layer electrically insulates the first electrode from the second electrode. A heat dissipation factor which is dependent on a ratio of an area the PTC material layer to the whole areas of the electrode and the conductor is larger than 0.6. At 25 degrees centigrade, the value of a holding current divided by the product of the number of the PTC material layers and the area of the PTC material layer is larger than 1A/mm^2. |
