Protective device

• US 9,153,401 B2
• Filed: 01/14/2010
• Issued: 10/06/2015
• Est. Priority Date: 01/21/2009
• Status: Active Grant

• Current Assignee: Dexerials Corporation
• Original Assignee: Dexerials Corporation
• Inventors: Kimura, Yuji, Ohashi, Youzo, Asada, Takahiro
• Primary Examiner(s): Vortman, Anatoly
• Application Number:
  US13/145,611
• Publication Number:
  US 20120001720A1
• Time in Patent Office: 2,091 Days
• Field of Search: 337/297, 337/153, 337/182, 337/183, 337/186, 337/187
• US Class Current: 1/1
• CPC Class Codes: H01H 1/5805 Connections to printed circuits for slide switches H01H15/005; for tumbler switches H01H23/006
• CPC Class Codes: H01H 2037/768 characterised by the composition of the fusible material
• CPC Class Codes: H01H 2085/0414 Surface mounted fuses
• CPC Class Codes: H01H 2085/466 with remote controlled forced fusing
• CPC Class Codes: H01H 37/761 with a fusible element forming part of the switched circuit H01H37/767 takes precedence
• CPC Class Codes: H01H 61/02 wherein the thermally-sensitive member is heated indirectly, e.g. resistively, inductively
• CPC Class Codes: H01H 85/046 Fuses formed as printed circuits

Abstract

A protective device for protecting equipment includes an insulation base substrate, a fusible conductor arranged on the insulation base substrate and connected to a power supply path for the equipment so that the fusible conductor is fused off by a preset abnormal current or voltage, an insulation cover mounted on the insulation base substrate to overlie the fusible conductor via a preset spacing, and a flux coated on a surface of the fusible conductor and disposed in the spacing. The fusible conductor is fused off to break a current path when the abnormal voltage is applied to the equipment. The fusible conductor is secured to a conductor layer and to pair electrodes provided on the insulation base substrate via an electrically conductive paste containing a metal component exhibiting wettability with respect to the fusible conductor in the fused state.

Claims

1. A protective device for protecting equipment, the protective device comprising:

an insulation base substrate;

a fusible conductor arranged on the insulation base substrate and connected to a power supply path for the equipment so that the fusible conductor is fused off by a preset abnormal current or voltage;

an insulation cover mounted on the insulation base substrate to overlie the fusible conductor via a preset spacing; and

a flux coated on a surface of the fusible conductor facing the insulation cover and disposed in the spacing,

wherein the fusible conductor is fused off to break a current path when the abnormal voltage is applied to the equipment,

wherein the fusible conductor is secured to a conductor layer and to a pair of electrodes provided on the insulation base substrate via an electrically conductive paste containing a metal component exhibiting wettability with respect to the fusible conductor in the fused state,

wherein a melting temperature of the metal component of the electrically conductive paste is lower than a melting temperature of the fusible conductor, and the electrically conductive paste is spread more outwards on the conductor layer than a rim of the fusible conductor,

wherein the insulation cover includes ribs for holding the flux at a center of an inner surface of the insulation cover,

wherein the ribs for holding the flux are formed integrally with the insulation cover such that the flux is held at the center of the inner surface of the insulation cover and the ribs do not contact the insulation base substrate, and

wherein the flux contacts the fusible conductor only at the surface of the fusible conductor facing the insulation cover.

2. The protective device according to claim 1, wherein the electrically conductive paste is a solder paste that immobilizes the fusible conductor with respect to the conductor layer and the pair of electrodes.

3. The protective device according to claim 2, wherein a flux component remains in the solder paste even after the solder paste has immobilized the fusible conductor on surfaces of the electrodes.

4. The protective device according to claim 1, wherein the electrically conductive paste is spread radially from the rim of the fusible conductor on a surface of the conductor layer.

5. The protective device according to claim 1, wherein the electrically conductive paste is spread radially from the rim of the fusible conductor on surfaces of the electrodes.

6. The protective device according to claim 1, wherein the electrically conductive paste is spread on the surface of the conductor layer from the rim of the fusible conductor towards a rim of the conductor layer.

7. The protective device according to claim 1, wherein the electrically conductive paste is spread on surfaces of the electrodes from the rim of the fusible conductor towards rims of the electrodes.