JPH0230135B2 - KAIROSHADANYOSOSHI - Google Patents

Description

[Detailed description of the invention]

The present invention relates to circuit breaking elements, and more particularly to improvements in ultra-small circuit breaking elements used in fuse fusible bodies, fuse resistors, etc. disposed in electrical flow paths of electrical equipment. Conventionally, this type of circuit breaker element has been constructed by directly layering a copper, copper alloy, or other metal resistance film on the surface of an electrically insulating base material such as ceramic by plating or vapor deposition. However, in this case, even if an overcurrent flows through the element and the metal resistance film is melted, the circuit is incompletely interrupted and there is a serious problem of lack of safety. The reason for this is that the metal resistance film formed by plating or vapor deposition is thin and is provided directly on the surface of the electrically insulating base material, and under such conditions In this case, even if the metal film melts due to overcurrent, the interval between melts is extremely short, and there is always residual resistance (when measured with a 500V megger), so the current interruption is incomplete and the circuit is interrupted. It is impossible to completely interrupt the circuit due to fusing, which is an important function of the device, and the relationship between the fusing current value, fusing time, and insulation resistance in this case is shown in Table 1 based on the fusing test. be.

【table】

[Table] As is clear from the table above, in the case of circuit-breaking elements that have a metal resistance film layered directly on the surface of the base material,
It can be seen that the insulation resistance at the time of melting of the metal film is small and the residual resistance is large. In addition, as this type of circuit interrupting element, for example, (1) Japanese Patent Application Laid-open No. 11463/1983, (2) Japanese Patent Publication No. 1983-11463,
41132, (3) Utility Model Publication No. 45-4441, etc. are known, but the method described in the above (1) publication is based on a resistive film formed on an insulating substrate. It is a fuse resistor that has one part thinner than the other part to make it easier to break the circuit.
The methods described in the publications (2) and (3) both deform and cut the metal film by the heat-induced deformation force of the insulating substrate, so the metal film is incompletely cut and there are parts that are not cut. Therefore, there is a problem that a high degree of reliability and safety in circuit interruption are still insufficient. The present invention was completed as a result of various studies aimed at eliminating the above-mentioned drawbacks, and consists of forming a low-melting-point organic insulating material layer on the surface of an electrically insulating base material, and forming a layer of an organic insulating material on the surface of the insulating material layer. A circuit breaking element on which a metal resistance film layer is formed, in which the low melting point organic insulating material layer is fused due to heat generated by the metal resistance film layer due to overcurrent, and the metal in a bridge state is melted through the fusion part. The present invention relates to a circuit breaking element characterized in that a resistive film layer is configured to be fused and separated on both sides. An embodiment of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, reference numeral 1 denotes an ultra-small cylindrical electrically insulating base material made of ceramic, the surface of which is coated with urethane resin. After coating the layer 2 with a low melting point organic insulating material layer 2, a thin metal resistance film layer 3 made of copper is further coated on the surface of the layer 2 by plating or vapor deposition to obtain an ultra-small circuit breaker element. 4, and a conductive cap 6 having lead wires 5 at both ends of the element 4 is fitted and fixed to form an ultra-small fuse. According to the circuit interrupting element configured as described above, the circuit is completely interrupted according to the following steps (see A, B, and C in FIG. 2). (1) First, the metal resistance film layer 3 generates heat due to the flow of an overcurrent, and the temperature gradually rises. (2) When the rising temperature of the metal resistance film layer 3 reaches the melting temperature of the low-melting-point organic insulating material layer 2 below it, the layer starts to melt as shown in Fig. 2A. Produce part a. (3) When the melting of the molten part a of the organic insulating material layer 2 further progresses and the part forms a completely fused part b as shown in FIG.
begins to melt, but at that point the metal resistance coating layer 3 is in the state of a bridge c at the melted portion b. (4) As the temperature further increases and the melting of the metal resistance film layer 3 progresses, the film layer is finally fused at the bridge c and completely separated into both sides, as shown in Figure 2 C. A complete cut-off part d is formed at. As mentioned above, the relationship between the fusing current value, the fusing time, and the insulation resistance of the element shown in the embodiment of the present invention, which is configured to completely interrupt the circuit due to overcurrent, is shown based on the fusing test. -2.

【table】

[Table] As is clear from the above table, in the case of the circuit breaking element shown in the example of the present invention, the insulation resistance is large when the metal film is fused, there is no residual resistance, and the circuit is completely broken. I can see that it is true. Note that the electrically insulating base material, low-melting point organic insulating material, and metal resistance coating material used in the present invention are not limited to the above-mentioned examples, and in addition to these, the following can be used, for example. Electrically insulating base materials; epoxy resins, phenolic resins, polyamide resins, enamel, and other low-melting point organic insulating materials; polyester resins, epoxy resins, and other metal resistance coating materials; various copper alloys such as copper-manganese alloys and copper-nickel alloys, silver, Gold, etc.Furthermore, the coating state of the metal resistance film and the low melting point organic insulating material can be either full coverage or partial coverage as appropriate, and the shape of the base material can be selected as appropriate. , columnar, plate-like, chip-like, cylindrical, etc. As described in detail above, according to the circuit interrupting element according to the present invention, due to the structure in which the low melting point organic insulating material is interposed between the electrically insulating base material and the metal resistance coating material, as described above, Since the metal resistance film layer can be fused at the bridged portion, the fused film layer can be completely separated on both sides to completely interrupt the circuit, and compared to the various types of known fuses mentioned above, , reliability as a circuit breaking element,
This can significantly improve safety and reliability.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view of the main part when applied to a fuse, and FIG.
Figures A, B, and C are explanatory diagrams of the progress of fusing. DESCRIPTION OF SYMBOLS 1...Electrical insulating base material, 2...Low melting point organic insulating material layer, 3...Metal resistance film layer.

Claims (1)

[Claims] 1. A circuit breaking element in which a low melting point organic insulating material layer is formed on the surface of an electrically insulating base material, and a metal resistance film layer is formed on the surface of the insulating material layer, wherein the metal resistance film is caused by an overcurrent. A circuit breaking element characterized in that the low melting point organic insulating material layer is fused by heat generated by the layer, and the metal resistance film layer in a bridge state is fused and separated on both sides via the fused portion.