JP6135895B2 - Circuit protection element - Google Patents

Description

  The present invention relates to a circuit protection element that melts and protects various electronic devices when an overcurrent flows.

  As shown in FIG. 2, this type of conventional circuit protection element includes an insulating substrate 1, a pair of electrodes 2 provided at both ends of the upper surface of the insulating substrate 1, and a central portion of the upper surface of the insulating substrate 1. A base layer 3 made of epoxy resin, an element portion 4 provided on the top surface of the base layer 3 and electrically connected to the pair of top surface electrodes 2, and so as to cover the element portion 4 It was set as the structure provided with the provided insulating layer 5 which consists of resin, and a pair of end surface electrode layer 6 formed in the both end surfaces of the said insulating substrate 1. FIG.

  As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.

Japanese Patent Laid-Open No. 5-225892

  In the configuration of the conventional circuit protection element described above, since the insulating layer 5 is made of resin, an arc generated when the element portion 4 is melted by overcurrent may jump out of the insulating layer 5. This has the problem that the arc may affect the surrounding product.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a circuit protection element that can prevent surrounding products from being affected.

  In order to achieve the above object, the present invention has the following configuration.

The invention described in claims 1 and 2 of the present invention is formed so as to bridge an insulating substrate, a pair of upper surface electrodes provided at both ends of the insulating substrate, and the pair of upper surface electrodes, and An element portion electrically connected to a pair of upper surface electrodes, a base layer provided between the element portion and the insulating substrate, a plurality of trimming grooves formed in the element portion, and the element portion An insulating layer provided so as to cover the insulating layer, and the insulating layer is composed of a mixture of a resin and a plurality of fillers mainly composed of amorphous silica having a hollow interior or a coarse internal density, and the filler The mixing ratio of the filler is 50 to 70% by volume, the filler has a particle size of 5 to 15 μm, and the filler has a particle size smaller than the groove width of the trimming groove. Fusing The metal that constitutes the element part included in the arc generated at the time can be absorbed into the inside of the filler whose main component is hollow or rough and amorphous silica, so that the arc jumps out of the insulating layer. This can prevent the surrounding product from being affected. Furthermore, since the exposed area of the metal absorbed inside the filler can be reduced, a resin can be present between the filler and the metal absorbed, thereby preventing current from flowing again. The effect of ensuring the interruption of the current after the element part is blown is obtained.

The invention described in claim 3 of the present invention, in particular, in the grooves of the plurality of trimming grooves in which were filled with the mixture of resin and filler, according to this configuration, the over in the groove of the trimming groove Since the metal constituting the element part melted by the current can be absorbed into the filler, and the exposed area of the metal absorbed inside the filler can be reduced, the current after the element part is melted can be cut off. The effect that it can be ensured is obtained.

  As described above, in the circuit protection element of the present invention, since the insulating layer is composed of a mixture of a resin and a plurality of fillers whose main components are hollow or rough and amorphous silica, an element with overcurrent The metal composing the element part scattered on the insulating layer side when the part is melted can be absorbed into the inside of the filler whose main component is hollow or rough and amorphous silica, thereby Can be prevented from jumping out of the insulating layer, and the current can be reliably cut off after the element portion is melted.

Sectional drawing of the circuit protection element in one embodiment of this invention Cross-sectional view of a conventional circuit protection element

  Hereinafter, a circuit protection element according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a cross-sectional view of a circuit protection element according to an embodiment of the present invention. As shown in FIG. 1, the circuit protection element according to an embodiment of the present invention includes an insulating substrate 11 and the circuit board. A pair of upper surface electrodes 12 provided at both ends of the upper surface of the insulating substrate 11 and an element portion formed so as to bridge the pair of upper surface electrodes 12 and electrically connected to the pair of upper surface electrodes 12 13, a base layer 14 provided between the element portion 13 and the insulating substrate 11, and an insulating layer 15 provided so as to cover the element portion 13. It is composed of a mixture of a silicon resin and a plurality of fillers mainly composed of silica having a hollow interior or a coarse internal density.

In the above configuration, the insulating substrate 11 has a square shape and is made of alumina containing 55% to 96% of Al ₂ O ₃ . The pair of upper surface electrodes 12 are provided at both ends of the upper surface of the insulating substrate 11 and are formed by printing Ag or the like. The element portion 13 is provided on the upper surface of the base layer 14 and the pair of upper surface electrodes 12 so as to cover the entire surface of the insulating substrate 11, and is constituted by a thin film layer 13a and a plating layer 13b. .

  Further, the thin film layer 13a is formed by sputtering Ti or Cu, and the plating layer 13b is provided on the upper surface of the thin film layer 13a, and the thin film layer 13a is used as a plating nucleus to form Ni, Cu, It is formed by electroless plating of Ag in order.

  Furthermore, an end face electrode layer 16 made of a silver-based material is formed on both ends of the insulating substrate 11 so as to overlap a part of the element portion 13, and the surface of the end face electrode layer 16 is plated. A film (not shown) is formed.

  A plurality of trimming grooves 17 are alternately formed in the central portion of the element portion 13 by laser from the side surfaces of the element portion 13 facing each other toward the central direction of the element portion 13. The region surrounded by the two trimming grooves 17 becomes a fusing portion 18 that melts and breaks when an overcurrent is applied, and the resistance value is adjusted by the trimming groove 17 on the outer side. The width of the trimming groove 17 is 20 to 30 μm.

  The underlayer 14 is provided at the center of the upper surface of the insulating substrate 11, and the underlayer 14 is provided between the element portion 13 located between the pair of upper surface electrodes 12 and the insulating substrate 11. It has been. The underlayer 14 is made of a material having low thermal conductivity such as silicon resin.

  The underlayer 14 is formed not only on the central portion of the insulating substrate 11 but also on almost the entire upper surface of the insulating substrate 11, and a pair of upper surface electrodes 12 are formed on both ends of the upper surface of the underlayer 14. May be.

  The insulating layer 15 is provided so as to cover the element portion 13, and includes a plurality of resins mainly composed of a resin such as silicon and silica having a hollow inside or a coarse inside density. It consists of a mixture of fillers. Furthermore, the surface of the filler is substantially spherical and has numerous irregularities. The mixture of the resin and the filler is also filled in the plurality of trimming grooves 17. As a result, the metal constituting the element portion 13 melted by overcurrent can be absorbed in the filler even in the groove of the trimming groove 17, and the exposed area of the metal absorbed in the filler is reduced. Therefore, the interruption of the current after the element part 13 is melted can be ensured. Furthermore, the particle size of the filler is about 5 to 15 μm, which is smaller than the width of the trimming groove 17, so that the filler can be surely filled into the groove of the trimming groove 17. The interruption of current can be made more reliable.

  In addition, the insulating layer 15 has a filler mixing ratio of 10 to 90% by volume, and the filler mixing ratio is particularly preferably 50 to 70% by volume. Here, if the mixing ratio of the filler is smaller than 10% by volume, it is impossible to absorb all of the metal into the filler, and there is a possibility that a current flows again. On the other hand, if the mixing ratio of the filler is larger than 90% by volume, the viscosity of the insulating layer 15 increases, and pinholes are generated in the insulating layer 15.

  The filler is mainly composed of silica or alumina. Since the silica or alumina is scientifically stable and excellent in heat resistance and fire resistance, an overcurrent flows and the element portion 13 is heated to a high temperature. Even if it becomes, a fusing characteristic can be stabilized.

  The insulating layer 15 may be constituted by a first insulating layer 15a that covers the fusing part 18 and a second insulating layer 15b provided on the upper surface of the first insulating layer 15a.

  In this case, the first insulating layer 15a is composed of a mixture of a resin such as silicon and a plurality of fillers mainly composed of silica having a hollow inside or a coarse inside density, and the second The insulating layer 15b may be made of a resin such as epoxy. The first insulating layer 15a is made of a resin such as silicon, and the second insulating layer 15b is made of a plurality of resins mainly composed of a resin such as epoxy and silica having a hollow inside or a coarse inside density. You may comprise with what mixed the filler. Further, both the first insulating layer 15a and the second insulating layer 15b may be mixed with a plurality of fillers mainly composed of silica whose inside is hollow or whose inside density is rough.

  In the above-described embodiment of the present invention, the insulating layer 15 is composed of a mixture of a resin and a plurality of fillers mainly composed of silica that is hollow or rough inside and is amorphous, The metal constituting the element part 13 included in the arc generated when the element part 13 is melted can be absorbed into the inside of a filler whose main component is hollow or rough and amorphous silica. Thus, since the arc can be prevented from jumping out of the insulating layer, an effect of preventing the arc from affecting the surrounding product can be obtained.

  In addition, since the exposed area of the metal absorbed inside the filler can be reduced, a resin can exist between the filler and the metal absorbed, thereby preventing current from flowing again. In addition, it is possible to ensure the interruption of the current after the element portion is blown.

  That is, the arc is formed by sublimation and scattering of the metal constituting the element portion 13 melted by overcurrent, so that the air is contained in the inside and the surface has innumerable irregularities and has a substantially spherical shape and its surface area. By adsorbing the scattered metal inside or on the surface of a large filler, it is possible to prevent the sublimated metal from jumping out of the insulating layer 15. Furthermore, since the insulating resin can be present between the metals by adsorbing the metal scattered inside or on the surface of the filler, re-conduction after fusing can be prevented.

  Here, in order to more reliably cut off the electric current after the element part 13 is melted, it is necessary to mix a plurality of fillers mainly composed of amorphous silica with hollow or rough inside into the insulating layer 15. On the other hand, even if this filler is mixed with the underlayer 14, the effect is hardly obtained.

  That is, the arc scatters in all directions, but since the insulating substrate 11 under the element portion 13 is made of alumina, the arc does not jump out below the product (below the insulating substrate 11), but above the product. This is because the (insulating layer 15) is a resin, and the arc may jump out of the resin and affect the surrounding products.

  In addition, since the filler contains air inside, the thermal conductivity is very low, and the silicon resin also has a low thermal conductivity, so the cross-sectional area of the element portion 13 is increased in order to improve the inrush resistance. Even if it is increased, the heat generated in the element part 13 can be stored in the element part 13, and this can quickly melt the element part 13 when an overcurrent flows. And fast-acting properties can both be achieved.

  Note that, as described above, in order to achieve both inrush resistance and quick disconnection, it is necessary to lower the thermal conductivity of the filler. Therefore, the inside is mainly hollow or coarse and amorphous silica.

  Furthermore, since the filler contains silica as a main component, the heat resistance of the insulating layer 15 can be improved, whereby the fusing characteristics can be stabilized.

  Since the silicon resin can enter between the filler particles, the insulating layer 15 can be firmly fixed. Further, since the silicon resin has almost no water absorption, moisture or plating in the atmosphere can be applied to the insulating layer 15. The liquid does not enter, so that the moisture resistance can be improved.

  Note that a plurality of fillers mainly composed of amorphous silica having a hollow or coarse inside may be mixed in the underlayer 14, and in this case, since the filler contains air, the underlayer 14 The thermal conductivity of 14 can be lowered, and thereby the inrush resistance and the quick disconnection can be further improved.

  In the above-described embodiment of the present invention, the circuit protection element has been described. However, the present invention can also be applied to other electronic components such as a fuse resistor that requires stabilization of the fusing characteristics.

  The circuit protection element according to the present invention has an effect that it is possible to more reliably cut off the current after the element portion is blown, and in particular, circuit protection that blows off and protects various electronic devices when an overcurrent flows. This is useful in devices and the like.

DESCRIPTION OF SYMBOLS 11 Insulating substrate 12 Upper surface electrode 13 Element part 14 Underlayer 15 Insulating layer 17 Trimming groove

Claims (3)

An insulating substrate; a pair of upper surface electrodes provided at both ends of the insulating substrate; and an element portion formed to bridge the pair of upper surface electrodes and electrically connected to the pair of upper surface electrodes; A base layer provided between the element portion and the insulating substrate; a plurality of trimming grooves formed in the element portion; and an insulating layer provided so as to cover the element portion. A circuit protection element in which a layer is composed of a mixture of a resin and a plurality of fillers mainly composed of amorphous silica with hollow inside or coarse inside density, and the mixing ratio of the filler is 50 to 70% by volume . An insulating substrate; a pair of upper surface electrodes provided at both ends of the insulating substrate; and an element portion formed to bridge the pair of upper surface electrodes and electrically connected to the pair of upper surface electrodes; A base layer provided between the element portion and the insulating substrate; a plurality of trimming grooves formed in the element portion; and an insulating layer provided so as to cover the element portion. The layer is composed of a mixture of a resin and a plurality of fillers mainly composed of amorphous silica having a hollow inside or a coarse inner density, and the filler has a particle size of 5 to 15 μm. Is a circuit protection element made smaller than the groove width of the trimming groove. It said plurality of circuit protection device of claim 1 or claim 2 trimming groove of the groove was filled with the mixture of resin and filler.

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