TWI493588B - Fuse - Google Patents

Description

fuse

The present invention relates to a fuse.

In the past, attempts were made to connect fuses to electronic components to protect electronic components from overcurrent. For example, Patent Document 1 discloses, as an example of a fuse, a first wiring portion and a second electrode portion disposed on an insulating substrate, a metal wiring portion connecting the first electrode portion and the second electrode portion, and a metal portion. A fuse of a low melting point metal portion over one portion of the wiring portion.

Patent Document 1: Japanese Laid-Open Patent Publication No. 2012-18777

However, in the fuse disclosed in Patent Document 1, since the metal wiring portion is provided with a conductive low-melting metal portion, the relative resistance of the metal wiring portion is low, and heat is less likely to occur even if an overcurrent flows. Therefore, the fuse described in Patent Document 1 has a problem that it is difficult to break the wire, that is, the current cannot be reliably blocked.

It is an object of the present invention to provide a fuse that can reliably interrupt an overcurrent.

The fuse of the present invention includes an insulating substrate, a wiring, a low melting point metal portion, and an insulating layer. The wiring system is disposed on one main surface of the insulating substrate. The low melting point metal portion is provided on the wiring. The low melting point metal portion has a lower melting point than the wiring. The low melting point metal portion melts the wiring when it becomes a molten metal. The insulating layer is disposed between the wiring and the low melting point metal portion.

In a particular form of the fuse of the present invention, the melting point of the insulating layer is lower than the melting point of gold The melting point of the genus is high.

In another specific form of the fuse of the present invention, the insulating layer has a melting point of from 180 ° C to 350 ° C.

In still another specific aspect of the fuse of the present invention, the insulating layer is made of a thermoplastic resin.

In still another specific aspect of the fuse of the present invention, the fuse further includes a second insulating layer that covers the low melting point metal portion and has a melting point of a lower melting point metal portion.

In still another specific aspect of the fuse of the present invention, the fuse further includes a heating element that heats the low melting point metal portion.

In still another specific form of the fuse of the present invention, the low melting point metal portion contains Sn as a main component.

In still another specific aspect of the fuse of the present invention, the insulating layer is provided integrally with the portion where the wiring and the low-melting-point metal portion overlap.

According to the present invention, it is possible to provide a fuse that can reliably interrupt an overcurrent.

1,1a, 1b‧‧‧Fuse

2‧‧‧2nd electrode layer

3‧‧‧1st electrode layer

11‧‧‧1st terminal

12‧‧‧2nd terminal

13‧‧‧Wiring

13a, 13b‧‧‧Fuse electrode

13c‧‧‧ connection point

14‧‧‧3rd terminal

15‧‧‧heating body

16‧‧‧4th terminal

20‧‧‧Insulating substrate

20a‧‧‧1st main face

20b‧‧‧2nd main face

21~24‧‧‧electrode

25,27,29,30‧‧‧side electrode

26,28‧‧‧through hole electrode

31,32‧‧‧Wiring

35‧‧‧electrode layer

36‧‧‧Insulation

36a‧‧‧through holes

37‧‧‧Electrode

38‧‧‧High thermal conductor

41,42‧‧‧Low-melting metal parts

51,52‧‧‧Insulation

61~64‧‧‧Metal film

70‧‧‧Protective layer

80‧‧‧2nd insulation layer

Fig. 1 is a schematic plan view of a fuse according to an embodiment of the present invention.

Fig. 2 is a schematic bottom view of a fuse according to an embodiment of the present invention.

Figure 3 is a schematic cross-sectional view taken along line III-III of Figure 1.

Figure 4 is a schematic cross-sectional view taken along line IV-IV of Figure 1.

Figure 5 is a schematic cross-sectional view taken along line V-V of Figure 1.

Fig. 6 is a schematic plan view showing the shape of a second electrode layer according to an embodiment of the present invention.

Fig. 7 is a schematic plan view showing the shape of a first electrode layer and a heat generating body according to an embodiment of the present invention.

Fig. 8 is a schematic circuit diagram of a fuse according to an embodiment of the present invention.

Fig. 9 is a schematic cross-sectional view showing a fuse according to a first modification.

Fig. 10 is a schematic cross-sectional view showing a fuse according to a second modification.

Hereinafter, an example of a preferred embodiment for carrying out the invention will be described. However, the following embodiments are merely illustrative. The present invention is not limited to the following embodiments.

In the drawings, the components having substantially the same functions are referred to by the same reference numerals in the drawings. Further, the drawings referred to in the embodiments and the like are described in a schematic manner. The ratio of the size of the object depicted in the drawing may be different from the ratio of the size of the actual object. There are also cases where the ratio of the size of the objects differs from each other in the drawings. The ratio of the specific object size should be judged by considering the following instructions.

Fig. 1 is a schematic plan view of a fuse of the embodiment. Fig. 2 is a schematic bottom view of the fuse of the embodiment. Figure 3 is a schematic cross-sectional view taken along line III-III of Figure 1. Figure 4 is a schematic cross-sectional view taken along line IV-IV of Figure 1. Figure 5 is a schematic cross-sectional view taken along line V-V of Figure 1. Fig. 6 is a schematic plan view for explaining the shape of the second electrode layer of the embodiment. Fig. 7 is a schematic plan view for explaining the shape of the first electrode layer and the heat generating body of the embodiment. Fig. 8 is a schematic circuit diagram of a fuse of the embodiment. In addition, in FIGS. 6 and 7, the drawing of the member located in the member to be described is omitted.

As shown in FIG. 8, the fuse 1 has a wiring 13 connected between the first terminal 11 and the second terminal 12. The fuse electrode portions 13a and 13b are connected in series to the wiring 13. Here, the fuse The electrode portions 13a and 13b are portions that are insulated to insulate between the first terminal 11 and the second terminal 12 when an overcurrent flows through the fuse 1 or when a signal for causing a function of the fuse is input to the fuse 1. For example, when an overcurrent flows between the first terminal 11 and the second terminal 12, at least one of the fuse electrode portions 13a and 13b is blown. Thereby, the first terminal 11 and the second terminal 12 are insulated. Therefore, the fuse 1 functions as a passive component that detects an overcurrent and the wiring 13 is automatically cut. Further, the thickness of the wiring 13 may be, for example, about 5 μm to 20 μm.

The connection point 13c between the fuse electrode portion 13a and the fuse electrode portion 13b is connected to the fourth terminal 16. A heating element 15 composed of a resistor is provided between the third terminal 14 and the connection point 13c. When electric power is applied between at least one of the third terminal 14 and the first and second terminals 11 and 12, the heating element 15 generates heat. Thereby, at least one of the fuse electrode portion 13a and the fuse electrode portion 13b is blown, and the first terminal 11 and the second terminal 12 are insulated. Therefore, the fuse 1 also functions to detect an overcurrent and actively cut off the active components of the wiring 13. In addition, the fuse of the present invention can only function as a passive component, and can only function as an active component.

Next, a specific configuration of the fuse 1 will be described in detail with reference to FIGS. 1 to 7.

As shown in FIGS. 1 to 5, the fuse 1 includes an insulating substrate 20. The insulating substrate 20 can be formed of a ceramic substrate such as an aluminum substrate or a resin substrate. The insulating substrate 20 may be a multilayer substrate having wiring therein.

The insulating substrate 20 has a first main surface 20a and a second main surface 20b. As shown in FIG. 2, the first to fourth terminals 11, 12, 14, and 16 are disposed on the second main surface 20b. The fourth terminal 16 is connected to a connection point between the heat generating body 15 and the connection point 13c shown in FIG. Further, each of the first to fourth terminals 11, 12, 14, and 16 may be made of a suitable conductive material such as Ag, AgPt, AgPd, or Cu. The thickness of the first to fourth terminals 11, 12, 14, 16 may be, for example, about 10 μm to 20 μm.

As shown in FIGS. 1 and 6, electrodes 21 to 24 are provided on the first main surface 20a. The electrode 21 is connected to the first terminal 11 by the side surface electrode 25 and the via electrode 26 (see FIG. 2). The electrode 22 is connected to the second terminal 12 via the side electrode 27 and the via electrode 28. The electrode 23 is connected to the third terminal 14 via the side surface electrode 29. The electrode 24 is connected to the fourth terminal 16 via the side surface electrode 30. Further, the electrodes 21 to 24 may each be formed of a suitable conductive material such as Ag, AgPt, AgPd or Cu.

As shown in Fig. 7, a heat generating body 15 connected between the electrode 23 and the electrode 24 is provided on the main surface 20a. The electrode 23 and the heating element 15 are connected by a wire 31. The electrode 24 and the heating element 15 are connected by a wire 32. The heating element 15 is supported by the insulating substrate 20. Further, the heating element 15 can be constituted by, for example, a resistance heating body composed of RuO ₂ , AgPd or the like.

Electrode layers 35 are provided on the electrodes 23, 24, the heating element 15, and the wirings 31, 32 (see Figs. 3 to 6). An insulating layer 36 is disposed between the electrode layer 35 and the electrodes 23 and 24 and the wirings 31 and 32. In the present embodiment, the insulating layer 36 is provided integrally with the overlapping portions of the wirings 31, 32 and the low-melting-point metal portions 41, 42. However, in the present invention, for example, an opening or the like is formed in the insulating layer, and the wiring and the low-melting-point metal portion are connected so that the entire resistance of the wiring does not excessively decrease. As shown in FIGS. 3 and 5, a through hole 36a is provided in the insulating layer 36. The through hole 36a is connected to each of the heating element 15 and the wiring 13 (in detail, the connection point 13c). The through hole 36a may have a diameter that is substantially constant in the direction in which the central axis extends, and may be formed in a tapered shape. For example, the through hole 36a may be tapered toward the tip end toward the insulating substrate 20 side. Further, the thickness of the insulating layer 36 may be, for example, about 15 μm to 30 μm.

As shown in FIGS. 5 and 6, the electrode layer 35 includes a wiring 13 that connects the electrode 21 and the electrode 22. The wiring 13 includes a fuse electrode portion 13a and a fuse electrode portion 13b. Guarantee The connection point 13c of the fuse electrode portion 13a and the fuse electrode portion 13b and the electrode 24 are connected to the electrode 37 shown in Figs. 3 and 6 . Further, the connection point 13c is connected to the heating element 15 through the high heat conductor 38 disposed in the through hole 36a. The thermal conductivity of the high thermal conductor 38 is higher than the thermal conductivity of the insulating layer 36. The high thermal conductor 38 can be constructed of, for example, a metal. In the present embodiment, the high thermal conductor 38 is integrally provided with the wiring 13. In this case, the high thermal conductor 38 can be easily disposed.

Further, the thickness of the electrode layer 35 may be, for example, about 5 μm to 20 μm.

As shown in FIGS. 1, 4, and 5, low melting point metal portions 41, 42 are provided on the fuse electrode portions 13a, 13b of the wiring 13. The low-melting-point metal portions 41 and 42 are made of a low-melting-point metal having a lower melting point than the wiring 13 and melting the wiring 13 when the melt is formed. The low melting point metal may be, for example, Sn as a main component. Specific examples of the low melting point metal include a Sn alloy such as SnSb, SnCu, SnAg, SnAgCu, and SnCuNi, or a Bi alloy such as BiAg or BiSbBiZn. The thickness of the low melting point metal portions 41, 42 may be, for example, about 0.1 mm to 0.5 mm.

Further, a protective film such as a flux layer or an oxidation preventing film or the like may be provided on the low-melting-point metal portions 41, 42 to cover at least a part of the low-melting-point metal portions 41, 42.

As shown in FIGS. 4 and 5, in the fuse 1, the insulating layers 51, 52 are disposed between the wiring 13 and the low-melting-point metal portions 41, 42. The melting points of the insulating layers 51, 52 are lower than those of the melting point metal portions 41, 42. The melting point of the insulating layers 51, 52 is preferably from 180 ° C to 350 ° C, more preferably from 220 ° C to 320 ° C. The insulating layers 51, 52 may be formed of a suitable insulating material, but are preferably made of, for example, a thermoplastic resin. The thermoplastic resin preferably used for constituting the insulating layers 51 and 52 may, for example, be polyethylene terephthalate (PET, melting point: 264 ° C) or polybutylene terephthalate (PBT, melting point 232). °C), such as a polyester resin, a vinyl resin such as polyvinyl chloride (melting point: 180 ° C), a polystyrene resin such as polystyrene (melting point: 230 ° C), nylon 6 (registered trademark, melting point: 225 ° C), or nylon 66 ( registered Polyvinylamine resin such as trademark, melting point 267 ° C), polycarbonate resin such as polycarbonate (melting point: 250 ° C), polyfluorinated diethylene (melting point 210 ° C), chlorotrifluoroethylene (melting point 220 ° C) and other fluorine Resin or the like. The thickness of the insulating layers 51, 52 may be, for example, about 10 μm to 200 μm, preferably about 20 to 150 μm.

As shown in FIG. 6, on the insulating substrate 20, metal films 61 to 64 are disposed on the outer sides of the insulating layers 51, 52. The metal films 61 to 64 are preferably made of a metal or an alloy having a high wettability to a molten metal of the low-melting-point metal portions 41 and 42 by, for example, Ag, AgPt, AgPd, or Cu. Further, it is preferable that the metal films 61 to 64 are not easily melted in the molten metal of the low-melting-point metal portions 41, 42, and particularly preferably composed of AgPt or AgPd.

The metal films 61 to 64 are provided on both sides of the insulating layers 51 and 52 in the width direction of the wiring 13. In the present embodiment, specifically, the metal films 61, 62 are provided on both sides of the insulating layer 51 in the width direction of the wiring 13. In the width direction of the wiring 13, the metal films 61, 62 are provided so as to sandwich the fuse electrode portion 13a. The low melting point metal portion 41 is in contact with the metal films 61, 62. Specifically, the low-melting-point metal portion 41 is provided from the metal film 61 across the insulating layer 51 and the metal film 62.

In the width direction of the wiring 13, the metal films 63, 64 are provided on both sides of the insulating layer 52. In the width direction of the wiring 13, the metal films 63, 64 are provided so as to sandwich the fuse electrode portion 13b. The low melting point metal portion 42 is in contact with the metal films 63, 64. Specifically, the low-melting-point metal portion 42 is provided from the metal film 63 across the insulating layer 52 and the metal film 64.

Further, the metal films 61 to 64 may be composed of a laminate of a plurality of metal films. The plurality of metal films constituting the metal films 61 to 64 may include a plurality of metal films having different melting points. The metal films 61 to 64 may have a first metal film or a second metal film which is provided on the first metal film and has a lower melting point than the first metal film. In this case, the second metal film may reach the insulating films 51, 52.

The thickness of the metal films 61 to 64 may be, for example, about 20 μm to 40 μm.

As shown in FIG. 1, a protective layer 70 is provided which surrounds each of the region in which the low-melting-point metal portion 41 is provided and the region in which the low-melting-point metal portion 42 is provided. By providing the protective layer 70, it is possible to effectively suppress the wet diffusion of the molten metal of the low melting point metal in the intended outward direction. The thickness of the protective layer 70 may be, for example, about 10 μm to 20 μm.

Next, the generation of the fuse function of the fuse 1 will be described.

For example, when an overcurrent flows between the first terminal 11 and the second terminal 12, the fuse electrode portions 13a and 13b which are thin and wide are heated. By this heat generation, the low-melting-point metal portions 41, 42 are heated and melted. Further, the insulating layers 51, 52 are also melted, and the molten metal of the low melting point metal is in contact with the fuse electrode portions 13a, 13b. As a result, the fuse electrode portions 13a and 13b are melted in the molten metal of the low melting point metal, and the wiring 13 is melted. Thereby, the fuse function is generated.

In the fuse 1, an insulating layer 51, 52 is provided between the wiring 13 and the low-melting-point metal portions 41, 42. The wiring 13 is electrically insulated from the low melting point metal portions 41, 42 by the insulating layers 51, 52. Therefore, unlike the case where the low-melting-point metal portion is electrically connected to the wiring, the relative resistance of the wiring 13 is large. Therefore, when an overcurrent flows between the first terminal 11 and the second terminal 12, the wiring 13 is likely to generate heat. Therefore, in the fuse 1, when an overcurrent flows between the first terminal 11 and the second terminal 12, the fuse function is highly accurate.

Further, in the fuse 1, the melting points of the insulating layers 51, 52 are lower, and the melting points of the metal portions 41, 42 have a higher melting point. Therefore, by bringing the low-melting-point metal portions 41, 42 into contact with the wiring 13 until the insulating layers 51, 52 are melted, the relative resistance of the wiring 13 can be effectively suppressed from being lowered. Therefore, the fuse function is generated at a higher accuracy rate.

From the viewpoint of the higher accuracy of the fuse function, the melting points of the insulating layers 51, 52 are lower. The melting point of the melting point metal portions 41, 42 is preferably 10 ° C or more, and more preferably 20 ° C or higher. however, If the melting points of the insulating layers 51, 52 are lower than the melting point of the melting point metal portions 41, 42 is too high, the insulating layers 51, 52 are not easily melted, and the molten metal of the low melting point metal is not easily contacted with the wiring 13, but the fuse function is not easily generated. situation. Therefore, the melting points of the insulating layers 51, 52 are preferably the melting point of the low melting point metal portions 41, 42 + 50 ° C or lower, more preferably the melting point of the low melting point metal portions 41, 42 + 30 ° C or lower. Specifically, the melting points of the insulating layers 51, 52 are preferably in the range of 180 ° C to 350 ° C, more preferably in the range of 220 ° C to 320 ° C, and most preferably in the range of 260 ° C to 280 ° C.

However, in order to reliably melt the wiring 13 by the molten metal of the low melting point metal, it is important to arrange the molten metal of the low melting point metal in advance in a region where the wiring 13 can be surely contacted. However, the insulating layers 51, 52 having a low wettability of the molten metal of the low melting point metal are provided below the low melting point metal portions 41, 42 so that the molten metal of the low melting point metal is easily displaced. Therefore, in the fuse 1, the metal films 61 to 64 are disposed on the insulating substrate 20 outside the insulating layers 51, 52. The molten metal of the low melting point metal is contacted by the metal films 61 to 64 by the molten metal of the low melting point metal, and the molten metal of the low melting point metal is captured by the metal films 61 to 64. Therefore, in the fuse 1, the molten metal of the low melting point metal can be placed in advance in a region where the wiring 13 can be reliably contacted. Therefore, in the fuse 1, the fuse function is generated at a high rate.

From the viewpoint of reliably capturing the molten metal of the low melting point metal by the metal films 61 to 64, it is preferable that the low melting point metal portions 41, 42 are in contact with the metal films 61 to 64. Preferably, in the width direction of the wiring 13, the metal films 61 to 64 are provided on both sides of the insulating films 51, 52. Preferably, the metal films 61 to 64 are provided on both sides of the fuse electrode portions 13a and 13b in the width direction of the wiring 13. Preferably, the low-melting-point metal portions 41 and 42 are provided across the metal film 61 and the metal film 62, the metal film 63, and the metal film 64 provided on both sides of the wiring 13.

Further, in the case where the overcurrent does not flow through the first terminal 11 and the second terminal 12, the fuse 1 can generate a fuse function by generating heat. in particular, By applying electric power between the third terminal 14 and the terminals 11, 12 or the terminal 16, the heating element 15 generates heat. The low-melting-point metal portions 41, 42 are melted by the heat from the heating element 15, and the fuse electrode portions 13a, 13b of the wiring 13 are blown.

In the fuse 1, the heat generating body 15 is connected to the wiring 13 by a high heat conductor 38 provided in the through hole 36 and having a higher thermal conductivity than the insulating layer 36. Therefore, the heat of the heating element 15 is easily transmitted to the low-melting-point metal portions 41, 42 through the wiring 13. Therefore, in the fuse 1, even when the heating element 15 is heated to actively generate the fuse function, the fuse function is highly accurate.

From the viewpoint of the higher accuracy of the fuse function, it is preferable that the through hole 36a is provided so as not to overlap the low melting point metal portions 41, 42 in plan view. When the low-melting-point metal portions 41 and 42 are located in the through-holes 36a, the first terminal 11 and the second terminal 12 are insulated from the fuse line 13, and when the high-heat conductor 38 is electrically conductive, it must be blown together with the wiring 13 to high heat conduction. Body 38. On the other hand, in the plan view, the through hole 36a is provided so as not to overlap the low-melting-point metal portions 41 and 42. When only the wiring 13 is blown, the first terminal 11 and the second terminal 12 are insulated. Therefore, the fuse function is easier to produce.

Hereinafter, a modification of the above embodiment will be described. In the following description, members having substantially the same functions as those of the above-described embodiments are referred to by common symbols, and description thereof will be omitted.

(First Modification)

Fig. 9 is a schematic cross-sectional view showing a fuse according to a first modification.

As shown in FIG. 9, the fuse 1a may further include an insulating layer 80 that covers the low-melting-point metal portions 41, 42 and has a melting point of a lower melting point metal portion 41, 42 having a higher melting point. By providing the insulating layer 80, it is possible to suppress the melt of the low melting point metal melted by the low melting point metal portions 41, 42 from spreading in an intended outward direction.

The melting point of the second insulating layer 80 is preferably such that the melting point of the lower melting point metal portions 41, 42 is 10 ° C or more higher, more preferably 20 ° C or higher. The second insulating layer 80 may be made of an insulating material such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate or the like which can be used for the insulating layers 51, 52.

(Second modification)

Fig. 10 is a schematic cross-sectional view showing a fuse according to a second modification.

In the fuse 1 of the above embodiment, an example in which the heating element 15 is provided on the insulating substrate 20 will be described. However, the present invention is not limited to this configuration. As shown in FIG. 10, in the fuse 1b of the present modification, the heat generating body 15 is provided inside the insulating substrate 20. The portion of the insulating substrate 20 between the heating element 15 and the wiring 13 constitutes an insulating layer 36. Even in this case, substantially the same effects as those of the above embodiment can be obtained.

1‧‧‧Fuse

11‧‧‧1st terminal

12‧‧‧2nd terminal

13‧‧‧Wiring

13a, 13b‧‧‧Fuse electrode

15‧‧‧heating body

20‧‧‧Insulating substrate

20a‧‧‧1st main face

20b‧‧‧2nd main face

21,22‧‧‧electrodes

25,27‧‧‧ Side electrode

35‧‧‧electrode layer

36‧‧‧Insulation

36a‧‧‧through holes

38‧‧‧High thermal conductor

41,42‧‧‧Low-melting metal parts

51,52‧‧‧Insulation

70‧‧‧Protective layer

Claims (7)

A fuse comprising: an insulating substrate; a wiring disposed on one main surface of the insulating substrate; and a low melting point metal portion provided on the wiring, having a melting point lower than the wiring, and being a molten metal The wiring is melted; and an insulating layer is disposed between the wiring and the low melting point metal portion, and the insulating layer has a melting point of 180 ° C to 350 ° C. The fuse of claim 1, wherein the insulating layer has a melting point higher than a melting point of the low melting point metal portion. A fuse according to claim 1 or 2, wherein the insulating layer is made of a thermoplastic resin. The fuse according to claim 1 or 2, further comprising a second insulating layer covering the low melting point metal portion and having a melting point higher than a melting point of the low melting point metal portion. A fuse according to claim 1 or 2, further comprising a heating element for heating the low melting point metal portion. The fuse of claim 1 or 2, wherein the low melting point metal portion is mainly composed of Sn. A fuse according to claim 1 or 2, wherein the insulating layer is provided over the entire overlapping portion of the wiring and the low melting point metal portion.