JP2009193723A - Fuse element, and fuse - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a miniaturizable fuse element capable of reducing an I<SP>2</SP>T value, and reducing cost. <P>SOLUTION: This fuse element comprises an insulating substrate, and a conductive thin film on the insulating substrate, and the conductive thin film has a pattern formed by further alternately and cyclically serially connecting cutoff parts each having a plurality of cutoff part narrow bands 22_<SB>k</SB>arranged in parallel to one another through connection bands 21_<SB>k</SB>. Each of the plurality of cutoff part narrow bands 22_<SB>k</SB>is provided with current narrowing means R<SB>a2</SB>, R<SB>b2</SB>each having an area smaller than that of a hole part Qj separating the cutoff part narrow bands 22_<SB>k</SB>from each other in the parallel direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuse for protecting a semiconductor switching device such as a GTO thyristor or IGBT, and a fuse element used for the fuse.

In contrast to the remarkable development of semiconductor switching devices, protective fuses for protecting semiconductor devices have always been developed late. In a fuse for protecting a semiconductor device, an I ² T value obtained by integrating a square value (I ² dt) of a breaking current I read in an oscillogram waveform of the breaking experiment with a breaking time 0 to T is defined, In comparison, the smaller the I ² T value, the better the performance. Further, unit fuses are arranged in parallel to form unit parallel parts (parallel interrupting parts), and S parallel interrupting parts are connected in series to form a fuse element. That is, the number of parallel sections of the blocking section narrow band constituting the parallel blocking section is expressed as “P value”, and the series number in which the parallel blocking sections are arranged in series is expressed as “S value”. In designing the fuse element, the serial connection number S value is determined corresponding to the rated voltage, and the parallel connection number P value is determined corresponding to the rated current. The conventional values of these values have been kept for 1 to 1.25 / 100 V with respect to the serial connection number S value and 1 to 10 P / cm with respect to the parallel connection number P value for more than 20 years.

Conventionally, a silver ribbon press-type fuse element is known as a fuse for protecting a semiconductor device. For example, by forming three circular holes adjacent to each other in a silver (Ag) ribbon by a press die in parallel, and further providing semicircular depressions on both sides, four blocking section narrow bands are formed, As a result, there is known a structure in which four unit fuses are arranged in parallel to form a parallel interrupting unit, and further, four sets of the parallel interrupting units arranged in parallel are arranged in series via a connecting band (heat dissipating zone). In this case, since five blocking section narrow bands in which the cross-sectional area of the silver ribbon is narrowed are in series and four in parallel, it is expressed as 5S4P. The silver ribbon press-type fuse element is housed in a fuse cylinder buried in arc-extinguishing sand. The energizing current normally flows through the fuse element. However, when an accident current occurs, each of the narrow sections having a small cross-sectional area and a high resistance value is melted, and the arc voltage is increased to quickly interrupt the accident current. Recently, the silver ribbon press-worked fuse element has been made to exceed AC8000V current 3000A, but it is large and the price is over 200,000 yen. However, the conventional press-type fuse element has a limit of 150 μm thickness and 150 μm line width, and it seems that the limit has been seen in the reduction of I ² T value, cost reduction and miniaturization. .

  The present inventors have proposed an etching fuse element for such a silver ribbon press-worked fuse element (see Patent Document 1). Furthermore, in addition to the etching fuse element proposed in Patent Document 1, various improved types have been prototyped and evaluated and studied. As shown in FIG. 11, these etching and fuse elements basically have a structure in which a conductive thin film 39 is formed on the surface of a rectangular ceramic substrate 32 having electrical insulation. The etching fuse element is embedded in arc-extinguishing sand in a fuse cylinder and stored in the same manner as a silver ribbon press-type fuse element. The conductive thin film 39 is made of a copper foil, a silver foil, or the like, and a pattern of a blocking portion narrow band is formed by etching.

  FIG. 11 shows an example of a planar pattern of an improved etching fuse element, and a network type intelligent fuse element having three rhombus portions Q arranged in parallel on both sides of the central separation hole V as parallel interrupting portions. It is. The central separation hole V has a shape in which a rhombus and a rectangle are combined. The long side of the rectangle is shorter than the length of the unit fuse, but is almost the length of the unit fuse. Both sides of the parallel cut-off portion are triangular with the diamond-shaped portion Q halved. One notch part sandwiched between the outermost triangle and rhombus Q, two notches sandwiched between two rhombus Q, and one notch sandwiched between rhombus Q and separation hole V In this structure, the four notches are arranged on both sides of the separation hole V in the central portion. That is, a total of eight channels of current paths are formed by the four notches on the left side of the separation hole V and the four notches on the right side of the separation hole V. In other words, in the pattern illustrated in FIG. 11, eight unit fuses are arranged in parallel to form a parallel cutoff unit, and a plurality of sets (for example, 22) of the parallel cutoff units are arranged in series via a connection band (heat dissipation band). Structure.

  In an etching fuse element as illustrated in FIG. 11 (a structure without a separation hole V like the network type intelligent fuse element in FIG. 11 may be used), the energization current normally flows through the conductive thin film 39 of the fuse element. However, when an accident current occurs, each of the narrow strips having a small cross-sectional area and a high resistance value is melted, and the arc voltage is increased to quickly interrupt the accident current.

Conventionally, the etching fuse element has been considered to have a limit of about 30 to 60 μm in thickness of the conductive thin film 39 and about 100 μm in line width. In particular, it is considered that the length measured in the series direction of the connecting band (heat dissipating band) connecting the parallel blocking portions is required to be 3 mm. Therefore, the maximum number of series connections S value is in the rated voltage 600V class. In the conventional technical common sense, it was thought that it would be about 8S. However, as a result of trial production by the present inventors, it has become possible up to about 24S, but it is difficult to further miniaturize due to the limitation of the etching technique. I think that the. Similarly, in the rated voltage of 7200V class, it was thought that it would be about 46S in the conventional technical common sense, but it has become possible to about 180S by trial production of the present inventors, but due to the limitation of the etching technology Further refinement seems to be difficult. With regard to the number of parallel connections, the present inventors have made a trial production, and it has become possible from about 5P to about 32P in the 2 rated voltage 600V class, and from about 30P to about 110P in the rated voltage 7200V class. However, further miniaturization seems difficult due to the limitations of the etching technique.
JP 2006-73331 A

In this way, the limit has been seen in the reduction of the I ² T value, cost reduction and miniaturization of the etching fuse element. A conventional etching fuse element with 1 / 100V for the number of series connections S and 10P / cm for the number P of parallel connections has been commercialized, and it is smaller and more efficient than a silver ribbon press-type fuse element. Even so, sales are still sluggish due to the high costs.

  Since there is basic research in foreign countries such as EU, it will not be put into practical use, so the same technical problem as above is estimated.

  In the past, attempts have been made to increase the number of breaking points in order to improve the breaking performance of the fuse. However, as a conventional common sense, it has been considered that the current-limiting characteristic is improved as the length of arcing at the same time in the blocking portion narrow band is increased. Therefore, it is said that the larger the diameter of the arc that forms the blocking portion narrow band, the better.

In view of the above problems, an object of the present invention is to provide a fuse element capable of reducing the I ² T value, reducing the cost, and reducing the size, and a fuse using the fuse element.

  In order to achieve the above object, an aspect of the present invention comprises an insulating substrate and a conductive thin film on the insulating substrate, and the conductive thin film includes a plurality of blocking portions narrow bands arranged in parallel. A fuse element having a pattern in which a plurality of interrupting section narrow bands are separated from each other in the parallel direction. The fuse element includes a current constricting means having a smaller area than the portion.

  Another aspect of the present invention includes an insulating tube serving as a fuse cylinder, and an insulating substrate housed in the insulating tube. The insulating substrate includes a conductive thin film on the insulating substrate. The conductive thin film includes a plurality of conductive thin films. The present invention relates to a fuse including a fuse element having a pattern in which interrupting parts in which interrupting part narrow bands are arranged in parallel are further connected in series alternately and in series via a connection band. That is, in the fuse according to another aspect, each of the plurality of blocking portion narrow bands provided in the fuse element housed therein has an area larger than the hole portion that separates the blocking portion narrow bands from each other in the parallel direction. It is characterized by having a small current confinement means.

According to the present invention, it is possible to provide a fuse which uses a reduction in I 2 ^T value, the fuse element and the fuse element capable cost reduction and downsizing.

  The inventors of the present invention have found that the arc voltage increases as the number of series is increased by dividing the narrow section of the interrupting portion to increase the arc voltage, and the arc characteristic is improved, and this is named “S effect”. While the experiment of the S effect is repeated, the method of increasing the dv / dt of the rising edge of the arc by increasing the length of the narrow band of the instantaneous interrupting portion, which was the conventional common sense, is not wrong, but only that is true. I started to question the best way.

  The present invention is an idea that is completely opposite to the conventional idea in that the method of shortening the arc length as much as possible, reducing the cross-sectional area of the blocking portion narrow band and shortening the arcing time as much as possible is good. However, it is practically difficult because the rated current, voltage, fusing characteristics, and temperature rise characteristics of the fuse element must be satisfied. There are many ways to do this.

  For example, in conventional silver ribbons and press-type fuses, there is a method of placing solder at one point of the narrow part of the interrupting part, and alloying the narrow part of the interrupting part to lower the fusing temperature. It is used to make the first firing point the center of the fuse element only by making the firing of a part of the fuse early, but applying it to all the breaking points increases the variation of the fusing characteristics and is economical. It does not hold.

  In order to improve current-limiting characteristics in power fuses, it has been common knowledge that the instantaneous fusing length of unit fuses must be increased to increase the arc voltage rise rate (dv / dt).

  However, in the etching fuse element of the present invention, it is important to produce a smaller minimum cross-section of the cut-off portion narrow band even if the instantaneous fusing length of the unit fuse is short. This finding is an empirical fact obtained as a result of numerous repeated experiments. Experiments for shortening the arcing time of all series break points of the etching / fuse element and ensuring fusing characteristics with little variation cannot be obtained with a fusing test circuit performed at a low voltage. It is necessary to carry out many interruption experiments similar to the actual circuit, and it is impossible in terms of economy and time to perform an experiment using a normally considered short-circuit generator. The present inventors are the first to make a high- and low-voltage LC-type breaker for electric power that enables an experiment of a sealed large-capacity fuse using an LC resonance circuit, and it is possible for the first time to enable a high-frequency break experiment. It became.

  In the etching fuse element according to the present invention, when a long interrupting narrow band melts simultaneously with Joule loss, and the arc energy is extremely larger than Joule loss due to resistance, the arc length at the time of ignition is However, even if it is short, the rate of progress is high, and it is thought that the current rise is suppressed more quickly in conjunction with the early arcing.

  Next, first and second embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. In addition, the thicknesses and dimensions of the layers described in the first and second embodiments of the present invention should not be interpreted in a limited manner, and the specific thicknesses and dimensions should be referred to the following description. It should be judged and, of course, there are portions where the dimensional relationships and ratios are different between the drawings.

  Further, the first and second embodiments of the present invention described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is as follows. The material, shape, structure, arrangement, etc. of the component parts are not specified as follows. The technical idea of the present invention can be variously modified within the technical scope described in the claims.

(First embodiment)
The fuse element according to the first embodiment of the present invention has m holes (ellipsoidal holes with projections) Q ₁ , Q ₂ , Q ₃ ,. _{Q m-1, Q m (} m = P-1 is a positive integer.) and the hole portions _{Q 1, Q 2, Q 3} , ......, flanked on _{Q m-1, Q m,} 2 -stage P pieces of narrow section narrow bands tied to the mortar shape of the diaphragm are arranged in parallel in the horizontal direction of FIG. 1 to form the shut sections 22 _-1 , 22 _-2 , 22 _-3 ,..., _{22- (n-1)} , 22- _n . Further, n (n = S is a positive integer) blocking portions 22 ₋₁ , 22 ₋₂ , 22 ₋₃ ,..., 22 _{− (n−1)} , 22 _−n are in the vertical direction of FIG. Are arranged in series.

FIG. 2A is a sectional view for explaining in detail the structure of a unit fuse constituting the fuse element according to the first embodiment of the present invention. 2 (b) corresponds to FIG. 2 (a), in which four specific unit fuses are selected from the fuse elements shown in FIG. 1, and the current confinement provided in the breaking portion narrow band 22- _k. It is a top view explaining a means ( _Ra2 , _Rb2 ) in detail. That is, as shown in FIG. 2 (b), blocking part narrow band 22 _-k is right the first arc R _a1, defined on the left in the first arc R _b1, and constricted mortar type substantially symmetrical However, at the position where the constriction width of the cut-off portion narrow band 22- _k is minimum, the second arc R _a2 having a notch pattern on the right side and the second arc R _b2 having a notch pattern on the left side are the current confinement of the present invention. As a means, a two-stage aperture structure is achieved. In FIG. 2B, the current confinement means is illustrated by the second arcs R _a2 and R _b2 , but the current confinement means does not need to be arc-shaped, and the holes Q ₁ , Q ₂ , Q ₃ ,. ..., Q _m−1 , as _long as the area is smaller than Q _m , a polygon such as a wedge shape (triangle), a rectangle, or a hexagon may be used. However, considering the ease of microfabrication, an arc shape such as a circle or an ellipse is preferable. )
FIG. 2 shows current confinement means (R _a2 , R at the side so as to have a thickness _H , a length H measured in the series direction, a minimum narrow band width P ₁ measured in the parallel direction, and a maximum width B. _b2 ), which is connected to the cut-off portion narrow band 22- _k and the cut-out portion narrow band 22- _k, which are confined in a two-stage mortar shape, and has a thickness _R and a length R measured in series. It shows that a unit fuse is constituted by a rectangular connecting band (heat radiation band) 21 _{-k of} width B measured in the direction. For this reason, the length P _L measured in the series direction of the unit fuses is H = R.

The blocking sections 22 ₋₁ , 22 ₋₂ , 22 ₋₃ ,..., 22 _{− (n−1)} and 22 _−n shown in FIG. 1 are preferably 2.5 mm or less in length measured in the series direction. N pairs may be arranged in series via the coupling bands (radiation bands) 21 ₋₁ , 21 ₋₂ , 21 ₋₃ ,..., 21 _{− (n−1)} and 21 _−n . As shown in FIG. 1, terminal portions 11 and 12 are provided at both ends of the fuse element measured in the series direction. In the present specification, a combination of the series connection number S = n and the parallel connection number P = m + 1 is expressed as “nS (m + 1) P” in the following description.

As shown in FIG. 3, if the length measured in the series direction of the fuse elements is L, the width measured in the parallel direction of the fuse elements is W, and the length measured in the series direction of the terminal portions 11 and 12 is T. Using the parallel connection number P value and the serial connection number S value:
B = W / P (1)
P _L = H + R = (L−2T) / S (2)
It can be expressed as

If it described with reference to the definition of the thickness shown FIG. 2 (a), the fuse element is cut off portion 22 _-1 according to the first embodiment, 22 _-2, 22 _-3, ..., 22 - _{( n-1),} a thickness of t _H = 10 to 60 [mu] m of 22 _-n, connecting bands (radiating _{band) 21 -1, 21 -2, 21} -3, ......, 21 - (n-1), 21 _-n thickness t _R = 80 to 150 μm is preferable, but is not necessarily limited thereto. Since the minimum narrow band width P ₁ depends on the thickness t _H of the blocking portion, considering the fine workability, the thickness t _H of the blocking portion is preferably 10 to 40 μm, and the parallel connection number P value and series connection In order to increase the value S, the thickness t _H of the blocking part is preferably about 10 to 30 μm. The minimum narrow band width P ₁ is theoretically possible up to about the thickness t _{H of} the blocking portion, but is preferably about twice the thickness t _H of the blocking portion in consideration of variations in processing dimensions. Therefore, if the thickness t _H of the blocking portion is about 30 μm, the minimum narrow band width P ₁ = 60 μm can be processed by etching, and if the thickness t _H of the blocking portion is about 10 μm, the minimum narrow band width is obtained. P ₁ = 20 μm can be processed by etching.

In the fuse element according to the first embodiment, the thickness t _R of the connection bands (heat dissipation bands) 21 ₋₁ , 21 ₋₂ , 21 ₋₃ ,..., 21 _{− (n−1)} , 21 _−n. , And the resistance values of the coupling bands (radiation bands) 21 ₋₁ , 21 ₋₂ , 21 ₋₃ ,..., 21 _{− (n−1)} , 21 _−n are small, and the coupling bands (radiation bands) ) 21 ₋₁ , 21 ₋₂ , 21 ₋₃ ,..., 21 _{− (n−1)} , 21 _−n to increase the mass of the connection band (heat dissipation band) 21 ₋₁ , 21 ₋₂ , 21 _{− Even if} the length R of ₃ ,..., 21- _(n-1) , 21 _-n is small, the coupling bands (heat radiation bands) 21 _-1 , 21 _-2 , 21 _{-3 ,. 1)} , 21 _-n can be ensured, which is preferable.

In the fuse element according to the first embodiment, the thickness t _H of the breaking portions 22 ₋₁ , 22 ₋₂ , 22 ₋₃ ,..., 22 _{− (n−1)} and 22 _−n is reduced. For example, the number P of parallel connections can be increased to increase the P effect while the number S of series connections can be increased, so that the I ² T value can be reduced to 1/10 of the conventional fuse by utilizing the S effect to the maximum. Can also be reduced.

As shown in FIG. 1, the fuse element according to the first embodiment is an insulating substrate such as a ceramic substrate having a thickness of 0.8 mm to 1.5 mm (the insulating substrate is not shown in FIG. 1). However, refer to the insulating substrate 32 in FIGS. 9 to 11) to form a conductive thin film pattern. As a material for the ceramic substrate, alumina (Al ₂ O ₃ ), mullite (3Al ₂ O ₃ .2SiO ₂ ), beryllia (BeO), aluminum nitride (AlN), silicon carbide (SiC), or the like can be used. The conductive thin film is preferably a metal thin film, particularly copper (Cu) in view of low cost and ease of processing, but is not limited to copper. If it is a metal thin film, especially a copper thin film, the pattern of the fuse element according to the first embodiment can be easily formed by copper (Cu) plating and etching. That is, copper is thinly plated with a thickness t _H = 10 to 60 μm on the ceramic substrate, and the blocking portions 22 _-1 , 22 _-2 , 22 _-3 , ..., _{22- (n-1)} , 22 After patterning _-n , the connecting bands (heat dissipation bands) 21 _-1 , 21 _-2 , 21 _-3 , ..., 21- _(n-1) , 21 _-n have thickness t _R = 80 ~ What is necessary is just to perform additional plating until it becomes 150 micrometers.

  The plane pattern illustrated in FIG. 1 shows the case where the number of parallel connections P = 16 for the sake of convenience, but is not limited to this, and various types such as P = 8, 30, 32,..., 60, 70, 75, etc. Values can be adopted. Similarly, various values such as the number of serial connections S = 12, 16, 24,..., 79,. According to the fuse element according to the first embodiment, it is possible to provide a fuse having a serial connection number S value of 1.5 / 100 V or more, which exceeds the conventional common sense value of 1 to 1.2 / 100 V. Here, “the number S of series connections of 1.5 / 100 V or more” indicates that the number S of series connections is 1.5 or more per 100 V of effective voltage. Specifically, the number S of serial connections of AC600V fuses is commonly 7 to 7S, whereas according to the fuse element according to the first embodiment, the number S of series connections of AC600V fuses is 24S-32S is possible. Further, 60 to 70S is the conventional common sense in the AC6000V fuse, but 148 to 198S can be realized by the fuse element according to the first embodiment.

Table 1 shows first to third embodiments related to an etching fuse element having a current confinement means, a comparative example related to an etching fuse element having a one-stage drawing pattern, and a conventional technique (a fuse for protecting a high voltage semiconductor device). (A silver ribbon press-working type fuse element with a rated current of 75 A, manufactured by Ferrers, Inc.), which is an exclusive manufacturer, is a comparison. The two-stage aperture patterns of the first to third embodiments are the same with the number of series connections S = 180 and the number of parallel connections P = 75 (180S75P type). However, by changing the plating thickness of the fuse elements of the first, second, and third embodiments, the total resistance value of the fuse elements of the first, second, and third embodiments is 18.11 mΩ, respectively. , 18.66 mΩ and 18.38 mΩ, which are different from each other. On the other hand, as a comparative example, in the trial production by the present inventors, two fuse elements having a series connection number S = 79 and a parallel connection number P = 30 (79S30P), which have obtained the highest performance so far, are connected in parallel. The total resistance value of the fuse element was 5.95 mΩ. On the other hand, the total resistance value of a conventional silver ribbon press-working type fuse element with a rated current of 75 A from Ferrers = 8.8 mΩ.

The total resistance value of the conventional fuse element of Ferrers's rated current 75A silver ribbon press-type fuse element is defined as the reference resistance value, and the "Equivalent I ² T value" in Table 1 indicates the same rated current value for each fuse. In order to compare the elements, the standard resistance value = 8.8 mΩ is standardized by the square of the value obtained by dividing the total resistance. That is, the equivalent I ² T value of the fuse element in the first embodiment by multiplying the total I ² T value 1470 (A ² s) and (18.11 / 8.8) ² of the first embodiment 6226 (A ² s). Similarly, the equivalent I ² T value of the fuse element of the second embodiment is obtained by multiplying the total I ² T value 1416 (A ² s) of the second embodiment by (18.66 / 8.8) ² to 6367 (A ² s), and the equivalent I ² T value of the fuse element of the third embodiment over the entire I ² T value 1802 (a ² s) and (13.38 / 8.8) ² of the third embodiment 4811 (A ² s). The equivalent I ² T value of the fuse element of the comparative example is 8364 (A ² s) by multiplying the total I ² T value 18296 (A ² s) of the comparative example by (5.95 / 8.8) ^2. .

The comparison value A shown in the second column from the right in Table 1 is that of the first, second, and third embodiments when the equivalent I ² T value of the prior art Fellers fuse element is 100%. This is the ratio of the equivalent I ² T values of the fuse elements. From Table 1, by providing current confinement means, the fuse element of the first embodiment is 70% of the prior art, the fuse element of the second embodiment is 72% of the prior art, and the fuse element of the third embodiment is the prior art. It can be seen that an improvement effect of reducing the equivalent I ² T value to a value of 72% or less of the prior art can be obtained.

The comparison value B shown in the rightmost column of Table 1 is the equivalent of each of the fuse elements of the first, second, and third embodiments when the equivalent I ² T value of the fuse element of the comparative example is 100%. It is the ratio of the I ² T value. From Table 1, by providing the current confinement means, 74% of the comparative example is the fuse element of the first embodiment, 76% of the comparative example is the fuse element of the second embodiment, and the comparative example is the fuse element of the third embodiment. It can be seen that an improvement effect of reducing the equivalent I ² T value to 58% or less of the comparative example is 76% or less is obtained.

From Table 1, it can be seen that the provision of the current constriction means improves the performance of the fuse element by forming the constriction pattern of the two-stage aperture. The “S, P effect” contributes to the improvement. So be careful. FIG. 4 shows four types of plane patterns for separating the “S, P effect” and the effect of the two-stage aperture by the current constriction means. FIG. 4 shows a planar pattern of unit fuses in a fuse element having a serial connection number S = 180 and a parallel connection number P = 75 (180S75P type), as in the first to third embodiments shown in Table 1. In FIG. 4, the unit fuse width P ₃ = 0.32 mm, the blocking portion narrow band width P ₁ is 45 μm, and the blocking portion thickness t _H is 15 μm.

In FIG. 4, the radius of curvature r of the one-stage aperture pattern (H-shaped aperture pattern) indicated by the symbol H is 0.1 mm. On the other hand, the curvature radius r of the two-stage aperture pattern (A-type aperture pattern) indicated by the symbol A is 0.1 mm, and the radius of curvature r of the two-stage aperture pattern (B-type aperture pattern) indicated by the symbol B = 0. The radius of curvature r of the two-stage aperture pattern (C-type aperture pattern) indicated by the symbol C is 0.04 mm. The calculation result of the resistance value of the entire breaking portion narrow band width per unit fuse with respect to a total of four types of patterns including the patterns of three types of current constriction means having different narrowing degrees shown in FIG. It shows in Table 2. In calculating the resistance value of the entire narrow width of the blocking portion, the resistivity of silver (Ag) at 20 ° C. was 1.72 × 10 ⁻⁸ Ω · m.

The result of Table 2 is shown as a graph in FIG. When the resistance value of the H-type aperture pattern, which is a one-stage aperture pattern, is 100%, the ratio of the resistance values of the A-type aperture pattern, the B-type aperture pattern, and the C-type aperture pattern to the resistance value of the H-type aperture pattern is expressed in%. The resistance value of the two-stage aperture pattern is as small as 97%, 79%, and 67%. I ² T value should be compared with the same rated current value, when converted by the resistance value, it means that dividing the square value of the resistance value, when converted I ² T value as 100% H It can be seen that the A-type aperture pattern is 94%, the B-type aperture pattern is 62%, and the C-type aperture pattern is 46%. Therefore, the effect of the two-stage constriction by the arc-shaped current confinement means becomes more effective as the radius of curvature r is decreased, and the improvement effect of reducing the I ² T value to 50% or less is obtained by improving the etching technique. You can see that If the current confinement means is wedge-shaped, the effect of reducing the I ² T value is increased if the tip angle of the wedge becomes sharp as a geometrical meaning equivalent to the radius of curvature. Similarly, even if the current confinement means is polygonal, the effect of reducing the I ² T value increases if the notch shape having the geometrical meaning equivalent to the radius of curvature becomes sharp.

  FIG. 6 shows an example of the mounting structure of the fuse element according to the first embodiment. In FIG. 6, three fuse elements 1a, 1b, 1c are fixed through rectangular slits provided in the inner caps 2a, 2b. Then, inner caps 2a and 2b are put on both ends of the insulating tube so as to close both ends of the insulating tube 5 serving as a fuse cylinder, and outer caps 3a and 3b having fuse terminals 4a and 4b on the outside of the inner caps 2a and 2b, respectively. Is inserted into the fuse cylinder. Arc-insulating sand is accommodated in the insulating tube 5 serving as a fuse cylinder, and the fuse elements 1a, 1b, and 1c are buried and accommodated in the arc-extinguishing sand.

As described above, according to the fuse element according to the first embodiment, the I ² T value can be reduced to 1/10 of that of the conventional fuse by using the current constriction means together with the S and P effects. Therefore, there is a margin in current in design. Therefore, the rated current can be increased by increasing the minimum narrow band width P ₁ while maintaining the I ² T value below the desired value. That is, since it is easy to double the rated current flowing through one fuse element, as shown in FIG. 6, the number of fuse elements used in the fuse element mounting structure is reduced to half or less, and the mounting structure ( It is possible to reduce the size and cost of the fuse cylinder).

(Second Embodiment)
As shown in FIG. 7, the fuse element according to the second embodiment of the present invention includes m elliptical hole portions (first holes) Q ₁₁ , Q ₂₁ , Q ₃₁ , _{......, Q (m1) 1,} Q m1 (m = P-1 is a positive integer.), the first bore Q _{11 respectively, Q 21, Q 31, ......} , Q (m1) 1, Q _m1 is sandwiched between the mortar-shaped constricted portions, and one mortar-shaped constricted portion is provided in each, and the first holes Q ₁₁ , Q ₂₁ , Q ₃₁ ,..., Q _{(m-1) 1} , P current paths (narrow strips of blocking parts) are arranged in parallel by the second holes Q ₁₂ , Q ₂₂ , Q ₃₂ , ..., Q _{(m-1) 2} and Q _m2 having a smaller radius of curvature than Q _m1. Each of the n blocking sections 22 _-1 , 22 _-2 , 22 _-3 ,..., 22 _{− (n−1)} , 22 _{−n includes n} blocking sections 22 ₋₁ , 22 ₋₂ , 22 _{−3 ,.} 22 ₋₁ , 22 ₋₂ , 22 ₋₃ ,..., 22 _{− (n−1)} and 22 _−n are connected in series. The second holes Q ₁₂ , Q ₂₂ , Q ₃₂ ,..., Q _{(m−1) 2} , Q _m2 function as the current confinement means of the present invention.

FIG. 8A is a cross-sectional view illustrating in detail the structure of the unit fuse constituting the fuse element according to the second embodiment of the present invention. 8 (b) corresponds to FIG. 8 (a), in which four specific unit fuses are selected from the fuse elements shown in FIG. 7, and the current confinement means provided in the respective narrowing portions narrow band. It is a top view explaining in detail. That is, as shown in FIG. 8B, the blocking portion narrow band 22- _k is defined by the arc R _a on the right side and the arc R _b on the left side, and is substantially symmetrically shaped like a mortar. A second hole Q _j2 is provided as a current confinement means of the present invention in the center of the position where the narrow band 22- _k has the minimum width, thereby forming a cut-off promoting structure that reduces the I ² T value.

As shown in FIG. 8, the profile of the side is confined in a mortar shape so as to have a thickness _H measured in the series direction, a length H measured in the series direction, a minimum narrow band width P ₁ measured in the parallel direction, and a maximum width B. And a cut-off portion narrow band 22 _-k having a second hole Q _j2 as a current confinement means, and a cut-off portion narrow band 22 _-k connected to the cut-off portion narrow band 22 _-k and having a thickness _R and a length R measured in series. It shows that a unit fuse is constituted by a rectangular connecting band (heat radiation band) 21 _{-k of} width B measured in the direction. For this reason, the length P _L measured in the series direction of the unit fuses is H = R.

Similarly to the fuse element according to the first embodiment, the interrupting portions 22 ₋₁ , 22 ₋₂ , 22 ₋₃ ,..., 22 _{− (n−1)} and 22 _−n shown in FIG. The length measured in the series direction is 2.5 mm or less, and n through the connection bands (radiation bands) 21 ₋₁ , 21 ₋₂ , 21 ₋₃ ,..., 21 _{− (n−1)} , 21 _−n What is necessary is just to arrange in series. If it described with reference to the definition of the thickness shown FIG. 8 (a), the fuse element is cut off portion 22 _-1 according to the second embodiment, 22 _-2, 22 _-3, ..., 22 - _{( n-1),} a thickness of t _H = 10 to 60 [mu] m of 22 _-n, connecting bands (radiating _{band) 21 -1, 21 -2, 21} -3, ......, 21 - (n-1), 21 _-n thickness t _R = 80 to 150 μm is preferable, but is not necessarily limited thereto. Since the minimum narrow band width P ₁ depends on the thickness t _H of the blocking portion, considering the fine workability, the thickness t _H of the blocking portion is preferably 10 to 40 μm, and the parallel connection number P value and series connection In order to increase the value S, the thickness t _H of the blocking part is preferably about 10 to 30 μm.

Like the fuse element according to the first embodiment, in the fuse element according to the second embodiment, the connection bands (radiation bands) 21 ₋₁ , 21 ₋₂ , 21 ₋₃ ,..., 21 _{− (n-1),} by increasing the thickness t _R of 21 _-n, connecting bands (radiating _{band) 21 -1, 21 -2, 21} -3, ......, 21 - (n-1), 21 - _{By reducing} the resistance value of _n and increasing the mass of the coupling bands (heat radiation bands) 21 ₋₁ , 21 ₋₂ , 21 ₋₃ ,..., 21 _{− (n−1)} , 21 _−n (Heat radiation band) 21 ₋₁ , 21 ₋₂ , 21 ₋₃ ,..., 21 _{− (n−1)} , 21 _{−n Even if} the length R is small, the connection band (heat radiation band) 21 ₋₁ , 21 _{− 2} , 21 ₋₃ ,..., 21 _{− (n−1)} and 21 _−n can be ensured, which is preferable.

As shown in FIG. 7, the fuse element according to the second embodiment has an insulating substrate such as a ceramic substrate having a thickness of 0.8 mm to 1.5 mm (the insulating substrate is not shown in FIG. 7). However, refer to the insulating substrate 32 in FIGS. 9 to 11) to form a conductive thin film pattern. As the material of the ceramic substrate, alumina (Al ₂ O ₃ ), mullite (3Al ₂ O ₃ .2SiO ₂ ), beryllia (BeO), aluminum nitride (AlN), silicon carbide (SiC) described in the first embodiment are used. Etc. can be used. The conductive thin film is preferably a metal thin film, particularly copper (Cu) in view of low cost and ease of processing, but is not limited to copper. If it is a metal thin film, especially a copper thin film, the pattern of the fuse element according to the second embodiment can be easily formed by copper (Cu) plating and etching.

Similar to the fuse element according to the first embodiment, the fuse element according to the second embodiment also allows the second holes Q ₁₂ , Q ₂₂ , Q ₃₂ ,..., Q _{(m -1)} by providing the 2, Q _{m @ 2,} the second bore _{Q 12, Q 22, Q 32} , ......, compared to when there is no _{Q (m-1) 2,} Q m2, the equivalent I ² T value An improvement effect of reducing to a value of about 50 to 70% or less is obtained.

In the fuse element according to the second embodiment, the thicknesses t _H of the interrupting portions 22 ₋₁ , 22 ₋₂ , 22 ₋₃ ,..., 22 _{− (n−1)} and 22 _−n are reduced. For example, the number P of parallel connections can be increased to increase the P effect while the number S of series connections can be increased, so that the I ² T value can be reduced to 1/10 of the conventional fuse by utilizing the S effect to the maximum. Can also be reduced.

  As shown in FIG. 6, a plurality of fuse elements according to the second embodiment can be mounted inside the insulating tube to constitute a fuse cylinder.

As described above, according to the fuse element according to the second embodiment, by using the S and P effects together with the current constricting means, the I ² T value can be reduced to 1/10 that of the conventional fuse. Therefore, there is a margin in current in design. Therefore, the rated current can be increased by increasing the minimum narrow band width P ₁ while maintaining the I ² T value below the desired value. That is, since it is easy to double the rated current flowing through one fuse element, as shown in FIG. 6, the number of fuse elements used in the fuse element mounting structure is reduced to half or less, and the mounting structure ( It is possible to reduce the size and cost of the fuse cylinder).

7 and 8, the hole (first hole) Q _j1 and the current constricting means (second hole) Q _j2 have a circular or elliptical topology, but are only examples, and FIG. 7 and FIG. It is not limited to the topology shown. For example, the hole (first hole) Q _j1 may be hexagonal as shown in FIG. 9, the hole (first hole) Q _j1 may be rhombus as shown in FIG. Various polygons may be used.

FIG. 9 shows an example of a planar pattern of a fuse element according to a first modification of the second embodiment. As shown in FIG. 9, a basic structure is that a conductive thin film 31C is formed on the surface of a rectangular ceramic substrate 32 having electrical insulation. As shown in FIG. 9, the fuse element according to the first modification of the second embodiment of the present invention includes a plurality of (three in FIG. 9) hexagonal hole portions (3 in FIG. 9) arranged in parallel. The first hole) Q _ji , the hole portion (first hole) Q _ji each provided with a blocking portion narrow band sandwiched between both sides, and each blocking portion narrow band, one hole portion (first hole) Q P current paths (blocking portion narrow bands) are arranged in parallel by a circular second hole Q _j2 having a smaller area than _ji , and each of n (n = S is a positive integer) blocking portion is configured. Furthermore, n blocking portions are connected in series along the vertical direction of FIG. The second hole Q _j2 functions as the current confinement means of the present invention. Specifically, since both sides of the parallel blocking portion are concave portions having a hexagon halved, one blocking portion narrow band sandwiched between the leftmost concave portion and the hole portion (first hole) Q _ji , three holes (first hole) Q 2 interceptions portions narrow band sandwiched by _ji, and holes the one blocking portion narrow band sandwiched between the (first hole) Q _ji and far right of the recess In addition, this is a structure in which a blocking section narrow band of P = 4 is configured. Further, a plurality of sets (for example, 22 for 1500 V) are arranged in series via the connecting band (heat dissipating band).

In the fuse element according to the first modification example of the second embodiment as illustrated in FIG. 9, the energizing current normally flows through the conductive thin film 31C of the fuse element. As the means, each of the narrow portions of the interrupting portion having the second hole Q _j2 is melted, the arc voltage is increased, and the accident current is promptly interrupted.

FIG. 10 shows an example of a planar pattern of a fuse element according to a second modification of the second embodiment. As shown in FIG. 10, a basic structure is that a conductive thin film 31d is formed on the surface of a rectangular ceramic substrate 32 having electrical insulation. As shown in FIG. 10, the fuse element according to the second modification of the second embodiment of the present invention has a plurality of (three in FIG. 10) rhombus holes (first in FIG. 10) arranged in parallel. 1 hole) Q _ji , a hole (first hole) Q _ji is provided on each side of the blocking part narrow band sandwiched between the holes (first hole) Q _ji , and one hole part (first hole) Q _ji P current paths (blocking section narrow bands) are arranged in parallel by a circular second hole Q _j2 having a smaller area than each other, and n (n = S is a positive integer) blocking section. Furthermore, n blocking parts are connected in series along the vertical direction of FIG. The second hole Q _j2 functions as the current confinement means of the present invention. Specifically, since both sides of the parallel blocking portion are concave portions having a rhombus halved, one blocking portion narrow band sandwiched between the leftmost concave portion and the hole portion (first hole) Q _ji , _Combine two blocking section narrow bands sandwiched by three holes (first hole) Q _ji , and one blocking section narrow band sandwiched by hole (first hole) Q _ji and the rightmost recess. Thus, a structure in which a narrow section of the blocking portion of P = 4 is configured. Further, a plurality of sets (for example, 22 for 1500 V) are arranged in series via the connecting band (heat dissipating band).

In the fuse element according to the second modification of the second embodiment as illustrated in FIG. 10, the energization current normally flows through the conductive thin film 31d of the fuse element. As the means, each of the narrow portions of the interrupting portion having the second hole Q _j2 is melted, the arc voltage is increased, and the accident current is promptly interrupted.

However, considering the fine workability, the hole (first hole) Q _j1 is preferably a circle or an ellipse. Current confinement means (second hole) Q _j2 similarly, various polygons are adoptable, current confinement means (second hole) Q _j2 is smaller area than the hole (first hole) Q _j1 Therefore, as a _matter of course, the demand for adopting a circle or an ellipse is higher than in the case of the hole (first hole) Q _j1 .

(Other embodiments)
As described above, the present invention has been described according to the first and second embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various aspects and alternative embodiments, examples, and operational techniques will be apparent to those skilled in the art. Therefore, the present invention naturally includes various aspects and embodiments not described herein, and the technical scope of the present invention is determined by the invention specific matters according to the scope of claims reasonable from the above description. It is only determined.

1 is a schematic plan view (top view) illustrating a schematic configuration of a fuse element according to a first embodiment. 2A is a cross-sectional view for explaining in detail the structure (three-dimensional structure) of the unit fuse constituting the fuse element according to the first embodiment, and FIG. 2B corresponds to FIG. FIG. 5 is a plan view for explaining in detail the structure of four unit fuses. It is a typical top view (top view) explaining the relationship between a unit fuse and the whole fuse element. FIG. 4 is a diagram showing four types of aperture patterns, which are studied by calculating the resistance value of the entire breaking portion narrow band width per unit fuse in order to separate the S, P effect and the current confinement means, on the same plan view. It is. FIG. 5 is a diagram showing the effect of the two-stage diaphragm by the current constricting means by comparing the resistance value and the I ² T value of the entire breaking portion narrow band width per unit fuse for the four types of patterns shown in FIG. 4. 6A is a schematic cross-sectional view showing the mounting structure of the fuse element according to the first embodiment, and FIG. 6B shows three fuse elements housed (inserted) in the inner cap. FIG. It is a typical top view (top view) explaining schematic structure of the fuse element concerning a 2nd embodiment. FIG. 8A is a sectional view for explaining in detail the structure (three-dimensional structure) of the unit fuse constituting the fuse element according to the second embodiment, and FIG. 8B corresponds to FIG. FIG. 5 is a plan view for explaining in detail the structure of four unit fuses. It is a typical top view (top view) explaining the schematic structure of the fuse element which concerns on the modification (1st modification) of 2nd Embodiment. It is a typical top view (top view) explaining the schematic structure of the fuse element which concerns on the other modification (2nd modification) of 2nd Embodiment. It is a typical top view (top view) which shows an example of the improved type of a fuse element which the present inventors examined in the process leading to completion of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b, 1c ... Fuse element 2a, 2b ... Inner cap 3a, 3b ... Outer cap 4a, 4b ... Fuse terminal 5 ... Insulation tube 11, 12 ... Terminal part _21-1 , _21-2 , _21-3 , ... , 21- _(n-1) , 21 _-n ... coupling band (heat dissipation band)
22 ₋₁ , 22 ₋₂ , 22 ₋₃ ,..., 22 _{− (n−1)} , 22 _−n .
31C, 31d, 39 ... conductive thin film 32 ... insulating substrate (ceramic substrate)
Q ₁ , Q ₂ , Q ₃ ,..., Q _m−1 , Q _m ... hole Q _j1 , Q ₁₁ , Q ₂₁ , Q ₃₁ ,..., Q _{(m−1) 1} , Q _m1 . 1st hole)
_{Q j2, Q 12, Q 22} , Q 32, ......, Q (m-1) 2, Q m2 ... current confinement means (second hole)
Q ... Rhombus R _a , R _b ... Arc R _a1 , R _b1 ... First arc R _a2 , R _b2 ... Current constriction means (second arc)
V ... Separation hole

Claims (11)

An insulating substrate and a conductive thin film on the insulating substrate, and the conductive thin film is formed by alternately and periodically connecting a plurality of blocking portion narrow bands in parallel via a connecting band. A fuse element having a pattern connected in series to
The fuse element, wherein each of the plurality of blocking portion narrow bands includes current constricting means having a smaller area than a hole portion that separates the blocking portion narrow bands from each other in the parallel direction.   2. The fuse element according to claim 1, wherein the current constricting means is provided at a position where the narrowing width of the blocking portion narrow band is minimized.   The current confinement means is a notch pattern provided at a position where the narrowing width of the blocking portion narrow band is minimized, and each of the plurality of blocking portion narrow bands is provided by providing the notch pattern on a side portion. The fuse element according to claim 1, wherein the fuse element has a two-stage throttle structure. Each of the plurality of blocking portion narrow bands is separated from each other in the parallel direction by an arcuate hole,
2. The fuse element according to claim 1, wherein the notch pattern has a radius of curvature smaller than a radius of curvature of an arc that defines an outline of the blocking portion narrow band.   2. The fuse according to claim 1, wherein the current confinement means is a second hole provided in the center of the blocking portion narrow band at a position where the narrowing width of the blocking portion narrow band is minimized. element. An insulation tube that becomes a fuse cylinder;
The insulating thin film is housed in the insulating tube, and is composed of an insulating substrate and a conductive thin film on the insulating substrate, and the conductive thin film further connects a plurality of blocking portions arranged in parallel to each other in series. A fuse element having a pattern alternately and periodically connected in series via a belt,
Each of the plurality of blocking portion narrow bands includes current constricting means having a smaller area than a hole portion that separates the blocking portion narrow bands from each other in the parallel direction.   The fuse according to claim 6, wherein a plurality of the fuse elements are housed in parallel in the insulating tube.   The fuse according to claim 6 or 7, wherein the current confinement means is provided at a position where the constriction width of the blocking portion narrow band is minimized.   The current confinement means is a notch pattern provided at a position where the narrowing width of the blocking portion narrow band is minimized, and each of the plurality of blocking portion narrow bands is provided by providing the notch pattern on a side portion. The fuse according to claim 6 or 7, wherein the fuse has a two-stage throttle structure. Each of the plurality of blocking portion narrow bands is separated from each other in the parallel direction by an arcuate hole,
The fuse according to claim 6 or 7, wherein the notch pattern has a radius of curvature smaller than a radius of curvature of an arc that defines an outline of the blocking portion narrow band.   The said current confinement means is a 2nd hole provided in the center of the said interruption | blocking part narrow strip in the position where the narrowing width | variety of the said interruption | blocking part narrow strip becomes the minimum. Fuse.

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