JPH0877911A - Fusing resistor - Google Patents

Abstract

PURPOSE: To provide a fusing resistor which can securely interrupt passage of an overcurrent by an insulating board rupturing completely in a short time when the overcurrent flows. CONSTITUTION: By firmly attaching a smooth body 28 having smooth surfaces to the almost central part of the surface of an insulating board 12 on which many fine unevenness exist and coveringly attaching a heating resistance body 14 onto these, part of a coveringly-attached surface of the heating resistance body 14 is thereby made uneven to form high-resistance part α1, α2 the resistance value of which is comparatively high. Along with this, the other part of the coveringly-attaching surface is made smooth to form a low-resistance part β1 the resistance value of which is comparatively low. Thereby, when an overcurrent flows, parts touching the middle and high-resistance parts α1, α2 out of the surface 12 of the insulating board 12 are heated to an extremely high temperature while a part touching the low-resistance part β is heated at a low temperature in the surface of the insulating board 12, and thermal distortion of the insulating board is therefore promoted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention crushes the above-mentioned insulating substrate by the heating effect of the heating resistor adhered on the insulating substrate due to the passing of overcurrent, thereby cutting the heating resistor which is the current-carrying path. By doing so, the present invention relates to a fuse resistor configured to cut off the overcurrent energization.

[0002]

2. Description of the Related Art Conventionally, a fuse resistor 60 shown in FIG. 17 has been used as an overcurrent interruption means for protecting an electronic circuit element or the like from an overcurrent. This fuse resistor 60
A heating resistor 14 such as ruthenium oxide is formed on one surface of an insulating substrate 12 such as alumina or forsterite, and electrode patterns 16 for extraction are provided on both sides of the heating resistor 14.
16 is attached and connected, and external terminals 18, 18 are connected to the lower ends of the electrode patterns 16, 16 via solders 20, 20 and a conductive adhesive. Further, a base type upper notch 24 is formed in the center of the upper side 12a of the insulating substrate, and an inverted base type lower notch 26 is formed in the center of the lower side 12b of the insulating substrate.
Further, the surfaces of the heating resistor 14 and the electrode pattern 16 are covered with a crossover glass 22 for preventing creeping discharge.

This fuse resistor 60 has the above-mentioned external terminal 1
It is connected to an electronic circuit or a circuit element via 8 and 18. For example, although not shown, they are connected in series to a line such as a communication line or a power line leading to an electronic device, or connected in series to a gas arrester or the like inserted and connected between the lines.

However, if an electronic device is erroneously connected to a power source exceeding its rating, or if an overvoltage exceeding the rating is continuously applied to the line due to an overvoltage test or the like, the overvoltage is applied. The heating resistor 14 generates heat due to the overcurrent. Then, due to this heat generation effect, the insulating substrate 12 causes thermal strain, and is ruptured to the left and right along a straight line (a) connecting the apex 24a of the upper cutout 24 and the apex 26a of the lower cutout 26. As a result, the heating resistor 14 itself, which is a path for overcurrent, is also cut, so that the electronic device or the gas arrester is protected from continuous overcurrent.

[0005]

Therefore, in order to reliably protect the electronic device and the like from overcurrent, when the overcurrent flows through the heating resistor 14, the insulating substrate 12 is kept in a short time. It must be completely shredded. Here, in order to improve the crushing property of the insulating substrate 12, first, the above heating resistor is used.
It is conceivable to set the resistance value of 14 high and increase the amount of heat generated.However, if the resistance value of the heating resistor 14 is set too high, when the fuse resistor 60 is connected in series to the above line, transmission loss will occur. Becomes large, and when connected in series to a gas arrester or the like inserted and connected between the lines, a correspondingly higher voltage is applied to the electronic device side. Therefore, there is a certain limit in increasing the amount of heat generation by setting the resistance value of the heating resistor 14 high.

Next, the material and the thickness of the insulating substrate 12 are adjusted, or as shown in FIG. 18 and FIG. 19 which is an enlarged partial sectional view taken along the line DD ′ of FIG. It may be possible to make the insulating substrate 12 itself easily cracked by forming a groove 62 having a substantially V-shaped cross-section extending along the straight line (a) on the (14 forming surface), but it is damaged during manufacturing and during use. There is a certain limit to this as well.

The present invention has been made in view of the above-mentioned problems of the conventional example, and does not set the resistance value of the heating resistor to an extremely high value or make the insulating substrate extremely easy to crack without causing overcurrent. It is an object of the present invention to realize a fuse resistor which can completely break the insulating substrate in a short time when the current flows, and can reliably cut off the overcurrent.

[0008]

In order to achieve the above-mentioned object, a fuse resistor according to the present invention comprises an insulating substrate and a heating resistor attached to at least one surface of the insulating substrate. In a fuse resistor configured so that, when an overcurrent flows through a resistor, the insulating substrate is heated and shatters due to its heat generation effect, and thus the heating resistor is cut to cut off the overcurrent conduction. The heating resistor is composed of a combination of a high resistance portion having a relatively high resistance value and a low resistance portion having a resistance value lower than the high resistance portion.

The heating resistor is composed of, for example, one high resistance portion attached along the crushing direction of the insulating substrate and a pair of low resistance portions connected to both sides of the high resistance portion. Alternatively, the insulating substrate includes one low resistance portion attached along the crushing direction and a pair of high resistance portions connected to both sides of the low resistance portion. Further, heating resistors are respectively attached to the front surface and the back surface of the insulating substrate, and the heating resistor on the front side is one high resistance portion applied along the crushing direction of the insulating substrate, A pair of low-resistance portions connected to both sides of the high-resistance portion, and a heating resistor on the back side is attached to the insulating substrate along the crushing direction of the insulating substrate; It may be configured to include a pair of high resistance portions coupled to opposite sides of the portion. The high resistance portion of the heating resistor is formed, for example, by forming a part of the adhered surface to be uneven, and the low resistance portion is formed by forming the other part of the adhered surface to be smooth. To be done.

[0010]

[Function] The overall resistance value is increased by using the heating resistor having the high resistance portion and the low resistance portion as described above, instead of using the heating resistor having the uniform resistance value as a whole. It is possible to facilitate the crushing of the insulating substrate when overcurrent is applied without causing it. That is, when an overcurrent exceeding the rating flows through the heating resistor, a relatively high amount of heat is generated in the high resistance portion, and the surface of the insulating substrate that is in contact with the high resistance portion is heated to a high temperature. On the other hand, in the low resistance part of the heating resistor, the amount of heat generated when an overcurrent is applied is smaller than in the high resistance part, and the surface of the insulating substrate in contact with the low resistance part is heated at that low temperature. . As described above, on the surface of the insulating substrate, a portion heated to a relatively high temperature and a portion heated to a relatively low temperature are distributed, and due to the non-uniformity of the temperature distribution, thermal strain of the insulating substrate is caused. It is encouraged. Therefore, even if the resistance value of the entire heating resistor is suppressed to a relatively low value, or even if the mechanical strength of the insulating substrate is set to a relatively high value, it is possible to insulate within a very short time. It is possible to completely crush the substrate.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiments. FIG. 1 shows a first fuse resistor 10 according to the present invention, in which one surface of an insulating substrate 12 made of a ceramic such as alumina, forsterite, steatite, etc. has a rectangular heat generation of ruthenium oxide or the like. Resistor
14 is adhered and formed, and A is provided on both sides of the heating resistor 14.
The extraction electrode patterns 16 and 16 made of g.Pd-based paste or the like are adhered and connected, and the first external terminals 18 and 18 are connected to the lower ends of the electrode patterns 16 and 16 via solders 20 and 20. It will be done. The overall resistance value of the heating resistor 14 is generally set within a range of several Ω to several tens of Ω, and here it is particularly set to 5 Ω. The surfaces of the heating resistor 14 and the electrode patterns 16 and 16 are covered with a crossover glass 22 for preventing creeping discharge.

FIG. 2 shows the insulating substrate 12. The insulating substrate 12 has a rectangular shape with a length of 16 mm and a width of 9.86 mm, and its plate thickness is set to 0.635 mm. An upper base notch 24 is formed at the center of the upper side 12a of the insulating substrate 12, and an inverted base lower notch 26 is formed at the center of the lower side 12b. The upper cutout portion 24 and the lower cutout portion 26 have substantially the same shape and size.

A rectangular smoothing body 28 is fixed to the insulating substrate 12 at approximately the center of the surface on which the heating resistor 14 is adhered. The smooth body 28 is made of glaze glass (high heat resistance alkaline lead-free glass) used for a thermal head of a thermal transfer printer. The width W1 of this smooth body 28
Is set to be slightly wider than the lateral width W2 of the bottom of the upper cutout 24 and the lower cutout 26, and the upper cutout of the insulating substrate 12 is
It is arranged along a straight line (hereinafter, referred to as "crushing line (a)") connecting the apex 24a of 24 and the apex 26a of the lower cutout 26. The smooth body 28 is formed by depositing a glass paste as a material on the surface of the insulating substrate 12 and firing it at a predetermined temperature.

The heating resistor 14 is fired by depositing a ruthenium-based paste on the surface of the insulating substrate 12 by printing or the like and heating it at a predetermined temperature. As a result, as shown in FIG. 3 which is a sectional view taken along the line AA ′ of FIG.
In the heating resistor 14, portions α1 and α2 contacting the surface of the insulating substrate 12 and a portion β1 contacting the surface of the smooth body 28 will appear. Note that, in FIG. 3, the crossover glass 22 is not shown for convenience of illustration. The same applies to FIGS. 7 and 10 described later.

Although not shown, the first fuse resistor 10 is connected to a protected element or a protected circuit via the first external terminals 18, 18. Then, when an overcurrent flows between the first external terminals 18, 18, the heating resistor 14 generates heat to heat the surface of the insulating substrate 12, causing thermal distortion of the insulating substrate 12 to cause the crushing wire. It is crushed to the left and right along (a). As a result, the heating resistor 14, which is a current-carrying path, is also disconnected, so that the first external terminals 18, 18 are electrically disconnected from each other.

Since the insulating substrate 12 is made of a ceramic material, as shown in FIG. 4 which is an enlarged partial sectional view, the surface of the insulating substrate 12 forms a rough surface having many fine irregularities. Therefore, the adhered surfaces of the portions α1 and α2 of the heating resistor 14 that come into contact with the surface of the insulating substrate 12 inevitably form uneven surfaces, and the resistance values of the portions α1 and α2 are relatively high values. Becomes On the other hand, since the surface of the smooth body 28 is a smooth surface with almost no unevenness, the adhered surface of the heating resistor portion β1 contacting this is also a substantially smooth surface and the resistance value of the portion β1. Is a relatively low value.

Therefore, when an overcurrent exceeding the rating flows through the heating resistor 14 via the first external terminals 18, 18,
In the heating resistor 14, the amount of heat generated in the high resistance portions α1 and α2 contacting the surface of the insulating substrate 12 is relatively large, whereas the amount of heat generation in the low resistance portion β1 contacting the surface of the smooth plate 28 is Relatively less. Moreover, the high resistance portion α of the heating resistor 14
Since the heat of relatively high temperature generated in 1 and α2 is directly conducted to the insulating substrate 12, the surface of the insulating substrate 12 is heated to an extremely high temperature. On the other hand, heating resistor
The heat at the relatively low temperature generated in the low resistance portion β1 of 14 is once conducted to the insulating substrate 12 via the smooth body 28. The smooth body 28 made of this glaze glass has a much larger specific heat than the ceramic material forming the insulating substrate 12, and exhibits a so-called heat storage effect. Therefore, the low resistance portion β1 of the heating resistor 14 originally generated. The heat of the low temperature reaches the surface of the insulating substrate 12 after being further attenuated by passing through the smoothing body 28.
The surface temperature of is almost unchanged.

As described above, when an overcurrent flows through the heating resistor 14, the portion along the rupture line (a) of the insulating substrate 12 (the portion where the smooth body 28 is adhered) has a relatively low temperature. While maintaining, the parts arranged on both the left and right sides (the parts in contact with the heating resistor 14) reach an extremely high temperature, and the thermal strain of the insulating substrate 12 concentrates on the rupture line (a). It can be completely crushed in an extremely short time. That is, the first fuse resistor 10 realizes the non-uniformity of the temperature distribution on the same surface of the insulating substrate 12 and promotes the thermal distortion of the insulating substrate 12, thereby reducing the minimum breaking power thereof. There is.

5-7 show a second fuse resistor 30. The second fuse resistor 30 is characterized by the arrangement pattern of the smooth body 28 fixed to the surface of the insulating substrate 12, and the other structure is substantially the same as that of the first fuse resistor 10. It is a thing. That is, as shown in FIG. 6, a pair of smooth bodies 28,
28 is the upper cutout 24 or the lower cutout 26 of the insulating substrate 12.
Are arranged on the left and right sides of the rupture line (a) at intervals 32 corresponding to the width W2 of the bottom side of the As a result, in the second fuse resistor 30, as shown in FIG. 7 which is a sectional view taken along line BB ′ of FIG. 5, the substantially central portion of the surface of the insulating substrate 12 is covered with the portion α3 of the heating resistor 14. At the same time, the left and right sides are covered with smooth bodies 28, 28. In addition, the surfaces of the smooth bodies 28, 28 have a portion β of the heating resistor.
It is covered with 2, β3.

When an overcurrent flows between the first external terminals 18 and 18 of the second fuse resistor 30, the heating resistor 14 generates heat and the surface of the insulating substrate 12 is heated, and the insulating substrate 12 is heated. Causes thermal strain, and is fractured left and right along the fracture line (a). At this time, in the surface of the insulating substrate 12, the heating resistor 14
In the portion covered with the portion α3, there are many fine irregularities on the surface of the insulating substrate 12, and the adhered surface of the portion α3 of the heating resistor 14 that covers this also inevitably forms irregularities. ,
Since the resistance value of the portion α3 becomes relatively high, and the heat of the relatively high temperature from the high resistance portion α3 of the heating resistor 14 is directly conducted, it is heated to an extremely high temperature. Further, in the portion of the surface of the insulating substrate 12 covered by the smooth bodies 28, 28, the surfaces of the smooth bodies 28, 28 form a smooth surface, and the portions β2, β3 of the heating resistor 14 which cover the surface.
The surface to be adhered to is inevitably smooth, and its resistance value is relatively low, and the low resistance parts β2 and β3 of this heating resistor 14 are
The heat of the relatively low temperature generated in 1 is indirectly conducted via the smooth bodies 28 having the heat storage effect, so that the heat is maintained at a relatively low temperature.

That is, this second fuse resistor 30
Although the arrangement of the high resistance portion and the low resistance portion of the heating resistor 14 is opposite to that of the first fuse resistor 10, the nonuniform temperature distribution is realized on the same surface of the insulating substrate 12. These are common in points, and similar to the first fuse resistor 10, thermal distortion of the insulating substrate 12 is promoted and the minimum breaking power of the fuse resistor can be reduced.

FIGS. 8 to 10 show a third fuse resistor 40 which is an application example of the first fuse resistor 10 and the second fuse resistor 30. As shown in FIG. 8, the third fuse resistor 40 is provided on the front surface 12c of the insulating substrate 12.
The heating resistor 14F on the front side is adhered and formed on the
Electrode patterns 16 and 16 are attached to both sides of 14F, and first branch portions 42a and 42a of the second external terminals 42 and 42 are soldered to the lower ends of the electrode patterns 16 and 16 via solders 20 and 20, respectively. 9A and 9B, a heating resistor 14B on the back side is adhered and formed on the back surface 12d of the insulating substrate 12 as shown in FIG.
Electrode patterns 16 and 16 are attached to both sides of B, and the second external terminals 42 and 42 are connected to the lower ends of the electrode patterns 16 and 16.
The branch portions 42b and 42b of the above are connected via the solders 20 and 20, and the surfaces of the heating resistors 14F and 14B on both sides and the electrode pattern 16 are covered with the crossover glass 22. The heat generating resistor 14F on the front side and the heat generating resistor 14B on the back side are connected in parallel via the second external terminals 42, 42.

On the front surface 12c of the insulating substrate, as in FIG. 6, a pair of smooth bodies 28, 28 are separated by a predetermined space 32 so that a rupture line (a) is formed.
In addition to being arranged on the left and right sides of the same, one smooth body 28 is also arranged along the rupture line (a) at the center of the back surface 12d of the insulating substrate, as in FIG. As a result, the third fuse resistor 40 is a cross-sectional view taken along the line CC ′ of FIG.
As shown in 0, the substantially central portion of the front surface 12c of the insulating substrate is covered with the high resistance portion α4 of the front surface side heating resistor 14F, and the left and right side portions thereof are covered with the smooth bodies 28, 28. , 28 are covered with low resistance portions β4, β5 of the front side heating resistor 14F. Further, in the back surface 12d of the insulating substrate, the substantially central portion thereof is covered with the smooth body 28, and the surface of the smooth body 28 is covered with the back side heating resistor.
The low resistance portion β6 of 14B is covered, and both sides thereof are covered by the high resistance portions α5 and α6 of the backside heating resistor 14B. That is, in the third fuse resistor 40, not only "high resistance portion" and "low resistance portion" are alternately generated in the front side heating resistor 14F and the back side heating resistor 14B, respectively. The "high resistance portion" of one heating resistor and the "low resistance portion" of the other heating resistor are positioned so as to substantially correspond to each other with the insulating substrate 12 interposed therebetween.

When an overcurrent more than the rating flows through the third fuse resistor 40 having such a configuration through the second external terminals 42, 42, the front side heating resistor 14F and the rear side heating resistor Since the body 14B generates heat and both surfaces of the insulating substrate 12 are heated at the same time, the insulating substrate 12 causes thermal strain and is crushed to the left and right along the rupture line (a). At this time, in the third fuse resistor 40, as described above, the high resistance part α4 and the low resistance parts β4, β5 of the front side heating resistor 14F are used.
However, since it corresponds to the low resistance portion β6 and the high resistance portions α5 and α6 of the backside heating resistor 14B with the insulating substrate 12 interposed therebetween, only the non-uniformity of the temperature distribution on the same surface of the insulating substrate 12 is considered. As a result, the non-uniformity of temperature distribution between different surfaces can be realized. As a result, the thermal strain of the insulating substrate 12 is further promoted, and the minimum breaking power thereof can be further reduced.

In the third fuse resistor 40,
The front side heating resistor 14F and the back side heating resistor 14B are connected in parallel via the second external terminals 42, 42 whose ends are bifurcated, but even if both heating resistors are connected in series. It goes without saying that the same effect can be obtained. 11 and 1
2 shows a fourth fuse resistor 50 as an example thereof. The fourth fuse resistor 50 has a front side heating resistor 14F formed on the front side 12c of the insulating substrate, and a front side heating resistor 14F on the back side 12d of the insulating substrate.
The back side heating resistor 14B, which is slightly shorter than the above, is attached and formed. An electrode pattern 16 for extraction is connected to the left side of the front side heating resistor 14F, a first external terminal 18 is connected to a lower end portion of the electrode pattern 16 via a solder 20, and the front side heating resistor 14F is heated. The first strip portion 52a of the connection pattern 52 is connected to the right side of the resistor 14F (FIG. 11). Further, the electrode pattern 16 for taking out is connected to the left side of the rear side heating resistor 14B, the first external terminal 18 is connected to the lower end portion of the electrode pattern 16 via the solder 20, and the rear side The second band portion 52b of the connection pattern 52 is connected to the right side of the side heating resistor 14B (see FIG. 1).
1). The first strip portion 52a and the second strip portion 52b of the connection pattern 52 are connected to each other via a connection strip 52c that is routed from the side edge 12e of the insulating substrate 12 across the upper portion of the rear surface 12d. Therefore, as a result, the front side heating resistor 14F and the back side heating resistor 14B are connected in series via the connection pattern 52. The surface of each heating resistor 14 and the like is covered with a crossover glass 22 for preventing creeping discharge.

In the above description, the smoothing body 28 is fixed to a part of the surface of the insulating substrate 12 having a large number of fine irregularities, and the heating resistor 14 is adhered on the smoothing body 28, whereby the heating resistor is formed.
While a part of the adherend surface of 14 is formed in a concavo-convex shape to realize a high resistance part of the heating resistor 14, while the other part of the adherend surface is formed to be a smooth surface to realize a low resistance part. However, the present invention is not limited to this. For example, as shown in FIG. 13, instead of fixing the smooth body 28, a part of the surface of the insulating substrate 12 is finished into a smooth surface 12f by means of polishing or the like, and an uneven surface 12g is left on the other part. , By attaching the heating resistor 14 on top of it,
The high resistance part α7 and the low resistance part β7 may be realized. Alternatively, by means such as cutting or pressing, as shown in FIG. 14, the unevenness degree of the part 12h of the surface of the insulating substrate 12 is made larger than the unevenness degree of the other part 12i, and the heating resistor is formed thereon. The high resistance portion α8 and the low resistance portion β8 of the heat generating resistor 14 may be realized by attaching 14 to each other.

Further, as described above, by adjusting the state of the insulating substrate 12 side, instead of controlling the distribution of the resistance value of the heating resistor 14 deposited thereon, as shown in FIG. , A first resistive material 14X having a relatively high resistance value on a part of the surface of the insulating substrate 12 (the central part in the figure)
And a second resistance material 14Y having a relatively low resistance value on other parts (left side and right side in the drawing),
14Y is adhered and each resistance substance is connected / integrated to form the heating resistor 14, and the first resistance substance 14X is connected to the high resistance portion α9.
Then, the second resistance materials 14Y and 14Y may be formed into the low resistance portions β9 and β10, respectively. Alternatively, instead of using two types of resistance materials having different resistance values as described above, one type of resistance material is used to form the heating resistor and the thickness thereof is partially made different, so that the high resistance portion is formed. And a low resistance part may be realized. FIG. 16 shows an example thereof, in which the central portion of the heating resistor 14 adhered to the surface of the insulating substrate 12 is formed relatively thick to form a low resistance portion β11, and the left and right side portions thereof are relatively formed. It is made thin and consists of high resistance parts α10 and α11.

[0028]

In the fuse resistor according to the present invention, since the heat generating resistor having the high resistance portion and the low resistance portion is used, when the heat generating resistor generates heat due to the application of overcurrent, it is insulated. On the surface of the substrate, a portion that is heated to a relatively high temperature because it is in contact with the high resistance portion and a portion that is heated to a relatively low temperature because it is in contact with the low resistance portion are distributed. The thermal strain of the insulating substrate is promoted. Therefore, the insulating substrate can be completely shredded in an extremely short time without setting the resistance value of the entire heating resistor to be extremely high or making the insulating substrate extremely easy to crack.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first fuse resistor according to the present invention.

FIG. 2 is a perspective view showing an insulating substrate of a first fuse resistor.

FIG. 3 is a cross-sectional view taken along the line A-A ′ in FIG.

FIG. 4 is an enlarged partial cross-sectional view showing a joint portion between the insulating substrate and the heating resistor of the first fuse resistor.

FIG. 5 is a perspective view showing a second fuse resistor according to the present invention.

FIG. 6 is a perspective view showing an insulating substrate of a second fuse resistor.

7 is a cross-sectional view taken along the line B-B ′ of FIG.

FIG. 8 is a perspective view showing a front surface side of a third fuse resistor according to the present invention.

FIG. 9 is a perspective view showing a back side of a third fuse resistor.

10 is a cross-sectional view taken along the line C-C ′ of FIG.

FIG. 11 is a perspective view showing a front surface side of a fourth fuse resistor according to the present invention.

FIG. 12 is a perspective view showing the back side of a fourth fuse resistor.

FIG. 13 is an enlarged partial cross-sectional view showing another example of the joint portion between the insulating substrate and the heating resistor.

FIG. 14 is an enlarged partial cross-sectional view showing another example of the joint portion between the insulating substrate and the heating resistor.

FIG. 15 is a cross-sectional view showing a modified example of a heating resistor.

FIG. 16 is a cross-sectional view showing a modified example of the heating resistor.

FIG. 17 is a perspective view showing a conventional fuse resistor.

FIG. 18 is a perspective view showing an insulating substrate of a conventional fuse resistor.

FIG. 19 is an enlarged partial sectional view taken along the line D-D ′ of FIG. 18.

[Explanation of symbols]

 10 First fuse resistor 12 Insulating substrate 14 Heating resistor 14F Front heating resistor 14B Rear heating resistor 14X First resistance substance 14Y Second resistance substance 28 Smoothing body 30 Second fuse resistor 40th Fuse resistor No. 3 50 Fuse resistor No. 4 (a) Fracture line α1 to α11 High resistance part of heating resistor β1 to β11 Low resistance part of heating resistor

Claims (5)

[Claims] 1. An insulating substrate, and a heating resistor attached to at least one surface of the insulating substrate. When an overcurrent flows through the heating resistor, the insulating substrate is heated by its heat generating action. In a fuse resistor configured to be crushed and cut, whereby the heating resistor is cut to cut off the overcurrent conduction, the heating resistor has a high resistance portion having a relatively high resistance value, A fuse resistor comprising a combination with a low resistance portion having a resistance value lower than that of the high resistance portion. 2. The heating resistor comprises one high resistance portion adhered along the crushing direction of the insulating substrate, and a pair of low resistance portions connected to both sides of the high resistance portion. The fuse resistor according to claim 1, wherein: 3. The heating resistor comprises one low resistance portion adhered along the crushing direction of the insulating substrate, and a pair of high resistance portions connected to both sides of the low resistance portion. The fuse resistor according to claim 1, wherein: 4. A heating resistor is attached to each of the front surface and the back surface of the insulating substrate, and the heating resistor on the front side is
The heat generating resistor on the back side is composed of one high resistance portion applied along the crushing direction of the insulating substrate and a pair of low resistance portions connected to both sides of the high resistance portion, and the heating resistor on the back side is the insulating substrate. 2. The fuse resistor according to claim 1, wherein the fuse resistor comprises one low resistance portion deposited along the crushing direction and a pair of high resistance portions connected to both sides of the low resistance portion. 5. The high resistance portion of the heating resistor is formed by forming a portion of the surface to be adhered of the heating resistor to be uneven, and the other portion of the surface to be attached is made smooth. The fuse resistor according to any one of claims 1 to 4, wherein a low resistance portion of the heating resistor is formed.