JPH0850848A - Fuse resistor - Google Patents

Abstract

PURPOSE:To surely explode a fuse resistor in a short time with an overcurrent so as to surely break a current by covering a part of the surface of an insulating substrate with a heat accumulating material, and forming a part, which indirectly contacts with a heat generating resistor through the heat accumulating part, and a part, which directly contacts with the heat generating resistor. CONSTITUTION:A rectangular heat accumulating material 28 is overlaid on the roughly center of the surface of an insulating substrate 12. Next, a heat- generating resistor is overlaid on the heat accumulating material 28 and the insulating substrate 12, thus a direct contact part beta between the insulating substrate 12 and the heat generating resistor 14 and an indirect contact part alphathrough the heat accumulating material 14 are made. Hereby, in case that an overcurrent is let flow between electrode patterns 16 and 16 connected to an external terminal, the direct contact part beta of an insulating substrate 12 is heated to high temperature, and the indirect part alpha is heated to low temperature, laying a time lag. Therefore, the temperature distribution of the insulating substrate 12 is unequal, which generates thermal distortion, and the insulating substrate 12 explodes. Accordingly, it surely breaks the current in a short time.

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. 12 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 are formed, and external terminals 1 are formed on the lower ends of the electrode patterns 16 and 16.
8 and 18 are connected via solder 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 in the figure, it is 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. 13 and FIG. 14 which is an enlarged partial sectional view taken along 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. When an overcurrent flows through the resistor, the insulating substrate is crushed by the heat generation effect thereof, and the heating resistor is cut to cut off the overcurrent. A heat storage material is arranged on a part of the surface of the substrate, and an indirect contact portion that is in contact with the heating resistor through the heat storage material and a direct contact portion that is in direct contact with the heating resistor on the surface of the insulating substrate. And is provided.

For example, notches are formed on two opposite sides of the insulating substrate, and the heat storage material is arranged along a line connecting the notches. Alternatively, notches may be formed on two opposite sides of the insulating substrate, and the heat storage materials may be arranged on both sides of a line connecting the notches. Further, the heat storage material may be arranged on the front surface and the back surface of the insulating substrate, respectively. In this case, notches are formed on two opposite sides of the insulating substrate, the heat storage material is arranged on a front surface of the insulating substrate along a line connecting the notches, and both notches on the back surface of the insulating substrate are formed. It is desirable to dispose the heat storage material on both sides of the line connecting the heat storage materials. The heat storage material is made of glass such as high heat resistant alkaline lead-free glass.

[0010]

Operation: A heat storage material is disposed on a part of the surface of the insulating substrate, and an indirect contact portion that is in contact with the heating resistor via the heat storage material and a direct contact that is in direct contact with the heating resistor. When the heating resistor generates heat due to the application of overcurrent, this heat is directly transmitted to the direct contact part on the surface of the insulating substrate as it is, but the heat storage material is applied to the indirect contact part of the insulating substrate. Conducted via. Therefore,
The direct contact part of the insulating substrate is instantly heated to an extremely high temperature, while the indirect contact part conducts heat whose temperature has decreased to some extent with a certain time lag, so that it is possible to maintain a relatively low temperature. Become. As a result, on the surface of the insulating substrate, a portion heated to a high temperature and a portion heated to a low temperature are distributed, and the non-uniformity of the temperature distribution promotes thermal strain of the insulating substrate. Therefore, even if the resistance value of the heating resistor is suppressed to a relatively low value,
Alternatively, even when the mechanical strength of the insulating substrate is set to be relatively high, the insulating substrate can be completely shredded in an extremely short time.

[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.
Electrode patterns 16 and 16 for extraction made of g.Pd-based paste are adhered and formed, and 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 surface of the heating resistor 14 and the electrode patterns 16, 16 has a crossover glass 22 for preventing creeping discharge.
Are covered. 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. The resistance value of the heating resistor 14 is generally set in the range of several Ω to several tens of Ω, and particularly set to 5 Ω here.

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. A base type upper notch 24 is formed at the center of the upper side 12a of the insulating substrate 12, and an inverted base type lower notch 26 is formed at the center of the lower side 12b. This upper notch
The lower cutout portion 24 and the lower cutout portion 26 have substantially the same shape and size.

A rectangular heat storage material 28 is adhered and formed on the insulating substrate 12 substantially in the center of the surface on which the heating resistor 14 is adhered. The heat storage material 28 is made of glaze glass (high heat-resistant alkaline lead-free glass) used for a thermal head of a thermal transfer printer, and has a remarkably larger specific heat than the ceramic material forming the insulating substrate 12. .
The width W ₁ of the heat storage material 28 is set to be slightly wider than the width W ₂ of the bottom sides of the upper cutout portion 24 and the lower cutout portion 26.
A straight line connecting the apex 24a of the upper cutout 24 and the apex 26a of the lower cutout 26 of the insulating substrate 12 (hereinafter, referred to as "crushing line (a)").
Are arranged along. When the heating resistor 14 is adhered to the insulating substrate 12, as shown in FIG. 3 which is a sectional view taken along the line AA ′ of FIG. 1, a heat storage material is formed on the surface of the insulating substrate 12.
Portions that are indirectly contacted with the heating resistor 14 with 28 in between (hereinafter referred to as “indirect contact portions α”) and portions that are located on both sides of the indirect contact portion α and that are in direct contact with the heating resistor 14 (hereinafter “Direct contact part β”) will appear. In addition,
For convenience of illustration, FIG. 3 exaggerates the thickness of the first fuse resistor 10.

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).

The insulating substrate 12 is made of a ceramic material,
The surface is a rough surface having many fine irregularities. Therefore, the contact surface of the heating resistor 14 directly attached to the surface of the insulating substrate 12 will inevitably form a concavo-convex surface, and its resistance value will be a relatively high value. The amount of heat generated at that time increases accordingly. Then, the relatively high heat generated in the high resistance portion of the heating resistor 14 is directly transferred to the surface of the insulating substrate 12, so that the direct contact portion β of the insulating substrate 12 is instantly heated to an extremely high temperature. It will be.

On the other hand, the heat storage material 28 is made of glaze glass, and the surface thereof is extremely smooth. Therefore, the contact surface of the heating resistor 14 adhered to the surface of the heat storage material 28 is a smooth surface, and its resistance value is a relatively low value, so the amount of heat generated during overcurrent conduction is correspondingly small. Become. Since the relatively low heat generated in the low resistance portion of the heating resistor 14 is once stored in the heat storage material 28 and then conducted to the surface of the insulating substrate 12, the indirect contact portion α of the insulating substrate 12 A predetermined time difference (delay) occurs in heating, and the heat to be conducted itself is significantly reduced.

As a result of the above, when an overcurrent flows through the heating resistor 14, the indirect contact portion α along the rupture line (a) of the insulating substrate 12 maintains a relatively low temperature and is arranged on both left and right sides thereof. The formed direct contact portion β reaches an extremely high temperature, and the thermal strain of the insulating substrate 12 concentrates on the rupture line (a), so that the insulating substrate 12 can be completely crushed within 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.

4-6 show a second fuse resistor 30. The second fuse resistor 30 is characterized by the arrangement pattern of the heat storage material 28 adhered and formed on the surface of the insulating substrate 12, and other configurations are substantially the same as those of the first fuse resistor 10. Is equal to. That is, as shown in FIG. 5, a pair of heat storage materials are formed on the surface of the insulating substrate 12.
28, 28 are arranged on the left and right sides of the rupture line (a) with an interval 32 corresponding to the width W ₂ of the bottom side of the upper cutout 24 or the lower cutout 26 of the insulating substrate 12. As a result, in the second fuse resistor 30, as shown in FIG. 6 which is a sectional view taken along the line BB ′ of FIG. 4, the second fuse resistor 30 is directly contacted with the heating resistor 14 at a substantially central portion of the surface of the insulating substrate 12. When the contact part β appears,
Indirect contact portions α that are in contact with the heating resistor 14 indirectly appear with the heat storage material 28 sandwiched therebetween on the left and right sides thereof.

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, since the direct contact portion β on the surface of the insulating substrate 12 along the rupture line (a) forms a rough surface peculiar to the ceramic material, the resistance value of the heating resistor 14 in contact with this is compared. Higher, and this heating resistor
The relatively high heat from the high resistance part of 14 is directly conducted to heat it to an extremely high temperature. Further, the indirect contact portions α, α arranged on both sides of the direct contact portion β have the surfaces of the heat storage materials 28, 28 covering the surfaces thereof smooth,
The resistance value of the heating resistor 14 in contact with this is relatively low, and the relatively low heat from the low resistance portion of the heating resistor 14 is conducted via the heat storage materials 28, 28. , Will be maintained at a relatively low temperature. That is,
The second fuse resistor 30 is the same as the first fuse resistor 10 except that the arrangement of the high temperature heating portion and the low temperature heating portion appearing on the surface of the insulating substrate 12 is opposite to that of the first fuse resistor 10. In common with the first fuse resistor 10, thermal distortion of the insulating substrate 12 is promoted and the minimum breaking power of the fuse resistor is reduced. Can be played.

7 to 9 show the above-mentioned first fuse resistor.
10 shows a third fuse resistor 40 which is an application example of 10 and the second fuse resistor 30. As shown in FIG. 7, the third fuse resistor 40 has a heating resistor 14 formed on the front surface 12c of the insulating substrate 12 by coating electrode patterns 16, 16 on both sides of the heating resistor 14. And the electrode pattern 16,
At the lower end of 16, the second external terminals 42, the first branch 42 of the 42
a and 42a are connected via the solders 20 and 20, and
As shown in FIG.
And the electrode pattern is formed on both sides of the heating resistor 14.
16 and 16 are adhered and formed, and the second branch portions 42b and 42b of the second external terminals 42 and 42 are connected to the lower ends of the electrode patterns 16 and 16 via solders 20 and 20 to generate heat on both sides. The surface of the resistor 14 and the electrode pattern 16 is covered with a crossover glass 22. Heating resistor 14 on the front side 12c side of the insulating substrate and the back side 12d
Side heating resistor 14 is connected in parallel via the second external terminals 42, 42.

On the front surface 12c of the insulating substrate, as in FIG. 5, a pair of heat storage materials 28, 28 are separated by a predetermined space 32 and rupture (a).
As shown in FIG. 2, one heat storage material 28 is arranged along the rupture line (a) at the center of the back surface 12d of the insulating substrate. As a result, in the third fuse resistor 40, as shown in FIG. 9 which is a sectional view taken along the line CC ′ of FIG. 7, the heating resistor 14 is directly contacted with the central portion of the front surface 12c of the insulating substrate. Direct contact part β appears,
On both sides of this, indirect contact portions α that indirectly contact the heat generating resistor 14 via the heat storage material 28 appear. Also, the back surface 12d of the insulating substrate
In, in the vicinity of the center, an indirect contact portion α that indirectly contacts the heating resistor 14 via the heat storage material 28 appears, and a direct contact portion β that directly contacts the heating resistor 14 appears on both sides thereof. As a result, on the front surface 12c and the rear surface 12d of the insulating substrate in the third fuse resistor 40, the arrangement of the high-temperature heating unit and the low-temperature heating unit when the overheating current flows and the heating resistor 14 generates heat is staggered, Not only the non-uniformity of the temperature distribution on the same surface of the insulating substrate 12 but also the non-uniformity of the temperature distribution on different surfaces can be realized, so that both surfaces of the insulating substrate 12 are simultaneously heated, The thermal distortion of the insulating substrate 12 is further promoted, and the minimum cutoff power thereof can be further reduced. As shown in FIG. 9, the heat storage materials 28, 28 formed on the front surface 12c of the insulating substrate and the heat storage material 28 formed on the back surface 12d partially overlap each other via the insulating substrate 12. It doesn't matter.

In the third fuse resistor 40,
A second external terminal in which the extremity of the heat-generating resistor 14 on the front surface 12c side and the heat-generating resistor 14 on the rear surface 12d side of the insulating substrate is bifurcated.
Although they are connected in parallel via 42, it goes without saying that the same effect can be obtained by connecting both heating resistors 14, 14 in series. 10 and 11 show a fourth fuse resistor 50 as an example thereof. This fourth fuse resistor 50 has the heating resistor 14 formed on the front surface 12c of the insulating substrate by depositing it on the front surface 12c of the insulating substrate.
The heat generating resistor 14 slightly shorter than the heat generating resistor 14 on the side is adhered and formed. An electrode pattern 16 for taking out is connected to the left side of the heating resistor 14 on the front surface 12c side, a first external terminal 18 is connected to a lower end portion of the electrode pattern 16 via a solder 20, and The first strip portion 52a of the connection pattern 52 is connected to the right side of the resistor 14 (see FIG. 1).
0). An electrode pattern 16 for extraction is also connected to the left side of the heating resistor 14 on the back surface 12d side,
The first external terminal 18 is connected to the lower end of 16 via the solder 20, and the second strip portion 52b of the connecting pattern 52 is connected to the right side of the heating resistor 14 ( Figure 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 heat generating resistor 14 on the front surface 12c side and the heat generating resistor 14 on the rear surface 12d side are connected in series via the connecting pattern 52. In addition, each heating resistor 14,
The surface of the electrode pattern 16 and the connection pattern 52 is covered with a crossover glass 22 for preventing creeping discharge.

On the front surface 12c of the insulating substrate 12, as in FIG.
A pair of heat storage materials 28, 28 are arranged on the left and right of the rupture line (a) with a predetermined gap 32 therebetween, and the back surface 12 of the insulating substrate
Similarly to FIG. 2, one heat storage material 28 is also arranged in the center of d. As a result, in the fourth fuse resistor 50, as in FIG. 9, a direct contact portion β that directly contacts the heating resistor 14 appears near the center of the front surface 12c of the insulating substrate, and the heat storage material is provided on both sides of the direct contact portion β. Heating resistor 14 indirectly through 28
An indirect contact part α that comes into contact with appears. Also, the back of the insulating substrate
In 12d, an indirect contact portion α that indirectly contacts the heat generating resistor 14 via the heat storage material 28 appears near the center thereof, and a direct contact portion β that directly contacts the heat generating resistor 14 on both sides thereof.
Appears. That is, this fourth fuse resistor 50
Similar to the third fuse resistor 40, the arrangement of the high-temperature heating portion and the low-temperature heating portion when an overcurrent flows and the heating resistor 14 generates heat is staggered between the front surface 12c and the back surface 12d of the insulating substrate, Not only the non-uniformity of the temperature distribution on the same surface of the insulating substrate 12 but also the non-uniformity of the temperature distribution on different surfaces can be realized, so that both surfaces of the insulating substrate 12 are simultaneously heated, The thermal distortion of the insulating substrate 12 is further promoted, and the minimum cutoff power thereof can be further reduced.

[0024]

In the fuse resistor according to the present invention, the heat storage material is disposed on a part of the surface of the insulating substrate, and the surface of the insulating substrate is indirectly contacted with the heating resistor via the heat storage material. Since the indirect contact part and the direct contact part that is in direct contact with the heat generating resistor are provided, when the heat generating resistor generates heat due to overcurrent, the surface of the insulating substrate is heated to a high temperature part and a low temperature part. The portion to be heated is distributed, and the non-uniformity of this temperature distribution promotes thermal strain of the insulating substrate. Therefore, the insulating substrate can be completely shredded in an extremely short time without setting the resistance value of the heating resistor to an extremely high value 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 an enlarged cross-sectional view taken along the line A-A ′ of FIG.

FIG. 4 is a perspective view showing a second fuse resistor according to the present invention.

FIG. 5 is a perspective view showing an insulating substrate of a second fuse resistor.

FIG. 6 is an enlarged cross-sectional view taken along the line B-B ′ of FIG.

FIG. 7 is a perspective view showing a front surface side of a third fuse resistor according to the present invention.

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

9 is an enlarged cross-sectional view taken along the line C-C ′ of FIG. 7.

FIG. 10 is a perspective view showing a front surface side of a fourth fuse resistor according to the present invention.

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

FIG. 12 is a perspective view showing a conventional fuse resistor.

FIG. 13 is a perspective view showing an insulating substrate of a conventional fuse resistor.

FIG. 14 is an enlarged partial sectional view of D-D ′ in FIG. 13.

[Explanation of symbols]

 10 First fuse resistor 12 Insulating substrate 14 Heating resistor 24 Upper notch 24a Top notch 26 Lower notch 26a Lower notch 28 Heat storage material 30 Second fuse resistor 40 Third fuse resistor Unit 50 Fourth fuse resistor (a) Fracture line α Indirect contact part β Direct contact part

Claims (6)

[Claims] 1. An insulating substrate, comprising: 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 crushed by the heating action thereof. Then, in the fuse resistor configured to cut off the heating current by cutting off the overcurrent,
A heat storage material is disposed on a part of the surface of the insulating substrate, and an indirect contact portion that indirectly contacts the heating resistor via the heat storage material on the surface of the insulating substrate, and a direct contact that directly contacts the heating resistor. A fuse resistor having a contact portion. 2. The fuse resistor according to claim 1, wherein notches are formed on two opposite sides of the insulating substrate, and the heat storage material is arranged along a line connecting the notches. . 3. The fuse resistor according to claim 1, wherein cutouts are formed on two opposite sides of the insulating substrate, and the heat storage material is arranged on both sides of a line connecting the cutouts. vessel. 4. The fuse resistor according to claim 1, wherein the heat storage material is arranged on the front surface and the back surface of the insulating substrate, respectively. 5. A notch is formed on two opposite sides of the insulating substrate, the heat storage material is arranged on a front surface of the insulating substrate along a line connecting the notches, and both sides of the insulating substrate are provided on a back surface of the insulating substrate. The fuse resistor according to claim 4, wherein the heat storage material is arranged on both sides of a line connecting the cutouts. 6. The fuse resistor according to claim 1, wherein the heat storage material is made of glass.