JPH0696659A - Fuse resistor - Google Patents

Abstract

PURPOSE:To cut off the supply of overcurrent by ensuring the rupture of an insulation base plate in a short time, upon the start of the overcurrent flow, without any need of setting the resistance value of a heat generating resistance body at an extremely high level, and making the base plate itself extremely breakable. CONSTITUTION:This fuse resistor 2 is constituted in such a way that an insulation substrate 4 is provided, and the first and second heat generating resistance bodies 10 and 12 are formed on the first plane 8 thereof. Furthermore, constitution is so made that when overcurrent flows across both resistance bodies 10 and 12, the base plate 4, ruptures due to the occurrence of thermal strain caused by the heat generating action of the bodies 10 and 12, thereby cutting both bodies 10 and 12 for the interruption of the overcurrent flow. In this case, the first spring member 6 is provided to energize the base board 4 in a direction to facilitate the rupture thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating resistor adhered and formed on an insulating substrate, and the insulating substrate is crushed by the heat generation effect of passing an overcurrent. The present invention relates to a fuse resistor configured to cut off the flow of current.

[0002]

2. Description of the Related Art Conventionally, a fuse resistor 70 shown in FIG. 9 has been used as an overcurrent interruption means for protecting an electronic circuit element or the like from an overcurrent. This fuse resistor 70
On one surface of the insulating substrate 72 such as alumina or forsterite,
A heating resistor 74 such as ruthenium-based paste is adhered and formed,
Electrode patterns 76 for extraction on both sides of the heating resistor 74,
76 is connected, and external terminals 78, 78 are connected to the electrode patterns 76, 76.

Although not shown, the fuse resistor 70 is connected in series via the external terminals 78, 78 to a line forming a communication line or a power supply line leading to, for example, an electronic device. However, if an electronic device is mistakenly connected to a power source exceeding its rating, or if an overvoltage is continuously applied to the line due to an overvoltage test, etc., the heat generated by the overcurrent due to the application of the overvoltage. The resistor 74 generates heat. Then, due to this heat generation effect, the insulating substrate 72 causes thermal distortion and is ruptured to the left and right along the two-dot chain line (b). As a result, the heating resistor 74 itself, which is a path for the overcurrent, is also cut, so that the continuous overcurrent is cut off and the electronic device can be protected.

FIGS. 10 and 11 show a fuse resistor 80 according to another conventional example. The first surface of an insulating substrate 82 is shown in FIG.
A heating resistor 86 is adhered to 84, and a conductive pattern 90 is adhered to the second surface 88. And the heating resistor
Extraction electrode patterns 91, 91 are connected to both sides of 86, and a first external terminal 92 and a second external terminal 93 are connected to the extraction electrode patterns 91, 91. In addition, a third external terminal 94 and a fourth external terminal are provided on both ends of the conductive pattern 90.
95 is connected. In addition, in order to facilitate the crushing of the insulating substrate 82, a cutout portion 96 is formed on the lower side of the insulating substrate 82.

In the double-sided use type fuse resistor 80, as shown in FIG. 12, for example, a third external terminal 94, a fourth external terminal 95 and a first external terminal 92 are electronic circuits of an electronic device ( The second external terminal is connected to the other end of the surge absorbing element 97, one end of which is connected to the line A ′, while being connected to the line A that constitutes a power supply line leading to the power line.
As a result, the conductive pattern 90 is connected to the line A in series, and the heating resistor 86 is connected to the surge absorbing element 97 in series. Then, when a continuous overvoltage is applied to the lines A and A ′, the heating resistor 86 generates heat and the insulating substrate 82 is ruptured left and right along the extension line (C) of the apex of the cutout 96. (FIG. 10). As a result, the heat generating resistor 86 is cut and the surge absorbing element 97 is separated from the line A, so that the element 97 can be prevented from being burned or the like due to continuous overcurrent. At the same time, the conductive pattern 90 is also cut and the line A itself is cut off, so that it is possible to prevent an overvoltage from being applied to the electronic circuit side after the surge absorbing element 97 is separated.

[0006]

Therefore, in order to reliably protect the electronic device, the surge absorbing element, and the like from overvoltage and overcurrent, when the overcurrent flows through the heating resistor, the insulating substrate is It is necessary to surely crush in a short time. However, this point has not always been satisfactory in the past. That is, even though the overcurrent is flowing, the insulating substrate is not sufficiently shredded, so that the overcurrent may continue to flow and the electronic device or the like may be destroyed. Further, in the double-sided fuse resistor, only the heat-generating resistor is cracked, and there is a risk that the conductive pattern on the back surface is intact and maintains the conductive state.

Here, in order to ensure the crushing of the insulating substrate, it is conceivable to set the resistance value of the heating resistor to a high value to increase the amount of heat generated. However, if the resistance value of the heating resistor is set too high, the transmission loss becomes large when the fuse resistor is connected in series to the above line, and when the line is connected between the above lines, a high voltage is generated by that amount. It will be added to the equipment side. Therefore, there is a certain limit to the method of facilitating the crushing of the insulating substrate by adjusting the resistance value of the heating resistor. On the other hand, it may be possible to make the insulating substrate itself easily cracked by appropriately setting the material, shape and dimensions (especially thickness) of the insulating substrate, but if the insulating substrate itself is configured to be too easily cracked, it will be damaged during the manufacturing process. There is a certain limit to this as it becomes easier.

The present invention has been made in view of the above-mentioned problems of the conventional example, without setting the resistance value of the heating resistor to an extremely high value or making the insulating substrate itself extremely easy to crack. It is an object of the present invention to realize a fuse resistor capable of reliably crushing an insulating substrate within a short time when an overcurrent flows and cutting off the overcurrent.

[0009]

In order to achieve the above-mentioned object, a fuse resistor according to the present invention comprises an insulating substrate and a heating resistor adhered to the surface of the insulating substrate. When an overcurrent flows through the resistor, the insulating substrate causes thermal strain and ruptures due to the heat generating action of the heating resistor, so that the heating resistor is cut and the overcurrent is cut off. In the fuse resistor described above, an urging means for urging the insulating substrate is provided in a direction of promoting the crushing of the insulating substrate. The biasing means is composed of, for example, a spring member.

[0010]

When an overcurrent flows through the heating resistor, the heating resistor generates heat and the surface of the insulating substrate on which the heating resistor is formed expands and the opposite surface contracts, causing thermal stress. Therefore, by urging the insulating substrate in the direction of promoting the crushing by the urging means, that is, in the direction of thermal stress, the insulating substrate is crushed reliably. As a result, the heating resistor itself is also cut, so that the overcurrent conduction is cut off.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiments. 1 is a schematic perspective view showing an embodiment of a fuse resistor 2 according to the present invention, and FIG. 2 is a schematic side view thereof. The fuse resistor 2 includes an insulating substrate 4 formed of a ceramic such as alumina, forsterite, steatite, and a first spring member 6 as a biasing means for biasing the insulating substrate 4 in a certain direction. To have.

As shown in FIG. 3, the first part of the insulating substrate 4 is
A first heating resistor 10 and a second heating resistor 12 made of ruthenium (Ru) -based paste or the like are deposited and formed on the surface 8 at regular intervals therebetween. The resistance value of each of the first heating resistor 10 and the second heating resistor 12 is 6Ω.
It is set to a degree. A first electrode pattern 14 is connected to the upper end side of the first heating resistor 10, and a first extraction electrode pattern 16 is connected to the lower end side thereof. Further, the second electrode pattern 18 is connected to the upper end side of the second heating resistor 12, and the second extraction electrode pattern 20 is connected to the lower end side thereof. Each of these electrode patterns is made of Ag / Pd-based paste or the like. Then, between the first electrode pattern 14 and the second electrode pattern 18
A chip-type silicon surge absorber 22 fixed to the first surface 8 of the insulating substrate 4 is connected to the. As shown in FIG. 4, on the second surface 24 of the insulating substrate 4, a conductive pattern 26 made of Ag / Pd based paste or the like is deposited. Although not shown, the first heating resistor 10 and the second heating resistor 10 are not shown.
The surfaces of the heating resistor 12 and the conductive pattern 26 are covered with a glass film for preventing creeping discharge.

The first extraction electrode pattern 16 has a first
External terminals 28 are connected by soldering or the like.
A second external terminal 30 is formed on the second extraction electrode pattern 20.
Are similarly connected. One end 32 of the conductive pattern 26
A third external terminal 34 is similarly connected to. The first external terminal 28 is similarly connected to the other end 36 of the conductive pattern 26. On both sides of the insulating substrate 4,
Notches 38, 38 are formed to facilitate crushing.

As shown in FIG. 5, the first spring member 6 has a pressing portion 40 having a substantially U-shaped cross section and an engaging portion 42 having a substantially inverted U-shaped cross section, and the above-mentioned pressing portion is provided. Part 40 and engaging part
In the vicinity of the boundary with 42, a punched hole 44 having an area slightly larger than the area of the chip type silicon surge absorber 22 is provided.
Are formed. The first spring member 6 is made of stainless steel or the like.

The insulating substrate 4 is erected on the base 46 with both surfaces sandwiched between fixing blocks 48, 48, 48 provided on the upper surface of the base 46. Then, the engaging portion 42 of the first spring member 6 is engaged with the upper end side of the insulating substrate 4. At this time, the chip-type silicon surge absorber 22 fixed on the insulating substrate 4 is positioned so as to protrude from the punching hole 44 formed in the first spring member 6 to the inside of the pressing portion 40. As a result, the pressing part
One surface of 40 is substantially in contact with the first surface 8 of the insulating substrate 4. The other surface of the pressing portion 40 is arranged so as to contact the inner surface of the cover 50 that covers the base 46. In this case, the pressing portion 40 of the first spring member 6 is arranged in a slightly compressed state inward so that the insulating substrate 4 is always biased in the direction of the arrow in FIG. 2 by the first spring member 6. There is a need. The urging force of the first spring member 6 is obtained when the breaking strength of the insulating substrate 4 is 3.6 kg.
It is desirable to set it in the range of 200 g to 1 kg. Each of the first to third external terminals 28, 30, 34 is penetrated through the base 46 and led out to the outside to form an external terminal of the fuse resistor 2.

As shown in FIG. 6, the third external terminal 34
By connecting the first external terminal 28 to the line A that constitutes a power supply line leading to an electronic circuit (not shown) of the electronic device, and connecting the second external terminal 30 to the line A ′, The conductive pattern 26 is connected in series to the line A, and the first heating resistor 10, the chip type silicon surge absorber 22 and the second heating resistor 12 which are connected in series are connected between the lines A and A '. Connected to.

However, the rated voltage (breakdown voltage) of the chip-type silicon surge absorber 22 may be applied to the lines A and A'due to incorrect connection of the power source or execution of an overvoltage test.
When the above-mentioned overvoltage is continuously applied, the first heating resistor 10 and the second heating resistor 12 rapidly generate heat due to the conduction of an overcurrent due to this overvoltage. As a result, the first surface 8 of the insulating substrate 4 expands and causes thermal strain, and due to the thermal stress and the urging by the first spring member 6,
The insulating substrate 4 is surely shredded along the two-dot chain line (a) connecting both apexes of the notches 38, 38 (FIGS. 3 and 4). As a result, the first heating resistor 10 and the second heating resistor 12 formed on the first surface 8 of the insulating substrate 4 are cut off, so that the chip-type silicon surge absorber 22 is connected to the lines A and A '. Can be prevented from burning. At the same time, the conductive pattern 26 formed on the second surface 24 of the insulating substrate 4 is also cut, so that the line A is blocked and the overvoltage can be reliably prevented from being applied to the electronic circuit side.

FIG. 7 is a schematic side view showing another embodiment. In the fuse resistor 2 according to this embodiment, the second spring member 54 is used in place of the first spring member 6. This second spring member 54
As shown in FIG. 8, is a pressing portion 56 having a substantially V-shaped cross section,
It has fixing parts 58 and 58 derived from both ends of the pressing part 56. Then, the second spring member 54 has the pressing portion 56.
The top line 60 of the insulating substrate 4 contacts the second surface 24 of the insulating substrate 4 along a straight line connecting the apexes of the notches 38, 38 of the insulating substrate 4, and the fixing portions 58, 58 contact the inner surface of the cover 50. Is located in. In this case, the second spring member 54 is arranged in a state in which the second spring member 54 is slightly outwardly opened so that the insulating substrate 4 is constantly urged in the arrow direction of FIG. 7 by the pressing portion 56 of the second spring member 54. There is a need to. The rest of the configuration is substantially the same as that of the above embodiment. When an overcurrent flows through the first heating resistor 10 and the second heating resistor 12, the insulating substrate 4 is affected by thermal stress and the second spring member 54, as in the above embodiment. It is surely crushed by the bias.

In each of the above-mentioned embodiments, the first heating resistor 10 and the second heating resistor 12 are adhered and formed on the first surface 8 of the insulating substrate 4, and the chip type silicon surge absorber 22 is interposed between them. , And the conductive pattern 26 is formed on the second surface 24 by adhesion. However, the present invention is not limited to this structure. That is, it suffices to include at least one heating resistor that is adhered and formed on at least one surface of the insulating substrate, and a biasing means that biases the insulating substrate in the direction of promoting the crushing thereof. Therefore, although illustration is omitted, for example, the fuse resistor 70 shown in FIG. 9 and the fuse resistor 80 shown in FIGS. 10 and 11 are used to connect the first spring member 6 and the second spring member 54 to each other. The same biasing means may be used to bias the insulating substrates in a direction that promotes crushing. When the fuse resistor 80 shown in FIGS. 10 and 11 is used, the circuit configuration shown in FIG. 12 can be realized by connecting the fuse resistor 80 and a single surge absorbing element in series. .

[0020]

As described above, according to the present invention, since the insulating substrate is biased by the biasing means in the direction of promoting the rupture of the insulating substrate, when the overheat current is applied to the heating resistor, heat is generated. , The insulating substrate is surely crushed in a short time. As a result, it is possible to reliably cut off the energization of the overcurrent.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an embodiment of a fuse resistor according to the present invention.

FIG. 2 is a schematic side view showing the embodiment.

FIG. 3 is a schematic perspective view showing a first surface of the insulating substrate according to the above embodiment.

FIG. 4 is a schematic perspective view showing a second surface of the insulating substrate according to the above embodiment.

FIG. 5 is a schematic perspective view showing a first spring member according to the above embodiment.

FIG. 6 is a circuit diagram showing a usage example of the above embodiment.

FIG. 7 is a schematic side view showing another embodiment of the fuse resistor according to the present invention.

FIG. 8 is a schematic perspective view showing a second spring member according to the above embodiment.

FIG. 9 is a schematic perspective view showing a conventional example.

FIG. 10 is a schematic perspective view showing the front surface of another conventional example.

FIG. 11 is a schematic perspective view showing a back surface of the conventional example.

FIG. 12 is a circuit diagram showing a usage example of the conventional example.

[Explanation of symbols]

 2 Fuse resistor 4 Insulating substrate 6 First spring member 10 First heating resistor 12 Second heating resistor 54 Second spring member

Claims (2)

[Claims] 1. An insulating substrate, and a heating resistor adhered to the surface of the insulating substrate. When an overcurrent flows through the heating resistor, the insulating action is generated by the heating resistor. In a fuse resistor configured so that the substrate causes thermal strain and ruptures, thereby cutting off the heating resistor and interrupting energization of an overcurrent, in a direction that promotes rupture of the insulating substrate, A fuse resistor characterized in that a biasing means for biasing the insulating substrate is provided. 2. The fuse resistor according to claim 1, wherein the urging means is a spring member.