JPH06290698A - Fuse resistor - Google Patents

Abstract

PURPOSE:To materialize a fuse resistor having a less fluctuation in a breaking current value even if the max. temp. part in heating a heating resistor is observed at a point deviated from its central point. CONSTITUTION:A heating resistor 4 is deposited and formed on one surface of an insulating substrate 12. A fuse resistor 10 breaks the supply of overcurrent by rupturing the insulating substrate 12 due to exothermic action by the heating resistor 14 in overcurrent supply and by simultaneously disconnecting the heating resistor 14. Formed are nine upper notch parts 22 on the upper side of the insulating substrate 12 and nine lower notch parts 24 facing the upper notch parts 22 at nearly equal intervals, respectively on the lower side. The central point 34 of the heating resistor 14 is positioned on the line connecting the upper notch parts 22a to the notch part 24a with the shortest route. A plurality of lines are placed to connect the upper notch parts 22 to the lower notch parts 24 with the shortest route at the right and the left of the above line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating resistor formed on an insulating substrate to generate heat due to the application of an overcurrent, and the heating action breaks the insulating substrate to interrupt the supply of an overcurrent. The present invention relates to a fuse resistor configured as described above, and more particularly to a fuse resistor having a stable breaking characteristic.

[0002]

2. Description of the Related Art Conventionally, a fuse resistor 50 shown in FIG. 5 has been used as an overcurrent interruption means for protecting an electronic circuit element or the like from an overcurrent. This fuse resistor 50
A heating resistor 14 such as a ruthenium-based paste is adhered and formed on an insulating substrate 52 such as alumina or forsterite, and electrode patterns 16 and 16 for extraction are formed on both ends of the heating resistor 14.
And the external terminals 18, 16 at one end of the electrode patterns 16, 16.
18 connected. Further, in the center of the upper side and the lower side of the insulating substrate 52, a base-shaped upper cutout 54 and a lower cutout are formed.
56 are formed. An overglass coat 20 is applied to the surface of the heating resistor 14 to prevent creeping discharge.

This fuse resistor 50 has the above-mentioned external terminal 1
It is connected to an electronic circuit element or the like via 8 and 18. For example,
As shown in FIG. 2, the electronic device 30 is connected in series to a gas arrester 32 inserted between the lines A and A ′ that form a communication line or a power supply line.

However, if the electronic device 30 is erroneously connected to a power source exceeding its rating, or if an overvoltage test is performed,
When an overvoltage equal to or higher than the rated voltage of the gas arrester 32 is continuously applied to the lines A and A ′, an overcurrent continuously flows through the gas arrester 32 to the heating resistor 14, and this overcurrent is generated. The heating resistor 14 generates heat due to the energization of. The heat generated by the heating resistor 14 causes thermal distortion of the insulating substrate 52, and the insulating substrate 52 is left and right along the two-dot chain line connecting the tip 54a of the upper cutout 54 and the tip 56a of the lower cutout 56. Shatter into pieces. Therefore, it is possible to effectively prevent the heating resistor 14 itself from being cut to the left and right to cut off the overcurrent conduction, and thereby to prevent the gas arrester 32 from burning.

By the way, when an overcurrent flows into the heating resistor 14, as shown in FIG. 6, theoretically, the vicinity of the central point 34 of the heating resistor 14 is the highest temperature part, and the central point 34 is far away. Therefore, the temperature tends to drop in a ripple pattern. Therefore, normally, the upper and lower cutouts 54, 56 are arranged so that the central point 34 of the heating resistor 14, the tip 54a of the upper cutout 54, and the tip 56a of the lower cutout 56 are substantially aligned. Thus, the insulating substrate 52 is designed so that it can be crushed most easily.

[0006]

However, in reality, the central point 34 may not always be the highest temperature portion due to various causes such as non-uniformity of the film thickness of the heating resistor 14 and mixing of impurities. . As a result, for example, as shown in FIG. 7, when the first side point 36, which is displaced to the left more than the center point 34, becomes the highest temperature portion, the left end 54b of the upper cutout portion 54 and the insulating substrate 52. The insulating substrate 52 will be fractured along the two-dot chain line connecting the points 52a on the lower side. Similarly, when the second side point 38, which is slightly left of the central point 34, is the hottest part, the tip 54a of the upper cutout 54 and the left end of the lower cutout 56 are formed.
When the insulating substrate 52 ruptures along the chain double-dashed line connecting 56b and the third side point 40, which is displaced to the right more than the central point 34, becomes the hottest part, the right side of the upper cutout 54 The insulating substrate 52 is crushed along the two-dot chain line connecting the end 54c and the tip 56a of the lower cutout 56.

The crushing of the insulating substrate 52 is caused by the cutouts 54 and 56 at the upper and lower sides.
It is easiest to follow the straight line connecting the tips 54a and 56a of the above, and therefore, the rated breaking current value of the fuse resistor 50 is also set on the assumption that the insulating substrate 52 is crushed along this straight line. . Therefore, as described above, when the highest temperature portion appears at a position outside the center point 34 of the heating resistor 14 and the insulating substrate 52 ruptures along an unplanned line, a current higher than the rated current is applied. There is a problem that the insulating substrate 52 is crushed by the value, and the breaking current value fluctuates.

The present invention has been made in view of the above-mentioned problems of the conventional example. Even when the highest temperature portion of the heating resistor during heat generation appears at a position deviating from the center point, the actual breaking current is generated. The purpose is to realize a fuse resistor whose value hardly changes compared to the rated breaking current value.

[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 one surface of the insulating substrate. A fuse configured so that, when an overcurrent exceeding the rated value flows in the resistor, the insulating substrate causes thermal distortion and ruptures due to its heat generation, thereby cutting the heating resistor and interrupting the current flow. In the resistor, a plurality of cutouts are formed on the first side of the insulating substrate, and a plurality of cutouts formed on the first side are formed on the second side opposite to the cutouts by substantially equal distances. At least one of a plurality of lines that form a plurality of notches facing each other at a distance and connect each notch formed on the first side and each notch formed on the second side in the shortest direction. The center point of the heating resistor is located between any pair of lines. As, characterized in that a respective notch. It should be noted that the above-mentioned “a plurality of lines connecting each cutout formed on the first side and each cutout formed on the second side in the shortest direction” means that the cutout and the heating resistor are connected to each other. It means an imaginary line assumed to show the positional relationship with the center point, and a line is not actually drawn between the notches on both sides.

[0010]

As described above, a plurality of cutouts are formed on the first side and the second side of the insulating substrate, and among the plurality of lines connecting the cutouts formed on the two sides in the shortest direction. , Since each notch is arranged so that the center point of the heating resistor is located between any one pair of lines, even if the hottest part of the heating resistor appears at a place outside the center point, The insulating substrate shreds along the line closest to. Moreover, since the distances between the notches formed on both sides are substantially equal, no matter which line the insulating substrate is crushed by, the thermal energy required for the crushing will be substantially equal. Therefore, the breaking current value of the fuse resistor can be made substantially uniform irrespective of where the highest temperature portion of the heating resistor appears.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiments. FIG. 1 shows an example of a fuse resistor 10 according to the present invention, in which a rectangular-shaped heat generation made of ruthenium-based paste or the like is formed on one surface of an insulating substrate 12 made of ceramic such as alumina, forsterite, steatite. The resistor 14 is adhered and formed, and electrode patterns 16 and 16 for extraction, which are made of Ag / Pd-based paste or the like and are connected to both ends of the heating resistor 14, are formed.
External terminals 18 and 18 are connected to the lower ends of 16 and 16, respectively. The surface of the heating resistor 14 is covered with an overglass coat 20 for preventing creeping discharge.

On the upper side of the insulating substrate 12, nine V-shaped upper notches 22 are continuously formed in a saw-tooth shape. Also, nine lower notches 24 having a V-shape are continuously provided in a saw-tooth shape on the lower side of the insulating substrate 12. Then, each tip of the upper cutout 22 and each tip of the lower cutout 24 are arranged to face each other with a substantially equal distance.

The fuse resistor 10 has the external terminal 1
It is connected to an electronic circuit element or the like via 8 and 18. For example, as shown in FIG. 2, it is connected in series to the gas arrester 32 connected between the lines A and A ′ that form the communication line or the power supply line of the electronic device 30. However, when the electronic device 30 is erroneously connected to a power source exceeding its rating, or an overvoltage test is performed, an overvoltage continuously exceeding the rated voltage of the gas arrester 32 is continuously applied to the lines A and A '. In this case, an overcurrent higher than the rated value continuously flows through the gas arrester 32 into the heating resistor 14, and the heating resistor 14 generates heat due to the passing of this overcurrent. The heat generated by the heating resistor 14 causes thermal distortion of the insulating substrate 12, and the insulating substrate 12 is crushed left and right along the shortest line connecting the tips of the upper cutout 22 and the lower cutout 24. To be done. Therefore, the heating resistor 14
It is also possible to effectively prevent the gas arrester 32 from burning or the like by cutting itself to the left and right to cut off the overcurrent conduction.

At this time, as shown in FIG.
When the center point 34 of the is the hottest part, the upper cutout 22a
The insulating substrate 12 is crushed to the left and right along the two-dot chain line connecting the tip of the lower end of the lower cutout 24a and the tip of the lower cutout 24a. If the first side point 36, which is farther to the left than the center point 34, is the hottest part, along the two-dot chain line connecting the tip of the upper cutout 22b and the tip of the lower cutout 24b. Insulation board 12 shreds, center point 34
When the second side point 38, which is slightly further to the left, becomes the highest temperature part, the insulating substrate 12 is crushed along the two-dot chain line connecting the tips of the upper cutout 22c and the lower cutout 24c. Tear. Furthermore, when the third side point 40, which is farther to the right than the central point 34, is the hottest part, along the two-dot chain line connecting the tip of the upper cutout 22d and the tip of the lower cutout 24d. Insulating substrate
12 shatters. The central point 34 is the heating resistor 14
The point where the center line in the longitudinal direction and the center line in the lateral direction intersect (the intersection of the diagonal lines of the heating resistor 14) is applicable.

As described above, even when the highest temperature portion of the heat generating resistor 14 during heat generation deviates from the central point 34, the upper cutout 22
Of the nine straight lines connecting the tip of the lower end and the tip of the lower cutout 24 with the shortest distance, the insulating substrate 12 is crushed along the closest line,
Moreover, since the distances between the tips of the upper cutouts 22 and the tips of the lower cutouts 24 are substantially equal, the thermal energy required for the crushing is substantially uniform. As a result, this fuse resistor 10
The breaking current value of can be made substantially constant regardless of the exposed position of the highest temperature portion when the heating resistor 14 is energized and generates heat.

The present invention is not limited to the above embodiment, but various modifications can be made without departing from the spirit of the invention. For example, as shown in FIG. 4, the number of upper notches 22 and lower notches 24 is increased so that each upper notch 22 and lower notch
A line (not shown) that connects the shortest lines between the 24 may be arranged at regular intervals from the left end portion to the right end portion of the heating resistor. As a result, it is possible to further reduce the error in the breaking current value due to the displacement of the highest temperature part. However, in the present invention, at least two upper and lower cutouts 22 and 24 are formed, and the central point is defined between the two lines connecting the cutouts at the shortest distance.
It suffices to arrange the notches 22 and 24 so that the 34 is located. As a result, even if the highest temperature part of the heating resistor 14 appears at a position that deviates from the center point 34 to the left or right, the insulating substrate 12 can be crushed along the line that is closer to the left or right.

[0017]

According to the fuse resistor of the present invention, a plurality of notches are formed on each of the first side and the second side of the insulating substrate, and the distance between the notches formed on both sides is minimized. Since each notch is arranged so that the center point of the heating resistor is located between any one of a plurality of lines that connect,
Even if the highest temperature part of the heating resistor appears at a position deviating from the central point, the insulating substrate is crushed along the line immediately adjacent to the position. Moreover, since the distances between the notches formed on both sides are substantially equal, no matter which line the insulating substrate is crushed by, the thermal energy required for the crushing will be substantially equal. Therefore, the breaking current value of the fuse resistor can be made substantially uniform irrespective of where the highest temperature portion of the heating resistor appears.

[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 circuit diagram showing a usage example of the embodiment and the conventional example.

FIG. 3 is a partially enlarged view showing the vicinity of an upper cutout portion and a lower cutout portion of the above embodiment.

FIG. 4 is a schematic perspective view showing another embodiment of the fuse resistor according to the present invention.

FIG. 5 is a schematic perspective view showing a conventional example.

FIG. 6 is a partially enlarged view showing the vicinity of an upper cutout portion and a lower cutout portion of the conventional example.

FIG. 7 is a partial enlarged view showing the vicinity of an upper cutout portion and a lower cutout portion of the conventional example.

[Explanation of symbols]

 10 Fuse resistor 12 Insulation board 14 Heating resistor 22 Upper notch 24 Lower notch 34 Center point of heating resistor

Claims (4)

[Claims] 1. An insulating substrate, comprising: an insulating substrate; and a heating resistor formed on one surface of the insulating substrate. When an overcurrent exceeding a rated value flows through the heating resistor, the insulating substrate produces heat, thereby producing the insulating substrate. In the fuse resistor configured to cause thermal strain and rupture, and thereby the heating resistor is cut to interrupt the current flow, a plurality of cutouts are formed on the first side of the insulating substrate. A plurality of notches formed on the second side facing the second side and facing each other with a distance substantially equal to the plurality of the notches formed on the first side.
The center point of the heat-generating resistor is at least between any one of a plurality of lines connecting the cutouts formed on the side of and the cutouts formed on the second side at the shortest distance. A fuse resistor characterized in that each notch is arranged so as to be positioned. 2. The first and second sides of the insulating substrate are each formed with at least three notches, and each notch formed on the first side and the second side are formed. A line in which the center point of the heating resistor is located on any one of a plurality of lines connecting the cutouts with the shortest distance and the center point is located between at least another pair of lines. 2. The fuse resistor according to claim 1, wherein the respective cutouts are arranged so as to be arranged. 3. A plurality of lines connecting the cutouts formed on the first side and the cutouts formed on the second side of the insulating substrate at the shortest are one of the heating resistors. 3. The fuse resistor according to claim 1, wherein the notches are arranged so as to be arranged at a predetermined interval from one end to the other end of the fuse resistor. 4. A plurality of V-shaped notches are continuously formed in a saw-tooth shape on the first side and the second side of the insulating substrate, respectively. The fuse resistor according to any one of the above.