JPH074761Y2 - Fuse resistor - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuse resistor in which a resistor paste is printed on an insulating substrate, and in particular, it has a fail-safe function of releasing conduction when a voltage higher than a predetermined voltage is continuously applied. A fuse resistor provided.

[0002]

2. Description of the Related Art There is a resistance element as a main element constituting an electric / electronic circuit. A resistance element used on a printed wiring board is such that a terminal is led out from both ends of the resistance element and the resistance element is made of glass or It was general that it was molded with a synthetic resin.

For hybrid ICs and the like, there is known a technique in which a resistance paste is applied on a ceramic substrate and used as a resistance element.

By the way, for such a resistance element,
When a high voltage higher than the specified voltage is applied for a long time, the resistance element itself generates heat, which may damage the element and deteriorate the characteristics of other elements on the circuit board.

For this reason, a resistance element having a so-called fail-safe function, in which a resistor is damaged by cracks or the like when a high voltage of a certain level or more is applied and the circuit is opened, is conceivable.

An example of such a resistance element, that is, a fuse resistor is shown in FIG. The fuse resistor 1 shown in the figure has a pair of terminals 3 and 3 attached to the lower end of an insulating substrate 2 made of ceramic or the like, and a resistor region 4 formed by applying a paste resistor at the center of the substrate surface. It has a structure in which the body region 4 and the terminal 3 are connected by a conductor pattern 5.

In such a fuse resistor 1, when a voltage of a predetermined value or more is continuously applied between the terminals 3 and 3, the resistor region 4 is heated, and the insulating substrate 2 is heated due to the deviation of thermal stress.
A crack D is generated in the inner surface of the terminal 3 to open the electrical continuity between the terminals 3.

[0008]

However, in the prior art shown in FIG. 3, the position where the crack is generated is indefinite. Therefore, for example, when the crack is generated at the position E in FIG. Will remain undivided. At this time, since the conductive state is maintained, a voltage higher than the rated voltage is continuously applied to other elements on the circuit board, and in the worst case, there is a risk of ignition due to heat generation of the fuse resistor.

The present invention has been made in view of the above problems, and an object thereof is to provide a fuse resistor capable of surely performing electrical opening between terminals when a high voltage higher than a specified value is applied. To provide.

[0010]

SUMMARY OF THE INVENTION According to the present invention, a pair of terminals is attached to an end of an insulating substrate, a resistor region is provided on the surface of the substrate, and the terminal and the resistor region are connected by a conductor pattern. The gist of the resistor is that, on the surface of the substrate, the conductor pattern having one end connected to the terminal is folded back around the periphery of the surface of the substrate and the other end is connected to the resistor region.

Further, at least a part of the peripheral edge of the substrate may be provided with a cutout portion for guiding a crack generation direction when a voltage higher than a predetermined value is applied between the terminals.

[0012]

According to the above means, the conductor pattern connecting the terminal and the resistor region is laid on the substrate surface in the vicinity of the peripheral edge of the substrate surface. Therefore, when a high voltage is continuously applied between the terminals, the conduction is interrupted at any part of the conductor pattern due to the cracks formed on the peripheral edge of the substrate surface. Therefore, it is possible to surely open the terminals when a high voltage higher than the specified value is applied.

Furthermore, by forming a notch in a part of the peripheral edge of the board, the board is easily broken, and even when the voltage value slightly exceeds the specified value, the terminals are opened. To be realized.

Further, by forming the notch, it is possible to control the crack generation direction so as to divide the resistor region, for example, and in combination with the above, a high voltage higher than a specified value is obtained. During application, the terminals can be more reliably opened.

As described above, it is possible to prevent the damage and characteristic deterioration of other elements due to the heat generation of the fuse resistor.

[0016]

1 and 2 are front views showing a fuse resistor according to an embodiment of the present invention.

In the fuse resistor 1 of this embodiment, a terminal 3 is attached to the lower end of an insulating substrate 2, and a resistor region 4 is formed in the center of the surface of the insulating substrate 2. And
The terminal 3 and the resistor region 4 are connected by a conductor pattern 5.

The insulating substrate 2 used in this embodiment is, for example, a ceramic substrate selected from alumina and forsterite, and is obtained by processing a so-called half-blended green sheet into a plate piece and then sintering. it can.

The terminal 3 is made of highly conductive metal such as 42 alloy or Kovar, and its base end is fixed to the insulating substrate 2 by soldering or the like.

The resistor region 4 formed on the surface of the insulating substrate 2 is formed by applying a ruthenium-based paste, and the resistivity is variable depending on the compounding ratio of the conductive material.

The conductor pattern 5 can be applied in a predetermined shape by using a printing technique such as a squeegee method or a mask method in a semi-molten state of Ag / Pd-based conductive metal.

In the present embodiment, this conductor pattern 5
Has one end connected to the terminal 3 and an intermediate portion formed into a shape that enters the center of the substrate surface via the vicinity of the peripheral edge of the substrate surface. It is preferable that such a laid shape of the conductor pattern 5 extends over the entire periphery of the substrate surface.

In the insulating substrate 2, a notch 6 is formed between the pair of terminals 3 and 3 in FIG. 1 (between the terminals 3 and 3 and the upper end in FIG. 2). This notch 6 can be provided at the stage of the green sheet in the process of forming the insulating substrate 2 described above.

The entire surface of the insulating substrate 2 element described above or at least the resistor region 4 is coated with a glass material 7 such as low melting point glass in order to prevent creeping discharge. Furthermore, by applying this glass material 7, physical damage and the like can be prevented.

In the fuse resistor 1 as shown in FIG. 1, when a voltage higher than a specified value, for example, a high voltage of about 600 V AC is applied between the terminals 3 and 3, the electric energy in the resistor region 4 becomes thermal energy. Converts to heat. Therefore, the thermal stress is deviated in the insulating substrate 2, and a crack is generated in the direction indicated by the symbol A from the most fragile notch 6 of the physical structure, and the crack A divides the resistor region 4 and the terminal. The electrical continuity between 3 and 3 is cut off.

At this time, a discharge may occur between the terminals 3 and 3 at the moment when the insulating substrate 2 is broken by a crack, but in order to prevent such a discharge, the terminals 3 and 3 are You may make it cover each base part with synthetic resins, such as an epoxy resin.

Further, depending on how the thermal stress in the insulating substrate 2 is deviated, a crack may occur from the side direction of the insulating substrate 2 as indicated by the symbol B. In the present embodiment, this crack is generated. The conductor pattern 5 laid near the peripheral edge of the insulating substrate 2 is first divided by B. Therefore, when the crack B is generated, the electrical conduction between the terminals 3 and 3 is cut off, so that the resistor region 4 can be prevented from overheating.

Furthermore, in the fuse resistor 1 shown in FIG. 2, even if the crack C generated from the notch 6 does not completely divide the resistor region 4, the conductor pattern 5 is formed.
Is definitely divided. Therefore, the electrical conduction between the terminals 3 is surely cut off.

[0029]

According to the present invention, when a high voltage is applied between the terminals, the cracks formed at the peripheral edge of the substrate surface first interrupt the conduction at any part of the conductor pattern. When the above high voltage is applied, the terminals can be reliably opened.

Furthermore, by forming a notch in a part of the peripheral edge of the substrate, it is possible to control the crack generation direction so as to divide the resistor region, and thus the inter-terminal gap. The opening can be performed more reliably.

Therefore, it is possible to prevent damage to other elements and deterioration of characteristics due to heat generation of the fuse resistor.

[Brief description of drawings]

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

FIG. 2 is a front view showing a fuse resistor according to an embodiment of the present invention.

FIG. 3 is a front view showing a fuse resistor as an example of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuse resistor, 2 Insulating substrate, 3 Terminal, 4 Resistor area, 5 Conductor pattern, 6 Notch part, 7 Glass material, AE crack.

Claims (2)

[Scope of utility model registration request] 1. A fuse resistor in which a pair of terminals are attached to an end portion of an insulating substrate, a resistor region is provided on a surface of the substrate, and the terminal and the resistor region are connected by a conductor pattern. A fuse resistor, characterized in that, on the surface, the conductor pattern having one end connected to the terminal is folded back via the vicinity of the peripheral edge of the substrate surface, and the other end is connected to a resistor region. 2. At least a part of the periphery of the substrate is
2. The fuse resistor according to claim 1, wherein a cutout portion is formed between the terminals to guide a crack generation direction when a voltage higher than a predetermined value is applied.