JPH10308160A - Fuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuse in which the size is not increased, the arc extinguishability is high, and the shut-off performance is improved. SOLUTION: A fuse-element is formed into a strip-shaped thin film in a longitudinal direction of an insulated substrate 2 by various kinds of thin film forming method on one surface of the insulated substrate 2 formed in long strip, to form an element 3. A first protective film 5a mainly consisting of silicon oxide is formed into a thin film through the sputtering on an upper surface of the element 3 with each end part in the longitudinal direction exposed. The silicone rubber, etc., is applied to an upper surface of the first protective film 5a, and hardened to laminate a second protective film 5b. The conductive paste, etc., is applied to the upper surface of the exposed element 3, the end face of the insulated substrate 2, and a back side of the insulated substrate 2, and hardened to form a pair of electrodes 4, 4. An overcoat 7 is formed by applying and hardening the resin having the crosslinking structure and the heat resistant resin which completely covers the protective film 4. The arc extinction effect of the first protective film 5a is reinforced by the second protective film 5b to prevent generation of the arc in the shut off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuse for preventing a circuit from being damaged by overcurrent.

[0002]

2. Description of the Related Art Conventionally, for example, a configuration shown in FIG. 2 has been known as a fuse.

The fuse 10 shown in FIG. 2 is made of, for example, glass such as quartz or borosilicate, ceramics such as alumina or aluminum nitride, or synthetic resin such as epoxy or polyimide.
Alternatively, on one plane of an insulating substrate 11 formed of a composite material of a synthetic resin and a glass cloth, a fusible element 12 is vacuum-deposited, ion-plated,
It is formed by a thin film forming technique such as sputtering or chemical vapor deposition, or by applying and firing a resinate paste. Further, a pair of electrodes 13, 13 that are separated from both ends of the element 12 and from the end surface of the insulating substrate 11 to the back surface are formed by applying or curing the conductive paste, or by baking, or by plating. Then, application and baking of a slurry-like ceramic or a glass paste, or application and curing of a synthetic resin such as an epoxy resin, a polyimide resin, silicone, or a fluorine resin so as to cover the vicinity of the ends of the electrodes 13 and 13 and the element 12. An overcoat 14 is provided to protect the element 12 and prevent an arc generated when the element 12 is cut off from affecting the surroundings.

[0004]

By the way, the breaking performance of a fuse is one of the important performances of the fuse, and is standardized for each fuse. And, the larger the rated voltage in this interruption standard, the wider the application.

In a conventional main structure in which a fusible metal wire is stretched between electrode terminals, a three-dimensional space is provided around the metal wire, or a three-dimensional space around the metal wire is provided. The space is filled with a material having an arc-extinguishing function, such as granular silicon oxide, to improve the breaking performance.

However, in response to the recent demand for miniaturization of electronic components, a thin film type fuse in which a fusible material is provided in a thin film on an insulating substrate to form an element for the purpose of miniaturization is disclosed in, for example, Japanese Patent Application Laid-Open No. It is difficult to provide a three-dimensional space around the element which is a fusible element or to fill a material having an arc-extinguishing function, as described in 190631, and it is difficult to reduce the size.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems, and has as its object to provide a fuse having high arc-extinguishing performance and improved breaking performance without increasing the size.

[0008]

According to a first aspect of the present invention, there is provided a fuse including an insulating substrate, a pair of electrodes provided on one surface of the insulating substrate with a gap therebetween, and a thin film formed between the electrodes. An element, a first protective film having an arc-extinguishing effect covering at least a part of the element, and a second protective film having an arc-extinguishing effect covering at least a part of the first protective film. An element is formed as a thin film at a position between a pair of opposing electrodes provided on one surface of an insulating substrate with a gap therebetween, and at least a part of the element is formed of a first protective film having an arc-extinguishing effect. To cover and cover at least a part of the first protective film with a second protective film having an arc extinguishing action, the arc extinguishing action of the first protective film is reinforced by the second protective film, Suppressing large size to suppress arcing when breaking More, cut-off performance is improved.

According to a second aspect of the present invention, there is provided the fuse according to the first aspect, wherein at least one of the first protective film and the second protective film contains silicon and a silicon compound as main components. Since at least one of the first protective film and the second protective film covering the silicon is mainly composed of silicon and a silicon compound, an arc at the time of interruption is reliably prevented.

According to a third aspect of the present invention, in the fuse according to the first or second aspect, the first protective film is a thin film formed by sputtering, and the first protective film is formed by sputtering. Since the first protective film is formed of a thin film, the first protective film can be easily formed without being enlarged.

According to a fourth aspect of the present invention, there is provided the fuse according to any one of the first to third aspects, wherein the second protective film is made of silicone. Since it can be arranged on the first protective film, productivity is improved.

According to a fifth aspect of the present invention, there is provided a fuse according to any one of the first to fourth aspects, wherein at least a part of the second protective film is covered with a third protective film. Since at least a part of the protective film is covered with the third protective film, the element and the protective film are easily protected from external force.

According to a sixth aspect of the present invention, in the fuse according to the fifth aspect, the third protective film is a resin having a crosslinked structure, and a resin having a crosslinked structure is used as the third protective film. As a result, an overcoat having high mechanical strength is obtained, and the protective properties of the element, the first protective film, and the second protective film are improved.

According to a seventh aspect of the present invention, there is provided the fuse according to the fifth aspect, wherein the third protective film is made of a heat-resistant resin, and the heat-resistant resin is used as the third protective film. An overcoat having high target strength is obtained, and the protective properties of the element, the first protective film, and the second protective film are improved.

[0015]

Next, an embodiment of a fuse according to the present invention will be described with reference to FIG.

Reference numeral 1 denotes a fuse. The fuse 1 has an insulating substrate 2 in the shape of a rectangular flat plate. This insulating substrate 2
Is made of, for example, glass such as quartz or borosilicate, ceramics such as alumina or aluminum nitride, synthetic resin such as epoxy or polyimide, or a composite material of synthetic resin and glass cloth.

On one plane of the insulating substrate 2,
An elongated element 3 is formed in a strip shape in the longitudinal direction. The element 3 is made of a soluble material such as aluminum, copper, or various alloys, and is formed by vacuum deposition, ion plating, sputtering, or chemical vapor deposition (Chemical Vapor Deposition).
A thin film is formed by a thin film forming technique such as Deposition (CVD) or application and baking of a resinate paste.

Further, a pair of electrodes 4, 4 are formed in a band from the both ends in the longitudinal direction of the element 3 to the back surface of the insulating substrate 2 through the end surface of the insulating substrate 2. These electrodes 4 and 4 are formed by hardening or baking after application of the conductive paste, plating, or the like, and lead out conductive paths.

Further, on the upper surface of the element 3, a protective film 5 is formed between the opposing electrodes 4 and 4.
This protective film 5 is formed in a laminated structure of a first protective film 5a located on the upper surface of the element 3 and a second protective film 5b located on the upper surface of the first protective film 5a.

Further, an overcoat 6 as a third protective film is formed so as to cover the ends of the opposing electrodes 4 and 4, the element 3 and the protective film 5. The overcoat 6 is formed by applying and curing a synthetic resin such as an epoxy resin, a polyimide resin, and a fluorine-based resin. In addition, the overcoat 6 has formability, handleability,
A synthetic resin having a crosslinked structure such as an epoxy resin or a heat-resistant resin such as a polyimide resin, an aromatic polyamide resin, or a polybenzoimidazole resin is particularly preferable in terms of mechanical strength, heat resistance, and water resistance.

Next, the manufacturing operation of the above embodiment will be described.

First, an element 3 is formed by forming a thin film of a fusible material in a longitudinal band shape in the longitudinal direction of the insulating substrate 2 on one plane of the insulating substrate 2 previously formed on a rectangular flat plate by various thin film forming methods.

Then, on the upper surface of the element 3, a first protective film 5a containing silicon oxide as a main component is formed as a thin film by exposing both ends in the longitudinal direction by sputtering or the like. Further, a second protective film 5b is formed on the upper surface of the first protective film 5a by applying and curing silicone rubber or the like, and the protective film 5 is formed by lamination.

Next, for example, a conductive paste or the like is applied and cured over the exposed upper surface of the element 3, the end surface of the insulating substrate 2, and the back surface of the insulating substrate 2 to form a pair of electrodes 4, 4.
Is formed, and the element 3 and the electrodes 4 and 4 are electrically connected.

Thereafter, the ends of the opposing electrodes 4 and 4, the element 3 and the protective film 5 are completely covered with the protective film 5.
A resin having a cross-linking structure such as an epoxy resin or a heat-resistant resin such as a polyimide resin, an aromatic polyamide resin, and a polybenzoimidazole resin is coated and cured to form an overcoat 6. To form

Next, the operation of the above embodiment will be described.

First, the element 3 of the manufactured fuse 1
Electrodes 4, 4 located on the back side of the side where no
Are soldered to lands between circuits to be protected from overcurrent (not shown) and mounted on a circuit board.

When an overcurrent flows through the circuit board, the element 3 melts. During this fusing, the first protective film 5a covering the element 3 has an arc-extinguishing effect of silicon oxide and the second protective film 5b has an arc-extinguishing effect of silicone, that is, direct arc-extinguishing of the first protective film 5a. The action and the silicone component having the arc-extinguishing effect of the second protective film 5b act to reinforce the arc-extinguishing effect of the first protective film 5a, thereby suppressing the generation of arc and ensuring the connection between the fuse terminals. Is opened to prevent an overcurrent from flowing to the circuit, thereby preventing the circuit from being damaged. Further, the overcoat 6 can reliably prevent the arc from going outside, and can prevent the surroundings from being adversely affected.

As described above, according to the above embodiment, since the element 3 is covered with the protective film 5 having a laminated structure of the first protective film 5a and the second protective film 5b having an arc-extinguishing function, It is possible to suppress the occurrence of an arc at the time of breaking without breaking, prevent damage to surrounding circuits, improve the breaking performance, and increase the applications.

Since the element 3 is covered with the first protective film 5a mainly composed of silicon oxide and the second protective film 5b mainly composed of silicone, the arc-extinguishing effect of the first protective film 5a is achieved. Is reinforced by the second protective film 5b, a good arc-extinguishing effect is obtained, and the interruption arc can be reliably prevented, and the protective film 5 can be easily formed.

Further, since the protective film 5 having a laminated structure is covered with an overcoat 6 formed of a resin having a crosslinked structure such as an epoxy resin, the element 3 and the protective film 5 are formed.
Is hardly damaged even when subjected to an external stress during manufacturing or mounting work on a circuit board, etc., so that the protection of the element 3 and the protective film 5 can be improved, and the influence of an arc on the surroundings can be prevented. In addition, the breaking performance can be improved, and the fuse 1 having stable characteristics and high reliability can be easily obtained.

Further, since the first protective film 5a is a thin film formed by sputtering, the first protective film 5a can be made thinner more easily, and the productivity can be improved.

Furthermore, if the element 3 and the protective film 5 are covered with an overcoat 6 formed of a heat-resistant resin such as a polyimide resin, an aromatic polyamide resin, and a polybenzimidazole resin in a higher temperature environment, the element 3 and the protective film 5 can be formed during the production and the circuit. During mounting work on a substrate, etc., it is hard to be damaged even when subjected to external stress, and the protection of the element 3 and the protective film 5 can be improved, and the influence of an arc on the surroundings can be prevented, and the breaking performance can be improved. The fuse 1 having stable characteristics and high reliability can be easily obtained.

In the above embodiment, the first protection film 5a is formed as a passivation film without using silicon oxide as a main component, and the second protection film 5b is formed by applying and curing silicone. Are the first protective film 5a and the second protective film 5b.
Any of the materials having an arc-quenching effect, such as forming a passivation film or applying and curing with silicone, may be used by any method.

The element 3, the protective film 5, the electrode 4,
4. The method of forming the overcoat 6 and the like are not limited to the above embodiment, and any method can be used.

Further, the overcoat 6 may be formed by using an inorganic material such as a ceramic or a glass material in addition to a resin having a crosslinked structure or a heat-resistant resin. When inorganic materials are used, the elements 3 and the like must be formed of a material that can withstand the firing temperature in order to form a film by applying and firing these materials. A resin having a crosslinked structure or a heat-resistant resin is preferable because the rise is high and the circuit board may be damaged.

[0037]

EXAMPLE An experiment was conducted on the breaking performance of the fuse of the above embodiment.

As a sample of this embodiment, a thin film of aluminum having a thickness of about 1.5 μm was formed on an insulating substrate 2 having a length of 7 mm, a width of 4 mm, and a thickness of 1 mm, and then etched. The element 3 is formed by forming a predetermined pattern. Then, a thin film made of silicon oxide having a thickness of about 0.
A thin film was formed to a thickness of 6 μm, and the thin film on both ends of the element 3 was removed and exposed to form a first protective film 5a. Further, a conductive paste (trade name: Dotite D- manufactured by Fujikura Kasei Co., Ltd.) is overlapped on the exposed portion of the element 3.
1230) was applied and cured to obtain an electrode 4. Then, silicone rubber (trade name: KE-1604, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the upper surface of the first protective film 5a and cured to form a second protective film 5b. Further, a first protective film
Epoxy resin (trade name: S-222, manufactured by Taiyo Ink Mfg. Co., Ltd.) so as to completely cover 5a and second protective film 5b.
Was applied and cured to obtain an overcoat 6.

On the other hand, as a comparative sample, the overcoat 6 of this example was not provided (Comparative Example 1), and the overcoat of Comparative Example 1 was applied using a silicone resin (trade name: Ohmic Coat AF495, manufactured by NAMICS). Cured (Comparative Example 2), and the overcoat of Comparative Example 1 was replaced with an epoxy resin (trade name: S-2, manufactured by Taiyo Ink Mfg. Co., Ltd.)
What was applied and hardened using 22) was used.

In the test of the breaking performance, various samples were soldered to a test printed board in which a copper foil pattern was formed on a glass-epoxy resin substrate having a thickness of about 1.5 mm, and the specified short-circuit current was 50 A. With a constant of 0 msec, the circuit voltage is
Under each condition of V, 63 V DC and 125 V DC, a cutoff test was performed to confirm the cutoff status of the element.

As a result, in Comparative Example 1 in which the overcoat 6 was not provided, the second protective film 5b was easily dropped from the insulating substrate, and the cutoff test could not be performed. In Comparative Example 2 in which the silicone resin was used for the overcoat of Comparative Example 1, the blocking was completed, but the overcoat was partially damaged. Further, in Comparative Example 3 in which the epoxy resin was used for the overcoat of Comparative Example 1, DC48 having a low circuit voltage was used.
In V, the cut-off was completed and no abnormalities were observed in appearance,
At high circuit voltages of 63 V DC and 125 V DC, the cutoff was completed, but some damage was observed in the overcoat.

On the other hand, it was found that the fuse 1 of the present embodiment had good breaking performance without any abnormality in appearance, with the breaking being completed even under the conditions of each circuit voltage.

[0043]

According to the fuse of the first aspect, the element is formed as a thin film between a pair of electrodes provided on the insulating substrate,
Since this element is laminated and covered with the first protective film and the second protective film having an arc extinguishing function, the arc extinguishing function of the first protective film is reinforced by the second protective film, thereby suppressing an increase in size. By suppressing the arc at the time of interruption, the interruption performance can be improved.

According to the fuse of the second aspect, in addition to the effect of the fuse of the first aspect, at least one of the first protective film and the second protective film covering the element is made of silicon and a silicon-based compound. As a main component, a reliable arc-extinguishing effect is obtained, and an arc at the time of interruption can be reliably prevented.

According to the fuse of the third aspect, in addition to the effect of the fuse of the first or second aspect, the first protective film is formed of a thin film formed by sputtering, so that the protective film becomes large. And a thin film can be easily formed.

According to the fuse according to the fourth aspect, in addition to the effect of the fuse according to any one of the first to third aspects, since the second protective film is made of silicone, the first protective film can be easily formed.
Can be disposed on the protective film, and the productivity can be improved.

According to the fuse according to the fifth aspect, in addition to the effect of the fuse according to any one of the first to fourth aspects, at least a part of the second protective film is covered with the third protective film. And the protective film can be easily protected from external force.

According to the fuse of the sixth aspect, in addition to the effect of the fuse of the fifth aspect, since a resin having a crosslinked structure is used as the third protective film, an overcoat having high mechanical strength can be obtained. The protective properties of the element, the first protective film, and the second protective film can be improved.

According to the fuse of the seventh aspect, in addition to the effect of the fuse of the fifth aspect, since a heat-resistant resin is used as the third protective film, an overcoat having high mechanical strength can be obtained even in a high-temperature environment. Thus, the protection of the element, the first protective film, and the second protective film can be improved.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view showing a conventional fuse.

[Explanation of symbols]

 Reference Signs List 1 fuse 2 insulating substrate 3 element 4 electrode 5a first protective film 5b second protective film 6 overcoat as third protective film

Claims (7)

[Claims] An insulating substrate; a pair of electrodes provided on one surface of the insulating substrate so as to face each other with a gap therebetween; an element formed as a thin film between the electrodes; and at least a part of the element. A fuse, comprising: a first protective film having an arc-extinguishing function; and a second protective film having an arc-extinguishing function that covers at least a part of the first protective film. 2. The fuse according to claim 1, wherein at least one of the first protection film and the second protection film contains silicon and a silicon compound as main components. 3. The fuse according to claim 1, wherein the first protective film is a thin film formed by sputtering. 4. The fuse according to claim 1, wherein the second protective film is made of silicone. 5. The fuse according to claim 1, wherein at least a part of the second protective film is covered with a third protective film. 6. The fuse according to claim 5, wherein the third protective film is a resin having a crosslinked structure. 7. The fuse according to claim 5, wherein the third protective film is made of a heat-resistant resin.