JPH06176680A - Fuse - Google Patents

Abstract

PURPOSE:To provide a lightweight fuse having stable performance by providing a film of soluble substance on a thin alumina substrate of specific thickness. CONSTITUTION:A high-purity, smooth alumina substrate 21 having a thickness of 0.03 to 0.4mm is obtained using sol-gel method which employs metal alkoxide. A film 22 of low melting-point organic substance is provided on the alumina substrate 21 and a metal film 23 is formed to cover the film 22. Heating resistors 24 are provided at both end portions of the metal film 23 and electrodes 25 are provided at the end portions of each heating resistor 24 to obtain a small fuse. To use the fuse in a circuit, the film 22 of low melting-point organic substance fused with an overcurrent because of Joule heat and heat conducted thereto from the heating resistors 24 via the metal film 23, so that the circuit is opened. Further, the metal film 23 is broken by the overcurrent to interrupt the current. A film with no defects can be formed on the smooth surface of the substrate 21 so that operation of the fuse is stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small fuse for preventing an overcurrent of an electric device, in which a fusible film is formed on a glass substrate or an alumina substrate by, for example, vapor deposition or sputtering.

[0002]

2. Description of the Related Art Fuses in which a fusible material film such as a low melting point organic material film is formed on an insulating substrate such as a glass substrate or an alumina substrate are widely used. FIG. 2 is a cross-sectional view of a conventional fuse in which a low melting point organic material film is formed on an alumina substrate.
Shown in.

The fuse 10 covers an alumina substrate 11 having a thickness exceeding 0.4 mm, a low melting point organic material film 12 formed on the alumina substrate 11, and the low melting point organic material film 12. Film 13 formed as
And two heating resistors 14 formed on both ends of the metal film 13, and electrodes 15 formed on the ends of the two heating resistors 14, respectively.

When a current of a certain value or more flows between the two electrodes 15, 15, Joule heat generated inside the low melting point organic material film 12 and heat transferred from the heating resistor 14 through the metal film 13 are generated. As a result, the low-melting point organic material film 12 is melted and the circuit including the fuse is opened.

[0005]

As the alumina substrate used for the substrate of the above fuse, it is impossible to manufacture an alumina substrate having a small thickness in the related art.
Alumina substrates having a thickness exceeding m are used, and generally, those having a thickness of 0.6 mm or 0.8 mm are common. This conventional fuse using an alumina substrate has a problem that the thickness of the alumina substrate exceeds 0.4 mm and the fuse is too thick to be downsized, and the thicker the fuse is.

Further, the conventional alumina substrate has a rough surface, has undulations that hinder the uniformity of the film thickness, and has fine holes and projections. Therefore, (1) it is difficult to obtain a film having a constant thickness when forming a resistor or other film due to the undulations of the surface of the substrate, and (2) it is formed because of holes or protrusions on the surface of the substrate. Defects such as pinholes and protrusions occur in the film. Moreover, pattern formation is not normally performed due to these holes and protrusions.

As a result, there are problems that the resistance value of the fuses introduced into the circuit varies and the operation of the fuses becomes unstable. In view of the above circumstances, it is an object of the present invention to provide a fuse that is thin, light, and has stable performance.

[0008]

The present inventor has conducted various experiments and studies in order to achieve the above-mentioned object, and as a result, used an alumina substrate manufactured by a sol-gel method using a metal alkoxide as an insulating substrate. The inventors have found that the above problems can be solved by doing so, and completed the present invention.

Specifically, the fuse of the present invention for achieving the above object comprises an alumina substrate having a thickness of 0.03 mm or more and 0.4 mm or less and a fusible substance film formed on the alumina substrate. It is characterized by having. Here, a low melting point organic material film is used as the fusible substance film, a metal film is formed so as to cover the low melting point organic material film, and the current is interrupted by breaking the metal film when an overcurrent occurs. It is preferable.

Further, it is preferable to use a high resistance heating element such as nichrome as a heat source for melting the fusible film at the time of overcurrent. The electrodes formed on this fuse are preferably made of a thick film conductive material.

[0011]

The fuse of the present invention comprises the conventional alumina substrate having a thickness of more than 0.4 mm because the fusible film is formed on the alumina substrate having a thickness of 0.03 mm or more and 0.4 mm or less. The fuse is thinner than the fuse, and the thinner the alumina substrate is, the lighter the fuse is than the conventional fuse. Moreover, since the surface of the alumina substrate has few irregularities and is smooth, the film formed on the alumina substrate is a flat film with a certain thickness, and since there are no holes or protrusions on the surface of the alumina substrate, No defects such as pinholes and protrusions are generated in the film formed on the alumina substrate. As a result, the pattern obtained by etching the film formed on the alumina substrate is as designed, and a fuse with stable performance is obtained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the fuse of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a fuse using a high-purity alumina substrate manufactured by the sol-gel method as an insulating substrate. The fuse 20 includes an alumina substrate 21 having a thickness of 0.03 mm or more and 0.4 mm or less.
A low melting point organic material film 22 formed on the alumina substrate 21, a metal film 23 formed so as to cover the low melting point organic material film 22, and formed on both ends of the metal film 23. Two heating resistors 24 and electrodes 25 formed at the ends of the two heating resistors 24 are provided.

When a current of a certain value or more flows between the two electrodes 25, Joule heat generated inside the low melting point organic material film 22 and heat transferred from the heating resistor 24 through the metal film 23. As a result, the low melting point organic material film 22 is melted and the circuit including the fuse is opened. Further, when the overcurrent is generated, the metal film 23 is destroyed and the current is cut off.

Since the fuse 20 shown in FIG. 1 uses an alumina substrate having a thickness of 0.03 mm or more and 0.4 mm or less manufactured by the sol-gel method, it is thinner than a fuse using a conventional alumina substrate. Moreover, the thinner the alumina substrate is, the lighter it is compared to the conventional fuse. Moreover, since this alumina substrate is made of high-purity alumina, it has less holes or protrusions on the surface and less unevenness than the alumina substrate manufactured by the conventional manufacturing method, and has excellent surface smoothness. As a result, a thin film with no defects and a uniform film thickness can be formed on this alumina substrate,
Pattern formation is performed normally. As a result, the resistance value of the fuse introduced into the circuit becomes stable, and the operation of the fuse becomes stable. This makes it possible to manufacture a fuse with stable performance.

[0015]

As described above, the fuse of the present invention has a low melting point organic material film formed on an alumina substrate having a thickness of 0.03 mm or more and 0.4 mm or less. It becomes a thin and light fuse. In addition, since the surface of this alumina substrate has no holes or protrusions, has no irregularities, and has excellent surface smoothness, it is possible to form a thin film having no defects and a uniform film thickness on this alumina substrate, which improves performance. A stable fuse can be manufactured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a fuse using a high-purity alumina substrate manufactured by a sol-gel method as an insulating substrate.

FIG. 2 is a cross-sectional view showing a fuse in which a low melting point organic material film is formed on a conventional alumina substrate.

[Explanation of symbols]

 10, 20 Fuse 12, 22 Low melting point organic material film 13, 23 Metal film 14, 24 Heating resistor 15, 25 Electrode

Claims (1)

[Claims] 1. A fuse comprising: an alumina substrate having a thickness of 0.03 mm or more and 0.4 mm or less; and a fusible substance film formed on the alumina substrate.