JP2000200539A - Fuse element and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable fuse element in which breaking caused by an excessive current occurs surely on a fuse part, and its manufacturing method. SOLUTION: This fuse element has a fuse part 14 formed on an insulating substrate 12 and composed of a low melting-point metal film or the like melting at a prescribed temperature, and conductor parts 16, 18 connected to the fuse part 14. The fuse element is equipped with electrodes 22 connected to the conductor parts 16, 18 and formed on the end face of the substrate 12, and auxiliary conductor films 24 laminated on the corner part contacting with the electrodes 22 on the substrate 12 end edge parts of the conductor parts 16, 18. The auxiliary conductor films 24 are laminated on the lower layer of the conductor parts 16, 18 on the periphery of the corner parts contacting with the electrodes 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuse element for protecting circuits and other important parts from damage caused by overcurrent or heating during use of electronic parts and electric products, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a fuse element such as a fuse that blows at a predetermined temperature is provided with an overcurrent protection function that operates mainly by generating an overcurrent, or a PTC.
Some devices, such as elements and bimetal switches, have a heating protection function that operates by heating.

As shown in the cross-sectional view of FIG. 3, a fuse element, which is blown by an excessive current to cut off a circuit, includes a pair of conductors 4 on the surface of an insulating substrate 2 and a pair of conductors 4. In some cases, a fuse metal film 6 was provided between the four. The electrode of this fuse element had an electrode 10 formed in a recess 8 formed by a through hole formed in the substrate 2 before division as shown in FIG.

[0004]

In the prior art, the resistance of the fuse element between the pair of electrodes 10 is determined by the resistance of the through-hole electrode 10, the resistance of the conductor 2, and the resistance of the fuse metal film 6. Consists of If there is a portion of the resistance value of each portion having a higher resistance value than the fuse metal film 6 due to a variation at the time of manufacturing or the like, the portion may be damaged by an excessive current. In particular, the thickness of the conductor portion at the corner 2a of the substrate 2 between the electrode 10 and the conductor portion 4 is thin, and the resistance value of this portion becomes higher than that of the other portions. there were.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a highly reliable fuse element which is reliably broken by an excessive current in a fuse portion, and a method of manufacturing the same. And

[0006]

According to the present invention, there is provided a fuse element formed of a low melting point metal film formed on an insulating substrate and melted at a predetermined temperature, and a conductor connected to the fuse. An electrode connected to the conductor and formed on the end face of the substrate; and an auxiliary conductor film laminated on a corner of the conductor at the edge of the substrate and in contact with the electrode. The auxiliary conductor film is laminated below the conductor portion around a corner in contact with the electrode. The resistance of the electrode and the conductor is lower than the resistance of the fuse.

Further, in the method of manufacturing a fuse element according to the present invention, a through hole is formed in an insulating substrate, and an auxiliary conductor film and a conductor portion having a predetermined length are formed around the periphery of the through hole. A fuse portion is provided so as to be in contact with the portion, and the substrate is divided along the through hole.

In the fuse element according to the present invention, when an overcurrent flows through the fuse section, the circuit is cut off at the fuse section. At this time, at the corner of the substrate between the electrode and the conductor, the resistance between the electrode and the conductor is set lower than that of the fuse by the auxiliary conductor film, so that the fuse is reliably blown.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show a fuse element according to an embodiment of the present invention. The fuse element includes a chip-shaped substrate 12 made of ceramics or the like and a fuse portion 14 of a fuse metal film formed on the substrate 12.
And Both ends of the fuse portion 14 are connected to the conductor portion 1 respectively.
6 and 18.

The conductors 16 and 18 are respectively connected to the corners of a pair of recesses 20 formed on the end face of the substrate 12,
An electrode 22 is formed in the recess 20. Auxiliary conductor films 24 and 26 are formed near the corners 20a of the recess 20 below the conductors 16 and 18.

The fuse portion 14 is made of a low melting point metal such as Pb.
And Pb-Sn, Pb-Sb, Sn-
It is made of an Sb-based solder metal or the like and has as low a resistance value as possible. The conductor portions 16 and 18 are a thick film conductor material obtained by printing and firing silver paste. Auxiliary conductor film 2
4 and 26 are also made of a solder material such as Pb. The surface of the fuse portion 14 is coated with a solder flux 28 for ensuring melting at about two places. Here, the conductor portions 16 and 18 and the electrode 22 are formed such that the resistance value is smaller than that of the fuse portion 14.

Next, a method of manufacturing the fuse element will be described. First, a plurality of through holes serving as the concave portions 20 are formed on the large substrate 12 before the division. A solder cream forming the electrode 22 is applied to the inside of the through-hole, and a solder cream serving as a conductor material for forming the auxiliary conductive films 24 and 26 is also applied around the through-hole. After this,
The solder cream is melted to form conductor layers each made of a solder material.

The conductors 16 and 18 are formed by printing silver paste over a predetermined length from the through hole. After that, the conductor portions 16 and 18 are cured, and the fuse portion 14 is formed between the conductor portions 16 and 18.

The formation of the fuse portion 14 is performed by the conductor portions 16 and 1
A paste of a low-melting metal material for forming the fuse portion 14 between the portions 8 is applied, melted and solidified to form a state connected to the conductor portions 16 and 18. Further, on the surface of the fuse portion 14, a flux 28 for ensuring the melting of the fuse portion 14 is provided.
Is applied.

The fuse element of this embodiment has a conductor 1
Substrate 12 between 6, 18 and each electrode 22 connected thereto
An auxiliary conductor film 24 is formed below the conductor films 16 and 18 in contact with the corners 20a. Therefore, the corner 20
The conductor portion a is formed thick and has low electric resistance.
Further, since the resistance of the conductors 16 and 18 and the resistance of the electrode 22 are formed to be lower than those of the fuse 14, the fuse 14 is reliably blown by an excessive current.

The member forming the fuse element of the present invention is not limited to the above-described example, but may be any member as long as the resistance value of the fuse portion is set to be higher than that of the electrode or other conductor portion. The material, width, thickness and the like can be appropriately selected. For example, the electrode portion may be formed by applying a conductive paste to the through hole, and the auxiliary conductive film may be formed by applying the conductive paste. Further, the holding conductor film may be formed on the surface side of the conductor portion.

[0017]

The fuse element according to the present invention has a function of protecting the circuit of an electronic device by immediately fusing the fuse portion when an excessive current is generated, cutting off a current supply state. Further, at this time, no break occurs at a portion outside the fuse portion, and the fuse portion is reliably blown under a predetermined condition. Furthermore, the fuse element of the present invention has a simple structure, can simplify the manufacturing process, and can reduce the cost.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal sectional view of the fuse element of the embodiment.

FIG. 3 is a longitudinal sectional view showing a conventional fuse element.

[Explanation of symbols]

 12 Substrate 14 Fuse part 16, 18 Conductor part 20 Depression 22 Electrode 24 Auxiliary conductor film

Continuing from the front page (72) Inventor Morikatsu Yamazaki 3158, Shimo-Okubo, Osawano-cho, Kamishinkawa-gun, Toyama Prefecture (72) Inventor Yutaka Nomura 3158, Shimo-Okubo, Osawano-cho, Kamishinkawa-gun, Toyama Hokuriku Electric Industry Co., Ltd. F-term (reference) 5G502 AA01 BA08 BB13 BC01 BD02 JJ01

Claims (3)

[Claims] A fuse formed on an insulating substrate and melting at a predetermined temperature; a conductor connected to the fuse; an electrode connected to the conductor and formed on an end surface of the substrate; A fuse element comprising an auxiliary conductor film laminated on a corner portion of the conductor portion which is in contact with the electrode at an edge of the substrate. 2. The fuse element according to claim 1, wherein the auxiliary conductor film is laminated below the conductor portion around a corner in contact with the electrode. 3. A plurality of through-holes are formed in an insulating substrate, and an auxiliary conductor film and a conductor having a predetermined length are formed on the periphery of the through-holes, respectively, so as to be in contact with a pair of the conductors. A method for manufacturing a fuse element, comprising: providing a fuse portion; and thereafter dividing the substrate along the through hole.