JPH1140025A - Thermal alloy fuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set the operating temperature within a specific range and facilitate the production of a low resistance thermal alloy fuse by constituting a low melting point fusible alloy out of a specific wt.% of Bi, a specific wt.% of Cd, a specific wt.% of Sn and the remainder of In. SOLUTION: This thermal alloy fuse is composed by such a process that a fuse element is coated with flux, a lead wire is connected to the rear end of each electrode and an epoxy-coated layer is formed on one side of an insulating board. In this case, a base alloy material used for the fuse element comprises 0.3-6 wt.% of Bi, 10-18 wt.% of Cd, 35-48 wt.% of Sn and the remainder of In, preferably 0.5-4 wt.% of Bi, 12-14 wt.% of Cd, 39-42 wt.% of Sn and the remainder of In. The base alloy material is drawn so that it can be used in the cross-sectionally round shape as it is or can be used after further formed into a flat shape by means of compression process. Accordingly, a thermal alloy fuse having an operating temperature ranging from 86 to 90 deg.C and low resistance can be produced by using it with a high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION

The present invention relates to an alloy type temperature fuse.

[Prior art]

[0002] An alloy type temperature fuse has a low melting point fusible alloy piece (fuse element) connected between a pair of lead wires.
The flux is applied on the low melting point fusible alloy piece, and the flux coated alloy piece is surrounded by an insulator, and is used by being attached to an electric device to be protected.

In this case, when electric equipment generates heat due to overcurrent, the low melting point fusible alloy piece is liquefied by the generated heat, and the molten metal is made spherical by surface tension in the coexistence with the already melted flux. Is cut off by the progress of spheroidization, and the power supply to the device is cut off.

[0004] One of the requirements required for the low melting point fusible alloy is that the solid-liquid coexistence region between the solidus line and the liquidus line is narrow. That is, usually, in an alloy, a solid-liquid coexistence region exists between the solidus line and the liquidus line, and in this region,
Since the solid particles are dispersed in the liquid phase and have a liquid-like property, the above-mentioned spheroidization may occur. T)
Previously, in the temperature range belonging to the solid-liquid coexistence region (referred to as ΔT),
There is a possibility that the low-melting-point fusible alloy piece is spheroidized and divided. Thus, in the temperature fuse using the low melting point fusible alloy piece, the fuse element temperature is (T-ΔT) to T
Therefore, the smaller the ΔT, that is, the narrower the solid-liquid coexistence area, the smaller the variation in the operating temperature range of the temperature fuse, and the lower the temperature fuse. Can be operated at a predetermined set temperature. Therefore, the alloy used as the fuse element of the temperature fuse must first have a narrow solid-liquid coexistence region. In addition, the fuse of the temperature fuse
Since the drawing element is used in the form of a linear piece, it is required to be capable of drawing.

[0005]

Conventionally, an operating temperature of 10
An alloy mold temperature fuse of 0 ° C or less has a melting temperature of 95 ° C.
A Bi-Pb-Sn-based eutectic alloy as a fuse element, and a Bi-Pb-Sn-Cd alloy (Bi50) having a melting temperature of 72 ° C (solidus temperature 70 ° C, liquidus temperature 72 ° C).
Wt%, Pb 25 wt%, Sn 12.5 wt%, Cd1
(2.5% by weight) as a fuse element is widely used. However, the separation between the operating temperatures of these temperature fuses reaches 20 ° C. or more, and a temperature fuse having an intermediate temperature between them as the operating temperature is required.

Hitherto, Bi-I has been known as a low melting point solder having a solid-liquid coexisting region between 80 ° C. and 90 ° C. and having a width within an allowable range (within 4 ° C.) for the operation of a temperature fuse.
n-Sn eutectic alloy (eutectic point temperature 82 ° C, eutectic composition Sn4
(6% by weight, In 50% by weight, Bi 4% by weight) are known, but they are very brittle, making it difficult to work as a fuse element, and it is difficult to use a temperature fuse as a fuse element. .

Therefore, the applicant of the present invention has proposed a fuse element having a reference composition of 1.0% by weight of Sn, 52.5% by weight of In, the balance of Bi having a liquidus temperature of 87 ° C., and a solid-liquid coexistence region width of 3 ° C. Have already been proposed (Patent Application No. 139398 of 1993). However, in this alloy type temperature fuse, the electric resistance of the fuse element is slightly high, and there is a case where the use is restricted due to the current capacity. The main reason for this relatively high electrical resistance is that B
The amount of i is large and the amount of Sn is small. However, if Bi is reduced and Sn is increased in the system having the above-described reference composition, the operating temperature deviates from 86 ° C to 90 ° C.

It is an object of the present invention to operate at an operating temperature of 86.degree.
It is an object of the present invention to provide an alloy type temperature fuse which can easily produce an alloy type temperature fuse having a low temperature and a low resistance.

[0009]

An alloy type temperature fuse according to the present invention is a temperature fuse having a low melting point fusible alloy as a fuse element.
i 0.3 to 6% by weight, Cd 10 to 18% by weight, Sn35
~ 48% by weight, with the balance being In.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As the type of the alloy type temperature fuse of the present invention, any of a case type, a substrate type and a resin dipping type can be used. As a case type, a fuse element of a linear piece is welded between lead wires that are opposed to each other in a straight line, a flux is applied on the fuse element, and a flux is applied on the fuse-coated fuse element. An axial type in which a ceramic tube is inserted and each end of the tube and each lead wire are sealed with an adhesive, for example, an epoxy resin, or a linear piece is attached to the end between parallel lead wires. The fuse element is welded, a flux is applied on the fuse element, a flat ceramic cap is placed on the fuse-coated fuse element, and an epoxy resin is placed between the opening of the cap and the lead wire. Radial type sealed with can be used.

As the resin dipping type, a radial type in which an epoxy resin coating layer is provided on a flux-coated fuse element by immersion in an epoxy resin liquid, instead of surrounding the ceramic cap.

In the above-mentioned substrate type, a fuse element of a linear piece is welded to a tip between the electrodes of an insulating substrate having a pair of layered electrodes provided on one surface, and a flux is applied on the fuse element. A structure in which a lead wire is connected to the rear end of each electrode and an epoxy resin coating layer is provided on one surface of an insulating substrate can be used, and either an axial or radial system can be used.

The fuse element includes Bi0.3
-6% by weight, Cd 10-18% by weight, Sn 35-48% by weight, balance In, preferably Bi 0.5-4% by weight,
Cd 12-14% by weight, Sn 39-42% by weight, balance I
The alloy base material of n can be used by drawing, and it can be used as it is with a round cross-section or by further flattening.

The reference composition of the above alloy composition is Bi: 2.9.
%, Cd: 13.6% by weight, Sn: 40.8% by weight, In: 42.7% by weight, and the liquidus temperature was 87%.
℃, the solid-liquid coexistence zone width is 4 ℃.

In the alloy type temperature fuse, the temperature fuse surface temperature is approximately 1 ° C. higher than the fuse element temperature due to the thermal resistance between the temperature fuse surface and the fuse element. The operating temperature of the temperature fuse using the above standard composition as a fuse element is 90 ° C to 86 ° C.

In the alloy having the above composition, Sn and In
Gives the ductility required for drawing, and Bi and Cd bring the melting point close to 90 ° C. and set it to a melting point of 89 ° C. to 85 ° C. (the temperature between the solidus line and the liquidus line). The above C
With respect to d and its compounding amount, the range of the operating temperature of the temperature fuse is ± 2 ° C. under a relatively large amount of Bi of 0.3 to 6% by weight and a relatively large amount of Sn of 35 to 48% by weight. (At around 88 ° C.), and by sufficiently reducing Bi with respect to Sn, a sufficiently low electric resistance of the fuse element can be achieved.

As the above flux, a flux whose melting point is lower than that of the fuse element is usually used. For example, 90 to 60 parts by weight of rosin, stearic acid 1
0-40 parts by weight, 0-3 parts by weight of activator can be used. In this case, a natural rosin, a modified rosin (for example, hydrogenated rosin, disproportionated rosin, polymerized rosin) or a purified rosin thereof can be used as the rosin, and a hydrochloride or a bromate of diethylamine can be used as the activator. Can be used.

According to the present invention, the operating temperature is from 86.degree.
It is possible to produce an alloy type temperature fuse having a low resistance at a temperature of ° C. with a good yield. This is clear from the following examples.

【Example】

Example 1 A base material having an alloy composition of Bi: 2.9% by weight, Cd: 13.6% by weight, Sn: 40.8% by weight, and In: 42.7% by weight was drawn to have a diameter of 0.6 mm. Was processed into a line. The drop rate for one die was 6.5%, and the drawing speed was 45 m / min, but there was no disconnection.
When the resistance value of this wire was measured, it was 0.6 Ω / m. This wire was cut into a length of 6 mm to form a fuse element, and a cylindrical temperature fuse was prepared. A tin-plated copper wire with an outer diameter of 0.6 mm is used for the lead wire, and an inner diameter of 1.5 mm is used for the cylinder.
The ceramic cylinder of No. 1 was composed of 80 parts by weight of rosin and 20 parts by weight of stearic acid as flux, and epoxy resin cured at room temperature as adhesive.

Fifty samples of this example were immersed in an oil bath at a heating rate of 1 ° C./1 minute while applying a current of 0.1 amperes, and the oil temperature was measured when the current was cut off by fusing. It was within the range of 88 ± 1 ° C. Further, it was confirmed that the operating temperature could be kept within a range of ± 2 ° C. around 88 ° C. within the range of the alloy composition described above.

Comparative Example 1 Sn 1.0% by weight, In5
In the same manner as in the example except that a base material having an alloy composition of 2.5% by weight and Bi 46.5% by weight was used, a cylindrical temperature fuse was formed using a drawn wire having a diameter of 0.6 mm as a fuse element. Created. The temperature characteristics were almost the same as in Example 1, but the resistance value of the fuse element was 1.9 Ω / m.
, Which was at least three times that of the comparative example.

[Comparative Example 2] Sn46 was added to the low melting point fusible alloy.
Wt%, In50 wt%, Bi4 wt%, eutectic point temperature 8
An alloy at 2 ° C. was used. Since it was difficult to make the wire thinner by drawing, it was made thinner by a rotary drum type yarn prevention method, and a cylindrical temperature fuse was formed as a fuse element in the same manner as in the embodiment, and the operating temperature was measured. Many fuse elements did not melt even when the eutectic point temperature reached 82 ° C. This is because a thick oxide film is formed on the fuse element surface due to the rotating drum type yarn protection method,
This is presumed to be because the oxide film becomes a sheath, and the fuse element is melted and becomes difficult.

[0022]

According to the present invention, a fuse element is manufactured by efficiently drawing a low-melting-point fusible alloy base material, and an operating temperature of 86 ° C. to 90 ° C. is used by using the fuse element.
In addition, it is possible to provide an alloy type temperature fuse having a low resistance and a sufficiently large current capacity.

Claims (1)

[Claims] In a temperature fuse using a low-melting-point fusible alloy as a fuse element, the alloy composition of the low-melting-point fusible alloy is 0.3 to 6% by weight of Bi, 10 to 18% by weight of Cd,
An alloy-type temperature fuse characterized in that n is 35 to 48% by weight and the balance is In.