JP2001143588A - Alloy fuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alloy fuse that ensures the effective operation at a temperature of 70 to 77 deg.C even with a diameter below 500 μm. SOLUTION: A fuse element is made of an alloy composed of 25 to 35 wt.% of Bi, 1.5 to 7.5 wt.% of Pb, and the remaining part of In.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an operating temperature of 70.degree.
It relates to a 77 ° C. alloy type temperature fuse.

[0002]

2. Description of the Related Art In an alloy type temperature fuse, a low melting point fusible alloy piece (fusing element) is connected between a pair of lead wires, and a flux is applied on the low melting point fusible alloy piece. The flux coated alloy piece is surrounded by an insulator, and it is used by attaching it to the electrical equipment to be protected.When the electrical equipment generates heat due to overcurrent, the low melting point fusible alloy piece is liquefied by the generated heat, In the coexistence of the molten metal and the flux that has already been melted, the molten metal is spheroidized by surface tension.

[0003] The basic condition required for the above low melting point fusible alloy is that it has a melting point determined from the permissible temperature of the equipment to be protected, and has a melting point between the solidus and liquidus at that melting point. The width of the liquid coexistence area is narrow. That is, in an alloy, there is usually a solid-liquid coexistence zone width between the solidus line and the liquidus line. In this area, the solid phase particles are dispersed in the liquid phase, and the liquid phase Because of the above-mentioned properties, the above-mentioned spheroidization may occur. Therefore, the temperature range (ΔT) belonging to the solid-liquid coexistence zone width before the liquidus temperature (T is this temperature) is considered. ), There is a possibility that the low-melting-point fusible alloy piece is spheroidized and divided. Therefore, the temperature fuse using such a low melting point fusible alloy piece must be treated as operating at a temperature range in which the fuse element temperature is (T-ΔT) to T. , .DELTA.T, that is, the narrower the solid-liquid coexistence area width, the smaller the variation in the operating temperature range of the temperature fuse, and the more accurately the temperature fuse can be operated at a predetermined set temperature. .

Conventionally, an alloy type temperature fuse having an operating temperature of about 70 ° C. has a melting temperature of 72 ° C. (solidus temperature of 70 ° C.).
(Bi-Pb-Sn-Cd alloy (50% by weight of Bi, 25% by weight of Pb, 12.5% by weight of Sn, 12.5% by weight of Cd and 12.5% by weight of Cd)) having a fuse element. ing.

[0005]

In recent years, in order to make the temperature fuse thinner, the fuse element has been required to be thinner, for example, as thin as 300 μmφ.
However, the aforementioned Bi-Pb-Sn-Cd alloy (Bi50
Wt%, Pb 25 wt%, Sn 12.5 wt%, Cd1
(2.5% by weight), the brittleness is high due to the large amount of Bi, the wire drawing is difficult, and the fuse element is 30%.
It is very difficult to make the diameter as small as 0 μmφ.

[0006] Under such thinning of the fuse element, the electric resistance value of the fuse element is considerably increased, and even at the time of rated energization, the fuse element becomes considerably high in temperature due to Joule heat, thereby causing an error. There is concern about the occurrence of operation.
That is, assuming that the temperature rise due to the Joule heat generation of the fuse element is Δθ and the melting point of the fuse element is T, the temperature fuse is operated at the temperature (T−Δθ). If the electrical resistance of the storage element increases and Δθ cannot be ignored, the power may be cut off before the equipment reaches a predetermined allowable temperature, and the electrical resistance is reduced to minimize the above Δθ. There is a need.

An object of the present invention is to provide an operating temperature of 70 ° C. to 77 ° C.
An object of the present invention is to provide an alloy type temperature fuse that can guarantee accurate operation under the above conditions even with a fuse element having a small diameter of less than 500 μmφ.

[0008]

The alloy type temperature fuse according to the present invention is composed of 25 to 35% by weight of Bi and 1.5 to 7% of Pb.
An alloy having a composition of 5% by weight and a balance of In is used as a fuse element.
0.5 to 5 parts by weight of Ag can be added to 0 parts by weight.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the temperature fuse according to the present invention, a circular wire having an outer diameter of less than 500 μmφ and a diameter of 200 μmφ or more or a flat wire having the same cross-sectional area as the circular wire can be used as the fuse element.

The alloy of the fuse element is Bi2
5 to 35% by weight, Pb 1.5 to 7.5% by weight, balance In
Is a Bi-Pb-In type, and the reference composition is Bi32.
7 wt%, Pb 3.8 wt%, In 63.5 wt%, the liquidus temperature is 75 ° C., and the solid-liquid coexistence zone width is 4 ° C.

The above Pb 1.5 to 7.5% by weight and the balance I
The ductility required for drawing and a sufficiently low electric resistance are imparted by n, and the melting point is set to a solid-liquid coexistence region of 68 ° C. to 75 ° C. while maintaining the above ductility and low resistivity by 25 to 35% by weight of Bi. You. The highest liquidus temperature of such an alloy composition is 75 ° C, the lowest solidus temperature is 68 ° C, and the solid-liquid coexistence zone width is about 4 ° C on average. Since the temperature difference between the fuse element of the temperature fuse and the equipment is about 2 ° C due to the thermal resistance therebetween, the operating temperature of the temperature fuse using this reference composition is 70 ° C. ~ 77 ° C. The specific resistance of the fuse element is approximately 30 to 40 μΩ · c.
m.

Ag is added to 100 parts by weight of the above-mentioned alloy composition.
By adding 5 to 5 parts by weight, the specific resistance can be increased to 30 to 4 parts by weight.
0 μΩ · cm can be further reduced. For example, by adding 2 parts by weight, the specific resistance is 25 μΩ · cm.
cm.

The fuse element of the temperature fuse according to the present invention is manufactured by drawing an alloy base material, and can be used as it is in a round cross section or in a flattened form.

FIG. 1A is an explanatory plan view showing a thin alloy-type temperature fuse according to the present invention, and FIG. 1B is a cross-sectional view taken along the line in FIG. Thickness 100-30
A 100 μm thick plastic base film 11
The band-shaped lead conductors 3 to 3 having a thickness of about 200 μm are fixed by an adhesive or fusion bonding, and the wire diameter is 500 μmφ between the band-shaped lead conductors.
And a flux 5 is applied to the fuse element 4, and the flux-coated fuse element is fixed to the plastic cover film 12 having a thickness of 100 to 300 μm by an adhesive or fusion. Sealed with.

The alloy type temperature fuse of the present invention can be implemented in a case type, a substrate type or a resin dipping type. 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 cylinder is inserted and each end of the cylinder and each lead wire are sealed with an adhesive, for example, an epoxy resin, or a line-shaped piece is attached to the end between parallel lead wires. Welding the fuse element, applying a flux on the fuse element, placing a flat ceramic cap on the flux-coated fuse element, and applying an epoxy resin between the opening of the cap and the lead wire. A sealed radial type 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, can be used.

In the above-mentioned substrate type, a fuse element of a linear piece is welded to an end 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.

As the above-mentioned 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, 10 to 40 parts of stearic acid.
Parts by weight, 0 to 3 parts by weight of activator can be used. in this case,
As the rosin, natural rosin, modified rosin (for example, hydrogenated rosin, disproportionated rosin, polymerized rosin) or these purified rosins can be used. As the activator, diethylamine hydrochloride, hydrobromide, or the like can be used. Can be used.

[0019]

EXAMPLES [Example] Bi: 32.7% by weight, Pb:
An alloy composition of 3.8% by weight and In: 63.5% by weight was used. The liquidus temperature of this alloy is 75 ° C., and the solid-liquid coexistence zone width is 4 ° C. The base material of this alloy composition is drawn to have a diameter of 30
It was processed into a 0 μmφ line. The area reduction rate for one die was 6.5%, and the drawing speed was 30 m / min.
There was no disconnection. When the specific resistance of this wire was measured, it was 34 μΩ · cm. This wire was cut into a length of 4 mm to form a fuse element, and a substrate-type temperature fuse was prepared. A composition of 80 parts by weight of rosin, 20 parts by weight of stearic acid, and 1 part by weight of diethylamine hydrobromide was used as a flux, and an epoxy resin cured at room temperature was used as a resin material.

The 50 samples of this embodiment were immersed in an oil bath at a heating rate of 1 ° C./min 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 ± 1 ° C. In addition, about 50 ° C. was applied to 50 pieces of the example product while applying a current of 1 amp.
Aging for 1000 hours in the atmosphere of
There was no blowout, and a malfunction caused by self-heating could be avoided. For these, the oil temperature at the time of energization cutoff due to fusing was measured in the same manner as described above, and was found to be substantially within the above-mentioned 73 ± 1 ° C.

Comparative Example 1 A Bi-Pb-Sn-Cd alloy (Bi50% by weight, Pb2) having a melting point of 72 ° C. (solidus temperature 70 ° C., liquidus temperature 72 ° C.) was added to a low melting point fusible alloy.
(5% by weight, Sn 12.5% by weight, Cd 12.5% by weight)
, Using a surface reduction rate of 5.0% and a drawing speed of 20 m / min.
Was tried to draw a thin wire having a diameter of 300 μmφ. However, the wire was frequently broken and it was extremely difficult. The specific resistance of this line is
It was 69 μΩ · cm. A substrate-type temperature fuse was prepared using the thin wire as a fuse element in the same manner as in the embodiment.
When the oil temperature at the time of energization cutoff due to fusing was measured by immersing in a / 1 minute oil bath, there were many that did not melt even when the liquidus temperature reached 72 ° C or higher. This is because a thick oxide film is formed on the fuse element surface due to the rotating drum spinning method, and this oxide film serves as a sheath to form the fuse.
This is presumed to be due to the fact that the element is less likely to be blown.

Comparative Example 2 Bi: 33.0% by weight, P
An alloy composition of b: 8.0% by weight and In: 59.0% by weight was used. 300 mm in diameter by drawing in the same manner as in the example.
It was processed into a μmφ line. When the specific resistance of this wire was measured, it was 49 μΩ · cm. A substrate-type temperature fuse was manufactured in the same manner as in the embodiment, and was heated to about 65 ° C. under a current of 1 amp.
When aging was performed for 1000 hours in the atmosphere described above, most of the aging was caused by self-heating.

[0023]

The alloy type temperature fuse according to the present invention has a low solid-liquid coexistence region of 74 to 68 ° C., a solid-liquid coexistence region width of 5 ° C. or less, and a specific resistance of about 30 to 40 μΩ · cm. Since the fuse element is made of an alloy having a specific resistance, even if the fuse element diameter is as small as 300 μm, malfunctions due to self-heating are well eliminated and the apparatus is operated at a predetermined temperature of 70 ° C. to 77 ° C. Can be cut off, and the fuse element does not contain harmful metals such as Cd.
It is extremely useful as a thin alloy-type temperature fuse having a temperature of from 70 to 77 ° C.

[Brief description of the drawings]

FIG. 1 is a drawing showing an example of an alloy type temperature fuse according to the present invention.

[Explanation of symbols]

 4 fuse element

Claims (2)

[Claims] 1. 25 to 35% by weight of Bi, 1.5 to 7% of Pb.
An alloy type temperature fuse, wherein an alloy having a composition of 5% by weight and the balance of In is used as a fuse element. 2. Bi 25-35% by weight, Pb 1.5-7.
5% by weight, the balance of 100 to 100 parts by weight of In is 0.5 to 5% of Ag.
An alloy-type temperature fuse characterized in that an alloy having a composition added in parts by weight is used as a fuse element.