JP4369008B2

JP4369008B2 - Alloy type temperature fuse

Info

Publication number: JP4369008B2
Application number: JP2000105933A
Authority: JP
Inventors: 嘉明田中
Original assignee: 内橋エステック株式会社
Priority date: 2000-04-07
Filing date: 2000-04-07
Publication date: 2009-11-18
Anticipated expiration: 2020-04-07
Also published as: JP2001291459A

Description

[Industrial application fields]
[0001]
The present invention relates to an alloy type temperature fuse having an operating temperature of 65 ° C to 75 ° C.
[Prior art]
[0002]
In the alloy type temperature fuse, a low melting point soluble alloy piece coated with a flux is used as a fuse element, and it is used by being attached to an electric device to be protected. As a result, the low-melting-point soluble alloy piece is made into a liquid phase, and the molten metal is spheroidized by surface tension in the presence of the flux, and is divided by the progress of spheronization, and the current supply to the device is cut off.
[0003]
One of the requirements for the low melting point soluble alloy is that the solid-liquid coexistence area between the solid phase line and the liquid phase line is narrow.
That is, in an alloy, there is usually a solid-liquid coexistence zone between the solid phase line and the liquid phase line. In this region, the solid phase particles are dispersed in the liquid phase. Therefore, the above spheroidization may occur. Therefore, the temperature range (ΔT) belonging to the solid-liquid coexistence region before the liquidus temperature (this temperature is T). ), The low melting point soluble alloy piece may be spheroidized. Thus, in the temperature fuse using such a low melting point soluble alloy piece, the fuse element temperature must be handled as operating in a temperature range of (T−ΔT) to T. The smaller the ΔT is, that is, the narrower the solid-liquid coexistence region, the smaller the variation in the operating temperature range of the temperature fuse, and the temperature fuse can be operated at a predetermined set temperature. Therefore, an alloy used as a fuse element for a temperature fuse is required to have a narrow solid-liquid coexistence region.
[0004]
Furthermore, one of the requirements for the low melting point soluble alloy is that the electric resistance is low.
That is, assuming that the temperature rise due to normal heat generation based on the resistance of the low melting point soluble alloy piece is ΔT ′, the operating temperature is substantially lower by ΔT ′ and ΔT ′ is higher than when there is no temperature rise. Indeed, the operating error is substantially increased. Therefore, an alloy used as a fuse element for a temperature fuse is required to have a low specific resistance.
[0005]
[Problems to be solved by the invention]
Conventionally, as a fuse element of an alloy type temperature fuse having an operating temperature of 65 ° C. to 75 ° C., a 70 ° C. eutectic Bi—Pb—Sn—Cd alloy (Bi 50 wt%, Pb 26.7 wt%, Sn13. 3% by weight and Cd 10% by weight) are known, but contain Pb and Cd that are harmful to biological systems, and are unfit for environmental conservation, which is a recent global demand. In addition, due to the miniaturization of the fuse-type temperature fuse corresponding to the miniaturization of recent electrical and electronic equipment, the fuse element has become extremely thin (300 μm), and the Bi content is large and fragile. Therefore, it is difficult to draw such a fine wire, and it is difficult to deal with it, and under such a fine wire fuse element, the alloy composition has a relatively high specific resistance and a fine wire. Combined with this, the resistance value becomes extremely high, so that malfunction of the fuse element due to self-heating is inevitable.
[0006]
A 72 ° C. eutectic In—Bi alloy (In 66.3% by weight, Bi 33.7% by weight) is also known, but as is apparent from the thermal differential curve shown in FIG. Because this phase is a temperature at which the fuse element is exposed for a long time during normal operation of the equipment due to the relative relationship with the operating temperature of 65 ° C to 75 ° C, Distortion occurs due to the solid phase transformation, and as a result, the resistance value of the fuse element increases, and there is a concern about malfunction due to self-heating of the fuse element.
[0007]
Under the present situation, the present inventor can accurately reduce the fuse element diameter to about 300 μmφ without containing harmful metals and with an operating temperature of 65 ° C. to 75 ° C. As a result of diligent research to develop an alloy-type temperature fuse that can be operated, by adding 2.5 to 10% by weight of Sn to a 72 ° C. eutectic In-Bi alloy, I learned that phase transformation could be eliminated and that purpose could be achieved.
[0008]
The purpose of the present invention is based on such results, satisfying environmental protection requirements in the operating temperature range of 65 ° C to 75 ° C, and can reduce the fuse element diameter to about 300 µmφ and suppress self-heating well. It is an object of the present invention to provide an alloy type temperature fuse that can be operated accurately.
[0009]
[Means for Solving the Problems]
An alloy type temperature fuse according to claim 1 of the present invention is a temperature fuse in which a low melting point soluble alloy is a fuse element, and the alloy composition of the low melting point soluble alloy is Bi25 to 35% by weight, The composition is characterized in that Sn is 2.5 to 10% by weight and the balance is In.
[0010]
The alloy type temperature fuse according to claim 2 of the present invention is a temperature fuse in which a low melting point soluble alloy is a fuse element, and the alloy composition of the low melting point soluble alloy is Bi25 to 35% by weight, The composition is characterized in that it has a composition in which 0.5 to 3.5 parts by weight of Ag is added to 100 parts by weight of Sn 2.5 to 10% by weight and the balance In, and the specific resistance is reduced by the addition of Ag. In addition, the variation of the operating temperature can be further suppressed by narrowing the width of the solid-liquid coexistence region without changing the operating temperature.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In the alloy type temperature fuse according to the present invention, a circular wire having an outer diameter of 200 μmφ to 500 μmφ, preferably 250 μmφ to 350 μmφ, or a flat wire having the same cross-sectional area as that of the circular line can be used as the fuse element.
[0012]
This fuse element alloy is Bi25-35 wt%, Sn2.5-10 wt%, the balance In, preferably Bi29-333 wt%, Sn3-6 wt%, the balance In, and the reference composition is Bi32 0.7 wt%, Sn 3.8 wt%, and In 63.5 wt%, the liquidus temperature is 71 ° C., and the solid-liquid coexistence zone width is 3 ° C.
[0013]
The blending amount of In and Bi temporarily sets the melting point to around 70 ° C. and gives sufficient ductility necessary for thin line drawing. The range of solidus temperature and liquidus temperature is 65 ° C. due to the blending of Sn. The specific resistance is set low while being finally set to ˜75 ° C.
If the lower limit of the amount of Sn is less than the amount of claim 1, not only the amount of Sn is insufficient and it is difficult to achieve the above results, but the above-mentioned solid phase transformation cannot be effectively prevented, and the upper limit of the amount of Sn is not limited. Exceeds the blending amount of claim 1, an In-Bi-Sn eutectic composition (In 42 wt%, Bi 29 wt%, Sn 13 wt%) having a melting point of 62 ° C. appears, and the solidus temperature and liquidus temperature are Not only can the range be kept between 65 ° C. and 75 ° C., but also noticeable variations in the operating temperature due to the bipolarization of the molten peak are inevitable.
With this composition, the total specific resistance can be lowered sufficiently because the total amount of In and Sn with low specific resistance is large compared to Bi with high specific resistance, and the fuse element has a low resistance even under an ultrafine wire of 300 μmφ. Resistance can be easily achieved, and as is apparent from FIG. 1 (DSC measurement result of In-32.7Bi-3.8Sn), solid phase transformation does not occur on the low temperature side of the operating temperature of 65 ° C. to 75 ° C. Since the resistance value change due to the solid phase transformation of the fuse element at the temperature during normal operation of the device with respect to the operating temperature of 65 ° C. to 75 ° C. can be eliminated, the operating temperature of the temperature fuse is set to 70 ° C. As a reference, it can be set within a range of ± 5 ° C.
The fuse element has a resistivity of 25 to 35 μΩ · cm.
[0014]
By adding 0.5 to 3.5 parts by weight of Ag to 100 parts by weight of the alloy composition, the resistivity can be made lower than the above, for example, by adding 3.5 parts by weight, about 10%. Can be lowered.
[0015]
The fuse element of the temperature fuse according to the present invention is manufactured by drawing an alloy base material, and can be used with a round cross section or further compressed into a flat shape.
[0016]
FIG. 2 shows a tape-type alloy-type temperature fuse according to the present invention, in which a strip-shaped lead conductor 1, 1 having a thickness of 100 to 200 μm is attached to an adhesive or a plastic base film 41 having a thickness of 100 to 300 μm. The fuse element 2 having a wire diameter of 250 .mu.m.phi. To 500 .mu.m.phi. Is connected between the belt-shaped lead conductors by bonding, and a flux 3 is applied to the fuse element 2, and the flux coating fuse element is thickened. It is sealed with an adhesive or fusion bonding of a 100 to 300 μm plastic cover film 41.
[0017]
The alloy type temperature fuse according to the present invention can also be implemented in the form of a cylindrical case type, a case type radial type, a substrate type, or a resin mold radial type.
FIG. 3 shows a cylindrical case type. A low melting point soluble alloy piece 2 is connected between a pair of lead wires 1 and 1, and a flux 3 is applied onto the low melting point soluble alloy piece 2. A heat-resistant and heat-conductive insulating cylinder 4, for example, a ceramic cylinder, is inserted over the flux-coated low-melting-point soluble alloy piece, and room temperature curing is performed between each end of the insulating cylinder 4 and each lead wire 1. Sealed with an adhesive, for example, an epoxy resin.
[0018]
FIG. 4 shows a case type radial type, in which a fuse element 2 is joined between the leading ends of the parallel lead conductors 1 and 1 by welding, and a flux 3 is applied to the fuse element 2. The coating fuse element is surrounded by an insulating case 4 having an opening at one end, for example, a ceramic case, and the opening of the insulating case 4 is sealed with a sealing material 5 such as an epoxy resin.
[0019]
FIG. 5 shows a substrate type. A pair of film electrodes 1 and 1 are formed on an insulating substrate 4, for example, a ceramic substrate, by printing and baking a conductive paste (for example, a silver paste). The conductor 11 is connected by welding or the like, the fuse element 2 is joined by welding between the electrodes 1 and 1, the flux 3 is applied to the fuse element 2, and the flux application fuse element is connected to the sealing material 4. For example, it is sealed with an epoxy resin.
[0020]
FIG. 6 shows a resin mold radial type, in which a fuse element 2 is joined between the end portions of the parallel lead conductors 1 and 1 by welding, and a flux 3 is applied to the fuse element 2. The coating fuse element is resin molded 5 by resin liquid dipping.
[0021]
In addition, a resistor (film resistance) is attached to a fuse with an energizing heating element, for example, an insulating substrate of a substrate type alloy-type temperature fuse, and when a device malfunctions, the resistor is energized to generate heat. It can also be implemented in the form of a substrate-type fuse with resistance that melts the low-melting-point soluble alloy piece with heat.
[0022]
As the above-mentioned flux, one having a melting point lower than that of the fuse element is usually used. For example, 90 to 60 parts by weight of rosin, 10 to 40 parts by weight of stearic acid, and 0 to 3 parts by weight of an activator are used. it can. In this case, natural rosin, modified rosin (eg, hydrogenated rosin, disproportionated rosin, polymerized rosin) or purified rosin can be used as the rosin, and diethylamine hydrochloride or hydrobromic acid can be used as the activator. Salt and the like can be used.
[0023]
【Example】
[Example 1]
A base material having an alloy composition of 63.5 wt% In, 32.7 wt% Bi, and 3.8 wt% Sn was drawn and processed into a wire having a diameter of 300 μmφ. The pulling rate for one die was 6.5%, and the drawing speed was 45 m / min, but there was no disconnection.
The resistivity of this line was measured and found to be 32 μΩ · cm.
This line was cut to a length of 4 mm to form a fuse element, and a tape type temperature fuse was prepared. The flux used was a composition of 80 parts by weight of rosin, 20 parts by weight of stearic acid, and 1 part by weight of diethylamine hydrobromide. Polyethylene terephthalate having a thickness of 200 μm was used for the plastic base film and the plastic cover film. -A film was used.
[0024]
50 pieces of this example product were immersed in an oil bath with a heating rate of 1 ° C./min while applying a current of 0.1 ampere, and the oil temperature at the time of cutting off the current due to fusing was measured. It was within the range of ° C. When the same measurement was performed with the energization current being 1/10, no difference was observed substantially, and it was confirmed that there was no influence of self-heating.
Further, within the range of the alloy composition described above, the operating temperature could be kept within a range of ± 5 ° C. centering on 70 ° C.
[0025]
[Example 2]
A base material having an alloy composition of In 61.3 wt%, Bi 31.6 wt%, Sn 3.7 wt%, and Ag 3.4 wt% was drawn into a wire having a diameter of 300 μmφ. The pulling rate for one die was 6.5%, and the drawing speed was 45 m / min, but there was no disconnection. The resistivity of this line was measured and found to be 29 μΩ · cm.
This line was cut to a length of 4 mm to form a fuse element, and a tape type temperature fuse similar to that in Example 1 was prepared.
[0026]
50 pieces of this example product were immersed in an oil bath with a heating rate of 1 ° C./min while applying a current of 0.1 ampere, and the oil temperature at the time of cutting off the current due to fusing was measured. It was within the range of ° C. When the same measurement was performed with the energization current being 1/10, no difference was observed substantially, and it was confirmed that there was no influence of self-heating.
Further, within the range of the alloy composition described above, the operating temperature could be kept within a range of ± 4 ° C. centering on 70 ° C.
[0027]
[Comparative example]
A base material having an alloy composition of 66.3% by weight of In and 33.7% by weight of Bi was drawn and processed into a wire having a diameter of 300 μmφ. The pulling rate for one die was 6.5%, and the drawing speed was 45 m / min, but there was no disconnection.
The resistivity of this line was measured and found to be 37 μΩ · cm.
This line was cut to a length of 4 mm to form a fuse element. A tape type temperature fuse was prepared in the same manner as in Example 1, and the operating temperature was measured. The thing which operate | moved at 74 degreeC vicinity was seen, and the variation in operating temperature was recognized.
This is due to the solid phase transformation on the low temperature side, and it was confirmed that Sn was blended in the fuse element of the temperature fuse according to the present invention.
[0028]
【The invention's effect】
According to the present invention, an ultrafine wire fuse element of 300 μmφ class is manufactured by efficient drawing of a Bi—In—Sn low melting point soluble alloy base material that does not affect the biological system. Can be used to obtain an alloy-type temperature fuse that has an operating temperature of 65 ° C. to 75 ° C. and can sufficiently prevent an operation error due to self-heating.
[Brief description of the drawings]
FIG. 1 is a drawing showing DSC measurement results of In-32.7Bi-3.8Sn.
FIG. 2 is a drawing showing an example of an alloy type temperature fuse according to the present invention.
FIG. 3 is a drawing showing another example of the alloy type temperature fuse according to the present invention.
FIG. 4 is a drawing showing another example of the alloy type temperature fuse according to the present invention.
FIG. 5 is a drawing showing another example of the alloy type temperature fuse according to the present invention.
FIG. 6 is a drawing showing another example of the alloy type temperature fuse according to the present invention.
FIG. 7 is a drawing showing DSC measurement results of In-33.7Bi.
[Explanation of symbols]
2 fuse elements

Claims

In a temperature fuse in which a low melting point fusible alloy is a fuse element, the alloy composition of the low melting point fusible alloy is Bi25 to 35 wt%, Sn 2.5 to 10 wt%, and the balance In. Alloy type temperature fuse to be used.
In a temperature fuse in which a low melting point soluble alloy is a fuse element, the alloy composition of the low melting point soluble alloy is 25 to 35% by weight of Bi, 2.5 to 10% by weight of Sn, and Ag in 100 parts by weight of the balance In. An alloy type temperature fuse characterized by having a composition with 0.5 to 3.5 parts by weight added.