JP2005285561A - Use method for alloy-type temperature fuse, and the alloy-type temperature fuse - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for using an alloy-type temperature fuse rationally by imposing long time direct current carrying stability which is an excessive load condition more than a case of use under alternate current, when using the alloy type temperature fuse using In-Sn alloy as a fuse element under direct current because there is inconvenience by long time direct current carrying, for example, fatal defects for direct current, such as long-term direct current carrying destruction, irrespective of the advantages for removing unevenness in operation temperature by In-Sn alloy of In 85 to 52% and ensuring satisfactory yield for proper ductility. <P>SOLUTION: The alloy type temperature fuse exclusively for alternate current at predetermined operation temperature, using the fuse element made of an In-Sn alloy and alternate current electronic/electric equipment are protected from overheating. Protection of direct current electronic/electric equipment for overheating at the temperature is performed by the alloy-type temperature fuse for direct current, having alloy component of the fuse element having alloy element different from that of the alloy-type temperature fuse exclusively for alternate current. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention imposes long-term DC current stability, which is an overload condition when using an alloy-type thermal fuse having an In-Sn alloy as a fuse element under direct current, compared to when using it under alternating current. It relates to a method for rationally using a thermal fuse.

  In an alloy type thermal fuse, a fusible alloy with a predetermined melting point is used for the fuse element, and a flux is applied to the fuse element, which is attached in thermal contact with the electronic / electrical equipment, causing abnormalities in the electronic / electrical equipment. The fuse element is melted by heat generation based on this, and the molten alloy is spheroidized by surface tension in the coexistence with the molten flux, and the molten severed alloy is solidified by the temperature drop of the equipment due to the current interruption due to the spheroidized severance and energized. It tries to complete the shut-off.

In recent years, lead-free products have been promoted for electronic and electrical equipment. That is, if lead is contained in the electronic / electrical equipment, lead is eluted from the waste and adversely affects the living system. For example, lead-free solder is being promoted.
Lead-free is also being promoted in the fuse elements of alloy-type thermal fuses.
The operating temperature of alloy-type thermal fuses that have been widely used belongs to 120 ° C to 150 ° C.
Conventionally, it has been proposed to use an In—Sn alloy as a lead-free fuse element of an alloy-type thermal fuse having an operating temperature of 120 ° C. to 150 ° C. (for example, Patent Document 1, Patent Document 2, and Patent Document 3). .

JP 11-25829 A JP 2002-25402 A JP 2003-13167 A

  FIG. 1 shows a temperature state diagram of an In—Sn alloy. In the range of In 85% to 52% (Sn 15 to 48%), the solidus temperature is in the range of about 120 ° C. to 150 ° C., and the β phase of the solid solution The solid-liquid coexistence width between the liquid and the melt L phase is extremely narrow, 3 ° C. to 4 ° C., and the variation in the operating temperature can be expected to be narrow.

However, according to the results of earnest study by the present inventors regarding an alloy-type thermal fuse using an In—Sn alloy as a fuse element, unexpectedly, if a direct current is applied for a long time, a problem caused by a long-term direct current application, for example, a fuse It has been found that the fuse element shears at a temperature below the melting point of the element. This phenomenon does not occur with AC energization, and it has been confirmed that this phenomenon is unique to DC.
As an example of this long-term DC current energization break, a cylindrical thermal fuse (50 pieces) with a wire element of diameter 500 μmφ obtained by drawing an In-Sn alloy of In74% and Sn26% is used as the operating temperature. When a DC 5A was energized for 3000 hours in a constant temperature bath lower by 35 ° C., almost 50% of the sample was sheared and destroyed in the middle of the fuse element, although the fuse element was in a solid solution state below the melting point.
On the other hand, no abnormality was recognized when the alternating current (crest value √2 × 5 A) having an effective value equal to the direct current value was applied for 3000 hours.

In FIG. 1, a phase transformation from (γ + β) mixed phase to β phase occurs along the curve ab in the range of In 85 to 52%, but destruction occurs at a temperature rise from room temperature to 100 ° C. before direct current application. It is clear that the long-time DC energization breakage is not based on this phase transformation.
When a conductor is energized, a circumferential magnetic field is generated, and a force that attracts current to the center of the conductor acts between the circumferential magnetic field and the conductor current. As a cause of long-term DC energization breakage of the fuse element, although it is not an estimated area, a center direction compressive force acts by the electromagnetic action over the entire length of the fuse element for DC energization, and as a result, axial compression based on the Poisson's ratio It can be assumed that stress acts and the soft In—Sn alloy fuse element due to In contained in a large amount undergoes shear failure on the surface where shear stress is generated based on the axial compressive stress.
Even if this shear fracture occurs in direct current, it does not occur in alternating current. In alternating current, if the angular frequency is ω, the shear stress on the slope becomes an alternating force with a frequency of 2ω, and the alternating stress becomes zero. While the strain between crystals is recovered in the meantime, the frequency is zero in direct current, the strain between crystals is accumulated, and a fracture mechanism that eventually leads to shear fracture can be imagined.

The thermo protector is used for circuit protection in the case of abnormal heat generation of the FET in the protection circuit of the battery pack, overheating protection of transistors, coils, transformers, etc. in the AC adapter. The operating temperature of the thermo protector required in this case is 120 ° C to 150 ° C.
However, an alloy-type thermal fuse using an In-Sn alloy as a fuse element is not suitable for the above-mentioned malfunction due to long-term DC energization, for example, long-term DC energization breakdown despite satisfying the operating temperature condition of the protector. It is difficult to use as a thermo protector.

  On the other hand, the variation in operating temperature is narrow in the range of In85 to 52%, the range of In85 to 52% has moderate ductility, can eliminate disconnection during wire drawing, and can guarantee a good yield. It is extremely useful as a thermo protector for AC electronic / electric equipment. AC electronic / electrical equipment refers to the one in which an alternating current flows through an alloy-type thermal fuse that protects it. Similarly, DC electronic / electrical equipment refers to an alloy-type thermal fuse that protects it. This means that a direct current flows.

  The object of the present invention is that the In-Sn alloy of In85 to 52% can eliminate the variation of the operating temperature well, and can obtain the advantage of ensuring a good yield due to moderate ductility. Considering the fact that there is a fatal defect for direct current such as long-term direct current failure, such as long-term direct current failure, when using an alloy-type thermal fuse whose fuse element is an In-Sn alloy under direct current The purpose is to impose long-term DC current stability, which is an overload condition than in use, and to rationally use the alloy-type thermal fuse.

The method of using the alloy-type thermal fuse according to claim 1 is that the fuse element is made of an In—Sn alloy having (In% + Sn%)> 93.4% and In%> 48.5%. ℃ AC dedicated alloy type thermal fuse protects AC electronic and electrical equipment from overheating, protects DC electronic and electrical equipment against overheating at the same temperature, fuse element alloy composition with that of the above-mentioned AC dedicated alloy type thermal fuse It is characterized by using an alloy type thermal fuse for direct current with different alloying elements.
The method of using an alloy type thermal fuse according to claim 2 is the method of using the alloy type thermal fuse according to claim 1, wherein the alloy composition of the fuse element of the AC-dedicated alloy type thermal fuse is 52% ≦ In ≦ 85%, and the balance It is characterized by the composition of Sn.
The method of using the alloy type thermal fuse according to claim 3 is the method of using the alloy type thermal fuse according to claim 1, wherein the alloy composition of the fuse element of the AC-dedicated alloy type thermal fuse is 52% ≦ In ≦ 85%, and the balance The composition is characterized by adding 0.01 to 7 parts by weight of at least one of Ag, Au, Ni, Pd, Pt, and Sb to 100 parts by weight of Sn.
The method of using an alloy type thermal fuse according to claim 4 is the method of using the alloy type thermal fuse according to claim 2 or 3, wherein the alloy composition of the fuse element of the direct current alloy type thermal fuse is 20% ≦ Bi ≦ 56. 5%, 43% <Sn ≦ 70%, 0.5% ≦ In ≦ 10%, or 20% ≦ Bi ≦ 56.5%, 43% <Sn ≦ 70%, 0.5% ≦ In ≦ 10% The composition is characterized by adding 0.01 to 7 parts by weight of at least one of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, and P to 100 parts by weight.
The method of using the alloy type thermal fuse according to claim 5 is that the fuse element is made of an In—Sn alloy with (In% + Sn%)> 93.4% and In%> 48.5%. It is characterized in that an AC-dedicated alloy-type thermal fuse of ℃ is used for protection from overheating of only AC electronic / electrical equipment among AC / DC electronic / electrical equipment.
The method of using the alloy type thermal fuse according to claim 6 is the method of using the alloy type thermal fuse according to claim 5, wherein the alloy composition of the fuse element of the AC-dedicated alloy type thermal fuse is 52% ≦ In ≦ 85%, and the balance It is characterized by the composition of Sn.
The method of using an alloy type thermal fuse according to claim 7 is the method of using an alloy type thermal fuse according to claim 5, wherein the alloy composition of the fuse element of the AC-dedicated alloy type thermal fuse is 52% ≦ In ≦ 85%, and the balance The composition is characterized by adding 0.01 to 7 parts by weight of at least one of Ag, Au, Ni, Pd, Pt, and Sb to 100 parts by weight of Sn.
The method of using the alloy type thermal fuse according to claim 8 is the method of using the alloy type thermal fuse according to any one of claims 1 to 7, wherein a heating element for fusing the fuse element is attached to the alloy type thermal fuse. Features.

  In the method of using an alloy type thermal fuse according to any one of claims 1 to 8, the operating temperature of the AC alloy type thermal fuse and the DC alloy type thermal fuse is substantially the same [the operating temperature tolerance (± value) Including those having a coincidence point within the range, and those having a coincidence point in both within the range of the nominal operating temperature +0 and −7 ° C.).

  An alloy-type thermal fuse according to claim 9 is an AC-dedicated alloy-type thermal fuse made of an In-Sn alloy, wherein the fuse element is used in the method for using an alloy-type thermal fuse according to any one of claims 1-8. A dedicated or direct use prohibition instruction is displayed directly or indirectly. In this case, direct display can be performed by printing on the body of the alloy-type thermal fuse or the like, and indirect display can be performed by description in an instruction manual, specification, catalog, or the like.

  In-Sn alloys, especially alloy-type thermal fuses that use In85-52% (Sn15% -48%) In-Sn binary alloys as fuse elements break down due to their energization under long-term DC energization. In view of this, an alloy type thermal fuse having the In-Sn alloy as a fuse element is used exclusively for alternating current, or an alloy type thermal fuse having the In-Sn alloy as a fuse element is used exclusively for alternating current, and excellent Since an alloy type thermal fuse using a fuse element of another alloy composition with long-term direct current stability is used for direct current, an alloy type thermal fuse having an In-Sn alloy of In85 to 52% as a fuse element is safe. Can be used reasonably.

  In particular, an alloy-type thermal fuse is used as a thermo-protector in a secondary battery used as a power source for a notebook computer, a mobile phone, etc., for example, a lithium ion secondary battery, a lithium polymer secondary battery pack or an AC adapter. In this case, it is prohibited to use an alloy-type thermal fuse having the In-Sn alloy of In85 to 52% as a fuse element, and an alloy-type thermal fuse using a fuse element having a different alloy composition with excellent long-term DC current stability is used as a battery. By using it exclusively for thermo protectors for packs and AC adapters, it is possible to improve the reliability of thermal protection for notebook computers and mobile phones.

  Furthermore, since the solid-liquid coexistence width of In85-52% In-Sn alloy is narrow and has an appropriate ductility, an alloy type thermal fuse using the alloy as a fuse element has a small variation in operating temperature. It has the advantage that it can be drawn and drawn with a good yield, and the advantage can be enjoyed by using the alloy type thermal fuse exclusively for AC.

FIG. 1 shows a temperature state diagram of an In—Sn alloy of a fuse element of an alloy type thermal fuse used in the present invention, and a range of In85 to 52% is used.
In this range, the β solid solution → the coexisting phase of the β solid solution and the solution L → the solution L melts by phase change, and the fuse element is spherically divided in the coexisting region. In other words, when the temperature of the fuse element exceeds the solidus temperature, the coexisting phase is divided into a lead conductor and an electrode of the alloy-type thermal fuse by spreading and spheroidizing due to surface tension due to a synergistic effect with the active action of the molten flux. . Therefore, the operating temperature of the alloy-type thermal fuse is a temperature between the solidus temperature and the liquidus temperature, but the temperature range between them is as narrow as about 3 ° C., and the variation in operating temperature can be minimized.
The operating temperature of a frequently used alloy type thermal fuse is 120 ° C. to 150 ° C., but the range of In 85 to 52% of the In—Sn alloy satisfies this operating temperature.

The fuse element can be manufactured through a raw material blending process, a billet manufacturing process, and a wire drawing process. First, Sn and In ingots are weighed so as to have a predetermined composition, put into a melting furnace, a molten alloy is poured into a mold to produce a billet, and this billet is formed into a rough wire by an extruder. A rough wire is drawn through a die to obtain a wire having a predetermined diameter, and the wire is cut into a predetermined length to obtain a fuse element.
In In alone, ductility is too large and drawing is difficult, but In85-52% In—Sn alloy has a good yield due to moderate ductility, and it is easy to draw to fine wires of 500 μmφ or less. .

Conventionally, alloy-type thermal fuses of the same alloy are used without distinction for both AC and DC. As an example of the rating, rated AC3.5A × AC50V and DC3.5A × at an operating temperature of 126 ± 2 ° C. And rated AC3A × AC50V and DC3A × DC50V at an operating temperature of 130 ± 2 ° C., rated AC4A × AC50V and DC4A × DC50V at an operating temperature of 145 ± 2 ° C., and the like.
However, it has already been described that an alloy type thermal fuse having an In85 to 52% In—Sn alloy as a fuse element has a problem in such dual use due to a failure due to a long-term DC current supply, for example, a long-term DC current breakdown. Street.

が成立するから（ｄはヒューズエレメントの外径）、 As described above, the cause of the long-term DC energization breakdown can be inferred from the breakdown due to the electromagnetic force.
That is, if the current density of the fuse element is i, the magnetic field H at the location of radius r is given by H = ir / 2, and if the radial compressive force at that location is f,

(D is the outer diameter of the fuse element),

f = [(d / 2) ³ −r ³ ] i ² / (6r)
It is assumed that the compression force f increases toward the center of the fuse element, and the fuse element creeps due to its softness.

  The long-term direct current failure of the In-Sn alloy fuse element of In85 to 52% is a phenomenon inherent to direct current, and does not occur in alternating current as described above. In fact, when an AC current having the same effective value as that of the DC current in which the long-term DC energization breakdown occurred was energized, no breakage was observed even after a time significantly exceeding the time in which the long-term DC energization breakdown occurred.

The long-term direct current energization failure of the fuse element of In85 to 52% In—Sn alloy is due to the fact that this alloy composition easily causes stress deformation. Therefore, under a heat cycle in which a large change in thermal stress occurs, a change in cross-sectional area or a change in length occurs due to a repeated stress change, and the resistance value tends to increase. Under such an increase in resistance value, if the temperature of the fuse element is raised by Joule heat generation and the rise temperature is ΔT, the temperature is lowered by the rise temperature ΔT before the alloy type temperature fuse temperature reaches the equipment allowable temperature. Therefore, if the temperature rise ΔT is increased, a serious operation error is caused.
Therefore, it is effective to add 0.01 to 7 parts by weight of at least one of Ag, Au, Ni, Pd, Pt, and Sb to 100 parts by weight of 52% ≦ In ≦ 85% of the In—Sn alloy and the remaining Sn. It is. The reason for adding at least 0.01 part by weight of at least one of Ag, Au, Ni, Pd, Pt, and Sb is that between at least one of Ag, Au, Ni, Pd, Pt, and Sb and In or Sn. This is to produce a compound, to prevent slip between crystals due to the wedge effect by the intermetallic compound, to suppress the deformation of the fuse element under the heat cycle and reduce the resistance value change, 7 parts by weight or less The reason is that the increase in the liquidus temperature and the increase in the solid-liquid coexistence temperature range become too large, and it becomes difficult to narrow the variation of the operating temperature under the operating temperature of 120 ° C to 150 ° C. is there.

  In the present invention, 52% ≦ In ≦ 85% of the In—Sn alloy, the remaining Sn or 100 parts by weight of this composition is 0.01 to 7 parts by weight of at least one of Ag, Au, Ni, Pd, Pt, and Sb. An alloy type thermal fuse using the added alloy fuse element is prohibited from being used in direct current, and can be implemented in a form for exclusive use in alternating current.

Further, 52% ≦ In ≦ 85% of In—Sn based alloy, remaining Sn or an alloy obtained by adding 0.01 to 7 parts by weight of at least one of Ag, Au, Ni, Pd, Pt, and Sb to 100 parts by weight of this composition. Alloy-type thermal fuse using a fuse element with an alloy composition that can be used exclusively for alternating current and for the long-term direct current energization, for example, long-term direct current breakdown can be well eliminated. Can also be implemented in a form in which is used for direct current. As an evaluation standard for this long-term DC energization breakdown, it is possible to take a pass of 5 A DC at an operating temperature of −35 ° C. and an energization time of 3000 hours.
Alloys satisfying such conditions include 20% ≦ Bi ≦ 56.5%, 43% <Sn ≦ 70%, 0.5% ≦ In ≦ 10%, or 20% ≦ Bi ≦ 56.5%, 43%. <Sn ≦ 70%, 0.5% ≦ In ≦ 10% by weight of 0.01 to 7 parts by weight of at least one of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, P Added compositions can be used.
In this alloy composition, the Sn amount (43% <Sn ≦ 70%) and the Bi amount (20% ≦ Bi ≦ 56.5%) provide ductility that enables drawing, and these and the In amount (0. 5% ≦ In ≦ 10%), the melting point is set to include the range of 120 ° C. to 150 ° C. When In is mixed in the Bi phase (α phase) and Sn phase (γ phase), which are hardly dissolved in Sn or In, a hard and brittle α phase and an Sn-In intermetallic compound phase precipitate and the interphase Since the mechanical property difference becomes large and the workability becomes poor, and the drawing process becomes more difficult as the In content increases, the In content is suppressed to 10% or less.
The reason for adding 0.01 to 7 parts by weight of at least one of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, and P is to reduce the specific resistance of the alloy and refine the crystal structure. This is to reduce the strain interface and stress distribution by reducing the interface between the different phases. If it is less than 0.01 part by weight, it is difficult to obtain the effect. If it exceeds 7 parts by weight, the operating temperature of the alloy-type thermal fuse is 120 ° C. It becomes difficult to set within the range of -150 degreeC.
In the present invention, the fuse element can be used with a round cross-section after drawing or further compressed into a flat shape. The diameter of the fuse element is 200 μmφ to 1050 μm outer diameter in the case of a circular wire. The

  The present invention is implemented in the form of a thermal fuse shown in FIGS. In addition, a thermal fuse element is connected in series to a semiconductor device, a capacitor, or a resistor, and a flux is applied to the element, and the flux application element is disposed close to the semiconductor, the capacitor element, or the resistance element, and the semiconductor, capacitor element, It can also be implemented in a form sealed together with a resistor element by a resin mold or a case.

  FIG. 2 shows an alloy type temperature fuse of a cylindrical case type. A low melting point soluble alloy piece 2 is connected between a pair of lead wires 1 and 1, and the low melting point soluble alloy piece 2 is placed on the low melting point soluble alloy piece 2. A flux 3 is applied, and a heat-resistant and heat-conductive insulating cylinder 4, for example, a ceramic cylinder, is inserted over the flux-applied low melting point soluble alloy piece, and each end of the insulating cylinder 4 and each lead wire 1 are inserted. Is sealed with a normal temperature curing sealant 5, for example, an epoxy resin.

  FIG. 3 shows a tape-type alloy-type temperature fuse, and a strip-shaped lead conductor 1, 1 having a thickness of 100 to 200 μm is fixed to a plastic base film 41 having a thickness of 100 to 300 μm by an adhesive or fusion. Then, a fuse element 2 having a wire diameter of 250 μmφ to 500 μmφ is connected between the strip-shaped lead conductors, and a flux 3 is applied to the fuse element 2, and the flux application fuse element is formed to a thickness of 100 to 300 μm. The plastic cover film 41 is sealed by fixing with an adhesive or fusion.

  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 agent 5 such as an epoxy resin.

  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 between the electrodes 1 and 1 by welding, the flux 3 is applied to the fuse element 2, and the flux application fuse element is connected to the sealant 5. For example, it is coated with an epoxy resin.

  FIG. 6 shows a resin dipping 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 flux application fuse element is sealed with an insulating sealant such as epoxy resin 5 by resin liquid dipping.

  In the present invention, a heating element is attached to an alloy-type thermal fuse, and a film resistance is attached by, for example, applying and baking a resistance paste (for example, a paste of metal oxide powder such as ruthenium oxide). A circuit current is passed through the fuse element as a path, the membrane resistance is not part of the circuit, the circuit current is not passed, and the membrane resistance is energized with this detection signal when a precursor causing abnormal heat generation of the device is detected It can also be implemented in a form in which heat is generated and the fuse element is melted by this heat to cut off the circuit current. In this case, since a circuit current is normally passed through the fuse element, in the case of direct current, the above-described problems caused by long-term direct current energization, such as long-term direct current energization breakdown, become a problem, so the In-Sn alloy fuse element is used. The use of the thermal fuse with a heating element is prohibited, and the thermal fuse with a heating element used in the Bi-Sn-In alloy fuse element is used.

  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. Organic acids such as salts and adipic acid can be used.

In the following examples and comparative examples, a flux in which a lead conductor is connected to both ends of a fuse element having a diameter of 600 μmφ and a length of 3.5 mm and 1% by weight of adipic acid is added as a main component is rosin. Is applied to the fuse element, and a ceramic cylinder having an outer diameter of 2.5 mmφ, a thickness of 0.5 mm, and a length of 9 mm is inserted into the flux-applied fuse element, and a room temperature curing type is provided between each end of the ceramic cylinder and each lead conductor. A cylindrical thermal fuse shown in FIG. 2 sealed with an epoxy resin was used.
The operating temperature of the alloy-type thermal fuse is 50 samples, immersed in an oil bath at a heating rate of 1 ° C / min while energizing a current of 0.1 ampere, and the oil temperature when the energization is cut off by fusing It was measured.
For long-term DC energization aging evaluation, the number of samples was 50, placed in a thermostatic chamber lower by 35 ° C. than the operating temperature, and DC5A was energized for 3000 hours. A defect, for example, a line observation device was inspected, and a case where all the pieces were not broken was regarded as acceptable.
The operating temperature after the long-term DC energization aging test was immersed in an oil bath at a heating rate of 1 ° C./min while energizing a current of 0.1 ampere, and the oil temperature when the energization was interrupted by fusing was measured.
In order to confirm that this long-term DC energization breakdown is peculiar to DC, the number of samples was set to 50, placed in a thermostatic chamber at the same temperature as described above, and the AC current (wave) having the same effective value as DC5A A high value √2 × 5 A) was energized for 3000 hours, and after the energization, a test (long-term energization aging test) was conducted to inspect whether the fuse element was broken by soft long-term DC energization, for example, with a wire device.
In drawing the fuse element, the drawing rate per die was set to 6.5%, the drawing speed was set to 45 m / min, and drawing was performed to a diameter of 300 μmφ.

Cylindrical thermal fuses using Bi-Sn-In alloys with Bi50%, Sn45%, and In5% as fuse elements, using cylindrical thermal fuses with In74% and Sn26% In-Sn alloys as fuse elements Was used for direct current.
The operating temperature was 129.2 ± 1 ° C. for the former and 129.7 ± 1 ° C. for the latter, which was substantially the same operating temperature.
For AC use, there were 28 out of 50 fuse elements that broke in the long-term DC energization aging test, and the evaluation for long-term DC energization aging failed. None of the products were evaluated, and the evaluation for long-term direct current aging was acceptable.
When the operating temperature of 50 samples after the long-term direct current aging test was measured, no substantial change was observed compared to before the aging test, and the operating performance could be maintained stably.
Drawing of the DC fuse element was more difficult than AC, but none of them was disconnected.
In the long-term AC energization aging test, no fuse element was broken in both AC and DC.

  From this example, it is a phenomenon peculiar to direct current that an alloy-type thermal fuse having an In85-52% In—Sn binary alloy as a fuse element breaks due to the energization under long-term direct current energization. By using an alloy-type thermal fuse with a Sn-based alloy fuse element as a dedicated AC element, and using an alloy-type thermal fuse with a Bi-Sn-In alloy alloy fuse element as a direct current element, both for AC and DC use It is clear that electronic and electrical equipment can be safely and reasonably protected with an alloy-type thermal fuse having an operating temperature of 120 to 150 ° C.

[Comparative example]
A cylindrical temperature fuse using In-Sn alloy of In74% and Sn26% as a fuse element was used for both AC and DC as usual.
In this comparative example, it can be predicted that a DC energization breakage will occur during long-term use for DC, and the DC electronic / electrical device cannot be safely protected.

It is a temperature state figure of an In-Sn alloy. It is drawing which shows an example of the alloy type temperature fuse used in this invention. It is drawing which shows an example different from the above of the alloy type temperature fuse used in this invention. It is drawing which shows an example different from the above of the alloy type temperature fuse used in this invention. It is drawing which shows an example different from the above of the alloy type temperature fuse used in this invention. It is drawing which shows an example different from the above of the alloy type temperature fuse used in this invention.

Explanation of symbols

1 Lead conductor or electrode 2 Fuse element 3 Flux 4 Insulator 5 Sealing material

Claims (9)

An AC-only alloy type thermal fuse with an operating temperature of 120 to 150 ° C. in which the fuse element is made of an In—Sn alloy with (In% + Sn%)> 93.4% and In%> 48.5%. Is protected from overheating, and direct current electronic equipment is protected against overheating at the same temperature by using an alloy type thermal fuse for direct current in which the alloy composition of the fuse element is different from that of the above-mentioned dedicated alloy type thermal fuse. A method of using an alloy-type thermal fuse characterized by the above. 2. The method of using an alloy type thermal fuse according to claim 1, wherein the alloy composition of the fuse element of the AC-only alloy type thermal fuse is 52% ≦ In ≦ 85% and the remaining Sn composition. The alloy composition of the fuse element of the AC-dedicated alloy type thermal fuse is 52% ≦ In ≦ 85%, and the remaining Sn is 100 to 10 parts by weight. At least one of Ag, Au, Ni, Pd, Pt, and Sb is 0.01 to 7 parts by weight. The method of using an alloy type thermal fuse according to claim 1, wherein the composition is an added composition. The alloy composition of the fuse element of the direct current alloy type thermal fuse is 20% ≦ Bi ≦ 56.5%, 43% <Sn ≦ 70%, 0.5% ≦ In ≦ 10%, or 20% ≦ Bi ≦ 56.5. %, 43% <Sn ≦ 70%, 0.5% ≦ In ≦ 10%, 100 parts by weight of at least one of Ag, Au, Cu, Ni, Pd, Pt, Sb, Ga, Ge, and P is 0.01 The method of using an alloy type thermal fuse according to claim 2 or 3, wherein the composition is added with -7 parts by weight. The fuse element is made of an In-Sn alloy with (In% + Sn%)> 93.4% and In%> 48.5%. A method of using an alloy-type thermal fuse, characterized in that it is used for protection from overheating of only AC electronics and electrical equipment among electrical equipment. 6. The method of using an alloy type thermal fuse according to claim 5, wherein the alloy composition of the fuse element of the AC-only alloy type thermal fuse is 52% ≦ In ≦ 85% and the remaining Sn composition. The alloy composition of the fuse element of the AC-dedicated alloy type thermal fuse is 52% ≦ In ≦ 85%, and the remaining Sn is 100 to 10 parts by weight. At least one of Ag, Au, Ni, Pd, Pt, and Sb is 0.01 to 7 parts by weight. 6. The method of using an alloy type thermal fuse according to claim 5, wherein the composition is an added composition. The method of using an alloy type thermal fuse according to any one of claims 1 to 7, wherein a heating element for fusing the fuse element is attached to the alloy type thermal fuse. The fuse element used in the method for using an alloy-type thermal fuse according to any one of claims 1 to 8, wherein the fuse element is an In-Sn alloy alloy-only alloy-type temperature fuse, and direct or direct use is prohibited. An alloy type thermal fuse characterized by being indirectly displayed.

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