JP4152706B2 - Alloy-type thermal fuse, article with built-in alloy-type thermal fuse, and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an alloy-type thermal fuse, an article with a built-in alloy-type thermal fuse, and a manufacturing method thereof.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in order to prevent abnormal heat generation and fire from occurring in an electrical appliance such as a plug, it is known to insert a thermo protector in series and embed it in a resin sheath of the plug.
Conventionally, as a thermo protector, a return type such as a thermostat or a thermistor and a non-reset type such as an alloy type thermal fuse are known.
In the thermo protector built-in plug, since the resin outer package is formed by injection molding, a return type is used for the thermo protector. The reason for this is that the plug with a built-in thermo protector uses a thermo protector that operates at a temperature lower than the melting and softening temperature of the resin sheathing body. It is necessary to prevent the temperature from rising, and an alloy type thermal fuse having such an operating temperature inevitably operates in a non-return state at the injection molding temperature of the resin sheathing body, and a resettable thermo protector must be used. It is because it does not get.
[0003]
In a conventional alloy-type thermal fuse, a flux is added to the surface of a soluble alloy piece having a melting point that regulates the operating temperature, and the flux-added soluble alloy piece is bonded with a room temperature curable resin mold or an insulator case and an adhesive. Airtightly sealed.
The operating mechanism of this alloy-type thermal fuse is that the soluble alloy piece is melted due to an increase in the external temperature, and this molten alloy is separated by being pulled by the lead conductor or electrode due to the interface energy in the coexistence with the already melted flux. (Divided by so-called spheroidization), and the spheroidization progresses to increase the dividing distance and complete the current interruption.
Thus, the alloy-type thermal fuse operates when the substantially fusible alloy piece reaches the melting point of the fusible alloy.
[0004]
Thus, if the addition of flux is eliminated, the fusible alloy piece does not operate even when the temperature of the alloy piece reaches the melting point of the alloy, and the dividing temperature is considerably higher than the melting point of the alloy. The reason is that the fusible alloy is easily oxidizable, and an oxide film is inevitably formed on the surface of the fusible alloy. This oxide film has a high melting point and high hardness, and the fusible alloy inside the film melts. However, the oxide film serves as a sheath to prevent the fragmentation of the alloy pieces, and the unsevered state is maintained until the sheath strength of the film is reduced by further heating and the inner molten alloy cannot be retained.
The present invention makes it possible to embed an alloy type thermal fuse in an injection molded resin exterior body of an electric appliance such as a plug using the unique fact of the alloy type thermal fuse.
[0005]
The object of the present invention is to provide an alloy-type thermal fuse or an alloy-type thermal fuse-containing article including a process having a temperature higher than the melting point of the alloy of the fusible alloy as the fuse element. The object is to safely manufacture a mold temperature fuse or an alloy type temperature fuse-containing article with a good yield.
[0006]
A more specific object of the present invention is to provide a resin injection molding process having a molding temperature higher than the melting point of an alloy of a fusible alloy as a fuse element during the manufacturing process of an alloy type thermal fuse or an article with a built-in alloy type thermal fuse. Even if it is included, the object is to safely manufacture the alloy-type temperature fuse or the alloy-type temperature fuse-containing article with a good yield.
[Means for Solving the Problems]
[0007]
The method of manufacturing an alloy type thermal fuse according to claim 1 of the present application is such that a flux is added to the outer surface of an easily oxidizable soluble alloy piece, and the flux added soluble alloy piece is covered with an insulator. Or a method of manufacturing an article with a built-in alloy type thermal fuse, in which an insulator is formed by coating with an insulating material in a state where no flux is added to the fusible alloy piece, and at the time of this formation, a flux is injected into the insulator A mouth is formed, and flux is injected from the inlet later than that to add flux to the soluble alloy piece.
[0008]
The method of manufacturing an alloy-type thermal fuse according to claim 2 of the present application includes an alloy-type thermal fuse in which a flux is added to the outer surface of an easily oxidizable soluble alloy piece and the flux-added soluble alloy piece is covered with an insulator. Or a method of manufacturing an article with a built-in alloy type thermal fuse, in which an insulator is formed by coating under heating with an insulating material without adding flux to the fusible alloy piece, and after forming the insulator, forming a flux injection port, characterized by adding a flux to the from the inlet by injecting fluxes fusible alloy piece later than this.
[0109]
According to a sixth aspect of the present invention , the coating under heating with the insulating material is performed by injection molding of a thermoplastic resin, and the flux injection port is formed by a protrusion on the inner surface of the mold.
[0010]
According to the seventh aspect of the present invention , the flux injection port is closed after the flux injection by either mounting of resin rivets, filling with an adhesive, or crushing and sealing.
[0011]
According to the eighth aspect of the invention , the fusible alloy piece is covered with an insulating material while being covered with the inner cover.
[0012]
The ninth aspect is an alloy type thermal fuse manufactured by the manufacturing method according to the present invention.
[0013]
Claim 10 is an alloy type thermal fuse built-in article manufactured by the manufacturing method according to the present invention, for example, a plug, in which a flux-added soluble alloy piece is connected in series on one blade side of the plug, and the heat of the plug It is embedded in the plastic resin outer package.
In the method for manufacturing an alloy type thermal fuse according to claim 11, the fusible alloy pieces connected between the lead conductors and the lead conductor portions in the vicinity of both ends thereof are sandwiched from above and below with a thermoplastic resin film, and the periphery between the films is unified. In the subsequent process, the flux is injected using the unfused portion as a flux injection port. After that, the unfused portion is crushed by ultrasonic fusion, dielectric heating fusion, or the like. It is characterized by closing with sealing .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1A is a longitudinal sectional view showing an example of an alloy type thermal fuse manufactured according to the present invention, and FIG. 1B is a cross-sectional view of FIG.
In FIG. 1, 1 is a lead conductor, 2 is a fusible alloy piece connected by welding or the like between the lead conductors 1, 1, 3 is a flux added to the outer surface of the fusible alloy piece 2, 4 is a flux-added fusible element It is an insulating material covering the alloy piece and the lead wire portion in the vicinity of both ends thereof.
[0015]
In order to manufacture this alloy-type thermal fuse, it is necessary to go through a process of connecting a soluble alloy piece between lead conductors by welding, a process of adding a flux, a process of covering an insulating material, and the like.
In the method for manufacturing an alloy-type thermal fuse according to the present invention, during all the above steps, the flux is used in the whole process of one step or in a specific step where the soluble alloy piece is temporarily exposed to a temperature higher than its melting point. It is performed without adding, and flux is added after this step.
[0016]
According to claim 1 or 2 , the insulating material coating step performed under heating is the specific step described above, and the fusible alloy piece and the lead conductor portions near both ends thereof are heated with no flux added. An insulating material is formed by covering an insulating material, and flux is added in a later process. In this case, when the insulating material is coated without adding the flux, or immediately after the coating, for example, when the thermoplastic resin is injection-molded without adding the flux, or immediately after the injection molding, the soluble alloy piece and opening to the flux filling space in contact with the outer surface into the space formed in the insulator, after the step flux is injected into the flux filling space from the opening in, and closes the opening after the injection.
[0017]
As the above-mentioned fusible alloy piece, an alloy having a melting point corresponding to the required temperature fuse operating temperature is used. However, since it contains an easily oxidizable element, the formation of an oxide film on the surface of the fusible alloy piece can be avoided. Absent.
Thus, in the state where the flux (melting alloy melting point> flux melting point) is added to the outer surface of the fusible alloy piece, when the fusible alloy piece is heated to the melting point of the fusible alloy, the active power is increased. The oxide film on the surface of the soluble alloy piece is dissolved by the molten flux, and the oxide film does not act as a sheath for the molten alloy, and the soluble alloy piece is substantially divided at the melting point of the alloy. In a state where the molten alloy piece is not added, even if the fusible alloy piece is melted, the oxide film remains in the original sheath shape and holds the molten alloy, so that the molten alloy is prevented from being divided.
Therefore, according to claim 1 or 2, even if the insulating material coating temperature is high and the soluble alloy piece is melted at the time of coating, the shape of the soluble alloy piece can be maintained, and the insulating material covering temperature is Even if the melting point is higher than the melting point of the alloy, the insulating material can be safely coated.
[0018]
The insulating material can be coated by injection molding of a thermoplastic resin, casting of a thermosetting resin, squeeze fusion of a thermoplastic resin film, or the like.
That is, (1) When an insulating coating is applied by injection molding of a thermoplastic resin, a fusible alloy piece connected between lead conductors is set in a mold, and a thermoplastic resin coating having the above-described space for flux filling is provided. Injection molding is performed, and a flux injection port is formed in the coated body at the time of injection molding or immediately after the injection molding, and flux is injected from the flux injection port into the flux filling space in a later process. It can be implemented by plugging the mouth with a resin rivet, filling with an adhesive, local pressurization / heating by crushing and sealing such as ultrasonic fusion or dielectric heating fusion. In this case, as described later, the flux filling space is formed by a method of attaching an inner cover (usually made of a thermoplastic resin) to the fusible alloy piece, and providing a mold for forming the flux filling space in the mold. A method or the like can be used.
(2) When applying an insulating coating by casting a curable resin, a flux filling space holding inner cover (usually made of a thermoplastic resin) is attached to the soluble alloy piece connected between the lead conductors. Set the wearable alloy piece in the mold, inject a curable resin (epoxy resin, polyester resin, etc.) into the mold, and heat the mold to cure the resin. Immediately after curing, a flux injection port is formed in the insulator, and flux is injected into the flux filling space from the flux injection port in a later process, and then the flux injection port is inserted into the resin rivet, adhesive It can be carried out by closing the tube by filling it. In this case, instead of the method of mounting the inner cover, a method of providing a flux filling space forming core in a mold can be used for forming the flux filling space.
(3) When the insulation coating is applied with a thermoplastic resin film, the fusible alloy pieces connected between the lead conductors and the lead conductor parts near both ends thereof are sandwiched from above and below with the thermoplastic resin film, and the periphery between the films is surrounded. In a later process, the flux is injected using the unfused portion as a flux injection port. After that, the unfused portion is subjected to ultrasonic fusion, dielectric heating fusion, etc. It can be carried out by closing by crushing and sealing, and since the unfused portion is small, the amount of heat required for the fusion is small, and the fusible alloy pieces are not substantially thermally damaged. In this embodiment, the upper and lower films are bent at the contact point with the fusible alloy piece, and a space in contact with the outer surface of the fusible alloy piece is inevitably formed, and this space can be used as a flux filling space. Therefore, no special means for forming the flux filling space is required.
[0019]
In the present invention, as the fusible alloy piece, in addition to a wire rod by drawing or rolling, a wire rod by a rotating drum spinning method can be used. In the case of the former, a billet is manufactured and formed into a rough wire with an extruder, and this rough wire can be manufactured by drawing with a die. The outer diameter is 200 μmφ to 600 μmφ, preferably 250 μmφ to 350 μmφ, and finally It can also be passed through a calendar roll and used as a flat wire. In the latter case, the cylinder containing the cooling liquid is rotated and the cooling liquid is held in layers by a rotational centrifugal force, and the base material molten jet injected from the nozzle is incident on the cooling liquid layer to be cooled and solidified to have an outer diameter of 200 μmφ. It can be made to be a wire rod of ˜600 μmφ, and the thickness of the surface oxide film is thicker than that of the former, so that it is more advantageous for preventing the fusible alloy pieces from being separated at the time of the high temperature insulating coating.
[0020]
FIGS. 2A to 2F show an embodiment of a method for manufacturing an alloy-type thermal fuse according to the present invention, in which injection molding is used for covering an insulating material.
2A to 2F, reference numeral 1 denotes a lead conductor, and a flat conductor is used in the illustrated example. 2 is a fusible alloy piece and 4 is an insulator.
In order to manufacture an alloy-type thermal fuse according to this embodiment, as shown in FIG. 2 (a), the fusible alloy piece 2 connected between the lead conductors 1 and 1 and the lead conductor portions 10 and 10 near both ends thereof are provided. As shown in FIG. 2B, the inner cover 5 made of a thermoplastic resin and having a U-shaped cross section is mounted, and this cover-mounted soluble alloy piece or the like is set in the mold 6. As shown in FIG. 3A, inner flanges 51 are provided at both ends of the inner cover, and a space for flux filling is secured between the inner cover and the soluble alloy piece. The cover is not particularly limited as long as a space can be secured between the inner surface and the outer surface of the fusible alloy piece under stable mounting. For example, the lead conductor can be held at both ends. It can also be a boat shape as shown in (b).
As shown in FIG. 2C, a flux inlet molding protrusion 61 can be provided on the inner surface of the mold. Thus, if the insulator 4 is formed by injection molding of a thermoplastic resin, a flux injection port 41 can be formed in the insulator 4 as shown in FIG. In addition, since the volume of the insulator is small, it is possible to prevent the generation of bubbles well even under low pressure charge to the mold and holding pressure in the mold, and as a result, the charge pressure and holding pressure can be sufficiently reduced. The flux filling space in the inner cover can be stably held.
After the injection molding of the insulator in this manner, as shown in FIG. 2 (e), the nozzle 7 is inserted into the flux injection port, and the flux is injected into the flux filling space. As shown in 2 (f), the inlet for flux injection is closed by filling with adhesive or by ultrasonic fusion or dielectric heat fusion (used for resins with strong electrical polarity such as vinyl chloride resin). This completes the production of the alloy-type thermal fuse.
[0021]
In the above embodiment, to form a flux injection port at the time of injection molding of the insulator, it is also possible to perforate the flux injection port at Horuso like the injection molded insulator.
[0022]
In the above, it is preferable to use a thermoplastic resin of the same quality as the insulator for the inner cover.
[0023]
In the above embodiment, the flux filling space is secured by mounting the inner cover 5, but as shown in FIG. 2C, a soluble alloy piece is formed at the front end of the flux inlet molding protrusion 61. The inner cover 5 may be omitted by providing a core portion 62 with a storage groove.
[0024]
As is well known, in injection molding, molten resin discharged from each cylinder is charged at a predetermined pressure into the mold cavity through the sprue, runner and gate, and this charge resin is cooled and cured in the mold. While being done, it is kept at a predetermined pressure and released after curing. Thus, in the above embodiment, it is preferable to reduce the charge pressure and the holding pressure as much as possible in order to prevent the resin from being pressed into the inner cover.
[0025]
FIGS. 4A to 4C show an example of an operation relationship among the die plate operation, the nozzle operation, and the plunger operation in the injection molding (plunger type), and the basic structure of the injection molding will be described from this operation relationship. For example:
That is, the injection molding apparatus includes a plunger type injection unit and the mold, when the mold by the die plate movement is as shown in (b) of FIG. 4, a closed t ₁ hour time point to b, As shown in FIG. 4B, the nozzle at the tip of the injection machine and the sprue at the entrance of the mold begin to contact at time point c by the nozzle operation, complete the contact association at time point d, and complete for t ₂ hours. Contact association is sustained. Then, as shown in (c) of FIG. 4, full contact plunger completion point d Union is advanced startup, the molten resin into the mold is injected t ₃ hours from the injection machine, the plunger is retracted starting at e Is done. However, at this point, the mold is still closed and curing is performed for a time (t ₂ -t ₃ ). When the mold clamping time of the mold is Δt ₁ , the closing time is t ₁ , the mold opening time is Δt ₂ , and the product removal time is Δt ₃ , the cycle time t is given by (Δt ₁ + t ₁ + Δt ₂ + Δt ₃ ).
Therefore, in the present invention, it is necessary to set the fusible alloy piece connected between the lead conductors to the mold. When this set time is Δt, the cycle time is (t + Δt). If the inner cover is attached to the connected fusible alloy pieces in advance, the set-up time Δt can be shortened sufficiently for the reinforcing function of the inner cover and the set time Δt can be sufficiently shortened. the time and curing time can be sufficiently shortened can mold closing time t ₁ short or the like, it is possible to enhance the working efficiency to shorten the cycle time.
[0026]
In the present invention, the stronger the oxidizability of the fusible alloy piece, the thicker the surface oxide film and the stronger the sheath strength. This is advantageous for improving the distillation. However, as the oxide film of the fusible alloy piece becomes thicker, the operability (operation delay) of the alloy-type thermal fuse decreases accordingly, so it is preferable to add an activator to the flux.
[0027]
A fusible alloy having a predetermined melting point is used as the fusible alloy, and the melting point is selected according to the operating temperature. The alloy element is usually selected from Pb, Sn, Bi, In, Sb, etc., and one or more of Cu, Ag, Au, and Al are adjusted to a total of 0. It is added in the range of 1 to 5%.
[0028]
As the flux, one having a melting point lower than that of the soluble alloy 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 can be used. . 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.
[0029]
In the alloy type thermal fuse, when the external temperature reaches a predetermined temperature Tx, the temperature of the fusible alloy piece becomes approximately the melting point Tm, and the energization is cut off. Therefore, the external temperature is prevented from exceeding Tx. Therefore, there is a difference between the outer surface temperature of the alloy-type thermal fuse, that is, the external temperature Tx and the soluble alloy piece temperature due to the thermal resistance between them, and if the difference is ΔT, the soluble alloy For the piece, an alloy having a melting point Tm of (Tx−ΔT) is used. In this alloy type thermal fuse, the flux-added soluble alloy piece is covered with an insulating material, and this insulator is heated to the external temperature Tx when the fuse is operated. It is necessary to impart heat resistance, and the insulating material melting point Tn must be equal to or higher than the temperature Tx. Therefore, in order to apply this insulating material coating by injection molding or heat fusion of a thermoplastic resin film, it is necessary to melt the insulating material, and melt coating with a flux added to a soluble alloy piece When the material (the temperature is equal to or higher than the melting point Tn) is brought into contact, the possibility that the soluble alloy piece is heated to the coating material temperature is high. As described above, the melting point Tn of the insulating material, the melting point Tm of the soluble alloy piece, and the predetermined value. As long as there is a relationship of Tn> Tx and Tm = Tx−ΔT between the temperature Tx and the temperature Tx, there is a high probability that the fusible alloy piece will be blown out, and the insulating material cannot be covered safely with a good yield. However, in the present invention, the coating material is coated in a state where no flux is added to the soluble alloy piece, and the flux is added in the subsequent process. Can be covered with an insulating material.
[0030]
Alloy-type thermal fuses are used to protect equipment. Thus, the melting point Tm of the fusible alloy of the alloy-type thermal fuse is set to be approximately equal to the allowable temperature Tx of the device (Tm = Tx−ΔT), and the melting point of the insulating coating material is set to the temperature Tx or higher. For example, if the allowable temperature of the device is 150 ° C., an alloy having a melting point of 148 ° C. can be used for the fusible alloy piece, and a vinyl chloride resin can be used for the insulating coating material. The injection temperature is approximately 170 ° C., and at the time of injection molding, the soluble alloy piece with no added flux is heated for several seconds under this 170 ° C., but the soluble alloy piece is blown out. There is no such thing.
[0031]
The method for manufacturing an alloy-type thermal fuse according to the present invention is suitable for manufacturing an alloy-type thermal fuse-containing article in which an alloy-type thermal fuse is embedded in a resin sheath, for example, a power plug or a table tap with a built-in alloy-type thermal fuse. Applicable. Here, the article with a built-in alloy type thermal fuse means that a flux-added soluble alloy piece is embedded in a resin sheath provided by injection molding, and the soluble alloy piece is connected in series to the internal circuit member of the article. Even if heat is generated by an electric current, the heat generated by energization is interrupted before the soft deformation of the resin sheathing body.
[0032]
5 (a) to 5 (f) show an embodiment of a method for producing an alloy-type thermal fuse-containing article according to the present invention.
In order to manufacture a power supply plug with a built-in alloy type thermal fuse according to this embodiment, first, as shown in FIG. 5 (a), the end of the two-core flat wire is branched and one core wire conductor 71 has one blade. 82 is connected by a compression terminal 91, an auxiliary conductor 72 'is connected to the other core wire conductor 71' by a compression fitting 91 ', and a soluble alloy piece is provided between the auxiliary conductor 72' and the other blade 82 '. 2 is connected. Further, as shown in FIG. 5B, the inner cover 5 is attached to the fusible alloy piece 2, and further, as shown in FIG. 5C, the flat outer package 40 is formed by injection molding of a thermoplastic resin. And a flux injection port 41 communicating with the flux filling space in the inner cover 5 is formed, and the nozzle 7 is inserted into the flux injection port 41 as shown in FIG. Flux is injected into the flux filling space in the cover 5, and then a thermoplastic resin rivet 43 is attached to the flux injection port 41 as shown in FIG. As shown in (f) of FIG. 5, the gap is integrated by ultrasonic fusion or the like, and the manufacture of the power plug with a built-in alloy type thermal fuse is completed.
In an alloy type thermal fuse built-in article, for example, an alloy type thermal fuse built-in power supply plug, it is necessary to set the operating temperature of the alloy type thermal fuse according to the heat resistance of the resin outer package. Thus, assuming that the melting point of the outer package is Ti and the operating temperature of the thermal fuse is Tx, even if heat is generated by overcurrent as Tx <Ti, the thermal fuse is operated before the resin outer package is thermally softened and deformed. It is necessary to stop energization heat generation. Thus, in order to coat such a resin sheathing body by injection molding, it is necessary to melt the resin, the molten resin temperature exceeds Ti, and the molten resin is in a state where flux is added to the soluble alloy piece. When the contact is made (the temperature is equal to or higher than the melting point Ti), it is highly probable that the soluble alloy piece is heated to the molten resin temperature. As described above, between the temperature fuse operating temperature Tx and the resin melting point Ti, Ti> Tx Therefore, it is highly probable that the fusible alloy piece is melted, and the resin outer package cannot be injection-molded safely and with a high yield. However, in the present invention, the resin outer package is injection-molded without adding flux to the fusible alloy piece, and the flux is added in a later process, so that the fusible alloy piece is prevented from being melted and is safe and good. Resin sheathing can be injection molded with yield. For example, when the resin outer package is a vinyl chloride resin, the melting point of the fusible alloy piece can be set to 150 ° C. In this case, the injection temperature of the vinyl chloride resin is approximately 170 ° C. The soluble alloy piece not added is heated at 170 ° C. for several seconds, but the soluble alloy piece is not blown out.
[0033]
In any of the above embodiments, the lead conductor surface to be coated with the insulating material is previously coated with the same material as the insulating material (for example, a resin layer), thereby improving the familiarity with the insulating material, It is possible to increase the airtightness around the lead conductor.
[0034]
【The invention's effect】
According to the present invention, in the manufacture of an alloy-type thermal fuse or an article with a built-in alloy-type thermal fuse, an insulating material having a melting point higher than that of a fusible alloy can be obtained without fusing the fusible alloy with the insulating material coating or the outer body coating. It can be safely applied with good yield by injection molding or resin film fusion.
In particular, since the insulating material can be coated by injection molding, the manufacturing time can be shortened and the dimensional accuracy can be improved.
[Brief description of the drawings]
FIG. 1 is a view showing an example of an alloy-type thermal fuse manufactured according to the present invention.
FIG. 2 is a drawing showing an embodiment of a method for manufacturing an alloy-type thermal fuse according to the present invention.
FIG. 3 is a drawing showing different examples of the inner cover used in the present invention.
FIG. 4 is a drawing showing the operation of injection molding used in the method for manufacturing an alloy-type thermal fuse according to the present invention.
FIG. 5 is a drawing showing an embodiment of a method of manufacturing an article with a built-in alloy type thermal fuse according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Lead conductor 2 Soluble alloy piece 3 Flux 4 Insulator 40 Resin exterior body 41 Flux injection port 43 Thermoplastic resin rivet 5 Inner cover 6 Mold 61 Flux injection molding protrusion 62 Flux filling space holding core 7 Nozzle for flux injection 82 blade 82 'blade

Claims (11)

A method of manufacturing an alloy-type thermal fuse or an article with a built-in alloy-type thermal fuse, in which a flux is added to the outer surface of an easily oxidizable soluble alloy piece, and the flux-added soluble alloy piece is covered with an insulator. An insulator is formed by coating under heating with an insulating material without adding flux to the molten alloy piece, and a flux injection port is formed in the insulator at the time of formation, and the flux is supplied from the injection port later than this. A method for producing an alloy-type thermal fuse, which comprises injecting and adding flux to a fusible alloy piece. A method of manufacturing an alloy-type thermal fuse or an article with a built-in alloy-type thermal fuse, in which a flux is added to the outer surface of an easily oxidizable soluble alloy piece, and the flux-added soluble alloy piece is covered with an insulator. An insulator is formed by coating under heating with an insulating material without adding flux to the molten alloy piece, and after forming the insulator, a flux injection port is formed in the insulator, and after that, the injection port is formed. A method for producing an alloy-type thermal fuse, which comprises injecting flux from the above and adding flux to the fusible alloy piece. 3. The method for producing an alloy-type thermal fuse according to claim 1, wherein the coating under heating with an insulating material is performed by coating molding of a thermoplastic resin. 3. The method for producing an alloy-type thermal fuse according to claim 1, wherein the coating under heating with an insulating material is performed by injection molding of a thermoplastic resin. 3. The method for producing an alloy-type thermal fuse according to claim 1, wherein the coating with the insulating material under heating is performed by fusing the upper and lower thermoplastic resin films. 2. The method of manufacturing an alloy-type thermal fuse according to claim 1, wherein coating with an insulating material under heating is performed by injection molding of a thermoplastic resin, and a flux injection port is formed by a protrusion on the inner surface of the mold. 7. The method of manufacturing an alloy-type thermal fuse according to claim 1, wherein the flux injection port is closed by resin rivets, adhesive filling, or crush sealing after flux injection. . The method for producing an alloy-type thermal fuse according to any one of claims 1 to 7, wherein the fusible alloy piece is covered with an insulating material while being covered with an inner cover. An alloy-type thermal fuse manufactured by the manufacturing method according to claim 1. An article with a built-in alloy-type thermal fuse manufactured by the manufacturing method according to claim 1. The fusible alloy pieces connected between the lead conductors and the lead conductor portions near both ends thereof are sandwiched from above and below with a thermoplastic resin film, and a part of the periphery between the films is fused except for a part thereof. An alloy-type thermal fuse characterized by injecting a flux using the fused portion as a flux injection port, and then closing the unfused portion with a crushing seal such as ultrasonic fusion or dielectric heating fusion Manufacturing method .

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