JP2005154797A - Fusible alloy for thermal fuse, and thermal fuse - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fusible alloy for a thermal fuse, which does not contain lead, is environmentally good and has practicality as well, and a thermal fuse using the alloy. <P>SOLUTION: The fusible alloy for the fuse which is composed of an alloy composition containing 25 to 39wt% Sn and 0.1 to 5wt% Bi and consisting of the balance In without using Pb and whose melting temperature is 120°C to 140°C is constituted. The fusible alloy is appropriate for use as a protection for a power transformer which is a main component of a power-supply circuit. The fusible alloy is also is usable for applications other than the power transformer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fusible alloy used for a non-returnable temperature fuse that detects an abnormal temperature rise and shuts down a circuit to protect an electronic device for home appliances, and a temperature fuse using the same.

  Recently, environmental problems have been screamed, and various studies have been conducted on the reduction of environmental pollutants and conversion to alternative substances.

  When assembling electronic equipment, solder is used for substrate wiring. Recently, the toxicity of lead, which is the main component of solder, has been highlighted, and solder containing no lead has been studied.

  The fusible alloy used for thermal fuses is no exception.

  Conventionally, a Pb—Sn—In alloy is used as a soluble alloy for a thermal fuse that operates in a temperature range of 123 to 136 ° C.

  Since this soluble alloy contains lead, it is not environmentally preferable.

  In other words, it is difficult to recover solder used for printed circuit boards and thermal fuses of home appliances, and waste home appliances may be eluted by acid rain and flow into groundwater or rivers, causing serious lead damage to animals and plants such as human bodies. There is a great negative impact on the environment.

  The present invention has been proposed in view of the above, and the object of the present invention is to use a soluble alloy for thermal fuses that does not contain lead and is environmentally good and also has practicality, and an alloy thereof. It is to provide a thermal fuse.

  The invention described in claim 1 is configured to contain Sn25 to 39 wt%, Bi 0.1 to 5 wt%, with the balance being In.

  Invention of Claim 2 set it as the structure which added 5 wt% or less of at least 1 type of Cu, Ag, Au, Ni, Pd, Zn to the said mixing | blending in Claim 1.

  The invention according to claim 3 is configured to include a soluble alloy for a thermal fuse that contains Sn25 to 39 wt%, Bi 0.1 to 5 wt%, and the balance is In.

  According to the first to third aspects of the present invention, since a desired melting temperature is obtained and lead which is an environmental pollutant is not included, there is an advantage that the environment is not harmed.

[Embodiment 1]
The fusible alloy for thermal fuses of the present invention is composed of Sn as 25 to 39 wt%, Bi as 0.1 to 5 wt%, and the balance as In, and the melting temperature is 120 to 140 ° C.

  In the thermal fuse alloy, Sn (tin) is used as a base material from the viewpoint of the melting point. Further, as other elements to be added thereto, for example, Ag (silver), Cu (copper), Bi (bismuth), Zn (zinc), In (indium) and the like exist.

  It is desirable that a temperature fuse used for protecting a power transformer, which is a main component of a power circuit of an electronic device, melts in a temperature range of 123 to 136 ° C.

  In the present invention, Sn, Bi, In is selected from various materials from this viewpoint, and the content is set to a predetermined amount.

  That is, as Sn is increased, the melting temperature tends to decrease. Further, when the addition amount of In or Bi is increased, the melting temperature tends to decrease.

  However, this tendency is not always observed in all blends, and it varies depending on blends. In addition, when a certain addition amount is exceeded, this tendency may be reversed.

  There is a certain rule regarding the hardness, which is soft when In is increased, and hard when Bi or Sn is increased.

  In view of the above, in the present invention, the material is selected from various materials, and the data is obtained by variously adjusting the blending amount, Sn is 25 to 39 wt%, Bi is 0.1 to 5 wt%, and the balance And a soluble alloy having a melting temperature and strength suitable for protecting a power transformer. In the present invention, Sn is used because the wettability of the soluble alloy is improved by Sn, and the reason why Sn is set to 39 wt% is that the temperature is excessively lowered when exceeding this. Moreover, it is because a desired effect cannot be expected at 25 wt% or less. The reason why Bi is added to 0.1 to 5 wt% is that if it is added more than this, the melting temperature is too low, and if a large amount of Bi is added, the alloy becomes hard and brittle, and workability is increased. This is because remarkably decreases.

  Next, a production example of the soluble alloy of the present invention will be described.

  The wire made of the soluble alloy of the present invention can be produced, for example, by an extrusion method by extrusion molding. This extrusion method includes a raw material blending step of blending a soluble alloy raw material forming the wire into a melting furnace, and a blended raw material. Is prepared by melting an alloy and adjusting an alloy and pouring the alloy into a mold to produce an ingot, and a thinning process for producing a wire by thinning the ingot.

  At the time of production, first, in the raw material blending method, Sn, Bi, In, which is the raw material of the wire rod, is weighed, blended and melted so that the alloy blend is Sn25-39 wt%, Bi0.1-5 wt%, and the remainder In. Put it in the furnace.

  In the ingot production step, the above-mentioned blended raw material is melted at a temperature of 350 to 450 ° C., and the molten alloy is poured into a cylindrical mold to produce a cylindrical ingot.

  In the thinning step, a fusible alloy for a fuse can be produced by loading an ingot into an extrusion press machine to which a die having a hole with a desired wire diameter is attached and making the wire thin by extruding from a hole in the die.

  As an example, FIG. 1 shows a DSC chart of an alloy having an alloy composition of Sn34.9-Bi0.3-In64.8, and FIG. 2 shows an operating temperature of a thermal fuse produced using this alloy. FIG. 3 shows an example of a thermal fuse, in which (1) is a soluble alloy for fuses of the present invention, (2) is a lead wire connected to each end thereof, and (3) is a soluble alloy (1). Flux provided in the periphery, (4) is a cylindrical case for storing them, and (5) is a sealing material for closing the opening of the case (4).

  In FIG. 1, DSC is an abbreviation for Differential Scanning Calorimetry, which is a differential scanning calorimetry method. From the DSC, the melting point (liquidus point) of the alloy is known. That is, the melting point of the soluble alloy according to the example of the present invention is 125.84 ° C. as a peak of the DSC curve.

  FIG. 2 is a histogram obtained by measuring the fusing temperature of a thermal fuse produced using the alloy of the example, and the fusing temperature distribution of the thermal fuse can be understood from this histogram. The average cutoff temperature in this example is 123.9 ° C.

  In the present invention, Sn25 to 39 wt%, Bi0.1 to 5 wt%, and the balance In, but at least one or more of Cu, Ag, Au, Ni, Pd, Zn, etc. is added to this blend at 5 wt% or less. An alloy may be produced, and this case is also suitable as a temperature fuse for protecting a power transformer.

  Further, the fusible alloy for fuse and the thermal fuse of the present invention can be used in addition to the power transformer.

The DSC chart of the fusible alloy for fuses of this invention is shown. The histogram of the operating temperature of the thermal fuse which uses the fusible alloy for fuses of this invention is shown. 1 shows an example of a thermal fuse using the fusible alloy for fuses of the present invention.

Explanation of symbols

1 Fusible alloy for fuse 2 Lead wire 3 Flux 4 Case 5 Sealing material

Claims (3)

A soluble alloy for a thermal fuse, characterized in that it contains Sn25-39 wt%, Bi0.1-5 wt%, and the balance is In. The soluble alloy for a thermal fuse according to claim 1, wherein at least one of Cu, Ag, Au, Ni, Pd, and Zn is added to the composition at 5 wt% or less. A thermal fuse comprising a soluble alloy for thermal fuses containing Sn25 to 39 wt%, Bi 0.1 to 5 wt%, with the balance being In.

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