JPS6235214B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a fuse element, and more particularly to a filament type fuse element with improved temperature characteristics and fusing characteristics. Prior Art and its Problems Conductive filament type fuses are known in which the surface of a single filament of a conventional polyacrylonitrile filament is chemically plated or electrolytically plated after chemical plating. However, one of the disadvantages of this type of fuse is that the metal coating of the fuse element melts at relatively low temperatures. This means that the melting temperature of the metal coating on the surface of the single fiber is the softening temperature of the acrylonitrile resin that is the support (125℃ or lower).
This is because it is restricted by. In reality, it is unavoidable that the ambient temperature has a greater or lesser effect on the physical properties of the metal used as the fuse element, but the higher the melting point of the metal, the less the fuse is affected by the ambient temperature. Stable performance as a material. In general, the recrystallization temperature (T) at which the physical properties of metals change increases almost in proportion to the melting point of the metal, and the much higher this temperature (T) is than the ambient temperature, the more it is influenced by the ambient temperature. This is because there are few. Considering this, silver or silver alloys are preferable for use as fuse elements because they have a relatively high melting point, are not easily affected by ambient temperature, and have several other excellent properties that are well known as fuses. It is metal. However, conventional silver or silver alloy coatings have unstable temperature characteristics, and therefore have the disadvantage that their fusing characteristics also vary. In view of the above-mentioned problems, the present invention provides a fuse element that has excellent temperature characteristics and fusing characteristics and can withstand use over time. Means for Solving the Problems The fuse element according to the present invention has a single thread of quartz glass fiber as a base, and the outer periphery of the base is
Consisting of Ag, Cu, Sn and Sb, each content is
It is characterized by forming a silver alloy coating of 70 to 73% by weight, 22 to 24% by weight, 2 to 4% by weight, and 1 to 3% by weight. According to the present invention, the silver alloy coating containing a specific content of Sb provides much more stable temperature characteristics and fusing characteristics than conventional silver alloy coatings. Typically, the silver alloy coating is
Ag72.3wt%, Cu23.2wt%, Sn2.7wt% and
Consists of 1.8% by weight of Sb. The fuse element of the present invention is particularly used in electrical equipment rated for a low capacity current of 1 mA to 250 mA. The first characteristic feature of the fuse element according to the present invention is that it is stable over time. This is because the fuse element according to the present invention has a very high melting point and recrystallization temperature of 872°C and 245°C, respectively. These temperatures are higher than low melting point metals. In fact, the recrystallization temperature of a metal is roughly proportional to its melting point. In fact, 150℃
The recrystallization temperature of low melting metals that melt at or below 20°C is well within normal ambient temperatures. Therefore, recrystallization effects may occur even at room temperature in fuse elements made of metals with low melting points (150°C). It is undesirable for recrystallization to occur at such low temperatures. This is because it changes the physical properties of the metal, resulting in fusing characteristics different from those originally intended. This is a definite drawback for fuses. However, the fuse element according to the present invention can maintain great stability due to its physical properties even when the fuse is used for a long period of time at a temperature much higher than the ambient temperature of 245° C. or the temperature cycle at which the fuse is used. . A second feature of the present invention is that the fusing characteristics of the fuse element are stable under low overload conditions. This is Sb added to the metal coating component at a rate of 3% or less (preferably about 2%).
lowers the temperature coefficient of the fuse element, reduces the influence of ambient temperature on fusing at low overloads, and reduces variation in fusing time. A third feature of the present invention is that the quartz glass fiber that forms the base of the fuse element has high heat resistance. It withstands continuous use at 1000°C or below and maintains a viscosity of 4.6x10 ⁷ poise even at temperatures of 1500°C. This is a high temperature that still leaves a considerable margin compared to the melting point of 875° C. of the silver alloy of the fuse element according to the present invention. Therefore,
Unlike a resin base whose melting point is lower than the melting point of the metal coating applied to its surface, the fuse element of the present invention is fused solely due to the characteristics of the silver alloy coating and is controlled by the temperature of the quartz glass fiber base. It is not affected by this and the shutdown is completed. A fourth feature of the present invention is that the fuse element has extremely precise and excellent fusing characteristics.

[Table] As shown in Table 1, the glass fibers constituting the support of the fuse element are made of resin material (5-
Since the coefficient of thermal expansion is much smaller than that of metal materials (20x10 ^-5 deg ^-1 ) and metal materials (4 to 60x10 ^-6 deg ^-1 ), thermal expansion due to Joule heat generation hardly occurs even when current flows. Therefore, extremely accurate fusing characteristics are expected. (In fact, since any fuse element is structurally connected and fixed between both ends of a conductive terminal, the fuse element linearly expands and sag due to the generation of joule heat when energized. Generally,
Since the fuse element is housed within the container, the slackened portion may approach or even come into contact with the inner wall of the container. This is one of the causes of variations in fusing time due to conduction of the generated Joule heat. ) Embodiment An embodiment of the fuse element of the present invention will be described with reference to the drawings. In FIG. 1, the horizontal axis shows temperature change (°C), and the vertical axis shows resistance temperature change (%). Lines 1, 2, 3, 4, and 5 in Figure 1 indicate a silver alloy coating (its composition is 70 to 73% by weight of Ag,
Cu content is 22 to 24% by weight, So content is 2% by weight.
to 4% by weight. The temperature coefficient of resistance characteristics were shown when the Sb content was 1%, 2%, 3%, 6%, and 0% by weight, respectively. As is clear from the figure, when the Sb content is 1% by weight, -
At 75ppm/℃, at 2% by weight, it is -150ppm/℃, and even at 3% by weight, it is only -300ppm/℃. 5) -2000ppm/
This is a remarkable difference (improvement) compared to °C. (Here, ppm means one millionth (10 ^-6 ).) This shows that the temperature characteristics of the fuse element are extremely stable. That is, this shows that the resistance value is stable against changes in ambient temperature, and therefore the fusing characteristics are stable. As can be seen from Figure 1, the Sb content is 3.
If it exceeds 6% by weight, for example, the temperature coefficient of resistance becomes relatively large and no practical improvement can be obtained. FIG. 2 shows the difference in temperature characteristics between a fuse element according to the invention and a fuse element according to the prior art. The horizontal axis shows the change in ambient temperature (°C), and the vertical axis shows the change in rated current value (%). 6 in the figure shows a conventional fuse element (i.e., an alloy of Ag and Cu on a base made of insulating resin such as polyacrylonitrile, polyester, or polyethylene (its composition is such that the content of Ag is 72%). weight%, Cu content is 28% by weight)
Figure 7 shows the temperature characteristics of
shows the temperature characteristics of the fuse element of the present invention. A silver alloy film with a thickness of 1 μm (in this example, 72.3% by weight of Ag, 23.2% by weight of Cu, 2.7% by weight of Sn, and In a test using a fuse element coated with Sb (1.8% by weight), a rated current value of 63mA was obtained. As shown in this figure, 6 (prior art fuse element) is at ambient temperature.
It undergoes a maximum change of 70% at 150℃, but 7
(The fuse element according to the invention) is subject to changes of only about 5%. This is due to the combined effect of the fact that the fuse element according to the present invention uses a single silica glass material as an insulating base, and that it uses a fuse element coated with a silver alloy coating having the composition as described above. However, as shown in Fig. 1, the effect of adding Sb is large, so it is thought that the main effect of the effect shown in Fig. 2 is the metal material applied to the fuse element. Figure 3 is a diagram showing the melting time (seconds) on the horizontal axis and the change (%) with respect to the rated current on the vertical axis, and 8 is a fuse element according to the prior art (its metal material is as described in the explanation of Figure 2 above). 9 is a silver alloy coating according to the present invention (in this example, Ag72.3% by weight, Cu23.2% by weight, Sn2.7
% by weight and the fusing characteristics of a fuse element treated with 1.8% by weight of Sb. Whereas fuse elements according to the prior art exhibit a curve of 8 in some cases and 8' in others, the fuse element according to the invention maintains narrow width ranges such as 9 and 9'. There is. This indicates that the fusing characteristics of the fuse element of the present invention have little variation. Effects of the Invention As described above, the fuse element according to the present invention has excellent temperature characteristics and fusing characteristics, and can withstand long-term use.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing how Sb added to the silver alloy coating affects the resistance temperature change, and FIG. 2 is a diagram showing the temperature characteristics of the fuse element of the present invention. FIG. 3 is a diagram showing the fusing characteristics of the fuse element of the present invention. 1, 2, 3, 4, 5...The content of Sb added to the silver alloy film is 1% by weight, 2% by weight, 3% by weight, 6% by weight, 0% by weight, 6, 8, 8 '...
... Fuse element according to prior art, 7, 9,
9'... Fuse element of the present invention.

Claims (1)

[Claims] 1 A silver alloy having a single thread of quartz glass fiber as a base, and containing Ag, Cu, Sn, and Sb on the outer periphery of the base, each containing 70 to 73% by weight, 22 to 24% by weight, and 2 to 4% by weight. A fuse element formed by forming a film.