JP6015571B2 - Pb-free Zn-Al alloy fuse - Google Patents

Description

  The present invention relates to an alloy fuse using a Zn—Al-based alloy, and more particularly to a fuse used for various electronic parts such as electronic equipment and cement resistance.

Generally, a protective device is attached to an electronic component in order to prevent a failure or breakage due to overcurrent or excessive temperature rise, and a fuse protects the electronic component or the like by adjusting a design temperature.
For example, the fuses can be classified into two types: a pellet type thermal fuse and a fusible alloy type thermal fuse.

  Pellet-type thermal fuse is a thermal fuse using a metal case and organic compound pellet temperature sensitive material. Insulating bush, spring, movable contact, disc and temperature sensitive pellet are incorporated in the metal case, and the case opening With a sealing material. Before operation, current flows through the lead wire, movable contact, metal case, and lead wire. When the ambient temperature rises, the temperature-sensitive pellet melts due to heat, the spring extends, and the movable contact is pushed away from the lead. Thus, the current is cut off.

  In addition, a fusible alloy type thermal fuse uses a low melting point fusible alloy as a temperature-sensitive material, and is built into a current-carrying circuit to melt the low melting point fusible alloy and shut off the circuit when the ambient temperature rises excessively. It has become. There are two types of fusible alloy type thermal fuses, an axial lead wire type and a radial lead wire type. The lead wire is welded to the low melting point fusible alloy, and the fusible alloy ensures the fusing during operation on the surface. In order to perform this, a special resin is coated and then placed in an insulating case, and the case opening is sealed with a sealing material. As the temperature of the device rises, the heat is sensed from the main body of the thermal fuse and the lead wire, and when the melting point of the fusible alloy is reached, the fusible alloy melts. The surface tension is exerted, and the fusible alloy is spheroidized into lead wires for fusing.

  Further, when fuses are classified in terms of fusing characteristics, they are classified into three types: normal fusing type, time lag fusing type, and fast-acting fusing type. The normal fusing type is a general type used for communication equipment and the like, and has characteristics of a time lag fusing type and a fast-acting fusing type. The time lag fusing type is for motors and surge currents. It does not blow for momentary overcurrents such as motor start-up current, and the fusing time for overcurrents is long, protecting circuits with momentary overcurrents. Used to do. The fast-acting fusing type is characterized by a quick reaction to overcurrent and a short fusing time, and is used for semiconductor protection and the like.

  As described above, various fuses are used for protecting electronic parts and the like, and for example, Zn-based fuses are used as Pb-free fuses. However, since various problems remain depending on the application, various investigations have been made on this Zn-based fuse. For example, prior applications such as Patent Documents 1 to 3 are disclosed.

JP 2008-034394 A JP 2006-322027 A JP 2007-207558 A

  In Patent Document 1, the fusing characteristics can be adjusted, the temperature rise during energization is lower than that of the conventional product, and various properties such as mechanical properties and workability such as pressing and forging are improved. In order to provide a relatively inexpensive material that can be used stably as a fuse for automobiles in the long term, Al: 3.0 to 8.0% and Mg: 0.0005 to 0.06 by weight %, And the balance using a zinc alloy material consisting of Zn and inevitable impurities is disclosed. The fuse material has a fusing part formed by a forging process and a punching process, or by a normal wire drawing process. The fuse material, which is finished in a linear shape with a diameter of 0.1 to 5.0 mm and contains standard 6.4% Al-0.005% Mg, is not blown by an instantaneous overcurrent, and has a relatively long time. As an automotive fuse that blows due to overcurrent Illustrates a preferred "lag fusible" is described as.

  Patent Document 2 discloses a fuse element that can sufficiently reduce the fusing temperature of a fuse element made of an alloy containing Zn-Al to be incorporated in a tantalum capacitor or the like and that can be safely maintained against soldering mounting by lead-free solder. For the purpose of providing, it contains Zn, Al and Ge, each content of Al and Ge is 0.5 to 15%, the total amount of Al and Ge is 5 to 20%, and the balance is Zn. A fuse element in which an alloy is processed into a thin wire is disclosed. The reason why the respective contents of Al and Ge are 0.5 to 15% is that the ratio of the heat of solution H260 ° C to 370 ° C and the total heat of heat ΣH at 260 ° C to 370 ° C H260 ° C to 370 ° C / It is also stated that ΣH is set to 0.2 or more so that the fuse element fusing temperature is made lower than the fusing temperature of the Zn-Al fuse element.

  Patent Document 3 provides a fusible alloy type thermal fuse and a circuit protection element using a low melting point fusible alloy that does not include an environmentally harmful harmful metal and can set an operating temperature in a high temperature region of 260 ° C. or higher. For this purpose, a low melting point soluble alloy 3 is joined to a pair of lead members 1 and 2 by resistance welding, a flux coating 4 is formed on the surface of the low melting point soluble alloy 3, and a ceramic soot tube made of alumina or the like. There is disclosed a fusible alloy type thermal fuse housed in an insulating container or case 5. For example, the low melting point soluble alloy 3 includes 95Zn-5Al having a melting operating temperature of 381 ° C., 89Zn-6Al-5Ge having a melting operating temperature of 352 ° C., or 93Zn-4Al-3Mg (wt%) having a melting operating temperature of 343 ° C. ) Is used, and the flux is prepared by blending a heat-resistant rosin derivative and an organic acid amide derivative, and any one of Sn, In and Ga can be added to adjust the melting operation temperature. It is also described. [Claim 1] further relates to a thermal fuse in which a low melting point soluble alloy having a flux coating is connected between electrode portions connected to a pair of lead members and accommodated in an insulating case. The melting point soluble alloy is any alloy selected from Zn—Al alloy, Zn—Al—Ge alloy and Zn—Al—Mg alloy, and the melting operation temperature is in the range of 260 ° C. to 400 ° C. A fusible alloy type thermal fuse characterized in that the low melting point fusible alloy is composed of 1.5 to 7.0 wt% Al and Ge is disclosed in [Claim 8]. There is disclosed a circuit protection element using a Zn—Al—Ge alloy of 1.5 to 7.0 wt%, the balance being Zn and inevitable impurities.

However, in such patent documents, it must be said that there are problems with the disclosed technologies.
Patent Document 2 discloses a fuse element that can sufficiently reduce the fusing temperature of a fuse element made of an alloy containing Zn-Al to be incorporated in a tantalum capacitor or the like and that can be safely maintained against soldering mounting by lead-free solder. For the purpose of providing, it contains Zn, Al and Ge, each content of Al and Ge is 0.5 to 15%, the total amount of Al and Ge is 5 to 20%, and the balance is Zn. A fuse element in which an alloy is processed into a thin wire is disclosed. The reason why the respective contents of Al and Ge are 0.5 to 15% is that the ratio of the heat of solution H260 ° C to 370 ° C and the total heat of heat ΣH at 260 ° C to 370 ° C H260 ° C to 370 ° C / It is also stated that ΣH is set to 0.2 or more so that the fuse element fusing temperature is made lower than the fusing temperature of the Zn-Al fuse element. However, the solidus temperature of Zn—Al—Ge is 356 ° C., and the total amount of Al and Ge is 5 to 20%, so that the solidus temperature does not become 350 ° C. or lower, and the fusing temperature is It does not reach 260-350 ° C. Furthermore, compared with Zn, the heat capacities of Al and Ge are not significantly changed. When the total amount of Al and Ge is changed within the range of 5 to 20%, the melting heat amount at 260 ° C. to 370 ° C. is H260 ° C. to 370 ° C. The ratio H260 ° C. to 370 ° C./ΣH with the amount of heat ΣH is considered not to change significantly. In addition, if the amount of Ge of 0.5 mass% or more and 15 mass% or less is included in Zn-based solder used for general-purpose products from the viewpoint of cost, the cost becomes very high, and it can be used practically It seems difficult. As described above, the technology described in Patent Document 2 has an unclear technical explanation, and is not practical in terms of cost. Therefore, it is clear that the technology is not actually usable.

Patent Document 3 provides a fusible alloy type thermal fuse and a circuit protection element using a low melting point fusible alloy that does not include an environmentally harmful harmful metal and can set an operating temperature in a high temperature region of 260 ° C. or higher. For this purpose, a low melting point soluble alloy 3 is joined to a pair of lead members 1 and 2 by resistance welding, a flux coating 4 is formed on the surface of the low melting point soluble alloy 3, and a ceramic soot tube made of alumina or the like. There is disclosed a fusible alloy type thermal fuse housed in an insulating container or case 5. For example, in the low melting point soluble alloy 3, 95Zn-5Al having a melting operating temperature of 381 ° C., 89Zn-6Al-5Ge having a melting operating temperature of 352 ° C., or 93Zn-4Al-3Mg (wt%) having a melting operating temperature of 343 ° C. Flux is prepared by blending a rosin derivative with good heat resistance and an organic acid amide derivative, and any one of Sn, In and Ga can be added to adjust the melting operation temperature. Is also described. [Claim 1] further relates to a thermal fuse in which a low melting point soluble alloy having a flux coating is connected between electrode portions connected to a pair of lead members and accommodated in an insulating case. The melting point soluble alloy is any alloy selected from Zn—Al alloy, Zn—Al—Ge alloy and Zn—Al—Mg alloy, and the melting operation temperature is in the range of 260 ° C. to 400 ° C. A fusible alloy type thermal fuse characterized in that the low melting point fusible alloy is 1.5 to 7.0 wt% Al and Ge is 1 is disclosed. The circuit protection element according to claim 6, wherein a Zn—Al—Ge alloy composed of 0.5 to 7.0 wt% and the balance of Zn and inevitable impurities is used.
The low melting point soluble alloy has Al of 1.5 to 7.0 wt%, Ge of 1.5 to 7.0 wt%, and the balance of Zn, which is a 95Zn-5Al composition having a melting point of 381 ° C. The melting temperature is further lowered from the crystal alloy. Outside this composition range, the melting point of the alloy becomes too high, and the fusing operation due to heat generation of the heat generation resistor becomes slow, and a satisfactory effect as a circuit protection element cannot be obtained. That is, when the range of Ge exceeds 7 wt%, the alloy becomes brittle and it becomes difficult to process the material, and when it is less than 1.5 wt%, the melting point lowering effect is not seen. The best composition is described that Al is 6 wt%, Ge is 5 wt%, and the balance is Zn, and that the addition of Ge can be expected to prevent oxidation of a low melting point soluble alloy.
However, when the Ge content is 1.5 to 7.0 wt%, the content is large and the cost is increased. And the effect of Ge by less than 1.5% by mass of Ge is not described, and conversely, it is described that the effect of lowering the melting point is not seen if less than 1.5% by weight, and is described in Patent Document 3. The invention relating to the Zn—Al—Ge alloy can be interpreted that the Ge content is 1.5 to 7.0 wt%. There is no description of the effect of improving the weather resistance of Ge.

  Therefore, the present invention, as a result of intensive studies to solve these problems, has provided a fuse material and a fuse having a basic composition of a Pb-free Zn—Al alloy.

The Pb-free Zn— Al-based alloy fuse according to the present invention contains Al in an amount of 2% by mass to 8% by mass, Ge in an amount of 0.001% by mass to 0.03% by mass, and the remainder is inevitable in manufacturing. It is characterized by being composed of Zn excluding contained elements.

  The fuse material and fuse of the present invention not only have excellent workability and fusing characteristics, but also provide a fuse material and a fuse that suppresses heat generation during energization and also has excellent environmental resistance, wettability, and bondability. can do. As a result, breakage of electronic components and the like, ignition due to excessive temperature rise, fire, and the like can be reliably suppressed, and a protection circuit design suitable for the purpose can be achieved. In addition, the fuse material of the present invention is Pb-free and is a suitable material in consideration of environmental pollution.

Hereinafter, the Pb-free fuse material and the fuse according to the present invention will be described in detail.
Fuse material according to the present invention, and fuse contains a Al 2 mass% or more and 8 mass% or less, a Ge containing less than 0.001% by mass to 0.5% by mass.
Furthermore, the thickness of the oxide film on the surface may be 50 nm or less. In addition, these fuse materials and the like more preferably have an Al content of 2% by mass or more and 4.5% by mass or less, and further contain at least one of Ni, Cu, Ag, and P. Good.

  The fuse material according to the present invention has higher characteristics with respect to various required characteristics than conventional fuse materials. Therefore, based on the composition in the vicinity of the eutectic point of the Zn-Al alloy, the weather resistance and environmental resistance are improved by containing a small amount of Ge, and in addition, the wettability is reduced by keeping the surface oxide film thin. In addition, characteristics such as bondability are improved. Hereinafter, the essential elements and conditions of the present invention will be described in more detail.

<About Zn>
Zn is an essential element in the present invention. Zn has a melting point of 419 ° C. and is selected because it has a melting point suitable for a thermal fuse. In addition, the low specific electrical resistance is 5.92 (μΩ · cm), which is a major reason for selection. In addition, since various elements are dissolved in solid or an intermetallic compound is appropriately generated, it is easy to adjust the fusing characteristics and the like, and it is easy to impart mechanical strength. With the above reasons as the main background, Zn is selected as the main component of the present invention.

<About Al>
Al is an essential element in the present invention, and the purpose of including Al includes adjustment of melting point, adjustment of fusing characteristics, improvement of mechanical characteristics, temperature rise suppression effect during energization, and the like.
First, the melting point can be adjusted by adding Al. That is, Al forms a eutectic alloy with Zn, the eutectic point is Al = 5% by mass, and the solidus temperature is 381 ° C. Therefore, by setting the Al content near the composition of the eutectic point, the solidus temperature can be made 381 ° C., and the liquidus temperature can be adjusted according to the purpose. By adjusting the solidus temperature and the liquidus temperature, the fusing characteristics can be controlled with a considerable degree of freedom.

  Furthermore, mechanical characteristics and workability can also be adjusted by containing Al. In other words, Zn alone is relatively soft when rolling or the like, causing meandering, undulation, etc., making it difficult to achieve the target shape, and naturally the productivity is poor. By containing Al, an appropriate strength can be imparted, and cracks are difficult to occur due to crystal refinement near the eutectic point, and the elongation rate is improved, so that it becomes an easy-to-use material that can sufficiently withstand practical use.

  In addition, Al has a specific electric resistance of 2.65 (μΩ · cm), which is smaller than that of Zn, and can easily flow electricity, thereby suppressing the generation of Joule heat. Therefore, unnecessary power consumption during energization can be suppressed, and of course, heat generation around the fuse due to Joule heat can be suppressed, failure frequency of electronic parts, electronic circuits, etc. can be reduced, heat resistance can be reduced, and miniaturization can be achieved. Is possible.

  The content of Al having such an excellent property improving effect is 2.0% by mass or more and 8.0% by mass or less. If the Al content is less than 2.0% by mass, the content is too small to obtain sufficient mechanical properties. Furthermore, the difference between the liquidus temperature and the solidus temperature becomes so large that the crystal grains become too large when the fuse is welded, or a melting and separation phenomenon occurs, so that sufficient bonding strength cannot be obtained. On the other hand, if the Al content exceeds 8.0% by mass, the above-described melting and separation phenomenon occurs, or the liquidus temperature becomes 410 ° C. or higher, and the melting point becomes too high.

  When the Al content is 2.0% by mass or more and 4.5% by mass or less, the Zn-rich side is obtained from the eutectic point, and since the Al content that is easy to oxidize is small, even better bondability can be obtained. At the same time, the weather resistance is improved. For this reason, by setting the Al content to 2.0 mass% or more and 4.5 mass% or less, a further excellent fuse material and fuse are obtained.

<About Ge>
Ge is an essential element in the present invention, and the main purpose of containing Ge is to improve wettability and weather resistance. That is, Zn is a relatively easily oxidized and reactive element, and Al is more easily oxidized. Therefore, it is difficult to say that a Zn-Al alloy has sufficient weather resistance, corrosion resistance, and environmental resistance. . Ge is an element that exhibits a dramatic effect in improving the weather resistance and the like.

  By including Ge in the Zn—Al alloy, Ge is condensed on the surface, and the oxidation of the main component metal of Zn or Al is suppressed, and thus the oxide film is prevented from becoming thick. As a result, wettability is improved, and sufficient bonding strength for bonding the fuse can be obtained. Naturally, it is also effective in suppressing oxidative degradation, leading to improved weather resistance. In addition, Ge exhibits a sufficient effect in a small amount, and conversely, if the amount increases, not only the workability and mechanical properties of the Zn-Al alloy are lowered, but also expensive Ge increases, which is disadvantageous in terms of cost. Become. Furthermore, if Ge exceeds 0.5% by mass, the oxide film becomes too thick and sufficient wettability and bondability cannot be obtained.

  The Ge content is 0.001% by mass or more and less than 0.5% by mass of Ge. If it is less than 0.001% by mass, the content is too small and the effect of containing Ge does not appear substantially, and if it exceeds 0.5% by mass, the Zn—Al—Ge alloy becomes too hard and the workability is greatly reduced. Or a wire-shaped or ribbon-shaped fuse is likely to break, resulting in a failure or failure. The reason why the alloy is hardened by containing Ge is that Ge exhibits a semi-metallic property and is brittle.

<About Ni>
Ni is an element that may be contained as necessary. The purpose of containing Ni is to improve workability by refining the crystal. That is, since Ni hardly dissolves in Zn or Al, it precipitates as an initial crystal upon cooling after melting, and the crystal becomes finer with the primary crystal serving as a nucleus. For this reason, softness increases and workability and stress relaxation properties are improved. The Ni content is 3.0% by mass or less. If the content exceeds 3.0% by mass, the Ni content is too large and the crystal becomes coarse regardless of the content of other elements, and the workability and mechanical properties are reduced. End up.

<About Cu>
Cu is an element that may be contained as necessary. The purpose of containing Cu is solid solution strengthening. That is, Cu functions to stop dislocation by dissolving in Zn to about 3% by mass. This increases the strength. Although Cu improves strength and suppresses crack growth, etc., Cu itself has flexibility, so it does not lower the flexibility and elongation of the alloy, and therefore does not lower stress relaxation properties. . And if content exceeds 3.0 mass%, the hardness of an alloy will rise and workability will fall rapidly.

<About Ag>
Ag is an element that may be contained as necessary. The purpose of containing Ag is also solid solution strengthening like Cu. That is, as can be inferred from the Ag—Zn phase diagram and the Cu—Zn phase diagram, these phase diagrams are very similar. Therefore, the effect of Ag is the same as that of Cu. The Ag content may be determined in consideration of the required alloy properties, but the upper limit is 3.0% by mass. If the content of Ag exceeds 3.0% by mass, the alloy becomes too hard and the workability is drastically reduced.

<About P>
P is an element that may be contained as necessary, and its effect is in improving wettability. The mechanism by which P improves wettability is as follows. P is highly reducible, and suppresses oxidation of the alloy surface by oxidizing itself, while reducing the joint surface and improving wettability.

  Moreover, the effect of reducing the generation | occurrence | production of a void at the time of joining by containing P is also acquired. That is, as already described, since P is easily oxidized by itself, oxidation proceeds preferentially. As a result, oxidation of the fuse parent phase can be prevented, and wettability can be ensured by reducing the joint surface during welding or the like. At the time of this bonding, the fuse and the oxide on the surface of the bonding surface are eliminated, so that an unbonded portion formed by the oxide film is less likely to be generated, and the bonding property and long-term reliability are improved.

  Note that P is vaporized when it is reduced to an oxide by reducing the alloy or the joint surface, and is not left behind in the atmospheric gas. For this reason, there is no possibility that the residue of P adversely affects reliability and the like, and it can be said that this is an excellent element. The amount in the case of containing P is preferably 0.550% by mass or less. Since P is very reducible, the effect of improving wettability can be obtained by adding a trace amount. Even if the content exceeds 0.50% by mass, the effect of improving wettability and bondability does not change much, and excessive content causes a large amount of P or P oxide gas to be generated. Or P forms a brittle phase and segregates, making the joint brittle and reducing reliability. In particular, it has been confirmed that wire breakage is likely to cause disconnection.

<About surface oxide film>
In the present invention, the thickness of the oxide film of the fuse may be 50 nm or less. In other words, if the thickness of the oxide film increases, when the fuse is bonded, the oxide film cannot be in direct contact with the metal connection portion of the bonding surface, so that the alloying is insufficient and the bonding can withstand practical use. This is because the strength cannot be obtained. In order to join metals together, alloying between joined materials must proceed, but if there is a thick oxide film between metals, this alloying does not proceed. Therefore, the thickness of the oxide film of the fuse is preferably 50 nm or less. Although depending on the bonding conditions, generally good bonding is possible if the thickness of the oxide film is within a range of 50 nm or less.

Hereinafter, the present invention will be described in more detail based on examples.
First, Zn, Al, Ge, Ni, Cu, Ag, P, and Ti having a purity of 99.9% by mass or more were prepared as raw materials. Large flakes and bulk-shaped raw materials were cut and pulverized, etc. so as to be uniform with no variation in composition depending on the sampling location in the alloy after melting, and were reduced to a size of 3 mm or less. Next, a predetermined amount of these raw materials was weighed into a graphite crucible for a high-frequency melting furnace.
The crucible containing the raw material was placed in a high-frequency melting furnace, and nitrogen was flowed at a flow rate of 0.7 L / min or more per 1 kg of the raw material in order to suppress oxidation. In this state, the melting furnace was turned on to heat and melt the raw material. When the metal began to melt, it was stirred well with a mixing rod and mixed uniformly so as not to cause local compositional variations. After confirming sufficient melting, the high frequency power supply was turned off, the crucible was quickly removed, and the molten metal in the crucible was poured into the solder mother alloy mold. As the mold, a cylindrical shape having a diameter of 19 mm × 100 mm in length for wire extrusion and a punch having a width of 40 mm × length of 200 mm × thickness of 5 mm were used.
In this way, the solder mother alloy of Sample 1 was produced. Solder mother alloys of Samples 2 to 38 were prepared in the same manner as Sample 1 except that the mixing ratio of the raw materials was changed. The compositions of the solder mother alloys of Samples 1 to 38 were analyzed using an ICP emission spectroscopic analyzer (SHIMAZU S-8100). The analysis results are shown in Table 1 below.

（注）表中の※を付した試料は比較例である。

(Note) Samples marked with * are comparative examples.

Next, each solder mother alloy of Samples 1 to 38 was processed into a wire shape with an extruder and into a sheet shape with a rolling mill as described below. In addition, the number of defects such as wire breakage and scratches per unit length was counted at the time of wire extrusion, and it was set as workability evaluation 1. For each sample rolled into a sheet, the number of defects such as cracks and chips per unit length is counted to obtain workability evaluation 2, and the defect rate when punched with a press is further calculated and processed. It was set as 3 sex evaluation. About each sample processed into the wire shape and the sheet | seat shape, the thickness of the oxide film was measured using the scanning projection type Auger electron spectrometer (the product made from ULVAC-PHI, model: SAM-4300). The results are shown in Table 1. Since the surface roughness of the sample also affects the bondability and weldability, it is necessary to control it. By adjusting the surface processing in the holes of the extrusion die and the surface processing of the rolling roll, The surface roughness (Ra) of the sample (wire, sheet, punched product) was set in the range of 0.50 ± 0.15 μm.
Furthermore, using these samples, the tensile strength was measured to evaluate mechanical properties, and the fusing properties, temperature rise, and weather resistance were also evaluated.

<Processability evaluation 1 (processing to wire shape)>
Each mother alloy (diameter 19 mm × length 100 mm) of the prepared samples 1 to 38 shown in Table 1 was processed into a wire shape having a diameter of 1.0 mm using an extruder. At this time, the extruded wire was extruded while flowing nitrogen so that the surface oxidation of the extruded wire did not proceed. The wire was extruded 50 m, and the case where there was no disconnection or scratch was evaluated as “◯”, and the case where one or more disconnections or one or more scratches occurred was evaluated as “x”.

<Processability evaluation 2 (processing into sheet shape)>
The prepared master alloys (width 40 mm × length 200 mm × thickness 5 mm) of samples 1 to 38 shown in Table 1 were adjusted to a thickness of 0. 0 mm while applying rolling oil using a rolling mill. Rolled to 10 mm. The case where there were no burrs or cracks per 10 m of the sheet was evaluated as “◯”, the case where one to three burrs or cracks occurred was evaluated as “Δ”, and the case where four or more burrs occurred was evaluated as “x”.

<Processability evaluation 3 (processing to punched products)>
Each sheet-like sample after rolling was cut into a width of 30 mm by slitting and punched into a 0.7 mm × 0.7 mm square using a die press to produce 1000 punched products. A punched product that shows defects such as burrs or chippings is considered a “defective product”, and a product that does not have such a defect and is neatly punched into a 0.7 mm × 0.7 mm square shape is considered a “good product”. The rate was calculated to be a workability evaluation of 3.

<Evaluation of mechanical properties (tensile strength)>
Each sample processed into a wire shape having a diameter of 1.0 mm by the same method as in workability evaluation 1 was cut into 100 mm, and used as a sample for measuring tensile strength. The tensile tester was measured using a Tensilon universal tester manufactured by A & D Corporation.

<Evaluation of temperature rise>
Each sample processed into a sheet shape by the same method as in workability evaluation 2 is cut into 1.0 mm using a slitter, further processed into a 5.0 mm length using a foil cutter, and the temperature rise is measured. A sample (width 1.0 mm × length 5.0 mm × thickness 0.10 mm) was prepared. Both ends of each sample were connected to each electrode by resistance welding. Then, a current of 2.0 (A) was passed through the joined body, and the increased temperature was measured. The outside air temperature was controlled to be constant at 20 ° C.
The temperature rise of the sample 38 was taken as 100%, and the degree of temperature rise of other samples was relatively evaluated.

<Weather resistance evaluation>
A similar sample was manufactured by the method manufactured when evaluating the temperature rise, and used as a sample for weather resistance evaluation. That is, for each sample, a sample having a shape of width 1.0 mm × length 5.0 mm × thickness 0.10 mm was prepared. The constant temperature and humidity chamber containing these samples was subjected to an accelerated test at 85 ° C. and 85% RH-1000 hours. Compared with the initial thickness, the rate of increase in the thickness of the oxide film was evaluated as “◯” when less than 30%, “△” when 30% or more and less than 100%, and “×” when 100% or more. .

（注）表中の※を付した試料は比較例である。

(Note) Samples marked with * are comparative examples.

  As can be seen from Table 2 above, Samples 1 to 23 satisfying the requirements of the present invention show good characteristics in each evaluation item. In other words, disconnection and scratches do not occur at all even when processed into a wire shape, no burrs or cracks occur even when processed into a sheet shape, and defects are generated even when 1000 punched products are manufactured for each sample. All were good. Moreover, all the tensile strengths were as high as 100 MPa or more, the temperature rise was suppressed more than the sample 38 generally used, and the increase rate of the oxide film was suppressed also about the weather resistance, and the favorable result was shown. .

  On the other hand, the samples 24-38 which do not satisfy the requirements of the present invention are not preferable in most evaluation items. In other words, breakage and scratches frequently occur when processed into a wire shape, burrs and cracks occur even when processed into a sheet shape, and there are many defective products even when 1000 punched products are manufactured for each sample, The defective rate was 30 to 35%. All the tensile strengths were as low as 45 MPa or less. As for the weather resistance, the increase rate of the oxide film was very bad.

Claims (1)

Al is contained in an amount of 2% by mass to 8% by mass, Ge is contained in an amount of 0.001% by mass to 0.03% by mass, and the balance is made of Zn except for elements inevitably included in production. Pb-free Zn- Al alloy fuse.