Alloy wire for probe pin, method for producing the same, and probe pin made using alloy wire

Abstract

To provide an alloy wire for probe pins which has both low electrical resistivity and high hardness in a balanced manner, exhibits bending resistance, offers excellent machinability into probe pins and long service life as a probe pin, and does not decrease in strength even when exposed to high temperatures, as well as a method for producing the same, and a probe pin made using the alloy wire.SOLUTION: To solve this problem, an alloy wire for probe pins and a method for producing the alloy wire are adopted, the alloy wire containing 6.7 wt.% or more and 7.1 wt.% or less of Ag, 55.6 wt.% or more and 56.0 wt.% or less of Pd, 36.40 wt.% or more and 37.00 wt.% or less of Cu, 0.001 wt.% or more and 0.009 wt.% or less of Al, 0.05 wt.% or more and 0.20 wt.% or less of B, and 0.1 wt.% or more and 1.0 wt.% or less of Zn, with the balance being inevitable impurities.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an alloy wire for a probe pin used for semiconductor component inspection, a method for manufacturing the same, and a probe pin obtained using the alloy wire.

Background Art

[0002] Conventionally, a probe card and a contact probe are known as probes for electrical inspection of semiconductor components such as semiconductor integrated circuits and semiconductor packages having narrow pitch electrodes. A plurality of probe pins formed using an alloy wire having a small wire diameter (also referred to as a metal fine wire or an alloy fine wire) are used for these inspection probes. Further, an alloy wire having a small wire diameter such as that used for a probe pin is also used as a conductor material in electric wires and cables used in electronic devices such as mobile devices and industrial robots, and medical devices. Such an alloy wire for a probe pin, when used as a probe pin, repeatedly contacts the electrode of the component to be inspected with an appropriate load, and thus is required to have well-balanced performance such as low electrical resistance, high hardness, and bend resistance.

[0003] In response to such requirements for a probe pin material, Patent Document 1 discloses a probe pin material composed of Ag: 19 - 37 mass%, Pd: 39 - 50 mass%, Cu: 23 - 35 mass%, In: less than 0.1 - 1.0 mass%, Ga: 0.1 - 0.6 mass%, and B: 0.03 - 0.3 mass% as a probe pin material that can be processed such as bent even after aging treatment with high hardness. And in the examples, it is shown that the Vickers hardness after aging treatment of the probe pin material is 480 HV or more, and the maximum hardness after aging treatment that did not break during 90° bending is 350 HV or more.

[0004] In addition, Patent Document 2 discloses a probe pin material that can obtain wear resistance and oxidation resistance to maintain a low contact resistance of the probe pin. The probe pin material consists of Pd: 45-55 wt%, Cu: 32-42 wt%, Ag: 8-15 wt%, Re: 0.5-5 wt%, and one or more elements selected from Ru, Zr, Ga, and Zn with a total of 1.0 wt% or less, and impurities less than 1000 ppm. It has been shown that the electrical conductivity of the probe pin material exceeds 19.5% IACS, the Knoop hardness is 350 HK or more, and the yield strength at a high temperature of 480°F is 100 ksi.

[0005] In addition, Patent Document 3 discloses a probe pin material that is excellent in resistance value and hardness (wear resistance) and has improved bending resistance. The probe pin material consists of Ag, Pd, Cu, the first additive element B, at least one of the second additive elements Zn, Bi, and Sn, and inevitable impurities. It has been shown that the specific resistance of the probe pin material is 10 μΩ·cm or less, the Vickers hardness is 380 HV or more and 580 HV or less, and the number of bending times at a 90° angle is 5 or more.

[0006] Furthermore, Patent Document 4 discloses an alloy material for a probe pin that is excellent in conductivity and oxidation resistance, has high hardness, and is excellent in rollability and machinability. The composition is Ag: 20-30 wt%, Pd: 35-55 wt%, Cu: 20-40 wt%, and the additive added to this composition. The additive is a probe pin material selected from Au, Pt, Sn, Co, Cr, Zn, Ir, and Ru. It has been shown that the probe pin material is excellent in conductivity and oxidation resistance, has high hardness, is also excellent in rollability and machinability, and the Vickers hardness after aging treatment is in the range of 480 HV - 560 HV.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

[0008] However, in the invention described in Patent Document 1, regarding the samples prepared in the examples, the strength and lifespan after exposure to the actual environmental temperature when used as probe pins are not clarified, and there are concerns about whether these characteristics are sufficient. Also, in the invention described in Patent Document 2, regarding the alloy after aging treatment, the toughness is not clarified, and there are concerns about whether this characteristic is sufficient. Further, in the invention described in Patent Document 3, regarding the alloy prepared in the examples, the strength and lifespan after exposure to the actual environmental temperature when used as probe pins are not clarified, and there are concerns about whether these characteristics are sufficient. Additionally, in the invention described in Patent Document 4, regarding the alloy prepared in the examples, the strength and lifespan after exposure to the actual environmental temperature when used as probe pins are not clarified, and there are concerns about whether these characteristics are sufficient.

[0009] The present invention has been made in view of such circumstances. The object of the present invention is to provide an alloy wire for probe pins that has a well-balanced low electrical resistance and high hardness, has bending resistance, is excellent in workability for processing into probe pins and lifespan during use as a probe pin, and does not have a reduced strength even when exposed to high temperatures, a method for manufacturing the same, and a probe pin obtained using the alloy wire. [Means for Solving the Problems]

[0010] As a result of intensive research to solve the above-described problems, the inventors have conceived of the following alloy wire for probe pins, a method for manufacturing the same, and a probe pin obtained using the alloy wire.

[0011] The alloy wire for probe pins according to the present invention employs an alloy wire for probe pins characterized by containing 6.7 wt% or more and 7.1 wt% or less of Ag, 55.6 wt% or more and 56.0 wt% or less of Pd, 36.40 wt% or more and 37.00 wt% or less of Cu, 0.001 wt% or more and 0.009 wt% or less of Al, 0.05 wt% or more and 0.20 wt% or less of B, and 0.1 wt% or more and 1.0 wt% or less of Zn, with the balance consisting of inevitable impurities.

[0012] The alloy wire for probe pins according to the present invention preferably has a Vickers hardness of 480 HV or more and 580 HV or less.

[0013] The alloy wire for probe pins according to the present invention preferably has a specific resistance of 8 μΩ·cm or less.

[0014] The alloy wire for probe pins according to the present invention preferably has 20 or more 90° bending times.

[0015] The alloy wire for probe pins according to the present invention preferably has a wire diameter of 1.0 mm or less.

[0016] The alloy wire for probe pins according to the present invention preferably has a Vickers hardness of 455 HV or more after heat treatment at a temperature of 450 °C for 1 hour.

[0017] The manufacturing method of the alloy wire for probe pins according to the present invention is the manufacturing method of the alloy wire for probe pins as described above, and employs a manufacturing method of the alloy wire for probe pins characterized by comprising the following steps 1 to 3. Process 1: A metal material containing Ag, Pd, Cu, Al, B, and Zn is heated and melted in a vacuum, an inert gas atmosphere, or a slightly reducing atmosphere to obtain an ingot containing 6.7 wt% or more and 7.1 wt% or less of Ag, 55.6 wt% or more and 56.0 wt% or less of Pd, 36.40 wt% or more and 37.00 wt% or less of Cu, 0.001 wt% or more and 0.009 wt% or less of Al, 0.05 wt% or more and 0.20 wt% or less of B, and 0.1 wt% or more and 1.0 wt% or less of Zn, with the balance being unavoidable impurities. Process 2: The ingot is repeatedly subjected to cold working with a cross-sectional reduction rate of 50% or more and solution treatment in an inert gas atmosphere or a slightly reducing atmosphere to obtain an alloy wire for a probe pin before aging treatment with a wire diameter of 1.0 mm or less. Process 3: The alloy wire for a probe pin before aging treatment is subjected to aging treatment in an inert gas atmosphere or a slightly reducing atmosphere to obtain an alloy wire for a probe pin that has been aged.

[0018] The probe pin according to the present invention employs a probe pin characterized by being obtained using the above-described alloy wire for a probe pin.

Effects of the Invention

[0019] According to the present invention, it is possible to provide an alloy wire for a probe pin that has a well-balanced low electrical resistance and high hardness, has excellent bend resistance, workability for processing into a probe pin, and service life when used as a probe pin, and does not have a decrease in strength even when exposed to high temperatures, a method for manufacturing the same, and a probe pin obtained using the alloy wire.

Brief Description of the Drawings

[0020]

Figure 1

Embodiments for Carrying Out the Invention

[0021] Hereinafter, embodiments of the alloy wire for probe pins according to the present invention, a method for manufacturing the same, and probe pins obtained using the alloy wire will be described. Note that what is described below merely shows one aspect and is not to be construed as being limited to the following description.

[0022] 1. Alloy wire for probe pins The alloy wire for probe pins according to the present invention contains 6.7 wt% or more and 7.1 wt% or less of Ag, 55.6 wt% or more and 56.0 wt% or less of Pd, 36.40 wt% or more and 37.00 wt% or less of Cu, 0.001 wt% or more and 0.009 wt% or less of Al, 0.05 wt% or more and 0.20 wt% or less of B, and 0.1 wt% or more and 1.0 wt% or less of Zn. And the total of each composition described above is 100 wt%. However, the alloy wire for probe pins according to the present invention may contain inevitable impurities. When inevitable impurities are contained, the total of all the above metal composition components and the inevitable impurities is 100 wt%. The alloy wire for probe pins adopting this composition has a well-balanced combination of low electrical resistance and high hardness, has bending resistance, is excellent in workability into probe pins and the lifespan during use as probe pins, and does not have a decrease in strength even when exposed to high temperatures.

[0023] The main components of the composition of the alloy wire for probe pins are Ag (silver), Pd (palladium), and Cu (copper). Since Cu has low electrical resistance but low hardness, Ag and Pd are added to achieve both high hardness and low resistance. At this time, in order to achieve bending resistance in addition to high hardness and low resistance, the suitable composition range is 6.7 wt% or more and 7.1 wt% or less of Ag, 55.6 wt% or more and 56.0 wt% or less of Pd, and 36.40 wt% or more and 37.00 wt% or less of Cu.

[0024] The first component added to the above Ag, Pd, and Cu is Al (aluminum). Al has the effect of promoting the formation of PdCu regular phases, which are the age hardening factors of Ag-Pd-Cu alloys, inside the grains. The preferred addition composition ratio is 0.001 wt% or more and 0.009 wt% or less. If the addition ratio is less than 0.001 wt%, the above-mentioned effects cannot be obtained. Also, if the addition ratio exceeds 0.009 wt%, the precipitation of intermetallic compounds is rather inhibited, the effect of improving hardness cannot be obtained, and the fluidity of molten metal decreases, resulting in a decrease in casting workability.

[0025] The second component added to the above Ag, Pd, and Cu is B (boron). By adding B to the Ag-Pd-Cu alloy, the hardness can be improved and the bending resistance can also be improved. The preferred addition composition ratio is 0.05 wt% or more and 0.20 wt% or less. If the addition ratio is less than 0.05 wt%, the above-mentioned effects cannot be obtained. Also, if the addition ratio exceeds 0.20 wt%, the plastic workability is significantly reduced and the precipitation of intermetallic compounds is inhibited.

[0026] The third component added to the above Ag, Pd, and Cu is Zn (zinc). Zn forms PdCu regular phases, which are the age hardening factors of Ag-Pd-Cu alloys, and intermetallic compounds to strengthen the grain boundaries. As a result, the hardness is improved and the effect of improving wear resistance is obtained. The preferred addition composition ratio is 0.1 wt% or more and 1.0 wt% or less. If the addition ratio is less than 1.0 wt%, the above-mentioned effects cannot be obtained. If the addition ratio exceeds 1.0 wt%, the plastic workability decreases, making cold working difficult.

[0027] By adopting an alloy wire for a probe pin containing Ag, Pd, Cu, Al, B, and Zn within the above-described ranges and the balance consisting of inevitable impurities, it has a well-balanced low electrical resistance and high hardness, and also has bending resistance. As a result, it has excellent workability for processing into a probe pin and a long service life when used as a probe pin. Furthermore, its strength does not decrease even when exposed to high temperatures. Here, the inevitable impurities are not particularly limited, but may include Au (gold), Bi (bismuth), Ca (calcium), Fe (iron), Pt (platinum), Ir (iridium), Mg (magnesium), Mn (manganese), Ru (ruthenium), Rh (rhodium), Sb (antimony), Si (silicon), Sn (tin), Ti (titanium), Zr (zirconium), etc. And the total content of these inevitable impurities is preferably 0.02 wt% or less. This is because it does not affect the excellent characteristics of the alloy wire for a probe pin according to the present invention. When inevitable impurities are contained, the total of all the above-described metal composition components and the inevitable impurities is 100 wt%.

[0028] 〔Vickers hardness〕 The Vickers hardness of the alloy wire for a probe pin according to the present invention is preferably 480 HV or more and 580 HV or less. If the Vickers hardness is less than 480 HV, it is difficult to achieve a Vickers hardness of 455 HV or more after heat treatment at a temperature of 450 °C for 1 hour. Also, if the Vickers hardness exceeds 580 HV, although it is possible to achieve a Vickers hardness of 455 HV or more after heat treatment at a temperature of 450 °C for 1 hour, the number of 90° bending times of 20 or more becomes difficult to achieve.

[0029] 〔Specific resistance〕 The specific resistance (also referred to as electrical resistivity) of the alloy wire for probe pins according to the present invention is preferably 8 μΩ·cm or less. The alloy wire for probe pins is used as a probe pin for electrical inspection of semiconductor components and the like as described above. That is, if the specific resistance exceeds 8 μΩ·cm, the voltage drop due to the current flowing through the probe pin during electrical inspection becomes large, resulting in a large measurement error. On the other hand, although there is no particular limitation on the lower limit of the specific resistance, although the bend resistance is improved by reducing the specific resistance, the hardness decreases. Therefore, the specific resistance of the alloy wire for probe pins according to the present invention is preferably 5 μΩ·cm or more.

[0030] 〔Number of 90° bends〕 The number of 90° bends in the 90° bending test of the alloy wire for probe pins according to the present invention is preferably 20 or more. This is because it not only has excellent workability but can also be suitably used for cantilever-type probe pins and the like. The 90° bending test is a test in which a straight alloy wire for probe pins is alternately repeated with a first step of bending it at an angle of approximately 90° and a second step of bending it back to a straight state from the state bent at approximately 90°. And, each of the first step and the second step is defined as one bending number, and the total number until the wire breaks is defined as the number of 90° bends. If the number of 90° bends is less than 20, not only is the workability inferior, but also the durability is inferior when used as, for example, a cantilever-type probe pin. On the other hand, although there is no particular limitation on the upper limit of the number of 90° bends, since the hardness decreases by increasing the number of 90° bends, the number of 90° bends of the alloy wire for probe pins according to the present invention is preferably 40 or less.

[0031] 〔Wire diameter〕 The wire diameter of the alloy wire for probe pins according to the present invention is preferably 1.0 mm or less. If the wire diameter exceeds 1.0 mm, the applications as probe pins for electrical inspection such as probe cards and contact probes are extremely limited, and the added value as an alloy wire tends to decrease, which is not preferable.

[0032] 〔Vickers hardness after heat treatment〕 The alloy wire for probe pins according to the present invention preferably has a Vickers hardness of 455 HV or more after heat treatment at a temperature of 450 °C for 1 hour. When inspecting semiconductor components or the like using an electrical inspection probe, the electrical inspection probe may be exposed to high temperatures due to screening tests or characteristic tests at high temperatures, or heat generation caused by the current passed through. If the hardness of the electrical inspection probe decreases due to exposure to a high-temperature environment, problems such as a decrease in the contact load of the probe with the electrode of the object to be measured and insufficient contact may occur. In addition, when the hardness decreases, the contact portion of the electrical inspection probe with the electrode is likely to wear during contact between the electrical inspection probe and the electrode, and the life of the electrical inspection probe may decrease. On the other hand, there is no particular limitation on the upper limit of the Vickers hardness after heat treatment at a temperature of 450 °C for 1 hour. However, when the Vickers hardness after heat treatment at a temperature of 450 °C for 1 hour is a high value, it means that the Vickers hardness of the alloy wire for probe pins before the heat treatment is a high value, and when the Vickers hardness of the alloy wire for probe pins before the heat treatment is a high value, the number of 90° bending times tends to decrease. Therefore, the Vickers hardness after heat treatment at a temperature of 450 °C for 1 hour is preferably 550 HV or less.

[0033] 〔Method for measuring composition〕 The method for measuring the composition of the alloy wire for probe pins is not particularly limited, but it can be carried out using an ICP (inductively coupled plasma) emission spectrometer, XRF (X-ray fluorescence) analysis, etc. In addition, measurement can also be performed using analytical methods such as EDX (energy dispersive X-ray) analysis and WDX (wavelength dispersive X-ray) analysis.

[0034] 2. Manufacturing method of alloy wire for probe pins The manufacturing method of the alloy wire for probe pins according to the present invention is the above-described manufacturing method of the alloy wire for probe pins, and includes the following steps 1 to 3. By adopting this manufacturing method, an alloy wire for probe pins can be manufactured that has a well-balanced low electrical resistance and high hardness, has excellent bend resistance, workability for processing into probe pins, and service life during use as a probe pin, and does not have its strength reduced even when exposed to high temperatures. Step 1: A metal material containing Ag, Pd, Cu, Al, B, and Zn is heated and melted in a vacuum, an inert gas atmosphere, or a slightly reducing atmosphere to obtain an ingot containing 6.7 wt% or more and 7.1 wt% or less of Ag, 55.6 wt% or more and 56.0 wt% or less of Pd, 36.40 wt% or more and 37.00 wt% or less of Cu, 0.001 wt% or more and 0.009 wt% or less of Al, 0.05 wt% or more and 0.20 wt% or less of B, and 0.1 wt% or more and 1.0 wt% or less of Zn, with the balance being unavoidable impurities. Step 2: The ingot is repeatedly subjected to cold working with a cross-sectional reduction rate of 50% or more and solution treatment in an inert gas atmosphere or a slightly reducing atmosphere to obtain an alloy wire before aging treatment with a wire diameter of 1.0 mm or less. Step 3: The alloy wire before aging treatment is subjected to aging treatment in an inert gas atmosphere or a slightly reducing atmosphere to obtain an alloy wire for probe pins that has been subjected to aging treatment.

[0035] 〔Step 1〕 Step 1 is a process of manufacturing an ingot that serves as a raw material for obtaining an alloy wire for probe pins having a predetermined composition using casting technology. Specifically, a metal material containing Ag, Pd, Cu, Al, B, and Zn is placed in a heat-resistant container and heated and melted in a vacuum, an inert gas atmosphere such as nitrogen or argon, or a slightly reducing atmosphere, and the melted metal material is poured into a mold to obtain an ingot containing 6.7 wt% or more and 7.1 wt% or less of Ag, 55.6 wt% or more and 56.0 wt% or less of Pd, 36.40 wt% or more and 37.00 wt% or less of Cu, 0.001 wt% or more and 0.009 wt% or less of Al, 0.05 wt% or more and 0.20 wt% or less of B, and 0.1 wt% or more and 1.0 wt% or less of Zn, with the balance consisting of inevitable impurities. Note that as long as the ingot of Step 1 can be obtained, it is not limited to the above method, and for example, an ingot may be obtained using any melting and casting method such as a continuous casting method.

[0036] Here, if the content of Al exceeds 0.01 wt%, the fluidity of the molten metal decreases and the casting processability deteriorates, which is not preferable. If the content of B exceeds 0.20 wt%, the plastic workability significantly decreases, making the cold working described later difficult, which is not preferable. Also, if the content of Zn exceeds 1.0 wt%, the plastic workability decreases and the cold working becomes difficult, which is not preferable.

[0037] As the manufacturing conditions for the heating and melting in this Step 1, conventionally known ones may be used. For example, the melting temperature may be 1500°C to 1700°C, and the degree of vacuum may be 1×10 3 Pa to 1×10 -3 Pa. However, as long as the metal material can be heated and melted, it is not limited to the above conditions. Note that the slightly reducing atmosphere is a gas in which a reducing gas such as hydrogen or carbon monoxide is mixed with an inert gas in a trace amount. For example, a gas mixed at a ratio of 95% nitrogen and 5% hydrogen can be used.

[0038] 〔Step 2〕 Step 2 is a step of manufacturing an alloy wire before aging treatment with a wire diameter of 1.0 mm or less by repeatedly performing cold working with a cross-sectional area reduction rate of 50% or more and solution treatment in an inert gas atmosphere or a slightly reducing atmosphere on the ingot obtained in Step 1. Here, the cold working step is a step of shaping the ingot into a desired shape and dimensions and introducing a large compressive stress into the alloy to improve the strength and hardness. Specifically, in an environment near room temperature, using a grooved roll rolling machine, a wire drawing device, etc., the ingot obtained in Step 1 is processed so that the cross-sectional area reduction rate is 50% or more. Here, the cross-sectional area reduction rate is calculated as (cross-sectional area before processing - cross-sectional area after processing) / cross-sectional area before processing × 100%. If the cross-sectional area reduction rate is less than 50%, it is not preferable because the improvement in hardness by cold working tends not to be sufficiently obtained. On the other hand, although there is no particular limit to the upper limit of the cross-sectional area reduction rate, it tends to be difficult to process and further improvement in hardness cannot be expected, so the cross-sectional area reduction rate is preferably 99.99% or less.

[0039] Next, the solution treatment step is a step of heating and holding the alloy to be processed at an appropriate temperature to dissolve (solid-solve) the metal atoms in the alloy to be processed in the solid and rapidly cooling without precipitating precipitates. As the conditions for this solution treatment, conventionally known ones may be used. For example, the alloy to be processed is placed in a heat-resistant container and heat-treated at 700°C to 900°C for about 1 hour to 3 hours in an inert gas atmosphere such as nitrogen or argon or a slightly reducing atmosphere, and then rapidly cooled as it is. The method of rapid cooling is not particularly limited, but a water cooling method, an oil cooling method, a cooling method using an inert gas, etc. can be used.

[0040] By repeatedly performing the above-described cold working and solution treatment on the ingot obtained in Step 1, an alloy wire before aging treatment with a wire diameter of 1.0 mm or less can be obtained.

[0041] 〔Step 3〕 Step 3 is a step of performing aging treatment on the alloy wire before aging treatment obtained in Step 2 in an inert gas atmosphere or a slightly reducing atmosphere to produce an alloy wire for a probe pin that has been subjected to aging treatment. Aging refers to the change in mechanical properties such as hardness over time, and aging treatment is a treatment that applies temperature to accelerate the transformation over time. In Step 3, aging treatment is performed on the alloy wire before aging treatment obtained in Step 2 to precipitate a PdCu regular phase or an intermetallic compound of a PdCu regular phase and Zn in the Pd matrix phase, thereby improving the hardness. As the conditions for the aging treatment, those known in the art may be employed. For example, the alloy wire before aging treatment obtained in Step 2 is placed in a heat-resistant container and heat-treated at 350°C to 550°C for about 1 hour to 20 hours in an inert gas atmosphere such as nitrogen or argon, and then allowed to cool naturally.

[0042] 〔Other steps〕 In addition, the method for manufacturing an alloy wire for a probe pin according to the present invention may include another step in addition to the above-described Steps 1 to 3 as long as the above-described alloy wire for a probe pin can be manufactured. For example, it is preferable to cut and remove a predetermined amount from the surface of the ingot using a shaper between Step 1 and Step 2. This is because the oxide film on the surface of the ingot manufactured in Step 1 and inclusions such as alumina and silica buried in the ingot surface can be removed, thereby increasing the compositional purity of the ingot.

[0043] 3. Probe pin The probe pin according to the present invention is formed using the above-described alloy wire for a probe pin. Since the probe pin according to the present invention is obtained using the above-described alloy wire for a probe pin, it has the excellent properties of the alloy wire for a probe pin according to the present invention, and has a well-balanced low electrical resistance and high hardness, excellent service life when used as a probe pin, and does not decrease in strength even when exposed to high temperatures. That is, it can be suitably used as an electrical inspection probe for semiconductor components and the like.

[0044] The embodiments of the present invention described above are one aspect of the present invention and can be appropriately modified without departing from the gist of the present invention. Further, the present invention will be described more specifically with reference to the following examples, but the present invention is not limited to the following examples.

Example

[0045] As Step 1, the following steps were performed. A metal material containing Ag, Pd, Cu, Al, B, and Zn was placed in a carbon crucible and melted at 1600 °C in a vacuum of 1 × 10 -3 Pa. Then, the melted metal material was poured into a mold to obtain an ingot with a shape of 20 mm × 20 mm × 150 mm, where Ag was 6.90 wt%, Pd was 55.80 wt%, Cu was 36.714 wt%, Al was 0.006 wt%, B was 0.08 wt%, Zn was 0.50 wt%, and the total of each composition was 100 wt%. At this time, the alloy composition of the ingot was measured using an ICP emission spectrometer. Note that the above composition does not prevent the possibility of containing inevitable impurities buried in the measurement accuracy.

[0046] Next, before Step 2, the surface of the ingot obtained in Step 1 was cut and removed to a thickness of 1 mm using a shaper. By doing this, the oxide film on the surface of the ingot obtained in Step 1 and inclusions such as alumina and silica buried in the ingot surface were removed.

[0047] Next, as Step 2, the following steps were performed on the ingot whose surface had been cut and removed to a thickness of 1 mm using a shaper. Cold working with a cross-sectional reduction rate of 50% or more using a groove roll rolling machine and a wire drawing device at room temperature of 25 °C, and a solution treatment of holding in a nitrogen atmosphere at 800 °C for 1 hour and then rapidly cooling were repeated to obtain an alloy wire with a wire diameter of 3 mm. Then, cold working and solution treatment using a wire drawing device under the same conditions as above were repeated on the alloy wire with a wire diameter of 3 mm to obtain an alloy wire before aging treatment with a wire diameter of 0.1 mm.

[0048] Next, as Step 3, the pre-aging alloy wire obtained in Step 2 was subjected to an aging treatment of holding for 1 hour in a slightly reducing atmosphere at 400°C mixed at a ratio of 95% nitrogen and 5% hydrogen to obtain the alloy wire for probe pins of Example 1.

Example

[0049] As Step 1, the following steps were performed. A metal material containing Ag, Pd, Cu, Al, B, and Zn was put into a carbon crucible and melted at 1600°C in a vacuum of 1×10 -3 Pa. Then, the melted metal material was poured into a mold to obtain an ingot with a shape of 20 mm × 20 mm × 150 mm, where Ag was 6.90 wt%, Pd was 55.80 wt%, Cu was 36.644 wt%, Al was 0.006 wt%, B was 0.15 wt%, Zn was 0.50 wt%, and the total of each composition was 100 wt%. At this time, the alloy composition of the ingot was measured using an ICP (Inductively Coupled Plasma) optical emission spectrometer. Note that the above composition does not prevent the possibility of containing inevitable impurities buried in the measurement accuracy.

[0050] In the subsequent steps, the same steps as in Example 1 were carried out to obtain the alloy wire for probe pins of Example 2. Comparative Example

[0051] 〔Comparative Example 1〕 As Step 1, the following steps were performed. A metal material containing Ag, Pd, Cu, B, and Zn was put into a carbon crucible and melted at 1600°C in a vacuum of 1×10 -3 Pa. Then, the melted metal material was poured into a mold to obtain an ingot with a shape of 20 mm × 20 mm × 150 mm, where Ag was 6.90 wt%, Pd was 55.80 wt%, Cu was 36.72 wt%, B was 0.08 wt%, Zn was 0.50 wt%, and the total of each composition was 100 wt%. At this time, the alloy composition of the ingot was measured using an ICP (Inductively Coupled Plasma) optical emission spectrometer. Note that the above composition does not prevent the possibility of containing inevitable impurities buried in the measurement accuracy.

[0052] In the subsequent steps, the same steps as in Example 1 were carried out to obtain the alloy wire for the probe pin of the comparative example.

[0053] 〔Comparative Example 2〕 As Step 1, the following steps were performed. A metal material containing Ag, Pd, Cu, Al, B, and Zn was put into a carbon crucible and melted at 1600 °C in a vacuum of 1×10 -3 Pa. However, the melted metal material had a reduced fluidity, making it difficult to pour it into a mold and cast it into an ingot with a shape of 20 mm × 20 mm × 150 mm. The alloy obtained from the melted metal material had Ag at 6.90 wt%, Pd at 55.80 wt%, Cu at 36.710 wt%, Al at 0.010 wt%, B at 0.08 wt%, and Zn at 0.50 wt%, and the total of each composition was 100 wt%. At this time, the composition of the alloy obtained from the melted metal material was measured using an ICP (Inductively Coupled Plasma) emission spectrometer. Note that the above composition does not prevent the possibility of containing inevitable impurities buried in the measurement accuracy.

[0054] Since an ingot with a shape of 20 mm × 20 mm × 150 mm could not be obtained in Step 1, Steps 2 and 3 were not carried out, and an alloy wire for the probe pin could not be obtained.

[0055] Table 1 shows the compositions of the alloy wires for the probe pins prepared in Example 1, Example 2, and Comparative Example 1, and the composition of the alloy obtained from the melted metal material of Comparative Example 2.

[0056]

Table 1

[0057] 〔Evaluation〕 1. Relationship between the aging treatment temperature and the Vickers hardness For Example 1, Example 2, and Comparative Example 1, alloy wires for probe pins that were subjected to aging treatment (holding time was 1 hour each) under temperature conditions other than 400°C (375°C, 410°C, 425°C, 450°C) were also prepared, and the results of measuring the Vickers hardness at room temperature are shown in Fig. 1. Note that the Vickers hardness at the position where the aging treatment temperature is zero indicates the value of the alloy wire before aging treatment without aging treatment. From Fig. 1, when comparing Example 1 with Al added and Comparative Example 1, although the Vickers hardness of the alloy wire before aging treatment in Example 1 is slightly inferior to that in Comparative Example 1, it is clear that the hardness of the alloy wire for probe pins in Example 1 is significantly improved by performing the aging treatment. This is presumably because the addition of Al promoted the formation of intragranular PdCu regular phases. Also, when comparing Example 1 and Example 2, it became clear that the hardness of the alloy wire for probe pins in Example 2 was improved. This is presumably because by increasing the addition amount of B, the effect of grain boundary strengthening was enhanced and the hardness was improved dramatically.

[0058] Note that Comparative Example 2 with 0.010 wt% Al added had a reduced flowability of the molten metal and was difficult to pour into a mold and cast into an ingot, so it was not suitable for alloy wires for probe pins and was excluded from this evaluation and subsequent evaluations.

[0059] 2. Evaluation of Various Properties Table 2 shows the results of measuring the specific resistance, the number of 90° bends, and the Vickers hardness at room temperature after heat treatment at 450°C for 1 hour simulating a semiconductor inspection environment for the alloy wires for probe pins prepared in Example 1, Example 2, and Comparative Example 1. Note that in the Vickers hardness in Table 2, "without heat treatment" represents the hardness of the alloy wires for probe pins prepared in Example 1, Example 2, and Comparative Example 1, and "after heat treatment at 450°C for 1 hour" represents the hardness after heat treatment at 450°C for 1 hour for the alloy wires for probe pins prepared in Example 1, Example 2, and Comparative Example 1.

[0060]

Table 2

[0061] From Table 2, it was revealed that the alloy wire for probe pins fabricated in Example 1 and Example 2 had a Vickers hardness of 455 HV or more even after heat treatment at a temperature of 450°C for 1 hour. This is presumably because the addition of Al promoted the formation of intragranular PdCu regular phases and improved the hardness. Regarding the number of 90° bends, it was clarified that the alloy wire for probe pins fabricated in Example 1 and Example 2 both had good values of 20 or more, indicating excellent hardness and bendability. On the other hand, it was revealed that the number of 90° bends in Comparative Example 1 was less than 20, with inferior hardness and bendability. Regarding the specific resistance, all of Example 1, Example 2, and Comparative Example 1 had good values of 8 μΩ·cm or less.

Industrial Applicability

[0062] The alloy wire for probe pins according to the present invention has a well-balanced combination of low electrical resistance and high hardness, and also has bend resistance, excellent workability for probe pins, and long life during use as a probe pin. Since its strength does not decrease even when exposed to high temperatures, it is suitable as an alloy wire for probe pins for electrical inspection. The manufacturing method of the alloy wire for probe pins according to the present invention is suitable as a method for manufacturing the alloy wire for probe pins according to the present invention. Furthermore, since the probe pin according to the present invention is obtained using the alloy wire for probe pins according to the present invention, it has a well-balanced combination of low electrical resistance and high hardness, and also has bend resistance, excellent life during use as a probe pin. Since its strength does not decrease even when exposed to high temperatures, it is suitable as a probe for electrical inspection.

Claims

1. An alloy wire for a probe pin, comprising 6.7 wt% or more and 7.1 wt% or less of Ag, 55.6 wt% or more and 56.0 wt% or less of Pd, 36.40 wt% or more and 37.00 wt% or less of Cu, 0.001 wt% or more and 0.009 wt% or less of Al, 0.05 wt% or more and 0.20 wt% or less of B, and 0.1 wt% or more and 1.0 wt% or less of Zn, with the balance consisting of unavoidable impurities.

2. The alloy wire for a probe pin according to Claim 1, having a Vickers hardness of 480 HV or more and 580 HV or less.

3. The alloy wire for a probe pin according to Claim 1, having a specific resistance of 8 μΩ·cm or less.

4. The alloy wire for a probe pin according to Claim 1, having a number of 90° bending times of 20 or more.

5. The alloy wire for a probe pin according to Claim 1, having a wire diameter of 1.0 mm or less.

6. The alloy wire for a probe pin according to Claim 1, having a Vickers hardness of 455 HV or more after heat treatment at a temperature of 450 °C for 1 hour.

7. A method for manufacturing an alloy wire for a probe pin according to Claim 1, characterized by comprising the following steps 1 - 3. Step 1: A metal material containing Ag, Pd, Cu, Al, B, and Zn is heated and melted in a vacuum, an inert gas atmosphere, or a slightly reducing atmosphere to obtain an ingot containing 6.7 wt% or more and 7.1 wt% or less of Ag, 55.6 wt% or more and 56.0 wt% or less of Pd, 36.40 wt% or more and 37.00 wt% or less of Cu, 0.001 wt% or more and 0.009 wt% or less of Al, 0.05 wt% or more and 0.20 wt% or less of B, and 0.1 wt% or more and 1.0 wt% or less of Zn, with the balance consisting of unavoidable impurities. Step 2: The ingot is repeatedly subjected to cold working with a cross-sectional reduction rate of 50% or more and solution treatment in an inert gas atmosphere or a slightly reducing atmosphere to obtain an alloy wire before aging treatment with a wire diameter of 1.0 mm or less. Step 3: The alloy wire before aging treatment is subjected to aging treatment in an inert gas atmosphere or a slightly reducing atmosphere to obtain an alloy wire for a probe pin that has been subjected to aging treatment.

8. A probe pin, characterized by being obtained using the alloy wire for a probe pin according to Claim 1.

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