JP2016109446A - PROBE PIN MADE OF Rh-BASED ALLOY AND MANUFACTURING METHOD THEREOF - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a probe pin made of a Rh-based alloy which is hardly cracked.SOLUTION: The probe pin is made of a material which contains 99.92 to 99.30 mass% of a Rh-based alloy, 0.08 to 0.70 mass% of Zr and inevitable impurities in the total 100 mass%, whose aspect ratio (a ratio of length to width of a crystal grain, crystal grain length/crystal grain width) is 4 or more, and whose Vickers hardness is 350 or more. The Vickers hardness of the probe pin becomes 350 or more by performing rolling processing or/and wire drawing processing at a rolling rate or a cross section reduction rate of 60% or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a probe pin (hereinafter abbreviated as “probe pin”) incorporated in a probe card for inspecting electrical characteristics of an integrated circuit or the like on a semiconductor wafer and a method for manufacturing the same.

  A probe card in which a plurality of probe pins are incorporated is used for inspection of electrical characteristics of an integrated circuit or the like formed on a semiconductor wafer. This inspection is performed by bringing a probe pin incorporated in a probe card into contact with an electrode, a terminal, or a conductive portion of an integrated circuit or the like.

  Such a probe pin is not only highly conductive, but also requires corrosion resistance and oxidation resistance in order to obtain a stable inspection result, and is required to have sufficient strength because it is repeatedly brought into contact with an inspection object. The strength is required because it is necessary to reduce wear caused by contacting the probe pin with the test object tens of thousands of times.

JP 10-38922 JP 10-221366 JP-A-11-94872 JP2000-137042 JP2005-233967 Patent 4874401 Patent No. 5074608

At present, beryllium copper, phosphor bronze, and tungsten are used for probe pins as shown in Patent Document 1 and Patent Document 2, for example.
Probe pins using beryllium copper, phosphor bronze, or tungsten are inferior in oxidation resistance, and when used, an oxide film is formed on the surface, and the oxide adheres to the object to be inspected as inspection continues. However, there is a problem that poor conduction occurs.

In order to prevent such a defect due to the formation of an oxide film of the probe pin, a palladium alloy or a platinum alloy may be used as in Patent Document 3, Patent Document 4, Patent Document 5, and Patent Document 6.
Among these, the probe pin using the palladium alloy improves the hardness by improving the hardness by work hardening, improving the hardness by precipitation hardening, or both. Moreover, platinum alloy improves hardness by solid solution hardening and work hardening.

  Among them, the ratio of power semiconductors among semiconductors to be inspected with probe cards is gradually increasing.

  Power semiconductors are used in inverter circuits and the like, and are often exposed to higher temperatures than ordinary semiconductors due to the usage environment and usage. Along with this, inspections at high temperatures are also required. In the conventional semiconductor, the inspection temperature of the Si wafer hardly exceeds 100 ° C., but in the case of the power semiconductor, it may exceed 100 ° C.

  Furthermore, when the wafer used is SiC or GaN, the inspection is performed at 200 ° C. or higher, and the flowing current tends to increase. For this reason, the temperature applied to the probe pin is sometimes increased to 300 ° C. or more by resistance heating in addition to the test temperature.

  Tungsten, beryllium copper, etc. are used for inspections at such test temperatures, but because they are more susceptible to oxidation than the normal temperature range, inspection defects are likely to occur, and platinum alloys and palladium alloys The rate at which is used is increasing.

  However, platinum alloys and palladium alloys also have problems, and in the case of platinum alloys, the resistance is larger than other materials, so the probe pin temperature rises easily due to resistance heating, in the case of palladium alloys, it approaches the aging temperature, In addition, since the inspection is performed at the aging temperature, there is a concern that the aging of the probe pin progresses and becomes brittle and easily breaks.

  Among these metals, Rh having a low specific resistance and oxidation resistance has attracted attention.

  As in Patent Document 7, a rhodium alloy patent has been issued as a probe pin having low resistance and antifouling properties.

  Patent Document 7 discloses a patent in which Fe, Ir, and Re are added in a very small amount of about several hundred ppm in order to improve low resistance and antifouling properties while ensuring processability.

  As a characteristic of Rh, there is a characteristic that work hardening ability is very high. For this reason, strong processing is not performed, and a crystal grain becomes a coarse structure. Also, the grain boundary strength is weak and processing by hot working etc. is easier than iridium, but when bending stress is applied to work-hardened material, cracks enter the surface starting from the grain boundary, and in some cases bending stress is applied Break at a point. When used as a probe pin, bending after wire drawing is usually performed in many cases, and even if bending is performed, there is no breakage such as breakage and there is a demand for minimal surface cracks. Yes.

  In view of the above-described problems of the prior art, an object of the present invention is to provide a probe pin that is unlikely to crack and a method for manufacturing the probe pin.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors processed an alloy containing a small amount of Zr in Rh at a processing rate of 60% or less after heat treatment at a predetermined temperature, or a predetermined amount. By heating at a temperature and processing at a processing rate of 60% or less, the Vickers hardness is set to 350 or more, and at the same time, the aspect ratio (the ratio of the length to the crystal grain width, crystal grain length / grain width, below) It has been found that by setting the aspect ratio to 4 or more, it is possible to obtain a probe pin that is less prone to cracks starting from grain boundaries on the surface, and the present invention has been completed. Here, the processing rate is a general term for a rolling rate and / or a cross-sectional reduction rate.

  That is, the above object is an Rh-based alloy of 99.92 to 99.30 mass%, Zr is 0.08 to 0.70 mass% and an alloy consisting of 100 mass% in total with inevitable impurities, rolling ratio [rolling ratio (%) = ( (Thickness before rolling-thickness after rolling) / thickness before rolling) × 100] or cross-sectional reduction rate [cross-sectional reduction rate (%) = ((area before wire drawing-after wire drawing) Area) / area before wire drawing) × 100]] after rolling or rolling and / or wire drawing at 60% or less, then aspect ratio (ratio of length to crystal grain width, crystal grain length) This is achieved by a probe pin made of a material having a thickness / grain width) of 4 or more and a Vickers hardness of 350 or more.

  The object is to produce a probe pin, characterized in that the material used for the probe pin is heat-treated at 700 ° C. or higher before processing, and then rolled or / and drawn at a rolling rate or cross-section reduction rate of 60% or less. Achieved by:

  Further, the above object is characterized in that the material used for the probe pin is rolled or / and drawn after being heated at a rolling rate or cross-sectional reduction rate of 60% or less and in a temperature range of 700 to 1100 ° C. This is achieved by a probe pin manufacturing method.

  According to the present invention, it is possible to provide a probe pin that is unlikely to crack and a method for manufacturing the probe pin.

Organizational photograph of Example 1-3 Structural photograph of Comparative Example 1-1 Structural photograph of Comparative Example 1-3 SEM observation result of Comparative Example 1-1

(Probe pin)
Since the probe pin needs to be processed into a predetermined shape in order to be incorporated into the probe card, it is necessary to suppress defects such as cracks on the surface when the probe pin is bent at least 90 °.
Rh is a material that has a high work-hardening ability, and therefore has a large increase in hardness even at a low processing rate, and is hard to be hard-worked. For this reason, even if the processing is performed, the crystal grains remain coarse and cracks are easily generated from the grain boundaries.

  In the present invention, a predetermined amount of Zr is added to suppress cracks on the surface during wire processing and probe pin processing, and breakage of the wire and the probe pin, so that the aspect ratio is 4 or more even at a low processing rate. Thus, it was found that surface cracks, strands, and probe pin breakage were suppressed.

  Further, the present invention has found that cracks on the surface and breakage from bent portions can be suppressed by setting the processing rate to 60% or less, preferably 3 to 50%.

  The probe pin of the present invention is made of an alloy composed of 0.08 to 0.7 mass% Zr and the balance of Rh and inevitable impurities. A more preferable composition is that Zr is 0.1 to 0.6 mass% and the balance is Rh, so that the aspect ratio can be increased, and further, since it is used in a processed material, it suppresses an increase in specific resistance during processing. Can do.

  The material used for the probe pin of the present invention can be processed at a processing rate of 60% or less, preferably 3 to 50% after heat treatment at 700 ° C. or higher. If the heat treatment temperature is less than 700 ° C., it is not sufficiently softened, and cracks, cracks and breaks occur after processing. Similarly, if the processing rate exceeds 60%, cracks, cracks and breaks occur after processing.

  The material used for the probe pin of the present invention can be processed at a processing rate of 60% or less, preferably 3 to 50% after heating in a temperature range of 700 to 1100 ° C. This is because cracks and cracks are generated on the surface when the heating temperature is out of the temperature range of 700 to 1100 ° C. Here, the processing rate refers to the rolling rate or / and the cross-section reduction rate.

(Probe pin manufacturing method)
The alloy used for the probe pin according to the present invention can be produced by adding a predetermined amount of Zr to Rh and melting it in an arc melting furnace or a plasma melting furnace according to a method known per se. An inert gas can be used as the furnace atmosphere during melting. Further, the ingot is produced by solidifying the above alloy in a molten state with an appropriate mold.

  After heat treating the ingot at a temperature of 700 ° C or higher, at a processing rate of 60% or less, or after heating at 700 to 1100 ° C, the processing rate is 60% or less and subjected to warm or hot forging or swaging. can do.

  After heat-treating the ingot at a temperature of 700 ° C. or higher, at a processing rate of 60% or less, or after heating at 700 to 1100 ° C., the processing rate is 60% or less and is square or polygonal by a warm or hot groove roll. Process into bar or wire. Furthermore, after heat treatment at a temperature of 700 ° C or higher using a die, at a processing rate of 60% or less, or after heating at 700 to 1100 ° C, the processing rate is 60% or less and warm or hot wire drawing at 200 ° C or higher By processing, a probe pin material can be produced. A plate shape can be produced by rolling, and a probe pin material can be produced from the resulting shape using a cutting process or the like. The probe pin material can be made into a probe pin by cutting or the like.

  Hereinafter, the present invention will be described more specifically with reference to examples.

  A predetermined amount of Zr was mixed with Rh, and a predetermined amount was mixed to 60 g per sample, and melted and solidified in an arc melting furnace on a water-cooled copper hearth having a predetermined shape to prepare an ingot. Table 1 shows the composition produced. In addition, Rh and Rh-Ti alloy ingots were prepared as comparative examples.

  In order to determine the workability, the manufactured ingot was heated (heat treated) to 1000 ° C. with an oxygen-city gas burner and then processed by groove roll processing with a cross-sectional reduction rate of 20%. Cross section reduction rate (%) = ((area before processing−area after processing) / area before processing) × 100.

  At this stage, no cracks occurred in all samples.

The hardness of each sample after processing (hereinafter referred to as a processed material) was measured.
Table 2 shows the hardness measurement results of samples (hereinafter referred to as heat treated materials) obtained by further heat treating the processed material at 1000 ° C. for 1 hour.

  Both the examples and the comparative examples have a hardness of HV350 or more at a low processing rate of about 20%, and the hardness is a hardness that can be used for the samples of the comparative examples. Since the samples obtained by heat-treating the processed material are HV300 or less in both the examples and the comparative examples, it can be seen that the increase in hardness is large even in low processing.

  The structure of each sample after processing (processed material) was observed, and the aspect ratio (= crystal grain length / crystal grain width) was calculated. The survey results are shown in Table 3.

  As shown in Table 3, all the examples have an aspect ratio of 4.0 or more, whereas Comparative Examples 1-1 to 1-2 and 1-3 have no aspect ratio of 2 or less and have no processed structure. .

  As representative examples, longitudinal sectional photographs of the processed materials of Example 1-3, Comparative Example 1-1, and Comparative Example 1-3 are shown in FIGS.

  As can be seen from FIGS. 1 to 3, Example 1-3 shows a fibrous structure even at a low processing rate of 20%, whereas Comparative Example 1-1 and Comparative Example 1-3 have large and small crystal grains. However, it is not a processed structure and is almost in the form of equiaxed crystals.

After processing (processed material), the electrical resistance of each sample was measured, and the specific resistance of the processed material was investigated.
Table 4 shows the results of investigation of specific resistance at room temperature for each sample.

  The example is 10.0 μΩ · cm or less at a processing rate of 20%, which is lower than the specific resistance of annealed Pt, which is 10.5 μΩ · cm, and shows excellent characteristics as a probe material. . On the other hand, Comparative Example 1-4 is 10.9 μΩ · cm, which is higher than the specific resistance of Pt. That is, the Rh-based alloy with Zr of 1.0 mass% has a problem that the temperature of the probe pin is likely to increase due to resistance heating because the specific resistance is larger than Pt.

  In order to ascertain the processing temperature, the above-mentioned processed material was heated (heat treatment) to 600 ° C. in an electric furnace, processed by groove roll processing at a cross-section reduction rate of 20%, and the state of each sample after processing was observed. Table 5 shows the processing conditions at that time.

  From the results in Table 5, the heat treatment at less than 700 ° C. caused cracks on the surface of all samples even when the cross-section reduction rate was as low as about 20%, and the processing under these conditions was interrupted here.

In order to determine the processing rate, the above-mentioned processed material was heated to 1000 ° C. (heat treatment) in an electric furnace, then rolled to a rolling rate of 70%, and the state of each sample after processing was observed. . Rolling ratio (%) = ((sheet thickness before rolling−sheet thickness after rolling) / sheet thickness before rolling) × 100.
Table 6 shows the processing conditions at that time.

  From the results in Table 6, cracking and cracking occurred in all samples during rolling at 70% with a processing rate exceeding 60%, and processing under these conditions was interrupted here.

  Next, the aforementioned processed material was further processed to reduce the diameter to about □ 1.0 mm. Specifically, after heating at 800 ° C., heating with an oxygen-city gas burner was performed so that the temperature of the material was 700 to 1000 ° C. as measured by a radiation thermometer. The processing rate is a cross-sectional reduction rate of 40% or less. The grooved roll material was wound on a reel with a radius of about 150 mm. Table 7 shows the processing conditions at that time.

  As shown in Table 7, each sample had no particular problem immediately after processing, but Examples 1-1 to 1-6 had no particular problem when it was wound on a reel, but Comparative Examples 1-1 to 1-3. Was applied to the reel, and broke frequently at locations where bending stress was applied, making it impossible to process.

  As a representative example, FIG. 4 shows the SEM observation result of the broken part of Comparative Example 1-1 in which breakage occurred particularly frequently.

As a result of the observation, fractures occurred along the grain boundaries as shown in FIG.
For this reason, if a predetermined amount of Zr is not added, there is no problem in processing where bending stress is not applied, but if bending stress is applied in a state where processing strain is applied, cracks will occur and break along the grain boundaries. I understand that Further, as in Comparative Example 1-3, it can be seen that the addition of elements other than Zr does not always improve.

  Furthermore, the following processing was performed on the example samples after coming out of the groove roll shown in Table 7. That is, after heating to 800 ° C. in an electric furnace, the wire was drawn using a die at a cross-section reduction rate of 3%. Then, the die-processed material was wound on a reel having a radius of about 150 mm. Table 8 shows the processing conditions at that time.

  As shown in Table 8, there was no particular problem at the stage of winding each reel immediately after processing for each sample.

  When probe wires were produced using the wires shown in Table 8, there were no problems such as cracks.

  The present invention relates to a probe pin (hereinafter abbreviated as “probe pin”) incorporated in a probe card for inspecting electrical characteristics of an integrated circuit or the like on a semiconductor wafer and a method for manufacturing the same.

  A probe card in which a plurality of probe pins are incorporated is used for inspection of electrical characteristics of an integrated circuit or the like formed on a semiconductor wafer. This inspection is performed by bringing a probe pin incorporated in a probe card into contact with an electrode, a terminal, or a conductive portion of an integrated circuit or the like.

  Such a probe pin is not only highly conductive, but also requires corrosion resistance and oxidation resistance in order to obtain a stable inspection result, and is required to have sufficient strength because it is repeatedly brought into contact with an inspection object. The strength is required because it is necessary to reduce wear caused by contacting the probe pin with the test object tens of thousands of times.

JP 10-38922 JP 10-221366 JP-A-11-94872 JP2000-137042 JP2005-233967 Patent 4874401 Patent No. 5074608

At present, beryllium copper, phosphor bronze, and tungsten are used for probe pins as shown in Patent Document 1 and Patent Document 2, for example.
Probe pins using beryllium copper, phosphor bronze, or tungsten are inferior in oxidation resistance, and when used, an oxide film is formed on the surface, and the oxide adheres to the object to be inspected as inspection continues. However, there is a problem that poor conduction occurs.

In order to prevent such a defect due to the formation of an oxide film of the probe pin, a palladium alloy or a platinum alloy may be used as in Patent Document 3, Patent Document 4, Patent Document 5, and Patent Document 6.
Among these, the probe pin using the palladium alloy improves the hardness by improving the hardness by work hardening, improving the hardness by precipitation hardening, or both. Moreover, platinum alloy improves hardness by solid solution hardening and work hardening.

  Among them, the ratio of power semiconductors among semiconductors to be inspected with probe cards is gradually increasing.

  Power semiconductors are used in inverter circuits and the like, and are often exposed to higher temperatures than ordinary semiconductors due to the usage environment and usage. Along with this, inspections at high temperatures are also required. In the conventional semiconductor, the inspection temperature of the Si wafer hardly exceeds 100 ° C., but in the case of the power semiconductor, it may exceed 100 ° C.

  Furthermore, when the wafer used is SiC or GaN, the inspection is performed at 200 ° C. or higher, and the flowing current tends to increase. For this reason, the temperature applied to the probe pin is sometimes increased to 300 ° C. or more by resistance heating in addition to the test temperature.

  Tungsten, beryllium copper, etc. are used for inspections at such test temperatures, but because they are more susceptible to oxidation than the normal temperature range, inspection defects are likely to occur, and platinum alloys and palladium alloys The rate at which is used is increasing.

  However, platinum alloys and palladium alloys also have problems, and in the case of platinum alloys, the resistance is larger than other materials, so the probe pin temperature rises easily due to resistance heating, in the case of palladium alloys, it approaches the aging temperature, In addition, since the inspection is performed at the aging temperature, there is a concern that the aging of the probe pin progresses and becomes brittle and easily breaks.

  Among these metals, Rh having a low specific resistance and oxidation resistance has attracted attention.

  As in Patent Document 7, a rhodium alloy patent has been issued as a probe pin having low resistance and antifouling properties.

  Patent Document 7 discloses a patent in which Fe, Ir, and Re are added in a very small amount of about several hundred ppm in order to improve low resistance and antifouling properties while ensuring processability.

  As a characteristic of Rh, there is a characteristic that work hardening ability is very high. For this reason, strong processing is not performed, and a crystal grain becomes a coarse structure. Also, the grain boundary strength is weak and processing by hot working etc. is easier than iridium, but when bending stress is applied to work-hardened material, cracks enter the surface starting from the grain boundary, and in some cases bending stress is applied Break at a point. When used as a probe pin, bending after wire drawing is usually performed in many cases, and even if bending is performed, there is no breakage such as breakage and there is a demand for minimal surface cracks. Yes.

  In view of the above-described problems of the prior art, an object of the present invention is to provide a probe pin that is unlikely to crack and a method for manufacturing the probe pin.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors processed an alloy containing a small amount of Zr in Rh at a processing rate of 60% or less after heat treatment at a predetermined temperature, or a predetermined amount. By heating at a temperature and processing at a processing rate of 60% or less, the Vickers hardness is set to 350 or more, and at the same time, the aspect ratio (the ratio of the length to the crystal grain width, crystal grain length / grain width, below) It has been found that by setting the aspect ratio to 4 or more, it is possible to obtain a probe pin that is less prone to cracks starting from grain boundaries on the surface, and the present invention has been completed. Here, the processing rate is a general term for a rolling rate and / or a cross-sectional reduction rate.

That is, the above-mentioned purpose is to contain an Rh-based alloy containing 0.08 to 0.70 mass% of Zr and the balance being Rh and inevitable impurities , rolling ratio [rolling ratio (%) = ((sheet thickness before rolling−sheet thickness after rolling) ) / Thickness before rolling) × 100] or cross-section reduction rate [cross-section reduction rate (%) = ((area before wire drawing−area after wire drawing) / area before wire drawing) × 100 ”, after performing rolling or / and wire drawing of 60% or less, the aspect ratio (the ratio of the length to the width of the crystal grains, the crystal grain length / grain width) is 4 or more, This is achieved by a probe pin made of a material having a Vickers hardness of 350 or more.

The above object is achieved by a method for producing a probe pin, characterized in that the material used for the probe pin is heat-treated at 700 ° C. or higher before processing and then rolled at a rolling rate of 60% or less . Further, it is achieved by a method for manufacturing a probe pin, characterized in that a material used for the probe pin is heat-treated at 700 ° C. or higher before processing, and then drawn at a cross-section reduction rate of 60% or less.

The above object is achieved by a method for producing a probe pin, wherein the material used for the probe pin is heated in a temperature range of 700 to 1100 ° C. and then rolled at a rolling rate of 60% or less . Further, it is achieved by a method of manufacturing a probe pin, characterized in that after the material used for the probe pin is heated in a temperature range of 700 to 1100 ° C., the cross-section reduction rate is drawn to 60% or less.

  According to the present invention, it is possible to provide a probe pin that is unlikely to crack and a method for manufacturing the probe pin.

Organizational photograph of Example 1-3 Structural photograph of Comparative Example 1-1 Structural photograph of Comparative Example 1-3 SEM observation result of Comparative Example 1-1

(Probe pin)
Since the probe pin needs to be processed into a predetermined shape in order to be incorporated into the probe card, it is necessary to suppress defects such as cracks on the surface when the probe pin is bent at least 90 °.
Rh is a material that has a high work-hardening ability, and therefore has a large increase in hardness even at a low processing rate, and is hard to be hard-worked. For this reason, even if the processing is performed, the crystal grains remain coarse and cracks are easily generated from the grain boundaries.

  In the present invention, a predetermined amount of Zr is added to suppress cracks on the surface during wire processing and probe pin processing, and breakage of the wire and the probe pin, so that the aspect ratio is 4 or more even at a low processing rate. Thus, it was found that surface cracks, strands, and probe pin breakage were suppressed.

  Further, the present invention has found that cracks on the surface and breakage from bent portions can be suppressed by setting the processing rate to 60% or less, preferably 3 to 50%.

  The probe pin of the present invention is made of an alloy composed of 0.08 to 0.7 mass% Zr and the balance of Rh and inevitable impurities. A more preferable composition is that Zr is 0.1 to 0.6 mass% and the balance is Rh, so that the aspect ratio can be increased, and further, since it is used in a processed material, it suppresses an increase in specific resistance during processing. Can do.

  The material used for the probe pin of the present invention can be processed at a processing rate of 60% or less, preferably 3 to 50% after heat treatment at 700 ° C. or higher. If the heat treatment temperature is less than 700 ° C., it is not sufficiently softened, and cracks, cracks and breaks occur after processing. Similarly, if the processing rate exceeds 60%, cracks, cracks and breaks occur after processing.

  The material used for the probe pin of the present invention can be processed at a processing rate of 60% or less, preferably 3 to 50% after heating in a temperature range of 700 to 1100 ° C. This is because cracks and cracks are generated on the surface when the heating temperature is out of the temperature range of 700 to 1100 ° C. Here, the processing rate refers to the rolling rate or / and the cross-section reduction rate.

(Probe pin manufacturing method)
The alloy used for the probe pin according to the present invention can be produced by adding a predetermined amount of Zr to Rh and melting it in an arc melting furnace or a plasma melting furnace according to a method known per se. An inert gas can be used as the furnace atmosphere during melting. Further, the ingot is produced by solidifying the above alloy in a molten state with an appropriate mold.

  After heat treating the ingot at a temperature of 700 ° C or higher, at a processing rate of 60% or less, or after heating at 700 to 1100 ° C, the processing rate is 60% or less and subjected to warm or hot forging or swaging. can do.

  After heat-treating the ingot at a temperature of 700 ° C. or higher, at a processing rate of 60% or less, or after heating at 700 to 1100 ° C., the processing rate is 60% or less and is square or polygonal by a warm or hot groove roll. Process into bar or wire. Furthermore, after heat treatment at a temperature of 700 ° C or higher using a die, at a processing rate of 60% or less, or after heating at 700 to 1100 ° C, the processing rate is 60% or less and warm or hot wire drawing at 200 ° C or higher By processing, a probe pin material can be produced. A plate shape can be produced by rolling, and a probe pin material can be produced from the resulting shape using a cutting process or the like. The probe pin material can be made into a probe pin by cutting or the like.

  Hereinafter, the present invention will be described more specifically with reference to examples.

  A predetermined amount of Zr was mixed with Rh, and a predetermined amount was mixed to 60 g per sample, and melted and solidified in an arc melting furnace on a water-cooled copper hearth having a predetermined shape to prepare an ingot. Table 1 shows the composition produced. In addition, Rh and Rh-Ti alloy ingots were prepared as comparative examples.

  In order to determine the workability, the manufactured ingot was heated (heat treated) to 1000 ° C. with an oxygen-city gas burner and then processed by groove roll processing with a cross-sectional reduction rate of 20%. Cross section reduction rate (%) = ((area before processing−area after processing) / area before processing) × 100.

  At this stage, no cracks occurred in all samples.

The hardness of each sample after processing (hereinafter referred to as a processed material) was measured.
Table 2 shows the hardness measurement results of samples (hereinafter referred to as heat treated materials) obtained by further heat treating the processed material at 1000 ° C. for 1 hour.

  Both the examples and the comparative examples have a hardness of HV350 or more at a low processing rate of about 20%, and the hardness is a hardness that can be used for the samples of the comparative examples. Since the samples obtained by heat-treating the processed material are HV300 or less in both the examples and the comparative examples, it can be seen that the increase in hardness is large even in low processing.

  The structure of each sample after processing (processed material) was observed, and the aspect ratio (= crystal grain length / crystal grain width) was calculated. The survey results are shown in Table 3.

  As shown in Table 3, all the examples have an aspect ratio of 4.0 or more, whereas Comparative Examples 1-1 to 1-2 and 1-3 have no aspect ratio of 2 or less and have no processed structure. .

  As representative examples, longitudinal sectional photographs of the processed materials of Example 1-3, Comparative Example 1-1, and Comparative Example 1-3 are shown in FIGS.

  As can be seen from FIGS. 1 to 3, Example 1-3 shows a fibrous structure even at a low processing rate of 20%, whereas Comparative Example 1-1 and Comparative Example 1-3 have large and small crystal grains. However, it is not a processed structure and is almost in the form of equiaxed crystals.

After processing (processed material), the electrical resistance of each sample was measured, and the specific resistance of the processed material was investigated.
Table 4 shows the results of investigation of specific resistance at room temperature for each sample.

  The example is 10.0 μΩ · cm or less at a processing rate of 20%, which is lower than the specific resistance of annealed Pt, which is 10.5 μΩ · cm, and shows excellent characteristics as a probe material. . On the other hand, Comparative Example 1-4 is 10.9 μΩ · cm, which is higher than the specific resistance of Pt. That is, the Rh-based alloy with Zr of 1.0 mass% has a problem that the temperature of the probe pin is likely to increase due to resistance heating because the specific resistance is larger than Pt.

  In order to ascertain the processing temperature, the above-mentioned processed material was heated (heat treatment) to 600 ° C. in an electric furnace, processed by groove roll processing at a cross-section reduction rate of 20%, and the state of each sample after processing was observed. Table 5 shows the processing conditions at that time.

  From the results in Table 5, the heat treatment at less than 700 ° C. caused cracks on the surface of all samples even when the cross-section reduction rate was as low as about 20%, and the processing under these conditions was interrupted here.

In order to determine the processing rate, the above-mentioned processed material was heated to 1000 ° C. (heat treatment) in an electric furnace, then rolled to a rolling rate of 70%, and the state of each sample after processing was observed. . Rolling ratio (%) = ((sheet thickness before rolling−sheet thickness after rolling) / sheet thickness before rolling) × 100.
Table 6 shows the processing conditions at that time.

  From the results in Table 6, cracking and cracking occurred in all samples during rolling at 70% with a processing rate exceeding 60%, and processing under these conditions was interrupted here.

  Next, the aforementioned processed material was further processed to reduce the diameter to about □ 1.0 mm. Specifically, after heating at 800 ° C., heating with an oxygen-city gas burner was performed so that the temperature of the material was 700 to 1000 ° C. as measured by a radiation thermometer. The processing rate is a cross-sectional reduction rate of 40% or less. The grooved roll material was wound on a reel with a radius of about 150 mm. Table 7 shows the processing conditions at that time.

  As shown in Table 7, each sample had no particular problem immediately after processing, but Examples 1-1 to 1-6 had no particular problem when it was wound on a reel, but Comparative Examples 1-1 to 1-3. Was applied to the reel, and broke frequently at locations where bending stress was applied, making it impossible to process.

  As a representative example, FIG. 4 shows the SEM observation result of the broken part of Comparative Example 1-1 in which breakage occurred particularly frequently.

As a result of the observation, fractures occurred along the grain boundaries as shown in FIG.
For this reason, if a predetermined amount of Zr is not added, there is no problem in processing where bending stress is not applied, but if bending stress is applied in a state where processing strain is applied, cracks will occur and break along the grain boundaries. I understand that Further, as in Comparative Example 1-3, it can be seen that the addition of elements other than Zr does not always improve.

  Further, the following processing was performed on the example samples after coming out of the groove roll shown in Table 7. That is, after heating to 800 ° C. in an electric furnace, the wire was drawn using a die at a cross-section reduction rate of 3%. Then, the die-processed material was wound on a reel having a radius of about 150 mm. Table 8 shows the processing conditions at that time.

  As shown in Table 8, there was no particular problem at the stage of winding each reel immediately after processing for each sample.

  When probe pins were produced using the wires shown in Table 8, there were no problems such as cracks.

Claims (3)

  99.92 ~ 99.30mass% Rh-based alloy with Zr of 0.08 ~ 0.70mass% and total of 100mass% in combination with inevitable impurities, aspect ratio (length ratio to grain width, grain length A probe pin made of a material having a crystal grain width) of 4 or more and a Vickers hardness of 350 or more.   2. The method of manufacturing a probe pin according to claim 1, wherein the material used for the probe pin is heat-treated at 700 ° C. or higher before being processed, and then rolled or / and drawn at a rolling rate or a cross-section reduction rate of 60% or less. A method for manufacturing a probe pin.   2. The method of manufacturing a probe pin according to claim 1, wherein the material used for the probe pin is rolled or / and drawn after heating at a rolling rate or cross-section reduction rate of 60% or less and in a temperature range of 700 to 1100.degree. A method of manufacturing a probe pin, comprising: