JP2002173731A - Tungsten wire and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide tungsten wire which has high mechanical strength, and exhibits excellent durability when used, e.g. as the structural material of a probe pin for semiconductor inspection, and to provide a production method by which the tungsten wire can efficiently be produced. SOLUTION: When the wire diameter of the tungsten wire is 0.37 to 0.41 mm, its tensile strength is 2,350 to 3,000 N/mm2. Further, the tungsten wire is preferably consisting of a tungsten alloy containing 1 to 5 mass% rhenium (Re).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tungsten wire and a method for manufacturing the same, and more particularly to a tungsten wire having high mechanical strength and exhibiting excellent durability when used as a component such as a probe pin for semiconductor inspection. The present invention relates to a tungsten wire and a manufacturing method capable of efficiently manufacturing the tungsten wire.

[0002]

2. Description of the Related Art Conventionally, cathode heaters for TV electron guns, filament materials for lighting of automobile lamps and home electric appliances,
Various tungsten wires have been used as components of high-temperature structural members, contact materials, and discharge electrodes. Particularly, a tungsten wire containing a predetermined amount of rhenium (Re) is excellent in high-temperature strength and ductility (workability) after recrystallization, and thus is widely used for a heater for an electron tube and a filament material for an anti-vibration bulb. Because of its excellent resistance characteristics and abrasion resistance, it is widely used as a constituent material of probe pins for semiconductor inspection.

FIG. 3 is a partial sectional view showing a configuration example of a probe card 20 having a probe pin formed of the above-mentioned tungsten wire. The probe card 20 has a plurality of probe pins 22 so as to extend obliquely downward from a multilayer printed circuit board 21 serving as a base. A plurality of probe pins 22 are provided corresponding to the number of electrode pads of a chip on a semiconductor wafer. The extending portion of each probe pin 22 is fixed with an epoxy resin 23 or the like.

When inspecting electrical characteristics (soundness of operation) of a semiconductor integrated circuit (IC), a liquid crystal display (LCD), or the like, each probe pin 22 is connected to a terminal (electrode portion) of the inspection object. The electrical contact from the device under test is transmitted to the tester by resiliently contacting the tip of the device, thereby inspecting the electrical characteristics of the device under test. Then, only non-defective products, for which it has been confirmed that the device under test, such as a semiconductor device, operates normally, are transferred to the next assembly process.

[0005] The tungsten wire constituting the probe pin as described above has been conventionally manufactured by a manufacturing process as shown in FIG. That is, a green compact is formed by pressurizing and forming a tungsten powder containing a dopant such as Al, Si, K or the like, and Re.
For example, after being pre-sintered at a temperature of about 1200 ° C., the two ends thereof are used as terminals to conduct current sintering to prepare a tungsten sintered body 1.

Next, an operation of heating the obtained tungsten sintered body 1 with a heating device 2 for rolling and a process of rolling the heated sintered body with a rolling device 3 until a predetermined processing rate is achieved are considered. After repeating the process, the work-hardened sintered body is
To perform a recrystallization treatment to obtain a tungsten wire material 1a. Further, by repeating the rolling operation by the rolling device 3 and the heating operation by the heating device for rolling 2 several times, the processing rate is further increased, and the tungsten wire material 1b having a smaller cross-sectional area is formed.

Next, an operation of heating the obtained tungsten wire material 1b by a wire drawing heating device 5, and an operation of drawing the heated tungsten wire material 1b to a predetermined wire diameter by a wire drawing machine 6. Was repeated a plurality of times to finally produce a tungsten wire 7 having a predetermined wire diameter. The manufactured tungsten wire 7 is wound into a coil shape by a winding device 8.

[0008]

However, for example, in a tungsten wire containing about 3% by mass of rhenium (Re) manufactured by the above-described conventional manufacturing process, the wire diameter is reduced to about 0.39 mm. The tensile strength when formed was about 2200 to 2300 N / mm ² , which was insufficient as the strength of the tungsten wire forming the probe pin. That is, when the tip of the probe pin is repeatedly brought into contact with the terminal of the object to be inspected, deformation or wear is apt to occur, causing a problem of poor contact at an early stage, resulting in a problem that inspection accuracy is rapidly lowered.

On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 2000-119837, a part of a probe pin is hardened by carbonizing or nitriding to have a tensile strength of 3000 to 60.
Probe pins that have been increased to about 00 N / mm ² have also been proposed. However, since the probe pin has a hardened metal structure, it has a disadvantage that it is easily broken.

On the other hand, as the integration density of semiconductor devices further increases in the future, thinning of the probe pin diameter for inspection is progressed, and the number of probe pins arranged per unit area is inevitably increased. It is inevitable to increase. Therefore, the development of tungsten having a high tensile strength even when the wire is made finer has become a technical problem.

In the conventional method of manufacturing a tungsten wire, a tungsten wire material is prepared by repeatedly performing a heating process and a stamping process on a tungsten sintered body having a predetermined size. The processing rate that can be processed by the rolling device after performing the above is a low value of at most 10 to 30%. Therefore, in order to process from a tungsten sintered body to a predetermined tungsten fine wire material, it is necessary to repeat the heat treatment and the stamping process many times as shown in FIG. As a result, while the production cost of the tungsten wire is increased, there is also a problem that the hardening action due to the accumulation of strain does not work due to the repetition of heating and rolling, and only a tungsten wire having a low tensile strength can be obtained.

The present invention has been made to solve the above problems, and has high mechanical strength and can exhibit excellent durability when used as a constituent material such as a probe pin for semiconductor inspection. An object of the present invention is to provide a tungsten wire and a manufacturing method capable of efficiently manufacturing the tungsten wire.

[0013]

Means for Solving the Problems The inventors of the present invention carried out a step of rolling at a high working ratio of 40 to 70% after performing a single heat treatment as a pre-process for rolling a tungsten sintered body. By adding, it was found that a tungsten wire having high tensile strength characteristics can be efficiently produced, and the present invention was completed.

That is, the tungsten wire according to the present invention is characterized in that when the wire diameter is 0.37 to 0.41 mm, the tensile strength is 2350 to 3000 N / mm ² . The tensile strength is 2350-2500 N / m.
The range of m ² is more preferred.

Further, the tungsten wire is formed of rhenium (R
It is preferable to comprise a tungsten alloy containing 1 to 5% by mass of e).

Further, a probe pin according to the present invention is characterized by comprising the above-mentioned tungsten wire.

Further, the method for producing a tungsten wire according to the present invention comprises the steps of: heating and rolling a tungsten sintered body;
A step of heating and rolling after the recrystallized heat treatment of the rolled sintered body, and a step of heating and drawing the rolled sintered body, and a rolling operation performed by one heating in the rolling step. The processing rate is 40 to 70%. here,
The processing rate is defined as a value obtained by dividing a difference in cross-sectional area between before and after processing of a workpiece by a cross-sectional area before processing.

Further, in the above-mentioned manufacturing method, it is preferable that the tungsten sintered body contains 1 to 5% by mass of rhenium (Re).

The tungsten wire according to the present invention is formed from a material containing tungsten (W) as a main component, and has a tungsten content of 70 to 100% by mass, preferably 90 to 1% by mass.
00% by weight of the material is used. Specific examples of the composition include a pure tungsten material, a doped tungsten material containing 0.01 to 1.0% by mass of a dopant element such as Al, Si, and K, or 1 to 5% by mass of Re, preferably 2% by mass. ~ 4
Re-W alloy material containing 1% by mass, and Re-Mo containing 1% to 10% by mass of Mo and 1% to 10% by mass of Mo
-W alloy or the like can be applied. Among these materials, in particular, as a material of a tungsten wire constituting a probe pin for semiconductor inspection, the ductility is enhanced to improve workability, and at the same time, high strength characteristics (tensile strength), hardness (wear resistance) and From the viewpoint of high conductivity (low contact resistance), a Re-W alloy in which a predetermined amount of Re is dissolved is preferable.

If the rhenium content of the tungsten wire is less than 1% by mass, the amount of deformation of the probe pin increases with the frequency of use as a probe pin, resulting in poor contact and lowering the semiconductor inspection accuracy. On the other hand, when the content is 5
If the content is more than 10% by mass, segregation tends to occur in some parts, and the workability tends to decrease when processing into fine wires, and the production yield of W wires decreases. Therefore, the content of Re is in the range of 1 to 5% by mass, and more preferably in the range of 2 to 4% by mass.

The tungsten wire according to the present invention is not manufactured by subjecting the above-described material (sintered body) containing tungsten as a main component to only conventional rolling and drawing. Instead, it is manufactured by a processing process in which rolling is added as a pre-process of the above-described rolling and wire drawing. In particular, in the rolling process, the working ratio (cross-sectional reduction ratio) by rolling after performing one heat treatment (one heat) is specified to be 40 to 70%.

In the above rolling process, 40 to 7
By giving a high processing rate of 0%, the tensile strength of the finally formed tungsten wire having a wire diameter of 0.37 to 0.41 mm can be improved to 2350 to 3000 N / mm ² , and semiconductor inspection can be performed. Tungsten wire suitable as a constituent material of the probe pin is efficiently obtained.

If the working ratio in the rolling step is too small, less than 40%, the effect of improving the tensile strength is small, and
The number of repetitions of stamping and drawing required to obtain a predetermined wire diameter increases, and the manufacturing efficiency decreases. On the other hand, when the working ratio is excessively large so as to exceed 70%, work hardening becomes remarkable, and cracks and breaks easily occur in the tungsten wire. Therefore, the working ratio in the rolling process is 40 to 70.
%, But is more preferably in the range of 50 to 65%.

The tungsten wire according to the present invention is manufactured through a manufacturing process as shown in FIG. That is, the tungsten sintered body 1 having a predetermined composition is heated to 1200 to 1300 ° C. by the heating device 9 for rolling, and then subjected to rolling by the rolling mill 10. As the rolling machine 10, a two-way roller rolling machine or a four-way roller rolling machine, a mold roll rolling machine, or the like can be used.

The above-mentioned rolling process can be advanced at a high speed, and the rolling of a plurality of stands can be completed while the temperature of the tungsten sintered body 1 does not decrease. That is, a high processing rate of 40 to 70% can be obtained by performing only one heat treatment on the tungsten sintered body 1. Therefore, it is possible to greatly increase the production efficiency of the tungsten wire as compared with the conventional production method of producing a tungsten wire having a predetermined wire diameter by performing only the stamping and drawing processing on the tungsten sintered body 1. Will be possible.

Tungsten wire blank 1 after rolling process
a is equal to or higher than the secondary recrystallization temperature (180
(0 to 2000 ° C.), and after being subjected to a recrystallization heat treatment to remove distortion, is sent to the driving device 3. In the rolling step, the processing of rolling the W wire material 1a by a hammer from the circumferential direction and the processing of being heated by the heating device for rolling 2 are repeated, and the W wire material 1a is thinned at a predetermined processing rate.
In this rolling device 3, it is difficult to set a high processing speed, and the processing rate that can be processed by one heat treatment is about 10 to 30%.

The rolled tungsten wire material 1b is then repeatedly heated by a wire drawing heating device 5 and drawn by a wire drawing machine (drawing die) 6, and finally processed. Tungsten wire 7 having a desired fine wire diameter
Can be obtained efficiently. The prepared wire diameter of 0.3
The tensile strength of a 9 mm tungsten wire is 2350-30.
00N / mm ² , and has strength and durability suitable as a constituent material of a probe pin for semiconductor inspection.

According to the tungsten wire and the method of manufacturing the same according to the present invention, the tungsten fine wire is prepared through rolling to give a high working ratio of 40 to 70% to the tungsten sintered body, so that the tensile strength is 2350 to 100%. 3000 N / mm
² , a tungsten wire having strength and durability suitable as a constituent material of a probe pin for semiconductor inspection can be obtained.

Further, since the rolling process through which a high working ratio can be obtained is passed, the working ratio in the rolling / drawing process after rolling can be reduced, and the number of repetitions of the rolling / drawing process can be reduced. Therefore, the manufacturing process of the tungsten wire can be simplified, and the manufacturing efficiency of the tungsten wire can be greatly increased.

[0030]

Next, an embodiment of the present invention will be described.
Specific description will be given based on the following examples and comparative examples with reference to the drawings.

Examples 1 to 5 Tungsten (W) powder having an average particle size of 3 μm was added to an average particle size of 2 μm.
After adding 3 μm of rhenium (Re) powder at a ratio of 3 μm, the mixture was uniformly mixed for 2 to 20 hours to obtain a raw material mixture.
After the obtained raw material mixture was formed into a compact at a compacting pressure of 200 MPa, it was temporarily sintered at 1300 ° C. in a hydrogen atmosphere, and then electrically sintered to prepare 1.5 kg of a W sintered compact.

Next, each W sintered body is sequentially rolled, recrystallized, stamped, and drawn according to the manufacturing process shown in FIG. 1 and finally has a nominal wire diameter of 0.39 mm. A tungsten wire 7 was manufactured. The heating temperature and the processing rate by the heating device 9 for rolling in the rolling process, the recrystallization temperature in the heat treatment furnace 4, the heating temperature and the processing rate by the heating device 2 for driving in the rolling process, and the drawing temperature in the wire drawing process. The heating temperature and the processing rate by the heating device 5 were set to the values shown in Table 1.

Comparative Examples 1 to 5 On the other hand, as shown in FIG. 2, the rolling process in the rolling process shown in Table 1 was performed according to a manufacturing process including only a rolling process and a wire drawing process without providing a rolling process by the rolling mill 10. Processing was performed in the same manner as in Examples 1 to 5, except that rolling, recrystallization, and wire drawing were repeatedly performed while setting the heating temperature and the working rate, and the heating temperature and working rate in the wire drawing step. A tungsten wire having a nominal wire diameter of 0.39 mm according to each comparative example was prepared.

With respect to the tungsten wires according to the examples and the comparative examples prepared as described above, the wire diameter was precisely measured, and the tensile load was measured using a tensile tester.
Further, the cross-sectional area was determined from the wire diameter, and the tensile load was divided by the cross-sectional area to calculate the tensile strength. The results of each measurement calculation are shown in Table 1 below and FIG.

[0035]

[Table 1]

As is evident from the results shown in Table 1 and FIG. 4, the tungsten wire according to each of the examples formed by rolling and wire-drawing after the rolling step for providing a high working ratio is obtained. Higher tensile strength is obtained as compared with the tungsten wire of the comparative example formed only by the punching and drawing processes.

Further, in the tungsten wire according to each embodiment, a high processing rate can be obtained in the rolling step.
The number of repetitions of stamping and drawing required to achieve a predetermined fine wire diameter can be greatly reduced, and the tungsten wire manufacturing process can be simplified, greatly increasing manufacturing efficiency. it can.

Further, using the tungsten wires according to each of the above embodiments and comparative examples, a probe pin 22 for semiconductor inspection as shown in FIG. 3 is formed, and an inspection probe for a semiconductor integrated circuit or a liquid crystal display device is actually formed. When used as a pin, the number of durable days until the probe pin was deformed or broken and needed to be replaced was compared. As a result, when the probe pin formed of the tungsten wire according to Comparative Example 1 was used as a reference, the durability of the probe pin according to each example could be increased to 1.5 to 2.1 times.

[0039]

As described above, according to the tungsten wire and the method of manufacturing the same according to the present invention, a fine tungsten wire is prepared by rolling to give a high working rate of 40 to 70% to the tungsten sintered body. Therefore, the tensile strength is 23
A tungsten wire having a strength as high as 50 to 3000 N / mm ² and suitable strength and durability as a constituent material of a probe pin for semiconductor inspection can be obtained.

[0040] Further, since the rolling process is performed to obtain a high working ratio, the working ratio in the rolling / drawing process after rolling can be reduced, and the number of repetitions of the rolling / drawing process can be reduced. Therefore, the manufacturing process of the tungsten wire can be simplified, and the manufacturing efficiency of the tungsten wire can be greatly increased.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a manufacturing process of a tungsten wire according to the present invention.

FIG. 2 is a schematic view showing a process for manufacturing a conventional tungsten wire.

FIG. 3 is a cross-sectional view showing an example of arrangement of probe pins formed using a tungsten wire according to the present invention.

FIG. 4 is a graph showing the tensile strength of a tungsten wire according to each example of the present invention together with a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tungsten sintered compact 1a, 1b Tungsten wire material 2 Heating device for rolling 3 Rolling device 4 Heat treatment furnace 5 Heating device for wire drawing 6 Wire drawing machine (drawing die) 7 Tungsten wire 8 Winding device 9 Heating for rolling Apparatus 10 Rolling machine 20 Probe card 21 Base (multilayer printed circuit board) 22 Probe pin 23 Epoxy resin

Claims (6)

[Claims] 1. A tungsten wire having a tensile strength of 2350 to 3000 N / mm ² when the wire diameter is 0.37 to 0.41 mm. 2. The tensile strength is 2350-2500 N /
The tungsten wire according to claim 1, wherein the diameter of the tungsten wire is ² mm. 3. The method according to claim 1, wherein the tungsten wire is rhenium (Re).
The tungsten wire according to claim 1, comprising a tungsten alloy containing 1 to 5% by mass. 4. A probe pin comprising the tungsten wire according to claim 1. 5. A step of heating and rolling a tungsten sintered body, a step of heating and rolling the rolled sintered body after recrystallization heat treatment, and a step of heating and drawing the rolled sintered body. And a working rate of a rolling operation performed by one heating in the rolling step is 40 to 70%. 6. The tungsten sintered body is provided with rhenium (R
The method for producing a tungsten wire according to claim 4, wherein 1) to 5% by mass of e) is contained.