Alloy material for probe pins

Abstract

To provide an alloy material for probe pins that makes it possible to suppress the diffusion of components in the probe material and solder at a circuit connection part to be tested during a probe test.SOLUTION: An alloy material for probe pins includes Pd of more than 20 mass% to 60 mass% or less, Ag of 3 mass% or more and less than 20 mass%, Ni of 3 mass% or more and 50 mass% or less, and Cu of 3 mass% or more and 74 mass% or less. Alternatively, an alloy material for probe pins includes Pd of more than 20 mass% to 60 mass% or less, Ag of 20 mass% or more and 35 mass% or less, Ni of 7 mass% or more and 50 mass% or less, and Cu of 3 mass% or more and 53 mass% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an alloy material for probe pins (hereinafter abbreviated as "probe material") for testing the electrical characteristics of integrated circuits, liquid crystal displays, etc. on semiconductor wafers. [Background technology]

[0002] Sockets and probe cards incorporating multiple probes are used to test the electrical characteristics of integrated circuits, liquid crystal display devices, etc. formed on semiconductor wafers. This testing is performed by contacting the probe pins incorporated in the socket or probe card with electrodes, terminals, or conductive parts of the integrated circuits, liquid crystal display devices, etc.

[0003] Such probe pins require low contact resistance and hardness to withstand repeated contact. Probe materials include beryllium copper alloy, tungsten, tungsten alloy, platinum alloy, and palladium alloy.

[0004] Patent Document 1 discloses a palladium alloy (hereinafter referred to as AgPdCu alloy) composed of 16% to 50% copper, approximately 35% to approximately 59% palladium, and 4% or more silver. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 1,935,897 Summary of the Invention [Problem to be solved by the invention]

[0006] Traditionally, AgPdCu alloys, which have excellent plastic workability and precipitation hardening properties, have been used as probe materials due to their shape stability and low resistivity, which are derived from their hardness. However, when used in circuit connections that use solder (e.g., Sn-Bi solder), the following issues have arisen. Specifically, repeated contact between the probe pin and solder and the passage of current during testing can cause Joule heat and other factors to cause mutual diffusion between solder components, such as Sn, and components of the probe material, resulting in rapid wear of the probe pin tip. In such cases, contact resistance can fluctuate suddenly or over time, resulting in test defects. This requires cleaning or replacement of the contact tip, which reduces the operating rate of the testing process.

[0007] Therefore, there is a strong demand for the development of a probe material that has solder resistance and suppresses the diffusion of solder components.

[0008] An object of the present invention is to provide a probe material that can suppress diffusion of components of the probe material and solder at a circuit connection portion to be inspected during probe inspection. [Means for solving the problem]

[0009] The present inventors have discovered a probe material characterized by comprising more than 20 mass% and not more than 60 mass% Pd, 3 mass% or more and less than 20 mass% Ag, 3 mass% or more and not more than 50 mass% Ni, and 3 mass% or more and not more than 74 mass% Cu, and have completed the present invention.

[0010] The present inventors also discovered a probe material characterized by comprising more than 20 mass% and not more than 60 mass% Pd, 20 mass% to 35 mass% Ag, 7 mass% to 50 mass% Ni, and 3 mass% to 53 mass% Cu, thereby completing the present invention.

[0011] In the above, at least one of In, Sn, Zn, and Ga may be contained in a total amount of 0.2 mass % to 2.0 mass % in place of a portion of Cu. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a probe material that suppresses diffusion of components of the probe material and solder of the circuit connection portion to be inspected during inspection. DETAILED DESCRIPTION OF THE INVENTION

[0013] A first aspect of the present invention is a probe material comprising more than 20 mass% and not more than 60 mass% of Pd, 3 mass% or more and less than 20 mass% of Ag, 3 mass% or more and not more than 50 mass% of Ni, and 3 mass% or more and not more than 74 mass% of Cu.

[0014] A second aspect of the present invention is a probe material comprising more than 20 mass% and not more than 60 mass% of Pd, 20 mass% to 35 mass% of Ag, 7 mass% to 50 mass% of Ni, and 3 mass% to 53 mass% of Cu.

[0015] In the above, at least one of In, Sn, Zn, and Ga may be contained in a total amount of 0.2 mass % to 2.0 mass % in place of a portion of Cu.

[0016] Pd has excellent corrosion resistance, but if it is less than 20 mass%, the corrosion resistance becomes insufficient. On the other hand, if it exceeds 60 mass%, it is not suitable because it cannot sufficiently suppress the diffusion of components in the solder and probe material.

[0017] In another embodiment, the Pd content can be 22 to 55 mass %. In another embodiment, the Pd content can be 25 to 50 mass %.

[0018] Adding Ni to an alloy improves the alloy's solder resistance. Experiments have shown that the amount of Ni required varies depending on the Ag content. In the first invention, the amount of Ag added is small, less than 20 mass%, so if Ni is less than 3 mass%, the diffusion of components of the solder and probe material cannot be sufficiently suppressed, and if Ni is more than 50 mass%, plastic processing such as cold rolling and wire drawing becomes difficult. In the second invention, the amount of Ag added is as large as 20 mass% or more. Therefore, if the Ni content is less than 7 mass%, the diffusion of the components of the solder and the probe material cannot be sufficiently suppressed, and if the Ni content exceeds 50 mass%, plastic processing such as cold rolling and wire drawing becomes difficult.

[0019] In the case of the first invention, in another embodiment, the Ni content can be 5 to 40 mass %. In another embodiment, the Ni content can be 7 to 35 mass %.

[0020] In the case of the second invention, in another embodiment, the Ni content can be 8 to 40 mass%. In another embodiment, the Ni content can be 10 to 35 mass%. In another embodiment, the Ni content can be 11 to 35 mass%.

[0021] Ag improves age hardening when added in combination with Pd and Cu, but if it is less than 3 mass%, the effect is insufficient, and if it exceeds 35 mass%, it is not suitable because it cannot sufficiently suppress the diffusion of components in the solder and probe material.

[0022] In the case of the first invention, in another embodiment, Ag can be 4 mass % to 18 mass %.

[0023] In the case of the second invention, in another embodiment, Ag can be 21 to 33 mass %.

[0024] In addition to its low resistivity, Cu has the effect of improving hardness when alloyed with Pd. However, adding too much Cu reduces corrosion resistance. Therefore, if it is added in amounts less than 3 mass%, sufficient hardness cannot be obtained, and if it exceeds 74 mass%, corrosion resistance decreases.

[0025] In the first aspect of the invention, the Cu content can be 5 to 70 mass% in another embodiment, 10 to 60 mass% in yet another embodiment, and 15 to 50 mass% in yet another embodiment.

[0026] In the case of the second invention, in another embodiment, the Cu content can be 5 to 47 mass %. In yet another embodiment, the Cu content can be 10 to 40 mass %.

[0027] The addition of at least one of In, Sn, Zn, and Ga further improves age hardening, but at less than 0.2 mass%, there is almost no difference from no addition, and at more than 2 mass%, plastic working such as cold rolling and wire drawing becomes difficult.

[0028] In another embodiment, the total content of at least one of In, Sn, Zn, and Ga can be 0.3 to 1.5 mass%.

[0029] It is important for the alloy of the present invention to suppress the phenomenon of wear of the probe pin tip due to diffusion of components of the solder and probe material. Hardness is not as important as that of existing AgPdCu alloys, but hardness is desirable because the contact surface may be mechanically crushed as the number of tests increases. While hardness of 200 HV or more is possible, the alloy of the present invention can achieve a hardness of 250 HV or more. Hardness can be achieved by work hardening through processing, as well as by aging.

[0030] It is believed that the reason why the alloy of the present invention suppresses the diffusion of components of the solder and probe material is as follows: The Ni added to the probe material forms a thin and dense intermetallic compound layer such as Sn-Ni at the interface where the solder and probe pin come into contact, which is thought to have the effect of preventing the diffusion of components of the solder and probe material and to prevent the tip of the probe pin from being easily worn out. [Example]

[0031] An embodiment of the present invention will now be described.

[0032] First, Ag, Pd, Cu, Ni, In, Sn, Zn, and Ga were mixed to obtain the compositions shown in Table 1, and then melted in an argon atmosphere by arc melting to produce alloy ingots. The compositions and properties of the alloys of the examples and comparative examples are shown in Table 1.

[0033] Each of the above alloy ingots was repeatedly rolled and heat treated to produce a plate material with a rolling reduction ratio [= ((thickness before rolling - thickness after rolling) / thickness before rolling) × 100] of 75%, which was used as a test piece for evaluating hardness and solder resistance.

[0034] In the workability investigation, the alloys for which a plate material with a rolling ratio of 75% could be produced were evaluated as O, and those for which it could not be produced were evaluated as X. Alloy compositions for which a plate material with a rolling ratio of 75% could not be produced and for which the workability was evaluated as X (Comparative Example 4 and Comparative Example 9) were not subjected to further tests.

[0035] The test pieces of each alloy thus prepared were subjected to the following evaluations, and the results are shown in Table 2.

[0036] Hardness was measured at the center of the cross section of the test piece using a micro Vickers hardness tester under conditions of a load of 200 gf and a holding time of 10 seconds. The hardness measured at this time is called the "hardness of the worked material." Furthermore, the center of the cross section of a test piece aged at 300-400°C for 1 hour (called the aged material) was measured using a micro Vickers hardness tester under conditions of a load of 200 gf and a holding time of 10 seconds. The hardness measured at this time is called the "hardness of the aged material."

[0037] To measure solder resistance, Sn-Bi solder was placed on a test piece (10 mm x 10 mm x 0.5 mm thick) and heat-treated in a N2 atmosphere at 250°C for 1 hour to melt the solder on the test piece. After heat treatment, the test piece was embedded in resin to expose a cross section, and line analysis was performed vertically using an EPMA on the interface between the solder and the test piece. The layer where Sn and Pd coexist due to mutual diffusion of Sn from the solder and Pd from the alloy was defined as the diffusion layer, and its thickness was measured.

[0038] The thinner the measured diffusion layer thickness, the higher the solder resistance was judged to be, and alloys with a diffusion layer thickness of less than 100 μm were evaluated as ◎, alloys with a diffusion layer thickness of 100 to 200 μm as ○, and alloys with a thickness of 200 μm or more as ×. The evaluation results are shown in Table 2.

[0039] The test specimens used were plates processed to a rolling ratio [= ((thickness before rolling - thickness after rolling) / thickness before rolling) x 100] of 90%. The resistivity was calculated according to Equation 1 by measuring the electrical resistance of each sample at room temperature. Equation 1: Resistivity = (electrical resistance x cross-sectional area) / measurement length

[0040] [Table 1]

[0041] [Table 2]

[0042] From the above results, it can be seen that the alloy produced by the present invention has high solder resistance while also having the hardness, age hardenability, and resistivity required for a probe material. Therefore, the present invention makes it possible to provide a material suitable for use as a solder-resistant probe material.

Claims

1. An alloy material for a probe pin, comprising more than 20 mass% and not more than 60 mass% Pd, 3 mass% or more and less than 20 mass% Ag, 3 mass% or more and not more than 50 mass% Ni, and 3 mass% or more and not more than 74 mass% Cu.

2. 2. The alloy material for a probe pin according to claim 1, further comprising 0.2 mass % to 2.0 mass % of at least one of In, Sn, Zn, and Ga in place of a portion of Cu.

3. An alloy material for a probe pin, comprising more than 20 mass% and not more than 60 mass% of Pd, 20 mass% to 35 mass% of Ag, 7 mass% to 50 mass% of Ni, and 3 mass% to 53 mass% of Cu.

4. 4. The alloy material for a probe pin according to claim 3, further comprising 0.2 mass % to 2.0 mass % of at least one of In, Sn, Zn, and Ga in place of a portion of Cu.

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