Alloy material for probe pins

Abstract

To provide an alloy material for probe pins that can suppress the diffusion of components of a probe material and solder at a circuit connection to be tested during a probe test.SOLUTION: An alloy material for probe pins comprises 15-60 mass% of Pd, 3-79.9 mass% of Cu, and 0.1-75 mass% of Ni and / or Pt.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Sockets and probe cards with multiple probes built in 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 built in the socket or probe card with the electrodes, terminals, and 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 used include beryllium copper alloy, tungsten, tungsten alloy, platinum alloy, and palladium alloy.

[0004] Patent Document 1 discloses a palladium alloy (hereinafter, AgPdCu alloy) composed of 16% to 50% copper, approximately 35% to 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, when the probe pin and solder repeatedly come into contact during testing and electricity is passed through them, the resulting Joule heat can cause mutual diffusion of solder components, such as Sn, and probe material components, which tends to accelerate wear of the probe pin tip. In such cases, contact resistance can fluctuate suddenly or over time, resulting in test defects. This necessitates 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 probe materials that are solder-resistant and suppress 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 the circuit connection portion of the test object during probe testing. [Means for solving the problem]

[0009] The present invention has been completed by discovering a probe material characterized by comprising 15 to 60 mass % Pd, 3 to 79.9 mass % Cu, and 0.1 to 75 mass % Ni and / or Pt. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a probe material that suppresses diffusion of components of the probe material and solder at the circuit connection portion of the test object during testing. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention is a probe material characterized by comprising 15 to 60 mass% Pd, 3 to 79.9 mass% Cu, and 0.1 to 75 mass% Ni and / or Pt (0.1 to 75 mass% in total when Ni and Pt are contained).

[0012] Pd has excellent corrosion resistance, but if it is less than 15 mass%, the corrosion resistance becomes insufficient. On the other hand, if Pd exceeds 60 mass%, it is not suitable because it cannot sufficiently suppress the diffusion of the components of the solder and probe material.

[0013] In another embodiment, the Pd content can be 17 to 55 mass %. In another embodiment, the Pd content can be 20 to 50 mass %.

[0014] Cu has low resistivity and, when alloyed with Pd, has the effect of improving hardness. However, adding large amounts of Cu reduces corrosion resistance. Therefore, if the Cu content is less than 3 mass%, sufficient hardness cannot be obtained, and if the Cu content exceeds 79.9 mass%, corrosion resistance decreases.

[0015] In another embodiment, the Cu content can be 5 to 74 mass %.

[0016] Adding Ni and / or Pt to an alloy has the effect of improving the alloy's solder resistance. Experiments have shown that a content of less than 0.1 mass% is not sufficient to suppress the diffusion of components in the solder and probe material, and that a content of more than 75 mass% is not appropriate because it increases the resistivity.

[0017] In another embodiment, the content of Ni and / or Pt can be 0.3 to 70 mass% (0.3 to 70 mass% in total when Ni and Pt are contained). In another embodiment, the content of Ni and / or Pt can be 0.5 to 65 mass% (0.5 to 65 mass% in total when Ni and Pt are contained).

[0018] It is important for the alloy of the present invention to suppress the phenomenon of wear at the tip of the probe pin due to the diffusion of components of the solder and probe material, and so hardness is not required to be as high as that of existing AgPdCu alloys. In other words, since the solder that the probe pin comes into contact with (e.g., Sn-Bi solder) has a relatively low hardness, the hardness required for the probe material is only 200 HV or more.

[0019] It is presumed that the reason why the diffusion of components of the solder and probe material is suppressed in the alloy of the present invention is as follows: Namely, the Ni and / or Pt added to the probe material forms a thin and dense intermetallic compound layer such as Sn-Ni and / or Sn-Pt at the interface where the solder and probe pin come into contact, and this intermetallic compound layer has the effect of preventing the diffusion of components of the solder and probe material, and is thought to prevent the probe pin tip from being easily worn out. [Example]

[0020] Examples of the present invention will be described below. Table 1 shows the alloy compositions and properties of the examples and comparative examples.

[0021] First, Pd, Cu, Ni, and Pt were mixed to obtain the compositions shown in Table 1, and then melted in an argon atmosphere by arc melting to prepare alloy ingots.

[0022] The above alloy ingot was repeatedly rolled and heat treated to produce a plate material with a rolling ratio [= ((thickness before rolling - thickness after rolling) / thickness before rolling) x 100] of 75%, which was used as a test piece for evaluating hardness and solder resistance. For the resistivity, a plate material processed to a rolling ratio [= ((thickness before rolling - thickness after rolling) / thickness before rolling) x 100] of 90% was used as a test piece.

[0023] The test pieces of each alloy prepared were evaluated as follows, and the results are shown in Table 2.

[0024] The hardness was measured at the center of the cross section of the test piece using a micro Vickers hardness tester under the conditions of a load of 200 gf and a holding time of 10 seconds.

[0025] To measure solder resistance, Sn-Bi solder was placed on the prepared test piece 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.

[0026] 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 rated as ◎, alloys with a diffusion layer thickness of 100 to 200 μm as 〇, alloys with a thickness of 200 to 500 μm as △, and alloys with a thickness of more than 500 μm as ×. The evaluation results are shown in Table 2. However, when the diffusion layer thickness was 800 μm or more, the diffusion layer was formed over almost the entire tested solder, so it was simply recorded as 800 μm.

[0027] The resistivity was calculated by measuring the electrical resistance of each sample at room temperature and using Equation 1. Equation 1: Resistivity = (electrical resistance x cross-sectional area) / measurement length

[0028] [Table 1]

[0029] [Table 2]

[0030] 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 and resistivity required for a probe material. Therefore, the present invention makes it possible to provide a material that is suitable as a solder-resistant probe material.

Claims

[Claim 1] An alloy material for probe pins, characterized by comprising 15-60 mass% Pd, 3-79.9 mass% Cu, and 0.1-75 mass% Ni and / or Pt.

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