JPH0658372U - Probe needle - Google Patents

Abstract

(57) [Abstract] [Purpose] It has good workability and can easily handle small diameters, and has high durability due to its high Young's modulus and mechanical strength. A highly reliable probe needle having a stable contact resistance. [Structure] A work-hardened and age-hardened cobalt-based alloy containing 20 to 60% by weight of cobalt is used. This alloy is processed into a linear shape by general drawing processing or the like. At this time, the final cold drawing work rate is 40% or more. This wire is straightened, cut into a predetermined length, and then the IC
One end on the side of contact with the chip is processed into a tapered shape by a general method such as centerless. Then, if necessary, an aging treatment is performed in a temperature range of 200 ° C to 600 ° C.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a probe needle, and is effectively applied to, for example, a probe needle for a probe test of an IC chip.

[0002]

[Prior art]

 The probe needle for the probe test is made of tungsten, palladium alloy or beryllium copper having a wire diameter of about 0.3 mm to 0.2 mm. Fig. 2 shows a vertical sectional view of a general probe needle. At the base of the probe needle that is soldered to the circuit board, a metal plating layer with good solderability is formed. Table 1 shows the characteristics of various probe needles.

[0003]

[Table 1]

[0004]

[Problems to be solved by the device]

 The probe needle used for the probe test of the IC chip is required to have stable characteristics and long durability life under the severe usage condition that the IC pad is repeatedly contacted several hundreds of times to several millions times. . Also, with the recent high-density integration of ICs, probe cards are also shifting to multi-pins, and the probe needles incorporated therein are becoming smaller in diameter. Under such circumstances, there is an increasing demand for probe needles having good workability and stable characteristics, which can replace the conventionally used tungsten, palladium alloy, and beryllium copper.

As a current problem, since the tangsten mainly used for the probe needle of the aluminum pad IC has a strong fiber structure, when the tip of the probe needle is bent at an angle of about 100 degrees, it is vertically split. It has the drawback of being easy. In addition, the base of the probe needle is plated with nickel or the like to improve solderability with the circuit board.However, due to the poor adhesion of the plating, the reliability of soldering is low and the probe needle is It may come off the board.

Next, a palladium alloy mainly used for a probe needle of a gold pad IC is difficult to handle because it has a low Young's modulus and a low tensile strength and is easily deformed. Also, the hardness is low and the abrasion resistance is insufficient. Beryllium copper is similar to the palladium alloy. The purpose of this invention is to improve workability and easily cope with diameter reduction, to have high durability due to high Young's modulus and mechanical strength, and to have good solderability due to good plating adhesion. Another object of the present invention is to provide a probe needle having a high and stable contact resistance.

[0007]

[Means for Solving the Problems]

 The probe needle of this invention has good workability, high mechanical strength, and excellent elasticity and wear resistance. A work-hardening and age-hardening type cobalt-based alloy containing 20 to 60% by weight of cobalt is used. This alloy is processed into a linear shape by general wire drawing. At this time, in order to obtain mechanical strength, the final cold drawing work rate is set to 40% or more. This wire is straightened, cut into a predetermined length, and then one end on the side to be brought into contact with the IC chip is processed into a tapered shape by a general method such as centerless. Then, if necessary, by performing an aging treatment in a temperature range of 200 ° C to 600 ° C, it is possible to obtain higher mechanical strength.

Next, a metal plating layer having good solderability and conductivity is formed on the entire surface by a general plating method. FIG. 1 shows a longitudinal sectional view of the probe needle of the present invention. 3 is a cobalt-based alloy that is the main body of the probe needle, and 4 is a metal plating layer with good solderability and conductivity.

[0009]

[Action]

 By using the above means, it is possible to provide a probe needle that can be easily processed to have a wire diameter of about 0.3 mm to 0.1 mm, and that has high durability and stable characteristics.

[0010]

【Example】

 Using the cobalt-based alloys having the chemical components shown in Table 2, Material A, Material B, and Material C, a wire having a wire diameter of 0.2 mm is processed by a general drawing method. The final cold wire drawing working ratio was 70%. After straightening, cut into a length of 40 mm. Next, one end is processed by centerless polishing into a tapered shape with a tip diameter of 20 μm and an angle of 4 degrees, and the tip of the tapered portion is bent to an angle of 103 degrees. Then, an aging treatment of 500 ° C. × 2H is performed using a vacuum heat treatment furnace.

Next, a wet process is performed to perform nickel undercoating with a thickness of 0.5 μm, and gold plating is performed thereon with a thickness of 0.2 μm. The plating material is not limited to nickel or gold as long as it is a metal having good solderability and conductivity, and the plating thickness is not limited to the thickness described here. Table 3 shows the characteristics of the probe needles obtained at this time.

[0012]

[Table 2]

[0013]

[Table 3]

The probe needle processed in this manner was incorporated into a probe card, and a probe test was conducted under the condition that the tip of the probe needle was bitten 50 μ into the pad of the IC chip. Table 4 shows the contact resistance value for each contact frequency with the gold pad IC and the aluminum pad IC.

[0015]

[Table 4]

Due to the high mechanical strength and fatigue strength of the cobalt-based alloy, a stable needle pressure can be obtained at all times, and since there is no adhesion of oxides etc. at the tip of the needle, it can be applied to both gold and aluminum pads. It also shows a very stable contact resistance. In addition, because of the good adhesion of the plating layer, solder did not peel off during the probe test and the probe needle did not come off from the circuit board.

[0017]

[Effect of device]

 As described above, the present invention has an effect that it is possible to provide an inexpensive probe needle that has stable contact resistance, high durability, and good wire drawing workability.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a probe needle of the present invention.

FIG. 2 shows a vertical cross-sectional view of a conventional probe needle.

[Explanation of symbols]

 3 Cobalt-based alloy 4 Metal plating layer

Claims (3)

[Scope of utility model registration request] 1. A probe needle comprising a work-hardening and age-hardening type cobalt-based alloy containing 20 to 60% by weight of cobalt, and having a metal plating layer having good solderability and good conductivity formed on the surface thereof. 2. The probe needle according to claim 1, wherein the cold drawing ratio is 40% or more in order to obtain mechanical strength. 3. The probe needle according to claim 2, wherein the probe needle is aged at a temperature of 200 ° C. to 600 ° C. to obtain higher mechanical strength.