JPH04351968A - Probe - Google Patents

Abstract

PURPOSE:To provide an inexpensive probe having abrasion resistance and capable of reducing adhesion of foreign matters significantly. CONSTITUTION:A laminated coat 2 consisting of an adhesive layer 2a and a hard layer 2b is farmed on a probe 1 using stainless as its base material. The adhesive layer 2a as a backing coat of the laminated coat is formed of titanium by means of an ion plating method, and the hard layer 2b as a finish coat is formed of titanium nitride by means of the same method. The adhesive layer 2a can strengthen sticking force between the stainless base material and the hard later 2b, so that the surface of the probe 1 can be coated with the hard laser of the titanium nitride having excellent electrical conductivity.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe which is an electrical contact terminal attached to the tip of a tester for testing electrical conductivity of printed circuit boards, semiconductor parts, etc.

0002

BACKGROUND OF THE INVENTION Conventional probes are known in which a coating of noble metals such as gold, platinum and rhodium is applied to the surface of a copper or copper alloy base material to prevent oxidation. However, ■Since both the base material and the coating are soft, repeated contact may cause the surface to wear out, or ■solder or silver from the object to be inspected may adhere to the prober, causing the insulating properties to deteriorate. It becomes garbage and causes poor contact. ■Furthermore, when attempting to remove dust from the tip of the prober, the noble metal coating for oxidation prevention also fell off, making it unsustainable for long-term use. In addition, since precious metals are used,
There was also the problem of high costs.

0003

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned problems.
The aim is to provide an inexpensive probe.

0004

[Means for solving the problem] The above object is to provide a probe having a special coating on a base material, in which the base material is made of a relatively hard conductive material, and the special coating is made of a relatively hard conductive metal. This is achieved by a probe characterized in that it is a laminated film consisting of a top film containing a compound as a main component and a metal base film that is a component of the metal compound.

[0005]

[Function] The probe constructed as described above has improved wear resistance, less adhesion of solder, silver, etc., long life, and low cost.

[0006]

[Embodiment] Next, an embodiment will be explained with reference to the drawings. FIG. 1 shows an enlarged sectional view of a probe 1 according to an embodiment of the present invention and a lead wire 3 of a light emitting diode as a test material for confirming its performance.

[0007] The probe 1 has a conductive and relatively hard laminated film 2 formed on the surface of a metal base material. FIG. 2 shows an enlarged cross-sectional view of the coated laminated film 2. An adhesive layer 2a made of titanium (Ti), which is a base film, is formed on the surface of stainless steel (SUS304), which is conductive and harder than brass. A hard layer 2b mainly made of titanium nitride (TiN) is formed thereon as an upper film. Both titanium and titanium nitride are electrically conductive and hard. Furthermore, oxidation of the probe can be prevented.

The laminated film 2 was formed on the surface of the base material by ion plating as described below. A vacuum exhaust system (not shown) via an exhaust valve 6 as shown in FIG.
The probe 1 was attached to a support plate 10 provided in a vacuum layer 5 connected to the vacuum layer 5. A water-cooled copper hearth 7 containing titanium (Ti) as an evaporative substance at a position facing the probe 1
and a hollow cathode type electron gun 8. Further, nitrogen gas is supplied from another nozzle 9 as a reactive gas.

First, the inside of the vacuum layer 5 is evacuated to form a 5×1
The pressure was set at 0-5 Torr. Next, while flowing argon gas through the hollow cathode type electron gun 8 (at 5 x 10-4 Torr), a voltage is applied between the water-cooled copper hearth 7 and the electron gun 8 using a DC power source RF starter (DC/RF) to heat the hollow cathode type electron gun 8. When cathodic discharge was generated to evaporate titanium and a bias voltage of -50V was applied to the support plate 10, a titanium film was formed on the surface of the probe. Next, nitrogen gas was introduced from the nozzle 9 to adjust the internal vacuum to 2 x 10-3 Torr, and a titanium nitride (TiN) film was further formed on the probe. When examined by X-ray diffraction, this film was found to be mainly composed of titanium nitride (TiN), and also contained titanium (Ti). The thickness of the titanium coating of the adhesive layer 2a obtained by the above method is several tenths of μm.
The thickness of the hard layer 2b mainly made of titanium nitride was about 2 μm. The film formation rate during the above process is 0.1 to 0.3 μm/
It was min. Moreover, the hard layer 2b of the obtained probe 1
The hardness was measured from above using a micro Vickers hardness meter and found to be approximately HV 1400.

[0010] As described above, by providing the adhesive layer 2a, the adhesive strength of the coating is increased. If the hard layer 2b is directly formed without providing the adhesive layer 2a, the adhesive strength will be weak and it will peel off during use. It was sufficient that the thickness of the adhesive layer was 1 μm or less.

The conventional probe and the probe of this embodiment were each incorporated into a light emitting diode light emitting test device, and the following comparative experiment was conducted.

[0012] A conventional probe has a laminated film of nickel (Ni) and gold (Au) formed on the surface of a brass metal pin by wet plating. As shown in Figure 1, press the probe against the lead wire 3 of the light emitting diode with a constant load,
One cycle consisted of passing the current several times, and 100 cycles were performed each time. The contact surfaces of the conventional probe and the probe of this example after the experiment are shown in FIGS. 4A and 4B, respectively. As shown in FIG. 4A, the conventional probe has solder adhesion on its surface, and a black part can be seen in a part of the adhesion part. In addition, black areas were observed in addition to the adhered areas. These black parts are thought to be caused by the gold coating being peeled off from the probe due to the load of the contacting probe, and the nickel or brass being oxidized. Furthermore, it is thought that dust and solder from the outside are also attached.

On the other hand, the probe obtained in this example had no discoloration, as shown in FIG. 4B, and was completely the same as the initial state. Furthermore, there was no difference in the characteristics of the light emitting diode compared to when a conventional probe was used.

[0014] In addition, with conventional probes, after 100 cycles of experiment, there were 3 cases where problems occurred in the contact part.
%, but no problem occurred with the probe of this example.

Next, the following experiment was conducted to examine whether there is a difference in electrical characteristics between the two probes.

A constant voltage is applied to each of the conventional probe and the probe of this embodiment in the initial state, and the load resistance is changed to zero.
．． When a current of 0.092 to 0.75 mA was applied and the correlation coefficient was determined, a value of 0.999 was obtained, and no difference in electrical characteristics was observed between the two probes.

FIG. 5 shows an example in which 0.38 to 0.75 mA is plotted.

Note that the probe of this example is made of stainless steel (
Since it has a structure in which the laminated coating 2 of titanium and titanium nitride is formed only on the head surface of the base material (SUS304), the lower part of the probe where no coating is provided can be soldered (titanium nitride has no coating). cannot be soldered).

When the probe of the present invention was subsequently subjected to a continuous test of 5000 cycles, only a slight discoloration was observed. When I rubbed this with sandpaper, only the discolored parts were removed and it looked like new.

[0020] The discolored part is where the solder adheres to the titanium nitride film and then oxidizes. By rubbing it with sandpaper, the solder on the titanium nitride film comes off cleanly. Since the titanium nitride film is harder than sandpaper, Since it will not fall off, the surface of the probe will be as good as new.

[0021] As described above, the present invention exhibited characteristics that were much superior to conventional products.

Suitable metal compounds for the present invention are those that are relatively hard and highly conductive. Figure 6 is a diagram showing the relationship between the hardness and melting point of various compounds, and Figure 7 is a diagram showing the electrical resistivity of various compounds. about 10
-4Ω・cm or less, specifically titanium (T
i) Nitride, carbide or boride of hafnium (Hf), tantalum (Ta), nickel (Ni), niobium (Nb), vanadium (v), zirconium (Zr) can be used. All of these are difficult to oxidize and are also effective in preventing oxidation of the base material.

The following experiment was conducted under exactly the same conditions as in the previous example except that the titanium and nitrogen gases were changed. The same applies to the use of stainless steel (SUS304) as the base material.

(1) Using titanium (Ti) as the metal,
Methane gas was introduced instead of nitrogen gas to form an adhesion layer made of titanium and a hard layer mainly made of titanium carbide (TiC).

(2) Hafnium (Hf) was used instead of titanium as the metal, and nitrogen gas was introduced to form an adhesive layer made of hafnium and a hard layer mainly made of hafnium nitride (HfN).

(3) Nickel (Ni) was used instead of titanium as the metal, and nitrogen gas was introduced to form an adhesive layer made of nickel and a hard layer mainly made of nickel nitride (Ni3 N2).

(4) Using titanium (Ti) as the metal,
3~ Titanium (Ti) film on stainless steel (SUS304)
A hard layer mainly made of titanium boride (TiB) was formed on the surface of the titanium film by forming a layer with a thickness of 5 μm and implanting boron by ion implantation.

[0028] Using the probe on which the laminated film was formed as described above, the operation of making the light emitting diode conductive was repeated, but as in the previous example, there was no discoloration or adhesion, and good results were obtained. It was done.

Although the embodiments of the present invention have been described above, the present invention is of course not limited thereto, and various modifications can be made based on the technical idea of the present invention.

For example, in the embodiment, the laminated film was formed by an ion plating method, but a sputtering method may also be used.

The material and thickness of the laminated coating can be selected depending on the purpose, taking into consideration hardness and electrical properties, and the thickness can be varied within the range of a few tenths of a micrometer to 10 micrometers.

The material of the probe is stainless steel (
SUS304) was used, but iron alloys other than stainless steel, nickel alloys, copper alloys, aluminum alloys, tungsten, and molybdenum can also be used instead.

[0033]Although the laminated film consists of an adhesive layer and a hard layer, if it is necessary to improve the compatibility with the object to be measured, a gold or platinum film may be further formed on top of it. good. In this case, the film thickness is 100 to 80% by vapor deposition or sputtering.
The thickness may be approximately 0 Å.

In addition, although the plunger styles shown in FIGS. 1 and 2 were used in the embodiment, plunger styles shown in A, B, and C of FIG. 8 may also be used.
Of course, the present invention can also be applied to shapes other than those shown here.

[0035]

[Effects of the Invention] Since the present invention has the above configuration,
It is difficult for foreign matter such as solder or dust to adhere to the probe surface, and even if it does adhere to it after long-term use, the probe surface is hard and can be easily removed by simply rubbing it with sandpaper. The surface of the probe is not worn out thereby, and a probe with a long life and no problems with electrical characteristics can be obtained at low cost. Furthermore, the parts of the probe of the present invention that are not coated with the special coating can be soldered, making it easy to use.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a probe according to an embodiment of the present invention and a lead wire of a light emitting diode in contact with the probe.

FIG. 2 is a cross-sectional view of the laminated coating of the probe in FIG. 1, further enlarged.

FIG. 3 is a schematic diagram of an apparatus for forming a laminated film.

FIGS. 4A and 4B show the contact surfaces of the conventional probe and the probe of the embodiment of the present invention after conducting continuity tests 100 times;

FIG. 5 is a graph comparing electrical characteristics of a conventional probe and a probe of an embodiment of the present invention.

FIG. 6 is a diagram showing the relationship between hardness and melting point of various compounds.

FIG. 7 is a diagram showing the electrical resistivity of various compounds.

FIGS. 8A, 8B, and 8C are diagrams showing some typical shapes of probes other than this example.

[Explanation of symbols]

1 Probe 2 Laminated film 2a Adhesion layer 2b Hard layer

Claims (3)

[Claims] 1. A probe in which a special coating is applied to a base material, wherein the base material is made of a relatively hard conductive material, and the special coating is a top coat containing a relatively hard conductive metal compound as a main component. A probe characterized in that it is a laminated film consisting of a base film of a metal which is a component of the metal compound. 2. The probe according to claim 1, wherein the base material is any one of copper alloy, iron alloy, nickel alloy, aluminum alloy, tungsten, and molybdenum. 3. The metal is any one of titanium, tantalum, nickel, niobium, vanadium, zirconium, and hafnium, and the metal compound is a nitride, carbide, or boride of the metal. Or the probe according to 2.