JP2022060711A - Contact probe - Google Patents

Abstract

To provide a contact probe capable of reliably contacting an inspection point of an object to be measured with a tip portion thereof, and preventing the inspection point of the object to be measured from being scraped or scratched.SOLUTION: In a contact probe 10 that has a body portion 14 having an insulating coating 12 on the outer periphery of a metal conductor 11 and an end portion 16 having no insulating coating 12 formed at both ends of the metal conductor 11, and that measures electrical characteristics by obtaining contact pressure with respect to an object to be measured 20 by applying a load in the axial direction and bending, the shape of the end portion 16 on the side of the end portion 16 that comes into contact with the object to be measured 20 is a curved surface, and by taking a curvature radius of the curved surface for R and a diameter of the metal conductor 11 for D, R is in the range of more than 0.5D and less than 5D.SELECTED DRAWING: Figure 3

Description

The present invention relates to an inspection contact probe used for inspecting electrical characteristics of electronic components and substrates.

In recent years, various circuit boards such as high-density mounting boards used for smartphones and mobile phones, and IC package boards such as BGA (Ball Grid Array) and CSP (Chip Size Package) incorporated in personal computers have been used. ing.
In the processes before and after mounting these circuit boards, for example, DC resistance value measurement, continuity inspection, and the like are performed, and the quality of their electrical characteristics is inspected.

For example, as shown in Patent Document 1, the quality of electrical characteristics is inspected using a jig for an inspection device (hereinafter, may be referred to as a probe unit) connected to the inspection device.
Specifically, a pin-shaped contact probe attached to the tip of a probe unit on an electrode (hereinafter, may be referred to as an inspection point) of a circuit board to be measured (hereinafter, may be referred to as a measured object). It is done by contacting the tips of the.

Patent Document 2 describes that the shape of the tip of the contact probe can be appropriately selected from a hemispherical shape, a conical shape, a conical shape having a hemispherical shape at the tip, and a conical shape having a flat shape at the tip. Has been done.

Patent Document 3 describes a contact probe having a flat tip.

Japanese Unexamined Patent Publication No. 2002-131334 Japanese Unexamined Patent Publication No. 2007-322369 Japanese Unexamined Patent Publication No. 2013-024716

If the shape of the tip of the contact probe is hemispherical as in Patent Document 1 and Patent Document 2 described above, the tip of the contact probe slips too much from the inspection point of the object to be measured, and the tip of the contact probe However, there is a risk that accurate inspection cannot be performed because it does not come into contact with the inspection point.

Further, as in Patent Document 2, when the shape of the tip portion of the contact probe is a conical shape, a conical shape having a hemispherical shape at the tip, and a conical shape having a flat shape at the tip, the inspection point of the object to be measured is used. Since the contact area becomes small, it may be difficult to inspect by contacting the tip of the contact probe with each inspection point due to the recent narrowing of the pitch of the electrodes.

Further, as in Patent Document 3, when the shape of the tip of the contact probe is flat, the contact area with the inspection point of the object to be measured is sufficient, but the edge portion perpendicular to the tip of the contact probe. If this edge portion comes into contact with the inspection point, the inspection point may be scraped or scratched.

Therefore, the present invention has been made to solve the above problems, and an object thereof is that the tip of the contact probe can surely come into contact with the inspection point of the object to be measured, and the inspection point of the object to be measured is scraped or scratched. The purpose is to provide a contact probe that reduces wearing.

According to the contact probe according to the present invention, the body portion having an insulating coating on the outer periphery of the pin-shaped metal conductor and the end portions formed at both ends of the metal conductor without the insulating coating are provided, and the axis line is provided. In a contact probe for measuring electrical characteristics by obtaining a contact pressure with respect to an object to be measured by applying a load in a direction and bending the contact probe, the shape of at least the end of the end portion on the side in contact with the object to be measured is a curved surface. When the radius of curvature of the curved surface is R and the diameter of the metal conductor is D, R is characterized in that it is in the range of more than 0.5D and 5D or less.
By adopting this configuration, the end portion in contact with the object to be measured can have a curved surface close to a nearly flat shape, so that the edge does not slip too much when in contact with the inspection point of the object to be measured, and the edge. Since the parts are no longer at right angles, surface contact can be made with respect to the inspection point, and the inspection point can be prevented from being scraped or scratched.

Further, the radius of curvature R may be D or more.

Further, the metal conductor may be characterized in that the diameter is 8 μm or more and 180 μm or less.

According to the present invention, it is possible to provide a contact probe that can reliably contact the inspection point of the object to be measured and that can prevent the inspection point of the object to be measured from being scraped or scratched.

It is a schematic plan view of a contact probe. It is explanatory drawing which shows the use mode of a contact probe. It is an enlarged view of the end part of a contact probe. It is explanatory drawing which shows the place where the end of a contact probe comes into contact with two inspection points. It is a table summarizing the results when the slip test and the scratch test were carried out by changing the shape of the end part. It is explanatory drawing which shows the shape of the corresponding end part in the table of FIG.

Hereinafter, embodiments of the contact probe of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic plan view of the contact probe, and FIG. 2 is an explanatory view when inspecting the electrical characteristics of the object to be measured is performed using the contact probe.

The contact probe 10 is made of an extremely thin columnar (pin-shaped) metal conductor 11 having a circular cross section, and has a body portion 14 having an insulating coating 12 on the outer periphery of the metal conductor 11. Ends 16 having no insulating coating 12 are formed at both ends of the metal conductor 11.
The contact probe 10 is configured to obtain a contact pressure with respect to the object to be measured and inspect the electrical characteristics by applying a load in the axial direction and bending the contact probe 10.

(Inspection method of electrical characteristics using contact probe)
The usage mode of the contact probe will be described with reference to FIG.
In the example shown here, the IC package substrate or the like is used as the object to be measured 20, and a plurality of electrodes formed on the surface of the object to be measured 20 are used as inspection points 22, and the end portion of the contact probe 10 with respect to the inspection point 22. 16 is brought into contact.

The probe unit 30, which is a jig for inspection, has a plurality of contact probes 10.
The probe unit 30 has an upper plate 32 that holds the upper end portions of the plurality of contact probes 10 and a lower plate that guides the lower end portions of the contact probe 10, and is supported between the upper plate 32 and the lower plate 34. It is supported by the pillar 36.
A guide hole having a diameter slightly larger than that of the lower end of the contact probe 10 is formed in the lower plate 34, and the lower end of the contact probe 10 can move in the guide hole in the axial direction.
Further, a plurality of lead wires 37 electrically connected to the upper end portions of the plurality of contact probes 10 are arranged on the upper plate 32. The plurality of lead wires 37 are connected to a measuring instrument (not shown) or a power source (not shown).

As shown in the right figure of FIG. 2, the probe unit 30 is arranged above the body to be measured 20 so that the lower end of each contact probe 10 faces the position of each inspection point 22 of the body to be measured 20.
Then, the probe unit 30 is lowered so that the lower end of each contact probe 10 comes into contact with each inspection point 22 of the object to be measured 20, and the probe unit 30 is directed downward from above as shown in the right figure of FIG. Pressurize.
Then, a load is applied along the axial direction of the contact probe 10, and the contact probe 10 bends. At this time, the end portion 16 of the contact probe 10 comes into contact with the inspection point 22 at a predetermined contact pressure due to the elastic force caused by the bending of the contact probe 10.

(Metal conductor)
As the metal conductor 11, a metal wire (also referred to as a metal spring wire) having high conductivity and high elastic modulus is used. As the metal material used for the metal conductor 11, copper alloys such as tungsten, renium tungsten and beryllium copper, palladium alloys, copper-silver alloys and the like can be preferably used.

A plating layer is provided on the surface of the metal material of the metal conductor 11 as necessary in order to suppress an increase in the contact resistance value between the metal conductor 11 and the inspection point 22 of the object to be measured 20 or the lead wire 37 of the inspection device. It may be provided. Examples of the metal forming the plating layer include metals such as nickel, gold and rhodium, and alloys such as gold alloys. The plating layer may be a single layer or a plurality of layers. As the multi-layered plating layer, for example, one in which a gold plating layer is formed on a nickel plating layer can be preferably mentioned. The thickness of the plating layer is not particularly limited, but may be, for example, 1 μm or more and 5 μm or less.

The conductor diameter of the metal conductor 11 of the present embodiment has been required to be reduced due to the recent demand for narrower pitch, and a conductor having a diameter of 8 μm or more and 180 μm or less can be preferably used. More preferably, a conductor diameter in the range of 10 μm or more and 110 μm or less can be used.
The metal conductor 11 is manufactured by plastic working such as cold or hot wire drawing so as to be a pin-shaped conductor having a predetermined diameter.

The metal conductor 11 is used so that the contact probe 10 can be easily attached to the probe unit 30 and the movement of the contact probe 10 is not hindered without being caught in the guide hole of the lower plate 34 of the probe unit 30. It is preferable that the straightness is high, and specifically, the straightness is preferably 1000 mm or more in radius of curvature.
The metal conductor 11 having high straightness is obtained by straightening the long metal wire before providing the insulating film 12. The straight line straightening process is performed by, for example, a rotary die type straight line straightening device or the like.

(edge)
One end 16 of both ends of the metal conductor 11 comes into contact with the inspection point 22 of the object 20 to be measured.
As shown in FIG. 3, the contact probe 10 of the present embodiment has a curved surface having at least the shape of the end portion 16 of both ends of the metal conductor 11 that contacts the inspection point 22 of the object to be measured 20.
Further, when the radius of curvature of this curved surface is R and the diameter of the metal conductor 11 is D, R exceeds 0.5D and is 5D or less (hereinafter, may be expressed as 0.5D <R≤5D). Certain configurations can be preferably used.
However, the curved surface under the above-mentioned conditions is not limited to one end 16, and both ends may be formed on the curved surface under the above-mentioned conditions.

By setting the radius of curvature R of the curved surface of the end portion 16 to 0.5D <R ≦ 5D, the end portion 16 in contact with the inspection point 22 of the object to be measured 20 can be made into a curved surface having a substantially flat shape.
Therefore, when the end portion 16 is brought into contact with the inspection point 22 of the object to be measured 20, it does not slip too much. Further, since the edge portion of the end portion 16 is not at a right angle, it is possible to make surface contact with the inspection point 22, and it is possible to prevent the inspection point 22 from being scraped or scratched. Further, a sufficient contact area with respect to the inspection point 22 can be secured.

As described above, when the diameter of the metal conductor 11 is 8 μm or more and 180 μm or less, for example, the radius of curvature R of the end portion 16 is in the range of 4 μm <R ≦ 40 μm when D = 8 μm, and 90 μm when D = 180 μm. <R ≦ 900 μm.

Further, as shown in FIG. 4, the contact probe 10 of the present embodiment can be suitably used in a case where the contact probe 10 of the present embodiment is arranged between two inspection points 22 in the object to be measured 20. Although the hemispherical inspection point 22 is shown in FIG. 4, the shape of the inspection point 22 is not limited to such a shape.
In this case, the end portion does not slip too much with respect to the hemispherical inspection point 22, and a sufficient contact area with respect to the inspection point 22 can be secured. Further, since the edge portion of the end portion 16 is not at a right angle, surface contact can be made with respect to the inspection points 22, and the two inspection points 22 can be prevented from being scraped or scratched.

The method of forming the end portion 16 of the metal conductor 11 into the above-mentioned shape is performed by grinding the end portion 16 of the metal conductor 11.
Grinding can be performed by using abrasive cloth or by using a diamond wheel. Further, a known grinding machine capable of grinding a pin-shaped metal material may be used.

(Insulation film)
The insulating coating 12 is not particularly limited as long as it is a coating having an insulating property, but is selected from polyurethane resin, nylon resin, polyester resin, epoxy resin, polyesterimide resin, polyamide resin, polyamideimide resin and the like1 A seed or two or more kinds of resin materials can be preferably used.
Further, since the insulating coating 12 made of these resins has different heat resistance depending on the type of resin, it can be arbitrarily selected in consideration of the heat generated during the inspection of the object to be measured 20 or the ambient temperature.

The thickness of the insulating coating 12 may be a thickness sufficient to ensure electrical insulation, and is appropriately set within a range of 1 μm or more and 30 μm or less in consideration of the relationship with the diameter of the metal conductor 11.
The insulating coating 12 is preferably formed on the metal conductor 11 as a baking enamel coating. Since the baked enamel film is formed by a continuous process of repeated coating and baking of the paint, the productivity is good, the adhesion with the metal conductor 11 is high, and the film strength can be made higher.

In this embodiment, a region is formed in which the insulating coating 12 is removed from each end 16 of the metal conductor 11 by a predetermined length. The length of the region from which the insulating coating 12 is removed is appropriately set based on the structure of the probe unit 30 and the like.

(Example)
In the following examples, a long rhenium tungsten wire (outer diameter D: 0.025 mm) was used as the metal conductor 11.
The insulating coating 12 had a two-layer structure, and a urethane resin-based enamel paint was used as the first insulating coating for the first insulating coating, and the first insulating coating was formed with a thickness of 1 μm. The second insulating coating used the same enamel paint as the first insulating coating, and contained 4 parts by weight of a pigment (manufactured by BASF Japan Co., Ltd., trade name: Irgazin (registered trademark)) in 100 parts by weight of the enamel paint. The enamel paint for the second insulating film was used, and the second insulating film was formed with a thickness of 2.5 μm.

A long contact probe having an insulating coating 12 (total thickness of about 3.5 μm) is cut with a standard cutting machine to cut out a contact probe with an insulating coating having a length of 10 mm, and both ends of the contact probe with an insulating coating are cut out. The contact probe 10 having the appearance shown in FIG. 1 was produced by laser peeling off the predetermined length of the above.
When the metal conductor 11 was machined by the grinding apparatus, the shape of the end portion 16 was adjusted by appropriately adjusting the grinding angle, time, and the like.

Further, a nickel plating layer having a thickness of 1 μm is provided on the surface of the metal conductor 11 exposed by peeling the insulating film 12, and then a gold plating layer having a thickness of 0.2 μm is further provided on the nickel plating layer. A plating layer having a thickness of 1.2 μm was formed.

FIG. 5 shows the results of evaluation of slippage of the end portion 16 with respect to the inspection point 22 and scratches at the inspection point 22 when the radius of curvature R of the curved surface of the curved surface of the end portion 16 of the contact probe 10 is changed according to the above-described embodiment. show. In this embodiment, the diameter D of the metal conductor 11 is constant.
As Comparative Example 1, the case where the radius of curvature R of the end portion was 0.5D, the case where the end portion had a flat shape as Comparative Example 2, and the case where the end portion had an acute angle were evaluated as Comparative Example 3.

Incidentally, FIG. 6 illustrates an outline of the end shape of the contact probe 10 in the examples and comparative examples of FIG.
In FIG. 6A, the end portion is a curved surface.
FIG. 6B has a flat end portion.
FIG. 6C has an acute-angled end.

As a method for evaluating slippage, a contact test between the end portion 16 of the contact probe 10 and the object to be measured 20 is performed 10,000 times, and evaluation A is performed when the number of times slippage occurs is 9 times or less, and evaluation A is performed when the number of times slippage occurs is 10 times or more and 99 times or less. Is evaluated as B, and if it is 100 times or more, it is evaluated as C.

As a method for evaluating scratches, a contact test between the end portion 16 of the contact probe 10 and the object to be measured 20 is performed 10,000 times, and if there are no scratches, evaluation A is performed, and if there are scratches, evaluation B is used.

Hereinafter, each embodiment will be described.
The end of Example 1 is R = 5D, and the corresponding model in FIG. 6 is (A). The slip evaluation in Example 1 was A, and the scratch evaluation was A.

The end of Example 2 is R = 4D, and the corresponding model in FIG. 6 is (A). The slip evaluation in Example 2 was A, and the scratch evaluation was A.

The end of Example 3 is R = 3D, and the corresponding model in FIG. 6 is (A). The slip evaluation in Example 3 was A, and the scratch evaluation was A.

The end of Example 4 is R = 2D, and the corresponding model in FIG. 6 is (A). The slip evaluation in Example 4 was A, and the scratch evaluation was A.

The end of Example 5 is R = 1.5D, and the corresponding model in FIG. 6 is (A). The slip evaluation in Example 5 was A, and the scratch evaluation was A.

The end of Example 6 is R = D, and the corresponding model in FIG. 6 is (A). The slip evaluation in Example 6 was A, and the scratch evaluation was A.

The end of Example 7 is R = 0.9D, and the corresponding model in FIG. 6 is (A). The slip evaluation in Example 7 was B, and the scratch evaluation was A.

The end of Example 8 is R = 0.7D, and the corresponding model in FIG. 6 is (A). The slip evaluation in Example 8 was B, and the scratch evaluation was A.

The end portion of Comparative Example 1 has R = 0.5D, and the shape is the same as that of Examples 1 to 8, but the radius of curvature is larger than that of Examples 1 to 8. The slip evaluation in Comparative Example 1 was C, and the scratch evaluation was A.

The end portion of Comparative Example 2 has a flat shape, and the corresponding model of FIG. 6 is (B). In Comparative Example 2, the slip evaluation was A and the scratch evaluation was B.

The end of Comparative Example 3 has an acute angle at the tip, and the corresponding model in FIG. 6 is (C). In Comparative Example 3, the slip evaluation was A and the scratch evaluation was B.

From the results of FIG. 5, when the end portion of the contact probe 10 is a curved surface and the radius of curvature R thereof is R ≦ 0.5D as in Comparative Example 1, the slipperiness becomes slippery, so that the slip evaluation may deteriorate. found.
Further, when the end portion of the contact probe has a flat shape as in Comparative Example 2, there is no problem in slip evaluation, but the contact probe is scratched.
Further, when the end portion of the contact probe has an acute angle as in Comparative Example 3, there is no problem in the slip evaluation, but the contact probe is scratched.
Therefore, it has been found that when the end portion of the contact probe 10 is a curved surface and the radius of curvature R thereof is 0.5D <R≤5D, it is not slippery and is not scratched, which is suitable.

The slip evaluation and the scratch evaluation of Examples 1 to 6 were both A. Therefore, it was also found that the range of R in which D ≦ R ≦ 5D is more preferable as in Examples 1 to 6.

10 Contact probe 11 Metal conductor 12 Insulation coating 14 Body part 16 End part 20 Measured body 22 Inspection point 30 Probe unit 32 Upper plate 34 Lower plate 36 Support column 37 Lead wire

Claims (3)

A fuselage with an insulating coating on the outer circumference of a pin-shaped metal conductor,
It has the end portions having no insulating coating formed on both ends of the metal conductor, and has.
A contact probe that measures electrical characteristics by obtaining contact pressure with respect to the object to be measured by applying a load in the axial direction and bending it.
When the shape of at least the end of the end that comes into contact with the object to be measured is a curved surface, the radius of curvature of the curved surface is R, and the diameter of the metal conductor is D, R is 0.5D. A contact probe characterized in that it exceeds 5D or less. The contact probe according to claim 1, wherein the radius of curvature R is D or more. The contact probe according to claim 1 or 2, wherein the metal conductor has a diameter of 8 μm or more and 180 μm or less.

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