CN115427820A

CN115427820A - Contact probe

Info

Publication number: CN115427820A
Application number: CN202180025869.XA
Authority: CN
Inventors: 小路辽太; 深泽雅章; 小泽卓弥
Original assignee: Totoku Electric Co Ltd
Current assignee: TOTOKU Corp.
Priority date: 2020-10-05
Filing date: 2021-07-12
Publication date: 2022-12-02
Also published as: KR20230082598A; WO2022074888A1; TW202229878A; JP2022060711A

Abstract

The present invention addresses the problem of providing a contact probe, the tip of which can reliably contact a checking point of a body to be measured and which can be configured so as not to cut or damage the checking point of the body to be measured. The contact probe (10) is provided with a main body part (14) having an insulating coating (12) on the outer periphery of a metal conductor (11) and end parts (16) which are formed at both ends of the metal conductor (11) and do not have the insulating coating (12), and the contact pressure to a measured object (20) is obtained and the electrical characteristics are measured by applying a load in the axial direction and bending the load, wherein the shape of at least one end part (16) on the side contacting the measured object (20) among the end parts (16) is a curved surface, and when the curvature radius of the curved surface is R and the diameter of the metal conductor (11) is D, the R is in the range of more than 0.5D and less than 5D.

Description

Contact probe

Technical Field

The present invention relates to a contact probe for inspecting electrical characteristics of an electronic component, a substrate, and the like.

Background

In recent years, various circuit boards have been used, for example, high-density mounting boards used in smartphones, mobile phones, and the like, and IC Package boards such as BGA (Ball Grid Array) and CSP (Chip Size Package) mounted in personal computers, and the like.

In the steps before and after mounting, the circuit boards are subjected to, for example, measurement of dc resistance values, conduction inspection, and the like, and are inspected for satisfactory electrical characteristics.

For example, as shown in patent document 1, the inspection of whether or not the electrical characteristics are good is performed using an inspection apparatus jig (hereinafter, sometimes referred to as a probe unit) connected to an inspection apparatus.

Specifically, the tip of a needle-like contact probe attached to the tip of the probe unit is brought into contact with an electrode (hereinafter, referred to as a check point) of a circuit board (hereinafter, referred to as a measurement object) to be measured.

Patent document 2 describes the following: the shape of the tip of the contact probe may be any of a hemispherical shape, a conical shape having a hemispherical shape at the tip, and a conical shape having a flat shape at the tip.

Patent document 3 describes a case where the tip portion of the contact probe has a flat shape.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2002-131334

Patent document 2: japanese patent laid-open No. 2007-322369

Patent document 3: japanese laid-open patent publication No. 2013-024716

Disclosure of Invention

Problems to be solved by the invention

As in

patent documents

1 and 2, if the tip portion of the contact probe has a hemispherical shape, the tip portion of the contact probe may slide too much from the inspection point of the object to be measured, and the tip portion of the contact probe may not contact the inspection point, and accurate inspection may not be performed.

Further, as in patent document 2, when the tip portion of the contact probe has a conical shape, a conical shape having a hemispherical shape at the tip, or a conical shape having a flat shape at the tip, the contact area with the inspection point of the object to be measured is reduced, and therefore, with the recent narrowing of the pitch of the electrodes, it may be difficult to bring the tip portion of the contact probe into contact with each inspection point and perform the inspection.

Further, as in patent document 3, when the shape of the distal end portion of the contact probe is a flat shape, the contact area with the inspection point of the object to be measured is sufficient, but since a right-angled edge portion is formed at the distal end portion of the contact probe, when the edge portion comes into contact with the inspection point, the inspection point may be cut or damaged.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a contact probe in which a distal end portion of the contact probe can reliably contact a detection point of a measurement object and cutting or damage to the detection point of the measurement object is reduced.

Means for solving the problems

The contact probe according to the present invention includes a body portion having an insulating film on an outer periphery of a needle-shaped metal conductor, and end portions formed at both ends of the metal conductor and not having the insulating film, and is configured to be deflected by applying a load in an axial direction to obtain a contact pressure with a measurement object and measure an electrical characteristic, wherein at least an end portion on a side in contact with the measurement object among the end portions has a curved surface shape, and when a radius of curvature of the curved surface is R and a diameter of the metal conductor is D, R is in a range of more than 0.5D and 5D or less.

With this configuration, since the end portion in contact with the object to be measured can be formed into a curved surface having a substantially flat shape, excessive sliding does not occur at the time of contact with the inspection point of the object to be measured, and since the edge portion is not perpendicular to the inspection point, surface contact with the inspection point is possible, and the inspection point can be prevented from being cut or damaged.

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

Further, the metal conductor may have a diameter of 8 μm or more and 180 μm or less.

Effects of the invention

According to the present invention, it is possible to provide a contact probe that can reliably contact a checking point of a measurement object and can prevent the checking point of the measurement object from being cut or damaged.

Drawings

FIG. 1: fig. 1 is a schematic top view of a contact probe.

FIG. 2 is a schematic diagram: fig. 2 is an explanatory diagram illustrating a usage of the contact probe.

FIG. 3: fig. 3 is an enlarged view of the end of the contact probe.

FIG. 4 is a schematic view of: fig. 4 is an explanatory diagram showing the positions of the end portions of the contact probes in contact with the 2-site inspection points.

FIG. 5: fig. 5 is a summary table of the results in the case where the end portion was changed in shape and the sliding test and the damage test were performed.

FIG. 6: fig. 6A to 6C are explanatory views showing shapes of corresponding end portions in the table of fig. 5.

Detailed Description

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 a contact probe, and fig. 2 is an explanatory view of a case where an inspection of electrical characteristics and the like of a measurement object is performed using the contact probe.

The contact probe 10 is composed of a very thin cylindrical (needle-like) metal conductor 11 having a circular cross section, and has a main body 14 having an insulating coating 12 on the outer periphery of the metal conductor 11. End portions 16 having no insulating coating 12 are formed at both ends of the metal conductor 11.

The contact probe 10 is constituted by: the test piece is deflected by applying a load in the axial direction, so that a contact pressure with respect to the body to be measured is obtained and the electrical characteristics are tested.

(method of inspecting electric characteristics Using contact Probe)

The mode of use of the contact probe will be described with reference to FIG. 2.

In the example shown here, an IC package substrate or the like is used as the object to be measured 20, a plurality of electrodes formed on the surface of the object to be measured 20 are used as the inspection points 22, and the end portions 16 of the contact probes 10 are brought into contact with the inspection points 22.

The probe unit 30 as a jig for inspection has a plurality of contact probes 10.

The probe unit 30 has an upper plate 32 holding upper end portions of a plurality of contact probes 10 and a lower plate guiding lower end portions of the contact probes 10, and the upper plate 32 and the lower plate 34 are supported by a support column 36 therebetween.

A guide hole having a diameter slightly larger than the lower end portion of the contact probe 10 is formed in the lower plate 34, and the lower end portion of the contact probe 10 is movable in the axial direction within the guide hole.

Further, a plurality of leads 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 leads 37 are connected to a measuring instrument (not shown) and a power supply (not shown).

As shown in the right drawing of fig. 2, the probe unit 30 is disposed above the measurement object 20 so that the lower end of each contact probe 10 faces the position of each inspection point 22 of the measurement object 20.

Then, the probe unit 30 is lowered so that the lower end portions of the contact probes 10 contact the inspection points 22 of the object 20, and the probe unit 30 is pressed from above to below as shown in the right drawing of fig. 2.

Then, a load is applied in the axial direction of the contact probe 10, and the contact probe 10 is deflected. At this time, the end portion 16 of the contact probe 10 contacts the inspection point 22 with a predetermined contact pressure from an elastic force generated by the deflection 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, a copper alloy such as tungsten, rhenium tungsten, beryllium copper, a palladium alloy, a copper-silver alloy, or the like can be preferably used.

In order to suppress an increase in contact resistance between the metal conductor 11 and the inspection point 22 of the object to be measured 20 or the lead 37 of the inspection device, a plating layer may be provided on the surface of the metal material of the metal conductor 11 as necessary. 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 multilayer plating layer, for example, a plating layer in which a gold plating layer is formed on a nickel plating layer is preferable. The thickness of the plating layer is not particularly limited, and 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 is required to be smaller due to recent demands for narrower pitches, and a conductor diameter of 8 μm or more and 180 μm or less can be preferably used. It is more preferable to use a metal conductor having a conductor diameter in the range of 10 μm or more and 110 μm or less.

The metal conductor 11 is manufactured into a needle-like conductor having a predetermined diameter by plastic working such as cold drawing or hot drawing.

In order to facilitate the attachment of the contact probe 10 to the probe unit 30, prevent the contact probe 10 from being caught by the guide hole of the lower plate 34 of the probe unit 30, and prevent the contact probe 10 from moving, the metal conductor 11 preferably has a high linearity, and specifically, the linearity is preferably set to have a curvature radius of 1000mm or more.

The metal conductor 11 having high linearity can be obtained by performing a straight line correction process on a long metal wire before the insulating film 12 is provided. The straight line correction processing is performed by, for example, a rotary die type straight line correction device.

(end part)

One end 16 of the two ends of the metal conductor 11 is in contact with a detection point 22 of the object to be measured 20.

As shown in fig. 3, the contact probe 10 of the present embodiment has a curved surface at least in the shape of the end 16 that is in contact with the inspection point 22 of the object to be measured 20, among the two ends of the metal conductor 11.

When the curvature radius of the curved surface is R and the diameter of the metal conductor 11 is D, a configuration in which R is greater than 0.5D and not greater than 5D (hereinafter, it may be expressed as 0.5D < R ≦ 5D) may be suitably used.

However, instead of only one end portion 16 being a curved surface under the above-described conditions, both end portions may be curved surfaces under the above-described conditions.

By setting the radius of curvature R of the curved surface of the end portion 16 to 0.5D < R.ltoreq.5D, the end portion 16 that is in contact with the inspection point 22 of the object 20 can be set to a curved surface having a substantially flat shape.

Therefore, the end 16 does not slide excessively when it is brought into contact with the inspection point 22 of the object 20. Further, since the edge portion of the end portion 16 is not perpendicular, it can be brought into surface contact with the inspection point 22, and cutting or damage to the inspection point 22 can be suppressed. Further, a sufficient contact area with the inspection point 22 can be ensured.

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

As shown in fig. 4, the contact probe 10 of the present embodiment can be suitably used when it is disposed in the middle of 2 inspection points 22 in the measurement object 20. In fig. 4, the inspection point 22 having a hemispherical shape is shown, but the shape of the inspection point 22 is not limited to such a shape.

In this case, the end portion does not slide excessively with respect to the inspection point 22, particularly, the hemispherical shape, and a sufficient contact area with the inspection point 22 can be ensured. Further, since the edge portion of the end portion 16 is not perpendicular, it can be in surface contact with the inspection points 22, and 2 inspection points 22 can be prevented from being cut or damaged.

As a method of forming the end portion 16 of the metal conductor 11 into the above-described shape, the end portion 16 of the metal conductor 11 is ground.

The grinding process may be performed by using a grinding cloth or a diamond wheel. In addition, a known grinding machine capable of grinding a needle-like metal material may be used.

(insulating coating film)

The material of the insulating film 12 is not particularly limited as long as it is a film having insulating properties, and 1 or 2 or more resin materials selected from urethane resin, nylon resin, polyester resin, epoxy resin, polyesterimide resin, polyamide resin, polyamideimide resin, and the like can be preferably used.

The insulating film 12 made of these resins has different heat resistance depending on the type of the resin, and therefore can be arbitrarily selected in consideration of the heat generated when the object 20 is inspected and the ambient temperature.

The thickness of the insulating coating 12 may be set as long as it is a thickness sufficient to ensure electrical insulation, and is appropriately set within a range of 1 μm to 30 μm 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 finish coating. Since the baked varnish coating is formed by a continuous process in which coating and baking of the paint are repeated, productivity is good, adhesion to the metal conductor 11 is high, and the coating strength can be made higher.

In the present embodiment, only a region where a predetermined length of the insulating coating 12 is removed from each end 16 of the metal conductor 11 is formed. The length of the region where the insulating coating 12 is removed is appropriately set according to the structure of the probe unit 30 and the like.

(examples)

In the following examples, a long rhenium tungsten wire (outer diameter D:0.025 mm) was used as the metal conductor 11.

The insulating film 12 has a 2-layer structure, and the first insulating film is formed to have a thickness of 1 μm using a urethane resin based enamel paint as a paint for the first insulating film. The second insulating film was formed to a thickness of 2.5 μm using the same enamel paint as the first insulating film and containing 4 parts by weight of a pigment (product name: irgazin (registered trademark) manufactured by BASF Japan) per 100 parts by weight of the enamel paint.

A long contact probe on which an insulating coating 12 (having a total thickness of about 3.5 μm) was formed was cut with a size cutter, and an insulating-coated contact probe having a length of 10mm was cut out, and a predetermined length of both ends of the insulating-coated contact probe was laser-peeled off, thereby producing a contact probe 10 having the configuration shown in fig. 1.

When the metal conductor 11 is machined by the grinding apparatus, the shape of the end portion 16 is adjusted by appropriately adjusting the grinding angle, time, and the like.

Further, a nickel plating layer having a thickness of 1 μm was formed by electroplating on the surface of the metal conductor 11 exposed by peeling off the insulating coating 12, and then a gold plating layer having a thickness of 0.2 μm was further formed thereon to form a plating layer having a total thickness of 1.2 μm.

Fig. 5 shows the results of evaluating the sliding of the end portion 16 with respect to the inspection point 22 and the damage at the inspection point 22, in the case where the radius of curvature R of the curved surface of the end portion 16 of the contact probe 10 of the above-described embodiment is changed. Note that, in the present embodiment, the diameter D of the metal conductor 11 is constant.

The case where the radius of curvature R of the end portion of comparative example 1 was 0.5D, the case where the end portion of comparative example 2 was flat, and the case where the end portion of comparative example 3 was acute was evaluated.

Fig. 6 is a schematic diagram showing the shapes of the end portions of the contact probes 10 in the example and the comparative example shown in fig. 5.

Fig. 6A shows a case where the end portion is curved.

Fig. 6B is a case where the end portion is flat.

Fig. 6C shows a case where the end is acute.

The method for slide evaluation was: the contact test of the end 16 of the contact probe 10 and the object 20 was performed 10000 times, and the number of times of sliding occurrence was evaluated as a when 9 times or less, B when 10 times or more and 99 times or less, and C when 100 times or more.

The method for evaluating the damage is as follows: the contact test of the end 16 of the contact probe 10 with the object 20 was performed 10000 times, and the result was evaluated as a when there was no damage and as B when there was damage.

Hereinafter, each example will be described.

Example 1 ends with R =5D and the corresponding model is fig. 6A. The slip in example 1 was evaluated as a, and the damage was evaluated as a.

Example 2 ends with R =4D and the corresponding model is fig. 6A. The slip in example 2 was evaluated as a, and the damage was evaluated as a.

Example 3 ends with R =3D and the corresponding model is fig. 6A. The slip in example 3 was evaluated as a, and the damage was evaluated as a.

Example 4 ends with R =2D and the corresponding model is fig. 6A. The slip in example 4 was evaluated as a, and the damage was evaluated as a.

Example 5 ends with R =1.5D and the corresponding model is fig. 6A. The slip in example 5 was evaluated as a, and the damage was evaluated as a.

Example 6 ends with R = D and the corresponding model is fig. 6A. The slip in example 6 was evaluated as a, and the damage was evaluated as a.

Example 7 ends with R =0.9D and the corresponding model is fig. 6A. The slip in example 7 was evaluated as B and the damage was evaluated as a.

Example 8 ends with R =0.7D and the corresponding model is fig. 6A. The slip in example 8 was evaluated as B and the damage was evaluated as a.

In comparative example 1, the end portion was R =0.5D, and the shape was the same as in examples 1 to 8, but the radius of curvature was larger than in examples 1 to 8. The slip in comparative example 1 was evaluated as C, and the damage was evaluated as a.

The end of comparative example 2 was flat, and the corresponding model was fig. 6B. The slip in comparative example 2 was evaluated as a, and the damage was evaluated as B.

The tip of the end portion of comparative example 3 is a sharp acute angle, and the corresponding model is fig. 6C. The slip in comparative example 3 was evaluated as a, and the damage was evaluated as B.

From the results of FIG. 5, it is understood that, as in comparative example 1, when the end portion of the contact probe 10 is a curved surface and the radius of curvature R thereof is R.ltoreq.0.5D, the sliding is easy, and therefore, the sliding evaluation is poor.

In addition, as in comparative example 2, when the end portion of the contact probe had a flat shape, the sliding evaluation was not problematic, but damage occurred.

Further, as in comparative example 3, when the end of the contact probe was at an acute angle, the sliding evaluation was not problematic, but damage occurred.

Therefore, it is preferable that the end of the contact probe 10 is a curved surface and the radius of curvature R is 0.5D < R.ltoreq.5D because the end is less likely to slide and is not damaged.

Both the sliding evaluation and the damage evaluation of examples 1 to 6 were a. Therefore, it is also found that the range of R where D.ltoreq.R.ltoreq.5D is more preferable as in examples 1 to 6.

Claims

1. A contact probe, having:

a main body part having an insulating coating on the outer periphery of a needle-like metal conductor, and

end portions formed at both ends of the metal conductor without the insulating coating,

the contact pressure to the body to be measured is obtained by applying a load in the axial direction and deflecting the load, and the electrical characteristics are measured,

among the end portions, at least an end portion on a side contacting the object to be measured has a curved surface shape, and when a radius of curvature of the curved surface is R and a diameter of the metal conductor is D, R is greater than 0.5D and not greater than 5D.

2. The contact probe of claim 1, wherein the radius of curvature R is D or greater.

3. The contact probe according to claim 1 or 2, wherein the diameter of the metal conductor is 8 μm or more and 180 μm or less.