JP5328042B2 - Contact probe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contact probe capable of suppressing heightening a resistance value without depending on its diameter even when being used at a high temperature. <P>SOLUTION: In this contact probe including a cylindrical barrel, a plunger provided on the end of the barrel, and an elastic body stored in the barrel and energizing the plunger outward, the plunger includes: a substrate; a Ni-plated film formed on the surface of the substrate; an Au-plated film formed on the Ni-plated film; and an alloy middle film formed by being heated in a vacuum atmosphere, which is an alloy film interposed between the Ni-plated film and the Au-plated film and containing Au, Pd and Co, and the barrel includes an Au layer forming the inner circumference thereof, and a Ni layer forming the outer circumference of the barrel, and the barrel is formed by an electroforming method on the outer circumferential surface of a core wire having a prescribed diameter. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

The present invention relates to a contact probe used for measuring and inspecting electrical characteristics of an electronic component such as an IC, and more particularly to a cylindrical barrel, a plunger provided at an end of the barrel, and a barrel. And an elastic body that urges the barrel outward.

Conventionally, a plunger of a contact probe is known in which a Ni plating film is formed as a base film on a base material made of, for example, BeCu, and an Au plating film is formed thereon as a surface film. Further, a barrel is known in which a Ni plating film is formed as a base film on a raw tube made of phosphor bronze, for example, and an Au plating film is formed thereon as a surface film.

On the other hand, the inspection of electronic components such as IC includes an operation test in a wafer state (pre-process) and an inspection in a package state after processes (post-process) such as wire bonding and packaging. In the operation test at the wafer stage, a plurality of the contact probes described above are used, for example, arranged on a probe card. On the other hand, in the inspection in the package state, for example, a plurality of sockets are used. The contact probe is used in a state where the plunger on one end is in contact with the electrode of the IC and the plunger on the other end is in contact with the circuit board of the inspection device. It is propagated.

In recent years, there is an increasing need for automotive applications such as an engine control function and a brake control function for ICs to be inspected in this way.
However, ICs for automobiles are often used in a high-temperature environment such as an automobile engine room. For this reason, the importance of performing inspection of ICs for these automobile applications in a high temperature environment is extremely increased.

As a test in such a high temperature environment, for example, a packaged IC is mounted in a socket and stored for several days in a high temperature furnace while applying a load such as voltage or current, and the electrical characteristics of the IC before and after that are stored. There are known a burn-in test for inspecting the presence or absence of a change, a test called wafer burn-in for performing an operation test while applying a load such as voltage and current to a wafer-state IC at a high temperature.

However, when the contact probe as described above is stored at a high temperature, for example, the Ni component of the base film diffuses to the surface and is oxidized, resulting in an increase in the electrical resistance value of the contact probe. In addition, there is a problem that, for example, repeated contact with a circuit board or the like at high temperatures causes the tip of the plunger to be worn and the electrical resistance value to easily increase.
For this reason, in the contact probe as described above, the resistance value increases in a high temperature environment, and the load such as voltage and current necessary for the inspection cannot be continuously applied. was there.

Further, while the number of electrodes of an IC increases as the IC functions become higher, the IC package size tends to decrease as the IC package becomes smaller. For this reason, since it is necessary to arrange as many contact probes as possible in one socket, it is necessary to narrow the pitch of contact probe arrangements, and it is required to make the diameter of the contact probes, that is, the diameter of the barrel as small as possible.
However, in the conventional method of forming the barrel by immersing the raw tube in a plating bath, the plating solution is less likely to penetrate into the inner surface of the raw tube due to surface tension or the like as the inner diameter of the raw tube becomes smaller. Therefore, for example, the thickness of the Au plating film on the inner surface of the central portion of the element tube is thinner than the thickness of the Au plating film on the inner surface near the end of the element tube. It becomes difficult to form an Au plating film with such a thickness.

When such a contact probe formed with a barrel having a thin Au plating film thickness is used at high temperatures, for example, the underlying Ni diffuses and appears on the barrel surface where the Au plating film thickness is thin, and appears on this surface. There is a problem that the resistance value of the contact probe may increase due to oxidation of Ni.
That is, the conventional barrel forming method in which Au plating is applied to the raw tube has a problem that the resistance value may increase at a high temperature as the diameter of the contact probe becomes thinner.

  With respect to the above problems, several proposals have been made regarding contact probes having excellent durability (hereinafter also referred to as “contact pins”) (see, for example, Patent Document 1 and Patent Document 2).

JP 2005-268090 A JP 2009-53124 A

According to Patent Document 1, a contact pin that is disposed in an electrical component socket and contacts a terminal of the electrical component, the first plunger (22), the second plunger (24), and a cylinder A contact pin having a body (25) and a coil spring is disclosed. The contact pin is subjected to gold-nickel alloy plating at least on the surface of the contact portion that is in contact with the terminal, prevents solder from transferring to the contact pin, and is repeatedly used at a high temperature of 150 ° C. Also, the resistance value is stable.

However, since the above-mentioned ICs for automobiles are used under a higher temperature environment than 150 ° C., it is necessary to inspect these ICs for automobile use under a high temperature environment of about 175 ° C., for example. Therefore, the contact pin is required to have a high quality that does not increase its resistance even when used at a high temperature of at least 175 ° C.
However, according to Patent Document 1, since the contact pin is plated with gold-nickel alloy, there is a problem in that the nickel component is oxidized at a high temperature exceeding 150 ° C. to increase the resistance value of the contact pin. there were.
Further, according to Patent Document 1, when the diameter of the cylindrical body (25) is reduced, it is unknown about fluctuations in the resistance value of the probe pin due to high-temperature storage.

Further, in Patent Document 2, in a contact member formed by forming a noble metal thin film on the surface of a base material, 0.01-2. A contact member dispersed at a rate of 0% by weight and improved in durability and the like is disclosed.
However, according to Patent Document 2, for example, it is not certain about the fluctuation of the resistance value when used in a high temperature exceeding 150 ° C.

Accordingly, the present invention has been made in view of the above-described conventional problems, and its purpose is to suppress an increase in resistance value even when used at high temperatures and to cope with a narrow pitch of the arrangement interval. It is to provide a possible contact probe.

  The invention according to claim 1 includes a contact including a cylindrical barrel, a plunger provided at an end of the barrel, and an elastic body housed in the barrel and biasing the plunger outward. In the probe, the plunger includes a base material, a Ni plating film formed on a surface of the base material, an Au plating film formed on the Ni plating film, the Ni plating film, and the Au plating film. An alloy intermediate film containing Au, Pd, and Co, and heated in a vacuum atmosphere, and the barrel includes an Au layer that forms an inner periphery thereof, And a Ni layer that forms an outer periphery of the barrel, the barrel being a contact probe formed by electroforming on an outer peripheral surface of a core wire having a predetermined diameter.

According to a second aspect of the present invention, in the contact probe according to the first aspect, the Au plating film is made of a pure Au plating film of 99.9% by weight or more.

  According to a third aspect of the present invention, in the contact probe according to the first aspect, the Au plating film is made of an AuCo plating film.

According to a fourth aspect of the present invention, in the contact probe according to the third aspect, the plunger includes a pure Au plating film made of 99.9% by weight or more of Au on the AuCo plating film. .

According to a fifth aspect of the present invention, in the contact probe according to any one of the first to fourth aspects, the barrel has a Pd layer interposed between the Au layer and the Ni layer.

The invention according to claim 6 is the contact probe according to any one of claims 1 to 5, wherein the Au layer comprises a pure Au layer having a thickness of approximately 1.0 to 5 μm and not less than 99.9% by weight. It is characterized by.

The invention according to claim 7 is a contact including a cylindrical barrel, a plunger provided at an end of the barrel, and an elastic body housed in the barrel and biasing the plunger outward. In the probe, the plunger includes a base material, a Ni plating film formed on a surface of the base material, an Au plating film formed on the Ni plating film, the Ni plating film, and the Au plating film. And an alloy intermediate film containing Au, Pd and Co, which is heated in a vacuum atmosphere, and the barrel includes a flat base material and the base material A first Ni plate pressure-bonded to the upper surface of the first metal plate, a second Ni plate pressure-bonded to the lower surface of the base material, and a plate pressure-bonded to the upper surface of the first Ni plate, Au or a noble metal alloy A third metal plate formed of the second Ni A plate which is pressed against the lower surface of the fourth metal plate formed of Au or noble metal alloy, a clad plate consisting of, was formed into a cylindrical shape by deep-drawing, a contact probe.

The invention according to claim 8 is a contact including a cylindrical barrel, a plunger provided at an end of the barrel, and an elastic body housed in the barrel and biasing the plunger outward. In the probe, the plunger includes a base material, a Ni plating film formed on a surface of the base material, an Au plating film formed on the Ni plating film, the Ni plating film, and the Au plating film. And an alloy intermediate film containing Au, Pd and Co, which is heated in a vacuum atmosphere, and the barrel is made of Au or a noble metal alloy containing Au It is a contact probe which consists of a cylindrical body.

According to the invention of claim 1, a cylindrical barrel, a plunger provided at an end of the barrel, and an elastic body housed in the barrel and biasing the plunger outward. In the contact probe including the plunger, the plunger includes a base material, a Ni plating film formed on the surface of the base material, an Au plating film formed on the Ni plating film, the Ni plating film, and the Au plating. An alloy intermediate film interposed between the film and containing Au, Pd, and Co and heated in a vacuum atmosphere, and the barrel has an Au layer forming an inner periphery thereof And the Ni layer that forms the outer periphery of the barrel, and the barrel is configured by electroforming on the outer peripheral surface of the core wire having a predetermined diameter, so that the diffusion of Ni in a high temperature, With alloy interlayer It is control becomes difficult to appear to the surface of the plunger. Accordingly, since the oxidation of the plunger surface can be suppressed even when used at a high temperature, an increase in the resistance value of the plunger can be suppressed. Further, even if the barrel is formed with a small diameter, it is possible to reliably provide an Au layer having a uniform thickness. Therefore, by setting the thickness of the Au layer to a predetermined thickness, even if Ni diffuses in the Au layer at a high temperature, it becomes difficult to appear on the inner peripheral surface of the barrel. Therefore, even when used at a high temperature, oxidation of the inner peripheral surface of the barrel can be suppressed, and an increase in the resistance value of the barrel can be suppressed. As described above, according to the present invention, it is possible to provide a contact probe that can suppress an increase in resistance value even when used at a high temperature and can cope with a narrow pitch of the arrangement interval.

According to the invention of claim 2, since the Au plating film is composed of 99.9% by weight or more of pure Au plating film, oxidation of the pure Au plating film at high temperature can be eliminated. Even when used in the present invention, a contact probe that can further suppress the increase in resistance value can be provided.

According to the invention of claim 3, since the Au plating film is composed of an AuCo plating film, the wear resistance and durability of the contact probe can be improved by improving the hardness of the plunger surface. .

According to the invention of claim 4, since the plunger is configured to have a pure Au plating film made of 99.9% by weight or more of Au on the AuCo plating film, the AuCo plating is performed even at a high temperature. By further suppressing the diffusion of Co in the film with the pure Au plating film on the surface, it is possible to prevent the Co from being oxidized on the plunger surface and increasing the resistance value.

Further, according to the invention of claim 5, since the barrel has a configuration in which a Pd layer is interposed between the Au layer and the Ni layer, resistance is suppressed by suppressing diffusion of Ni by the Pd layer. The increase in value can be further suppressed.

According to the invention of claim 6, the Au layer is composed of a pure Au layer having a thickness of approximately 1.0 to 5 μm and 99.9% by weight or more. Oxidation can be prevented, and Ni can be prevented from diffusing to the inner peripheral surface of the barrel, so that an increase in resistance value can be further suppressed.

According to the invention of claim 7, a cylindrical barrel, a plunger provided at an end of the barrel, and an elastic body housed in the barrel and biasing the plunger outward. The plunger includes a base material, a Ni plating film formed on the surface of the base material, an Au plating film formed on the Ni plating film, the Ni plating film, and the An alloy intermediate film interposed between the Au plating film and containing Au, Pd, and Co, and heated in a vacuum atmosphere, and the barrel includes a flat base material and A first Ni plate crimped to the upper surface of the base material, a second Ni plate crimped to the lower surface of the base material, and a plate crimped to the upper surface of the first Ni plate, A third metal plate formed of Au or a noble metal alloy; Since the clad plate made of Au or a fourth metal plate made of a noble metal alloy is pressed onto the lower surface of the second Ni plate, it is formed into a cylindrical shape by deep drawing. The diffusion of Ni at a high temperature is suppressed by the alloy intermediate film and hardly appears up to the surface of the plunger. Accordingly, since the oxidation of the plunger surface can be suppressed even when used at a high temperature, an increase in the resistance value of the plunger can be suppressed. Further, even if the barrel is formed with a small diameter, the interface between the first Ni plate and the third metal plate of the clad material and the interface between the second Ni plate and the fourth metal plate are still at a high temperature. Ni becomes a barrier against Ni diffusion, and Ni is difficult to precipitate on the barrel surface. Therefore, even if it uses in high temperature, the oxidation of the surface of a barrel can be suppressed and the raise of the resistance value of a barrel can be suppressed. As described above, according to the present invention, it is possible to provide a contact probe that can suppress an increase in the resistance value even when used at a high temperature and can cope with a narrow pitch of the arrangement interval.

According to the invention of claim 8, a cylindrical barrel, a plunger provided at an end of the barrel, and an elastic body housed in the barrel and biasing the plunger outward. The plunger includes a base material, a Ni plating film formed on the surface of the base material, an Au plating film formed on the Ni plating film, the Ni plating film, and the An alloy intermediate film interposed between the Au plating film and containing Au, Pd, and Co, and heated in a vacuum atmosphere, and the barrel contains Au or Au Since it is the structure which consists of a cylindrical body formed with a noble metal alloy, the diffusion of Ni at a high temperature is suppressed by the alloy intermediate film and hardly appears up to the surface of the plunger. Accordingly, since the oxidation of the plunger surface can be suppressed even when used at a high temperature, an increase in the resistance value of the plunger can be suppressed. Moreover, since the barrel is made of a noble metal even if it is formed with a small diameter, oxidation of the surface of the barrel is suppressed, and an increase in the resistance value of the barrel can be suppressed. As described above, according to the present invention, it is possible to provide a contact probe that can suppress an increase in the resistance value even when used at a high temperature and can cope with a narrow pitch of the arrangement interval.

It is a section explanatory view of the contact probe concerning a 1st embodiment of the present invention. It is a graph explaining the component analysis of the plunger which concerns on 1st Embodiment of this invention. It is the schematic explaining the evaluation apparatus of the contact probe of this invention. It is a graph explaining the example of evaluation using the evaluation apparatus of FIG. It is a section explanatory view of a contact probe concerning a 2nd embodiment of the present invention. It is a section explanatory view of a contact probe concerning a 3rd embodiment of the present invention. It is a graph which shows the evaluation result of the Example of this invention. It is a graph which shows the evaluation result of the Example of this invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
First, the contact probe 10 according to the first embodiment of the present invention will be described mainly with reference to FIG.
FIG. 1A is an explanatory cross-sectional view of a contact probe 10 according to a first embodiment of the present invention. FIG.1 (b) is an enlarged view of b part in Fig.1 (a). FIG.1 (c) is an enlarged view of c part in Fig.1 (a).
As shown in FIG. 1, the contact probe 10 of this embodiment includes a barrel 20, plungers 30 and 32, and a spring 40.

As shown in FIG. 1A, the barrel 20 of the present embodiment includes a cylindrical tube body 22 and a reduced diameter portion 21 in which both ends of the tube body 22 are reduced in diameter. The tubular body 22 is formed of, for example, a cylindrical thin tube having a length of about 4 mm, an inner diameter of about 0.3 mm, and a wall thickness of about 35 μm. As shown in FIG. 1A, the reduced diameter portion 21 is formed by caulking or the like after a spring 40 to be described later is accommodated in the barrel 20 and the plungers 30 and 32 are respectively disposed at both ends of the barrel 20. Is done. As shown in FIG. 1, flange portions 34 of plungers 30 and 32 to be described later are locked to the reduced diameter portion 21 so as not to jump out of the barrel 20, that is, the reduced diameter portion 21 has the plungers 30 and 32. This is a locking means for preventing the barrel 20 from jumping out. The locking means is not limited to the reduced diameter portion 21 of the present embodiment. For example, a part of the side surface of the barrel is formed by reducing the diameter by caulking, and an arbitrary configuration according to the shape of the plunger is used. can do.

Next, a method for manufacturing the sectional structure of the barrel 20 according to this embodiment will be described.
As shown in FIG. 1C, the barrel 20 of the present embodiment includes an Au layer 24 that forms the inner periphery and a Ni layer 26 that forms the outer periphery of the barrel 20, and is formed by electroforming. Here, the electroforming method refers to a manufacturing method in which a single-layer or multi-layer plating layer is formed on the outer peripheral surface of a thin core wire, and then the core wire is drawn to form a cylindrical body composed of only the plating layer.

Specifically, the barrel 20 forms an AuCo plating layer as the Au layer 24 on the outer peripheral surface of, for example, a stainless steel core wire having a predetermined diameter, and further forms a Ni plating layer on the AuCo plating layer. Thereafter, the core wire is drawn out. Therefore, as shown in FIG. 1C, the barrel 20 has a configuration in which the Au layer 24 (AuCo plating layer) forms the inner periphery, and the Ni plating layer as the Ni layer 26 forms the outer periphery of the barrel 20. ing.
The reason why the inner peripheral side is formed of the Au layer 24 is to reduce the contact resistance with the plunger described later. The reason why the outer peripheral side is formed by the Ni layer 26 is to give the barrel 20 the strength necessary for a contact probe.

Thus, since the barrel 20 is formed by electroforming, the thickness of the Au layer 24 can be formed substantially uniformly along the cylinder length direction of the barrel 20 even when the inner diameter is small. At this time, it is desirable that the Au layer be formed with a thickness of at least 1 μm. This is to prevent Ni in the Ni layer 26 from diffusing and precipitating on the surface of the Au layer 24 at a high temperature.

In the barrel 20 of this embodiment, as described above, the inner Au layer 24 is formed of an AuCo plated film, but the present invention is not limited to this, and an Au layer made of pure Au plating of 99.9% by weight or more. It may be. This is because the pure Au plating contains almost no easily oxidized metal such as Co contained in the AuCo plating, so that an increase in barrel resistance due to oxidation of Co during high temperature storage can be eliminated. In the case of an Au layer formed by pure Au plating, it is desirable that the thickness is 1 μm to 5 μm. This is because if it is thinner than 1 μm, Ni in the Ni layer 26 may diffuse and precipitate on the surface of the Au layer at a high temperature. Further, if it is thicker than 5 μm, it will increase the cost of the contact probe.

Further, as shown in FIG. 1C, the barrel 20 of the present embodiment is composed of two layers of an Au layer 24 on the inside and a Ni layer 26 on the outside, but the structure of the barrel is not limited to two layers. Alternatively, a Pd layer may be interposed between the Au layer 24 and the Ni layer 26. This is because Ni diffusion at high temperatures can be suppressed by the Pd layer. An Au layer 24 is formed on the outer peripheral surface of the core wire by Au plating, a Pd layer is formed on the Au layer 24 by Pd plating, and a Ni layer 26 is formed on the Pd layer by Ni plating. Thereafter, for example, the core wire is drawn out.

Next, the plungers 30 and 32 will be described. As shown in FIGS. 1A and 3, the contact probe 10 of the present embodiment includes a plunger 30 at one end of the barrel 20 and a plunger 32 at the other end.
As shown in FIG. 1A, the plunger 30 includes a columnar shaft body portion 33 having substantially the same diameter as the inner diameter of the reduced diameter portion 21, and a crown-shaped protrusion provided at the tip of the shaft body portion 33. 31 and a flange 34 whose lower end is expanded to the inner diameter of the tubular body 22. In addition, the plunger 32 includes a protrusion 35 at the center of the tip of the shaft body 33 and a flange 34 at the lower end. The plungers 30 and 32 are arranged at both ends of the barrel 20 as described above, and are slidable along the tube length direction of the tube body 22.
In addition, the shape of a plunger is not restricted to the shape of this embodiment, It can be set as the well-known shape which can be provided in the edge part of a barrel. Further, in the contact probe 10 of this embodiment, both the plungers 30 and 32 are slidable. However, any one of the plungers can slide by, for example, barrel caulking. It may be a regulated known configuration.

Hereinafter, taking the plunger 30 as an example, the cross-sectional structure and the manufacturing method will be described.
As shown in FIG. 1B, the plunger 30 of the present embodiment includes a base material 36, a base film 37 that covers the surface of the base material 36, a surface film 39 that forms the surface of the plunger 30, An alloy intermediate film 38 formed between the base film 37 and the surface film 39 is provided.

Next, a method for manufacturing the plunger 30 will be described. First, a Ni plating film is formed on the surface of a base material 36 made of, for example, BeCu. Next, a PdCo plating film is formed on the surface of the Ni plating film. Next, an AuCo plating film as an Au plating film is formed on the surface of the PdCo plating film. Thereafter, it can be manufactured by heating in a vacuum atmosphere (hereinafter also referred to as “heat treatment”) using, for example, a vacuum heat treatment furnace.
In this way, the reason for heating is to promote the alloying of the ternary alloy composed of Au, Pd and Co by promoting the mutual diffusion of the respective metals in the PdCo plating film and the AuCo plating film. .
Also, one of the purposes of heating in a vacuum atmosphere is that if a reactive gas such as O ₂ is contained in the heat treatment atmosphere, the Co in the AuCo plating film becomes the surface of the AuCo plating film, that is, the plunger 30 This is to suppress segregation on the surface in many cases. Therefore, the oxidation of the plunger 30 surface during the heat treatment can be suppressed.
Another object is to eliminate the reactive gas as much as possible because the reaction between the reactive gas and the material often dominates the thermal diffusion when the reactive gas is contained in the heat treatment atmosphere. This is to promote alloying.
In order to improve the adhesion between the Ni plating film and the PdCo plating film, the PdCo plating film may be formed after an Au strike plating film is formed on the surface of the Ni plating film. Further, in order to improve the adhesion between the PdCo plating film and the AuCo plating film, the AuCo plating film may be formed after the Au strike plating film is formed on the surface of the PdCo plating film.

Thus, the base film 37 formed on the surface of the substrate 36 is made of the Ni-plated film subjected to the heat treatment, and the surface film 39 is made of the Au-plated film (AuCo plated film) subjected to the heat treatment. By performing the heat treatment, an alloy intermediate film 38 containing Au, Pd, and Co is interposed between the base film 37 and the surface film 39. This will be described later.
The heating temperature described above is preferably about 295 ° C to 335 ° C. This is because if the temperature is lower than 295 ° C., the alloying may not be promoted. On the other hand, when the temperature is higher than 335 ° C., the above-described interdiffusion significantly progresses, and the contact resistance of the plunger 30 may increase due to a decrease in the Au content in the AuCo plating film.
The heating time is preferably 2 to 3 hours. This is because if the time is shorter than 2 hours, the alloying may not be promoted. In addition, when the time is longer than 3 hours, the above-described interdiffusion proceeds remarkably, and the contact resistance of the plunger 30 may increase due to a decrease in the Au content in the AuCo plating film.

Here, the following plunger P for evaluation was manufactured, and the relationship between the presence or absence of heat treatment and the component in the depth direction of the plunger P, and the relationship between the heating temperature and the component in the depth direction of the plunger P were evaluated. Went. The shape and size of the plunger P are the same as the shape and size of the plunger 30 described above.
A Ni plating film having a thickness of about 0.5 μm is formed on the surface of a base material made of BeCu by electroless plating using a NiP plating bath, and an Au strike plating film having a thickness of about 0.1 μm is formed thereon. A PdCo plating film having a thickness of approximately 1.8 μm is formed thereon by electrolytic plating using a PdCo plating bath, and an Au strike plating film having a thickness of approximately 0.1 μm is formed thereon. On top of this, a plunger P was manufactured by forming an approximately 2.6 μm thick AuCo plating film by electrolytic plating using the AuCo plating bath.

FIG. 2 is a graph in which components in the depth direction of the plunger P are measured. More specifically, one of the crown-shaped protrusions of the plunger P is cut in the longitudinal direction to expose the cross section, and the cross section (see FIG. 1B) is measured with an EDX (energy dispersive X-ray spectrometer). did. In FIG. 2, the vertical axis indicates the detection amount (At%). The horizontal axis indicates the depth (μm), that is, the distance in the direction of arrow D with the tip of the protrusion 31 as a base point, as shown in FIG. In FIG. 2, the thick solid line indicates the Au profile J, the thin solid line indicates the Co profile L, the alternate long and short dash line indicates the Pd profile K, the thick chain line indicates the Ni profile M, and the thin chain line indicates Cu. Profile H is shown.

Fig.2 (a) is a graph which shows the measurement result of the plunger P cross section before performing heat processing.
According to the profile H in FIG. 2A, the detected amount of the Cu component increases in the deep direction from the vicinity of 5 μm. This is because the Cu component of the BeCu material (base material 36) is detected. Is shown.
Further, according to the profile M in FIG. 2A, it can be seen that the Ni plating film is formed on the base material 36.
2A has a peak B in a region slightly shallower than the peak of the profile M, which indicates that the Au component of the Au strike plating film has been detected. It can also be seen that the AuCo plating film is formed from the surface of the plunger to a depth of about 2 to 3 μm.
2A shows that the Pd component of the PdCo plating film is detected between the AuCo plating film and the Ni plating film. The profile L shows that the Co component of the PdCo plating film is detected between the AuCo plating film and the Ni plating film.

Next, FIG.2 (b) is a graph which shows the EDX measurement result of the plunger P cross section after heat processing for about 1.5 hours at a vacuum degree of 10 ^<-6 > Torr and about 250 degreeC.
According to the profile J in FIG. 2B, it can be seen that the Au component has dropped to the bottom in the vicinity of about 4 μm, and the Au component has not diffused much into the PdCo plating film. Further, since the peak value of the profile K in FIGS. 2A and 2B hardly changes, it can be seen that the Pd component of the PdCo plating film is not diffused so much in the AuCo plating film. . In other words, since the effect of the heat treatment is small, there is almost no change in the profile before and after the heat treatment, and it can be seen that alloying has not progressed.

Next, FIG.2 (c) is a graph which shows the EDX measurement result of the plunger P cross section after heat-processing for about 2 hours at a vacuum degree of 10 ^<-6 > Torr and about 315 degreeC.
As apparent from FIG. 2C, it can be seen that the Au component of the surface AuCo plating film diffuses into the PdCo plating film, and the Pd component of the PdCo plating film diffuses into the Au plating film. . Thus, it can be seen that by performing the heat treatment, an alloy intermediate film 38 made of an alloy containing Au, Co, and Pd is formed between the base film 37 and the surface film 39.
In the example of the present embodiment, the alloy intermediate film 38 has an Au content of about 25 At%, a Co content of about 12 At%, and a Pd content of about 55 At%, for example, when the depth from the surface is about 4 μm. It is made up of. The alloy intermediate film 38 has an Au ratio (25 / (25 + 12 + 55)) of approximately 27% and a Co ratio (12 / (25 + 12 + 55)) of approximately 13% with respect to the total content. The Pd ratio (55 / (25 + 12 + 55)) is approximately 60%.

The base film 37 of the plunger 30 of this embodiment is made of the Ni-plated film subjected to the heat treatment, the alloy intermediate film 38 is made of an alloy containing Au, Co, and Pd, and the surface film 39 is made of the heat treatment. It consists of an applied AuCo plating film.
Next, the hardness of the base film 37, the alloy intermediate film 38, and the surface film 39 of the plunger 30 thus formed was measured. More specifically, the surface of the plunger 30 was mirror-polished with an inclination angle of several degrees, and the Vickers hardness (Hv) of the polished surface was measured by nanoindentation.
First, the Ni plating film (undercoat film 37) whose hardness was approximately 550 Hv before the vacuum heat treatment improved to approximately 680 Hv after the heat treatment.
In addition, the alloy intermediate film 38, which had a PdCo plating film hardness before the heat treatment of about 500 Hv, was improved to about 600 Hv by alloying.
In addition, the AuCo plating film (surface film 39) had a hardness of about 150 Hv before the heat treatment without depending on the thickness of the film, but after the heat treatment, the surface was about 150 Hv and was almost in the vicinity of the alloy intermediate film 38. At 350 Hv, the hardness tends to increase from the surface side toward the intermediate film side. This is considered to be because AuCo and PdCo interdiffusion due to the heat treatment, and the amount of Pd and Co increases as the AuCo plating film is deeper.

Here, it is desirable that the Ni plating film thickness formed on the surface of the substrate 36 is 0.5 μm to 5 μm. This is because if the thickness is less than 0.5 μm, the durability of the plunger may be reduced. In addition, when the thickness is larger than 5 μm, it may lead to an increase in cost and resistance.
Next, the PdCo plating film thickness is desirably 0.5 μm to 5 μm. If it is thinner than 0.5 μm, for example, the thickness of the alloy intermediate film 38 becomes insufficient, and the effect of suppressing the diffusion of Ni at a high temperature decreases. In addition, when the thickness is larger than 5 μm, it may lead to an increase in cost and resistance.
Next, the AuCo plating film thickness is desirably 0.5 μm to 5 μm. This is because when the thickness is less than 0.5 μm, the bulk resistance of the plunger 30 increases. Further, when the plunger 30 is stored at a high temperature, Co in the AuCo or PdCo plating film tends to be deposited on the surface of the plunger 30 and easily oxidized. Moreover, it is because it may lead to a cost increase when thicker than 5 micrometers.

The plunger 30 of the present embodiment has a structure in which the outermost surface is made of an AuCo plated film as an Au plated film, and a pure Au plated film made of 99.9% by weight or more of Au is formed on the AuCo plated film. May be. This is because with such a configuration, oxidation of Co in the AuCo plating film can be suppressed.
Moreover, it may replace with the AuCo plating film as Au plating film, and may be comprised by the pure Au plating film which consists of 99.9 weight% or more Au. This is because with such a configuration, Co in Au can be eliminated and oxidation can be further suppressed.

Next, the spring 40 of the present embodiment is a known coil spring in which a stainless steel wire is formed in a coil shape. The spring 40 is accommodated in the barrel 20 as shown in FIG. At that time, the spring 40 is interposed between the plunger 30 and the plunger 32 and biases the plunger 30 and the plunger 32 outward.

Next, an evaluation device 70 and an evaluation method for the contact probe 10 will be described with reference to FIG.
FIG. 3 is an explanatory diagram of a schematic configuration of the evaluation device 70 of the contact probe 10. As shown in FIG. 3, the evaluation apparatus 70 includes a first board 57, a socket body 62, a second board 55, a load detection sensor 52, an elevating means 51, a resistance measuring device 53, a power source (not shown), a control unit 54, and the like. Is provided.
The first substrate 57 is formed of a known printed circuit board, and includes a plurality of thin electrode pads 59 formed on its upper surface by, for example, Au plating. And the 1st board | substrate 57 is installed on the table 61, as shown in FIG. The table 61 includes a known heating mechanism (not shown) such as a heater, and is configured to be able to evaluate the contact probe 10 while being heated.

Next, the socket body 62 is formed of an insulating block used for a known IC socket or the like, and includes a plurality of through holes 63 for accommodating the contact probes 10. As shown in FIG. 3, the socket body 62 is disposed on the first substrate 57, and the contact probe 10 is held in the through hole 63 such that the plunger 32 contacts the electrode pad 59, for example.

Next, the 2nd board | substrate 55 is formed with a well-known printed circuit board, and is provided with the metal plate 56 which coat | covers the substantially whole bottom face. And the 2nd board | substrate 55 is arrange | positioned in the upper position of the socket body 62, as shown in FIG. In the present embodiment, the metal plate 56 is made of an Au plate.

Next, the load detection sensor 52 is formed of a known load cell, for example, and is installed on the upper surface of the second substrate 55, for example, as shown in FIG.

Next, the raising / lowering means 51 is formed by a known servo motor, for example, and is connected to the second substrate 55 and the load detection sensor 52 to move them in the vertical direction.

Next, the control unit 54 includes a CPU, a memory, a timer, a counter, and the like, and is connected to the lifting means 51 and the load detection sensor 52. Then, for example, on the basis of the signal from the load detection sensor 52, the raising / lowering speed of the second substrate 55 by the raising / lowering means 51, etc. The operation of 51 is controlled.

Next, the resistance measuring device 53 includes a known four-terminal resistance measuring device and the like, and is connected to the first substrate 57 and the second substrate 55 as shown in FIG. And it is the structure which can measure the resistance between these board | substrates.

Next, an operation example of the evaluation apparatus 70 will be described.
First, when the lifting means 51 lowers the second substrate 55 and the metal plate 56 contacts the plunger 30, the load detection sensor 52 detects the load and sends a detection signal to the control unit 54. Next, the control unit 54 that has received the detection signal further lowers the second substrate 55 to push the plungers 30 and 32 into the barrel 20. When the predetermined lowering amount is reached, the lifting / lowering means 51 raises the second substrate 55. The load detection sensor 52 detects the load at the time of lowering and rising, and the resistance measuring device 53 measures the resistance value of the contact probe 10. Hereinafter, the descending amount from the height at which the second substrate 55 contacts the plunger 30 is referred to as a stroke amount (mm).

Next, a data example of the contact probe 10 using the above-described evaluation apparatus 70 will be described with reference to FIG. FIG. 4 is a graph showing the relationship between the stroke amount and the load and the relationship between the stroke amount and the resistance value by the evaluation device 70. In FIG. 4, the horizontal axis corresponds to the stroke amount (mm), the left vertical axis corresponds to the load (g), and the right vertical axis corresponds to the resistance value (mΩ).
In FIG. 4, the curve H is a curve indicating the relationship between the stroke amount and the load, and the curve R is a curve indicating the relationship between the stroke amount and the resistance value of the contact probe 10.

First, the curve H is a hysteresis curve as shown in FIG. 4. The curve N in the curve H indicates the load detected when the second substrate 55 is lowered, and the curve L indicates the second substrate 55. Indicates the load detected when ascending. In addition, the stroke amount of the turning point is set to 0.65 mm because the recommended stroke amount when using the contact probe 10 of the present embodiment is 0.65 mm.

Next, the curve R is a hysteresis curve as shown in FIG. 4, and the resistance value detected at the time of descending and the resistance value detected at the time of ascent substantially overlap. In addition, the point indicated by the sign is a turning point. Thus, according to the curve, the resistance value of the contact probe 10 can be evaluated.

Next, a contact probe 80 according to a second embodiment of the present invention will be described with reference to FIG. The same members as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. The difference between the first embodiment and the second embodiment is that the barrel 28 is formed by deep drawing a clad material.

Specifically, the clad material of this embodiment includes, for example, a flat base material made of NS steel, a first Ni plate press-bonded to the upper surface of the base material, and a first press-bonded to the lower surface of the base material. 2 Ni plate, the 3rd metal plate crimped | bonded to the upper surface of the said 1st Ni plate, and the 4th metal plate crimped | bonded to the lower surface of the said 2nd Ni plate. In the present embodiment, the third metal plate and the fourth metal plate are made of 99.9% by weight or more of pure Au.
Further, the deep drawing process is a known processing method for processing a plate form material into a cylinder form through a multi-step process using a mold.
According to the deep drawing process, the innermost layer thickness can be uniformly formed in the tube length direction of the tube even if the tube has a small inner diameter of, for example, about 0.3 mm. Even if the diameter is narrow, the interface between the first Ni plate and the third metal plate of the clad material and the interface between the second Ni plate and the fourth metal plate are diffused at high temperatures. Ni becomes difficult to precipitate on the barrel surface. In addition, since the clad material is used, the film quality is more densely formed than the plating film formed by the electroforming method described above, so that the effect of suppressing the diffusion of Ni or the like is high without providing the barrier layer such as the Pd layer described above.

In FIG. 5, reference numeral 81 denotes a layer formed by deep row processing of the above-described base material, and is formed with a thickness of, for example, about 80 μm. Reference numeral 82 denotes a layer formed by processing the first Ni plate, and reference numeral 83 denotes a layer formed by processing the second Ni plate, and each is formed with a thickness of, for example, approximately 1 μm. Reference numeral 84 denotes a layer formed by processing the above-described third metal plate, and reference numeral 85 denotes a layer formed by processing the above-described fourth metal plate, each having a thickness of, for example, approximately 1 μm. Formed with.
The third metal plate and the fourth metal plate are not limited to those composed of 99.9% by weight or more of pure Au. For example, Au (approximately 69% by weight), Ag (approximately 25% by weight), and Pt You may consist of the noble metal alloy board comprised by (about 6 weight%).

Next, a contact probe 90 according to a third embodiment of the present invention will be described with reference to FIG. The same members as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. The difference between the first embodiment and the third embodiment is that the barrel 29 is made of a cylindrical body 91 formed of Au.

In the barrel 29 of the present embodiment, a cylindrical material made of pure Au of 99.9% by weight or more is thinned by a known seamless process. This is because the pure Au has a low ionization tendency and is not easily oxidized even at high temperatures, thereby eliminating the problem that the barrel 29 is oxidized at high temperatures and the resistance value increases. The processing method is not limited to seamless processing, and may be, for example, hot extrusion processing, forged welding tube processing, electric sewing tube processing, spiral processing, or the like.
The material is not limited to a material composed of 99.9% by weight or more of pure Au. For example, a noble metal composed of Au (approximately 69% by weight), Ag (approximately 25% by weight), and Pt (approximately 6% by weight). It may be a material made of an alloy.

[Evaluation of resistance fluctuation]
The contact probes of the following comparative examples and the contact probes of the examples were manufactured.
[Comparative Example 1]
The plunger and barrel of the contact probe of Comparative Example 1 were manufactured as follows.
First, the plunger formed a Ni plating film having a thickness of about 2 μm on the surface of a base material made of BeCu by electroless plating using a NiP plating bath. Next, an AuCo plating film having a thickness of about 2.5 μm was formed thereon by electrolytic plating using an AuCo alloy plating bath containing about 0.3% by weight of Co.
Next, as the barrel tube, a phosphor bronze tube having an inner diameter of about 0.3 mm and a thickness of about 30 μm was used. Then, a Ni plating film having a thickness of about 2 μm was formed on the outer peripheral side of the element tube by electrolytic plating using a Ni plating bath on the surface of the element tube. Next, an AuCo plating film having a thickness of about 1.5 μm was formed on the outer periphery of the base tube by electrolytic plating using the same AuCo alloy plating bath as described above.
The thickness of the Ni plating film formed on the inner side of the barrel was approximately 1 μm near the center in the cylinder length direction, and the thickness of the AuCo plating film was approximately 0.8 μm near the center in the cylinder length direction. .

[Comparative Example 2]
In Comparative Example 2, the plunger of the contact probe was manufactured in the same manner as in Comparative Example 1.
Next, the barrel was manufactured by the following electroforming method. That is, an AuCo plating film (Au layer 24) having a thickness of about 1.5 μm was formed on the outer peripheral surface of a stainless steel core wire having a diameter of about 0.3 mm by electrolytic plating using the AuCo alloy plating bath. Next, a Ni plating film (Ni layer 26) having a thickness of about 33.5 μm was formed thereon by electrolytic plating using a Ni plating bath, and then the core wire was drawn out.

[Example 1]
The barrel 20 and the plungers 30 and 32 of the contact probe 10 of Example 1 were manufactured as follows.
First, the plungers 30 and 32 formed a Ni plating film having a thickness of about 0.5 μm on the surface of the same BeCu substrate as in Comparative Example 1 by electroless plating using a NiP plating bath. Next, an Au strike plating film having a thickness of about 0.1 μm was formed thereon. Next, a PdCo plating film having a thickness of about 1.8 μm was formed thereon by electrolytic plating using a PdCo plating bath. Next, an Au strike plating film having a thickness of about 0.1 μm was formed thereon. Next, an approximately 2.5 μm thick AuCo plating film was formed thereon by electrolytic plating using the AuCo plating bath. Then, it manufactured by performing the heat processing for about 2 hours at about 315 degreeC in the degree of vacuum about 10 ^<-6 > Torr in a vacuum heat processing furnace.
Next, the barrel 20 was manufactured in the same manner as in Comparative Example 2.

[Example 2]
The plunger and barrel of the contact probe of Example 2 were manufactured as follows.
The difference between the plungers 30 and 32 of Example 1 and the plunger of Example 2 is that an AuCo plating film is formed with a thickness of approximately 2.3 μm as in Example 1, and then in a vacuum heat treatment furnace. A pure Au plating film having a thickness of about 0.5 μm was formed by electrolytic plating using a 99.9% by weight pure Au plating bath after heat treatment at about 315 ° C. for about 2 hours at a degree of vacuum of about 10 ⁻⁶ Torr. It is a point formed.
Next, the barrel 20 was manufactured in the same manner as in Comparative Example 2.

With respect to these comparative examples and examples, the following evaluation 1 and evaluation 2 were performed using the evaluation apparatus 70.
[Evaluation 1]
The evaluation method in Evaluation 1 is as follows.
As described in FIG. 4, the relationship (curve) between the stroke amount and the resistance value is obtained in the initial state and after high-temperature storage (stored in a high-temperature atmospheric furnace at approximately 200 ° C. in an atmospheric atmosphere for approximately 10 hours). It was. Then, the ratio (black circle) of the resistance value R ₀ (see FIG. 4) at the turning point of the curved line in the initial state and the resistance value R _{1 at} the turning point of the curved line after the high-temperature storage was obtained.
The evaluation results of Comparative Examples 1 and 2 and Examples 1 and 2 by the evaluation method are shown in FIG.
In FIG. 7, the vertical axis indicates the resistance value ratio, but is 1 (R ₀ / R ₀ ) in the initial state (white circles).
As shown in FIG. 7, in Comparative Example 1, R ₁ rises to about 2.8 times R ₀ after the high temperature storage, and in Comparative Example 2, R ₁ rises to about 2 times R ₀ after the high temperature storage. ing. On the other hand, about Example 1 and Example 2, the fluctuation | variation of the resistance value in an initial state and the said high temperature storage was hardly seen.

[Evaluation 2]
The evaluation method in Evaluation 2 is as follows.
First, it is stored for about 20 hours in an air atmosphere at about 200 ° C. in a high-temperature atmospheric furnace. Next, while heating to about 175 ° C. by the above-described evaluation apparatus 70 and applying a current of about 100 mA, the second substrate 55 is brought into contact with the tip of the plunger 30 by the lifting means 51 and further lowered by 0 · 65 mm. By the way, the reciprocating motion of raising the second substrate 55 and separating it slightly from the tip of the plunger 30 was repeated. Then, for each 1000 times reciprocating to obtain the resistance value R _n at the curve Li the folded Teno contact probe.
FIG. 8 shows the measurement results obtained by repeating the reciprocating motion 100,000 times in Comparative Example 2, Example 1 and Example 2 by the evaluation method. 8A is a graph showing the evaluation result of Comparative Example 2, FIG. 8B is a graph showing the evaluation result of Example 1, and FIG. 8C is a graph showing the evaluation result of Example 2. In FIG. 8, the vertical axis represents the ratio of the resistance value R _n for Comparative Example 2, Example 1, the average value obtained from all of the resistance value R _n of up to 100,000 times Example 2 . The horizontal axis represents the number of sliding times, that is, the number of reciprocating motions.

In the graph of FIG. 8A, the resistance ratio is approximately 3.5 when the number of sliding times is 0. The reason is that the resistance ratio is approximately 20 hours in an air atmosphere at approximately 200 ° C. in a high-temperature atmospheric furnace. This is because the contact resistance of the contact probe has increased due to oxidation of the jar surface. Further, in the graph of FIG. 8A, the resistance ratio decreases from the number of sliding times of 0 to approximately 2000 times because the tip of the plunger 30 comes into contact with the second substrate 55 by the reciprocating motion. This is because the oxide film is peeled off and the contact resistance is recovered.
In the case of the comparative example 2, as is clear from FIG. 8A, it can be seen that although the resistance once decreases due to the reciprocating motion, the resistance increases again from about 50,000 times.
On the other hand, in the case of Example 1 and Example 2, as is apparent from FIGS. 8B and 8C, even when the reciprocating motion is repeated approximately 100,000 times, the resistance value is hardly increased. It can be seen that there is no durability, that is, excellent durability.

As described above, the reason why the contact probes 10 of Example 1 and Example 2 are excellent in durability even after the high temperature storage is considered to be that a solid lubricating film is formed on the surface of the plunger 30. It is done.
Specifically, as described above, the hardness of the base film 37 of the plunger 30 is approximately 680 Hv, and the hardness of the alloy intermediate film 38 formed on the base film 37 is approximately 600 Hv, and is formed on the alloy intermediate film 38. The hardness of the surface film 39 was about 350 Hv in the vicinity of the alloy intermediate film 38 and about 150 Hv on the outermost surface. Thus, it is considered that the metal film having a low surface hardness is less likely to be worn by adopting a structure in which the surface of the metal film having a high hardness is covered with a metal film having a low hardness.

As described above, according to the contact probes 10, 80, 90 of the present embodiment, it is possible to suppress an increase in resistance value even when used at a high temperature, and to cope with a narrow pitch of the arrangement interval. Possible contact probes can be provided.

As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. However, these are merely examples, and the present invention is variously modified and improved based on the knowledge of those skilled in the art. It is possible to carry out the invention.

10, 80, 90 Contact probe 20, 28, 29 Barrel 30, 32 Plunger 40 Spring (elastic body)
36 Substrate 37 Base film (Ni plating film)
38 Alloy intermediate film 39 Surface film (Au plating film)
24 Au layer 26 Ni layer 81 Base material 82 First Ni plate 83 Second Ni plate 84 Third metal plate 85 Fourth metal plate 91 Cylindrical body

Claims (8)

In a contact probe including a cylindrical barrel, a plunger provided at an end of the barrel, and an elastic body that is housed in the barrel and biases the plunger outward.
The plunger is
A substrate;
Ni plating film formed on the surface of the substrate;
An Au plating film formed on the Ni plating film;
An alloy film which is interposed between the Ni plating film and the Au plating film and contains Au, Pd and Co, and which is heated in a vacuum atmosphere,
The barrel is
An Au layer forming its inner periphery,
Ni layer forming the outer periphery of the barrel,
The contact probe according to claim 1, wherein the barrel is formed on an outer peripheral surface of a core wire having a predetermined diameter by electroforming. The contact probe according to claim 1, wherein the Au plating film is made of a pure Au plating film of 99.9% by weight or more. The contact probe according to claim 1, wherein the Au plating film is made of an AuCo plating film. The contact probe according to claim 3, wherein the plunger includes a pure Au plating film made of 99.9% by weight or more of Au on the AuCo plating film. The contact probe according to claim 1, wherein the barrel has a Pd layer interposed between the Au layer and the Ni layer. The contact probe according to claim 1, wherein the Au layer is a pure Au layer having a thickness of approximately 1.0 to 5 μm and 99.9% by weight or more. In a contact probe including a cylindrical barrel, a plunger provided at an end of the barrel, and an elastic body that is housed in the barrel and biases the plunger outward.
The plunger is
A substrate;
Ni plating film formed on the surface of the substrate;
An Au plating film formed on the Ni plating film;
An alloy film which is interposed between the Ni plating film and the Au plating film and contains Au, Pd and Co, and which is heated in a vacuum atmosphere,
The barrel is
A flat base material;
A first Ni plate bonded to the upper surface of the base material;
A second Ni plate pressure-bonded to the lower surface of the base material;
A plate press-bonded to the upper surface of the first Ni plate, a third metal plate formed of Au or a noble metal alloy;
A clad plate made of Au or a noble metal alloy, which is press-bonded to the lower surface of the second Ni plate, and is formed into a cylindrical shape by deep drawing. Contact probe. In a contact probe including a cylindrical barrel, a plunger provided at an end of the barrel, and an elastic body that is housed in the barrel and biases the plunger outward.
The plunger is
A substrate;
Ni plating film formed on the surface of the substrate;
An Au plating film formed on the Ni plating film;
An alloy film which is interposed between the Ni plating film and the Au plating film and contains Au, Pd and Co, and which is heated in a vacuum atmosphere,
The barrel is
A contact probe comprising a cylindrical body formed of Au or a noble metal alloy containing Au.

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