JP2020165888A - Probe needle and probe unit - Google Patents

Abstract

To provide a probe needle and a probe unit which are used primarily for inspection of an electronic component and a substrate, etc., and which are of a small diameter used specifically with a narrow pitch.SOLUTION: Provided is a probe needle 10 used in inspection which is carried out by placing an edge 2a of an insulating coating 2 against a guide hole 21a of a support plate 21 on the measured object side constituting a probe unit 20 and bringing a tip 1a of a metal conductor 1 into contact with the measured object. The probe needle 10 comprises a metal conductor 1 and insulating coatings 2, 3 provided in at least a region of the metal conductor 1 except both ends, the insulating coatings 2, 3 including a thin insulating coating 3 provided on the measured object side and a thick insulating coating 2 provided in the barrel part other than the measured object side, the thick insulating coating 2 being constituted so that its edge 2a touches the guide hole 21a of the support plate 21 on the measured object side, the thin insulating coating 3 on the measured object side being constituted so that the withstand voltage is 250 V or higher.SELECTED DRAWING: Figure 2

Description

The present invention relates mainly to a small diameter probe needle and a probe unit used for continuity inspection of electronic parts, substrates, etc., and particularly used at a narrow pitch.

In recent years, various circuit boards such as high-density mounting boards used for mobile phones and IC package boards such as BGA (Ball Grid Array) and CSP (Chip Size Package) incorporated in personal computers have been widely used. There is. In such a circuit board, in the steps before and after mounting, for example, the DC resistance value is measured, the continuity is inspected, and the quality of its electrical characteristics is inspected. The quality of the electrical characteristics is inspected using an inspection device jig (hereinafter referred to as "probe unit") connected to the inspection device for measuring the electrical characteristics. For example, a pin shape attached to the probe unit. This is done by bringing the tip of the probe needle of the above into contact with an electrode (hereinafter, also referred to as “measured object”) of the circuit board. The probe needle is composed of a metal conductor and an insulating film provided in a region other than at least both ends of the metal conductor (see, for example, Patent Document 1).

Further, in Patent Document 2, even when the inspection of the electrical characteristics using the probe unit is repeatedly performed and the end of the insulating film repeatedly hits the guide hole, the end of the insulating film is prevented from peeling off from the metal conductor. A probe needle with an insulating coating that can be used has been proposed. This technology is used in a probe needle with an insulating film that measures the electrical characteristics of the object to be measured by bringing the tip of the metal conductor on the object to be measured into contact with the electrode of the object to be measured. The two-stage structure is thin on the tip side and thick on the center side, and the stepped portion of the two-stage structure is formed at a position where it abuts on the guide hole of the guide plate used when measuring the electrical characteristics. At this time, the thickness of the thin portion provided on the tip side is within the range of 0.1 μm or more and 4 μm or less, and the difference in thickness between the thin portion and the thick portion is within the range of 3 μm or more and 25 μm or less. It is said to be preferable.

Japanese Unexamined Patent Publication No. 2007-322369 Japanese Unexamined Patent Publication No. 2007-17219

In recent years, as the pitch between electrodes has become narrower, the diameter of the probe needle has been reduced. Under these circumstances, in the probe unit, the ends of the insulating film on the side to be measured of a large number of probe needles repeatedly hit the guide holes of the support plate, so that it is necessary to increase the strength of the support plate. A metal support plate can be considered as a high-strength support plate, but since it is necessary to electrically insulate the probe needles and the slipperiness is not very good, it is necessary to manufacture the support plate made of resin. However, the resin support plate has better slipperiness but lower strength than the metal support plate. Therefore, in order to maintain the strength, the pitch between the probe needles must be widened, which causes a problem of narrowing the pitch. It is conceivable that it is made of high-strength ceramic, but there are problems such as low workability and toughness.

On the other hand, since resin has a higher coefficient of thermal expansion than metal, when a probe unit equipped with a resin support plate is used for inspection in a high temperature environment, the probe needle is subjected to thermal expansion of the resin support plate. There is a problem that the pitch between them changes and it is difficult to make accurate contact with the electrodes.

The present invention has been made to solve the above problems, and an object of the present invention is to use a small-diameter probe needle and probe unit mainly used for inspecting electronic parts and substrates, and particularly used at a narrow pitch. To provide.

(1) The probe needle according to the present invention is used in an inspection performed by contacting the end of the insulating film with the guide hole of the support plate on the side to be measured which constitutes the probe unit and bringing the tip of the metal conductor into contact with the body to be measured. The probe needle is provided with the metal conductor and the insulating film provided in a region other than at least both ends of the metal conductor, and the insulating film is a thin insulating film provided on the side to be measured. And a thick insulating film provided on the body portion other than the object to be measured side, and the thick insulating film is configured such that the end portion thereof hits the guide hole of the support plate on the side to be measured. The thin insulating film on the side to be measured is characterized in that it has a withstand voltage of 250 V or more.

According to the present invention, since it has a two-stage structure composed of a thin insulating film on the side to be measured and a thick insulating film on the body portion, the thin insulating film comes into contact with the inner wall of the guide hole. As a result, the slipperiness is improved as compared with the case where the metal conductors come into contact with each other. Further, since the thin insulating film has the above-mentioned withstand voltage, for example, even if the support plate is made of metal, it has a sufficient withstand voltage, and the slipperiness with the inner wall of the guide hole of the metal support plate can be ensured. As a result, it can be preferably used as a probe needle having a small diameter used at a narrow pitch.

In the probe needle according to the present invention, the thickness of the thin insulating film on the side to be measured is in the range of 1 to 7 μm, and the thickness of the thick insulating film other than the tip skin is in the range of 3 to 20 μm. By doing so, the above-mentioned withstand voltage with a thin insulating film can be shown.

In the probe needle according to the present invention, the length L1 in the longitudinal direction of the thin insulating film on the side to be measured is 1.3 times longer than the thickness L2 of the support plate included in the probe unit. By doing so, the stroke length L5 repeated up and down by the probe unit becomes about twice. For example, even if the support plate is made of metal, the metal conductor exposed at the tip does not come into contact with the metal support plate, resulting in a short circuit. There is no such thing.

In the probe needle according to the present invention, the insulating film is a single layer or two or more layers composed of one or more resin materials selected from polyurethane, polyester, polyesterimide, polyamideimide, polyimide and fluororesin. It is formed. By forming the insulating film with such a highly slippery resin material, the slipperiness with the inner wall of the support plate is improved.

(2) The probe unit according to the present invention includes a support plate arranged on the side to be measured, a support plate arranged on the inspection device side, and a probe needle mounted in a guide hole provided in each of at least two of these support plates. This probe unit is used for inspections in which the end of the insulating film is applied to the guide hole of the support plate on the side to be measured and the tip of the metal conductor is brought into contact with the body to be measured.
The probe needle has the metal conductor and the insulating film provided in a region other than at least both ends of the metal conductor, and the insulating film includes a thin insulating film provided on the side to be measured and the insulating film. It has a thick insulating film provided on the body portion other than the body to be measured, and the thick insulating film is configured such that its end portion hits a guide hole of a support plate on the body to be measured. The thin insulating film on the body side is characterized by having a withstand voltage of 250 V or more.

In the probe unit according to the present invention, the support plate on the side to be measured is made of metal. By doing so, it is possible to have a sufficient withstand voltage and to ensure slipperiness with the inner wall of the guide hole of the metal support plate. As a result, it can be preferably used as a probe needle having a small diameter used at a narrow pitch.

In the probe unit according to the present invention, the length L1 of the thin insulating film on the side to be measured in the longitudinal direction is 1.3 times longer than the thickness L2 of the support plate on the side to be measured. By doing so, the stroke length L5 repeated up and down by the probe unit becomes about twice. For example, even if the support plate is made of metal, the metal conductor exposed at the tip does not come into contact with the metal support plate, resulting in a short circuit. There is no such thing.

According to the present invention, it is possible to provide a probe needle and a probe unit having a small diameter, which are mainly used for inspection of electronic parts, substrates and the like, and are particularly used at a narrow pitch. In particular, since it has a two-stage structure consisting of a thin insulating film on the tip side and a thick insulating film on the body, the thin insulating film comes into contact with the inner wall of the guide hole, so it slips more than when a metal conductor comes into contact. Improves sex. Further, since the thin insulating film has the above-mentioned withstand voltage, for example, even if the support plate is made of metal, it has a sufficient withstand voltage, and the slipperiness with the inner wall of the guide hole of the metal support plate can be ensured. As a result, it can be preferably used as a probe needle having a small diameter used at a narrow pitch.

It is a schematic diagram which shows an example of the probe needle which concerns on this invention. It is a schematic diagram which shows the operation mode of the probe needle in the probe unit which concerns on this invention. It is a schematic diagram which shows the operation mode of the probe unit which attached the conventional probe needle.

Hereinafter, the probe needle and the probe unit of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments.

As shown in FIGS. 1 and 2, the probe needle 10 according to the present invention has the end portion 2a of the insulating film 2 applied to the guide hole 21a of the support plate 21 on the side to be measured, which constitutes the probe unit 20, and the object to be measured. This is a probe needle 10 used in an inspection performed by bringing the tip 1a of a metal conductor 1 into contact with the metal conductor 1. The probe needle 10 has a metal conductor 1 and insulating films 2 and 3 provided in regions other than at least both ends of the metal conductor 1. The feature of such a probe needle is that the insulating films 2 and 3 have a two-stage structure having a thin insulating film 3 provided on the side to be measured and a thick insulating film 2 provided on the body portion other than the body to be measured. The thick insulating film 2 is configured such that its end 2a contacts the guide hole 21a of the support plate 21 on the object to be measured, and the thin insulating film 3 on the object to be measured has a withstand voltage of 250 V or more. It is to be configured like this.

As shown in FIG. 2, the probe unit 20 according to the present invention includes a support plate 21 arranged on the side to be measured, a support plate 22 arranged on the inspection device side, and at least two of these support plates 21 and 22, respectively. The probe needle 10 is attached to the guide holes 21a and 22a provided in the above, and the end portion 2a of the insulating film 2 is applied to the guide hole 21a of the support plate 21 on the side to be measured, and the metal conductor 1 is attached to the body to be measured. This is a probe unit used for inspection performed by contacting the tip 1a. The probe needle 10 has a two-stage structure having a metal conductor 1 and insulating films 2 and 3 provided in regions other than at least both ends of the metal conductor. The insulating films 2 and 3 have a thin insulating film 3 provided on the side to be measured and a thick insulating film 2 provided on the body portion other than the body to be measured, and the thick insulating film 2 has an end portion 2a thereof. Is configured to hit the guide hole 21a of the support plate 21 on the side to be measured, and the thin insulating film 3 on the side to be measured is configured to have a withstand voltage of 250 V or more.

Since the probe needle 10 and the probe unit 20 have a two-stage structure composed of a thin insulating film 3 on the side to be measured and a thick insulating film 2 on the body portion, the thin insulating film 3 comes into contact with the inner wall of the guide hole 21a. To do. As a result, the slipperiness is improved as compared with the case where the metal conductor 1 comes into contact with the metal conductor 1. Further, since the thin insulating film 3 has the above-mentioned withstand voltage, for example, even if the support plate 21 is made of metal, it has a sufficient withstand voltage, and the slipperiness of the metal support plate 21 with the inner wall of the guide hole 21a is also ensured. it can.

Hereinafter, each component will be described.

<Probe needle>
The probe needle 10 is an inspection performed by contacting the end portion 2a of the insulating film 2 with the guide hole 21a of the support plate 21 on the side to be measured, which constitutes the probe unit 20, and bringing the tip 1a of the metal conductor 1 into contact with the object to be measured. It is what is used. The probe needle 10 has a metal conductor 1 and insulating films 2 and 3 provided in regions other than at least both ends of the metal conductor 1.

(Metal conductor)
The metal conductor 1 is a pin-shaped conductor that is processed to a predetermined length, and is formed by cutting a metal wire (also referred to as a “metal spring wire”) having high conductivity and high elastic modulus. Examples of the metal used for the metal conductor 1 include metals having a wide elastic range, such as copper alloys such as silver-copper alloys, tin-copper alloys, and beryllium-copper alloys, tungsten, renium tungsten, and steel (for example, high-speed steel). : SKH) and the like can be preferably used.

The metal conductor 1 is usually subjected to plastic working such as cold or hot wire drawing until the metal becomes a linear conductor having a predetermined diameter. The outer diameter D1 of the metal conductor 1 is within the range of 10 to 110 μm, preferably within the range of 20 to 90 μm, depending on the distance between the adjacent probe needles 10 in the probe unit 20 due to the recent demand for narrower pitch. It can be selected arbitrarily.

The probe needle 10 can be easily attached to the probe unit 20, and the tip 1a of the probe needle 10 is caught in the guide hole 21a of the support plate 21 when the probe unit 20 is used, so that the movement of the probe needle 10 is hindered. From the viewpoint of prevention, the straightness of the metal conductor 1 is preferably high, and specifically, the straightness is preferably 1000 mm or more with a radius of curvature R.

The shapes of the end portion 1a and / or the end portion 1b on the rear end side of the metal conductor 1 are not shown, but are hemispherical, conical, conical with a hemispherical shape at the tip, and flat at the tip. It can be any one selected from the shape, etc. The "hemispherical shape" and "conical shape" referred to here include an accurate hemisphere and a cone, but also include a substantially conical shape and a substantially hemisphere.

At the ends 1a and 1b of the metal conductor 1, plating layers are provided at the ends 1a and 1b in order to suppress an increase in the contact resistance value between the metal conductor 1 and the lead wire of the object to be measured or the inspection device. You may be. 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, one in which a gold plating layer is formed on a nickel plating layer can be preferably mentioned. The plating layer is usually formed after cutting the metal conductor 1 on which the insulating films 2 and 3 are formed, then peeling the insulating films 2 and 3 and processing the end portion of the metal conductor 1.

(Insulation film)
As shown in FIGS. 1 and 2, the insulating films 2 and 3 are provided in a region other than at least both ends of the metal conductor 1. The structure of the insulating films 2 and 3 includes a thin insulating film 3 provided on the side to be measured and a thick insulating film 2 provided on the body portion other than the side to be measured, and has at least a two-stage structure. ing. Here, "having" and "at least" may have an insulating film (not shown) having a thickness different from that of the thin insulating film 3 and the thick insulating film 2, and may have a three-stage structure or more. It means that it may be.

The insulating films 2 and 3 are composed of one or more resin materials selected from polyurethane, polyester, polyesterimide, polyamideimide, polyimide and fluororesin. Then, it is formed of a single layer or two or more layers by the above-mentioned one or more kinds of resin materials. By forming the insulating films 2 and 3 with such a highly slippery resin material, the slipperiness of the support plates 21 and 22 with the inner walls of the guide holes 21a and 22a is improved. When more heat resistance is required, it is preferably formed of polyesterimide, polyamideimide, or the like.

The insulating films 2 and 3 are usually preferably formed on a long metal conductor 1 by a continuous enamel baking method, but of course, they may be formed by another method. At this time, the thick insulating film 2 and the thin insulating film 3 are made separately by using ablation by laser irradiation to irradiate the insulating film on the side to be measured with a laser, and the portion of length L1 composed of the thin insulating film 3 is formed. It can be formed so that it remains. All the insulating film on the inspection device side may be peeled off, and it is not necessary to form a thin insulating film 3. The thin insulating film 3 and the thick insulating film 2 may be made separately by a method other than the method using laser irradiation, and are not particularly limited.

The thick insulating film 2 is provided on the body portion other than the side to be measured, and is provided on the metal conductor 1 to prevent contact between the probe needles when inspecting the electrical characteristics of the object to be measured to prevent a short circuit. Acts like. The thick insulating film 2 is configured such that its end portion 2a abuts on the guide hole 21a of the support plate 21 on the side to be measured. The thickness of the thick insulating film 2 may be such that a necessary thickness that does not cause a short circuit when the probe needles come into contact with each other is provided in consideration of the wire diameter of the metal conductor 1 within the range of 3 to 20 μm. It is preferable to have.

The thin insulating film 3 is provided on the side to be measured, and is provided so that the tip 1a of the metal conductor 1 projects from the tip of the thin insulating film 3. The thin insulating film 3 is configured to have a withstand voltage of 250 V or more. The thin insulating film 3 formed with this withstand voltage is preferably formed with a thickness of at least about 1 μm or more. From the viewpoint of withstand voltage, the upper limit of the thickness of the thin insulating film 3 is not particularly limited, but it is also necessary to insert a portion where the thin insulating film 3 is formed into the guide hole 21a of the support plate 21. Therefore, the thickness of the thin insulating film 3 is preferably 7 μm or less.

As shown in FIG. 2, the length L1 of the thin insulating film 3 in the longitudinal direction (long method of the probe needle) may be 1.3 times longer than the thickness L2 of the support plate 21 included in the probe unit 20. preferable. By making it 1.3 times longer, the length L1 of the thin insulating film 3 becomes about twice the stroke length L5 repeated up and down by the probe unit 20, so that even if the support plate 21 is made of metal, it is exposed at the tip. The metal conductor 1 and the metal support plate 21 do not come into contact with each other, and there is no short circuit.

Since such a probe needle 10 has a two-stage structure composed of a thin insulating film 3 on the side to be measured and a thick insulating film 2 on the body portion, the thin insulating film 3 comes into contact with the inner wall of the guide hole 21a. .. Therefore, the slipperiness can be improved as compared with the case where the metal conductor 1 comes into contact with the inner wall of the guide hole 21a. Further, since the thin insulating film 3 has the above-mentioned withstand voltage, for example, even if the support plate 21 is made of metal, it has a sufficient withstand voltage, and the support plate 21 made of metal or ceramics slides with the inner wall of the guide hole 21a. There is an advantage that sex can be guaranteed.

<Probe unit>
As shown in FIG. 2, the probe unit 20 includes a support plate 21 arranged on the side to be measured, a support plate 22 arranged on the inspection device side, and guide holes provided in each of the at least two support plates 21 and 22. It has a probe needle 10 according to the present invention mounted on 21a and 22a. In the probe unit 20, the metal conductor 1 is placed on the object to be measured in a state where the end portion 2a of the insulating film 2 hits the guide hole 21a of the support plate 21 on the object to be measured and the probe needle 10 is prevented from falling. This is a device for inspecting by contacting the tip 1a. The probe unit 20 is equipped with a plurality of to several thousand probe needles 10.

The support plate 22 on the inspection device side has a guide hole 22a having an inner diameter D5 slightly larger than the outer diameter D2 (outer diameter of the probe needle 10) of the body portion provided with the thick insulating film 2. The guide hole 22a guides the metal conductor 1 of each probe needle 10 to the lead wire.

The support plate 21 on the side to be measured has a guide hole 21a having an inner diameter D4 slightly larger than the outer diameter D3 of the portion provided with the thin insulating film 3. The guide hole 21a guides the tips of the probe needles 10 one by one, and guides the tip 1a of the metal conductor 1 to the object to be measured so as to be in accurate contact with the tip 1a. Then, the metal conductor 1 does not contact the inner wall of the guide hole 21a, and only the thin insulating film 3 having a withstand voltage of 250 V or more contacts. As a result, even if the support plate 21 on the side to be measured is made of metal, it has a sufficient withstand voltage and can secure good slipperiness.

As shown in FIG. 2, reference numeral L3 is the length of the metal conductor 1 that enters the guide hole 21a of the support plate 21 when the probe needle 10 is most retracted, and reference numeral L4 is the length of the metal conductor 1 in which the probe needle 10 is most advanced. It is the length that protrudes from the lower surface of the support plate when it is used. Further, reference numeral L5 is a distance (length) between the upper surface of the support plate 21 and the end portion 3a of the thick insulating film 3 when the probe needle 10 is most retracted. As shown in FIG. 2A, the length L3 of the metal conductor 1 that enters the guide hole 21a of the support plate 21 is 0 of the thickness of the support plate 21 even when the probe needle 10 is most retracted. The length is preferably about% to 30%, and the length is preferably about 0% to 20%. By doing so, the tip 1a of the metal conductor 1 does not come into contact with the inner wall of the guide hole 21a and short-circuit. After that, when the probe needle 10 advances toward the object to be measured, the end portion 2a of the thick insulating film 2 hits the upper surface of the support plate 21 through the aspect of FIG. 2B, as shown in FIG. 2C. The probe needle 10 reaches the most advanced mode. In the aspect of FIG. 2C, the length L4 protruding from the lower surface of the support plate 21 is not particularly limited, but is generally preferably about 10 to 30% of the thickness L2 of the support plate 21.

The position of the probe unit 20 is controlled so that the probe needle 10 and the object to be measured correspond to each other when inspecting the electrical characteristics of the object to be measured. The inspection of the electrical characteristics is performed by stroking the probe unit 20 up and down and pressing the tip 1a of the probe needle 10 against the object to be measured with a predetermined pressure by utilizing the elastic force of the probe needle 10. At this time, the rear end 1b of the probe needle 10 comes into contact with a lead wire (not shown), and an electric signal from the object to be measured is sent to an inspection device (not shown) through the lead wire.

According to such a probe unit 20, since the thin insulating film 3 comes into contact with the inner wall of the guide hole 21a of the support plate 21 on the side to be measured, the slipperiness is improved as compared with the case where the metal conductor 1 comes into contact. As a result, the slidability in the probe unit 20 is improved, the contact stability to the object to be inspected is improved, and the contact defect is eliminated. Further, since the withstand voltage is also secured, for example, even if the support plate 21 is made of metal, it has a sufficient withstand voltage, and the slipperiness of the metal support plate 21 with the inner wall of the guide hole 21a can be ensured. In particular, by using the metal support plate 21, the strength of the support plate 21 is improved, and the pitch of the probe needle 10 can be narrowed. Further, the metal or ceramic support plate 21 has an advantage that the coefficient of thermal expansion is lower than that of the resin support plate 21 and the support plate 21 can be used at a high temperature. The metal support plate 21 may be entirely made of metal or partly made of metal, and is not particularly limited.

1 Metal conductor 1a Metal conductor exposed on the front end side 1b Metal conductor exposed on the rear end side 2 Thick insulating film on the body 2a End of the insulating film that hits the guide hole 3 Thin insulating film on the object to be measured 10 Probe needle 20 Probe unit 21 Support plate on the side to be measured 21a Guide hole 22 Support plate on the inspection device side 22a Guide hole 100 Conventional probe needle L1 Length of thin insulating film L2 Thickness of support plate on the side to be measured L3 When the probe needle is most retracted Length of metal conductor that enters the support plate L4 Length that protrudes from the lower surface of the support plate when the probe needle is most advanced L5 Distance (length) between the upper surface of the support plate and the end of the thick insulating film when the probe needle is most retracted )
D1 Outer diameter of metal conductor D2 Outer diameter of fuselage with thick insulation film D3 Outer diameter of part with thin insulation film D4 Inner diameter of guide hole of support plate on the side to be measured D5 Support plate on inspection device side Inner diameter of guide hole

Claims (7)

A probe needle used in inspections performed by contacting the end of the insulating film with the guide hole of the support plate on the side of the object to be measured that constitutes the probe unit and contacting the tip of the metal conductor with the object to be measured.
It has the metal conductor and the insulating film provided in a region other than at least both ends of the metal conductor, and the insulating film is a thin insulating film provided on the side to be measured and a film other than the side to be measured. It has a thick insulating film provided on the body portion, and the thick insulating film is configured such that its end portion hits a guide hole of a support plate on the side to be measured, and a thin insulating film on the side to be measured. Is a probe needle having a withstand voltage of 250 V or more. The probe needle according to claim 1, wherein the thickness of the thin insulating film on the side to be measured is in the range of 1 to 7 μm, and the thickness of the thick insulating film other than the tip skin is in the range of 3 to 20 μm. .. The probe needle according to claim 1 or 2, wherein the length L1 in the longitudinal direction of the thin insulating film on the side to be measured is 1.3 times longer than the thickness L2 of the support plate included in the probe unit. Claim 1 The insulating film is formed of a single layer or two or more layers made of one or more resin materials selected from polyurethane, polyester, polyesterimide, polyamideimide, polyimide and fluororesin. The probe needle according to any one of 3 to 3. It has a support plate arranged on the side to be measured, a support plate arranged on the inspection device side, and a probe needle attached to a guide hole provided in each of the at least two support plates, and supports the body to be measured. A probe unit used for inspections performed by contacting the end of the insulating film with the guide hole of the plate and bringing the tip of the metal conductor into contact with the object to be measured.
The probe needle has the metal conductor and the insulating film provided in a region other than at least both ends of the metal conductor, and the insulating film includes a thin insulating film provided on the side to be measured and the insulating film. It has a thick insulating film provided on the body portion other than the body to be measured, and the thick insulating film is configured such that its end portion hits a guide hole of a support plate on the body to be measured. A probe unit characterized in that the thin insulating film on the body side has a withstand voltage of 250 V or more. The probe unit according to claim 5, wherein the support plate on the side to be measured is made of metal. The probe unit according to claim 5 or 6, wherein the length L1 in the longitudinal direction of the thin insulating film on the side to be measured is 1.3 times longer than the thickness L2 of the support plate on the side to be measured.

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