JP2001305159A - Countermeasure type probe against static electricity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide of a counter measure type probe against static electricity that can surely remove static electricity and measure impedance without trouble at a low price. SOLUTION: An interior conductor 1 and an external conductor 2 are placed so as to be in the form of a coaxial line. The top end of the contacting pin 6 of the internal conductor 2 is protruded from the end face of the external conductor 1. The contacting part 8 of a ground circuit for contacting to the ground circuit 7 of a circuit board 3 is placed at the end face of the external conductor 1. In a state that the top end of the contacting pin 6 is contacted to a measured circuit 4 and the contacting part 8 of the ground circuit is not contacted to the ground circuit 7 of the circuit board 3, the contacting pin 6 is extended so as to contact to the external conductor 1. In a state that the contacting pin 6 is contacted to the measured circuit 4 of the circuit board 3 and the contacting part 8 of the ground circuit is contacted to the ground circuit 7, the contacting pin 6 is extensively formed to be a compressed state that the pin 6 is not contacted the external conductor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antistatic probe used for measuring the impedance of a circuit board such as a multilayer printed wiring board.

[0002]

2. Description of the Related Art In a circuit board used for electronic equipment, etc.,
The impedance matching between a circuit provided on a circuit board and a signal transmitted through the circuit is performed. Particularly, in the case of a circuit for transmitting a high-frequency signal (high-speed signal), this impedance matching is important. is there. Therefore, the circuit on the circuit board is designed so that impedance matching can be achieved with the signal to be transmitted, and the circuit board checks whether the impedance (value) of the circuit is within the allowable range from the design value (check). ), And those whose circuit impedance is out of a certain allowable range are discarded as defective.

Conventionally, when measuring the impedance of a circuit on a circuit board, mainly TDR (Time Domain Ref) is used.
rectrometry) method is used. In this method, a signal for impedance measurement such as a pulse or a step signal is transmitted to a transmission circuit including a signal circuit (circuit to be measured) whose impedance is to be measured and a reference ground circuit. A signal is detected, and an impedance value of a transmission circuit (circuit under test) is obtained by using a reflection coefficient obtained from the reflection signal.

When transmitting a signal to a transmission circuit, a probe is used as an intermediary for electrically connecting a cable derived from a signal generator provided in an impedance measuring device and the transmission circuit. Such a probe mainly includes a contact pin for a circuit to be measured for contacting a circuit to be measured and a contact pin for a ground circuit for contacting a ground circuit. A macrostrip structure with a plate-shaped dielectric layer sandwiched between pins, an inner conductor and an outer conductor arranged in a coaxial line shape, and a contact pin for a circuit under test is drawn out of the inner conductor and an outer conductor And a coaxial line structure formed by pulling out a ground circuit contact pin. In any of the above-described static electricity prevention probes, the tip of the contact pin for the circuit to be measured and the tip of the contact pin for the ground circuit are simultaneously brought into contact with the signal circuit and the ground circuit, respectively, to measure the impedance. Do it.

[0005]

One of the problems in the impedance measurement as described above is measures against static electricity. Generally, circuits on a circuit board such as a printed wiring board are easily charged by static electricity, and are charged only by being carried. The impedance is measured by bringing a probe into contact with a circuit to be measured on the charged circuit board. When the static electricity flows backward from the contact pin for the circuit to be measured of the probe, the signal generator of the impedance measuring instrument may be destroyed. In particular, in winter, the air was dry, and the impedance measuring instrument was frequently destroyed due to inadequate measures against static electricity.

Therefore, static electricity has been removed from a circuit board before impedance measurement.
For example, methods of measuring impedance on a conductive mat or removing electricity with an ionizer are generally performed.In these methods, a multilayer circuit under test or signal such as a recent multilayer printed wiring board is used. In a circuit board having a circuit, static electricity charged in a circuit to be measured or a signal circuit in an inner layer cannot be easily removed.
Therefore, as a method for reliably and effectively removing static electricity charged on a circuit to be measured or a signal circuit on a circuit board, the contact pin for the ground circuit of the probe is brought into contact with a circuit to be measured or a signal circuit in an inner layer to ground the static electricity. After that, the contact pins for the circuit under test are brought into contact with the circuit under test to measure the impedance. However, in this method, it is necessary to operate the probe so as to switch the two contact pins to the circuit to be measured and bring the circuit into contact with the circuit to be measured, and there is a problem that it takes time and effort to measure the impedance.

[0007] In addition, a changeover switch is sold as a static elimination system, but it is an expensive system that costs about 400,000 to 500,000 yen.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is possible to reliably remove static electricity and to measure an impedance in a short time without any trouble and at low cost. It is intended to provide a countermeasure type probe.

[0009]

According to the first aspect of the present invention, there is provided an antistatic probe A having an inner conductor 2 having contact pins 6 for making contact with a circuit 4 to be measured on a circuit board 3.
And the external conductor 1 are arranged in a coaxial line shape, and the ground circuit contact portion 8 for projecting the tip of the contact pin 6 from the end face 50 of the external conductor 1 and making contact with the ground circuit 7 of the circuit board 3 is formed by the external conductor. 1 is provided on the end face 50, and the tip of the contact pin 6 is
The contact pin 6 is extended so as to contact the external conductor 1 in a state where the contact pin 8 is in contact with the ground circuit 7 of the circuit board 3 and the contact pin 6 is in contact with the external conductor 1. The contact pin 6 is formed to be stretchable so that the contact pin 6 is compressed so that the contact pin 6 does not contact the external conductor 1 when the contact portion 8 contacts the ground circuit 7 of the circuit board 3. It is characterized by comprising.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the antistatic probe A according to the second aspect of the present invention comprises an outer conductor body 51 and a cover body 52 detachably attached to the outer conductor body 51. 1 and cover body 5
2, the end face 50 of the outer conductor 1 is formed.

According to a third aspect of the present invention, there is provided an antistatic probe A in which the ground circuit contact portion 8 is formed of conductive rubber in addition to the configuration of the first or second aspect. It is.

[0012]

Embodiments of the present invention will be described below.

As shown in FIG. 2, an antistatic probe A of the present invention is formed by arranging an outer conductor 1 and an inner conductor 2 in a coaxial line shape. The antistatic probe A is designed to have the same impedance as a coaxial cable to be described later, and is impedance-matched.

The outer conductor 1 is formed of an outer conductor body 51 and a cover body 52 detachably attached to a front end of the outer conductor body 51. The front side of the cover body 52 becomes the front side of the outer conductor 1. Is formed as an end face 50 of the first embodiment. The outer conductor body 51 is made of any conductive metal material such as copper or stainless steel, which is generally used for electrical components, or any material having the same conductivity and the same shape stability as the metal material. Can be formed. The outer conductor main body 51 is formed in a substantially cylindrical shape having the through hole 11, and the opening of the through hole 11 on the front surface of the outer conductor main body 51 is formed as the pin outlet 15 and the rear surface of the outer conductor main body 51. Through hole 11 in
Are formed as cable insertion ports 16. A male screw part 4 is provided substantially at the center of the front part of the outer conductor body 51.
0 is protruding.

On the middle outer peripheral surface of the outer conductor body 51, a mounting piece 18 is formed so as to protrude over the entire circumference.
By fixing the attachment piece 18 to another member, the antistatic probe A of the present invention can be attached to another member. Further, a thread 17 is formed on the outer peripheral surface of the rear part of the outer conductor main body 51, and a connector provided at an end portion of a coaxial cable described later can be screwed into the thread 17; The cable can be easily connected to the antistatic probe A of the present invention.

The cover body 52 is formed of the same material as that of the outer conductor body 51. As shown in FIGS. 3A and 3B, the cover body 52 has a female screw portion 41 opening on the rear surface. Is recessed. A moving space 43 is provided in the cover body 52 on the front side of the female screw portion 41. The diameter of the moving space 43 is formed slightly larger than the outer diameter of the locking piece 24 of the contact pin 6 of the internal conductor 2 described later. The rear surface of the moving space 43 is formed so as to open to the front surface of the female screw portion 41, and the moving space 43 and the female screw portion 41 are in communication. further,
On the front side of the moving space 43, a pin projecting hole 44 is provided in the cover body 52. The diameter of the pin projecting hole 44 is determined by the pin body 21 of the contact pin 6 of the internal conductor 2 described later.
Are formed slightly larger than the outer diameter of the engaging piece 24 of the contact pin 6 of the inner conductor 2. . The front surface of the pin protrusion hole 44 is formed so as to open to the front surface of the cover body 52 (the front end surface 50 of the outer conductor 1), and the rear surface of the pin protrusion hole 44 opens to the front surface of the moving space 43. The pin projecting hole 44 and the moving space 43 communicate with each other.

On the front surface of the cover 52, a ground circuit contact portion 8 is provided so as to protrude. The ground circuit contact portion 8 is integrally formed of the same material as the cover body 52,
The outer conductor 1 is formed in a substantially circular frame shape continuous in the circumferential direction. Further, the ground circuit contact portion 8 is
4 is formed so as to surround the opening. The ground circuit contact portion 8 can be formed in a substantially triangular cross section,
As a result, the area of the ground circuit contact portion 8 can be reduced by sharpening the tip of the ground circuit contact portion 8. The contact can be reliably made, and the ground circuit contact portion 8 and the ground circuit 7 can be contacted with a relatively strong force.

The ground circuit contact 8 may be formed at the periphery of the pin projecting hole 44 on the front surface of the cover 52 without projecting the ground circuit contact 8 as described above. In this case, the risk of damaging (damaging) the ground circuit 7 is reduced as compared with the case where the ground circuit contact portion 8 is formed so as to protrude. However, the ground circuit contact 8 is
It is preferable that the ground circuit contact portion 8 is formed so as to protrude from the front surface of the cover body 52 in order to easily and stably make contact and improve the contact property.

The male screw portion 40 of the outer conductor body 51
By screwing the female screw portion 41 of the cover body 52 with the cover body 52 and attaching the cover body 52 to the front side of the outer conductor body 51,
The outer conductor 1 can be formed. When the cover body 52 is attached to the outer conductor body 51 in this way, the through hole 11 of the outer conductor body 51 and the moving space 43 of the cover body 52 are provided.
Can be brought into a communication state. In addition, the outer conductor body 5
The cover body 52 can be removed from the outer conductor main body 51 by releasing the screw engagement between the male screw part 40 of the first and the female screw part 41 of the cover body 52. For example, when the ground circuit contact part 8 is worn or damaged. In such a case, only the cover body 52 can be replaced, and wear and breakage can be easily repaired without waste.

The inner conductor 2 is composed of a contact pin 6 and a connecting conductor 30. The contact pin 6 is formed of a conductive metal such as copper or nickel. As shown in FIG. 4, the contact pin 6 has a needle-shaped pin body 21 having a sharp tip and a cylindrical shape having an open front surface and a closed rear surface. , And a spring 23 such as a coil spring. The pin body 21 has a socket 2 at the front.
2 is inserted into the socket 22 so as to protrude from the front opening, and is formed in a state where the socket 22 covers other than the front part of the pin body 21. A locking piece 24 protrudes from an outer periphery of a portion (front portion) of the pin main body 21 protruding from the socket 22. The locking piece 24 has a disk shape and is formed over the entire circumference of the pin body 21.
Of the cover body 52 is smaller than the inner diameter of the moving space 43 of the cover body 52, and the pin projection hole 4 of the cover body 52 is
4 is formed larger than the inner diameter. The spring 23
Is provided between the rear end of the pin body 21 and the bottom surface of the socket 22. Further, the pin body 21 is formed so as to be slidable in the front-rear direction with respect to the socket 22. The pin body 21 is formed so as to be able to be inserted and removed from the socket 22. Further, the contact between the outer peripheral surface of the pin main body 21 and the inner peripheral surface of the socket 22 causes the
1 and the socket 22 are electrically connected.

The above-mentioned contact pin 6 is
Are formed so as to be slidable in the front-rear direction with respect to the socket 22, so that the pin body 21 is inserted into the socket 22 shallowly by the elastic force of the spring 23, and the front portion of the pin body 21 projects greatly from the socket 22. The pin body 21 is formed to extend and contract in the front-rear direction between a state in which the pin body 21 is deeply inserted into the socket 22 against the elastic force of the spring 23 and a compressed state in which the front portion of the pin body 21 projects slightly from the socket 22. Have been. In addition, the above-mentioned contact pin 6
Since the spring 23 is provided between the rear end of the pin body 21 and the bottom surface of the socket 22, the spring 23 has cushioning properties, and makes the pin body 21 elastically contact the circuit 4 to be measured on the circuit board 3. Can be done. The cushioning property in the present invention means that when measuring the impedance of the circuit 4 to be measured on the circuit board 3, it is determined whether the tip of the pin body 21, the tip of the ground circuit contact portion 8, or the contact portion of the contact pin 6 of the circuit 4 to be measured. In order to prevent weighting, it refers to the property of absorbing a weight above a certain threshold. In the contact pin 6 described above, the spring 23 is contracted (compressed) to exhibit this cushioning property, and the pin body 2
1 and reduction of damage to circuit under test 4 and pin body 2
1 can improve the contact with the circuit under test 4.

The connection conductor 30 is for electrically connecting the contact pin 6 and the core wire of the coaxial cable inserted into the through hole 11 from the cable insertion port 16 and is of the same kind as the contact pin 6 and the external conductor 1. It can be formed of the following materials. The connection conductor 30 is provided with a pin connection hole 31, and the pin connection hole 31 is formed so as to open on the front surface of the connection conductor 30. The connection conductor 30 is provided with a core wire connection hole 32, and the core wire connection hole 32 is
0 is formed on the rear surface. By inserting the rear part of the contact pin 6 into the pin connection hole 31, the connection conductor 30 is attached to the rear side of the contact pin 6, and the contact pin 6 and the connection conductor 30 are electrically connected.

The inner conductor 2 formed as described above is arranged concentrically inside the outer conductor 1 along the axial center line of the outer conductor 1. At this time, the portion of the socket 22 of the contact pin 6 of the inner conductor 2 is disposed inside the through hole 11 of the outer conductor main body 51 of the outer conductor 1. The core connection hole 32 of the connection conductor 30 faces the cable insertion port 16 side of the through hole 11 and is in communication with the cable insertion port 16. Further, the portion of the contact pin 6 on the front side of the socket 22 (the front portion of the pin main body 21) protrudes forward from the pin outlet 15 of the through hole 11, and the locking piece 24 of the contact pin 6 moves the cover body 52. It is arranged in the space 43 and is arranged inside the outer conductor 1. Further, a portion of the contact pin 6 on the front side of the locking piece 24 (the front end of the pin main body 21) is introduced into the pin projecting hole 44 from the rear opening, and the front end of the pin main body 21 is located on the front side of the cover body 52. It is arranged in a protruding state.

The distal end of the pin body 21 of the contact pin 6 is projected approximately 1 mm forward from the distal end of the ground circuit contact portion 8 which is normally provided on the front surface of the cover 52 of the external conductor 1. The protrusion dimension of the pin body 21 of the pin 6 can be set arbitrarily. Since the contact pin 6 is formed to be extendable and contractable as described above, the pin main body 21 of the contact pin 6 can be moved in the front-rear direction with respect to (the ground circuit contact portion 8 of) the external conductor 1. When the pin body 21 receives a load from the front side, the contact pin 6 is designed and manufactured so as to shrink at least until the tip of the pin body 21 and the tip of the ground circuit contact portion 8 are located in the same plane. . Also, the pin body 2 of the contact pin 6
The ground circuit contact portion 8 is formed so as to surround the front end of the circuit pin 1 and the pitch (interval) between the front end of the pin body 21 of the contact pin 6 and the front end of the ground circuit contact portion 8. It is formed so as to match the pitch.

The outer peripheral surface of the inner conductor 2 and the inner peripheral surface of the outer conductor 1 (through hole 1)
A dielectric layer 9 is formed between the two (1 wall surfaces). The dielectric layer 9 includes the outer conductor 1 and the inner conductor 2 adjacent to each other with the dielectric layer 9 interposed therebetween.
And to hold the internal conductor 2 in the through hole 11. The dielectric layer 9 is preferably formed of a material having a low dielectric constant and a low dielectric loss tangent in order to improve the characteristics at high frequencies. For example, PTFE (fluororesin such as polytetrafluoroethylene, PPO (polyphenylene ether), PPE (polyphenylene oxide)
Such a resin can be used, but any material having a low dielectric constant and a low dielectric loss tangent similar to that of the fluororesin, and having the same shape stability as the fluororesin can be used. When the contact pins 6 are held by the dielectric layer 9 as described above, the socket 22 is fixed, but since the pin body 21 is formed so as to be able to be inserted into and removed from the socket 22, the pin body 21 is connected to the external conductor 1. Can be inserted and removed from the outer conductor main body 51. Therefore, the pin body 21 whose life has expired due to wear due to contact with the circuit 4 to be measured is extracted from the socket 22, and a new pin body 21 is inserted into the socket 22.
Only can be replaced. That is, at the time of impedance measurement, the tip of the contact pin 6 repeatedly contacts the circuit 4 to be measured on the circuit board 3, so that the contact pin 6 is inevitably deteriorated. However, in the present invention, since only the pin body 21 can be replaced, the running cost can be reduced.

The inner peripheral surface of the pin projecting hole 44 provided on the cover body 52 of the outer conductor 1 (the wall surface of the pin projecting hole 44) and the outer peripheral surface of the tip of the contact pin 6 inserted into the pin projecting hole 44 An insulating layer 45 made of the same material as the above-described dielectric layer 9 is provided between them. Insulator layer 45
Is to secure insulation between the cover 52 and the tip of the contact pin 6 which are adjacent to each other.

The antistatic probe A of the present invention formed as described above is electrically connected to an oscilloscope or an impedance measuring instrument having an input signal generator for generating a signal for measurement via a coaxial cable. Things. When connecting the coaxial cable to the antistatic probe A, connect one end of the coaxial cable to the cable insertion port 1.
6 to the through hole 11, and the core wire (center conductor) at one end of the inserted coaxial cable is connected to the connection conductor 30 of the inner conductor 2.
Of the coaxial cable inserted into the through-hole 11 and the coated conductor (outer conductor) at one end of the coaxial cable is brought into contact with the wall surface of the through-hole 11 to connect the connector provided at the end of the coaxial cable to the external conductor. The first screw 17 is screwed. By connecting the end of the coaxial cable to the anti-static probe A in this way, the core wire of the coaxial cable can be electrically connected to the pin body 21 of the contact pin 6 and the coated conductor of the coaxial cable can be electrically connected. It can be electrically connected to the external conductor 1. The other end of the coaxial cable is connected to an impedance measuring device.

The antistatic probe A of the present invention is a TDR
It can be used for characteristic impedance measurement by a method or the like. In this case, a ground circuit 7 is formed on the surface of the circuit board 3 and the circuit under test 4 is provided inside the circuit board 3.
Are formed. The end face of the circuit 4 to be measured on the circuit board 3 and the end face of the ground circuit 7 are formed so as to be exposed from the end face of the circuit board 3 so that the tip of the contact pin 6 and the tip of the ground circuit contact portion 8 can contact each other. ing. The circuit under test 4 may be a signal circuit to which a signal is actually transmitted, or may be a test pattern for measuring impedance.

The antistatic probe A of the present invention
Is used to measure the impedance of the circuit under test 4 on the circuit board 3 as follows. First, the pin body 21 of the contact pin 6 is attached to the circuit 4 to be measured on the circuit board 3.
In the state (normal state) before the tip of the spring 23 contacts, the spring 23
The contact pin 6 is in an extended state due to the elastic force of
The pin main body 21 has moved to the front side. Therefore, the locking piece 24 of the contact pin 6 is also moved forward in the moving space 43, and the front surface of the locking piece 24 is formed at the rear opening edge of the pin projecting hole 44 in the moving space 43 by the cover 52. (The inner surface of the outer conductor 1). Therefore, the contact pins 6 of the outer conductor 1 and the inner conductor 2 are in an electrically conductive state, and a static elimination path composed of the tip of the contact pin 6 including the locking piece 24 and the outer conductor 1 is formed. Is grounded.

Next, the antistatic probe A is brought close to the circuit board 3 from the side, and the tip of the pin body 21 of the contact pin 6 is brought into contact with the end face of the circuit 4 to be measured as shown in FIG. Let it. At this time, the pin body 2 of the contact pin 6 is pressed with a small pressing force such that the contact pin 6 is not compressed.
1 is brought into contact with the end face of the circuit 4 to be measured,
In addition, the ground circuit contact portion 8 is set so as not to contact the ground circuit 7 of the circuit board 3. That is, the contact pin 6 comes into contact with the circuit under test 4 while the locking piece 24 is in contact with the cover body 52 of the external conductor 1 in the extended state. Flows through the neutralization path to the coated conductor of the coaxial cable as shown by the arrow A, and is discharged and removed.

Thereafter, the pin body 21 of the contact pin 6
1 is in contact with the end face of the circuit 4 to be measured.
As shown in (b), the antistatic probe A is further pressed toward the circuit board 3 to retreat the pin body 21 of the contact pin 6 against the elastic force of the spring 23 and to ground the external conductor 1. The contact portion 8 is brought into contact with the ground circuit 7 of the circuit board 3. As a result, the contact pin 6 comes into contact with the circuit under test 4 in a compressed state and the locking piece 24 is separated from the cover body 52 of the outer conductor 1. At this stage, the static elimination path is cut off and the impedance is reduced. Becomes a measurable state. Then, in this state, a signal for impedance measurement is supplied from the impedance measuring device to the internal conductor 2 (measurement path) through the core wire of the coaxial cable, and is supplied to the circuit under test 4 through the contact pins 6 of the internal conductor 2 as shown by arrow B. By inputting a signal for impedance measurement, the impedance of the circuit under test 4 from which static electricity has been removed can be measured.

After the impedance is measured, the antistatic probe A is moved away from the circuit board 3 so that the contact pin 6 and the ground circuit contact portion 8 do not contact the circuit 4 to be measured and the ground circuit 7. At the same time, the pressing force applied to the contact pin 6 is released, so that the contact pin 6
As a result, the engagement piece 24 of the contact pin 6 and the cover body 52 (the outer conductor 1) are brought into contact with each other, and a static elimination path is formed in the same manner as before the impedance measurement.

Since the antistatic probe A is brought into contact with very small end surfaces of the circuit 4 to be measured and the ground circuit 7, the position of the antistatic probe A can be adjusted while observing the contact portion in an enlarged manner using a camera or the like. It is preferred to do so. In the TDR measurement, it is preferable to treat all conductive portions of the circuit board 3 other than the circuit under test 4 as grounds (circuits) in order to measure impedance with high accuracy and stability. Contact pin 6
Since the ground circuit contact portion 8 is formed so as to surround the entire circumference of the circuit 4, the tip of the ground circuit contact portion 8 can be simultaneously contacted with a plurality of conductive portions in the vicinity of the end of the circuit 4 to be measured. In addition, impedance measurement with high stability can be performed.

The antistatic probe A of the present invention
Before measuring the impedance, the contact pins 6 that come into contact with the external conductor 1 can be brought into contact with the circuit 4 to be measured on the circuit board 3 and the impedance can be measured on a conductive mat as in the prior art. In addition, static electricity charged in the circuit under measurement 4 in the inner layer of the circuit board 3 can be easily and reliably eliminated as compared with a method of eliminating electricity by an ionizer. Also, as described above, the outer conductor 1
The contact pin 6 that comes into contact with the circuit 4
When the contact pins 6 are pressed further from the state where they are brought into contact with the circuit board 3 and the contact pins 6 are pressed, the contact between the contact pins 6 and the external conductor 1 is released, and An operation of bringing the ground circuit contact portion 8 into contact with the ground circuit 7 of the circuit board 3 and bringing the contact pins 6 closer to the circuit 4 to be measured of the circuit board 3 in order to remove static electricity before measuring impedance; The operation of bringing the ground circuit contact portion 8 close to the ground circuit 7 of the circuit board 3 with the contact pin 6 being in contact with the circuit under test 4 to enable impedance measurement is performed in substantially the same operation. It is possible to perform the measurement continuously, and it is not necessary to perform the measurement of the impedance in a short time. In addition, since the contact pins 6 and the external conductor 1 are used to remove static electricity, a separate large-scale device is not required, and static electricity can be removed at low cost. Except when the impedance is being measured, the contact pins 6 are always in contact with the outer conductor 1 to be electrically connected, and the inner conductor 2 is covered by the outer conductor 1 which is ground. In this state, the contact pins 6 are not electrically connected directly to the impedance measuring device. Can be prevented.

FIG. 5 shows another embodiment. The antistatic probe A can be formed in the same manner as in the above embodiment except for the cover 52. The ground circuit contact portion 8 of the cover body 52 in this embodiment is formed of an annular conductive rubber. As shown in FIG. 6A, the cover body 52 has an annular groove 55 which is open at the front surface thereof and surrounds the front opening of the pin projecting hole 44. b) As shown in (c), by inserting the rear portion of the annular ground circuit contact portion 8 into the groove portion 55, the conductive rubber ground circuit contact portion 8 is detachably attached to the cover body 52. Installed. Other configurations are formed in the same manner as the cover 52 of the above embodiment.

By attaching the cover body 52 to the outer conductor body 51 similar to the above, the antistatic probe A of the present invention can be formed. Since it is provided so as to protrude from the front surface of the cover 52, the ground circuit contact portion 8 is formed so as to surround the tip of the contact pin 6 protruding from the front surface of the cover body 52. In addition, as the conductive rubber, specifically, “EC-A” manufactured by Shin-Etsu Chemical Co., Ltd. can be used.

An antistatic probe A according to this embodiment
5 can be used for measuring impedance in the same manner as in the antistatic probe A of the above embodiment as shown in FIG. 5, but by forming the ground circuit contact portion 8 with conductive rubber, the ground circuit contact portion can be used. 8 has a cushioning property, so that the circuit board 3
Even if the ground circuit 7 has roughness such as irregularities, the ground circuit contact portion 8 can be deformed and brought into close contact with the roughness, and contact failure can be prevented. Damage to the cover body 52 can also be reduced and has a protective effect. In addition, by replacing only the ground circuit contact portion 8 according to wear, it is not necessary to replace the entire cover body 52 or the outer conductor body 51, and the life thereof can be extended.

[0038]

As described above, according to the first aspect of the present invention, the inner conductor and the outer conductor having the contact pins for contacting the circuit to be measured on the circuit board are arranged in a coaxial line shape, A ground circuit contact portion for projecting the tip of the pin from the end face of the external conductor and making contact with the ground circuit of the circuit board is provided on the end face of the external conductor, and the tip of the contact pin contacts the circuit to be measured of the circuit board; When the ground circuit contact portion is not in contact with the ground circuit of the circuit board, the contact pin is extended so as to contact the external conductor, the contact pin contacts the circuit to be measured on the circuit board, and the ground circuit contact portion is on the circuit board. Make sure that the contact pins are compressed so that they do not come into contact with the outer conductor when they are in contact with the ground circuit. Since the down telescopically formed,
Before impedance measurement, contact pins that come into contact with external conductors can be brought into contact with the circuit under test on the circuit board, and static electricity charged on the circuit under test on the inner layer of the circuit board can be easily and reliably eliminated. You can do it. Also, as described above, the contact pins that are in contact with the external conductor for removing static electricity are brought into contact with the circuit to be measured on the circuit board, and are further brought closer to the circuit board side to press the contact pins. The pin is compressed and the contact between the contact pin and the external conductor is released, and the ground circuit of the external conductor can be brought into contact with the ground circuit of the circuit board. An operation of bringing the circuit board into contact with the circuit to be measured close to the circuit to be measured and, in order to enable the measurement of impedance, bringing the contact pin into contact with the ground circuit of the circuit board with the contact pin in contact with the circuit to be measured. Operation can be performed continuously with almost the same operation, and static electricity is removed. In a short time measurements-impedance is something that would be time-consuming.

According to the invention of claim 2 of the present invention, the outer conductor is formed by the outer conductor body and the cover body detachably attached to the outer conductor body, and the end face of the outer conductor is formed by the cover body. In the case where the ground circuit contact portion is worn or damaged, only the cover body can be replaced, so that the worn or damaged can be easily repaired without waste.

Further, according to the invention of claim 3 of the present invention, since the ground circuit contact portion is formed of conductive rubber, even if the ground circuit of the circuit board has roughness such as unevenness, the ground circuit contact portion can be dealt with. Can be deformed and brought into close contact with each other, so that a contact failure does not occur, and damage to a ground circuit and a cover body can be reduced.

[Brief description of the drawings]

FIGS. 1A and 1B are cross-sectional views showing an example of an embodiment of the present invention.

FIG. 2 is a sectional view showing the whole of the same.

FIG. 3 (a) is a cross-sectional view showing an example of the above cover body.
(B) is a front view.

FIG. 4 is a cross-sectional view showing an example of the above contact pin.

FIG. 5 is a sectional view showing an example of another embodiment of the above.

6 (a) and 6 (b) are cross-sectional views and (c) is a front view showing another example of the above cover body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 External conductor 2 Internal conductor 3 Circuit board 4 Circuit under test 6 Contact pin 7 Ground circuit 8 Ground circuit contact part 50 End face 51 External conductor main body 52 Cover body

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsuhide Nagasou, Kazuma, Kazuma, Osaka 1048, Matsushita Electric Works, Ltd. In-house F term (reference) 2G011 AA02 AB04 AB07 AB08 AC14 AC32 AD01 AE01 AF06 2G028 AA04 BB00 BC01 CG08 HN01 HN09 2G032 AB08 AF01 AK04 5E346 BB02 BB04 BB06 GG32 GG34 HH33 9A001 BB06 JJ48 KK48

Claims (3)

[Claims] An internal conductor having contact pins for making contact with a circuit to be measured on a circuit board and an external conductor are arranged in a coaxial line shape, and the tips of the contact pins protrude from the end surface of the external conductor. A ground circuit contact portion for contacting the ground circuit of the present invention is provided on the end surface of the outer conductor, and the tip of the contact pin contacts the circuit to be measured on the circuit board and the ground circuit contact portion does not contact the ground circuit of the circuit board. The contact pin contacts the external conductor when the contact pin contacts the circuit to be measured on the circuit board and the ground circuit contact portion contacts the ground circuit on the circuit board. The contact pins are formed so as to be stretchable so as to be in a compressed state so as not to be compressed. Antistatic probe. 2. The method according to claim 1, wherein the outer conductor is formed by an outer conductor body and a cover body detachably attached to the outer conductor body, and an end face of the outer conductor is formed by the cover body. Antistatic probe as described. 3. The antistatic probe according to claim 1, wherein the ground circuit contact portion is formed of conductive rubber.