Patent Publication Number: US-11656246-B2

Title: Contact probe and probe unit

Description:
This application is a continuation of U.S. application Ser. No. 16/633,597 filed on Jan. 24, 2020, which is U.S. National Phase application of PCT/JP2018/028136, filed on Jul. 26, 2018, and claims the benefit of priority from Japanese Patent Application No. 2017-146975 filed on Jul. 28, 2017, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     The present disclosure relates to a contact probe and a probe unit. 
     In a technical field related to an electrical characteristics inspection of a semiconductor integrated circuit (IC), a technology is known related to a probe unit in which a plurality of contact probes (hereinafter, simply called probes) are arranged corresponding to external connection electrodes of the semiconductor IC. The probe unit includes the probes and a probe holder in which hole portions for accommodating the probes are formed (refer, for example, to Japanese Patent Application Laid-open No. 2016-70863). 
     In the probe unit, a signal probe for receiving and outputting an electrical signal from and to the semiconductor IC, a power supply probe for supplying power, and a grounding probe for supplying a ground potential are used as the above-mentioned probes. The signal probe, the power supply probe, and the grounding probe may have different outside diameters according to the functions thereof. In Japanese Patent Application Laid-open No. 2016-70863, the probe holder is provided with an insulating block in which holes corresponding to the diameters of the respective probes and forming a part of the above-mentioned hole portions are formed corresponding to the arrangement of the probes. In the probe holder, the arrangement of the various probes can be changed by providing the insulating block corresponding to the arrangement of the external connection electrodes of the semiconductor IC used. 
     SUMMARY 
     In the technique disclosed in Japanese Patent Application Laid-open No. 2016-70863, the insulating block with corresponding holes formed therein has to be prepared each time the arrangement of the external connection electrodes of the semiconductor IC is changed to different one. As a result, the number of insulating blocks increases with increase in number of arrangement patterns of the external connection electrodes of the semiconductor IC that can be used. 
     There is a need for a contact probe and a probe unit capable of simplifying the configuration of a probe holder in which the arrangement of the contact probes is changeable. 
     According to one aspect of the present disclosure, there is provided a probe unit including: a signal probe configured to receive and output a signal from and to a predetermined circuit structure; a power supply probe configured to supply power to the predetermined circuit structure; a grounding probe configured to supply a ground potential to the predetermined circuit structure; and a conductive probe holder including a plurality of hole portions in which the signal probe, the power supply probe, and the grounding probe are insertable, the plurality of hole portions having a same hole shape as one another, wherein the signal probe, the power supply probe, and the grounding probe inserted into the plurality of hole portions are interchangeable with one another to change an arrangement of the signal probe, the power supply probe, and the grounding probe. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic view illustrating an overall configuration of a probe unit according to a first embodiment of the present disclosure. 
         FIG.  2    is a partial sectional view illustrating a detailed structure of a probe holder and probes constituting the probe unit according to the first embodiment of the present disclosure. 
         FIG.  3    is a partial sectional view illustrating a configuration of the probe unit during an inspection of a semiconductor integrated circuit (IC) according to the first embodiment of the present disclosure. 
         FIG.  4    is a partial sectional view illustrating a detailed structure of a probe holder and probes constituting a probe unit according to a second embodiment of the present disclosure. 
         FIG.  5    is a partial sectional view illustrating a configuration when a cap is mounted on one of the probes constituting the probe unit according to the second embodiment of the present disclosure. 
         FIG.  6    is a partial sectional view illustrating a configuration of a cap according to a first modification of the second embodiment of the present disclosure. 
         FIG.  7    is a partial sectional view illustrating a configuration of a cap according to a second modification of the second embodiment of the present disclosure. 
         FIG.  8    is a partial sectional view illustrating a configuration of a cap according to a third modification of the second embodiment of the present disclosure. 
         FIG.  9    is a partial sectional view illustrating a detailed structure of a probe holder and the probes constituting a probe unit according to a third embodiment of the present disclosure. 
         FIG.  10    is a partial sectional view illustrating a detailed structure of the probe holder and probes constituting a probe unit according to a fourth embodiment of the present disclosure. 
         FIG.  11    is a partial sectional view illustrating a detailed structure of a probe holder and the probes constituting a probe unit according to a fifth embodiment of the present disclosure. 
         FIG.  12    is a top view illustrating a configuration of a probe holder constituting a probe unit according to a first modification of the fifth embodiment of the present disclosure. 
         FIG.  13    is a perspective sectional view illustrating the configuration of the probe holder constituting the probe unit according to the first modification of the fifth embodiment of the present disclosure. 
         FIG.  14    is a sectional view illustrating a configuration of a probe holder constituting a probe unit according to a second modification of the fifth embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments for carrying out the present disclosure will be described below in detail together with the accompanying drawings. The present disclosure is not limited by the following embodiments. The same parts illustrated in the drawings are denoted by the same reference signs. The drawings to be referred to in the following description merely schematically illustrate shapes, sizes, and positional relations to an extent sufficient to allow the details of the present disclosure to be understood. Accordingly, the present disclosure is not limited to only the shapes, sizes and positional relations illustrated in the drawings. 
     First Embodiment 
     A probe unit according to a first embodiment of the present disclosure is a component for receiving and outputting electrical signals from and to a predetermined circuit structure, such as a semiconductor integrated circuit (IC), and for supplying power and a ground potential thereto, and, in particular, to stably supply the ground potential, has a configuration in which grounding probes for supplying the ground potential are electrically connected to a probe holder made of a conductive material. 
       FIG.  1    is a schematic view illustrating a structure of a probe unit according to the first embodiment of the present disclosure. As illustrated in  FIG.  1   , the probe unit according to the first embodiment includes a circuit substrate  2  including a circuit for, for example, generating signals to be supplied to a semiconductor integrated circuit (IC)  1 , a probe holder  3  disposed on the circuit substrate  2  and including predetermined hole portions (not illustrated in  FIG.  1   ), and contact probes  4  (hereinafter, the contact probes are simply called “probes”) accommodated in the hole portions of the probe holder  3 . A holder member  5  for restraining the semiconductor IC  1  in use from being displaced is disposed on the circuit substrate  2  at an outer periphery of the probe holder  3 . 
     The circuit substrate  2  includes an inspection circuit for inspecting electrical characteristics of the semiconductor IC  1  to be inspected. The circuit substrate  2  has a configuration in which electrodes (not illustrated in  FIG.  1   ) for electrically connecting a built-in circuit to the probes  4  are arranged on a contact surface with the probe holder  3 . 
     The probe holder  3  is a component for accommodating the probes  4 . Specifically, the probe holder  3  includes a holder substrate made of a conductive material, such as a metal. The holder substrate has a structure in which the hole portions (holder holes) are formed in areas thereof corresponding to arrangement locations of the probes  4 , and the hole portions accommodate the probes  4 . 
     The probes  4  are components for electrically connecting the circuit included in the circuit substrate  2  to the semiconductor IC  1 . The probes  4  are broadly divided into three patterns according to, for example, types of signals to be supplied to the semiconductor IC  1 , and specifically include signal probes for receiving and outputting the electrical signals from and to the semiconductor IC  1 , power supply probes for supplying the power to the semiconductor IC  1 , and the grounding probes for supplying the ground potential to the semiconductor IC  1 . Hereinafter, each of the signal probes, the grounding probes, and the power supply probes will be called “probe” when collectively called, and will be called using the individual name when individually mentioned. 
       FIG.  2    is a partial sectional view illustrating a detailed configuration of the probe holder and the probes. As illustrated in  FIG.  2   , the probe holder  3  is laminated with a first member  31  located on an upper surface side and a second member  32  located on a lower surface side in  FIG.  2   . The first member  31  is fixed to the second member  32 , for example, using an adhesive material such as a resin or by screwing. In the present specification, a coaxial structure refers to a coincident axial structure in which the central axis of the signal probe coincides with the central axis of an inner surface of each of the hole portions. The configuration of the probe holder  3  will be described later. 
     The following describes structures of the probes. The following describes the structures of the respective probes in the order of a signal probe  6 , a power supply probe  7 , and a grounding probe  8 . 
     The signal probe  6  includes a first plunger  61  that contacts an inspection signal electrode of the semiconductor IC  1  when the semiconductor IC  1  is inspected, a second plunger  62  that contacts an electrode of the circuit substrate  2  including the inspection circuit, a coil spring  63  that is provided between the first plunger  61  and the second plunger  62  and connects the first plunger  61  to the second plunger  62  in an expandable and contractible manner, a first pipe member  64  that accommodates portions of the first plunger  61  and the second plunger  62  and accommodates the coil spring  63 , and collars  65  provided at both ends of the first pipe member  64 . The first plunger  61 , the second plunger  62 , and the coil spring  63  have the same axis line. When the signal probe  6  contacts the semiconductor IC  1 , the coil spring  63  expands and contracts in the axis line direction to reduce impact on a contact electrode of the semiconductor IC  1  and apply a load to the semiconductor IC  1  and the circuit substrate  2 . A thickness  1001  of the first pipe member  64  is indicated in  FIG.  2     
     The first plunger  61  is made of, for example, a conductive material, such as a metal. The first plunger  61  coaxially includes a distal end  61   a  having a shape of tapered ends, a flange  61   b  extending from a proximal end side of the distal end  61   a  and having a diameter larger than that of the distal end  61   a , and a boss  61   c  extending from an end of the flange  61   b  different from that on a side thereof continuing to the distal end  61   a  and having a diameter smaller than that of the flange  61   b . The distal end  61   a  has a crown shape. The distal end  61   a  and the flange  61   b  form a stepped portion on the first plunger  61 . The distal end and the flange also form a stepped portion in configurations given below. 
     The second plunger  62  is made of, for example, a conductive material, such as a metal. The second plunger  62  coaxially includes a distal end  62   a  having a shape of a tapered end, a flange  62   b  extending from a proximal end side of the distal end  62   a  and having a diameter larger than that of the distal end  62   a , a boss  62   c  extending from an end of the flange  62   b  different from that on a side thereof continuing to the distal end  62   a  and having substantially the same diameter as that of the boss  61   c , and a proximal end  62   d  extending from an end of the boss  62   c  different from that on a side thereof continuing to the flange  62   b  and having a diameter slightly smaller than that of the bosses  61   c  and  62   c . The second plunger  62  is movable in the axis line direction by the expansion/contraction action of the coil spring  63 , and is urged in a direction toward the circuit substrate  2  by an elastic force of the coil spring  63  to contact the electrode of the circuit substrate  2 . 
     The distal end  61   a  of the first plunger  61  may have a conical shape, and the distal end  62   a  of the second plunger  62  may have a crown shape. The distal ends  61   a  and  62   a  can each be changed in shape according to a contact target. 
     A wire rod made of, for example, a metal, a resin, or a material obtained by coating a metal surface with a resin is used as the coil spring  63 . The first plunger  61  side of the coil spring  63  serves as a solid coil portion  63   a  wound with substantially the same inside diameter as the diameter of the boss  61   c , while the second plunger  62  side of the coil spring  63  serves as a coarse coil portion  63   b  wound at a predetermined pitch with an inside diameter equal to or larger than the diameter of the proximal end  62   d . An end of the solid coil portion  63   a  is, for example, press-fitted onto the boss  61   c , and abuts on the flange  61   b . An end of the coarse coil portion  63   b  is press-fitted onto the boss  62   c , and abuts on the flange  62   b.    
     In the present specification, the configuration in which the first plunger and the second plunger are connected to the coil spring corresponds to an inner conductor in the probe. An outermost diameter  1000  of the inner conductor is indicated in  FIG.  2   . 
     The first pipe member  64  has a cylindrical shape in which the first plunger  61 , the second plunger  62 , and the coil spring  63  are insertable. The first pipe member  64  includes an impedance correction member  641  for correcting a value of characteristic impedance of the signal probe  6 , an inner circumferential plating  642  provided on an inner circumference of the impedance correction member  641 , and an outer circumferential plating  643  provided on an outer circumference of the impedance correction member  641 . 
     The impedance correction member  641  is a member obtained by forming a dielectric material having a predetermined dielectric constant into a cylindrical shape, and is an insulating member for correcting the value of the characteristic impedance of the signal probe  6 . Specifically, the impedance correction member  641  is adjusted in the dielectric constant of the dielectric material and the outside diameter of the cylindrical shape, and as a result, corrects the characteristic impedance of the signal probe  6  so as to be equal to, for example, a generally employed value of 50 ohms. The impedance correction member  641  is made of, for example, an insulating material such as polytetrafluoroethylene. 
     The inner circumferential plating  642  is a conductive coating layer provided on the inner circumference of the impedance correction member  641 . The inner circumferential plating  642  includes a first plating  642   a  provided on the inner circumference of the impedance correction member  641  and a second plating  642   b  that covers the first plating  642   a . The first plating  642   a  is formed of, for example, nickel. The second plating  642   b  is formed of, for example, gold. 
     The outer circumferential plating  643  is a conductive coating layer provided on the outer circumference of the impedance correction member  641 . The outer circumferential plating  643  includes a first plating  643   a  provided on the outer circumference of the impedance correction member  641  and a second plating  643   b  that covers the first plating  643   a . The first plating  643   a  is formed of, for example, nickel. The second plating  643   b  is formed of, for example, gold. 
     While the first pipe member  64  is subjected to the plating treatment of two layers, the number of layers may be one, or multiple, such as three or more. Such plating treatment is applied to form the conductive layers on the first pipe member  64 . 
     Each of the collars  65  is made of, for example, a conductive material, such as a metal, and has a hollow cylindrical shape. The outer circumference of the collar  65  has a diameter that can be press-fitted or fixed into the inner circumference of the first pipe member  64 . The inner circumference (hollow portion) of the collar  65  has a diameter equal to or slightly larger than the diameter of the distal end of one of the first plunger  61  and the second plunger  62  inserted in the collar  65 . The collars  65  are provided at both ends of the first pipe member  64 , and form stepped portions in conjunction with the inner circumferential surface of the first pipe member  64 . The flange  61   b  of the first plunger  61  and the flange  62   b  of the second plunger  62  abut on the stepped portions to be prevented from coming off of the first pipe member  64 . The collars  65  are press-fitted to be fixed to the inner circumference of the first pipe member  64 , or fixed to the inner circumference of the first pipe member  64  by soldering or with an adhesive. 
     The power supply probe  7  includes a first plunger  71  that contacts a power supply electrode of the semiconductor IC  1  when the semiconductor IC  1  is inspected, a second plunger  72  that contacts an electrode of the circuit substrate  2  including the inspection circuit, a coil spring  73  that is provided between the first plunger  71  and the second plunger  72  and connects the first plunger  71  to the second plunger  72  in an expandable and contractible manner, a second pipe member  74  that accommodates portions of the first plunger  71  and the second plunger  72  and accommodates the coil spring  73 , and collars  75  provided at both ends of the second pipe member  74 . The first plunger  71 , the second plunger  72 , and the coil spring  73  have the same axis line. A thickness  1007  of the second pipe member  74  is indicated in  FIG.  2   . 
     The first plunger  71  is made of, for example, a conductive material, such as a metal. The first plunger  71  coaxially includes a distal end  71   a  having a shape of tapered ends, a flange  71   b  extending from a proximal end side of the distal end  71   a  and having a diameter larger than that of the distal end  71   a , and a boss  71   c  extending from an end of the flange  71   b  different from that on a side thereof continuing to the distal end  71   a  and having a diameter smaller than that of the flange  71   b . The distal end  71   a  has a crown shape. 
     The second plunger  72  is made of, for example, a conductive material, such as a metal. The second plunger  72  coaxially includes a distal end  72   a  having a shape of a tapered end, a flange  72   b  extending from a proximal end side of the distal end  72   a  and having a diameter larger than that of the distal end  72   a , a boss  72   c  extending from an end of the flange  72   b  different from that on a side thereof continuing to the distal end  72   a  and having substantially the same diameter as that of the boss  71   c , and a proximal end  72   d  extending from an end of the boss  72   c  different from that on a side thereof continuing to the flange  72   b  and having a diameter slightly smaller than that of the bosses  71   c  and  72   c . The second plunger  72  is movable in the axis line direction by the expansion/contraction action of the coil spring  73 , and is urged in a direction toward the circuit substrate  2  by an elastic force of the coil spring  73  to contact the electrode of the circuit substrate  2 . 
     In the same way as the distal ends  61   a  and  62   a , the distal ends  71   a  and  72   a  are not limited in shape, and can each be changed in shape according to the contact target. 
     A wire rod made of, for example, a metal, a resin, or a material obtained by coating a metal surface with a resin is used as the coil spring  73 . The first plunger  71  side of the coil spring  73  serves as a solid coil portion  73   a  wound with substantially the same inside diameter as the diameter of the boss  71   c , while the second plunger  72  side of the coil spring  73  serves as a coarse coil portion  73   b  wound at a predetermined pitch with an inside diameter equal to or larger than the diameter of the proximal end  72   d . An end of the solid coil portion  73   a  is, for example, press-fitted onto the boss  71   c , and abuts on the flange  71   b . An end of the coarse coil portion  73   b  is press-fitted onto the boss  72   c , and abuts on the flange  72   b.    
     The second pipe member  74  has a cylindrical shape in which the first plunger  71 , the second plunger  72 , and the coil spring  73  are insertable. The second pipe member  74  includes an insulating member  741  made of an insulating material, an inner circumferential plating  742  provided on an inner circumference of the insulating member  741 , and an outer circumferential plating  743  provided on an outer circumference of the insulating member  741 . 
     The insulating member  741  is a member obtained by forming the insulating material into a cylindrical shape. Specifically, the insulating member  741  is formed of the insulating material, such as ceramic or polytetrafluoroethylene. 
     The inner circumferential plating  742  includes a first plating  742   a  provided on the inner circumference of the insulating member  741  and a second plating  742   b  that covers the first plating  742   a . The first plating  742   a  is formed of, for example, nickel. The second plating  742   b  is formed of, for example, gold. 
     The outer circumferential plating  743  includes a first plating  743   a  provided on the outer circumference of the insulating member  741  and a second plating  743   b  that covers the first plating  743   a . The first plating  743   a  is formed of, for example, nickel. The second plating  743   b  is formed of, for example, gold. 
     While the second pipe member  74  is subjected to the plating treatment of two layers, the number of layers may be one, or multiple, such as three or more. 
     Each of the collars  75  is made of, for example, a conductive material, such as a metal, and has a hollow cylindrical shape. The outer circumference of the collar  75  has a diameter that can be press-fitted or fixed into the inner circumference of the second pipe member  74 . The inner circumference of the collar  75  has a diameter equal to or slightly larger than the diameter of the distal end of one of the first plunger  71  and the second plunger  72  inserted in the collar  75 . The collars  75  are provided at both ends of the second pipe member  74 , and form stepped portions in conjunction with the inner circumferential surface of the second pipe member  74 . The flange  71   b  of the first plunger  71  and the flange  72   b  of the second plunger  72  abut on the stepped portions to be prevented from coming off of the second pipe member  74 . 
     The grounding probe  8  includes a first plunger  81  that contacts a grounding electrode of the semiconductor IC  1  when the semiconductor IC  1  is inspected, a second plunger  82  that contacts an electrode of the circuit substrate  2  including the inspection circuit, a coil spring  83  that is provided between the first plunger  81  and the second plunger  82  and connects the first plunger  81  to the second plunger  82  in an expandable and contractible manner, a third pipe member  84  that accommodates portions of the first plunger  81  and the second plunger  82  and accommodates the coil spring  83 , and collars  85  provided at both ends of the third pipe member  84 . The first plunger  81 , the second plunger  82 , and the coil spring  83  have the same axis line. A thickness  1008  of the third pipe member  84  is indicated in  FIG.  2   . 
     The first plunger  81  is made of, for example, a conductive material, such as a metal. The first plunger  81  coaxially includes a distal end  81   a  having a shape of tapered ends, a flange  81   b  extending from a proximal end side of the distal end  81   a  and having a diameter larger than that of the distal end  81   a , and a boss  81   c  extending from an end of the flange  81   b  different from that on a side thereof continuing to the distal end  81   a  and having a diameter smaller than that of the flange  81   b . The distal end  81   a  has a crown shape. 
     The second plunger  82  is made of, for example, a conductive material, such as a metal. The second plunger  82  coaxially includes a distal end  82   a  having a shape of a tapered end, a flange  82   b  extending from a proximal end side of the distal end  82   a  and having a diameter larger than that of the distal end  82   a , a boss  82   c  extending from an end of the flange  82   b  different from that on a side thereof continuing to the distal end  82   a  and having substantially the same diameter as that of the boss  81   c , and a proximal end  82   d  extending from an end of the boss  82   c  different from that on a side thereof continuing to the flange  82   b  and having a diameter slightly smaller than that of the bosses  81   c  and  82   c . The second plunger  82  is movable in the axis line direction by the expansion/contraction action of the coil spring  83 , and is urged in a direction toward the circuit substrate  2  by an elastic force of the coil spring  83  to contact the electrode of the circuit substrate  2 . 
     In the same way as the distal ends  61   a  and  62   a , the distal ends  81   a  and  82   a  are not limited in shape, and can each be changed in shape according to the contact target. 
     A wire rod made of, for example, a metal, a resin, or a material obtained by coating a metal surface with a resin is used as the coil spring  83 . The first plunger  81  side of the coil spring  83  serves as a solid coil portion  83   a  wound with substantially the same inside diameter as the diameter of the boss  81   c , while the second plunger  82  side of the coil spring  83  serves as a coarse coil portion  83   b  wound at a predetermined pitch with an inside diameter equal to or larger than the diameter of the proximal end  82   d . An end of the solid coil portion  83   a  is, for example, press-fitted onto the boss  81   c , and abuts on the flange  81   b . An end of the coarse coil portion  83   b  is press-fitted onto the boss  82   c , and abuts on the flange  82   b.    
     The third pipe member  84  has a cylindrical shape in which the first plunger  81 , the second plunger  82 , and the coil spring  83  are insertable. The third pipe member  84  is made of a conductive material, such as a metal. The outer circumferential surface and the inner circumferential surface of the third pipe member  84  may be plated. 
     Each of the collars  85  is made of, for example, a conductive material, such as a metal, and has a hollow cylindrical shape. The outer circumference of the collar  85  has a diameter that can be press-fitted or fixed into the inner circumference of the third pipe member  84 . The inner circumference of the collar  85  has a diameter equal to or slightly larger than the diameter of the distal end of one of the first plunger  81  and the second plunger  82  inserted in the collar  85 . The collars  85  are provided at both ends of the third pipe member  84 , and form stepped portions in conjunction with the inner circumferential surface of the third pipe member  84 . The flange  81   b  of the first plunger  81  and the flange  82   b  of the second plunger  82  abut on the stepped portions to be prevented from coming off of the third pipe member  84 . 
     In the first embodiment, the diameters of the outer circumferences of the first pipe member  64 , the second pipe member  74 , and the third pipe member  84  are the same as one another. 
     As described above, the probe holder  3  is laminated with the first member  31  and the second member  32 . The first member  31  and the second member  32  are each made of, for example, a conductive material, such as a metal. The first member  31  and the second member  32  are provided with the same numbers of holder holes  33  and  34 , respectively, serving as the hole portions for accommodating the probes  4 . The holder holes  33  and  34  for accommodating the probes  4  are formed such that the axis lines of each of the holder holes  33  and corresponding one of the holder holes  34  coincide with each other. The holder holes  33  and  34  are formed in positions covering all possible wiring patterns in the semiconductor IC  1  to be inspected. In addition to the metal, any conductive materials are applicable as the first member  31  and the second member  32 . From the viewpoint of strength as the probe holder, the first member  31  and the second member  32  are each preferably made of a metal material (including an alloy). 
     Each of the holder holes  33  and  34  has a stepped hole shape having different diameters along a penetration direction. In other words, the holder hole  33  is constituted by a small diameter portion  33   a  having an opening on an upper surface side of the first member  31  and a large diameter portion  33   b  having a diameter larger than that of the small diameter portion  33   a . The small diameter portion  33   a  has a diameter smaller than that of the outer circumference of the above-described pipe members (the pipe members  64 ,  74 , and  84 ) and larger than that of the distal ends (the distal ends  61   a ,  71   a , and  81   a ) of the first plungers. The large diameter portion  33   b  has a diameter equal to that of the outer circumference of the pipe members (the pipe members  64 ,  74 , and  84 ), or a diameter smaller than the outside diameter  1002  of the pipe members within a press-fittable range, or a diameter larger than the outside diameter  1002  of the pipe members within an allowable range of a positional deviation of each of the probes  4  in the probe holder  3 . 
     The holder hole  34  is constituted by a small diameter portion  34   a  having an opening on a lower end surface of the probe holder  3  and a large diameter portion  34   b  having a diameter larger than that of the small diameter portion  34   a . The small diameter portion  34   a  has a diameter smaller than that of the outer circumference of the above-described pipe members (the pipe members  64 ,  74 , and  84 ) and larger than that of the distal ends (the distal ends  62   a ,  72   a , and  82   a ) of the second plungers. The large diameter portion  34   b  is preferably equivalent to the large diameter portion  33   b , and has a diameter equal to that of the outer circumference of the pipe members (the pipe members  64 ,  74 , and  84 ), or a diameter smaller than the outside diameter  1002  of the pipe members within a press-fittable range, or a diameter larger than the outside diameter  1002  of the pipe members within an allowable range of a positional deviation of each of the probes  4  in the probe holder  3 . 
     The following describes electrical operations of the probe unit according to the present embodiment during the inspection of the semiconductor IC.  FIG.  3    is a partial sectional view illustrating a configuration of the probe unit during the inspection of the semiconductor integrated IC according to the first embodiment of the present disclosure. 
     First, an electrical operation of the grounding probe  8  will be described. In the present embodiment, the grounding probe  8  is configured to not only supply a potential from the circuit substrate  2  through electrodes  100   c  and  200   c  to the semiconductor IC  1 , but also receive a potential from the probe holder  3  and supply the ground potential to the semiconductor IC  1 . In other words, as illustrated also in  FIG.  2   , inner surfaces of the holder holes  33  and  34  accommodating the grounding probe  8  have a configuration of directly contacting the outer circumferential surface of the grounding probe  8 , specifically, the third pipe member  84 . Since the probe holder  3  is made of the conductive material as described above, the grounding probe  8  is electrically connected to the probe holder  3 . Accordingly, an internal charge can freely traverse between the grounding probe  8  and the probe holder  3 , so that the potential supplied by the grounding probe  8  has the same value as the potential of the probe holder  3 . 
     Subsequently, an electrical operation of the signal probe  6  will be described. Each of the signal probes  6  receives an electrical signal generated in the circuit substrate  2  from an electrode  200   a , and receives and outputs the received electrical signal through an electrode  100   a  to the semiconductor IC  1 . In the signal probe  6 , the electrical signal is received from the second plunger  62 , flows through the inner circumferential plating  642  via the collar  65  on the second plunger  62  side, and then flows into the first plunger  61  via the collar  65  on the first plunger  61  side. When the proximal end  62   d  is made in contact with the solid coil portion  63   a , the electrical signal may flow from the proximal end  62   d  to the solid coil portion  63   a , and then flow from the solid coil portion  63   a  into the first plunger  61 . 
     Subsequently, an electrical operation of the power supply probe  7  will be described. The power supply probe  7  receives supply power generated in the circuit substrate  2  from an electrode  200   b  of the circuit substrate  2 , and receives and outputs the received power through an electrode  100   b  of the semiconductor IC  1  to the semiconductor IC  1 . In the power supply probe  7 , the power is received from the second plunger  72 , flows through the inner circumferential plating  742  via the collar  75  on the second plunger  72  side, and then flows into the first plunger  71  via the collar  75  on the first plunger  71  side. When the proximal end  72   d  is made in contact with the solid coil portion  73   a , the power may flow from the proximal end  72   d  to the solid coil portion  73   a , and then flow from the solid coil portion  73   a  into the first plunger  71 . 
     The following describes an advantage obtained by using the impedance correction member  641  to correct the characteristic impedance of the signal probe  6 . It is known that, generally in an electronic circuit dealing with an alternating current signal, an amount of the signal corresponding to a ratio between different impedance values are reflected at a location where wires having the different impedance values are connected to each other, and the signal is restrained from propagating. This phenomenon also applies to a relation between the semiconductor IC  1  used and the signal probe  6 , and when the characteristic impedance of the semiconductor IC  1  has a value greatly different from that of the characteristic impedance of the signal probe  6 , a loss of the electrical signal occurs, and the electrical signal is distorted. 
     The percentage of the signal reflection generated at the connection location by the difference in characteristic impedance is known to increase as the electrical length (length of a propagation path with respect to a period of the electrical signal) of the signal probe  6  increases. In other words, in the case of the probe unit according to the present embodiment, the percentage of the signal reflection of the electrical signal increases with increase in speed, that is, frequency of the semiconductor IC  1 . Accordingly, in the case of producing the probe unit corresponding to the semiconductor IC  1  driven at a high frequency, it is important to accurately perform what is called impedance matching to match the value of the characteristic impedance of the signal probe  6  with that of the semiconductor IC  1 . 
     In the first embodiment described above, the hole portions formed of the holder holes  33  and  34  are formed in the probe holder  3 , and the signal probes  6 , the power supply probes  7 , and the grounding probes  8  can be arranged in the hole portions. This configuration allows a change in arrangement of the signal probes  6 , the power supply probes  7 , and the grounding probes  8  with respect to the respective hole portions. In this case, the arrangement can be changed, for example, by removing the first member  31  from the second member  32 , accommodating predetermined types of the probes in predetermined holes of the holder holes  34 , and mounting again the first member  31  on the second member  32 . According to the first embodiment, the hole portions having the same shape only need to be formed in positions where the probes can be arranged in the probe holder  3 . Thus, the simple holder configuration allows the change in arrangement of the contact probes. 
     The impedance correction members are conventionally bonded to be fixed to the holder holes using, for example, an adhesive. In the first embodiment, however, the bonding process is not required, and work processes can be reduced when the probe unit is assembled. Since the configuration of the holder holes includes no impedance member, the holder holes can be restrained from being crushed or broken. 
     In the signal probe  6  according to the first embodiment, the inner circumferential plating  642  is formed on the inner circumference of the first pipe member  64 . Therefore, the collars  65  can be press-fitted to be fixed to the inner circumference of the first pipe member  64 , or fixed to the inner circumference of the first pipe member  64  with the adhesive, and in addition, can be fixed to the inner circumference of the first pipe member  64  by the soldering. In the same way, in the power supply probe  7 , the inner circumferential plating  742  is formed on the inner circumference of the second pipe member  74 . Therefore, the collars  75  can be press-fitted to be fixed to the inner circumference of the second pipe member  74 , or fixed to the inner circumference of the second pipe member  74  with the adhesive, and in addition, can be fixed to the inner circumference of the second pipe member  74  by the soldering. 
     In the signal probe  6  according to the first embodiment, the outer circumferential plating  643  is formed on the outer circumference of the first pipe member  64 . Therefore, the entire outer circumference of the first pipe member  64  can be set to the ground potential through the conductive probe holder  3 . This configuration allows some of the hole portions of the probe holder  3  to communicate with one another, and can ensure an adjustable range in thickness of the impedance correction member  641 . 
     In the power supply probe  7  according to the first embodiment, the inner circumferential plating  742  is formed on the inner circumference of the second pipe member  74 . Therefore, two paths of a path through the second pipe member  74  and a path through the coil spring  73  can be used as conducting paths for the power. This configuration can increase the allowable current of the power supply probe  7 . 
     In each of the probes according to the first embodiment, the first plunger, the second plunger, and the coil spring in the pipe member can be easily taken out by removing one of the collars. This configuration allows an easy replacement of the first plunger, the second plunger, and the coil spring when the probe is repaired. 
     In the first embodiment, each pair of the holder holes  33  and  34  for holding any one of the probes have been described as being independently provided. However, some of the adjacent holder holes may communicate with each other. For example, communications may be established between the large diameter portions  33   b  of the adjacent holder holes  33  and between the large diameter portions  34   b  of the adjacent holder holes  34 , or a communication may be established between the large diameter portions  33   b  of the holder holes  33 , with the holder holes  34  being independent from one another. 
     Second Embodiment 
       FIG.  4    is a partial sectional view illustrating a detailed structure of a probe holder and probes constituting a probe unit according to a second embodiment of the present disclosure. In the above-described first embodiment, the configuration has been described in which both ends of the pipe members are provided with the collars. The present disclosure is, however, not limited to this configuration. In the second embodiment, only the first plunger sides are provided with the collars. 
     The probe unit according to the second embodiment includes the circuit substrate  2  ( FIG.  1   ) including the circuit for, for example, generating the signals to be supplied to the semiconductor IC  1  ( FIG.  1   ), a probe holder  3 A disposed on the circuit substrate  2  and including predetermined hole portions, and probes (signal probes  6 A, power supply probes  7 A, and grounding probes  8 A) accommodated in the hole portions of the probe holder  3 A. 
     Each of the signal probes  6 A is the same as the signal probe  6  except that the collar  65  on the second plunger  62  side is excluded from the configuration of the signal probe  6  described above. In the same way, each of the power supply probes  7 A is the same as the power supply probe  7  described above except that the collar  75  on the side of the second plunger  72  of the power supply probe  7  is excluded, and each of the grounding probes  8 A is the same as the grounding probe  8  described above except that the collar  85  on the side of the second plunger  82  of the grounding probe  8  is excluded. 
     The probe holder  3 A includes a holder substrate  35  made of a conductive material, such as a metal, and an insulating substrate  36  provided on one surface of the holder substrate  35 . The probe holder  3 A has a structure in which hole portions (holder holes) are formed in areas thereof corresponding to arrangement locations of the probes and the hole portions accommodate the probes. 
     The probe holder  3 A is laminated with the holder substrate  35  and the insulating substrate  36 . The holder substrate  35  is made of, for example, a conductive material, such as a metal. The insulating substrate  36  is made of, for example, an insulating material, such as polyether ether ketone (PEEK), polyimide (PI), or polyethersulfone (PES). In addition to the metal, any conductive materials are applicable for the holder substrate  35 . From the viewpoint of strength as the probe holder, the holder substrate  35  is preferably made of a metal material (including an alloy). 
     The holder substrate  35  and the insulating substrate  36  are provided with the same numbers of holder holes  37  and  38 , respectively, serving as the hole portions for accommodating the probes. The holder holes  37  and  38  for accommodating the probes are formed such that the axis lines of each of the holder holes  37  and corresponding one of the holder holes  38  coincide with each other. The holder holes  37  and  38  are formed in positions covering all possible wiring patterns in the semiconductor IC  1  to be inspected. 
     Each of the holder holes  37  has a stepped hole shape having different diameters along a penetration direction. In other words, the holder hole  37  is constituted by a small diameter portion  37   a  having an opening on an upper surface side of the holder substrate  35  and a large diameter portion  37   b  having an opening on a lower side of the holder substrate  35  on which the insulating substrate  36  is disposed and having a diameter larger than that of the small diameter portion  37   a . The small diameter portion  37   a  has a diameter smaller than that of the outer circumference of the above-described pipe members (the pipe members  64 ,  74 , and  84 ) and larger than that of the distal ends (the distal ends  61   a ,  71   a , and  81   a ) of the first plungers. The large diameter portion  37   b  has a diameter equal to that of the outer circumference of the pipe members (the pipe members  64 ,  74 , and  84 ), or a diameter smaller than the outside diameter  1002  of the pipe members within a press-fittable range, or a diameter larger than the outside diameter  1002  of the pipe members within an allowable range of a positional deviation of each of the probes in the probe holder  3 A. 
     Each of the holder holes  38  has a hole shape having an opening on a lower end surface of the probe holder  3 A. The holder hole  38  has a diameter smaller than that of the outer circumference of the above-described pipe members (the pipe members  64 ,  74 , and  84 ) and larger than that of the distal ends (the distal ends  62   a ,  72   a , and  82   a ) of the second plungers. 
     In the second embodiment, the large diameter portion  37   b  and the holder hole  38  form a stepped portion. For example, the flange  62   b  of the second plunger  62  abuts on the stepped portion to be prevented from coming off of the probe holder  3 A. 
     In the probe unit configured as described above, the plungers and the coil springs operate in the same way as in the first embodiment described above during the inspection of the semiconductor IC. In the second embodiment, for example, the proximal end of the second plunger contacts the solid coil portion of the coil spring. In the second embodiment, the electrical signal flowing through the probe unit flows from the second plunger into the first plunger via the solid coil portion. For example, in the signal probe  6 A, the electrical signal having flowed into the second plunger  62  flows from the proximal end  62   d  to the solid coil portion  63   a , and then flows from the solid coil portion  63   a  into the first plunger  61 . The flange  62   b  may contact the inner circumferential plating  642  of the first pipe member  64  so as to let the electrical signal flow from the second plunger  62  to the inner circumferential plating  642  of the first pipe member  64 . 
     The signal probe  6 A, the power supply probe  7 A, and the grounding probe  8 A all include no collar on the second plunger side. Therefore, the probe as a separate component may allow the first plunger, the second plunger, and the coil spring to come off of the pipe member. When each of the probes is handled separately, a cap is preferably used to prevent the plungers and the coil spring from coming off of the pipe member. 
       FIG.  5    is a partial sectional view illustrating a configuration when the cap is mounted on one of the probes constituting the probe unit according to the second embodiment of the present disclosure. While  FIG.  5    demonstrates an example in which a cap  300  is mounted on the signal probe  6 A, the same cap is also mounted on the power supply probe  7 A and the grounding probe  8 A. 
     The cap  300  is provided with an accommodating portion  301  having a hole shape for accommodating a part of the distal end  62   a  of the second plunger  62  and a projecting portion  302  cylindrically projecting along an inner circumferential surface of the accommodating portion  301 . The projecting portion  302  has an inside diameter equal to the diameter of the accommodating portion  301  and an outside diameter having a size equal to or press-fittable to the inside diameter  1003  of the first pipe member  64 . 
     The cap  300  is mounted over an opening on the second plunger  62  side of the first pipe member  64  to prevent the second plunger  62  from coming off of the first pipe member  64 . In this case, the projecting portion  302  enters a gap between the distal end  62   a  and the first pipe member  64 , and abuts on the flange  62   b  to prevent the distal end of the distal end  62   a  from interfering with the bottom of the accommodating portion  301 . The projecting portion  302  is press-fitted into the first pipe member  64 , and thereby, the cap  300  is held by the first pipe member  64 . 
     In the second embodiment described above, the hole portions formed of the holder holes  37  and  38  are formed in the probe holder  3 A, and the signal probes  6 A, the power supply probes  7 A, and the grounding probes  8 A can be arranged in the hole portions. This configuration allows a change in arrangement of the signal probes  6 A, the power supply probes  7 A, and the grounding probes  8 A with respect to the respective hole portions. According to the second embodiment, since the hole portions having the same shape only need to be formed in positions where the probes can be arranged in the probe holder  3 A. Thus, the simple holder configuration allows the change in arrangement of the contact probes. 
     In the second embodiment, the large diameter portion  37   b  and the holder hole  38  form the stepped portion in the probe holder  3 A, and the stepped portion has the function to prevent the second plunger from coming off. Such a configuration eliminates the need for the collar on the second plunger side in each of the signal probe  6 A, the power supply probe  7 A, and the grounding probe  8 A, so that the number of components can be reduced. 
     In the second embodiment, since the cap is mounted on each of the probes to prevent the first plunger, the second plunger, and the coil spring from coming off of the pipe member, the probe can be easily handled separately. 
     First Modification of Second Embodiment 
       FIG.  6    is a partial sectional view illustrating a configuration of a cap according to a first modification of the second embodiment of the present disclosure. In the second embodiment described above, the projecting portion  302  of the cap  300  has been described as being press-fitted into the first pipe member  64  to be held by the first pipe member  64 . However, in the first modification, a cap  310  holds the first pipe member  64 . While  FIG.  6    demonstrates an example in which the cap  310  is mounted on the signal probe  6 A, the same cap is also mounted on the power supply probe  7 A and the grounding probe  8 A. 
     An accommodating portion  311  is formed in the cap  310 , and includes a first accommodating portion  311   a  having a hole shape for accommodating a part of the distal end  62   a  of the second plunger  62  and a second accommodating portion  311   b  having a hole shape for accommodating a part of the first pipe member  64 . The second accommodating portion  311   b  has an inside diameter having a size equal to or press-fittable to the outside diameter of the first pipe member  64 . 
     The cap  310  is mounted over the opening on the second plunger  62  side of the first pipe member  64  to prevent the second plunger  62  from coming off of the first pipe member  64 . In this case, for example, the first pipe member  64  is press-fitted into the cap  310 , and the cap  310  holds the first pipe member  64 . 
     Second Modification of Second Embodiment 
       FIG.  7    is a partial sectional view illustrating a configuration of a cap according to a second modification of the second embodiment of the present disclosure. In the second embodiment and the first modification described above, the caps  300  and  310  each hold one probe. However, in the second modification, a cap  320  holds a plurality of probes. 
     Two of the accommodating portions  311  are formed in the cap  320 , and each include the first accommodating portion  311   a  having a hole shape for accommodating a part of the distal end  62   a  of the second plunger  62  and the second accommodating portion  311   b  having a hole shape for accommodating a part of the first pipe member  64 . 
     The cap  320  holds the first pipe member  64  in each of the accommodating portions  311  to prevent the second plunger  62  from coming off of the first pipe member  64 . 
     Third Modification of Second Embodiment 
       FIG.  8    is a partial sectional view illustrating a configuration of a cap according to a third modification of the second embodiment of the present disclosure. In the second modification of the second embodiment described above, the cap  320  has been described as holding the ends on the second plunger  62  sides of the first pipe members  64 . However, in the third modification, a cap  330  holds the ends on the first plunger  61  sides of the first pipe members  64 . 
     Two accommodating portions  331  are formed in the cap  330 , and each include a first accommodating portion  331   a  having a hole shape for accommodating a part of the distal end  61   a  of the first plunger  61  and a second accommodating portion  331   b  having a hole shape for accommodating a part of the first pipe member  64 . 
     In the cap  330 , each of the accommodating portions  331  holds the end on the first plunger  61  side of the first pipe member  64  so as to make the second plunger  62  face upward, and prevents the second plunger  62  from coming off of the first pipe member  64 . 
     In the second and third modifications, the examples have been described in which the caps  320  and  330  each hold the two signal probes  6 A. However, the caps can each fold three or more probes. 
     In the above-described second and third modifications, the examples have been described in which the signal probes  6 A are mounted on the caps  320  and  330 . The same caps are each mounted on the power supply probes  7 A and the grounding probes  8 A. The caps  320  and  330  may each hold a plurality of types of the probes. For example, the caps  320  and  330  may each hold the signal probe  6 A and the power supply probe  7 A. 
     Third Embodiment 
       FIG.  9    is a partial sectional view illustrating a detailed structure of a probe holder and the probes constituting a probe unit according to a third embodiment of the present disclosure. The third embodiment has a configuration in which the collars are provided only on the first plunger  61  sides, and the circuit substrate  2  is stacked in advance. 
     The probe unit according to the third embodiment includes the circuit substrate  2  ( FIG.  1   ) including the circuit for, for example, generating the signals to be supplied to the semiconductor IC  1  ( FIG.  1   ), a probe holder  3 B disposed on the circuit substrate  2  and including predetermined hole portions, and the probes (the signal probes  6 A, the power supply probes  7 A, and the grounding probes  8 A) accommodated in the hole portions of the probe holder  3 B. The following describes only the probe holder  3 B having a different configuration from that in the second embodiment described above, and the same configuration will not be described. 
     The probe holder  3 B includes the holder substrate  35  made of a conductive material, such as a metal. In other words, the probe holder  3 B has a configuration obtained by excluding the insulating substrate  36  from the probe holder  3 A described above. The length in the axis line direction of the holder hole  37  can be changed as appropriate according to the length in the axis line direction of the plunger or the coil spring. 
     The circuit substrate  2  is mounted in advance on the holder substrate  35  in the probe holder  3 B. In the third embodiment, the second plungers (the second plungers  62 ,  72 , and  82 ) contact the electrodes (the electrodes  200   a ,  200   b , and  200   c ) of the circuit substrate  2  to be prevented from coming off of the probe holder  3 B. 
     In the probe unit configured as described above, the plungers and the coil springs operate in the same way as in the second embodiment described above during the inspection of the semiconductor IC. Also in the third embodiment, the electrical signal flowing through the probe unit flows from the second plunger into the first plunger via the solid coil portion. For example, in the signal probe  6 A, the electrical signal having flowed into the second plunger  62  flows from the proximal end  62   d  to the solid coil portion  63   a , and then flows from the solid coil portion  63   a  into the first plunger  61 . 
     In the third embodiment described above, the holder holes  37  are formed in the probe holder  3 B, and the signal probes  6 A, the power supply probes  7 A, and the grounding probes  8 A can be arranged in the holder holes  37 . This configuration allows a change in arrangement of the signal probes  6 A, the power supply probes  7 A, and the grounding probes  8 A with respect to the respective holder holes  37 . According to the third embodiment, since the hole portions having the same shape only need to be formed in positions where the probes can be arranged in the probe holder  3 B. Thus, the simple holder configuration allows the change in arrangement of the contact probes. 
     In the third embodiment, the second plunger is prevented from coming off by mounting the circuit substrate  2  on the probe holder  3 B. Such a configuration eliminates the need for the collar on the second plunger side in each of the signal probe  6 A, the power supply probe  7 A, and the grounding probe  8 A, so that the number of components can be reduced. 
     Fourth Embodiment 
       FIG.  10    is a partial sectional view illustrating a detailed structure of the probe holder and probes constituting a probe unit according to a fourth embodiment of the present disclosure. In the fourth embodiment, air in the signal probe corrects the impedance thereof. 
     The probe unit according to the fourth embodiment includes the circuit substrate  2  ( FIG.  1   ) including the circuit for, for example, generating the signals to be supplied to the semiconductor IC  1  ( FIG.  1   ), the probe holder  3  disposed on the circuit substrate  2  and including the predetermined hole portions, and probes (signal probes  6 B, the power supply probes  7 , and the grounding probes  8 ) accommodated in the hole portions of the probe holder  3 . The following describes only the signal probes  6 B having a different configuration from that in the first embodiment described above, and the same configuration will not be described. 
     Each of the signal probes  6 B includes the first plunger  61 , the second plunger  62 , and the coil spring  63  described above, a first pipe member  64 A that accommodates portions of the first plunger  61  and the second plunger  62  and accommodates the coil spring  63 , and the collars  65  provided at both ends of the first pipe member  64 A. The signal probe  6 B differs from the signal probe  6  described above only in the first pipe member. The following describes a configuration of the first pipe member  64 A. 
     The first pipe member  64 A has a cylindrical shape in which the first plunger  61 , the second plunger  62 , and the coil spring  63  are insertable. The first pipe member  64 A includes a metal pipe  644  constituted by an outer circumferential pipe and an inner circumferential pipe forming a double-pipe structure made of a metal, insulating pipes  645  provided at both ends of the metal pipe  644 , and platings  646  provided between the metal pipe  644  and the insulating pipes  645 . The metal pipe  644  is formed of, for example, nickel, copper, or an alloy primarily containing nickel or copper. A pipe-shaped member with plated surfaces may be used as the metal pipe  644 . The insulating pipes  645  are produced using an insulating material, such as ceramic. 
     The first plunger  61 , the second plunger  62 , and the coil spring  63  are inserted in a hollow space formed by the inner circumferential pipe of the first pipe member  64 A. The first pipe member  64 A includes an air layer S formed by sealing a hollow space (hereinafter, called “outer circumferential-side hollow space”) formed between the inner circumferential pipe and the outer circumferential pipe of the metal pipe  644  at both ends of the outer circumferential-side hollow space with the insulating pipes  645  and the platings  646 . In the first pipe member  64 A, the air layer S corrects the characteristic impedance of the signal probe  6 B so as to be equal to, for example, a generally employed value of 50 ohms. 
     The collars  65  are provided at both ends of the first pipe member  64 A, and form stepped portions in conjunction with the inner circumferential surface of the first pipe member  64 A. The flange  61   b  of the first plunger  61  and the flange  62   b  of the second plunger  62  abut on the stepped portions to be prevented from coming off of the first pipe member  64 A. 
     The characteristic impedance of the signal probe  6 B can be adjusted by adjusting a length d 1  in the axis line direction of each of the insulating pipes  645  to adjust the volume and forming position of the air layer S. The length d 1  is preferably smaller than a length d 2  in the axis line direction of the collar  65 . A dielectric for impedance adjustment may be provided between the insulating pipes  645  in the first pipe member  64 A. 
     In the probe unit configured as described above, the plungers and the coil springs operate in the same way as in the first embodiment described above during the inspection of the semiconductor IC. In the fourth embodiment, the electrical signal to flow through the signal probe  6 B is received from the second plunger  62 , flows through the platings  646  or the metal pipe  644  via the collar  65  on the second plunger  62  side, and then flows into the first plunger  61  via the collar  65  on the first plunger  61  side. When the proximal end  62   d  is made in contact with the solid coil portion  63   a , the electrical signal may flow from the proximal end  62   d  to the solid coil portion  63   a , and then flow from the solid coil portion  63   a  into the first plunger  61 . 
     In the fourth embodiment described above, in the same way as in the first embodiment, the hole portions formed of the holder holes  33  and  34  are formed in the probe holder  3 , and the signal probes  6 B, the power supply probes  7 , and the grounding probes  8  can be arranged in the hole portions. This configuration allows a change in arrangement of the signal probes  6 B, the power supply probes  7 , and the grounding probes  8  with respect to the respective hole portions. According to the fourth embodiment, the hole portions having the same shape only need to be formed in positions where the probes can be arranged in the probe holder  3 . Thus, the simple holder configuration allows the change in arrangement of the contact probes. 
     According to the fourth embodiment described above, since the air layer S is formed in the first pipe member  64 A, the air layer S can correct the impedance of the signal probe  6 B. 
     Fifth Embodiment 
       FIG.  11    is a partial sectional view illustrating a detailed structure of the probe holder and the probes constituting a probe unit according to a fifth embodiment of the present disclosure. In the fifth embodiment, a probe holder  3 C holds the adjacent probes so as to contact each other. 
     The probe unit according to the fifth embodiment includes the circuit substrate  2  ( FIG.  1   ) including the circuit for, for example, generating the signals to be supplied to the semiconductor IC  1  ( FIG.  1   ), the probe holder  3 C disposed on the circuit substrate  2  and including the predetermined hole portions, and the probes (the signal probes  6 , the power supply probes  7 , and the grounding probes  8 ) accommodated in the hole portions of the probe holder  3 C. The following describes only the probe holder  3 C having a different configuration from that in the first embodiment described above, and the same configuration will not be described. 
     As described above, the probe holder  3 C is laminated with the first member  31  and the second member  32 . The first member  31  and the second member  32  are provided with the same numbers of the holder holes  33  and  34 , respectively, serving as the hole portions for accommodating the probes. In the fifth embodiment, adjacent large diameter portions of the large diameter portions ( 33   b  and  34   b ) of the respective holder holes contact each other, and communicate with each other at these contact portions. 
     Therefore, each of the pipe members accommodated in the holder portions contacts a part of the outer circumferential surface of the pipe member of adjacent one of the probes. At least the outer circumferential surface of the pipe member of each of the probes is conductive. Therefore, in  FIG.  11   , the power supply probe  7  directly contacts the grounding probe  8 , and the signal probe  6  is electrically connected to the grounding probe  8  through the power supply probe  7 . As a result, the entire outer surface of the pipe member of each of the probes is set to the ground potential. 
     In the fifth embodiment described above, the same effects as those of the first embodiment described above can be obtained, and since each of the probes held in the probe holder  3 C is electrically connected to the grounding probe  8 , the entire outer surface of the pipe member of each of the probes can be more reliably set to the ground potential. 
     First Modification of Fifth Embodiment 
       FIG.  12    is a top view illustrating a configuration of a probe holder constituting a probe unit according to a first modification of the fifth embodiment of the present disclosure.  FIG.  13    is a perspective sectional view illustrating the configuration of the probe holder constituting the probe unit according to the first modification of the fifth embodiment of the present disclosure, and is a perspective sectional view with a cutting plane orthogonal to the axis lines of the holder holes  33  and passing through the large diameter portions  33   b . In the same way as the fifth embodiment described above, the first modification has a configuration in which the large diameter portions of the adjacent holder holes contact each other and parts of the large diameter portions communicate with each other, and the holder holes are arranged in a grid pattern. 
     As illustrated in  FIG.  12   , when the holder holes  33  are arranged in a grid pattern and the adjacent large diameter portions  33   b  contact each other, rhombic columnar portions  39  each surrounded by four of the large diameter portions  33   b  are formed in the first member  31 . Each of the rhombic columnar portions  39  contacts the pipe members of the probes to position the probes and restrain the axis lines of the probes from inclining with respect to the axis lines of the holder holes. 
     Second Modification of Fifth Embodiment 
       FIG.  14    is a sectional view illustrating a configuration of a probe holder constituting a probe unit according to a second modification of the fifth embodiment of the present disclosure, and is a sectional view illustrating an A-A line section of  FIG.  12   . A probe holder  3 D according to the second modification includes rhombic columnar portions  39   a  each obtained by cutting off a part of the rhombic columnar portion  39  described above. The probe holder  3 D is laminated with a first member  31 A and a second member  32 A. 
     When the holder holes  33  are arranged in a grid pattern and the adjacent large diameter portions  33   b  contact each other, the rhombic columnar portions  39   a  each surrounded by four of the large diameter portions  33   b  are formed in the first member  31 A and the second member  32 A, as illustrated in  FIG.  14   . Each of the rhombic columnar portions  39   a  is formed by cutting off a central part in the axis line direction of the rhombic columnar portion  39  described above. The strength of the holder holes can be improved by configuring the rhombic columnar portions  39   a  as being provided on only the upper surface side and the lower surface side of the probe holder  3 D. 
     While the configuration examples of correcting the impedance of the signal probe have been described in the first to fifth embodiments described above, the impedance correction can also be applied to the power supply probe. 
     In the above-described first to fifth embodiments, the inner conductor has been described to be formed by the first and second plungers and the coil spring. However, the inner conductor may be formed by a configuration different from the first and second plungers and the coil spring if the configuration has a stepped shape abutting on the stepped portion formed by the pipe member and the collar and is expandable and contractible along a longitudinal direction. 
     In the above-described first to fifth embodiments, the pipe member has been described to have a cylindrical shape and have a circular ring shape when viewed from a direction orthogonal to the longitudinal direction. However, the pipe member may have a hollow angular shape. 
     In the above-described first to fifth embodiments, when the signal input/output is not performed through the pipe member, that is, when the first and second plungers and the coil spring are used as a conducting path, an insulating material can be used to make the collars. 
     In the above-described first to fifth embodiments, the plating layers (the inner circumferential platings  642  and  742 , the outer circumferential platings  643  and  743 , and the platings  646 ) have been described to be formed on the surfaces of the pipe members (the first pipe members  64  and  64 A, and the second pipe member  74 ). However, a configuration including no plating layer may be employed depending on the mode of fixing the pipe members to the holder holes and the mode of fixing the collars (in the case of the fourth embodiment, the mode of fixing the insulating pipes) to the pipe members. For example, a configuration including no plating layer may be employed when the collars are press-fitted into the pipe members to fix the collars into the pipe members. 
     When the signal probe transmits a signal other than a radio frequency (RF) signal, the configuration of the power supply probe may be applied to the signal probe. 
     As described above, the present disclosure can include various embodiments and the like not described herein, and various design changes and the like can be made within a scope not departing from the technical idea specified by the claims. 
     As described above, the contact probe and the probe unit according to the present disclosure are suitable for simplifying the configuration of the probe holder in which the arrangement of the contact probes is changeable. 
     The present disclosure provides an effect that, in a probe holder in which contact probes are changeable in arrangement, the probe holder can be simplified in configuration.