Coaxial cable and device testing apparatus

Abstract

To provide a coaxial cable capable of being disposed with high density.SOLUTION: A coaxial cable 40 comprises a tubular outer conductor 45, an insulator 44 covered by the outer conductor 45, and a plurality of inner conductors 41 disposed within the insulator 44.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a coaxial cable and a device testing apparatus equipped with the coaxial cable. [Background technology]

[0002] A known semiconductor device testing device for testing the electrical characteristics of various semiconductor devices (DUTs) such as semiconductor integrated circuit elements includes a DSA with a socket, a test head with a pin electronics card, and a motherboard with a coaxial cable that electrically connects the DSA and the test head (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-078048 Summary of the Invention [Problem to be solved by the invention]

[0004] In semiconductor device test equipment, as the number of simultaneous measurements (the number of DUTs that can be tested simultaneously) increases, the number of coaxial cables equipped on the motherboard also increases.However, due to the limited space inside the motherboard case, it can be difficult to increase the number of coaxial cables.

[0005] The problem to be solved by the present invention is to provide a coaxial cable that can be arranged at high density, and a device testing apparatus equipped with the coaxial cable. [Means for solving the problem]

[0006] [1] A first aspect of the present invention is a coaxial cable comprising a tubular outer conductor, an insulating portion covered by the outer conductor, and a plurality of inner conductors arranged within the insulating portion.

[0007] [2] A second aspect of the present invention may be the coaxial cable of the first aspect, wherein the plurality of inner conductors are arranged in the insulating portion so as to be spaced apart from each other.

[0008] [3] A third aspect of the present invention may be the coaxial cable of the first or second aspect, wherein the insulating portion is interposed between the plurality of inner conductors.

[0009] [4] A fourth aspect of the present invention may be the coaxial cable of any one of the first to third aspects, wherein the inner conductor has a cross-sectional shape that extends in an arc shape.

[0010] [5] A fifth aspect of the present invention may be a coaxial cable according to any one of the first to fourth aspects, wherein the inner conductor has a cross-sectional shape that extends substantially parallel to the inner peripheral surface of the outer conductor.

[0011] [6] A sixth aspect of the present invention may be a coaxial cable according to any one of the first to fifth aspects, wherein the thickness of the inner conductor along the radial direction of the coaxial cable is smaller than the width of the inner conductor along the circumferential direction of the coaxial cable.

[0012] [7] A seventh aspect of the present invention may be the coaxial cable of the sixth aspect, wherein the thickness of the inner conductor is 1 / 5 or less of the width of the inner conductor.

[0013] [8] Aspect 8 of the present invention may be a coaxial cable according to any one of aspects 1 to 7, wherein the thickness of the inner conductor along the radial direction of the coaxial cable is substantially constant in the circumferential direction of the coaxial cable.

[0014] [9] A ninth aspect of the present invention may be a coaxial cable according to any one of the first to eighth aspects, wherein the plurality of inner conductors are arranged at intervals in the circumferential direction of the coaxial cable and are arranged concentrically with the outer conductor.

[0015]

[10] A tenth aspect of the present invention may be the coaxial cable of the ninth aspect, wherein the plurality of inner conductors are arranged at substantially equal intervals in the circumferential direction of the coaxial cable.

[0016]

[11] An eleventh aspect of the present invention may be a coaxial cable according to any one of the first to tenth aspects, wherein the distance between the plurality of inner conductors is greater than the distance between the inner conductor and the outer conductor.

[0017]

[12] A twelfth aspect of the present invention is a coaxial cable according to any one of the first to eleventh aspects, wherein the inner conductor is a metal layer having an arc-shaped cross-sectional shape, or a coaxial cable having a plurality of metal wires arranged in an arc shape.

[0018]

[13] A thirteenth aspect of the present invention may be the coaxial cable of any one of the first to twelfth aspects, wherein the insulating portion is a first insulating portion including a resin material.

[0019]

[14] A fourteenth aspect of the present invention is a coaxial cable according to the thirteenth aspect, wherein the first insulating portion is a columnar or tubular resin body that holds the plurality of inner conductors, and the outer conductor is a coaxial cable that covers the resin body.

[0020]

[15] A fifteenth aspect of the present invention may be the coaxial cable of the fourteenth aspect, wherein the plurality of inner conductors are embedded in the resin body.

[0021]

[16] A sixteenth aspect of the present invention may be a coaxial cable according to the thirteenth aspect, wherein the first insulating portion comprises a plurality of resin strands assembled together, a strand assembly that holds the plurality of inner conductors, and the outer conductor covers the strand assembly.

[0022]

[17] A seventeenth aspect of the present invention may be the coaxial cable of the sixteenth aspect, wherein the inner conductor is disposed between the resin wires.

[0023]

[18] An eighteenth aspect of the present invention may be the coaxial cable of any one of the thirteenth to seventeenth aspects, wherein the insulating portion includes a second insulating portion made of gas or vacuum.

[0024]

[19] A nineteenth aspect of the present invention may be the coaxial cable of the eighteenth aspect, wherein the second insulating portion is interposed between the plurality of inner conductors.

[0025]

[20] Aspect 20 of the present invention may be a coaxial cable according to aspect 18 or 19, wherein the first insulating portion has a hole formed inside the first insulating portion, and the second insulating portion is a gas or vacuum within the hole.

[0026]

[21] A twenty-first aspect of the present invention may be the coaxial cable of any one of the eighteenth to twentieth aspects, wherein the second insulating portion is interposed between the inner conductor and the outer conductor.

[0027]

[22] Aspect 22 of the present invention may be a coaxial cable according to any one of aspects 18 to 21, wherein the first insulating portion has a groove formed on the outer surface of the first insulating portion, and the second insulating portion is a gas or vacuum in the groove.

[0028]

[23] A twenty-third aspect of the present invention may be the coaxial cable of any one of the eighteenth to twenty-second aspects, wherein the inner conductors are exposed to the second insulating portion.

[0029]

[24] Aspect 24 of the present invention is a coaxial cable according to any one of aspects 1 to 23, wherein the coaxial cable comprises a plurality of wall-like conductors interposed between the plurality of inner conductors in the circumferential direction of the coaxial cable, and the wall-like conductors may be electrically connected to the outer conductor.

[0030]

[25] A twenty-fifth aspect of the present invention may be a coaxial cable according to the twenty-fourth aspect, wherein the wall-shaped conductor is connected to the outer conductor and protrudes from the outer conductor toward the center of the coaxial cable.

[0031]

[26] A twenty-sixth aspect of the present invention may be a coaxial cable according to the twenty-fourth or twenty-fifth aspect, wherein the plurality of wall-shaped conductors are connected to each other at the center of the coaxial cable.

[0032]

[27] A twenty-seventh aspect of the present invention is a coaxial cable according to the twenty-sixth aspect, wherein the coaxial cable has a central conductor disposed at the center of the coaxial cable, and the plurality of wall-shaped conductors are connected to each other at the center of the coaxial cable via the central conductor.

[0033]

[28] A twenty-eighth aspect of the present invention may be a coaxial cable according to the twenty-sixth aspect, wherein the plurality of wall-like conductors are directly connected to each other at the center of the coaxial cable.

[0034]

[29] Aspect 29 of the present invention is a coaxial cable according to any one of aspects 24 to 28, wherein the wall-shaped conductor is a metal layer extending radially of the coaxial cable, or a coaxial cable having a plurality of metal wires arranged radially.

[0035]

[30] A thirtieth aspect of the present invention may be the coaxial cable according to any one of the first to twenty-ninth aspects, wherein the insulating portion is disposed within the outer conductor.

[0036]

[31] A thirty-first aspect of the present invention may be a coaxial cable according to any one of the first to thirty aspects, wherein the outer conductor collectively surrounds the plurality of inner conductors via the insulating portion.

[0037]

[32] A thirty-second aspect of the present invention is the coaxial cable of any one of the first to thirty-first aspects, wherein the coaxial cable is a coaxial cable having an outer sheath that covers the outer conductor.

[0038]

[33] A thirty-third aspect of the present invention relates to the coaxial cable of any one of the first to thirty-second aspects, and may be a coaxial cable used in a device testing apparatus that tests a DUT.

[0039]

[34] A thirty-fourth aspect of the present invention is a device testing apparatus for testing a DUT, the device testing apparatus comprising the coaxial cable according to any one of the first to thirty-third aspects.

[0040]

[35] A thirty-fifth aspect of the present invention may be the device testing apparatus of the thirty-fourth aspect, wherein the plurality of internal conductors transmit electrical signals different from one another. [Effects of the Invention]

[0041] According to the present invention, the coaxial cable includes a plurality of inner conductors disposed within the insulating portion, which allows the coaxial cable to be arranged at a high density. [Brief explanation of the drawings]

[0042] [Figure 1] FIG. 1 is a schematic cross-sectional view showing the overall configuration of a device testing apparatus according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an exploded cross-sectional view showing the DSA and the motherboard according to the first embodiment of the present invention, and corresponds to part II in FIG. [Figure 3] FIG. 3 is a cross-sectional view showing a coaxial cable according to the first embodiment of the present invention. [Figure 4]FIG. 4 is a cross-sectional view showing a modified example of the coaxial cable according to the first embodiment of the present invention. [Figure 5] FIG. 5 is a cross-sectional view showing a coaxial cable according to the second embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view showing a coaxial cable according to a third embodiment of the present invention. [Figure 7] FIG. 7 is a cross-sectional view showing a first modified example of the coaxial cable according to the third embodiment of the present invention. [Figure 8] FIG. 8 is a cross-sectional view showing a second modified example of the coaxial cable according to the third embodiment of the present invention. [Figure 9] FIG. 9 is a cross-sectional view showing a coaxial cable according to the fourth embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional view showing a coaxial cable according to the fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0043] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0044] <<First Embodiment>> Fig. 1 is a schematic cross-sectional view showing the overall configuration of a device testing apparatus 1 according to a first embodiment of the present invention. Fig. 2 is an exploded cross-sectional view showing a DSA 20 and a motherboard 30 according to the first embodiment of the present invention, and corresponds to part II in Fig. 1.

[0045] The device testing apparatus 1 in this embodiment is an apparatus for testing the electrical characteristics of a semiconductor device (hereinafter also simply referred to as "DUT") 100 such as a semiconductor integrated circuit element. Specific examples of the DUT 100 to be tested include, but are not limited to, a memory device, a logic device, or an SoC (System on Chip). As shown in FIG. 1 , the device testing apparatus 1 includes a tester 10 that tests the DUT 100 and a handler 90 that handles the DUT 100 and presses it against a socket 21. The tester 10 includes a DSA 20, a motherboard 30, a test head 70, and a mainframe 80. Note that the configuration of the tester 10 is not particularly limited to the following, as long as it includes a coaxial cable 40.

[0046] As shown in FIGS. 1 and 2, the DSA (Device Specific Adapter) 20 includes a socket 21, a socket board 23, and a plurality of connectors 24. The DSA 20 is electrically connected to the test head 70 via a motherboard 30. The DSA 20 is detachable from the motherboard 30. The DSA 20 is designed according to the type of DUT 100, and is replaced with a new one that corresponds to the type when the type of DUT 100 is changed. Note that the number of DSAs 20 that can be mounted on the motherboard 30 is not particularly limited, and a plurality of DSAs 20 may be mounted on the motherboard 30.

[0047] During testing of the DUT 100, the DUT 100 is pressed against the socket 21 by the handler 90, thereby electrically connecting the DUT 100 and the socket 21. The socket 21 includes a plurality of contactors 22 that respectively come into contact with the terminals 110 of the DUT 100. Specific examples of such contactors 22 include, but are not limited to, pogo pins, vertical probe needles, cantilever probe needles, anisotropic conductive rubber sheets, bumps on a membrane, or contactors fabricated using MEMS technology.

[0048] The socket board 23 is a wiring board on which the above-mentioned sockets 21 are mounted on the upper surface. There is no particular limitation on the number of sockets 21 mounted on the socket board 23, and a plurality of sockets 21 may be mounted on the socket board 23. Although not shown, a socket guide for positioning the DUT 100 with respect to the socket 21 may be attached to the upper surface of the socket board 23. A coaxial connector 24 is mounted on the lower surface of the socket board 23. The sockets 21 and the coaxial connector 24 are electrically connected via conductive paths (not shown), such as wiring patterns or through holes, formed on the socket board 23.

[0049] The motherboard 30 is a repeater that electrically connects the DSA 20 and the test head 70. The motherboard 30 includes a housing 31, a plurality of coaxial connectors 32, and a plurality of coaxial cables 40. While not particularly limited, for example, the motherboard 30 may include 100 or more coaxial connectors 32, with 50 to 100 coaxial cables 40 connected to each coaxial connector 32. As a result, the motherboard 30 includes thousands to tens of thousands of coaxial cables 40. The coaxial connector 32 is connected to one end of the coaxial cable 40 (the upper end in FIG. 2). The coaxial connector 32 is fittable with the coaxial connector 24 of the DSA 20. The coaxial connector 32 is held in the upper part of the housing 31 so as to correspond to the coaxial connector 24 of the DSA 20. When the DSA 20 is mounted on the motherboard 30, the coaxial connector 24 of the DSA 20 mates with the coaxial connector 32 of the motherboard 30. The configuration of the coaxial cable 40 will be described in detail later.

[0050] 1, the test head 70 houses therein a test module (pin electronics card) 71 for testing the DUT 100. The test module 71 is a wiring board on which electronic components such as test devices used in testing the DUT 100 are mounted. The test module 71 is electrically connected to the coaxial cable 40 via a coaxial connector (not shown) or the like connected to the other end of the coaxial cable 40 of the motherboard 30. The test module 71 tests the DUT 100 by sending and receiving test signals to and from the DUT 100 via the DSA 20 and the motherboard 30. The test head 70 is connected to the mainframe 80 via a cable 72.

[0051] The mainframe (tester main body) 80 is, for example, a computer that executes a program, and communicates with each test module 71 in the test head 70 in accordance with the program to control each test module 71. Each test module 71 generates a test signal in accordance with an instruction from the mainframe 80 and outputs the test signal to the DUT 100.

[0052] Although not specifically shown, the handler 90 includes, for example, a transport device that transports a test tray loaded with DUTs 100 above the DSA 20, a pressing device that presses the DUTs 100 against the sockets 21 of the DSA 20, and a sorting device that removes the DUTs 100 from the test tray and sorts them according to the test results.

[0053] The handler 90 also includes a chamber 91 as a temperature control device for applying high or low temperature thermal stress to the DUT 100. The chamber 91 is configured as a thermostatic chamber capable of maintaining the temperature inside the chamber at a desired temperature. Therefore, the device testing apparatus 1 is capable of testing the DUT 100 while applying thermal stress to the DUT 100, and is capable of performing so-called high temperature testing and low temperature testing.

[0054] The above-mentioned DSA 20 enters the chamber 91 through an opening 92 formed in the handler 90, and the socket 21 of the DSA 20 is disposed in the chamber 91. The DUT 100 is pressed against the socket 21 of the DSA 20 by a pressing device of the handler 90, thereby electrically connecting the DUT 100 and the socket 21.

[0055] The handler 90 may be of a type that does not use a test tray, but includes a contact arm that sucks and holds the DUT 100 and moves it, and that presses the DUT 100 with the contact arm. In this case, the handler 90 may include, as a temperature adjustment device, a heater or a heat sink provided at the tip of the contact arm, instead of the chamber 91. Alternatively, the handler 90 may include, as a temperature adjustment device, a heater or a heat sink provided at the tip of the contact arm, in addition to the chamber 91.

[0056] Next, the configuration of the coaxial cable 40 provided on the above-mentioned motherboard 30 will be described in detail with reference to Fig. 3. Fig. 3 is a cross-sectional view showing the coaxial cable 40 according to the first embodiment of the present invention.

[0057] As shown in Fig. 3, a coaxial cable 40 in this embodiment includes a plurality of inner conductors 41, a plurality of wall-like conductors 42, a central conductor 43, an insulating portion 44 that holds these conductors 41 to 43, an outer conductor 45 that covers the insulating portion 44, and an outer jacket 46 that covers the outer conductor 45. This coaxial cable 40 is a cable that extends in the normal direction to the plane of the paper in Fig. 3, and Fig. 3 shows a cross section orthogonal to the longitudinal direction (axial direction) of the coaxial cable 40.

[0058] Each internal conductor 41 functions as a transmission path for transmitting an electrical signal between the test head 70 and the DUT 100. On the other hand, the external conductor 45 is connected to the ground and functions as an electromagnetic shielding layer for shielding noise. Also, the wall-like conductor 42 and the central conductor 43 have a function of suppressing crosstalk between the plurality of internal conductors 41. In the device test apparatus 1 described above, the electrical signal flowing through the internal conductor 41 is a high-frequency electrical signal, an electrical signal of 10 MHz or more, an electrical signal of 100 MHz or more, an electrical signal of 1 GHz or more, an electrical signal of 2.5 GHz or more, an electrical signal of 5 GHz or more, or an electrical signal of 10 GHz or more. Also, different electrical signals are assigned to the plurality of internal conductors 41, and a plurality (three in this embodiment) of electrical signals can be transmitted through one coaxial cable 40.

[0059] The coaxial cable 40 of this embodiment includes three internal conductors 41. Each internal conductor 41 is a conductor layer that extends over the entire axial direction of the coaxial cable 40. Each internal conductor 41 has an arc-shaped cross-sectional shape. Each internal conductor 41 extends substantially parallel to the inner peripheral surface 451 of the external conductor 45, and a microstrip line structure is formed between the internal conductor 41 and the external conductor 45. Note that the number of internal conductors 41 included in the coaxial cable 40 is not particularly limited as long as it is plural.

[0060] This internal conductor 具有 a tape-like cross-sectional shape. That is, the thickness t1 of this internal conductor 41 along the radial direction of the coaxial cable 40 is smaller than the width w1 of this internal conductor 41 along the circumferential direction of the coaxial cable 40 (t1 < w1). Although not particularly limited, it is preferable that the thickness t1 of the internal conductor 41 is 1 / 5 or less of the width w1 of the internal conductor 41 (t1 < w1 × 1 / 5), and more preferably 1 / 10 or less of the width w1 of the internal conductor 41 (t1 < w1 × 1 / 10). Also, the thickness t1 of this internal conductor 41 is substantially constant in the circumferential direction of the coaxial cable 40.

[0061] The thickness t1 of the inner conductor 41 is, for example, preferably 0.1 μm or more and 20 μm or less (0.1 μm≦t1≦20 μm), and more preferably 0.1 μm or more and 10 μm or less (0.1 μm≦t1≦10 μm). The thickness t1 of the inner conductor 41 can be set according to the frequency of the electrical signal flowing through the coaxial cable 40. Specifically, when the frequency of the electrical signal is high, the thickness t1 of the inner conductor 41 is set to be thin, and when the frequency of the electrical signal is low, the thickness t1 of the inner conductor 41 is set to be thick.

[0062] The internal conductor 41 is made of a conductive material. Although not particularly limited, the internal conductor 41 is specifically made of a metal foil. Specific examples of the metal foil constituting the internal conductor 41 include copper foil and silver-plated copper foil. The internal conductor 41 may be a thin film formed by a plating method such as electrolytic plating or electroless plating. Alternatively, the internal conductor 41 may be a thin film formed by a physical vapor deposition (PVD) method such as vacuum deposition or sputtering, or a chemical vapor deposition (CVD) method. Alternatively, the internal conductor 41 may be a thin film formed by applying a paint containing metal particles and an adhesive and curing it by heating.

[0063] The coaxial cable 40 of this embodiment includes three wall-shaped conductors 42. Each wall-shaped conductor 42 is a conductor layer extending across the entire axial direction of the coaxial cable 40. Each wall-shaped conductor 42 has a tape-like cross-sectional shape that extends linearly in the radial direction of the coaxial cable 40. One end 421 of each wall-shaped conductor 42 is connected to an outer conductor 45 and protrudes from the outer conductor 45 toward the center of the coaxial cable 40. Therefore, each wall-shaped conductor 42 is connected to ground via the outer conductor 45. The number of wall-shaped conductors 42 included in the coaxial cable 40 is not particularly limited to the number described above and can be set according to the number of inner conductors 41 included in the coaxial cable 40.

[0064] Like the internal conductor 41, the wall-shaped conductor 42 is made of a conductive material. While not particularly limited, the wall-shaped conductor 42 is specifically made of a metal foil. Specific examples of the metal foil constituting the wall-shaped conductor 42 include copper foil and silver-plated copper foil. The wall-shaped conductor 42 may be a thin film formed by a plating method such as electrolytic plating or electroless plating. Alternatively, the wall-shaped conductor 42 may be a thin film formed by a physical vapor deposition (PVD) method such as vacuum deposition or sputtering, or a chemical vapor deposition (CVD) method. Alternatively, the wall-shaped conductor 42 may be a thin film formed by applying a paint containing metal particles and an adhesive and curing it by heating.

[0065] The central conductor 43 is a single wire extending over the entire axial length of the coaxial cable 40. The central conductor 43 has a circular cross section and is a solid wire made of a conductive material. A stranded wire may also be used as the central conductor 43.

[0066] The central conductor 43 is disposed at the center of the coaxial cable 40. Each wall-shaped conductor 42 is connected to the central conductor 43 at the other end 422 of the wall-shaped conductor 42, and all of the wall-shaped conductors 42 are electrically connected to one another via the central conductor 43. Therefore, the central conductor 43 is connected to ground via the wall-shaped conductor 42 and the outer conductor 45. Specific examples of the metal material constituting the central conductor 43 are not particularly limited as long as they have good electrical conductivity, and include, for example, silver, copper, or an alloy thereof.

[0067] As shown in Fig. 4, the coaxial cable 40 does not have to include the central conductor 43. In this case, all the wall-shaped conductors 42 are electrically connected to each other by directly connecting the wall-shaped conductors 42 to each other at the other ends 422 of the wall-shaped conductors 42. Fig. 4 is a cross-sectional view showing a modified example of the coaxial cable 40 according to the first embodiment of the present invention.

[0068] 3, the insulating portion 44 includes a cylindrical resin body 441 extending over the entire axial direction of the coaxial cable 40. The above-described inner conductor 41, wall-like conductors 42, and center conductor 43 are embedded in this resin body 441. This resin body 441 is made of a resin material having electrical insulating properties. Although not particularly limited, specific examples of the resin material constituting this resin body 441 include imide-based resins such as polyimide, fluororesins such as polytetrafluoroethylene (PTFE), polyethylene (PE), and cross-linked foamed polyethylene.

[0069] The multiple inner conductors 41 are arranged at substantially equal intervals in the circumferential direction of the coaxial cable 40. The multiple inner conductors 41 are also arranged concentrically with the outer conductor 45. A resin body 441 is interposed between the mutually adjacent inner conductors 41.

[0070] The multiple wall-shaped conductors 42 are arranged in the resin body 441 such that each wall-shaped conductor 42 is interposed between adjacent internal conductors 41 in the circumferential direction of the coaxial cable 40. Each wall-shaped conductor 42 is preferably arranged in the center between adjacent internal conductors 41. The wall-shaped conductors 42 can suppress crosstalk between the multiple internal conductors 41. The resin body 441 is interposed between the wall-shaped conductors 42 and the internal conductors 41.

[0071] A central conductor 43 is disposed at the center of the resin body 441, and the other ends 422 of the multiple wall-shaped conductors 42 are connected to this central conductor 43. Connecting all the wall-shaped conductors 42 with the central conductor 43 can further suppress crosstalk between the multiple internal conductors 41. The resin body 441 is interposed between the central conductor 43 and the internal conductors 41.

[0072] When the internal conductor 41 and the wall-like conductor 42 are metal foils, for example, the conductors 41 to 43 are arranged as described above and then a resin material is extruded to form the resin body 441 in which the conductors 41 to 43 are embedded. When the internal conductor 41 and the wall-like conductor 42 are thin films formed by plating or the like, for example, the resin body 441 in which the conductors 41 to 43 are embedded can be formed by repeatedly extruding a core material that constitutes a part of the insulating portion 44 and forming a thin film on the core material.

[0073] The outer conductor 45 is a tubular conductor layer that covers the entire periphery of the outer peripheral surface 442 of the resin body 441 and extends over the entire axial direction of the coaxial cable 40. The resin body 441 is disposed within the outer conductor 45, and the outer conductor 45 collectively surrounds all of the inner conductors 41 via the resin body 441. The resin body 441 is interposed between the outer conductor 45 and each of the inner conductors 41. As described above, each wall-shaped conductor 42 is connected to the outer conductor 45 at one end 421 of the wall conductor 42 and to the center conductor 43 at the other end 422 of the wall conductor 42. As a result, the internal space of the outer conductor 45 is divided into three chambers 453 by the wall conductors 42 and the center conductor 43, and each of the chambers 453 individually houses an inner conductor 41.

[0074] The outer conductor 45 is a thin film formed on the outer peripheral surface 442 of the resin body 441. The thin film is made of a metal material. The thin film is, for example, a plated layer formed by a plating method such as electrolytic plating or electroless plating. Specific examples of the metal material constituting the outer conductor 45 are not particularly limited as long as it is a metal material having good conductivity, and include, for example, silver, copper, or an alloy thereof.

[0075] The method for forming the thin film of the outer conductor 45 is not limited to the plating method described above, and the outer conductor 45 may be formed by, for example, physical vapor deposition (PVD) or chemical vapor deposition (CVD). Alternatively, the thin film of the outer conductor 45 may be a coating layer. Although not particularly limited, this coating layer can be formed, for example, by applying paint containing metal particles and an adhesive to the outer peripheral surface 442 of the insulating portion 44 and curing it by heating.

[0076] Alternatively, instead of the thin film described above, the outer conductor 45 may be made of a metal foil. In this case, the outer conductor 45 is formed by wrapping the metal foil around the outer peripheral surface 442 of the resin body 441. Specific examples of the metal foil that forms the outer conductor 45 include, but are not limited to, copper foil and silver-plated copper foil. Alternatively, instead of the thin film described above, a metal pipe such as a copper tube may be used as the outer conductor 45. Alternatively, instead of the thin film described above, a braided shield having a plurality of woven metal wires may be used as the outer conductor 45.

[0077] The outer jacket 46 is a tubular member that covers the entire circumference of the outer peripheral surface 452 of the outer conductor 45, and covers the outer conductor 45 over the entire axial direction of the coaxial cable 40. The outer jacket 46 is made of an electrically insulating resin material. Although not particularly limited, specific examples of the resin material that forms the outer jacket 46 include polyvinyl chloride (PVC), polyethylene (PE), polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), and fluorinated ethylene propylene (FEP).

[0078] However, if the outer conductor of a coaxial cable is made too thin, the outer conductor becomes more susceptible to breakage. Furthermore, if the outer jacket of a coaxial cable is made too thin, sufficient insulation may not be ensured. These limitations on the thickness of the outer conductor and the jacket impose a limit on how thin a coaxial cable can be, and therefore, there is a limit to how densely the coaxial cables can be arranged on a motherboard by making the coaxial cable thinner.

[0079] In contrast, in this embodiment, the coaxial cable 40 has multiple inner conductors 41, and the multiple inner conductors 41 share a single outer conductor 45. Therefore, the coaxial cable 40 has transmission characteristics equivalent to those of a conventional coaxial cable having a single inner conductor, and can have a smaller cross-sectional area than a conventional coaxial cable having the same number of inner conductors 41 (three in this embodiment). Therefore, in this embodiment, it is possible to arrange the coaxial cables 40 at high density within the motherboard 30.

[0080] Furthermore, because the inner conductor of the conventional coaxial cable is made of a metal wire with a circular cross-section, the coaxial cable has a relatively high rigidity. Furthermore, multiple coaxial cables may be connected to one connector. In this case, the greater the number of coaxial cables connected to one connector, the stronger the reaction force from the coaxial cables. Therefore, when assembling a motherboard, forcibly pushing the coaxial cable into place can result in the coaxial cable itself breaking, or cracks occurring in the soldered connection between the coaxial cable's inner conductor and the terminal of the coaxial connector, resulting in poor connection.

[0081] In contrast, in this embodiment, each of the inner conductors 41 has a cross-sectional shape that extends in an arc shape, which reduces the rigidity of the coaxial cable 40 and reduces the reaction force of the coaxial cable 40. In this embodiment, the frequency of the electrical signals used in the device testing equipment is high, and the higher the frequency is, the more the electrical signal concentrates on the surface of the conductor due to the skin effect. In light of this, the cross-sectional shape of each of the inner conductors 41 is made thinner, thereby reducing the reaction force of the coaxial cable 40. This makes it possible to prevent breakage during assembly of the motherboard 30.

[0082] In addition, device testing equipment may be equipped with a sliding function that allows one connector (the connector connected to the coaxial cable) to slide laterally (perpendicular to the mating direction) relative to the other connector (the connector mounted on the wiring board) to absorb mechanical errors that occur when mating connectors.

[0083] In contrast, in this embodiment, the reaction force of the coaxial cable 40 can be reduced as described above, so that even if the connector 32 to which the coaxial cable 40 is connected has the above-mentioned sliding function, sufficient contact pressure can be ensured between the terminals of the connectors 32, 24, and the occurrence of poor connection of the connectors 32, 24 can be suppressed.

[0084] Furthermore, in device testing equipment, connectors are plugged in and out every time the DUT type is changed.When a large number of coaxial cables are connected to one connector, the connector may be mated in an inclined position due to the strong reaction force from the coaxial cables, which may make it difficult to ensure sufficient connection reliability even after thousands of plugging and unplugging of the connector.

[0085] In contrast, in this embodiment, the reaction force of the coaxial cable 40 can be reduced as described above, thereby preventing the connector 32 from mating in an inclined state relative to the mating connector 24, and ensuring sufficient connection reliability over thousands of insertions and removals of the connectors 32, 24.

[0086] Furthermore, when performing low-temperature testing in a device testing device (e.g., testing a DUT at -50°C to -40°C), if the inner conductor of the coaxial cable is a metal wire with a circular cross-sectional shape, heat may be transferred into the motherboard through this inner conductor, causing the inside of the motherboard to cool and resulting in condensation.

[0087] In contrast, in this embodiment, each internal conductor 41 has a thin cross-sectional shape extending in an arc shape, which makes it possible to suppress heat transfer from the chamber 91 of the handler 90 to the inside of the motherboard 30, and to suppress condensation from occurring inside the motherboard 30.

[0088] Furthermore, in this embodiment, each of the internal conductors 41 has a thin cross-sectional shape extending in an arc shape, which makes it possible to reduce the weight of several thousand to several tens of thousands of coaxial cables 40. This allows the strength of the housing 31 that holds the coaxial cables 40 to be reduced, and as a result, the cost of the motherboard 30 can be reduced.

[0089] <<Second embodiment>> 5 is a cross-sectional view showing a coaxial cable 40B according to a second embodiment of the present invention. In this embodiment, the configurations of an inner conductor 41B, a wall-like conductor 42B, a center conductor 43B, and an insulating portion 44B differ from those of the first embodiment, but the other configurations are the same as those of the first embodiment. Below, only the differences between the coaxial cable 40B according to the second embodiment and the first embodiment will be described, and parts having the same configuration as those of the first embodiment will be assigned the same reference numerals and their description will be omitted.

[0090] As shown in Fig. 5, each inner conductor 41B in this embodiment includes a plurality of metal wires 411 instead of a single conductor layer. Each metal wire 411 extends over the entire axial length of the coaxial cable 40B. The plurality of metal wires 411 are arranged in an arc shape, and as a result, each inner conductor 41B has a cross-sectional shape that extends in an arc shape. The plurality of metal wires 411 are arranged so as to be substantially parallel to the inner circumferential surface 451 of the outer conductor 45, and a microstrip line structure is formed between the inner conductor 41B and the outer conductor 45. The number of metal wires 411 included in each inner conductor 41B is not particularly limited as long as it is plural.

[0091] The thickness t2 of the inner conductor 41B along the radial direction of the coaxial cable 40B is smaller than the width w2 along the circumferential direction of the coaxial cable 40B of the inner conductor 41B (t2 < w2). Although not particularly limited, it is preferable that the thickness t2 of the inner conductor 41B is 1 / 5 or less of the width w2 of the inner conductor 41B (t2 < w2 × 1 / 5), and it is more preferable that the thickness t2 of the inner conductor 41B is 1 / 10 or less of the width w2 of the inner conductor 41B (t2 < w2 × 1 / 10). In this embodiment, as will be described later, since the cross-sectional shape of the metal wire 411 is circular, the thickness t2 of the inner conductor 41B is equal to the diameter of the metal wire 411.

[0092] Each wall-shaped conductor 42B in this embodiment also includes a plurality of metal wires 423 instead of a single conductor layer. Each metal wire 423 extends over the entire axial direction of the coaxial cable 40B. These plurality of metal wires 423 are linearly arranged in the radial direction of the coaxial cable 40B. As a result, each wall-shaped conductor 42B has a linearly extending cross-sectional shape. The metal wire 423a located at one end of each wall-shaped conductor 42B is connected to the outer conductor 45, and the wall-shaped conductor 42B protrudes from the outer conductor 45 toward the center of the coaxial cable 40B. Therefore, each wall-shaped conductor 42B is connected to the ground via the outer conductor 45. The number of metal wires 423 included in each wall-shaped conductor 42B is not particularly limited as long as it is plural.

[0093] The center conductor 43B in this embodiment also includes a plurality of metal wires 431. Each metal wire 431 extends over the entire axial direction of the coaxial cable 40B. These plurality of metal wires 431 are arranged in a circular shape around the center of the coaxial cable 40B. The metal wire 423b located at the other end of each wall-shaped conductor 42B is connected to this center conductor 43B, and all the above-mentioned wall-shaped conductors 42B are electrically connected to each other via the center conductor 43B. Therefore, this center conductor 43B is connected to the ground via the wall-shaped conductor 42B and the outer conductor 45. The number of metal wires 431 included in the center conductor 43B is not particularly limited.

[0094] The metal wires 411, 423, and 431 are all solid wires having a circular cross section and made of a metal material with good electrical conductivity. While not particularly limited, specific examples of the metal material constituting the metal wires 411, 423, and 431 include copper, silver, and alloys thereof. While the metal wires 411, 423, and 431 have the same diameter in this embodiment, the present invention is not particularly limited thereto, and the diameters of the metal wires 411, 423, and 431 may be different.

[0095] The insulating part 44B in this embodiment includes a wire assembly 446 that holds the inner conductor 41B, the wall-shaped conductors 42B, and the center conductor 43B. The wire assembly 446 includes a plurality of resin wires 447 that are assembled together. The outer conductor 45 covers the wire assembly 446.

[0096] Each of the resin wires 447 has a circular cross-sectional shape, is a solid wire made of an electrically insulating resin material, and extends throughout the axial direction of the coaxial cable 40B. Specific examples of the resin material constituting the resin wires 447 include, but are not limited to, imide resins such as polyimide, fluororesins such as polytetrafluoroethylene (PTFE) and perfluoroalkoxyalkane (PFA), polyetheretherketone (PEEK), polyethylene (PE), and cross-linked foamed polyethylene. The multiple resin wires 447 are disposed within the outer conductor 45 so as to fill the internal space of the outer conductor 45.

[0097] As in the first embodiment described above, in this embodiment, the multiple inner conductors 41B are arranged at substantially equal intervals in the circumferential direction of the coaxial cable 40B and are arranged concentrically with the outer conductor 45. The multiple wall-shaped conductors 42B are each interposed between adjacent internal conductors 41B. These wall-shaped conductors 42B can suppress crosstalk between the multiple internal conductors 41B. A central conductor 43B to which the multiple wall-shaped conductors 42B are connected is then arranged in the center of the coaxial cable 40B. By connecting all the wall-shaped conductors 42B with the central conductor 43B, crosstalk between the multiple internal conductors 41B can be further suppressed.

[0098] In this embodiment, the metal wires 411, 423, and 431 are arranged between the multiple resin wires 447 so that the conductors 41B to 43B are arranged as described above. With the wires 411, 423, and 431 and the resin wire 447 arranged in this manner, the wires 411, 423, 431, and 447 are twisted together to form the inner conductor 41B, the wall-shaped conductor 42B, the central conductor 43B, and the insulating portion 44B of this embodiment.

[0099] In this embodiment, as in the first embodiment described above, the coaxial cable 40B includes a plurality of inner conductors 41B, so that the coaxial cables 40B can be arranged within the motherboard 30 at high density.

[0100] Furthermore, in this embodiment, similar to the first embodiment described above, each internal conductor 41B has a thin cross-sectional shape extending in an arc shape, which reduces the reaction force of the coaxial cable 40B and makes it lighter, while also preventing condensation from forming inside the motherboard 30.

[0101] <<Third Embodiment>> 6 is a cross-sectional view showing a coaxial cable 40C according to a third embodiment of the present invention. This embodiment differs from the first embodiment in that the coaxial cable 40C does not include a central conductor 43, but other configurations are similar to those of the first embodiment. Below, only the differences between the coaxial cable 40C according to the third embodiment and the first embodiment will be described, and portions having the same configuration as those of the first embodiment will be assigned the same reference numerals and their description will be omitted.

[0102] As shown in Fig. 6, a coaxial cable 40C of this embodiment does not include a center conductor 43. Furthermore, each wall-shaped conductor 42 is connected to an outer conductor 45 at one end 421 of the wall-shaped conductor 42, but the amount by which the wall-shaped conductor 42 protrudes from the outer conductor 45 is shorter than in the first embodiment. The wall-shaped conductor 42 only needs to be interposed between the inner conductors 41 in the circumferential direction of the coaxial cable 40C. Because the wall-shaped conductor 42 is interposed between the inner conductors 41 adjacent to each other in the circumferential direction of the coaxial cable 40C, crosstalk between the inner conductors 41 can be suppressed.

[0103] In this embodiment, similarly to the first embodiment described above, the internal conductor 41 has a cross-sectional shape extending substantially parallel to the inner peripheral surface 451 of the external conductor 45, so that a microstrip line structure is formed between the internal conductor 41 and the external conductor 45. In this case, it is preferable that the shortest distance D1 between adjacent internal conductors 41 is greater than the shortest distance D2 between the internal conductor 41 and the external conductor 45 (D1>D2). This increases the distance between the internal conductors 41, and makes it possible to further suppress crosstalk between the internal conductors 41.

[0104] In this embodiment, as in the first embodiment described above, the coaxial cable 40C includes a plurality of inner conductors 41, so that the coaxial cables 40B can be arranged within the motherboard 30 at high density.

[0105] Furthermore, in this embodiment, similar to the first embodiment described above, each internal conductor 41 has a thin cross-sectional shape extending in an arc shape, which reduces the reaction force of the coaxial cable 40C and makes it lighter, while also preventing condensation from forming inside the motherboard 30.

[0106] As shown in Fig. 7, a coaxial cable 40C does not necessarily have to include the wall-like conductor 42. Fig. 7 is a cross-sectional view showing a first modified example of the coaxial cable according to the third embodiment of the present invention.

[0107] Furthermore, the number of inner conductors 41 included in the coaxial cable 40C is not particularly limited to the above. For example, as shown in Fig. 8, the coaxial cable 40C may include two inner conductors 41. Fig. 8 is a cross-sectional view showing a second modified example of the coaxial cable according to the third embodiment of the present invention. Alternatively, although not specifically shown, the coaxial cable 40 may include four or more inner conductors 41.

[0108] <<Fourth Embodiment>> 9 is a cross-sectional view showing a coaxial cable 40D according to a fourth embodiment of the present invention. This embodiment differs from the third embodiment in that an insulating portion 44D includes an air layer 445, but other configurations are similar to those of the third embodiment. Below, only the differences between coaxial cable 40D according to the fourth embodiment and the third embodiment will be described, and portions having the same configuration as those of the third embodiment will be assigned the same reference numerals and their description will be omitted.

[0109] 9, the insulating part 44D of the present embodiment includes a resin body 441 and an air layer 445. The resin body 441 of the present embodiment has a cylindrical shape and has a hole 443 at its center. The hole 443 penetrates the resin body 441 over the entire axial direction of the coaxial cable 40D. The air present in the hole 443 forms an air layer 445. The air layer 445 is interposed between the multiple inner conductors 41.

[0110] Note that instead of the air layer 445, a gas other than air may exist in the hole 443, or the inside of the hole 443 may be a vacuum. In addition, although the internal conductor 41 is completely buried inside the resin body 441 in FIG. 9, the internal conductor 41 may be exposed to the air layer 445 from the resin body 441.

[0111] In this embodiment, as in the third embodiment described above, the coaxial cable 40D includes a plurality of inner conductors 41, so that the coaxial cables 40D can be arranged within the motherboard 30 at high density.

[0112] Furthermore, in this embodiment, similar to the third embodiment described above, each internal conductor 41 has a thin cross-sectional shape extending in an arc shape, which reduces the reaction force of the coaxial cable 40D and makes it lighter, while also preventing condensation from forming inside the motherboard 30.

[0113] Furthermore, in this embodiment, similar to the third embodiment described above, the internal conductor 41 has a cross-sectional shape that extends substantially parallel to the inner circumferential surface 451 of the external conductor 45, and therefore a microstrip line structure is formed between the internal conductor 41 and the external conductor 45.

[0114] Furthermore, in this embodiment, as in the third embodiment described above, a wall-shaped conductor 42 is interposed between the inner conductors 41 adjacent to each other in the circumferential direction of the coaxial cable 40D, thereby suppressing crosstalk between the inner conductors 41.

[0115] Furthermore, in this embodiment, the air layers 445 are interposed between the multiple internal conductors 41, and the dielectric constant of the insulating portion 44D is reduced in the portions between the internal conductors 41, thereby increasing the electrical distance between the internal conductors 41. Also, in this embodiment, the electrical distance between the internal conductors 41 can be adjusted by adjusting the size of the holes 443 in the resin body 441.

[0116] <<Fifth Embodiment>> 10 is a cross-sectional view showing a coaxial cable 40E according to a fifth embodiment of the present invention. This embodiment differs from the third embodiment in that an insulating portion 44E includes an air layer 445, but other configurations are similar to those of the third embodiment. Below, only the differences between the coaxial cable 40E according to the fifth embodiment and the third embodiment will be described, and portions having the same configuration as those of the third embodiment will be assigned the same reference numerals and their description will be omitted.

[0117] As shown in FIG. 10 , the insulating part 44E of this embodiment includes a resin body 441 and an air layer 445. The resin body 441 of this embodiment has a cylindrical shape and has a plurality of grooves 444 (three in this embodiment) on its outer circumferential surface 442. Each groove 444 is recessed radially inward of the coaxial cable 40E and extends over the entire axial length of the coaxial cable 40E. The plurality of grooves 444 are arranged at substantially equal intervals in the circumferential direction of the coaxial cable 40E and are arranged concentrically with the outer conductor 45. The inner conductor 41 is located at the bottom of the groove 444. The outer conductor 45 covers the outer circumferential surface 442 of the resin body 441, and the air present in each groove 444 forms an air layer 445. Therefore, the air layer 445 is interposed between the inner conductor 41 and the outer conductor 45.

[0118] 10, the internal conductor 41 is exposed to the air layer 445 from the resin body 441, but the internal conductor 41 may be completely buried in the resin body 441.

[0119] In this embodiment, as in the third embodiment described above, the coaxial cable 40E includes a plurality of inner conductors 41, so that the coaxial cables 40E can be arranged within the motherboard 30 at high density.

[0120] Furthermore, in this embodiment, similar to the third embodiment described above, each internal conductor 41 has a thin cross-sectional shape extending in an arc shape, which reduces the reaction force of the coaxial cable 40E and makes it lighter, while also preventing condensation from forming inside the motherboard 30.

[0121] Furthermore, in this embodiment, similar to the third embodiment described above, the internal conductor 41 has a cross-sectional shape that extends substantially parallel to the inner circumferential surface 451 of the external conductor 45, and therefore a microstrip line structure is formed between the internal conductor 41 and the external conductor 45.

[0122] Furthermore, in this embodiment, as in the third embodiment described above, a wall-shaped conductor 42 is interposed between the inner conductors 41 adjacent to each other in the circumferential direction of the coaxial cable 40E, thereby suppressing crosstalk between the inner conductors 41.

[0123] Furthermore, in this embodiment, an air layer 445 is interposed between the internal conductor 41 and the external conductor 45, and the dielectric constant of the insulating portion 44E is reduced in the portion between the internal conductor 41 and the external conductor 45. This makes it possible to increase the physical distance between the internal conductors 41 while maintaining the electrical distance between the internal conductor 41 and the external conductor 45, thereby suppressing crosstalk between the internal conductors 41.

[0124] In this embodiment, in addition to the grooves 444, the holes 443 described in the fourth embodiment may be formed in the resin body 441. The holes 443 can increase the electrical distance between the internal conductors 41 or adjust the electrical distance between the internal conductors 41.

[0125] It should be noted that the above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, the elements disclosed in the above embodiments are intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0126] For example, in the third to fifth embodiments, the conductors 41 to 43 and the insulating portion 44 (44D, 44E) may be formed by twisting together a plurality of wires, as in the second embodiment. [Explanation of symbols]

[0127] 1...Device testing equipment 10...Tester 20...DSA 21...Socket 22...Contactor 23...Socket board 24...Coaxial connector 30…Motherboard 31...Case 32...Coaxial connector 40, 40B~40E...Coaxial cable 41, 41B...Inner conductor 411...Metal wire 42, 42B...Wall-shaped conductor 421...one end 422...other end 423,423a,423b...metal wire 43, 43B...Center conductor 431...Metal wire 44, 44C~44E...Insulation section 441...Resin body 442...Outer surface 443…hole 444...Groove 445...Air layer 446…Element wire assembly 447...Resin wire 45...Outer conductor 451…Inner peripheral surface 452...Outer surface 453…Room 46...Outer cover 70...Test head 71...Test module 72…Cable 80...Mainframe 90...Handler 91...Chamba 92…Aperture 100...DUT 110...Terminal

Claims

1. a cylindrical outer conductor; an insulating portion covered with the outer conductor; a plurality of inner conductors disposed within the insulation.

2. 2. The coaxial cable according to claim 1, A coaxial cable in which the multiple inner conductors are arranged in the insulating portion so as to be spaced apart from each other.

3. 2. The coaxial cable according to claim 1, The inner conductor of the coaxial cable has a cross-sectional shape that extends in an arc shape.

4. 2. The coaxial cable according to claim 1, A coaxial cable in which the inner conductor has a cross-sectional shape that extends substantially parallel to the inner circumferential surface of the outer conductor.

5. 2. The coaxial cable according to claim 1, A coaxial cable in which the thickness of the inner conductor along the radial direction of the coaxial cable is smaller than the width of the inner conductor along the circumferential direction of the coaxial cable.

6. 2. The coaxial cable according to claim 1, The plurality of inner conductors are arranged at intervals in the circumferential direction of the coaxial cable and are arranged concentrically with the outer conductor.

7. 2. The coaxial cable according to claim 1, The inner conductor is a metal layer having an arc-shaped cross section, or a coaxial cable having a plurality of metal wires arranged in an arc-shaped configuration.

8. 2. The coaxial cable according to claim 1, The coaxial cable includes a first insulating portion including a resin material.

9. 9. The coaxial cable according to claim 8, the first insulating portion is a columnar or tubular resin body that holds the plurality of internal conductors, The outer conductor of the coaxial cable is covered with the resin body.

10. 9. The coaxial cable according to claim 8, the first insulating portion includes a plurality of resin wires assembled together and a wire assembly that holds the plurality of inner conductors; The outer conductor covers the wire assembly.

11. 9. The coaxial cable according to claim 8, The coaxial cable has a second insulating portion made of gas or vacuum.

12. 12. The coaxial cable of claim 11, The second insulating portion is interposed between the plurality of inner conductors.

13. 12. The coaxial cable of claim 11, The second insulating portion is interposed between the inner conductor and the outer conductor of the coaxial cable.

14. 2. The coaxial cable according to claim 1, the coaxial cable includes a plurality of wall-like conductors interposed between the plurality of inner conductors in a circumferential direction of the coaxial cable, The wall-like conductor is a coaxial cable electrically connected to the outer conductor.

15. 15. The coaxial cable of claim 14, A coaxial cable in which the plurality of wall-like conductors are connected to each other at the center of the coaxial cable.

16. 15. The coaxial cable of claim 14, The wall-shaped conductor is a metal layer extending in the radial direction of the coaxial cable, or a coaxial cable having a plurality of metal wires arranged in the radial direction.

17. A device test apparatus for testing a DUT, comprising: A device testing apparatus comprising the coaxial cable according to any one of claims 1 to 16.

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