WO2008123652A1

WO2008123652A1 - Coaxial connecting system and coaxial connecting device

Info

Publication number: WO2008123652A1
Application number: PCT/KR2008/000342
Authority: WO
Inventors: Maeng Youl Lee; Yong Goo Lee; Min Su Park; Sung Jin Kim
Original assignee: Gigalane Co., Ltd.
Priority date: 2007-04-09
Filing date: 2008-01-18
Publication date: 2008-10-16
Also published as: KR20080091582A; KR100874191B1

Abstract

A coaxial connecting system and coaxial connecting device is provided for making a reliable electrical connection between a coaxial cable and a device under test. A coaxial connecting system for electrically connecting a test device to a printed circuit board to be tested through at least one coaxial cable includes a coupling connector for making an electrical ground connection between the coaxial cable and the printed circuit board, the coupling connector having at least one jack hole; and at least one coaxial connecting device penetrating the at least one jack hole for establishing the electrical ground connection and a signal connection between the coaxial cable and the printed circuit board. The coaxial connecting device comprises a signal pin which electrically connects a signal conductor of the coaxial cable to a signal pad of the printed circuit board, a ground coupler which electrically connects a ground conductor of the coaxial cable to a ground pad of the printed circuit board, the ground coupler surrounding the signal pin while maintaining a predetermined distance, and a insulator which surrounds a part of the signal pin inside the ground coupler for electrically isolating the signal pin from the ground coupler and maintaining the ground coupler and the signal pin in a coaxial manner. The coaxial connecting system and coaxial connecting device of the present invention allow connecting a coaxial cable to a PCB with shortened and stable electrical path, resulting in reduction of high frequency signal loss and distortion.

Description

COAXIAL CONNECTING SYSTEM AND COAXIAL CONNECTING DEVICE

Technical Field

[1] The present invention relates to a coaxial connecting system and, in particular, to a coaxial connecting system and coaxial connecting device for making a reliable electrical connection between a coaxial cable and a device under test. Background Art

[2] Coaxial cable is an electrical cable consisting of an inner signal conductor, an insulator surrounding the signal conductor, and an outer cylindrical conducting shield surrounding the insulator such that the inner conductor and the outer shield shares the same axis.

[3] The coaxial cable is often used for precise electric and electronic devices and test devices due to its low electrical interference and transmission stability relative to other types of cables. A test device requires an intermediate connection means for securing reliable electrical connectivity of the coaxial cable, which is elongated from the test device, to the test objects even with repeated attachment and detachment.

[4] Particularly, since the test device is used for testing sensitive electrical characteristics of a printed circuit board or semiconductor device, the reliability of the interconnection means is very important.

[5] In the meantime, as the devices are highly getting advanced in operation speed and performance, the test signals are more vulnerable to attenuation and interference, thereby degrading reliability of the test result.

[6] Therefore, there has been a requirement for a connection device robust to attenuation and frequency noise so as to secure reliable transmission of the test signals to the devices. Disclosure of Invention

Technical Problem

[7] The present invention has been made in an effort to solve the above problems, and it is an object of the present invention to provide a coaxial connecting system that is capable of minimizing the signal transfer path between a coaxial cable and a PCB and isolating the signal path, thereby improving robustness to external noise and reducing signal loss.

[8] It is another object of the present invention to provide a coaxial connecting device that is capable of minimizing the signal transfer path between a coaxial cable and an external pad and isolating the signal path, thereby improving robustness to external noise and reducing signal loss. Technical Solution

[9] In one aspect of the present invention, the above and other objects of the present invention are accomplished by a coaxial connecting system for electrically connecting a test equipment to a printed circuit board to be tested through at least one coaxial cable. The coaxial connecting system comprises a coupling connector for making an electrical ground connection between the coaxial cable and the printed circuit board, the coupling connector having at least one jack hole; and at least one coaxial connecting device penetrating the at least one jack hole for establishing the electrical ground connection and a signal connection between the coaxial cable and the printed circuit board, wherein the coaxial connecting device comprises a signal pin which electrically connects a signal conductor of the coaxial cable to a signal pad of the printed circuit board, a ground coupler which electrically connects a ground conductor of the coaxial cable to a ground pad of the printed circuit board, the ground coupler surrounding the signal pin while maintaining a predetermined distance, and a insulator which surrounds a part of the signal pin inside the ground coupler for electrically isolating the signal pin from the ground coupler and maintaining the ground coupler and the signal pin in a coaxial manner.

[10] Preferably, the coupling connector comprises a jack having at least one jack hole which the coaxial connecting device is inserted; and a jack interposer which is elastically contacting the ground pad of the printed circuit board and located between the jack and the printed circuit board for making an electrical connection between the ground pad of the printed circuit board and the ground conductor of the coaxial cable.

[11] Preferably, the jack interposer is a thin metal sheet having at least one interposer hole corresponding to the jack hole and having a plurality of teeth formed along an inner wall of the interposer hole, the teeth being alternately bent up and down.

[12] Preferably, the jack hole has a stepped recess forming an inlet for facilitating reception of the coaxial connecting device the ground conductor of the coaxial cable is tightly contacted with the inner wall of the jack hole and electrically connected the ground pad of the printed circuit board, the jack has at least one guide pin which is connected to the printed circuit board.

[13] Preferably, the ground coupler comprises a ground connector tightly surrounding the ground conductor exposed at an end of the coaxial cable and a cylindrical guide tube connected to the ground connector and surrounding the signal pin while maintaining a predetermined distance from the signal pin, wherein the ground connector is electrically connected to the ground conductor of the coaxial cable and has a first protrusion formed around an outer surface circumferentially for fixing the cylindrical guide tube.

[14] Preferably, the cylindrical guide tube comprises a fixing part coupled with the ground connector by means of shrink fit and fixed by the first protrusion and having a recess with a shape of "D" formed on an inner wall and a ground contact elongated from the fixing part and contacting the ground pad by elastic force.

[15] Preferably, the ground contact has at least one slit formed in a longitudinal direction.

[16] Preferably, the signal pin is a spring probe pin. Preferably, the signal pin comprises a first part which is elastically contacting with the signal pad; a second part longitudinally connected to a proximal end of the first part and having a fixation protrusion for limiting movement of the insulator, the second part being formed with a diameter larger than that of the first part such that the first part reciprocates within the second part; and a third part longitudinally connected to the second part at one end and having an insertion hole formed at the other end for receiving the signal conductor, the third part having a diameter larger than that of the second part.

[17] Preferably, the insulator is fixed by the recess of the cylindrical guide tube and the fixation protrusion at one end and by the other end of the ground connector and the third part at the other end, and the signal pin and the ground coupler are isolated from each other by the insulator and air in between and impedance matched.

[18] Preferably, the ground coupler comprises a ground connector connected to the ground conductor of the coaxial cable and coupled with the insulator by means of shrink fit and a ground contact elongated from the ground connector and inserted into the jack hole while tightly contacting with the inner wall of the jack hole.

[19] Preferably, the signal pin comprises a first part which is electrically contacting with the signal pad; a second part which a diameter larger than that of the first part and is connected to the first part at one end and has a insertion hole formed at the other end for receiving the signal conductor of the coaxial cable.

[20] Preferably, the insulator is inserted into the ground coupler while surrounding the second part of the signal pin and fixed by means of shrink fit, and the signal pin and the ground coupler are isolated from each other by the insulator and air in between and impedance matched.

[21] Preferably, the jack holes have stepped recesses formed with different depths for distributing vertical pressure generated when the end of the cylindrical guide tubes are inserted into respective jack holes.

[22] In another aspect of the present invention, the above and other objects of the present invention are accomplished by a coaxial connecting device for electrically connecting a coaxial cable to a printed circuit board. The coaxial connecting device includes a signal pin for electrically connecting a signal conductor of the coaxial cable to a signal pad of the printed circuit board; a ground coupler for electrically connecting a ground conductor of the coaxial cable to a ground pad of the printed circuit board; a insulator surrounding a part of the signal pin for electrically isolating the ground coupler and the signal pin from each other and maintaining the ground coupler and the signal pin in a coaxial manner.

[23] Preferably, the ground coupler comprises a ground connector tightly surrounding the ground conductor exposed at an end of the coaxial cable; and a cylindrical guide tube connected to the ground connector and surrounding the signal pin while maintaining a predetermined distance from the signal pin, wherein the ground connector is electrically connected to the ground conductor of the coaxial cable and has a first protrusion formed around an outer surface circumferentially for fixing the cylindrical guide tube.

[24] Preferably, the cylindrical guide tube comprises a fixing part coupled with the ground connector by means of shrink fit and fixed by the first protrusion and having a recess with a shape of "D" formed on an inner wall; and a ground contact elongated from the fixing part and contacting the ground pad by elastic force.

[25] Preferably, the ground contact has at least one slit formed in a longitudinal direction. Preferably, the signal pin is a spring probe pin.

[26] Preferably, the signal pin comprises a first part which is elastically contacting with the signal pad; a second part longitudinally connected to a proximal end of the first part and having a fixation protrusion for limiting movement of the insulator, the second part being formed with a diameter larger than that of the first part such that the first part reciprocates within the second part; and a third part longitudinally connected to the second part at one end and having an insertion hole formed at the other end for receiving the signal conductor, the third part having a diameter larger than that of the second part.

[27] Preferably, the insulator is fixed by the recess of the cylindrical guide tube and the fixation protrusion at one end and by the other end of the ground connector and the third part at the other end, and the signal pin and the ground coupler are isolated from each other by the insulator and air in between and impedance matched.

[28] Preferably, the ground coupler comprises a ground connector connected to the ground conductor of the coaxial cable and coupled with the insulator by means of shrink fit; and a ground contact elongated from the ground connector and contacted with the coupling connector by elastic force.

[29] In accordance with another aspect of the present invention, the above and other objects are accomplished by a coaxial connecting system for electrically contacting a test device to a printed circuit board to be tested through at least one coaxial cable. The coaxial connecting system includes a coupling connector for making an electrical ground connection between the coaxial cable and the printed circuit board, the coupling connector having more than one jack hole; and at least one coaxial connecting device penetrating each jack hole for establishing the electrical ground connection and a signal connection between the coaxial cable and the printed circuit board.

[30] Preferably, the coupling connector comprises a jack having the jack hole which is connected to a signal pin of the coaxial connecting device connected to a signal conductor of the coaxial cable and a cylindrical guide tube of the coaxial connecting device connected to a ground conductor of the coaxial cable, and electrically connects the signal pin to a ground pad of the printed circuit board and the cylindrical guide tube to a signal pad of the printed circuit board ;and a jack interposer which is located between the jack and the printed circuit board for making an electrical connection between the jack and the circuit board.

[31] Preferably, the jack is provided with the jack hole having a stepped recess forming an inlet for facilitating reception of the coaxial connecting device and comprises a jack pin connected to the signal pad of the printed circuit board at one end and connected to the signal pin of the coaxial connecting device at the other end ; and a jack isolator surrounding the jack pin in the jack hole for isolating the jack pin against the inner wall of the jack hole, the end of the cylindrical guide tube electrically contacting with the inner wall of the jack hole for making the electrical connection between the ground conductor of the coaxial cable and the ground pad of the printed circuit board.

[32] Preferably, the stepped recesses of adjacent jack holes are formed with different depths for distributing vertical pressure generated when the end of the cylindrical guide tubes are inserted into respective jack holes.

[33] Preferably, the jack interposer is provided with at least one interposer hole corresponding to the jack hole and having a plurality of teeth formed along an inner wall of the interposer hole, the teeth being alternately bent up and down.

Advantageous Effects

[34] The coaxial connecting system and coaxial connecting device according to the present invention allow reducing the lengths signal and ground paths between a coaxial cable and a PCB and securing stable contacts, resulting in reduction of high frequency signal loss and distortion. Brief Description of the Drawings

[35] The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description in conjunction with the accompanying drawings, in which:

[36] FIG. 1 is a perspective view illustrating a coaxial connecting system according to an exemplary embodiment of the present invention;

[37] FIG. 2 is a perspective view illustrating a configuration of the jack of FIG. 1 ;

[38] FIG. 3 is a perspective view illustrating a configuration of the jack interposer of

FIG l; [39] FIG. 4 is a perspective view illustrating a coaxial connecting device of the coaxial connecting device of FIG. 1 ;

[40] FIG. 5 is a cross sectional view illustrating a coaxial connecting device of FIG. 4;

[41] FIG. 6 is a cross sectional view of a coaxial connecting device aligned on a PCB for illustrating steps of operation of the coaxial connecting device of FIG. 4; [42] FIG. 7 is an enlarged view illustrating the coaxial connecting device at step (d) of

FIG. 6; [43] FIG. 8 is an enlarged view illustrating the coaxial connecting device at step (e) of

FIG. 6; [44] FIG. 9 is a cross sectional view illustrating a coaxial connecting device according to another exemplary embodiment of the present invention; [45] FIG. 10 is a cross sectional view illustrating a coaxial connecting device according to an exemplary embodiment of the present invention; [46] FIG. 11 is a cross sectional view of a coaxial connecting device aligned on a PCB for illustrating steps of operation of the coaxial connecting device of FIG. 10; [47] FIG. 12 is an enlarged view illustrating the coaxial connecting device at step (e) of

FIG. 11; [48] FIG. 13 is a cross sectional view illustrating a jack according to another exemplary embodiment of the present invention; and [49] FIG. 14 is a cross sectional view illustrating a jack according to another exemplary embodiment of the present invention.

Best Mode for Carrying Out the Invention [50] Exemplary embodiments of the present invention are described with reference to the accompanying drawings in detail. The same reference numbers are used throughout the drawings to refer to the same or like parts. Detailed descriptions of well-known functions and structures incorporated herein may be omitted to avoid obscuring the subject matter of the present invention. [51] In the following, the term proximal means nearest to the test device , and distal means farthest from the test device . [52] FIG. 1 is a perspective view illustrating a coaxial connecting system according to an exemplary embodiment of the present invention. As shown in FIG. 1, the coaxial connecting system 100 makes electrical connections to Printed Circuit Board (PCV)

110. The coaxial connecting system 100 includes a coupling part and coaxial connecting devices (CAC).

[53] The PCB 110 is provided with a plurality of signal pads (not shown) and ground pads (not shown) that are arranged on a substrate for allowing the coaxial connecting devices to electrically connect to the devices mounted on the PCB 110.

[54] The coupling part 115 is contacting with the ground pads so as to make shortest electrical paths between the ground conductors of coaxial cables and the ground pads. The coupling part 115 has a shape of plate having a plurality of holes (HL and IHL) formed over the entire surface for receiving the coaxial connecting devices.

[55] In more detail, the coupling part 115 is provided with a jack interposer 120 which is elastically contacted with the ground pads of the PCB 110 for providing stable and shortest electrical paths between the ground conductors of the coaxial cables and the ground pads and a jack 130 arranged on the top surface of the jack interposer 120. The jack interposer 120 is provided with a plurality of interposer holes (IHL) formed over its entire surface and the jack 130 is provided with a plurality of jack holes (HL) arranged in a corresponding manner.

[56] The coaxial connecting device 100 also includes a mould 140 mounted on the top surface of the coupling part 115. In this manner, the coaxial connecting system 100 allows at least one coaxial connecting device to be held by means of the mould 140, jack 130, and jack interposer 120 and to contact with the PCB 110. With this configuration of the coaxial connecting device 100, the coaxial connecting device carried by the coaxial connecting device 100 can securely and stably contact with the PCB 110, whereby the ground connector of the coaxial connecting device can be located at a position close to the ground pad of the PCB 110, resulting in reduction frequency noise.

[57] FIG. 2 is a perspective view illustrating a configuration of the jack of FIG. 1, and

FIG. 3 is a perspective view illustrating a configuration of the jack interposer of FIG 1.

[58] The jack and jack interposer are made of metallic material so as to be used as a path of the electrical signals.

[59] As shown in FIG. 2, the jack 130 is provided with a plurality of insertion jack holes

(HL) for receiving the respective coaxial connecting devices. Each jack hole has the shape of funnel of which diameter decreases to the bottom surface of the jack 130. The jack 130 is fixed to the PCB 110 by means of at least one guide pins (GDP).

[60] The guide pin (GDP) is used for removing an offset between the jack 130 and the

PCB 110. The jack hole (HL) has a shape of funnel for facilitating insertion of the cylindrical guide tube (not shown) of the coaxial connecting device (CAC). The ground conductor of the coaxial cable is electrically connected to a corresponding ground pad via the inner wall of the jack hole (HL) such that the shortest electrical connection path can be accomplished between the ground conductor and the ground pad.

[61] The jack interposer 120 is a thin metal sheet having interposer holes (IHL) corresponding to the jack holes of the jack 130. The jack 130 and the jack interposer 120 are connected to the PCB 110 by means of screws. The jack 130 and the interposer 120 are provided with screw holes 210 and 210a for screw coupling with the PCB 110.

[62] The jack holes (HL) of the jack 130 and the interposer holes (IHL) of the interposer

120 are formed correspondingly to the ground pads (not shown) such that the signal pins of the coaxial connecting device penetrated through the holes are contacting with the signal pads (not shown) of the PCB 110.

[63] Each interposer hole(IHL) is provided with a plurality of metal plates (MP) protruded along its circumferential inner wall with a regular interval. The metal plates are bent alternately up and down.

[64] The jack interposer 120 is interposed between the jack 130 and the PCB 110 for securing ideal surface contact even when at least one the jack 130 and the PCB 110 does not provide regular contact surface.

[65] The metal plates (MP) of the jack interposer 120 are alternately bent up and down to allow the jack interposer 120 to elastically contact with the jack 130 and the PCB 110, thereby securing reliable electrical connection of the jack 130, jack interposer 120, and PCB 110 and minimizing ground connection between the PCB 110 and the ground pad.

[66] FIG. 4 is a perspective view illustrating a coaxial connecting device of the coaxial connecting device of FIG. 1, and FIG. 5 is a cross sectional view illustrating a coaxial connecting device of FIG. 4.

[67] The structure of the coaxial connecting device is described hereinafter in detail with reference to FIGs. 4 and 5. The coaxial connecting device (CAC) is connected to a coaxial cable 410 at its proximal end and penetrates the jack hole (HL) of the jack 130 such that its distal end contacts the signal and ground pads of the PCB 110.

[68] The coaxial cable 410 includes a signal conductor 410c, a dielectric insulator 410b surrounding the signal conductor 410c, a ground conductor 410a surrounding the dielectric insulator 410b, and a plastic jacket surrounding the ground conductor 410.

[69] The coaxial connecting device (CAC) includes a signal pin 420, a ground coupler

425, and a insulator 450. The ground coupler 425 is directly connected to the ground conductor 410a of the coaxial cable 410 and surrounds the signal pin 420 while maintaining a distance to the signal pin 420 by means of the insulator 450.

[70] The ground coupler 425 is provided with a ground connector 430 which surrounds the ground conductor 410a of the coaxial cable 410 so as to electrically contact with the ground conductor 410a and a cylindrical guide tube 440 which is surroundingly coupled with the ground connector 430. [71] The coaxial connecting device (CAC) relays the electrical signal input though the signal conductor 410c of the coaxial cable to the signal pad on the PCB 110 via the signal pin 420 and connects the ground conductor 410a of the coaxial cable to the ground pad on the PCB 110 via the ground connector 430 and the cylindrical guide tube 440.

[72] The insulator 450 has a shape of a doughnut such that the signal pin 420 is inserted into the center opening of the insulator 450 and fixed at the beginning end of a third part 420c of the signal pin 420 by means of a fixing protrusion 510 formed around the beginning end of the third part 420c. The insulator 450 surrounds a part of the signal pin 420 so as to electrically isolate the signal pin 420 and the cylindrical guide tube 440 each other and maintain the coaxial relationship of the signal pin 420 and the cylindrical guide tube 440.

[73] The insulator 450 is fixed by a stepped potion of the guide tube 440a and the fixation protrusion 510 formed on the signal pin 420 at its distal end and by the distal end of the ground connector 430 and the distal end of the third part 420c of the signal pin 420 at its proximal end.

[74] The ground connector 430 is surroundingly connected to a distal end of the coaxial cable 410 so as to be electrically connected to the ground conductor 410a of the coaxial cable 410. The plastic jacket of the coaxial cable 410 prevents the ground connector 430 from sliding along the coaxial cable 410. The ground connector 430 is tightly surrounding the ground conductor 410a of the coaxial cable 410 so as to make the electrical connection to the ground conductor 410a. Since the ground connector 430 is connected to the cylindrical guide tube 440, the entire cylindrical guide tube 440 functions as a ground.

[75] The ground connector 430 has a protrusion 430a formed around the circumferential outer surface in the middle of its length such that the protrusion 430a acts as a stopper of the cylindrical guide tube 440. The proximal end of the ground connector is coupled with the ground conductor 410a of the coaxial cable 410.

[76] The signal pin 420 is configured to elastically contact with the signal pad so as to make the electrical connection between the signal conductor 410c and the signal pad. The signal pin 420 can be made of any of conductive materials. Preferably, the signal pin 420 is a spring probe pin. That is, the signal pin 420 is configured such that its distal end can be elastically contracted and extended relative to the cylindrical guide tube 440.

[77] The signal pin 420 is provided with a first part 420a, a second part 420b, and a third part 420c that are formed with different diameters. The first part 420a has a diameter smaller than that of the second part 420b and elastically connected to the distal end of the second part 420b so as to reciprocate inside the second part 420b. The second part 420b is provided with a fixation protrusion 510 formed around its outer surface for limiting the movement of the insulator 450 mounted thereon.

[78] The third part 420c is connected to the proximal end of the second part 420b and having a diameter larger than that of the second part 420b. The third part 420c is provided with a hole 520 for receiving the signal conductor 410c of the coaxial cable 410.

[79] The signal conductor 410c of the coaxial cable 410 is fixed to the third part 420c of the signal pin 420 by means of soldering after being inserted to the hole 520. Although the signal conductor 410 is fixed to the signal pin 420 by means of soldering, the fixation can be accomplished with different techniques.

[80] The signal pin 420 insulated against the cylindrical guide tube 440 by means of space secured by the insulator 450 interposed between the second part 420b and the cylindrical guide tube 440. The signal pin 420 and the ground coupler 425 are electrically isolated from each other by the insulator 450 and the air in between. The ground connector 430 is inserted into the cylindrical guide tube and fixed therein by means of shrink fit.

[81] The cylindrical guide tube 440 receives the signal pin 420 from the first part 420a to the third part 420c and tightly fitted by means of the insulator 450.

[82] The cylindrical guide tube 440 surrounds the outer surface of the ground connector

430 and the signal pin 420 while maintaining a predetermined distance with the signal pin 420. The cylindrical guide tube 440 is provided with a fixing part 440a, which is engaged with the insulator 450 and the ground connector 430, a ground contact 440b elongated from the fixing part 440a.

[83] The fixing part 440a is connected to the ground connector 430 to the protrusion

430a by means of shrink fit and has a stepped potion for fixing the insulator 450. The ground contact 440b is formed integral with the fixing part 440a and contact with the inner wall of the hole (HL) of the jack 130.

[84] The ground contact 440b is formed elastically. The ground contact 440b can be formed such that its end is slightly bent outward. Preferably, the ground contact 440b has at least one slit formed in the longitudinal direction as shown if FIG. 4 so as to generate electric force.

[85] By forming the ground contact 440b in such manner, the ground contact 440b is tightly contacted with the inner wall of the jack hole (HL) of the jack 130 due to the elastic force generating outward.

[86] After the cylindrical guide tube 440 is coupled with the ground connector 430, the ground connector 430 and the ground conductor 410a of the coaxial cable are soldered such that the ground connector 430 and the cylindrical guide tube 440 function as a ground. [87] FIG. 6 is a cross sectional view of a coaxial connecting device aligned on a PCB for illustrating steps of operation of the coaxial connecting device of FIG. 4.

[88] In FIG. 6, the jack interposer 120 is interconnecting the ground pad (PG) and the jack 130 in between.

[89] At step (a) of FIG. 6, the contact part 440b of the coaxial connecting device (CAC) is aligned over the jack hole (HL) of the jack 130. At this time, the split ends of the ground contact 440b are stretched out.

[90] At step (b) of FIG. 6, the ground contact 440b of the coaxial connecting device

(CAC) begins being inserted into the jack hole (HL) of the jack 130. Here, the end of the ground contact 440b contacts the jack, but the signal pin 420 is not contacted with the signal pad (PS) yet.

[91] At step (c) of FIG. 6, the end of the contact part 440b is inserted into the jack hole (

HL) of the jack 130. The jack hole (HL) has a shape of a funnel such that the contact part 440b of the coaxial connecting device (CAC) is easily slid into the jack hole (HL). At this time the slit ends of the contact part 440b are shrunken by contacting the inner surface of the hole (HL).

[92] At step (d) of FIG. 6, the contact part 440b is inserted into the jack hole (HL) halfway. At this time, the slit ends of the contact part 440b are tightly contacted with the inner wall of the jack hole (HL) by the elastic force generated outward and the tip of the signal pin 420 is contacted with the signal pad (PS). In this formation, the ground conductor 410a of the coaxial cable 410 is electrically connected with the ground pad (PG) of the PCB 110.

[93] At step (e) of FIG. 6, the ground contact 440b of the coaxial connecting device

(CAC) is completely inserted into the jack hole (HL) of the jack 130. In this case, the tip of the first part 420a is retreated into the second part 420b so as to be contacted with the signal pad (SG) more tightly by the elastic force while maintaining the tight connection between the ground contact 440b and the inner wall of the jack hole (HL).

[94] FIG. 7 is an enlarged view illustrating the coaxial connecting device at step (d) of

FIG. 6, and FIG. 8 is an enlarged view illustrating the coaxial connecting device at step (e) of FIG. 6.

[95] Referring to FIGs. 7 and 8, the ground contact 440b is tightly contacted with the inner wall of the jack hole (HL) by the restoring force (P) of the slit ends of the ground contact 440b which is generating outward. The ground conductor 410a of the coaxial cable 410 is electrically connected to the ground pad (PG) via the ground contact 440b, the jack 130, and the interposer 120. In this case, the ground contact 440b and the ground pad (PG) are connected through a short electrical path, thereby reducing noise in high frequency transmission.

[96] FIG. 9 is a cross sectional view illustrating a coaxial connecting device according to another exemplary embodiment of the present invention.

[97] Referring to FIG. 9, a ground coupler 830 is provided with a ground connector 810 which surrounds the distal end of the coaxial cable 410 and is directly coupled with the ground conductor of the coaxial cable 410 and a ground contact 820 which is elongated from the distal end of the ground connector 810 and inserted into the jack hole (HL) of the jack 130 so as to be contacted with the inner wall of the jack hole. The ground contact 820is formed so as to be elastically shrunken inward. The ground contact 820 also can be configured such that its end to be slightly bent outward.

[98] The ground connector 810 and the ground contact 820of the ground coupler 830 are formed integrally unlike in FIG. 4. The ground connector 810 is swollen at a portion near the contact part 820, which makes comfortable to hold. However, the contour of the ground connector is not limited thereto.

[99] Although the ground connector 810 is provided with a stepped portion formed on its inner wall for limiting movement of the coaxial cable in a PCB direction 110, the ground connector 810 is not limited to such an inside contour.

[100] The insulator 450 is tightly seating inside the ground coupler 830 and fixed without additional structure such as protrusion form on the inner wall of the ground coupler 830.

[101] The signal pin 840 is provided with a first part 840a which is electrically contacting with the signal pad and a second part 840b which has a diameter greater than that of the first part 840a. The second part 840b is also provided with a hole 520 formed at its proximal end for receiving the signal conductor 410c of the coaxial cable 410. The first part 840a of the signal pin 840 can be elastic like a spring probe pin. Or the first part 840a of the signal pin 840 can not be elastic and can be composed of one body with the second part 840b.

[102] The signal pin 840 has no fixation protrusion unlike the signal pin 420 of FIG. 5 has the fixation protrusion 510 for fixing the insulator 450. The signal pin 420 also has no third part but only the second part elongated without change of diameter. The insulator 450 is engaged with the second part 840b by means of shrink fit.

[103] The signal pin 840 and the ground coupler 830 are electrically isolated from each other by the insulator and air in between.

[104] Although not depicted, the coaxial connecting device can be implemented with the ground connector shown in FIG. 5 and the signal pin shown in FIG. 9 that are fixed with each other by the insulator in between. The coaxial connecting device also can be implemented with the ground connector shown in FIG. 9 and the signal pin shown in FIG. 5.

[105] The coaxial connecting devices structured as shown in FIGs. 4, 5, and 9 can be applied to the coaxial connecting system 100 of FIG. 1. The structure of the coaxial connecting system 100 has been explained above, and thus description on the same elements and functions are omitted.

[106] FIG. 10 is a cross sectional view illustrating a coaxial connecting device according to an exemplary embodiment of the present invention.

[107] The coaxial connecting system according to an embodiment of the present invention is provided for electrically connecting at least one coaxial connecting device coupled with respective coaxial cables to the circuits on a PCB.

[108] Referring to FIG. 10, the coaxial connecting device (CACl) has a structure similar to the coaxial connecting devices of FIGs. 5 and 9. The coaxial connecting device (CACl) is provided with a cylindrical guide tube 1040 connected to the ground conductor 1010a of a coaxial cable 1010, a signal pin 1020 connected to the signal conductor of the coaxial cable 1010, and an insulator 1050 interposed between the cylindrical guide tube 1040 and the signal pin 1020. The cylindrical guide tube 1040 is provided with a contact part 1040a and a fixing part 1040b. The contact part 1040a is inserted into the jack hole formed on a jack for making an electrical connection to the ground pad of a PCB.

[109] The signal pin 1020 is characterized in that its tip is not projected out of the cylindrical guide tube 1040 but ends up with the tip of the contact part 1040a unlike the signal pins 420 and 840 in FIGs. 5 and 9. The signal pin 1020 is fixed unlike the signal pins 420 and 840 that are spring probe pins contracting by force. Also, the signal pin 1020 is not elastic.

[110] The coaxial connecting system can be implemented to carry various types of coaxial connecting devices using the jack.

[I l l] FIG. 11 is a cross sectional view of a coaxial connecting device aligned on a PCB for illustrating steps of operation of the coaxial connecting device of FIG. 10.

[112] In FIG. 11, the coaxial connecting system 1100 is provided with a coupling connector 1115 and coaxial connecting devices (CACl). However, the coaxial connecting system 1100 of FIG. 11 differs from the coaxial connecting system of FIG. 1 in the structures of the coupling connector 1115 and coaxial connecting devices (CACl). In the following, the descriptions are focused on the structures and functions of the coaxial connecting system different from the coaxial system of FIG. 1.

[113] The coaxial connecting system 1100 is provided with a coupling connector 1115 having at least one jack hole (HL) through which a coaxial connecting device (CACl) is inserted such that the ground conductor 1010a of the coaxial cable is contacted with a corresponding ground pad (PG) through a minimal electrical connection path, and at least one coaxial connecting device (CACl) which is inserted into the jack hole (HL) and makes electrical connections to the signal pad (PS) and the ground pad (PG) of the PCB 110. [114] The coupling connector 1115 is provided with a jack 1030 and a jack interposer

120.

[115] The jack 1030 is provided with at least one jack hole (HL) through which the signal pin 1020 of the coaxial connecting device (CACl) connected to the signal conductor of the coaxial cable 1010 and the cylindrical guide tube 1040 of the coaxial connecting device (CACl) are inserted such that the signal pin 1020 and the cylindrical guide tube 1040 are electrically connected to the signal pad (PS) and the ground pad of the PCB 110.

[116] The jack interposer 120 is provided with at least one interposer hole (IHL) corresponding to the jack hole (HL) of the jack 1030 and arranged between the jack 1030 and the PCB 110 so as to electrically connect the jack 1030 to the PCB 110. The jack interposer 120 has shape identical with the jack interpose of FIG. 3. The structure of the jack interpose 120 can be modified in various shape capable of securing stable electrical connection between the jack 1030 and the PCB 110.

[117] As shown in FIG. 11, the jack hole (HL) of the jack 1030 is formed to have a shape of funnel such that the contact part 1040a is easily inserted into the jack hole (HL) and tightly contacted with the inner wall of the jack hole (HL). At the center of the jack hole (HL), a jack pin 1035 is arranged for receiving the signal pin 1020. The jack pin 1035 is supported by an jack isolator 1033 surrounding the jack pin 1035 and electrically isolated from the jack 1030 by the jack isolator 1033.

[118] The contact part 1040a of the cylindrical guide tube 1040 is tightly contacted with the inner wall of the jack hole (HL) of the jack 1030 such that the ground conductor 1010a of the coaxial cable 1010 is electrically connected to the corresponding ground pad (PG).

[119] The jack 1030 is provided with a jack pin 1035 for receiving the signal pin 1020 of the coaxial connecting device (CACl) so as to electrically connect the signal pin 1020 to the PCB 110. The jack pin 1035 is supported by an jack isolator 1033 surrounding a low part of the jack pin 1035 inside the jack hole (HL). The jack pin 1035 is made of a conductive material and its bottom end is protruded downward to be contacted with the signal pad (PS).

[120] Since the inner wall of the jack hole (HL) functions as a ground, the jack isolator

1033 is interposed between the jack pin 1035 and the inner wall of the jack hole (HL). The jack isolator 1033 is provided with a center hole through which the jack pin 1035 is inserted.

[121] At step (a) of FIG. 11, the contact part 1040a of the coaxial connecting device

(CACl) is aligned over the jack hole (HL) of the jack 1030. At step (b) of FIG. 6, the contact part 1040a of the coaxial connecting device (CACl) begins being inserted into the jack hole (HL) of the jack 1030. At this time, the tip of the signal pin 1020 contacts the inlet of the jack pin 1035 and the contact part 1040 contacts the inlet of the jack hole (HL).

[122] At step (c) of FIG. 11, the end of the contact part 1040a in inserted into the jack hole (HL) of the jack 1030. Since the jack hole (HL) has a shape of large funnel and the jack pin 1035 has a shape of small funnel, the contact part 1040a and the signal pin 1020 are slidably inserted into the jack hole (HL).

[123] At step (d) of FIG. 11, the contact part 1040a of the coaxial connecting device

(CACl) is further inserted into the jack hole (HL). At this time, the end of the contact part 1040a is tightly contacted with the inner wall of the jack hole (HL), and the signal pin 1020 is tightly contacted with the jack pin 1035.

[124] At step (e) of FIG. 11, the coaxial connecting device (CAC) is completely inserted into the jack hole (HL) of the jack 1030 such that the contact part 1040a maintains stable electrical connection to the inner wall of the jack hole (HL) and the signal pin 1020 maintains stable electrical connection to the jack pin 1035.

[125] FIG. 12 is an enlarged view illustrating the coaxial connecting device at step (e) of

FIG. 11. As shown in FIG. 12, the contact part 1040a is tightly contacted with the inner wall of the jack hole (HL) of the jack 1030 by the restoring force (P).

[126] The ground conductor 1010a of the coaxial cable 1010 is electrically connected to the ground pad (PG) via the fixing part 1040b and contact part 1040a of the cylindrical guide tube 1040, the inner wall of the jack hole (HL), and the jack interposer 120. Since the contact part 1040a connected to the ground conductor 1010a of the coaxial cable 1010 is positioned very close to the ground pad (PG), it is possible to reduce the high frequency noise.

[127] In FIG. 12, GS denotes a ground path, and SS denotes a signal path.

[128] FIG. 13 is a cross sectional view illustrating a jack according to another exemplary embodiment of the present invention.

[129] As shown in FIG. 13, the jack 1030 is provided with a plurality of jack holes (HL) each having stepped recess. However, the stepped recesses of the jack holes are formed to different depth for distributing the restoring force of the contact parts 1040a when multiple coaxial connecting devices are inserted to the respective jack holes (HL).

[130] In a case that stepped recesses are formed to the same depth, it may difficult for the multiple contact parts 1040a to be inserted into the respective jack holes (HL) due to the restoring forces generated in multiple directions. This problem can be solve by forming the walls 1030a, 1030b, 1030c, and 1030d defining adjacent jack holes to have stepped recesses of different depths.

[131] FIG. 14 is a cross sectional view illustrating a jack according to another exemplary embodiment of the present invention.

[132] Similar to the jack of FIG. 13, the jack 130 is provided with a plurality of jack holes (HL) defined by walls 130a, 130b, 130c, and 130d, and the jack holes (HL) are provided with stepped recesses formed to different depths, whereby the force applied to the walls can be distributed.

[133] Although exemplary embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concepts herein taught which may appear to those skilled in the present art will still fall within the spirit and scope of the present invention, as defined in the appended claims. Industrial Applicability

[134] The coaxial connecting system and coaxial connecting device of the present invention can be applied to various types of device testing systems.

Claims

[1] A coaxial connecting system for electrically connecting a test equipment to a printed circuit board to be tested through at least one coaxial cable, comprising: a coupling connector for making an electrical ground connection between the coaxial cable and the printed circuit board, the coupling connector having at least one jack hole; and at least one coaxial connecting device penetrating the at least one jack hole for establishing the electrical ground connection and a signal connection between the coaxial cable and the printed circuit board, wherein the coaxial connecting device comprises: a signal pin which electrically connects a signal conductor of the coaxial cable to a signal pad of the printed circuit board, a ground coupler which electrically connects a ground conductor of the coaxial cable to a ground pad of the printed circuit board, the ground coupler surrounding the signal pin while maintaining a predetermined distance, and a insulator which surrounds a part of the signal pin inside the ground coupler for electrically isolating the signal pin from the ground coupler and maintaining the ground coupler and the signal pin in a coaxial manner.

[2] The coaxial connecting system of claim 1, wherein the coupling connector comprises: a jack having at least one jack hole which the coaxial connecting device is inserted; and a jack interposer which is elastically contacting the ground pad of the printed circuit board and located between the jack and the printed circuit board for making an electrical connection between the ground pad of the printed circuit board and the ground conductor of the coaxial cable.

[3] The coaxial connecting system of claim 2, wherein the jack interposer is a thin metal sheet having at least one interposer hole corresponding to the jack hole and having a plurality of teeth formed along an inner wall of the interposer hole, the teeth being alternately bent up and down.

[4] The coaxial connecting system of claim 2, wherein the jack hole has a stepped recess forming an inlet for facilitating reception of the coaxial connecting device the ground conductor of the coaxial cable is tightly contacted with the inner wall of the jack hole and electrically connected the ground pad of the printed circuit board, the jack has at least one guide pin which is connected to the printed circuit board.

[5] The coaxial connecting system of claim 1, wherein the ground coupler comprises: a ground connector tightly surrounding the ground conductor exposed at an end of the coaxial cable; and a cylindrical guide tube connected to the ground connector and surrounding the signal pin while maintaining a predetermined distance from the signal pin, wherein the ground connector is electrically connected to the ground conductor of the coaxial cable and has a first protrusion formed around an outer surface cir- cumferentially for fixing the cylindrical guide tube.

[6] The coaxial connecting system of claim 5, wherein the cylindrical guide tube comprises: a fixing part coupled with the ground connector by means of shrink fit and fixed by the first protrusion and having a recess with a shape of "D" formed on an inner wall; and a ground contact elongated from the fixing part and contacting the ground pad by elastic force.

[7] The coaxial connecting system of claim 6, wherein the ground contact has at least one slit formed in a longitudinal direction.

[8] The coaxial connecting system of claim 6, wherein the signal pin is a spring probe pin.

[9] The coaxial connecting system of claim 8, wherein the signal pin comprises: a first part which is elastically contacting with the signal pad; a second part longitudinally connected to a proximal end of the first part and having a fixation protrusion for limiting movement of the insulator, the second part being formed with a diameter larger than that of the first part such that the first part reciprocates within the second part; and a third part longitudinally connected to the second part at one end and having an insertion hole formed at the other end for receiving the signal conductor, the third part having a diameter larger than that of the second part.

[10] The coaxial connecting system of claim 9, wherein the insulator is fixed by the recess of the cylindrical guide tube and the fixation protrusion at one end and by the other end of the ground connector and the third part at the other end, and the signal pin and the ground coupler are isolated from each other by the insulator and air in between and impedance matched.

[11] The coaxial connecting system of claim 1, wherein the ground coupler comprises: a ground connector connected to the ground conductor of the coaxial cable and coupled with the insulator by means of shrink fit; and a ground contact elongated from the ground connector and inserted into the jack hole while tightly contacting with the inner wall of the jack hole.

[12] The coaxial connecting system of claim 11, wherein the signal pin comprises: a first part which is electrically contacting with the signal pad; a second part which a diameter larger than that of the first part and is connected to the first part at one end and has a insertion hole formed at the other end for receiving the signal conductor of the coaxial cable.

[13] The coaxial connecting system of claim 12, wherein the insulator is inserted into the ground coupler while surrounding the second part of the signal pin and fixed by means of shrink fit, and the signal pin and the ground coupler are isolated from each other by the insulator and air in between and impedance matched.

[14] A coaxial connecting device for electrically connecting a coaxial cable to a printed circuit board, comprising: a signal pin for electrically connecting a signal conductor of the coaxial cable to a signal pad of the printed circuit board; a ground coupler for electrically connecting a ground conductor of the coaxial cable to a ground pad of the printed circuit board; a insulator surrounding a part of the signal pin for electrically isolating the ground coupler and the signal pin from each other and maintaining the ground coupler and the signal pin in a coaxial manner.

[15] The coaxial connecting device of claim 14, wherein the ground coupler comprises: a ground connector tightly surrounding the ground conductor exposed at an end of the coaxial cable; and a cylindrical guide tube connected to the ground connector and surrounding the signal pin while maintaining a predetermined distance from the signal pin, wherein the ground connector is electrically connected to the ground conductor of the coaxial cable and has a first protrusion formed around an outer surface cir- cumferentially for fixing the cylindrical guide tube.

[16] The coaxial connecting device of claim 15, wherein the cylindrical guide tube comprises: a fixing part coupled with the ground connector by means of shrink fit and fixed by the first protrusion and having a recess with a shape of "D" formed on an inner wall; and a ground contact elongated from the fixing part and contacting the ground pad by elastic force.

[17] The coaxial connecting device of claim 16, wherein the ground contact has at least one slit formed in a longitudinal direction.

[18] The coaxial connecting device of claim 16, wherein the signal pin is a spring probe pin.

[19] The coaxial connecting device of claim 18, wherein the signal pin comprises: a first part which is elastically contacting with the signal pad; a second part longitudinally connected to a proximal end of the first part and having a fixation protrusion for limiting movement of the insulator, the second part being formed with a diameter larger than that of the first part such that the first part reciprocates within the second part; and a third part longitudinally connected to the second part at one end and having an insertion hole formed at the other end for receiving the signal conductor, the third part having a diameter larger than that of the second part.

[20] The coaxial connecting device of claim 19, wherein the insulator is fixed by the recess of the cylindrical guide tube and the fixation protrusion at one end and by the other end of the ground connector and the third part at the other end, and the signal pin and the ground coupler are isolated from each other by the insulator and air in between and impedance matched.

[21] The coaxial connecting device of claim 14, wherein the ground coupler comprises: a ground connector connected to the ground conductor of the coaxial cable and coupled with the insulator by means of shrink fit; and a ground contact elongated from the ground connector and contacted with the coupling connector by elastic force.

[22] The coaxial connecting device of claim 21, wherein the signal pin comprises: a first part which is electrically contacting with the signal pad; a second part which a diameter larger than that of the first part and is connected to the first part at one end and has a insertion hole formed at the other end for receiving the signal conductor of the coaxial cable.

[23] The coaxial connecting device of claim 22, wherein the insulator is inserted into the ground coupler while surrounding the second part of the signal pin and fixed by means of shrink fit, and the signal pin and the ground coupler are isolated from each other by the insulator and air in between and impedance matched.

[24] A coaxial connecting system for electrically contacting a test equipment to a printed circuit board to be tested through at least one coaxial cable, comprising: a coupling connector for making an electrical ground connection between the coaxial cable and the printed circuit board, the coupling connector having more than one jack hole; and at least one coaxial connecting device penetrating each jack hole for establishing the electrical ground connection and a signal connection between the coaxial cable and the printed circuit board.

[25] The coaxial connecting system of claim 24, wherein the coupling connector comprises: a jack having the jack hole which is connected to a signal pin of the coaxial connecting device connected to a signal conductor of the coaxial cable and a cylindrical guide tube of the coaxial connecting device connected to a ground conductor of the coaxial cable, and electrically connects the signal pin to a ground pad of the printed circuit board and the cylindrical guide tube to a signal pad of the printed circuit board ;and a jack interposer which is located between the jack and the printed circuit board for making an electrical connection between the jack and the circuit board.

[26] The coaxial connecting system of claim 25, wherein the jack is provided with the jack hole having a stepped recess forming an inlet for facilitating reception of the coaxial connecting device and comprises: a jack pin connected to the signal pad of the printed circuit board at one end and connected to the signal pin of the coaxial connecting device at the other end ; and a jack isolator surrounding the jack pin in the jack hole for isolating the jack pin against the inner wall of the jack hole the end of the cylindrical guide tube electrically contacting with the inner wall of the jack hole for making the electrical connection between the ground conductor of the coaxial cable and the ground pad of the printed circuit board.

[27] The coaxial connecting system of claim 26, wherein the stepped recesses of adjacent jack holes are formed with different depths for distributing vertical pressure generated when the end of the cylindrical guide tubes are inserted into respective jack holes.

[28] The coaxial connecting system of claim 25, wherein the jack interposer is provided with at least one interposer hole corresponding to the jack hole and having a plurality of teeth formed along an inner wall of the interposer hole, the teeth being alternately bent up and down.

[29] The coaxial connecting system of claim 4, wherein the jack holes have stepped recesses formed with different depths for distributing vertical pressure generated when the end of the cylindrical guide tubes are inserted into respective jack holes.