JP2002203618A - Coaxial cable for board connection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coaxial cable for a board connection, which, compact and with excellent strength, is in compliance in characteristics impedance with a wiring board, by restraining fluctuation of characteristics impedance at a connection terminal. SOLUTION: A signal terminal 38 is composed of an inner conductor 22 led to protrude from the tip an insulating body 23, and at same time, a contact- type grounding terminal 33 is so composed as to be exposed from a tip face 32 of a cover member 27. Further, a gap part 35 is formed around the insulating body 23, and then, connection between the grounding terminal and a wiring board is performed by a contact of the grounding terminal 33 with a grounding circuit of the wiring board 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coaxial cable for connecting a board, and more particularly, to suppressing the variation of the characteristic impedance at a connection terminal so as to achieve the matching of the characteristic impedance with a wiring board. The present invention relates to a coaxial cable for connecting a board having strength.

[0002]

2. Description of the Related Art In a semiconductor test apparatus, a signal is transmitted to a wiring board serving as an interface with a device under test by connecting a coaxial cable to a through hole of the wiring board and transmitting a signal from the cable. Is adopted. Usually, a through-hole for signal and a through-hole for ground are formed on the wiring board at an interval of 2.54 mm, and a plurality of channels having these pairs as one channel are formed. A coaxial cable for board connection having a pair of pin terminals at the tip is connected to each channel, and a predetermined test is performed based on this configuration.

FIG. 2 shows a configuration of a coaxial cable for connecting a board, which is frequently used in the related art, and a relationship between the cable and a wiring board. In FIG. 1, reference numeral 1 denotes a coaxial cable in which an inner conductor 2, an insulator 3, and an outer conductor 4 are respectively exposed by a predetermined length. A signal terminal 5 and a ground terminal 6 are attached to the exposed inner conductor 2 and outer conductor 4, respectively, and the periphery thereof is covered with a cover member 7 made of resin mold. Reference numeral 8 denotes a cable jacket.

Reference numeral 9 denotes a wiring board, 10 denotes a through hole as a signal electrode formed through the board 9, and 11 denotes a through hole as a ground electrode similarly formed. The through holes 10 and 11 have a distance of 2.54 mm from each other, and although not shown, the wiring board 9 is formed with a large number of channels each of which is a set, and a coaxial cable for board connection is formed. C is the terminal 5 at the tip
And 6 are inserted into through holes 10 and 11 to connect to each channel.

Incidentally, the characteristic impedance of the coaxial cable 1 and the wiring board 9 used in the above connection configuration is usually designed to the same level. However, according to the board connecting coaxial cable C having the illustrated configuration, the arrangement of the inner conductor 2 and the outer conductor 4 is changed from the portion of the coaxial cable 1 to a portion parallel to the two wires including the terminals 5 and 6. Further, since the material and shape are also changed in this process, the characteristic impedance often increases due to these instability factors, and as a result, the characteristic impedance mismatches with the wiring board. . The characteristic impedance mismatch causes a reflection phenomenon at the mismatched portion, and thus acts to reduce the transmission fidelity due to the adverse effect on the transmission signal due to the reflection.

Japanese Patent Application No. 2000-108 discloses a coaxial cable for connecting a board which eliminates the cause of instability of the internal structure.
No. 109 has been proposed. FIG. 3 shows the configuration.
The feature of this coaxial cable for connecting a board is that the insulator 3 is protruded to the position of the front end face 13 of the cover member 7 including the insulating base material 12 formed by resin molding, and the inner conductor 2 is protruded from the front end of the insulator 3. The signal terminal 5
And a configuration in which the ground terminal 6 is attached to the outer conductor 4 which is converged and bent laterally at a right angle. The insulating base member 12 forms the front end surface 13 of the cover member 7 and the vicinity thereof, and the internal conductor 2 (signal terminal 5) and the ground terminal 6 are inserted through the insulating base member 12. It projects through holes 14 and 15.

According to the coaxial cable C for connecting a board having this configuration, since the insulator 3 is protruded to the position of the distal end face 13 of the cover member 7, the variation of the characteristic impedance at the connection terminal with the wiring board 9 is reduced. Can be suppressed and therefore
As a result, impedance matching with the wiring board 9 can be achieved.

[0008] However, although the coaxial cable for connecting a substrate shown in FIG. 3 has improved performance as described above, it still has the following problems strictly. (1) When the signal terminal 5 and the ground terminal 6 are connected to the signal through hole 10 and the ground through hole 11 of the wiring board 9, the through holes 10 and 11
The addition of the capacitance between them changes the characteristic impedance, causing a mismatch of the characteristic impedance with the wiring board 9.

(2) Since the exposed insulator 3 is covered by the cover member 7 including the insulating base member 12, the capacitance of these components acts on the insulator 3,
For this reason, the characteristic impedance of the coaxial cable C changes, causing a mismatch of the characteristic impedance with the wiring board 9.

(3) Since both the signal terminal 5 and the ground terminal 6 are formed and the cover member 7 is provided, the connection space to the wiring board 9 is increased, preventing high-density mounting.

FIG. 4 shows a configuration of a coaxial cable for connecting a board which can solve the above problems (1) to (3). It is disclosed in Japanese Patent Application Laid-Open No. 2000-134783, and is characterized in that a drain wire is used as a ground terminal. FIG. 4A shows the configuration of the coaxial cable 1 used, in which a drain wire 16 is vertically arranged between the insulator 3 and the outer conductor 4.

As shown in FIG. 4 (b), the coaxial cable C for board connection is configured such that the inner conductor 2, the insulator 3, the outer conductor 4 and the jacket 8 are each stripped by a predetermined length. The inner conductor 2 is used as the signal terminal 5, and the outer conductor 4 formed by tape-like winding is fixed on the insulator 3 by soldering 17, and the insulator 3 and the outer conductor 4 are fixed. Drain wire 16 drawn out between
Are used as ground terminals 6. Reference numeral 18 denotes a heat-shrinkable tube fitted to the cable end.

According to the coaxial cable for board connection having the above-described structure, the drain wire 16 is used as the ground terminal 5, so that the terminal structure is simple and small, and the cover member as shown in FIGS. 7 does not affect the capacitance. Therefore, according to this cable, the problems (2) and (3) described above can be solved, and the cable is evaluated as a useful coaxial cable for board connection.

[0014]

However, according to this type of conventional coaxial cable for connecting a board, the above-mentioned (1)
Is still unresolved, and since the structure is insufficient in strength, there is a possibility that the structure may be broken during the connection to the wiring board by the action of an external force such as hooking. The latter problem is likely to occur frequently when the density of mounting on a wiring board is increased, and thus needs to be emphasized.

Accordingly, it is an object of the present invention to achieve the matching of the characteristic impedance with the wiring board by suppressing the fluctuation of the characteristic impedance including the above-mentioned (1), and furthermore, the board connection having a small size and excellent strength. To provide a coaxial cable.

[0016]

According to the present invention, in order to achieve the above object, an insulator, an outer conductor and a jacket are sequentially formed on an inner conductor, and a signal terminal and a ground terminal provided at the tip are provided. In a coaxial cable for board connection used by connecting a terminal to a predetermined portion of a wiring board, the coaxial cable is composed of an inner conductor protruding from a tip of an insulator, and is inserted into a through hole of the wiring board to form a predetermined connection portion. A signal terminal to be configured, a ground terminal that is electrically connected to an external conductor, is brought into contact with a ground circuit on the surface of the wiring board, and forms a predetermined connection portion, and is formed from a jacket to a distal end portion of the insulator. A cover member having the signal terminal protruding from the front end surface thereof and exposing the ground terminal, and having a gap formed from the front end surface to the periphery of the front end portion of the insulator. It is to provide a coaxial cable for board connection, characterized in that it comprises.

The above cover member may be entirely formed of a single resin molded body, but it is also useful to form the front end surface in contact with the wiring board and the vicinity thereof with another insulating base material. In this case, as the insulating base material, it is common to have a configuration integrated with the ground terminal and to expose this from the tip end surface, and to have a through hole through which the insulator of the coaxial cable is inserted. The through-hole is provided with an internal dimension necessary for forming the above-mentioned gap between the through-hole and the insulator.

The above structure incorporating the insulating base material is as follows.
The occurrence of inconveniences such as displacement of the ground terminal due to resin flow when forming the cover member or inflow of the resin film onto the ground terminal is prevented, thereby exposing the ground terminal from the front end surface of the cover member. Produces an effect that stabilizes the state. The insulating base material is preferably made of a porous resin molded product having a small relative dielectric constant in order to further stabilize the characteristic impedance. For example, a foam of a fluororesin or PBT (polybutylene terephthalate) resin is applied.

The form of conduction between the external conductor and the ground terminal in the present invention is, for example, when the coaxial cable has a drain wire interposed between the insulator and the external conductor, the drain wire is connected to the ground. The terminal is connected to the terminal, and the external conductor and the ground terminal are electrically connected via the drain wire. In this case, since the internal configuration in the cable terminal portion is stabilized, it is possible to provide a highly useful coaxial cable for connecting a board, which suppresses fluctuations in characteristic impedance.

In the coaxial cable used in the present invention, the inner conductor constituting the signal terminal may be in the form of a single wire or a stranded wire. In the case of a stranded wire, this is formed into a single wire by soldering or the like. It is possible to harden it as a signal terminal. The insulator is made of a resin having a low dielectric constant such as polyethylene or fluororesin, or a porous body obtained by foaming the resin, and is formed by extrusion or tape winding. In addition, the outer conductor is formed by winding a plurality of fine wires, winding the same braid, or winding a metal tape or a resin tape having a metal layer formed on one side, and the outer jacket is made of polyethylene, fluororesin, or the like. .

[0021]

Next, an embodiment of a coaxial cable for connecting a board according to the present invention will be described. In FIG. 1A, reference numeral 21 denotes a coaxial cable, which is constituted by sequentially providing an insulator 23, a drain wire 24, an outer conductor 25, and a jacket 26 on an inner conductor 22. Here, the main specifications of the coaxial cable 21 are as follows. -Inner conductor 22: AWG24-32 stranded wire with silver plating. Insulator 23: Extrusion coating of porous fluororesin. Outer diameter 0.
8 mm External conductor 25: Wound body with a metal layer on the inside made of a resin tape with a metal layer on one side. -Jacket 26: Extrusion coating of fluororesin. Outer diameter 1.4mm. Characteristic impedance between the inner conductor 22 and the outer conductor 25: 50 ± 2Ω.

Reference numeral 27 denotes a cover member formed by molding a PBT resin or the like, and reference numeral 28 denotes an insulating base material provided at the tip of the cover member 27. The first hole 29 and the second hole 3 are provided.
A combination of 0 has a through hole 31 for inserting the insulator 23. The cover member 27 is formed from the outer cover 26 to the periphery of the distal end portion of the insulator 23 by including the insulating base material 28 as a constituent member thereof, and further includes a distal end face 32 formed of the insulating base material 28. ing.

Reference numeral 33 denotes a ground terminal formed so as to straddle both surfaces of the insulating base member 28 and exposing a terminal surface 34 from the distal end surface 32 of the cover member 27. The ground terminal 33 made of solder-plated phosphor bronze having a thickness of 0.4 mm and a width of 2.4 mm is integrated with the insulating base material 28 such that the effective length L of the terminal surface 34 is 4 mm. Further, a drain wire 24 bent in a direction orthogonal to the insulator 23 is connected by soldering.

Therefore, the outer conductor 25 in this example is
It is electrically connected to the ground terminal 33 via the drain wire 24. Reference numeral 35 denotes a gap formed around the insulator 23 having an outer diameter of 0.8 mm by giving the first hole 29 and the second hole 30 inner diameters of 1.2 mm and 1.4 mm, respectively. 27 is formed from the distal end surface 32 to the distal end of the insulator 23.

FIG. 1B shows a structure in which the coaxial cable C for board connection having the above-described configuration is connected to a wiring board. In the figure, 36 is a wiring board, 37 is a wiring board 36
Shows a through-hole as a signal electrode of which the internal conductor 22, that is, the signal terminal 38 of the coaxial cable C for board connection is inserted and connected. On the other hand, the wiring board 3
The ground electrode 6 is constituted by a ground circuit on the surface of the substrate 36 (not shown), and the terminal 33 is brought into contact with the terminal surface 34 of the ground terminal 33 of the coaxial cable C for substrate connection. A predetermined connection portion is formed between them.

The through-hole 37 and the ground electrode form one channel by forming a pair with each other, and a large number of channels are formed on the wiring board 36 by these sets. Will be connected. In the figure, 39 and 4
Numeral 0 indicates the solder that has been supplied and fixed to fix the connection between the signal terminal 38 and the ground terminal 33.

According to the coaxial cable for board connection according to the present embodiment configured as described above, the following effects can be obtained, and the problems in FIGS. 2 to 4 can be effectively solved. Can be. (1) Since the signal terminal 38 is formed by the internal conductor 22 protruding from the tip of the insulator 23 and the ground terminal 33 is of a contact type, the configuration can be downsized and the configuration inside the cover member 27 Is not destabilized unlike the conventional two-wire parallel configuration, and therefore, the connection space to the wiring board can be reduced, and the variation of the characteristic impedance is suppressed to achieve the impedance matching with the wiring board 36. be able to.

(2) Since the gap 35 is formed from the distal end face 32 of the cover member 27 to the periphery of the distal end of the insulator 23, the insulator 23 is formed by the static electricity of the cover member 27 (insulating base material 28). It is not affected by the capacitance, and therefore, it is possible to prevent the impedance mismatch with the wiring board 36 due to the change of the characteristic impedance due to the influence.

(3) Since the entire structure is covered by the cover member 27 including the insulating base material 28, the cover member 27 has a sufficient strength. There is no danger of being destroyed.

(4) Connect the ground terminal 33 to the wiring board 36
Since the connection portion is formed by making contact with the ground circuit, there is no need to form a through-hole as a ground electrode on the wiring board 36. Therefore, the signal and ground through holes formed on the wiring board are not required. It is possible to prevent fluctuation of the characteristic impedance due to the addition of the capacitance between the holes and the mismatch of the characteristic impedance with the wiring board due to the fluctuation.

[0031]

As described above, according to the coaxial cable for board connection according to the present invention, the signal terminal is constituted by the internal conductor protruding from the tip of the insulator.
Since a ground terminal is provided to make a predetermined connection by contacting the ground circuit of the wiring board, it is possible to eliminate the instability factor of the internal configuration as in the conventional two-wire parallel configuration, and to reduce the ground potential of the wiring board. Through holes can be dispensed with, and therefore, fluctuations in the characteristic impedance resulting from the unstable internal configuration and the addition of capacitance between the through holes in the wiring board can be effectively suppressed. When connecting to a substrate, the space can be reduced.

Further, since the cover member is formed from the jacket of the coaxial cable to the distal end portion of the insulator, sufficient mechanical strength can be ensured. Since a void is formed around the periphery of the part, the influence of the capacitance of the cover member on the insulator can be prevented, and therefore, the structure is not more likely to be destroyed by the action of an external force as a whole, and thus more stable. It is possible to provide a coaxial cable for board connection having a simplified characteristic impedance.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a coaxial cable for connecting a board according to the present invention, wherein FIG.
Indicates a connection structure to a wiring board.

FIG. 2 is an explanatory view showing a conventional coaxial cable for connecting a board.

FIG. 3 is an explanatory view showing another conventional coaxial cable for connecting a board.

FIGS. 4A and 4B are explanatory views showing another conventional coaxial cable for connecting a board, wherein FIG. 4A is a cross-sectional view of a coaxial cable to be used, and FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Coaxial cable 22 Inner conductor 23 Insulator 24 Drain wire 25 Outer conductor 26 Jacket 27 Cover member 28 Insulation base material 29 First hole 30 Second hole 31 Through hole 32 Tip surface 33 Ground terminal 34 Terminal surface 35 Void portion 36 Wiring board 37 Through hole 38 Signal terminal 39, 40 Solder

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[Procedure amendment]

[Submission date] June 14, 2001 (2001.6.1)
4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

According to the coaxial cable for substrate connection having the above-described structure, the drain wire 16 is used as the ground terminal 6 , so that the terminal structure is simple and small, and the cover member as shown in FIGS. 7 does not affect the capacitance. Therefore, according to this cable, the problems (2) and (3) described above can be solved, and the cable is evaluated as a useful coaxial cable for board connection.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

[0016]

According to the present invention, in order to achieve the above object, an insulator, an outer conductor and a jacket are sequentially formed on an inner conductor, and the inner conductor and the outer conductor are formed on a wiring board. a coaxial cable for board connection which connects said <br/> is composed of the inner conductor which projects from the front end of the insulator, inserted in the sul in the through hole of the wiring board
A signal terminal connected to Horu, the are electrically connected to the outer conductor, the wiring ground terminals grayed Ru is connected to the land for the circuit board, are formed to the tip portions of the insulator from the said outer, the tip A coaxial member for connecting a substrate, wherein the signal terminal protrudes from a surface, the ground terminal is exposed, and a cover member is formed from the front end surface to a periphery of a front end portion of the insulator. Provide cables.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

The form of conduction between the external conductor and the ground terminal in the present invention is, for example, a cable connected to a coaxial cable.
When provided with the rain wires, connect the drain wire to the ground terminal, thereby forming grains through electrically between the external conductor and the ground terminal is employed. In this case, since the internal configuration in the cable terminal portion is stabilized, it is possible to provide a highly useful coaxial cable for connecting a board, which suppresses fluctuations in characteristic impedance.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E077 BB06 BB26 BB31 BB38 CC26 DD01 EE03 FF24 GG07 GG21 GG29 JJ05 JJ10 JJ15 JJ16 JJ24

Claims (4)

[Claims] 1. A board which is formed by sequentially forming an insulator, an outer conductor and a jacket on an inner conductor, and which is used by connecting a signal terminal and a ground terminal provided at a tip to predetermined portions of a wiring board. In the connection coaxial cable, a signal terminal formed of an internal conductor protruding from an end of an insulator and inserted into a through hole of a wiring board to form a predetermined connection portion; A ground terminal which is in contact with the ground circuit on the surface of the surface to form a predetermined connecting portion; and a ground terminal is formed from the outer cover to the tip of the insulator, and the signal terminal protrudes from the tip surface and the ground is formed. A coaxial cable for board connection, comprising: a cover member that exposes terminals for use and that has a gap formed from the distal end surface to the periphery of the distal end of the insulator. 2. The cover member is formed of an insulating base material at and near the distal end surface, and the insulating base material has a through-hole in which the distal end portion of the insulator is inserted to form the gap. 2. The coaxial cable for board connection according to claim 1, wherein the ground terminal is integrated with the ground terminal to expose the ground terminal from the position of the front end surface. 3. The coaxial cable for connecting a board according to claim 2, wherein said insulating base material is formed of a porous resin molded body. 4. The external conductor has a drain wire between itself and the insulator, and is electrically connected to the ground terminal via the drain wire when the drain wire is connected to the ground terminal. The coaxial cable for board connection according to claim 1, characterized in that: