JP2011034858A - End-processed coaxial cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an end-processed coaxial cable attaining miniaturization and reduction in size, superior in adhesive strength even when the coaxial cable has a small diameter or a pitch distance between the cables is narrow, and preventing thermal damages to the surface of a dielectric layer and a deterioration of high-frequency characteristics. <P>SOLUTION: In an end-processed coaxial cable, an end of a group (1) of coaxial cables is cut, at least at one end of a coaxial cable assembly including the group (1) of coaxial cables arranged in parallel at a predetermined pitch, and each central conductor (4) and an end of each shielding layer (2) of the group of coaxial cables are connected by soldering with a connection substrate (9) via a ground bar (8). While the ground bar (8) is brought into surface contact with a ground pattern (10) on the connecting substrate (9), a solder (5) is poured through a plurality of solder injection holes (12), formed in the ground pattern (10) on the rear surface of the connection substrate (9) and are connected by soldering the ground bar (8) with the ground pattern (10). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a terminal processing cable suitable for applications such as a mobile phone, a small communication device terminal, a liquid crystal display of a personal computer, and an internal wiring of an electronic device. In particular, it relates to a terminal-processed ultrafine coaxial cable.

  In recent years, along with the widespread use of various small electronic devices such as personal computers, it has been required to wire coaxial cable groups in a narrow space so as to match characteristic impedance with a high-precision pitch. In order to cope with this requirement, it is necessary to connect the center conductor of each coaxial cable to the connector terminal of a predetermined pitch or the circuit of the board with the upper surface of the positive ground bar (8). For this reason, a crimping connection is collectively performed using a flat cable in which coaxial cable groups juxtaposed at a predetermined pitch are bonded together with a tape. However, this method has a problem that the strength of the connection portion decreases as the cable becomes thinner.

In order to solve this problem, a method has been proposed in which terminal processing is performed with a center conductor, a dielectric layer, and a shield layer of a predetermined length sequentially exposed from the cutting end of each cable of the micro coaxial cable group. .
The shape of the final product in this proposal is shown in FIG. Here, with the exposed shield layer (2) sandwiched between the dielectric layer (3) and the ground bar (8), the solder (5) is applied to the ground pattern (10) provided on the connection substrate (9). And the exposed center conductor (4) is solder-connected to a center conductor connection pattern (corresponding to (11) in the figure described later) provided on the connection board (9). ing. When soldering each shield layer (2) and ground bar (8), solder fixing portions (8a) provided at both ends of the ground bar (8), and substantially the middle portion of the ground bar (8) The soldering iron is pressed from the upper ground bar (8) of the gap (S) portion of the coaxial cable group provided to the upper side until the upper ground bar (8) and the lower ground bar (8) come into contact with each other. ) And the ground pattern (10).

That is, in this method, the length of the ground bar (8) is extended from the usual length, and solder fixing portions (8a) bent sideways are provided at both ends, or are aligned with the positions of the extended solder fixing portions (8a). Therefore, the length dimension of the ground pattern (10) provided on the connection board (9) also needs to be extended in the width direction, and further, a gap for applying a soldering iron to substantially the middle part of the ground bar (8). Since S is provided, the width direction is inevitably widened, and there is a limit in reducing the size of the final product including the connection substrate (9) in the width direction.
Further, in this method, the places where the ground bar (8) and the ground pattern (10) are solder-connected are the three places of the both ends and the middle of the ground bar (8), and the solder (5) is attached. The area of the pattern is small, and a substantially line contact state is obtained. For this reason, in the case of lead-free solder having poor flowability, a situation occurs in which the solder (5) does not reach the ground pattern (10) at the bottom of the ground bar (8) and the dielectric layer (3). Accordingly, there is a portion where no solder (5) is attached. As a result, in addition to the problem of insufficient adhesive strength, the problem that a gap is generated between the bottom of the dielectric layer (3) and the ground pattern (10) is caused. .
Furthermore, since the soldering iron contacts the dielectric layer (3) or comes close to the dielectric layer (3), the dielectric layer (3) is thermally damaged. This damage causes a serious situation that the central conductor (4) is exposed in the case of a micro coaxial cable having a thin dielectric layer (3). In addition, heat at the time of solder heating is transferred to the dielectric layer (3) and changes the dielectric characteristics of the dielectric layer (3), which deteriorates the high-frequency characteristics originally required for the coaxial cable. These problems are more serious nowadays when the outer diameter of the coaxial cable is increasingly reduced and the pitch between the cables is also smaller.

  Therefore, an object of the present invention is to provide a terminal-processed coaxial cable that can be reduced in size and reduced, and has excellent adhesive strength even when the coaxial cable has a small diameter or a narrow pitch between the cables. Furthermore, it is providing the terminal processing coaxial cable which can prevent the thermal damage of the dielectric material layer surface, and deterioration of a high frequency characteristic.

  According to the present inventors, the coaxial cable group is aligned at the tip at at least one end of the coaxial cable body in which the coaxial cable group is aligned at a predetermined pitch, and the central conductors of the coaxial cable group and the tip portions of the shield layers In the terminal-processed coaxial cable in which the ground bar connected to is connected to the connection board by soldering, a plurality of solder injection holes are provided along the longitudinal direction of the ground pattern provided on the connection board. A featured end-processed coaxial cable is provided.

According to the present invention employing the above-described configuration, the following remarkable actions and effects can be achieved.
a. Since solder is flown from the solder injection hole on the back of the connection board, it is not necessary to provide a gap for solder to flow in the solder connection part at both ends of the ground bar and the middle part of the ground bar for solder connection. Therefore, the cable width direction can be reduced in size and reduced.
b. Since the solder is flowed and connected through the plurality of solder injection holes, the solder adheres uniformly on the ground bar and the solder attachment area increases, so that the solder connection strength is improved as compared with the conventional method in which the solder connection is performed at three points.
c. When soldering, solder is injected from the back of the board where the cable is not attached through the through hole, so soldering jigs such as soldering iron do not touch the dielectric of the cable or the ground bar directly. It is possible to prevent thermal damage of the dielectric layer, deterioration of high frequency characteristics, and thermal deformation of the ground bar.
d. Since the solder injection hole is not related to the position and pitch of the cable, it can be handled even when the micro-coaxial cable or the pitch of the cable is narrow.

It is a top view which shows an example of the terminal process coaxial cable of this invention. It is the elements on larger scale of FIG. It is AA sectional drawing of FIG. 2 which shows an example of the terminal processing coaxial cable of this invention. It is a figure which shows an example of the connection board | substrate in this invention, FIG. 4a is the surface view of the board | substrate, FIG. 4b is the back view of the board | substrate. It is sectional drawing which shows an example of the conventional terminal processing coaxial cable.

Hereinafter, the present invention will be described in detail with reference to the drawings with respect to an example in which a processed coaxial cable product in which a horizontally wound shield layer composed of a shield wire bundle is connected to a ground bar is soldered to a connection substrate.
1 and 2, the coaxial cable (1) group is aligned at a predetermined pitch, and one end thereof is cut to align the tips. In each cable (1), the center conductor (4), the dielectric layer (3), and the shield layer (2) having a predetermined length are sequentially exposed starting from the cut end.
Furthermore, the ground bar (8) to which the tip of each shield layer (2) of the coaxial cable group (1) is connected is solder-connected to the ground pattern (10) of the connection substrate (9). 8) and the ground pattern (10) are in surface contact with each other, and a plurality of solder injection holes (12) are provided along the longitudinal direction of the ground pattern (10). On the other hand, the exposed central conductor (4) of the coaxial cable group (1) is connected to the central conductor connection pattern (11) of the connection board (9). Further, (6) is a removal start point of the sheath (7) shown in FIG.

What is characteristic of the present invention is that a plurality of solder injection holes (12) are provided in the connection substrate (9) as shown in FIG. 4, and five solder injection holes (12) are provided in FIG. 1 (FIG. 2). ing. The solder injection hole (12) is preferably a conductive through hole that is connected to the ground pattern (10) of the connection substrate (9) in order to improve the flowability of the solder (5).
By doing so, the solder (5) can be uniformly injected into the entire ground pattern (10) from the back side of the board opposite to the component side of the connection board (9). Adhesive strength is improved. Moreover, as in the prior art, the gap (S of the coaxial cable group for flowing the solder (5a) provided in the solder fixing part (8a) and the substantially middle part of the ground bar (8) at both ends of the ground bar (8). ) Can be reduced in size and reduced in the width direction.
Further, since the heating tool such as a soldering iron does not directly touch the dielectric (3) or the ground bar (8), the dielectric layer (3) is not damaged even in the case of the micro coaxial cable. Deterioration of high frequency characteristics can be prevented; furthermore, soldering is facilitated even in the case of a very narrow pitch coaxial cable that does not contain solder iron.

More specifically, regarding the solder injection hole (12), it is desirable to provide a plurality of locations along the longitudinal direction of the ground pattern (10). Further, preferably, all the solder injection holes (12) are provided so as to be located inside the ground bar (8) connected to the ground pattern (10). This is because if all the solder injection holes (12) are provided so as to be located inside the ground bar (8), the injected solder can be prevented from protruding toward the ground pattern (10), and the amount of solder can be minimized. This is because the ground bar (8) can be reliably connected to the ground pattern (10), which is efficient.
Although the number of solder injection holes (12) depends on the length of the ground pattern (10), it is better to increase the number of solders evenly on the ground bar (8). Just choose.
The lower limit of the hole diameter of the solder injection hole (12) is determined based on the fluidity or fluidity of the solder, while the upper limit is used for utilizing the effect of sucking up the solder by the capillary phenomenon, or the ground bar (8). The width and the solder protrusion amount are determined, and it is preferably 0.3 mm to 0.8 mm. Further, the pitch of the solder injection holes (12) is preferably 1.5 mm to 10 mm. The lower limit value is related to the width of the cable group (1), that is, the length of the ground bar (8). If the amount is too small, the solder (5) uniformly adheres to the ground bar (8) and the ground pattern (10). Disappears, causing poor adhesion. On the contrary, the upper limit value is determined from the number of man-hours for solder injection.
Further, the thickness of the connection substrate (9) is preferably 0.3 mm to 0.8 mm in consideration of the strength of the connection substrate and the size reduction in the thickness direction, the amount of solder injection and the injection time.
Here, the connection board (9) means various connections such as a circuit board when directly connecting to a circuit board such as a mobile phone or a relay circuit board when connecting indirectly to a circuit board such as a mobile phone. It shall refer to the substrate for responding to the condition.

Next, the remaining configuration of the coaxial cable used in the present invention will be described.
As the coaxial cable (1), a thinned or ultrathinned cable having an outer diameter of 0.2 mm to 1.5 mm is preferably used. At this time, as the central conductor (4), the outer diameter is usually a single wire of a conductive wire made of tin-containing copper alloy, silver-copper alloy wire, annealed copper wire or the like having a diameter of 0.03 to 0.15 mm, or twisted together. Is preferably a thin wire of 0.06 mm to 0.5 mm. The dielectric layer covering the central conductor (4) is made of any synthetic resin having insulation properties, such as polyethylene or fluororesin. In terms of the signal transmission characteristics of the coaxial cable and the heat resistance when soldering, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polytetra A fluororesin such as fluoroethylene (PTFE) is preferably used. This dielectric layer (3) may be adjusted to a thickness of 0.05 mm to 0.5 mm in consideration of its strength and the outer dimensions of the coaxial cable.

As the shield layer (2) covered with the dielectric layer (3), horizontal winding, braiding, longitudinal attachment, etc., such as a copper alloy wire containing tin, a silver copper alloy wire, or an annealed copper wire are usually used. Among these, a horizontal winding that can easily sort the bundle of shield wires (2a) is preferably used. The wire diameter of each shield wire (2a) constituting the shield layer (2) is 0.01 mm to less than the unevenness of the shield layer, and considering the ease of sorting work and mechanical strength at the same time. What is necessary is just to set suitably from the range of 0.1 mm.
Furthermore, a polyester film, a fluororesin, or the like is used as a material constituting the sheath (7).

In addition, after the above-described plurality of coaxial cables are subjected to terminal processing, the shield layer (2) of the coaxial cable (1) group is soldered to two ground bars (8) to form a coaxial cable intermediate processed product. However, the ground bar (8) may be a conductive thin plate, and may be appropriately selected from metals such as copper, tin, and zinc. The ground bar (8) may have a width of about 0.3 mm to 1.5 mm and a thickness of about 0.05 mm to 0.1 mm.

Next, the coaxial cable intermediate processed product in which the two upper and lower ground bars (8) are solder-connected is connected to the connection board (9). At that time, the connection board (9) Examples of the material include various materials such as glass epoxy, paper epoxy, bakelite, and polyimide, but a thin and strong glass epoxy substrate or polyimide is particularly preferable. The thickness of the ground pattern (10) provided on the connection board (9) is in consideration of the strength, etc., the thickness is 0.01 mm to 0.1 mm, and the width is in consideration of the amount of solder adhesion and the connection strength. 0.2 mm to 5 mm is a preferable range. On the other hand, the thickness of the central conductor connection pattern (11) is preferably 0.01 mm to 0.1 mm, the width is 0.15 mm to 1.0 mm, and the pitch is 0.2 mm to 1.0 mm in consideration of the connection strength and the like. It is a range. As the material of the pattern, a metal foil made of a metal such as tin-plated or solder-plated copper is commonly used.
In addition, for the convenience of explanation, the example of the terminal processing is shown as one end, but it goes without saying that both terminal processing may be performed.

Hereinafter, an aspect of manufacturing the terminal-processed coaxial cable of the present invention will be briefly described.
First, one end side of the coaxial cable body formed by aligning the coaxial cable (1) group is cut and subjected to tip alignment processing. At this time, if the portion from which the sheath (7) is to be removed is fixed at a predetermined pitch by a tip aligning jig such as an adhesive tape, the subsequent operations are facilitated.
However, this processing is usually performed when the ends of the coaxial cable (1) group are uneven. Although it is slightly inferior in efficiency, the cable group with the aligned tips from the beginning is not intentionally cut.
First, the sheath (7) is cut with a carbon dioxide laser at two locations over a width of 2 mm to 3 mm at the sheath removal start point (6). Next, these two cuts are shifted to the terminal side by a width of about 2 mm to 3 mm to form a semi-strip in which the shield layer (2) is exposed.
Next, the shield layer (2) exposed by the YAG laser is cut.
At this time, when a metal vapor deposition film is provided on the outer periphery of a horizontal winding or braid such as a copper alloy wire containing tin or an annealed copper wire as the shield layer (2), this metal vapor deposition film is regarded as a sheath (7). , Removed with sheath (7).
Next, the cut shield layer (2) and the sheath (7) formed with the semi-strip are pulled out. Then, two upper and lower ground bars (8) are soldered to the upper and lower portions of the exposed shield layer (2).

  Next, laser light is irradiated to a predetermined length from the cut end surface of the dielectric layer (3) to make a cut, and the portion of the dielectric layer (3) having the predetermined length is directed toward the tip side of each cable. Remove while shifting. As a result, a coaxial cable intermediate processed product in which the center conductor (4) is exposed at a desired length is completed at each cable end.

Next, the ground bar (8) of the intermediate product of the coaxial cable is brought into contact with the ground pattern (10) provided on the connection board (9). In this state, the cable is temporarily fixed using a temporary fixing jig.
At this time, it is desirable to align and contact the ground bar (8) so that the entire ground bar (8) is located inside the ground pattern (10).
Next, the ground bar (8) is soldered to the ground pattern (10) on the connection substrate (9) by flowing the solder (5) through the solder injection holes (12) at a plurality of locations on the connection substrate (9). The As a solder injection method, there is a method of injecting molten solder into the solder injection hole (12) with an injection jig or immersing a substrate in a solder bath and sucking up the solder using a capillary phenomenon.
Then, after the solder has cooled sufficiently, remove the temporary fixing jig.
Finally, each center conductor (4) is soldered to the center conductor connection pattern (11) provided on the connection board (9), and the terminal-processed coaxial cable (1) of the present invention is completed.

The outer periphery of the center conductor (4) having an outer diameter of 0.063 mm formed by twisting seven silver-plated copper alloy wires having a diameter of 0.021 mm is covered with a PFA resin having a thickness of 0.031 mm as a dielectric layer (3). did. Next, a tin-plated copper alloy wire having an element wire diameter of 0.02 mm is laterally wound around the outer periphery of the dielectric layer (3) to form a shield layer (2). 03 mm PFA resin was extrusion coated to produce a coaxial cable (1) having a cable length of 70 mm and an outer diameter of 0.225 mm. Next, 34 coaxial cables (1) were arranged in parallel at a pitch of 0.25 mm to produce a coaxial cable bundle (1).
Next, one end of the coaxial cable bundle (1) was cut to align the tips of the cable group. Further, a position 12 mm from the cutting end of each cable, that is, the sheath removal start point (6) is irradiated with carbon dioxide laser light to make a cut, and then the sheath (7) is connected to the cutting end of the cable bundle (1). The shield layer (2) was exposed by pulling in the direction and removing. The exposed length of the shield layer (2) remaining at this time was 0.45 mm.

Next, a ground bar (8) made of a thin copper plate having a thickness of 0.05 mm and a width of 0.7 mm is soldered to the upper and lower portions of the exposed shield layer (2).
Thereafter, 34 linear portions composed of the exposed dielectric layer (3) and the shield layer (2) were aligned again and adhered to the adhesive tape over the entire surface at a pitch of 0.25 mm. Subsequently, the dielectric layer (3) was cut by irradiating carbon dioxide laser light at a position of 0.45 mm from each cutting terminal. Thereafter, while pulling out the dielectric layer (3), the 0.45 mm long dielectric layer (3) group was removed at a time to expose the central conductor (4). As a result, a coaxial cable intermediate processed product of the center conductor (4) in which the exposed length of each cable soldered to the ground bar (8) was 0.45 mm was obtained.

Next, a glass epoxy substrate having a width of 10 mm, a length of 11 mm, and a thickness of 0.7 mm was used as the connection substrate (9) for soldering the ground bar (8) of the coaxial cable intermediate processed product. Also, the width of the ground pattern (10) on the connection substrate (9) is 8.8 mm, the length is 0.9 mm, the width of the central conductor connection pattern (11) is 0.12 mm, the length is 0.45 mm, and the thickness The thickness was 0.05 mm. On the ground pattern (10), five solder injection holes (12) made of copper foil through holes having a pitch of 1.7 mm and a hole diameter of 0.5 mm are provided. These patterns are obtained by performing solder plating on copper foil.
Next, the ground bar (8) is fixed with a temporary fixing jig in a state where the ground bar (8) is positioned and brought into contact with the inside of the ground pattern (10).
Thereafter, the solder (5) is injected by the solder injection jig into the five solder injection holes (12) from the back surface of the connection substrate (9), and the ground bar (8) and the ground pattern (10) are connected by soldering. To do. Then, when it has cooled sufficiently, the temporary fixing jig is removed.
Finally, each exposed center conductor (4) was soldered to a center conductor connection pattern (11) provided on the connection substrate (9) to complete the end-processed coaxial cable of the present invention.

"Comparative example"
The coaxial cable was the same as in the example, and 17 coaxial cables (1) were arranged in parallel at a pitch of 0.25 mm, and two coaxial cable bundles (1) were prepared in the same manner as in the example.
Next, as the connection substrate (9), the width of the ground pattern (10) is 11 mm, the width of the central conductor connection pattern (11) is 0.12 mm, the length is 0.45 mm, the widths at both ends are 9 mm, Except for providing a 1 mm space (S), the dimensions and materials were the same as in the examples.
The ground bar (8) was a ground bar (8) made of a copper plate having a width of 0.7 mm, a length of 10.2 mm, and a thickness of 0.05 mm.
Next, with the ground bar (8) placed on the dielectric layer (3), the terminal-processed coaxial cable is completed by flowing solder to both ends (8a) of the ground bar (8) and the central side. did.

When the example and the comparative example were compared, the width of the cable bundle could be shortened by about 2 mm.
In addition, it was confirmed that in the example, the solder was evenly bonded and the adhesive strength was excellent. Furthermore, in the cable of this example, it was confirmed that the dielectric was not damaged at all.

  The terminal-processed coaxial cable of the present invention can be applied to a very small diameter cable and a very narrow pitch flat cable, and is particularly useful for a mobile phone, a personal computer, a PDA (portable data terminal) or a medical device.

1 Coaxial cable 2 Shield layer 2a Shield wire 3 Dielectric layer 4 Center conductor
5 Solder 6 Sheath removal start point 7 Sheath 8 Ground bar 9 Connection board 10 Ground pattern 11 Center conductor connection pattern 12 Solder injection hole

Claims (6)

A ground bar in which the coaxial cable group is aligned at the tip at at least one end of a coaxial cable body in which the coaxial cable group is aligned at a predetermined pitch, and the central conductor of the coaxial cable group and the tip of each shield layer are connected. A terminal-processed coaxial cable in which a plurality of solder injection holes are provided along the longitudinal direction of the ground pattern provided on the connection board. cable. The terminal-processed coaxial cable according to claim 1, wherein the solder injection hole is a conductive through hole connected to the ground pattern provided in the connection substrate. The terminal-processed coaxial cable according to claim 1 or 2, wherein all of the solder injection holes are located inside the ground bar connected to the ground pattern. The terminal-processed coaxial cable according to any one of claims 1 to 3, wherein a diameter of the solder injection hole is 0.3 mm to 0.8 mm. The terminal-processed coaxial cable according to any one of claims 1 to 4, wherein a pitch of the solder injection holes is 1.5 mm to 10 mm. The terminal-processed coaxial cable according to any one of claims 1 to 5, wherein a thickness of the connection substrate is 0.3 mm to 0.8 mm.

Images