JPH04370608A - Coaxial multi-conductor cable and treating method for its terminal - Google Patents

Abstract

PURPOSE:To allow the compact treatment of a ground-treated portion by forming the primary insulating layer and the secondary insulating layer of each conductor by materials having different melting temperature and by melting and removing the secondary insulating layer only in a soldering bath. CONSTITUTION:The primary insulating layer 3 of a central conductor 4 uses a fluorine-based resin having a melting point of 320 degrees C. A shielding layer is provided on its outside circumference. In addition, the secondary insulating layer 2 comprising polyester having a melting point of 260 degrees C is provided on its outside circumference. The results form a coaxial conductor. And, a plurality of the coaxial conductors are assembled to form a coaxial multi-conductor cable. Next, heat-resistant tapes are wound on the predetermined positions of the cable in spaced relation. These portions are soaked in a 300 degrees C-soldering bath. As the result, the layer 2 of the spaced portions is melted and removed to integrate the shielding layer with solder. This portion is connected to ground. This can perform compact treatment without providing a ground-treated portion with swelling-like projections.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing the terminals of multicore coaxial cables used in measuring instruments, medical equipment, and the like.

0002

2. Description of the Related Art In coaxial cables, it is essential to ground the outer conductor, which is a shield layer, at the terminal end. In the case of a multicore coaxial cable, it is necessary to perform this for each core, and the process shown in FIG. 3 is usually performed. That is, the secondary insulator 2 of each core is removed to expose the shield layer 7, which is pulled out away from the primary insulator, and these many external conductors are connected to the spring 8 ground all at once. .

0003

SUMMARY OF THE INVENTION The conventional terminal processing method described above has the following problems. As shown in the cross-sectional view of Figure 3, the part where the outer conductor is bent forms a knob-like protrusion.
Difficult to process in small diameter and narrow spaces. Also, in order to pull out the shield layer and make it spring as shown in Figure 3, it is necessary to expose about 10 cm of the shield layer, but this may damage the shield when stripping off the secondary insulation layer, causing the shield to break. The core of the part where the shield is pulled out has a non-coaxial structure, causing problems such as the shielding effect disappearing in that part. On the other hand, if the length of the skin strip is shortened, it will be difficult to fold the shield, and there is a risk of a core that is not completely grounded due to poor contact. Further, since the secondary insulating layer is peeled off before the grounding process, there is an inconvenience in terms of wiring connection that it is not possible to differentiate the secondary insulating layer by color.

0004

[Means for solving the problems] The reason why conventional terminal processing causes various problems is that the secondary insulating layer is peeled off and the shield layer is separated from the primary insulating layer and folded all at once. There is a reason for that. Therefore, the present inventors investigated various methods of grounding without stripping the secondary insulating layer or disturbing the structure of the shield layer, and melted and removed the secondary insulating layer using the heat of solder. They came up with a method and completed the present invention.

That is, in the present invention, the primary insulating layer and the secondary insulating layer are composed of insulating layers having different melting temperatures, and the secondary insulating layer is melted while the secondary insulating layer is applied, but the primary insulating layer is The layer is immersed in a solder bath set at a temperature that does not melt, the secondary insulating layer is melted and removed by the heat of the solder, and the shield layer between the secondary insulating layer and the primary insulating layer is integrated with the solder. This is characterized by grounding.

[0006]

[Function] With the method of the present invention, the shielding layer is not damaged because the skin is not stripped, and the shielding layer at the end is not separated, so a good shielding effect can be achieved even in the area beyond the grounding part. You can get it. In addition, since the grounding portion does not become a lump-like protrusion, it is possible to perform the treatment in a small diameter and narrow space portion.

[0007]

[Example] The center conductor diameter is 0.09 mmφ, the primary insulating layer is made of fluorine resin with a melting point of about 320°C, and the outer diameter is 0.24 mm.
A coaxial core was prepared by winding 30 tinned annealed copper wires of 0.03 mm diameter horizontally as a shield layer, and wrapping two polyester tapes with a melting point of about 260° C. as a secondary insulating layer. A total of 98 multicore cables were created using these seven coaxial cores as one structural unit. Next, approximately 100mm from the end of each constituent unit.
As shown in Figure 1, protect two locations with a distance of approximately 5 mm between them with heat-resistant tape (polyimide tape), infiltrate with flux, and then immerse in a solder bath heated to 300°C. Then, the solder and the shield layer were integrated as shown in the sectional view of FIG. 1, and this part was connected to ground. As a result, we were able to perform a compact grounding procedure.

In the embodiment described above, the primary insulating layer has a melting point of about 32
Although 0° C. fluorocarbon resin and a polyester tape having a melting point of about 260° C. were used for the secondary insulating layer, the combination of the primary insulating layer and the secondary insulating layer is not limited to these. 2
Since it is necessary that the primary insulating layer does not melt when the next insulating layer is melted and removed by the heat of solder, the primary insulating layer can be made of fluorocarbon resin with a high melting point, as well as polyether ether ketone, polyphenylene sulfide, and polyamideimide. etc. are suitable. Also, the temperature of the secondary insulating layer is 260°C to 300°C.
It is necessary that the tape can be easily melted and removed with a moderate amount of solder heat, and other than polyester tape, polyolefin, polyvinyl chloride, etc. are suitable.

[0009]

[Effects of the Invention] According to the terminal processing method of the present invention, the portion to be grounded does not become a bump-like protrusion, and compact processing can be performed with minimal increase in cross-sectional area. Further, since the shield layer in the area beyond the processing section also leans back as it was, a good shielding effect can be obtained up to the end. Furthermore, since the ends of the secondary insulating layer are not peeled off, the secondary insulating layer is colored so that it can be easily identified during wiring.

[Brief explanation of drawings]

FIG. 1 shows an example of a sample in which terminal processing of the present invention is implemented.

FIG. 2 shows how the terminal processing of the present invention is implemented.

FIG. 3 shows an example of a sample in which conventional terminal processing is performed.

[Explanation of symbols]

1: Solder 2: Secondary insulation layer 3: Primary insulation layer 4: Center conductor 5: Solder bath 6: Heat resistant tape 7: Horizontal shield layer 8: Horizontal shield rolled up

Claims (3)

[Claims] Claim 1: The primary insulating layer of each core is heated to 260°C to 300°C.
Using an insulating material that does not melt with the heat of soldering at ℃, a shield layer is provided on the outer periphery of the insulating material, and a secondary insulating layer on the outer periphery of the coaxial wire is made of an insulating material that melts with the heat of the solder. A coaxial multi-core cable made up of a collection of books. 2. The coaxial multicore cable of claim 1 is immersed in a solder bath with the secondary insulating layer attached, and the secondary insulating layer is melted and removed by the heat of the solder to integrate the shield layer and the solder, A terminal processing method characterized by grounding this. 3. A coaxial multicore cable characterized by being subjected to the terminal treatment according to claim 2.