JPH02236909A - Flat cable - Google Patents

Abstract

PURPOSE:To improve a stripping property in a terminal part by making crystallinity of a material substance of an insulating layer below a prescribed value. CONSTITUTION:Polytetrafluoroethylene unsintered tapes 2a, 2b are continuously fed between rotating rollers 1a, 1b being in mutual pressure contact, conductors 3 consisting of a silver-plated copper wire are fed in parallel between the tapes, while these are pressure fixed from up and down direction by the tapes 2a, 2b for being wrapped up. The obtained flat cable precursor 4 is introduced into a furnace 5 for being sintered followed by being cooled in order to obtain various kinds of flat cable. A polytetrafluoroethylene insulating layer at this time is consisting of polyetrafluoroethylene of crystallinity less than 50%.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a flat cable, and more particularly, to a flat cable with excellent stripability at the terminal portion. (Prior art) Flat cables used for peripheral wiring of large computers, etc. have multiple conductors spaced apart from each other and placed side by side.
Unsintered tapes of polytetrafluoroethylene are crimped from the top and bottom of these conductors to cover the entire conductor, then edges are removed on both sides, and finally the whole is introduced into a sintering furnace at a predetermined temperature. It is manufactured by sintering sintered tape of polytetrafluoroethylene into a conductor. In this case, silver-plated copper wire is generally used as the conductor. Here, polytetrafluoroethylene acts as an insulating layer that envelops the conductor, and because it has excellent heat resistance and good signal transmission properties, it is widely used as an insulator for connection cables between electronic devices. In order to attach a connector to the flat cable manufactured in this way, it is necessary to strip off the insulation layer at both ends of the flat cable with a flat cable stripper to expose the conductor. (Problem to be solved by the invention) However, the polytetrafluoroethylene insulation layer in conventional flat cables is flexible as a whole and has low frictional resistance, so the stripper blade may slip on the surface of the insulation layer and enter the layer. As a result, the insulating layer at the terminal part could not be peeled off cleanly.

An object of the present invention is to solve the above-mentioned problems and provide a flat cable from which the insulating layer at the terminal portion can be reliably stripped.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention includes a plurality of conductors arranged in parallel and spaced apart from each other, and a polytetrafluoroethylene insulating layer that covers and closely contacts the conductors. In the flat cable consisting of, it is unprecedented! ! A flat cable is provided, characterized in that the layers are made of polytetrafluoroethylene with a degree of crystallinity of 50% or less.

In the case of the flat cable of the present invention, there is no difference from the conventional cable except that the insulating layer is made of polytetrafluoroethylene having the above crystallinity. If the crystallinity of the polytetrafluoroethylene constituting the insulating layer is higher than 50%, the hardness of the polytetrafluoroethylene will decrease and it will become soft, and the strength of the insulating layer will also increase, making it difficult to peel off with a stripper. It becomes difficult. The preferred crystallinity is about 40 to 50%.

Note that the crystallinity as used in the present invention is a value (%) calculated from the ratio of absorbance at each wave number of 778 cm to 2367 cm when infrared absorption spectrum measurement is performed on polytetrafluoroethylene.

When manufacturing the flat cable of the present invention, first, as in the conventional case, a plurality of conductors are arranged in parallel so as to be spaced apart from each other, and then an unsintered polytetrafluoroethylene tape is applied from above and below. After crimping and cutting edges on both sides, it is introduced into a sintering furnace and sintered.

At this time, the temperature of the sintering furnace is preferably controlled to be lower than 480°C. If the temperature at this time is higher than 480°C, when silver-plated copper wire is used as a conductor, it will turn black and begin to cause edge resistance defects. After sintering, the entire product is cooled using water-cooled rolls, air-cooled, etc.

(Examples of the Invention) Examples 1 to 9, Comparative Examples 1 to 7 Flat cables were manufactured using the apparatus schematically shown in FIG. That is, unsintered polytetrafluoroethylene tapes 2a and 2b are continuously supplied between rolls la and Ib that rotate while being pressed against each other, and a silver-plated copper wire 144 with a wire diameter of 0.18 mm is inserted between these tapes. The conductors 3 of the book are fed parallel to each other and these conductors 3 are connected to the tape 2.
A and 2b were crimped and encapsulated from above and below. Then, the flant cable precursor 4 thus obtained is placed in a sintering furnace 5.
After sintering for 4 minutes at the temperature shown in Table 1,
Various flat cables were manufactured by cooling using the method shown. The crystallinity of the polytetrafluoroethylene in these flat cables was calculated using IR spectroscopy. Regarding the stripability of the terminal part of each flat cable,
Carpenter Full Soto Cable Stripper 47
-B was used to strip the insulating layer at the terminal part, and the case where the insulating layer was completely stripped off was evaluated as ○, and the case where even a small amount remained in the center of the cable width direction was evaluated as ×. The above results are summarized in Table 1. (Margin below) 4. (Effects of the Invention) As is clear from the above explanation, in the flat cable of the present invention, the crystallinity of the polytetrafluoroethylene that is the insulating layer is 50% or less, the hardness is high, and the strength is low. Because of this, the stripping property at the terminal part is excellent.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of an example of equipment used to manufacture the flat cable of the present invention. la, lb...Roll, 2a, 2b...Polytetrafluoroethylene unsintered tape, 3...Conductor (II
plated copper wire), 4... flat cable precursor, 5...
...Sintering furnace.

Claims (1)

[Claims] A flat cable consisting of a plurality of conductors spaced apart from each other and a polytetrafluoroethylene insulating layer encasing and adhering to the conductors, wherein the insulating layer has a polytetrafluoroethylene crystallinity of 50% or less. A flat cable characterized by consisting of.