JP3075782B2 - Flat cable manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a flat cable having no adhesive layer.

[0002]

2. Description of the Related Art A conventional flat cable is obtained by arranging a plurality of conductors at predetermined intervals and extruding and coating a thermoplastic resin such as vinyl chloride or polyethylene terephthalate (PET) or sandwiching and firing with an insulating tape. . Although such a flat cable is inexpensive and excellent in productivity, it cannot be said that heat resistance and chemical resistance are sufficient for use around an engine of an automobile or an oil-immersed portion.
In order to solve such problems, tetrafluoroethylene (PTF)
Although the flat cable according to E) has been put to practical use, it cannot be said that it is sufficient in terms of heat resistance and supportability, and a material satisfying such requirements has not been put to practical use.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyimide flat cable without an adhesive layer, which makes use of the inherent alkali resistance, solvent resistance, heat resistance, and electrical characteristics of polyimide. It is intended to provide a manufacturing method.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a pattern in which a plurality of pairs of conductor wires are arranged in parallel on a two-layer flexible printed circuit board without a polyimide adhesive layer is formed. A flat cable manufacturing method characterized by heating and pressing the polyamic acid film surfaces of the polyamic acid film formed as described above, and then heating and drying imidization.

That is, a polyamic acid solution is applied on a release film and dried until a tack-free state is obtained, thereby forming a polyamic acid film. Thereafter, the films are heated and pressed together with the amic acid film surfaces aligned, sandwiching a plurality of pairs of rectangular conductors arranged in parallel. At this time, if necessary, the polyamic acid film from which the release film has been peeled can be inserted between a predetermined number of sheets to obtain a thicker polyamic acid film. After crimping,
The release film on one side can be peeled off, and the same can be repeated to obtain a thicker film. If necessary, the polyamic acid film with the release film is subjected to hole processing by opening the polyamic acid film together with the release film or only the polyamic acid film by a usual method, for example, punching, cutting, alkali etching, laser or the like. And a flat cable having an opening. After the hole processing is completed, the release film is peeled off, and imidization is performed by sufficiently heating and drying.

Alternatively, a pattern in which a plurality of pairs of conductor wires are arranged in parallel on a polyimide two-layer flexible printed circuit board by an ordinary method such as etching is formed, and a polyamic acid film formed on a release film is formed on the wiring. After heating and pressing the amic acid film surface on top of each other,
A flat cable can be obtained by dry imidization.

In the present invention, the conditions for drying the polyamic acid solution to form a semi-cured polyamic acid film are preferably 80 to 200 ° C. and 5 to 30 minutes.
If the temperature is lower and the time is shorter than this, when heat-pressing with the conductor foil, the fluidity is large, the bleeding at the opening, the seepage is large, the variation in the film thickness is large, and the dimensional change after imidization is large. growing. If the temperature is higher and the time is longer than this, the fluidity is too small when heating and pressing with the conductor foil, the peel strength with the conductor foil is reduced, and the occurrence of voids increases. It is appropriate that the thickness of one amic acid be 50 μm or less after imidization. If the thickness is larger than this, the stress due to the shrinkage due to imidization exceeds the supporting force of the release film, and a large curl is generated during drying. In addition, the evaporation rate of the solvent is slow because the film layer is thick,
Productivity drops significantly. The conditions for heating and pressure bonding the polyamic acid films to the conductor foil are as follows: 70 to 200 ° C for press type, 5 to 100 kg / cm ² for 5 to 30 minutes, and 70 to 200 for roll type laminator. 200 ℃, 1-50kg / cm, 0.1-10m
/ Min is appropriate, and the temperature is preferably 10 to 30 ° C. lower than the drying temperature of the polyamic acid film without generation of volatiles.

The polyamic acid of the present invention is usually obtained by reacting a diamine with an acid anhydride.
Examples of the diamine include phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, and diaminodiphenyl ether.Examples of the acid anhydride include trimellitic anhydride, pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, and benzophenone. For example, tetracarboxylic dianhydride can be used.
Species or a combination of two or more can be used as appropriate. The imidation ratio in the state of the polyamic acid film is preferably from 10 to 50%, and more preferably from 20 to 40%.

Materials that can be used as the release film include polypropylene, polyester, and polyester.
Plastic films such as tersulfone, polyimide, and polyethylene can be given.

Materials that can be used for the conductor layer include metal foils such as copper, aluminum, constantan, and nickel.

[0011]

According to the present invention, a semi-cured polyamic acid film is formed on a release film, and a plurality of pairs of rectangular conductors arranged in parallel are interposed therebetween.・ After crimping, heat-dry imidization, or form a pattern in which a plurality of pairs of conductor wires are arranged in parallel by a normal method such as etching on a polyimide two-layer flexible printed circuit board, and release film on this wiring After heating and pressing the amic acid film surface of the polyamic acid film formed on top,
By heating and drying imidization, productivity and
Good yield, the inherent alkali resistance of polyimide,
It is possible to obtain a polyimide flat cable having no adhesive layer, utilizing the solvent resistance, heat resistance, and electric characteristics as they are.

[0012]

EXAMPLE In a four-neck separable flask equipped with a thermometer, a stirrer, a reflux condenser and a dry nitrogen gas inlet, 108 g of purified anhydrous paraphenylenediamine was added.
200 g of 4'-diaminodiphenyl ether was taken, and a mixed solvent of 90% by weight of anhydrous N-methyl-2-pyrrolidone and 10% by weight of toluene was added thereto.
Was added and dissolved. Dry nitrogen gas was allowed to flow throughout the entire process from the preparation of the reaction to the removal of the product. Next, 294 g of purified anhydrous 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and 218 g of pyromellitic dianhydride are added little by little with stirring, but the reaction is exothermic. This was cooled by circulating cold water at about 15 ° C. After the addition, set the internal temperature to 20 ° C,
After stirring for 5 hours, the reaction was completed to obtain a polyamic acid solution.

This polyamic acid solution was applied on a commercially available copper foil so as to have a thickness of 50 μm after imidization by a spinner, dried and imidized to obtain a two-layer flexible printed circuit board. Next, parallel wiring pattern processing is performed,
Use a two-layer flexible printed circuit board, and use a polyester film instead of the above-mentioned copper foil on the conductor layer side at 110 ° C and 15 ° C.
The surface of the amic acid film of the polyamic acid film with the release film obtained by drying for minutes is heated and pressed, and a roll laminator is applied at 90 ° C., 10 kg / cm, 1 m / min. After using, peel off the release film 380 ℃
For 1 hour to complete the imidization. The characteristics of the obtained flat cable are excellent in heat resistance (solder heat resistance, 36
0 ° C. for 1 minute) and had chemical resistance.

[0014]

According to the present invention, a flat cable consisting of only a polyimide layer having no adhesive layer can be obtained, and it can be easily applied to a continuous process using a continuous sheet. This is suitable as a method for manufacturing a flat cable.

Claims (1)

(57) [Claims] 1. A pattern in which a plurality of conductor wires are arranged in parallel on a two-layer flexible printed circuit board without a polyimide adhesive layer, and a polyamic acid film formed on a release film is formed on the wiring. A method for producing a flat cable, which comprises heating and pressing the amic acid film surfaces together, followed by heating and drying imidization.