JPH04174912A - Insulating film-covered electric wire - Google Patents

Abstract

PURPOSE:To improve the insulating property and reduce the aging reduction rate by providing a plasma-polymerized insulating film with the relative dielectric constant 3.0 or below. CONSTITUTION:A plasma-polymerized insulating film 14 with the relative dielectric constant 3.0 or below, preferably 2.5 or below, is formed on the outer periphery of the linear conductor 12 of an insulating film-covered electric wire 10. A hydrocarbon monomer is used for the film 14, it is coated and formed by plasma polymerization, and the thickness is preferably set to 0.5-50mum, more preferably to 1-20mum. Saturated hydrocarbon such as methane, ethane, propane, hexane and isobutane, unsaturated hydrocarbon such as 1-butene, butadiene, butyne, pentene and pentadiene, alicyclic hydrocarbon such as cyclohexane, aromatic hydrocarbon such as benzene and toluene, or a monomer substituted with fluorine atoms for part or all of hydrogen atoms connected to carbon atoms of these monomers is used for the hydrocarbon monomer. The insulating property can be improved, and the reduction of the insulating property can be reduced after a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an insulating film-coated electric wire suitable for pulse signal transmission.

(Prior Art) Enamel insulated wires have conventionally been used as wires whose conductors have a diameter of 1 mm or less. However, this electric wire has a large dielectric constant of 4 to 7, so the dielectric constant of this electric wire is 3.
It is unsuitable as an electric wire for pulse signal transmission which requires the following.

For this reason, there is a problem in that the enamel insulated wire is difficult to apply to wiring between ICs.

(Problems to be Solved by the Invention) As mentioned above, the dielectric constant of an enamel insulating film cannot be reduced to 3 or less. Therefore, in order to obtain an electric wire coated with an insulating coating having a dielectric constant of 3 or less, a fluororesin is applied to a linear conductor. However, the insulating film coated with fluororesin and dried does not have a uniform thickness and becomes quite uneven. For this reason, fluororesins have a problem in that their insulation properties are significantly degraded.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide an insulating film-coated electric wire having a small dielectric constant and an extremely thin insulating film suitable for pulse signal transmission.

(Means and effects for solving the problem) The insulating film coated electric wire of the present invention has a
The structure includes a plasma polymerized insulating film having a dielectric constant of 3.0 or less. 'Hereinafter, the present invention will be explained based on the drawings. In FIG. 1, an insulating film coated electric wire 1O is formed by covering the outer periphery of a linear conductor 12 with a plasma polymerized insulating film 14.

The wire forming the linear conductor 12 is not particularly limited as long as it has a diameter of 1 mm or less, such as a metal wire, a metal superconducting wire, a ceramic superconducting wire, or a conductive plastic fiber. Further, a plating layer, an insulating layer, a buffer layer, etc. may be formed on the outer peripheral surface of these wires in advance.

The plasma polymerized insulating film 14 has a dielectric constant of 3.0 or less. If the dielectric constant exceeds 3.0, the wire is unsuitable for use as a pulse signal transmission wire.

The relative dielectric constant of the plasma polymerized insulating film 14 is preferably 2.5 or less.

The plasma-polymerized insulating film 14 is formed by a plasma polymerization method using a hydrocarbon monomer. The thickness is set appropriately depending on the application, but it is usually 500 mm.
The thickness is preferably from nm to 50 μm, and more preferably from 1 μm to 20 μm.

The hydrocarbon monomer is not particularly limited as long as it can lower the dielectric constant of the plasma polymerized insulating film to 3.0 or less and can be vaporized in a reduced pressure atmosphere in which plasma polymerization is performed. The hydrocarbon monomers include saturated hydrocarbons such as methane, ethane, propane, butane, isobutane, pentane, neopentane, hexane, heptane, octane, nonane, decane, ■-butene, 2-butene, butadiene, butyne, pentene, etc. , pentanene,
Unsaturated hydrocarbons such as pentene, hexene, octene, octyne, and decadiene; alicyclic hydrocarbons such as cyclohexene, cyclooctane, and cyclooctyne; aromatic hydrocarbons such as benzene, toluene, and p-diethylbenzene; Examples include monomers in which some or all of the hydrogen atoms bonded to carbon atoms are replaced with fluorine atoms. These monomers can also be used in combination of two or more types.

Next, a method for manufacturing the insulating film-covered electric wire 10 using the plasma polymerization method will be explained based on FIG. 3. The wire 20 (which becomes the linear conductor 12) is sent out from the delivery roller 22 in the direction of the arrow in the figure, and is placed between the two magnets 24a and 24b in the hollow of the inner tube 26 (shown in cross section in the figure). It passes between the two magnets 28a and 28b, and is finally wound up on a winding roller 29. A hydrocarbon monomer is supplied to the hollow portion of the inner tube 26 from a monomer supply source 31 .

Outer tube 30 (in the figure,
A non-polymerizable gas is supplied from a non-polymerizable gas supply source 32 to the hollow portion (the space formed by the outer circumferential wall of the inner tube 26 and the inner circumferential wall of the outer tube 30) (shown in cross section). This non-polymerizable gas is a gas that does not undergo plasma polymerization by itself, such as inert gases such as argon and helium, halogen gases such as hydrogen, deuterium, nitrogen, oxygen, and chlorine, and mixed gases thereof.

While feeding the wire 20 in this manner and supplying the monomer and non-polymerizable gas into the inner tube 26 and outer tube 30,
A discharge is caused by an RF electric field applied from an RF power source 36 to a discharge induction coil 34 wound around the outer circumference of the outer tube 30 . Due to this discharge, the non-polymerizable gas within the outer tube 30 is discharged and turned into plasma. Note that the discharge method is not limited to this, and may be a parallel plate type, magnetron type, or capacitive coupling type discharge, and the discharge frequency is RF (1 to 20 MHz).
>, it can be used for everything from direct current to microwaves.

This RF discharge electric field is absorbed or reflected by the plasma generated inside the outer tube 30 and does not reach the inside of the inner tube 26. As a result, the monomer supplied into the inner tube 26 is
It is discharged as it is from the outlets (or inlets) in both directions of the inner tube 26. On the other hand, the non-polymerizable gas released from the outlet (or inlet) of the outer tube 30 is transferred to the magnets 24a and 24.
Due to the action of the magnetic field formed by the magnets 28a and 28b, the magnetic field concentrates on the surface of the wire 20 near the exit. Then, the hydrocarbon monomer that comes into contact with the non-polymerizable gas turned into plasma is decomposed or activated, and a plasma polymerized film is formed on the surface of the wire 20. Although the magnet disposed near the exit is not essential, it is preferable to use it because it can improve the film forming speed.

These series of steps for forming a plasma polymerized film are performed by operating a vacuum exhaust device 42 in a vacuum chamber 40;
It is preferable to perform this in a vacuum or a reduced pressure atmosphere, or it is also possible to use differential pumping or the like to perform the feeding and winding of the wire 20 outside a vacuum or a reduced pressure atmosphere.

Next, modifications of the insulating film-coated electric wire of the present invention will be explained. In FIG. 2, an insulating film coated electric wire 50 is a plasma polymerized insulating film 5 coated on the outer periphery of a linear conductor 52.
4, a porous plasma-polymerized insulating film (hereinafter referred to as "porous insulating film") 56 and a non-porous plasma-polymerized insulating film (above plasma-polymerized insulating film 1) formed on the outer periphery of the porous plasma-polymerized insulating film 56;
Same quality as 4. (hereinafter referred to as a "non-porous insulating film") 58.

The porous insulating film 56 is formed by a plasma polymerization method using the above-mentioned hydrocarbon layer. The porous insulating film 56 has, for example, pores large enough to allow water to enter from the outside. Further, the thickness of the porous insulating film 56 is appropriately set depending on the application, but is usually preferably 500 nm to 50 μm, and more preferably 1 μm to 20 μm.

The non-porous insulating film 58 is formed by plasma polymerization using the same hydrocarbon monomer as described above. The hydrocarbon monomer in this case may be the same as or different from the monomer used to form the porous insulating film 56. The thickness of this non-porous insulating film 58 is appropriately set depending on the application, and is usually preferably 50 nm to 30 μm, more preferably 500 nm to 15 μm.

Next, a method for manufacturing the insulating film coated electric wire 50 will be explained with reference to FIG. The insulating film coated electric wire 50 is produced by first forming a porous insulating film 56 on the wire, and then forming a non-porous insulating film 58 thereon.

The method for forming the porous insulating film 56 is as follows: plasma polymerized insulating film 1
This process is almost the same as the formation process in No. 4, but differs in that a means for making the insulating film porous is added as described below. That is, when forming a plasma-polymerized insulating film on the surface of the wire 20, a material for making the insulating film porous is added near the exits in both directions of the inner tube 26 and the outer tube 30 by an appropriate means (not shown). (hereinafter referred to as "porous material")
supply. This porous material is not particularly limited as long as it evaporates under a reduced pressure atmosphere, and for example, the same hydrocarbon monomers as described above can be used. The porous material supplied to the surface of the wire rod 20 is immediately vaporized because the inside of the system is maintained in a reduced pressure atmosphere, and is immediately dispersed inside the plasma polymerized film that is being formed.

At this time, the plasma is concentrated on the surface of the wire 20 due to the presence of the magnetic field generated by the magnet, so the porous material dispersed within the film is not fixed and is removed from the film before and after being wound up by the winding roller 29. He runs away to In this way, a series of changes such as supply, vaporization, and escape of the porous material are performed in parallel with the formation of the plasma polymerized film, so that the wire rod 2
The plasma polymerized film formed on the surface of 0 becomes porous.

Note that a grid electrode or an electrostatic field can be used instead of the magnetic field generated by the magnet. In addition, although the porous material dispersed in the membrane is allowed to escape naturally, it is forcibly removed by heating the plasma polymerized membrane, extraction with a solvent, blowing dry hot gas, etc. You can also do that.

The wire rod on which the porous insulating film 56 has been formed in this way is then sent out in the opposite direction from the winding roller 29, and in the process of being finally wound up by the sending roller 22, the above-mentioned insulating film coated electric wire IO is A non-porous insulating film 58 is formed in the same manner as the method for forming the plasma-polymerized insulating film 14 to obtain an insulating film-covered electric wire 50.

Note that in the insulating film coated electric wire 50, the porous insulating film 5
A protective layer, a buffer layer, or an insulating layer may also be formed between 6 and the non-porous insulating film 58.

Insulating film coated electric wire of the present invention! In this case, the relative dielectric constant of the plasma polymerized insulating film formed around the outer periphery of the linear conductor is small. Further, when the plasma polymerized insulating film has a composite film structure and the lower layer film is a porous film, the relative dielectric constant can be further reduced due to the presence of voids contained in the film. By forming a non-porous film on the porous film, it is possible to prevent water and the like from entering the porous film, thereby preventing a decrease in dielectric constant and an increase in insulation resistance.

(Example) Examples 1 to 28 A plasma polymerized insulating film was formed on the outer periphery of a tin-plated copper wire with a diameter of 0.1 mm by applying a plasma polymerization method using the apparatus shown in FIG. 3, and the structure shown in FIG. 1 was obtained. An insulating film coated wire was obtained. The monomers and non-polymerizable gases for forming the plasma-polymerized insulating film are as shown in Table 1, and the discharge voltage is 60W.
I went there. The volume resistance, dielectric breakdown voltage, and dielectric constant of these wires were measured. The results are shown in Table 1.

Comparative Example 1 Enamel film (
A wire was obtained by coating the wire with a thickness of 12 μm. This electric wire had a volume resistivity of 6XlO''Ω·cm, a relative dielectric constant of 4°2, and a dielectric breakdown voltage of 180 KV/mm.

(Leaves below) Examples 29 to 54 A porous insulating film was formed on the outer periphery of a tin-plated copper wire with a diameter of 0.1 mm by applying a plasma polymerization method using the apparatus shown in Figure 3, and a non-porous insulating film was further formed on the outer periphery. A quality insulating film was coated to obtain an insulating film-covered electric wire having the structure shown in FIG. 2. Note that the upper parts for forming the porous insulating film and the non-porous insulating film are as shown in Table 2, decane was used as the porous material, and the discharge voltage was 60 W. The volume resistance, dielectric breakdown voltage, and dielectric constant of the obtained insulating film-coated wire were measured.

Comparative Example 2 An electric wire was obtained in the same manner as in Example 29 except that a non-porous insulating film was not formed. The initial volume resistance value of this electric wire is Example 29
As shown in Figure 4, the change over time was large, making it impractical.

(Blank below) (Effects of the Invention) The insulating film-coated electric wire of the present invention has a plasma polymerized insulating film with a dielectric constant of 3.0 or less on the outer periphery of a linear conductor with a diameter of 1 mm or less. It is something.

In the insulating film coated electric wire of the present invention, the plasma polymerized insulating film formed on the outer periphery of the linear conductor is a very thin and homogeneous film. For this reason, the dielectric constant of the insulating film is small,
The wire itself can be made extremely thin. Further, the insulating film-coated electric wire of the present invention has excellent insulation properties, and its deterioration is small even after a long period of time.

The insulating film-coated wire of the present invention is suitable for transmitting pulse signals, for example, as a wire for wiring between ICs.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of an insulating film-coated electric wire of the present invention, Fig. 2 is a cross-sectional view of a modification of the insulating film-coated electric wire of the present invention, Fig. 3 is a schematic diagram of a plasma polymerization apparatus, and Fig. 4 is an example. 29 is a diagram showing oral changes in volume resistivity of Comparative Example 2 and Comparative Example 2. 10... Insulating film coated electric wire, 12... Linear conductor, 1
4... Plasma polymerized insulating film, 50... Insulating film coated electric wire, 52... Linear conductor, 54... Plasma polymerized insulating film, 56... Porous plasma polymerized insulating film, 58...
・Non-porous plasma polymerized insulation film.

Claims (1)

[Claims] The outer periphery of a linear conductor with a diameter of 1 mm or less has a relative permittivity of 3.
．． An insulating film-coated electric wire characterized by having a plasma polymerized insulating film of 0 or less.