JP3124536B2 - Manufacturing method of noise prevention shielded wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Industrial Application Field] The present invention relates to conduction of electromagnetic noise generated in an electronic device,
Or to prevent electromagnetic interference to other equipment due to radiation,
The present invention relates to a method for manufacturing a noise-prevention shielded wire that connects inside or between electronic devices.

[Prior art] Conventionally, in order to prevent electromagnetic noise generated in an electronic device from being conducted or radiated by electromagnetic noise to prevent electromagnetic interference to other devices, the electromagnetic noise that propagates on a signal line is In a simple configuration, a device housing 7 as shown in FIG. 4 is grounded by a ground wire 5 at a signal line outlet or a signal inlet of each device, and a capacitor 6 is inserted between the device case 7 and the signal line 1. Use a through-type capacitor, or wrap a signal line and attach an inductor in a closed magnetic circuit around the cable, or combine the capacitor and inductor to form a filter circuit,
A shielded wire inserted into a signal line or covered with a metal net having good electrical conductivity has been used for radiation of electromagnetic waves from the outside. On the other hand, when a conventional shielded wire is used as it is for connection between devices, it is necessary to mount a noise filter on the input and output sides of the device. Therefore, extra inlet filters and outlet filters are required, and it is necessary to incorporate a noise filter on the board when mounting the board.For this reason, a through-type capacitor is used for connecting the signal line on the output side of the device, and beads are mounted on the board. Take countermeasures such as inserting an inductor in series with the signal line to configure an inverted L-type or π-type noise filter, or configuring a T-type noise filter by passing the signal line cable through the center hole of the toroidal core. I was For electromagnetic noise in the frequency band of 100 MHz or more, a capacitor was inserted between the signal line and the ground to take measures to suppress the electromagnetic noise.

[Problems to be solved by the invention]

The present invention allows a signal line connecting electronic devices to maintain the characteristic of suppressing electromagnetic noise in the electronic device or between the electronic devices. In order to suppress electromagnetic noise, remove the noise filters that were conventionally mounted on the input and output sides of signal lines between electronic devices, or configure the noise filter with a simple configuration and with only an inductor mounted. It is an object of the present invention to provide a method for manufacturing a noise prevention shielded wire.

B. Configuration of the Invention [Means for Solving the Problems] The noise prevention shield wire according to the present invention is formed by coating a polymer material kneaded with dielectric ceramic powder around the signal line in order to suppress electromagnetic noise in a high frequency band. The surface of the polymer material having the above-mentioned dielectric properties, which covers the signal line, is covered with an electromagnetic shielding conductor made of a copper net made of a good electrical conductor. By providing a capacitance between the electromagnetic shielding conductors, a noise filter can be easily realized only by inserting a bead inductor or the like in series to the signal line on the substrate. That is, a high-permittivity polymer material in which a dielectric ceramic powder is dispersed is coated on a signal line through which a signal is transmitted, and an electromagnetic shielding conductor is formed with a mesh wire or a metal foil. By manufacturing by covering with a polymer material, a noise prevention shield line having a large distributed capacitance between the signal line and the electromagnetic shielding conductor and having a characteristic of suppressing electromagnetic noise is obtained.

That is, the present invention relates to: 1.A plurality of parallelly arranged at equal intervals, the periphery of a signal line composed of an electric conductor that conducts an electric signal is integrally formed by a dielectric layer obtained by kneading a dielectric ceramic powder in a polymer material. A method for manufacturing a noise-prevention shielded wire, comprising wrapping, covering the outer periphery of the dielectric layer with an electromagnetic shielding conductor made of a net-like electric good conductor, and covering the outermost periphery with an insulating covering layer.

[Action]

Conventional shielded wires for connecting between electronic devices usually have a low dielectric constant to prevent signal attenuation during signal transmission to an electrical insulating material wrapped around a signal line through which a central signal is transmitted. Polyethylene or the like is used. Unlike such conventional shielded wires, in the present invention, a ceramic material having a high dielectric constant is kneaded to produce a polymer material having a high dielectric constant. Shielded wire replaced with a high polymer material.

The shielded wire of the present invention is wrapped with a vinyl chloride polymer material having a dielectric constant of about 60 and a ceramic powder kneaded around a central conductor through which the signal wire passes, and the outer periphery thereof is made of a copper mesh or copper foil. It has a structure in which it is wrapped with an electromagnetic shielding conductor and its outer periphery is further covered with a polymer organic electric insulating material. The signal line through which signals are transmitted is wrapped with a polymer material with a high dielectric constant, and the outer periphery is covered with an electromagnetic shielding conductor made of a good electrical conductor made of copper mesh. The equivalent effect is equivalent to connecting a large capacitance in parallel to the signal line, and has the effect of suppressing electromagnetic noise only by the capacitance of the shield line. When connecting a bead inductor, for example, to the output side of a device to which the shielded wire using the shielded wire of the present invention is connected, an inverted L-type noise filter is formed. When a bead inductor is connected to the line, a T-type noise filter is formed. Also, the noise prevention shield wire of the present invention
Depending on the amount of the high dielectric ceramic powder dispersed in the polymer material forming the dielectric layer, the capacitance value can be changed in any way, and the capacitance value of the shielded wire can be changed depending on the frequency band used. Just choose.

〔Example〕

 The noise prevention shield wire of the present invention will be described.

FIG. 1 shows the configuration of a noise prevention shield line according to an embodiment of the present invention. In FIG. 1, a signal line 1 made of a copper wire, which is a good electrical conductor, and a cylindrical dielectric layer 3 formed concentrically around the signal line, and the outer periphery thereof is covered with an electromagnetic shielding conductor. A pair of conductors is formed by the central signal line. The outer periphery of the dielectric layer is wrapped by an electromagnetic shielding conductor 2 made by knitting a thin copper wire, which is a good electrical conductor of metal, and the outer periphery is further covered by an insulating coating layer 4 made of an electrically insulating resin. The signal line 1 may be a copper wire of 0.3 mm and the electromagnetic shielding conductor 2 may be a cylindrical net made of a copper wire or a copper foil having a thickness of, for example, about 6 μm. The electromagnetic shielding conductor that covers the outer periphery of the dielectric layer is conductive, and the mesh-shaped conductor has strength against bending of the shielded wire, but when the shielded wire of the present invention is fixed and used, copper foil or aluminum foil or the like is used. May be used by winding the ribbon.

The dielectric layer 3 is formed by selecting and combining a high dielectric material of ceramic powder having high dielectric properties, a binder of a polymer material, rubbers, a composite polymer, a solvent, a plasticizer, and the like. It is composed of a polymer material obtained by kneading a high dielectric ceramic powder into an organic material.

As a dielectric material, lead / nickel / niobium / magnesium / tungsten / titanium oxide [Pd ｛(NiNb) (Mg
W) {TiO ₃ ] and barium-titanium calcium oxide (BaT
Any of a dielectric material composed of iO ₃ , CaTiO ₃ ) and lead (Pb) perovskite, and a tantalum oxide (Ta ₂ O ₅ ) may be used.

The polymer material into which the dielectric powder is kneaded is, in addition to vinyl chloride resin, rubbers such as silicone rubber, butyl rubber,
And propylene rubber. In addition, as a device related to this dispersion, there are a ball mill, an attritor, a sand mill, a homogenizer, a three-roller, a raikai machine and the like, and any of them may be used for kneading the ceramic powder and the polymer material.

Next, a noise prevention shield wire according to an embodiment of the present invention will be described. Lead with a characteristic of dielectric constant ε of about 8000
After coarsely pulverizing the sintered block of perovskite-based dielectric material, using a sand mill in a toluene-based solvent,
After producing a ceramic powder having a particle size of 0.5 μm to 1.5 μm and scattering the solvent, polyvinyl butyral and a ceramic powder composed of a dielectric material are mixed in a weight ratio of about 75% ceramic powder to polyvinyl butyral, and Was added, and slurried with a ball mill. A 0.3 mmφ copper wire was passed through the slurry to form a 200 μm to 300 μm dielectric layer on the outer periphery of the copper wire. A copper mesh was covered so as to cover the dielectric layer, and the whole was covered with vinyl having an electric insulating property to manufacture a noise prevention shield wire. The dielectric constant ε of the dielectric layer used for the obtained shield wire was approximately 60, and the capacitance of the noise prevention shield wire having an outer diameter of 1.7 mm and a length of 1 m was 1700 PF. Connect the noise prevention shield wire of 1 m length according to the embodiment to an oscillator with an internal impedance of 50 Ω, terminate it with 50 Ω and insert the noise prevention shield wire, and both ends of the terminal resistance when the noise prevention shield wire is not inserted FIG. 2 shows the results of measuring the damping characteristics of FIG. At 500MHz, the attenuation is almost
A characteristic of 40 dB was confirmed.

FIG. 3 shows another embodiment of the noise prevention shield wire according to the present invention, in which a plurality of conductors are arranged in parallel at substantially equal intervals,
The space between the conductors is wrapped with a dielectric layer 3 obtained by kneading ceramic powder into a polymer organic insulating material similar to that of the above-described embodiment, and the outer periphery is further covered with a net-like electromagnetic shielding conductor 2 of an electric conductor, and the outer periphery is further organically insulated. It is covered with a material. Dielectric ceramic powder is added to polyvinyl butyral so as to enclose the conductors arranged in parallel at the center, and then ethyl cellosolve is added and kneaded to form a dielectric layer with a dielectric constant ε value of about 60. It is formed into a flat cable type noise prevention shielded wire whose outer periphery is further covered with an electromagnetic shielding conductor.

C. Effect of the Invention [Effect of the Invention] As described above, the signal line for transmitting the signal according to the present invention and the periphery thereof are wrapped with a polymer material kneaded with ceramic powder having a high dielectric constant, and the outer periphery is covered with an electromagnetic shielding conductor. Since the noise prevention shield wire has a capacitance between the signal wire itself and the electromagnetic shielding conductor that is grounded, the noise prevention shield wire is a noise prevention shield wire that has the advantage that a filter circuit can be easily formed. A reverse L-type or T-type noise filter can be constructed simply by connecting an inductor in series to the output and output signal lines, the number of noise components on the equipment board is reduced, and a conventional electromagnetic noise prevention circuit of this type The suppression effect is also greater than that of

[Brief description of the drawings]

FIG. 1 is a perspective view showing the structure of a noise prevention shield line according to the present invention. FIG. 2 is a characteristic diagram showing attenuation characteristics at high frequency of one embodiment of the noise prevention shield wire according to the present invention. FIG. 3 is a perspective view showing a flat cable type noise prevention shield wire according to the present invention. FIG. 4 is a side sectional view showing a conventional noise prevention filter. 1 ... signal line, 2 ... electromagnetic shielding conductor, 3 ... dielectric layer,
4 ... insulating coating layer, 5 ... ground wire, 6 ... capacitor,
7: Device housing, 8: Solder.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-165310 (JP, A) JP-A-60-117506 (JP, A) JP-A-58-166608 (JP, A) JP-A 63-165 98903 (JP, A) JP-A-63-228526 (JP, A) JP-A-1-132002 (JP, A) JP-A-62-140310 (JP, A) Japanese Utility Model Laid-Open No. 60-186617 (JP, U) 62-41617 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01B 11/06 H01B 3/00 H01B 7/08

Claims (1)

(57) [Claims] 1. A signal line comprising a plurality of electric conductors for conducting electric signals, which are arranged in parallel at equal intervals, is integrally surrounded by a dielectric layer obtained by kneading dielectric ceramic powder in a polymer material. A method for manufacturing a noise-prevention shield wire, comprising: covering an outer periphery of the dielectric layer with an electromagnetic shielding conductor made of a net-like electric conductor, and covering an outermost periphery with an insulating coating layer.