JPS63275204A - One body molded product of high frequency antenna substrate and its manufacture - Google Patents

Abstract

PURPOSE:To prevent the warp of a substrate by using a special earthing conductor, and integrally molding a conductor, a dielectric and the earthing conductor, formed on the surface of the molded product, into one body. CONSTITUTION:A plastic molded product 4, provided with a through hole 5, is used as the substrate, and it has such a constitution that the plastic molded product 4 with the earthing conductor of such a special structure that the earthing conductor 6 is formed on the surface of the plastic molded product 4, including the inner surface of the through hole 5, and the dielectric 3 and the conductors 1, 2 are integrally molded into one body. Thus, the warp of the substrate after a circuit pattern is formed on the conductors 1, 2, can be prevented with the aid of the strengthening action of the plastic molded product.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a substrate for a flat antenna used in the communication field such as satellite broadcasting.

[Conventional technology]

Microwave flat antennas used as antennas for satellite broadcasting etc. use copper foil etc. as a conductor on one side of a dielectric material, and circuits are processed on this to create a circular, square, or crank-shaped resonator (radiator) or micro It consists of a flat board on which a strip line is formed and a ground conductor made of metal or the like is placed on the other side. Then, in order to obtain desired gain and directivity, resonators are arranged into an array. The dielectric material used is required to have a small relative permittivity (hereinafter abbreviated as ε), a small dielectric loss tangent (hereinafter abbreviated as tanδ), and good high frequency characteristics.

For this reason, conventionally, resins such as polytetrafluoroethylene, polyethylene, polypropylene, polystyrene, polyisobutylene, and polymethylpentene-1, which have a relatively small ε, have been used as dielectric materials, and these have thermal and mechanical reinforcement effects. In order to express this, glass fibers are embedded and cross-linked (for example, Japanese Patent Laid-Open No. 60-253528), or quartz glass fibers are used as glass fibers (Japanese Patent Laid-Open No. 60-253528).
9-109347) and a method of mixing glass bubbles (microscopic hollow spheres) into a dielectric layer such as epoxy resin (Japanese Patent Application Laid-Open No. 167394/1982). Generally, polyethylene, polytetrafluoroethylene, etc. A substrate made of composite glass fiber and laminated copper foil on both sides is commonly used as a high-frequency substrate. However, these conventional devices have a problem in that transmission loss is large.

Also, Nikkei Electronics No. 347, 145-1
As introduced on page 60 (1984, Nikkei McGraw-Hill Publishing), a flat antenna for receiving microwaves such as satellite broadcasting has a large number of resonators placed on a conductor on one side of a dielectric material to receive radio wave power. However, a method is known in which these signals are aligned using a microstrip line, collected at one or several locations, and guided to a converter, tuner, etc. using a coaxial cable or the like. However, with this method, when high-frequency power flows through the conductor of the dielectric substrate, there is large attenuation due to skin resistance, etc., and the loss (
There is a problem in that the transmission loss (transmission loss) becomes large. As a means to solve this problem, for example, the length of the stripline is shortened by dividing the aperture of the planar antenna into several sections, and the radio wave power from the resonator is concentrated in the center of these sections, thereby creating a conductor with low transmission loss. One possible method is to connect these sections using wave tubes or coaxial cables, but this method has the disadvantage that the connection between the strip line and the waveguide or coaxial cable becomes complicated and requires a large number of steps. As another method, it may be desirable to arrange a large number of resonators on a board, connect them with a microstrip line, concentrate them in one place, and connect them to a coaxial cable.
In this case, the microstrip line must have a substrate with low transmission loss.

In other words, since satellite broadcasting radio waves cannot be made to have as much power as terrestrial broadcasting radio waves in the VHF and UHF bands, and are weak, a board with significantly lower transmission loss is required to increase antenna gain. is the current situation.

In addition, in conventional antenna substrates, when a resonator or strip line is formed on the conductor surface on one side of the dielectric,
There is a problem that warpage occurs at the bottom of the formed surface.

This warpage causes a phase difference in the received radio waves, which is undesirable. This warping of the antenna substrate occurs even if glass fiber is embedded in the dielectric material.

Therefore, in order to prevent this warping and ensure parallelism of the board surface, conventional conductors, dielectrics, and ground conductors are laminated, and after the board is fabricated, a reinforcing plate is laminated from the ground conductor side, and the casing is screwed or A method of fixing by fitting is adopted. There is a method of using a general-purpose metal plate such as iron, aluminum, or stainless steel as the reinforcing plate, but this method increases transmission loss due to the electrical resistance of the metal, makes the planar antenna heavier, and prevents the housing and mounting. The problem is that the jig must be made stronger. Another method is to use an insulator such as plastic as a reinforcing plate, but in this case, the shield conductor and ground conductor of the waveguide or coaxial cable used for the principle of the antenna and for fixing the mode to be used. There is a problem in that it is difficult to connect to the Furthermore, as a reinforcing material for this planar antenna, Japanese Patent Application Laid-Open No. 59-6.
In Publication No. 1203 and Publication of Utility Model Application No. 59-76118,
It has been shown to use reinforced plastic plates made of honeycomb sand inch structures impregnated with resin and cured with carbon fibers. However, these use expensive carbon fiber and require many manufacturing processes, resulting in high costs, so they are useful as special antennas such as large antennas for satellite broadcasting itself and relays, but satellite broadcasting There were problems such as being too expensive and unsuitable for use as a receiving antenna for consumer use or home use to receive radio waves from.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and one of its objects is to make it possible to easily connect a waveguide or a coaxial cable to a ground conductor without substantially causing any warping of the board, and furthermore, to The purpose of the present invention is to provide a high-frequency antenna substrate integrated molded product that has significantly reduced transmission loss, is compact, easy to store, and lightweight, and is extremely superior in practical terms. The purpose is to provide a method for its production.

[Means for solving problems]

As a result of intensive research to solve the above-mentioned problems, the present inventors found that in a high-frequency antenna board composed of a conductor, an inductor, and a ground conductor, a plastic molded product having a through hole is used as a ground conductor. It has been found that a high frequency antenna substrate integrated product constructed using a molded product having a ground conductor formed on the surface including holes is extremely effective in achieving the object of the first invention of the present invention, and Manufacturability of antenna substrate integrated product of this first invention 9
^1 As a method, a through hole is provided in a plastic molded product, the surface of the plastic molded product including the through hole is plated with metal to form a ground conductor, and then the conductor, dielectric, and the ground conductor are integrated. Found that the method of molding is extremely effective in achieving the object of the second invention of the present invention,
Based on these findings, we have completed the present invention.

That is, the high-frequency antenna substrate integrated molded article of the first invention is a high-frequency antenna substrate composed of a conductor, a dielectric material, and a ground conductor, which includes, as the ground conductor, the inner surface of the through-hole of a plastic molded product having a through-hole. This is a high-frequency antenna substrate integrally molded product characterized in that the conductor, dielectric, and ground conductor formed on the surface of the molded product are integrally molded using a ground conductor formed on the surface of the molded product.

A second invention is an invention of a method for manufacturing the high-frequency antenna substrate integrally molded article of the first invention, which comprises a plastier substrate in the method for manufacturing an antenna substrate composed of a conductor, a dielectric material, and a ground conductor. A through-hole is provided in the molded product, a ground conductor is formed on the surface of the molded product including the through-hole, and the conductor, dielectric, and ground conductor formed on the surface of the plastic molded product are integrally molded. This is a method for manufacturing a high-frequency antenna substrate integrally molded article.

Next, the high frequency antenna substrate integrally molded article of the present invention will be explained based on the drawings. Fig. 1 is a perspective view showing a part of a planar antenna, in which 1.2 is a resonator and a strip line after forming a circuit on a conductor, 3 is a dielectric, 4 is a plastic molded product, and 5 is a plastic molded product. A through hole provided in the
6 shows a ground conductor formed on the surface of the plastic molded product and the surface of the through hole.

A through hole 5 is provided in the plastic molded product 4,
The surface of the through hole 5 and both sides of the plastic molded product 4 are coated with a conductive film (metal cladding, plating, vapor deposition film, etc.) to form a ground conductor 6. Plastic molded product 4, dielectric material 3, and conductor (1
, 2) are laminated and integrated as shown in FIG. By doing so, warping of the board after circuit patterns such as resonators and microstrip lines are formed on the conductor can be prevented due to the reinforcing effect of the integrally molded plastic molded product 4. Further, the ground conductor 6 on the surface of the plastic molded product 4 adjacent to the dielectric 3 passes through the ground conductor 6 formed on the surface of the through hole 5 to the ground conductor 6 on the outer surface of the other substrate.
Since the coaxial cable or the waveguide can be connected to an appropriate part of the ground conductor 6 on the outer surface, they can be easily attached, and work efficiency is significantly improved.

The number of through holes 5 may be one, but is preferably two or more in order to ensure reliability.

The plastic molded product 4 is not particularly limited as long as it can be shaped into a desired shape in a sheet form or a mold.
Extrusion molding, press molding, injection molding, stamp sample molding,
Those molded by commonly used molding methods such as vacuum molding and RIM molding can be appropriately selected and used. It may also have a boss for attaching related parts such as a converter, or may be provided with ribs to increase the strength of the plastic molded product. Further, it is desirable that the plastic molded article be reinforced with an inorganic or organic filler.

Examples of the filler include mica, clay, glass peas, glass fiber, alumina, diatomaceous earth, calcium carbonate, talc, wollastonite, starch, paper, and pulp. The type of plastic is not particularly limited, but suitable examples include polyethylene, polystyrene, polypropylene, ABS, As, PVC, polyester, acrylic resin, and polycarbonate. When providing the ground conductor 6 on the surface of the plastic molded product 4, the surface is roughened or chemically modified to improve the adhesion between the ground conductor 6 and the plastic, such as by sandblasting or chrome. It is desirable that the material be chemically etched using a mixture of acid and sulfuric acid or an organic solvent, corona treatment, plasma treatment, etc.

However, since the smoother the dielectric side surface of the ground conductor 6 is, the lower the transmission loss is and the better, it is preferable that the degree of plastic surface roughening is appropriately adjusted to balance adhesion and transmission loss. As the conductors (1, 2) and the ground conductor 6, conductors with low electrical resistance, such as gold, silver, copper, aluminum, nickel, etc., are suitable.In order to reduce transmission loss, silver and copper with lower electrical resistance are preferable. Copper is preferred, and copper is particularly preferred from the viewpoint of cost. The conductor is preferably a metal foil that is smooth on both sides, particularly a copper foil that is smooth on both sides, and among these, rolled copper foil and oxygen-free copper foil are particularly preferable. Furthermore, since high-frequency current flows through the surface layer of the conductor, it is sufficient that the ground conductor has a thickness of several micrometers; if it is too thick, it will easily warp, so it is desirable to adjust the thickness to an appropriate value.

The dielectric 3 may be polytetrafluoroethylene, which is often used in high-frequency substrates, or polyethylene with glass fiber embedded in it, and other resins such as polyolefin and polystyrene can also be suitably used. Among them, in order to reduce transmission loss, it is desirable to use a resin that has as small a value of ε or tan δ as possible.
For example, foamed polyolefin foam containing a small amount of gas or a sintered body of polyolefin powder can be used. By adopting such a configuration, not only the values of ε1 and tanδ are reduced, thereby reducing the transmission loss, but also the elastic modulus of the dielectric material is lowered, and the effect of preventing warping is significantly improved. Since the wall thickness of the plastic molded product can be made thinner, weight reduction can be achieved, and it is also advantageous in terms of cost.

Examples of the polyolefin include polyethylene,
Polyolefin homopolymers such as polypropylene, poly-1-butene, poly-4-methylpentene, polyisobutyne, ethylene-propylene copolymers, ethylene-1-
Examples include polyolefin copolymers such as butene copolymers, propylene-1-butene copolymers, ethylene-vinyl acetate copolymers, ethylene-styrene copolymers, and resin compositions comprising mixtures of these. be able to.

It is desirable that the dielectric 3, the conductors (1, 2), and the ground conductor 6 are laminated via an adhesive layer such as an adhesive or an adhesive film. This is because it is effective in preventing the etching solution from seeping into the dielectric material when etching the conductor. If the adhesive layer contains many polar groups in its structure, ε
,, tan δ may become high. In such a case,
It is desirable to minimize the thickness of the adhesive layer.

Examples of the adhesive include acrylic resin, polyester resin, polyurethane resin, phenol resin, epoxy resin, chloroprene rubber, nitrile rubber, epoxy phenol, butyral phenol, nitrile phenol, and the like. In addition, as an adhesive film, (I) ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ethylene-acrylic acid copolymer, ethylene-maleic acid copolymer, ethylene-maleic anhydride grafted polymer , ethylene-glycidyl methacrylate-
Polyolefins such as vinyl acetate terpolymers and ionomer polymers are copolymerized or grafted with α,β-unsaturated carboxylic acids, their esters, their anhydrides, their metal salts, or saturated organic carboxylic acids. Examples include a copolymer obtained by polymerization, a mixture of (11) polyolefin and the copolymer of (I), and an adhesive composition in which (I) polyolefin is blended with a tackifier or the like.

Next, to explain the manufacturing method of this high-frequency antenna board, the above-mentioned plastic molded product is formed with the above-mentioned through-holes, the above-mentioned ground conductor is formed on the surface including the through-holes, and then the above-mentioned dielectric The high frequency antenna substrate of the present invention can be manufactured by laminating and integrally molding the conductors (1, 2).

The method for providing through holes in plastic molded products is to install a jig such as a pin that becomes the through hole in the mold when molding the plastic molded product, or to create the through hole by punching with a drill after molding. There is.

There are no particular restrictions on the plastic as long as it satisfies the purpose of the present invention, and examples include electroless plating, a combination of electroless plating and electroplating, spunter method, electron beam evaporation, resistance heating evaporation, etc. can be mentioned.

The conductor, the dielectric material, and the ground conductor formed on the plastic molded product can be integrally formed by applying the adhesive or adhesive layer between the ground conductor formed on the plastic molded product, the dielectric material, and the dielectric material and the conductor. Set it so that it has a thickness of
This can be done by stacking them in close contact with each other and pressing and heating under conditions that do not significantly deform the plastic.

In addition, when using a plastic molded product with bosses and ribs as a plastic molded product, if the mold is a male mold, a female mold corresponding to the bosses and ribs is made, and the plastic molded product is inserted into this female mold. By fitting into the mold, the workability of integral molding can be improved.

[Effect]

The high frequency antenna board of the present invention uses a plastic molded product provided with a through hole, and the plastic molded product with a ground conductor has a specific structure in which a ground conductor is formed on the surface of the plastic molded product including the inner surface of the through hole. , a dielectric, and a conductor are laminated and integrally molded, so the reinforcing effect of the plastic molded product prevents the board from warping after a circuit pattern is formed on the conductor, and it also prevents the board from warping after forming a circuit pattern on the conductor. The ground conductor adjacent to the dielectric is electrically connected to the other ground conductor through the ground conductor formed on the through hole in the plastic molded product, so the connection between the ground conductor and the ground conductor can be made at this location. Easy to install and significantly improves work efficiency. Furthermore, as a dielectric, ε
By using a foamed polyolefin foam or a sintered body of polyolefin powder having a small value of , and tan δ, and using copper as a ground conductor, transmission loss can be significantly reduced.

〔Example〕

Example 1 ABS, Talalastic AP-8 (
Molding was carried out using a press at 230° C. using Sumitomo Naugatac Co., Ltd. (trade name) to obtain a plastic molded product measuring 300 x 300 x 3 m. Four through holes each having a diameter of 1 φ were drilled into this.

Next, this was etched with chromic acid and sulfuric acid according to a conventional method, and electroless copper plating was applied to the surface of the plastic molded product including the through holes using Hitachi electroless copper plating solution CUST-201 (trade name of Hitachi Chemical Co., Ltd.). Further, electroplating was performed using copper sulfate to form a ground conductor as a copper plated body having a thickness of 2 to 3 μm. An adhesive film [Nukrel 0908C (25 μm, trade name of DuPont Mitsui Polychemicals Co., Ltd., ethylene methacrylic acid copolymer)] was applied to the copper plating on one side of this ground conductor-covered plastic molded product.
Dielectric material (10 times expanded cross-linked polyethylene foam, High Ethylene S (1 mm, Hitachi Chemical Co., Ltd. trade name)),
Adhesive film: Cucler 0908C), rolled copper foil (35
μm, manufactured by Nippon Mining Co., Ltd.) in this order, and pressed at 120°C for 10 minutes so that the dielectric thickness of the adhesive film and foam becomes 0.7 to 0.8 fins. Obtained.

Example 2 Glass fiber reinforced poly-4-methylpentene-1, FR-TP containing 10% by weight of glass fiber as plastic
Using X Tl 10 (trade name of Mitsui Petrochemical Industries, Ltd.), molding was performed by pressing at 260°C,
A plastic molded product measuring 300 x 3 mm was obtained. Four through holes of 1 length φ were drilled in this. Next, this is sputtered on the front and back sides of the plastic molded product using a sputtering method using a copper plate according to a conventional method.
A copper layer serving as a 3 μm ground conductor was formed.

The surface of the through hole was coated with copper, and when the conductivity of the front and back surfaces of the plastic molded product was measured with a tester, it was found to be conductive. An adhesive film, foam, and copper foil were laminated on the plastic molded product on which the ground conductor was formed in the same manner as in Practical Example 1 to obtain an integrally molded planar antenna board.

Comparative Example 1 300 of FR-TPX Tll0 used in Example 2
A board measuring 300 x 0.7 mm was formed using a press, a rolled copper foil was laminated thereon via an adhesive film Nucrel 0908G (25 μm), and pressed at 120° C. for 10 minutes to obtain a double-sided copper-clad laminate.

Comparative Example 2 The plastic used in Comparative Example 1 was high-density polyethylene, HIZEX 6200B (trade name of Mitsui Petrochemical Industries, Ltd.), and the same procedure as in Comparative Example 1 was performed except that the press molding temperature was 180°C, and both sides were laminated with copper cladding. Got the board.

ε1, transmission loss, and 300% after etching the conductor (copper foil) on the entire surface of the substrates fabricated in Example 1.2 and Comparative Example 1.2
The amount of warpage between fi spans is summarized in Table 1.

ε was measured according to ASTM D3380.

The transmission loss was measured by etching the conductor (copper foil) of the substrate to form a strip line so that the characteristic impedance of the microstrip line was 50±5Ω, and using a sweep generator and a Scalane Sotowork Analyzer in a conventional manner. The measurement frequency was 12 GHz. To measure the warpage, the board was suspended, a straight line ruler was placed on the concave surface, and the maximum distance between the ruler and the concave surface was measured, and this was defined as the amount of warpage.

(Leaving space below) Table 1 * The board may curl and return to its original position. As shown in Table 1, a plastic molded product with through holes is molded, a ground conductor is formed on the surface of the plastic molded product, and a dielectric,
In Examples 1 and 2, in which conductors are laminated and integrally molded, warping after etching can be prevented.

In Comparative Examples 1 and 2, the amount of warpage was zero before etching, but one copper foil of the double-sided copper-clad laminate was used as a ground conductor, a masking film was attached to it, and the other conductor was When removing the entire surface by etching with the assumption that a circuit pattern will be formed on the surface, the amount of warpage is 8fl in Comparative Example 1, even though 10% glass fiber is mixed in and reinforced.
showed a large value. In Comparative Example 2, the substrate curled into a scroll shape, and the amount of warpage could not be measured. After measuring the amount of warpage, Comparative Examples 1 and 2 were screwed to an aluminum plate with a thickness of 1 m, but in Comparative Example 2, the substrate rose from the aluminum plate unless it was screwed at narrow intervals.

A planar antenna must receive radio waves with a resonator, match the phase with a microstrip line, and transmit the collected radio wave power to a waveguide or coaxial cable. When I tried to attach the waveguide of the waveguide coaxial component to the board using four screws, in Example 1.2, I drilled a hole in the waveguide's mounting hole and inserted the screws into the hole. If the through-waveguide was directly fixed, the conductor part of the waveguide and the ground conductor were in contact with each other, so they were sufficiently coupled and the workability was good. On the other hand, comparative example 1
．． Regarding the second example, it was found that the one in which an aluminum plate was used as a reinforcing plate lacked reliability because the contact between the copper foil, which is a ground conductor, and the aluminum plate was insufficient. Further, in this case, connection by soldering was extremely difficult.

Example 3 A planar antenna substrate was obtained in the same manner as in Example 1, except that the plastic molded product was plated with nickel instead of copper. The transmission loss of this product was 2.5 dB/m, and the amount of warpage was zero.

〔Effect of the invention〕

According to the present invention, there is virtually no warping of the board, it is easy to connect the waveguide or coaxial cable to the ground conductor, the transmission loss is significantly reduced, and it is more compact and easy to store. It is possible to provide a high-frequency antenna substrate integrally molded product that is highly superior in terms of characteristics such as being tall and lightweight, and is practically excellent, as well as an efficient manufacturing method thereof.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the main parts of an embodiment of the high frequency antenna board of the present invention. Explanation of symbols 1 Conductor (resonator) 2 Conductor (microstrip line) 3 Dielectric
4 Plastic molded product 5 Through hole 6
Grounding conductor diagram 1

Claims (1)

[Claims] 1. In a high-frequency antenna substrate composed of a conductor, a dielectric material, and a ground conductor, the ground conductor is formed on the surface of a plastic molded product having a through hole, including the inner surface of the through hole. 1. A high-frequency antenna substrate integrally molded product, characterized in that the conductor, dielectric, and ground conductor are integrally molded using a ground conductor. 2. Claim 1 in which the conductor and the ground conductor are copper
An integrally molded product with a high frequency antenna substrate as described in . 3. The high frequency antenna substrate integrally molded product according to claim 1 or 2, wherein the plastic molded product is reinforced with an inorganic or organic filler. 4. The high-frequency antenna substrate integrally molded product according to claim 1, 2, or 3, wherein the dielectric material is a sintered body of expanded polyolefin foam or polyolefin powder. 5. The high-frequency antenna substrate integrally molded article according to claim 1, 2, 3, or 4, wherein the dielectric is bonded to the conductor and the ground conductor by providing an adhesive layer. 6. In a method for manufacturing an antenna substrate composed of a conductor, a dielectric material, and a ground conductor, a through hole is provided in a plastic molded product, a ground conductor is formed on the surface of the molded product including the through hole, and the conductor, dielectric material 1. A method for producing a high-frequency antenna substrate integrally molded product, comprising integrally molding a body and a ground conductor formed on the surface of the plastic molded product. 7. Claim 6 in which the conductor and the ground conductor are copper
A method for manufacturing a high-frequency antenna substrate integrally molded product as described in 2. 8. The method for manufacturing a high-frequency antenna substrate integrally molded product according to claim 6 or 7, wherein the plastic molded product is reinforced with an inorganic or organic filler. 9. The method for manufacturing a high-frequency antenna substrate integrally molded article according to claim 6, 7, or 8, wherein the dielectric material is a sintered body of expanded polyolefin foam or polyolefin powder. 10. A method for manufacturing a high-frequency antenna substrate integrally molded article according to claim 6, 7, 8, or 9, wherein the dielectric is bonded to the conductor and the ground conductor by providing an adhesive layer.