JP2013236121A - High frequency circuit structure and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency circuit structure which includes a high frequency circuit, efficiently realizes good electric characteristics, and, in particular, achieves the downsizing of a printed wiring board when the printed wiring board is formed, and to provide a manufacturing method of the high frequency circuit structure.SOLUTION: A high frequency circuit structure K includes: a base material 10 formed by an insulative resin; a first high frequency circuit 21a provided on the base material 10 and made of a conductive metal; and a second high frequency circuit 21b electrically connected with the first high frequency circuit 21a in at least a part thereof. The second high frequency circuit 21b is formed as a layer formed by applying and burning a conductive ink containing metal particles.

Description

  The present invention relates to a high-frequency circuit structure that can realize good electrical characteristics in a high-frequency circuit structure including a high-frequency circuit, and a method for manufacturing the high-frequency circuit structure.

In the field of electronic devices such as mobile phones and computer hard disk devices, signal transmission speeds have increased with the downsizing and higher performance of electronic devices. And with the improvement in signal transmission speed, electrical signals transmitted through transmission lines (so-called circuits) have become higher in frequency.
Therefore, in recent years, in the field of, for example, a printed wiring board disposed inside an electronic device, a printed wiring board having a high-frequency circuit structure having a circuit for transmitting a high-frequency signal (hereinafter referred to as a high-frequency circuit) is frequently used. ing.
Here, “high frequency” means a region having a frequency of 300 MHz or more.
In such a high-frequency circuit structure, the amplitude and phase of the signal change depending on the length of the wiring constituting the circuit, and the characteristic impedance changes depending on the width of the wiring constituting the circuit. That is, in the high-frequency circuit structure, a distributed constant circuit is formed by using components (conductor (C), inductance (L), resistance (R)) that cause changes in the signal that the high-frequency circuit itself passes.
Therefore, in the development of a high-frequency circuit structure, an important development issue is how to design a high-frequency circuit capable of matching electrical characteristics in order to achieve good electrical characteristics.
As a prior art showing such a high-frequency circuit structure, for example, there is Patent Document 1 below.

JP-A-5-259762

Conventionally, in a printed wiring board having a high-frequency circuit structure as shown in Patent Document 1, a land is provided in a part of the high-frequency circuit, and a chip component such as a chip capacitor (so-called passive element) is mounted on the land via solder. By doing so, it is common to try to match the electrical characteristics.
However, in a printed wiring board in which such chip parts are mounted, the total thickness (height) of the printed wiring board increases by the thickness (height) of the chip parts. There was a problem that could not be planned. There is also a problem that the chip component may come off when the printed wiring board is hit against something.
Conventionally, a high-frequency circuit structure in which a high-frequency circuit is formed by etching a wiring made of a conductive metal such as copper and the high-frequency circuit itself is a passive circuit such as a conductor (C) is provided. There was a printed wiring board.
However, in such a configuration, when it is desired to finely adjust the characteristics of the manufactured high-frequency circuit, it is necessary to recreate the etching mask, and there is a problem in that it is impossible to realize the efficiency of the manufacturing process and the reduction of the manufacturing cost. It was.

  Therefore, the present invention solves the above-mentioned conventional problems, and in a high-frequency circuit structure including a high-frequency circuit, it is possible to efficiently realize good electrical characteristics, as well as increase the efficiency of the manufacturing process and the reduction of manufacturing cost. It is another object of the present invention to provide a high-frequency circuit structure capable of reducing the size of the printed wiring board and a method for manufacturing the high-frequency circuit structure, particularly when the printed wiring board is formed.

  The high-frequency circuit structure of the present invention includes a base material made of an insulating resin, a first high-frequency circuit made of a conductive metal provided on the base material, and a second electrical connection at least partially with the first high-frequency circuit. A high-frequency circuit structure including a high-frequency circuit is characterized in that the second high-frequency circuit is configured as a layer formed by applying and baking a conductive ink containing metal particles.

According to the first aspect of the present invention, the high-frequency circuit structure includes a base material made of an insulating resin, a first high-frequency circuit made of a conductive metal provided on the base material, the first high-frequency circuit, and at least A high-frequency circuit structure comprising a second high-frequency circuit electrically connected in part, wherein the second high-frequency circuit is configured as a layer formed by applying and baking conductive ink containing metal particles. The second high-frequency circuit itself can be used as a passive circuit such as a conductor (C), and a high-frequency circuit structure capable of realizing good electrical characteristics can be obtained. Further, since the second high-frequency circuit itself can be used as a passive circuit such as a conductor (C), there is no need to mount a chip component or the like, and in particular when a printed wiring board having a high-frequency circuit structure is formed, The thickness (height) of the wiring board can be effectively suppressed, and a high-frequency circuit structure that can reduce the size of the printed wiring board can be obtained.
Further, by forming the second high-frequency circuit as a layer formed by applying and baking conductive ink containing metal particles, the second high-frequency circuit is adjusted to a desired configuration (shape, length, width, thickness, etc.). It can be formed with high accuracy. Therefore, a high-frequency circuit structure capable of realizing much better electrical characteristics can be obtained. Also, the second high-frequency circuit can be easily formed on the substrate without the need for expensive vacuum equipment necessary for physical vapor deposition such as sputtering for the formation of the second high-frequency circuit, and without using an organic adhesive. Can do. Therefore, the second high-frequency circuit can be easily formed, and the manufacturing process can be made more efficient and the manufacturing cost can be reduced.

  The method for manufacturing a high-frequency circuit structure according to the present invention includes a first high-frequency circuit forming step of forming a first high-frequency circuit made of a conductive metal in a predetermined region on a base material made of an insulating resin, and the first high-frequency circuit; Conductive ink containing metal particles is applied to another predetermined region on the substrate so as to be electrically connected at least in part, and baked to use the metal particles in the conductive ink as a second high-frequency circuit. A second feature is that it includes at least a second high-frequency circuit forming step that is fixedly formed thereon.

According to the second aspect of the present invention, the method of manufacturing a high frequency circuit structure includes a first high frequency circuit forming step of forming a first high frequency circuit made of a conductive metal in a predetermined region on a base material made of an insulating resin. And applying a conductive ink containing metal particles to another predetermined region on the substrate so as to be electrically connected to at least a part of the first high-frequency circuit, and firing the metal particles in the conductive ink. Since the second high-frequency circuit includes at least a second high-frequency circuit forming step that is fixedly formed on the base material, the first high-frequency circuit and the second high-frequency circuit are formed in different steps. The high frequency circuit can be formed with a configuration (shape, length, etc.) different from that of the first high frequency circuit. Therefore, the second high-frequency circuit itself can be used as a passive circuit such as a conductor (C), and a high-frequency circuit structure capable of realizing good electrical characteristics can be manufactured. Further, since the second high-frequency circuit itself can be used as a passive circuit such as a conductor (C), there is no need to mount a chip component or the like, and in particular when a printed wiring board having a high-frequency circuit structure is formed, The thickness (height) of the wiring board can be effectively suppressed, and a high-frequency circuit structure that can reduce the size of the printed wiring board can be manufactured.
Further, the second high-frequency circuit is formed into a desired configuration (shape, shape) by applying and baking a conductive ink containing metal particles on a base material and forming the second high-frequency circuit with the metal particles in the conductive ink. The length, width, thickness, etc.) can be accurately formed. Therefore, it is possible to manufacture a high-frequency circuit structure that can realize even better electrical characteristics. Also, the second high-frequency circuit can be easily formed on the substrate without the need for expensive vacuum equipment necessary for physical vapor deposition such as sputtering for the formation of the second high-frequency circuit, and without using an organic adhesive. Can do. Therefore, the second high-frequency circuit can be easily formed, and the manufacturing process can be made more efficient and the manufacturing cost can be reduced.

  In addition to the second feature of the present invention described above, the method for manufacturing a high-frequency circuit structure according to the present invention is further characterized in that the step of applying the conductive ink containing the metal particles on the substrate is performed by ink jet printing. 3 features.

According to the third aspect of the present invention, in addition to the function and effect of the second aspect of the present invention, the step of applying the conductive ink containing the metal particles on the substrate is performed by ink jet printing. Therefore, the second high-frequency circuit can be formed more efficiently and accurately according to the desired configuration (shape, length, width, thickness, etc.). Therefore, it is possible to manufacture a high-frequency circuit structure that can realize even better electrical characteristics. Further, it is possible to further improve the manufacturing efficiency and the manufacturing cost.
Moreover, the length and width | variety of a 2nd high frequency circuit can be increased in steps by using inkjet printing. Therefore, the second high-frequency circuit can be easily finely adjusted, and a high-frequency circuit structure that can realize much better electrical characteristics can be manufactured.

According to the high frequency circuit structure of the present invention, a high frequency circuit structure capable of realizing good electrical characteristics can be obtained. In particular, when a printed wiring board having a high-frequency circuit structure is formed, a high-frequency circuit structure that can reduce the size of the printed wiring board can be obtained. In addition, the second high-frequency circuit can be easily formed, and the manufacturing process can be made more efficient and the manufacturing cost can be reduced.
Further, according to the method for manufacturing a high-frequency circuit structure of the present invention, a high-frequency circuit structure capable of realizing good electrical characteristics can be manufactured. In particular, when a printed wiring board having a high-frequency circuit structure is formed, a high-frequency circuit structure capable of reducing the size of the printed wiring board can be manufactured. In addition, the second high-frequency circuit can be easily formed, and the manufacturing process can be made more efficient and the manufacturing cost can be reduced.

It is sectional drawing of the principal part which simplifies and shows the manufacturing method of the high frequency circuit structure which concerns on embodiment of this invention. It is sectional drawing of the principal part which simplifies and shows the manufacturing method of the high frequency circuit structure which concerns on embodiment of this invention. It is a top view of the principal part which shows the high frequency circuit structure which concerns on embodiment of this invention. It is sectional drawing which shows the principal part of the conventional high frequency circuit structure.

  With reference to the following drawings, a high-frequency circuit structure K according to an embodiment of the present invention and a method for manufacturing the high-frequency circuit structure K will be described for understanding of the present invention. However, the following description is an embodiment of the present invention, and does not limit the contents described in the claims.

  First, referring to FIGS. 1 to 3, a high-frequency circuit structure K according to an embodiment of the present invention and a method for manufacturing the high-frequency circuit structure K are described. A printed wiring comprising the high-frequency circuit structure K according to an embodiment of the present invention. The method for manufacturing the plate 1 will be described.

The manufacturing method of the printed wiring board 1 which concerns on embodiment of this invention is a manufacturing method of the printed wiring board provided with the high frequency circuit structure K. FIG. More specifically, by providing a discontinuous part of the circuit shape in a predetermined region (specific region) of the high-frequency circuit, the high-frequency circuit itself can be a passive component such as a capacitor (C), It is a manufacturing method of a printed wiring board provided with the high frequency circuit structure K which can aim at matching.
Here, the “passive component” means a component that consumes, stores, and discharges the supplied power, such as a capacitor (C), an inductance (L), a resistance (R), and the like.
This method for manufacturing a printed wiring board includes a laminate preparation step A, a high-frequency circuit formation step B, and an insulating layer formation step C.

First, referring to FIG. 1 (a), a laminate 1 a serving as an original plate for forming the printed wiring board 1 is prepared by a laminate preparation step A.
This laminated board 1a is comprised from the base material 10 and the conductive layer 20 formed in both front and back surfaces of the base material 10, as shown to Fig.1 (a).

The said base material 10 becomes a base of the laminated board 1a, and is formed with the insulating resin film.
As a resin film, what consists of a resin material excellent in the softness | flexibility is used. For example, any film may be used as long as it is normally used as a resin film for forming a substrate of a printed wiring board, such as a polyimide film or a polyester film.
In particular, those having high heat resistance in addition to flexibility are desirable. For example, polyamide resin films, polyimide resin films such as polyimide and polyamideimide, and polyethylene naphthalate can be preferably used.
As the heat resistant resin, any resin such as polyimide resin or epoxy resin may be used as long as it is normally used as a heat resistant resin for forming a printed wiring board.
In addition, the thickness of the base material 10 can be appropriately changed according to the design characteristic value of the high-frequency circuit structure K.

The conductive layer 20 is a layer made of a conductive metal formed on the base material 10 and is a layer constituting an electrode, a circuit (wiring), or the like of the printed wiring board 1.
The conductive layer 20 can be formed by a known forming method such as forming a conductive metal foil on the substrate 10 by plating (so-called additive method).
In the present embodiment, copper (Cu) is used as the conductive metal foil. Of course, it is not restricted to copper (Cu), What can be normally used as a conductive metal foil which forms the conductive layer of a printed wiring board can be used.
Further, the thickness of the conductive layer 20 can be appropriately changed according to the design characteristic value of the high-frequency circuit structure K.

Next, with reference to FIG. 1B to FIG. 2A, a high frequency circuit is formed in a predetermined region on the substrate 10 by a high frequency circuit forming step B. The high frequency circuit forming step B includes a first high frequency circuit forming step B1 and a second high frequency circuit forming step B2.
First, referring to FIG. 1B, a known exposure process and development using a pattern mask 40 or the like for the conductive layer 20 formed on the upper surface of the substrate 10 in the first high-frequency circuit forming step B1. The first high-frequency wave formed by patterning the wiring in a predetermined region of the conductive layer 20 (the region excluding the passive component forming region P, which is a region in which the second high-frequency circuit 21b described later is formed in the laminated plate 1a). A circuit 21a is formed.
More specifically, the first high-frequency circuit 21 a is formed by etching away the conductive layer 20 corresponding to the passive component formation region P from the conductive layer 20 formed on the upper surface of the base material 10.
The exposure amount, the exposure time, and the like can be appropriately changed according to the design value of the first high frequency circuit 21a to be formed.
In this embodiment, as shown in part in FIG. 1C, the conductive layer 20 formed on the lower surface of the base material 10 is used as a so-called solid ground circuit 22, and therefore in the high-frequency circuit forming step B. No processing is performed. Therefore, in the process of forming the first high-frequency circuit 21a (etching process or the like), each process is performed with the conductive layer 20 formed on the lower surface of the base material 10 covered with a protective film (not shown).
Thus, as shown in FIGS. 1C and 3, the first high-frequency circuit 21a is formed, and a so-called microstrip line is formed.
The thickness of the first high-frequency circuit 21a can be changed as appropriate according to the design characteristic value of the high-frequency circuit structure K.

Next, referring to FIG. 1C and FIG. 2A, the second high-frequency circuit 21b is formed in the passive component forming region P by the second high-frequency circuit forming step B2.
More specifically, first, a conductive ink containing metal particles is applied to the passive component forming region P.
In addition, the process of apply | coating the conductive ink containing a metal particle to the passive component formation area P is performed by inkjet printing using the application means 50 shown to Fig.2 (a). More specifically, as shown in FIG. 3, the passive component forming region P sandwiched between the pair of first high-frequency circuits 21a is electrically conductive so as to have a desired shape, width, and length using ink jet printing. Apply ink.
In the present embodiment, as shown in FIG. 3, the conductive ink is applied on the base material 20 so as to form an open stub having a substantially cross shape. At this time, the width of the wiring formed in the direction orthogonal to the direction in which the signal is transmitted (indicated by the white arrow) (width in the short direction) is formed in the direction parallel to the direction in which the signal is transmitted. The conductive ink is applied so as to be wider (larger) than the width (width in the short direction). Furthermore, the width of the wiring formed in the direction parallel to the direction in which the signal is transmitted (width in the short direction) is smaller (smaller) than the width (width in the short direction) of the first high-frequency circuit 21a. Apply a functional ink.
In FIG. 3, for convenience of explanation, the insulating layer 30 is omitted from the illustration.
Further, in the step of applying the conductive ink containing metal particles on the substrate 10, as shown in FIG. 2A, the first high frequency circuit 21a already formed and the second high frequency circuit 21b to be formed from now on. The conductive ink is applied on the base material 10 so as to overlap the first high-frequency circuit 21a so that at least a portion of the conductive ink is electrically connected. More specifically, in this embodiment, as shown in FIGS. 2 and 3, each of the pair of wirings formed in a direction parallel to the direction in which a signal is transmitted (indicated by a white arrow) is used. Conductive ink is applied on the substrate 10 so as to be electrically connected to the first high-frequency circuit 21a at the end.
Thereafter, the applied conductive ink is baked by a heat treatment step (not shown), and the metal particles in the conductive ink are fixedly formed on the substrate 10 as the second high-frequency circuit 21b.
As a result, as shown in FIGS. 2A and 3, the second high-frequency circuit 21 b as a layer is formed on the substrate 10 by applying and firing the conductive ink containing metal particles.
As described above, as shown in FIG. 3, the high-frequency circuit structure K including the high-frequency circuit 21 is formed on the substrate 10 by forming the high-frequency circuit 21 including the discontinuous portion of the circuit shape. The
The length, width, and thickness of the second high frequency circuit 21b can be appropriately changed according to the design characteristic value of the high frequency circuit structure K.

  In the present embodiment, the conductive ink is configured to include a metal particle as a conductive substance that provides conductivity, a dispersant that disperses the metal particle, and a dispersion medium.

  In the present embodiment, nickel (Ni) is used as the metal particles. Of course, the present invention is not limited to nickel (Ni), and other than nickel (Ni), one or more elements of copper (Cu), titanium (Ti), vanadium (V) and oxides thereof are used. can do.

  The size of the metal particles contained in the conductive ink is desirably a particle size of about 1 nm to 500 nm. This particle size is significantly smaller than that for normal coating, and is suitable for obtaining a dense conductive thin film. When the particle diameter is less than 1 nm, the dispersibility and stability in the ink are not necessarily good, and the particles are too small, and it takes time and effort to coat the layers. Moreover, when exceeding 500 nm, it is easy to precipitate and it becomes easy to produce an unevenness | corrugation when apply | coating. In consideration of dispersibility, stability, unevenness prevention, and the like, it is preferable to use a material having a thickness of 30 nm to 100 nm.

  Further, the metal particles contained in the conductive ink can be obtained by a titanium redox method. Here, the “titanium redox method” means a method in which metal element ions are reduced by a redox action when trivalent Ti ions are oxidized to tetravalent, and metal particles are precipitated. . The metal particles obtained by the titanium redox method have a small particle size, are uniform, and can be spherical or granular in shape, so that the second high-frequency circuit 21b can be thin and formed in a dense layer. .

  The viscosity of the conductive ink is preferably about 0.1 Pa · s to 100 Pa · s, more preferably about 1 Pa · s to 20 Pa · s. This is because if it is less than 0.1 Pa · s, the ink drips after printing, and if it exceeds 100 Pa · s, the flying shape (the shape that flies from the nozzle) is poor, and printing cannot be performed well.

Next, referring to FIG. 2B, an insulating layer 30 made of an insulating resin is formed on the surfaces of the first high-frequency circuit 21 a, the second high-frequency circuit 21 b, and the ground circuit 22 by an insulating layer forming step C.
More specifically, the insulating layer 30 is formed by attaching an insulating film including an insulating adhesive layer and an insulating resin layer to the surfaces of the first high-frequency circuit 21a, the second high-frequency circuit 21b, and the ground circuit 22. Form.
As the insulating adhesive for forming the insulating adhesive layer, any adhesive can be used as long as it is usually used as an insulating adhesive for forming a printed wiring board, such as an epoxy adhesive.
As the insulating resin for forming the insulating resin layer, any material, property, etc. can be used as long as it is normally used as an insulating resin for forming an insulating layer in a printed wiring board, such as a polyimide film. Also good.

  By passing through the above process, the printed wiring board 1 provided with the high frequency circuit structure K which concerns on embodiment of this invention is formed.

  Hereinafter, the high-frequency circuit structure K according to the embodiment of the present invention, the manufacturing method of the high-frequency circuit structure K, the configuration of the printed wiring board 1 including the high-frequency circuit structure K according to the embodiment of the present invention, and the manufacturing method will be further detailed. Explained.

(Method for producing metal particles)
The manufacturing method of a metal particle includes the titanium redox method mentioned above, and the following manufacturing methods are possible.
The metal particles can be produced by a conventionally known method such as a high temperature treatment method called an impregnation method, a liquid phase reduction method, or a gas phase method.
In order to produce metal particles by the liquid phase reduction method, for example, in water, a water-soluble metal compound that is a source of metal ions forming the metal particles and a dispersant are dissolved, and a reducing agent is added. Preferably, the metal ion may be subjected to a reduction reaction for a certain time under stirring. Of course, when metal particles made of an alloy are produced by a liquid phase reduction method, two or more water-soluble metal compounds are used.
In the case of the liquid phase reduction method, the produced metal particles are spherical or granular in shape, have a sharp particle size distribution, and can be made into fine particles.
For example, in the case of Ni, nickel (II) chloride hexahydrate [NiCl ₂ .6H ₂ O], nickel nitrate (II) hexahydrate [Ni ( NO ₃ ) ₂ · 6H ₂ O]. In the case of Cu, copper nitrate (II) [Cu (NO ₃ ) ₂ ] and copper sulfate (II) pentahydrate [CuSO ₄ .5H ₂ O] can be exemplified. For other metal particles, water-soluble compounds such as chlorides, nitric acid compounds and sulfuric acid compounds can be used.

(Reducing agent)
As a reducing agent when producing metal particles by the oxidation-reduction method, various reducing agents capable of reducing and precipitating metal ions in a liquid phase (aqueous solution) reaction system can be used. For example, sodium borohydride, sodium hypophosphite, hydrazine, transition metal ions such as trivalent titanium ions and divalent cobalt ions, reducing sugars such as ascorbic acid, glucose and fructose, ethylene glycol, glycerin, etc. Mention may be made of polyhydric alcohols. Among these, the titanium redox method described above is a method of reducing and precipitating metal ions by redox action when trivalent titanium ions are oxidized to tetravalent.

(Dispersant for conductive ink)
As the dispersant contained in the conductive ink, various dispersants having a molecular weight of 2000 to 30000 and capable of favorably dispersing the metal particles precipitated in the dispersion medium can be used. By using a dispersant having a molecular weight of 2000 to 30000, the metal particles can be favorably dispersed in the dispersion medium, and the film quality of the obtained second high-frequency circuit 21b can be made dense and defect-free. . If the molecular weight of the dispersant is less than 2000, the effect of preventing the aggregation of metal particles and maintaining the dispersion may not be obtained sufficiently. As a result, the second high-frequency circuit laminated on the insulating base material 10. There is a possibility that 21b cannot be made dense and has few defects. On the other hand, when the molecular weight exceeds 30000, the bulk is too large, and in the heat treatment performed after the application of the conductive ink, the sintering of the metal particles is inhibited to generate voids, or the film quality of the second high-frequency circuit 21b is dense. Or the decomposition residue of the dispersant may lower the conductivity.
In addition, it is preferable that the dispersant does not contain sulfur, phosphorus, boron, halogen and alkali from the viewpoint of preventing the deterioration of parts.
Preferred dispersants are those having a molecular weight in the range of 2000 to 30000, having amine-based polymer dispersants such as polyethyleneimine and polyvinylpyrrolidone, and having a carboxylic acid group in the molecule such as polyacrylic acid and carboxymethylcellulose. Hydrocarbon polymer dispersant, poval (polyvinyl alcohol), styrene-maleic acid copolymer, olefin-maleic acid copolymer, or copolymer having a polyethyleneimine moiety and a polyethylene oxide moiety in one molecule And a polymer dispersant having a polar group of
The dispersant can be added to the reaction system in the form of a solution dissolved in water or a water-soluble organic solvent.
It is preferable that the content rate of a dispersing agent is 1-60 weight part per 100 weight part of metal particles. When the content ratio of the dispersant is less than the above range, there is a possibility that the effect of preventing the aggregation by dispersing the metal particles around the metal particles in the conductive ink containing water is insufficient. When the above range is exceeded, during the baking heat treatment after the coating of the conductive ink, the excessive dispersant inhibits the baking including the sintering of the metal particles, thereby causing voids or reducing the denseness of the film quality. In addition, the decomposition residue of the polymer dispersant may remain in the second high-frequency circuit 21b as an impurity, and the conductivity of the printed wiring board 1 may be reduced.

(Metallic particle size adjustment)
To adjust the particle size of the metal particles, adjust the type and blending ratio of the metal compound, dispersant, and reducing agent, and adjust the stirring speed, temperature, time, pH, etc. when the metal compound is reduced. That's fine.
For example, the pH of the reaction system is preferably 7 to 13 in order to obtain particles having a fine particle size as in the present invention.
In order to adjust the pH of the reaction system to 7 to 13, a pH adjusting agent can be used. As this pH adjuster, common acids and alkalis such as hydrochloric acid, sulfuric acid, sodium hydroxide and sodium carbonate are used. In particular, in order to prevent deterioration of peripheral members, alkali metals and alkaline earth metals, Nitric acid and ammonia which do not contain a halogen element such as chlorine and impurity elements such as sulfur, phosphorus and boron are preferable.
In the embodiment of the present invention, metal particles having a particle diameter in the range of 30 to 100 nm are used, but it is possible to use those having a particle diameter in the range of 1 to 500 nm as an allowable range.
Here, the particle diameter is represented by the center diameter D50 of the particle size distribution in the dispersion, and was measured using a Microtrac particle size distribution meter (UPA-150EX) manufactured by Nikkiso Co., Ltd.

(Adjustment of conductive ink)
The metal particles deposited in the liquid phase reaction system can be adjusted to a conductive ink using a powder once passed through processes such as separation, washing, drying, and crushing. In this case, powdered metal particles, water as a dispersion medium, a dispersant, and if necessary, a water-soluble organic solvent are blended at a predetermined ratio, and a conductive ink containing metal particles can do.
Preferably, the conductive ink is prepared using a liquid phase (aqueous solution) reaction system in which metal particles are deposited as a starting material.
That is, the liquid phase (aqueous solution) of the reaction system containing the precipitated metal particles is subjected to treatments such as ultrafiltration, centrifugation, washing with water, and electrodialysis to remove impurities, and if necessary, concentrated to remove water. Or, conversely, after adjusting the concentration of the metal particles by adding water, if necessary, a conductive ink containing the metal particles is prepared by blending a water-soluble organic solvent in a predetermined ratio. In this method, generation of coarse and irregular particles due to aggregation of metal particles during drying can be prevented, and a dense and uniform second high-frequency circuit 21b can be obtained.

(Dispersion medium)
The ratio of water serving as a dispersion medium in the conductive ink is preferably 20 to 1900 parts by weight per 100 parts by weight of the metal particles. If the water content is less than the above range, the effect of dispersing the water-based dispersant sufficiently and dispersing the metal particles surrounded by the dispersant may be insufficient. When the water content exceeds the above range, the ratio of the metal particles in the conductive ink decreases, and a good coating layer having the necessary thickness and density cannot be formed on the surface of the insulating substrate 10. There is a fear.

The organic solvent blended into the conductive ink as necessary can be various water-soluble organic solvents. Specific examples thereof include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol and tert-butyl alcohol, ketones such as acetone and methyl ethyl ketone, Examples thereof include polyhydric alcohols such as ethylene glycol and glycerin and other esters, and glycol ethers such as ethylene glycol monoethyl ether and diethylene glycol monobutyl ether.
The content ratio of the water-soluble organic solvent is preferably 30 to 900 parts by weight per 100 parts by weight of the metal particles. If the content ratio of the water-soluble organic solvent is less than the above range, the effect of adjusting the viscosity and vapor pressure of the dispersion due to the inclusion of the organic solvent may not be sufficiently obtained. When the above range is exceeded, there is a possibility that the effect of dispersing the metal particles in the conductive ink satisfactorily without causing aggregation by sufficiently swelling the dispersant with water.

(Heat treatment of conductive ink)
By heat-treating the conductive ink applied on the insulating substrate 10, the second high-frequency circuit 21b fixed on the substrate 10 as a baked coating layer is obtained.
By heat treatment, the dispersant and other organic substances contained in the applied conductive ink are volatilized and decomposed by heat to remove them from the coating layer, and the remaining metal particles are in a sintered state or a stage before sintering. Then, they are firmly fixed on the insulating base material 10 as if they were in close contact with each other and solid-bonded.
The heat treatment may be performed in the air. Further, in order to prevent oxidation of the metal particles, it may be further fired in a reducing atmosphere after firing in the air. The firing temperature can be set to 700 ° C. or less from the viewpoint of suppressing the metal crystal grain size of the second high-frequency circuit 21b formed by the firing from becoming too large or the generation of voids.
Of course, the heat treatment is performed at a temperature of 500 ° C. or less in consideration of the heat resistance of the insulating base material 10 when the insulating base material 10 is an organic resin such as polyimide. The lower limit of the heat treatment temperature is preferably 150 ° C. or higher in consideration of the purpose of removing organic substances other than metal particles contained in the conductive ink from the coating layer.
Further, as the heat treatment atmosphere, considering that the metal particles to be laminated are extremely fine, in order to prevent the oxidation well, for example, the O ₂ concentration was decreased, for example, the O ₂ concentration was set to 1000 ppm or less. A non-oxidizing atmosphere can be obtained. Furthermore, for example, a reducing atmosphere can be obtained by containing hydrogen at a concentration lower than the lower explosion limit (3%).
Thus, the second high-frequency circuit forming step B2 is completed by applying the conductive ink onto the insulating base material 10 and heat-treating the coating layer.

  The high-frequency circuit structure K according to the embodiment of the present invention configured as described above, the method for manufacturing the high-frequency circuit structure K, and the printed wiring board 1 including the high-frequency circuit structure K according to the embodiment of the present invention are as follows. There is an effect.

A configuration in which the second high-frequency circuit 21b is formed in a shape (discontinuous shape) different from the shape of the first high-frequency circuit 21a (in the present embodiment, the second high-frequency circuit 21b is formed as an open stub having a substantially cross shape). The second high-frequency circuit 21b itself can be used as a passive circuit such as a conductor (C), an inductance (L), and a resistance (R) for matching electric characteristics. Therefore, the high-frequency circuit structure K that can realize good electrical characteristics can be manufactured. Further, the high-frequency circuit structure K and the printed wiring board 1 that can realize good electrical characteristics can be obtained. Further, since the second high-frequency circuit 21b itself can be used as a passive circuit such as a conductor (C), it is not necessary to mount a chip component or the like, and when the printed wiring board 1 including the high-frequency circuit structure K is formed, Accordingly, the thickness (height) of the printed wiring board 1 can be effectively suppressed, and the high-frequency circuit structure K capable of reducing the size of the printed wiring board 1 can be manufactured. In addition, the printed circuit board 1 can be miniaturized, and the printed circuit board 1 can be miniaturized.
Further, the second high-frequency circuit 21b is formed in a desired design by applying the conductive ink containing metal particles onto the base material 10 and baking it to form the second high-frequency circuit 21b with the metal particles in the conductive ink. It can be formed with high accuracy in accordance with the configuration (shape, length, width, thickness, etc.). Therefore, the high-frequency circuit structure K that can realize good electrical characteristics can be manufactured. Further, the high-frequency circuit structure K and the printed wiring board 1 that can realize good electrical characteristics can be obtained. Furthermore, the second high-frequency circuit 21b can be easily formed on the substrate 10 without the need for expensive vacuum equipment necessary for physical vapor deposition such as sputtering and the use of an organic adhesive. Can be formed. Therefore, the second high-frequency circuit 21b can be easily formed, and the manufacturing process can be made more efficient and the manufacturing cost can be reduced.
In addition, as a process of applying the conductive ink on the base material 10, by using ink jet printing, a desired configuration (shape, length, width, thickness, etc.) is pinpointed to the passive component forming region P. A coating layer made of conductive ink can be formed. Therefore, the second high-frequency circuit 21b can be formed more efficiently and accurately in accordance with a desired configuration (shape, length, width, thickness, etc.). Therefore, the high-frequency circuit structure K that can realize much better electrical characteristics can be manufactured. Further, the high-frequency circuit structure K and the printed wiring board 1 that can realize even better electrical characteristics can be obtained. Further, it is possible to further improve the manufacturing efficiency and the manufacturing cost.
Furthermore, as a process of applying the conductive ink on the base material 10, the length and width of the second high-frequency circuit 21 b can be increased step-by-step (afterward) by using ink jet printing, and fine adjustment is performed. The high frequency circuit 21b can be formed while performing the above. More specifically, as shown in FIG. 3, the conductive ink is first applied and baked on the base material 10 in the configuration shown by the broken line, and the metal particles are fixedly formed on the base material 10. A coating layer is formed. After that, when the electrical characteristics are measured and a desired measurement value cannot be obtained, the conductive ink is applied and fired on the base material 10 and the conductive ink coating layer, and the metal particles are fixedly formed. Thus, it is possible to form the second high-frequency circuit 21b capable of realizing the measured value. That is, the second high-frequency circuit 21b can be formed while measuring the electrical characteristics of the high-frequency circuit structure. Therefore, the fine adjustment of the second high-frequency circuit 21b can be easily performed, and the high-frequency circuit structure K that can realize better electrical characteristics can be manufactured more efficiently and accurately. Further, the high-frequency circuit structure K and the printed wiring board 1 that can realize even better electrical characteristics can be obtained.

On the other hand, in the conventional high-frequency circuit structure K and the conventional printed wiring board 2 provided with the high-frequency circuit structure K, as shown in FIG. In general, a chip component 6 (a so-called passive element) such as a chip capacitor is mounted via a capacitor to achieve matching of electric characteristics.
However, in the printed wiring board 2 on which the chip component 6 is mounted, the total thickness (height) of the printed wiring board 2 is increased by the thickness (height) of the chip component 6. There was a problem that the size of 2 could not be reduced. There is also a problem that the chip component 6 may come off when the printed wiring board 2 is hit against something.
For such a problem, although not shown in the drawings, a high-frequency circuit is formed by etching a wiring made of a conductive metal such as copper, and this high-frequency circuit itself is used as a passive circuit such as a conductor (C). There was a printed wiring board provided with a high-frequency circuit structure.
However, in such a configuration, when it is desired to finely adjust the characteristics of the manufactured high-frequency circuit, it is necessary to recreate the etching mask, and there is a problem in that it is impossible to realize the efficiency of the manufacturing process and the reduction of the manufacturing cost. It was.

Therefore, the high-frequency circuit structure K according to the embodiment of the present invention, the manufacturing method of the high-frequency circuit structure K, and the configuration of the printed wiring board 1 including the high-frequency circuit structure K can realize good electrical characteristics. A high-frequency circuit structure K that can be manufactured is manufactured. Further, the high-frequency circuit structure K and the printed wiring board 1 that can realize good electrical characteristics can be obtained.
Moreover, the high frequency circuit structure K which can achieve size reduction of the printed wiring board 1 can be manufactured. In addition, the printed circuit board 1 can be miniaturized, and the printed circuit board 1 can be miniaturized.
Further, the second high-frequency circuit 21b can be easily formed, and the manufacturing process can be made more efficient and the manufacturing cost can be reduced.

The shape of the second high-frequency circuit 21b is not limited to that of the present embodiment, and can be changed as long as the shape can match the electrical characteristics of the high-frequency circuit structure K to a desired characteristic value (design value). Is possible.
In the present embodiment, the second high-frequency circuit 21b is formed as an open stub. However, the present invention is not limited to such a configuration, and other configurations (for example, a short stub) may be used.
In the present embodiment, the configuration of the high-frequency circuit structure K is a so-called microstrip line in which the high-frequency circuit 21 is provided on the upper surface of the base material 10 made of an insulating resin and the ground circuit 22 is provided on the lower surface of the base material 10. However, the present invention is not necessarily limited to such a configuration, and may be a high-frequency circuit structure K including the high-frequency circuit 21 having a discontinuous circuit shape in the second high-frequency circuit 21b. The configuration of the high-frequency circuit structure K can be changed as appropriate.
In the present embodiment, the printed wiring board 1 is used as a structure having the high-frequency circuit structure K. However, the structure is not necessarily limited to such a structure, and the structure having the high-frequency circuit structure K can be changed as appropriate. It is. In other words, any structure may be used as long as the structure has a high-frequency circuit structure K including a high-frequency circuit on a base material made of at least an insulating resin. Here, the “structure having the high-frequency circuit structure K” refers to a structure including a part of the high-frequency circuit structure K and a structure including the high-frequency circuit structure K itself (a structure including only the high-frequency circuit structure K). It is a concept including any of the above.

  According to the present invention, good electrical characteristics can be realized in a high-frequency circuit structure including a high-frequency circuit, and therefore, industrial applicability in the field of a printed wiring board including the high-frequency circuit structure is high.

DESCRIPTION OF SYMBOLS 1 Printed wiring board 1a Laminated board 2 Printed wiring board 3 Base material 4 Conductive layer 4a High frequency circuit 4b Ground circuit 5 Insulating layer 6 Chip component 10 Base material 20 Conductive layer 21 High frequency circuit 21a 1st high frequency circuit 21b 2nd high frequency circuit 22 Ground Circuit 30 Insulating layer 40 Pattern mask 50 Coating means A Laminate plate preparation process B High frequency circuit forming process B1 First high frequency circuit forming process B2 Second high frequency circuit forming process C Insulating layer forming process H Solder K High frequency circuit structure P Passive component forming region

Claims (3)

  A high frequency comprising a base material made of an insulating resin, a first high frequency circuit made of a conductive metal provided on the base material, and a second high frequency circuit electrically connected to at least a part of the first high frequency circuit. A high-frequency circuit structure having a circuit structure, wherein the second high-frequency circuit is configured as a layer formed by applying and baking a conductive ink containing metal particles.   A first high-frequency circuit forming step of forming a first high-frequency circuit made of a conductive metal in a predetermined region on a base material made of an insulating resin; and metal particles so as to be electrically connected at least partially to the first high-frequency circuit. A second high-frequency circuit forming step of applying and firing a conductive ink containing a metal to another predetermined region on the base material, and fixing the metal particles in the conductive ink on the base material as a second high-frequency circuit; A method for manufacturing a high-frequency circuit structure, comprising:   The method for manufacturing a high-frequency circuit structure according to claim 2, wherein the step of applying the conductive ink containing the metal particles on the substrate is performed by ink jet printing.

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