JP2022003669A - Circuit wiring board and manufacturing method thereof - Google Patents

Abstract

To provide a circuit wiring board in which an electrode having high adhesion strength to a base material film is formed and which is suitable for millimeter-wave band communication.SOLUTION: A circuit wiring board is a circuit wiring board in which an electrode is formed directly in contact with a surface of a base material film. A main component of the base material film is a cyclic olefin resin with a crystallinity of 1%-30%. Arithmetic mean roughness Ra of the surface of the base material film is 0.01-0.3 μm. The electrode is a metal film with a thickness of 3-20 times the arithmetic mean roughness Ra of the basic material film.SELECTED DRAWING: Figure 1

Description

The present invention relates to a circuit wiring board in which electrodes are formed on a base film, and is applied to a photoelectric conversion element (optical modulator) in a next-generation communication network by forming an optical waveguide or the like on the circuit wiring board of the present invention. can. In optical communication using optical fibers, photoelectric conversion elements (optical modulators, etc.) modulate the intensity of a light source using a conversion circuit to convert an electrical signal into an optical signal, and vice versa. It is a device that converts to.

The cyclic olefin resin used for the base film of the present invention is a resin having extremely low water absorption, low moisture permeability, and extremely excellent dielectric properties, and is expected to be used in next-generation communication networks. It is also listed as one of the candidates for circuit board materials compatible with millimeter-wave charged waves.

・・・式（１） Conventionally, there has been the invention of Patent Document 1 as an invention of a circuit wiring board (touch sensor) in which an electrode is formed on a base film made of a cyclic olefin resin. In the invention of Patent Document 1, the base film is composed mainly of hydrogenated ring-opening metathesis polymer of the ring structure substituent R ₁ and R ₂ of formula (1) is led, the electrode is made of copper electrodes touch It was an invention of a sensor, and was characterized by being compatible with transparency, heat resistance, and the like.

... Equation (1)

Patent No. 6267056

However, hydrogenated ring-opening metathesis polymer of the substituents R ₁ and R ₂ are linked ring structure of formula (1) as described above, to become a more amorphous the ring structure increases. Although the transparency is excellent, there is a problem that the dielectric property tends to be slightly deteriorated. Since high transparency is an essential characteristic for touch sensor applications, it is permissible even if the high dielectric property deteriorates to some extent, but in circuit wiring boards for photoelectric conversion elements that support millimeter-wave band communication that require high dielectric property, Such properties were unsuitable.

In addition, the more amorphous, the more chemically the adhesion with the electrode such as a metal material is lowered, and the smoother the surface, the more physically the adhesion with the electrode is lowered. .. Therefore, in order to maintain a constant adhesion strength, it is necessary to provide an anchor layer made of another material between the base film and the electrode such as a metal material, and due to the relatively low dielectric property performance of the anchor layer. There is a problem that the dielectric property of the entire circuit wiring board is significantly deteriorated. The present inventions have invented the following circuit wiring boards in order to solve these problems.

That is, the first characteristic configuration of the present invention is a circuit wiring board in which an electrode is formed in direct contact with the surface of a base film, and the base film is a cyclic olefin having a crystallinity of 1% to 30%. The main component is a based resin, and the arithmetic mean roughness Ra of the surface of the base film is 0.01 to 0.3 μm, and the electrode is 3 to 20 times the arithmetic average roughness Ra of the surface of the base film. It is a circuit wiring board that is a thick metal film.

・・・式（１） The second characteristic configuration of the present invention is that the electrode has an antenna receiving or transmitting electrode pattern formed on one surface of the base film and a ground formed on the other surface of the base film. It is a circuit wiring board composed of electrodes. A third aspect of the present invention, the cyclic olefin resin, the structure of the not connected and the substituents _{R 1} and _{R 2} of formula (1), and _{C n H 2n + 1 (n} = 0~8) It is a circuit wiring board consisting of.

... Equation (1)

Further, the fourth characteristic configuration of the present invention is a circuit wiring board in which an optical waveguide is formed on the upper part of the electrode. The fifth characteristic configuration of the present invention is to irradiate the surface of the base film with ultraviolet rays or plasma treatment so that the arithmetic average roughness Ra of the surface is 0.01 to 0.3 μm, and the surface thereof is described. This is a method for manufacturing a circuit wiring board for forming an electrode which is a metal film having a thickness of 3 to 20 times the arithmetic average roughness Ra.

According to the first characteristic configuration of the present invention, the circuit wiring board of the present invention is a circuit wiring board in which electrodes are formed in direct contact with the surface of the base film, and the base film has a degree of crystallization. The main component is 1% to 30% cyclic olefin resin, the arithmetic mean roughness Ra of the surface of the base film is 0.01 to 0.3 μm, and the electrode has the arithmetic mean roughness of the surface of the base film. It is characterized by having a metal film having a thickness of 3 to 20 times that of Ra. Therefore, the CH bonds in the crystalline portion of the base film are oriented almost regularly and densely, and the surface of the base film also has appropriate irregularities suitable for millimeter wave band communication, and the metal film has appropriate irregularities. Since the electrode is also in the thickness range adapted to the unevenness of the surface of the base film, if a treatment of cutting a part of the CH bond and modifying it into a functional group compatible with the electrode material is performed, the base film can be formed. There is an effect that it is possible to obtain a circuit wiring board suitable for millimeter wave band communication in which an electrode having a high adhesion strength is formed.

Further, according to the second characteristic configuration of the present invention, the electrodes are formed on the antenna receiving or transmitting electrode pattern formed on one surface of the substrate film and on the other surface of the substrate film. It is characterized by being a circuit wiring board composed of a ground electrode. Therefore, since the ground electrode and the base film shield the noise of the radio wave coming from the back surface, there is an effect of improving the antenna reception or transmission performance. Further, since each electrode pattern is formed in direct contact with a base film having high dielectric properties, it is possible to obtain a circuit wiring board suitable for high-performance millimeter-wave band communication with little attenuation of electric signals received or transmitted. There is an effect that can be done.

Further, according to the third characteristic configuration of the present invention, in the cyclic olefin resin, the substituents R ₁ and R _{2 of} the formula (1) are not connected, and C _n H _{2n + 1} (n = 0 to 8). It is characterized by having the structure of. Therefore, since the substituent is not bulky, the main chain of the polymer is easily oriented regularly, which has the effect of facilitating the production of a cyclic olefin resin having many crystalline portions.

Further, according to the fourth characteristic configuration of the present invention, the circuit wiring board of the present invention is a circuit wiring board in which an optical waveguide is formed on an upper portion of an electrode. Therefore, there is an effect of obtaining a photoelectric conversion element using a cyclic olefin resin as a substrate. As a result, there is an effect that a very high-performance photoelectric conversion element suitable for millimeter-wave band communication can be obtained.

Further, according to the fifth characteristic configuration of the present invention, in the method for manufacturing the circuit wiring board of the present invention, the arithmetic average roughness Ra of the surface of the base film is 0.01 to 0.3 μm. Is irradiated with ultraviolet rays or subjected to plasma treatment, and an electrode which is a metal film having a thickness of 3 to 20 times the arithmetic mean roughness Ra is formed on the surface thereof. Therefore, by irradiating with ultraviolet rays or plasma gas, there is an effect that a fine uneven surface suitable for millimeter wave band communication and contributing to improvement of adhesion strength can be formed on the surface of the base film.

It is a schematic sectional drawing which shows an example of the circuit wiring board in the 1st characteristic structure of this invention. It is a schematic perspective view which shows an example of the circuit wiring board in the 2nd characteristic structure of this invention. It is a schematic sectional drawing which shows an example of the circuit wiring board and the photoelectric conversion element in the 4th characteristic structure of this invention. It is a schematic perspective view which shows an example of the circuit wiring board and the photoelectric conversion element in the 4th characteristic structure of this invention.

Hereinafter, embodiments of the circuit wiring board according to the present invention will be described with reference to the drawings. The circuit wiring board 1 of the present invention is a circuit wiring board in which an electrode 20 is formed in direct contact with a base film 10, and the base film 10 is a cyclic olefin having a crystallinity of 1% to 30%. The main component is a based resin, the arithmetic average roughness Ra of the surface of the base film 10 is 0.01 to 0.3 μm, and the electrode 20 is 3 of the arithmetic average roughness Ra of the surface of the base film 10. It is characterized by having a metal film having a thickness of about 20 times (see FIG. 1).

The crystallinity of the cyclic olefin resin of the base film 10 is measured by using an X-ray diffraction method, and the crystalline portion to be the peak shape portion and the amorphous portion to be the baseline portion are fitted. The crystallinity is calculated by substituting each integrated intensity into the following equation. In the equation, X indicates the crystalline scattering integral strength (that is, the scattering integral strength derived from the crystalline portion), and Y indicates the amorphous scattering integral strength (that is, the scattering integral strength derived from the amorphous portion). Is shown.
Crystallinity (%) = [X / (X + Y)] x 100

・・・式（１） Examples of the crystallinity of 1% to 30% of a cyclic olefin resin, the structure of the not connected and the substituents _{R 1} and _{R 2} of formula (1), and _{C n H 2n + 1 (n} = 0~8) Examples thereof include a cyclic olefin resin composed of. When it is cyclic polyolefin polymer substituents R ₁ and R ₂ and led ring structure of formula (1), its bulky length of the main chain each other polymers for substituents away, of the main chain of the polymer Orientation is inhibited, resulting in an amorphous polymer with less than 1% crystalline moiety.

... Equation (1)

By subjecting the surface of the cyclic olefin resin of the base film 10 to some kind of surface modification treatment, a part of the C—H bond is cleaved, and a −OH group and a −COOH group having an affinity with a metal material or the like are cut. By changing to a functional group such as a −CO group, the adhesion strength between the base film 10 and the electrode 20 can be improved.

In particular, since the CH bonds in the crystalline portion are oriented almost regularly and densely, if the portion at that portion is modified to the above-mentioned functional group, the adhesion strength can be effectively improved. Can be done. Therefore, it is possible to effectively improve the adhesion strength higher crystallinity, the substituents R ₁ and R ₂ are preferably towards the C _{n H} 2n _{+ 1} values is low substituents n. If the value of n becomes a large substituent exceeding 8, there is a tendency that there is no big difference from the case of a substituent in which _{R 1} and R _{2 are connected.}

Further, if the fine unevenness 11 is formed on the surface of the base film 10 (see FIG. 1) and the electrode 20 is directly formed on the surface thereof, metal particles or the like bite into the deep portion of the concave portion of the fine unevenness 11. As described above, the adhesion strength between the base film 10 and the electrode 20 can be further improved by the anchor effect.

However, if the surface of the base film 10 is formed into a large concavo-convex shape on the level of several tens of μm to several hundreds of μm as applied by a general plating method, it is possible to base the electric signal moving in the electrode 20. Since the path of the electric signal moving near the interface with the material film 10 is reduced, it is inconvenient to apply it to a circuit board compatible with millimeter-wave charged waves in which the ratio of the electric signal moving near the interface is high. Therefore, it is necessary to newly invent and devise the shape of the fine unevenness 11 that can sufficiently secure the path of the electric signal moving near the interface while maintaining the anchor effect, and the manufacturing method thereof.

As a result of repeated ingenuity and ingenuity to determine how fine the shape of the unevenness 11 is appropriate, the inventors set that the fine unevenness 11 has an arithmetic average roughness Ra of 0.01 to 0.3 μm. It was found that the path of the electric signal moving near the interface can be sufficiently secured while maintaining the effect. That is, if Ra is less than 0.01 μm, sufficient adhesion strength cannot be obtained, and if Ra is larger than 0.3 μm, it is insufficient for application to a circuit board compatible with millimeter-wave charged waves (see Table 1). ).

Further, as a result of repeated diligent efforts on how to manufacture the fine unevenness 11, he invented a method of surface modification by ultraviolet irradiation or plasma treatment under specific conditions. The thermal imprint method is also mentioned as one of the methods, but it is not very suitable for endless mass production with a large area. Further, although the corona discharge treatment used for general purposes can be mentioned as one of the methods, the setting conditions for stably forming the fine unevenness 11 in the above range are narrow.

As a condition for surface modification by ultraviolet irradiation, for example, it is advisable to irradiate the base film 10 to 1 to 3 cm away from the base film 10 for about 3 to 10 minutes using an ultraviolet lamp (see Tables 2 and 3). If the distance is longer than the above or the irradiation time is shortened, the desired fine unevenness 11 cannot be obtained. On the contrary, when the distance is closer than the distance or the irradiation time is lengthened, there is a problem that the unevenness becomes too large or the unevenness of the unevenness becomes too large.

As conditions for surface modification by plasma treatment, for example, using a xenon excimer lamp of vacuum ultraviolet light in an oxygen or carbon tetrafluoride atmosphere, the substrate film 10 is separated from the base film 10 by 0.5 to 2 cm for about 2 to 5 minutes. It is good to irradiate. If the distance is increased or the irradiation time is shortened, the desired fine unevenness 11 cannot be obtained. Conversely, if the distance is shorter or the irradiation time is longer, the unevenness becomes too large or the unevenness becomes too large. There was a problem.

Then, the thickness of the electrode 20 needs to be 3 to 20 times the arithmetic average roughness Ra of the surface of the base film 10. When the thickness of the electrode 20 is less than 30 nm (that is, three times the arithmetic average minimum roughness Ra of the surface of the base film 10 = 0.01 μm), the cross-sectional area of the electrode 20 becomes small and sufficient electric signals are propagated. The route cannot be secured. On the other hand, when the thickness of the electrode 20 exceeds 20 times the arithmetic mean roughness of the surface of the base film 10, the anchor effect is lowered even if the surface of the base film 10 has fine irregularities 11 in a desired range. As a result, the electrode 20 is easily peeled off from the surface of the base film 10.

The electrode 20 is a layer made of a metal film, and examples of the material include a pure conductor metal such as copper, gold, silver, aluminum, nickel, palladium, and indium, a conductive paste film containing the metal, and the metal. It may be a conductive fiber containing or an oxide film containing the metal. Examples of the film forming method of the electrode 20 include a method of forming by sputtering, vacuum vapor deposition, diffusion transfer and the like, in addition to an electrolytic or electroless plating method.

Further, the electrode 20 may be an electrode pattern 201 for receiving or transmitting an antenna that receives a radio wave signal transmitted from the outside or transmits a radio wave signal to the outside. Further, the ground electrode 202 may be used to shield the radio signal noise. Then, the electrode 201 made of the electrode pattern for receiving or transmitting the antenna and the electrode 202 made of the ground electrode for shielding the radio signal noise may be formed on both sides of the base film 10 (see FIG. 2).

By forming the electrodes 201 and 202 having the desired thickness on both sides of the base film 10 made of the desired fine unevenness 11 in this way, the attenuation of the electric signal to be received or transmitted is small, and the antenna is received or transmitted. A circuit wiring board 1 having improved performance can be obtained. Since the electrodes 201 and 202 are formed in direct contact with the base film 10 having high dielectric properties, the circuit wiring board 1 is suitable for high-performance millimeter-wave band communication. As a result, it can be applied to products for various purposes such as millimeter wave light modulators, millimeter wave light receiving batteries, collision prevention millimeter wave radars using optical fibers, antenna converters, marine radars, wireless LANs, FWAs, and ETCs.

Among them, by forming the optical waveguide 3 on the circuit wiring board 1, a next-generation photoelectric conversion element 5 suitable for millimeter-wave band communication, for example, a next-generation millimeter-wave optical modulator can be obtained (FIG. 3). , See Figure 4). The optical waveguide 3 may be formed by, for example, forming a part of a plate-shaped substrate such as lithium niobate having a thickness of about 0.3 mm by changing the refractive index by an annealing proton exchange method. Since light is confined in the optical waveguide 3 due to the difference in refractive index, when light is input from one direction, it is converted according to the input optical signal until the light travels along the optical waveguide 3 and is output. The radio electric signal is transmitted as a radio wave from the electrode pattern 201 of the antenna transmission. Further, it is also possible to convert the radio electric signal of the radio wave received by the electrode pattern 201 of the antenna reception into an optical signal. Examples of the lamination of the plate-shaped substrate and the circuit wiring board include a method of applying and placing a low-dielectric polyimide adhesive.

(Example 1)
As the base film, the substituents R ₁ and R ₂ is a hydrogen atom of the formula (1), ethyl, n- octane group, on both sides of the cyclic olefin resin polymer film having a thickness of 200μm made of the structure of the n- nonane group After irradiating with an ultraviolet lamp having a wavelength of 254 nm at a distance of 2 cm from the substrate film for 10 minutes, a copper sulfate-free copper plating bath (copper sulfate / pentahydrate 0.03 mol / L, formalin 0.3 mol / L) at 25 ° C. Immerse in L, Rochelle salt complexing agent 0.3 mol / L, PH 12.5), followed by an electrolytic copper plating bath at 25 ° C (copper sulfate / pentahydrate 10%, sulfuric acid 18%, hydrochloric acid 0.5%). , 1% of organic additives, etc., 70.5% of ion-exchanged water) to form a copper film having a thickness of 0.3 to 5 μm on both sides.

Table 1 shows the peeling strength results of the copper film with respect to the base film of the obtained circuit wiring board. Relatively copper film is thin enough peel strength is high thickness, tended to higher peel strength smaller substituents R ₁ and R ₂ is high. Then, when measured in advance the crystallinity of the base film, crystallinity smaller functional group substituents R ₁ and R ₂ are a high tendency was observed. Moreover, when the dielectric characteristics of the obtained circuit wiring board at a frequency of 60 GHz were evaluated, the dielectric loss tangent was 0.0008 to 0.0015 and the relative permittivity was as low as 2.3 to 2.7 in all the circuit wiring boards. , was particularly good as _the substituents _{R 1} and _{R 2} are small.

Subsequently, a photosensitive film was attached to both sides of the copper film and exposed and developed using a photomask to obtain a circuit wiring board in which an electrode of an antenna transmission pattern and an electrode of an electromagnetic wave shield pattern were formed. Then, an optical waveguide made of lithium niobate having a thickness of 0.25 mm was laminated on the antenna transmission pattern electrode of the obtained circuit wiring board to produce a photoelectric conversion element. When the obtained photoelectric conversion element is connected to an optical fiber and an optical signal is input from the optical fiber, a wireless electric signal corresponding to the optical signal is emitted from an electrode of an antenna transmission pattern as a radio wave having a frequency of 60 GHz via an optical waveguide. Was confirmed.

When the emitted radio wave with a frequency of 60 GHz was received and evaluated by a receiver 100 m away, the average communication speed was 1.2 Gb / s, the transmission density was ^{5 to} 8 Gb / s per ^{1 m 2, and per 1 m 2.} The line density that can be connected corresponds to 4 to 7 channels, and the loss due to transmission is suppressed to 20% or less. Therefore, it has been confirmed that if the circuit wiring board for the photoelectric conversion element of the present invention is used, high-speed and large-capacity optical signal data can be efficiently converted into radio waves in the 60 GHz band and transmitted.

(Example 2)
As the base film, using a cyclic olefin-based resin polymer film having a thickness of 200μm the substituents R ₁ of the formula (1) and R ₂ is the structure of n- octane group, changing the irradiation time and distance of the ultraviolet lamp, After that, a circuit wiring board and a photoelectric conversion element were manufactured and evaluated under the same conditions as in Example 1. For the evaluation, the arithmetic average roughness Ra was measured on the surface of the cyclic olefin resin polymer film irradiated with the ultraviolet lamp using a surface roughness meter. The results are shown in Tables 2 and 3. As a result of the evaluation, if the arithmetic average roughness Ra of the surface of the cyclic olefin resin polymer film is in the range of 0.01 to 0.3 μm and the thickness of the copper film is in the range of 3 to 20 times Ra, it adheres to the copper film. It was confirmed that the radio electric signal corresponding to the optical signal was emitted from the electrode of the antenna transmission pattern as a radio wave having a frequency of 60 GHz. In particular, if Ra is 0.04 to 0.3 μm and the thickness of the copper film is in the range of 3 to 5 times that of Ra, a circuit wiring board having a peel strength of 10 N / cm or more can be obtained. On the other hand, when the arithmetic average roughness Ra exceeded 0.3 μm, the adhesion with the copper film was strong, but the radio wave having a frequency of 60 GHz was not detected.

(Examples 3 and 4)
As a result of the same test using the xenon excimer lamp of vacuum ultraviolet light in an oxygen atmosphere instead of the ultraviolet lamp, although there are differences in conditions such as the distance from the base film and the irradiation time, the cyclic olefin system is used. Similar results were obtained for the evaluation results such as the adhesiveness between the arithmetic average roughness Ra of the surface of the resin polymer film and the copper film, and the radio wave performance at a frequency of 60 GHz. From this, if the arithmetic average roughness Ra of the surface of the cyclic olefin resin polymer film and the relationship between the thickness of the copper film and Ra are within the predetermined ranges, the surface of the substrate file can be modified. It was confirmed that a circuit wiring board for a desired photoelectric conversion element can be manufactured regardless of the method.

1 Circuit wiring board 3 Optical wave guide 5 Photoelectric conversion element 10 Base film 11 Fine irregularities on the surface of the base film 20 Electrode 201 Electrode 201 Electrode 202 ground electrode consisting of an antenna receiving or transmitting electrode pattern

Claims (5)

A circuit wiring board in which electrodes are formed in direct contact with the surface of a base film.
The base film contains a cyclic olefin resin having a crystallinity of 1% to 30% as a main component.
The arithmetic average roughness Ra of the surface of the base film is 0.01 to 0.3 μm.
A circuit wiring board in which the electrode is a metal film having a thickness of 3 to 20 times the arithmetic mean roughness Ra of the surface of the base film. The circuit according to claim 1, wherein the electrode comprises an antenna receiving or transmitting electrode pattern formed on one surface of the substrate film and a ground electrode formed on the other surface of the substrate film. Wiring board. The cyclic olefin resin, not connected and the substituents _{R 1} and _{R 2} of formula (1), and consisting of _C n _H 2n + 1 structure (n = 0 to 8), according to claim 1 or claim 2 Circuit wiring board.

... Equation (1) The circuit wiring board according to any one of claims 1 to 3, wherein an optical waveguide is formed on the electrode. The surface of the base film is irradiated with ultraviolet rays or plasma-treated so that the arithmetic average roughness Ra of the surface is 0.01 to 0.3 μm, and the surface thereof is 3 to 20 times the arithmetic average roughness Ra. A method of manufacturing a circuit wiring board that forms an electrode that is a thick metal film.

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