JP2002319757A - Flexible copper clad plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible copper clad plate having an excellent durability in which stripping strength is sufficiently high between a flexible polymer basic material and a copper layer and a fine circuit pattern can be formed. SOLUTION: In the flexible copper clad plate having a copper layer formed on a flexible polymer basic material 1, independent micro metal films are spotted substantially uniformly on the surface of the flexible polymer basic material and the part on the surface of the flexible polymer basic material not spotted with the metal film 2 has a structure 3 recessed from the surface by 0.1-2.0 μm on the average. An intermediate metal layer and a copper layer are formed sequentially on the surface of the flexible polymer basic material while covering the micro metal films and the recess structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible copper-clad board and a method for manufacturing the same, and more particularly, to a flexible printed circuit board (FPC) used for electronic equipment and the like.
The present invention relates to a flexible copper-clad plate that can be suitably applied to the above.

[0002]

2. Description of the Related Art In recent years, a flexible copper-clad board in which a copper layer is formed on a flexible polymer base material such as a polyimide film,
Flexible printed wiring board, TAB (Tape Au
It is widely used in fields such as tomated bonding tapes. If the peel strength between the flexible polymer base material and the copper layer is not sufficiently strong, the flexible copper-clad board is liable to undergo interface peeling due to heat or vibration, resulting in a problem in durability. In particular, it was difficult to obtain sufficient delamination strength of a flexible copper-clad board in which a copper layer was formed on a flexible polymer substrate without using an adhesive. Such a problem will be specifically described below using a flexible printed wiring board as an example.

A printed wiring board is a processed board having three functions: a support function for fixing and supporting electronic components for forming an electronic circuit, a conductive function for connecting components, and an insulating function. In general, printed wiring boards are roughly classified into rigid wiring boards and flexible wiring boards, and a flex-rigid wiring board in which these two types of wiring boards are combined into one is also known. As the flexible printed wiring board, there are known a three-layer structure in which a base film (flexible polymer base material) is laminated with a copper foil with an adhesive, and a two-layer structure without an adhesive layer.

[0004] A method for forming a circuit on a printed wiring board is as follows.
It is roughly divided into the subtractive method and the additive method.
In the subtractive method, using a copper-clad laminate as a starting material, after performing copper plating in the hole for the through hole and on the surface, using a photolithography technique using a resist, removing unnecessary portions by etching, A necessary conductor pattern is formed on the laminate. In the conventional subtractive method, a copper-clad laminate in which a relatively thick copper foil is laminated is used, so that there is a limit in increasing the density and miniaturization of wiring.

[0005] The additive method is a full additive method,
It is classified into the semi-additive method and the part-reactive method. In both the full-additive method and the semi-additive method, a conductive pattern is selectively formed in the hole and on the surface by plating using an insulating material having no copper foil and a photolithography technique using a resist. In the full additive method, a metal is generally deposited only on a conductor portion by electroless copper plating. In the semi-additive method, generally, after a thin copper layer is formed on the entire surface by electroless copper plating, a resist pattern is formed, and the required thickness of electrolytic copper plating (electrolytic copper plating) or electroless copper plating is applied. The resist is stripped and the first electroless copper plating is etched. In the part-reactive method, a copper-clad laminate is used as a starting material, a conductor pattern is formed by etching, and then plating is performed only on a through-hole portion.

In a flexible printed wiring board using the additive method, a semi-additive method is generally applied. The most difficult technique in the semi-additive method is to increase the peel strength between the base film (flexible polymer substrate) and the copper layer. In order to increase the peel strength, a technique for forming a seed layer on a base film has been developed. The seed layer is formed by a method using electroless plating, or a method using vacuum deposition or sputtering. In either case, a seed layer made of metal is formed on the base film, and a copper layer having a desired thickness can be formed by electroplating based on the seed layer. further,
After patterning a portion to be a circuit by a photolithography technique using a resist, preferably, the thickness of the copper in the circuit portion is increased to a predetermined thickness by electroplating. Thereafter, the resist is removed, and the copper layer other than the circuit is removed by etching.

A flexible printed wiring board using the additive method has excellent dimensional stability as compared with a case using a flexible copper-clad board in which ordinary copper foils are laminated.
Since a fine circuit composed of a thin copper layer can be easily formed and no adhesive is used, the heat resistance of a flexible polymer substrate such as a polyimide film can be fully utilized.

However, as a seed layer, nickel (N
Even if metal such as i) or chromium (Cr) is interposed, the peel strength between the flexible polymer substrate and the copper layer is insufficient,
Improvement was desired. JP-A-5-251511 discloses that a surface of a polyimide film is subjected to dry etching to form fine irregularities, and a discharge plasma treatment is performed thereon to generate a functional group having a strong binding action with copper. ,
A method for producing a polyimide laminated structure in which a copper thin film is formed by vapor deposition has been proposed.

When the surface of the flexible polymer base material is roughened to form fine irregularities, the contact area between the flexible polymer base material and the copper layer can be increased. It is expected that the peel strength can be improved by the so-called anchor effect. However, in reality, it is difficult to form fine and deep irregularities on the surface of a flexible polymer base material, and it is extremely difficult to obtain a flexible copper-clad board having a peel strength that is sufficiently satisfactory industrially. there were.

In recent years, as electronic devices have become lighter and smaller and have higher performance, flexible substrates such as flexible printed wiring boards have been increasingly used as wiring materials in the devices. The wiring pitch in these devices is expected to continue to be miniaturized in the future.
In addition, electronic devices are often used in environments and situations where heat, vibration, impact, and the like are applied, and the electronic devices themselves generate heat and vibration. Therefore, there is a need for a flexible copper-clad substrate that has sufficient peel strength between the flexible polymer base material and the copper layer, is resistant to heat, vibration, impact, and the like, and has excellent durability.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a flexible copper-clad board used for a flexible printed wiring board or the like, which has a sufficient peel strength between a flexible polymer base material and a copper layer. It is an object of the present invention to provide a flexible copper-clad board that is high, has excellent durability, and can form a fine circuit.

The present inventors have conducted intensive studies in order to achieve the above object, and as a result, the average diameter of a flexible polymer base material such as a polyimide film has been formed by a dry process such as a vapor deposition method or a sputtering method. Have conceived a method of forming a large number of independent small metal films interspersed and etching a flexible polymer substrate using the fine metal films as a mask to form a fine and deep hollow structure. .

When an intermediate metal layer (seed layer) and a copper layer are formed in this order on the surface of the flexible polymer substrate so as to cover the fine metal film and the hollow structure, the flexibility is high. The peel strength between the molecular substrate and the copper layer is remarkably improved, and a flexible copper-clad board excellent in durability can be obtained. A minute metal film, an intermediate metal layer, and a copper layer can be formed by a dry process.

That is, since it is possible to continuously form in the same vacuum apparatus from the unevenness processing of the flexible substrate surface to the formation of sputtered copper, there is a great merit that equipment and processes can be simplified. Further, a copper plating layer having a desired thickness can be formed by electroplating on the copper thin film formed by the dry process. The present invention has been completed based on these findings.

[0015]

Thus, according to the present invention, there is provided a flexible copper-clad board in which a copper layer is formed on a flexible polymer substrate, and (1) the surface of the flexible polymer substrate. To
Independent minute metal films are almost uniformly scattered,
(2) The portion of the surface of the flexible polymer substrate where the fine metal film is not interspersed has an average depth (d) from the surface of 0.1 to 2.
It has a concave structure of 0 μm. (3) A fine metal film and a concave structure are coated on the surface of the flexible polymer base material, and an intermediate metal layer and a copper layer are formed in this order. A flexible copper clad board is provided.

According to the present invention, there is further provided a method for producing a flexible copper-clad board in which a copper layer is formed on a flexible polymer base material, wherein (I) (II) The flexible polymer substrate is formed by using the fine metal film scattered on the surface of the flexible polymer as a mask. The surface of the flexible polymer substrate is etched to form a concave structure having an average depth (d) of 0.1 to 2.0 μm from the surface in a portion where the fine metal film is not dotted. Form (II
I) On the surface of the flexible polymer base material, a fine metal film and a hollow structure are coated by a dry process to form an intermediate metal layer, and then (IV) a dry process is performed on the intermediate metal layer. A process for producing a flexible copper-clad board is provided, wherein a thin copper film is formed by a process.

In the above method, after the step (IV),
(V) An additional step of forming a copper plating layer having a desired thickness by electroplating on a copper thin film formed by a dry process can be arranged.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of a flexible polymer substrate used in the present invention include a film made of a heat-resistant resin such as polyimide, liquid crystal polymer, polyester, polyethersulfone, and fluororesin. . Among these, a polyimide film and a liquid crystal polymer film are particularly preferable because they are excellent in heat resistance, have a low dielectric constant, and can easily obtain a flexible copper-clad board having excellent peel strength by the production method of the present invention. The thickness of the flexible polymer substrate is not particularly limited and can be appropriately determined depending on the application, but is usually about 10 to 100 μm.

Independent fine metal films are almost uniformly scattered on the surface of the flexible polymer base material. As a method of forming such minute metal films interspersed on the surface of a flexible polymer base material, first, a flexible process is performed by a dry process such as an evaporation method, a sputtering method, or an ion plating method. There is a method of depositing fine metal particles on the surface of a polymer base material. Next, the fine metal particles are agglomerated by the agglomeration treatment to create a state in which independent fine metal films are almost uniformly scattered. The average diameter, thickness, dot density, and the like of the independent fine metal film are determined by the depth, opening diameter, pitch, and the like of the concave portions formed on the surface of the flexible polymer base material.

The vapor deposition method is a thin film forming method in which a small piece of metal is heated and evaporated in a high vacuum, and the evaporated particles adhere to a substrate. Examples of the heating method include resistance heating, high-frequency heating, flash heating, electron beam heating, and laser heating. Further, a reactive evaporation method can also be applied.

The sputtering method is a method of irradiating high-speed particles to the surface of a target material in a low-pressure gas to release atoms or molecules on the surface of the target material and depositing the atoms or molecules on a substrate to form a film. It is. The sputtering method includes an ion beam sputtering method and a plasma sputtering method. The sputtering device is a discharge method,
Depending on the structure of the electrode and the like, it is classified into a method such as direct current bipolar sputtering, high frequency sputtering, and magnetron sputtering.

According to the sputtering method, a high-melting-point material can be thinned at a low temperature, the adhesion between the thin film and the substrate is strong, a large-area film can be easily formed, high-frequency discharge, use of active gas, and the like. Thus, a thin film of any material can be formed. When a metal is used as the target material, a metal thin film can be formed on the base material.

The ion plating method is a method in which metal atoms generated from an evaporation source are ionized in plasma, accelerated by an electric field, and deposited on a substrate to form a film. As the plasma, an inert gas such as argon (Ar) is often used. As the ionization method, there are direct current ion plating using glow discharge by direct current and high frequency ion plating using high frequency discharge.

According to such a dry process, 0.1.
Fine metal particles having a thickness of about 01 to 0.3 μm can be independently deposited. In order to form minute metal films interspersed on the surface of the flexible polymer base material, a coagulation treatment is usually performed. Originally, in a dry process, metal is formed in fine particles on the surface of a flexible polymer base material.
Utilizing this property, the fine metal particles are formed to have a thickness of about several hundred angstroms, and then the fine metal particles are agglomerated by heat of an infrared heater or an inert plasma to have an average diameter of about 0.1 to 2.5 μm. Let it grow. This is called an agglomeration treatment. The density of the scattered metal film can be controlled by the heat irradiation time and the temperature. By the aggregation of the fine metal particles, exposed portions of the flexible polymer base material are formed between the metal films that are independently scattered. This exposed portion will be etched to form a recessed structure.

The shape of the minute metal film (shape viewed from above: front shape) is not particularly limited, and may be any shape such as a circle, an ellipse, or a polygon such as a rectangle. preferable. The average diameter (a) of the fine metal film is usually 0.1
To 2.5 μm, preferably 0.1 to 2.0 μm.
In many cases, good results can be obtained when the average diameter (a) is in the range of 0.5 to 2.0 μm.

The diameter of the minute metal film indicates the diameter of the minute metal film in the case of a circular shape, but the average value of the maximum length and the minimum length in the case of another shape such as an ellipse. means. The cross-sectional shape of the minute metal film is arbitrary, such as a rectangle or an arc. The thickness of the cross section of the fine metal film is usually 0.01 to 0.3 μm, preferably 0.015 to 0.2 μm.
It is about 5 μm.

Various surface shape measuring instruments are used for measuring the surface state of the independent minute metal film scattered on the surface of the flexible polymer base material. Among them, a non-contact type method, for example, measurement by a laser microscope is preferable because the base material is a polymer material. Specifically, any 20μ
By selecting the m-angle as a visual field and observing 10 or more fine metal films scattered in the visual field, the average value can be used as the average diameter. The thickness of the minute metal film can be determined by observing the cross section with a high-resolution SEM (HRSEM) and measuring from a photograph.

The material of such a minute metal film is as follows.
For example, nickel (Ni), chromium (Cr), cobalt (Co), manganese (Mn), molybdenum (Mo), and a mixture of two or more thereof can be given.

In the present invention, preferably, an independent fine metal film having an average diameter (a) of 0.1 to 2.5 μm is formed on the surface of the flexible polymer base material at an average pitch (p) a to 4a. Dotted with. The average pitch (p) is more preferably 1.5a to
3a.

The portion of the surface of the flexible polymer substrate where the fine metal film is not scattered has an average depth (d) of 0.1 from the surface.
It has a concave structure of about 2.0 μm. The average depth (d) of the depression is preferably 0.5 to 2.0 μm,
In many cases, good results can be obtained in the range of 0.5 to 1.5 μm.

Such a concave structure having fine and deep irregularities is formed by etching the surface of a flexible polymer substrate using a fine metal film scattered on the surface of the flexible polymer as a mask. In this case, it is preferable to perform over-etching up to the interface between the fine metal film and the flexible polymer substrate. The average length of over-etching is 0.1a to 0.5a (a = average diameter of a minute metal film), preferably 0.1a or more and less than 0.5a, more preferably 0.1a to 0.3a. . If the length of over-etching is too large, the peel strength tends to decrease, which is not preferable. The slight over-etching further enhances the anchor effect and improves the peel strength of the copper layer.

FIG. 3 is a sectional view for explaining the average diameter (a), the average pitch (p), and the depth (d) of the depression of the fine metal film. A minute metal film 32 is scattered on the surface of the flexible polymer base material 31, and a concave structure 33 is formed in a portion where the fine metal film 32 is not scattered. FIG. 3 shows a case where the shape of the minute metal film (shape viewed from above) is circular. The average diameter (a) of the minute metal film is the average value of the length indicated by a in FIG. The average pitch (p) is an average value of the length indicated by p in FIG. The depth (d) of the depression is an average value of the length indicated by d in FIG. The length of the over-etching is the length indicated by reference numeral 34 in FIG.

The flexible copper-clad board of the present invention covers the surface of such a flexible polymer substrate with a fine metal film and a hollow structure, and an intermediate metal layer and a copper layer are formed in this order. Layer structure. The copper layer is usually one or two layers, and may be a multilayer of three or more layers if desired.

The material of the intermediate metal layer may be nickel (Ni), chromium (Cr), cobalt (Co), manganese (Mn), molybdenum (Mo), or two of these materials from the viewpoint of adhesion to the copper layer. The mixture is preferably the above, and more preferably the same material as the fine metal film. The material of the intermediate metal layer is particularly preferably Ni and Cr. The presence of the intermediate metal layer can increase the peel strength between the flexible polymer substrate and the copper layer.

The intermediate metal layer is generally formed by a dry process such as a vapor deposition method, a sputtering method, and an ion plating method. The thickness of the intermediate metal layer is preferably 0.01 to 0.3 μm, more preferably 0.015 to 0.35 μm.
0.25 μm. In many cases, good results can be obtained when the thickness of the intermediate metal layer is about 0.015 to 0.025 μm.

The copper layer is formed on the intermediate metal layer, preferably by a dry process. The thickness of the copper thin film formed by the dry process is preferably 10 to 30.
0 nm (100 to 3000 °), more preferably 15 to
250 nm (150-2500 °). When the flexible copper-clad board of the present invention is used as a substrate to which, for example, a semi-additive method is applied, a resist pattern is formed thereon by using a flexible copper-clad board in which an intermediate metal layer and a copper layer are formed by a dry process. Then, a conductor pattern having a desired thickness can be formed by electrolytic copper plating. After removing the resist, the copper layer other than the conductor pattern (circuit) portion is removed by etching.

On the other hand, when the flexible copper clad board of the present invention is used as a substrate to which the subtractive method is applied,
A copper plating layer having a desired thickness is further formed on the copper thin film formed by the dry process by electrolytic copper plating.
In this case, the copper layer is a thin copper film formed by a dry process,
It consists of two copper plating layers by electroplating. In this case, prior to electroplating, a process such as drilling for a through hole can be arranged. Further, a copper plating layer may be formed by electroless copper plating instead of electroplating, but it is preferable to perform high-speed electroplating. The thickness of the copper plating layer is usually 3 to 50 μm.
m, preferably about 5 to 40 μm.

The method for producing a flexible copper clad board of the present invention will be further described. As a method for etching the surface of the flexible polymer, there are a wet etching method using a chemical such as hydrazine and a dry etching method such as plasma etching and ion etching. In the present invention, from the viewpoint of workability and productivity, it is preferable to employ a dry etching method. Among them, ion etching is more preferable, and reactive ion etching (RIE) is particularly preferable. Ion etching is a method of etching a substrate using positive ions generated in plasma,
Argon is widely used as an inert ion. Since ion etching uses only physical reactions,
Low etching rate. On the other hand, reactive ion etching using an active gas uses a chemical reaction due to ions or the like, so that the etching rate is high and anisotropic etching is possible. As the active gas, for example, a fluorine-based gas or a chlorine-based gas is used.

FIGS. 1 and 2 are process diagrams (cross-sectional views) for explaining a method of manufacturing a flexible copper clad board according to the present invention. As shown in FIG. 1, an independent fine metal film 2 is formed on a flexible polymer substrate 1 by a dry process and an agglomeration process. Next, using the fine metal film 2 as a mask, the flexible polymer base material is etched by reactive ion etching or the like to form the depression structure 3.

Next, as shown in FIG. 2, an intermediate metal layer 4 is formed on the surface of the flexible polymer substrate 1 by a dry process so as to cover the fine metal film 2 and the hollow structure 3. A copper thin film 5 is formed thereon by a dry process. When used as a substrate to which the subtractive method is applied, a copper plating layer 6 having a desired thickness is formed on the copper thin film 5, preferably by electroplating.

Since the flexible copper-clad plate of the present invention is subjected to the above-described treatment on the surface of the flexible polymer base material, the adhesion of the intermediate metal layer is excellent. The peel strength is significantly improved. In order to further enhance the anchor effect, it is preferable to slightly overetch just below the minute metal film by reactive ion etching as shown in FIG.

[0042]

The present invention will be described more specifically below with reference to examples and comparative examples. Methods for measuring physical properties and the like are as follows. (1) Initial peel strength Immediately after the preparation of the flexible copper-clad board, the force per 1 cm required for peeling the copper layer and the flexible polymer substrate was measured. (2) Peel strength after heat treatment After preparing a flexible copper-clad board, leave it in an atmosphere of 150 ° C. for 3 days, and then apply a force per 1 cm necessary to peel the copper layer and the flexible polymer base material. It was measured.

Example 1 As a flexible polymer substrate, a polyimide film (Kapton EN, manufactured by Du Pont-Toray Co., Ltd.) cut into 25 cm square was used, and after setting this in a substrate holder of a sputtering apparatus, 3 × 10 ^-3 Pa
Vacuum was applied until RF plasma treatment of Argon (Ar) (RF power 100 W) for cleaning the substrate
For 3 minutes. Thereafter, a film of nickel (Ni) was formed to a thickness of 0.02 μm on the substrate. Further, by heating the surface of the base material at 200 ° C. for 3 minutes by infrared heating, the deposited fine Ni particles are aggregated to have an average diameter of 0.5
It was scattered on the surface of the polyimide film substrate as a fine nickel film having a pitch of 1.0 μm and a thickness of 1.0 μm. Next, using this minute nickel film as a mask, reactive ion etching (RIE) is performed using CF ₄ / O ₂ gas to form a film.
After a minute treatment, a depression having a depth of 0.1 μm was formed on the surface of the polyimide film substrate. Overetching was about 0.05 μm.

On the surface of the flexible polymer substrate treated as described above, a thickness of 20 nm (200
ニ ッ ケ ル) The nickel (Ni) film was formed as an intermediate metal layer. On this Ni layer, a copper thin film having a thickness of 200 nm (2000 °) was formed by a sputtering method. Further, a thickness of 8 μm is formed on the copper thin film by electroplating.
m of the copper plating layer was formed. Table 1 shows the measurement results of the peel strength of the flexible copper-clad board thus obtained.
Shown in

[Examples 2 to 6 and Comparative Examples 1 to 4] The average diameter (a), average pitch (p), average depth (d) of dents, and average length of overetching of a fine metal film were determined. Except having changed as shown in Table 1, it carried out similarly to Example 1, and produced the flexible copper clad board. Table 1 shows the results.

[0046]

[Table 1]

As is evident from the results in Table 1, the flexible copper-clad sheets of the present invention (Examples 1 to 6) have remarkably improved initial peel strength, and maintain a high level of peel strength after heat treatment. ing.

[Examples 7 and 8] In Example 1, a liquid crystal polymer film (Kuraray FA film, thickness 25 μm) was used instead of the polyimide film.
In addition, except that the average diameter (a), average pitch (p), average depth of depression (d), and average length of overetching of the minute metal film were changed as shown in Table 2,
A flexible copper-clad board was produced in the same manner as in Example 1.
Table 2 shows the results.

[0049]

[Table 2]

[Examples 9 and 10] Except that the metal forming the intermediate metal layer was changed from Ni to chromium (Cr),
In the same manner as in Examples 2 and 3, flexible copper-clad boards were produced. Table 3 shows the results.

[0051]

[Table 3]

[0052]

According to the present invention, there is provided a flexible copper-clad board having sufficiently high peel strength between a flexible polymer substrate and a copper layer, excellent durability, and capable of forming a fine circuit. Provided. The flexible copper-clad board of the present invention can be applied to, for example, various types of structures in which a copper layer (copper foil) such as a flexible printed wiring board or TAB tape and a flexible polymer base material are combined. In addition, the flexible copper clad board of the present invention is capable of forming a fine and high-density circuit (conductor pattern) by a subtractive method or a semi-additive method.
Can be formed.

[Brief description of the drawings]

FIG. 1 is a part of a process diagram (cross-sectional view) showing a method for manufacturing a flexible copper-clad board of the present invention. Fig. 1 (1)
Indicates a flexible polymer substrate. FIG. 1B shows a step of forming a minute metal film. FIG. 1 (3) shows a step of forming a concave structure.

FIG. 2 is a part of a process diagram (cross-sectional view) showing a method for manufacturing a flexible copper-clad board of the present invention. Fig. 2 (1)
Shows a step of forming an intermediate metal layer. FIG. 2B shows a process of forming a copper thin film. FIG. 2 (3) shows a step of forming a copper plating film.

FIG. 3 is a cross-sectional view for explaining an average diameter (a), an average pitch (p), and a depth (d) of a depression of a minute metal film.

[Description of Signs] 1: Flexible polymer base material 2: Fine metal film 3: Indented structure 4: Intermediate metal film 5: Copper thin film 6: Copper plating layer 31: Flexible polymer base material 32: Fine metal film 33: Indentation structure 34: Length of overetching a: Diameter of minute metal film p: Pitch d: Depth of depression

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/18 H05K 3/18 G (72) Inventor Gotaro Tanaka 1-chome, Shimaya, Konohana-ku, Osaka-shi, Osaka No. 3 F-term in Sumitomo Electric Industries, Ltd. Osaka Works (reference) 4E351 AA02 AA04 AA05 BB35 CC01 CC03 CC06 CC27 DD04 DD17 DD19 DD23 GG02 GG08 GG20 5E343 AA18 AA19 AA33 BB22 BB24 BB38 BB39 BB44 BB24 BB25 DD43 GG02 GG08

Claims (10)

[Claims] 1. A flexible copper-clad board in which a copper layer is formed on a flexible polymer base material, (1) an independent fine metal film is formed on the surface of the flexible polymer base material substantially uniformly. (2) A portion of the surface of the flexible polymer substrate where the fine metal film is not dotted has an average depth (d) of 0.1 from the surface.
(3) A fine metal film and a hollow structure are coated on the surface of the flexible polymer base material, and an intermediate metal layer and a copper layer are formed in this order. A flexible copper-clad board characterized by being made. 2. The flexible copper clad board according to claim 1, wherein the flexible polymer substrate is a polyimide film or a liquid crystal polymer film. 3. The fine metal film and the intermediate metal layer are at least one metal selected from the group consisting of nickel (Ni), chromium (Cr), cobalt (Co), manganese (Mn), and molybdenum (Mo). The flexible copper-clad board according to claim 1 or 2, which contains an element. 4. The concave structure on the surface of the flexible polymer base material is formed by etching using a fine metal film scattered on the surface of the flexible polymer base material as a mask,
The flexible copper clad board according to claim 1, wherein the flexible copper clad board is over-etched. 5. The flexible copper clad board according to claim 1, wherein the copper layer is a thin copper film formed by a dry process. 6. The copper layer has a two-layer structure of a lower layer made of a copper thin film formed by a dry process and an upper layer made of a copper plating layer formed by electroplating.
5. The flexible copper-clad board according to any one of items 4 to 4. 7. A method for producing a flexible copper-clad board in which a copper layer is formed on a flexible polymer base material, wherein (I) a process for forming an independent fine particle on the surface of the flexible polymer base material by a dry process. (II) Etching the surface of the flexible polymer substrate using the fine metal film scattered on the surface of the flexible polymer as a mask. Thus, the average depth (d) from the surface to the portion where the fine metal film is not scattered is 0.1 to 2.0.
μm indentation structure is formed, and (III) a fine metal film and the indentation structure are coated on the surface of the flexible polymer substrate by a dry process to form an intermediate metal layer. )
A method for manufacturing a flexible copper-clad board, comprising forming a copper thin film on an intermediate metal layer by a dry process. 8. The method according to claim 7, further comprising, after the step (IV), (V) forming a copper plating layer having a desired thickness by electroplating on the copper thin film formed by the dry process. Manufacturing method. 9. The method according to claim 7, wherein the dry process in the steps (I), (III) and (IV) is a sputtering method. 10. The method according to claim 7, wherein the etching in the step (II) is reactive ion etching.
The production method according to the paragraph.