KR20170107040A - Roughened copper foil and printed wiring board - Google Patents

Abstract

There is provided a copper foil capable of exhibiting a high peel strength even for an insulating resin base material in which transmission loss in a high-frequency use is good and chemical adhesion such as a liquid crystal polymer film can not be expected. The roughened copper foil of the present invention has a roughened surface having roughening particles on at least one side thereof and a roughened surface having a 10-point average roughness Rzjis of 0.6 to 1.7 m, The half width in the frequency distribution of the height is 0.9 占 퐉 or less.

Description

Roughened copper foil and printed wiring board

The present invention relates to a roughened copper foil and a printed wiring board, and more particularly to a printed wiring board for high frequency use and a roughened copper foil suitable for the same.

Flexible printed wiring boards (FPC) are widely used in electronic devices such as portable electronic devices. Particularly, along with the recent enhancement of functions of portable electronic devices and the like, high frequency signals have been advanced for high-speed processing of a large amount of information, and a flexible printed wiring board suitable for high frequency applications is required. In such a high frequency flexible printed wiring board, it is desired to reduce the transmission loss in order to enable high frequency signals to be transmitted without degrading the quality. The flexible printed wiring board has a copper foil and an insulating resin base material processed into a wiring pattern. The transmission loss is mainly composed of a conductor loss caused by the copper foil and a dielectric loss caused by the insulating resin base. The conductor loss can be further increased by the skin effect of the copper foil, which is remarkable as the frequency becomes higher.

In order to reduce the transmission loss in high-frequency applications, a copper foil capable of reducing conductor loss has been proposed. For example, in Patent Document 1 (Japanese Patent Laid-Open Publication No. 2014-224313), after a primary particle layer of copper is formed on the surface of a copper foil, a Cu-Co-Ni alloy A copper foil having a secondary particle layer formed thereon and an average value of heights of concavities and convexities on a roughened surface by a laser microscope of 1500 or more. In addition, Patent Document 2 (Japanese Patent Laid-Open Publication No. 2014-225650) discloses a method in which a primary particle layer of copper is formed on the surface of a copper foil and then a secondary particle layer of Cu- A copper foil having a particle layer formed thereon and a ratio of a three-dimensional surface area to a two-dimensional surface area by a laser microscope in a certain region of the roughed surface is not less than 2.0 and less than 2.2. All of the copper foils described in Patent Documents 1 and 2 are used for a high-frequency circuit board so that transmission loss can be satisfactorily suppressed.

As another method for reducing the transmission loss in high-frequency applications, an insulating resin base capable of reducing dielectric loss has also been proposed. An example of such an insulating resin base material is a liquid crystal polymer (LCP) film. However, an insulating resin base material suitable for high frequency applications such as a liquid crystal polymer film tends to have poor adhesion with copper foil, and a copper foil to cope with the improvement in adhesion with such an insulating resin base has also been proposed. For example, Patent Document 3 (Japanese Unexamined Patent Publication (Kokai) No. 2005-219379) discloses a surface treated copper foil having a roughened surface having a surface roughness Rz of 2.5 to 4.0 占 퐉, and a thermoplastic liquid crystal polymer having 50% And an insulating substrate is laminated on the substrate. Patent Document 4 (Japanese Patent Application Laid-Open No. 2010-236058) discloses a roughened copper foil having a roughened surface obtained by precipitating protruding fine copper particles having a head top angle of 85 or less .

Japanese Patent Application Laid-Open No. 2014-224313 Japanese Patent Application Laid-Open No. 2014-225650 Japanese Patent Application Laid-Open No. 2005-219379 Japanese Patent Application Laid-Open No. 2010-236058

In order to suppress transmission loss in high-frequency applications, a copper foil of a low-profile surface is required in view of the skin effect. On the other hand, the low-profile copper foil reduces the anchor effect with the insulating resin base material (that is, the effect of improving the physical adhesiveness by using the unevenness of the copper foil surface). As a result, it is difficult to obtain a sufficient peel strength for an insulating resin base material which can not be chemically contacted with, such as a liquid crystal polymer film, and as a result, the reliability as a flexible printed wiring board can be deteriorated. As described above, the transmission loss and the peel strength are inherently difficult to achieve because they have a trade-off relationship with the surface profile of the copper foil.

The inventors of the present invention have found that by applying to the copper foil a roughened surface having a 10-point average roughness Rzjis of 0.6 to 1.7 탆 and a half width of 0.9 탆 or less in the frequency distribution of the height of the roughened particles, It was possible to provide a copper foil capable of exhibiting a high peel strength even for an insulating resin base material in which a transmission loss in use is good and chemical adhesion such as a liquid crystal polymer film can not be expected.

Accordingly, an object of the present invention is to provide a copper foil which can exhibit a high peel strength even for an insulating resin base material in which a transmission loss in a high-frequency application is good and chemical adhesion such as a liquid crystal polymer film can not be expected.

According to one aspect of the present invention, there is provided a roughened copper foil having a roughened surface provided with roughening particles on at least one side thereof, wherein the roughened surface has a 10-point average roughness Rzjis of 0.6 to 1.7 m , And a full width at half maximum in the frequency distribution of the height of the roughening particles is not more than 0.9 mu m.

According to another aspect of the present invention, there is provided a printed wiring board for high frequency use, comprising a roughened copper foil of the above-mentioned aspect and an insulating resin layer formed in close contact with the roughened surface of the copper foil.

1 is a diagram for explaining the relationship between the frequency distribution of the height of the roughened particles and the half width.
2 is an FIB-SIM image obtained by observing the cross section of roughened particles on the roughened surface.
3 is an enlarged image (FIB-SIM image) of the head of the roughened particle.
4 is a schematic cross-sectional view showing a configuration of a sample for measurement of transmission loss.

Justice

Definitions of terms and parameters used to specify the present invention are as follows.

In the present specification, the " 10-point average roughness Rzjis " is the surface roughness measured according to JIS B0601-2001, and the average of the peak height from the highest peak to the fifth highest peak in the roughness curve, To the fifth in the deepest order.

In the present specification, the " half-width in the frequency distribution of the height of the roughened particle " refers to the distribution of the height of the roughened particle height present on the roughened surface of the roughened copper foil, Is defined as the total width of the frequency distribution peak at a value 1/2 of the maximum value of the frequency distribution peak as shown. The frequency distribution of the height of the roughened particles can be measured by using a three-dimensional roughness analyzer to measure the surface profile of the roughened surface of the roughened copper foil at a desired magnification (for example, 600 to 30000 times ). ≪ / RTI > The height of the roughened particle can be regarded as the particle size of the roughened particle. The height and the grain size of the roughed grains can be calculated by measuring the surface profile of the electrolytic copper foil before roughening and measuring the value resulting from the roughened surface profile before the roughening treatment as a background .

In the present specification, the term "specific surface area" refers to a value of X / Y obtained by dividing the three-dimensional surface area X of the roughened surface of the roughened copper foil by the measured area Y. The three-dimensional surface area X can be calculated by measuring a surface profile of a predetermined measurement area Y (for example, 14000 mu m ² ) of the roughened surface with a commercially available laser microscope.

In the present specification, the term " roughened particle cross-sectional area ratio " is an index indicating the degree of roughness (i.e., degree of fine roughening) of the roughed surface of the roughened particle, and is calculated by a commercially available image processing analyzer and a commercially available convergent ion beam processing A section of each roughened particle in a predetermined viewing range (for example, 8 占 퐉 占 8 占 퐉) of the roughened surface was observed using an observation apparatus (FIB), and a SIM image of FIB The cross sectional area and the cross sectional area of the FIB-SIM image were analyzed by image analysis of the FIB-SIM image, and the ratio of the cross sectional area of the roughened particle to the cross sectional area of the roughened particle) Is a value determined by calculating the ratio of cotton particle cross-sectional area. The specific measurement procedure is as follows. First, as shown in the FIB-SIM image shown in Fig. 2, a straight line is drawn from the approximately bisecting position of the roughened particle head to the roughened particle long side direction (i.e., the height direction of the roughened particle). A reference point a is specified at a position a predetermined distance (for example, 2 占 퐉) from the top of the head of the straightened roughened particle. Two tangent lines are drawn from the reference point a to the roughened particle, and the tangent line and the contact points b and c of the roughened particle are specified. Sectional area of a cross-sectional area surrounded by a straight line connecting the contacts b and c (hereinafter referred to as a straight line b-c) and the cross-section contour of the head of the roughened particle is determined by image analysis to be " cross-sectional area of roughened particle ". Next, as shown in the FIB-SIM image of Fig. 3, the "closed cross-sectional area of the roughened particle" was measured at each tip of the fine convex shape of the roughened particle surface (when fine roughened particles were present, And the area surrounded by the straight line bc, and this is determined by image analysis. The positioning of each of the leading ends can be automatically performed by software provided in a commercially available image processing analyzer. The cross-sectional area of the roughened particle is obtained as a value larger than the cross-sectional area of the roughened particle according to the degree of concavity and convexity of the roughened particle surface (that is, the degree of fine roughening). Therefore, by dividing the closed cross-sectional area of the roughened particle by the cross-sectional area of the roughened particle, it is possible to obtain a numerical value indicating the degree of concavity and convexity of the roughened particle surface (i.e., degree of fine roughening). That is, the ratio of the cross-section of the roughened particle is calculated from the obtained closed cross-sectional area and the cross-sectional area of the roughened particle. The ratio of the roughened particle cross-sectional area is preferably determined for each of the roughened particles observed every 1 o'clock, and it is preferable to calculate the average value of the roughened particle cross-sectional area ratios obtained for all the roughened particles at 5 o'clock.

Rough cotton  process Copper foil

The copper foil of the present invention is a roughened copper foil. The roughened copper foil has a roughened surface having roughened particles on at least one side thereof. The roughened surface has a 10-point average roughness Rzjis of 0.6 to 1.7 탆, and the half width in the frequency distribution of the height of the roughened particles is 0.9 탆 or less. Thus, by providing the copper foil with a roughened surface having a 10-point average roughness Rzjis of 0.6 to 1.7 탆 and a half-width of 0.9 탆 or less in the frequency distribution of the height of the roughened particles, It is possible to exhibit a high peel strength (for example, 1.2 kgf / cm or more in a copper foil having a thickness of 18 mu m) for an insulating resin base material in which the transmission loss is good and chemical adhesion as the liquid crystal polymer film can not be expected. As described above, since the transmission loss and the peel strength are in a trade-off relationship with respect to the surface profile of the copper foil, there is a problem that they are inherently difficult to be compatible with each other. According to the roughened copper foil of the present invention, The loss and the high peel strength can be achieved at an unexpected level.

The mechanism that enables compatibility between a good transmission loss and a high peel strength is not necessarily certain, but is considered to be as follows. First, by setting the 10-point average roughness Rzjis of the roughened surface to a low value range of 0.6 to 1.7 탆, the skin effect of the copper foil in the high-frequency application is significantly reduced to reduce the conductor loss, It is thought that the loss can be reduced. However, since the 10-point average roughness Rzjis of 0.6 to 1.7 탆 is a somewhat low value, the adhesiveness to an insulating resin base material, which can not be expected to have the same chemical adhesion as the liquid crystal polymer film originally, can be insufficient. This is presumably because the adhesion strength becomes unstable when the height of the roughened particle varies. In this regard, in the roughened copper foil of the present invention, the half width in the frequency distribution of the height of the roughened particles is set to 0.9 탆 or less, whereby the fluctuation of the height of the roughened particles is reduced, Thereby contributing to the improvement of the adhesion, whereby the adhesion strength can be stabilized. As a result, it becomes possible to exhibit a high peeling strength (for example, 1.2 kgf / cm or more in a copper foil having a thickness of 18 mu m) for an insulating resin base material in which chemical adhesion as the liquid crystal polymer film can not be expected.

The 10-point average roughness Rzjis (measured in accordance with JIS B0601-2001) of the roughed surface is 0.6 to 1.7 탆, preferably 0.7 to 1.6 탆, more preferably 0.9 to 1.5 탆. If Rzjis is within these ranges, the transmission loss in high-frequency applications can be preferably reduced, and also the adhesion to the insulating resin base material can be ensured.

The half width in the frequency distribution of the height of the roughening particles is 0.9 탆 or less, preferably 0.2 to 0.9 탆, more preferably 0.2 to 0.7 탆, and still more preferably 0.2 to 0.6 탆. When the half width is within the above range, the fluctuation of the height of the roughened particles is reduced, and more roughened particles contribute to the improvement of the adhesion, thereby achieving stabilization of the adhesion strength. As a result, it becomes possible to exhibit a high peeling strength (for example, 1.2 kgf / cm or more in a copper foil having a thickness of 18 mu m) for an insulating resin base material in which chemical adhesion as the liquid crystal polymer film can not be expected.

It is preferable that the roughened copper foil is further provided with fine fine roughening particles on the roughened particles rather than roughened particles. By forming the fine roughened particles on the roughening particles to increase the surface area, the peel strength can be further improved. However, the particle diameter of the fine roughened particles is very small, which is typically about 150 nm or less, and the influence on the transmission loss is very low in the frequency band below 100 GHz.

The roughened surface preferably has a specific surface area of 1.1 to 2.1, more preferably 1.2 to 2.0, still more preferably 1.3 to 1.9, and particularly preferably 1.5 to 1.9. The specific surface area is a value of X / Y obtained by dividing the three-dimensional surface area X of the roughened surface by the measured area Y, as described above. The specific surface area is appropriately increased to not less than 1.1 so that the peel strength of the insulating resin base material can be improved. Further, since the specific surface area is not excessively large at 2.1 or less, it is possible to suppress peeling off (so-called dropping of the powder) of the roughed particles due to physical contact which may occur when the specific surface area is excessively large, It is possible to effectively avoid the contamination of the downstream and downstream processes.

The roughened surface preferably has a roughened particle cross-sectional area ratio of 1.10 to 1.50, more preferably 1.15 to 1.30, and further preferably 1.15 to 1.20. The ratio of the roughened particle cross-sectional area is an index indicating the degree of roughness (that is, the degree of fine roughening) of the roughened particle surface as described above. Therefore, the larger the value of the ratio of the cross-sectional area of the roughened particle becomes, the more the projection surface on the roughened particle becomes. Therefore, when the roughened surface is bonded to the insulating resin base material, (I.e., in the absence of fine roughening particles), the physical adhesion becomes higher. Therefore, when the ratio of the cross-sectional area of the roughened particles is 1.15 or more, the physical adhesion of the roughened particles can be effectively increased. By setting the ratio of the cross-sectional area of the roughened particles to 1.50 or less, it is possible to suppress peeling off (so-called dropping of the powder) of the fine roughed particles due to physical contact which may occur when the specific surface area is excessively large, It is possible to effectively avoid the contamination of the downstream and downstream processes.

The thickness of the roughened copper foil of the present invention is not particularly limited, but is preferably 0.1 to 35 mu m, more preferably 0.5 to 18 mu m. The surface roughening treatment copper foil of the present invention is not limited to the roughening treatment of the surface of a conventional copper foil but may be a roughening treatment or fine roughening treatment of the copper foil surface of the copper foil with a carrier .

As described above, the roughed copper foil of the present invention is preferably used in a printed wiring board for high frequency use. That is, according to a preferred embodiment of the present invention, there is provided a printed wiring board for high frequency use, which comprises the roughened copper foil of the present invention and an insulating resin layer formed in close contact with the roughened surface of the copper foil. When used in a printed wiring board for high frequency use, the roughened copper foil of the present invention is excellent in transmission loss in high-frequency applications and has a high peeling strength (for example, an insulating resin base material such as a liquid crystal polymer film, For example, 1.2 kgf / cm or more in a copper foil having a thickness of 18 mu m). Therefore, the insulating resin layer preferably comprises a liquid crystal polymer (LCP), and is, for example, a liquid crystal polymer (LCP) film. Preferred examples of high-frequency applications include high-frequency components mounted on portable electronic devices such as a smart phone, for example, a liquid crystal display module, a camera module, and an antenna module.

Manufacturing method

An example of a preferable method for producing a roughened copper foil according to the present invention will be described. This preferred production method comprises the steps of preparing a copper foil having a surface having a 10-point average roughness Rzjis of not more than 1.5 탆, a first roughening step of performing electrolytic deposition at a predetermined current density J ₁ on the surface, A second roughing step of performing electrolytic deposition at a predetermined current density J ₂ on the surface, and a third roughing step of forming a roughened surface by subjecting the surface to electrolytic deposition at a predetermined current density J ₃ (J ₁ : J ₂ : J ₃₎ of the current densities J ₁ , J ₂ and J ₃ in the first roughing process, the second roughing process and the third roughing process, ) Is in the range of 1.0: 1.4: 1.2 to 1.0: 1.6: 1.5. However, the roughened copper foil of the present invention is not limited to the method described below, but may be produced by any method.

(1) Preparation of Copper foil

The copper foil used for the production of the roughened copper foil can be either an electrolytic copper foil or a rolled copper foil, more preferably an electrolytic copper foil. The copper foil may be a non-roughened copper foil or may be preliminary roughened. The thickness of the copper foil is not particularly limited, but is preferably 0.1 to 35 mu m, more preferably 0.5 to 18 mu m. When the copper foil is prepared in the form of a copper foil with a carrier, the copper foil is formed by a wet film formation method such as an electroless copper plating method and an electrolytic copper plating method, a dry film formation method such as sputtering and chemical vapor deposition, or a combination thereof It is acceptable.

The surface of the copper foil subjected to the roughening treatment preferably has a surface having a 10-point average roughness Rzjis measured according to JIS B0601-2001 of 1.5 m or less, more preferably 1.3 m or less, Or less. The lower limit value is not particularly limited, but is, for example, 0.1 mu m or more. Within the above range, it is easy to impart the surface profile required for the roughened copper foil of the present invention, particularly 10-point average roughness Rzjis of 0.6 to 1.7 m, to the roughened surface.

(2) roughening treatment

It is preferable to carry out the three-step roughening process of the first roughening process, the second roughening process and the third roughening process on the copper foil surface having the Rzjis of not more than 1.5 탆. In the first step cotton process, electrolytic precipitation is preferably performed at a predetermined current density J ₁ at a temperature of 20 to 40 캜 in a copper sulfate solution containing a copper concentration of 8 to 12 g / L and a sulfuric acid concentration of 200 to 280 g / L And the electrolytic precipitation is preferably carried out for 5 to 20 seconds. In the second step of the cotton process, electrolytic precipitation is preferably performed at a predetermined current density J ₂ at a temperature of 20 to 40 캜 in a copper sulfate solution containing a copper concentration of 8 to 12 g / L and a sulfuric acid concentration of 200 to 280 g / L And the electrolytic precipitation is preferably carried out for 5 to 20 seconds. Article 3 In the cotton process, electrodeposition is carried out at a predetermined current density J ₃ at a temperature of 45 to 55 ° C in a copper sulfate solution containing a copper concentration of 65 to 80 g / L and a sulfuric acid concentration of 200 to 280 g / It is preferable to form the treated surface, and the electrolytic precipitation is preferably performed for 5 to 25 seconds. The ratio of the current densities J ₁ , J ₂ and J ₃ in the first roughing process, the second roughing process and the third roughing process, that is, the ratio J ₁ : J ₂ : J ₃ is 1.0: 1.4: 1.2 To 1.0: 1.6: 1.5. When the current density ratio is within this range, it is easy to impart a half width in the frequency distribution of the surface profile required for the roughened copper foil of the present invention, particularly, the height distribution of the roughed grains of 0.9 mu m or less, to the roughened surface Loses. Preferably, the current density J ₁ of the first roughening process is ₈ to 20 A / dm ² , the current density J ₂ of the second roughening process is ₁₂ to 32 A / dm ² , the current density of the third roughening process J ₃ is 10 to 30 A / dm ² .

(3) Fine roughening treatment

(3) The fine roughening treatment is preferably performed on the roughened surface formed in the step (3). The fine roughening treatment was carried out in a copper sulfate solution having a copper concentration of 10 to 20 g / L, a sulfuric acid concentration of 30 to 130 g / L, a 9-phenyl acridine concentration of 100 to 200 mg / L and a chlorine concentration of 20 to 100 mg / It is preferable to conduct electrolytic deposition of the fine copper particles at a current density of 10 to 40 A / dm ² at a temperature of -40 캜, and this electrolytic deposition is preferably performed for 0.3 to 1.0 second.

(4) Anti-rust treatment

The copper foil after the roughening treatment may be subjected to an anti-corrosive treatment as required. The rust-preventive treatment preferably includes a plating treatment using zinc. The plating process using zinc may be either a zinc plating process or a zinc alloy plating process, and the zinc alloy plating process is particularly preferably a zinc-nickel alloy process. The zinc-nickel alloy treatment may be a plating treatment containing at least Ni and Zn, and may further include other elements such as Sn, Cr, and Co. The ratio of Ni / Zn in the zinc-nickel alloy plating is preferably 1.2 to 10, more preferably 2 to 7, and still more preferably 2.7 to 4 in mass ratio. Further, it is preferable that the rust-preventive treatment further includes a chromate treatment, and it is more preferable that the chromate treatment is performed on the surface of the plating containing zinc after the plating treatment with zinc. By doing so, the corrosion resistance can be further improved. A particularly preferable rust-preventive treatment is a combination of a zinc-nickel alloy plating treatment and a subsequent chromate treatment.

(5) Treatment with silane coupling agent

According to requirements, a copper foil may be treated with a silane coupling agent to form a silane coupling agent layer. As a result, it is possible to improve the moisture resistance, chemical resistance, adhesion with the insulating resin base material, and the like. The silane coupling agent layer can be formed by appropriately diluting a silane coupling agent, applying it, and drying it. Examples of the silane coupling agent include epoxy functional silane coupling agents such as 4-glycidylbutyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane, or 3-aminopropyltriethoxysilane, N-2 ( Aminopropyltrimethoxysilane, N-3- (4- (3-aminopropoxy) butoxy) propyl-3-aminopropyltrimethoxysilane, N-phenyl- Amino functional silane coupling agents such as trimethyl silane, amino silane coupling agents such as trimethyl silane, amino silane coupling agents such as trimethyl silane, amino silane coupling agents such as trimethyl silane, Or an acryl functional silane coupling agent such as 3-methacryloxypropyltrimethoxysilane, or an imidazole functional silane coupling agent such as imidazole silane, or a triazine functional silane coupling agent such as triazinilane .

carrier  Attach Copper foil

The roughened copper foil of the present invention may be provided in the form of a copper foil with a carrier. In this case, the copper foil with a carrier is provided with a carrier, a peeling layer formed on the carrier, and a roughened copper foil of the present invention formed on the peeling layer with the roughened surface outward. However, a known layer structure can be employed for the copper foil with a carrier, except that the roughened copper foil of the present invention is used.

The carrier is a thin or layered member for supporting the roughened copper foil and improving its handling properties. Examples of the carrier include an aluminum foil, a copper foil, and a resin film formed by metal coating the surface, and is preferably a copper foil. The copper foil may be either a rolled copper foil or an electrolytic copper foil. The thickness of the carrier is typically 200 μm or less, preferably 12 μm to 70 μm.

The release layer is a layer having a function of suppressing the mutual diffusion which may occur between the carrier and the copper foil at the time of press molding at a high temperature by securing the stability of the strength by weakening the peel strength of the carrier. The release layer is generally formed on one side of the carrier, but it may be formed on both sides. The release layer may be either an organic release layer or an inorganic release layer. Examples of the organic component used in the organic release layer include a nitrogen-containing organic compound, a sulfur-containing organic compound, and a carboxylic acid. Examples of the nitrogen-containing organic compound include triazole compounds and imidazole compounds. Among them, triazole compounds are preferable because of their easy peelability. Examples of triazole compounds include 1,2,3-benzotriazole, carboxybenzotriazole, N ', N'-bis (benzotriazolylmethyl) urea, 1H-1,2,4- -1H-1,2,4-triazole, and the like. Examples of the sulfur-containing organic compound include mercaptobenzothiazole, thiocyanuric acid, 2-benzimidazole thiol and the like. Examples of the carboxylic acid include a monocarboxylic acid and a dicarboxylic acid. On the other hand, examples of the inorganic component used in the inorganic release layer include Ni, Mo, Co, Cr, Fe, Ti, W, P, Zn and a chromate treatment film. The release layer may be formed by bringing the release layer component-containing solution into contact with at least one surface of the carrier and fixing the release layer component to the surface of the carrier. The carrier may be contacted with the solution containing the release layer component by immersion in the release layer component-containing solution, spraying of the solution containing the release layer component, and dropping of the solution containing the release layer component. The peeling layer component may be fixed to the carrier surface by adsorption or drying of the solution containing the peeling layer component and electrodeposition of the peeling layer component in the solution containing the releasing layer component. The thickness of the release layer is typically 1 nm to 1 占 퐉, preferably 5 nm to 500 nm.

As the roughened copper foil, the above-mentioned roughened copper foil of the present invention is used. The roughened copper foil of the present invention is subjected to a roughening treatment or a roughening treatment and a fine roughening treatment. In order to attain this, the copper layer is first formed on the surface of the release layer as a copper foil, And / or fine roughening treatment may be performed. Details of the roughening treatment and the fine roughening treatment are as described above. Further, in order to take advantage of the copper foil with a carrier, the copper foil is preferably formed in the form of an ultra-thin copper foil. The thickness of the ultra thin copper foil is preferably from 0.1 mu m to 7 mu m, more preferably from 0.5 mu m to 5 mu m, and still more preferably from 0.5 mu m to 3 mu m.

Another functional layer may be formed between the release layer and the copper foil. An example of such another functional layer is an auxiliary metal layer. The auxiliary metal layer is preferably made of nickel and / or cobalt. The thickness of the auxiliary metal layer is preferably 0.001 to 3 mu m.

Example

The present invention will be described more specifically with reference to the following examples.

Examples 1-3

The roughened copper foil of the present invention was produced as follows.

(1) Production of electrolytic copper foil

A copper sulfate solution of the following composition was used as the copper electrolyte, a rotary electrode made of titanium having a surface roughness Ra of 0.20 占 퐉 was used for the negative electrode, DSA (dimensional stability anode) was used for the positive electrode, And a current density of 55 A / dm < ² &^gt; to obtain an electrolytic copper foil having a thickness of 18 mu m. The ten-point average roughness Rzjis of the precipitated surface of the electrolytic copper foil was measured by the method described later and found to be 0.6 탆.

<Composition of Sulfuric Acid Sulfuric Acid Solution>

- Copper concentration: 80g / L

- sulfuric acid concentration: 260 g / L

Bis (3-sulfopropyl) disulfide concentration: 30 mg / L

- diallyldimethylammonium chloride Polymer concentration: 50 mg / L

- Chlorine concentration: 40 mg / L

(2) roughening treatment

Roughening treatment was performed on the side of the precipitation surface of the electrode surface and the precipitation surface of the above-mentioned electrolytic copper foil by the following three-step process.

In the first step of the roughening treatment, a copper electrolytic solution (copper concentration: 10.8 g / L, sulfuric acid concentration: 240 g / L, 9-phenyl acridine concentration: 0 mg / L, chlorine concentration: 0 Mg / L) under the conditions shown in Table 1A, and rinsed with water.

In the second stage of the roughening treatment, the copper electrolytic solution for roughening treatment (copper concentration: 10.8 g / L, sulfuric acid concentration: 240 g / L, 9-phenyl acridine concentration: 0 mg / Mg / L) under the conditions shown in Table 1A, and rinsed with water.

In the third step of the roughening treatment, a copper electrolytic solution (copper concentration: 70 g / L, sulfuric acid concentration: 240 g / L, 9-phenyl acridine concentration: 0 mg / / L) under the conditions shown in Table 1A, and rinsed with water.

(3) Fine roughening treatment

Fine-roughening treatment was carried out by conducting electrolysis under the conditions shown in Table 1. The fine roughening treatment was carried out in a copper electrolytic solution (copper concentration: 13 g / L, sulfuric acid concentration: 70 g / L, 9-phenyl acridine concentration: 140 mg / L, chlorine concentration: 35 mg / L) , And electrolysis under the conditions shown in Table 1B, followed by washing with water.

(4) Anti-rust treatment

The both surfaces of the electrolytic copper foil after the fine roughening treatment were subjected to anti-corrosive treatment comprising an inorganic anti-rust treatment and a chromate treatment. First, as an inorganic anti-corrosive treatment, using an acid bath exhaustion, potassium pyrophosphate concentration of 80g / L, zinc concentration of 0.2g / L, the nickel concentration 2g / L, liquid temperature of 40 ℃, zinc at a current density of 0.5A / dm ² - Nickel Alloy rust prevention treatment. Subsequently, as a chromate treatment, a chromate layer was further formed on the zinc-nickel alloy rust-preventive treatment. The chromate treatment was carried out at a chromic acid concentration of 1 g / L, a pH of 11, a solution temperature of 25 캜, and a current density of 1 A / dm ² .

(5) Treatment with silane coupling agent

The copper foil subjected to the rust-inhibitive treatment was washed with water and then immediately subjected to a silane coupling agent treatment to adsorb a silane coupling agent on the rust-inhibited layer on the roughened surface. This silane coupling agent treatment was carried out by using a solution having a concentration of 3 g / L of 3-aminopropyltrimethoxysilane as a solvent and spraying the solution onto a roughened surface with a shower to carry out an adsorption treatment . After the adsorption of the silane coupling agent, moisture was finally evaporated by an electric heater to obtain a roughened copper foil with a thickness of 18 mu m.

Example 4

A roughened copper foil was produced in the same manner as in Example 1 except that i) the fine roughening treatment was omitted, and ii) the roughening treatment was conducted under the conditions shown in Table 1A.

Example 5 (comparative)

(i) the surface of the electrolytic copper foil on the electrode surface side (i.e., the side opposite to the precipitation surface side, Rzjis: 1.5 占 퐉) was subjected to roughening treatment and the like; and ii) roughening treatment and fine roughening treatment were shown in Tables 1A and 1B A roughened copper foil was produced in the same manner as in Example 1, except that the copper foil was subjected to the conditions shown.

Example 6 (comparative)

(i) roughening treatment in the following one step was performed in place of the first, second and third roughening processes, and (ii) roughening treatment in the same manner as in Example 1, except that the fine roughening treatment was omitted .

(Roughening treatment)

Of the surface of the above electrolysis comprising copper foil electrode surface and precipitation, using the electrolytic copper for treatment roughening of the composition solution indicated below for the deposition side, the solution temperature 30 ℃, a current density of 50A / dm ^2, time 4 Sec, and roughening treatment was carried out.

<Composition of copper electrolytic solution for roughening treatment>

- Copper concentration: 13 g / L

- sulfuric acid concentration: 70 g / L

- 9-phenylacridine concentration: 100 mg / L

- Chlorine concentration: 35 mg / L

Example 7 (comparative)

(i) a treatment such as roughening treatment on the electrode surface side of the electrolytic copper foil (that is, the side opposite to the precipitation surface side, Rzjis: 1.5 탆), ii) the fine roughening treatment is omitted, and iii) A roughened copper foil was produced in the same manner as in Example 1 except that the conditions were as shown in Table 1A.

Example 8 (comparative)

(i) a treatment such as roughening treatment on the electrode surface side of the electrolytic copper foil (that is, the side opposite to the precipitation surface side, Rzjis: 1.5 탆), ii) the second roughening step and the fine roughening treatment are omitted, and (iii) roughening treatment (that is, the first roughening process and the third roughening process) were carried out under the conditions shown in Table 1A.

[Table 1A]

[Table 1B]

evaluation

For the roughened copper foil produced in Examples 1 to 8, various evaluations shown below were carried out.

<10 point average roughness Rzjis>

The 10-point average roughness Rzjis of the roughened surface of the roughened copper foil was measured according to JIS B0601-2001 by a contact surface roughness meter (Kosaka Kagaku Co., Ltd., SE3500). This measurement was carried out for a reference length of 0.8 mm using a diamond ball having a diameter of 2 탆 as a stylus. The Rzjis of the deposition surface or the electrode surface of the electrolytic copper foil before the roughening treatment in each of the examples described above was also measured in the same manner as described above.

&Lt; Half width in the frequency distribution of the height of the roughened particles >

The surface profile of the roughened surface of the roughened copper foil was measured using a three-dimensional roughness analyzer (ERA-8900, manufactured by EI ONIX CO., LTD.) Under the conditions of a magnification of 600 to 30000 times and an acceleration voltage of 10 kV. The measurement magnification was adjusted within the above range depending on the size of the roughened particles. The particle size was calculated based on the measured surface profile. At that time, the height of the roughened particles measured in the z-axis (in the thickness direction) interval in the unit of 0.01 mu m was regarded as the particle size. The height and the grain size of the roughed grains can be calculated by measuring the surface profile of the electrolytic copper foil before roughening and measuring the value resulting from the roughened surface profile before the roughening treatment as a background . The frequency distribution of the height of the roughened particle based on the height or the grain size thus calculated is created and the total width of the frequency distribution peak at a value 1/2 of the maximum value of the frequency distribution peak as shown in Fig. Was calculated as a half width (mu m).

&Lt; Surface surface area of roughened surface >

The surface profile of the area (100 μm × 140 μm) having an area of 14,000 μm ² on the roughened surface of the roughened copper foil was measured at a magnification of 2000 × using a laser microscope (VK-X100, manufactured by KYOSEN CHEMICAL CO. Respectively. A three-dimensional surface area X (mu m ² ) of the surface profile of the obtained roughened surface was calculated, and the value X / Y obtained by dividing the value of X by the measured area Y (14,000 mu m ² ) was defined as the specific surface area.

<Peel strength>

As an insulating resin base material, a liquid crystal polymer (LCP) film having a thickness of 50 占 퐉 (Vecstar CTZ manufactured by Kabushiki Kaisha K.K.) was prepared. The roughened copper foil was laminated on the insulating resin base so that the roughened surface was in contact with the insulating resin base, and hot press forming was performed at a pressure of 4 MPa and a temperature of 310 DEG C for 10 minutes to prepare a copper clad laminate sample. With respect to this copper-clad laminate sample, the state peel strength (kgf / cm) was measured in accordance with Method A of JIS C 5016-1994 by peeling in the direction of 90 ° with respect to the surface of the insulating resin base material.

&Lt; Percentage of cross-sectional area of roughed grain &

The roughened particle cross-sectional area ratio on the roughened surface of the roughened copper foil was measured. This measurement was carried out using a bench type automatic multifunctional image processing analyzer (LUZEX AP) and a converged ion beam processing observation apparatus (FIB) (Hereinafter referred to as &quot; FIB-SIM image &quot;) at a magnification of 18000 times by observing a cross section of each of the roughened particles in the FIB-SIM image , And calculating the ratio of the roughened particle cross-sectional area as a ratio of the cross-sectional area of the roughened particles to the cross-sectional area of the roughened particles. The binarization setting in this image analysis was set to 127. [ The concrete procedure was as follows.

(1) Measurement of cross-sectional area of roughened particles

As shown in the FIB-SIM image shown in Fig. 2, a straight line is drawn in the direction of the long side of the roughened particle (i.e., the height direction of the roughened particle) from the roughly bisection position of the roughened particle head. The reference point a is specified at a position 2 占 퐉 away from the top of the head of the straightened roughened particle. Two tangent lines are drawn from the reference point a to the roughened particle, and the tangent line and the contact points b and c of the roughened particle are specified. Sectional area of a cross-sectional area surrounded by a straight line connecting the contacts b and c (hereinafter referred to as a straight line b-c) and the cross-sectional contour of the head of the roughened particle is determined by image analysis to obtain the cross- The reason why the distance from the top of the head of the roughened particle in setting the reference point a is 2 占 퐉 is that the length of the scale of the FIB-SIM image is 2 占 퐉. The positions of the contact points b and c are uniquely specified even if they fluctuate, so that the value of the cross-sectional area of the roughened particles can be obtained with high accuracy.

(2) Measurement of the cross sectional area of roughened particles

An enlarged image of the head of the roughened particle is shown in Fig. As shown in the FIB-SIM image of Fig. 3, the closed cross-sectional area of the roughened particles was determined by dividing the cross-sectional area of each roughened surface of the roughened particle surface by the tip of each of the fine convex roughened surfaces (each tip of the roughened particles in the presence of fine roughened particles) And an area of a region surrounded by a connecting line and a bc straight line, and this was determined by image analysis. The positioning of each tip was automatically performed by the software provided in the image processing analyzer.

(3) Determination of the roughening particle cross-sectional area ratio

The ratio of the cross-section of the roughened particle was calculated from the obtained closed cross-sectional area and the cross-sectional area of the roughened particle. The ratio of the roughened particle cross-sectional area was calculated for each roughened particle observed every 1 field, and the average value of the roughened particle cross-sectional area ratios obtained for all roughened particles at 5 fields was calculated.

<Transmission Loss>

As an insulating resin base material, a liquid crystal polymer (LCP) film having a thickness of 50 占 퐉 (Vecstar CTZ manufactured by Kabushiki Kaisha K.K.) was prepared. The roughened copper foil was laminated on both sides of the insulating resin base material so that the roughened surface was in contact with the insulating resin base material and bonded by a batch press. 4, etching is performed only on the roughened copper foil on one side of the insulating resin base material 40, and a signal layer 42 (18 占 퐉 thick) is formed by forming a microstrip line so that the characteristic impedance becomes 50? Respectively. On the other hand, the roughened copper foil on the opposite side of the signal layer 42 of the insulating resin base material 40 was not subjected to etching, and the ground layer 44 (18 mu m thick) was formed. A 12 μm thick polyimide film (manufactured by Nikkan Kogyo Co., Ltd.) was applied to the signal layer 42 side of the insulating resin base material 40 through an adhesive (AY-25KA manufactured by Asahi Glass Co., Ltd., , CISV-1225) were bonded as a coverlay 46 to obtain a transmission loss measurement sample. The transmission loss S ₂₁ of 40 GHz at a circuit length of 5 cm was measured using a network analyzer (Nissha KK, N5247A) and a probing system (SUMMIT 9000, manufactured by Cascade Microtech Co., Ltd.) Respectively.

result

The evaluation results obtained in Examples 1 to 8 were as shown in Table 2.

[Table 2]

Claims (8)

Wherein the roughened surface has a 10-point average roughness Rzjis of 0.6 to 1.7 mu m, and the height of the roughened grains Wherein the full width at half maximum in the frequency distribution of the copper foil is 0.9 占 퐉 or less. The method according to claim 1,
Wherein the half-width of the copper foil is 0.2 to 0.9 mu m. 3. The method according to claim 1 or 2,
Wherein the surface to be roughened has a specific surface area of 1.1 to 2.1, and the specific surface area is a value of X / Y obtained by dividing the three-dimensional surface area X of the roughened surface by the measured area Y. 4. The method according to any one of claims 1 to 3,
Wherein the roughening treatment further comprises fine roughening particles finer than the roughening particles on the roughening particles. 5. The method according to any one of claims 1 to 4,
Wherein the roughened surface has a roughened particle cross-sectional area ratio of 1.10 to 1.50. 6. The method according to any one of claims 1 to 5,
Roughened copper foil used for printed wiring boards for high frequency applications. A printed wiring board for high frequency use, comprising the roughened copper foil according to any one of claims 1 to 6 and an insulating resin layer formed in close contact with the roughened surface of the copper foil. 8. The method of claim 7,
Wherein the insulating resin layer comprises a liquid crystal polymer.

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