WO2016174998A1

WO2016174998A1 - Roughened copper foil and printed wiring board

Info

Publication number: WO2016174998A1
Application number: PCT/JP2016/061127
Authority: WO
Inventors: 響介柳; 美智溝口; 咲子朝長
Original assignee: 三井金属鉱業株式会社
Priority date: 2015-04-28
Filing date: 2016-04-05
Publication date: 2016-11-03
Also published as: JP6682516B2; CN107532322A; KR20170107040A; TW201706457A; TWI588302B; JPWO2016174998A1; CN107532322B; KR101975135B1

Abstract

Provided is a copper foil which can exhibit high peel strength with respect to insulating resin substrates from which chemical bonding cannot be expected, such as liquid crystal polymer films, while exhibiting good transmission loss in high frequency applications. This roughened copper foil has a roughened surface having roughened particles on at least one side of the foil, the roughened surface has a ten point average roughness Rzjis of 0.6-1.7 μm, and the half value width is 0.9 μm or less in a frequency distribution of the height of the roughened particles.

Description

Roughened copper foil and printed wiring board

The present invention relates to a roughened copper foil and a printed wiring board, and more specifically to a printed wiring board for high frequency applications 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. In particular, with the advancement of functions of portable electronic devices and the like in recent years, the frequency of signals has been increased to perform high-speed processing of a large amount of information, and a flexible printed wiring board suitable for high-frequency applications is required. Such a high-frequency flexible printed wiring board is desired to reduce transmission loss in order to enable transmission of high-frequency signals without degrading quality. The flexible printed wiring board has a copper foil processed into a wiring pattern and an insulating resin base material, but the transmission loss is a conductor loss due to the copper foil and a dielectric loss due to the insulating resin base material. And mainly. The conductor loss can be further increased by the skin effect of the copper foil that appears more prominently at higher frequencies.

In order to reduce transmission loss in high frequency applications, copper foils that can reduce conductor loss have been proposed. For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2014-224313), a primary particle layer of copper is formed on the surface of a copper foil, and then a secondary layer of Cu—Co—Ni alloy is formed on the primary particle layer. There is disclosed a copper foil for a high-frequency circuit, which is a copper foil having a particle layer, in which the average value of the unevenness of the roughened surface by a laser microscope is 1500 or more. In Patent Document 2 (Japanese Patent Laid-Open No. 2014-225650), a primary particle layer of copper is formed on the surface of a copper foil, and then a secondary layer of Cu—Co—Ni alloy is formed on the primary particle layer. A copper foil for a high-frequency circuit, in which a ratio of a three-dimensional surface area to a two-dimensional surface area by a laser microscope in a certain region of a roughened surface is 2.0 or more and less than 2.2, is a copper foil having a particle layer formed thereon. ing. It is said that both of the copper foils described in Patent Documents 1 and 2 can be satisfactorily suppressed by using a high frequency circuit board.

In addition, as another technique for reducing transmission loss in high frequency applications, an insulating resin base material capable of reducing dielectric loss has been proposed. An example of such an insulating resin substrate is a liquid crystal polymer (LCP) film. However, insulating resin base materials suitable for high-frequency applications such as liquid crystal polymer films tend to have poor adhesion to copper foil, and copper foils that address such improved adhesion to insulating resin base materials are also proposed. Has been. For example, in Patent Document 3 (Japanese Patent Application Laid-Open No. 2005-219379), a surface-treated copper foil having a roughened surface with a surface roughness Rz of 2.5 to 4.0 μm, and 50% or more is thermoplastic. A composite material in which an insulating substrate made of a liquid crystal polymer is laminated is disclosed. Further, Patent Document 4 (Japanese Patent Laid-Open No. 2010-236058) discloses a roughened copper foil having a roughened surface on which fine copper particles having a protrusion shape with a vertex angle of 85 ° or less are deposited. ing.

JP 2014-224313 A JP 2014-225650 A JP 2005-219379 A JP 2010-236058 A

To suppress transmission loss in high frequency applications, low profile copper foil is required from the viewpoint of 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 physical adhesion utilizing the unevenness of the copper foil surface). Therefore, it is difficult to obtain sufficient peel strength with respect to an insulating resin base material that cannot be expected to be chemically adhered, such as a liquid crystal polymer film, and can therefore be inferior in reliability as a flexible printed wiring board. Thus, since transmission loss and peel strength are in a trade-off relationship with the surface profile of the copper foil, it is inherently difficult to achieve both.

The inventors of the present invention now have a ten-point average roughness Rzjis of 0.6 to 1.7 μm, and a roughening whose half-value width in the frequency distribution of the height of the roughening particles is 0.9 μm or less. By imparting a treated surface to copper foil, it is possible to exhibit high peel strength even for insulating resin substrates that cannot be expected to be chemically adhered, such as liquid crystal polymer films, while having good transmission loss in high-frequency applications. The knowledge that a copper foil can be provided was acquired.

Therefore, an object of the present invention is to provide a copper foil that can exhibit high peel strength even with respect to an insulating resin base material that cannot be expected to be chemically adhered, such as a liquid crystal polymer film, while having good transmission loss in high frequency applications. It is to provide.

According to an aspect of the present invention, there is provided a roughened copper foil having a roughened surface provided with roughened particles on at least one side, wherein the roughened surface is 0.6 to 1.7 μm. A roughened copper foil having a point average roughness Rzjis and having a half-value width of 0.9 μm or less in the frequency distribution of the height of the roughened particles is provided.

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

It is a figure for demonstrating the relationship between the frequency distribution of the height of a roughening particle | grain, and a half value width. It is a FIB-SIM image in which a cross section of roughened particles on the roughened surface is observed. It is an enlarged image (FIB-SIM image) of the head of roughened particles. It is a schematic cross section showing the composition of a sample for transmission loss measurement.

Definitions The definitions of terms and parameters used to specify the present invention are shown below.

In this specification, “ten-point average roughness Rzjis” is a surface roughness measured in accordance with JIS B0601-2001, and is an average of the peak heights from the highest peak to the fifth highest in the roughness curve. , The average sum up to the fifth deepest from the deepest valley bottom.

In the present specification, the “half-value width in the frequency distribution of the height of the roughened particles” is shown in FIG. 1 in the frequency distribution of the height of the roughened particles existing on the roughened surface of the roughened copper foil. Thus, it is defined as the full width of the frequency distribution peak at a value ½ of the maximum value of the frequency distribution peak. The frequency distribution of the height of the roughened particles is obtained by using a three-dimensional roughness analyzer to obtain a desired magnification according to the size of the roughened particles (for example, 600 to 600). (30000 times). The height of the roughened particles can be regarded as the particle size of the roughened particles. For the calculation of the rough particle size, the surface profile of the electrolytic copper foil (raw foil) before the roughening treatment is measured in advance, and the value resulting from the surface profile before the roughening treatment is calculated. Sometimes it is desirable to do so by removing as background.

In this specification, the “specific surface area” is 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 measurement 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 μm ² ) of the roughened surface with a commercially available laser microscope.

In this specification, the “roughened particle cross-sectional area ratio” is an index representing the degree of unevenness of the roughened particle surface (that is, the degree of fine roughening), and is a commercially available image processing analyzer and a commercially available focused ion beam processing observation. Using an apparatus (FIB), the cross-section of each roughened particle in a predetermined visual field range (for example, 8 μm × 8 μm) of the roughened surface is observed, and a FIB SIM image (hereinafter referred to as FIB-SIM image) at a magnification of 18000 times The FIB-SIM image is subjected to image analysis to measure the closed cross-sectional area and cross-sectional area, and the ratio of (closed cross-sectional area of roughened particles) / (cross-sectional area of roughened particles) is measured. It is a value determined by calculating the fractional particle cross-sectional area ratio. The specific measurement procedure is as follows. First, as depicted in the FIB-SIM image shown in FIG. 2, a straight line is drawn from the approximately bisected position of the head of the roughened particle to the long side direction of the roughened particle (that is, the height direction of the roughened particle). . The reference point a is specified at a position away from the top of the roughened particles on the straight line by a predetermined distance (for example, 2 μm). Two tangent lines are drawn from the reference point a to the roughened particles, and the contact points b and c between the tangent lines and the roughened particles are specified. A cross-sectional area of a cross-sectional area surrounded by a straight line connecting the contact points b and c (hereinafter referred to as a bc straight line) and a cross-sectional contour line of the head of the roughened particle is obtained by image analysis. " Next, as depicted in the FIB-SIM image of FIG. 3, the “closed curved cross-sectional area of the roughened particles” is defined as each fine convex tip of the roughened particle surface (if fine roughened particles exist, The area of the region surrounded by the line connecting the tips of the coarse particles and the bc line is defined, and this is obtained by image analysis. The positioning of each tip can be automatically performed by software provided in a commercially available image processing analyzer. The closed curved cross-sectional area of the roughened particles is obtained as a value larger than the cross-sectional area of the roughened particles according to the degree of unevenness on the surface of the roughened particles (ie, the degree of fine roughening). Accordingly, by dividing the closed curved cross-sectional area of the roughened particles by the cross-sectional area of the roughened particles, a numerical value representing the degree of unevenness (that is, the degree of fine roughening) on the surface of the roughened particles can be obtained. That is, the roughened particle cross-sectional area ratio is calculated from the obtained closed curved cross-sectional area and the cross-sectional area of the roughened particles. The rough particle cross-sectional area ratio is calculated for each rough particle observed for each field of view, and the average value of the rough particle cross-sectional area ratios obtained for all the rough particles for five fields of view is calculated. Is preferred.

Roughened copper foil The copper foil of the present invention is a roughened copper foil. This roughened copper foil has a roughened surface with roughened particles on at least one side. The roughened surface has a 10-point average roughness Rzjis of 0.6 to 1.7 μm, and the half width in the frequency distribution of the height of the roughened particles is 0.9 μm or less. Thus, a roughened surface having a 10-point average roughness Rzjis of 0.6 to 1.7 μm and a half-value width in the frequency distribution of the height of the roughened particles being 0.9 μm or less is made of copper foil. Is applied to an insulating resin substrate such as a liquid crystal polymer film that cannot be expected to have chemical adhesion while having good transmission loss in high-frequency applications (for example, a copper foil having a thickness of 18 μm is 1. 2 kgf / cm or more). As described above, transmission loss and peel strength are in a trade-off relationship with the surface profile of the copper foil, so there is a problem that it is inherently difficult to achieve compatibility. According to this, good transmission loss and high peel strength can be achieved unexpectedly.

The mechanism that makes it possible to achieve both good transmission loss and high peel strength is not necessarily clear, but is thought to be as follows. First, the ten-point average roughness Rzjis of the roughened surface is set to a low value range of 0.6 to 1.7 μm, thereby significantly reducing the skin effect of copper foil in high frequency applications and reducing conductor loss. Thus, it is considered that transmission loss can be reduced. However, the above-mentioned 10-point average roughness Rzjis of 0.6 to 1.7 μm is a low value, and by itself, adhesion with an insulating resin base material, such as a liquid crystal polymer film, that cannot be expected to be chemically adhered is poor. Can be enough. This is considered to be because the adhesion strength becomes unstable when the height of the roughened particles varies. In this regard, in the roughened copper foil of the present invention, the variation in the height of the roughened particles is reduced by setting the half-value width in the frequency distribution of the height of the roughened particles to 0.9 μm or less. The roughened particles can contribute to the improvement of adhesion, and thereby the adhesion strength can be stabilized. As a result, it becomes possible to exhibit high peel strength (for example, 1.2 kgf / cm or more with a copper foil having a thickness of 18 μm) even for an insulating resin base material such as a liquid crystal polymer film that cannot be expected to have chemical adhesion.

The ten-point average roughness Rzjis (measured according to JIS B0601-2001) of the roughened surface is 0.6 to 1.7 μm, preferably 0.7 to 1.6 μm, more preferably Is 0.9 to 1.5 μm. Rzjis within these ranges can desirably reduce transmission loss in high frequency applications and contribute to securing adhesion to the insulating resin substrate.

The half width in the frequency distribution of the height of the roughened particles is 0.9 μm or less, preferably 0.2 to 0.9 μm, more preferably 0.2 to 0.7 μm, and still more preferably 0.2 to 0.6 μm. When the half-value width is within these ranges, the variation in the height of the roughened particles can be reduced, and more roughened particles can contribute to improving the adhesion, thereby stabilizing the adhesion strength. As a result, it becomes possible to exhibit high peel strength (for example, 1.2 kgf / cm or more with a copper foil having a thickness of 18 μm) even for an insulating resin base material such as a liquid crystal polymer film that cannot be expected to have chemical adhesion.

It is preferable that the roughened copper foil further comprises fine roughened particles that are finer than the roughened particles on the roughened particles. By forming fine roughened particles on the roughened particles and increasing the surface area, the peel strength can be further improved. Nevertheless, since the particle size of the finely roughened particles is extremely small, typically 150 nm or less, the influence on the transmission loss is extremely low in the frequency band of 100 GHz or less.

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, particularly preferably. 1.5 to 1.9. As described above, 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 measurement area Y. When the specific surface area is appropriately large as 1.1 or more, the peel strength with respect to the insulating resin substrate can be improved. Further, since the specific surface area is not too large as 2.1 or less, it is possible to suppress peeling of the roughened particles (so-called powder falling) due to physical contact that may occur when the specific surface area is too large. It is possible to effectively avoid a decrease in peel strength and contamination in the subsequent process.

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 even more preferably 1.15 to 1.20. . As described above, the roughened particle cross-sectional area ratio is an index representing the degree of unevenness of the roughened particle surface (that is, the degree of fine roughening). Therefore, the larger the protrusion on the roughened particle, the larger the value of the cross-sectional area ratio of the roughened particle. Therefore, when the roughened surface is bonded to the insulating resin base material, the contact area with the insulating resin base material is large. As a result, the physical adhesion is increased as compared with the roughened particles alone (that is, when there are no finely roughened particles). Therefore, when the rough particle cross-sectional area ratio is 1.15 or more, the physical adhesion of the rough particles can be effectively increased. In addition, by setting the roughened particle cross-sectional area ratio to 1.50 or less, it is possible to suppress peeling of fine roughened particles (so-called powder falling) due to physical contact that may occur when the specific surface area is too large. As a result, it is possible to effectively avoid a decrease in peel strength and contamination in the subsequent process.

The thickness of the roughened copper foil of the present invention is not particularly limited, but is preferably 0.1 to 35 μm, more preferably 0.5 to 18 μm. In addition, the roughening copper foil of this invention performed the roughening process or the fine roughening process of the copper foil surface not only what performed the roughening process on the surface of the normal copper foil but the copper foil with a carrier. It may be a thing.

As described above, the roughened copper foil of the present invention is preferably used for a printed wiring board for high frequency applications. That is, according to a preferred aspect of the present invention, there is provided a printed wiring board for high frequency applications, comprising the roughened copper foil of the present invention and an insulating resin layer provided in close contact with the roughened surface of the copper foil. Provided. When used for printed wiring boards for high-frequency applications, the roughened copper foil of the present invention has good transmission loss in high-frequency applications, but against insulating resin substrates that cannot be expected to be chemically adhered, such as liquid crystal polymer films. However, it is possible to exhibit high peel strength (for example, 1.2 kgf / cm or more with a 18 μm thick copper foil). Therefore, the insulating resin layer preferably includes a liquid crystal polymer (LCP), 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 smartphones, such as liquid crystal display modules, camera modules, and antenna modules.

Production Method An example of a preferred method for producing the roughened copper foil according to the present invention will be described. The preferred manufacturing method comprises the steps of ten-point average roughness Rzjis is prepared copper foil having the surface 1.5 [mu] m, the first crude performing electrolytic deposition at a predetermined current density J ₁ to said surface step a, roughening performed a second roughened step of performing electrolytic deposition at a predetermined current density J ₂ relative to the surface, the electrolytic deposition at a predetermined current density J ₃ relative to the surface A third roughening step for forming a treatment surface, and preferably a ratio of current densities J ₁ , J ₂ and J ₃ in the first roughening step, the second roughening step and the third roughening step ( That is, J ₁ : J ₂ : J ₃ ) is set within the range of 1.0: 1.4: 1.2 to 1.0: 1.6: 1.5. However, the roughened copper foil according to the present invention is not limited to the method described below, and may be manufactured by any method.

(1) Preparation of copper foil As copper foil used for manufacture of a roughening process copper foil, use of both electrolytic copper foil and rolled copper foil is possible, More preferably, it is electrolytic copper foil. Further, the copper foil may be a non-roughened copper foil or a pre-roughened copper foil. The thickness of the copper foil is not particularly limited, but is preferably 0.1 to 35 μm, more preferably 0.5 to 18 μm. When the copper foil is prepared in the form of a copper foil with a carrier, the copper foil is prepared 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 It may be formed by a combination thereof.

The surface of the copper foil to be roughened preferably has a surface with a ten-point average roughness Rzjis measured in accordance with JIS B0601-2001 of 1.5 μm or less, more preferably 1. It is 3 μm or less, more preferably 1.0 μm or less. Although a lower limit is not specifically limited, For example, it is 0.1 micrometer or more. Within the above range, the surface profile required for the roughened copper foil of the present invention, in particular, the 10-point average roughness Rzjis of 0.6 to 1.7 μm can be easily imparted to the roughened surface.

(2) Roughening treatment It is preferable to perform a three-step roughening step, a first roughening step, a second roughening step, and a third roughening step, on the surface of the copper foil having Rzjis of 1.5 μm or less. In the first roughening step, electrolytic deposition is performed at a predetermined current density J ₁ at a temperature of 20 to 40 ° C. 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. Preferably, this electrolytic deposition is performed for 5 to 20 seconds. In the second roughening step, electrolytic deposition is performed at a predetermined current density J ₂ at a temperature of 20 to 40 ° C. 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. Preferably, this electrolytic deposition is performed for 5 to 20 seconds. In the third roughening step, electrolytic deposition is performed 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 / L. A roughened surface is preferably formed, and this electrolytic deposition is preferably performed for 5 to 25 seconds. The first roughening step, the second coarse step and the third ratio roughening current density _J 1 in step _{J 2} and _{J 3,} i.e. _{_J} _1: _J _2: _J ₃ 1.0: 1.4 : 1.2 to 1.0: 1.6: 1.5 is preferable. When the current density ratio is within this range, the surface profile required for the roughened copper foil of the present invention, particularly the half-value width in the frequency distribution of the height of the roughened particles of 0.9 μm or less on the roughened surface. It becomes easy to give. Preferably, the current density J ₁ in the first roughening step is 8 to 20 A / dm ² , the current density J ₂ in the second roughening step is 12 to 32 A / dm ² , and the current in the third roughening step The density J ₃ is 10 to 30 A / dm ² .

(3) Fine roughening treatment It is preferable that the fine roughening treatment is further performed on the roughening treatment surface formed in the third roughening step. The fine roughening treatment is performed at 20 to 40 ° C. 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-phenylacridine concentration of 100 to 200 mg / L, and a chlorine concentration of 20 to 100 mg / L. It is preferable to carry out the electrolytic deposition of fine copper particles at a current density of 10 to 40 A / dm ² at this temperature, and this electrolytic deposition is preferably carried out for 0.3 to 1.0 seconds.

(4) Rust prevention treatment If desired, the copper foil after the roughening treatment may be subjected to a rust prevention treatment. The rust prevention treatment preferably includes a plating treatment using zinc. The plating treatment using zinc may be either a zinc plating treatment or a zinc alloy plating treatment, and the zinc alloy plating treatment is particularly preferably a zinc-nickel alloy treatment. The zinc-nickel alloy treatment may be a plating treatment containing at least Ni and Zn, and may further contain other elements such as Sn, Cr, and Co. The Ni / Zn adhesion ratio 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 terms of mass ratio. The rust prevention treatment preferably further includes a chromate treatment, and this chromate treatment is more preferably performed on the surface of the plating containing zinc after the plating treatment using zinc. By carrying out like this, rust prevention property can further be improved. A particularly preferable antirust treatment is a combination of a zinc-nickel alloy plating treatment and a subsequent chromate treatment.

(5) Silane coupling agent treatment If desired, the copper foil may be treated with a silane coupling agent to form a silane coupling agent layer. Thereby, moisture resistance, chemical resistance, adhesion to an insulating resin substrate, and the like can be improved. The silane coupling agent layer can be formed by appropriately diluting and applying a silane coupling agent and drying. Examples of silane coupling agents include epoxy-functional silane coupling agents such as 4-glycidylbutyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane, or 3-aminopropyltriethoxysilane, N-2 (amino Amino functions such as ethyl) 3-aminopropyltrimethoxysilane, N-3- (4- (3-aminopropoxy) butoxy) propyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane Silane coupling agents, or mercapto-functional silane coupling agents such as 3-mercaptopropyltrimethoxysilane, or olefin-functional silane coupling agents such as vinyltrimethoxysilane and vinylphenyltrimethoxysilane, or 3-methacryloxypropyl Trime Acrylic-functional silane coupling agent such as Kishishiran, or imidazole functional silane coupling agent such as imidazole silane, or triazine functional silane coupling agents such as triazine silane.

Copper foil with carrier The roughened copper foil of the present invention may be provided in the form of a copper foil with carrier. In this case, the carrier-attached copper foil includes a carrier, a release layer provided on the carrier, and the roughened copper foil of the present invention provided on the release layer with the roughened treatment surface outside. It becomes. However, a known layer structure can be adopted as the carrier-attached copper foil except that the roughened copper foil of the present invention is used.

The carrier is a foil-like or layer-like member for supporting the roughened copper foil and improving its handleability. Examples of the carrier include an aluminum foil, a copper foil, a resin film whose surface is metal-coated, and the like, preferably a copper foil. The copper foil may be 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 weakening the peeling strength of the carrier, ensuring the stability of the strength, and further suppressing the interdiffusion that may occur between the carrier and the copper foil during press molding at a high temperature. . The release layer is generally formed on one side of the carrier, but may be formed on both sides. The release layer may be either an organic release layer or an inorganic release layer. Examples of organic components used in the organic release layer include nitrogen-containing organic compounds, sulfur-containing organic compounds, carboxylic acids and the like. Examples of nitrogen-containing organic compounds include triazole compounds, imidazole compounds, and the like. Among these, triazole compounds are preferred in terms of easy release stability. Examples of triazole compounds include 1,2,3-benzotriazole, carboxybenzotriazole, N ′, N′-bis (benzotriazolylmethyl) urea, 1H-1,2,4-triazole and 3-amino- And 1H-1,2,4-triazole. Examples of the sulfur-containing organic compound include mercaptobenzothiazole, thiocyanuric acid, 2-benzimidazolethiol and the like. Examples of the carboxylic acid include monocarboxylic acid and dicarboxylic acid. On the other hand, examples of inorganic components used in the inorganic release layer include Ni, Mo, Co, Cr, Fe, Ti, W, P, Zn, and a chromate-treated film. The release layer may be formed by bringing a 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 brought into contact with the release layer component-containing solution by immersion in the release layer component-containing solution, spraying of the release layer component-containing solution, flowing down of the release layer component-containing solution, or the like. The release layer component may be fixed to the carrier surface by adsorption or drying of the release layer component-containing solution, electrodeposition of the release layer component in the release layer component-containing solution, or the like. The thickness of the release layer is typically 1 nm to 1 μm, preferably 5 nm to 500 nm.

The roughened copper foil of the present invention described above is used as the roughened copper foil. The roughened copper foil of the present invention has been subjected to a roughening treatment, or a roughening treatment and a fine roughening treatment, but as a procedure, first, a copper layer is formed on the surface of the release layer as a copper foil, Thereafter, at least roughening treatment and / or fine roughening treatment may be performed. Details of the roughening treatment and the fine roughening treatment are as described above. In addition, it is preferable that copper foil is comprised with the form of an ultra-thin copper foil in order to utilize the advantage as copper foil with a carrier. A preferable thickness of the ultrathin copper foil is 0.1 μm to 7 μm, more preferably 0.5 μm to 5 μm, and still more preferably 0.5 μm to 3 μm.

Other functional layers may be provided 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 μm.

The present invention will be described more specifically by the following examples.

Examples 1-3
The roughened copper foil of the present invention was produced as follows.

(1) Preparation of electrolytic copper foil A copper sulfate solution having the composition shown below was used as the copper electrolyte, a titanium rotating electrode having a surface roughness Ra of 0.20 μm was used for the cathode, and a DSA (dimensional stability) was used for the anode. Electrolysis at a solution temperature of 45 ° C. and a current density of 55 A / dm ² to obtain an electrolytic copper foil having a thickness of 18 μm. The ten-point average roughness Rzjis of the deposited surface of this electrolytic copper foil was measured by the method described later and found to be 0.6 μm.
<Composition of sulfuric acid copper sulfate solution>
-Copper concentration: 80 g / 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 The roughening treatment was performed in the following three stages on the precipitation surface side of the electrode surface and the precipitation surface included in the electrolytic copper foil.
-The first stage of the roughening treatment is a copper electrolytic solution for roughening treatment (copper concentration: 10.8 g / L, sulfuric acid concentration: 240 g / L, 9-phenylacridine concentration: 0 mg / L, chlorine concentration: 0 mg / L ), Electrolysis was performed under the conditions shown in Table 1A, followed by washing with water.
-The second stage of the roughening treatment is a copper electrolytic solution for roughening treatment (copper concentration: 10.8 g / L, sulfuric acid concentration: 240 g / L, 9-phenylacridine concentration: 0 mg / L, chlorine concentration: 0 mg / L ), Electrolysis was performed under the conditions shown in Table 1A, followed by washing with water.
-The third stage of the roughening treatment is in a copper electrolytic solution for roughening treatment (copper concentration: 70 g / L, sulfuric acid concentration: 240 g / L, 9-phenylacridine concentration: 0 mg / L, chlorine concentration: 0 mg / L) The electrolysis was performed under the conditions shown in Table 1A, followed by washing with water.

(3) Fine roughening treatment A fine roughening treatment was performed by electrolysis under the conditions shown in Table 1. The fine roughening treatment is performed in Table 1B in a copper electrolytic solution for roughening treatment (copper concentration: 13 g / L, sulfuric acid concentration: 70 g / L, 9-phenylacridine concentration: 140 mg / L, chlorine concentration: 35 mg / L). It was carried out by electrolyzing under the indicated conditions and washing with water.

(4) Rust prevention treatment Rust prevention treatment consisting of inorganic rust prevention treatment and chromate treatment was performed on both surfaces of the electrolytic copper foil after the fine roughening treatment. First, as an inorganic rust prevention treatment, using a pyrophosphate bath, potassium pyrophosphate concentration 80 g / L, zinc concentration 0.2 g / L, nickel concentration 2 g / L, liquid temperature 40 ° C., current density 0.5 A / dm ² Zinc-nickel alloy rust prevention treatment was performed. Next, as a chromate treatment, a chromate layer was further formed on the zinc-nickel alloy rust preventive treatment. This chromate treatment was performed at a chromic acid concentration of 1 g / L, pH 11, a solution temperature of 25 ° C., and a current density of 1 A / dm ² .

(5) Silane coupling agent treatment The copper foil that has been subjected to the above rust prevention treatment is washed with water and then immediately treated with a silane coupling agent to adsorb the silane coupling agent on the rust prevention treatment layer of the roughened surface. It was. In this silane coupling agent treatment, pure water is used as a solvent, a solution having a 3-aminopropyltrimethoxysilane concentration of 3 g / L is used, and this solution is sprayed onto the roughened surface by showering to perform an adsorption treatment. went. After adsorption of the silane coupling agent, water was finally evaporated by an electric heater to obtain a roughened copper foil having a thickness of 18 μm.

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 performed under the conditions shown in Table 1A.

Example 5 (Comparison)
i) The surface of the electrolytic copper foil (that is, the side opposite to the deposition surface, Rzjis: 1.5 μm) was subjected to a treatment such as a roughening treatment, and ii) The roughening treatment and the fine roughening treatment were performed in Table 1A. And the roughened copper foil was produced like Example 1 except having performed according to the conditions shown by 1B.

Example 6 (Comparison)
i) Roughing was performed in the same manner as in Example 1 except that the following one-step roughening treatment was performed instead of the first, second and third roughening steps, and ii) the fine roughening treatment was omitted. The copper foil was prepared.

(Roughening treatment)
Of the electrode surface and the deposition surface provided in the above-described electrolytic copper foil, a copper electrolytic solution for roughening treatment having the following composition is used for the deposition surface side, a solution temperature of 30 ° C., a current density of 50 A / dm ² , Roughening was performed by electrolysis under conditions of time 4 seconds.
<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 (Comparison)
i) The surface of the electrolytic copper foil (that is, the side opposite to the deposition surface, Rzjis: 1.5 μm) was subjected to a treatment such as a roughening treatment, ii) the fine roughening treatment was omitted, and iii) A roughened copper foil was produced in the same manner as in Example 1 except that the roughening treatment was performed under the conditions shown in Table 1A.

Example 8 (Comparison)
i) The electrode surface side of the electrolytic copper foil (that is, the side opposite to the deposition surface side, Rzjis: 1.5 μm) was subjected to a treatment such as a roughening treatment, ii) the second roughening step and the fine roughening treatment were omitted. And iii) Preparation of a roughened copper foil in the same manner as in Example 1 except that the roughening treatment (that is, the first roughening step and the third roughening step) was performed under the conditions shown in Table 1A. Went.

Various evaluations shown below were performed on the roughened copper foils produced in Evaluation Examples 1 to 8.

<10-point average roughness Rzjis>
The ten-point average roughness Rzjis of the roughened copper foil was measured with a contact surface roughness meter (Kosaka Laboratory, SE3500) in accordance with JIS B0601-2001. This measurement was performed using a diamond ball having a diameter of 2 μm as a stylus and a reference length of 0.8 mm. In addition, the measurement of Rzjis of the deposition surface or electrode surface of the electrolytic copper foil before the roughening treatment in each of the examples described above was also performed in the same procedure as described above.

<Half width in the frequency distribution of the height of the roughened particles>
The surface profile of the roughened copper foil was measured with a three-dimensional roughness analyzer (manufactured by Elionix Co., Ltd., ERA-8900) under 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 according to the size of the coarse particles. The particle size was calculated based on the measured surface profile. At that time, the height of the roughened particles measured at intervals of 0.01 μm in the z-axis (foil thickness direction) interval was regarded as the particle size. For the calculation of the rough particle size, the surface profile of the electrolytic copper foil (raw foil) before the roughening treatment is measured in advance, and the value resulting from the surface profile before the roughening treatment is calculated. Sometimes done by removing as background. A frequency distribution of the height of the roughened particles based on the height or particle size calculated in this way is created, and the full width of the frequency distribution peak at half the maximum value of the frequency distribution peak as shown in FIG. It calculated as a value range (micrometer).

<Roughening surface specific surface area>
The surface profile of a region (100 μm × 140 μm) having an area of 14000 μm ^{2 on} the roughened surface of the roughened copper foil was measured using a laser microscope (manufactured by Keyence Corporation, VK-X100) at a magnification of 2000 times. A three-dimensional surface area X (μm ² ) of the surface profile of the obtained roughened surface was calculated, and a value X / Y obtained by dividing the value of X by a measurement area Y (14000 μm ² ) was defined as a specific surface area.

<Peel strength>
As an insulating resin substrate, a liquid crystal polymer (LCP) film (Vecstar CTZ manufactured by Kuraray Co., Ltd.) having a thickness of 50 μm was prepared. Laminated copper foil is laminated on this insulating resin base material so that the roughened surface is in contact with the insulating resin base material, and hot press molding is performed at a pressure of 4 MPa and a temperature of 310 ° C. for 10 minutes to form a copper-clad laminate. A plate sample was prepared. The copper-clad laminate sample was peeled in the direction of 90 ° with respect to the surface of the insulating resin substrate in accordance with JIS C 5016-1994, Method A, and the normal peel strength (kgf / cm) was measured.

<Roughened particle cross-sectional area ratio>
The ratio of the roughened particle cross-sectional area on the roughened surface of the roughened copper foil was measured. This measurement is performed using a desktop automatic multifunctional image processing analyzer (manufactured by Nireco Corporation, LUZEX AP) and a focused ion beam processing observation apparatus (FIB), and a predetermined visual field range (8 μm × 8 μm) of the roughened surface. ) By observing the cross-section of each roughened particle and obtaining a FIB SIM image (hereinafter referred to as FIB-SIM image) at a magnification of 18000 times. The area was measured, and the ratio of the roughened particle cross-sectional area was calculated as the ratio of (closed curved cross-sectional area of the roughened particles) / (cross-sectional area of the roughened particles). The binarization setting in this image analysis was set to 127. The specific procedure was as follows.

(1) Measurement of the cross-sectional area of the roughened particles As depicted in the FIB-SIM image shown in FIG. Draw a straight line in the height direction. A reference point a is specified at a position 2 μm away from the top of the rough particles on the straight line. Two tangent lines are drawn from the reference point a to the roughened particles, and the contact points b and c between the tangent lines and the roughened particles are specified. A cross-sectional area of a cross-sectional area surrounded by a straight line connecting the contacts b and c (hereinafter referred to as a bc straight line) and a cross-sectional outline of the head of the roughened particle is obtained by image analysis, To do. Note that the reason why the distance from the top of the roughened particles is set to 2 μm in determining the reference point a is that the length of the scale of the FIB-SIM image is 2 μm, which is such a length. This is because, even if the position of the reference point a fluctuates somewhat, the positions of the contacts b and c are identified almost uniquely, so that the value of the cross-sectional area of the roughened particles can be obtained with high accuracy.

(2) Measurement of closed cross-sectional area of roughened particles FIG. 3 illustrates an enlarged image of the head of roughened particles. As depicted in the FIB-SIM image of FIG. 3, the closed curved cross-sectional area of the roughened particles is determined by measuring the tips of the fine convex shapes on the surface of the roughened particles (if fine roughened particles exist, The area of the region surrounded by the line connecting each tip) and the bc line was defined, and this was determined by image analysis. The positioning of each tip was automatically performed by software included in the image processing analyzer.

(3) Determination of roughened particle cross-sectional area ratio The roughened particle cross-sectional area ratio was calculated from the obtained closed curved cross-sectional area and the cross-sectional area of the roughened particles. The roughened particle cross-sectional area ratio was applied to each roughened particle observed for each visual field, and the average value of the roughened particle cross-sectional area ratios obtained for all the roughened particles for five visual fields was calculated.

<Transmission loss>
As an insulating resin substrate, a liquid crystal polymer (LCP) film (Vecstar CTZ manufactured by Kuraray Co., Ltd.) having a thickness of 50 μm was prepared. A roughened copper foil was laminated on both surfaces of the insulating resin base material so that the roughened surface was in contact with the insulating resin base material, and was bonded together by a batch press. As shown in FIG. 4, only the roughened copper foil on one side of the insulating resin base material 40 is etched to form a microstrip line so that the characteristic impedance is 50Ω to form the signal layer 42 (thickness 18 μm). ). On the other hand, the roughened copper foil on the opposite side of the signal layer 42 of the insulating resin substrate 40 was not etched, and was used as a ground layer 44 (thickness 18 μm). Cover the insulating resin substrate 40 on the signal layer 42 side with a 12 μm thick polyimide film (Niskan Kogyo Co., Ltd., CISV-1225) through an adhesive (AY-25KA, manufactured by Arisawa Manufacturing Co., Ltd.) coated to a thickness of 25 μm. A sample for transmission loss measurement was obtained by laminating as a ray 46. The obtained sample microstrip line is subjected to a transmission loss S of 40 GHz at a circuit length of 5 cm using a network analyzer (N5247A, Keysight Technology, Inc.) and a prober system (SUMMIT 9000, Cascade Microtech). ₂₁ was obtained.

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

Claims

A roughened copper foil having a roughened surface with roughened particles on at least one side, the roughened surface having a ten-point average roughness Rzjis of 0.6 to 1.7 μm, And the roughening process copper foil whose half value width in the frequency distribution of the height of the said roughening particle | grain is 0.9 micrometer or less.
2. The roughened copper foil according to claim 1, wherein the half width is 0.2 to 0.9 μm.
The roughened surface has a specific surface area of 1.1 to 2.1, which is obtained by dividing the three-dimensional surface area X of the roughened surface by the measurement area Y. The roughened copper foil according to claim 1 or 2, which is a value.
The roughened copper foil according to any one of claims 1 to 3, further comprising fine roughened particles finer than the roughened particles on the roughened particles.
The roughened copper foil 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.
The roughened copper foil according to any one of claims 1 to 5, which is used for a printed wiring board for high frequency applications.
A printed wiring board for high frequency applications, comprising the roughened copper foil according to any one of claims 1 to 6 and an insulating resin layer provided in close contact with the roughened surface of the copper foil. .
The printed wiring board for high frequency applications according to claim 7, wherein the insulating resin layer comprises a liquid crystal polymer.