TW202002731A - Roughened copper foil, copper clad laminate and printed wiring board - Google Patents

Abstract

To provide a roughened copper foil which is capable of significantly improving the heat-resistant peel strength between itself and a thermoplastic resin that has low dielectric constant. A roughened copper foil that has a roughened surface on at least one side, said roughened surface being composed of needle-like crystals and/or plate-like crystals, which contain cuprous oxide and/or copper oxide. With respect to this roughened copper foil, the roughened surface has a cuprous oxide thickness of 71-300 nm as determined by sequential electrochemical reduction analysis (SERA) and a copper oxide thickness of 0-20 nm as determined by sequential electrochemical reduction analysis (SERA).

Description

Roughened copper foil, copper-clad laminate and printed wiring board

The invention relates to a roughened copper foil, a copper-clad laminate and a printed wiring board.

Copper foil for printed wiring boards suitable for forming fine pitch circuits has been proposed as a roughening copper foil, which has fine irregularities formed by oxidation treatment and reduction treatment (hereinafter collectively referred to as redox treatment) as coarse化处理面。 Treatment surface.

For example, Patent Document 1 (International Publication No. 2014/126193) discloses a surface-treated copper foil having a roughened layer on the surface, the roughened layer being needle-shaped fine particles composed of a copper composite compound with a maximum length of 500 nm or less Concave and convex. In addition, Patent Document 2 (International Publication No. 2015/040998) discloses a copper foil having a roughening treatment layer and a silane coupling agent treatment layer on at least one side, the roughening treatment layer having a maximum length of 500 nm composed of a copper composite compound The fine concavo-convex formed by the following needle-shaped convex portions, the silane coupling agent treatment layer is on the surface of the roughening treatment layer. According to the roughened copper foil of the above-mentioned document, the anchor effect produced by the fine irregularities of the roughened layer can provide good adhesion to the insulating resin substrate and can form a layer with a good etching factor. Fine pitch circuit. The roughening treatment layers with fine irregularities disclosed in Patent Documents 1 and 2 are formed by performing preliminary treatment such as alkaline degreasing treatment and then undergoing oxidation-reduction treatment. The fine concavo-convex formed in this way has a unique shape composed of needle-like crystals and/or plate-like crystals of the copper composite compound, and the roughened surface provided with the fine concavo-convex is roughly larger than the roughened surface formed by the adhesion of fine copper particles Or the roughened surface provided with etching by the etching is finer.

On the other hand, in recent years, with the increasing performance of portable electronic devices, in order to process large amounts of information at high speed, the high frequency of signals continues to develop, and a printed wiring board suitable for high frequency applications is required. Such high-frequency printed wiring boards are required to reduce transmission loss in order to transmit high-frequency signals without degrading quality. The printed wiring board is equipped with copper foil processed into a wiring pattern and an insulating resin substrate. However, the transmission loss is mainly due to the conductor loss caused by the copper foil and the dielectric loss caused by the insulating resin substrate. Therefore, in order to reduce the dielectric loss caused by the insulating resin substrate, it is preferable to use a thermoplastic resin with a low dielectric constant. However, the low dielectric constant thermoplastic resins represented by fluororesins such as polytetrafluoroethylene (PTFE) or liquid crystal polymer (LCP) resins are different from thermosetting resins in that they have low chemical activity and therefore have low adhesion to copper foil. The problem.

As a method for manufacturing the copper-clad laminate to solve this problem, there has been proposed a method of improving the adhesion with the thermoplastic resin by controlling the oxidation state of the roughened surface of the roughened copper foil. For example, Patent Document 3 (International Publication No. 2017/150043) discloses a method for manufacturing a copper-clad laminate to which a thermoplastic resin sheet is bonded to a roughened copper foil having a roughened surface, which is provided with Fine concavo-convex composed of needle-like crystals of copper oxide and cuprous oxide, Patent Document 3 describes that the roughened surface is measured by continuous electrochemical reduction (SERA) with a thickness of copper oxide of 1-20 nm, and the oxidation is measured by SERA Cuprous thickness is 15 ~ 70nm. According to this method, the affinity of the roughened surface of the roughened copper foil and the thermoplastic resin is improved, and as a result, high peel strength can be achieved.

Patent Document 1 is International Publication No. 2014/126193, Patent Document 2 is International Publication No. 2015/040998, and Patent Document 3 is International Publication No. 2017/150043.

In addition, in the automotive field in recent years, safe driving support systems such as collision avoidance functions are rapidly spreading, and millimeter wave sensors are utilized in this system. Therefore, the demand for high-frequency printed wiring boards used in millimeter wave sensors and the like has also increased. In this regard, vehicle-mounted millimeter wave sensors are used under high-temperature conditions around the engine. Therefore, from the viewpoint of maintaining high reliability, the printed wiring board mounted on a machine used in such a severe environment needs to be kept between the copper foil and the resin even after being exposed to a high temperature (such as 150°C) for a long time. High density. However, in the case of pasting a conventional roughened copper foil to a thermoplastic resin, the adhesion force is reduced due to long-term heating, and further improvement is required.

The present inventors found that the thickness of the cuprous oxide and copper oxide measured by the continuous electrochemical reduction method (SERA) for the roughened copper foil having a roughened surface made of needle crystals and/or plate crystals The thickness is controlled within the specified range, thereby significantly improving the heat-resistant peel strength of the low dielectric constant thermoplastic resin.

Therefore, an object of the present invention is to provide a roughened copper foil that can significantly improve the heat-resistant peel strength of a thermoplastic resin with a low dielectric constant.

According to an embodiment of the present invention, there is provided a roughened copper foil having a roughened surface on at least one side, the roughened surface comprising needle-like crystals including cuprous oxide and/or copper oxide and/or The plate-shaped crystal is composed of the roughened surface. The thickness of the cuprous oxide measured by the continuous electrochemical reduction method (SERA) is 71 to 300 nm, and the thickness of the copper oxide measured by the continuous electrochemical reduction method (SERA) is 0 to 20 nm. .

According to another embodiment of the present invention, there is provided a copper-clad laminate including the roughened copper foil and an insulating resin substrate provided on at least one side of the roughened copper foil.

Another embodiment of the present invention provides a printed wiring board provided with the roughened copper foil.

"Roughening Copper Foil" The copper foil of the present invention is a roughening copper foil. At least one side of this roughened copper foil has a roughened surface. The roughened surface is composed of needle crystals and/or plate crystals. These needle crystals and/or plate crystals form fine irregularities and form roughened surfaces. The needle crystals and/or plate crystals include cuprous oxide (Cu ₂ O) and copper oxide (CuO) as required. That is, cuprous oxide is an essential component, and copper oxide is an arbitrarily added component. In addition, the roughened surface has a thickness of cuprous oxide measured by the continuous electrochemical reduction method (SERA) of 71 to 300 nm, and a thickness of copper oxide measured by the continuous electrochemical reduction method (SERA) of 0 to 20 nm. In this way, the thickness of the cuprous oxide and the thickness of the copper oxide measured by the continuous electrochemical reduction method (SERA) are controlled within the above ranges, respectively, whereby the heat-resistant peel strength of the thermoplastic resin with a low dielectric constant can be significantly improved. In other words, when the conventional roughened copper foil is bonded to the thermoplastic resin as described above, the adhesion force is reduced due to long-term heating in a severe environment such as high-temperature conditions around the engine. The reduction in peel strength (ie, heat-resistant peel strength) between the copper foil and the resin accompanying the high-temperature treatment used is considered to be caused by the diffusion of copper constituting the copper foil into the resin substrate. In order to prevent the diffusion of copper, it is generally carried out by applying antirust treatment of metals such as zinc or nickel on the surface of the copper foil, but thermoplastic resins such as polytetrafluoroethylene (PTFE) cannot sufficiently prevent the diffusion of copper. Compared with this, the roughened copper foil of the present invention has a predetermined amount of cuprous oxide measured on the roughened surface by continuous electrochemical reduction (SERA) conversion thickness, compared with pure copper (Cu) The stabilized cuprous oxide acts as a diffusion prevention layer, thereby effectively suppressing the diffusion of copper into the thermoplastic resin base material. In addition, the cuprous oxide that forms the roughened surface is a non-conducting non-conductor component, so even if the roughness is large in order to enhance the adhesion with the thermoplastic resin, the skin of the copper foil is not likely to occur when transmitting high-frequency signals Signal attenuation caused by the effect. As a result, it has been found that when the roughened copper foil of the present invention and a low dielectric constant thermoplastic resin are laminated to form a copper-clad laminate or printed wiring board, the transmission loss of high-frequency signals can be significantly reduced, and excellent heat-resistant peeling can be exerted strength.

From the above point of view, the roughened surface of the roughened copper foil measured by the continuous electrochemical reduction method (SERA) has a thickness of cuprous oxide of 71 to 300 nm, preferably 100 to 300 nm, more preferably 120 to 300 nm, It is also preferably 200 to 300 nm, and particularly preferably 250 to 300 nm. In addition, the roughened surface of the roughened copper foil measured by the continuous electrochemical reduction method (SERA) has a copper oxide thickness of 0 to 20 nm, preferably 1 to 20 nm, more preferably 2 to 15 nm, and still more preferably 3 ~10nm. With this, the desired acid resistance can be imparted to the roughened copper foil, and the heat-resistant peel strength with the thermoplastic resin can be further improved.

The SERA analysis system for measuring the thickness of the copper oxide and the thickness of the cuprous oxide can be carried out using a commercially available SERA analysis device (for example, QC-100 manufactured by ECI Technology Co., Ltd.), for example, by the following procedure. First, the 8.0 mm ² area of the roughened copper foil was isolated with an O-ring gasket for analysis, and boric acid buffer solution was injected and saturated with nitrogen. Apply a current density I _{d of} 30 μA/cm ² to the above area, and measure the time required for the Cu ₂ O reduction reaction occurring at -0.40V to -0.60V and the CuO reduction reaction occurring at -0.60V to -0.85V, respectively As t ₁ and t ₂ (seconds). The thickness T (nm) of each of CuO and Cu ₂ O is calculated using the constant K obtained by Faraday's law, according to the equation of T=K‧I _d ‧t. In addition, the value of the constant K related to CuO is 6.53×10 ^-5 (cm ³ /A‧sec), and the value of the constant K related to Cu ₂ O is 2.45×10 ^-4 (cm ³ /A‧sec).

The needle-like crystals and/or plate-like crystals constituting the roughening surface of the roughening-treated copper foil can be formed by redox treatment, and typical needle-like crystals and/or plate-like crystals can be observed relative to the copper foil The surface grows densely in a vertical direction and/or grows obliquely in a dense direction (such as turf). Needle crystals and plate crystals need not be clearly distinguished from each other, and may be plate crystals that look like needles or needle crystals that look like plates.

The roughened copper foil preferably has roughened surfaces on both sides. In other words, in addition to the surface intended to be bonded to the resin, the roughened copper foil preferably has the roughened surface on the opposite side. With this, excellent laser processability can be achieved on the surface on the opposite side. This is considered to be because the cuprous oxide constituting the roughened surface has a better CO ₂ laser absorption rate than pure copper, and the uneven shape formed by needle crystals and/or plate crystals can also obtain CO ₂ The effect of laser absorption by radiation. Therefore, when direct laser drilling is performed on the copper foil of the copper-clad laminate to directly irradiate the CO ₂ laser to form a through hole, by using the surface irradiated with the laser as the roughening surface, it is not necessary to Pre-treatments such as blackening treatment on the foil surface can be used for hole drilling, which greatly improves productivity.

The thickness of the roughened copper foil is not particularly limited, but it is preferably 0.1 to 70 μm, and more preferably 0.5 to 18 μm. In addition, the roughened copper foil of the present invention is not limited to those that roughen the surface of a general copper foil, but may also roughen the surface of a copper foil with a carrier copper foil.

The roughened copper foil preferably has an organic anti-rust layer on the roughened surface. The organic antirust layer is not particularly limited, and preferably contains at least one of a triazole compound and a silane coupling agent. Examples of triazole compounds include benzotriazole, carboxybenzotriazole, methylbenzotriazole, aminotriazole, nitrobenzotriazole, hydroxybenzotriazole, chlorobenzotriazole, and ethylbenzene Pyrogallazole, naphthotriazole. The silane coupling agent is, for example, epoxy functional silane coupling agent such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, or 3-amino group Propyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-2(aminoethyl)3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyl Amine functional silane coupling agent such as trimethoxysilane, or mercapto functional silane coupling agent such as 3-mercaptopropyltrimethoxysilane, or vinyltrimethoxysilane, vinylphenyltrimethoxysilane, etc. Vinyl-functional silane coupling agent, or 3-methacryl propyl propyl trimethoxy silane and other methacryl functional silane coupling agent, or 3-propenyl propyl propyl trimethoxy silane, etc. Acrylic functional silane coupling agent, imidazole functional silane coupling agent such as imidazole silane, or triazine functional silane coupling agent such as triazine silane. The organic anticorrosive layer more preferably contains a triazole compound. Preferred examples of the triazole compound include benzotriazole (BTA) and carboxybenzotriazole (CBTA). In the case where the thermoplastic resin adhering to the roughened copper foil is a fluororesin, an organic antirust layer containing triazole compounds such as BTA and CBTA is particularly preferred. The reason why the triazole compound is preferable is listed as follows. It is considered that the triazole compound forms a copper complex with the cuprous oxide on the roughened surface. Compared with the case where it is formed on a general copper foil, the component adheres densely to the surface, so it can exert an excellent rust prevention function. Therefore, the thickness of the copper oxide and the thickness of the cuprous oxide when storing the roughened copper foil for a long period of time can be easily maintained within the above-defined range. In addition, when exposed to severe environments such as high temperatures, it is considered that the organic anti-corrosion layer containing a triazole compound maintains fine irregularities on the surface, and therefore high reliability can be maintained.

"Manufacturing method" The roughened copper foil of the present invention can be produced by any method, preferably by redox treatment. An example of a preferred method of manufacturing the roughened copper foil of the present invention will be described below. This preferred manufacturing method includes a step of preparing a copper foil, a step of attaching a specific organic substance to the copper foil, and a step of sequentially performing oxidation treatment and reduction treatment (redox treatment) on the surface of the copper foil to which the organic substance is attached.

(1) Preparation of copper foil As the copper foil used for the production of the roughened copper foil, both electrolytic copper foil and rolled copper foil can be used, and electrolytic copper foil is preferred. In addition, the copper foil may be a copper foil without roughening, or may be a copper foil roughened in advance. The thickness of the copper foil is not particularly limited, but it is preferably 0.1 to 70 μm, and 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 can use a wet film forming method such as electroless copper plating and electrolytic copper plating, a dry film forming method such as sputtering and chemical vapor deposition, or the like Combination.

The surface of the copper foil subjected to the roughening treatment has a maximum height Sz measured based on ISO25178 of preferably 1.5 μm or less, more preferably 1.2 μm or less, and still more preferably 1.0 μm or less. Within the above range, the roughened copper foil of the present invention can easily achieve a desired surface profile. The lower limit of Sz is not particularly limited, and Sz is preferably 0.1 μm or more, more preferably 0.2 μm or more, and still more preferably 0.3 μm or more.

(2) Organic matter attachment treatment A specific organic substance is attached to the surface of the copper foil. The adhesion of organic matter is preferably carried out in the pickling process. For example, it is preferable to immerse the copper foil in the pickling solution to which a specific organic substance is added and then wash with water. Thereby, specific organic substances can be attached to the surface of the copper foil, and in the oxidation-reduction treatment step described later, a roughened copper foil having surface characteristics favorable for adhesion to the resin and laser processability can be obtained. The organic substance added to the pickling solution is preferably a sulfonic acid or its salt of an active organic sulfur compound that forms a coating on the copper surface. Examples of the sulfonic acid or salt of the active organic sulfur compound include bis-(3-sulfopropyl) disulfide, 3-mercapto-1-propanesulfonic acid, and 3-(N,N-dimethylaminosulfide Methyl)-thiopropanesulfonic acid, 3-[(amino-iminomethyl)thio]-1-propanesulfonic acid, o-ethyldithiocarbonate-S-(3-sulfonate Acid propyl)-ester, 3-(benzothiazolyl-2-mercapto)-propyl-sulfonic acid, ethylenedithiodipropylsulfonic acid, thioglycolic acid, phosphorothioate-o-ethyl-bis- (ω-sulfopropyl) disodium salt, thiophosphoric acid-ginseng-(ω-sulfopropyl) trisodium salt, etc. The preferred concentration of the sulfonic acid or its salt (for example, bis-(3-sulfopropyl) disulfide) of the active organic sulfur compound of the pickling solution is 25-200 ppm, more preferably 50-150 ppm. The pickling solution is preferably a sulfuric acid-based aqueous solution. The sulfuric acid concentration of the sulfuric acid-based aqueous solution is not particularly limited, but is preferably 1 to 20% by volume. In addition, the immersion time of the copper foil in the sulfuric acid-based aqueous solution is not particularly limited, but is preferably 2 seconds to 2 minutes.

(3) Redox treatment The surface of the copper foil subjected to the above-mentioned pickling treatment as described above is preferably subjected to a wet roughening step in which oxidation treatment and reduction treatment are sequentially performed. In particular, a copper compound containing copper oxide (copper (II) oxide) is formed on the surface of the copper foil by oxidizing the surface of the copper foil by a wet method using a solution. Afterwards, the copper compound is subjected to reduction treatment to convert part or all of the copper oxide to cuprous oxide (copper oxide (I)), whereby the surface of the copper foil can be formed of copper oxide and copper oxide (if any Existing conditions) Fine concavo-convex composed of needle-like crystals and/or plate-like crystals composed of a copper composite compound. Here, the fine irregularities are formed by a copper compound containing copper oxide as the main component during the oxidation treatment of the copper foil surface by the wet method. In addition, when the copper compound is subjected to reduction treatment, the shape of the fine irregularities formed by the copper compound is roughly maintained, and some or all of the copper oxide is converted into cuprous oxide, including cuprous oxide and copper oxide (if any exist). Case) Fine irregularities composed of a copper composite compound. In this way, after appropriate oxidation treatment is applied to the copper foil surface by a wet method, reduction treatment is performed, whereby fine irregularities can be formed.

(3a) Oxidation treatment The copper foil subjected to the above-mentioned pickling treatment is subjected to oxidation treatment using an alkaline solution such as sodium hydroxide solution. The alkaline solution (oxidation treatment solution) has the function of finely corroding copper foil, and the function of re-precipitating copper ions eluted by corrosion. Therefore, by treating the surface of the copper foil with an alkaline solution, fine irregularities composed of needle-like crystals and/or plate-like crystals composed of a copper composite compound containing copper oxide as a main component can be formed on the surface of the copper foil. At this time, it is considered that by attaching specific organic substances to the copper foil in advance as described above, the density of corrosion and reprecipitation of the copper foil by the alkaline solution is lowered, and the corrosion and reprecipitation are concentrated in part. As a result, a roughened copper foil having surface characteristics favorable for adhesion to resin and laser processability, which is difficult to be produced by general oxidation treatment, can be obtained. The temperature of the alkaline solution is preferably 60 to 85°C, and the pH of the alkaline solution is preferably 10 to 14. From the viewpoint of oxidation, the alkaline solution preferably contains chlorate, chlorite, hypochlorite, and perchlorate, and the concentration thereof is preferably 100 to 500 g/L. The oxidation treatment is preferably performed by immersing the electrolytic copper foil in an alkaline solution, and the immersion time (ie, oxidation time) is preferably 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes.

The alkaline solution used for the oxidation treatment preferably further contains an oxidation inhibitor. In other words, when an oxidation treatment is applied to the copper foil surface with an alkaline solution, the convex portions of the fine irregularities may grow excessively and exceed a desired length, making it difficult to form the desired fine irregularities. Here, in order to form the above-mentioned fine irregularities, it is preferable to use an alkaline solution containing an oxidation inhibitor, which can suppress the oxidation of the copper foil surface. Examples of preferred oxidation inhibitors include amine-based silane coupling agents. By using an alkaline solution containing an amine-based silane coupling agent to oxidize the copper foil surface, the amine-based silane coupling agent in the alkaline solution is adsorbed on the surface of the copper foil, which can suppress the oxidation of the copper foil surface by the alkaline solution . As a result, the growth of the needle-shaped crystals and/or plate-shaped crystals of copper oxide can be suppressed, and a preferable roughened surface having desired fine irregularities can be formed. Specific examples of the amine-based silane coupling agent include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-amine 3-propyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl -Butylene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, etc., particularly preferably N-2-(aminoethyl)-3-aminopropyltrimethoxysilane. Any of the above are soluble in alkaline solution, maintain stability in the alkaline solution, and exert the effect of inhibiting the oxidation of the copper foil surface. The preferred concentration of the amine-based silane coupling agent (such as N-2-(aminoethyl)-3-aminopropyltrimethoxysilane) in the alkaline solution is 0.01-20 g/L, more preferably 0.02-20 g /L.

(3b) Reduction treatment The copper foil subjected to the above-mentioned oxidation treatment (hereinafter referred to as oxidation-treated copper foil) is subjected to reduction treatment using a reduction treatment solution. By reduction treatment, a part or all of the copper oxide is converted to cuprous oxide (copper oxide (I)), whereby the surface of the copper foil can be composed of cuprous oxide and copper oxide (if any) Fine irregularities composed of needle-like crystals and/or plate-like crystals composed of copper composite compounds. This reduction treatment can be carried out by contacting the oxidation treatment copper foil with the reduction treatment solution, preferably by dipping the oxidation treatment copper foil in the reduction treatment solution, or dipping the reduction treatment solution in the oxidation treatment copper foil, treatment time It is preferably 2 to 60 seconds, and more preferably 5 to 30 seconds. In addition, the reduction treatment solution is preferably an aqueous solution of dimethylamine borane, and the aqueous solution preferably contains dimethylamine borane at a concentration of 10 to 40 g/L. In addition, the dimethylamine borane aqueous solution is preferably adjusted to pH 12 to 14 using sodium carbonate and sodium hydroxide. At this time, the temperature of the aqueous solution is not particularly limited, and it may be room temperature. The copper foil thus reduced is preferably washed with water and dried.

(4) Anti-rust treatment The copper foil may be subjected to an anti-rust treatment with an organic anti-rust agent as desired to form an organic anti-rust layer. In this way, the roughened surface of the roughened copper foil can be maintained, and the respective contents of cuprous oxide and copper oxide measured by SERA conversion thickness can be controlled within the prescribed ranges, and the insulating resin can be easily maintained in this maintained state The substrate is attached to the roughened surface. In addition, moisture resistance, chemical resistance, adhesion to adhesives, etc. can also be improved. The organic anti-rust layer is not particularly limited, and preferably contains at least one of a triazole compound and a silane coupling agent. Examples of triazole compounds include benzotriazole, carboxybenzotriazole, methylbenzotriazole, aminotriazole, nitrobenzotriazole, hydroxybenzotriazole, chlorobenzotriazole, ethyl Benzotriazole and naphthotriazole, especially benzotriazole. The silane coupling agent is, for example, epoxy functional silane coupling agent such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, or 3-amino group Propyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-2(aminoethyl)3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyl Amine functional silane coupling agent such as trimethoxysilane, or mercapto functional silane coupling agent such as 3-mercaptopropyltrimethoxysilane, or vinyltrimethoxysilane, vinylphenyltrimethoxysilane, etc. Vinyl-functional silane coupling agent, or 3-methacryl propyl propyl trimethoxy silane and other methacryl functional silane coupling agent, or 3-propenyl propyl propyl trimethoxy silane, etc. Acrylic functional silane coupling agent, imidazole functional silane coupling agent such as imidazole silane, or triazine functional silane coupling agent such as triazine silane. The organic anti-rust layer can be formed by appropriately diluting an organic anti-rust agent such as a triazole compound or a silane coupling agent, and then coating and drying.

"Copper Laminated Board" The roughened copper foil of the present invention is preferably used for the production of copper-laminated laminates. In other words, according to a preferred aspect of the present invention, the roughened copper foil and the copper-clad laminate are provided, and the copper-clad laminate has an insulating resin substrate provided on the roughened surface of the roughened copper foil. The roughened copper foil can be installed on one side of the insulating resin substrate or on both sides. The insulating resin substrate is preferably a prepreg and/or resin sheet. The general name of the composite material impregnated with synthetic resin on the base materials such as synthetic resin board, glass board, glass fiber woven fabric, glass fiber non-woven fabric, paper, etc. On the other hand, the resin sheet may be a cut sheet or a long sheet drawn by a roller, and its form is not particularly limited. In addition, from the viewpoint of improving insulation, the insulating resin substrate may contain filler particles composed of various inorganic particles such as silica and alumina. The thickness of the insulating resin substrate is not particularly limited, but it is preferably 1 to 1000 μm, more preferably 2 to 400 μm, and still more preferably 3 to 200 μm. The insulating resin substrate may also be composed of several layers.

From the viewpoint of providing a copper-clad laminate suitable for high-frequency applications, the insulating resin base material preferably contains a thermoplastic resin, and more preferably the resin component contained in the insulating resin base material is mostly (for example, 50% by weight or more) or Almost all (for example, 80% by weight or more or 90% by weight or more) are thermoplastic resins. The thermoplastic resin is preferably exemplified by polysulfonate (PSF), polyether sulfonate (PES), amorphous polyarylate (PAR), liquid crystal polymer (LCP), polyetheretherketone (PEEK), thermoplastic polyimide ( PI), polyamidoamide imide (PAI), fluororesin, polyamide (PA), nylon, polyoxymethylene (POM), modified polyphenylene ether (m-PPE), polyethylene terephthalate Ester (PET), glass fiber reinforced polyethylene terephthalate (GF-PET), cyclic olefin (COP) and any combination of these. From the viewpoint of the expected loss factor and excellent heat resistance, better examples of thermoplastic resins include polysulfonate (PSF), polyether sulfonate (PES), amorphous polyarylate (PAR), and liquid crystal polymer (LCP) ), polyetheretherketone (PEEK), thermoplastic polyimide (PI), polyamidoimide (PAI), fluororesin and any combination of these. From the viewpoint of low dielectric constant, the particularly preferred thermoplastic resin is a fluororesin. The fluororesin preferably includes, for example, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-ethylene copolymerization. (ETFE) and any combination of these. In addition, the bonding of the insulating resin base material to the roughened copper foil is preferably performed while applying pressure while heating, whereby the thermoplastic resin can be softened and embedded in the fine irregularities of the roughened surface. As a result, it is possible to ensure the adhesion between the copper foil and the resin by anchoring the fine irregularities (especially needle crystals and/or plate crystals) into the resin.

"Printed Wiring Board" The roughened copper foil of the present invention is preferably used for the production of printed wiring boards. In other words, according to a preferred aspect of the present invention, a printed wiring board provided with the roughened copper foil described above is provided. Specific examples of the printed wiring board include a single-sided or double-sided printed wiring board forming a circuit on the copper-clad laminate of the present invention, or a multilayer printed wiring board in which the circuit is multilayered. The multilayer printed wiring board may be a multilayer copper-clad laminated board in which an inner layer substrate is laminated with a copper foil via a thermoplastic resin layer, or a build-up may be further formed. In addition, the circuit formation method may be a subtractive method or a modified semi-additive (MSAP) method. The printed wiring board with roughened copper foil of the present invention can be applied to high-frequency antennas used in automotive antennas, mobile phone base station antennas, high-performance servers, anti-collision radars, etc. used in high-frequency regions with signal frequencies above 10 GHz. Frequency substrate. In particular, the printed wiring board of the present invention is provided with the above-mentioned roughened copper foil, and the copper foil and the thermoplastic resin have excellent heat-resistant peel strength. Therefore, they are extremely suitable for use in high-temperature machines such as automotive millimeter wave sensors. High frequency substrate.

Examples: The following examples illustrate the present invention more specifically.

"Examples 1 to 4" (1) Preparation of roughened copper foil (1a) Preparation of electrolytic copper foil A sulfuric acid copper sulfate solution containing the composition shown below was used as a copper electrolyte, a titanium rotating electrode was used for the cathode, and an anode Using DSA (Dimensionally Stable Anode), electrolysis was performed at a solution temperature of 45°C and a current density of 55 A/dm ^{2 to} obtain an electrolytic copper foil with a thickness of 18 μm. The maximum height Sz of the precipitation surface of the electrolytic copper foil and the electrode surface is measured according to ISO25178 using a laser microscope (VK-X100 manufactured by KEYENCE Co., Ltd.). The Sz of the precipitation surface is 0.8 μm, and the Sz of the electrode surface is 1.2 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 diallyl dimethyl chloride Ammonium polymer concentration: 50 mg/L Chlorine concentration: 40 mg/L

(1b) Organic matter attachment treatment The electrolytic copper foil obtained above was immersed in an organic-containing sulfuric acid aqueous solution having a liquid temperature of 40° C., a bis(3-sulfopropyl) disulfide concentration of 100 ppm, and a sulfuric acid concentration of 10% by volume for 23 seconds (Example 1 and Example 2) After 5 minutes (Example 3 and Example 4), wash with water.

(1c) Roughening treatment (redox treatment) Both sides of the electrolytic copper foil subjected to the above-mentioned pickling treatment were subjected to roughening treatment (redox treatment) as shown below. In other words, the oxidation treatment and reduction treatment shown below are performed in order.

Oxidation treatment: The electrolytic copper foil subjected to the above-mentioned pickling treatment was oxidized. This oxidation treatment is to immerse the electrolytic copper foil in a liquid temperature of 75°C, pH=12, chlorite concentration of 100～500g/L, N-2-(aminoethyl)-3-aminopropyltrimethoxy Sodium hydroxide solution with a concentration of 10 g/L of sodium silane was used for 3 minutes (Example 1 and Example 3) or 10 minutes (Example 2 and Example 4). In this way, fine irregularities composed of needle-like crystals and/or plate-like crystals composed of a copper composite compound are formed on both sides of the electrolytic copper foil.

Restore processing: The sample subjected to the above-mentioned oxidation treatment is subjected to reduction treatment. This reduction treatment is to immerse a sample formed with fine irregularities by the above oxidation treatment into an aqueous solution adjusted to pH=13 using sodium carbonate and sodium hydroxide and having a dimethylamine borane concentration of 10 to 40 g/L for 1 minute. get on. At this time, the temperature of the aqueous solution is room temperature. The sample thus subjected to reduction treatment was washed with water and dried. Through the above steps, part of the copper oxide on both sides of the electrolytic copper foil is reduced to cuprous oxide to form a roughened surface, which has fine irregularities composed of a copper composite compound containing copper oxide and cuprous oxide. In this way, a roughened copper foil having a roughened surface composed of needle crystals and/or plate crystals on both sides is obtained.

(1d) Formation of organic antirust layer The roughened copper foil obtained above was subjected to the formation of an organic antirust layer. This organic anti-rust layer is formed by immersing the roughened copper foil in an aqueous solution containing benzotriazole with a concentration of 6 g/L as an organic anti-rust agent at a liquid temperature of 25° C. for 30 seconds, and then exposed to hot air at 180° C. 10 Let it dry in seconds.

(2) Evaluation of roughened copper foil The following various evaluations were performed on the roughened copper foil produced.

SERA measurement: The thickness of copper oxide (CuO) and the thickness of cuprous oxide (Cu ₂ O) of the roughened surface of the roughened copper foil were measured by the continuous electrochemical reduction method (SERA). For this SERA analysis, QC-100 manufactured by ECI Technology was used as the measuring device. Proceed as follows. First, the 8.0 mm ² area of the roughened copper foil was isolated with an O-ring gasket for analysis, and boric acid buffer solution was injected and saturated with nitrogen. Apply a current density I _{d of} 30 μA/cm ² to the above area, and measure the time required for the Cu ₂ O reduction reaction occurring at -0.40V to -0.60V and the CuO reduction reaction occurring at -0.60V to -0.85V, respectively As t ₁ and t ₂ (seconds). The thickness T (nm) of each of CuO and Cu ₂ O is calculated using the constant K obtained by Faraday's law, according to the equation of T=K‧I _d ‧t. In addition, the value of the constant K related to CuO is 6.53×10 ^-5 (cm ³ /A‧sec), and the value of the constant K related to Cu ₂ O is 2.45×10 ^-4 (cm ³ /A‧sec). The above constant K is calculated based on the formula K=M/(z‧F‧ρ) (where M is the molecular weight, z is the number of charges, F is the Faraday constant, and ρ is the density).

That is, the constant K (=6.53×10 ^-5 (cm ³ /A‧sec)) related to CuO is calculated by entering the following value in the formula of K=M/(z‧F‧ρ). M (molecular weight) = 79.545 (g/mol) z (charge number) = 2 (CuO+H ₂ O+2e-→Cu+2OH-) F (Faraday constant) = 96494 (C/mol) = 96500 (A･ sec/mol) Ρ (density) = 6.31 (g/cm ³ )

In addition, the constant K (=2.45×10 ^-4 (cm ³ /A‧sec)) related to Cu ₂ O is calculated by entering the following value in the formula of K=M/(z‧F‧ρ). M (molecular weight) = 143.09 (g/mol) z (charge number) = 1 (Cu ₂ O+H ₂ O+2e-→ 2Cu+2OH-) F (Faraday constant) = 96494 (C/mol) = 96500 ( A･sec/mol) Ρ(density)=6.04(g/cm ³ )

Observation of roughened surface (fine irregularities): Observe the surface and cross section of the fine irregularities (precipitation surface side) constituting the roughened surface of the roughened copper foil by SEM. Any one of Examples 1 to 4 can be confirmed that the roughened surface consists of countless plate-like surfaces The needle-like crystals are formed by fine irregularities.

Normal peel strength of thermoplastic resin (PTFE): A PTFE substrate (RO3003 Bondply, manufactured by ROGERS Corporation, thickness 125 μm) was prepared as a thermoplastic resin substrate. The roughened copper foil (thickness 18 μm) just finished by the above SERA measurement was laminated on this PTFE substrate so that the roughened surface of the roughened copper foil was in contact with the substrate, using a vacuum press at a pressure of 2.4 MPa At a temperature of 370°C and a pressing time of 30 minutes, a copper-clad laminate was produced under pressure. Next, a test circuit having a linear circuit for measuring the peel strength of 0.4 mm in width was produced on the copper-clad laminate by an etching method. According to the method A (90 degree peeling) of JIS C 5016-1994, the linear circuit thus formed was peeled from the PTFE substrate, and the normal peel strength (kgf/cm) was measured. This measurement is performed using a table material testing machine (STA-1150, manufactured by ORIENTEC Co., Ltd.). The results are shown in Table 1.

Heat-resistant peel strength of thermoplastic resin (PTFE): Except that a test substrate with a linear circuit for measuring the peel strength of 0.4 mm is placed in an oven and heated at 150° C. or 171° C. for 10 days, the same procedure as described above for the normal peel strength of a thermoplastic resin (PTFE) is used to measure Heat-resistant peel strength of PTFE (kgf/cm). The results are shown in Table 1. In addition, the expected value of the heat-resistant peel strength determined by the UL standard is 0.36 kgf/cm or more under any of the above conditions.

Laser processability: Using the roughened copper foil obtained in the above (1), a laminate for evaluation of laser processability was produced as follows. First, a PTFE base material (RO3003 Bondply, manufactured by ROGERS Corporation, thickness 125 μm) was prepared as a thermoplastic resin base material. Next, the roughened copper foil obtained in (1) above was laminated on both sides of the PTFE substrate so that the roughened surface of the roughened copper foil was in contact with the substrate, using a vacuum press at a pressure of 2.4 Pressure was applied under the conditions of MPa, temperature 370°C, and pressing time for 30 minutes to obtain a laminate for evaluation of laser processability. In addition, since the roughened copper foil obtained in the above (1) is subjected to the same roughening treatment on both sides, there is an adhesion surface between the roughened copper foil and the PTFE substrate and a surface opposite to the adhesion surface The same roughened surface. For the obtained laminate for evaluation of laser processability, carbon dioxide laser was used, and the conditions were as follows: photomask diameter 2.0 mm, pulse width 14 μsec, pulse energy 19.3 mJ, offset 0.8, laser light diameter 153 μm, target aperture 70 μm The roughened copper foil was subjected to laser processing, and 100 through-holes were formed in each case. The through-holes penetrated the roughened copper foil and the thermoplastic resin and reached the other side of the roughened copper foil. The processed diameter of the formed through-hole was measured, the ratio of the through-hole diameter near the target aperture (70 μm±5 μm) was calculated, and the following criteria were used for classification evaluation. The results are shown in Table 1. Evaluation A: The ratio of the through hole diameter of 70 μm±5 μm is 80% or more. Evaluation B: The ratio of the 70 μm±5 μm through pore diameter is 60% or more and less than 80%. Evaluation C: The ratio of the through hole diameter of 70 μm±5 μm was less than 60%.

Example 5 (comparison): The electrolytic copper foil is immersed in a sulfuric acid aqueous solution having a liquid temperature of 40° C. and a sulfuric acid concentration of 10% by volume for 23 seconds, and then washed with water without acid pickling treatment to replace the organic matter adhesion treatment of (1b) above. The roughened copper foil was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 6 (comparison): The electrolytic copper foil is immersed in a sulfuric acid aqueous solution with a liquid temperature of 40° C. and a sulfuric acid concentration of 10% by volume for 23 seconds, and then washed with an acid pickling treatment (no organic matter is added) such as water washing to replace the organic matter adhesion treatment of (1b) Otherwise, the roughened copper foil was prepared and evaluated in the same manner as in Example 2. The results are shown in Table 1.

Example 7 (comparison): The electrolytic copper foil was immersed in a sulfuric acid aqueous solution having a liquid temperature of 40° C. and a sulfuric acid concentration of 10% by volume for 23 seconds, followed by washing with water without acid addition treatment to replace the organic matter adhesion treatment of (1b) above, and through the following steps An inorganic rust prevention layer was formed instead of the organic rust prevention layer (1d), except that the roughened copper foil was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Formation of inorganic antirust layer: The roughened copper foil is subjected to antirust treatment consisting of inorganic antirust treatment and chromate treatment. First, as an inorganic anti-rust treatment, pyrophosphoric acid was used, and zinc pyrophosphate concentration was 80g/L, zinc concentration 0.2g/L, nickel concentration 2g/L, liquid temperature 40°C, current density 0.5A/dm ^2- Nickel alloy anti-rust treatment. Next, as a chromate treatment, a chromate layer is further formed on the zinc-nickel alloy anti-rust treatment. This chromate treatment is carried out with a chromic acid concentration of 1 g/L, a pH=111, a solution temperature of 25° C., and a current density of 1 A/dm ² . In this way, an inorganic antirust layer is formed on both surfaces of the roughened copper foil.

Table 1 (* indicates a comparative example)

no

Claims (10)

A roughened copper foil having a roughened surface on at least one side, the roughened surface is composed of needle-like crystals and/or plate-like crystals including cuprous oxide and/or copper oxide, the roughening process The thickness of the cuprous oxide measured by the continuous electrochemical reduction method is 71 to 300 nm, and the thickness of the copper oxide measured by the continuous electrochemical reduction method is 0 to 20 nm. The roughened copper foil as described in item 1 of the patent application range, wherein the thickness of the cuprous oxide on the roughened surface is 100 to 300 nm. The roughened copper foil as described in item 1 or 2 of the patent application range, wherein the copper oxide thickness of the roughened surface is 1-20 nm. The roughened copper foil according to any one of items 1 to 3 of the patent application range, wherein the roughened copper foil has roughened surfaces on both sides. The roughened copper foil according to any one of items 1 to 4 of the patent application range, wherein the roughened surface has an organic anti-rust layer. The roughened copper foil as described in item 5 of the patent application range, wherein the organic anti-rust layer contains at least one of a triazole compound and a silane coupling agent. The roughened copper foil as described in item 5 of the patent application range, wherein the organic antirust layer contains a triazole compound. A copper-clad laminated board comprising the roughened copper foil as described in any one of claims 1 to 7 and an insulating resin substrate provided on the at least one side of the roughened copper foil. The copper-clad laminate as described in item 8 of the patent application range, wherein the insulating resin base material contains a thermoplastic resin. A printed wiring board provided with the roughened copper foil as described in any one of items 1 to 7 of the patent application.