JP2004169088A - Metal surface treatment agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface treatment agent for metal foil which has excellent adhesiveness with an insulated resin. <P>SOLUTION: The metal surface treatment agent comprises a resin for a high frequency substrate and a silane coupling agent as effective components. The resin for a high frequency substrate may include at least one kind of resin selected from polyphenylene ether, triallylisocyanurate, triallylcyanurate, a phenol resin, an epoxy resin having a reduced dielectric constant, a diallyl phthalate resin, a divinylbenzene resin, a polyfunctional acryloyl resin, a polyfunctional methacryloyl resin, a polyfunctional cyanic acid ester resin, a polyfunctional maleimide resin, a polyfunctional isocyanate resin, and a styrene-butadiene copolymer. The silane coupling agent may include at least one kind of functional group selected from a vinyl group, an amino group, an epoxy radical, a chlorine group, a methacryl group, an acryl group, a mercapto group, an azole ring and a pyridine ring. <P>COPYRIGHT: (C)2004,JPO

Description

【００２９】
接着性試験２
前記表面処理剤▲２▼、▲４▼、▲６▼で表面処理された銅箔及び表面処理を塗布していない銅箔を、シアン酸エステル樹脂とフェノール樹脂を主成分とした液に含浸したガラス繊維基材と加熱プレスし、銅張積層板を作製した。ＪＩＳ Ｃ ６４８１に規定する方法により、この銅張積層板の常態ピール強度を測定した。その結果を表２に示す。
【００３０】
【表２】

【００３１】
【発明の効果】
本発明の表面処理剤を用いて金属箔を表面処理することにより、絶縁樹脂と金属箔との密着性が向上する。特に高周波基板の絶縁樹脂との密着性に優れ、ロープロファイル銅箔の表面処理剤としても十分な特性が得られる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a metal foil surface treatment agent. In particular, the present invention relates to a copper foil surface treating agent having excellent adhesion between a copper foil and an insulating resin.
[0002]
[Prior art]
2. Description of the Related Art In recent years, as computers and information communication devices have become high-performance and high-function, and their networks have been developed, signals handled for transmitting and processing large-capacity information at high speed tend to have higher frequencies.
In general, an epoxy resin having an excellent adhesive property is widely used as an insulating material of a printed wiring board. However, an epoxy resin generally has a high relative dielectric constant and a high dielectric loss tangent, and does not have sufficient high-frequency characteristics. Therefore, a resin having excellent dielectric properties must be used. However, a resin having a low relative dielectric constant or a low dielectric loss tangent has a small number of functional groups having a high polarity contributing to adhesion, and the adhesive properties tend to deteriorate. Further, it is desired that the surface roughness of the copper foil of the high-frequency compatible substrate be as small as possible. As described above, it is desired that the copper foil has a low profile because, as the frequency becomes higher, current concentrates and flows on the surface of the copper foil (this phenomenon is called a skin effect), and the surface roughness of the copper foil is reduced. Is considered to greatly affect the transmission loss.
[0003]
As described above, in the high-frequency compatible substrate, the adhesive strength between the copper foil and the insulating resin is reduced due to the change of the resin and the low profile of the copper foil, and there is a strong demand for improving the adhesiveness.
[0004]
As a means for improving the adhesion between the copper foil and the insulating resin, a method of surface treatment of a silane coupling agent or addition to a resin is generally employed. Epoxy-based or amino-based commercially available silane coupling agents are effective and have been used for many years. However, in recent years, the requirements for high-frequency applications have not been satisfied in the current situation.
[0005]
Further, as a conventional technique similar to the present invention, there is a metal foil with resin (for example, see Patent Documents 1, 2, and 3). In these techniques, the thickness of the resin composition is 10 μm or more (usually 20 μm or more), and the resin functions as an adhesive. The use is in the production of multilayer boards using the built-up method. On the other hand, the surface treatment agent of the present invention is for improving the wettability and adhesion with a prepreg or an adhesive, and is not used as an adhesive in the surface treatment layer itself. Therefore, the present invention is a technology in a field completely different in application from those of the metal foil with resin.
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 9-1728 [Patent Document 2]
JP-A-10-178275 [Patent Document 3]
JP 2000-34406 A
[Problems to be solved by the invention]
An object of the present invention is to provide a metal foil surface treatment agent having excellent adhesion to an insulating resin. In particular, it is an object of the present invention to provide a surface treatment agent for a low-profile copper foil having excellent adhesion to an insulating resin of a high-frequency compatible substrate.
[0008]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to improve the adhesion between the copper foil and the insulating substrate. As a result, the resin for the high-frequency substrate and the metal surface treatment agent containing a silane coupling agent as an active ingredient are used as the insulating resin of the high-frequency-compatible substrate. It was confirmed that the adhesiveness was excellent, and that sufficient characteristics could be obtained even with a low-profile copper foil.
[0009]
That is, the present invention is as follows.
(1) A metal surface treatment agent comprising a high-frequency substrate resin and a silane coupling agent as active ingredients.
(2) A surface-treated metal foil obtained by treating one or both surfaces of a metal foil with the metal surface treating agent according to (1).
(3) The surface-treated metal foil according to (2), wherein the thickness of the surface-treating agent of the surface-treated metal foil is 10 µm or less.
[0010]
Examples of the resin for a high-frequency substrate which is one of the effective components of the metal surface treating agent of the present invention include polyphenylene ether, triallyl isocyanurate, triallyl cyanurate, phenolic resin, epoxy resin having a low dielectric constant, diallyl phthalate resin, and divinyl resin. Contains at least one resin among benzene resin, polyfunctional acryloyl resin, polyfunctional methacryloyl resin, polyfunctional cyanate ester resin, polyfunctional maleimide resin, polyfunctional isocyanate resin, and styrene-butadiene copolymer Just do it.
[0011]
Examples of polyphenylene ether include poly (2,6-dimethyl-1,4-phenylene ether) and poly (2,6-dimethyl-1,4-phenylene ether) obtained by homopolymerization of 2,6-dimethylphenol. A styrene graft polymer, a copolymer of 2,6-dimethylphenol and 2,3,6-trimethylphenol, a copolymer of 2,6-dimethylphenol and 2-methyl-6-phenylphenol, and the like.
[0012]
Examples of the polyfunctional cyanate ester resin include 2,2-bis (4-cyanatophenyl) propane, 1,1-bis (4-cyanatophenyl) ethane, and bis (4-cyanato-3,5-dimethyl) Bifunctional cyanates such as phenyl) methane, 1,3-bis (4-cyanatophenyl-1- (methylethylidene)) benzene, bis (4-cyanatophenyl) thioether and bis (4-cyanatophenyl) ether Resins: Polyfunctional cyanate resins derived from phenol novolak, cresol novolak and the like can be mentioned.
[0013]
In selecting the resin, it is preferable to use the same resin or a resin that reacts with the resin composition of the prepreg or the like to be bonded, and it is necessary to change the resin depending on each prepreg or the like.
[0014]
The silane coupling agent, which is one of the active ingredients of the metal surface treatment agent of the present invention, is at least one of a vinyl group, an amino group, an epoxy group, a chloro group, a methacryl group, an acryl group, a mercapto group, an azole ring, and a pyridine ring. What is necessary is just to contain one kind of functional group, and those which are commercially available, or those disclosed in JP-A-05-186479, JP-A-05-039295, JP-A-06-279458, JP-A-06-279461, JP-A-06-279462, JP-A-06-279456, JP-A-06-279364, JP-A-06-293779, JP-A-09-295990, JP-A-09-295988, JP-A-09-296135, JP-A-09-295899, JP-A-09-2959991, JP-A-09-2959991, 09-295992, JP-A-11-108246, etc. Preferred.
The selection of the silane coupling agent is preferably one that reacts with or has good compatibility with the resin for the high-frequency substrate to be mixed, and is preferably changed depending on each case.
[0015]
The composition ratio of the high-frequency substrate resin and the silane coupling agent is not particularly limited, but the weight ratio of the silane coupling agent / high-frequency substrate resin is preferably 0.1 or more. The role of each component is that the silane coupling agent improves adhesion by reacting with both the metal foil and the resin, and the high-frequency substrate resin adheres by improving the wettability with the insulating resin. It improves the performance. Therefore, the respective composition ratios are not particularly limited, but those having a large amount of the silane coupling agent are preferable. However, since the silane coupling agent is expensive, the weight ratio of the silane coupling agent / the resin for a high-frequency substrate is preferably 0.1 to 0.9, and more preferably 0.3 to 0.8.
[0016]
The surface treatment agent of the present invention is used by dissolving at least the resin for a high-frequency substrate and a silane coupling agent in a solvent. Examples of the solvent used include aromatic solvents such as benzene, ethylbenzene, toluene, and xylene. Examples include hydrocarbons, halogen-based solvents such as dichloromethane, chloroform, and trichloroethylene, and cyclic ether-based solvents such as tetrahydrofuran and dioxane. These can be used alone or as a mixture.
Further, the surface treating agent of the present invention may contain an additive in an amount that does not impair the original properties for the purpose of imparting desired performance. Examples of the additives include a flame retardant, an antioxidant, a heat stabilizer, and an antistatic agent.
[0017]
The surface treatment of the metal foil using the surface treatment agent of the present invention may be any method that forms a film on the surface of the metal foil. For example, a method in which the metal foil is simply immersed in the surface treatment agent, a surface treatment agent Is applied using a shower or an apparatus such as an aired coater, a blade coater, a rod coater, a knife coater, a gravure coater, a reverse coater, or a cast coater.
[0018]
As a method of drying the coating film, a method using a device such as hot air drying, roll heating drying, infrared drying, far infrared drying, etc., is used, and in practice, these devices are used alone or in combination of two or more. May be.
[0019]
The thickness of the surface treatment layer is not particularly limited, but is preferably 10 μm or less from the viewpoint of cost. Further, it is more preferably 5 μm or less.
[0020]
As the metal foil used in the present invention, any metal foil can be used, and examples thereof include copper foil, aluminum foil, tin foil, and gold foil. Since the metal foil is easily available and can be easily etched, a copper foil or an aluminum foil is preferable as the metal foil, and a copper foil is most preferable. The thickness of the metal foil used is not particularly limited, but is suitably 500 μm or less, preferably 200 μm or less, and more preferably 105 μm or less from the viewpoint of ease of handling.
[0021]
The copper foil used in the present invention may be either an electrolytic copper foil or a rolled copper foil. Depending on the application, a roughening treatment may be performed. The roughening treatment is a step of precipitating fine copper particles, and is preferably performed before forming the heat-resistant treatment layer. In particular, when high-density wiring is not performed, a roughening treatment can be performed to further enhance the adhesiveness to the resin.
On the other hand, for a high-frequency compatible substrate, it is preferable that the surface roughness of the copper foil be as small as possible as described above. A copper foil having a surface roughness (Rz) of 4.0 μm or less, preferably 3.5 μm or less, and more preferably 3.0 μm or less is preferred.
[0022]
The copper foil used in the present invention may be subjected to heat treatment, rust prevention treatment, silane coupling agent treatment, or the like on both surfaces or one surface. The heat treatment is preferably at least one of zinc, zinc-tin, zinc-nickel, zinc-cobalt, copper-zinc, copper-nickel-cobalt, and nickel-cobalt. Those contained are more preferred, and copper-zinc is particularly preferred. It should be noted that some other elements, for example, Mn, Al, Fe, Ni, Co, Sn and the like may be added to this heat-resistant layer.
This thin film formation can be performed using a known method of electroplating, but is not limited to electroplating, and there is no problem using vapor deposition or other means. When the heat treatment is galvanization, the methods disclosed in JP-B-61-33907 and JP-A-6-81157 can be used. In the case of zinc-nickel and zinc-cobalt, the methods disclosed in Japanese Patent Publication No. 7-32307 and Japanese Patent Application Laid-Open No. 6-81157 can be used. In the case of treatment with zinc-tin, the method disclosed in JP-B-58-56758 can be used. The copper-zinc (brass, brass) plating is to deposit 50 to 85% by weight of copper, 15 to 50% by weight of a zinc composition, for example, 70% by weight of copper to 30% by weight of zinc and brass using a cyan bath. The thickness of the heat-resistant layer, 100~10000μg / dm ² as the coating weight of zinc, more preferably 1000~5500μg / dm ^2.
[0023]
The rust prevention treatment is preferably zinc-chromate or chromate treatment. As a method for forming a rust-preventive layer, any known method can be applied to the present invention, but immersion or electrolytic chromate treatment of chromium oxide or electrolytic chromium-zinc treatment of chromium oxide and zinc or zinc oxide It is preferable to form a rust preventive layer composed of a mixture. In the case of performing zinc-chromate and chromate treatment, the method described in Japanese Patent Publication No. 7-32307 can be used. The amount of adhesion of these rust preventive layers is preferably 15 μg / dm ² or more in terms of the amount of chromium, and 30 μg / dm ² or more in the case where zinc is contained.
[0024]
The silane coupling agent used in the silane coupling agent treatment includes at least one of a vinyl group, an amino group, an epoxy group, a chloro group, a methacryl group, an acryl group, a mercapto group, an azole ring, and a pyridine ring. Is preferred.
[0025]
【Example】
Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples.
Examples 1 and 2 and Comparative Examples 1 to 6
Surface treatment of copper foil After roughening the roughened surface of electrolytic copper foil (thickness: 18 μm) to form a brass layer, copper plated with zinc or a zinc-chromium-based mixture of zinc oxide and chromium oxide The following surface treatment agents (1) to (4) were applied to a foil (Rz: 2.5 μm) with a doctor blade. After the application, it was dried with a hot air drier. The film thickness of the surface treatment agent was about 3 μm.
As for the surface treatment agents (5) and (6), a small amount of the surface treatment agent was dropped on a copper foil, and a SUS roll was rolled to apply the surface treatment agent. After the application, it was dried with a hot air drier.
[0026]
{Circle around (1)} A toluene solution of 2% vinyltriethoxysilane, 2% triallyl isocyanurate, 1% poly (2,6-dimethyl-1,4-phenylene ether), 0.04% ditertiary butyl peroxide (Example) solution)
(2) 2% 3-glycidoxypropyltrimethoxysilane, 1% 2,2-bis (4-cyanatophenyl) propane prepolymer, 2% phenol novolak resin, 0.001% zinc naphthenate DMF ( Dimethylformamide) solution (example solution)
(3) 3.3% triallyl isocyanurate, 1.7% poly (2,6-dimethyl-1,4-phenylene ether), 0.04% ditertiary butyl peroxide in toluene solution (comparative solution)
(4) 1.7% 2,2-bis (4-cyanatophenyl) propane prepolymer, 3.3% phenol novolak resin, 0.001% zinc naphthenate in DMF (dimethylformamide) solution (comparative solution) )
(5) Pure aqueous solution of 2% vinyltriethoxysilane (pH adjusted to 5 with acetic acid) (comparative solution)
(6) 2% pure aqueous solution of 3-glycidoxypropyltrimethoxysilane (pH adjusted to 5 with acetic acid) (comparative solution)
[0027]
Adhesion test 1
Impregnating the copper foil surface-treated with the surface treatment agents (1), (3), and (5) and the copper foil not coated with the surface treatment agent with a liquid containing polyphenylene ether and triallyl isocyanurate as main components. The resulting glass fiber base was hot-pressed to produce a copper-clad laminate. The normal peel strength of the copper-clad laminate was measured by the method specified in JIS C6481. Table 1 shows the results.
[0028]
[Table 1]

[0029]
Adhesion test 2
The copper foil surface-treated with the surface treatment agents (2), (4), and (6) and the copper foil not coated with the surface treatment were impregnated with a liquid containing a cyanate ester resin and a phenol resin as main components. A glass-clad laminate was prepared by hot pressing with a glass fiber substrate. The normal peel strength of the copper-clad laminate was measured by the method specified in JIS C6481. Table 2 shows the results.
[0030]
[Table 2]

[0031]
【The invention's effect】
The surface treatment of the metal foil using the surface treatment agent of the present invention improves the adhesion between the insulating resin and the metal foil. In particular, the adhesiveness to the insulating resin of the high-frequency substrate is excellent, and sufficient characteristics can be obtained as a surface treatment agent for a low-profile copper foil.

Claims (3)

A metal surface treatment agent comprising a high-frequency substrate resin and a silane coupling agent as active ingredients. A surface-treated metal foil obtained by treating one or both surfaces of a metal foil with the metal surface treatment agent according to claim 1. The surface-treated metal foil according to claim 2, wherein the surface-treated metal foil has a thickness of 10 µm or less.