JP2003229648A - Copper foil for printed wiring board and its producing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copper foil for printed wiring board, and its producing method, exhibiting excellent stripping strength without increasing the surface roughness in order to deal with fine patterning of circuit wiring and high function of a basic material. <P>SOLUTION: The copper foil for printed wiring board comprises a rust prevention processing layer, a coupling agent processing layer, and an adhesive property imparting layer of epoxy resin polymer having weight average molecular weight of 70,000 or above wherein the adhesive property imparting layer has a thickness of 0.5-5 g/m<SP>2</SP>expressed in terms of weight. When an epoxy silane based coupling agent is employed, a copper foil for printed wiring board exhibiting excellent stripping strength is obtained. In the process for producing a copper foil for printed wiring board by forming an adhesive property imparting layer on a copper foil, the copper foil is coated with a solution containing epoxy resin polymer by 1-10%. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper foil for printed wiring boards and a method for manufacturing the same.

[0002]

2. Description of the Related Art In printed wiring boards used in electronic equipment, unnecessary parts of copper foil are removed by etching a copper clad laminate to form circuit wiring. The copper clad laminate is manufactured by laminating and molding a base material obtained by impregnating a glass fiber cloth with an epoxy resin and a copper foil. Further, it is also practiced to use a resin-coated copper foil in which an epoxy resin film containing an inorganic filler is formed on a copper foil. The thickness of the epoxy resin film used for the resin-coated copper foil is usually about 100 μm in order to ensure insulation between circuit wiring layers. The printed wiring board is exposed to harsh processing conditions in the manufacturing process and is used for a long period of time. Therefore, high reliability is required and high peeling strength between the copper foil and the base material is particularly required. Therefore, for the purpose of physically improving the peeling strength between the copper foil and the base material, a roughening treatment with an acidic copper plating bath or the like is performed on the copper foil.
Further, JP-A-57-87324 discloses that a coupling agent is treated with a silane coupling agent for the purpose of chemically improving the peeling strength. Further, JP-A-8-193188 describes a copper foil with an adhesive in which an adhesive layer made of a rubber-modified epoxy resin composition is formed on a copper foil which is not subjected to a roughening treatment. The thickness of this adhesive layer is not particularly specified, but is about 30 μm as seen from the examples.

[0003]

The printed wiring board has made rapid technological progress with the sophistication of electronic technology, and the performance required for the copper foil constituting the printed wiring board has become more severe. ing. In particular, a copper foil having a small surface roughness is desired in order to cope with high density of circuit wiring and high speed of data transfer accompanying the progress of miniaturization and high performance of electronic devices. By using a copper foil with a small surface roughness, etching processability is improved, fine circuit wiring can be easily formed, high-density circuit wiring can be realized, and it causes signal waveform distortion. Although the speed of data transfer can be increased by reducing the irregularities on the surface of the circuit wiring, the physical interaction with the base material is reduced and the peeling strength of the circuit wiring is reduced. In addition, the inorganic filler in the base material tends to increase in response to high functionality such as high heat resistance, high elastic modulus and low thermal expansion coefficient of the base material. Therefore, as a result of the decrease in the resin content in the base material, stress relaxation due to plastic deformation and the like are reduced, and the peeling strength tends to decrease. If the resin is modified to increase the peel strength, the characteristics of the base material may be impaired.

The present invention provides a copper foil for a printed wiring board which is excellent in peeling strength without increasing the surface roughness and a method for producing the same, in order to cope with the miniaturization of circuit wiring and the higher functionality of the base material. To do.

[0005]

DISCLOSURE OF THE INVENTION As a result of intensive investigations by the present inventors, by providing an adhesion imparting layer made of an epoxy resin polymer having a weight average molecular weight of 70,000 or more,
The inventors have found that practically sufficient peeling strength can be obtained even by using a smooth copper foil having a small surface roughness, and have completed the present invention. That is, the present invention has a weight average molecular weight of 7
A copper foil for a printed wiring board, which has an adhesion imparting layer made of an epoxy resin polymer of 20,000 or more. Further, the present invention is a printed wiring board having a rust preventive treatment layer, a coupling agent treatment layer, and an adhesion imparting layer made of an epoxy resin polymer having a weight average molecular weight of 70,000 or more. The thickness of the adhesion-imparting layer, which is a copper foil and made of an epoxy resin polymer having a weight average molecular weight of 70,000 or more, is 0.5 to 5 g / m 2 in terms of weight.
It is copper foil for printed wiring boards characterized by being ² . By using an epoxysilane coupling agent as the coupling agent, a copper foil for a printed wiring board having excellent peeling strength can be obtained.

Further, the present invention has a weight average molecular weight of 70,
000 or more epoxy resin polymer adhesiveness imparting layer is formed to produce a copper foil for printed wiring board, in the step of coating the copper foil with a solution containing 1 to 10% of the epoxy resin polymer. It is a characteristic method for producing a copper foil for a printed wiring board.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The type of copper foil used in the copper foil for a printed wiring board of the present invention may be either electrolytic copper foil or rolled copper foil, and the thickness is preferably 3 to 70 μm, and particularly preferably Is more preferably 3 to 18 μm. 7 copper foil
If it is thicker than 0 μm, the etching process becomes difficult, and 3 μm
If it is thinner than m, handling becomes difficult. The electrolytic copper foil has two types of surfaces, that is, a glossy surface and a non-glossy surface, each having a different surface shape and surface roughness. In the present invention, the adhesion imparting layer may be provided on either surface. The surface roughness is preferably from 10 to 10 average roughness of 0.5 to 10 μm, particularly preferably 0.5 to 3 μm. Surface roughness is 0.5
If it is smaller than μm, it becomes difficult to manufacture the copper foil itself. On the other hand, when the thickness is larger than 3 μm, the portion buried in the base resin increases and etching processing becomes difficult. Further, when the surface roughness is large, the waveform of the high-frequency signal is likely to be disturbed, and therefore when used in a high-frequency circuit, it is preferable that the surface roughness be small within the above range. If the surface roughness is within the above range, a copper foil that has not been roughened can also be used. A steel-clad laminate using a copper foil that has not been roughened is particularly excellent in etching processability because there are no roughening particles embedded in the base resin.

Further, in the present invention, it is necessary to provide an anticorrosion treatment layer and a coupling agent treatment layer on the adhered surface of the copper foil. As the rust-preventive treatment layer, in addition to the chromate treatment layer, there is a zinc-containing chromate treatment layer containing zinc, a composite treatment layer consisting of zinc and aluminum, etc., and these rust-preventive treatment layers block oxygen and moisture, The deterioration of copper or the above-mentioned metal-treated layer and alloy-treated layer with time is prevented. The anticorrosion layer is
It can be formed by immersion or electrolytic treatment in a treatment bath containing the corresponding metal ion or its complex ion. The silane coupling agent-treated layer can be formed by various methods such as coating and spraying an aqueous solution, aqueous dispersion, solution or the like of various coupling agents on the anticorrosion-treated layer. As the coupling agent, various silane coupling agents can be used alone or in combination, and vinyltrimethoxysilane, vinyltriethoxysilane,
Vinyltris (β-methoxyethoxy) silane, β-
(3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ
-Methacryloxypropylmethyldimethoxysilane, γ
-Methacryloxypropyltrimethoxysilane, N-β
-(Aminoethyl) -γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-
Phenyl-γ-aminopropyltriethoxysilane, γ
-Chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane and the like can be used. Further, one or more of the above-mentioned silane coupling agents are mixed and used. Particularly preferably, epoxy silane is more preferable. If necessary, the above silane coupling agent and tetramethoxysilane, tetraethoxysilane,
It may be used by mixing with tetraalkoxysilane such as tetrapropoxysilane or tetrabutoxysilane or with polysilicate such as water glass, lithium silicate or potassium silicate. By forming the coupling treatment agent layer, the peeling strength of the circuit wiring and the moisture resistance are improved. Further, a metal treatment layer or an alloy treatment layer may be formed under the rustproof treatment layer depending on the required characteristics of the printed wiring board. Examples of the metal used as the metal treatment layer or the alloy treatment layer include zinc, nickel, cobalt, molybdenum, indium, iron, etc., which are used alone or as an alloy as necessary. Some of these metals may be present as oxides or hydroxides.

Epoxy resin polymers used for forming the adhesion imparting layer are disclosed in JP-A-4-120124, JP-A-4-120125, JP-A-5-93041, and JP-A-5-93042. The bifunctional epoxy resin such as bisphenol A diglycidyl ether described in 1., the bifunctional phenol such as bisphenol A and the epoxy obtained by the reaction with the compound having a triazine ring or isocyanuric ring such as melamine and isocyanuric acid can be used. . This epoxy resin polymer is
From the standpoint of excellent film-forming property and mechanical strength, it is preferable that the polymer has a high molecular weight within a range that the solubility allows, and a weight average molecular weight of 70,000 or more, more preferably 100,
It is more than 000. The above epoxy resin polymer is dissolved in a solvent and used as a varnish having a concentration of 1 to 10%. As the solvent, amide compounds such as formamide, dimethylformamide, dimethylacetamide and N-methylpyrrolidone, halogenated hydrocarbons such as chloroform and methylene chloride, epoxy compounds such as allyl glycidyl ether, styrene oxide and phenyl glycidyl ether, Amide compounds and benzene, hexane, toluene,
Hydrocarbons such as xylene, methanol, ethanol, 1
Alcohols such as 1-propanol, 21-propanol,
A mixed solvent of ketones such as acetone, 2-butanone, 2-pentanone and 3-pentanone or esters such as methyl formate, methyl acetate and ethyl acetate is used.

The above-mentioned epoxy resin polymer is heat-softenable, and is coated on a copper foil by various methods as an epoxy resin polymer varnish containing a curing agent imparting thermosetting property, and dried to obtain a varnish. An adhesion imparting layer is formed. As the curing agent, various blocked isocyanates and the like that can react with the hydroxyl groups of the epoxy polymer to form three-dimensional crosslinking can be used. Further, a low molecular weight epoxy resin and a curing agent such as dicyandiamide may be added and integrated with the cured epoxy resin. Furthermore, various thermosetting resin curing systems can be applied. Further, the epoxy resin polymer varnish of the present invention can be added with various additives such as a flame retardant, a leveling agent and an antioxidant, and the coating amount of the resin composition layer after drying is the weight-converted thickness. It is 0.5 to 5 g / m ² . If it is less than 0.5 g / m ² , the peeling strength is low, and if it is thicker than 5 g / m ² , the moisture resistance decreases. The adhesion-imparting layer does not need to completely cover the adhered surface of the copper foil, and the apex of the convex portion may not be covered on the rough surface side.

As a method for providing the adhesion-imparting layer on the surface of the copper foil to be adhered, the above-mentioned epoxy resin polymer varnish is applied by a known coating method, for example, a transfer method (roller, wheel, dowbar), or a pressure-sensitive method ( Ball point), injection method, self-weight dropping method and the like can be used. Among these, the injection method or the self-weight dropping method is practically preferable in terms of mass productivity and economical efficiency. After applying the epoxy resin polymer varnish, the adhesiveness imparting layer is semi-cured by heating and drying. In the completely cured state, the integration of the adhesion-imparting layer and the base resin is not sufficient at the time of laminate molding with a laminated base material such as a glass cloth epoxy resin base material, resulting in a decrease in reliability. On the other hand, in the insufficiently cured state, the adhesiveness-imparting layer contaminates the other surface of the copper foil when the coated product is stored in a roll form. Drying temperature is 45-300
℃, preferably 70-200 ℃, drying time is 10 seconds to 6
It is 0 minutes, preferably 1 to 30 minutes.

[0012]

EXAMPLES The present invention will now be described in detail based on examples, but the present invention is not limited thereto.

Example 1 The weight average molecular weight is 127,0.
Solution containing 00 bisphenol A epoxy resin polymer (solid content 30%, solvent: dimethylacetamide)
100 parts by weight, cresol novolac type epoxy resin (epoxy equivalent: 198) 15 parts by weight, phenol novolac (hydroxyl group equivalent: 106) 7 parts by weight, 2-ethyl-
1 part by weight of 4-methylimidazole and 1878 parts by weight of dimethylacedamide were added and stirred to prepare an epoxy resin polymer varnish. This epoxy resin polymer varnish was treated with a roughening treatment layer, an alloy treatment layer made of nickel, molybdenum and cobalt, a chromate treatment layer, and a silane coupling agent treatment layer to form a non-electrolytic copper foil having a thickness of 12 μm. Glossy surface side (10-point average roughness: Rz = 5.5 μm)
Was sprayed for 5 seconds and immediately dried at 70 ° C. for 30 minutes to obtain a copper foil for a printed wiring board. The thickness of the adhesion imparting layer was 4.7 g / m ² in terms of weight. Copper foil for printed wiring board, glass cloth base material epoxy resin prepreg of 0.2 mm thickness (Hitachi Chemical Co., Ltd., trade name GEA-67N and GEA-679N) 8
The sheet is laminated so that the resin surface (that is, the surface to be adhered) faces the prepreg, and heat and pressure treatment is performed under conditions of temperature 168 ° C., pressure 0.3 MPa, and time 90 minutes to produce a copper clad laminate. did. The characteristics of this copper clad laminate are shown in the table. The test method is as described below. However, the peel strength and the chemical resistance deterioration rate are the values in the copper clad laminate using the FR-5 grade prepreg (GEA-679N), and the moisture resistance deterioration rate is the FR-4 grade prepreg (GEA- 67N) for a copper clad laminate. (Example 2) Evaluation was performed in the same manner as in Example 1 except that the surface roughness was 10-point average roughness = 2.3 and no roughening treatment layer was formed. The results are shown together in the table.

(Embodiment 3) Surface roughness is 10 points Average roughness =
Evaluation was carried out in the same manner as in Example 1 except that the roughening treatment layer was not formed at 1.5. The results are shown together in the table.

Comparative Example 1 Evaluation was carried out in the same manner as in Example 1 except that the coupling agent treatment layer was not formed. The results are shown together in the table.

Comparative Example 2 Evaluation was performed in the same manner as in Example 1 except that the adhesion-imparting layer had a weight-converted thickness of 0.3 g / m ² . The results are shown together in the table.

(Comparative Example 3) Evaluation was carried out in the same manner as in Example 1 except that the thickness of the adhesion-imparting layer was 10 g / m ² in terms of weight. The results are shown together in the table.

Comparative Example 4 Evaluation was carried out in the same manner as in Example 1 except that the adhesion imparting layer was not formed.
The results are shown together in the table.

(Comparative Example 5) Evaluation was carried out in the same manner as in Example 2 except that the adhesion imparting layer was not formed.
The results are shown together in the table.

Comparative Example 6 Evaluation was carried out in the same manner as in Example 3 except that the adhesion imparting layer was not formed.
The results are shown together in the table.

[0021]

[Table 1]

[0022]

By using the copper foil for a printed wiring board of the present invention, it is possible to manufacture a highly reliable printed wiring board which maintains a high peeling strength between the copper foil and the resin base material.

Continued front page    (72) Inventor Toshiju Kumakura             Hitachi, 1500, Ogawa, Shimodai, Shimodate, Ibaraki Prefecture             Seiko Building Shimodate Office (72) Inventor Kazuhito Kobayashi             Hitachi, 1500, Ogawa, Shimodai, Shimodate, Ibaraki Prefecture             Seisei Co., Ltd. Research Institute F term (reference) 4E351 AA03 BB01 BB30 BB38 CC18                       CC19 CC22 DD04 DD17 DD19                       DD21 DD54 GG02                 4F100 AB15 AB16 AB17A AB20                       AB33A AK52C AK53C AK53D                       AR00B AR00C BA04 BA07                       CB01D EJ17 EJ42 EJ67C                       EJ69 GB43 JA07D JB02B                       YY00D                 5E346 AA15 CC04 CC09 CC32 CC41                       DD02 DD12 GG13 GG28 HH11

Claims (5)

[Claims] 1. A copper foil for a printed wiring board, having an adhesion imparting layer made of an epoxy resin polymer having a weight average molecular weight of 70,000 or more. 2. The print according to claim 1, further comprising an anticorrosion treatment layer, a coupling agent treatment layer, and an adhesion imparting layer made of an epoxy resin polymer having a weight average molecular weight of 70,000 or more. Copper foil for wiring boards. 3. The copper foil for a printed wiring board according to claim 1, wherein the thickness of the adhesion imparting layer is 0.5 to 5 g / m ² in terms of weight. 4. The copper foil for a printed wiring board according to claim 1, wherein the coupling agent is epoxysilane. 5. In the step of producing a copper foil for a printed wiring board by forming an adhesion imparting layer made of an epoxy resin polymer having a weight average molecular weight of 70,000 or more on the copper foil, the epoxy resin polymer is added to The method for producing a copper foil for a printed wiring board according to claim 1, wherein a solution containing 10% is applied to the copper foil.