JP3559598B2 - Metal foil for printed wiring board, method for manufacturing the same, and method for manufacturing wiring board using the metal foil - Google Patents

Description

【００４６】
以上のようにして得られた実施例８〜１２の印刷配線板は、いずれも配線密度が回路幅０．０３ｍｍまで形成でき、しかも引き剥がし度はいずれも１．３〜１．４ｋｇｆ／ｃｍ^２の範囲であった。比較例２、３の場合には、ピール強度が約１．２ｋｇｆ／ｃｍ^２であったが、めっき液の安定性や配線形成性や耐熱性に劣り、比較例５に至っては０．４ｋｇｆ／ｃｍ^２と小さかった。
【００４７】
【発明の効果】
以上に説明たように、本発明によってピンホールの抑制に優れ、かつ配線密度に優れた印刷配線板用金属箔と、その製造法並びにこの金属箔を用いて効率良く印刷配線板を製造する方法を提供することができる。[0001]
[Industrial applications]
The present invention relates to a metal foil for a printed wiring board, a method for manufacturing the same, and a method for manufacturing a wiring board using the metal foil.
[0002]
[Prior art]
With the development of electronic devices, high performance printed wiring boards have been required.
For example, with respect to the wiring density, a so-called surface mount component has been developed in which connection is made only to the electronic component on the surface of the wiring board, and when the spacing between the connection terminals of the electronic component is reduced, a component having a wiring density of 0.15 mm or less is also used. Therefore, it is required to form a circuit conductor according to the density.
As for heat resistance, it is necessary to withstand 260 ° C required for soldering, but also to withstand harsh environments such as those used in the control of automobiles. It has become.
[0003]
As a method of manufacturing such a printed wiring board, a copper-clad laminate obtained by bonding copper foil to an insulating base material is used as a starting material, and a portion of the copper foil that is not a circuit conductor is removed by etching to form a circuit. The active method, the additive method of forming the circuit by performing electroless plating on the required circuit shape on the surface of the insulating base material, and the partial additive method of forming a part of the circuit conductor such as the inner wall of the through hole by electroless plating are common. Is known to.
[0004]
Above all, the subtractive method has been used for a long time. In order to improve the wiring density, the thickness of the copper foil of the copper-clad laminate is usually reduced. The reason for this is that when an etching resist is formed in the required circuit shape on the surface of the copper foil and unnecessary copper foil exposed from the etching resist is removed with an etching solution, copper is corroded from the side surfaces of the required circuit portion. A phenomenon called so-called side etch occurs, and the thicker the copper foil, the larger the amount of copper on the side that is removed by the side etch, so a thin copper foil is required to form a fine circuit. .
[0005]
In addition, in the case of printed wiring boards that provide through holes and connect the circuits of different layers by metalizing the inner wall, drill holes in the copper-clad laminate, perform electroless plating on the inner wall of the hole and the entire copper foil surface, Further, since electroplating is usually performed to secure the thickness of the metal layer on the inner wall of the hole, a plating layer is also formed on the copper foil, and the thickness of copper is inevitably increased.
[0006]
Therefore, the copper foil of the copper-clad laminate, which is the starting material, needs to be thin, and such a copper foil is obtained by electrolytic plating on the surface of a metal such as a rolled copper foil obtained by extending copper by heat and pressure or stainless steel. An electrolytic copper foil on which copper is deposited is used, and in recent years, a copper foil having a thickness of 18 to 70 μm has been manufactured.
In recent years, an ultra-thin copper foil with an aluminum carrier in which a thin copper foil of about 5 μm is formed on an aluminum foil by electrolytic plating is also known.
[0007]
Such a thin copper foil is difficult to handle when laminating a copper foil and an uncured or semi-cured prepreg, and the copper foil is broken by a slight force.
Such inconveniences may also occur depending on the handling when manufacturing the copper foil.
Therefore, a method has been developed in which a thin copper foil as a whole is made into a board or foil having sufficient strength to form a composite layer, and the support layer is removed after bonding with a resin or immediately before use.
For example, as described in JP-A-58-108785, an intermediate metal such as nickel, nickel-iron, tin, lead, etc., having etching conditions different from copper between two copper foil layers is used. A metal foil having a three-layer structure provided with layers has been proposed.
[0008]
[Problems to be solved by the invention]
Meanwhile, among the conventional techniques, those using a metal foil having a three-layer structure as described in Japanese Patent Application Laid-Open No. 58-108785 have disclosed that electrolytic etching is used to remove the intermediate layer by etching. There is a statement that it can be performed.
This electrolytic etching requires special equipment and is inefficient.
At present, commercially available chemical solutions for etching and removing nickel-iron, tin, lead and the like include ethylenediamine-based Enstrip NP (trade name, manufactured by Meltex Corporation) and Meltec SCB (trade name, manufactured by McDermid Corporation). A solution, a mixed solution of nitric acid and hydrogen peroxide, or a mixed solution of chromic acid and sulfuric acid can be used. However, when Enstrip NP (trade name, manufactured by Meltex Co., Ltd.) is used, the intermediate layer is not A surface alteration layer called smut, which is a melting residue, is generated, and it is very difficult to remove this smut.If other solutions are used, not only the intermediate layer but also the copper layer that becomes the circuit may be removed. On the contrary, if the copper layer is to be left, the intermediate layer may not be completely removed.
In addition, when smut occurs, the copper foil becomes discontinuous, and the adhesiveness between the resin and the copper foil decreases. Even when the intermediate layer remains, the adhesiveness between the resin and the copper foil similarly decreases.
[0009]
Therefore, the inventors of the present invention have conducted intensive studies and as a result, in order to solve these problems, nickel-phosphorus is used as the intermediate layer, and the average surface roughness of the copper layer serving as a circuit in contact with the resin is 1 to 2 μm. We propose a technique for roughening.
However, when the surface is roughened with such a roughness, the area covered with the nickel-phosphorus alloy layer becomes large, and since there is more unevenness, pinholes are easily generated in the nickel-phosphorus alloy layer, and the second material serving as a support is formed. It has been found that when the copper layer is removed by etching, the pinhole damages the first copper layer to be a circuit.
[0010]
The present invention is directed to a metal foil for a printed wiring board which is excellent in wiring density and excellent in suppressing pinholes in the manufacturing process, a method for manufacturing the same, and a simple method for manufacturing a printed wiring board using the metal foil. The purpose is to provide.
[0011]
[Means for Solving the Problems]
The metal foil for a printed wiring board of the present invention comprises a first copper layer serving as a circuit, a second copper layer having sufficient strength as a metal foil as a whole, and an intermediate layer sandwiched therebetween. In the metal foil for wiring boards, the average roughness of the surface of the first copper layer in contact with the resin is 0.1 to 0.8 μm, and the average roughness of the surface of the second copper layer in contact with the intermediate layer is 0. 0.5 to 0.4 μm, wherein the intermediate layer is nickel or an alloy thereof and has a thickness of 0.04 to 1.5 μm.
If the average roughness of the surface of the first copper layer in contact with the resin is less than 0.1 μm, the peel strength is small and the formed wiring may float, and if it exceeds 0.8 μm, it becomes difficult to form fine wiring. .
If the average roughness of the surface of the second copper layer in contact with the intermediate layer is less than 0.05 μm, the adhesion to the resist at the time of forming the wiring decreases, and if it exceeds 0.4 μm, pinholes are generated. Easier to do.
[0012]
In such a metal foil for a printed wiring board, the thickness of the second copper layer is preferably in the range of 10 to 150 μm. If it is less than 10 μm, sufficient strength cannot be obtained as a whole metal foil for a printed wiring board, and if it exceeds 150 μm, it takes time to remove by etching, which is not efficient. However, if the effect produced by the thickening is more important than efficiency, it can be made thicker, but usually does not require more. More preferably, it is in the range of 18 to 70 μm.
[0013]
Further, the thickness of the first copper layer is preferably in the range of 1 to 15 μm. If it is less than 1 μm, pinholes are likely to be formed in the formed copper foil, and if it exceeds 15 μm, the side etching becomes large as described in the related art, and it becomes difficult to increase the wiring density. More preferably, it is 3 to 6 μm.
[0014]
It is preferable to provide a rust-preventive coating on the surface of the metal foil for a printed wiring board that is not in contact with the intermediate layer between the first copper layer and the second copper layer. For example, a method of forming a coating made of an imidazole organic material A conventionally known method such as a chromate treatment, a zincate treatment, or the like can be used.
[0015]
Such a metal foil for a printed wiring board has at least one of the second copper layers having sufficient strength as the metal foil for a printed wiring board as a whole so that the average roughness is 0.05 to 0.4 μm. After adjustment, a layer of nickel or an alloy thereof having a thickness of 0.04 to 1.5 μm is formed on the surface thereof, and further, a copper layer serving as a circuit is formed on the surface thereof, and then the resin of the first copper layer is brought into contact therewith. It can be manufactured by forming a roughened surface on the surface such that the average roughness is 0.1 to 0.8 μm.
[0016]
The step of forming a roughened surface on the surface of the first copper layer can be performed by a method selected from among electroplating, electroless plating, displacement plating, etching, and vapor deposition.
When using electroplating, roughening can be performed by changing the current density or plating solution composition and making the plating deposition rate faster than normal bright plating, and in order to control the average roughness, , By controlling the conditions to be maintained within a certain range.
Similar roughening can be performed by using a cathode plate having an average roughness of 0.05 to 0.4 μm.
When electroless plating or displacement plating is used, roughening can be performed by changing the composition and making the plating deposition rate faster than normal bright plating.
Further, a conventionally known method can also be used, for example, a method of contacting with a soft etching solution such as ammonium persulfate, a method of spraying sand blast, or a method of mechanically polishing with a sander belt.
[0017]
As a method of manufacturing a printed wiring board using such a metal foil for a printed wiring board, it is possible to include the following steps in this order.
a. In a first copper layer to be a circuit, a second copper layer having sufficient strength as a metal foil as a whole, and a metal foil composed of an intermediate layer sandwiched between the first copper layer and the resin of the first copper layer, The average roughness of the surface in contact with the intermediate layer of the second copper layer is 0.1 to 0.8 μm, the average roughness of the surface in contact with the intermediate layer of the second copper layer is 0.05 to 0.4 μm, and the intermediate layer is nickel or an alloy thereof. Wherein the surface of the first copper layer of the metal foil for a printed wiring board having a thickness of 0.04 to 1.5 μm is impregnated with an uncured or semi-cured thermosetting resin.
Of stacking prepregs and stacking them by applying heat and pressure
b. Step of etching and removing only the second copper layer
c. Step of removing only the intermediate layer by etching
d. Step of forming circuit conductors
[0018]
The metal foil for a printed wiring board used in the present invention is as described above. However, when the metal foil for a printed wiring board is laminated and integrated with a prepreg, the first copper layer of the metal foil is overlapped on one surface of the prepreg, and The same metal foil can be overlapped on the surface of, but a copper foil used for a normal wiring board can also be overlapped.
[0019]
As an uncured or semi-cured prepreg, a reinforcing material such as glass cloth, glass fiber, paper, etc. was impregnated with a polyimide resin, an epoxy resin, a phenol resin, or a mixture thereof, and a curing agent for each resin. Or a semi-cured one (B-stage) by heating.
Further, it can also be produced by applying a mixture of a resin and a curing agent thereof without using a reinforcing base material, and heating and curing the mixture. For example, as the resin, a polyimide resin modified with an epoxy resin, a polyamide resin, or a heat-resistant thermosetting resin such as a polyamide-polyimide resin, and a curing agent thereof, for example, diaminodiphenyl sulfone, dicyandiamide, or phenol novolak may also be used. it can.
As this resin, a thermoplastic resin such as a fluororesin may be used.
In this case, it can be performed by using similar steps in the order of melting the resin, fusing with the metal foil, and cooling without using a curing agent. In this case, it is also possible to use a thermoplastic resin which has been previously processed into a sheet shape.
[0020]
As an etching solution for removing only the second copper layer of the metal foil for a printed wiring board, an alkaline chemical solution containing chlorine ions, ammonium ions, and copper ions, for example, an A process solution (trade name, manufactured by Meltex Corporation) (Hereinafter, referred to as an alkali etchant), and etching can be performed by contact with the alkali etchant. Here, the term “contact” refers to immersion in the solution or spraying the solution.
[0021]
As an etching solution for removing only the intermediate layer, a solution containing nitric acid, hydrogen peroxide, an organic acid containing a carboxyl group, and benzotriazole can be used. For example, as such a solution, 200 g / l of nitric acid, 100 g / l of propionic acid, H₂O₂10 ml / l, benzotriazole 5 g / l and the like.
[0022]
The step of forming the circuit conductor includes, after removing the second copper layer and the intermediate layer, forming an etching resist on the surface of the first copper layer forming the circuit, and etching the copper foil exposed from the etching resist. By removal, a desired circuit can be formed.
Also, when connecting circuits on both sides, make a hole to be a through hole before this process, electroless-plate the inner wall of the hole, perform electroplating if necessary, and secure the thickness of the conductor. A circuit can also be formed by forming an etching resist and removing unnecessary copper foil by etching.
Furthermore, on at least one surface of the inner layer substrate on which the inner layer circuit was formed, the prepreg and the metal foil were stacked and integrated, and the removal of the second copper layer and the removal of the intermediate layer of the metal foil were performed. After that, a hole to be a through hole is drilled, the inner wall of the hole is electroless plated, if necessary, electrolytic plating is performed, the thickness of the conductor is secured, an etching resist is formed, and unnecessary copper foil is removed by etching To form a circuit conductor.
[0023]
[Action]
The present inventors have conducted intensive studies and as a result,
(1) By setting the surface roughness of the second copper layer to Ra; 0.05 to 0.4 μm, pinholes in the intermediate layer can be suppressed and the first copper layer is not eroded during etching;
(2) Even if the surface roughness of the first copper layer is Ra; 0.1 to 0.8 μm, sufficient adhesive strength with the resin base material is obtained, and the wiring formability is also good. ,
And obtained the present invention.
[0024]
【Example】
Example 1
As the second copper layer, electrolytic copper plating is performed on the surface of the stainless steel plate using a copper sulfate plating solution, and the plating thickness is about 30 μm, and the average roughness Ra of the surface of the deposited copper is 0.2 μm (10-point average roughness). (Rz: 1.0 μm) was obtained.
An intermediate layer was formed on the surface by nickel-phosphorus plating with the following composition and conditions. As a result, the thickness of the plating was about 0.2 μm as measured by a fluorescent X-ray film thickness meter.
(composition)
Nickel sulfate (NiSO₄・ 6H₂O) ... 300g / l
Nickel chloride (NiCl₂・ 6H₂O) ・ ・ ・ ・ 50g / l
Boric acid (H₃BO₃) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 40g / l
Phosphorous acid 10g / l
(conditions)
Current density: 1.5 A / dm²
Liquid temperature: 50 ° C
Time; 5 minutes
Next, as a first copper layer, electrolytic copper plating was performed on the surface of the nickel-phosphorus alloy layer thus deposited, using a copper sulfate plating solution, smooth plating at a thickness of 3 μm, roughening plating at 1 μm, and electrolytic plating. As a result, granular precipitation having a particle size of approximately 0.2 to 0.4 μm was performed, and the plating thickness was approximately 4 μm. The average roughness at this time was about 0.5 μm.
Further, the surface of the last formed first copper layer is electrolytically treated with Na.₂Cr₂O₇・ 2H₂O; 5 g / l, 0.3 A / dm²The anticorrosion film of the chromate treatment was formed under the conditions described above to obtain a metal foil for a printed wiring board having a three-layer structure consisting of a first copper layer / intermediate layer / second copper layer.
Next, a glass cloth-epoxy resin prepreg E-67 (trade name, manufactured by Hitachi Chemical Co., Ltd.) is overlaid on the anticorrosion coating surface, and 170 ° C., 30 kgf / cm.²The laminate was integrated by heating and pressing for 90 minutes.
Next, the copper layer formed first was removed using a commercially available solution A process solution (trade name, manufactured by Meltex Corporation) until the nickel-phosphorus alloy layer was exposed.
Next, the exposed nickel-phosphorus alloy layer was removed using an etching solution having the following composition until the last formed first copper layer was exposed.
(composition)
Nitric acid 200 g / l hydrogen peroxide ········ 10 ml / l propionic acid ······ 100 g / l benzotriazole ... 5 g / l (conditions)
Temperature; 50 ° C
Time; 2 minutes
[0025]
Example 2
A metal foil for a printed wiring board was prepared in the same manner as in Example 1 except that the thickness of the second copper layer was set to 120 μm. The average roughness of the second copper layer was 0.2 μm, and the average roughness of the surface of the first copper layer was 0.4 μm.
[0026]
Example 3
A metal foil for a printed wiring board was prepared in the same manner as in Example 1 except that the thickness of the first copper layer was changed to 15 μm. The average roughness of the second copper layer was 0.3 μm, and the average roughness of the surface of the first copper layer was 0.3 μm.
[0027]
Example 4
As an intermediate layer, a metal foil for a printed wiring board was prepared in the same manner as in Example 1 except that plating was performed at a solution temperature of 80 ° C. for 1 minute using an electroless nickel-phosphorous plating solution having the following composition. The thickness of the intermediate layer was about 0.2 μm as measured by a fluorescent X-ray film thickness meter. The average roughness of the second copper layer was 0.3 μm, and the average roughness of the surface of the first copper layer was 0.5 μm.
(composition)
Nickel chloride (NiCl₂・ 6H₂O) ... 30g / l
Acetic acid (CH₃COOH) 10 g / l
Sodium hypophosphite (NaH₂PO₂・ 6H₂O) ········· 10 g / l
Hydrochloric acid ・ ・ ・ ・ ・ ・ ・ ・ ・ Amount to adjust the pH to 5 in combination with the above composition
[0028]
Example 5
A metal foil for a printed wiring board was prepared in the same manner as in Example 1 except that the thickness of the intermediate layer was changed to 0.04 μm. The average roughness of the second copper layer was 0.3 μm, and the average roughness of the surface of the first copper layer was 0.8 μm.
[0029]
Example 6
A metal foil for a printed wiring board was prepared in the same manner as in Example 1 except that the intermediate layer was plated with nickel having the following composition. The average roughness of the second copper layer was 0.4 μm, and the average roughness of the surface of the first copper layer was 0.7 μm.
(composition)
Nickel sulfate (NiSO₄・ 6H₂O) 100g / l
Nickel chloride (NiCl₂・ 6H₂O) ... 50g / l
Boric acid 40 g / l
(conditions)
Current density: 5 A / dm²
Liquid temperature; 40 ° C
Time; 21 seconds
[0030]
Comparative Example 1
A metal foil for a printed wiring board was prepared in the same manner as in Example 1 except that the intermediate layer was plated with lead-tin having the following composition. The average roughness of the second copper layer was 0.2 μm, and the average roughness of the surface of the first copper layer was 0.5 μm.
(composition)
Stannous borofluoride 130g / l
Lead borofluoride 50g / l
Borofluoric acid ... 125g / l
Boric acid 25 g / l
Peptone ... 5g / l
(conditions)
Current density: 2.5 A / dm²
Liquid temperature; 25 ° C
Time; 21 seconds
[0031]
Comparative Example 2
A metal foil for a printed wiring board was prepared in the same manner as in Example 1 except that the intermediate layer was plated with tin having the following composition. The average roughness of the second copper layer was 0.3 μm, and the average roughness of the surface of the first copper layer was 0.3 μm.
(composition)
Tin sulfate ... 73g / l
Sulfuric acid 50g / l
Phenolsulfonic acid 40g / l
Gelatin ... 2g / l
β-naphthol 1g / l
(conditions)
Current density: 2.5 A / dm²
Liquid temperature; 25 ° C
Time; 20 seconds
[0032]
Comparative Example 3
The same prepreg as in Example 1 was heated and pressed on a 5 μm copper foil with an aluminum carrier under the same conditions to form a laminated board. Thereafter, the aluminum carrier was removed, and electrolytic plating was performed to reduce the thickness of the copper foil to about 35 μm. At this time, the average roughness of the surface of the copper layer serving as a circuit was 0.5 μm.
[0033]
Example 7
Instead of the nickel-phosphorus alloy layer in Example 1, an intermediate layer was formed using Blue Schumer SB-55 (trade name, manufactured by Nippon Kanigen Co., Ltd.), which is an electroless nickel-boron plating solution containing a boron reducing agent. A metal foil for a printed wiring board was prepared in the same manner as in Example 1 except for the above. The average roughness of the second copper layer was 0.3 μm, and the average roughness of the surface of the first copper layer was 0.6 μm.
[0034]
Comparative Example 4
Test pieces were prepared in the same manner as in Example 1 except that the thickness of the nickel-phosphorus alloy layer in Example 1 was changed to 0.02 μm. The average roughness of the second copper layer was 0.2 μm, and the average roughness of the surface of the first copper layer was 0.4 μm.
[0035]
Comparative Example 5
The first copper layer was formed in the same manner as in Example 1 except that the average roughness of the first copper layer was 0.02 μm.
[0036]
(test)
(1) Preparation of test pieces and formability of wiring
A plating resist is formed so as to expose only the portion of the circuit conductor to be obtained on the surface of the laminate thus prepared, and a copper foil is formed by electrolytic plating on the portion exposed from the resist in the same manner as described above. It was formed to 30 μm. Thereafter, solder plating was deposited to a thickness of 8 μm, and the plating resist was peeled off to expose the copper layer covered by the plating resist, and etching was performed with an alkaline etching solution to such an extent that the exposed copper layer could be removed. . As a result, the shape of the circuit conductor with the copper layer formed thereon was a pattern for testing, forming a 10 mm wide, 100 mm long rectangle, and a 30 μm wide conductor. The formability of this 30 μm conductor was examined, and the case where all the conductors were formed was marked as Δ, the case where a part of the conductor was formed was marked as Δ, and the case where no conductor was formed at all was marked X.
Table 1 shows the above results.
[0037]
(2) Observation of pinhole
The second copper layer of each of the metal-foil-laminated laminates for printed wiring boards prepared in Examples 1 to 7 and Comparative Examples 1 to 5 was removed by etching with an alkali etchant. The judgment was made that the number of pinholes having a diameter of 50 μm or less was an area of 3 cm × 3 cm (0.09 m²In), 100 or less was defined as Δ, 101 to 200 was defined as Δ, and 201 or more was defined as ×.
[0038]
(3) Heat resistance of the intermediate layer
The selective etching property of the intermediate layer was visually observed by using the metal foil-bonded laminates for printed wiring boards prepared in Examples 1 to 7 and Comparative Examples 1 to 5 which were heated at 200 to 500 ° C. for 30 minutes. did.
A case where only the second copper layer is selectively etched is Δ, a case where a part of the intermediate layer is etched to form a pinhole, and a case where the intermediate layer and the intermediate layer are removed by etching is ×. And
[0039]
(4) Stability of plating solution
The plating solution on which the intermediate layer was formed was left for a long time, and the occurrence of decomposition and precipitation was observed.
[0040]
Example 8
As the second copper layer, electrolytic copper plating was performed on the surface of the stainless steel plate using copper sulfate plating. As a result, the plating thickness was about 30 μm, and the average surface roughness of the deposited copper was 0.2 μm.
Next, as the intermediate layer, a nickel-phosphorus alloy plating solution having the following composition was used and 0.7 A / dm.² Electrolytic nickel-phosphorus plating was performed under the conditions of a solution temperature of 50 ° C. and a plating time of about 16 minutes. As a result, the plating thickness was about 1.0 μm.
(composition)
Nickel sulfate 300g / l
Nickel chloride ... 50g / l
Boric acid 40 g / l
Phosphorous acid 10g / l
Next, electrolytic plating was performed on the surface of the deposited nickel-phosphorus alloy layer as a first copper layer using a copper sulfate plating solution. As a result, granular precipitation having a particle size of approximately 0.2 to 0.4 μm was performed, the plating thickness was about 2 μm, and the average surface roughness was 0.4 μm.
Further, an anticorrosion film of chromate treatment was formed on the surface of the copper layer formed last by electrolytic treatment.
Using two metal foils for a printed wiring board prepared in this manner, an epoxy resin impregnated glass cloth prepreg E-67 which is a thermosetting resin semi-cured on the roughened surface of the first copper layer (Hitachi, Japan) The prepregs are sandwiched between the prepregs in such a manner that the prepregs are in contact with each other at 170 ° C. and 30 kgf / cm.²Under heat and pressure for 90 minutes, the layers were integrated.
Only the second copper layer on both surfaces is removed by etching with an A process solution (trade name, manufactured by Meltex Co., Ltd.), which is an alkaline etching solution. The hole is removed, a hole is formed, and a 5 μm-thick electroless plating is performed on the entire surface using a CC-41 plating solution (trade name, manufactured by Hitachi Chemical Co., Ltd.) on the inner wall of the hole and the surface of the first copper layer on both surfaces. Then, electrolytic copper plating was performed using a copper pyrophosphate plating bath to form a copper layer having a thickness of 25 μm, and an etching resist was formed to form a circuit conductor.
[0041]
Example 9
A semi-cured epoxy resin prepreg E-67 (trade name, manufactured by Hitachi Chemical Co., Ltd.) was overlaid on the roughened surface of the first copper layer of the metal foil for printed wiring boards of Example 8, and A copper foil of 35 μm is placed on the other side, and the temperature is 170 ° C., 30 kgf / cm²The laminate was integrated by heating and pressing for 90 minutes. Only the first copper layer was removed by etching with an etching solution for process A (trade name, manufactured by Meltex Co., Ltd.), which is an alkaline etching solution. Then, a hole having a thickness of 5 μm was formed on the entire surface using a CC-41 plating solution (trade name, manufactured by Hitachi Chemical Co., Ltd.) on the entire surface of the inner wall of the hole, the first copper layer, and the bonded copper foil. Electroplating was performed, and further, electrolytic copper plating was performed in a copper pyrophosphate plating bath to form a copper layer having a thickness of 25 μm, and an etching resist was formed to form a circuit conductor.
[0042]
Example 10
Using two pieces of the metal foil for a printed wiring board prepared in Example 8, a prepreg impregnated with polytetrafluoroethylene, which is a fluororesin, which is a thermoplastic resin, comes into contact with the roughened surface of the first copper layer. At 385 ° C, 20 kgf / cm²The laminate was integrated by heating and pressing for 90 minutes.
Only the second copper layer on both surfaces is removed by etching with an A process solution (trade name, manufactured by Meltex Co., Ltd.), which is an alkaline etching solution. The hole is removed, a hole is formed, and a 5 μm-thick electroless plating is performed on the entire surface using a CC-41 plating solution (trade name, manufactured by Hitachi Chemical Co., Ltd.) on the inner wall of the hole and the surface of the first copper layer on both surfaces. Then, electrolytic copper plating was performed using a copper pyrophosphate plating bath to form a copper layer having a thickness of 25 μm, and an etching resist was formed to form a circuit conductor.
[0043]
Example 11
Rolled copper foil of 35 μm was used as the second copper layer, and the surface was roughened by soft etching using ammonium persulfate. The average surface roughness of this rolled copper foil was 0.2 μm.
Next, as the intermediate layer, 1.5 A / dm.²Electrolytic nickel-phosphorus alloy plating was performed under the conditions of a liquid temperature of 50 ° C. and a plating time of 8 minutes. As a result, the thickness of the plating was about 0.5 μm.
(composition)
Nickel sulfate 300g / l
Nickel chloride ... 50g / l
Boric acid 40 g / l
Phosphorous acid 10g / l
Next, electrolytic plating was performed on the surface of the deposited nickel-phosphorus alloy layer as a first copper layer using a copper sulfate plating solution. As a result, granular precipitation having a particle size of approximately 0.2 to 0.4 μm was performed, and the plating thickness was approximately 2 μm. The average surface roughness was 0.4 μm.
Thereafter, the surface of the copper foil was oxidized with an oxidizing agent to form an oxide film. As the oxidation treatment, treatment with an alkali aqueous solution of an chlorite oxidizing agent was performed. Further, the oxide film was brought into contact with dimethylamine borane as a reducing agent, and at least a part thereof was reduced to metallic copper.
A varnish of polyamic acid was directly applied to the roughened surfaces of the first copper layers of the two metal foils thus formed, the applied surfaces were matched, and the polyimide was cured by heating to 400 ° C. Removing only the second copper layer with an alkaline etchant, subsequently removing the nickel-phosphorus alloy layer with an etchant used to remove only the nickel-phosphorus alloy layer used in Example 1, and drilling holes; Electroless plating of a thickness of 5 μm is performed using a CC-41 plating solution (trade name, manufactured by Hitachi Chemical Co., Ltd.) on the entire surface of the inner wall of the hole and the first copper layer on both surfaces, and then a copper pyrophosphate plating solution is further applied. Was used to perform electrolytic copper plating to obtain a copper layer having a thickness of about 25 μm.
Thereafter, a plating resist is formed, solder plating is formed by electroplating on a portion exposed from the plating resist, and after the plating resist is peeled off, the copper layer exposed from the solder plating is removed by an alkali etching solution. Then, the solder plating was removed by a solder plating stripper to form a circuit conductor.
[0044]
Example 12
On the roughened surface of the first copper layer of the metal foil for a printed wiring board prepared in Example 11, a fluororesin polytetrafluoroethylene sheet as a thermoplastic resin was overlapped and sandwiched between two metal foils, 385 ° C, 20kgf / cm²Laminate by heating under the conditions of 90 minutes to remove only the second copper layer by etching, and then remove by using the solution for etching only the nickel-phosphorus alloy layer used in Example 1 to form an etching resist. Thus, a circuit conductor was formed.
[0045]
[Table 1]

[0046]
All of the printed wiring boards of Examples 8 to 12 obtained as described above can be formed with a wiring density of up to 0.03 mm in circuit width, and all have a peeling degree of 1.3 to 1.4 kgf / cm.²Was in the range. In the case of Comparative Examples 2 and 3, the peel strength was about 1.2 kgf / cm.²However, the stability of the plating solution, the wiring formability and the heat resistance were inferior, and in Comparative Example 5, 0.4 kgf / cm²Was small.
[0047]
【The invention's effect】
As described above, a metal foil for a printed wiring board excellent in suppressing pinholes and excellent in wiring density according to the present invention, a method of manufacturing the same, and a method of efficiently manufacturing a printed wiring board using the metal foil Can be provided.

Claims (12)

In a first copper layer to be a circuit, a second copper layer having sufficient strength as a metal foil as a whole, and a metal foil composed of an intermediate layer sandwiched between the first copper layer and the resin of the first copper layer, The average roughness of the surface in contact with the intermediate layer of the second copper layer is 0.1 to 0.8 μm, the average roughness of the surface in contact with the intermediate layer of the second copper layer is 0.05 to 0.4 μm, and the intermediate layer is nickel or an alloy thereof. Wherein the metal foil has a thickness of 0.04 to 1.5 μm. The metal foil for a printed wiring board according to claim 1, wherein the thickness of the second copper layer is in the range of 10 to 150 m. The metal foil for a printed wiring board according to claim 1, wherein a thickness of the first copper layer is in a range of 1 to 15 μm. The printing according to any one of claims 1 to 3, wherein a rust preventive coating is provided on a surface (outside surface) of the first copper layer and the second copper layer that is not in contact with the intermediate layer. Metal foil for wiring boards. At least one of the surfaces of the second copper layer having sufficient strength as the whole metal foil has an average roughness in the range of 0.05 to 0.4 μm and a thickness of 0.04 to 1. After forming a layer of nickel or an alloy thereof having a thickness of 5 μm and further forming a first copper layer serving as a circuit on the surface thereof, the surface of the first copper layer in contact with the resin has an average roughness of 0.1 to 0.1 μm. A method for producing a metal foil for a printed wiring board, wherein a roughened surface is formed to have a thickness of 8 μm. 6. The printing method according to claim 5, wherein the step of forming the roughened surface on the surface of the first copper layer is performed by a method selected from among electroplating, electroless plating, displacement plating, etching and vapor deposition. Manufacturing method of metal foil for wiring boards. A method for manufacturing a printed wiring board, comprising the following steps in this order:
a. A first copper layer serving as a circuit, a second copper layer having sufficient strength as a metal foil for a printed wiring board as a whole, and a metal foil including an intermediate layer sandwiched between the first copper layer and the first copper layer The average roughness of the surface of the layer in contact with the resin is 0.1 to 0.8 μm, the average roughness of the surface of the second copper layer in contact with the intermediate layer is 0.05 to 0.4 μm, and the intermediate layer is A surface of the first copper layer is impregnated with an uncured or semi-cured thermosetting resin of nickel or an alloy thereof and having a thickness of 0.04 to 1.5 μm for a printed wiring board. A step of stacking the prepregs so as to be in contact with each other, and heating and pressurizing to laminate and integrate b. Etching away only the second copper layer c. A step of etching and removing only the intermediate layer d. Step of forming circuit conductors A method for manufacturing a printed wiring board, comprising the following steps in this order:
a. A first copper layer serving as a circuit, a second copper layer having sufficient strength as a metal foil for a printed wiring board as a whole, and a metal foil including an intermediate layer sandwiched between the first copper layer and the first copper layer The average roughness of the surface of the layer in contact with the resin is 0.1 to 0.8 μm, the average roughness of the surface of the second copper layer in contact with the intermediate layer is 0.05 to 0.4 μm, and the intermediate layer is A prepreg impregnated with a thermoplastic resin is superimposed on the surface of the first copper layer of the metal foil for a printed wiring board, which is nickel or an alloy thereof and has a thickness of 0.04 to 1.5 μm, and is heated and pressed. B. Lamination and integration. Etching away only the second copper layer c. A step of etching and removing only the intermediate layer d. Step of forming circuit conductors A method for manufacturing a printed wiring board, comprising the following steps in this order:
a. In a metal foil for a printed wiring board including a first copper layer to be a circuit, a second copper layer having sufficient strength as a whole metal foil, and an intermediate layer sandwiched between the first copper layer and the first copper layer, The average roughness of the surface of the layer in contact with the resin is 0.1 to 0.8 μm, the average roughness of the surface of the second copper layer in contact with the intermediate layer is 0.05 to 0.4 μm, and the intermediate layer is A mixture of an uncured thermosetting resin and a curing agent thereof on a surface of a first copper layer of a metal foil for a printed wiring board, which is nickel or an alloy thereof and has a thickness of 0.04 to 1.5 μm. Applying and heating to cure b. Etching away only the second copper layer c. A step of etching and removing only the intermediate layer d. Step of forming circuit conductors A method for manufacturing a printed wiring board, comprising the following steps in this order:
a. A first copper layer serving as a circuit, a second copper layer having sufficient strength as a metal foil for a printed wiring board as a whole, and a metal foil including an intermediate layer sandwiched between the first copper layer and the first copper layer The average roughness of the surface of the layer in contact with the resin is 0.1 to 0.8 μm, the average roughness of the surface of the second copper layer in contact with the intermediate layer is 0.05 to 0.4 μm, and the intermediate layer is A thermoplastic resin sheet is superimposed on the surface of the first copper layer of the metal foil for a printed wiring board, which is nickel or an alloy thereof and has a thickness of 0.04 to 1.5 μm, and is laminated by heating and pressing. B. Etching away only the second copper layer c. A step of etching and removing only the intermediate layer d. Step of forming circuit conductors The method for manufacturing a printed wiring board according to any one of claims 7 to 10, wherein the etching solution for removing only the second copper layer contains chlorine ions, ammonium ions, and copper ions. 12. The printed wiring board according to claim 7, wherein the etching solution for removing only the intermediate layer contains nitric acid, hydrogen peroxide, an organic acid containing a carboxyl group, and benzotriazole. Manufacturing method.