TECHNICAL FIELD

The present application relates to a surface-treated copper foil, a copper foil having a carrier, a laminated material, a method for producing a printed wiring board, and a method for producing an electronic apparatus.

BACKGROUND ART

Printed wiring boards have accomplished great development over the recent half century, and have been finally used in almost all of electronic apparatuses. Associated with the increasing needs of size reduction and performance enhancement of electronic apparatuses in recent years, the components are mounted in high density, and the frequency of signal is increased, which result in the demand of the printed wiring board having excellent capability to adapt to high frequency.

A high frequency board is demanded to have a decreased transmission loss for ensuring the quality of the output signal. The transmission loss is formed mainly of a dielectric loss caused by the resin (i.e., the substrate side) and a conductor loss caused by the conductor (i.e., the copper foil side). The dielectric loss is decreased with the decrease of the dielectric constant and the dielectric loss tangent of the resin. The conductor loss of a high frequency signal is mainly caused by decreasing the cross sectional area, through which an electric current flows, due to the skin effect, in which an electric current having a higher frequency flows only the surface of the conductor, thereby increasing the resistance.

As a technique for decreasing the transmission loss of the high frequency copper foil, for example, PTL 1 describes a metal foil for a high frequency circuit containing a metal foil, silver or a silver alloy that is coated on one surface or both surfaces of the metal foil, and a coated layer other than the silver or silver alloy that is provided on the silver or silver alloy coated layer to a thickness that is smaller than the silver or silver alloy coated layer. There is also described that according to the structure, a metal foil having a decreased loss due to the skin effect in a superhigh frequency region used in the satellite communications can be provided.

PTL 2 describes a surface-roughened rolled copper foil for a high frequency circuit, in which the ratio of the integral intensity (I(200)) of the (200) plane measured by X-ray diffraction of the rolled surface of the rolled copper foil after the recrystallization annealing to the integral intensity (I0(200)) of the (200) plane measured by X-ray diffraction of the fine powder copper is I(200)/I0(200)>40, the roughened surface of the rolled surface after subjecting to the roughening treatment by electrolytic plating has an arithmetic average roughness (which may be hereinafter referred to as Ra) of from 0.02 μm to 0.2 μm and a ten-point average roughness (which may be hereinafter referred to as Rz) of from 0.1 μm to 1.5 μm, and the copper foil is a material for a printed circuit board. There is also described that according to the structure, a printed circuit board capable of being used under a high frequency exceeding 1 GHz can be provided.

PTL 3 describes an electrolytic copper foil, in which a part of the surface of the copper foil is an uneven surface constituted by knobby protrusions having a surface roughness of from 2 μm to 4 μm. There is also described that according to the structure, an electrolytic copper foil excellent in high frequency transmission characteristics can be provided.

PTL 4 describes a surface-treated copper foil having on at least one surface thereof a surface treatment layer, in which the surface treatment layer contains a roughening treatment layer, the surface treatment layer has a total deposited amount of Co, Ni, and Fe of 300 μg/dm2or less, the surface treatment layer has a Zn metal layer or an alloy treatment layer containing Zn, the surface treatment layer has a ratio of a three-dimensional surface area to a two-dimensional surface area measured with a laser microscope of from 1.0 to 1.9, at least one surface of the copper foil has a surface roughness Rz JIS of 2.2 μm or less, the surface treatment layer is formed on both surfaces of the copper foil, and the both surfaces have a surface roughness Rz JIS of 2.2 μm or less. There is also described that according to the structure, a surface-treated copper foil capable of favorably suppressing the transmission loss even used in a high frequency circuit board can be provided.

CITATION LIST

Patent Literatures

PTL 1: Japanese Patent No. 4,161,304

PTL 2: Japanese Patent No. 4,704,025

PTL 3: JP-A-2004-244656

PTL 4: Japanese Patent No. 5,710,737

SUMMARY OF INVENTION

Technical Problem

The control of the transmission loss of the copper foil used in a high frequency circuit board has been variously investigated as described above, but there is still room for development. Furthermore, there are cases where a circuit (copper wiring) is subjected to soft etching with an acid or the like in the production of a high frequency circuit board, and therefore the copper foil is still demanded to have enhanced acid resistance.

Solution to Problem

The present inventors have found that in a surface-treated copper foil containing a copper foil and a surface treatment layer containing a roughening treatment layer on one or both surfaces of the copper foil, the transmission loss can be favorably decreased even used in a high frequency circuit board, and the acid resistance thereof can be improved, by controlling the content ratio of Ni in the surface treatment layer, and the ten-point average roughness Rz of the outermost surface of the surface treatment layer.

One or more embodiments of the present application have been completed based on the aforementioned knowledge, and relate to, in one aspect, a surface-treated copper foil containing a copper foil, and a surface treatment layer containing a roughening treatment layer on at least one surface of the copper foil, wherein the surface treatment layer contains Ni, the surface treatment layer has a content ratio of Ni of 8% by mass or less (excluding 0% by mass), and an outermost surface of the surface treatment layer has a ten-point average roughness Rz of 1.4 μm or less.

In one embodiment of the surface-treated copper foil of the present application, the surface treatment layer has a total deposited amount of from 1.0 to 5.0 g/m2.

In another embodiment of the surface-treated copper foil of the present application, the surface treatment layer contains Co, and the surface treatment layer has a content ratio of Co of 15% by mass or less (excluding 0% by mass).

In still another embodiment of the surface-treated copper foil of the present application, the surface treatment layer has a deposited amount of Co of from 30 to 2,000 μg/d m2.

In still another embodiment of the surface-treated copper foil of the present application, the surface treatment layer contains Ni, and the surface treatment layer has a deposited amount of Ni of from 10 to 1,000 μg/dm2.

In still another embodiment of the surface-treated copper foil of the present application, the surface treatment layer further contains one or more layer selected from the group consisting of a heat resistant layer, a rust preventing layer, a chromate treatment layer, and a silane coupling treatment layer.

In still another embodiment of the surface-treated copper foil of the present application, the surface-treated copper foil is used in a copper-clad laminated board or a printed wiring board for a high frequency circuit board.

The present application also relates to, in another aspect, a surface-treated copper foil having a resin layer, containing the surface-treated copper foil according to one or more embodiments of the present application, and a resin layer.

The present application also relates to, in still another aspect, a copper foil having a carrier, containing a carrier, and an intermediate layer and an ultrathin copper layer on at least one surface of the carrier, wherein the ultrathin copper layer is the surface-treated copper foil according to one or more embodiments of the present application, or the surface-treated copper foil having a resin layer according to one or more embodiments of the present application.

The present application also relates to, in still another aspect, a laminated material containing the surface-treated copper foil according to one or more embodiments of the present application, the surface-treated copper foil having a resin layer according to one or more embodiments of the present application, or the copper foil having a carrier according to one or more embodiments of the present application.

The present application also relates to, in still another aspect, a laminated material containing the copper foil having a carrier according to one or more embodiments of the present application, and a resin, wherein a part or the whole of an end face of the copper foil having a carrier is covered with the resin.

The present application also relates to, in still another aspect, a laminated material containing two of the copper foils having a carrier according to one or more embodiments of the present application.

The present application also relates to, in still another aspect, a method for producing a printed wiring board containing using the surface-treated copper foil according to one or more embodiments of the present application, the surface-treated copper foil having a resin layer according to one or more embodiments of the present application, or the copper foil having a carrier according to one or more embodiments of the present application.

The present application also relates to, in still another aspect, a method for producing a printed wiring board containing: laminating the surface-treated copper foil according to one or more embodiments of the present application or the surface-treated copper foil having a resin layer according to one or more embodiments of the present application with an insulating substrate to form a copper-clad laminated board, or laminating the copper foil having a carrier according to one or more embodiments of the present application with an insulating substrate, and then detaching the carrier of the copper foil having a carrier to form a copper-clad laminated board; and forming a circuit by any of a semi-additive method, a subtractive method, a partly additive method, and a modified semi-additive method.

The present application also relates to, in still another aspect, a method for producing a printed wiring board containing: forming a circuit on the surface-treated copper foil according to one or more embodiments of the present application on the side of the surface treatment layer, or forming a circuit on the copper foil having a carrier according to one or more embodiments of the present application on a surface on the side of the ultrathin copper layer or on a surface of the side of the carrier; forming a resin layer on the surface on the side of the surface treatment layer of the surface-treated copper foil or on the surface on the side of the ultrathin copper layer or the surface on the side of the carrier of the copper foil having a carrier, so as to embed the circuit; and after forming the resin layer, removing the surface-treated copper foil, or detaching the carrier or the ultrathin copper layer, and then removing the ultrathin copper layer or the carrier, so as to expose the circuit having been embedded in the resin layer.

The present application also relates to, in still another aspect, a method for producing a printed wiring board containing: laminating a resin substrate with the copper foil having a carrier according to one or more embodiments of the present application on a surface on the side of the carrier or on a surface on the side of the ultrathin copper layer; providing a resin layer and a circuit at least once on a surface of the copper foil having a carrier that is opposite to the surface having the resin substrate laminated; and after forming the resin layer and the circuit, detaching the carrier or the ultrathin copper layer from the copper foil having a carrier.

The present application also relates to, in still another aspect, a method for producing a printed wiring board containing: providing a resin layer and a circuit at least once on at least one surface of a laminated material containing the copper foil having a carrier according to one or more embodiments of the present application or the laminated material according to one or more embodiments of the present application; and after forming the resin layer and the circuit, detaching the carrier or the ultrathin copper layer from the copper foil having a carrier constituting the laminated material.

The present application also relates to, in still another aspect, a method for producing an electronic apparatus containing using a printed wiring board produced by the method according to one or more embodiments of the present application.

Advantageous Effects of Invention

According to one or more embodiments of the present application, a surface-treated copper foil can be provided that is capable of favorably decreasing the transmission loss even used in a high frequency circuit board and has good acid resistance.

