JP2011210994A - Copper foil for printed wiring board, and laminate using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper foil for a printed wiring board which has superior heat resistance, excellent etching properties during circuit pattern formation, and is suitable for fine-pitch fabrication, and to provide a layered body using the same.SOLUTION: The copper foil for the printed wiring board includes: a copper foil base material; and a coating layer which covers at least a part of a surface of the copper foil base material. The coating layer is composed of Ni alone or Ni alloy of 80 to 800 μg/dmin sticking amount, or Cu alloy of 300 to 1,500 μg/dmin sticking amount.

Description

  The present invention relates to a copper foil for a printed wiring board and a laminate using the same, and more particularly to a copper foil for a flexible printed wiring board and a laminate using the same.

  Printed wiring boards have made great progress over the last half century and are now used in almost all electronic devices. In recent years, with the increasing needs for miniaturization and higher performance of electronic devices, higher density mounting of components and higher frequency of signals have progressed, and circuit patterns of conductors have become finer (fine pitch) with respect to printed wiring boards. And high-frequency response is required. In particular, regarding finer pitches of circuit patterns, it is currently required to form a circuit pattern having a pitch of 50 μm or less.

  In general, a printed wiring board is manufactured through a process in which an insulating substrate is bonded to a copper foil to form a laminate, and then a conductor pattern is formed on the copper foil surface by etching. Therefore, one surface of the copper foil for printed wiring boards is required to have good adhesion and etching properties with the insulating substrate, and the other surface has not only good etching properties when forming a circuit pattern. In view of the appearance, it is necessary that the material does not easily discolor due to the heat history when adhered to the insulating substrate, so that good heat resistance is also required.

  Alternatively, a printed wiring board is formed by forming a very thin metal layer on an insulating substrate by dry film formation or electroless plating, electrodepositing a copper layer starting from the metal layer, forming a laminate, and then etching the copper foil surface. In general, it is manufactured through a process of forming a conductor pattern. After forming the circuit, it is incorporated as an electronic component, and current continues to flow for several years. Therefore, the surface on the etching surface side of the copper layer is not easily changed in color due to the thermal history due to the circuit energization cycle in order to maintain not only good etching properties when forming a circuit pattern, but also good long-term conductivity. Therefore, good heat resistance is also required.

Here, in Patent Document 1, an alloy layer composed of nickel and cobalt is formed on the surface of a copper foil, and a rust preventive layer composed of a zinc layer and a chromate layer is formed thereon to form a glossy surface. In the copper foil for wiring boards, the alloy layer has a nickel adhesion amount of 0.5 μg / cm ² or more and 2.0 μg / cm ² or less, and the cobalt adhesion amount is the sum of the nickel adhesion amount and the cobalt adhesion amount. There is disclosed a copper foil for printed wiring board characterized by a mass ratio of 40% to 80%. In addition, according to this, the heat discoloration resistance of the glossy copper foil surface is improved so as not to cause discoloration even at high temperature treatment, the acid solubility is good, and the printed wiring board is environmentally friendly and does not use hexavalent chromium. It is described that a copper foil can be provided.

Patent Document 2 discloses a copper foil for a printed wiring board in which a nickel layer and a chromium layer are sequentially formed on a surface of a copper foil by a sputtering method to form a smooth adhesive layer with an insulating substrate. , is not less 15 [mu] g / dm ² or more 440μg / dm ² or less weight nickel deposition, copper foil for printed wiring boards, wherein the amount of chromium deposited is 15 [mu] g / dm ² or more 210μg / dm ² or less is disclosed . According to this, it is described that a copper foil for a wiring board can be provided in which the nickel layer and the chromium layer have high adhesion to the insulating substrate and the etching property at the time of forming the circuit pattern is good.

JP 2009-81396 A International Publication No. 2009/081889

  In Patent Document 1, chromate treatment is performed to impart heat resistance to the etched surface side of the copper foil, and heat resistance is imparted to some extent. However, if Cr is present on the outermost surface of the etching surface side coating, it causes etching failure.

  Patent Document 2 is extremely excellent in adhesion with an insulating substrate. However, when the surface treatment is not performed on the etched surface side of the copper foil, the copper foil may be discolored by heat treatment when adhering to the insulating substrate. In Patent Document 2, a film is formed by a sputtering method, particularly by a sputtering method. Therefore, forming the surface treatment layer on the etched surface side of the copper foil by electrolytic plating leads to a decrease in productivity.

  Therefore, the present invention is excellent in heat resistance by forming a coating film by dry film formation on the copper foil or the surface side to be the etching surface of the laminate. It is an object of the present invention to provide a copper foil for a printed wiring board suitable for manufacturing and a laminate using the copper foil.

It is necessary to form a metal film that is more heat resistant than pure copper on the circuit pattern forming side surface of the copper foil of the laminate, so that it does not change color at the time of resin curing or thermocompression bonding or the heat history of the energization cycle, By forming a film having an adhesion amount of Ni simple substance or Ni alloy of 80 to 800 μg / dm ² or Cu alloy of 300 to 1500 μg / dm ² , it is favorable on the circuit pattern forming surface side of the copper foil or laminate. Heat resistance and etching properties can be imparted.

The present invention completed on the basis of the above knowledge is, in one aspect, a copper foil for a printed wiring board comprising a copper foil substrate and a coating layer covering at least a part of one surface of the copper foil substrate. The coating layer is a copper foil for a printed wiring board in which the adhesion amount is 80 to 800 μg / dm ² of Ni alone or Ni alloy, or the adhesion amount is 300 to 1500 μg / dm ² of Cu alloy.

  In one embodiment of the copper foil for printed wiring boards according to the present invention, the Ni alloy is composed of Ni and at least one of Cu, Sn, V, Mn, Zn, and Cr.

In another embodiment of the copper foil for printed wiring boards according to the present invention, the Ni simple substance or the Ni alloy is present in the coating layer in an adhesion amount of 160 to 700 μg / dm ² .

In still another embodiment of the copper foil for printed wiring board according to the present invention, the Ni simple substance or the Ni alloy is present in an amount of 300 to 600 μg / dm ^{2 in} the coating layer.

  In still another embodiment of the copper foil for printed wiring board according to the present invention, 3 to 50% by mass of any one of Cu, Sn, V, Mn, Zn and Cr is present in the Ni alloy layer.

  In still another embodiment of the copper foil for printed wiring board according to the present invention, the Cu alloy is composed of Cu and at least one of Ni, Sn, V, Mn, Zn, and Cr.

In still another embodiment of the copper foil for printed wiring board according to the present invention, the Cu alloy is present in the coating layer in an adhesion amount of 400 to 1200 μg / dm ² .

In still another embodiment of the copper foil for printed wiring board according to the present invention, the Cu alloy is present in an amount of 450 to 1000 μg / dm ^{2 in} the coating layer.

  In still another embodiment of the copper foil for printed wiring board according to the present invention, 20 to 70% by mass of any one or two of Sn, Zn and Ni are present in the Cu alloy layer.

  In yet another embodiment of the copper foil for printed wiring board according to the present invention, the atomic concentration of nickel in the depth direction (x: unit nm) obtained from the depth direction analysis from the surface by XPS of the coating layer (%) Is f (x), atomic concentration (%) of any one of tin, vanadium, chromium, manganese and zinc is g (x), and atomic concentration (%) of oxygen is h (x) If the atomic concentration (%) of copper is i (x), the atomic concentration (%) of carbon is j (x), and the total of other atomic concentrations is k (x), the interval [4.0, 8 .0], ∫h (x) dx / (∫f (x) dx + ∫g (x) dx + ∫h (x) dx + ∫i (x) dx + ∫j (x) dx + ∫k (x) dx) satisfies 5% or less.

  In yet another embodiment of the copper foil for printed wiring board according to the present invention, when heat treatment equivalent to lamination or heat treatment equivalent to polyimide curing is performed, from the depth direction analysis from the surface of the coating layer by XPS The atomic concentration (%) of nickel in the depth direction (x: unit nm) is defined as f (x), and the atomic concentration (%) of any one of tin, vanadium, chromium, manganese and zinc is expressed as g ( x), oxygen atomic concentration (%) as h (x), copper atomic concentration (%) as i (x), carbon atomic concentration (%) as j (x), and other atomic concentrations In the interval [4.0, 8.0], ８h (x) dx / (∫f (x) dx + ∫g (x) dx + ∫h (x) dx + ∫i (x) dx + ∫j (x) dx + ∫k (x) dx) is 5% or less.

  In yet another embodiment of the copper foil for printed wiring board according to the present invention, heat treatment equivalent to lamination or heat treatment equivalent to polyimide curing is performed, and from the depth direction analysis from the surface of the coating layer by XPS The atomic concentration (%) of nickel in the depth direction (x: unit nm) is defined as f (x), and the atomic concentration (%) of any one of tin, vanadium, chromium, manganese and zinc is expressed as g ( x), oxygen atomic concentration (%) as h (x), copper atomic concentration (%) as i (x), carbon atomic concentration (%) as j (x), and other atomic concentrations In the interval [4.0, 8.0], ８h (x) dx / (∫f (x) dx + ∫g (x) dx + ∫h (x) dx + ∫i (x) dx + ∫j (x) dx + ∫k (x) dx) is 5% or less.

  In yet another embodiment of the copper foil for a printed wiring board according to the present invention, a printed wiring board in which an insulating substrate is formed on the surface opposite to the surface on which the coating layer is formed by performing lamination or polyimide curing. For the copper foil for coating, the atomic concentration (%) of nickel in the depth direction (x: unit nm) obtained from the depth direction analysis from the surface of the coating layer by XPS is defined as f (x), tin, vanadium, The atomic concentration (%) of any one of chromium, manganese and zinc is g (x), the atomic concentration (%) of oxygen is h (x), and the atomic concentration (%) of copper is i (x) , Where j (x) is the atomic concentration (%) of carbon and k (x) is the sum of the other atomic concentrations, in the interval [4.0, 8.0], ∫h (x) dx / (∫ f (x) dx + ∫g (x) dx + ∫h (x) dx + ∫i (x) dx + ∫j (x) dx + ∫k (x) dx) satisfies 5% or less.

  In yet another embodiment of the copper foil for printed wiring board according to the present invention, the copper foil base material is a rolled copper foil or an electrolytic copper foil.

  In another embodiment of the copper foil for printed wiring boards according to the present invention, the printed wiring board is a flexible printed wiring board.

  In another aspect of the present invention, at least a part of one surface of the copper foil base material contains Ni alone or any one of Ni, Cu, Sn, V, Mn, and Zn by a sputtering method. Forming a Ni alloy or a coating layer made of a Cu alloy with a thickness of 1.0 to 9.0 nm and a Cu alloy with a thickness of 3.0 to 16.0 nm; It is a manufacturing method of the copper foil for printed wiring boards.

  In another aspect of the present invention, there is provided a laminate of the copper foil and the resin substrate according to the present invention.

  In still another aspect, the present invention is a laminate including a copper layer and a resin substrate, the laminate including the coating layer according to the present invention that covers at least a part of the surface of the copper layer.

  In one embodiment of the laminate according to the present invention, the resin substrate is a polyimide substrate.

  In yet another aspect, the present invention is a printed wiring board made of the laminate according to the present invention.

  According to the present invention, it is possible to obtain a copper foil for a printed wiring board which is excellent in heat resistance, has good etching properties when forming a circuit pattern, and is suitable for fine pitch formation, and a laminate using the copper foil.

It is a depth profile by XPS of the coating layer surface of the copper foil of Example 1 (after heat treatment equivalent to a laminate). It is a depth profile by XPS of the coating layer surface of the copper foil (after heat processing equivalent to a laminate) of Example 2. It is a photograph of the circuit formed by the comparative example d.

(Copper foil base material)
Although there is no restriction | limiting in particular in the form of the copper foil base material which can be used for this invention, Typically, it can use with the form of rolled copper foil or electrolytic copper foil. In general, the electrolytic copper foil is produced by electrolytic deposition of copper from a copper sulfate plating bath onto a drum of titanium or stainless steel, and the rolled copper foil is produced by repeating plastic working and heat treatment with a rolling roll. Rolled copper foil is often used for applications that require flexibility.
As a material of the copper foil base material, in addition to high-purity copper such as tough pitch copper or oxygen-free copper, which is usually used as a circuit pattern of a printed wiring board conductor, for example, Sn-containing copper, Ag-containing copper, Cr, Zr or Mg It is also possible to use a copper alloy such as a copper alloy to which Ni is added and a Corson-based copper alloy to which Ni and Si are added. In addition, when the term “copper foil” is used alone in this specification, a copper alloy foil is also included.

  There is no restriction | limiting in particular also about the thickness of the copper foil base material which can be used for this invention, What is necessary is just to adjust to the thickness suitable for printed wiring boards suitably. For example, it can be set to about 5 to 100 μm. However, for the purpose of forming a fine pattern, it is 30 μm or less, preferably 20 μm or less, and typically about 5 to 20 μm.

  Although the copper foil base material used for this invention is not specifically limited, For example, you may use what does not perform a roughening process. Conventionally, the surface is generally roughened by special plating with irregularities on the order of μm, and the physical anchor effect provides adhesion to the resin. A smooth foil is considered to have good characteristics, and a roughened foil may work in a disadvantageous direction. Moreover, since the roughening process process is abbreviate | omitted if it does not perform a roughening process, there exists an effect of economical efficiency and productivity improvement.

(Coating layer)
A coating layer is formed on at least a part of the surface of the copper foil base material. There are no particular restrictions on the area to be covered, but it is generally the area where the circuit pattern of the printed wiring board is to be formed. The coating layer is made of Ni alone, Ni alloy containing at least one of Ni, Cu, Sn, V, Mn and Zn, or Cu alloy. Specifically, for example, Ni— It is comprised by Sn alloy, Ni-V alloy, Ni-Mn alloy, Ni-Zn alloy, Cu-Ni alloy, Cu-Zn alloy or Cu-Ni-Zn alloy, Cu-Sn alloy, etc. On the circuit pattern forming side surface of the copper foil of the laminate, it is necessary to form a metal film that is more heat resistant than copper so that it does not change color due to thermal history during resin curing or thermocompression bonding. Since the coating layer comprised by the above-mentioned Ni simple substance, Ni alloy, or Cu alloy is formed in the circuit pattern formation side surface of copper foil, it has favorable heat resistance. Moreover, since Cr is used as a component of the alloy without being present on the outermost surface, it also has good etching properties.

A specific configuration of the coating layer will be described below.
(1) Identification of coating layer The coating layer can be identified by the presence of each detection peak by sputtering with argon from the surface layer using a surface analyzer such as XPS or AES and performing chemical analysis in the depth direction. Moreover, the order of covering from the position of each detection peak can be confirmed.

(2) Amount of deposition On the other hand, since the coating layer is very thin, it is difficult to accurately evaluate the thickness with XPS and AES. Therefore, in the present invention, the thickness of the coating layer is evaluated by the weight of the coating metal per unit area.
In the coating layer, Ni alone or Ni alloy is present in an adhesion amount of 80 to 800 μg / dm ² , or Cu alloy is present in an amount of 300 to 1500 μg / dm ² . When the adhesion amount of Ni simple substance or Ni alloy is less than 80 μg / dm ² , sufficient heat resistance cannot be obtained, and when the adhesion amount of Ni simple substance or Ni alloy exceeds 800 μg / dm ² , the etching property tends to decrease significantly. is there. The adhesion amount of Ni simple substance or Ni alloy is preferably 160 to 700 μg / dm ² , more preferably 300 to 600 μg / dm ² . Moreover, when the adhesion amount of Cu alloy is less than 300 μg / dm ² , sufficient heat resistance cannot be obtained, and when it exceeds 1500 μg / dm ² , the etching property tends to be significantly lowered. The coating amount of the Cu alloy is preferably 400 to 1200 μg / dm ² , more preferably 450 to 1000 μg / dm ² .
Ni alone can have sufficient heat resistance, but when the coating layer is formed by sputtering, the use efficiency of the sputtering target is reduced due to the influence of the magnetism of Ni. desirable. In the Ni alloy, 3 to 50% by mass of any one of Cu, Sn, V, Mn, Zn and Cr is present. When any one of Cu, Sn, V, Mn, Zn, and Cr is less than 3% by mass, the use efficiency of the sputtering target decreases, and when it exceeds 50% by mass, the amount of Ni in the coating is reduced. Sufficient heat resistance cannot be obtained. In the Ni alloy, any one of Cu, Sn, V, Mn, Zn and Cr is preferably present in an amount of 5 to 40% by mass, more preferably 15 to 30% by mass. The Cu alloy is composed of Cu and at least one of Ni, Sn, V, Mn, Zn, and Cr. In the Cu alloy, one or two of Sn, Zn and Ni are present in an amount of 20 to 70% by mass. If any one or two of Sn, Zn and Ni is less than 20% by mass, the amount of Cu in the coating increases and sufficient heat resistance cannot be obtained. If any one or two of Sn, Zn, and Ni is more than 70% by mass, the amount of low melting point metal components such as Sn and Zn increases, so that it becomes difficult to produce a sputtering target. In the Cu alloy, one or two of Sn, Zn and Ni are preferably present in an amount of 25 to 60% by mass, more preferably 30 to 50% by mass.

  At a depth of 4.0 to 8.0 nm immediately below the outermost surface of the coating layer serving as an etching surface, it is desirable that there is almost no oxide film from the surface so that the copper foil surface does not change color due to thermal history. Therefore, the atomic concentration (%) of nickel in the depth direction (x: unit nm) obtained from the depth direction analysis from the surface by XPS of the coating layer is defined as f (x), and tin, vanadium, chromium, manganese, and The atomic concentration (%) of any one of zinc is g (x), the atomic concentration (%) of oxygen is h (x), the atomic concentration (%) of copper is i (x), and carbon atoms Assuming that the concentration (%) is j (x) and the total of other atomic concentrations is k (x), in the interval [4.0, 8.0], xh (x) dx / (∫f (x) It is desirable that dx + ∫g (x) dx + ∫h (x) dx + ∫i (x) dx + ∫j (x) dx + ∫k (x) dx) is 5% or less.

  In addition, when a heat treatment equivalent to lamination, a heat treatment equivalent to polyimide curing, or a heat treatment equivalent to an energization cycle is performed, the depth direction (x: unit nm) obtained from the depth direction analysis from the surface of the coating layer by XPS The atomic concentration (%) of nickel is f (x), the atomic concentration (%) of any one of tin, vanadium, chromium, manganese and zinc is g (x), and the atomic concentration (%) of oxygen is h (x), the atomic concentration (%) of copper is i (x), the atomic concentration (%) of carbon is j (x), and the total of other atomic concentrations is k (x). 0, 8.0], ∫h (x) dx / (∫f (x) dx + ∫g (x) dx + ∫h (x) dx + ∫i (x) dx + ∫j (x) dx + ∫k (x) dx) is preferably 5% or less.

  Furthermore, when the insulating substrate is bonded to the opposite surface of the coating layer of copper foil by lamination or polyimide curing, the depth direction obtained from the depth direction analysis from the surface of the coating layer by XPS (x: unit nm) The atomic concentration (%) of nickel is f (x), the atomic concentration (%) of any one of tin, vanadium, chromium, manganese and zinc is g (x), and the atomic concentration (%) of oxygen is If h (x), the atomic concentration (%) of copper is i (x), the atomic concentration (%) of carbon is j (x), and the total of other atomic concentrations is k (x), the interval [ 4.0, 8.0], ∫h (x) dx / (∫f (x) dx + ∫g (x) dx + ∫h (x) dx + ∫i (x) dx + ∫j (x ) dx + ∫k (x) dx) is preferably 5% or less.

(Method for producing copper foil according to the present invention)
The copper foil for printed wiring boards which concerns on this invention, and a laminated body using the same can be formed by sputtering method. That is, at least a part of the etching surface side of the copper foil base material or the laminate is made of Ni alone, Ni alloy containing any one of Ni, Cu, Sn, V, Mn and Zn, or Cu alloy. The coating layer can be manufactured by forming a coating layer with a thickness of 1.0 to 9.0 nm for Ni alone or a Ni alloy and a thickness of 3.0 to 16.0 nm for Cu alloy. When such an ultra-thin film is laminated by electroplating, the thickness varies, and when a thermal history is applied, the copper foil or laminate surface may be discolored.
The thickness here is not the thickness determined by the XPS or TEM described above, but the thickness derived from the film formation rate of sputtering. The deposition rate under a certain sputtering condition can be measured from the relationship between the sputtering time and the sputtering thickness by performing sputtering of 0.1 μm (100 nm) or more. Once the deposition rate under the sputtering conditions can be measured, the sputtering time is set according to the desired thickness. Sputtering may be performed continuously or batchwise, and the coating layer can be uniformly laminated with a thickness as defined in the present invention. Examples of the sputtering method include a direct current magnetron sputtering method.

(Manufacture of printed wiring boards)
A printed wiring board (PWB) can be manufactured according to a conventional method using the copper foil according to the present invention. Below, the example of manufacture of a printed wiring board is shown.

  First, a laminated body is manufactured by bonding a copper foil to an insulating substrate from the surface opposite to the coating layer. The insulating substrate on which the copper foil is laminated is not particularly limited as long as it has characteristics applicable to a printed wiring board. For example, paper base phenolic resin, paper base epoxy resin, synthetic fiber for rigid PWB Use cloth base epoxy resin, glass cloth / paper composite base epoxy resin, glass cloth / glass non-woven composite base epoxy resin, glass cloth base epoxy resin, etc., use polyester film, polyimide film, etc. for FPC I can do things.

  In the case of the rigid PWB, a prepreg is prepared by impregnating a base material such as a glass cloth with a resin and curing the resin to a semi-cured state. It can be carried out by superposing and heating and pressing the surfaces having the prepreg and the copper foil coating layer.

  In the case of a flexible printed wiring board (FPC), a surface having a polyimide film or polyester film and a copper foil coating layer can be bonded using an epoxy or acrylic adhesive (three-layer structure). In addition, as a method without using an adhesive (two-layer structure), a polyimide varnish (polyamic acid varnish), which is a polyimide precursor, is applied to a surface having a coating layer of copper foil, and imidized by heating. And a lamination method in which a thermoplastic polyimide is applied on a polyimide film, a surface having a copper foil coating layer is superimposed thereon, and heated and pressed. In the casting method, it is also effective to apply an anchor coating material such as thermoplastic polyimide in advance before applying the polyimide varnish.

  The effect of the copper foil according to the present invention is prominent when an FPC is produced by adopting a casting method. That is, when the copper foil and the resin are to be bonded without using an adhesive, the copper foil is particularly required to adhere to the resin, but the copper foil according to the present invention is bonded to the resin, particularly to the polyimide. It can be said that it is suitable for production of a laminate by a casting method because of its excellent properties.

  The laminate according to the present invention can be used for various printed wiring boards (PWB) and is not particularly limited. For example, from the viewpoint of the number of layers of the conductor pattern, the single-sided PWB, double-sided PWB, and multilayer PWB ( It is applicable to rigid PWB, flexible PWB (FPC), and rigid flex PWB from the viewpoint of the type of insulating substrate material. Moreover, the laminated body which concerns on this invention is not limited to the above copper clad laminated board which affixes copper foil to resin, What was formed on the resin by metallizing (metallized film) may be sufficient. . The metallized film is generally pre-treated by glow discharge treatment on an insulating resin substrate made mainly of polyimide, and after forming a tie coat layer and a seed layer by dry film formation such as sputtering or vacuum deposition, It is formed by electrodepositing a copper layer in an electrolytic cell.

  A method well-known to those skilled in the art can be used for the process of manufacturing a printed wiring board from a laminated body. For example, an etching resist is applied only to a necessary portion as each line pattern constituting a circuit on the surface of the copper foil covering layer of the laminate, and an unnecessary portion of the copper foil is removed by spraying an etching solution onto the copper foil surface. A circuit of a conductor composed of a pattern is formed, and then the etching resist is peeled and removed to expose the line pattern.

  EXAMPLES Examples of the present invention will be described below, but these are provided for better understanding of the present invention and are not intended to limit the present invention.

(Example 1: Examples 1-14)
As a copper foil base material of Examples 1 to 11, a rolled copper foil (Nikko Metal C1100) having a thickness of 8 μm was prepared. The surface roughness (Rz) of the rolled copper foil was 0.7 μm. Moreover, as a copper foil base material of Examples 12 to 14, a non-roughened electrolytic copper foil having a thickness of 8 μm was prepared. The surface roughness (Rz) of the electrolytic copper foil was 1.5 μm.

  Ni simple substance used for sputtering used the thing of purity 3N. Moreover, regarding formation of a coating layer, various alloys (Ni-V, Cu-Ni-Zn, Ni-Sn, Ni-Mn, and Ni-Zn) were produced in the following procedures. First, the above-mentioned simple substance and alloy elements were respectively added to electrolytic copper or nickel, an ingot was cast in a high-frequency melting furnace, and this was hot-rolled at 600 to 900 ° C. Furthermore, after homogenizing annealing at 500-850 degreeC for 3 hours, the surface oxide layer was removed and it used as a sputtering target.

On the etched surface side of this copper foil or laminate, the thin oxide films previously attached to both surfaces of the copper foil base material are removed by reverse sputtering under the following conditions, and Ni simple substance, Ni alloy, and Cu alloy target A coating layer was formed by sputtering. The thickness of the coating layer was changed by adjusting the film formation time.
-Equipment: Batch type sputtering equipment (ULVAC, Model MNS-6000)
・ Achieving vacuum: 1.0 × 10 ⁻⁵ Pa
・ Sputtering pressure: 0.2 Pa
・ Reverse sputtering power: 100W
·target:
Ni alloy layer = Ni-V, Ni-Mn, Ni-Cr, Ni-Zn, Ni-Cu and various alloys of Ni-Sn Cu alloy layer = Cu-Ni-Zn alloy, Cu-Zn alloy, Cu-Sn alloy・ Sputtering power: 50W
Film formation rate: About 0.2 μm of film was formed for each target for a fixed time, the thickness was measured with a three-dimensional measuring device, and the sputtering rate per unit time was calculated.
A polyimide film was bonded to the surface of the copper foil having the surface opposite to the coating layer subjected to the surface treatment (adhesion layer) described in Patent Document 2 by the following procedure.
(1) Using an applicator on a copper foil of 7 cm × 7 cm, Ube Industries-made U varnish-A (polyimide varnish) was applied to a dry body to a thickness of 25 μm.
(2) The resin-coated copper foil obtained in (1) is dried at 120 ° C. for 30 minutes in an air dryer.
(3) Imidization at 350 ° C. for 30 minutes in a high-temperature heating furnace with a nitrogen flow rate set to 10 L / min.

  As a heat treatment condition equivalent to lamination, a copper foil or a laminate having a coating layer on the etching surface side was heated at 300 ° C. for 10 minutes in an air atmosphere.

<Measurement of adhesion amount>
A film on the surface of a copper foil of 50 mm × 50 mm is dissolved in a mixed solution of HNO ₃ (2% by weight) and HCl (5% by weight), and the metal concentration in the solution is measured by an ICP emission spectrometer (SII Nanotechnology). The amount of metal per unit area (μg / dm ² ) was calculated by quantitative determination using SFC-3100). Note that, in the present invention, when Cu alloy is used as a target, the adhesion amount of Cu and other metals is the analysis value when a film is formed on a Ti foil under the same conditions.

<Measurement by XPS>
The operating conditions of XPS when creating the depth profile of the coating layer are shown below.
・ Device: XPS measuring device (ULVAC-PHI, Model 5600MC)
・ Achieving vacuum: 3.8 × 10 ⁻⁷ Pa
X-ray: Monochromatic AlKα or non-monochromatic MgKα, X-ray output 300 W, detection area 800 μmφ, angle between sample and detector 45 °
Ion beam: ion species Ar ⁺ , acceleration voltage 3 kV, sweep area 3 mm × 3 mm, sputtering rate 2.0 nm / min (SiO ₂ conversion)
Measurement was carried out after film formation by sputtering, and the coating layer was analyzed in a state where heat treatment (350 ° C. × 120 minutes) under conditions more severe than polyimide curing conditions (350 ° C. × 30 minutes) was applied. Moreover, the heat history generally applied at the time of lamination is about 300 ° C. × 1 minute, and the coating layer subjected to a heat treatment equivalent to a more severe laminate (atmospheric atmosphere 300 ° C. × 10 minutes) was analyzed. In addition, it is said that the heat treatment condition corresponding to a 10-year energization cycle or energization is about 150 ° C. × 168 hours in an air atmosphere, and the coating layer subjected to a heat treatment equivalent to a severer laminate was analyzed. .

<Etching evaluation>
The evaluation of the etching property related to the coating layer is carried out by adhering an insulating substrate to the surface opposite to the coating layer and forming a circuit pattern (line / space = 25 μm / 5 μm) by etching under the following conditions, The shape was observed with a scanning electron microscope (SEM) (JEOL-5410), and whether or not a circuit could be formed was determined according to the following criteria.
(Etching conditions)
・ Ferric chloride solution (37% by mass, 40 ° Baume)
・ Liquid temperature: 50 ℃
・ Spray pressure: 0.25 MPa
(Possibility of circuit formation)
×: Short circuit (etching failure due to the presence of a coating layer)
○: Circuit formation possible

<Discoloration resistance evaluation>
After the heat treatment at 300 ° C. for 10 minutes under the atmospheric pressure atmosphere on the surface of the copper foil or the coating layer of the laminate produced as described above, L ^* (brightness) using a color difference meter, The a ^* (red-green axis chromaticity) and b ^* (yellow-blue axis chromaticity) were measured and evaluated based on (JIS Z 8729) by the color difference ΔE ^* ab shown in Formula (1).
E ^* ab = [(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² ] ^1/2 (1)
The color difference is evaluated as follows based on the ΔE ^* ab value.
0-0.5: very slightly different 0.5-1.5: slightly different 1.5-3.0: appreciably different 3.0-6.0: markedly different 6.0-12 0: Extremely different 12.0 or more: Different color system

(Example 2: Comparative examples a and d to h)
Sputtering time was changed on both surfaces of the rolled copper foil base material used in Example 1 to form a coating layer having a thickness described below. Moreover, about the comparative example a, the coating layer was not formed. For the copper foil thus provided with the coating layer, a polyimide film is adhered to the surface opposite to the coating layer by the same procedure as in Example 1, and the circuit line pattern is formed from the coating layer side by etching. Formed.

(Example 3: Comparative example b)
A Ni layer was formed by sputtering on one surface of the rolled copper foil substrate used in Example 1, and then the Cr layer was formed by chromate treatment under the following conditions. A Ni layer was formed on the other surface by sputtering to form a coating layer.
(Chromate treatment)
-Plating bath: CrO ₃ (1 g / L), Zn (powder 0.4 g), Na ₃ SO ₄ (10 g / L)
Current density: 2.0 A / dm ²
・ Bath temperature: 55 ℃
・ Cr amount: 21 μg / dm ² (thickness: about 0.5 nm)
For the copper foil thus provided with the coating layers on both surfaces, a polyimide film was adhered to the surface opposite to the coating layer by the same procedure as in Example 1, and further, the circuit layer was etched from the coating layer side by etching. A line pattern was formed.

(Example 4: Comparative Example c)
One surface of the rolled copper foil substrate used in Example 1 was subjected to Ni plating treatment under the following conditions to form a Ni layer, and subsequently subjected to chromate treatment under the following conditions to form a chromate layer. A Ni layer was formed on the other surface by sputtering to form a coating layer.
(Ni plating)
・ Plating bath: Nickel sulfamate (110 g / L as Ni ²⁺ ), H ₃ BO ₃ (40 g / L)
・ Current density: 1.0 A / dm ²
・ Bath temperature: 55 ℃
Ni content: 220 μg / dm ² (thickness approximately 1.1 nm)
(Chromate treatment)
-Plating bath: CrO ₃ (1 g / L), Zn (powder 0.4 g), Na ₃ SO ₄ (10 g / L)
Current density: 2.0 A / dm ²
・ Bath temperature: 55 ℃
・ Cr amount: 21 μg / dm ² (thickness: about 0.5 nm)
Subsequently, a polyimide film was bonded to the copper foil provided with the coating layer by the same procedure as in Example 1.

Each measurement result of Examples 1-4 is shown to Tables 1-2.

  In each of Examples 1 to 14, the etching property and the discoloration resistance of the coating layer side surface were good.

Comparative Example a was a blank material whose copper foil surface was untreated, and the discoloration resistance of the coating layer side surface was poor.
In Comparative Examples b, d, and h, the adhesion amount of Ni, Ni alloy, or Cu alloy in the coating layer was excessive, and the etching property was poor.
In Comparative Examples c, e, f, and g, the adhesion amount of Ni, Ni alloy, or Cu alloy in the coating layer was insufficient, and discoloration resistance was poor.

  Moreover, the depth profile by XPS of the coating layer surface of the copper foil (after heat processing equivalent to a polyimide varnish hardening) which concerns on Example 1 and 2 to FIG. 1 and 2 is shown, respectively. FIG. 3 shows a photograph of the circuit formed by Comparative Example d.

Claims (20)

A copper foil for a printed wiring board comprising a copper foil substrate and a coating layer covering at least a part of one surface of the copper foil substrate,
The coating layer, Ni alone or Ni alloy coating weight 80~800μg / dm ^2, or adhesion amount 300~1500μg / dm ² of copper foil for printed wiring boards which are composed of Cu alloy.   The copper foil for printed wiring boards according to claim 1, wherein the Ni alloy is composed of Ni and at least one of Cu, Sn, V, Mn, Zn, and Cr. The copper foil for printed wiring boards according to claim 1 or 2, wherein in the coating layer, Ni alone or an Ni alloy is present in an adhesion amount of 160 to 700 µg / dm ² . The copper foil for printed wiring boards according to claim 3, wherein in the coating layer, Ni alone or an Ni alloy is present in an adhesion amount of 300 to 600 μg / dm ² .   The copper foil for printed wiring boards according to any one of claims 1 to 4, wherein any one of Cu, Sn, V, Mn, Zn, and Cr is present in the Ni alloy layer in an amount of 3 to 50 mass%.   The copper foil for printed wiring boards according to claim 1, wherein the Cu alloy is composed of Cu and at least one of Ni, Sn, V, Mn, Zn, and Cr. The copper foil for printed wiring boards according to claim 1 or 6, wherein in the coating layer, a Cu alloy is present in an adhesion amount of 400 to 1200 µg / dm ² . The copper foil for printed wiring boards according to claim 7, wherein in the coating layer, a Cu alloy is present in an adhesion amount of 450 to 1000 μg / dm ² .   The copper foil for printed wiring boards according to any one of claims 1, 6, 7 and 8, wherein one or two of Sn, Zn and Ni are present in the Cu alloy layer in an amount of 20 to 70 mass%.   The atomic concentration (%) of nickel in the depth direction (x: unit nm) obtained from the analysis of the depth direction from the surface by XPS of the coating layer is defined as f (x), and tin, vanadium, chromium, manganese, and zinc The atomic concentration (%) of any one of the above is g (x), the atomic concentration (%) of oxygen is h (x), the atomic concentration (%) of copper is i (x), and the atomic concentration of carbon (%) Is j (x), and the total of other atomic concentrations is k (x). In the interval [4.0, 8.0], ∫h (x) dx / (∫f (x) dx + (G) (x) dx + (h) x (x) dx + (i) x (x) dx + (j) dx + (k) (x) dx) satisfies 5% or less. Copper foil for printed wiring boards as described in 2.   The atomic concentration (%) of nickel in the depth direction (x: unit nm) obtained from the analysis of the depth direction from the surface by XPS of the coating layer when heat treatment equivalent to lamination or heat treatment equivalent to polyimide curing was performed F (x), atomic concentration (%) of any one of tin, vanadium, chromium, manganese and zinc is g (x), oxygen atomic concentration (%) is h (x), If the atomic concentration (%) is i (x), the carbon atomic concentration (%) is j (x), and the total of other atomic concentrations is k (x), the interval [4.0, 8.0] ∫h (x) dx / (∫f (x) dx + ∫g (x) dx + ∫h (x) dx + ∫i (x) dx + ∫j (x) dx + ∫k (x) The copper foil for printed wiring boards according to any one of claims 1 to 10, wherein dx) is 5% or less.   Heat treatment equivalent to lamination or heat treatment equivalent to polyimide curing is performed, and the atomic concentration (%) of nickel in the depth direction (x: unit nm) obtained from the depth direction analysis from the surface by XPS of the coating layer F (x), atomic concentration (%) of any one of tin, vanadium, chromium, manganese and zinc is g (x), oxygen atomic concentration (%) is h (x), If the atomic concentration (%) is i (x), the carbon atomic concentration (%) is j (x), and the total of other atomic concentrations is k (x), the interval [4.0, 8.0] ∫h (x) dx / (∫f (x) dx + ∫g (x) dx + ∫h (x) dx + ∫i (x) dx + ∫j (x) dx + ∫k (x) The copper foil for printed wiring boards according to any one of claims 1 to 11, wherein dx) is 5% or less.   Obtained from depth analysis from the surface of the coating layer by XPS with respect to the copper foil for printed wiring board in which the insulating substrate is formed on the surface opposite to the surface on which the coating layer is formed by laminating or polyimide curing The atomic concentration (%) of nickel in the depth direction (x: unit nm) is f (x), and the atomic concentration (%) of any one of tin, vanadium, chromium, manganese and zinc is g (x ), The atomic concentration (%) of oxygen is h (x), the atomic concentration (%) of copper is i (x), the atomic concentration (%) of carbon is j (x), and other atomic concentrations If the sum is k (x), in the interval [4.0, 8.0],］ h (x) dx / (∫f (x) dx + ∫g (x) dx + ∫h (x) dx + The copper foil for printed wiring boards according to any one of claims 1 to 12, wherein i (x) dx + ∫j (x) dx + ∫k (x) dx) satisfies 5% or less.   The said copper foil base material is a rolled copper foil or an electrolytic copper foil, The copper foil for printed wiring boards in any one of Claims 1-13.   A printed wiring board is a flexible printed wiring board, Copper foil for printed wiring boards in any one of Claims 1-14.   By sputtering, at least part of one surface of the copper foil base material is composed of Ni alone, Ni alloy containing any one of Ni, Cu, Sn, V, Mn and Zn, or Cu alloy. A method for producing a copper foil for printed wiring board, comprising a step of forming a coating layer of Ni or Ni alloy in a thickness of 1.0 to 9.0 nm and a Cu alloy in a thickness of 3.0 to 16.0 nm. .   The laminated body of the copper foil and resin substrate in any one of Claims 1-15. A laminate of a copper layer and a resin substrate,
The laminated body provided with the coating layer in any one of Claims 1-15 which coat | covers at least one part of the surface of the said copper layer.   The laminate according to claim 17 or 18, wherein the resin substrate is a polyimide substrate.   The printed wiring board which used the laminated body in any one of Claims 17-19 as a material.