JP2022100020A - Surface-treated copper foil, copper-clad laminate, and printed wiring board - Google Patents

Abstract

To provide a surface-treated copper foil with which it is possible to reduce peeling from a substrate and to form a fine-pitched circuit pattern.SOLUTION: The surface-treated copper foil in the present invention has a copper foil, a first surface treatment layer formed on one surface of the copper foil, and a second surface treatment layer formed on the other surface of the copper foil. The ratio of the amount of Ni adhering to the first surface treatment layer to the amount of Ni adhering to the second surface treatment layer is 0.01-2.0. The surface-treated copper foil has a tensile strength of 235-290 MPa. The copper foil is made of at least 99.0 mass% of Cu and the balance being unavoidable impurities.SELECTED DRAWING: Figure 1

Description

The present invention relates to a surface-treated copper foil, a copper-clad laminate, and a printed wiring board.

In recent years, with the increasing needs for miniaturization and high performance of electronic devices, fine pitching (miniaturization) of circuit patterns (also referred to as "conductor patterns") for printed wiring boards mounted on electronic devices is required. ing.

In response to the above-mentioned demand for fine pitch, for example, Patent Document 1 states that "a copper foil, a first surface-treated layer formed on one surface of the copper foil, and a copper foil formed on the other surface of the copper foil". The surface-treated copper foil having the second surface-treated layer and the ratio of the Ni adhesion amount of the first surface-treated layer to the Ni adhesion amount of the second surface-treated layer is 0.01 to 2, is disclosed. It is described that the surface-treated copper foil can form a circuit pattern having a high etching factor suitable for fine pitching.

Japanese Unexamined Patent Publication No. 2019-81913

By the way, in the printed wiring board in which the circuit pattern is made fine pitch as described above, since the circuit pattern is fine pitch, the formed circuit is peeled off from the base material as compared with the circuit before making fine pitch. It turns out that it can be easier. In particular, a flexible printed wiring board (hereinafter, also referred to as “FPC”) having flexibility may be more easily peeled off because the printed wiring board is deformed at the time of its manufacture or use. Therefore, in the printed wiring board, it is necessary to improve the peeling resistance as well as to make the circuit pattern finer pitch.

Therefore, the present invention has been made to solve the above-mentioned problems, and is a surface-treated copper foil and a copper-clad laminate capable of reducing peeling from a substrate and forming a circuit pattern having a fine pitch. The purpose is to provide a board.
Another object of the present invention is to provide a printed wiring board having a circuit pattern having a fine pitch by reducing peeling from a substrate.

As a result of diligent research to solve the above problems, the present inventors made a circuit board formed by increasing the strength of the copper foil in a printed wiring board having a fine pitch circuit pattern. We have found that it is possible to reduce the peeling of the material, and have arrived at the present invention.
That is, the present invention is as follows.

In one embodiment, the surface-treated copper foil of the present invention comprises a copper foil, a first surface-treated layer formed on one surface of the copper foil, and a second surface-treated surface formed on the other surface of the copper foil. It has a layer, and the ratio of the Ni adhesion amount of the first surface-treated layer to the Ni adhesion amount of the second surface-treated layer is 0.01 to 2.0, and the tensile strength of the surface-treated copper foil is 235. ~ 290 MPa,
The copper foil is composed of 99.0% by mass or more of Cu and the balance of unavoidable impurities.

In one embodiment, the copper-clad laminate of the present invention comprises the above-mentioned surface-treated copper foil and a base material adhered to the first surface-treated layer of the surface-treated copper foil.

In one embodiment, the printed wiring board of the present invention comprises a circuit pattern formed by etching the surface-treated copper foil of the copper-clad laminate.

According to the present invention, it is possible to provide a surface-treated copper foil and a copper-clad laminate capable of forming a circuit pattern having a fine pitch by reducing peeling from a substrate.
Further, according to the present invention, it is possible to provide a printed wiring board having a circuit pattern having a fine pitch by reducing peeling from a substrate.

It is sectional drawing which shows the surface-treated copper foil of this embodiment in the state which adhered to the base material.

Hereinafter, embodiments of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail, but the present invention is not limited to the present embodiment.
<Surface-treated copper foil>
FIG. 1 is a cross-sectional view (cross-sectional view of a copper-clad laminate 10) showing a state in which the surface-treated copper foil of the present embodiment is adhered to a base material.
The surface-treated copper foil 1 of the present embodiment has the copper foil 2, the first surface-treated layer 3 formed on one surface of the copper foil 2, and the second surface-treated surface-treated on the other surface of the copper foil 2. It has a layer 4. Further, the copper-clad laminate 10 has a surface-treated copper foil 1 and a base material 11 adhered to the first surface-treated layer 3 of the surface-treated copper foil 1.
The surface-treated copper foil 1 of the present embodiment is not particularly limited, but can be used as a copper foil for a printed wiring board mounted on an electronic device or the like, particularly a flexible printed wiring board.

The first surface treatment layer 3 and the second surface treatment layer 4 contain at least Ni as an adhering element. In the surface-treated copper foil 1, the ratio of the Ni adhesion amount of the first surface-treated layer 3 to the Ni adhesion amount of the second surface-treated layer 4 is 0.01 to 2.0, preferably 0.8 to 1.5. be. Since Ni is a component that is difficult to dissolve in the etching solution, by setting the ratio of the amount of Ni adhered to the above range, the first surface treatment layer that becomes the bottom side of the circuit pattern when etching the copper-clad laminate 10. It is possible to promote the dissolution of 3 and delay the dissolution of the second surface treatment layer 4, which is the top side of the circuit pattern. Therefore, it is possible to obtain a circuit pattern in which the difference between the top width and the bottom width is small and the etching factor is high.

The amount of Ni attached to the first surface treatment layer 3 is not particularly limited as long as the ratio of the amount of attached Ni is within the above range, but is preferably 20 to 200 μg / dm ² , and more preferably 20 to 100 μg / dm ² . .. By setting the amount of Ni adhered to the first surface treatment layer 3 within the above range, the etching factor of the circuit pattern can be stably increased.

The first surface treatment layer 3 can contain elements such as Zn, Co, and Cr in addition to Ni as an adhering element. The amount of Zn adhered to the first surface treatment layer 3 is not particularly limited because it depends on the type of the first surface treatment layer 3, but when Zn is contained in the first surface treatment layer 3, it is preferably 20 to 1000 μg / dm. ² , more preferably 400 to 500 μg / dm ² . By setting the amount of Zn adhered to the first surface treatment layer 3 within the above range, the etching factor of the circuit pattern can be stably increased.

The amount of Co adhered to the first surface treatment layer 3 is not particularly limited because it depends on the type of the first surface treatment layer 3, but is preferably 1500 μg / dm ² or less, more preferably 0.1 to 500 μg / dm ² , and further. It is preferably 0.5 to 100 μg / dm ² . By setting the amount of Co adhered to the first surface treatment layer 3 within the above range, the etching factor of the circuit pattern can be stably increased. Further, since Co is a magnetic metal, the amount of Co adhered to the first surface treatment layer 3 is suppressed to 100 μg / dm ² or less, preferably 0.5 to 100 μg / dm ² , so that the printed wiring has excellent high frequency characteristics. A surface-treated copper foil 1 capable of producing a plate can be obtained.

The amount of Cr adhered to the first surface treatment layer 3 is not particularly limited because it depends on the type of the first surface treatment layer 3, but is 500 μg / dm ² or less, more preferably 0.5 to 300 μg / dm ² , and even more preferably. It is 1 to 100 μg / dm ² . By setting the amount of Cr adhered to the first surface treatment layer 3 within the above range, the etching factor of the circuit pattern can be stably increased.

The Rzjis of the first surface treatment layer 3 is not particularly limited, but is preferably 0.3 to 1.5, and more preferably 0.5 to 0.8. By setting the Rzjis of the first surface treatment layer 3 within the above range, the adhesiveness with the base material 11 can be improved. Here, "Rzjis" in the present specification means a ten-point average roughness defined in JIS B 0601: 2001.

The type of the first surface treatment layer 3 is not particularly limited as long as the ratio of the Ni adhesion amount is within the above range, and various surface treatment layers known in the art can be used. Examples of the surface treatment layer include a roughening treatment layer, a heat resistant layer, a rust preventive layer, a chromate treatment layer, a silane coupling treatment layer and the like. These layers can be used alone or in combination of two or more. Among them, the first surface-treated layer 3 preferably has a roughened-treated layer from the viewpoint of adhesiveness to the base material 11. Here, the "roughened layer" in the present specification is a layer formed by the roughening treatment, and includes a layer of roughened particles. Further, in the roughening treatment, normal copper plating or the like may be performed as a pretreatment, or normal copper plating or the like may be performed as a finishing treatment to prevent the roughened particles from falling off. The "roughened layer" in the book includes layers formed by these pretreatments and finishing treatments.

The roughened particles are not particularly limited, but are formed from any simple substance selected from the group consisting of copper, nickel, cobalt, phosphorus, tungsten, arsenic, molybdenum, chromium and zinc, or an alloy containing any one or more thereof. can do. Further, after forming the roughened particles, it is also possible to further perform a roughening treatment for providing secondary particles or tertiary particles with a simple substance or an alloy of nickel, cobalt, copper, zinc or the like.

The heat-resistant layer and the rust-preventive layer are not particularly limited, and can be formed from a material known in the art. Since the heat-resistant layer may also function as a rust-preventive layer, one layer having both the functions of the heat-resistant layer and the rust-preventive layer may be formed as the heat-resistant layer and the rust-preventive layer. The heat-resistant layer and / or rust-preventive layer includes nickel, zinc, tin, cobalt, molybdenum, copper, tungsten, phosphorus, arsenic, chromium, vanadium, titanium, aluminum, gold, silver, platinum group elements, iron, and tantalum. It can be a layer containing one or more elements selected from the above (which may be in any form such as metal, alloy, oxide, nitride, sulfide, etc.). Examples of the heat-resistant layer and / or the rust-preventive layer include a layer containing a nickel-zinc alloy.

The chromate-treated layer is not particularly limited and can be formed from a material known in the art. Here, the term "chromate-treated layer" as used herein means a layer formed of a liquid containing chromic anhydride, chromic acid, chromic acid, chromate or dichromate. The chromate-treated layer can be any element (metal, alloy, oxide, nitride, sulfide, etc.) such as cobalt, iron, nickel, molybdenum, zinc, tantalum, copper, aluminum, phosphorus, tungsten, tin, arsenic, and titanium. It can be a layer containing). Examples of the chromate-treated layer include a chromate-treated layer treated with an aqueous solution of chromic acid anhydride or potassium dichromate, and a chromate-treated layer treated with a treatment liquid containing chromic acid anhydride or potassium dichromate and zinc.

The silane coupling treatment layer is not particularly limited and can be formed from a material known in the art. Here, the term "silane coupling-treated layer" as used herein means a layer formed of a silane coupling agent. The silane coupling agent is not particularly limited, and those known in the art can be used. Examples of the silane coupling agent include an amino-based silane coupling agent, an epoxy-based silane coupling agent, and a mercapto-based silane coupling agent. These can be used alone or in combination of two or more.

The type of the second surface treatment layer 4 is not particularly limited as long as the ratio of the Ni adhesion amount is within the above range, and various surface treatment layers known in the art are used as in the first surface treatment layer 3. be able to. Further, the type of the second surface treatment layer 4 may be the same as or different from that of the first surface treatment layer 3.

The amount of Ni attached to the second surface treatment layer 4 is not particularly limited as long as the ratio of the amount of attached Ni is within the above range, but is preferably 0.1 to 500 μg / dm ² , more preferably 0.5 to 200 μg /. It is dm ² , more preferably 1.0 to 100 μg / dm ² . By setting the amount of Ni adhered to the second surface treatment layer 4 within the above range, the etching factor of the circuit pattern can be stably increased.

The second surface treatment layer 4 can contain elements such as Zn and Cr as adhesion elements in addition to Ni. The amount of Zn adhered to the second surface treatment layer 4 is not particularly limited because it depends on the type of the second surface treatment layer 4, but when Zn is contained in the second surface treatment layer 4, it is preferably 10 to 1000 μg / dm. ² , more preferably 50 to 500 μg / dm ² , still more preferably 100 to 300 μg / dm ² . By setting the amount of Zn adhered to the second surface treatment layer 4 within the above range, the etching factor of the circuit pattern can be stably increased.

The amount of Cr adhered to the second surface treatment layer 4 is not particularly limited because it depends on the type of the second surface treatment layer 4, but when Cr is contained in the second surface treatment layer 4, it preferably exceeds 0 μg / dm ² . It is 500 μg / dm ² or less, more preferably 0.1 to 100 μg / dm ² , and even more preferably 1 to 50 μg / dm ² . By setting the amount of Cr adhered to the second surface treatment layer 4 within the above range, the etching factor of the circuit pattern can be stably increased.

The copper foil 2 is composed of 99.0% by mass or more of Cu and unavoidable impurities in the balance, and has a tensile strength of 235 to 290 MPa when used as a surface-treated copper foil. When the copper foil 2 has such a configuration, it is possible to reduce peeling of the formed circuit from the base material in the printed wiring board having a fine pitch circuit pattern. More specifically, when improving the durability of the circuit pattern (preventing peeling), it is common to consider improving the adhesiveness with the resin by adjusting the plating composition and the surface roughness. However, in the present embodiment, the copper foil 2 has a composition as described above, and the tensile strength when the surface-treated copper foil is formed is set within a predetermined range, so that the printed wiring board has a fine pitch. Also, the peeling of the circuit pattern can be reduced.

More specifically, in the present embodiment, the method for improving the tensile strength of the copper foil (and thus the surface-treated copper foil) is not limited, but the crystal grains after recrystallization of the copper foil are refined. Can be mentioned.
In the case of a pure copper-based composition such as copper foil 2, it is difficult to refine the crystal grains, but by performing recrystallization annealing at the initial stage of cold rolling and not performing recrystallization annealing thereafter, it is cold. A large amount of processing strain can be introduced by rolling to generate dynamic recrystallization, and finer crystal grains can be realized.

Further, as an additive element for refining the crystal grains, the copper foil has a total of 0 or more additive elements selected from the group of P, Ti, Sn, Ni, Be, Zn, In and Mg with respect to the above composition. When it is contained in an amount of .002 to 0.825% by mass, finer crystal grains can be more easily realized. Since these additive elements increase the dislocation density during cold rolling, miniaturization of crystal grains can be realized more easily.

As a method for refining the crystal grains after recrystallization of the copper foil, in addition to the method of adding an additive element, a method of polymerized rolling and a method of using a pulse current when electrolyzing with an electrolytic copper foil. Alternatively, a method of adding an appropriate amount of thiourea, nikawa, or the like to the electrolytic solution using an electrolytic copper foil can be mentioned.

The copper foil of the present embodiment may be composed of tough pitch copper (TPC) standardized for JIS-H3100 (C1100) or oxygen-free copper (OFC) of JIS-H3100 (C1011). Further, the composition may be such that the above-mentioned additive element is contained in the above-mentioned TPC or OFC.

In the present embodiment, the average crystal grain size of the copper foil is preferably 0.5 to 4.0 μm. When the average crystal grain size is less than 0.5 μm, the tensile strength can be higher than the desired value, specifically, the strength becomes too high and the bending rigidity becomes high, and in particular, the surface-treated copper foil is flexible. When used for printed wiring boards, the springback tends to be large and not suitable for flexible printed wiring boards. If the average crystal grain size exceeds 4.0 μm, the crystal grains cannot be refined and the tensile strength can be smaller than the desired value. Specifically, it becomes difficult to sufficiently increase the strength. , Etching factor and circuit linearity are deteriorated, and etching property is lowered. The average crystal grain size is measured by observing 10 or more fields of view on the foil surface with a field of view of 15 μm × 15 μm in order to avoid errors. The foil surface can be observed using SIM (Scanning Ion Microscope) or SEM (Scanning Electron Microscope), and the average crystal grain size can be determined based on the cutting method described in JIS H 0501. However, twins are measured as separate crystal grains.

In the present embodiment, the tensile strength of the surface-treated copper foil is 235 to 290 MPa. As described above, the tensile strength is improved by refining the crystal grains. Circuit peeling caused by an external force applied during the manufacturing process of a printed wiring board and mounting on a product involves deformation of the circuit. In the case of peeling accompanied by such deformation, the range in which the external force is concentrated on the interface changes depending on the ease of deformation of the peeling target. When it is easily deformed, the external force is concentrated in a narrow range on the interface, while when it is difficult to deform, the external force is dispersed in a wide range on the interface. That is, by adopting a surface-treated copper foil having high strength and being hard to be deformed as a circuit, external force can be dispersed in a wide range on the interface and circuit peeling can be suppressed. In particular, in a fine pitch circuit, the present inventors have found that the narrowness of the circuit width makes it easy for an external force to concentrate, and it is more important to disperse the external force due to the difficulty in deforming the object to be peeled off. When the tensile strength of the surface-treated copper foil is less than 235 MPa, the external force applied on the interface is not sufficiently dispersed and the circuit peeling cannot be suppressed. Further, when the tensile strength of the surface-treated copper foil exceeds 290 MPa, circuit peeling can be sufficiently suppressed, but the strength becomes too high and the bending rigidity becomes large, especially when the surface-treated copper foil is used for a flexible printed wiring board. Tends to be unsuitable for flexible printed wiring board applications due to the large springback. Tensile strength was measured by a tensile test based on IPC-TM-650, with a test piece width of 12.7 mm, room temperature (15 to 35 ° C), a tensile speed of 50.8 mm / min, and a gauge length of 50 mm, in the rolling direction of the copper foil. A tensile test was performed in a direction parallel to (or MD direction).

In the present embodiment, the surface-treated copper foil may have a tensile strength of 235 to 290 MPa after heat treatment of the surface-treated copper foil at 300 ° C. for 30 minutes (in other words, the surface-treated copper foil having a tensile strength of 235 to 290 MPa is 300. It may be the one after heat treatment at ° C. for 30 minutes). The surface-treated copper foil in the present embodiment can be used for a printed wiring board, and the copper-clad laminated board in which the surface-treated copper foil and the resin as a base material are laminated is heat-treated to cure the resin at 200 to 400 ° C. Therefore, there is a possibility that the crystal grains will be coarsened by recrystallization.
On the other hand, the surface-treated copper foil in the present embodiment may have a tensile strength of 235 to 290 MPa after the surface-treated copper foil is heat-treated at 300 ° C. for 30 minutes, but this physical property is the surface before laminating with the resin. It is specified by paying attention to the state when the treated copper foil is subjected to the above heat treatment. This heat treatment at 300 ° C. for 30 minutes imitates the temperature condition for curing and heat-treating the resin when laminating the copper-clad laminate.

The thickness of the copper foil is not particularly limited, but may be, for example, 1 to 1000 μm, 1 to 500 μm, 1 to 300 μm, 3 to 100 μm, 5 to 70 μm, 6 to 35 μm, or 9 to 18 μm. ..

The copper foil in this embodiment can be manufactured, for example, as follows. First, the above additive is added to a copper ingot, melted and cast, then hot rolled, cold rolled and annealed, and the final cold rolling described above is carried out to produce a foil.

Further, the surface-treated copper foil 1 of the present embodiment can be manufactured by using the above-mentioned copper foil 2 according to a method known in the art. Here, the ratio of the Ni adhesion amount and the Ni adhesion amount of the first surface treatment layer 3 and the second surface treatment layer 4 can be controlled by changing, for example, the type and thickness of the surface treatment layer to be formed. Further, the Rzjis of the first surface treatment layer 3 can be controlled by adjusting the formation conditions of the first surface treatment layer 3 and the like.

<Copper-clad laminate>
The copper-clad laminate 10 of the present embodiment includes the above-mentioned surface-treated copper foil 1 and a base material 11 adhered to the first surface-treated layer 3 of the surface-treated copper foil 1.
The base material 11 is not particularly limited, and those known in the art can be used. Examples of the base material 11 include paper base material phenol resin, paper base material epoxy resin, synthetic fiber cloth base material epoxy resin, glass cloth / paper composite base material epoxy resin, glass cloth / glass non-woven material composite base material epoxy resin, and glass. Examples thereof include a cloth base material epoxy resin, a polyester (polyethylene terephthalate, polyethylene naphthalate, etc.) film, a polyimide film, a liquid crystal polymer, a fluororesin, and the like, and it is preferable that the cloth base material has an insulating property.

The method for manufacturing the copper-clad laminate 10 is not particularly limited, and the copper-clad laminate 10 can be manufactured by adhering the surface-treated copper foil 1 and the base material 11 according to a method known in the art. For example, the surface-treated copper foil 1 and the base material 11 may be laminated and thermocompression bonded.

When the copper-clad laminate of the present embodiment is for a flexible printed wiring board, a polyethylene terephthalate, polyimide, polyethylene naphthalate, or liquid crystal polymer film can be used as the base material 11, and the base material 11 and the surface thereof can be used. As a method of laminating with the treated copper foil 1, a material to be a base material 11 may be applied to the surface of the surface-treated copper foil 1 and a heat film may be formed. Further, a resin film may be used as the base material 11, and the following adhesive may be used between the resin film and the surface-treated copper foil 1, and the resin film is thermally pressure-bonded to the surface-treated copper foil 1 without using an adhesive. You may. However, it is preferable to use an adhesive from the viewpoint that extra heat is not applied to the resin film. When a film is used as the base material 11, this film may be laminated on the surface-treated copper foil 1 via an adhesive layer. In this case, it is preferable to use an adhesive having the same composition as the film. For example, when a polyimide film is used as the base material 11, it is preferable to use a polyimide adhesive as the adhesive layer. The polyimide-based adhesive referred to here refers to an adhesive containing an imide bond, and also includes polyetherimide and the like.

<Printed wiring board>
The printed wiring board of the present embodiment includes a circuit pattern formed by etching the surface-treated copper foil 1 of the copper-clad laminated board 10. The method for manufacturing the printed wiring board is not particularly limited, and the printed wiring board can be manufactured by a known method, and a circuit can be formed on the copper-clad laminate 10 by using a photolithography technique. Further, a flexible printed wiring board (flexible wiring board) can also be obtained by plating the circuit as needed and laminating a coverlay film.

Although the embodiment of the present invention has been described above, the surface-treated copper foil, the copper-clad laminate, and the printed wiring board of the present invention are not limited to the above examples, and can be appropriately modified.

Hereinafter, the present embodiment will be described in more detail by way of examples, but the present embodiment is not limited to these examples.

It was examined whether it is possible to manufacture a surface-treated copper foil and bond the surface-treated copper foil to a substrate to obtain a copper-clad laminate, reduce peeling from the substrate, and form a circuit pattern with a fine pitch. ..

The surface-treated copper foils of each Example and each Comparative Example were obtained as follows.
<Example: Surface-treated copper foil 1>
Ingots were made using electrolytic copper in a non-oxidizing atmosphere. The proportion of copper contained in the ingot was 99.99% by mass. This ingot was homogenized and annealed at 900 ° C. or higher, then hot-rolled, and cold-rolled and annealed. After the final annealing, the final cold rolling was performed to obtain a foil having a final thickness of 12 μm.
Next, a roughening-treated layer, a heat-resistant layer and a chromate-treated layer are sequentially formed on one surface of the copper foil sample as a first surface-treated layer, and a heat-resistant layer and chromate as a second surface-treated layer on the other surface. A surface-treated copper foil was obtained by sequentially forming treated layers. The conditions for forming each layer are as follows.
Each physical property of the surface-treated copper foil 1 was evaluated by a method described later, and the results are shown in Table 1.
-Roughening treatment layer of the first surface treatment layer A roughening treatment layer was formed by electroplating.
Plating solution composition: 10 to 20 g / L Cu, 50 to 100 g / L sulfuric acid plating solution temperature: 25 to 50 ° C.
Electroplating conditions: Current is applied in two stages First stage: Current density 45.0 A / dm ² , Time 1.4 seconds, Coulomb amount 60.8 As / dm ²
Second stage: current density 4.1 A / dm ² , time 2.8 seconds, coulomb amount 11.8 As / dm ²
-The heat-resistant layer of the first surface treatment layer The heat-resistant layer was formed by electroplating.
Plating solution composition: 1 to 30 g / L Ni, 1 to 30 g / L Zn
Plating solution pH: 2-5
Plating liquid temperature: 30 to 50 ° C
Electroplating conditions: current density 2.1 A / dm ² , time 0.7 seconds, coulomb amount 1.4 As / dm ²
-Chromate-treated layer of the first surface-treated layer A chromate-treated layer was formed by electroplating.
Plating solution composition: 1 to 10 g / L K ₂ Cr ₂ O ₂ , 0.01 to 10 g / L Zn
Plating solution pH: 2-5
Plating liquid temperature: 30 to 50 ° C
Electroplating conditions: current density 2.1 A / dm ² , time 1.4 seconds, coulomb amount 2.9 As / dm ²
-The heat-resistant layer of the second surface treatment layer The heat-resistant layer was formed by electroplating.
Plating solution composition: 1 to 30 g / L Ni, 1 to 30 g / L Zn
Plating solution pH: 2-5
Plating liquid temperature: 30 to 50 ° C
Electroplating conditions: current density 2.1 A / dm ² , time 0.7 seconds, coulomb amount 1.4 As / dm ²
-Chromate-treated layer of the second surface-treated layer A chromate-treated layer was formed by immersion chromate treatment.
Chromate solution composition: 1 to 10 g / L K ₂ Cr ₂ O ₂ , 0.01 to 10 g / L Zn
Chromate solution pH: 2-5
Chromate liquid temperature: 30-50 ° C

<Comparative example: Surface-treated copper foil 2>
The surface-treated copper foil 2 is a copper foil having a reduced tensile strength of the surface-treated copper foil 1.
Each physical property of the surface-treated copper foil 2 was evaluated by the method described later, and the results are shown in Table 1.

The following base materials were adhered to the above surface-treated copper foils 1 and 2.
<Base material>
As the base material, a FR-4 base material (a type of glass cloth base material epoxy resin) was used.

Using the above surface-treated copper foil and the base material, a copper-clad laminate was obtained as described below.
<Example 1>
A base material was adhered to the surface of the first surface-treated layer of the surface-treated copper foil 1 to obtain a copper-clad laminate 1. Specifically, a base material was laminated on the surface of the first surface treatment layer of the copper foil, and heat-treated at 300 ° C. for 30 minutes with a heating press (4 MPa) to bond them together to obtain a copper-clad laminate 1.

<Comparative Example 1>
A copper-clad laminate 2 was obtained in the same manner as in Example 1 except that the surface-treated copper foil 1 was changed to the surface-treated copper foil 2.
The peel strength of the copper-clad laminates 1 and 2 described later was evaluated, and the results are shown in Table 2.

Each physical property and each evaluation were performed by the following methods.

<Tensile strength of surface-treated copper foil>
The above surface-treated copper foil was heat-treated at 300 ° C. for 30 minutes to obtain a surface-treated copper foil sample. The tensile strength of each surface-treated copper foil sample was measured under the above conditions by a tensile test based on IPC-TM-650.

<Measurement of adhesion amount of each element in the first surface treatment layer and the second surface treatment layer>
The amount of Ni, Zn and Co adhered is quantitatively analyzed by the atomic absorption spectrophotometer (model: AA240FS) manufactured by VARIAN by dissolving each surface treatment layer in nitric acid having a concentration of 20% by mass. Measured by The amount of Cr adhered was measured by dissolving each surface-treated layer in hydrochloric acid having a concentration of 7% by mass and performing quantitative analysis by the atomic absorption method in the same manner as described above.

<Peel strength>
The peel strength (easiness of peeling) of the copper-clad laminates 1 and 2 was measured according to JIS C 6471 8.1. As a test piece for measurement, a circuit having a width of 10 mm was prepared on a copper-clad laminate using a copper chloride circuit etching solution. In the measurement, the copper foil was peeled off from the substrate and continuously pulled in the 90 ° direction, and the lowest value within the range where the load was stable with a measurement length of 10 mm or more was defined as the peel strength.
When the peel strength is 0.80 kgf / cm or more, it can be evaluated that the circuit pattern is hard to peel off.

According to the present invention, it is possible to provide a surface-treated copper foil and a copper-clad laminate capable of forming a circuit pattern having a fine pitch by reducing peeling from a substrate.
Further, according to the present invention, it is possible to provide a printed wiring board having a circuit pattern having a fine pitch by reducing peeling from a substrate.

1: Surface-treated copper foil 2: Copper foil 3: First surface-treated layer 4: Second surface-treated layer 10: Copper-clad laminate 11: Base material

Claims (11)

Surface-treated copper foil
The surface-treated copper foil has a copper foil, a first surface-treated layer formed on one surface of the copper foil, and a second surface-treated layer formed on the other surface of the copper foil. The ratio of the Ni adhesion amount of the first surface treatment layer to the Ni adhesion amount of the second surface treatment layer is 0.01 to 2.0, and the tensile strength of the surface-treated copper foil is 235 to 290 MPa.
The copper foil is a surface-treated copper foil composed of 99.0% by mass or more of Cu and unavoidable impurities in the balance. The surface-treated copper foil according to claim 1, wherein the ratio of the Ni adhesion amount is 0.8 to 1.5. The surface-treated copper foil according to claim 1 or 2, wherein the Ni adhesion amount of the first surface-treated layer is 20 to 200 μg / dm ² . The surface-treated copper foil according to any one of claims 1 to 3, wherein the amount of Zn adhered to the first surface-treated layer is 20 to 1000 μg / dm ² . The surface-treated copper foil according to any one of claims 1 to 4, wherein the Rzjis of the first surface-treated layer is 0.3 to 1.5. The surface-treated copper foil according to any one of claims 1 to 5, wherein the copper foil is made of tough pitch copper specified in JIS-H3100 (C1100) or oxygen-free copper of JIS-H3100 (C1011). The copper foil further contains 0.002 to 0.825% by mass of one or more additive elements selected from the group of P, Ti, Sn, Ni, Be, Zn, In and Mg in total. The surface-treated copper foil according to any one of claims 1 to 6. The surface-treated copper foil according to any one of claims 1 to 7, wherein the surface-treated copper foil having a tensile strength of 235 to 290 MPa is the surface-treated copper foil after being heat-treated at 300 ° C. for 30 minutes. The surface-treated copper foil according to any one of claims 1 to 8, wherein the first surface-treated layer is adhered to a base material. A copper-clad laminate comprising the surface-treated copper foil according to any one of claims 1 to 9 and a base material adhered to the first surface-treated layer of the surface-treated copper foil. A printed wiring board comprising a circuit pattern formed by etching the surface-treated copper foil of the copper-clad laminate according to claim 10.

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