JP2014139347A - Method of treating surface of copper foil for printed circuit, copper foil produced by the same and plating apparatus for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of treating the surface of copper foil for printed circuits with adhesion to a resin film, heat resistance and acid resistance improved and copper foil obtained by the method.SOLUTION: Copper foil for printed circuits is surface-treated by a surface treatment method including steps 100 and 101 of forming a copper nodule layer on the surface of copper foil of a surface roughness (Rz) of 2.0 μm or smaller and a number of times of bending of 60 or greater and a step 102 of plating cobalt (Co) or a cobalt (Co) alloy on the copper nodule layer to form a barrier layer and has an adhesion strength to a polyimide (PI) film of 1.0 kgf/cm or higher. The plating amount of cobalt is preferably 0.5-50 mg/mor greater. Preferably, the method of treating the surface of copper foil also includes a step 103 of plating zinc or a zinc alloy by an amount of 0.5-20 mg/mafter the plating of cobalt and a step 104 of plating further chromium or a chromium alloy by an amount of 0.5-20 mg/m.

Description

  The present invention relates to surface treatment of copper foil for printed circuit, and more specifically, the surface of copper foil used for printed circuit such as flexible printed circuit (FPC) is subjected to plating treatment and adhesion to resin film. The present invention relates to a surface treatment method for a copper foil for printed circuit, which has improved heat resistance, acid resistance and the like, the copper foil, and a plating apparatus.

  Copper foil, which is a basic material used in printed circuits for electronic components, is manufactured through a foil-making process for producing electrolytic copper foil by electroplating and a post-treatment process for giving peel strength to the original foil. .

  The copper foil produced by the normal foil making process is peeled off from the cathode plate when electroplating, and has a relatively low roughness and glossy surface (S surface: Shiny Side), and the other surface of the S surface. And a surface having a relatively high roughness and no gloss (M surface: Matte Side).

  The electrolytic copper foil produced in the foil-making process is given physical and chemical characteristics suitable for printed circuits by performing a surface treatment that forms a copper nodule and a barrier in the post-treatment process.

  That is, in the post-processing step, the copper foil is electroplated by sequentially passing through the first copper plating tank 10, the second copper plating tank 11, the nickel plating tank 12, the chrome plating tank 13 and the like as shown in FIG. Surface treated by. In FIG. 1, the main body copper foil 1 is guided to the inside of each plating tank by a plurality of guide rolls 14 and finally taken up by a take-up roll 15. An electrode having a polarity corresponding to the polarity applied to the plating solution for electroplating is connected to the guide roll 14 disposed in each plating tank. The first copper plating tank 10 is filled with a plating solution for generating copper nodule nuclei on the M surface of the copper foil, and the second copper plating tank 11 is filled with a plating solution for growing copper nodule nuclei. It is.

  As shown in FIG. 2, the printed circuit copper foil has a structure in which the copper nodule layer 2 is provided on the M surface of the main body copper foil 1 by the post-processing step. On the copper nodule layer 2, a barrier layer 3 which is a plating layer of nickel (Ni), chromium (Cr) or the like is provided, and heat resistance, hydrochloric acid resistance, oxidation resistance and the like are given. Although not shown, a silane coupling agent is applied on the barrier layer 3 in order to improve the adhesive force with the resin film bonded to the copper foil.

  However, there is a limit to increasing the adhesive strength, heat resistance, acid resistance, etc. in the conventional post-treatment process, especially in the high-temperature heat treatment process for bonding copper foil and polymer resin, the heat resistance is fragile and the etching property is not good. There is a problem.

JP 2004-238647 A

  The present invention was devised to solve the above-described problems, and is a print in which the metal element component of the barrier layer is improved in order to improve the adhesive strength, heat resistance, acid resistance, etc. with the resin film. An object of the present invention is to provide a surface treatment method for a copper foil for circuits, a copper foil produced by the method, and a plating apparatus for the copper foil.

  In order to achieve the above-described object, the present invention discloses a surface treatment method for a copper foil for a printed circuit which provides a barrier layer containing a cobalt (Co) element.

  That is, the present invention is a first step of forming a copper nodule layer on the surface of a copper foil having a surface roughness (Rz) of 2.0 μm or less and a bending property of 60 times or more, and cobalt on the copper nodule layer. A copper foil for printed circuits having an adhesive strength of 1.0 kgf / cm or more with a polyimide (PI) film through a surface treatment process including a second step of plating a (Co) or cobalt (Co) alloy to form a barrier layer. Disclosed is a surface treatment method for a printed circuit copper foil that can be provided.

The plating amount of cobalt (Co) is preferably 0.5 to 50 mg / m ² .

  When the barrier layer is formed in the second step, a treatment of plating zinc (Zn) or a zinc (Zn) alloy can be further performed.

The plating amount of zinc (Zn) is preferably 0.5 to 20 mg / m ² .

  When the barrier layer is formed in the second stage, a treatment of plating chromium (Cr) or a chromium (Cr) alloy may be further performed.

The plating amount of chromium (Cr) is preferably 0.5 to 20 mg / m ² .

  Preferably, after the second step, a treatment for applying a silane coupling agent on the barrier layer can be performed.

  The silane is preferably epoxy-based or amine-related.

  According to the present invention, by forming the barrier layer containing cobalt (Co) or cobalt (Co) alloy on the copper nodule layer of the copper foil, in particular, the adhesive force between the copper foil for FPC and the polyimide (PI) resin. And the heat resistance, acid resistance, corrosion resistance, etching property and the like can be improved.

The following drawings attached to the specification illustrate preferred embodiments of the present invention, and together with the detailed description, serve to further understand the technical idea of the present invention. It should not be construed as being limited to the matters described in the drawings.
It is a block diagram of the copper foil plating apparatus for printed circuits used in the post-processing process by a prior art. It is sectional drawing which showed the main structures of the copper foil for printed circuits surface-treated by the copper foil plating apparatus for printed circuits of FIG. 1 is a flowchart illustrating a process in which a surface treatment method for a printed circuit copper foil according to a preferred embodiment of the present invention is performed. 1 is a configuration diagram of a copper foil plating apparatus for a printed circuit according to a preferred embodiment of the present invention. 1 is a cross-sectional view illustrating a main configuration of a printed circuit copper foil surface-treated by a printed circuit copper foil plating apparatus according to a preferred embodiment of the present invention.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in this specification and claims should not be construed to be limited to ordinary or lexicographic meanings, and the inventor himself should explain the invention in the best possible manner. It must be interpreted with the meaning and concept corresponding to the technical idea of the present invention in accordance with the principle that the term concept can be appropriately defined. Therefore, the configuration described in the embodiments and drawings described in this specification is only the most preferable embodiment of the present invention, and does not represent all of the technical idea of the present invention. It should be understood that there are various equivalents and variations that can be substituted at the time of filing.

  In the present invention, a copper foil is manufactured by performing a foil manufacturing process, and then a nodule process (S110) in which copper is plated on the M surface of the copper foil to form a number of nodule structures, and cobalt ( A surface treatment process including a barrier layer plating process (S120) for strengthening physical and chemical characteristics by forming a plating layer containing a (Co) component is performed.

  FIG. 4 shows a schematic configuration of a copper foil plating apparatus for a printed circuit for performing a surface treatment method according to a preferred embodiment of the present invention.

  Referring to FIG. 4, a copper foil plating apparatus for a printed circuit according to a preferred embodiment of the present invention includes a first copper plating tank 100 and a second copper plating tank 101 for forming a copper nodule structure on a copper foil, A cobalt plating bath 102 for forming a barrier layer on the copper nodule structure.

  The first copper plating tank 100 is filled with a plating solution for generating copper nodule nuclei on the M surface of the copper foil, and the second copper plating tank 101 is filled with a plating solution for growing copper nodule nuclei. It is.

  In the cobalt plating tank 102, a plating solution containing cobalt (Co) or a cobalt (Co) alloy component having high adhesive strength to a resin film such as polyimide (PI) and excellent in heat resistance, acid resistance, and corrosion resistance. It is filled.

  In order to further enhance the physical and chemical properties provided by the cobalt (Co) component, the copper foil plating apparatus for printed circuits is filled with a plating solution containing zinc (Zn) or a zinc (Zn) alloy component. A tank 103 and a chromium plating tank 104 filled with a plating solution containing chromium (Cr) or a chromium (Cr) alloy component are further provided.

  The cobalt (Co) content in the plating solution filled in the cobalt plating bath 102 and the zinc (Zn) content in the plating solution filled in the galvanizing bath 103 can be set to 1.0 g / l. It is desirable to maintain the pH of the two plating solutions at 12 and the temperature at 30 ° C.

  The main body copper foil 200 manufactured by the foil making process sequentially passes through the first copper plating tank 100, the second copper plating tank 101, the cobalt plating tank 102, the galvanizing tank 103, and the chrome plating tank 104 sequentially. Surface treatment is performed by electroplating. Here, the main body copper foil 200 is guided to the inside of each plating tank by a plurality of guide rolls 105 and finally taken up by the take-up roll 106. The guide roll 105 disposed inside each plating tank is energized with an electrode having a polarity corresponding to the polarity applied to the corresponding plating solution for electroplating.

  FIG. 5 shows a structure of a copper foil for a printed circuit manufactured by a copper foil plating apparatus for a printed circuit according to a preferred embodiment of the present invention.

  As shown in FIG. 5, the copper foil for a printed circuit is provided on the main body copper foil 200, the copper nodule layer 201 formed on the M surface of the main body copper foil 200, and the copper nodule layer 201. And a barrier layer 202 containing components such as zinc (Zn) and chromium (Cr).

  In consideration of physical characteristics required for the copper foil for printed circuit, the surface roughness (Rz) of the main body copper foil 200 is desirably 2.0 μm or less. When the surface roughness (Rz) of the main body copper foil 200 exceeds 2.0 μm, there is a problem that the surface of the copper foil becomes excessively uneven.

The cobalt (Co) component plated on the copper nodule layer 201 acts to increase the adhesive strength, heat resistance, hydrochloric acid resistance, corrosion resistance, and the like for resin films such as polyimide (PI). In the barrier layer 202, it is effective that the plating amount of cobalt (Co) is 0.5 to 50 mg / m ² .

The zinc (Zn) and chromium (Cr) components act to further enhance the heat resistance, chemical resistance, oxidation resistance, and the like of the barrier layer 202. Here, the plating amount of zinc (Zn) is effectively 0.5 to 20 mg / m ² , and the plating amount of chromium (Cr) is effectively 0.5 to 20 mg / m ^2. It is.

  A silane coupling agent (not shown) is applied on the barrier layer 202 in order to improve the adhesive force with the resin film adhered to the copper foil. Here, as a silane, an epoxy type or an amine type is desirable.

  In order to improve the peel strength, the copper foil for printed circuit has a structure in which the main body copper foil 200 has a surface roughness (Rz) of 2.0 μm or less and a bending property (number of bendings) of 60 or more. Moreover, the copper foil for printed circuits is required to have an adhesive strength with a polyimide (PI) film of 1.0 kgf / cm or more and a chemical resistance against HCl (hydrochloric acid) of 2% or less. Here, the bending characteristics are determined by performing a bending test that repeats the operation of bending the main body copper foil 200 and then extending it, and measuring the number of bending resistances at which the breaking phenomenon does not occur. In addition, chemical resistance is tested by immersing a copper foil sample processed into a wiring pattern of a printed circuit board in HCL, measuring the depth of penetration of HCL in the width direction of the copper foil sample, It is determined by converting to a percentage of the original width of the foil sample.

  Table 1 shows the results of comparing the peel strength characteristics of the copper foil for printed circuits according to one embodiment of the present invention and the HCl property, which is an index of chemical resistance, with the prior art (comparative example).

In Table 1, examples of the present invention are cases where a barrier layer 202 is formed by plating 10 mg / m ^{2 of} cobalt (Co) and zinc (Zn) on a main body copper foil having a thickness of 12 μm. After bonding polyimide (PI), heat treatment was performed at 180 ° C. for 48 hours, and the peel strength and HCl property of the copper foil were measured.

  On the other hand, a comparative example is a case where a barrier layer is formed with nickel (Ni) as a main component on a main body copper foil having a thickness of 12 μm. After polyimide (PI) is bonded as a resin film, heat treatment is performed at 180 ° C. for 48 hours. Then, the peel strength and HCl property of the copper foil were measured.

  Referring to Table 1, it can be confirmed that when the present invention is applied, the peel strength characteristics after normal temperature and after heat treatment are all improved and the chemical resistance is improved as compared with the prior art.

  As described above, the present invention has been described by way of limited embodiments and drawings. However, the present invention is not limited thereto, and the present invention can be obtained by a person having ordinary knowledge in the technical field to which the present invention belongs. It goes without saying that various modifications and variations can be made within the scope of the technical idea and the scope of claims.

DESCRIPTION OF SYMBOLS 100 1st copper plating tank 101 2nd copper plating tank 102 Cobalt plating tank 103 Zinc plating tank 104 Chromium plating tank 105 Guide roll 106 Winding roll 200 Main body copper foil 201 Copper nodule layer 202 Barrier layer

Claims (8)

A first step of forming a copper nodule layer on the surface of the copper foil having a surface roughness (Rz) of 2.0 μm or less and a bending property of 60 times or more;
Forming a barrier layer by plating cobalt (Co) or a cobalt (Co) alloy on the copper nodule layer,
The surface treatment method of the copper foil for printed circuits which provides the copper foil for printed circuits whose adhesive strength with a polyimide (PI) film is 1.0 kgf / cm or more. ^2. The surface treatment method for a copper foil for printed circuit according to claim 1, wherein the cobalt (Co) plating amount is 0.5 to 50 mg / m ² .   2. The surface treatment method for a copper foil for a printed circuit according to claim 1, wherein in the second stage, zinc (Zn) or a zinc (Zn) alloy is further plated. The surface treatment method for a copper foil for printed circuit according to claim 3, wherein the zinc (Zn) plating amount is 0.5 to 20 mg / m ² .   2. The surface treatment method for a copper foil for a printed circuit according to claim 1, wherein in the second step, chromium (Cr) or a chromium (Cr) alloy is further plated. 6. The surface treatment method for a copper foil for printed circuit according to claim 5, wherein the chromium (Cr) plating amount is 0.5 to 20 mg / m < ² >.   The surface treatment method for a copper foil for a printed circuit according to claim 1, wherein a silane coupling agent is applied on the barrier layer after the second step.   The surface treatment method for a copper foil for a printed circuit according to claim 7, wherein the silane is epoxy-based or amine-based.

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