WO2008056603A1 - Electroless copper plating method - Google Patents

Abstract

A coating film having good adhesion can be formed by a simple process of an electroless plating method without performing a surface roughening treatment on a plastic film surface to be processed. This coating film enables to form a circuit electrode of a fine pitch wiring pattern. Specifically disclosed is an electroless copper plating method wherein a plastic film composed of a resin composition having an aromatic ring structure in the main chain is provided with a catalyst and immersed in an electroless copper plating liquid, and a plating for forming a copper coating film is performed by a reduction reaction. In this method, the plastic film is subjected to a solution treatment, wherein the plastic film is brought into contact with a sulfuric acid-hydrogen peroxide mixture, before plating.

Description

 Specification

 Electroless copper plating method

 Technical field

 The present invention relates to an electroless copper plating method for forming a copper film on a plastic film made of a resin composition having an aromatic ring structure in the main chain.

 Background art

 Conventionally, a plastic film made of a resin composition having an aromatic ring structure in the main chain, such as polyethylene terephthalate (PET), polyphenylene sulfide (PPS), and wholly aromatic polyamide (aramid) has been heat resistant. It is excellent in electrical insulation, dielectric properties, moisture resistance, chemical resistance, etc., and has been widely used as an insulating base material for electronic parts, focusing on its relatively low cost. For example, it is used as a flexible printed circuit board (FPC) by forming a copper film on the surface of the plastic film and further subjecting the copper film to photolithography.

 [0003] By the way, as one method for forming a metal film such as copper on the surface of the plastic film, conventionally, metal ions in a solution are chemically reduced and deposited to form a metal film on the surface of the substrate. There are known electroless plating methods.

 [0004] In this method, palladium, silver or the like is added as a catalyst, and a plastic film is immersed in an electroless plating solution composed of a metal source, a complexing agent, a reducing agent, etc. (In this specification, this treatment is simply referred to as “plating treatment”). However, in recent years, the anchor effect is utilized to make the coating adhere to a plastic film made of a resin composition. For the purpose of improving the strength, the surface (surface to be treated) of a plastic film as a base material is first roughened before the staking treatment.

[0005] Specifically, this roughening is performed by forming irregularities on the surface to be processed by etching the surface to be processed of the plastic film using an etching solution such as chromic acid or an alkaline aqueous solution. (For example, see Patent Document 1 for a method using an alkaline aqueous solution). Patent Document 1: Japanese Patent Laid-Open No. 7-207451

 Disclosure of the invention

 Problems to be solved by the invention

[0007] However, even if such etching is performed on the surface to be treated as a pretreatment for the plating treatment, depending on the type of the plastic film, the adhesion of a metal film such as copper to the film is required for the electronic component. The force is not enough compared to the adhesive strength.

[0008] In addition, when circuit electrodes are formed on a surface to be processed with a copper film, if the unevenness formed on the rough surface is too large, the film thickness and the etching rate will not be constant, and the edge of the wiring pattern It is difficult to form a straight line. For this reason, it was difficult to form circuit electrodes with a fine pitch wiring pattern.

[0009] Further, in the etching solution containing chromic acid, the use of the chromic acid has an environmental problem, and the etching using the alkaline aqueous solution is a process at a high temperature for a long time and the cost is increased. there were.

[0010] The present invention has been made in view of these points, and in particular, the adhesion of the copper coating to a plastic film made of a resin composition having an aromatic ring structure in the main chain is good, and Means for solving the problem of providing an electroless copper plating method for producing a copper-plated plastic film that can easily process fine pitch (m-order) wiring patterns

[0011] In order to achieve the above object, the electroless copper plating method of the present invention is characterized in that a catalyst is imparted to a plastic film comprising a resin composition having an aromatic ring structure in the main chain, and electroless An electroless copper plating method in which a copper coating is formed by dipping in a copper plating solution to form a copper film by a reduction reaction, wherein the plastic film is subjected to hydrogen peroxide sulfate before the plating treatment. It is in the point which performs the solution processing which contacts water.

[0012] According to the electroless copper plating method of the present invention, organic contaminants on the treated surface of the plastic film are removed by bringing the plastic film into contact with sulfuric acid hydrogen peroxide solution. In order to improve the wettability by oxidizing the surface to be treated and to remove the fragile layer on the surface to be treated, the surface is covered by an easy process without excessive surface roughening. A film having good adhesion can be formed on the treated surface.

[0013] Further, another feature of the electroless copper plating method of the present invention is that, before the solution treatment, the treatment surface of the plastic film is irradiated with ultraviolet rays and / or plasma. There is a point to do.

[0014] According to the electroless copper plating method of the present invention, organic contaminants on the treated surface of the plastic film are removed in advance by irradiating the treated surface of the plastic film with ultraviolet rays or plasma. Since the surface to be treated of the plastic film is also oxidized, solution treatment with a mixed solution of an acid and an oxide can be performed more efficiently, thereby improving the adhesion of the coating to the surface to be treated. Can be improved.

[0015] Further, another feature of the electroless copper plating method of the present invention is that an alkali treatment is performed on the plastic film after the solution treatment.

[0016] According to the electroless copper plating method of the present invention, the surface to be treated of the plastic film can be made a high cleaning surface by performing an alkali treatment, whereby the film is in close contact with the surface to be treated. The power S can be improved. It is presumed that OH groups are arranged on the surface to be treated and affect the catalyst application state.

[0017] Further, another feature of the electroless copper plating method of the present invention is that after the plating process, a heat treatment for heating the plastic film or a heating / pressurizing process for heating while pressing is performed. It is in.

 [0018] According to the electroless copper plating method of the present invention, after forming a coating on a plastic film, the plastic film is heated to remove hydrogen present at the interface between the surface to be processed and the coating. In addition, by heating the plastic film while applying pressure, the gap between the surface to be treated and the coating can be reduced, and hydrogen that has entered the interface between the surface to be treated and the coating can be reduced. Can be removed. As a result, the adhesion of the coating to the surface to be processed can be further improved.

 [0019] Further, another feature of the electroless copper plating method of the present invention is that the sulfuric acid hydrogen peroxide solution is composed of sulfuric acid and 30% to 36% hydrogen peroxide solution, and the sulfuric acid is 50% by volume. ~ 70% by volume, hydrogen peroxide water is 50% to 30% by volume.

[0020] According to the electroless copper plating method of the present invention, the sulfuric acid hydrogen peroxide solution is prepared at this ratio. As a result, it is possible to improve the wettability by oxidizing the treated surface of the plastic film, and to avoid applying an excessive surface roughening treatment to remove the fragile layer on the treated surface. As a result, a film having good adhesion can be formed on the surface to be treated. It is also possible to use a treatment solution in which a surfactant is added to the sulfuric acid hydrogen peroxide solution!

 [0021] Further, another feature of the electroless copper plating method of the present invention is that the electroless copper plating solution contains copper ions, nickel ions, formaldehyde as a reducing agent, and tartaric acid or tartrate as a complexing agent. It is in the point of including.

 [0022] According to the electroless copper plating method of the present invention, a low-stress copper plating film can be obtained, and sufficient adhesion between the substrate and the copper plating film can be secured.

 [0023] Further, another feature of the electroless copper plating method of the present invention is that the addition amount of the nickel ions is less than 30 mol of lmo paste relative to lOOmol of copper ions contained in the electroless copper plating solution. There is a point.

 [0024] According to the electroless copper plating method of the present invention, sufficient adhesion between the plastic film and the copper coating can be obtained, and the physical properties of copper can be maintained even when used as a circuit electrode. Thus, a significant increase in specific resistance can be prevented.

 The invention's effect

 [0025] As described above, according to the electroless copper plating method according to the present invention, a copper film having a good adhesion without excessively roughening the surface to be treated of a plastic film. Forming power S is possible. In addition, since the surface to be treated is not excessively roughened, the circuit electrode of the fine pitch wiring pattern must be formed when the circuit electrode is formed by the copper coating formed on such a plastic film. Can do.

 Brief Description of Drawings

 FIG. 1 is a flowchart showing each step of an electroless plating method according to the present invention.

 BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the electroless copper plating method of the present invention will be described with reference to FIG. 1 and FIG.

 FIG. 1 is a flowchart showing each step of the electroless copper plating method of the present embodiment.

In this embodiment, the base material to which electroless copper plating is applied is an aromatic ring in the main chain. It is a plastic film having a resin composition having a structure.

 As shown in FIG. 1, first, as a pretreatment for plating treatment (main treatment) on a plastic film as a base material, an irradiation treatment is performed in which ultraviolet rays are irradiated onto a surface to be treated on which a copper film is formed on the plastic film. (Hereinafter referred to as UV treatment) is performed (ST11). In this ultraviolet treatment, active oxygen is separated from ozone generated by ultraviolet rays, and organic pollutants present on the surface to be treated are decomposed into volatile substances and removed by the active oxygen. The surface to be treated can be cleaned and oxidized by directly breaking the bond of organic pollutants.

 [0030] In this ultraviolet treatment, it is preferable to irradiate ultraviolet rays having a wavelength of 254 nm or less. This is because when the ultraviolet rays irradiated to the surface to be processed have a wavelength longer than 254 nm, the cleaning power for the surface to be processed is reduced. It is further desirable that the wavelength of ultraviolet light is 172 nm. This is because the wavelength of light is short and the energy is high, so the effect of removing organic contamination and oxidizing the surface to be treated is great.

 Here, instead of the ultraviolet treatment or in addition to the ultraviolet treatment, an irradiation treatment (hereinafter referred to as plasma treatment) for irradiating the plastic film with plasma may be performed. In plasma processing, the organic pollutants existing on the surface to be processed are changed to other states and removed by radicals generated by generating plasma, so that the surface to be processed can be cleaned and oxidized. Note that when plasma processing is performed in addition to ultraviolet processing, the order of processing may be any first.

[0032] After the ultraviolet treatment, next, a solution treatment is performed in which the plastic film is immersed in a sulfuric acid hydrogen peroxide solution, which is a mixed solution of sulfuric acid and hydrogen peroxide solution having a predetermined temperature and composition ratio, for a predetermined time (ST12). ). The sulfuric acid / hydrogen peroxide solution is composed of sulfuric acid and 30% to 36% hydrogen peroxide solution, the sulfuric acid is 50% to 70% by volume, and the hydrogen peroxide solution is the remaining 50% to 30% by volume. It is preferable that If the sulfuric acid concentration is less than 50% by volume, the oxidation and cleaning treatments will be inadequate, and the adhesion will be poor. If the concentration exceeds 70% by volume, damage will occur on the surface of the aramid film, resulting in a stable film state. It is because it becomes impossible to keep. Also, if the concentration of hydrogen peroxide falls below 30%, or if the concentration of hydrogen peroxide is reduced by diluting with water other than sulfuric acid and hydrogen peroxide, the oxidizing power is insufficient and sufficient effects are obtained. This is not desirable because the adhesion is reduced. In addition, if the concentration of hydrogen peroxide solution exceeds 36%, the oxidizing power becomes a problem, and the aramid film surface may be damaged, which is not desirable. Further, the sulfuric acid hydrogen peroxide solution may contain an additive such as a surfactant. By including a surfactant, the wettability is improved and the reattachment of foreign matter can be prevented. In this solution treatment, the treated surface of the plastic film is oxidized to give oxygen. At this time, the surface to be processed is in a state where the thin film has been peeled off, and fine linear or dot-shaped convex portions appear on the surface to be processed, and fine irregularities are formed on the surface to be processed.

 [0033] After the solution treatment, subsequently, a degreasing treatment is performed in which the plastic film is immersed in an aqueous sodium hydroxide solution to perform an alkali treatment (ST13). In the degreasing treatment, by subjecting the treated surface of the plastic film to a degreasing treatment, the treated surface can be cleaned and wettability can be improved. In addition, it is presumed that OH groups are added on the plastic film, which has a good effect on the catalyst application.

 Next, the plastic film pretreated in this way is subjected to a tacking process (main process) by an electroless plating method.

 That is, a catalyst treatment for applying a catalyst to the treated surface of the plastic film that has been subjected to the pretreatment of the electroless plating method is performed (ST14). In the catalyst treatment, the plastic finoleum is immersed in an aqueous tin chloride solution at a predetermined temperature for a predetermined time and then washed. The plastic film is immersed in an aqueous palladium chloride solution at a predetermined temperature for a predetermined time, and then washed with water. Further, after the plastic film is immersed again in the tin chloride aqueous solution and washed, the step of immersing the plastic film in the palladium chloride aqueous solution and then washing with water is repeated. As a result, a catalyst is applied to the treated surface of the plastic film.

 [0036] After the catalyst treatment, a film-forming treatment for forming a copper film on the treated surface of the plastic film is further performed (ST15). In the film formation process, for example, the plastic film is coated by immersing it in a copper plating solution at a predetermined temperature containing copper ions, nickel ions, formaldehyde as a reducing agent, and tartaric acid or tartrate as a complexing agent. A copper film is formed on the treated surface.

[0037] The amount of copper ions added to the copper plating solution is 0 · 041-0.055 mol / L. It is preferable that the amount of added rhoion is not more than 30 mol of lmo with respect to lOOmol of copper ion contained in the copper plating solution. Nickel ion force Copper ion If it is less than lmol with respect to lOOmol, sufficient adhesion between the plastic film and the copper coating will not be obtained. For example, when a copper film is used as a circuit electrode, the specific resistance is greatly increased because the physical properties are lowered.

 [0038] Furthermore, this copper plating solution contains about 1.5 g / L sodium hydroxide (NaOH) for pH adjustment, and the pH is adjusted to about 12.6. About 0.1% chelating agent.

 [0039] After the film forming process, a heating process is performed in which the plastic film is heated at a predetermined temperature for a predetermined time (ST16). Instead of this heat treatment, it may be a heat / pressure treatment in which a plastic film is heated in a predetermined pressure atmosphere! /, (ST16 '). As a result, the gap between the copper coating and the surface to be processed can be reduced.

 Next, the operation of this embodiment will be described.

 [0041] In the present embodiment, organic contaminants on the treated surface of the plastic film can be removed by bringing the hydrogen peroxide aqueous solution into contact with the plastic film, and the treated surface of the plastic film. To improve wettability and form a film with good adhesion on the surface to be processed by an easy process without excessive roughening treatment to remove the fragile layer on the surface to be processed Can do.

 [0042] Therefore, since the surface to be treated of the plastic film is not excessively roughened, when forming circuit electrodes with a copper film formed on such a plastic film, an order fine pitch wiring pattern is used. This is a circuit electrode that can be easily formed.

[0043] Further, before the solution treatment, an ultraviolet treatment is performed, and further, a plasma treatment is performed in place of or in addition to the ultraviolet treatment, thereby removing organic contaminants on the treated surface of the plastic film. It can be removed in advance. In addition, since the surface to be treated of the plastic film is oxidized, solution treatment with sulfuric acid hydrogen peroxide can be performed more efficiently. Thereby, the contact | adhesion power of the film with respect to a to-be-processed surface can be improved more. [0044] Furthermore, by performing a degreasing treatment after the solution treatment, the treated surface of the plastic film can be made a high cleaning surface, and the adhesion state of the catalyst in the catalyst treatment step is improved. Thereby, the contact | adhesion power of the copper film with respect to a to-be-processed surface can be improved more.

[0045] Further, after forming the copper film on the plastic film, the gap between the surface to be treated and the copper film can be reduced by heating the plastic film while applying pressure. Hydrogen that has entered the interface between the copper film and the copper film can be removed. Thereby, the adhesive force of the copper film with respect to a to-be-processed surface can be improved more.

 Example

[Example 1]

As the plastic film, a 25 μm thick aramid film (manufactured by Toray: trade name Mikutron) is prepared. In the irradiation process (ST11) as a pretreatment, xenon excimer UV is applied to the aramid film. The ultraviolet ray treatment was performed by irradiating with ultraviolet rays having a wavelength of 172 nm and a light amount of 20 mW / cm ² for 2 minutes.

[0047] Subsequently, in the solution treatment step (ST12), sulfuric acid peroxidation in which the liquid temperature was set to 23 ° C, sulfuric acid was adjusted to 60% by volume, and 35% hydrogen peroxide solution was adjusted to 40% by volume. Prepared with hydrogen water, the aramid film was immersed in this sulfuric acid hydrogen peroxide solution for 3 minutes for solution treatment.

 [0048] Further, in the degreasing step (ST13), a 13% sodium hydroxide aqueous solution having a liquid temperature set to 50 ° C is prepared, and the aramid film is immersed in the sodium hydroxide aqueous solution for 3 minutes. The degreasing process was performed.

 [0049] Next, in the catalyst treatment step (ST14) as the main treatment, the aramid film was immersed in a tin chloride aqueous solution having a concentration of stannous chloride of 1.3% for 3 minutes and then rinsed. Thereafter, it was immersed in an aqueous palladium chloride solution having a palladium ion concentration of 0.015% for 2 minutes. This catalyst treatment step was repeated twice to give a catalyst to the treated surface of the aramid film.

[0050] Subsequently, in the film forming process (ST15), a copper film was formed on the surface to be processed of the aramid film. In the film forming process, 0.047 mol / L of copper ions, and mol / L of nickel ions is added, sodium potassium tartrate tetrahydrate (Rosiel salt) as a complexing agent, about 0.2% honoremuanolide as a reducing agent, and about 0.1% A copper plating solution containing a chelating agent was prepared. Further, the copper plating solution contains about 1.5 g / L sodium hydroxide (NaOH) as pH adjustment, and the pH is adjusted to 12.6. Then, the aramid film was immersed in the plating solution whose liquid temperature was set to 30 ° C. for 1 hour to form a copper coating on the surface to be treated of the aramid film.

[0051] Thereafter, in the heat treatment step (ST16), the heat treatment temperature was set to 150 ° C, and the aramid film was heated in a nitrogen atmosphere at atmospheric pressure with a heat treatment time of 1 hour. This completed the copper coating formed on the treated surface of the aramid film.

[0052] The copper-coated aramid film obtained through such treatment steps was evaluated for the adhesion of the copper coating to the surface to be treated.

 [0053] Adhesion strength is evaluated by whether cellophane tape is attached to a copper film, and when this cellophane tape is peeled off, the copper film peels off the surface to be treated together with the cellophane tape. Thus, an adhesion test using a cellophane tape for evaluating the adhesion of the copper film to the surface to be treated was conducted. In this case, the copper film did not peel from the surface to be treated, and sufficient adhesion between the aramid film and the copper film could be secured.

 [0054] Further, an evaluation pin made of aluminum having a diameter of 2 mm and having a flat bottom surface and coated with an epoxy resin is used, and the bottom surface of the evaluation pin is brought into contact with the copper film at a temperature of 150 ° C. Heat and fix the pin for evaluation to the copper coating via the epoxy resin. Then, a tensile test was performed through an evaluation pin, and the tensile strength when the copper coating was peeled from the aramid film was measured on the treated surface of the aramid film (Sebastian method). As a result, it was confirmed that the aramid film was broken before the copper film was peeled off from the surface of the aramid film, and had a sufficient adhesion strength.

 [Example 2]

 Example 2 was different from the electroless plating method of Example 1 described above in the following points, and a copper film was formed on the aramid film.

That is, in this example, irradiation treatment in the electroless plating method of Example 1 In the process (ST11), instead of UV treatment, plasma treatment was used, and an aramid film was irradiated with argon gas plasma at a moving speed of 1 Omm / sec for 10 seconds using an atmospheric pressure oxygen plasma treatment device (Matsushita Electric Works). did.

[0057] Further, in this example, the heat treatment step (ST16) is carried out in the nitrogen film in a nitrogen atmosphere with a heat treatment temperature set to 150 ° C and a heat treatment time of 1 hour in an environment of 0.3 MPa. Was heated.

 [0058] An adhesion test similar to the adhesion test using the cellophane tape described above was performed on the copper-coated aramid film obtained through such a treatment process. However, the copper coating did not peel from the surface to be treated, and sufficient adhesion between the aramid film and the copper coating could be secured.

 [0059] Further, when the adhesion of the copper coating was evaluated under the same conditions as in the Sebastian method, the aramid film was broken before the copper coating was peeled off from the surface of the aramid film. And with sufficient adhesion strength!

 [0060] (Example 3)

As the plastic film, a PET (polyethylene terephthalate) film (made by Teijin DuPont Films: trade name Tetron Film) with a thickness of 100 m is prepared, and this PET is used in the irradiation treatment process (ST11) as a pretreatment. The film was irradiated with ultraviolet rays using a xenon excimer UV with a wavelength of 172 nm and an amount of light of 20 mW / cm ² for 2 minutes.

 [0061] Subsequently, in the solution treatment step (ST12), the sulfuric acid peroxidation was adjusted to a liquid temperature of 23 ° C, sulfuric acid adjusted to 60% by volume, and 35% hydrogen peroxide solution to 40% by volume. Prepared with hydrogen water, the PET film was immersed in this hydrogen peroxide solution for 3 minutes for solution treatment.

 [0062] Further, in the degreasing treatment step (ST13), a 13% sodium hydroxide aqueous solution having a liquid temperature of 50 ° C is prepared, and the PET film is immersed in the sodium hydroxide aqueous solution for 3 minutes. Degreasing treatment was performed.

[0063] Next, in the catalyst treatment step (ST14) as the main treatment, the PET film was immersed in a tin chloride aqueous solution having a stannous chloride concentration of 1.3% for 3 minutes, and then rinsed. Para It was immersed for 2 minutes in a palladium chloride aqueous solution having a concentration of dimethyl ion of 0.015%. This catalyst treatment step was repeated twice to give a catalyst to the treated surface of the PET film.

 [0064] Subsequently, in the film forming process (ST15), a copper film was formed on the surface to be processed of the PET film. In the film forming process, 0.047 mol / L copper ion and 0.0022 mol / L nickel ion are added, sodium potassium tartrate tetrahydrate (Rossiel salt) as a complexing agent, and reducing agent as a reducing agent. Then, a copper plating solution containing about 0.2% honoremuanolide and about 0.1% chelating agent was prepared. Further, the copper plating solution contains about 1.5 g / L sodium hydroxide (NaOH) as pH adjustment, and the pH is adjusted to 12.6. Then, the PET film was immersed in the plating solution set at a liquid temperature of 30 ° C. for 1 hour to form a copper film on the treated surface of the PET film.

 [0065] Thereafter, in the heat treatment step (ST16), the heat treatment temperature was set to 150 ° C, and the heat treatment time was 1 hour at atmospheric pressure, and the PET film was heated in a nitrogen atmosphere. As a result, a copper film formed on the treated surface of the liquid crystal polymer film was completed.

 [0066] For the copper-plated PET film obtained through such a treatment step, the adhesion of the copper film to the surface to be treated was evaluated.

 [0067] The adhesion strength is evaluated by whether cellophane tape is attached to a copper film, and when the cellophane tape is peeled off from the surface to be treated, the copper film peels off from the surface to be treated together with the cellophane tape. Thus, an adhesion test using a cellophane tape for evaluating the adhesion of the copper film to the surface to be treated was conducted. In this case, the copper film did not peel from the surface to be treated, and sufficient adhesion between the PET film and the copper film could be secured.

[0068] In addition, an evaluation pin made of aluminum having a diameter of 2 mm and having a flat bottom surface and coated with an epoxy resin is used, and the bottom surface of the evaluation pin is brought into contact with the copper film at a temperature of 150 ° C. Heat and fix the pin for evaluation to the copper coating via the epoxy resin. Then, a tensile test was performed through an evaluation pin, and the tensile strength when peeling from the copper film strength ΦΕΤ film was measured on the treated surface of the PET film (Sebastian method). As a result, it was confirmed that the copper film strength ΦΕΤ film peeled before peeling from the film surface, and the PET film was broken and had sufficient adhesion strength. [0069] (Example 4)

 Example 4 is different from the above-described electroless plating method of Example 3 in the following points:

A copper film was formed on the PET film.

That is, in this example, in the irradiation process step (ST11) in the electroless plating method of Example 3, plasma treatment was used instead of ultraviolet treatment, and an atmospheric pressure oxygen plasma treatment apparatus (manufactured by Matsushita Electric Works) was used. The PET film was irradiated with argon gas plasma at a moving speed of 1 Omm / sec for 10 seconds.

[0071] Further, in this example, the heat treatment step (ST16) is performed in the nitrogen atmosphere in a nitrogen atmosphere with a heat treatment temperature set to 150 ° C and a heat treatment time of 1 hour in an environment of 0.3 MPa.

The ET film was heated.

[0072] An adhesion test similar to the adhesion test using the cellophane tape described above was performed on the copper-plated PET film obtained through such a treatment process.

Even when applied to an ET film, the copper coating did not peel from the treated surface, and sufficient adhesion between the PET film and the copper coating could be secured.

[0073] Further, when the adhesion of the copper film was evaluated under the same conditions as in the Sebastian method, the copper-coated PET film also had a copper film strength before being peeled from the surface of the SPET film.

The PET film was broken and had sufficient adhesion strength!

[Example 5]

 As the plastic film, a PI (polyimide) film (made by Toray DuPont: trade name Kapton) with a thickness of 50 μm is prepared. In the irradiation process (ST11) as a pretreatment, Using xenon excimer UV, wavelength is 172nm, light intensity is 20m

Ultraviolet treatment was performed by irradiating W / cm ² ultraviolet rays for 2 minutes.

[0075] Subsequently, in the solution treatment step (ST12), the sulfuric acid peroxidation was adjusted to a liquid temperature of 23 ° C, sulfuric acid adjusted to 60% by volume, and 35% hydrogen peroxide solution to 40% by volume. Prepared with hydrogen water, the PI film was immersed in this hydrogen peroxide solution for 3 minutes for solution treatment.

[0076] Further, in the degreasing step (ST13), a 13% aqueous sodium hydroxide solution having a liquid temperature of 50 ° C was prepared, and the PI film was placed in this aqueous sodium hydroxide solution for 3 minutes. A degreasing treatment was carried out by immersing in between.

 [0077] Next, in the catalyst treatment step (ST14) as the main treatment, the PI film is chlorinated.

 1 After immersing in a tin chloride aqueous solution having a tin concentration of 1.3% for 3 minutes, rinsing, and then immersing in a palladium chloride aqueous solution having a palladium ion concentration of 0.015% for 2 minutes. This catalyst treatment step was repeated twice to give a catalyst to the treated surface of the PI film.

 [0078] Subsequently, in the film forming process (ST15), a copper film was formed on the processed surface of the PI film. In the film forming process, 0 · 047 mol / L of copper ions and 0.0028 mol / L of nickel ions are added, sodium potassium tartrate tetrahydrate (mouth shell salt) as the complexing agent, and reducing agent as the reducing agent. Then, a copper plating solution containing about 0.2% honoremuanoldehydride and about 0.1% chelating agent was prepared. Further, the copper plating solution contains about 1.5 g / L sodium hydroxide (NaOH) as pH adjustment, and the pH is adjusted to 12.6. Then, the PI film was immersed in the plating solution whose liquid temperature was set to 30 ° C. for 1 hour to form a copper film on the treated surface of the PI film.

 [0079] Thereafter, in the heat treatment step (ST16), the heat treatment temperature was set to 150 ° C, and the PI film was heated in a nitrogen atmosphere at atmospheric pressure with a heat treatment time of 1 hour. As a result, a copper film formed on the treated surface of the liquid crystal polymer film was completed.

 [0080] With respect to the copper-plated PI film obtained through such a treatment process, the adhesion of the copper film to the surface to be treated was evaluated.

 [0081] The adhesion strength is evaluated by whether cellophane tape is attached to a copper film, and when this cellophane tape is peeled off, the copper film is peeled off from the surface to be treated together with the cellophane tape. Thus, an adhesion test using a cellophane tape for evaluating the adhesion of the copper film to the surface to be treated was conducted. In this case, the copper film did not peel off from the surface to be treated, and sufficient adhesion between the PI finale and the copper film could be secured.

[0082] In addition, an evaluation pin made of aluminum having a diameter of 2 mm whose bottom surface is flat and coated with an epoxy resin is used, and the bottom surface of the evaluation pin is brought into contact with the copper film at a temperature of 150 ° C. Heat and fix the pin for evaluation to the copper coating via the epoxy resin. Then, a tensile test is performed through the evaluation pin, and pulling is performed when peeling from the copper film. The tensile strength was measured by measuring the treated surface of the PI film (Sebastian method). As a result, it was confirmed that the PI film was broken before peeling from the surface of the copper film, and that it had sufficient adhesion strength.

 [0083] (Example 6)

 Example 6 is different from the above-described electroless plating method of Example 5 in the following points:

A copper film was formed on the PI film.

[0084] That is, in this example, in the irradiation process step (ST11) in the electroless plating method of Example 3, plasma treatment was used instead of ultraviolet treatment, and an atmospheric pressure oxygen plasma treatment apparatus (manufactured by Matsushita Electric Works) was used. Was used to irradiate the PI film with argon gas plasma at a moving speed of 1 Omm / sec for 10 seconds.

[0085] Further, in this example, in the heat treatment step (ST16), the heat treatment temperature was set to 150 ° C, and the PI film was placed in a nitrogen atmosphere under an environment of 0.3 MPa with a heat treatment time of 1 hour. Heated.

 [0086] An adhesion test similar to the adhesion test using the cellophane tape described above was performed on the copper-plated PI film obtained through such a treatment process. However, the copper film did not peel from the surface to be treated, and sufficient adhesion between the PI film and the copper film could be secured.

 [0087] Further, when the adhesion of the copper film was evaluated under the same conditions as in the Sebastian method, the PI film was broken before the copper film peeled off the surface of the PI film. We were able to confirm that it had sufficient adhesion strength.

 Note that the present invention is not limited to the above-described embodiment, and various modifications can be made as necessary.

 [0089] For example, the processing conditions such as degreasing treatment, catalyst treatment, and plating treatment are not limited to the present embodiment, and various processing steps can be performed using various known processing conditions. Further, the plastic film having an aromatic ring in the main chain is not limited to the aramid film and the like. For example, PEN (polyethylene telenaphthalate) can be exemplified. However, the electroless copper plating method of the present invention can achieve the same effects as described above.

Claims

The scope of the claims  [1] A plating treatment in which a catalyst is applied to a plastic film made of a resin composition having an aromatic ring structure in the main chain and immersed in an electroless copper plating solution to form a copper film by a reduction reaction. An electroless copper plating method,  An electroless copper plating method, wherein the plastic film is subjected to a solution treatment in contact with sulfuric acid / hydrogen peroxide solution before the plating process.  [2] The electroless copper plating method according to [1], wherein the surface to be treated of the plastic film is irradiated with ultraviolet rays and / or plasma before the solution treatment.  [3] The electroless copper plating method according to [1], wherein the plastic film is subjected to an alkali treatment after the solution treatment. [4] The electroless copper plating method according to [1], wherein after the staking treatment, a heat treatment for heating the plastic film or a heating / pressurizing treatment for heating the plastic film is performed.  [5] The sulfuric acid / hydrogen peroxide solution is composed of sulfuric acid and 30% to 36% hydrogen peroxide solution, the sulfuric acid is 50% to 70% by volume, and the hydrogen peroxide solution is 50% to 30% by volume. The electroless copper plating method according to claim 1, wherein [6] The electroless copper plating solution contains copper ions, nickel ions, formaldehyde as a reducing agent, and tartaric acid or tartrate as a complexing agent. The electroless copper plating method according to 1. [7] The electroless copper mesh according to [6], wherein the addition amount of the nickel ion is a lmo amount of 30 mol or less with respect to 100 mol of copper ion contained in the electroless copper plating solution. How to get there.