KR20080030314A - Metallization process of non-conductive polymer substrates using wet surface treatment technology - Google Patents

Abstract

A metallization method of a surface of a non-conductive polymer material using wet surface treatment technology and a polymer film prepared by the metallization method are provided to form a uniform metal film on the surface of the polymer material, enable one or both faces of the polymer material to be subjected to a metallization treatment process, and expect to improve economic efficiency and productivity by a batch process. A metallization method of a surface of a non-conductive polymer material comprises: a first step of proceeding degreasing and cleaning processes to remove contaminants from the polymer material; a second step of proceeding a surface modification process to impart a functional group to the polymer material and impart roughness onto a surface of the polymer material; a third step of proceeding a catalytic treatment process and an activating process to adsorb precious metal particles onto the surface of the polymer material and reduce the precious metal particles into metal particles; and a fourth step of proceeding an electroless plating process to form a final metal film layer. The metallization method further comprises a fifth step of proceeding an electroplating process after the fourth step.

Description

Metallization method of non-conductive polymer substrates using wet surface treatment technology

1 is a diagram illustrating a metallization process of a nonconductive polymer substrate according to the present invention.

2 is an electron microscope observation of the electroless nickel plated coating layer on the surface of the polyimide film prepared according to the method of the present invention.

3 is an electron microscope observation of the electroless copper plating film layer on the surface of the polyimide film prepared according to the method of the present invention.

Figure 4 is an electron microscope observation of the electroless nickel plated coating layer on the surface of the PET film prepared according to the method of the present invention.

5 is an electron microscope observation of the electroless copper plating film layer on the surface of the PET film prepared according to the method of the present invention.

Figure 6 is a picture observed after electroplating the electroless copper plating film layer on the surface of the polyimide film prepared according to the method of the present invention.

The present invention relates to a metallization method of the surface of a non-conductive polymer material using a wet surface treatment technology and a polymer film prepared thereby, specifically, a first step of performing a degreasing and cleaning process to remove contaminants; A second step of performing a surface modification process for imparting roughness to the functional group and the surface of the polymer; A third step of performing a catalytic treatment and an activation process of adsorbing noble metal particles on the surface of the polymer and reducing them to metal particles; And a fourth step of performing an electroless plating process for forming the final metallization layer on the resultant of the third step, and a method of metallization of the surface of the non-conductive polymer material and the polymer film manufactured thereby.

Recently, after the surface modification of the polymer material by plasma ions, a conductive metal bonding layer is formed on the polymer surface by using a dry surface treatment technique such as sputtering or metal deposition, and using electroplating technique according to the product conditions. A method of controlling the thickness of the metal film layer has been developed and applied to mass production. Such dry surface treatment technology has an advantage that the thickness of the metal film layer corresponding to the circuit layer can be adjusted thinner than the conventional method according to the fine circuit pattern structure required in the related industry, and its application range is gradually increasing. However, in the production method of forming a metal film by electroplating after dry surface treatment, the metal surface is modified in an expensive vacuum chamber and the metal deposition process for forming a thin metal bonding layer is carried out in a separate wet plating line. It is known that the batch continuous production method is impossible because the work to form the coating layer is performed. In the metallization process of polymer film material by dry surface treatment technology, there are disadvantages such as uniformity of deposited metal particles, defects caused by pore formation, relatively low productivity and expensive equipment investment due to dualization of production process. .

 In particular, the metallization process of polymer film material by wet surface treatment has advantages such as simple process and equipment, high productivity and uniform metal coating layer along with batch production method, but it does not modify polymer surface and form metal bonding layer. The treatment process conditions are very demanding depending on the basic material, and the physical properties such as the low adhesion between the metal adhesive layer and the polymer surface have many problems in application. Therefore, it is a reality that dry surface treatment technology, which is relatively difficult to form a uniform metal bonding layer and requires expensive manufacturing cost, is widely used in the metallization process of polymer film materials.

Accordingly, the present inventors have been able to solve the problems occurring during the metallization process of the polymer film material by the wet surface treatment technique by the degreasing, surface modification process, activation treatment using a noble metal catalyst and electroless plating process. The invention has been completed.

One object of the present invention is to provide a method for metallization of polymer material surfaces using wet surface treatment techniques. That is, the decontamination and washing process remove the contaminant on the surface of the polymer material, and the surface of the polymer is immersed in a certain mixed solution and modified to impart functional groups and roughness, which is activated by a noble metal catalyst and electroless plating. To provide a method for producing a metallized polymer film in one process.

Another object of the present invention is to provide a polymer film produced by the above method.

In one aspect, the present invention relates to a method for metallization of polymer material surfaces using wet surface treatment techniques. That is, the present invention comprises a first step of proceeding a degreasing and cleaning process to remove contaminants; A second step of performing a surface modification process for imparting roughness to the functional group and the surface of the polymer; A third step of performing a catalytic treatment and an activation process of adsorbing noble metal particles on the surface of the polymer and reducing them to metal particles; And a fourth step of performing an electroless plating process for forming a final metallization layer on the resultant of the third step.

Polymers used in the present invention include polyimide, polyester-based polyethylene terephthalate polyester (PET) and aramid film, and are mainly used in flexible printed circuit boards (FPCBs). It refers to a film used for the manufacture of flexible copper clad laminate (FCCL) and electronic circuit pattern, or for electromagnetic interference (EMI) shielding.

The metallization method of the polymer material surface of the present invention may be applied to one or both sides of the polymer film. In addition, the metallization method of the present invention is not only one polymer film, but also two polymer films are laminated and metallized, and then two layers of film are declaminated to remove two single-sided metallized polymer films. It can manufacture. In addition, the metallization method of the present invention by adhering another polymer film (e.g. PET) to the polymer film (e.g., polyimide film) for the single-sided metallization treatment to deposit a metal film on the surface and then another polymer By removing the film, a metal coating layer may be formed on the surface of the polymer film of different types.

In one specific embodiment, as shown in Figure 1, the metallization method of the surface of the polymer material of the present invention, first, the process (Unwinding) to constantly supply a polymer film to be plated; Degreasing process for removing contaminants on the surface of the plated body by using a degreasing solution; Spray washing to clean the degreasing solution and contaminants remaining on the surface; A surface modification process (Surface Modifiaction) for facilitating the adsorption of noble metal particles, such as a catalyst when forming a metal bonding layer; Ultrasonic washing step for removing reaction product and treatment solution; A pre-dip process for preventing instability of the catalyst solution due to water inflow and controlling pH and charge of the modified polymer surface; Activation process of adsorbing catalyst particles such as noble metal on the polymer surface; Acceleration to accelerate the reduction of the noble metal catalyst component in the form of a salt on the surface after the catalytic treatment in the form of metal particles; A washing process for washing the accelerated solution from the surface of the plated body; Electroless plating process for depositing a metal bonding layer; It consists of a washing process for cleaning the plated surface. The metal bonding layer formed through wet surface modification and electroless plating forms the final metal coating layer through electroplating or additional electroless plating, and then the surface is prevented from corrosion. It consists of a washing process to remove the remaining rust preventive solution, a drying process to remove the remaining aqueous solution on the surface, and rewinding the produced polymer film.

The degreasing process is performed at 30 to 70 ° C. in an alkaline compound of 10 to 50 g / l of alkali metal carbonate, 10 to 50 g / l of phosphate, and 1 to 3 g / l of surfactant (Surfactant). The polymer material substrate is deposited for 1-5 minutes. The alkali metal is sodium (Na), potassium (K) and the like, and the surface active agent is sodium alkyl sulfonate (SAS), sodium alkyl sulfate sodium (AS), sodium olefin sulfonate (AOS), alkyl bezen sulfonate (LAS) Anionic surfactants, cationic surfactants, neutral surfactants and the like can be used. The degreasing process is generated during polymer film manufacturing or handling to remove by-products, dust or contaminants remaining on the surface. In particular, in the polymer film production process, in order to remove contaminants blocking the extremely fine capillaries or cavities formed naturally on the surface, the hydrophobic polymer surface is hydrophilized and the surface active agent mentioned above is added by adding the surface active agent mentioned above. Should be lowered to improve the wettability of the polymer film and treatment solution. However, conventionally used degreasing solutions such as acetone or ethyl alcohol have a problem that it is difficult to uniform degreasing on the polymer film and the wettability of water may be lowered, which may adversely affect the adhesion between the metal film and the polymer film material. In the case of the degreasing process using the same alkaline compound, this problem can be solved.

The surface modification treatment solution for the surface modification treatment process is a mixed solution of 3 to 10 mol of alkali metal hydroxide, 50 to 200 ml of nitrogen compound and 1 to 5 g of surfactant per D.I.Water. The hydroxide is, for example, sodium hydroxide (NaOH), potassium hydroxide (KOH) and the like. The nitrogen compound includes an ammonium salt or an amine compound. The ammonium salt is, for example, ammonium salt substituted with an alkyl group or an aryl group, such as ammonium hydroxide, ammonium chloride, ammonium sulfate, ammonium carbonate or triethylammonium salt, tetraethylammonium salt, trimethylammonium salt, tetramethylammonium salt, trifluoroammonium salt, tetrafluoroammonium salt, or the like. to be. The amine compound is, for example, an aliphatic amine compound such as methylamine, ethylamine, dimethylamine, diethylamine, trimethylamine, ethylenediamine, diethylenetriamine, or urea and hydrazine derivatives. The surfactant may be anionic surfactants such as sodium alkyl sulfonate (SAS), sodium sodium sulfate ester (AS), sodium olefin sulfonate (AOS), alkyl bezen sulfonate (LAS), cationic surfactants, or neutral surfactants. Can be. Surface modification treatment is performed by depositing a polymer film in the surface modification treatment solution at 20 to 50 ° C. for about 2 to 6 minutes.

Through the surface modification process, the hydrophobic polymer film surface is converted to hydrophilic, and functional groups such as carboxyl group, amine group and hydroxyl group are introduced to the polymer film surface to facilitate the adsorption of metal ions and at the same time. By forming a fine cavity on the surface to increase the surface roughness (roughness), the deposited metal film is to improve the adhesion to the polymer surface.

The washing process serves to remove the remaining treatment solution and suspended matter on the surface, it is preferable to spray the washing water or ultrasonic or vibration stirring at the same time as the washing water to increase the cleaning effect. Impurities and suspended particles present in the wash water are continuously filtered through a filter and an ion exchange resin.

The surface activation process may use a colloidal solution containing a noble metal such as Pd, Pt, Ro, Rh, Ag, Au, or a noble metal complex ion, preferably Pd-Sn colloidal solution, Ag or Pd complex salt have. In a specific embodiment, the colloidal solution is 100 to 250 ml of hydrochloric acid per liter of non-ionic water (DI Water), 150 to 300 g of sodium chloride or potassium chloride, 5 to 60 g of tin chloride (SnCl ₂ ), and 0.1 to palladium chloride (PdCl ₂ ). The solution containing 2g is used, and the treatment conditions are 1 to 5 minutes at room temperature.

Before the surface activation process, the pre-dip process prevents the inflow of water and imparts stability of the noble metal catalyst, adjusts pH and surface charge, and increases the adsorption efficiency of the catalyst particles. The composition of the treatment solution contains 200 to 400 g of hydrochloric acid and a compound of sodium chloride or potassium chloride per liter of non-ionized water, and the treatment conditions are 1 to 5 minutes at room temperature.

The acceleration process is to improve the activity of the adsorbed Pd-Sn colloid and the like after the catalyst treatment process and the precipitation behavior of the electroless plating solution. Through this acceleration process, the Sn layer surrounding the colloidal particles is removed and only the adsorbed Pd catalyst remains, thereby making it easier to deposit the electroless metal film. In a specific implementation, a solution containing 50 to 150 ml of fluorate per liter of non-ionized water may be used as a solution for the acceleration process, and treated by depositing 1 to 3 minutes at room temperature.

The electroless plating process uses copper, nickel, palladium, gold or alloys thereof to form a metal film layer having excellent adhesion. The electroless plating solution can use commercial products with low internal stress and excellent precipitation characteristics.

After the electroless plated coating layer is formed, the surface of the electroless plated coating layer may be cleaned in the same manner as the above washing step, and further drying may be performed if necessary. The drying process may be performed by hot air, ultraviolet (UV) radiation or infrared (IR) radiation.

After the electroless plating process, an electroplating process may be further performed to form the final metallization layer. Copper electroplating with low internal stress can be used to improve adhesion in the electroplating process. Initial electroplating is carried out at 1 A / dm ² or less, preferably 0.1 to 0.6 A / dm ² .

After the electroplating process, the same washing and drying process as described above may be performed. In addition, when the anti-corrosion treatment of the copper plating surface is required, the anti-rust treatment after the electroplating process may be performed, and washing and drying may be performed.

By the above method, the present inventors were able to form a metal coating layer on the surface of the polymer material in one consistent process, and solved the problem of forming a uniform metal bonding layer, which had been a problem in the past.

In another aspect, the present invention relates to a polymer film produced by the above method.

The polymer film produced by the metallization method of the surface of the non-conductive polymer material of the present invention is an intermediate material that is used in a flexible printed circuit board (FPCB) because a uniform metal bonding layer is formed on the polymer material surface. It can be used as a film for manufacturing a flexible copper clad laminate (FCCL) and an electronic circuit pattern or a film for shielding electromagnetic interference (EMI).

Hereinafter, the present invention will be described in more detail with reference to Examples. The following examples are only intended to illustrate the present invention in more detail and are not intended to limit the present invention thereto.

Example  1: on the surface of polyimide film Electroless  Nickel plating Film layer  formation

According to the production method of the present invention, an electroless nickel plated film was formed on the surface of the polyimide film. The activated catalyst solution is a solution containing 100 to 250 ml of hydrochloric acid, 150 to 300 g of sodium chloride or potassium chloride, 5 to 60 g of tin chloride (SnCl ₂ ), and 0.1 to 2 g of palladium chloride (PdCl ₂ ) per liter of DI water. Nickel sulfate 20-30 g / l, sodium hypophosphite 20-25 g / l, adipic acid, lactic acid and acetic acid mixed complexing agent 20-30 g / l, stabilizer 1-5 mg / l An electroless nickel plating solution was used. The electroless nickel plated coating layer on the surface of the polyimide film thus prepared was observed with an electron microscope, which is shown in FIG. 2.

Example  2: on the surface of polyimide film Electroless Copper plating Film layer  formation

According to the production method of the present invention, an electroless copper plating film was formed on the surface of the polyimide film. The surface modification solution and the activated catalyst solution used were as described above, and the electroless copper plating used was copper sulfate 10-15 g / l, lotel salt 50-60 g / l, sodium hydroxide 10-15 g / l, reducing agent As a solution, a solution consisting of 20 to 30 ml / l of formalin solution and 5 to 10 mg / l of additive was used. The electroless copper plating layer on the surface of the polyimide film thus prepared was observed with an electron microscope, which is shown in FIG. 3.

Example  3: PET  On the film surface Electroless  nickel Plating layer  formation

An electroless nickel plating layer was formed on the PET film surface in the same manner as in Example 1. The electroless nickel plated coating layer on the surface of the PET film thus prepared was observed with an electron microscope, which is shown in FIG. 4.

Example  4 : PET  On the film surface Electroless  copper Plating layer  formation

An electroless copper plating layer was formed on the PET film surface in the same manner as in Example 2. The electroless copper plating layer on the surface of the PET film thus prepared was observed with an electron microscope, which is shown in FIG. 5.

Example 5  : On polyimide film surface Copper  formation

In the same manner as in Example 1, an electroless nickel plated layer having a thickness of about 150 nm was formed on the surface of the polyimide film as a bonding layer, and then a copper layer having a thickness of about 18 μm was formed by electroplating. The composition of the electroplating used was nickel sulfate 80 to 120 g / l, sulfuric acid 200 to 250 g / l, hydrochloric acid 40 to 60 ml / l, additives 5 to 10 ppm. The initial current density during the electrocopper plating process should be adjusted to about 0.1 to 0.6 A / dm ² , and when a thin copper layer was formed on the surface to lower the surface resistance, work was performed at a maximum of 8 to 9 A / dm ² . When working at a current density higher than that, the film burns due to resistance heat generation. The electroplated film on the surface of the polyimide film thus prepared was observed with an electron microscope, which is shown in FIG. 6.

As described above, the method of forming a metal film on the surface of the non-conductive polymer film of the present invention is a metal material of various surfaces of both sides or cross-section, which is used as an intermediate material of a flexible printed circuit board and a base material for shielding electromagnetic interference or metal circuit patterns. Films can be produced consistently and efficiently in one process and can produce a variety of products requiring metallization of polymer film materials with high productivity and low equipment cost.

Claims (6)

A first step of degreasing and washing to remove contaminants; A second step of performing a surface modification process for imparting roughness to the functional group and the surface of the polymer; A third step of performing a catalytic treatment and an activation process of adsorbing noble metal particles on the surface of the polymer and reducing them to metal particles; And a fourth step of performing an electroless plating process to form a final metallization layer. The method of claim 1, further comprising a fifth step of undergoing the electroplating process after the fourth step. The method according to claim 1 or 2, wherein the surface modification treatment solution of the second step comprises 3 to 10 mol of alkali metal hydroxide, 50 to 200 ml of nitrogen compound and 1 to 5 g of surfactant. The method according to claim 1 or 2, wherein the activation treatment solution of the third step is a solution containing a Pd-Sn colloidal solution, Ag complex salt or Pd complex salt. The method of claim 2, wherein the current density in the initial electroplating process of the electroplating process is 0.1 to 0.6 A / dm ² . A polymer substrate produced by the method of claim 1.

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