KR20060021990A - Surface treatment method of polyimide film using atmospheric plasma - Google Patents

Abstract

The present invention relates to a surface treatment method of a polyimide film using atmospheric pressure plasma.

The surface treatment method of the polyimide film of the present invention is a surface treatment for 1 to 5 minutes at 150-300W atmospheric pressure strength on the polyimide film, and improves hydrophilicity by introducing a polar functional group containing oxygen into the hydrophobic polyimide film. In order to improve the wettability of the polyimide film by increasing the surface free energy, the adhesion between the polyimide film and the metal is improved.

Atmospheric Plasma, Polyimide, Surface Treatment

Description

Surface treatment method of polyimide film using atmospheric pressure plasma {SURFACE TREATMENT METHOD OF POLYIMIDE FILM USING ATMOSPHERIC PLASMA}             

1 is a view showing a schematic diagram of an atmospheric pressure plasma apparatus of the present invention,

2 is an FT-IR result of the polyimide film surface-treated with the atmospheric pressure plasma of the present invention,

3 is an AFM result of the polyimide film surface-treated with the atmospheric pressure plasma of the present invention,

4 is a view showing the adhesive strength of the polyimide film surface-treated with the atmospheric pressure plasma of the present invention.

The present invention relates to a surface treatment method of a polyimide film using atmospheric pressure plasma, and more specifically, to improve the adhesion between a polyimide film and a metal by using an atmospheric pressure plasma generated from a fixed atmospheric pressure plasma apparatus at an optimal condition. It is related with the surface treatment method of a mid film.

Polyimides have excellent physical properties such as excellent mechanical properties, chemical resistance, chemical resistance, high heat resistance, and electrical insulation, and thus are used as electric / electronic heat-resistant films, liquid crystal alignment films, semiconductor materials, molded part materials, adhesives, and the like. In particular, recently, polyimides have been in the spotlight as flexible printed circuit boards (FPCBs), tape automated bondings (TABs), and heat-resistant heat-resistant coatings as heat-resistant films for electric and electronic applications. Among them, FPCB can be bent and moveable circuit, 3D circuit configuration and high-density wiring can be widely used in computers and peripherals, communication equipment, medical equipment, aerospace electronic equipment. At this time, when used as an insulating layer of the FPCB, the polyimide film and the conductor are generally bonded using an adhesive such as epoxy and polyimide.

However, since the polyimide represented by the following Chemical Formula 1 does not have a polar group on the surface, the adhesion force between the polyimide film and the metal is reduced, resulting in peeling between the polyimide film and the metal.

Therefore, durability according to the adhesiveness of the polyimide film is required, and studies for improving the adhesiveness of such polyimide films have been actively conducted. As an example, Korean Patent Laid-Open Publication No. 195-0029297 discloses a surface treatment method of a polyimide that is performed by an amine treatment step of dipping a polyimide in an amine solution and a drying step of drying an amine-treated polyimide. In addition, Korean Patent Laid-Open Publication No. 1999-0045681 discloses a method for improving the adhesion of an aromatic polyimide film, comprising a heat-resistant aromatic polyimide / metal (or an aromatic polyimide film and a metal or metal oxide layer formed on the film). Metal oxide) composite plate, the polyimide film is composed of an aromatic polyimide resin and an aluminum containing material dispersed in the polyimide resin and the dispersed amount is 1 to 1,000 ppm relative to the amount of the polyimide film. A method of forming a metal oxide layer on a polyimide film without adhesive is disclosed. In addition, in Korean Patent Laid-Open Publication No. 2002-0077188, a surface of a polyimide film having a biphenyltetracarboxylic acid component is subjected to contact treatment with a solution containing potassium permanganate and / or sodium permanganate and potassium hydroxide and / or sodium hydroxide, It has been proposed a surface treatment method of a polyimide film which improves adhesion to metal by acid treatment.

However, the methods for improving the adhesion of the conventional polyimide film is mainly a method of modifying the surface by chemical treatment on the surface of the polyimide film.

Therefore, the inventors of the present invention, as part of the method for improving the adhesion of the polyimide film, the atmospheric pressure plasma generated from the atmospheric pressure plasma apparatus is fixed to the optimum conditions of the plasma intensity, processing time, processing speed, the distance between the electrode and the polyimide specimen The present invention was completed by confirming that the polyimide film was used for surface treatment and the adhesion of the polyimide film was improved.

An object of the present invention is to provide a surface treatment method of a polyimide film using atmospheric pressure plasma.

It is another object of the present invention to provide a method for surface treatment of polyimide film using atmospheric pressure plasma generated from an atmospheric pressure plasma device in which plasma intensity, processing time, processing speed, and distance between electrodes and polyimide specimens are fixed under optimum conditions. will be.

In order to achieve the above object of the present invention, the present invention is a surface-treated for 1 to 5 minutes at 150-300W atmospheric plasma strength to a polyimide film, to provide a surface treatment method of a polyimide film using atmospheric plasma.

The atmospheric pressure plasma is generated from an atmospheric pressure plasma generator using a mixed gas composed of argon gas 98 to 99% and oxygen gas 1 to 2% as a carrier gas, and the atmospheric pressure plasma generator is treated at 1 to 60 mm / min. It is carried out at a speed, characterized in that the distance between the electrode and the polyimide specimen is fixed to 1 to 10 mm.

Hereinafter, the present invention will be described in detail with reference to the drawings.

The present invention provides a surface treatment method of a polyimide film using atmospheric pressure plasma treated on the polyimide film at atmospheric pressure intensity of 150 to 300 W for 1 to 5 minutes.

1 is a schematic diagram of an atmospheric pressure plasma apparatus of the present invention, wherein the frequency is fixed at 13.56 MHz to stably form plasma, and the injection amount of carrier gas is kept constant using a mass folw controller (MFC).

The atmospheric pressure plasma apparatus of the present invention uses a mixed gas composed of 98 to 99% of argon gas and 1 to 2% of oxygen gas as a carrier gas, and performs a treatment speed at 1 to 60 mm / min. The distance between the specimens is characterized in that fixed to 1 to 10 mm.

FIG. 2 is an FT-IR result of the polyimide film surface-treated with an atmospheric pressure plasma of the present invention, in which peaks of 3,600 to 3,200 cm ⁻¹ region due to OH stretching of carboxylic acid are observed. Therefore, the polyimide film is surface-treated using atmospheric pressure plasma by the manufacturing method of this invention, and the polar functional group containing oxygen is introduce | transduced into the surface of a polyimide film. Therefore, hydrophilicity can be effectively provided to the surface of the polyimide film, thereby improving adhesion.

3 is an AFM result of the polyimide film surface-treated with the atmospheric pressure plasma of the present invention. As the plasma intensity increases, the surface roughness Ra of the polyimide film increases. In particular, when the plasma intensity is 200 W, the surface roughness Ra Represents the maximum value. Therefore, by surface treatment using atmospheric pressure plasma on the polyimide film, the surface roughness (Ra) of the polyimide film is increased to improve the adhesion to the metal.

In addition, the surface treatment method of the polyimide film surface-treated with the atmospheric pressure plasma of the present invention increases the free energy of the surface, thereby improving the wettability of the polyimide film can improve the adhesion to the metal.

4 is a view showing the adhesive strength of the polyimide film surface-treated with the atmospheric pressure plasma of the present invention. In the surface treatment method of the polyimide film using the atmospheric pressure plasma of the present invention, by confirming the result that the peel adhesion strength increases as the pressure of the plasma pressure increases, the effect of the polyimide film has improved the conventional problem of weak adhesion with the metal. have.

In addition, the surface treatment method of the polyimide film using the atmospheric pressure plasma of the present invention is performed at room temperature and atmospheric pressure without the need for a separate vacuum apparatus under atmospheric pressure, so that the stability of the process is given and the process can be performed continuously, thereby reducing the manufacturing cost. There is this.

Hereinafter, the present invention will be described in more detail with reference to Examples.

This embodiment is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

<Example 1>

50 μm polyimide film (Du Pont Co., Kapton) represented by Chemical Formula 1 was cut to a size of 25 × 100 mm, washed three times using an ultrasonic wave containing methanol, and dried in a vacuum oven to be pretreated. Thereafter, the surface of the pretreated polyimide film was plasma treated.

In the plasma treatment, atmospheric pressure plasma (ATMOSTM-multi, Plasmart) was used ( FIG. 1 ), and argon (99%) gas containing 1% oxygen was used as a carrier gas. The frequency was fixed at 13.56 MHz, which stably formed the plasma, and the voltage was 150 W. The injection amount of carrier gas was maintained at 5 L / min using a mass flow controller, and the distance between the electrode and the polyimide film was fixed at 4 mm without arcing. The treatment time was 1 min, and the treatment speed was treated once at 60 mm / min.

<Example 2>

In the plasma treatment process, argon (99%) gas containing 1% oxygen was used as a carrier gas, and the plasma frequency was fixed at 13.56 MHz, the distance between the electrode and the polyimide film was 4 mm, the treatment time was 1 min, and After fixing at a treatment rate of 60 mm / min, it was carried out in the same manner as in Example 1 except that the surface treatment was performed once by adjusting the plasma voltage to 200 W.

<Example 3>

In the plasma treatment, argon (99%) gas containing 1% oxygen was used as a carrier gas, and the plasma frequency was fixed at 13.56 MHz, the distance between the electrode and the polyimide film was 4 mm, the treatment time was 1 min, and After fixing at a treatment rate of 60 mm / min, it was carried out in the same manner as in Example 1, except that the surface treatment once by adjusting the plasma voltage to 300 W.

Comparative Example 1

In the plasma treatment process, argon (99%) gas containing 1% oxygen was used as a carrier gas, and the plasma frequency was fixed at 13.56 MHz, the distance between the electrode and the polyimide film was 4 mm, the treatment time was 1 min, and After fixing at a treatment rate of 60 mm / min, it was carried out in the same manner as in Example 1, except that the surface treatment once by adjusting the plasma voltage to 0 W.

Experimental Example 1 Surface Characteristic Analysis

1. Surface Characteristic Analysis Using FT-IR

In order to determine the change of functional groups on the surface of the atmospheric pressure plasma surface-treated polyimide film prepared in Examples 1 to 3 and Comparative Example 1 was analyzed by the following method.

The polyimide film treated above was analyzed using a FT-IR spectrum (Digilab FTS-165 spectrometer) to which a KRS-5 reflection element was attached, and the results are shown in FIG. 2 .

As shown in FIG. 2, in the film of Comparative Example 1 which was not treated with atmospheric plasma, a peak of 3,600 to 3,200 cm ⁻¹ region due to OH stretching of carboxylic acid not observed was observed in the film treated in Examples 1 to 3 Confirmed.

Therefore, by confirming the introduction of oxygen-containing polar functional groups on the surface of the polyimide film, excellent adhesion can be imparted by effectively hydrophilizing the surface through plasma surface treatment.

2. Surface Characteristic Analysis Using AFM

Atmospheric plasma treated polyimide surface morphology (Morphology) was analyzed using AFM (Atomic Force Microscopy, Digital instruments Inc. Nanoscope III mocroscope). AFM measurement was performed at room temperature and normal pressure, and surface roughness (Ra) was calculated | required using the profile. The results are shown in Fig.

As shown in FIG. 3, it was confirmed that the surface roughness Ra increases as the voltage, that is, the plasma intensity increases during the atmospheric pressure plasma treatment, and the surface roughness Ra of the polyimide film is maximum when the plasma intensity is 200 W. Value was shown.

Experimental Example 2 Surface Free Energy Measurement

The change in surface free energy of the polyimide films prepared in Examples 1 to 3 and Comparative Example 1 was confirmed using a contact angle measuring device. In the present invention, the surface free energy of the polyimide film was measured at room temperature using a sessile drop method (SEO 300A). At this time, the folding liquid used for measuring the contact angle was used as the distilled water and diiodomethane (diiodomethane) and the obtained measured value represents the average value of 10 times. The results are shown in Table 1 below.

Change in contact angle characteristic of plasma treated polyimide film (unit: mJ / m ² ) Test piece Example 1 Example 2 Example 3 Comparative Example 1

Specific component,

29.62 32.28 33.1 6.52 London dispersive component,

42.26 43.17 37.09 40.01 Surface free energy,

71.88 73.45 70.19 46.53

As shown in Table 1, it can be observed that the nonpolar elements of the surface free energy do not change significantly according to the atmospheric pressure plasma surface treatment, while the polar elements increase greatly, and the surface free energy increases with the increase of the polar elements. You can check it. This is due to the increase in the oxygen-containing polar functional group according to the atmospheric pressure plasma treatment, the hydrophilicity is greatly increased on the surface of the hydrophobic polyimide film to increase the polar component of the surface free energy. In addition, it was confirmed that the polar element and the surface free energy of the film treated with the output 200W showed the largest value.

Experimental Example 3 Component Measurement of Film

The chemical composition of the film according to the surface treatment of the polyimide film prepared in Examples 1 to 3 and Comparative Example 1 was analyzed through XPS (ESCALAB MK-II). The X-ray source used for XPS measurement was Mg Kα, the pressure in the chamber was adjusted to 10 ^-1 to 10 ^-9 torr.

As a result, the peak of oxygen characteristics of the polyimide treated with atmospheric plasma surface treatment increased with the increase of plasma intensity compared to the untreated film. This means that oxygen-containing functional groups such as C = O are effectively introduced into the polyimide film surface. It is judged because

Experimental Example 4 Adhesion Measure

In order to measure the adhesion of the polyimide film prepared in Examples 1 to 3 and Comparative Example 1 was carried out by the following method.

In order to measure the adhesion of the surface-treated polyimide film, a metal to be provided as an adhesive surface was used 50 μm copper foil (Fukuda), and as an adhesive an epoxy resin (DGEBA, Kukdo Chemical Co., Ltd., YD-128). , EEW = 185-190 g / mol, d = 1.16 g / cm ³ ), and 4,4-diamino diphenyl methane was used as a curing agent for epoxy.

Thereafter, the adhesive force of the polyimide film and the copper foil according to the atmospheric pressure plasma surface treatment was measured by using a universal testing machine (Universal Testing Machine, Lloyd LR5K) in accordance with ASTM 1876-72. Adhesive specimens were measured after the epoxy resin as an adhesive was introduced between the polyimide film and the copper foil and cured at 120 ° C. for 2 hours. The size of the adhesive specimen was 25 × 100 mm and the constant head speed was measured at 254 mm / min. Accordingly, peel strengths, which are adhesive properties of polyimide / copper foil according to plasma voltage, are shown in FIG. 4 .

As shown in FIG. 4, the peel adhesive strength increased as the plasma voltage, that is, the plasma intensity, increased, and in particular, the polyimide film prepared in Example 2 having a plasma voltage of 200 W showed the maximum peel adhesive strength.

As we saw above,

First, the surface treatment method of polyimide using the atmospheric pressure plasma of the present invention introduces a polar functional group to the hydrophobic surface of the polyimide film, gives hydrophilization through surface etching, improves the wettability, and implements excellent adhesion property with metal. Provided a polyimide film,

Second, the surface treatment method of the polyimide of the present invention, by using the atmospheric plasma carried out at room temperature and atmospheric pressure without the need for vacuum, the stability of the process is imparted, and the atmospheric pressure plasma treatment is performed continuously, thereby reducing the process time It can shorten and lower the manufacturing cost.

Although the present invention has been described in detail only with respect to the embodiments described, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical spirit of the present invention, and such modifications and variations belong to the appended claims. .

Claims (4)

The surface treatment method of a polyimide film, The surface treatment method of the polyimide film using atmospheric pressure plasma characterized by surface-treating the said polyimide film by 150-300 W of atmospheric pressure intensity for 1 to 5 minutes. The polyimide film using atmospheric pressure plasma according to claim 1, wherein the atmospheric pressure plasma is generated from an atmospheric pressure plasma generator using a mixed gas comprising argon gas 98 to 99% and oxygen gas 1 to 2% as a carrier gas. Surface treatment method. The surface treatment method of a polyimide film using atmospheric pressure plasma according to claim 1, wherein the atmospheric pressure plasma is generated from an atmospheric pressure plasma generating apparatus performed at a treatment speed of 1 to 60 mm / min. The surface treatment method of a polyimide film using atmospheric pressure plasma according to claim 1, wherein the atmospheric pressure plasma is generated from an atmospheric pressure plasma generator in which a distance between the electrode and the polyimide specimen is fixed at 1 to 10 mm.

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