KR101001062B1 - flexible metal clad laminate for fine pattern - Google Patents

Abstract

By controlling the roughness and the surface shape of the metal conductive layer deposited on the polymer film to provide a flexible metal laminate advantageous for accurate micropattern formation.

The flexible metal laminate of the present invention has a polymer film, a metal seed layer formed on the polymer film by a vacuum deposition method, and a roughness Rz formed by wet plating on the metal seed layer on the upper surface of the metal seed layer, and having a first incident angle of 0.5 μm or less. When the amount of reflection of light incident on the surface of the film is I, and the amount of light incident on the surface of the second incident angle greater than the first incident angle is Ⅱ, a metal conductive layer having I / II equal to or less than 1.0 Include.

Flexible Printed Circuit Boards, Flexible Metal Laminates, Roughness, Reflectance

Description

Flexible metal clad laminate for fine pattern

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.

1 is a cross-sectional view showing the configuration of a flexible metal laminate according to a preferred embodiment of the present invention.

2A to 2C are cross-sectional views showing examples of concave-convex shapes of surfaces formed on top of flexible metal laminates;

3A to 3C are cross-sectional views schematically showing the etching property at the time of forming a fine pattern in the irregular shape of the surface formed on the upper portion of the flexible metal laminate.

4A to 4C are photographs showing fine pattern formation results according to examples of concave-convex shapes of surfaces formed on top of a flexible metal laminate.

<Description of Major Reference Marks in Drawings>

10. Polymer film 20. Metal seed layer 30. Metal conductive layer

100 ductile metal laminate 200 photoresist layer 300 mask

The present invention relates to a flexible metal laminate, and more particularly, to a flexible metal laminate having a surface shape advantageous for forming a fine pattern.

Recently, the demand for circuit boards using tape automated bonding (TAB), flexible print circuit (FPC), etc. is increasing as a circuit board for miniaturization and light weight of electronic devices. Until now, this type of circuit board has been used to attach a metal thin film to an adhesive such as an epoxy-based adhesive on a plastic plastic substrate.

However, in order to achieve high-density mounting of electronic devices, this type of circuit board is further thinned, and a technique of forming a metal layer without using an adhesive due to poor adhesion between the plastic substrate and the metal thin film is being investigated. For example, a method of forming a base metal film directly on a plastic substrate by thin film formation techniques such as vacuum deposition, sputtering and ion plating, and then depositing a metal plating layer on the metal film by electroplating or the like is well known.

When the flexible metal laminate is formed by the above-described method, a pattern is formed on the upper surface of the flexible metal laminate to produce various kinds of components. In this case, accurate etching is required to form an accurate pattern, and the etching property is required to form the surface of the flexible metal laminate. Related to illuminance

However, even if the surface roughness is the same, there is a difference in etching characteristics when forming the fine pattern according to the shape of the unevenness formed on the surface, and when only the roughness is controlled, there is a limit in forming an accurate fine pattern.

The present invention has been made to solve the above problems, in forming a fine pattern, in addition to the roughness, by applying the concept of light reflectance considering the shape of the irregularities formed on the surface of the flexible metal laminated plate advantageous for accurate fine pattern formation The purpose is to provide.

In order to achieve the above object, the flexible metal laminate for fine patterns according to the present invention has an illuminance Rz of 0.2 to 0.5 μm, and has a first incident angle and a reflection amount of light incident on the surface thereof as I, and the first When the amount of reflection of light incident on the surface with a second incident angle greater than the incident angle is Ⅱ, a metal conductive layer having I / II equal to or less than 1.0 may be provided to provide optimum etching property when forming a fine pattern.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in this specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly interpret the concept of terms in order to explain the invention in the best way possible. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

1 is a view schematically showing a cross section of a flexible metal laminate for a fine pattern according to a preferred embodiment of the present invention.

Referring to FIG. 1, the flexible metal laminate for a fine pattern according to the present embodiment is formed on the polymer film 10, the metal seed layer 20 made of a conductive metal, and the metal conductive layer formed on the metal seed layer 20. (30).

It is preferable that the polymer film 10 has bendability so as to be suitable for a flexible metal laminate, and is made of, for example, a polyimide film. The polyimide film has high heat resistance, flexibility, and excellent mechanical strength, and has a coefficient of thermal expansion similar to that of metal, and thus is widely used as a material of the flexible film 10.

The metal seed layer 20 is formed on one side of the polymer film 10 and is formed using a vacuum film forming method such as sputtering or ion plating. The above methods are preferable because they can increase the bonding strength.

Copper and copper alloys may be used as the material for forming the metal seed layer 20, or nickel, chromium, or nickel-chromium alloys may be used. However, the material for forming the metal seed layer in the present invention is not limited thereto, and of course, other materials may be employed.

The metal conductive layer 30 is formed on the metal seed layer 20 by electroplating and can be formed using a wet plating method, that is, an electrolytic plating method and an electroless plating method. The electroplating method is preferable because of the high film forming speed, low film forming cost, and high surface smoothness. In the case of using the electroplating method, the polymer film 10 having the metal seed layer 20 formed thereon is immersed in the wet plating solution, the power cathode is connected to the metal seed layer 20, and electricity is supplied between the positive electrode immersed in the wet plating solution. By depositing the metal wet conductive layer on the metal seed layer (20). In the case of using the electroless plating method, first, after the precipitation nuclei are attached to the metal seed layer 20 by a palladium salt solution or the like, the polymer film 10 is immersed in the electroless plating solution.

As the material of the metal conductive layer 30, copper or copper alloy is preferable in terms of electrical conductivity. However, the material of the metal conductive layer 30 is not limited thereto, and other metals may be employed. Of course.

Moreover, as for the roughness which is the surface characteristic of the metal conductive layer 30, 0.5 micrometer or less is preferable.

In forming the fine pattern, one of the factors that greatly influence the etching property in the performance of the flexible metal laminate is the roughness of the surface, that is, roughness. Therefore, it is preferable to form the metal conductive layer whose roughness Rz is 0.5 micrometer or less in order to favor formation of the micropattern of 50 micrometers or less.

Here, when wet plating the metal conductive layer 30 of the flexible metal laminate, the surface shape of the flexible metal laminate is adjusted according to the additive added to the electrolyte solution. For example, low molecular weight water-soluble celluose ethers, low molecular weight water-soluble polyalkylene glycol ethers, low molecular weight water-soluble polyethylene glycol ethers Additives such as soluble polyethyleneimine and water-soluble sulfonated organic sulfur compounds can be used to change the irregularities of the ductile laminate.

2A to 2C are cross-sectional views showing examples of the surface of a flexible metal laminate formed according to the above method.

Even if the illuminance is the same, the adhesion of the photomask is different when the fine pattern is formed depending on the uneven shape formed on the surface of the flexible metal laminate, and the amount of light reflection on the surface is also different.

Referring to FIGS. 2A to 2C, unevenness is severe in the case of FIG. 2A, and unevenness becomes smoother toward FIG. 2C. When forming a fine pattern, adhesiveness of the photomask is greater in the case of FIG. 2C than in FIG. Is advantageous.

In addition, looking at the amount of light reflection on the surface, both the large incident angle (B) of 70 degrees and the small incident angle (A) of 5 degrees, the reflection amount of the reflected light increases from 2a to 2c.

Referring to FIG. 2A, when the uneven shape is the same, at a large incident angle B of 70 degrees, light is blocked due to the height of the unevenness higher than the inclination of the incident light, thereby reducing the amount of light reflection than at a small incident angle A of 5 degrees. .

However, referring to FIG. 2C, when the uneven shape is the same, light scattered is added to the actual light reflection amount at a large incident angle B of 70 degrees to increase the amount of light reflection than the small incident angle A of 5 degrees.

By measuring the amount of light reflection on the surface of the flexible metal laminate using the method described above, it is possible to determine the shape of the irregularities formed on the surface.

Next, the influence of each uneven shape on the fine pattern formation will be described.

3A to 3C are cross-sectional views schematically illustrating etching property in a fine pattern according to the shape of irregularities formed on the surface of the flexible metal laminate.

Referring to FIGS. 3A to 3C, the flexible metal laminates 101, 102, 103 including a metal seed layer and a metal conductive layer formed on the polymer film, and a mask layer on the flexible metal laminates 101, 102, 103 are shown. As a photoresist layer 200 and a photomask 300 having a fine pattern of a desired shape are provided.

When the etching masks 201, 202, and 203 are provided in the photoresist layer 200 through exposure and development, in FIG. 3A, IR scattering is severe and the etching mask 201 is damaged. This is because when the etching in the next process, the shape of the desired fine pattern is damaged, there is a high probability that a non-etching interval occurs, so that a bad pattern may be generated without obtaining an accurate pattern. Therefore, the closer to the concave-convex shape of FIG. 3C than the concave-convex shape of FIG. 3A, the more advantageous it is to accurately form a desired fine pattern when etching.

Next, according to a preferred embodiment of the present invention using the embodiment and the comparative example of the flexible metal laminate having a different concavo-convex shape, the surface characteristics suitable for forming a fine pattern is embodied.

That is, as illustrated in FIG. 1, a flexible copper foil laminate in which the copper seed layer 20 and the copper conductive layer 30 are sequentially formed on the polyimide film 10 is prepared, and the incident angle is 5 degrees and 70 degrees. The amount of reflection of light was measured. Here, surface roughness Rz in each Example and the comparative example was 0.5 micrometer or less.

Table 1 is a table showing the results of measuring the amount of reflection of light according to the change of the irregular shape. Here, the 'reflected dose' is a standard measurement method of gloss and gloss of the American Society for Testing and Materials (ASTM), a standard method used internationally, that is, when tested according to ASTM D2457 and D523. It is a shame.

At an angle of incidence of 5 degrees
Reflective amount (Ⅰ) At an angle of incidence of 70 degrees
Reflective amount (Ⅱ) Real pattern photo Ⅱ / Ⅰ Example 1 110.0 175.9 Figure 4a 1.6 Example 2 117.5 133.1 Figure 4a 1.1 Comparative Example 1 46.8 14.4 4b 0.308 Comparative Example 2 70.7 1.7 4c 0.024 Comparative Example 3 61.7 1.9 4c 0.030

Referring to Table 1, first, Example 1 and Example 2 is closer to the concave-convex shape shown in FIG. 2C because the amount of light reflection at the 70 degree incident angle is greater than the amount of light reflection at the 5 degree incident angle. It can be seen that in Examples 1 to 3, the reflection amount of light at the 70 degree incidence angle is smaller than the reflection amount of light at the 5 degree incidence angle, which is close to the uneven shape shown in FIG. 2A.

To support this, the photograph showing the actual fine pattern formation result of the flexible metal laminates provided with the concave-convex shape of Example 1 and Example 2, as shown in Figure 4a, while the uniform cross section is formed without the remaining photoresist In FIG. 4B to FIG. 4C, a photograph showing the actual fine pattern formation result of the flexible metal laminate provided with the uneven shape of Comparative Examples 1 to 3 has an uneven cross section due to the occurrence of an unetched section. It is.

In addition, the amount of reflection of light at an angle of incidence of 70 degrees is preferably 10 or more, because when the amount of reflection of light is less than or equal to 10 at an angle of incidence of 70 degrees sensitive to the roughness of the flexible metal laminate, there is a high possibility of the straightness and the non-etching interval of the circuit. to be.

In addition, as shown in the results of the above-described examples and comparative examples, in order for a fine pattern to be formed in a desired shape without a non-etching interval occurring, a large amount of reflection of light at a large incident angle at a small incident angle, that is, It is preferable that the light reflection amount ratio (I / II) at a large incident angle is 1.0 or less.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited thereto and the present invention will be described by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

According to the present invention, in manufacturing a flexible metal laminate for fine patterns, the surface characteristics are roughness Rz of 0.5 µm or less, and the amount of light reflection at a large incident angle is larger than that of light at a small incident angle, that is, a large incident angle and By providing a metal conductive layer having a reflectance ratio of light at a small incident angle of 1.0 or more, etching property can be improved when forming a fine pattern.

In addition, it is possible to check the quality of the flexible metal laminate by using the amount of light reflection that appears differently depending on the uneven shape of the surface.

Claims (4)

In the flexible metal laminate for fine patterns, Polymer film; A metal seed layer formed on the polymer film by a vacuum deposition method; And Formed by wet plating on the metal seed layer, the surface roughness Rz is 0.5 μm or less, and the amount of reflection of light incident on the surface having a first incident angle is referred to as I, and a second incident angle larger than the first incident angle is defined as I. And a metal conductive layer having I / II equal to or less than 1.0 when the amount of reflection of light incident on the surface is II. The method of claim 1, And said first incident angle is 5 degrees, and said second incident angle is 70 degrees. delete The method of claim 1, The metal seed layer is made of any one of copper, nickel, chromium or alloys thereof, and the metal conductive layer is a flexible metal laminate, characterized in that made of copper or copper alloy.

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