KR100764300B1 - flexible metal clad laminate and method for manufacturing the same - Google Patents

Abstract

The flexible metal laminate of the present invention is a raw material used in a flexible circuit board, and includes a polymer film, a dissimilar metal layer, a metal seed layer, and a metal conductive layer, and the (111) plane texture fraction provided on the metal conductive layer, I (111). / I _all is 0.5 ~ 0.65, the (200) plane texture fraction, I (200) / I _all is characterized in that more than 0.15.

Flexible printed circuit boards, flexible metal laminates, flexible copper foil laminates, electroplating

Description

Flexible metal clad laminate and method for manufacturing the same

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.

Figure 2 is a flow chart showing the manufacturing process of the flexible metal laminate according to the present invention in order.

<Description of Major Reference Marks in Drawing>

100. Polymer film 110. Dissimilar metal layer

120. Metal seed layer 130. Metal conductive layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible metal laminate, and more particularly, to a flexible metal laminate, which is a main material of a flexible circuit board used in small electronic devices such as mobile phones and PDAs.

In general, a printed circuit board is connected to or supported by various printed circuit boards according to the circuit design of electrical wiring, and is often compared to neural circuits of electronic products. With the remarkable growth of electronic devices such as notebook computers, mobile phones, PDAs, small video cameras, and electronic notebooks, printed circuit boards are becoming more important for high integration and miniaturization of products.

Printed circuit boards are rigid-flexible printed circuit boards and rigid-flexible printed circuit boards that combine two types of rigid printed circuit boards (PCBs) and flexible printed circuit boards, depending on their physical characteristics. It is divided into a multi-flexible printed circuit board similar to the substrate.

Here, flexible metal laminates, which are the raw materials for flexible circuit boards, are used in digital home appliances such as mobile phones, digital camcorders, laptops, and LCD monitors. Recently, demand is increasing rapidly due to their high flexibility and low weight.

A flexible metal laminate is a laminate of a metal conductive layer and a resin layer. The flexible metal laminate is used for a part that requires flexibility and flexibility, and contributes to miniaturization and weight reduction of electronic devices. As a method of manufacturing such a flexible metal laminate, a method of bonding a film-like polyimide to a thin metal conductive layer by using an adhesive such as an epoxy resin or a method of directly applying a polyimide aqueous solution onto a metal conductive layer is prepared. Can be mentioned. However, the former manufacturing method may cause deterioration of properties due to the adhesive, while the latter manufacturing method has problems such as curling, generation of ripples, foaming of the resin layer, and oxidation deterioration of copper foil. Therefore, there is a need for another method for producing a flexible metal laminate that does not cause defects.

In order to improve the above-mentioned drawback, the method of controlling the roughness of a surface by surface-treating a resin layer, or introducing a dissimilar metal layer between a resin layer and a metal conductive layer is used. In addition, in order to facilitate formation of the metal conductive layer, a method of forming a metal seed layer and then electrodepositing the metal conductive layer by an electroplating method is used. The metal conductive layer formed by the above method is determined in addition to the conductive layer forming method, depending on the surface treatment state of the resin layer, the state of the dissimilar metal layer, the metal seed layer formed by the sputtering method, and the method of forming the metal conductive layer. . This texture has a close relationship with the strength of the metal conductive layer and the bonding force with the resin layer, which is a substrate, and also affects the initial physical properties and the strength of the physical property deterioration with time.

The present invention has been made under the technical background as described above, and an object thereof is to provide a flexible metal laminate having excellent strength of the metal conductive layer and bonding strength with other substrates by controlling the texture of the metal conductive layer and a manufacturing method thereof.

In order to achieve the above object, in the flexible metal laminate according to the present invention, the adhesive force between the polymer film and the metal conductive layer is enhanced by increasing the texture fraction of the metal conductive layer.

A flexible metal laminate according to an aspect of the present invention is a raw material used for a flexible circuit board, and includes a polymer film, a dissimilar metal layer, a metal seed layer, and a metal conductive layer, and the (111) plane provided on the metal conductive layer. The aggregate fraction of the aggregate, if I (111) / I _all is 0.5 to 0.65, (200), the aggregate fraction of the aggregate, I (200) / I _all is characterized in that more than 0.15.

According to another aspect of the present invention, there is provided a method of manufacturing a flexible metal laminate, comprising: preparing a polymer film by surface treating a polymer film with activated ions in a vacuum atmosphere, coating a dissimilar metal on the surface-treated polymer film; Forming a metal seed layer on the polymer film provided with a dissimilar metal layer by sputtering, and contacting a plating solution to the surface on which the metal seed layer is formed, thereby forming an aggregate structure fraction of the (111) surface on the metal seed layer, I (111) / I _all is 0.5 ~ 0.65, forming a metal conductive layer having a texture fraction of the (200) plane, I (200) / I _all is 0.15 or more.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. 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 schematic cross-sectional view of a flexible metal laminate according to a preferred embodiment of the present invention.

Referring to FIG. 1, the flexible metal laminate according to the present embodiment may include a heterogeneous metal layer 110 made of metal, a metal seed layer 120 deposited on a heterogeneous metal layer 110, and the metal on the polymer film 100. And a metal conductive layer 130 electrodeposited on the seed layer 120.

Preferably, the polymer film 100 is made of a polyimide film having flexibility to be suitable for a flexible metal laminate. 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 for flexible films.

The dissimilar metal layer 110 is vacuum deposited on the surface of the polymer film 100. The dissimilar metal layer 110 is interposed between the polymer film 100 and the metal seed layer 120 to be deposited on the dissimilar metal layer 110 to serve as a barrier and a bonding strength between the two layers. Therefore, even when the flexible metal laminate is subjected to high temperature treatment, the metal seed layer 120 may be prevented from being peeled from the polymer film 100.

It is preferable to control the thickness of the dissimilar metal layer 110 to a range that does not peel off due to the penetration of the plating liquid after the high temperature treatment or when the circuit is formed. In addition, the dissimilar metal layer 110 may be interposed between the polymer film 100 and the metal seed layer 120, and thus the use of the heterogeneous metal layer 110 does not need to be too thick. Preferably, the thickness of the dissimilar metal layer 110 is 50 to 200 mm 3. When the thickness of the dissimilar metal layer 110 is too thin, it is weak to high temperature and poor in corrosion resistance, and may be peeled off due to plating solution penetration after high temperature treatment or when forming a circuit.

As the material of the dissimilar metal layer 110, a metal having good bonding strength and reactivity with other materials, for example, chromium, nickel, or an alloy of chromium and nickel is preferable.

The metal seed layer 120 is formed on the dissimilar metal layer 110 by various vacuum deposition methods including sputtering. Preferably, the metal seed layer 120 is copper (Cu) or a copper alloy. And, the thickness is adjusted to have an adhesive force of a predetermined range or more with the metal conductive layer 130 which will be described later. Preferably, the thickness of the metal seed layer 120 is 500 kPa or more.

The metal conductive layer 130 is formed on the metal seed layer 120 by an electroplating method. That is, after the metal seed layer 120 is formed by vacuum deposition, the metal seed layer 120 is immersed in the plating solution so that the metal conductive layer 130 can be transferred onto the metal seed layer 120 by an electrochemical reaction. Preferably, the metal conductive layer 130 is copper or an alloy layer of copper.

The metal conductive layer 130 is formed to have an aggregate structure having excellent physical properties. Specifically, the degree to which the (111) plane is aligned in the horizontal direction with respect to the lower layer plane, that is, the texture fraction I [111] / I _all of the (111) plane of the metal conductive layer 130 is 0.5 to 0.65, The texture fraction (I [200] / I _all ) of the (200) plane should be 0.15 or more. It will be described later that the metal conductive layer 130 having such a condition has excellent physical properties.

On the other hand, aggregated structure means one aggregate composed of many crystal grains having the same crystal orientation in a polycrystalline material. For example, the texture of the crystal orientation (100) plane refers to the texture of the material in orderly alignment with the axis in a specific direction (direction perpendicular to the plane of 100). Metal sheets having two or more textures exhibit important properties in physical properties.

The degree of texture of the polycrystalline material can be judged by the texture fraction. The aggregate fraction used in the present embodiment is shown in Equation 1.

Where I (hkl) is the intensity at the (hkl) plane of the test specimen, and I _all is the intensity at the (111) plane, i.e., I (111), I (200), and I (220). And I (311). Here, the intensity is the relative intensity of the X-rays that are diffracted by the X-rays transmitted through the polycrystalline material according to the crystal structure.

In the metal conductive layer 130, if the texture fraction value of the specific (hkl) face is larger than the average value of the other faces, the metal conductive layer 130 is relatively inclined to the texture in which the [hkl] direction of the crystal is perpendicular to the substrate. It means that it has a lot, and the closer the value of the texture fraction is to 1, the better the crystal of the metal conductive layer 130 is grown in the [hkl] direction.

Next, the manufacturing method of the flexible metal laminate according to the present invention will be described in detail.

2 is a process flowchart schematically showing a process of manufacturing a flexible metal laminate according to a preferred embodiment of the present invention.

First, the polymer film 100 is prepared (step S10), and a dissimilar metal layer 110 made of metal is formed by a vacuum film forming method such as sputtering, vacuum deposition, or ion plating (step S20). Specifically, the polymer film 100 is brought into a chamber in which vacuum is maintained, and dry pre-treatment with a plasma in which gas such as argon, oxygen, nitrogen, or a mixture thereof is injected to modify the surface of the polymer film. Subsequently, the heterogeneous metal layer 110 is formed on the polymer film 100 by various vacuum deposition methods including sputtering from a metal target (a metal target of nickel-chromium alloy element) in an inert gas atmosphere such as argon and maintaining the vacuum degree in the chamber. do.

Subsequently, a metal seed layer 120 made of copper or a copper alloy is formed on the dissimilar metal layer 110 (step S30). The metal seed layer 120 maintains the vacuum in the chamber and sputters from the copper or copper alloy target in an inert gas atmosphere such as argon to form the metal seed layer 120 on the dissimilar metal layer 110.

Subsequently, a metal conductive layer 130 is formed on the metal seed layer 120 (step S40). The metal conductive layer 130 uses an electroplating method using a plating solution. When the metal conductive layer 130 is formed by the electroplating method, the texture of the metal conductive layer 130 is adjusted according to the following variables.

When stacking the dissimilar metal layer 110 and the metal seed layer 120 on the polymer film 100, the modified pretreatment conditions of the polymer film, that is, gas type, mixing ratio, power and pretreatment, and pressure during lamination , The distance between the polymer film and the metal target, the lamination rate, and the temperature of the polymer film. In addition, when plating the metal conductive layer 130, the temperature of the plating liquid, the composition of the plating liquid, and the current density during electroplating are changed. The grain size, surface state, etc. of the dissimilar metal layer 110 and the metal seed layer 120 thus formed change the texture of the metal conductive layer 130.

In addition, by providing a separate magnet outside the plating bath containing the plating liquid containing the metal ion to be plated, by applying a magnetic field from the magnet may be changed the texture of the metal conductive layer 130. At this time, the Lorentz force applied to the metal ions is used to move the metal ions in a constant direction.

The relationship between the magnetic field applied to the plating bath and the Lorentz force according to it is shown in Equation 2 below.

F = q (E + v × B)

Where F is the Lorentz force, q is the charge of the metal ion, v is the velocity vector of the metal ion, and B is the magnetic field vector.

This Lorentz force causes the metal ions to be plated to grow with a certain orientation.

On the other hand, the present invention will be described in more detail by explaining a more specific experimental example of the present invention. However, the present invention is not limited to the following experimental examples, and various forms of embodiments may be implemented within the scope of the appended claims.

In the present experimental example, a heterogeneous metal layer and a metal seed layer are sequentially formed on the polymer film, and then a metal conductive layer is formed on the samples by electroplating. At this time, by controlling the texture of the metal conductive layer to specify a suitable range of texture fraction that can strengthen the bonding force between the two layers.

 In other words, during the lamination process of the metal seed layer, the pressure during lamination, the distance between the polymer film and the metal target, the lamination speed, and the temperature of the polymer film are changed, and during the plating process of the metal conductive layer, the temperature, composition and electroplating of the plating solution. The change of the current density in the metal structure of the conductive layer will be examined.

Then, the crystal structure of the metal conductive layer is examined by X-ray diffraction method. Specifically, the presence or absence of texture and degree of texture of the (111), (200), (220) and (311) planes of the crystals arranged horizontally with respect to the surface of the polymer film on which the metal seed layer was formed were confirmed. . The degree of aggregate structure is the sum of the aggregated strengths of the (111) planes, (200) planes, (220) planes, and (311) planes of the specimen prepared according to the experimental example, that is, the aggregate structure of each (hkl) plane for I _all . This can be seen from the texture fraction (see Equation 1), which is the ratio of intensity, i (hkl).

Table 1 shows the texture intensity (I) of each surface measured by X-ray diffraction method, and the intensity at each surface, that is, the value of I (hkl), is based on the texture strength of the (111) plane as reference value 1. Normalized value. In addition, Io is the strength of the texture of the standard powder sample.

I (111) I (200) I (220) I (311) I (111) / Io I (200) / Io Experimental Example 1 1.0 0.14 0.11 0.10 0.74 0.11 Experimental Example 2 1.0 0.22 0.13 0.18 0.66 0.14 Experimental Example 3 1.0 0.30 0.15 0.11 0.64 0.19 Experimental Example 4 1.0 0.42 0.18 0.15 0.57 0.24 Experimental Example 5 1.0 0.37 0.23 0.35 0.51 0.19

In addition, to test the peel strength (A) at 90 degrees by taking five samples according to each experimental example for the flexible metal laminate prepared according to the experimental example described above, the samples were left for one week and then left at 90 degrees Peel strength (B) was tested, and the samples were also subjected to high temperature treatment in an oven at 150 ° C. for 1 week, followed by testing the peel strength (C) at 90 ° and the results are shown in Table 2 below.

Peel Strength A [kgf / cm] Peel Strength B [kgf / cm] Peel Strength C [kgf / cm] Experimental Example 1 0.74 0.54 0.13 Experimental Example 2 0.76 0.60 0.17 Experimental Example 3 0.68 0.66 0.28 Experimental Example 4 0.71 0.70 0.30 Experimental Example 5 0.70 0.69 0.33

Referring to Table 1 and Table 2, in Experimental Example 1 and Example 2, I (111) / Io value and I (200) / Io value was 0.66 ~ 0.74, 0.11 ~ 0.14, respectively, and the initial Peel strength was as high as 0.74kgf / cm and 0.76kgf / cm, but after 1 week of high temperature in peeling strength and oven at 150 ℃, peel strength was less than 20% of initial peel strength Lowered to.

On the other hand, in the case of Experimental Examples 3 to 5, I (111) / Io value and I (200) / Io value was 0.51 ~ 0.64, 0.19 ~ 0.24, respectively, the initial peel strength of these samples is 0.68kgf / cm , 0.71kgf / cm, high as 0.70kgf / cm, and after 1 week of standing, the peel strength and high temperature treatment in an oven at 150 ℃ was maintained at 40% or more of the initial peel strength.

Therefore, when the results of the above experimental example are summed up, when the metal conductive layer is formed by electroplating on the polymer film on which the metal seed layer is formed, the metal ions are oriented and electrodeposited to form an aggregate structure, wherein (111) The texture fraction of the face, I (111) / I _all is to have a value of 0.5 ~ 0.65, and the texture fraction, I (200) / I _all of the (200) plane is preferably controlled to have a value of 0.15 or more.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person 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, a heterogeneous metal layer formed by vacuum deposition on a polymer film and a metal seed layer formed by sputtering, and a metal conductive layer formed on the upper portion of the polymer film by electroplating are formed on the polymer film. The texture of the aggregate can be controlled to improve the strength of the metal conductive layer and to maintain constant physical properties even after elapse of time.

Claims (9)

In the flexible metal laminate comprising a polymer film, a dissimilar metal layer, a metal seed layer and a metal conductive layer, The textured fraction of the (111) plane of the metal conductive layer, I (111) / I _all is 0.5 ~ 0.65, the textured fraction of the (200) plane, I (200) / I _all is characterized in that more than 0.15 Flexible metal laminates. The method of claim 1, The dissimilar metal layer is a flexible metal laminate, characterized in that made of nickel (Ni), chromium (Cr) or an alloy thereof. The method of claim 1, The metal seed layer and the metal conductive layer is a flexible metal laminate, characterized in that made of copper or copper alloy. In the method of manufacturing a flexible metal laminate used for a flexible circuit board, Preparing a polymer film; Forming a dissimilar metal layer on the polymer film; Forming a metal seed layer on the polymer film on which the dissimilar metal layer is formed; And Contacting the plating liquid to the surface on which the metal seed layer was formed, the texture fraction of the (111) plane on the metal seed layer, I (111) / I _all is 0.5 ~ 0.65, the texture fraction of the (200) plane, Forming a metal conductive layer I (200) / I _all is 0.15 or more; manufacturing method of a flexible metal laminate comprising a. The method of claim 4, wherein The dissimilar metal layer is a method of manufacturing a flexible metal laminate, characterized in that formed in a vacuum film forming method. The method of claim 5, The vacuum film forming method is any one of a sputtering method, vacuum deposition method, ion plating method characterized in that the manufacturing method of the flexible metal laminate. The method of claim 4, wherein The metal seed layer is a method of manufacturing a flexible metal laminate, characterized in that formed by the sputtering method. The method of claim 4, wherein The texture structure of the metal conductive layer is determined by controlling the pre-treatment conditions of the polymer film, the pressure upon lamination of the dissimilar metal layer and the metal seed layer, the distance between the polymer film and the metal target, the lamination rate, and the temperature of the polymer film. A method for producing a flexible metal laminate. The method of claim 4, wherein The aggregate structure of the metal conductive layer is determined by controlling the temperature of the plating liquid, the composition of the plating liquid and the current density during electroplating.

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