Alloy composition, tiecoat layer formed from alloy composition, wiring layer, and flexible circuit board including same wiring layer

Abstract

The present invention relates to: a nickel-chromium-zinc (Ni-Cr-Zn) alloy composition comprising, with respect to the total weight of the composition, 60-94 wt% of Ni, 5-20 wt% of Cr, and 1-20 wt% of Zn; a tiecoat layer formed from the alloy composition; a wiring layer; and a flexible circuit board including the wiring layer.

Description

An alloy composition, a tie coat layer formed by the alloy composition, a wiring layer, and a flexible circuit board including the wiring layer

[0001] The present invention relates to a nickel-chromium-zinc (Ni-Cr-Zn) alloy composition, a tiecoat layer comprising the alloy composition, a metal wiring layer comprising the tiecoat layer, and a flexible circuit board comprising the metal wiring layer, and an electronic device and display comprising the same.

[0002] A printed circuit board (PCB) is a board that forms conductors such as copper on an insulating substrate to transmit electrical signals and operates by forming an electric circuit.

[0003] Flexible printed circuit boards (FPCB) are essential components for most electrical and electronic products, including computers, home appliances, aircraft, and automobiles. In particular, flexible printed circuit boards (FPCB) are used in wearable devices, flexible displays, small electronic devices, mobile phones, and other products that emphasize portability.

[0004] The above flexible circuit board is a printed circuit board based on flexible materials such as polyimide (PI), polyethylene terephthalate (PET), polydimethylsiloxane (PDMS), polyurethane, modified polyimide, liquid crystal polymer (LCP), etc., and unlike existing printed circuit boards, it has the characteristics of flexibility and thinness of the circuit board, chemical stability, thermal stability, and high mechanical strength, and is applied to electronic products that require high integration, light weight, and miniaturization.

[0005] Conventional methods for forming copper-clad laminates for flexible circuit boards include sputtering, which allows for the formation of extremely thin copper films for circuit pattern formation and offers significant advantages in implementing fine-pitch designs. However, the significantly low adhesion of copper deposited on such flexible circuit boards presents a challenge, leading to the insertion of a tiecoat layer at the interface between the flexible circuit board and the copper.

[0006] However, flexible circuit laminates using materials such as nickel-chromium (Ni-Cr) alloy, nickel-molybdenum (Ni-Mo) alloy, nickel-copper (Ni-Cu) alloy, nickel-molybdenum-vanadium (Ni-Mo-V) alloy, or nickel-molybdenum-niobium (Ni-Mo-Nb) alloy, which are used as conventional tie coat layers, have a problem in that they do not meet these requirements.

[0007] Korean Patent Publication No. 10-2014-0041080 discloses a flexible circuit copper-clad laminate comprising a polymer film, a tiecoat layer, and a copper layer, wherein the tiecoat layer is made of an alloy containing molybdenum, cobalt, and nickel. However, the adhesive strength with the flexible circuit board is insufficient.

[0008] Accordingly, there is a continuing demand for an alloy composition that has excellent bonding properties with copper as a tie coat layer on a flexible circuit board including a polymer film such as modified polyimide, liquid crystal polymer (LCP), etc., and has excellent etching properties and peel strength that enable the implementation of fine pitch patterns.

[0009]

[0010] The present invention provides an alloy composition for forming an alloy film on a printed circuit board based on a flexible material including a polymer film such as polyimide, polyethylene terephthalate (PET), polyurethane, polydimethylsiloxane (PDMS), modified polyimide (PM), and liquid crystal polymer (LCP), which has excellent bonding strength with copper and excellent properties such as etching properties and peel strength that enable implementation of a fine pitch pattern, and in particular, an alloy composition suitable for forming a tie coat layer of a flexible circuit board.

[0011]

[0012] The present invention provides a nickel-chromium-zinc (Ni-Cr-Zn) alloy composition comprising 60 to 94 wt% of nickel (Ni); 5 to 20 wt% of chromium (Cr); and 1 to 20 wt% of zinc (Zn) based on the total weight of the composition.

[0013] The above alloy composition may not contain molybdenum (Mo).

[0014] The above alloy composition may include 70 to 80 wt% of nickel (Ni), 10 to 15 wt% of chromium (Cr), and 10 to 15 wt% of zinc (Zn).

[0015] In addition, the present invention provides a tie coat layer comprising the alloy composition.

[0016] The above-mentioned tie coat layer may have an etching rate of 75 nm / sec to 100 nm / sec for FeCl3 etchant.

[0017] The above-mentioned tie coat layer may have an etching rate of 60 nm / sec to 90 nm / sec for CuCl2 etchant.

[0018] In addition, the present invention provides a wiring layer including the above-described tie coat layer; and a metal layer.

[0019] The above metal layer may be characterized by being formed by laminating one or more types selected from the group consisting of a copper film, an aluminum film, and a nickel-copper-titanium alloy film.

[0020] In addition, the present invention provides a flexible circuit board including a substrate layer; and the wiring layer.

[0021] The above-mentioned substrate layer may include at least one selected from the group consisting of polyimide, polyethylene terephthalate (PET), polyurethane, polydimethylsiloxane (PDMS), modified polyimide, and liquid crystal polymer (LCP).

[0022]

[0023] According to a nickel-chromium-zinc (Ni-Cr-Zn) alloy composition according to one embodiment of the present invention, by including nickel (Ni), chromium (Cr) and zinc (Zn) at a certain ratio with respect to the total weight of the composition, an alloy composition having high bonding strength to a flexible circuit board and having further improved etching properties can be provided.

[0024] In addition, the present invention can provide a tie coat layer, a wiring layer, and a flexible circuit board including the wiring layer that can be applied to a flexible display.

[0025]

[0026] FIG. 1 is a schematic diagram illustrating a laminated structure of a flexible circuit board including a nickel-chromium-zinc (Ni-Cr-Zn) alloy composition according to one embodiment of the present invention.

[0027] What each symbol represents is as follows:

[0028] 1: Flexible circuit board

[0029] 20: Wiring layer

[0030] 22: Metal layer

[0031] 21: Thai Court Floor

[0032] 10: Substrate layer

[0033]

[0034] The present invention relates to an alloy composition having high adhesive strength with a flexible circuit board and further improved etching properties by including nickel (Ni), chromium (Cr) and zinc (Zn) at a certain ratio relative to the total weight of the composition, a tie coat layer formed by the alloy composition, a wiring layer and a flexible circuit including the wiring layer. More specifically, the present invention relates to a nickel-chromium-zinc (Ni-Cr-Zn) alloy composition comprising 60 to 94 wt% of nickel (Ni), 5 to 20 wt% of chromium (Cr) and 1 to 20 wt% of zinc (Zn) relative to the total weight of the composition.

[0035]

[0036] Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. However, the following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the contents of the invention described above, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited to the matters described in these drawings.

[0037] As used herein, the terms "comprises" and / or "comprising" are used to mean that they do not exclude the presence or addition of one or more other components, steps, operations, and / or elements other than the components, steps, operations, and / or elements mentioned. Like reference numerals refer to like elements throughout the specification.

[0038]

[0039] FIG. 1 is a schematic diagram illustrating a laminated structure of a flexible circuit board (1) including a nickel-chromium-zinc (Ni-Cr-Zn) alloy composition according to one embodiment of the present invention.

[0040] Referring to FIG. 1, the present invention includes a tiecoat layer (21) including the nickel-chromium-zinc (Ni-Cr-Zn) alloy composition, and the wiring layer (20) of the present invention includes the tiecoat layer (21) and a metal layer (22).

[0041] In addition, the present invention can provide a flexible circuit board (1) including a substrate layer (10) and the wiring layer (20), which can be applied to a flexible display or a stretchable display, and in the present invention, all of these are referred to as flexible circuit boards.

[0042] In a flexible display or flexible electronic device, a substrate having flexibility and stretchability (referred to as a flexible circuit board in the present invention) is used, and a polymer substrate can be used as the substrate's base layer. When forming copper wiring on a polymer substrate included in such a flexible circuit board, a bonding layer called a tie coat layer can be further included for the purpose of establishing a strong bonding force between the wiring and the substrate. For example, in a Flexible Copper Clad Laminate (FCCL) or a Flexible Printed Circuit Board (FPCB), when a binary alloy such as nickel-copper (Ni-Cu) or nickel-chromium (Ni-Cr) is used as the lower layer of a copper wiring, there is a problem that the bonding force and stretchability for a base layer including a flexible polymer material such as polyimide or liquid crystal polymer are somewhat poor, and in particular, nickel-chromium (Ni-Cr) alloy has poor etching properties, which can cause many problems in patterning.

[0043] Accordingly, the nickel-chromium-zinc (Ni-Cr-Zn) alloy composition of the present invention not only has high adhesive strength with a polymer substrate as nickel, chromium, and zinc are included in a certain ratio, but also has excellent bonding strength with copper, which is a metal wiring on the upper part of the tie coat layer, thereby further improving etching properties.

[0044]

[0045] Nickel-chromium-zinc (Ni-Cr-Zn) alloy composition

[0046] The present invention provides a nickel-chromium-zinc (Ni-Cr-Zn) alloy composition comprising 60 to 94 wt% of nickel (Ni); 5 to 20 wt% of chromium (Cr); and 1 to 20 wt% of zinc (Zn) based on the total weight of the composition.

[0047] The above nickel (Ni) is a main component of the alloy composition according to the present invention, and is suitable as an alloy composition for forming a tie coat layer due to its excellent diffusion prevention properties for copper. In one or more embodiments, the nickel (Ni) may be included as a remainder of the contents of chromium (Chromium) and zinc (Zinc) to be described later based on the total weight of the alloy composition, and specifically, the nickel (Ni) may be included in an amount of 60 to 94 wt% based on the total weight of the alloy composition, and more preferably, the nickel (Ni) may be included in an amount of 70 to 80 wt% based on the total weight of the alloy composition. When the nickel (Ni) is included in an amount of less than 60 wt% based on the total weight of the composition, the bonding strength with the polymer substrate may be reduced, and when the nickel (Ni) is included in an amount of more than 94 wt%, the etching rate may be reduced in an iron chloride-based etchant or a copper chloride-based etchant.

[0048] The above chromium (Cr) is a metal with excellent corrosion resistance and heat resistance, and exhibits a process reaction with a very large solubility limit in nickel, making it suitable for alloying. The crystal structure of Ni-Cr is FCC, which has high toughness, making it suitable as an alloy composition for forming a tie coat layer.

[0049] In one or more embodiments, the chromium (Cr) may be included in an amount of 5 to 20 wt%, more preferably 10 to 15 wt%, based on the total weight of the alloy composition. When chromium (Cr) is included in an amount of less than 5 wt%, it is not suitable for maintaining thermal, mechanical, and electrical properties for high reliability, and when it exceeds 20 wt%, there is a problem of reduced etchability, which may cause residue during pattern formation. In addition, a Cr2O3 oxide film may be densely formed on the bonding interface, which may reduce bonding strength.

[0050]

[0051] The zinc mentioned above is provided to improve etchability when forming a micropattern, and may play a role in improving the bonding strength of the alloy film, and is therefore suitable as an alloy composition for forming a tie coat layer. Specifically, since zinc is contained in the alloy film, the potential difference with copper is reduced, so that the residue can be improved when wet etching the double film structure, and the diffusion barrier function of copper may not be significantly inhibited. Zinc may play a role in preventing oxidation of Cr and forming a zinc oxide compound to increase the bonding strength with the base layer of the substrate. Specifically, when Zn is included in the alloy composition, the elastic modulus of the bonding layer is lowered, so that the amount of plastic deformation is increased during a peel test, and there is an effect of increasing the peeling strength.

[0052] In one or more embodiments, the zinc may be included in an amount of 1 to 20 wt%, more preferably 10 to 15 wt%, based on the total weight of the alloy composition. If the zinc is included in an amount of less than 1 wt%, etchability may be reduced, resulting in residues when forming a pattern. If the zinc is included in an amount of more than 20 wt%, the etch rate of the alloy composition may significantly increase, making it difficult to form a fine pattern.

[0053] The above alloy composition may not contain molybdenum (Mo).

[0054] For example, in a display device, when pure titanium or a molybdenum alloy is used as the lower layer (referred to as a tie coat layer in the present invention) of copper wiring on a polymer substrate, it is not suitable for inclusion in the wiring layer (20) of a flexible device due to the lack of ductility of the titanium and molybdenum alloys.

[0055]

[0056] Thai coat layer (21)

[0057] The present invention provides, in addition to the nickel-chromium-zinc (Ni-Cr-Zn) alloy composition, a tiecoat layer comprising the alloy composition. The alloy film of the present invention may refer to a tiecoat layer.

[0058] In one or more embodiments, the thickness of the alloy film (tie coat layer) formed from the nickel-chromium-zinc (Ni-Cr-Zn) alloy composition can be adjusted in various ways within a range that does not deteriorate the physical properties of the nickel-chromium-zinc (Ni-Cr-Zn) alloy composition according to the present invention, and is therefore not particularly limited.

[0059]

[0060] For example, the tiecoat layer may have an etching rate of 75 nm / sec to 100 nm / sec for FeCl3 etchant. Further, for example, the tiecoat layer may have an etching rate of 60 nm / sec to 90 nm / sec for CuCl2 etchant. If the etching rate for the FeCl3 etchant is less than 75 nm / sec or the etching rate for the CuCl2 etchant is less than 60 nm / sec, the etching rate is low, resulting in a large difference in etching rates with respect to the metal layer, particularly the copper layer, which is not suitable for forming a wiring layer such as a double film.

[0061]

[0062] Wiring layer (20) and flexible circuit board (1)

[0063] In addition, the present invention provides a wiring layer (20) including the tiecoat layer (21); and a metal layer (22). In addition, the present invention provides a flexible circuit board (1) including a substrate layer (10) and the wiring layer (20). That is, the flexible circuit board (1) including the tiecoat layer may sequentially include the substrate layer (10), the tiecoat layer (21) of the present invention, and the metal layer (22).

[0064]

[0065] The above-mentioned substrate layer (10) may be a flexible polymer substrate, and specifically, may include at least one selected from the group consisting of polyimide, polyethylene terephthalate (PET), polyurethane, polydimethylsiloxane (PDMS), modified polyimide, and liquid crystal polymer (LCP). Preferably, it may include a liquid crystal polymer (LCP).

[0066] The wiring layer (20) of the present invention includes a tiecoat layer (21) and a metal layer (22) formed of a nickel-chromium-zinc (Ni-Cr-Zn) alloy composition on the substrate layer (10), and the tiecoat layer (21) can be formed in a thin film form. The wiring layer (20) has a structure in which a metal layer (22) is included on the tiecoat layer (21), and each layer can be formed through a physical vapor deposition (PVD) method such as sputtering deposition or a chemical vapor deposition (CVD) method such as plasma, thermal energy, or atomic layer deposition.

[0067] The above wiring layer (20) can be etched according to the purpose, and for example, can be etched with one or more types of copper wet etchants (copper etchants) selected from the group consisting of persulfate, hydrogen peroxide, copper chloride, and iron chloride, and preferably can be etched with a CuCl2 solution or FeCl3 solution.

[0068] The above metal layer (22) may be characterized by being formed by laminating one or more selected from the group consisting of a copper film, an aluminum film, and a nickel-copper-titanium alloy film. For example, the wiring layer (20) may have a structure consisting only of the tiecoat layer and the copper film, or may have a structure in which the tiecoat layer, the copper film, and the nickel-copper-titanium (Ni-Cu-Ti) alloy film are laminated, or may have a structure in which the tiecoat layer, the aluminum film, and the nickel-copper-titanium (Ni-Cu-Ti) alloy film are laminated.

[0069] The thickness of the above wiring layer (20) is not particularly limited, as it can be adjusted in various ways within a range that does not deteriorate the properties of the nickel-chromium-zinc (Ni-Cr-Zn) alloy composition according to the present invention.

[0070]

[0071] Hereinafter, specific embodiments of the present invention will be described. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided solely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the invention of the scope of the invention. The present invention is defined solely by the scope of the claims.

[0072]

[0073] Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-6: Preparation of alloy compositions

[0074] Alloy compositions of Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-6 were prepared so as to have the composition ratios shown in Table 1 below.

[0075] (Wt%) Nickel (Ni) Chromium (Cr) Zinc (Zn) Molybdenum (Mo) Example 1-1801010-Example 1-2751015-Example 1-3701515-Comparative Example 1-17030--Comparative Example 1-28020--Comparative Example 1-3651025-Comparative Example 1-4502525-Comparative Example 1-565305-Comparative Example 1-680--20

[0076]

[0077] Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-6: Preparation of alloy film

[0078] The alloy compositions of Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-6 were deposited by sputtering on each Liquid Crystal Polymer (LCP) substrate under the following conditions to manufacture alloy films (tie coat layers) of Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-6.

[0079]

[0080] Sputtering conditions

[0081] Vacuum level reached: 4.0*10-6 Torr or less

[0082] Ar gas pressure: 2 mTorr

[0083] Ar gas flow rate: 60 sccm

[0084] Sputtering power: 200W

[0085] Substrate temperature: room temperature

[0086]

[0087] Experimental Example: Measurement of Etching Rate and Peel Strength

[0088]

[0089] (1) Etchability

[0090] On a Liquid Crystal Polymer (LCP) substrate, the alloy films of Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-6 were deposited by sputtering to a thickness of 200 nm, and then immersed in a 45°C CuCl2 solution and a 45°C FeCl3 solution, respectively, by half etching. The remaining thickness was measured to calculate the etching rate, and the results are shown in Table 2 below.

[0091]

[0092] (2) Measurement of bonding strength

[0093] An alloy film was deposited on a Liquid Crystal Polymer (LCP) substrate by sputtering, and a copper metal layer (seed layer) was electroplated to a thickness of approximately 18 μm. Then, peel strength was measured using Z05TN from Zwick Roell.

[0094] The lead width was 1 mm, the required angle was 90°, and after measuring 8 times each, the average value of the remaining values ​​was calculated excluding the maximum and minimum values, and the results are shown in Table 2.

[0095]

[0096] Alloy film Alloy composition Etching rate (nm / sec) Ehant: FeCl3 Etching rate (nm / sec) Ehant: CuCl2 Peeling strength (N) Example 2-1 Example 1-183781.48 Example 2-2 Example 1-286.3811.42 Example 2-3 Example 1-380.4721.44 Comparative example 2-1 Comparative example 1-133.516.31.04 Comparative example 2-2 Comparative example 1-25329.30.98 Comparative example 2-3 Comparative example 1-3113.4102.30.81 Comparative example 2-4 Comparative example 1-4106.299.10.75 Comparative example 2-5 Comparative example 1-528.123.10.96Comparative Example 2-6Comparative Example 1-673551.07

[0097]

[0098] Referring to Table 2, in the case of the alloy film manufactured with the alloy composition according to the example, since it shows excellent results in terms of both etching rate and peel strength, it can be confirmed that it has a high bonding force to a polymer substrate and has an effect of further improving etching properties by including a nickel-chromium-zinc (Ni-Cr-Zn) alloy composition including 60 to 94 wt% of nickel (Ni), 5 to 20 wt% of chromium (Cr), and 1 to 20 wt% of zinc (Zn) based on the total weight of the composition. On the other hand, in the case of the comparative example, it can be confirmed that not only is the etching rate significantly low or excessively high, making it unsuitable for etching, but also the peel strength is low, resulting in poor bonding force to a polymer substrate.

[0099]

[0100] According to a nickel-chromium-zinc (Ni-Cr-Zn) alloy composition according to one embodiment of the present invention, by including nickel (Ni), chromium (Cr) and zinc (Zn) at a certain ratio with respect to the total weight of the composition, an alloy composition having high bonding strength to a flexible circuit board and having further improved etching properties can be provided.

[0101] In addition, the present invention can provide a tie coat layer, a wiring layer, and a flexible circuit board including the wiring layer that can be applied to a flexible display.

Claims

1. Regarding the total weight of the composition, Nickel (Ni) 60 to 94 wt%; 5 to 20 wt% chromium (Cr); and A nickel-chromium-zinc (Ni-Cr-Zn) alloy composition comprising 1 to 20 wt% of zinc (Zn).

2. In claim 1, A nickel-chromium-zinc (Ni-Cr-Zn) alloy composition that does not contain molybdenum (Mo).

3. In claim 1, Nickel (Ni) 70 to 80 wt%; 10 to 15 wt% chromium (Cr); and Containing 10 to 15 wt% of zinc (Zn); Nickel-chromium-zinc (Ni-Cr-Zn) alloy composition.

4. A tie coat layer comprising an alloy composition according to any one of claims 1 to 3.

5. In claim 4, The above-mentioned tie coat layer is A tie coat layer having an etching rate of 75 nm / sec to 100 nm / sec for FeCl3 etchant.

6. In claim 4, The above-mentioned tie coat layer is A tie coat layer having an etching rate of 60 nm / sec to 90 nm / sec for CuCl2 etchant.

7. A wiring layer comprising a tie coat layer of claim 4; and a metal layer.

8. In claim 7, The above metal layer is a wiring layer characterized in that one or more types selected from the group consisting of a copper film, an aluminum film, and a nickel-copper-titanium alloy film are laminated.

9. Base layer; and A flexible circuit board comprising the wiring layer of claim 7.

10. In claim 9, A flexible circuit board, wherein the substrate layer comprises at least one selected from the group consisting of polyimide, polyethylene terephthalate (PET), polyurethane, polydimethylsiloxane (PDMS), modified polyimide, and liquid crystal polymer (LCP).

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