KR20160084689A - Flexible Printed Circuit Board Comprising Hard Coating Layer and Fabrication Method thereof - Google Patents

Abstract

The present invention relates to a flexible printed circuit board comprising a hard coating layer and a manufacturing method thereof and, more specifically, to a flexible printed circuit board comprising a hard coating layer placed between an insulation substrate, a circuit pattern, and a connection pattern. The flexible printed circuit board has excellent adhesive force between a substrate and a metal layer so that durability and reliability are improved. Therefore, the flexible printed circuit board may be utilized for various small and medium-sized electronic devices including a smartphone, a display, a solar cell, an electronic paper, and so forth.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a flexible printed circuit board including a hard coating layer,

The present invention relates to a flexible printed circuit board having excellent interfacial adhesion and a method of manufacturing the same.

The printed circuit board is divided into a hard printed circuit board, a flexible printed circuit board, and a rigid printed circuit board, which are connected to each other according to the circuit design of the electric wiring on the printed circuit board. .

Among them, a flexible printed circuit board (FPCB) is advantageous in that the flexible printed circuit board (FPCB) has a thin thickness and excellent bendability because a component or a copper foil circuit is mounted on a flexible insulating film such as polyimide.

The printed circuit board is classified into a single-sided board, a double-sided board, and a multi-layer board according to the number of wirings of the wiring circuit. Such a substrate is used as a base for connecting various components mounted on a circuit design. The single-sided substrate is mainly used for a product having a relatively simple circuit configuration such as a radio, a telephone, and a simple measuring instrument. A double-sided substrate is mainly used for a color television, a VTR, a facsimile For products with relatively complicated circuits, multilayer boards are used in high-precision equipment such as computers, electronic exchangers, and high-performance communication equipment.

A flexible printed circuit board is produced by cutting a copper-clad laminated copper-clad laminated board to a predetermined working size, laminating three or four sheets of the copper-clad laminated board to a predetermined working size, making a through-hole through mechanical drilling using an expensive NC drill, Thereafter, the through holes are subjected to electroless plating and electrolytic plating in the conventional robot method to impart conductivity to the through holes, and a circuit pattern is formed by dry film laminating, exposure, developing and etching processes.

The number of through holes is increasing in flexible printed circuit boards due to the high performance and high density of products. However, since the substrate material of the flexible printed circuit board is made of a plastic material such as polyimide, and circuit patterns formed on the flexible printed circuit board and connection patterns formed in the through via holes are metal such as copper or aluminum, when forming a metal layer on the substrate or through- There is a problem in that the quality of the substrate deteriorates due to the problem of deterioration of the adhesion between the substrate and the substrate.

In order to improve the adhesion between the substrate and the metal layer, there is a method of pre-treating the surface of the substrate by dry pretreatment using a plasma or an ion beam, and then interfacial adhesion improving layer made of a metal component is inserted between the metal layer and the substrate. Methods for increasing the area are actively researched.

Korean Patent Registration No. 10-0764300 discloses a method in which a surface of a polymer film as a substrate is subjected to a dry pretreatment with a plasma and then a dissimilar metal layer made of nickel, chromium, or an alloy thereof is formed and then a metal layer is formed to form a dissimilar metal layer And a method of enhancing the adhesion between the substrate and the metal layer by acting as a set organization.

Korean Patent Laid-Open Publication No. 10-2014-0090961 discloses a polyimide resin which is an insulating substrate contains rubber particles which can be removed by a desmearing process, so that fine grooves are formed on the surface after the hole processing to improve the bonding strength with the seed layer And the like.

These patents show that although the adhesive strength is improved, the effect is not sufficient, and the circuit pattern formed on the insulating substrate can still be electrically conducted through the through hole, so that the problems caused by the defective circuit and insufficient durability can not be solved.

Korean Patent Registration No. 10-0764300 Korean Patent Publication No. 10-2014-0090961

As a result of various studies on the material and the manufacturing method so that the excellent interfacial adhesion can be sufficiently maintained, the Applicant has confirmed that the above problem can be solved by adding a hard coat layer containing inorganic particles between the substrate and the metal layer Thereby completing the invention.

It is therefore an object of the present invention to provide a flexible printed circuit board with improved interfacial adhesion by disposing a hard coating layer containing inorganic particles between a substrate and a circuit pattern made of a metal component and a connection pattern.

Another object of the present invention is to provide a method of manufacturing a flexible printed circuit board having excellent adhesion strength, excellent scratch resistance and heat resistance, and high reliability and bending durability even under frequent bending or severe conditions.

According to an aspect of the present invention, there is provided a semiconductor device comprising: an insulating substrate on which at least one via hole is formed; A circuit pattern formed on the insulating substrate; And a connection pattern formed to electrically connect the circuit pattern, including an inner circumferential surface of the via hole, and a hard coating layer between the insulating substrate and the circuit pattern and the connection pattern.

The hard coat layer may include inorganic particles, a resin, a curing agent, and a solvent.

Wherein the inorganic particles are at least one oxide, nitride or carbide selected from the group consisting of Si, Al, Sn, Sb, Ta, Ce, La, Fe, Zn, W, Zr, In, Ti, Lt; / RTI >

At this time, the inorganic particles may have an average particle diameter of 0.01 to 3 탆.

The hard coating layer may have a thickness of 1 to 100 탆.

At this time, the circuit pattern and the connection pattern are composed of a metal layer or a seed layer / metal layer.

The present invention also relates to a method of manufacturing a flexible printed circuit board

(S1) punching an insulating substrate to form a via hole passing therethrough;

(S2) forming a hard coating layer on the upper surface of the insulating substrate and the inner peripheral surface of the via hole;

(S3) forming a seed layer on the hard coat layer

(S4) forming a metal layer on the seed layer; And

(S5) patterning the hard coat layer, the seed layer and the metal layer to form a circuit pattern and a connection pattern, respectively.

The flexible printed circuit board according to the present invention can arrange a hard coating layer containing inorganic particles between an insulating substrate and a circuit pattern and a connecting pattern to improve interfacial adhesion and maintain reliability of bending durability and circuit performance of the entire substrate.

The flexible printed circuit board obtained through such a manufacturing method can be applied to various small and medium electronic apparatuses such as a smart phone, a display, a solar cell, and an electronic paper.

1 is a cross-sectional view illustrating a flexible printed circuit board according to an embodiment of the present invention.
2 is a flowchart illustrating a method of manufacturing a flexible printed circuit board according to an embodiment of the present invention.
3 is a cross-sectional view illustrating a manufacturing procedure of a flexible printed circuit board according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the drawings. Hereinafter, a repeated description, a known function that may obscure the gist of the present invention, and a detailed description of the configuration will be omitted. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings and the like can be exaggerated for clarity.

1 is a cross-sectional view illustrating a flexible printed circuit board according to an embodiment of the present invention.

1, a flexible printed circuit board includes a circuit pattern 14a formed on an insulating substrate 11, at least one via hole 12 formed in the insulating substrate 11, The connection pattern 14b is formed on the via hole 12 passing through the insulating substrate 11 to electrically connect the connection pattern 14b.

At this time, the circuit pattern 19a is stacked on the insulating substrate 11, and the connection pattern 19b is formed so as to cover a predetermined region of the insulating substrate 11 so as to include it on the inner peripheral surface of the via hole 12. [

Particularly, in the present invention, the hard coating layers 13a and 13b are provided to further increase the adhesive force between the insulating substrate 11 and the circuit pattern 19a and the connection pattern 19b in the above structure. The hard coating layers 13a and 13b contain inorganic particles as essential components and the inorganic particles improve the adhesion between the circuit pattern 19a and the connection pattern 19b made of a metal and the insulating substrate 11, Thereby securing an advantage of preventing scratches.

The inorganic particles may be at least one selected from the group consisting of Si (silicon), Al (aluminum), Sn (tin), Sb (antimony), Ta (tantalum), Ce (cerium), La (lanthanum) A nitride or a carbide selected from the group consisting of W (tungsten), Zr (zirconium), In (indium), Ti (titanium), Nb (niobium), Y (yttrium) . Specifically selected from the group consisting of SiO ₂ , SiC, Si ₃ N ₄ , TiO ₂ , ZrO ₂ , Al ₂ O ₃ , AlN SnO ₂ , Sb ₂ O ₅ , Nb ₂ O ₃ , Y ₂ O ₃ , One paper is available.

The inorganic particles may have an average particle diameter of 0.01 to 3 mu m, preferably 0.05 to 2 mu m, more preferably 0.1 to 1 mu m. In this case, if the particle size is too small, sufficient adhesion improving effect can not be expected. On the contrary, if it is too large, the surface of the hard coat layer can not be precipitated or uniform in quality.

The inorganic particles may be used in an amount of 5 to 50% by weight, preferably 10 to 25% by weight, based on 100% by weight of the composition for forming the hard coat layer. If the content of the inorganic particles is less than the above range, the adhesion strength to be obtained can not be ensured. On the other hand, if the content exceeds the above range, cracks and circuit deformation due to the difference in thermal expansion between adjacent layers can be caused.

In addition to the inorganic particles, the hard coat layer according to the present invention includes a resin, a curing agent and a solvent.

Each composition will be described below.

The resin to be contained in the hard coat layer of the present invention is not particularly limited and may be any one having a suitable viscosity to form a uniform thickness and capable of exhibiting excellent hardness, adhesive strength and heat resistance together with the inorganic particles when forming a layer.

Specific examples of the resin include polyimide resin, liquid crystal polymer, polytetrafluoroethylene resin, polyethylene resin, polypropylene resin, polyester resin, polyamide resin, acrylic resin, vinyl chloride resin, celluloid resin, epoxy resin, A melamine resin, an alkyd resin, a silicone resin, a urethane resin, a phenoxy resin, a polyvinyl acetal resin, a polyamideimide resin, a polyether sulfone resin, a polysulfone resin and a combination thereof.

The content of the resin may be 20 to 90% by weight, preferably 40 to 50% by weight, based on 100% by weight of the composition for forming a hard coat layer. At this time, when the resin is used in the above-mentioned content range, it is preferable because the layer formation is easy.

The curing agent is not particularly limited as long as it has a function of curing the composition for forming the hard coat layer as described above. Specifically, phenol type curing agent, naphthol type curing agent, active ester type curing agent, benzoxazine type curing agent, cyanate ester type curing agent, Can be used. A phenol-based curing agent, a naphthol-based curing agent or an active ester-based curing agent is preferably used.

The content of the curing agent may be 1 to 50% by weight, preferably 5 to 30% by weight, based on 100% by weight of the composition for forming a hard coat layer. If the thickness is less than the above range, the durability of the formed layer may be deteriorated, and conversely, if the thickness exceeds the above range, thickness control may be difficult.

Any solvent may be used as long as it can dissolve or disperse the above-mentioned composition, and the solvent is not particularly limited in the present invention. Examples thereof include ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone, acetic ester solvents such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate and carbitol acetate, cellosolve and butyl Carbitol solvents such as carbitol; aromatic hydrocarbon solvents such as toluene and xylene; and amide solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone. The solvent may be used alone, or two or more solvents may be used in combination.

Such a solvent can be used as the balance to satisfy 100 wt% of the total composition, but is preferably 30 to 90 wt%. Such a content is selected in consideration of dispersion stability of the composition and easiness of process in the production process (for example, applicability).

The hard coat layer composition may contain other additives as needed. Such other additives may be selected from the group consisting of a dispersant, a viscosity modifier, a curing accelerator, a flame retardant, an anti-aggregation agent, a defoaming agent, a leveling agent, an adhesion promoter, a colorant and a combination thereof.

The thickness of the hard coat layer is preferably in the range of 1 to 100 mu m, more preferably in the range of 1 to 50 mu m, and further preferably in the range of 1 to 20 mu m. If it is less than the above range, sufficient adhesion improving effect can not be obtained. On the other hand, if it exceeds the above range, pattern formation and overall substrate quality may be deteriorated.

The insulating substrate on which the hard coating layer is formed is a space in which various electric and electronic parts are connected to each other by receiving electric power and is a supporting space. Therefore, the glass transition temperature (T _g ) And excellent in heat resistance, as well as in flexibility and insulation. In addition, the chemical resistance and moisture resistance must also be excellent.

At this time, the material of the insulating substrate is not particularly limited in the present invention, and any material can be used as long as it is used as a material of a known flexible printed circuit board. Typical examples of the polymer include polyimide (PI), polystyrene (PS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polytetrafluoroethylene (PTFE) ), Fluorinated ethylene propylene (FEP), perfluoroalkoxy (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), ethylene-chlorotrifluoroethylene copolymer Polychlorotrifluoroethylene (PCTFE), and a combination thereof. Preferably, polyimide or polyethylene terephthalate is used.

At this time, the thickness of the insulating substrate differs depending on the use and is not particularly limited, but is preferably 10 to 150 mu m, more preferably 25 to 50 mu m. If it is less than the above range, it is difficult to support or handle the circuit, and conversely, if it exceeds the range, the flexibility becomes poor.

The circuit pattern and the connection pattern are layers for electrical conduction, and have a structure in which a metal layer or a seed layer and a metal layer are laminated.

The metal layer is not particularly limited in the present invention, and any known metal may be used. Typically, a metal such as aluminum, iron, cobalt, nickel, copper, zinc, ruthenium, palladium, silver, tin, (Sn), platinum (Pt), gold (Au), and combinations thereof, preferably aluminum (Al), copper (Cu), or silver (Ag).

At this time, the thickness of the metal layer is 3 to 70 占 퐉, preferably 3 to 50 占 퐉, more preferably 3 to 30 占 퐉. In this case, in consideration of formation of a thick circuit, the thickness is preferably in the range of 3 to 70 mu m, and more preferably in the range of 3 to 30 mu m in consideration of the fine wiring formation. The thickness of the metal layer may vary depending on the apparatus to which the flexible printed circuit board of the present invention is applied, and is not particularly limited in the present invention.

The seed layer is a layer for further enhancing the adhesion of the metal layer and may be formed of a metal such as Al, Ti, Cr, Fe, Co, Ni, 1 selected from the group consisting of ruthenium (Ru), ruthenium (Ru), palladium (Pd), silver (Ag), tin (Sn), neodymium (Nd), tungsten (W), platinum Paper is available. Preferably, one kind selected from aluminum (Al), Ti (titanium), Cr (chromium), nickel (Ni), copper (Cu), neodymium (Nd), tungsten (W) and combinations thereof is used.

The thickness of such a seed layer is preferably 0.01 to 3 占 퐉, more preferably 0.01 to 1 占 퐉, and most preferably 0.01 to 0.5 占 퐉. If the thickness is less than the above range, a short circuit occurs or an effect of improving the adhesion of the seed layer can not be sufficiently secured. On the contrary, if the thickness is formed to be thicker than the above range, the thickness of the substrate increases, The via hole may be buried (or filled) instead of forming the seed layer. Therefore, it is properly adjusted within the above range.

The flexible printed circuit board according to the present invention having the above structure can improve the adhesion between the substrate and the circuit pattern and the connection pattern by using the hard coating layer containing the inorganic particles while maintaining the reliability of the bending durability and circuit performance of the entire insulating substrate. .

Such a flexible printed circuit board includes a circuit pattern stacked on an insulating substrate and a via hole passing through the insulating substrate, wherein the upper front surface of the insulating substrate and the upper surface of the insulating substrate before forming the seed layer and the metal layer for the circuit pattern and the connection pattern, A hard coating layer is formed on an insulating substrate that has undergone the process.

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

FIG. 2 is a flowchart showing a method of manufacturing a flexible printed circuit board according to an embodiment of the present invention, and FIG. 3 is a sectional view thereof.

As shown in Figs. 2 and 3, the flexible printed circuit board according to the present invention includes:

(S1) punching an insulating substrate to form a via hole passing therethrough;

(S2) forming a hard coating layer on the upper surface of the insulating substrate and the inner peripheral surface of the via hole;

(S3) forming a seed layer on the hard coat layer;

(S3) forming a metal layer on the seed layer; And

(S4) patterning the hard coat layer, the seed layer and the metal layer to form a circuit pattern and a connection pattern.

Each step will be described in more detail below

First, after the insulating substrate 11 is prepared, a via hole 12 is formed through the through hole (S1) (see a and b in FIG. 3).

The perforation process is not particularly limited in the present invention, and can be applied to any known perforation process. In one example, the drilling process drilling, punching, possible mechanical processing methods such as machining by milling bit or a laser, wherein the laser is a YAG (Yag) laser, an excimer (Eximer) laser or a carbon dioxide (CO ₂₎ can be a laser have.

The via hole 12 formed at this time can be used in any form of the structure for electrical conduction inside the insulating substrate 11, and is not limited to the present invention. For example, the cross-sectional shape may be circular or polygonal, and the via hole 12 may have a diameter of 0.05 mm to 0.3 mm.

The impurities generated after the boring process may lower the adhesion of the layer formed in the subsequent step to the insulating substrate 11 and may be a desmear process for chemically removing the impurities adhered to the inner peripheral surface of the via hole 12 , Which can be done in a roll-to-roll fashion.

Next, a hard coating layer 13 is formed on the upper surface of the insulating substrate 11 and the inner peripheral surface of the via hole 12 (S2) (see Fig. 3 (c)).

3, the hard coating layer 13 in the via hole 12 includes the entire inner peripheral surface of the via hole 12 and is formed so as to surround a predetermined region of the insulating substrate 11 to be connected thereto.

The hard coating layer 13 may be formed by a conventional coating method such as a bar, a blade, a spin, a gravure, a spray, a slot die die coating, reverse gravure coating, or electro-spray coating.

Next, a seed layer 15 is formed on the hard coat layer 13 (S3) (see Fig. 3 (d)).

The seed layer 15 may be formed by a known dry deposition method or a wet coating method including electrolytic / electroless plating, but is preferably performed by a dry deposition process.

The dry deposition process is not particularly limited in the present invention, and any known dry deposition process can be used. For example, sputtering, E-beam evaporation, thermal evaporation, L-MBE (Laser Molecular Beam Epitaxy), and Pulsed Laser Deposition (PLD) , Physical vapor deposition (PVD) using physical methods such as arc ion plating (AIP), and chemical methods such as MOCVD (Metal-Organic Chemical Vapor Deposition) and HVPE (Hydride Vapor Phase Epitaxy) CVD (chemical vapor deposition) is possible.

At this time, if necessary, the heat treatment may be performed at a temperature of 300 to 600 ° C under argon or nitrogen atmosphere.

Next, a metal layer 17 is formed on the seed layer 15 (S4) (see FIG. 3E).

At this time, the metal layer 17 may be formed through a dry deposition or a wet coating process, and is not particularly limited in the present invention.

The dry deposition can be performed by the method described above, and can be preferably performed in the same manner as the seed layer 53 in terms of economy, and a sputtering method can be most preferably used.

The wet coating may be performed through an electroplating, electroless plating or printing process.

Electroplating or electroless plating is performed by immersing the insulating substrate 11 in a solution containing the material of the metal layer 17 and then applying electricity. At this time, an insulating material such as a tape is attached .

The printing process may be performed in a known manner such as flexo printing, flat-screen printing, roll-to-roll (R2R) printing, and rotary screen printing, And the printing is performed only selectively.

If the metal layer 17 is formed in the same manner as the seed layer 15, the process can be further simplified, and a dry deposition or printing process can be preferably used for the roll-to-roll process.

Next, the hard coat layer 13, the seed layer 15, and the metal layer 17 are patterned to form a circuit pattern 19a and a connection pattern 19b formed in the via hole 12 on the insulating substrate 11, A printed circuit board is manufactured (S5) (see Fig. 3 (f)).

The patterning is not particularly limited in the present invention, and a known process may be used.

For example, a positive or negative photoresist may be applied followed by an etch process, where the etch may be accomplished through a dry etch using a reactive gas or a wet etch process using a chemical have.

Dry etching can be performed by plasma etching, reactive ion etching (RIE), magnetically enhanced RIE (MERIE), reactive ion beam etching, and high density plasma (HDP). The etching process is used.

The wet etching is _{CH 3 COOH, HNO 3, HF} , BHF, NH 4 F, H 3 PO 4, may be carried out using the etching solution consisting of an aqueous solution, such as KI, wherein the seed layer 15 and the metal layer 17 Depending on the material, the composition, concentration, temperature, treatment time, etc. of the etchant can be varied and varied.

The patterning may be performed sequentially or simultaneously with the metal layer 17, the seed layer 15 and the hard coat layer 13, and an appropriate etching process may be selected according to the material of each layer.

3 (f), the flexible printed circuit board manufactured through the patterning process is formed by sequentially laminating the hard coating layer 13a / the seed layer 15a / the metal layer 17a and patterning the circuit patterns 19a and 19b The hard coat layer 13b / the seed layer 15b / the metal layer 17b are sequentially stacked on the inner peripheral surface of the via hole 12 and patterned.

The flexible printed circuit board manufactured through the above steps can be used as a one-sided flexible printed circuit board by processing through-via-holes 12 and forming a circuit pattern. In addition, if necessary, the flexible circuit board can be manufactured in multiple layers by stacking (stacking) the substrates in order above and below the center substrate.

At this time, the metal material in the through via holes 12 is filled so that the substrates are electrically connected to each other. Such metal materials and filling technology follow well-known techniques.

In the manufacturing process, any one or more of the previous steps can be performed by a roll-to-roll process, and the automation is maximized by the roll-to-roll process, thereby dramatically improving the productivity and maximizing the yield , It is possible to manufacture the entire process equipments at lower cost than the existing equipments, thereby lowering the manufacturing cost and enhancing the product competitiveness.

The above-described flexible printed circuit board according to the present invention can secure a high reliability because there is no circuit defect rate or malfunction under frequent bending or severe operating conditions, and can be used as an automation device, Batteries, electronic paper, and the like.

Hereinafter, preferred embodiments and experimental examples of the present invention will be described. However, the following examples are only preferred examples of the present invention, and the present invention is not limited by these examples.

Examples 1 to 2 and Comparative Example 1: Flexible printed circuit board fabrication

A hard coating layer was formed on the plasma-treated polyimide film (thickness: 35 m), titanium was formed to a thickness of 0.05 m as a seed layer by DC magnetron sputtering, and copper was vapor-deposited to a thickness of 5 m on the upper surface thereof. At this time, in the case of the seed layer, the sputtering was carried out using argon gas, which is an inert gas, while the vacuum degree was maintained at about 1.2 × 10 ^-1 Pa. In the case of the metal layer, the gas layer was maintained at 1.6 × 10 ^-1 Pa using argon gas.

At this time, the hard coat layer was prepared by diluting 20 wt% of inorganic particles, 45 wt% of epoxy resin, and 7 wt% of EXB-9460 (manufactured by Dainippon Ink and Chemicals, Incorporated) into methyl ethyl ketone. The inorganic particles used are as shown in Table 1 below.

Experimental Example 1: Pencil Hardness Measurement

The pencil hardness of the hard coat layer is tested according to the provisions of JIS K 5600-5-4 to evaluate the pencil hardness by the formula of "pencil hardness" = "minimum hardness at which scratches occur" - "(number of scratches in 10) / 10" Respectively. At this time, the pencil hardness indicates the hardness by H, F, HB, B, etc., and the higher the number H, the higher the hardness, and the higher the number B, the lower the hardness.

Experimental Example 2: Adhesion Measurement

The adhesion test was evaluated using a 3M # 610 adhesive tape test method. The flexible printed circuit boards obtained in the above Examples and Comparative Examples were cut in a checkerboard shape at intervals of 1 mm x 1 mm, and the number of checkerboards having a size of 1 mm x 1 mm remained when the tape was attached and detached.

Experimental Example 3: Flexural durability evaluation

A single-sided circuit board was fabricated by screen printing using the 200-mesh plate on the flexible printed circuit board manufactured in the above-described Examples and Comparative Examples. The produced single-sided circuit board was bent at 180 °. The bending durability evaluation is as follows.

≪ Evaluation of bending durability &

Good: Flexibility

X: Insufficient flexibility

Hard coating layer Pencil hardness Adhesion
(Number / 100) curve
durability Whether Inorganic particle Kinds Average particle diameter
(탆) content
(weight%) Example 1 ○ SiO ₂ 0.1 20 2H 100/100 ○ Example 2 ○ SiN 0.5 20 H 100/100 ○ Comparative Example 1 × - - - 2B 80/100 ×

Referring to Table 1, when the hard coating layer was present according to the present invention, it was confirmed that whitening occurred at the curved portion, and the interfacial adhesion and scratch resistance were also excellent as compared with Comparative Example 1 in which the hard coating layer was not formed.

The flexible printed circuit board according to the present invention has excellent interfacial adhesion and bending durability and can be used in various small and medium electronic apparatuses such as smart phones, displays, solar cells, and electronic paper.

11: substrate 12: via hole
13: Hard coating layer
13a: hard coating layer of circuit pattern 13b: hard coating layer of connection pattern
15: Seed layer
15a: Seed layer of the circuit pattern 15b: Seed layer of the connection pattern
17: metal layer
17a: metal layer of circuit pattern 17b: seed layer of connection pattern
19a: circuit pattern 19b: connection pattern

Claims (9)

An insulating substrate on which at least one via hole is formed;
A circuit pattern formed on the insulating substrate; And
And a connection pattern formed to electrically connect the circuit pattern, including an inner circumferential surface of the via hole,
And a hard coating layer between the insulating substrate and the circuit pattern and the connection pattern. The flexible printed circuit board according to claim 1, wherein the hard coating layer comprises inorganic particles, a resin, a curing agent, and a solvent. The method of claim 2, wherein the inorganic particles are selected from the group consisting of Si, Al, Sn, Sb, Ta, Ce, La, Fe, Zn, W, Zr, In, Ti, Nb, Y, An oxide, a nitride, or a carbide. The flexible printed circuit board according to claim 2, wherein the inorganic particles have an average particle diameter of 0.01 to 3 탆. [2] The composition of claim 1, wherein the composition of the hard coat layer satisfies 100 wt%
5 to 50% by mass of inorganic particles,
20 to 90% by mass of a resin,
1 to 50% by mass of a curing agent and
And the remaining portion comprises a solvent. The flexible printed circuit board according to claim 1, wherein the hard coating layer has a thickness of 1 to 100 mu m. The hard coating layer according to claim 2, wherein the hard coating layer further comprises one kind selected from the group consisting of a dispersant, a viscosity adjusting agent, a curing accelerator, a flame retardant, an aggregation inhibitor, a defoaming agent, a leveling agent, And a flexible printed circuit board. The flexible printed circuit board according to claim 1, wherein the circuit pattern and the connection pattern are formed of a metal layer or a seed layer / metal layer. (S1) punching an insulating substrate to form a via hole passing therethrough;
(S2) forming a hard coating layer on the upper surface of the insulating substrate and the inner peripheral surface of the via hole;
(S3) forming a seed layer on the hard coat layer
(S4) forming a metal layer on the seed layer; And
(S5) patterning the hard coat layer, the seed layer, and the metal layer to form a circuit pattern and a connection pattern, respectively.

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