KR20150015208A - Manufacturing method of cover layer for FPC and Manufacturing method of FPC and cover layer for FPC and FPC using the methods - Google Patents

Abstract

The present invention relates to a cover layer with the improved permeability of a flexible printed circuit (FPC) and a FPC using the same. A method of manufacturing the cover layer of a FPC includes: a step (s100) of preparing a mixture of metal powder and a polymer binder to fixate the metal powder; a step (s200) of preparing an insulating flexible base layer of the cover layer which supports the mixture of the metal powder and the polymer binder; a step (s300) of coating the mixture of the metal powder and the polymer binder on the insulating flexible base layer and forming a sheet shape with the coated mixture; a step (s400) of winding the sheet on which the binder mixture is coated on the insulating flexible base layer while applying a tension on the sheet as a roll shape; and a step (s500) of thermally processing the sheet wound in the roll shape.

Description

Technical Field The present invention relates to a method of manufacturing a cover layer of a flexible printed circuit board, a method of manufacturing a flexible printed circuit board using the manufacturing method, and a cover layer and a flexible printed circuit board manufactured by the manufacturing method. and cover layer for FPC and FPC using the methods}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cover layer of a flexible printed circuit board (FPC) having improved permeability and a flexible printed circuit board using the cover layer. More particularly, And more particularly, to a manufacturing method that can simplify the manufacturing process of the cover layer.

In general, a flexible printed circuit board (FPC) is used for electrically connecting two sections of a plurality of electronic apparatuses with many bends or for a small space and a flexible electronic apparatus. The major feature of such a flexible circuit board is that it is used as a core component of all electronic products because it is flexible and has excellent workability, heat resistance, rust resistance, chemical resistance, and heat resistance. , Audio equipment, camcorders, printers, DVD, TFT LCD, satellite equipment, military equipment, and medical equipment.

The manufacturing process of the flexible printed circuit board according to the related art includes a step of bonding a base film of a polyimide material and a copper foil with an adhesive to form a laminate; Forming a circuit through etching and dry film peeling on the copper foil; Forming a via hole in the laminate; Electroless copper plating on an upper surface of the laminate, that is, an upper surface of the copper foil and a via hole; Electroplating the upper surface of the electroless copper plating and the via hole; And a cover layer of a polyimide material coated with a thermosetting adhesive on the upper surface of the electroplating is adhered with an adhesive to laminate a cover layer made of a polyimide material, followed by bonding by thermocompression bonding. A shielding sheet may be attached to the upper part of the flexible circuit board by the following methods for the purpose of preventing the malfunction of the electronic device or improving the function of the flexible circuit board for the digitizer.

As a first method, there is a method of attaching a composite magnetic sheet using a pressure-sensitive adhesive fully oriented on a completed flexible circuit board;

In the second method, the cover layer of the flexible circuit board and the low-density magnetic sheet which is not aligned are thermo-pressed to improve the density of the magnetic sheet in one process, and the orientation of the flake powder to improve the permeability A method of inducing and adhering;

As a third method, a low density oriented magnetic shielding sheet coated with a thermosetting adhesive on a conventional cover layer is laminated and thermocompression-bonded. In the above process, similarly to the above second method, density improvement and flake orientation as well as improvement of permeability A method of attaching the shielding sheet by a method of inducing and attaching the shielding sheet may be included.

The shielding sheet is made of a ferrite powder or a soft magnetic flake powder mixed with a polymer material such as rubber or plastic to form a sheet. In many cases, the shielding sheet or the electromagnetic wave absorbing sheet is referred to as a magnetic shielding sheet in the structural aspect. It has appeared in the electronic materials market for anti-noise measures since mid-year.

The magnetic shielding sheet satisfying the requirements of thinness, light weight, and flame resistance is convenient to be attached to an IC chip or to be wound around a signal line as compared with a conventional device.

With the progress of miniaturization and high density of electronic devices, magnetic shielding sheets have come up with more suitable means.

(In the blue text below, I feel too much emphasis on the general EMC content.) The material we are applying for is used to improve the EMC problem or the digitizer function in the device rather than the general EMC. The density of electromagnetic waves in the environment is increased, which causes the occurrence of a malfunction between components of the electronic apparatus or components in the apparatus, and at the same time, it causes many problems such as being pointed out as a factor that may harm the human body.

In order to solve these electromagnetic noise problems, noise countermeasures must be used. Demand for noise countermeasures is higher than that of general electronic components. Demand is expected to steadily increase in the future.

Currently, noise countermeasures are widely used in handheld devices such as mobile phones, computers, displays, and digital cameras, and their use is increasing in industrial devices and automobiles.

There are numerous combinations to eliminate the various noise generated. Electro-Magnetic Compatibility (EMC) design and countermeasure techniques are complex technologies in which a lot of knowledge and experience must be harmonized.

The ratio of the energy absorbed by the object to the incident energy when the wave is incident on the object is called the absorption rate. An electromagnetic wave absorber is a substance having a high absorption rate. Generally, graphite powder is made of a dielectric material mixed with foamed styrene resin or the like, and made of a magnetic material such as ferrite. By attaching a magnetic sheet using such a radio wave absorber to a cover layer of a flexible printed circuit board (FPC), electromagnetic waves generated in the flexible printed circuit board (FPC) are shielded / absorbed to prevent malfunction of the equipment and harm to the human body, Techniques have been introduced to improve the recognition efficiency between the electronic pen and the flexible circuit of the tablet PC.

Japanese Patent Registration No. 10-1161737 relates to a method for producing a composite magnetic sheet compression molded at a high density and a composite magnetic sheet formed by the method. The present invention relates to a composite magnetic sheet for increasing the magnetic permeability of a magnetic sheet for enhancing electromagnetic wave absorption of various electronic devices and increasing the recognition distance of an antenna and improving attenuation characteristics of electromagnetic waves and the like. And the release pockets including the overlapped sheet are inserted into a separate compression mold, wherein the release pockets and the divided compression plates are sequentially laminated in the compression mold, The pressing frame is pressure-formed stepwise through a hot pressing process at a high temperature and a cold pressing process at a low temperature so that a plurality of base sheets having a low density soft magnetic powder are stacked and heat- Removal of the voids and the soft magnetic powder are aligned between the binders, Density composite magnetic sheet can be produced while compressing the inductor. Therefore, the thickness of the composite magnetic sheet can be reduced to 1/2 to 1/5 according to the type of the soft magnetic powder while maintaining the area of the existing base sheet, Density composite magnetic sheet can be obtained by using a compression mold and a multi-stage compression press to produce a composite magnetic sheet in which the magnetic permeability is increased drastically and the attenuation characteristics of electromagnetic waves are greatly improved, It can be produced in a large quantity and has a very economical effect due to excellent productivity. However, there is no description of a manufacturing method for increasing the density of a sheet usable in a composite magnetic sheet, an electromagnetic wave absorber, or the like and having an effect of high permeability.

In the above-mentioned three methods of attaching the magnetic shielding sheet to the surface of the flexible circuit, the first method is the most stable but the problem that the process of attaching the magnetic shielding sheet is further required after completing the flexible circuit board by thermocompression And the second method and the third method are advantageous in that the magnetic shielding sheet is simultaneously adhered during the thermocompression bonding process of the flexible circuit board. However, since the magnetic shielding sheet can be inspected and the appearance of the magnetic shielding sheet can be checked only after the attachment to the flexible circuit, There is a risk that the loss cost to the user is increased.

That is, a high permeability magnetic sheet having a high density and a high degree of orientation is fabricated from a cover layer for a flexible printed circuit and an integral or separate magnetic shielding sheet, and the thickness density permeability change Since the magnetic circuit board can be manufactured by thermocompression after the magnetic permeability performance and appearance inspection of the magnetic shielding sheet are completed before the thermocompression bonding step for manufacturing the flexible circuit board and the appearance and performance of the magnetic shielding sheet are uneven It is necessary to have a technique to prevent the possibility of occurrence of defects in advance.

In addition, when the adhesive layer and the crosslinking layer are thermally bonded together by thermocompression bonding the cover layer and the main layer at a time in the thermocompression bonding process, there is a problem that it is impossible to confirm which of the cover layer and the main layer is caused by the defect.

Accordingly, the present invention provides a method of manufacturing a cover layer of a flexible printed circuit (FPC), comprising the steps of: preparing a mixture of a metal powder for shielding electromagnetic waves and a polymer binder for fixing the metal powder, ; Preparing an insulating flexible base layer (s200) of a cover layer for supporting a mixture of the metal powder and the polymer binder; Coating a mixture of the metal powder and the polymeric binder on the insulating flexible base layer to form a sheet shape (s300); Winding the sheet coated with the binder mixture on the insulative flexible base layer in a rolled state with tension applied (s400); And a step of heat-treating the roll-wound sheet (s500), and a step of coating and drying a thermosetting adhesive on the opposite polyimide of the magnetic shielding sheet.

The present invention relates to a method of manufacturing a plurality of sheets at one time while improving the density to obtain a high-permeability electromagnetic wave absorber, and simplifying the manufacturing process of the cover layer.

In addition, the present invention is characterized in that, in the step of forming a sheet by coating a mixture of the metal powder and the polymer binder, the mixture of the metal powder and the polymer binder is not coated on the supporting substrate to be subsequently removed, To thereby simplify the process by laminating the sheets having the cover layer thereon, and to perform the defect rate preliminary inspection of the cover layer manufactured by previously heat-treating the cover layer in a roll shape. This makes it possible to easily identify the cause of the defect in the cover layer and the main layer in the subsequent total defect inspection.

1 is a flowchart of a method of manufacturing a cover layer of a flexible printed circuit board of the present invention.
2 is a cross-sectional view of a main part of a cover layer of a flexible printed circuit board of the present invention.
3 is an explanatory diagram of a step s400 of winding a roll 9 into a shape.
4 is a flowchart of a method of manufacturing a flexible printed circuit board of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cover layer of a flexible printed circuit board (FPC) having improved permeability and a flexible printed circuit board using the cover layer. More particularly, And more particularly, to a manufacturing method that can simplify the manufacturing process of the cover layer.

That is, the present invention provides a method of manufacturing a cover layer of a flexible printed circuit (FPC)

(S100) preparing a mixture of a metal powder (1) for electromagnetic shielding and a polymer binder (2) for fixing the metal powder;

A step (s200) of preparing an insulating flexible base layer (4) of a cover layer (3) for supporting a mixture of the metal powder (1) and the polymer binder (2);

Coating a mixture (2) of the metal powder (1) and the polymeric binder on the insulating flexible base layer (4) to form a sheet shape (s300);

A step (s400) of winding the sheet coated with the binder mixture on the insulating flexible base layer (4) in the form of a roll (9) while applying tension thereto; And

Heat treating the sheet wound in the form of the roll (s500);

And a control unit.

The mixture of the metal powder 1 and the polymer binder 2 in the step of forming the sheet shape by coating the mixture of the metal powder 1 and the polymer binder 2 is then transferred to the next It is possible to simplify the process by coating the base layer 4 directly on the insulating flexible base layer 4 which is a component of the cover layer without being coated on the base layer.

In this case, since the mixture of the metal powder 1 and the polymeric binder 2 may fall on the insulating flexible base layer 4 after the subsequent manufacturing process, the adhesive layer 41 is applied on the insulating flexible base layer 4, It is preferable to coat a mixture of the metal powder (1) and the polymeric binder (2) on the adhesive layer (41).

This method makes it possible to perform the defect rate preliminary inspection of the cover layer produced by heat treating the cover layer in the form of a roll 9 so that the defect of the cover layer 3 and the main layer 5 .

Preferably, the flexible base layer 4 in the step (s200) of preparing the flexible base layer is a polyimide layer, and the polyimide layer has a thickness of 20 m to 100 m.

In the step (s100) of preparing the mixture of the metal powder (1) and the polymer binder (2), the mixture of the metal powder (1) and the binder (2) is mixed with a flake metal powder ) And a polymer resin are preferably dispersed. The metal powder is composed of at least one of iron (Fe), silicon (Si), aluminum (Al), chrome (Cr), nickel (Ni) and manganese (Mn) . The metallic powder 1 in the shape of a flake is overlapped with each other in the binder 2 to effectively block electromagnetic waves.

The organic solvent may be at least one selected from the group consisting of toluene, cyclohexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, n-butyl acetate, ceroussol acetate, methylene chloride, methyl ethyl ketone, dichloromethane, xylene, It is preferable to include at least one of them.

The polymeric binder 2 may be at least one selected from the group consisting of phenolic resin, urea resin, melamine resin, Teflon, polyamide, polyvinyl chloride, flame retardant polyethylene, flame retardant polypropylene, flame retardant polystyrene, polyphenylene sulfide, At least one of a resin, an epoxy resin, chlorinated polyethylene, ethylene propylene dimethyl, acrylic resin, amide resin, polyester resin, polyethylene resin, ethylene-propylene rubber, polyvinyl butyral resin, polyurethane resin, nitrile-butadiene rubber It is preferable to include at least one of them.

It is also possible to add an additive to the binder (2). In the case of the flame retardant, at least one of antimony trioxide (Sb ₂ O ₃ ), aluminum hydroxide (Al (OH) ₃ ), and magnesium hydroxide (Mg (OH) ₂ ) But it should not be construed as being limited thereto.

In the step (s300) of forming a sheet shape by coating a mixture of a metal powder and a polymeric binder on the polyimide layer, the coating process comprises:

Coatings such as slot die coating, comma coating, knife coating, gravure coating, micro-gravure coating, dip coating, Spray coating, doctor blade coating, roll coating, bar coating (coating), spray coating (roll coating), spray coating Bar coating.

In order to manufacture the high magnetic permeability composite magnetic sheet and the electromagnetic wave absorber by increasing the density, the shearing stress should not be applied to the flake metal powder 1 during sheet production.

This is because the powder undergoes stress due to shear stress and the permeability decreases.

Therefore, in the present invention, the metal powder (1) and the binder (2) are dispersed in a wet manner and the dispersed solution is prepared by a coating method to produce a sheet without applying shear stress.

The sheet thus produced has a low permeability because of its low density. Therefore, in order to obtain the high magnetic permeability composite magnetic sheet and the electromagnetic wave absorber, a process for improving the density must be performed.

In order to increase the density of the sheet, it is possible to produce electromagnetic wave absorbers with high permeability by increasing the density through a cross-linking process while pressurizing with a hot press.

Methods for improving the density include not only a hot pressing method but also a rolling method including a plurality of rolls, a method including a polymer rubber roll, a method using an endless belt, and a method using a metal roll.

The use of rolls allows continuous operation, which results in good working efficiency, but has limitations in increasing the density to obtain a high permeability. In addition, the initial density of the rolls can be increased and the high permeability can be secured. However, the density is decreased again due to the spring back phenomenon and the permeability is lowered over time.

The cross-linking process using a press has a disadvantage in that a high permeability can be obtained but a large number of sheets can not be produced at one time.

In order to solve this problem, in order to solve such a problem, the sheet is rolled with a high tensile force together with the insulating flexible base layer 4 to increase the density by applying pressure, and heat treatment is carried out by putting it in a heating device such as an oven.

Here, since the insulating flexible base layer 4 must be wound with a high tensile force to increase the density of the sheet 110, the insulating flexible base layer 4 should be made to withstand high tension.

Specifically, it is preferable that the tension is 5,000 dyn / cm to 12,000 dyn / cm in the step s400 of rolling the roll 9 with the tension applied. If the sheet is wound in the form of a roll 9, the above tension can be uniformly applied to the entire region of the sheet. More preferably from 7,000 dyn / cm to 10,000 dyn / cm (0.07 N / cm to 0.1 N / cm). If the tension is 10,000 dyn / cm or more, the solvent trapped in the sheet may not be discharged in the form of gas.

And supplies the necessary pressure to the subsequent heat treatment step (s500). Preferably, the step of heat treating the sheet formed on the support wound in the form of the roll 9 (s500) is performed at a temperature of 100 ° C to 200 ° C for 30 minutes to 90 minutes.

The electromagnetic wave absorber produced by this method has a density of 3.0 g / cm ³ to 4.0 g / cm ³ and a permeability of 60 μ to 200 μ.

The above values are significantly different from the density of the green sheet before crosslinking of 1.6 g / cm ³ - 1.8 g / cm ³ and the permeability of 30 μ - 120 μ.

That is, according to the cover layer manufacturing method applied to the flexible printed circuit board of the present invention, it is possible to manufacture the cover layer 3 of the flexible printed circuit board to which the cross-linking reaction and the thermocompression effect are applied together.

The present invention also provides a flexible printed circuit (FPC)

In a main layer (4) of a flexible circuit board composed of an insulating flexible base layer (8) and a circuit layer (6) printed with the insulating flexible base layer (8)

And a cover layer (3) produced by the above manufacturing method is attached by an adhesive layer (7).

That is, the method of manufacturing the flexible printed circuit (FPC)

Preparing an insulating flexible base layer 8 (S1000);

A step (s1100) of printing a circuit layer (6) by etching the circuit layer (6) on the insulating flexible base layer (8);

Preparing a cover layer (3) of a flexible printed circuit board (s1200);

An adhesion step (s1300) in which the main layer (4) and the cover layer (3) are adhered to each other with an adhesive layer (7);

(S1200) of preparing the cover layer 3 of the flexible printed circuit board includes the steps of manufacturing the cover layer 3 described above.

(S100) preparing a mixture of a metal powder for electromagnetic shielding and a polymer binder for fixing the metal powder;

A step (s200) of preparing an insulating flexible base layer (5) of a cover layer for supporting a mixture of the metal powder and the polymer binder;

Coating a mixture of the metal powder (1) and the polymer binder (2) on the insulating flexible base layer (4) to form a sheet shape (s300);

Winding the sheet coated with the binder mixture on the insulative flexible base layer in the form of a roll (9) with tension applied (s400); And

Heat treating the sheet wound in the form of the roll (s500);

And a method of manufacturing a cover layer (3) of a flexible printed circuit board including the flexible printed circuit board.

The step (s1000) of preparing the insulating flexible base layer and the circuit layer printing step (s1100) of forming the insulating flexible base layer by etching a circuit layer are generally performed by bonding a base film made of a polyimide material and a copper foil To form a laminate; Forming a circuit through etching and dry film peeling on the copper foil; Forming a via hole in the laminate; Electroless copper plating on an upper surface of the laminate, that is, an upper surface of the copper foil and a via hole; Electroplating the upper surface of the electroless copper plating and the via hole, and the like.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it should be understood that various changes and modifications will be apparent to those skilled in the art. It is to be understood that the present invention is not limited to the above-described embodiments. Accordingly, the scope of protection of the present invention should be construed according to the following claims, and all technical ideas which fall within the scope of equivalence by alteration, substitution, substitution, Range. In addition, it should be clarified that some configurations of the drawings are intended to explain the configuration more clearly and are provided in an exaggerated or reduced size than the actual configuration.

1. metal powder
2. Binder
3. Cover layer
4. Isolation flexible base layer
5. The main layer
6. Circuit layer
7. Adhesive Layer
8. Isolation flexible base layer

Claims (14)

A method of manufacturing a cover layer of a flexible printed circuit (FPC)
(S100) preparing a mixture of a metal powder (1) for shielding electromagnetic waves and a polymer binder (2) for fixing the metal powder (1);
A step (s200) of preparing an insulating flexible base layer (4) of a cover layer (3) for supporting a mixture of the metal powder (1) and the polymer binder (2);
Coating a mixture of the metal powder (1) and the polymeric binder (2) on the insulating flexible base layer to form a sheet (s300);
A step (s400) of winding the sheet coated with the binder mixture on the insulating flexible base layer (4) in the form of a roll (9) while applying tension thereto; And
Heat treating the sheet wound in the form of the roll (s500);
The method of claim 1, further comprising:
The method according to claim 1,
Wherein the flexible base layer (4) in the step (s200) of preparing the flexible base layer is a polyimide layer.
3. The method of claim 2,
In step (s100) of preparing a mixture of the metal powder (1) and the polymer binder (3), the mixture of the metal powder (1) and the binder (2) is mixed with a flake metal powder and a polymer resin Wherein the adhesive layer is dispersed in the adhesive layer.
The method of claim 3,
Characterized in that the metal powder (1) is composed of at least one of iron (Fe), silicon (Si), aluminum (Al), chromium (Cr), nickel (Ni) A method of manufacturing a cover layer of a substrate.
3. The method of claim 2,
The polymeric binder (2)
Phenol resin, urea resin, melamine resin, Teflon, polyamide, polyvinyl chloride, flame retardant polyethylene, flame retardant polypropylene, flame retardant polystyrene, polyphenylene sulfide, flame retardant PET, flame retardant PBT, flame retardant polyolefin, silicone resin, epoxy resin, chlorinated polyethylene , At least one of ethylene propylene dimethyl, acrylic resin, amide resin, polyester resin, polyethylene resin, ethylene-propylene rubber, polyvinyl butyral resin, polyurethane resin and nitrile-butadiene rubber Wherein the cover layer is made of a metal.
3. The method of claim 2,
Wherein the polyimide layer has a thickness of 20 占 퐉 to 100 占 퐉.
3. The method of claim 2,
In the step (s300) of forming a sheet shape by coating a mixture of a metal powder and a polymeric binder on the polyimide layer, the coating process comprises:
Coatings such as slot die coating, comma coating, knife coating, gravure coating, micro-gravure coating, dip coating, Spray coating, doctor blade coating, roll coating, bar coating, spray coating, spin coating, spin coating, spin coating, The method of manufacturing a cover layer of a flexible printed circuit board according to claim 1,
8. The method of claim 7,
An adhesive layer 41 is coated on the insulating flexible base layer 4 in step S300 of forming a sheet shape by coating a mixture of a metal powder and a polymer binder on the polyimide layer, 41) is coated with a mixture of the metal powder (1) and the polymeric binder (2).
3. The method of claim 2,
Wherein the tensile force is 5,000 dyn / cm to 12,000 dyn / cm in the step (s400) of winding the roll (9) with the tension applied thereto. Gt;
3. The method of claim 2,
The step (S500) of heat-treating the sheet formed on the support wound in the form of the roll (9)
Wherein the heat treatment is performed at a temperature of 100 캜 to 200 캜.
11. The method of claim 10,
Wherein the step of heat treating the sheet formed on the support wound in the form of the roll (9) is performed for 30 minutes to 90 minutes.
In a cover layer applied to a flexible printed circuit board,
11. A method of manufacturing a semiconductor device according to any one of claims 1 to 11, wherein a cross-linking reaction and a thermocompression effect are simultaneously performed, a density is 3.0-4.0 g / cm < ³ & And the cover layer of the flexible printed circuit board.
In a flexible printed circuit (FPC)
An insulating flexible base layer and a circuit layer printed on the insulating flexible base layer,
A flexible circuit board according to any one of claims 1 to 11, wherein the cover layer is attached by an adhesive layer.
A method of manufacturing a flexible printed circuit (FPC)
Preparing an insulating flexible base layer (S1000);
A circuit layer printing step s1100 of forming a circuit layer on the insulating flexible base layer by etching;
Preparing a cover layer of a flexible printed circuit board (s1200);
An adhesion step (s1300) in which the main layer and the cover layer are adhered to each other with an adhesive layer;
(S1200) of preparing the cover layer of the flexible printed circuit board,
A method of manufacturing a flexible printed circuit board, comprising the steps of: forming a cover layer of a flexible printed circuit board according to any one of claims 1 to 11.

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