阅读说明：本技术 用于制造柔性印刷电路板的方法及由该方法制造的柔性印刷电路板 (Method for manufacturing flexible printed circuit board and flexible printed circuit board manufactured by the same ) 是由 段成伯 于 2018-05-16 设计创作，主要内容包括：公开了一种用于制造柔性印刷电路板的方法及由该方法制造的柔性印刷电路板。在该方法中通过堆叠由具有耐热性和低介电常数的聚四氟乙烯膜构成的基片来防止高频信号的损失,同时使得由高频信号引起的介电损耗最小化。所提出的用于制造柔性印刷电路板的方法包括以下步骤：制备基片,该基片是聚四氟乙烯膜,在该聚四氟乙烯膜一个表面上形成有薄膜图案；制备粘合片；堆叠多个基片和粘合片；以及加热、加压并粘合其中堆叠有多个基片和粘合片堆叠体。(Disclosed are a method for manufacturing a flexible printed circuit board and a flexible printed circuit board manufactured by the same. In which loss of high-frequency signals is prevented while dielectric loss caused by the high-frequency signals is minimized by stacking substrates composed of polytetrafluoroethylene films having heat resistance and a low dielectric constant. The proposed method for manufacturing a flexible printed circuit board comprises the steps of: preparing a substrate, which is a polytetrafluoroethylene film, with a thin film pattern formed on one surface of the polytetrafluoroethylene film; preparing an adhesive sheet; stacking a plurality of substrates and adhesive sheets; and heating, pressing and bonding the adhesive sheet stack in which the plurality of substrates and the adhesive sheet stack are stacked.)

1. A method for manufacturing a flexible printed circuit board, the method comprising:

preparing a substrate, wherein the substrate is a polytetrafluoroethylene film, and a thin film pattern is formed on the polytetrafluoroethylene film;

stacking a plurality of substrates; and

heating, pressurizing and bonding a stacked body in which the plurality of substrates are stacked.

2. The method for manufacturing a flexible printed circuit board according to claim 1,

wherein the preparing a substrate comprises:

adhering a guide film on one surface of the polytetrafluoroethylene film;

forming a thin film pattern on the other surface of the polytetrafluoroethylene film; and

forming one or more through holes passing through the polytetrafluoroethylene film, the guide film, and the thin film pattern.

3. The method for manufacturing a flexible printed circuit board according to claim 2,

wherein the adhesion guide film interposes a silicon-based adhesive film between the polytetrafluoroethylene film and the guide film.

4. The method for manufacturing a flexible printed circuit board according to claim 1, further comprising: preliminarily bonding the stack by applying water pressure to the stack before the bonding.

5. The method for manufacturing a flexible printed circuit board according to claim 1, further comprising:

forming a via in the stack after the bonding; and

forming a connection pattern in the via hole.

6. The method for manufacturing a flexible printed circuit board according to claim 1,

the preparation substrate prepares the polytetrafluoroethylene membrane into a substrate, and a surface modification layer is formed on the polytetrafluoroethylene membrane.

7. The method for manufacturing a flexible printed circuit board according to claim 6,

wherein the preparing a substrate comprises:

adhering a guide film to one surface of the polytetrafluoroethylene film;

forming a thin film pattern on the other surface of the polytetrafluoroethylene film; and

forming the surface modification layer on the other surface of the polytetrafluoroethylene film.

8. The method for manufacturing a flexible printed circuit board according to claim 7,

wherein the preparing the substrate further comprises:

removing the guide film; and

forming the surface modification layer on the one surface of the polytetrafluoroethylene film.

9. The method for manufacturing a flexible printed circuit board according to claim 1,

wherein the preparing a substrate comprises:

forming a surface modification layer on at least one of one surface and the other surface of the polytetrafluoroethylene film;

adhering a guide film on one surface of the polytetrafluoroethylene film; and

and forming a thin film pattern on the other surface of the polytetrafluoroethylene film.

10. The method for manufacturing a flexible printed circuit board according to claim 1,

the preparation substrate prepares the polytetrafluoroethylene film as a substrate, and an adhesive layer made of polytetrafluoroethylene material is formed on the polytetrafluoroethylene film.

11. The method for manufacturing a flexible printed circuit board according to claim 10,

wherein the preparing a substrate comprises:

adhering a guide film on one surface of the polytetrafluoroethylene film;

forming a thin film pattern on the other surface of the polytetrafluoroethylene film; and

forming an adhesive layer on the other surface of the polytetrafluoroethylene film.

12. The method for manufacturing a flexible printed circuit board according to claim 11,

wherein the forming of the adhesive layer forms the adhesive layer on the upper surface and the periphery of the thin film pattern and an area where the thin film pattern is not formed.

13. The method for manufacturing a flexible printed circuit board according to claim 11,

wherein the preparing the substrate further comprises:

removing the guide film; and

forming a coating layer on the one surface of the polytetrafluoroethylene film.

14. A flexible printed circuit board comprising:

a stacked body in which a plurality of substrates are stacked; and

a circuit pattern formed on the stacked body,

wherein the substrate includes a polytetrafluoroethylene film on which a thin film pattern is formed.

15. The flexible printed circuit board according to claim 14,

wherein the polytetrafluoroethylene film is formed with an adhesive layer on one surface to be adhered to another substrate, an

Wherein the adhesive layer is a polytetrafluoroethylene material.

16. The flexible printed circuit board according to claim 14,

wherein a surface modification layer is formed on the polytetrafluoroethylene film, and

wherein the surface modification layer is formed on one surface of the polytetrafluoroethylene film on which the thin film pattern is formed.

17. The flexible printed circuit board according to claim 16,

wherein the surface modification layer is formed on a region of one surface of the polytetrafluoroethylene film exposed to the space of the thin film pattern.

18. The flexible printed circuit board according to claim 14,

wherein surface modification layers are formed on the upper surface and the periphery of the thin film pattern.

19. The flexible printed circuit board according to claim 14, further comprising an adhesive sheet stacked between the plurality of substrates,

wherein the adhesive sheet is: a cast polypropylene (CPP) film of a multilayer structure having an adhesive layer formed on at least one surface thereof, or

An adhesive film of a single layer structure comprising at least one of polyethylene, polypropylene and polyimide.

20. The flexible printed circuit board according to claim 14,

wherein the circuit pattern includes:

a plurality of thin film patterns formed on one surface of the polytetrafluoroethylene film and disposed inside the stack and on an upper surface of the stack; and

a connection pattern connecting the plurality of thin film patterns.

Technical Field

The present disclosure relates to a method for manufacturing a flexible printed circuit board and a flexible printed circuit board manufactured by the method, and more particularly, to a method for manufacturing a flexible printed circuit board having heat resistance and flexibility and a flexible printed circuit board manufactured by the method.

Background

In general, a printed circuit board is a board that can be flexibly bent by forming a circuit pattern on an insulating film, and is widely used in portable electronic devices and automation devices or display products that need to be bent and flexible when mounted and used.

Generally, a printed circuit board is manufactured by bonding or die-casting a copper foil onto a Polyimide (PI) film. At this time, a polyimide film is widely used as a base material for a printed circuit board because of its characteristics such as high mechanical strength, good heat resistance, good insulation properties, and good solvent resistance.

Meanwhile, as services for transmitting a large amount of information in real time, such as video calls, movie watching, and real-time relay, are used more, portable terminals are mounted with circuits for transmitting a large amount of information by using a high frequency band (e.g., GHz).

However, in the case of transmitting a high-frequency signal using a printed circuit board made of a polyimide film, there is a problem of signal loss of the high-frequency signal due to dielectric loss inherent to the material.

In other words, there are the following problems: the polyimide film has a high dielectric constant, and dielectric loss occurs at the time of transmission and reception of high-frequency signals, resulting in loss of high-frequency signals, and thus disconnection occurs when services such as video call, movie watching, and real-time relay are used.

Further, there are the following problems: a printed circuit board made of a film having a low dielectric constant can minimize loss of high frequency signals, but such a film has a low melting temperature, which reduces heat resistance, so that a high temperature of about 250 c generated in a process of Surface Mount Technology (SMT) for high frequency device mounting may melt a surface, thereby causing defects.

In addition, there is a problem that the low dielectric constant and the high heat resistant film are formed at high prices, so that the manufacturing cost of the printed circuit board is increased, thereby losing market competitiveness.

Disclosure of Invention

Technical problem

The present disclosure is directed to solving the above-mentioned conventional problems, and an object of the present disclosure is to provide a method for manufacturing a flexible printed circuit board in which substrates manufactured of a polytetrafluoroethylene film having high heat resistance and a low dielectric constant are stacked, thereby minimizing dielectric loss caused by high-frequency signals while preventing loss of the high-frequency signals, and a flexible printed circuit board manufactured by the method.

In other words, an object of the present disclosure is to provide a method for manufacturing a flexible printed circuit board, which constitutes a substrate by forming a circuit pattern on a teflon-based material having excellent heat resistance and dielectric characteristics and stacks a plurality of substrates, thereby forming high heat resistance and low dielectric constant characteristics, and a flexible printed circuit board manufactured by the method.

Further, another object of the present disclosure is to provide a method for manufacturing a flexible printed circuit board, which can modify the surface of a polytetrafluoroethylene film to manufacture a multi-layer flexible printed circuit board using the polytetrafluoroethylene film, and a flexible printed circuit board manufactured by the method.

Further, it is still another object of the present disclosure to provide a method for manufacturing a flexible printed circuit board, which can form an adhesive layer of a polytetrafluoroethylene material on a substrate (i.e., a polytetrafluoroethylene film) to manufacture a multi-layer flexible printed circuit board, and a flexible printed circuit board manufactured by the method.

In other words, it is still another object of the present disclosure to provide a method for manufacturing a flexible printed circuit board, which can form a coating adhesive layer on a surface of a polytetrafluoroethylene film by a dip coating or printing method, and then heat, press and adhere the stacked polytetrafluoroethylene films, thereby manufacturing a multi-layer flexible printed circuit board, and a flexible printed circuit board manufactured by the method.

Technical scheme

To achieve these objects, a method for manufacturing a flexible printed circuit board according to an embodiment of the present disclosure includes: preparing a substrate, which is a polytetrafluoroethylene film having a thin film pattern formed thereon; stacking a plurality of substrates; and heating, pressing, and bonding the stacked body in which the plurality of substrates have been stacked. At this time, the preparation substrate operation may prepare a teflon film having a surface modification layer or an adhesive layer of a teflon material formed thereon as a substrate.

To achieve these objects, a flexible printed circuit board according to an embodiment of the present disclosure includes a stacked body in which a plurality of substrates are stacked and a circuit pattern formed on the stacked body, and the substrates include a teflon film on which a thin film pattern is formed. At this time, an adhesive layer or a surface modification layer may be formed on the polytetrafluoroethylene film.

Advantageous effects

According to the present disclosure, a method for manufacturing a flexible printed circuit board and a flexible printed circuit board manufactured by the method may stack a plurality of substrates having high heat resistance and low dielectric constant, thereby minimizing dielectric loss caused by high frequency signals and preventing loss of the high frequency signals.

Further, the method for manufacturing a flexible printed circuit board and the flexible printed circuit board manufactured by the method may stack a substrate made of a polytetrafluoroethylene film having heat resistance and a low dielectric constant to form a dielectric constant lower than that of a conventional flexible printed circuit board composed of a substrate using a polyimide or polypropylene film, thereby manufacturing a flexible printed circuit board having minimized dielectric loss.

In addition, the method for manufacturing the flexible printed circuit board and the flexible printed circuit board manufactured by the method may constitute a substrate using a teflon sheet to improve reliability, thereby preventing deformation and breakage of the flexible printed circuit board due to heat (about 250 ℃) applied in a reflow process.

Further, the method for manufacturing a flexible printed circuit board and the flexible printed circuit board manufactured by the method may use a polytetrafluoroethylene sheet to constitute a substrate, thereby manufacturing a flexible printed circuit board having high heat resistance and low dielectric constant characteristics.

In addition, the method for manufacturing a flexible printed circuit board and the flexible printed circuit board manufactured by the method may form a substrate by adhering a guide film to a polytetrafluoroethylene film, thereby preventing the shape of the polytetrafluoroethylene film from being deformed or broken during the manufacturing process to prevent the manufacturing yield and reliability of the flexible printed circuit board from being lowered.

Further, the method for manufacturing a flexible printed circuit board and the flexible printed circuit board manufactured by the method can stack a plurality of substrates and adhesive sheets by forming guide holes in the substrates and the adhesive sheets and performing a setting such that guide pins formed on a jig pass through the guide holes formed in the substrates and the adhesive sheets and then move them downward, thereby not performing an alignment process of the stacked substrates (in other words, the substrates and the adhesive sheets) during the stacking process, thereby simplifying the manufacturing process.

Further, the method for manufacturing a flexible printed circuit board and the flexible printed circuit board manufactured by the method may stack a plurality of substrates and adhesive sheets by performing an arrangement such that guide pins formed on a jig pass through guide holes formed in the substrates and the adhesive sheets and then move them downward so that thin film patterns formed on the stacked substrates are aligned in an accurate position, thereby preventing a manufacturing yield and reliability of the flexible printed circuit board from being lowered.

Further, the method for manufacturing a flexible printed circuit board and the flexible printed circuit board manufactured by the method may form a surface modification layer of ceramic or oxide on the surface of the polytetrafluoroethylene film to improve the adhesiveness of the surface of the polytetrafluoroethylene film, thereby manufacturing a multi-layer flexible printed circuit board using the polytetrafluoroethylene film having poor adhesiveness.

Further, the method for manufacturing a flexible printed circuit board and the flexible printed circuit board manufactured by the method may form a surface modification layer of ceramic or oxide on the surface of the polytetrafluoroethylene film to improve the adhesiveness of the surface of the polytetrafluoroethylene film, thereby adhering the polytetrafluoroethylene film with adhesive sheets of various materials.

In addition, the method for manufacturing the flexible printed circuit board and the flexible printed circuit board manufactured by the method may form a surface modification layer of ceramic or oxide on the surface of the teflon film to use an adhesive sheet of various materials, thereby minimizing the manufacturing cost of the flexible printed circuit board.

Further, the method for manufacturing a flexible printed circuit board and the flexible printed circuit board manufactured by the method may form an adhesive layer including a polytetrafluoroethylene paste on a surface of a polytetrafluoroethylene film to improve adhesiveness of the surface of the polytetrafluoroethylene film, thereby manufacturing a multi-layer flexible printed circuit board using the polytetrafluoroethylene film having poor adhesiveness.

Drawings

Fig. 1 and 2 are diagrams for explaining a method for manufacturing a flexible printed circuit board according to a first embodiment of the present disclosure.

Fig. 3 and 4 are diagrams for explaining the preparation substrate in fig. 1.

Fig. 5 and 6 are views for explaining the stacked substrate and the adhesive sheet in fig. 1.

Fig. 7 is a diagram for explaining a flexible printed circuit board according to a first embodiment of the present disclosure.

Fig. 8 and 9 are diagrams for explaining a method for manufacturing a flexible printed circuit board according to a second embodiment of the present disclosure.

Fig. 10 to 15 are diagrams for explaining the preparation substrate in fig. 8.

Fig. 16 and 17 are diagrams for explaining the stack in fig. 8.

Fig. 18 to 23 are diagrams for explaining a flexible printed circuit board according to a second embodiment of the present disclosure.

Fig. 24 and 25 are diagrams for explaining a method for manufacturing a flexible printed circuit board according to a third embodiment of the present disclosure.

Fig. 26 to 31 are diagrams for explaining the preparation substrate in fig. 24.

Fig. 32 and 33 are diagrams for explaining the stack in fig. 24.

Fig. 34 is a diagram for explaining a flexible printed circuit board according to a third embodiment of the present disclosure.

Detailed Description

Hereinafter, the most preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings, so that those skilled in the art to which the present disclosure pertains can easily realize the technical spirit of the present disclosure. First, when a reference numeral is added to a component of each drawing, it should be noted that the same component has the same reference numeral as much as possible even if the same component is displayed on different drawings. In addition, in describing the present disclosure, when it is determined that a detailed description of a related well-known configuration or function may make the gist of the present disclosure unclear, the detailed description will be omitted.

Referring to fig. 1 and 2, a method for manufacturing a flexible printed circuit board according to a first embodiment of the present disclosure includes: preparing a substrate (S110), preparing an adhesive sheet (S120), stacking (S130), bonding (S140), forming a via hole (S150), and forming a connection pattern (S160).

The preparation substrate operation (S110) prepares a substrate 110, sequentially stacks a guide film 112, a teflon film 111, and a thin film pattern 116, and forms a guide hole penetrating the guide film 112 and the teflon film 111 therein. At this time, the guide pins 220 of the jig 200 are inserted into the guide holes so as to be easily stacked (S130), which will be described later.

Referring to fig. 3 and 4, the preparing a substrate operation (S110) includes bonding a teflon film and a guide film (S111), forming a seed layer (S113), forming a plating layer (S115), forming a thin film pattern (S117), and forming a first guide hole (S119).

The adhering polytetrafluoroethylene film and the guiding film operation (S111) prepare a polytetrafluoroethylene film 111 having heat resistance and a low dielectric constant. In other words, after the manufacturing is completed, the flexible printed circuit board is mounted together with the semiconductor element by a surface mount technology process (in other words, an SMT process).

At this time, there are the following problems: the high frequency flexible printed circuit board in the development stage uses polypropylene having a heat resistance of about 160 to 180 c to constitute the substrate 110, so that the substrate 110 is deformed or broken due to heat (about 250 c) applied in a reflow process of the surface mounting technology process.

In order to prevent the reliability of the flexible printed circuit board from being reduced in the case where the substrate 110 is deformed or broken, the method for manufacturing the flexible printed circuit board according to the embodiment of the present disclosure uses the polytetrafluoroethylene film 111 to constitute the substrate 110.

At this time, since the polytetrafluoroethylene film 111 is not deformed even by heat of about 300 ℃, deformation and breakage of the substrate due to heat applied in the reflow process can be prevented.

Accordingly, the bonding of the polytetrafluoroethylene film and the guiding film operation (S111) uses the polytetrafluoroethylene film 111 to construct the substrate 110.

Thus, the method for manufacturing a flexible printed circuit board and the flexible printed circuit board manufactured by the method can prevent deformation and breakage of the flexible printed circuit board due to heat (about 250 ℃) applied in a reflow process, thereby improving reliability.

Polytetrafluoroethylene is mainly used as a lubricant, a release material, and an insulating material. Since polytetrafluoroethylene has optimum heat resistance and dielectric properties (in other words, low dielectric constant) among polymer materials, it is used as a base material for high-frequency printed circuit boards that require low dielectric constant and heat resistance.

However, since polytetrafluoroethylene is soft-melting and thermoplastic, heat and pressure applied during the manufacturing process deform the base material, resulting in a high defective rate. Therefore, polytetrafluoroethylene is mainly used as a thick and hard single-sided or double-sided substrate.

In the embodiment of the present disclosure, a thin-film teflon film 111 is used as the substrate 110 to manufacture a flexible printed circuit board. Due to the reflow property of ptfe, the ptfe film 111 is deformed or broken even if the pressure applied during the manufacturing process is small, thereby reducing the manufacturing yield and reliability of the flexible printed circuit board.

Accordingly, the adhering of the polytetrafluoroethylene film and the guide film operation (S111) adheres the guide film 112 to one surface of the polytetrafluoroethylene film 111 to prevent the polytetrafluoroethylene film 111 from being deformed and broken during the manufacturing process.

At this time, for example, the guide film 112 is a hard polyethylene terephthalate (PET) film.

The polytetrafluoroethylene film and guide film bonding operation (S111) bonds the polytetrafluoroethylene film 111 and the guide film 112 by interposing an adhesive sheet 113 between the polytetrafluoroethylene film 111 and the guide film 112. In other words, since the guide film 112 should be removed in the stacking operation (S130) described later, the operation (S111) of bonding the polytetrafluoroethylene film and the guide film couples the polytetrafluoroethylene film 111 and the guide film 112 in an adhered state (in other words, the adhesive sheet 113), so that the guide film 112 can be easily removed while supporting the polytetrafluoroethylene film 111. Here, the adhesive sheet 113 is, for example, a silicone (Si) -based adhesive.

As described above, the method for manufacturing a flexible printed circuit board according to the embodiment of the present disclosure may form the substrate 110 by adhering the guide film 112 to the polytetrafluoroethylene film 111 to prevent the polytetrafluoroethylene film 111 from being deformed or broken during the manufacturing process, thereby preventing the manufacturing yield and reliability of the flexible printed circuit board from being lowered.

The seed layer forming operation (S113) forms a seed layer 114 of a thin film on one surface of the polytetrafluoroethylene film 111. The seed layer forming operation (S113) forms a seed layer 114 on the other surface of the polytetrafluoroethylene film 111 (in other words, the surface opposite to the one surface to which the guide film 112 has been bonded) by a deposition process or a sputtering process. Here, the seed layer forming operation (S113) forms a seed layer 114 of a mixed material of mixed nickel copper (NiCu) and copper (Cu) or nickel copper (NiCu) material on the other surface of the polytetrafluoroethylene film 111.

The plating layer forming operation (S115) forms a plating layer 115 on the seed layer 114. At this time, the plating layer forming operation (S115) forms a plating layer 115 on the seed layer 114 by electroplating copper (Cu).

Here, the seed layer 114 and the plating layer 115 are elements constituting a circuit pattern, and are formed to a thickness of about 5 μm.

The thin film pattern forming operation (S117) forms a thin film pattern 116 on the other surface of the teflon film 111. In other words, the thin film pattern forming operation (S117) forms the thin film pattern 116 of a predetermined shape by removing a part of the seed layer 114 and the plating layer 115 formed on the other surface of the polytetrafluoroethylene film 111 through an etching process.

The forming of the first guide holes (S119) forms a plurality of first guide holes 117 passing through the polytetrafluoroethylene film 111 and the guide film 112. In other words, the forming of the first guide holes (S119) forms a plurality of first guide holes 117 to align the substrate 110 in an accurate position while firmly fixing the substrate 110 to the jig 200 in the stacking operation (S130) to be described later. Here, the forming of the first guide hole operation (S119) forms the first guide hole 117 in the substrate 110 through a punching process, a laser drilling process, or the like.

The adhesive sheet preparing operation (S120) prepares the adhesive sheet 120 having the plurality of second guide holes 122 formed therein. At this time, the preparation of the adhesive sheet operation (S120) forms second guide holes 122 at positions corresponding to the first guide holes 117 when the substrate 110 and the adhesive sheet 120 are stacked.

The adhesive sheet preparation operation (S120) may prepare an adhesive sheet 120 having a multilayer structure that forms an adhesive layer on one surface or both surfaces of a film substrate.

For example, the adhesive sheet 120 may be a low dielectric constant cast polypropylene (CPP) film having low dielectric loss. At this time, the CPP film is formed as a multi-layer structure having an adhesive layer formed on one or both surfaces of a polypropylene (PP) film (hereinafter, referred to as a PP film).

Here, the adhesive layer may be made of a composite material configured by mixing the same material as the CPP film, for example, a material of Polyethylene (PE), polypropylene (PP), polyimide, etc., and an additive, for example, acrylate, etc., to increase the adhesive force between the polymer, in other words, the polytetrafluoroethylene film 111 of the substrate 110, and the metal, in other words, the thin film pattern 116.

The adhesive sheet preparation operation (S120) may also prepare an adhesive sheet 120 having a single-layer structure.

At this time, for example, the adhesive sheet preparation operation (S120) prepares an adhesive sheet 120 made of a composite material obtained by mixing a material such as polyethylene, polypropylene, or polyimide with an additive, having excellent adhesive properties with a polymer and a metal.

Preparation of adhesive sheet operation (S120) an adhesive sheet 120 of polytetrafluoroethylene material may also be prepared.

The stacking operation (S130) stacks a plurality of substrates 110 and adhesive sheets 120. At this time, the stacking operation (S130) inserts the adhesive sheet 120 between the substrates 110 by alternately stacking the substrates 110 and the adhesive sheet 120.

The stacking operation (S130) stacks a plurality of substrates 110 and adhesive sheets 120 by using the jig 200. In other words, the stacking operation (S130) may provide reliability of the flexible printed circuit board only when the thin film patterns 116 of the substrate 110 are stacked to be aligned at an accurate position.

Accordingly, the stacking operation (S130) stacks the plurality of substrates 110 and the adhesive sheets 120 by using the jig 200 including the guide pins 220.

An example of the stacking operation (S130) of stacking the two substrates 110, in other words, the first substrate 110a and the second substrate 110b, and the adhesive sheet 120 will be described below with reference to fig. 5 and 6.

The stacking operation (S130) includes stacking the first substrate 110a (S131), removing the guide film 112a of the first substrate 110a (S133), stacking the adhesive sheet 120(S135), stacking the second substrate 110b (S137), and removing the guide film 112b of the second substrate 110b (S139).

The stacking first substrate 110a operation (S131) stacks the first substrate 110a on the jig 200. In other words, the operation of stacking the first substrate 110a (S131) stacks the first substrate 110a on the jig 200 by setting such that the guide pins 220 of the jig 200 pass through the first guide holes 117a of the first substrate 110a, respectively, and then move downward.

At this time, the stacking of the first substrate 110a operation (S131) stacks the first substrate 110a such that the thin film pattern 116a formed on the first substrate 110a is placed downward, so that the guide film 112a is easily removed. In other words, the stacking of the first substrate 110a (S131) sets the guide film 112a on top by stacking the first substrate 110a such that the thin film pattern 116a is placed downward.

The operation (S133) of removing the guide film 112a of the first substrate 110a removes the guide film 112a from the first substrate 110a stacked on the jig 200. In other words, the operation (S133) of removing the guide film 112a of the first substrate 110a removes the guide film 112a and the adhesive film 113a disposed on the top of the first substrate 110 a.

The stack adhesive sheet 120 operation (S135) stacks the adhesive sheet 120 on the jig 200. In other words, the operation of stacking the adhesive sheets 120(S135) stacks the adhesive sheets on the jig 200 by setting such that the guide pins 220 of the jig 200 pass through the second guide holes 122 of the adhesive sheets 120, respectively, and then move downward. At this time, the stack adhesive sheet 120 operation (S135) stacks the adhesive sheet 120 on the first substrate 110a stacked on the jig 200.

The operation of stacking the second substrate 110b (S137) stacks the second substrate 110b on the jig 200. In other words, the operation of stacking the second substrate 110b (S137) stacks the second substrate 110b on the jig 200 by setting such that the guide pins 220 of the jig 200 pass through the first guide holes 117b of the second substrate 110b, respectively, and then move downward.

At this time, the stacking of the second substrate 110b operation (S137) stacks the second substrate 110b on the adhesive sheet 120 stacked on the jig 200. The operation of stacking the second substrate 110b (S137) stacks the second substrate 110b such that one surface formed with the thin film pattern 116b is disposed on the adhesive sheet 120.

The operation (S139) of removing the guide film 112b of the second substrate 110b removes the guide film 112b from the second substrate 110b stacked on the jig 200. In other words, the operation (S139) of removing the guide film 112b of the second substrate 110b removes the guide film 112b and the adhesive film 113b disposed on the top of the second substrate 110 b.

As described above, the method for manufacturing a flexible printed circuit board may stack a plurality of substrates 110 and adhesive sheets 120 by performing the following arrangement in the stacking operation (S130) such that the guide pins 220 formed on the jig 200 pass through the guide holes (in other words, the first guide holes 117 and the second guide holes 122) formed in the substrates 110 and the adhesive sheets 120 and then move them downward, without performing the alignment process of the stacked substrates (in other words, the substrates 110 and the adhesive sheets 120) during the stacking process, thereby simplifying the manufacturing process.

Further, the method for manufacturing a flexible printed circuit board may stack a plurality of substrates 110 and adhesive sheets 120 by performing a setting in the stacking operation (S130) such that the guide pins 220 formed on the jig 200 pass through the guide holes (in other words, the first guide holes 117 and the second guide holes 122) formed in the substrates 110 and the adhesive sheets 120 and then move them downward to align the thin film patterns 116 formed on the stacked substrates 110 in an accurate position, thereby preventing the manufacturing yield and reliability of the flexible printed circuit board from being lowered.

The bonding operation (S140) constitutes a stacked body by bonding the plurality of substrates 110 and the adhesive sheets 120 stacked on the jig 200.

For example, the bonding operation (S140) constitutes a stacked body by compressing and preliminarily bonding the plurality of substrates 110 and the adhesive sheets 120, and then mainly bonding the plurality of substrates 110 and the adhesive sheets 120.

Here, the preliminary bonding compresses the plurality of substrates 110 and the adhesive sheets 120 stacked on the jig 200 by, for example, a Water Injection Molding (WIM) process, i.e., compression by applying high water pressure.

For example, the main bonding bonds the preliminarily bonded plurality of substrates 110 and the adhesive sheet 120 through a hot press process applying predetermined pressure and heat. At this time, the main bonding (in other words, the hot press process) bonds the plurality of substrates 110 and the adhesive sheet 120 by applying a pressure lower than that of the preliminary bonding (in other words, the water injection molding process).

If the adhesive sheet 120 is made of a teflon material, the main bonding applies pressure at a temperature of about 300 c or higher.

The bonding operation (S140) constitutes a stacked body by completing the bonding of the plurality of substrates 110 and the adhesive sheets 120, and then separates the stacked body from the jig 200.

The forming vias operation (S150) forms one or more vias 130 through the stack. In other words, the forming of the through-hole (S150) forms the through-hole 130 in the stacked body separated from the jig 200 through a punching process, a laser drilling process, or the like.

Here, although it has been shown in fig. 1 and 2 that a plurality of substrates 110 and adhesive sheets 120 are stacked and adhered to each other and then the through-holes 130 are formed therein, it is not limited thereto and the respective substrates 110 and adhesive sheets 120 may be stacked and adhered to each other after the through-holes 130 are formed therein.

The forming connection pattern operation (S160) forms connection patterns 140 in the through holes 130 to electrically connect (in other words, electrically conduct) the thin film patterns 116 formed on the plurality of substrates 110, respectively. At this time, the operation of forming the connection pattern (S160) forms the connection pattern 140 by filling the conductive material in the via hole 130. Here, the operation of forming the connection pattern (S160) may also form the connection pattern 140 by plating a conductive material on the inner wall surface of the through hole 130 and on the thin film pattern 116 exposed outside the stacked body.

Meanwhile, the method for manufacturing a flexible printed circuit board may further include forming a protective layer on an upper surface of a stacked body configured by stacking a plurality of substrates 110 and adhesive sheets 120.

The forming of the protective layer operation forms a protective layer covering the thin film pattern 116 and the surface of the substrate 110 by applying and curing a coating liquid on the surfaces of the thin film pattern 116 and the base material stacked on the uppermost portion of the stack body. At this time, the protective layer may be made of a composite material containing resin such as polypropylene and polyimide.

In addition, the method for manufacturing a flexible printed circuit board may further include forming the electrode part. At this time, the operation of forming the electrode portion may form the electrode portion by removing a portion of the protective layer and then plating a conductive material such as copper on the corresponding region. Here, the electrode portion may be formed on at least one of the plurality of thin film patterns 116 disposed on the upper surface of the stack body.

Referring to fig. 7, a printed circuit board manufactured by the method for manufacturing a flexible printed circuit board according to an embodiment of the present disclosure is configured to include: a stacked body in which a plurality of substrates 110 and adhesive sheets 120 are alternately stacked and then adhered to each other; and a circuit pattern formed in the stacked body and on an upper surface of the stacked body.

Since the stacked body is constructed by alternately stacking a plurality of substrates 110 and adhesive sheets 120, the stacked body is constructed by repeatedly stacking the polytetrafluoroethylene film 111 and the adhesive sheets 120. At this time, in the stacked body, the adhesive sheet 120 is inserted between the polytetrafluoroethylene films 111.

At this time, although it is illustrated in fig. 7 that the adhesive sheet 120 is configured as a single layer, it is not limited thereto, and the adhesive sheet may be configured as a multi-layer structure.

The circuit pattern is composed of thin film patterns 116 exposed on the upper surface of the stack, thin film patterns 116 inserted in the stack, and connection patterns 140 electrically connecting the thin film patterns.

In other words, when the substrates 110 are stacked together, among the circuit patterns, the thin film pattern 116 formed on the substrate 110 stacked on the uppermost portion of the stack is exposed to the upper surface of the stack, and the thin film patterns 116 formed on the other substrates 110 are inserted into the stack. At this time, the thin film patterns 116 are electrically connected (in other words, electrically conducted) by the connection patterns 140 formed in the via holes 130.

Here, although it has been illustrated in fig. 7 that the connection pattern 140 is formed by filling in the through hole 130, it is not limited thereto, and the connection pattern 140 may be formed by plating on the inner wall surface of the through hole 130.

Referring to fig. 8 and 9, a method for manufacturing a flexible printed circuit board according to a second embodiment of the present disclosure includes: preparing a substrate (S210), preparing an adhesive sheet (S230), stacking (S240), bonding (S250), forming a via hole (S260), and forming a connection pattern (S270).

The preparation substrate operation (S210) prepares a substrate 310, sequentially stacks a guide film 312, a teflon film 311, and a thin film pattern 316, and forms a guide hole passing through the guide film 312 and the teflon film 311 therein. At this time, the guide pins 220 of the jig 200 are inserted into the guide holes so as to easily perform a stacking operation (S240), which will be described later.

The preparing a substrate operation (S210) forms surface modification layers 318 on both surfaces (in other words, upper and lower surfaces) of the polytetrafluoroethylene film to improve the adhesiveness of the polytetrafluoroethylene film. At this time, the preparing substrate operation (S210) may form the surface modification layer 318 only on one surface to be adhered to the adhesive sheet 320 among the upper and lower surfaces of the polytetrafluoroethylene film. Here, for example, the surface modification layer 318 may be a ceramic (e.g., titanium dioxide (TiO) having excellent adhesiveness with an adhesive sheet 320 of various materials₂) Or an oxide.

Referring to fig. 10 and 11, the preparation of a substrate operation (S210) forms a surface modification layer 318 on one surface of polytetrafluoroethylene 311. To this end, the preparing a substrate operation (S210) includes: bonding a polytetrafluoroethylene film and a guide film (S211), forming a seed layer (S212), forming a plating layer (S213), forming a thin film pattern (S214), forming a surface modification layer (S215), and forming a first guide hole (S216).

The adhering polytetrafluoroethylene film and the guiding film operation (S211) prepare a polytetrafluoroethylene film 311 having heat resistance and a low dielectric constant. In other words, after the manufacturing is completed, the flexible printed circuit board is mounted together with the semiconductor element by a surface mount technology process (in other words, an SMT process).

At this time, there are the following problems: the high frequency flexible printed circuit board in the development stage uses polypropylene having a heat resistance of about 160 to 180 c to constitute the substrate 310, so that the substrate 310 is deformed or broken due to heat (about 250 c) applied in a reflow process of the surface mounting technology process.

In order to prevent the reliability of the flexible printed circuit board from being reduced in the case where the substrate 310 is deformed or broken, the method for manufacturing the flexible printed circuit board according to the embodiment of the present disclosure uses the polytetrafluoroethylene film 311 to constitute the substrate 310.

At this time, since the polytetrafluoroethylene film 311 is not deformed even by heat of about 300 ℃, deformation and breakage of the substrate due to heat applied in the reflow process can be prevented.

Accordingly, the bonding of the polytetrafluoroethylene film and the guiding film operation (S211) uses the polytetrafluoroethylene film 311 to construct the substrate 310.

Thus, the method for manufacturing a flexible printed circuit board and the flexible printed circuit board manufactured by the method can prevent deformation and breakage of the flexible printed circuit board due to heat (about 250 ℃) applied in a reflow process, thereby improving reliability.

Polytetrafluoroethylene is mainly used as a lubricant, a release material, and an insulating material. Since polytetrafluoroethylene has optimum heat resistance and dielectric properties (in other words, low dielectric constant) among polymer materials, it is used as a base material for high-frequency printed circuit boards that require low dielectric constant and heat resistance.

However, since polytetrafluoroethylene is soft-fusible and thermoplastic, heat and pressure applied during the manufacturing process deform the base material, resulting in a high defective rate. Therefore, polytetrafluoroethylene is mainly used as a thick and hard single-sided or double-sided substrate.

The embodiment of the present disclosure manufactures a flexible printed circuit board using a thin-film teflon film 311 as a substrate 310. Due to the reflow property of ptfe, the ptfe film 111 is deformed or broken even if the pressure applied during the manufacturing process is small, thereby reducing the manufacturing yield and reliability of the flexible printed circuit board.

Accordingly, the adhering polytetrafluoroethylene film and guiding film operation (S211) adheres the guiding film 312 to one surface of the polytetrafluoroethylene film 311 to prevent deformation and breakage of the polytetrafluoroethylene film 311 during the manufacturing process.

At this time, the guide film 312 is, for example, a hard polyethylene terephthalate (PET) film.

The polytetrafluoroethylene film and guide film bonding operation (S211) bonds the polytetrafluoroethylene film 311 and the guide film 312 by inserting the adhesive sheet 313 between the polytetrafluoroethylene film 311 and the guide film 312. In other words, since the guide film 312 should be removed in the stacking operation (S240) described later, the operation (S211) of bonding the polytetrafluoroethylene film and the guide film couples the polytetrafluoroethylene film 311 and the guide film 312 in an adhered state (in other words, the adhesive sheet 313), so that the guide film 312 can be easily removed while supporting the polytetrafluoroethylene film 311. Here, the adhesive sheet 313 is, for example, a silicone (Si) -based adhesive.

As described above, the method for manufacturing a flexible printed circuit board according to the embodiment of the present disclosure may form the substrate 310 by adhering the guide film 312 to the polytetrafluoroethylene film 311 to prevent the polytetrafluoroethylene film 311 from being deformed or broken during the manufacturing process, thereby preventing the manufacturing yield and reliability of the flexible printed circuit board from being lowered.

The seed layer formation operation (S212) forms a seed layer 314 of a thin film on one surface of the polytetrafluoroethylene film 311. The seed layer forming operation (S212) forms a seed layer 314 on the other surface of the polytetrafluoroethylene film 311 (in other words, the surface opposite to the surface to which the guide film 312 has been bonded) by a deposition process or a sputtering process. Here, the seed layer forming operation (S212) forms a seed layer 314 of a mixed material of mixed nickel copper (NiCu) and copper (Cu) or nickel copper (NiCu) material on the other surface of the polytetrafluoroethylene film 311.

The plating layer forming operation (S213) forms a plating layer 315 on the seed layer 314. At this time, the plating layer forming operation (S213) forms a plating layer 315 on the seed layer 314 by electroplating copper (Cu).

Here, the seed layer 314 and the plating layer 315 are elements constituting a circuit pattern, and are formed to a thickness of about 5 μm.

The thin film pattern forming operation (S214) forms a thin film pattern 316 on the other surface of the teflon film 311. In other words, the thin film pattern forming operation (S214) forms the thin film pattern 316 of a predetermined shape by removing a part of the seed layer 314 and the plating layer 315 formed on the other surface of the polytetrafluoroethylene film 311 through an etching process.

The forming of the surface modification layer operation (S215) forms a surface modification layer 318 on one surface of the polytetrafluoroethylene film 311. In other words, the forming of the surface modification layer operation (S215) forms the surface modification layer 318 on one of the two surfaces (in other words, the upper surface and the lower surface) of the polytetrafluoroethylene film 311 on which the thin film pattern 316 has been formed. At this time, the surface modification layer 318 is formed on the upper surface and the periphery of the thin film pattern 316 and the upper surface of the polytetrafluoroethylene film 311 exposed to the space between the thin film patterns 316.

Forming a surface modification layer operation (S215) the surface modification layer 318 is formed by depositing a ceramic or an oxide on one surface of the teflon film 311 by a sputtering process as a vacuum deposition method. At this time, the surface modification layer 318 is a material selected from ceramics, oxides, nitrides and carbonates having excellent adhesion with the adhesive sheet 320, and the sputtering process is, for example, an oxide sputtering process.

As described above, the method for manufacturing a flexible printed circuit board may form the surface modification layer 318 of ceramic or oxide on the surface of the polytetrafluoroethylene film to improve the adhesiveness of the surface of the polytetrafluoroethylene film, thereby manufacturing a multi-layered flexible printed circuit board using the polytetrafluoroethylene film having poor adhesiveness, and adhere the polytetrafluoroethylene film to adhesive sheets of various materials, thereby minimizing the manufacturing cost of the flexible printed circuit board.

The forming of the first guide hole operation (S216) forms a plurality of first guide holes 317 passing through the surface modification layer 318, the teflon film 311, and the guide film 312. In other words, the forming of the first guide holes (S216) forms a plurality of first guide holes 317 to align the substrate 310 in a correct position while firmly fixing the substrate 310 to the jig 200 in the stacking operation (S240) to be described later. Here, the forming of the first guide hole (S216) forms the first guide hole 317 in the substrate 310 through a punching process, a laser drilling process, or the like.

Referring to fig. 12 and 13, the forming of the surface modification layer operation (S215) may include: forming a first surface modification layer (S217), removing the guide film (S218), and forming a second surface modification layer (S219).

The operation of forming the first surface modification layer (S217) forms a first surface modification layer 318a on one surface of the polytetrafluoroethylene film 311. In other words, the operation of forming the first surface modification layer (S217) forms the first surface modification layer 318a on one of the two surfaces (in other words, the upper and lower surfaces) of the polytetrafluoroethylene film 311 on which the thin-film pattern 316 has been formed. At this time, the first surface modification layer 318a is formed on the upper surface and the periphery of the thin film patterns 316 and the upper surface of the polytetrafluoroethylene film 311 exposed to the space between the thin film patterns 316.

Forming the first surface modification layer operation (S217) the first surface modification layer 318a is formed by depositing ceramic or oxide on one surface of the teflon film 311 by a sputtering process, which is a vacuum deposition method. At this time, the first surface modification layer 318a is a material selected from ceramics, oxides, nitrides and carbonates having excellent adhesion with the adhesive sheet 320, and the sputtering process is, for example, an oxide sputtering process.

The removing guide film operation (S218) removes the guide film 312 adhered on the other surface of the polytetrafluoroethylene film 311. In other words, the removal guide film operation (S218) is a previous operation for forming the second surface modification layer 318b on the other surface of the polytetrafluoroethylene film 311, which removes the guide film 312 and the adhesive film 313 adhered on the other surface of the polytetrafluoroethylene film 311.

The operation of forming a second surface modification layer (S219) forms a second surface modification layer 318b on the other surface of the polytetrafluoroethylene film 311. In other words, the operation of forming the second surface modification layer (S219) forms the second surface modification layer 318b by depositing ceramic or oxide on the other surface of the polytetrafluoroethylene film 311 (in other words, the lower surface from which the guide film 312 has been removed) by a sputtering process which is a vacuum deposition method. At this time, the second surface modification layer 318b is a material selected from ceramics, oxides, nitrides and carbonates having excellent adhesion with the adhesive sheet 320, and the sputtering process is, for example, an oxide sputtering process.

The forming of the first guide hole operation (S216) forms a plurality of first guide holes 317 passing through the first surface modification layer 318a, the teflon film 311, and the second surface modification layer 318 b. In other words, the forming of the first guide holes (S216) forms a plurality of first guide holes 317 to align the substrate 310 in a correct position while firmly fixing the substrate 310 to the jig 200 in the stacking operation (S240) to be described later. Here, the forming of the first guide hole (S216) forms the first guide hole 317 in the substrate 310 through a punching process, a laser drilling process, or the like.

Referring to fig. 14 and 15, the preparation substrate operation (S210) forms a surface modification layer 318 on at least one of both surfaces of the teflon film 311. To this end, the preparing a substrate operation (S210) includes: forming a surface modification layer (S221), bonding a polytetrafluoroethylene film and a guide film (S222), forming a seed layer (S223), forming a plating layer (S224), forming a thin film pattern (S225), and forming a first guide hole (S226).

The surface modification layer forming operation (S221) forms a surface modification layer 318 on the surface of the polytetrafluoroethylene film 311. At this time, although it is illustrated in fig. 15 that the surface modification layer 318 is formed on both surfaces (in other words, the upper surface and the lower surface) of the polytetrafluoroethylene film 311, it is not limited thereto, and the surface modification layer 318 may be formed only on one of both surfaces of the polytetrafluoroethylene film 311.

In other words, the operation of forming the surface modification layer (S221) may form the surface modification layer 318 only on one of the two surfaces of the polytetrafluoroethylene film 311 on which the thin film pattern 316 is to be formed, or form the surface modification layer 318 only on one of the two surfaces of the polytetrafluoroethylene film 311 on which the guide film is to be adhered.

Forming a surface modification layer operation (S221) the surface modification layer 318 is formed by depositing a ceramic or an oxide on the surface of the teflon film 311 by a sputtering process as a vacuum deposition method. At this time, the surface modification layer 318 is a material selected from ceramics, oxides, nitrides and carbonates having excellent adhesion properties with the adhesive sheet 320, and the sputtering process is, for example, an oxide sputtering process.

As described above, the method for manufacturing a flexible printed circuit board may form the surface modification layer 318 of ceramic or oxide on the surface of the polytetrafluoroethylene film to improve the adhesiveness of the surface of the polytetrafluoroethylene film, thereby manufacturing a multi-layered flexible printed circuit board using the polytetrafluoroethylene film having poor adhesiveness, and adhere the polytetrafluoroethylene film to adhesive sheets of various materials, thereby minimizing the manufacturing cost of the flexible printed circuit board.

The adhering of the teflon film and the guide film operation (S222) adheres the guide film 312 to one surface of the teflon film 311 to prevent deformation or breakage of the teflon film 311 during the manufacturing process of the flexible printed circuit board. At this time, the guide film 312 is, for example, a hard polyethylene terephthalate (PET) film.

The polytetrafluoroethylene film and guide film bonding operation (S222) bonds the polytetrafluoroethylene film 311 and the guide film 312 by inserting an adhesive sheet 313 between the surface modification layer 318 and the guide film 312 formed on one surface (in other words, the lower surface) of the polytetrafluoroethylene film 311. In other words, since the guide film 312 should be removed in the stacking operation (S240) described later, the adhering polytetrafluoroethylene film and guide film operation (S222) couples the polytetrafluoroethylene film 311 and the guide film 312 in a stuck state (in other words, the adhesive sheet 313) so that the guide film 112 can be easily removed while supporting the polytetrafluoroethylene film 311. Here, the adhesive sheet 313 is, for example, a silicone (Si) -based adhesive.

Meanwhile, if a hard surface modification layer is formed in S221, the operations of bonding the polytetrafluoroethylene film and guiding the film (S222) may be omitted.

As described above, the method for manufacturing a flexible printed circuit board according to the embodiment of the present disclosure may form the substrate 310 by adhering the guide film 312 to the polytetrafluoroethylene film 311 to prevent the polytetrafluoroethylene film 311 from being deformed or broken during the manufacturing process, thereby preventing the manufacturing yield and reliability of the flexible printed circuit board from being lowered.

The seed layer forming operation (S223) forms a seed layer 314 of a thin film on one surface of the polytetrafluoroethylene film 311. The seed layer forming operation (S223) forms a seed layer 314 on an upper surface of the surface modification layer 318 formed on the other surface (in other words, an upper surface) of the polytetrafluoroethylene film 311 by a deposition process or a sputtering process. Here, the seed layer forming operation (S223) forms a seed layer 314 of a mixed material of mixed nickel copper (NiCu) and copper (Cu) or nickel copper (NiCu) material on the other surface of the polytetrafluoroethylene film 311.

The plating layer forming operation (S224) forms a plating layer 315 on the seed layer 314. At this time, the forming plating operation (S224) forms a plating layer 315 on the seed layer 314 by electroplating copper (Cu).

Here, the seed layer 314 and the plating layer 315 are elements constituting a circuit pattern, and are formed to a thickness of about 5 μm.

The thin film pattern forming operation (S225) forms a thin film pattern 316 on the other surface of the teflon film 311. In other words, the thin film pattern forming operation (S225) forms the thin film pattern 316 of a predetermined shape by removing a part of the seed layer 314 and the plating layer 315 formed on the other surface of the polytetrafluoroethylene film 311 through an etching process.

The operation (S226) of forming the first guide hole 317 forms a plurality of first guide holes 317 passing through the surface modification layer 318, the teflon film 311, and the guide film 312. In other words, the forming of the first guide holes 317 operation (S226) forms a plurality of first guide holes 317 to align the substrate 310 in a correct position while firmly fixing the substrate 310 to the jig 200 in the stacking operation (S240) to be described later. Here, the operation (S226) of forming the first guide hole 317 forms the first guide hole 317 in the substrate 310 through a punching process, a laser drilling process, or the like.

The adhesive sheet preparing operation (S230) prepares an adhesive sheet 320 in which a plurality of second guide holes 322 are formed in the adhesive sheet 320. At this time, the preparation of the adhesive sheet operation (S230) forms the second guide holes 322 at positions corresponding to the first guide holes 317 when the substrate 310 and the adhesive sheet 320 are stacked.

The adhesive sheet preparation operation (S230) may prepare an adhesive sheet 320 of a multilayer structure in which an adhesive layer is formed on one surface or both surfaces of a film substrate.

For example, the adhesive sheet 320 may be a low dielectric constant cast polypropylene (CPP) film having low dielectric loss. At this time, the CPP film is formed as a multi-layer structure in which an adhesive layer is formed on one surface or both surfaces of a polypropylene (PP) film (hereinafter, PP film).

Here, the adhesive layer is made of a composite material that mixes the same material as the CPP film (a material such as Polyethylene (PE), polypropylene (PP), polyimide, etc.) and an additive (such as acrylate, etc.) to increase adhesion with a polymer (in other words, the polytetrafluoroethylene film 311 of the substrate 310) and a metal (in other words, the thin film pattern 316).

The adhesive sheet preparation operation (S230) may also prepare an adhesive sheet 320 having a single-layer structure. At this time, for example, the adhesive sheet preparation operation (S230) prepares an adhesive sheet 320 made of a composite material obtained by mixing a material such as polyethylene, polypropylene or polyimide with an additive, the adhesive sheet having excellent adhesiveness with polymers and metals.

The stacking operation (S240) stacks a plurality of substrates 310 and adhesive sheets 320. At this time, the stacking operation (S240) inserts the adhesive sheet 320 between the substrates 310 by alternately stacking the substrates 310 and the adhesive sheet 320.

The stacking operation (S240) stacks a plurality of substrates 310 and adhesive sheets 320 by using the jig 200. In other words, the stacking operation (S240) may provide reliability of the flexible printed circuit board only when the thin film patterns 316 of the substrate 310 are stacked to be aligned at an accurate position.

Accordingly, the stacking operation (S240) stacks the plurality of substrates 310 and the adhesive sheets 320 by using the jig 200 including the guide pins 220.

An example of the stacking operation (S240) of stacking the two substrates 310, in other words, the first and second substrates 310a and 310b, and the adhesive sheet 320 will be described below with reference to fig. 16 and 17.

The stacking operation (S240) includes: stacking the first substrate 310a (S241), removing the guide film 312a of the first substrate 310a (S243), stacking the adhesive sheet 320(S245), stacking the second substrate 310b (S247), and removing the guide film 312b of the second substrate 310b (S249).

The stacking of the first substrate 310a operation (S241) stacks the first substrate 310a on the jig 200. In other words, the operation of stacking the first substrate 310a (S241) stacks the first substrate 310a on the jig 200 by performing the setting such that the guide pins 220 of the jig 200 pass through the first guide holes 317a of the first substrate 310a, respectively, and then move downward.

At this time, the stacking of the first substrate 310a operation (S241) stacks the first substrate 310a such that the thin film pattern 316a formed on the first substrate 310a is placed downward, so that the guide film 312a is easily removed. In other words, the stacking of the first substrate 310a (S241) sets the guide film 312a on top by stacking the first substrate 310a such that the thin film pattern 316a is placed downward.

The operation (S243) of removing the guide film 312a of the first substrate 310a removes the guide film 312a from the first substrate 310a stacked on the jig 200. In other words, the operation (S243) of removing the guide film 312a of the first substrate 310a removes the guide film 312a and the adhesive film 313a of the first substrate 310a disposed on the top.

The stack adhesive sheet 320 operation (S245) stacks the adhesive sheet 320 on the jig 200. In other words, the operation of stacking the adhesive sheets 320(S245) stacks the adhesive sheets 320 on the jig 200 by performing a setting such that the guide pins 220 of the jig 200 pass through the second guide holes 322 of the adhesive sheets 320, respectively, and then move downward. At this time, the stack adhesive sheet 320 operation (S245) stacks the adhesive sheet 320 on the first substrate 310a stacked on the jig 200.

The stacking second substrate 310b operation (S247) stacks the second substrate 310b on the jig 200. In other words, the operation of stacking the second substrate 310b (S247) stacks the second substrate 310b on the jig 200 by performing the setting such that the guide pins 220 of the jig 200 pass through the first guide holes 317b of the second substrate 310b, respectively, and then move downward.

At this time, the operation of stacking the second substrate 310b (S247) stacks the second substrate 310b on the adhesive sheet 320 stacked on the jig 200. The operation of stacking the second substrate 310b (S247) stacks the second substrate 310b such that the one surface on which the thin film pattern 316b has been formed is disposed on the adhesive sheet 320.

The operation (S249) of removing the guide film 312b of the second substrate 310b removes the guide film 312b from the second substrate 310b stacked on the jig 200. In other words, the operation of removing the guide film 312b of the second substrate 310b (S249) removes the guide film 312b and the adhesive film 313b of the second substrate 310b disposed on the top.

Here, in the case where the surface modification layer 318 has been formed on the lower surface of the substrate 310 and the guide film has been removed, operations S243 and S249 may be omitted.

As described above, the method for manufacturing a flexible printed circuit board may stack a plurality of substrates 310 and adhesive sheets 320 by performing the following arrangement in the stacking operation (S240) such that the guide pins 220 formed on the jig 200 pass through the guide holes (in other words, the first guide holes 317 and the second guide holes 322) formed in the substrates 310 and the adhesive sheets 320 and then move downward, so that the alignment process of the stacked substrates (in other words, the substrates 310 and the adhesive sheets 320) is not performed during the stacking process, thereby simplifying the manufacturing process.

Further, the method for manufacturing a flexible printed circuit board may stack a plurality of substrates 310 and adhesive sheets 320 by performing a setting such that the guide pins 220 formed on the jig 200 pass through the guide holes (in other words, the first guide holes 317 and the second guide holes 322) formed in the substrates 310 and the adhesive sheets 320 and then move downward to align the thin film patterns 316 formed on the stacked substrates 310 in an accurate position in the stacking operation (S240), thereby preventing the manufacturing yield and reliability of the flexible printed circuit board from being lowered.

The bonding operation (S250) constitutes a stacked body by bonding a plurality of substrates 310 and adhesive sheets 320 stacked on the jig 200.

For example, the bonding operation (S250) constitutes a stacked body by compressing and preliminarily bonding the plurality of substrates 310 and the adhesive sheets 320, and then primarily bonding the plurality of substrates 310 and the adhesive sheets 320.

Here, the preliminary bonding compresses the plurality of substrates 310 and the adhesive sheets 320 stacked on the jig 200 by, for example, a Water Injection Molding (WIM) process, i.e., compression by applying high water pressure.

For example, the main bonding bonds the preliminarily bonded plurality of substrates 310 and the adhesive sheet 320 by a hot press process applying predetermined pressure and heat. At this time, the main bonding (in other words, the hot press process) bonds the plurality of substrates 310 and the adhesive sheet 320 by applying a pressure lower than that of the preliminary bonding (in other words, the water injection molding process).

The bonding operation (S250) constitutes a stacked body by completing the bonding of the plurality of substrates 310 and the bonding sheets 320, and separates the stacked body from the jig 200.

The forming vias operation (S260) forms one or more vias 330 through the stack. In other words, the forming of the through-hole (S260) operation forms the through-hole 330 in the stacked body separated from the jig 200 through a punching process, a laser drilling process, or the like.

Here, although it is illustrated in fig. 8 and 9 that the through-hole 330 is formed after the plurality of substrates 310 and the adhesive sheets 320 are stacked and adhered to each other, it is not limited thereto, and the respective substrates 310 and the adhesive sheets 320 may be stacked and adhered to each other after the through-hole 330 is formed.

The forming connection pattern operation (S270) forms connection patterns 340 in the through holes 330 to electrically connect (in other words, electrically conduct) the thin film patterns 316 formed on the plurality of substrates 310, respectively. At this time, the operation of forming a connection pattern (S270) forms a connection pattern 340 by filling a conductive material in the via hole 330. Here, the operation of forming the connection pattern (S270) may also form the connection pattern 340 by plating a conductive material on the inner wall surface of the through-hole 330 and on the thin film pattern 316 exposed to the outside of the stack.

Meanwhile, the method for manufacturing a flexible printed circuit board may further include forming a protective layer on an upper surface of a stacked body configured by stacking a plurality of substrates 310 and an adhesive sheet 320.

The protective layer forming operation forms a protective layer covering the thin film pattern 316 and the surface of the substrate 310 by applying and curing a coating liquid on the thin film pattern 316 and the surface of the base material stacked on the uppermost portion of the stack. At this time, the protective layer may be made of a composite material containing resin such as polypropylene and polyimide.

In addition, the method for manufacturing a flexible printed circuit board may further include forming the electrode part. At this time, the forming of the electrode portion may be performed by removing a portion of the protective layer and then plating a conductive material such as copper on the corresponding region to form the electrode portion. Here, the electrode portion may be formed on at least one of the plurality of thin film patterns 316 disposed on the upper surface of the stack body.

Referring to fig. 18 and 19, a flexible printed circuit board according to a second embodiment of the present disclosure may be configured to include: a stacked body in which a plurality of substrates 310 and adhesive sheets 320 are alternately stacked and adhered to each other; and a circuit pattern formed inside the stacked body and on the upper surface. Here, although a flexible printed circuit board in which two substrates 310 and one adhesive sheet 320 are stacked is shown in fig. 18 and 19 for convenience of description, three or more substrates 310 and two or more adhesive sheets 320 may be stacked in a flexible printed circuit board, and various configurations may be made according to a desired thickness.

The stacked body is constructed by alternately stacking a plurality of substrates 310 and adhesive sheets 320. In other words, the stack is constructed by: a plurality of substrates 310 are repeatedly stacked, and an adhesive sheet 320 is interposed between the substrates 310 to adhere the substrates 310.

At this time, the substrate 310 has the surface modification layer 318 disposed on at least one of the two surfaces (in other words, the upper and lower surfaces) thereof to solve the problem of poor adhesion of the polytetrafluoroethylene film 311.

In other words, as shown in fig. 18, the surface modification layer 318 is formed on one surface (i.e., the upper surface) of the two surfaces of the substrate 310 on which the thin film pattern 316 has been formed. At this time, the surface modification layer 318 is formed on the upper surface and the periphery of the thin film patterns 316 and the upper surface of the polytetrafluoroethylene film 311 exposed to the space between the thin film patterns 316.

Meanwhile, as shown in fig. 19, the surface modification layer 318 may also be formed on both surfaces (in other words, an upper surface and a lower surface) of the substrate 310. In other words, the surface modification layer 318 may also be formed on: the upper surface and the periphery of the thin film patterns 316, a portion of the upper surface of the teflon film 311 exposed to the space between the thin film patterns 316, and the entire lower surface of the teflon film 311.

On the other hand, the stack may also be constructed by: the polytetrafluoroethylene film 311 having only the surface modification layer 318 formed on the upper surface thereof, the polytetrafluoroethylene film 311 having only the surface modification layer 318 formed on the lower surface thereof, and the polytetrafluoroethylene film 311 having the surface modification layers 318 formed on both surfaces thereof may be used interchangeably.

For example, as shown in fig. 20, among the plurality of substrate sheets 310 constituting the stacked body, the uppermost substrate sheet 310 stacked may be formed with the surface modification layer 318 only on the lower surface thereof, and the lowermost substrate sheet 310 stacked may be formed with the surface modification layer 318 only on the upper surface thereof. At this time, the other substrate 310 interposed between the uppermost and lowermost substrates 310 is formed with the surface modification layers 318 on both surfaces (in other words, upper and lower surfaces) of the substrate.

The circuit pattern is composed of a thin film pattern 316 exposed to the upper surface of the stack, a thin film pattern 316 interposed in the stack, and a connection pattern 340 electrically connecting the thin film patterns.

In other words, when the substrates 310 are stacked together, among the circuit patterns, the thin film pattern 316 formed on the substrate 310 stacked on the uppermost portion of the stack is exposed to the upper surface of the stack, and the thin film patterns 316 formed on the other substrates 310 are inserted into the stack. At this time, the thin film pattern 316 is electrically connected (in other words, electrically conducted) through the connection pattern 340 formed in the via hole 330.

Referring to fig. 21 and 22, a flexible printed circuit board according to a second embodiment of the present disclosure is configured to include: a stacked body in which a plurality of substrates 310 and adhesive sheets 320 are alternately stacked and then adhered to each other; and a circuit pattern formed in the stacked body and on an upper surface thereof. Here, although the flexible printed circuit board on which two substrates 310 and one adhesive sheet 320 are stacked is shown in fig. 21 and 22 for convenience of description, three or more substrates 310 and two or more adhesive sheets 320 may be stacked on the flexible printed circuit board, and various configurations may be made according to a desired thickness.

The stacked body is constructed by alternately stacking a plurality of substrates 310 and adhesive sheets 320. In other words, the stack is constructed by: a plurality of substrates 310 are repeatedly stacked, and an adhesive sheet 320 is interposed between the substrates 310 to adhere the substrates 310.

At this time, the substrate 310 has the surface modification layer 318 disposed on at least one of the two surfaces (in other words, the upper and lower surfaces) thereof to solve the problem of poor adhesion of the polytetrafluoroethylene film 311.

In other words, as shown in fig. 21, the surface modification layer 318 is formed on one (i.e., the upper surface) of the two surfaces of the substrate 310 on which the thin film pattern 316 has been formed. At this time, the surface modification layer 318 is formed on the upper surface of the polytetrafluoroethylene film 311 in a predetermined thickness, and the thin film pattern 316 is formed on the upper surface of the surface modification layer 318.

Meanwhile, as shown in fig. 22, the surface modification layer 318 may also be formed on both surfaces (in other words, upper and lower surfaces) of the substrate 310.

On the other hand, the stack may also be constructed by: the polytetrafluoroethylene film 311 having only the surface modification layer 318 formed on the upper surface thereof, the polytetrafluoroethylene film 311 having only the surface modification layer 318 formed on the lower surface thereof, and the polytetrafluoroethylene film 311 having the surface modification layers 318 formed on both surfaces thereof may be used interchangeably.

For example, as shown in fig. 23, among a plurality of substrate sheets 310 constituting the stacked body, the uppermost substrate sheet 310 may be formed with the surface modification layer 318 only on the lower surface thereof, and the lowermost substrate sheet 310 may be formed with the surface modification layer 318 only on the upper surface thereof. At this time, the other substrate 310 interposed between the uppermost and lowermost substrates 310 is formed with the surface modification layers 318 on both surfaces (in other words, upper and lower surfaces) of the substrate.

The circuit pattern is composed of a thin film pattern 316 exposed to the upper surface of the stack, a thin film pattern 316 interposed in the stack, and a connection pattern 340 electrically connecting the thin film patterns.

In other words, when the substrates 310 are stacked together, among the circuit patterns, the thin film pattern 316 formed on the substrate 310 stacked on the uppermost portion of the stack is exposed to the upper surface of the stack, and the thin film patterns 316 formed on the other substrates 310 are inserted into the stack. At this time, the thin film pattern 316 is electrically connected (in other words, electrically conducted) through the connection pattern 340 formed in the via hole 330.

Here, although it is illustrated in fig. 18 to 23 that the adhesive sheet 320 is configured as a single layer, it is not limited thereto, and the adhesive sheet 320 may also be configured as a multi-layer structure.

Further, although it is illustrated in fig. 18 to 23 that the connection pattern 340 is formed by filling the through-hole 330, it is not limited thereto, and the connection pattern 340 may be formed by plating on the inner wall surface of the through-hole 330.

Referring to fig. 24 and 25, a method for manufacturing a flexible printed circuit board according to a third embodiment of the present disclosure includes the operations of: preparing a substrate (S310), stacking (S330), bonding (S350), forming a via hole (S370), and forming a connection pattern (S390).

The preparation substrate operation (S310) prepares a substrate 410, sequentially stacks a guide film 412, a teflon film 411, and a thin film pattern 416, and a guide hole 418 passing through the guide film 412 and the teflon film 411 is formed in the substrate 410. At this time, the guide hole 418 is a hole into which the guide pin 220 of the jig 200 is inserted so as to easily perform a stacking operation (S330) to be described later.

The preparation substrate operation (S310) forms an adhesive layer 417 on the teflon film 411 to improve the adhesiveness of the teflon film 411. The preparation substrate operation (S310) forms an adhesive layer 417 only on the surface, which is adhered to the other substrate 410, of the upper surface and the lower surface of the teflon film 411. At this time, the preparation substrate operation (S310) forms adhesive layers 417 on the upper and lower surfaces of the teflon film 411. Here, for example, the adhesive layer 417 is a polytetrafluoroethylene material.

Referring to fig. 26 and 27, the operation of preparing a substrate (S310) includes the operations of: bonding the polytetrafluoroethylene film and the guide film (S311), forming a seed layer (S312), forming a plating layer (S313), forming a thin film pattern (S314), forming an adhesive layer (S315), and forming a guide hole (S316).

The adhering polytetrafluoroethylene film and guiding film operation (S311) prepares the polytetrafluoroethylene film 411 having heat resistance and low dielectric constant.

Generally, after the flexible printed circuit board is manufactured, the circuit board is mounted with the semiconductor element by a surface mount technology process (in other words, an SMT process).

At this time, since the conventional flexible printed circuit board uses polypropylene (PP) having heat resistance of about 160 to 180 ℃ to constitute the substrate 410, the substrate 410 is deformed or broken by heat (about 250 ℃) applied in a reflow process of a surface mounting technology process, thereby reducing reliability of the flexible printed circuit board.

The method for manufacturing a flexible printed circuit board according to the embodiment of the present disclosure uses the polytetrafluoroethylene film 411 to constitute the substrate 410 to prevent the reliability of the flexible printed circuit board from being lowered.

In other words, since the polytetrafluoroethylene film 411 is not deformed even by heat of about 300 ℃, deformation and breakage of the substrate due to heat applied in the reflow process can be prevented.

Accordingly, the adhering polytetrafluoroethylene film and guiding film operation (S311) uses the polytetrafluoroethylene film 411 to construct the substrate 410.

Therefore, the method for manufacturing the flexible printed circuit board and the flexible printed circuit board manufactured by the method can prevent deformation and breakage of the flexible printed circuit board due to heat applied in a reflow process, thereby improving reliability.

Polytetrafluoroethylene is mainly used as a lubricant, a release material, and an insulating material. Since polytetrafluoroethylene has optimum heat resistance and dielectric properties (in other words, low dielectric constant) among polymer materials, it is used as a base material for high-frequency printed circuit boards that require low dielectric constant and heat resistance.

However, since polytetrafluoroethylene is soft-fusible and thermoplastic, heat and pressure applied during the manufacturing process deform the base material, resulting in a high defective rate. Therefore, polytetrafluoroethylene is mainly used as a thick and hard single-sided or double-sided substrate.

In one embodiment of the present disclosure, a thin-film teflon film is used as the substrate 410 to manufacture a flexible printed circuit board. Due to the reflow property of ptfe, the ptfe film 111 is deformed or broken even if the pressure applied during the manufacturing process is small, thereby reducing the manufacturing yield and reliability of the flexible printed circuit board.

Accordingly, the adhering of the polytetrafluoroethylene film and the guide film operation (S311) adheres the guide film 412 to one surface of the polytetrafluoroethylene film 411 to prevent the polytetrafluoroethylene film 411 from being deformed and broken during the manufacturing process. At this time, the guide film 412 is, for example, a hard polyethylene terephthalate (PET) film.

The polytetrafluoroethylene film and guide film bonding operation (S311) bonds the polytetrafluoroethylene film 411 and the guide film 412 by inserting an adhesive sheet 413 between the polytetrafluoroethylene film 411 and the guide film 412. In other words, since the guide film 412 should be removed in the stacking operation (S330) described later, the adhering polytetrafluoroethylene film and guide film operation (S311) couples the polytetrafluoroethylene film 411 and the guide film 412 in an adhered state (in other words, the adhesive sheet 413), so that it is possible to easily remove the guide film 112 while supporting the polytetrafluoroethylene film 411. Here, the adhesive sheet 413 is, for example, a silicone (Si) -based adhesive.

As described above, the method for manufacturing a flexible printed circuit board according to the embodiment of the present disclosure may form the substrate 410 by adhering the guide film 412 to the polytetrafluoroethylene film 411 to prevent the polytetrafluoroethylene film 411 from being deformed or broken during the manufacturing process, thereby preventing the manufacturing yield and reliability of the flexible printed circuit board from being lowered.

The seed layer formation operation (S312) forms a seed layer 414 of a thin film on one surface of the polytetrafluoroethylene film 411. The seed layer forming operation (S312) forms a seed layer 414 on the other surface of the teflon film 411 (in other words, the surface opposite to the one surface to which the guide film 412 has been adhered) through a deposition process or a sputtering process.

Here, the seed layer forming operation (S312) forms a seed layer 414 of a mixed material of mixed nickel copper (NiCu) and copper (Cu) or nickel copper (NiCu) material on the other surface of the teflon film 411.

The plating layer forming operation (S313) forms a plating layer 415 on the seed layer 414. At this time, the plating layer forming operation (S313) forms a plating layer 415 on the seed layer 414 by electroplating copper (Cu).

Here, the seed layer 414 and the plating layer 415 are elements constituting a circuit pattern, and are formed to a thickness of about 5 μm.

The thin film pattern forming operation (S314) forms a thin film pattern 416 on the other surface of the teflon film 411. In other words, the thin film pattern forming operation (S314) forms a thin film pattern 416 of a predetermined shape by removing a part of the seed layer 414 and the plating layer 415 formed on the other surface of the teflon film 411 through an etching process.

The forming of the adhesive layer operation (S315) forms an adhesive layer 417 on one surface of the polytetrafluoroethylene. In other words, the forming of the adhesive layer operation (S315) forms the adhesive layer 417 on one of the two surfaces (in other words, the upper surface and the lower surface) of the polytetrafluoroethylene film 411 on which the thin pattern 416 is formed. At this time, the adhesive layer 417 is formed on the upper surface and the periphery of the thin film pattern 416 and the upper surface of the polytetrafluoroethylene film 411 exposed to the space between the thin film patterns 416.

Here, although it has been shown in fig. 27 that the surface of the adhesive layer 417 is flat, the adhesive layer 417 may be actually formed such that a portion formed above the thin film pattern 416 is higher than other portions, thereby forming the unevenness.

The adhesive layer forming operation (S315) forms an adhesive layer 417 on one surface of the polytetrafluoroethylene film 411 through a dip coating process. In other words, the adhesive layer forming operation (S315) inserts the polytetrafluoroethylene film 411 into a solvent (e.g., water) in which polytetrafluoroethylene slurry (particles) has been in a dispersed state, and then pressurizes it at a high temperature. Thus, the polytetrafluoroethylene slurry is dip-coated on the surface of the polytetrafluoroethylene film 411 to form an adhesive layer 417.

The forming of the adhesive layer operation (S315) may also form an adhesive layer 417 on one surface of the teflon film 411 through a printing process. In other words, the forming of the adhesive layer operation (S315) forms the adhesive layer 417 by printing (e.g., gravure printing, spray coating) the polytetrafluoroethylene slurry on one surface of the polytetrafluoroethylene film 411.

The forming of the guide holes operation (S316) forms a plurality of guide holes 418 passing through the adhesive layer 417, the teflon film 411, and the guide film 412. In other words, the guide hole forming operation (S316) forms a plurality of guide holes 418 to align the substrate 410 in an accurate position while firmly fixing the substrate 410 to the jig 200 in the stacking operation (S330) to be described later. Here, the forming of the guide holes (S316) forms the guide holes 418 on the substrate 410 through a punching process, a laser drilling process, or the like.

Meanwhile, the preparation substrate operation (S310) may also form an adhesive layer 417 (in other words, a first adhesive layer 417a and a second adhesive layer 417b) on both surfaces of the polytetrafluoroethylene film 411.

For this, referring to fig. 28 and 29, the forming of the adhesive layer (S315) may include the following operations: forming a first adhesive layer (S317), removing the guide film (S318), and forming a second adhesive layer (S319).

The adhering polytetrafluoroethylene film and guiding film operation (S311) adheres the guiding film 412 to one surface of the polytetrafluoroethylene film 411 having heat resistance and low dielectric constant. At this time, for example, the guide film 412 is a hard polyethylene terephthalate (PET) film.

The polytetrafluoroethylene film and guide film bonding operation (S311) bonds the polytetrafluoroethylene film 411 and the guide film 412 by inserting an adhesive sheet 413 between the polytetrafluoroethylene film 411 and the guide film 412.

At this time, in order to easily remove the guide film 412 in the stacking operation (S330) which will be described later, the operation (S311) of bonding the polytetrafluoroethylene film and the guide film couples the polytetrafluoroethylene film 411 and the guide film 412 in a stuck state (in other words, the adhesive sheet 413) capable of easily removing the guide film 412 while supporting the polytetrafluoroethylene film 411. Here, the adhesive sheet 413 is, for example, a silicone (Si) -based adhesive.

The first adhesive layer forming operation (S317) forms a first adhesive layer 417a on one surface of the polytetrafluoroethylene film 411. In other words, the forming of the first adhesive layer operation (S317) forms the first adhesive layer 417a on one of the two surfaces (in other words, the upper and lower surfaces) of the polytetrafluoroethylene film 411 on which the thin film pattern 416 has been formed.

The forming of the first adhesive layer operation (S317) forms a first adhesive layer 417a of a polytetrafluoroethylene material on one surface of the polytetrafluoroethylene film 411 through a dip coating process or a printing process (e.g., gravure printing, jet printing, etc.).

The guide film removing operation (S318) removes the guide film 412 adhered on the other surface of the polytetrafluoroethylene film 411. In other words, the removal guide film operation (S318) is a previous operation for forming the second adhesive layer 417b on the other surface of the polytetrafluoroethylene film 411, which removes the guide film 412 and the adhesive film 413 adhered on the other surface of the polytetrafluoroethylene film 411.

The second adhesive layer forming operation (S319) forms a second adhesive layer 417b on the other surface of the teflon film 411. In other words, the operation of forming the second adhesive layer (S319) forms the second adhesive layer 417b of the teflon material on the other surface of the teflon film 411 (in other words, the lower surface of the guide film 412 has been removed) through a dip coating process or a printing process.

As described above, the method for manufacturing a flexible printed circuit board may form the adhesive layer 417 of a polytetrafluoroethylene material on the surface of the polytetrafluoroethylene film 411 to improve the adhesiveness of the surface of the polytetrafluoroethylene film 411, thereby manufacturing a multi-layer flexible printed circuit board using the polytetrafluoroethylene film 411 having poor adhesiveness.

The guide hole forming operation (S316) forms a plurality of guide holes 418 passing through the first adhesive layer 417a, the teflon film 411, and the second adhesive layer 417 b. In other words, the guide hole forming operation (S316) forms a plurality of guide holes 418 to align the substrate 410 in an accurate position while firmly fixing the substrate 410 to the jig 200 in the stacking operation (S330) to be described later. Here, the forming of the guide holes (S316) forms the guide holes 418 on the substrate 410 through a punching process, a laser drilling process, or the like.

Referring to fig. 30 and 31, after the preparation substrate operation (S310) forms an adhesive layer 417 on at least one of both surfaces of the teflon film 411, a thin film pattern 416 is formed.

For this, the operation of preparing the substrate (S310) includes the operations of: forming an adhesive layer (S321), adhering the teflon film 411 and the guide film 412(S322), forming a seed layer (S323), forming a plating layer (S324), forming a thin film pattern (S325), and forming a guide hole (S326).

The adhesive layer forming operation (S321) forms an adhesive layer 417 on the surface of the teflon film 411 through a dip coating process or a printing process. At this time, for example, the forming of the adhesive layer operation (S321) forms an adhesive layer 417 of a polytetrafluoroethylene material on the surface of the polytetrafluoroethylene film 411.

The forming of the adhesive layer operation (S321) may form the adhesive layer 417 only on one of the two surfaces of the polytetrafluoroethylene film 411, on which the thin film pattern 416 is to be formed, or form the adhesive layer 417 only on the other of the two surfaces of the polytetrafluoroethylene film 411, on which the guide film 412 is to be adhered.

Here, although it is shown in fig. 31 that the adhesive layer 417 is formed only on one surface (in other words, the lower surface) of the polytetrafluoroethylene film 411, it is not limited thereto, and the adhesive layer 417 may be formed on both surfaces (in other words, the upper surface and the lower surface) of the polytetrafluoroethylene film 411.

As described above, the method for manufacturing a flexible printed circuit board may form the adhesive layer 417 of a polytetrafluoroethylene material on the surface of the polytetrafluoroethylene film 411 to improve the adhesiveness of the surface of the polytetrafluoroethylene film 411, thereby manufacturing a multi-layer flexible printed circuit board using the polytetrafluoroethylene film 411 having poor adhesiveness.

The adhering of the teflon film 411 and the guide film 412 operation (S322) adheres the guide film 412 to one surface of the teflon film 411 to prevent the teflon film 411 from being deformed or broken during the manufacturing of the flexible printed circuit board. At this time, for example, the guide film 412 is a hard polyethylene terephthalate (PET) film.

The operation (S322) of adhering the teflon film 411 and the guide film 412 adheres the teflon film 411 and the guide film 412 by inserting an adhesive sheet 413 between the adhesive layer 417 and the guide film 412, the guide film 412 being formed on one surface (in other words, the lower surface) of the teflon film 411. In other words, since the guide film 412 should be removed in the stacking operation (S330) described later, the adhering of the teflon film 411 and the guide film 412(S322) to enable easy removal of the adhered state of the guide film 412 (in other words, the adhesive sheet 413) while supporting the teflon film 411 couples the teflon film 411 and the guide film 412. Here, the adhesive sheet 413 is, for example, a silicone (Si) -based adhesive.

As described above, the method for manufacturing a flexible printed circuit board according to the embodiment of the present disclosure may form the substrate 410 by adhering the guide film 412 to the polytetrafluoroethylene film 411 to prevent the polytetrafluoroethylene film 411 from being deformed or broken during the manufacturing process, thereby preventing the manufacturing yield and reliability of the flexible printed circuit board from being lowered.

The seed layer formation operation (S323) forms a seed layer 414 of a thin film on one surface of the polytetrafluoroethylene film 411. The seed layer forming operation (S323) forms a seed layer 414 on an upper surface of an adhesive layer 417 by a deposition process or a sputtering process, the adhesive layer 417 being formed on the other surface (in other words, the upper surface) of the teflon 411. Here, the seed layer forming operation (S323) forms a seed layer 414 of a mixed material of mixed nickel copper (NiCu) and copper (Cu) or a nickel copper (NiCu) material on the other surface of the polytetrafluoroethylene film 411.

The plating layer forming operation (S324) forms a plating layer 415 on the seed layer 414. At this time, the forming plating operation (S324) forms a plating layer 415 on the seed layer 414 by electroplating copper (Cu).

Here, the seed layer 414 and the plating layer 415 are elements constituting a circuit pattern, and are formed to a thickness of about 5 μm.

The thin film pattern forming operation (S325) forms a thin film pattern 416 on the other surface of the teflon film 411. In other words, the thin film pattern forming operation (S325) forms a thin film pattern 416 of a predetermined shape by removing a portion of the seed layer 414 and the plating layer 415 formed on the other surface of the teflon film 411 through an etching process.

The forming of the guide holes operation (S326) forms a plurality of guide holes 418 passing through the adhesive layer 417, the teflon film 411, and the guide film 412. In other words, the guide hole forming operation (S326) forms a plurality of guide holes 418 to align the substrate 410 in an accurate position while firmly fixing the substrate 410 to the jig 200 in the stacking operation (S330) to be described later. Here, the forming of the guide holes (S326) forms the guide holes 418 on the substrate 410 through a punching process, a laser drilling process, or the like.

The stacking operation (S330) stacks a plurality of substrates 410. The stacking operation (S330) stacks a plurality of substrates 410 by using the jig 200.

At this time, the stacking operation (S330) may provide reliability of the flexible printed circuit board only when the thin film patterns 416 of the substrate 410 are stacked to be aligned at an accurate position.

Accordingly, the stacking operation (S330) stacks a plurality of substrates 410 and adhesive sheets by using the jig 200 including the guide pins 220.

An example of the stacking operation (S330) of stacking two substrates 410, in other words, a first substrate 410a and a second substrate 410b, will be described below with reference to fig. 32 and 33.

The stacking operation (S330) may include the following operations: the first substrate 410a is stacked (S331), the guide film 412a of the first substrate 410a is removed (S333), the second substrate 410b is stacked (S335), and the guide film 412b of the second substrate 410b is removed (S337).

The stacking of the first substrate 410a (S310) stacks the first substrate 410a on the jig 200. In other words, the operation of stacking the first substrate 410a (S310) stacks the first substrate 410a on the jig 200 by performing the following arrangement such that the guide pins 220 of the jig 200 pass through the guide holes 418a of the first substrate 410a, respectively, and then move downward.

At this time, the stacking of the first substrate 410a (S310) stacks the first substrate 410a such that the thin film pattern 416a formed on the first substrate 410a is placed downward, so that the guide film 412a is easily removed. In other words, the stacking of the first substrate 410a (S310) arranges the guide film 412a on top by stacking the first substrate 410a such that the thin film pattern 416a is placed downward.

The operation (S333) of removing the guide film 412a of the first substrate 410a removes the guide film 412a from the first substrate 410a stacked on the jig 200. In other words, the operation (S333) of removing the guide film 412a of the first substrate 410a removes the guide film 412a and the adhesive film 413a of the first substrate 410a, which are disposed on top.

The stacking of the second substrate 410b (S335) stacks the second substrate 410b on the jig 200. In other words, the operation of stacking the second substrate 410b (S335) stacks the second substrate 410b on the jig 200 by performing the following arrangement such that the guide pins 220 of the jig 200 pass through the guide holes 418b of the second substrate 410b, respectively, and then move downward.

At this time, the stacking of the second substrate 410b (S335) stacks the second substrate 410b on the first substrate 410a stacked on the jig 200. The operation of stacking the second substrate 410b (S335) stacks the second substrate 410b such that one surface on which the thin film pattern 416b has been formed is disposed on the adhesive sheet.

The operation (S337) of removing the guide film 412b of the second substrate 410b removes the guide film 412b from the second substrate 410b stacked on the jig 200. In other words, the operation (S337) of removing the guide film 412b of the second substrate 410b removes the guide film 412b and the adhesive film 413b of the second substrate 410b, which are disposed on top.

Here, in the case of a state where the adhesive layer 417 has been formed on the lower surface of the substrate 410 and the guide film 412 has been removed, operations S230 and S270 may be omitted.

As described above, the method for manufacturing a flexible printed circuit board may stack a plurality of substrates 410 by performing the arrangement such that the guide pins 220 formed on the jig 200 pass through the guide holes 418 formed in the substrates 410 and then move them downward in the stacking operation (S330), without performing the alignment process of the adhesive sheets during the stacking process, thereby simplifying the manufacturing process.

Further, the method for manufacturing a flexible printed circuit board may stack a plurality of substrates 410 by performing a setting such that the guide pins 220 formed on the jig 200 pass through the guide holes 418 formed in the substrates 410 and then move them downward in the stacking operation (S330) to align the thin film patterns 416 formed on the stacked substrates 410 in an accurate position, thereby preventing the manufacturing yield and reliability of the flexible printed circuit board from being lowered.

The bonding operation (S350) constitutes a stacked body by bonding the plurality of substrates 410 and the adhesive sheets stacked on the jig 200. At this time, for example, the bonding operation (S350) bonds the plurality of substrates 410 included in the stacked body through a hot press process in which a predetermined pressure and heat are simultaneously applied. Here, since the adhesive layer 417 is made of a polytetrafluoroethylene material, the bonding operation (S350) heats the stacked body at a temperature of about 300 ℃ or more.

When the plurality of substrates 410 are completely bonded to constitute the stack, the bonding operation (S350) separates the stack from the jig 200.

The forming via operation (S370) forms one or more vias 420 through the stack. In other words, the forming of the through-hole (S370) forms the through-hole 420 in the stacked body separated from the jig 200 through a punching process, a laser drilling process, or the like.

Here, although it is illustrated in fig. 24 and 25 that the through-hole 420 is formed after the plurality of substrates 410 and adhesive sheets are stacked and adhered to each other, it is not limited thereto, and the substrates 410 and the adhesive sheets may be stacked and adhered to each other after the through-hole 420 is formed.

The forming connection pattern operation (S390) forms connection patterns 430 in the through holes 420 to electrically connect (in other words, electrically conduct) the thin film patterns 416 formed on the plurality of substrates 410, respectively. At this time, the forming of the connection pattern operation (S390) forms the connection pattern 430 by filling the via hole 420 with a conductive material. Here, the operation of forming the connection pattern (S390) may also form the connection pattern 430 by plating a conductive material on the inner wall surface of the through-hole 420 and on the thin film pattern 416 exposed to the outside of the stack.

In addition, the method for manufacturing a flexible printed circuit board may further include forming a protective layer on an upper surface of the stacked body configured by stacking the plurality of substrates 410.

The forming of the protective layer operation forms a protective layer covering the thin film pattern 416 and the surface of the substrate 410 by applying and curing a coating liquid on the thin film pattern 416 and the surface of the substrate 410 stacked at the uppermost portion of the stack. At this time, the protective layer may be made of a composite material containing a resin such as polypropylene and polyimide.

In addition, the method for manufacturing a flexible printed circuit board may further include forming the electrode part. At this time, the forming of the electrode portion may be performed by removing a portion of the protective layer and then plating a conductive material such as copper on the corresponding region to form the electrode portion. Here, the electrode portion may be formed on at least one of the plurality of thin film patterns 416 disposed on the upper surface of the stack body.

Referring to fig. 34, the flexible printed circuit board according to the third embodiment of the present disclosure is configured to include: a stacked body in which a plurality of substrates 410 are stacked and then bonded to each other; and a circuit pattern formed in the stacked body and on the upper surface.

The substrate 410 is composed of a teflon film 411 having a thin film pattern 416, the thin film pattern 416 being formed on one surface of the teflon film 411. At this time, the thin film pattern 416 is composed of a seed layer 414 and a plating layer 415, the seed layer 414 being formed on the surface of the teflon film 411, and the plating layer being formed on the upper surface of the seed layer 414.

The substrate 410 includes an adhesive layer 417 formed on at least one of the upper and lower surfaces of the teflon film 411. At this time, the adhesive layer 417 may be formed only on one surface of the polytetrafluoroethylene film 411 to be adhered to the other substrate 410 or on both surfaces of the polytetrafluoroethylene film 411.

For example, the adhesive layer 417 is a polytetrafluoroethylene material, and is formed on the surface of the polytetrafluoroethylene film 411 by a dip coating or printing (e.g., gravure printing, spray coating, etc.) process.

When a plurality of substrates 410 are stacked, some regions of the stacked body are formed in a structure in which the teflon film 411 and the adhesive layer 417 are alternately stacked, and the remaining regions are formed in a structure in which the teflon film 411, the thin film pattern 416, and the adhesive layer 417 are alternately stacked.

The circuit pattern is composed of a thin film pattern 416 exposed to the upper surface of the stack, the thin film pattern 416 inserted in the stack, and a connection pattern 430 electrically connecting the thin film pattern 416.

In other words, when the substrates 410 are stacked together, among the circuit patterns, the thin film pattern 416 formed on the substrate 410 stacked on the uppermost portion of the stack is exposed to the upper surface of the stack, and the thin film patterns 416 formed on the other substrates 410 are inserted into the stack. At this time, the thin film pattern 416 is electrically connected (in other words, electrically conducted) through the connection pattern 430 formed in the via hole 420.

Here, although it is illustrated in fig. 34 that the connection pattern 430 is formed by filling in the through hole 420, it is not limited thereto, and the connection pattern 140 may be formed by plating on the inner wall surface of the through hole 420.

As described above, although the preferred embodiments according to the present disclosure have been described, they may be modified in various forms, and it should be understood by those skilled in the art that various modified examples and changed examples may be practiced without departing from the claims of the present disclosure.