KR20230041355A - Manufacturing method of flexible printed circuit board - Google Patents

Abstract

The present invention relates to a method for manufacturing a flexible printed circuit board, comprising: a step of performing primary plating on the master mold; a step of attaching a dry film to the master mold on which the plating was performed; a step of removing the remaining portion of the attached dry film except for the portion corresponding to the circuit pattern; a step of removing the first plating portion from the portion from which the dry film was removed; a step of removing residual dry film from the master mold; performing printing using ink to cover the master mold with an ink composition; a step of polishing the ink composition to expose the primary plated portion; removing the remaining primary plating portion from the master mold; and a step of forming the circuit pattern by plating a conductive material on the master mold. Accordingly, the present invention can reduce the manufacturing cost of a flexible printed circuit board.

Description

Flexible printed circuit board manufacturing method {MANUFACTURING METHOD OF FLEXIBLE PRINTED CIRCUIT BOARD}

The present invention relates to a method for manufacturing a flexible printed circuit board, and more particularly, to a method for manufacturing a flexible printed circuit board for forming a circuit pattern of the flexible printed circuit board using plating.

Flexible Printed Circuit Board (FPCB) is a board that can be flexibly bent by forming a circuit pattern on a thin insulating film. It is widely used in mobile devices and display devices.

Such a flexible printed circuit board is generally manufactured using a flexible copper clad laminate (FCCL) in which a copper clad layer is laminated on a polyimide film layer as a substrate (raw material), and is laminated to the copper clad laminated film, exposed, developed, A method of forming a circuit pattern by performing an operation such as etching is mainly used.

Meanwhile, the background art of the present invention is disclosed in Korean Patent Publication No. 10-2013-0104507 (2013.09.25).

In the case of a conventional flexible printed circuit board manufacturing method using FCCL, a method of forming a circuit pattern by removing copper corresponding to the circuit pattern from planar copper through an etching process was used. At this time, since the copper itself is etched, there is a problem that the shape may be uneven when the circuit is formed. In particular, when copper is etched inward, the gap between the gaps at the end of the etching is uneven and gradually decreases. There is a problem that may occur.

Therefore, in order to manufacture a product with a more precise shape, it is necessary to precisely control the shape of the circuit pattern itself or the surrounding structure for forming the circuit pattern in forming the circuit pattern.

Accordingly, an object of the present invention is to provide a method for manufacturing a flexible printed circuit board that enables relatively precise shape control compared to conventional methods and facilitates repeated manufacturing of circuit patterns using a master mold.

A method for manufacturing a flexible printed circuit board according to the present invention includes performing primary plating on a master mold; attaching a dry film to the master mold on which the plating is performed; removing portions other than the portion corresponding to the circuit pattern from the attached dry film; removing the first plated portion from the dry film-removed portion; removing residual dry film from the master mold; Covering the master mold with an ink composition by performing printing using ink; exposing the primarily plated portion by polishing the ink composition; removing the remaining primary plating portion from the master mold; and forming the circuit pattern by plating a conductive material on the master mold.

After the step of forming the circuit pattern, the present invention includes the steps of attaching an insulating film to the formed circuit pattern; and separating the flexible printed circuit board on which the insulating film and the circuit pattern are laminated from the master mold.

The step of removing the primary plated portion from the dry film-removed portion of the present invention may include removing a portion of the master mold in addition to the primary plated portion through an etching process.

In the present invention, the conductive material is copper, and the insulating film is characterized in that a polyimide film.

In the flexible printed circuit board manufacturing method according to the present invention, a circuit pattern is formed by performing primary plating on a master mold and processing the primary plated portion into a shape according to the circuit pattern to be formed, but the shape of the cross section is uniformly formed. By doing so, there is an effect of enabling high circuit precision to be achieved more easily than in the conventional method.

The method for manufacturing a flexible printed circuit board according to the present invention has an effect of reducing the manufacturing cost of a flexible printed circuit board because a product can be produced by reusing a master mold having a wall structure formed thereon.

1 is a flowchart illustrating a method of manufacturing a flexible printed circuit board according to an embodiment of the present invention.
2 to 12 are exemplary diagrams for explaining a method of manufacturing a flexible printed circuit board according to an embodiment of the present invention.

Hereinafter, embodiments of a method for manufacturing a flexible printed circuit board according to the present invention will be described with reference to the accompanying drawings. In this process, the thickness of lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of a user or operator. Therefore, definitions of these terms will have to be made based on the content throughout this specification.

1 is a flowchart for explaining a method for manufacturing a flexible printed circuit board according to an embodiment of the present invention, and FIGS. 2 to 12 are exemplary diagrams for explaining a method for manufacturing a flexible printed circuit board according to an embodiment of the present invention. As such, a method for manufacturing a flexible printed circuit board according to an embodiment of the present invention will be described with reference to this.

In FIGS. 2 to 12, only the cross section of the board is shown to explain the manufacturing process of the flexible printed circuit board, and the implementation and configuration of typical circuit patterns, such as circuit patterns connected in a circle, are widely used in the technical field of the present invention. Since it corresponds to known content, a detailed description thereof will be omitted.

As shown in FIG. 1 , in the method for manufacturing a flexible printed circuit board according to an embodiment of the present invention, first plating 2 is performed on a master mold 1 (S10). That is, as shown in FIG. 2, primary plating (2) is performed on the master mold (1), and this primary plating (2) is performed to form a wall structure in the future. In the primary plating 2, various types of materials may be selected as necessary, but materials that are relatively easy to chemically treat in an etching process described later may be employed.

Meanwhile, in the case of the master mold 1, it may be composed of SUS (SUS, stainless steel), etc., but may be composed of various materials that can perform smooth plating in addition to it.

Subsequently, a dry film (3) is attached to the master mold (1) on which plating has been performed (S20), and the rest of the attached dry film (3) except for the portion corresponding to the circuit pattern (6) is removed. Do (S30). That is, as shown in FIGS. 3 and 4, after the dry film 3 is attached to the master mold 1, a certain portion is removed in relation to the shape of the circuit pattern 6 to be formed later, and only the corresponding portion is used. The primary plating 2 may be exposed.

At this time, the circuit pattern 6 may be input to the control device by a user, and removal of the dry film 3 may be performed by performing exposure and development.

Subsequently, the primary plating 2 is removed from the area where the dry film 3 is removed (S40). At this time, the first plating (2) may be removed through an etching process. On the other hand, as shown in FIG. 5, not only the first plating 2 by this etching operation, but also a certain portion of the master mold 1 is further removed to form an intaglio portion in a partial region of the master mold 1. can be made

Precise control of the shape of the wall structure for the formation of a circuit pattern to be described later, in particular, in order to derive a certain shape in the gap of the wall structure, the side of the remaining part of the first plating (2) (that is, exposed according to the etching process) side) should have a uniform shape. In the present invention, for this purpose, not only the primary plating (2) part, but also a certain portion of the master mold (1) is further removed, and the end portion to be etched corresponds to the master mold (1), not the primary plating (2) portion By doing so, the side surface of the remaining part of the first plating (2) can have an even shape.

Then, the remaining dry film 3 is removed (S50). That is, the remaining dry film 3 is removed as shown in FIG. 6 in the form shown in FIG. 5 . At this time, in the case of the remaining dry film 3, it may be performed by using a method of peeling the dry film 3, etc., and since this corresponds to the contents already known in the technical field of the present invention, a detailed description of the method will be omitted. do.

Subsequently, silk printing is performed (S60). That is, as shown in FIG. 7 , the ink composition 4 may entirely cover the master mold 1 and the primary plating 2 by performing printing using a special ink.

At this time, the ink used for printing may utilize an ink having resistance to plating (eg, high insulation performance). In the case of such printing ink, commercially available products or specially formulated inks may be utilized.

Meanwhile, since a method of performing silk printing in relation to a PCB (PRINTED CIRCUIT BOARD) corresponds to a widely known technology, a detailed description thereof will be omitted.

Thereafter, polishing is performed to expose the first plating (2) portion (S70). That is, as shown in FIG. 8 , the first plating portion 2 may be exposed by polishing the ink composition 4 formed in step S60.

Subsequently, the remaining portion of the first plating (2) is removed (S80). That is, as shown in FIG. 9 , the area 5 where a circuit pattern is to be formed may be prepared by removing the remaining portion of the primary plating 2 to form a wall structure of the ink composition 4 .

At this time, the removal of the remaining primary plating (2) portion may be performed by etching or the like. Since the entire primary plating (2) portion is removed, the master mold (1), the primary plating (2) portion, and the ink Only the first plating (2) portion can be removed by using the difference in physical properties of the composition (4).

The removal of the remaining primary plating (2) portion may be performed using a solution having different chemical characteristics from the removal of the primary plating (2) portion in the above-described step (S40), which is the master mold ( This is to ensure that only the first plating (2) portion is smoothly removed without affecting 1).

After the above step (S80), copper is plated to form the circuit pattern 6 (S90).

For example, a method in which the master mold 1 is put into a tank filled with a solution for plating, and plating is performed by electroplating may be used. At this time, plating is not performed on a portion of the wall structure 4 formed of a special ink having different physical properties from the surface of the master mold 1 .

Alternatively, electroless plating may be performed, but plating may be performed only on the master mold 1 by selecting a catalyst according to the physical properties of the master mold 1 and the wall structure 4 .

In this embodiment, the configuration of the device or the specific plating method for performing the plating process corresponds to a technique already widely known in the art of the present invention, and since various embodiments are available, a detailed description thereof will be omitted.

Through this plating process, a circuit pattern 6 as shown in FIG. 10 may be formed on the master mold 1 .

Meanwhile, although the conductive material is described as being copper in this embodiment, a conductive material of another material may be used to achieve the purpose of electrical connection.

Also, if necessary, nickel (Ni) or nickel+chromium (Ni+Cr) plating may be first performed on the region where the circuit pattern 6 is to be formed. That is, a nickel or nickel+chromium plating layer is formed on the portion where copper is to be plated so that the circuit pattern 6 can be smoothly separated from the master mold 1 in the future.

Subsequently, an insulating film 7 is attached to the circuit pattern 6 formed through this process (S100). At this time, the insulating film 7 may be attached to the circuit pattern 6 by an adhesive method. For example, a method of laminating an adhesive layer on the circuit pattern 6 or applying an adhesive and attaching the insulating film 7, an adhesive layer or A method of attaching an insulating film 7 provided with an adhesive to the circuit pattern 6 may be used, and a thermosetting adhesive or adhesive sheet may be utilized.

Meanwhile, in this embodiment, the insulating film 7 may be a polyimide film, but other types of insulating films may be utilized.

Subsequently, the FPCB is separated from the master mold 1 (S110). As shown in FIG. 11 , the circuit pattern 6 to which the insulating film 7 is attached may be separated from the master mold 1 and processed through a post-process for product completion.

For example, as shown in FIG. 12, the insulating film 7 is attached to the other surface of the circuit pattern 6 to which the insulating film 7 is not attached, and the flexible printed circuit board is formed through a process such as hot pressing. can complete.

In the case of the master mold 1 in which the wall structure 4 is formed, it can be reused for a certain number of times to form a circuit pattern (repetition to the extent that the wall structure 4 is not deformed), so the manufacturing cost of the flexible printed circuit board has the effect of reducing

Meanwhile, in some embodiments of the present invention, openings may be formed in both or one of the insulating films 7 attached to both sides of the circuit pattern 6 . These openings allow circuit patterns to be exposed, thereby enabling connection of circuits or devices, mounting of components, and the like.

Depending on the printed circuit board to be manufactured, these openings may have various shapes such as a hole shape or a rectangular shape, and may be formed in plurality.

According to the present invention, since such an opening can be formed in advance by processing an insulating film on which the copper foil layer is not laminated, the problem of damaging the copper foil layer by forming the opening later does not occur.

In addition, oxidation prevention treatment may be applied to at least a portion of the circuit pattern 6 exposed through the opening. That is, since a portion of the circuit pattern 6 is exposed, oxidation may be prevented from proceeding by performing oxidation prevention treatment thereon to form an oxidation prevention layer.

For example, HASL (Hot Air Solder Leveling), which flattens the thickness of the solder by melting b/Sn alloy (Solder) and burying it on the substrate passing through the transfer belt, and applying hot air in the subsequent process, and electroless nickel on the same An electroless gold plating method in which about 5 microns of gold is plated and about 0.03 microns of gold is electrolessly plated on nickel, a method in which electroplating and electroless plating are combined to plate nickel and gold, and an organic form of Alkyl Imidazole. An OSP (Organic Solderability Preservative) method that prevents oxidation of copper by selectively forming a film of about 0.2 to 0.4 microns on copper with a compound may be performed. In addition, since various known oxidation prevention treatment methods may be used, more detailed Description is omitted.

On the other hand, in the case of attaching the insulating film having openings formed on both sides as described above, the circuit patterns 6 are exposed on both sides of the printed circuit board, and double-sided patterning may be possible.

At this time, at least a portion of the circuit pattern 6 exposed through the openings on both sides may be subjected to the above-described oxidation prevention treatment to form a terminal portion.

Alternatively, as shown in FIG. 10, after preparing two master molds 1 on which circuit patterns 6 are formed and attaching an insulating film between the two circuit patterns 6, a flexible printed circuit board is manufactured from the master mold. By separating, it is possible to obtain a double-sided flexible printed circuit board having circuit patterns formed on both sides.

In this process, the product can be completed using a conventional flexible printed circuit board manufacturing method. That is, a hole is formed by penetrating the desired connection location through a drilling process, and plating of a conductive material is performed on the hole so that the circuit patterns 6 on both sides can be connected, and the circuit patterns 6 on both sides A terminal portion may be formed by attaching an insulating film having openings and performing the above-mentioned anti-oxidation treatment. At this time, the attachment of the insulating film and the anti-oxidation treatment may be performed before the process of forming the through hole.

After this process, components can be mounted using the anti-oxidation treated terminal portion (exposed circuit pattern) as a contact point.

A conductive connection member may be used between these components and the exposed terminal portion, and for example, a conductive adhesive, conductive cream, solder, or the like may be used.

The flexible printed circuit board manufactured in this way may be completed as a product through an external processing process such as cutting.

Between the above processes, additional processes for product production (eg, washing process, drying process, etc.) may be added as needed.

Meanwhile, the present invention can be performed in a flexible printed circuit board manufacturing facility configured to perform each process such as coating, exposure, development, plating, attachment, and peeling, and the control device of such manufacturing facility controls the operation of each process. can do. These manufacturing facilities may be additionally provided with a robot arm, a conveying belt, etc. for transferring products between each process, and various other equipment may be added. In addition, the control device may include a computer-readable storage medium storing instructions for controlling manufacturing equipment to perform each process, and such a storage medium is combined with a processor to cause the processor to perform each step of the present invention. It can be.

The present invention has been described with reference to the embodiments shown in the drawings, but this is only exemplary, and those skilled in the art can make various modifications and equivalent other embodiments. will understand Therefore, the technical protection scope of the present invention should be determined by the claims below.

1: Master mold
2: 1st plating
3: dry film
4: ink composition
5: circuit pattern formation area
6: circuit pattern
7: insulating film

Claims (4)

performing primary plating on the master mold;
attaching a dry film to the master mold on which the plating is performed;
removing portions other than the portion corresponding to the circuit pattern from the attached dry film;
removing the first plated portion from the dry film-removed portion;
removing residual dry film from the master mold;
Covering the master mold with an ink composition by performing printing using ink;
exposing the primarily plated portion by polishing the ink composition;
removing the remaining primary plating portion from the master mold; and
and forming the circuit pattern by plating a conductive material on the master mold.
According to claim 1,
After the step of forming the circuit pattern,
attaching an insulating film to the formed circuit pattern; and
The flexible printed circuit board manufacturing method further comprising the step of separating the flexible printed circuit board on which the insulating film and the circuit pattern are laminated from the master mold.
According to claim 1,
The step of removing the primary plated portion from the dry film-removed portion includes removing a portion of the master mold in addition to the primary plated portion through an etching process. .
According to claim 1,
The method of manufacturing a flexible printed circuit board, characterized in that the conductive material is copper, and the insulating film is a polyimide film.

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