KR100731819B1 - Manufacturing process of multiple flexible printed circuit board - Google Patents

Abstract

A method for manufacturing a multiple flexible printed circuit board is provided to form a micro circuit by selectively performing copper-plating on a penetration hole or a via-hole formed on an inner layer and an outer layer. A method for manufacturing a multiple flexible printed circuit board includes the steps of: processing a penetration hole or a via-hole on a copper clad laminate plate having a copper layer stacked on a base film(S10); forming a plating layer to apply conductivity to the copper clad laminate plate passed through the hole processing step, and performing copper-plating on the copper clad laminate plate(S11); attaching a dry film for preventing the plating layer, which is plated on the penetration hole or the via-hole, from being etched by laminating the dry film on the copper clad laminate plate(S12); half-etching a part except the penetration hole or the via-hole of the copper clad laminate plate having the dry film(S13); exfoliating the dry film after the half-etching process(S14); forming circuit patterns on both planes of the copper clad laminate plate(S15); laminating outer copper clad laminate plates on both planes of the copper clad laminate plate having the circuit pattern(S16); processing a second via-hole on the outer copper clad laminate plate or a second penetration hole which penetrates the outer copper clad laminate plate and the copper clad laminate plate; forming the plating layer to apply the conductivity to the outer copper clad laminate plate after the hole processing step, and performing copper-plating on the outer copper clad laminate plate(S17); attaching the dry film for preventing the plating layer plated on the second penetration hole or the second via-hole, from being etched by laminating the dry film on the outer copper clad laminate plate; and selectively half-etching a part except the second penetration hole or the second via-hole.

Description

Manufacturing process of multiple flexible printed circuit boards

1 is a flowchart illustrating a manufacturing process of a conventional general multilayer FPCB;

2A is a view showing a state in which a through hole is formed in a stacked FPCB;

2B is a view showing a state in which electroless plating is performed on the FPCB shown in FIG. 2A;

2C is a view showing a state in which electrolytic copper plating is performed on the FPCB shown in FIG. 2B;

3 is a view showing an example of an FPCB manufactured by a conventional general manufacturing method,

4 is a flowchart illustrating a method of manufacturing a multilayer flexible printed circuit board according to an embodiment of the present invention;

5A is a view showing an inner layer electroless plating process in the method of manufacturing the multilayer FPCB shown in FIG. 4;

5B is a view showing a process of attaching a dry film after the electroless plating process illustrated in FIG. 5A;

Figure 5c is a view showing the inner layer copper plating process after the dry film shown in Figure 5b,

Figure 5d is a view showing a state in which the dry film peeled off after the inner layer copper plating process shown in Figure 5c,

6 is a flowchart illustrating a method of manufacturing a multilayer FPCB according to another embodiment of the present invention;

7A is a view showing an inner layer plating process in the method of manufacturing the multilayer FPCB shown in FIG. 6;

Figure 7b is a view showing a process of attaching a dry film after the plating process shown in Figure 7a,

Figure 7c is a view showing the inner layer copper plating process after the dry film shown in Figure 7b,

Figure 7d is a view showing a state in which the dry film peeled off after the inner layer copper plating process shown in Figure 7c,

8 is a schematic cross-sectional view of a multilayer FPCB fabricated by the present invention.

The present invention relates to a method for manufacturing a multilayer flexible printed circuit board, and more particularly, to prevent the thickening of the bent portion due to copper plating, and to maintain the stretching force of the original copper foil to prevent cracks from occurring. In addition, the present invention relates to a method for manufacturing a multilayer flexible printed circuit board capable of improving flexibility.

In general, a printed circuit board (PCB) is a circuit formed of a conductive material such as copper foil on an electrically insulating substrate substrate, and refers to a substrate immediately before mounting an electronic component.

In recent years, due to the development of electronic components and component embedding technology and the miniaturization of electronic products, the demand for flexible printed circuit boards (hereinafter referred to as 'FPCB') has been continuously growing, and also semiconductor integration The rapid development of integration in circuits has led to the development of surface mount technology for mounting small chips and components, and the demand for multilayer FPCBs that can be easily embedded in more complex and narrow spaces continues to increase.

In particular, in the case of a multi-layered FPCB which is easy to increase the density of circuits and has a high level of use, there is a need for technology development for the manufacturing technology as the usage increases with the development of cameras, mobile phones, liquid crystal displays, etc. It's happening.

1 is a flow chart illustrating a conventional manufacturing process of a conventional multi-layer FPCB, Figure 2a is a view showing a through hole formed in the laminated FPCB, Figure 2b is a state in which the electroless plating is performed on the FPCB shown in Figure 2a 2C is a view showing a state in which electrolytic copper plating is performed on the FPCB shown in FIG. 2B.

First, referring to FIG. 1, a flexible copper foil laminate in which copper foil is laminated on both sides of a base film made of a material such as polyimide is prepared and a reference hole is processed (S1).

Standard hole processing is to process working standard hole in flexible copper clad laminate through NC drill process or press process.

On the other hand, an adhesive sheet is laminated | stacked under high temperature and high pressure on the flexible copper foil laminated board which finished the reference hole process.

Next, dry film lamination is performed on the laminated flexible copper foil laminate, and a circuit is formed in the inner layer through an exposure, development, and etching process (S2).

Next, after forming an inner layer circuit, a copper clad laminated board is prepared and laminated using an adhesive sheet (S3).

On the other hand, in the portion corresponding to the bent portion of the finished product at the time of lamination to remove the adhesive to form an air gap (air gap).

Next, referring to FIG. 2A, a through hole 3 is formed in a required portion on the circuit (S4).

At this time, the electrical foil is not yet electrically conducted between the copper foil 1 and the outer copper foil 2 of the internal circuit. On the other hand, for the sake of simplicity, the insulating layers inside the substrate are not shown, and the curved portion is omitted.

Next, referring to FIG. 2B, electroless plating is performed to impart electrical conductivity to the inside of the through hole 3 (S5).

In order to secure the plating reliability inside the through hole 3, a desmear treatment is performed, and electroless plating is performed to form a conductive layer 4 inside the through hole 3 to impart conductivity.

Next, referring to FIG. 2C, after electroless plating is performed, electrolytic copper plating is performed such that the copper plating layer 5 is formed inside the outer copper foil 2 and the through hole 3 of the substrate (S6).

Finally, the circuit of the outer layer is formed, and the FPCB is completed through a post-treatment process such as surface treatment (soldering or gold plating, etc.) or outer processing according to various specifications (S7).

3 is a view showing an example of an FPCB manufactured by a conventional general manufacturing method.

Referring to the drawings, it can be seen that the copper plating layer 9 is formed in the inner layer and the outer layer in the bent portion (a).

Specifically, the copper plating layer 9 is formed on the “A” portion formed in the inner layer of the bent portion and the “B” portion formed on the outer layer, respectively, and the curved portion thickened by the copper plating layer 9 is inferior in flexibility. The layer 9 thickened with copper plating has a problem in that it is difficult to form a fine circuit when forming a circuit.

Incidentally, reference numerals not described in the drawings indicate a coverlay 6, an adhesive sheet 7, a polyimide 5 as a base film, a PSR 8, and a via hole 9.

The through hole may be divided into an inner layer through hole 3 and an outer layer through hole 3 ′.

The present invention has been made to solve the above problems, it is possible to maintain the bending characteristics of the copper foil to prevent the occurrence of cracks, to provide a method for manufacturing a multilayer flexible printed circuit board capable of forming a fine circuit. It is.

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The disclosed method of manufacturing a multilayer flexible printed circuit board includes a hole processing step of processing a through hole or a via hole in a copper foil laminate in which a copper foil layer is laminated on a base film; An electroless plating step of forming a plating layer to impart electrical conductivity to the copper foil laminated plate which has been subjected to the hole processing step; Dry film attachment step of laminating the dry film on the copper foil laminated plate to prevent the copper plated portion except the through-hole or via hole; An inner layer copper plating step of selectively copper plating through-holes or via-holes of the copper-clad laminate with a dry film attached thereto; A dry film peeling step of peeling the dry film after the inner layer copper plating step; And a circuit forming step of forming a circuit pattern on both surfaces of the copper-clad laminate.

Here, after the circuit forming step, the outer layer of the laminated copper clad laminate on the upper and lower surfaces of the copper clad laminate, and the outer layer for selectively copper plating the second through hole or the second via hole formed in the outer copper clad laminate through the outer copper clad laminate It is preferable to include a plating step.

In addition, the outer layer plating step, the hole processing step of processing to form a second through hole or the second via hole, the electroless plating step of forming a plating layer to impart electrical conductivity to the outer layer copper laminate laminated through the hole processing step, Dry film attaching step that prevents copper plated parts except the second through hole or the second via hole by laminating the dry film on the outer layer copper laminate, and outer layer copper plating step to selectively copper plate the second through hole or the second via hole. It is desirable to.

According to another aspect of the present invention, there is provided a method of manufacturing a multilayer flexible printed circuit board, including: a hole processing step of processing through holes or via holes in a copper foil laminate in which a copper foil layer is laminated on a base film; A plating step including an electroless plating for forming a plating layer and an electroplating for copper plating the copper foil laminated plate that has undergone electroless plating to impart electrical conductivity to the copper foil laminated plate that has undergone the hole processing step; A dry film attaching step of laminating a dry film on the copper-clad laminate to prevent etching of the plated layer plated in the through hole or the via hole; A half etching step of half-etching portions except through-holes or via holes of the copper-clad laminate to which the dry film is attached; A dry film peeling step of peeling the dry film after the half etching step; And

And forming a circuit pattern on both sides of the copper-clad laminate.

In this case, after the circuit forming step, the outer copper clad laminate is laminated on the upper and lower surfaces of the copper clad laminate, and a portion except for the second through hole penetrating the outer copper clad laminate and the copper foil laminated plate or the second via hole formed in the outer copper clad laminate is selectively selected. It is preferable to include an outer layer half etching step of half etching.

In addition, the outer layer half etching step may include a hole processing step of processing a second through hole or a second via hole, and an electroless plating step of forming a plating layer to impart electrical conductivity to the outer copper clad laminate that has undergone the hole processing step; An outer layer plating step including an electroplating process for copper plating a copper foil laminated plate that has undergone electroless plating, and a dry film which laminates a dry film on the outer copper laminate plate to prevent the plating layer plated on the second through hole or the second via hole from being etched. It is preferable to include an attachment step.

The terms or words used in this specification and claims are not to be construed as being limited to their ordinary or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best describe their invention. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

4 is a flowchart illustrating a method of manufacturing a flexible printed circuit board (FPCB) hereinafter according to an embodiment of the present invention, and FIG. 5A is a method of manufacturing the multilayer FPCB illustrated in FIG. 4. 5 is a diagram illustrating a process of attaching a dry film after the electroless plating process illustrated in FIG. 5A, and FIG. 5C is a diagram of an inner layer copper plating process after attaching a dry film illustrated in FIG. 5B. 5D is a view showing a state in which the dry film is peeled off after the inner layer copper plating process shown in FIG. 5C, and FIG. 8 is a view schematically showing a cross section of the multilayer FPCB manufactured by the present invention.

First, referring to FIG. 4, in the method of manufacturing a multilayer FPCB according to an embodiment of the present invention, the through hole 30 or the non-coating layer is formed on the copper foil laminated plate 10 in which the copper foil layer 11 is laminated on the base film 12. The ahole 40 is processed (S10). (See FIG. 5A).

In this case, as an example of the base film, polyimide is generally used, but is not necessarily limited thereto.

Next, referring to FIG. 5A, electroless plating is performed to impart electrical conductivity to the copper-clad laminate 10 (S11).

After the electroless plating process, the electroless plating layer 20 having a thickness of about 1 to 2 μm is formed on the copper foil crystal layer plate 10.

Next, referring to FIG. 5B, the dry film 50 is laminated on the copper-clad laminate 10 to prevent copper plating from portions other than the through hole 30 or the via hole 40 (S12).

The dry film 50 covers the remaining copper foil laminated plate 10 except for the through hole 30 or the via hole 40 formed in the copper foil laminated plate 10.

Specifically, the shape of the dry film 50 is selectively processed by the inner layer copper plating, which will be described later, so that only the through hole 30 or the via hole 40 and its periphery are copper plated, and laminated on the copper foil laminated plate 10.

Next, referring to FIG. 5C, the through hole 30 or the via hole 40 formed in the copper clad laminate 10 is selectively copper plated (S13).

Selective copper plating of the through hole 30 or the via hole 40 can prevent copper plating on the copper foil layer 11 in the bent portion (a), which will be described later, so that bending characteristics can be maintained. Circuit formation may be possible (see FIG. 8).

Next, referring to FIG. 5D, after the inner layer copper plating step is performed, the dry film 50 is peeled off, and circuit patterns are formed on both surfaces of the copper clad laminate 10 (S14 and S15).

If the circuit pattern is formed on both sides of the copper-clad laminate 10 after the inner copper plating, the electroless plating layer 20 (refer to FIG. 5A) may be easily removed.

If the inner layer copper plating is performed after the circuit is formed on the inner layer, the electroless plating layer 20 remaining between the circuit patterns is not completely removed, thereby increasing the probability of a short.

Next, the outer layer copper laminated sheet 11 'is laminated on both surfaces of the inner layer copper laminated sheet 10 (S16).

Referring to FIG. 8, the multilayer FPCB as an example of the present invention is composed of eight layers, which will be referred to as one layer from the top of the drawings.

First, copper foil laminated boards 10a and 10b constituting two and three layers and six and seven layers are laminated on both surfaces of the copper foil laminated board 10 constituting four and five layers.

At this time, the coverlay 70 and the adhesive sheet 80 are interposed between the copper foil layers 11a and 11 constituting the three and four layers and the copper foil layers 11 and 11b constituting the five and six layers, respectively. Will be.

And the outer layer copper laminated board 11 'is laminated | stacked on both surfaces of the inner layer copper laminated boards 10a and 10b which comprise 2 to 7 layers.

At this time, the adhesive sheet 80 and the coverlay 70 are interposed between the copper foil layers 11 'and 11a constituting the first and second layers, and the copper foil layers 11b and 11 constituting the seventh and eighth layers. Between '), the adhesive sheet 80 and the base film polyimide 12 and the coverlay 70 are interposed.

Finally, referring to FIG. 8, a second through hole 30 ′ or an outer copper clad laminate 11 ′ penetrating through the outer copper clad laminate 11 ′ and the inner copper clad laminates 10, 10 a, and 10 b is formed. Outer layer plating for selectively copper plating the via holes 40 'is performed (S17).

On the other hand, the radioless to form a plating layer in order to impart electrical conductivity to the outer layer copper-clad laminate (11 ') through the hole processing step and hole processing step to form the second through hole (30') or the second via hole (40 ') is formed. Dry film attaching step and second through hole 30 'to prevent copper plating of parts except second through hole 30' or second via hole 40 'by laminating dry film on plating layer and outer copper clad laminate. ) Or an outer layer copper plating step of selectively copper plating the second via hole 40 '.

In addition, the outer layer plating step as described above may be carried out by repeating the hole processing step to the inner layer copper plating step of the inner layer in the same manner.

Hereinafter, a method of manufacturing a multilayer FPCB according to another embodiment of the present invention will be described.

6 is a flowchart illustrating a method of manufacturing a multilayer FPCB according to another embodiment of the present invention. FIG. 7A is a view illustrating an inner layer plating process in the method of manufacturing the multilayer FPCB shown in FIG. 6, and FIG. 7B is illustrated in FIG. 7A. Figure 7c is a view showing a process of attaching a dry film after the plating process, Figure 7c is a view showing the inner layer copper plating process after the dry film is shown in Figure 7b, Figure 7d is a dry film peeling after the inner layer copper plating process shown in Figure 7c It is a figure which shows the state.

Referring to FIG. 6, in the method of manufacturing a multilayer FPCB according to another embodiment of the present invention, the remaining portions except for the plating process (S21), half etching (S23), and outer layer half etching (S27) are shown in FIG. 4. It will be omitted in the same relationship with the manufacturing method of the multilayer FPCB according to an embodiment of.

First, referring to FIG. 7A, in the plating step, the electroless plating forming the plating layer 20 and the copper foil laminated plate 10 which has undergone electroless plating are applied to the copper foil laminated plate 10 which has undergone the hole processing step. Electroplating to form the plating layer 60 is included (S21).

Next, referring to FIGS. 7B and 7C, the through hole 30 or the via hole (not shown) formed in the copper-clad laminate 10 and the peripheral portion thereof are coated using the dry film 50 and then half etched (S23). ).

Since the thickness of the copper plating layer 60 formed on the copper foil layer 11 can be reduced by performing half etching, the bending characteristics of the bent portion (see FIG. 8) can be maintained and fine circuit formation can be possible. Will be.

Specifically, the half etching corrodes the thickness of the copper plating layer 60 plated on the copper foil layer 11, and the thinner the thickness of the copper plating layer 60 formed on the copper foil layer 11, the easier the formation of the microcircuit. have.

Next, after reducing the thickness of the copper plating layer 60 formed on the copper-clad laminate 10 through half etching, the dry film is removed and an inner layer circuit is formed.

Then, a second through hole penetrates the outer copper clad laminate 11 'and the copper clad laminate 10, 10a and 10b by laminating the outer copper clad laminate 11' on the upper and lower surfaces of the copper clad laminates 10, 10a and 10b. The outer layer half etching is performed by selectively half-etching portions other than the second via hole 40 'formed in the 30' or outer copper-clad laminate 11 '.

At this time, the outer layer half etching step is to impart electrical conductivity to the outer layer copper laminate (11 ') through the hole processing step and the hole processing step to form the second through hole (30') or the second via hole (40 '). In order to laminate the dry film on the outer layer plating step including the electroless plating step of forming the plating layer and the electroplating of the copper foil laminated plate 11 'subjected to the electroless plating and the outer layer copper laminate, the second through hole 30' Or a dry film attaching step of preventing the plating layer 60 plated in the second via hole 40 'from being etched.

As described above, the manufacturing method of the multilayer flexible printed circuit board according to the present invention provides the following effects.

First, it is possible to maintain the elongation peculiar to the copper foil in the bent portion, there is an advantage that can continue to maintain the bending characteristics.

Second, since only through-holes and via-holes formed in the inner layer and the outer layer are selectively copper plated, there is an advantage in that a fine circuit can be formed when the circuit is formed.

As mentioned above, although this invention was demonstrated by the limited embodiment and drawing, this invention is not limited by this, The person of ordinary skill in the art to which this invention belongs, Of course, various modifications and variations are possible within the scope of equivalent claims.

Claims (6)

delete delete delete A hole processing step of processing through-holes or via holes in the copper-clad laminate in which the copper foil layer is laminated on the base film; A plating step including an electroless plating for forming a plating layer and an electroplating for copper plating the copper foil laminated plate that has undergone electroless plating to impart electrical conductivity to the copper foil laminated plate that has undergone the hole processing step; A dry film attaching step of laminating a dry film on the copper-clad laminate to prevent etching of the plated layer plated in the through hole or the via hole; A half etching step of half-etching portions except through-holes or via holes of the copper-clad laminate to which the dry film is attached; A dry film peeling step of peeling the dry film after the half etching step; A circuit forming step of forming circuit patterns on both sides of the copper-clad laminate; A laminating step of laminating an outer layer copper laminated sheet on both sides of the copper laminated sheet having a circuit pattern formed thereon; A hole processing step of processing a second through hole through the outer copper clad laminate and the copper clad laminate, or a second via hole in the outer copper clad laminate; An outer layer plating step including an electroless plating for forming a plating layer and an electroplating for copper plating the outer layer copper foil laminated plate through the electroless plating in order to impart electrical conductivity to the outer layer copper laminate sheet which has undergone the hole processing step; A dry film attaching step of laminating a dry film on the outer copper laminate to prevent etching of the plating layer plated on the second through hole or the second via hole; An outer layer half etching step of selectively half-etching portions other than the second through hole or the second via hole; Method of manufacturing a multilayer flexible printed circuit board comprising a. delete delete

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