KR100651535B1 - Rigid-flexible printed circuit board and method for manufacturing the same - Google Patents

Abstract

A rigid-flexible printed circuit board and a fabrication method thereof are provided to achieve compactness of a product where the rigid-flexible printed circuit board is used, by reducing total thickness of the rigid-flexible printed circuit board mounted with an electronic component. A flexible region includes at least one flexible film where a first circuit pattern is formed at least one plane. A rigid region includes a number of insulation layers(140) formed by intervening an extended part of the one flexible film, at a position adjacent to the flexible region. An aperture is formed on the insulation layer located at the outermost part of the rigid region and then a stepped part is formed on the surface of the rigid region.

Description

Rigid-flexible printed circuit board and method for manufacturing the same

1 is a cross-sectional view showing a conventional flexible printed circuit board.

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

3 is a flowchart illustrating a method of manufacturing a flexible printed circuit board according to the present invention.

4A to 4H are process diagrams illustrating a method of manufacturing a flexible printed circuit board according to an exemplary embodiment of the present invention.

5A to 5G are flowcharts illustrating a method of manufacturing a flexible printed circuit board according to another exemplary embodiment of the present invention.

FIG. 6A illustrates an electronic component mounted on a conventional flexible printed circuit board.

FIG. 6B illustrates an electronic component mounted on a flexible printed circuit board according to an exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100, 200: base substrate 102, 202: flexible film

104, 150, 250, 270: copper foil layers 106, 206: first circuit pattern

108, 109, 208, 264: Protective film 120, 220: 1st insulating layer

122, 222: first opening 140, 240: second insulating layer

142 and 242: second openings 144 and 244: third openings

146, 260: laminate 152, 272: through hole

154 and 274: plating layers 160 and 262; Second circuit pattern

170: electronic component 280: third circuit pattern

The present invention relates to a flexible printed circuit board and a manufacturing method thereof, and more particularly, to a flexible printed circuit board having a stepped portion formed on its surface.

As Rigid-Flexible Printed Circuit Board (RFPCB) has emerged as a hot topic in the printed circuit board market, interest in the market is increasing. A flexible printed circuit board is a flexible region in which a circuit pattern is formed on a flexible film such as polyester or polyimide (PI), which is flexible, and a rigid region, in which an insulating layer is laminated on the flexible film, thereby increasing physical hardness. In addition, the three-dimensional solid structure wiring is possible, and the ease of assembly, the market size of the industry that requires the design of highly integrated circuits, such as notebook PC, digital camera, camcorder, mobile communication terminal is expanding In proportion to that, the demand is increasing.

Looking at the trend of mobile phones in recent years, the adoption and demand of the folder type (folder type) is rapidly increasing in the conventional bar-type, coupled with the demand of the flexible printed circuit board applied to the folder-type mobile phone Printed circuit board makers, which have been exploding and focused on producing low-cost printed circuit boards, are also focusing on developing and producing high-priced mobile printed circuit boards.

1 is a cross-sectional view of a flexible printed circuit board according to a conventional example, which will be described with reference to the following.

As shown in FIG. 1, a conventional flexible printed circuit board includes a flexible region (I) including a polyimide film (2) formed on one surface of a first circuit pattern (1) protected by a coverlay film (3). And a rigid region (II) including an insulating layer 4 formed on an extension of the polyimide film 2 having the first circuit pattern 1 formed thereon and a second circuit pattern 5 formed on the upper surface of the insulating layer 4. Here, the first circuit pattern 1 and the second circuit pattern 5 is electrically connected to each other by the through hole (6).

As described above, in the conventional flexible printed circuit board described above, since the thickness of the rigid region I is always constant, when the electronic component is mounted on the rigid region I to form a product, the flexible printed circuit board is There is a problem that brings a limitation in reducing the thickness of the product used.

For example, in the mobile communication terminal industry in which a flexible printed circuit board is mainly used, since the pursuit of miniaturization and functional diversification of the mobile communication terminal is increasingly required, high density and compactness of the flexible printed circuit board are required. However, since the thickness of the flexible region and the rigid region of the flexible printed circuit board is formed to be constant, the thickness of the flexible printed circuit board on which the electronic component is mounted should be placed on the upper surface of the rigid region when mounting the electronic component. Has a rigid area thickness + electronic component thickness, which makes it difficult to realize miniaturization of products in which a flexible printed circuit board is used.

In order to solve the problems described above, the present invention forms a stepped portion in the rigid area of the flexible printed circuit board to reduce the total thickness of the flexible printed circuit board on which the electronic components are mounted, and to print the flexible component when the electronic components are mounted. The present invention relates to a flexible printed circuit board and a method of manufacturing the same.

In order to solve the above technical problem, the present invention is a flexible region including at least one flexible film having a first circuit pattern formed on at least one surface, and at least one extension portion of the flexible film at a position adjacent to the flexible region A flexible printed circuit board comprising a rigid region including a plurality of insulating layers interposed therebetween, wherein an opening is formed in an insulating layer positioned at the outermost portion of the rigid region, and a stepped portion is formed on a surface of the rigid region. To provide.

In the flexible printed circuit board according to the present invention, the flexible region may include a base substrate on which a first circuit pattern formed on at least one surface of the flexible film is protected by a protective film.

In the flexible printed circuit board according to the present invention, the rigid region further includes at least one circuit layer having a second circuit pattern electrically connected to the first circuit pattern between the plurality of insulating layers. do.

In addition, in the flexible printed circuit board according to the present invention, the outermost insulating layer is characterized in that it further comprises a third circuit pattern electrically connected to the first circuit pattern on the upper surface.

Further, in the flexible printed circuit board according to the present invention, the stepped portion of the rigid region is formed to mount at least a part of the electronic component.

In order to solve the above technical problem, the present invention, (A) providing a base substrate in which a part of the first circuit pattern formed on at least one surface of the flexible film is protected with a protective film, (B) a circuit protected with a protective film Providing a first insulating layer having a first opening corresponding to the pattern and a second insulating layer having a second opening corresponding to the first opening and a third opening having a predetermined size, (C) a protective film protected by a protective film Forming a laminate by alternately stacking one or more first insulating layers and a base substrate so as to expose a portion of a circuit pattern, (D) forming a stepped portion by laminating a second insulating layer on at least one surface of the laminate And (E) forming a second circuit pattern electrically connected to the first circuit pattern on both surfaces of the laminate in which the second insulating layer is laminated. To to provide.

In the method for manufacturing a flexible printed circuit board according to the present invention, after step (C), (F) a circuit layer and a third circuit pattern having a third circuit pattern electrically connected to the first circuit pattern on both surfaces of the laminate. It characterized in that it further comprises the step of forming one or more insulating layers alternately.

In addition, in the method of manufacturing a flexible printed circuit board according to the present invention, before the step (D), (G) further comprises the step of protecting a portion of the laminate corresponding to the third opening with a protective film. It is done.

In addition, in the method for manufacturing a flexible printed circuit board according to the present invention, the first opening, the second opening, and the third opening may be formed by punching.

In the method for manufacturing a flexible printed circuit board according to the present invention, the first opening, the second opening, and the third opening may be formed by router processing.

In addition, in the method for manufacturing a flexible printed circuit board according to the present invention, the first insulating layer and the second insulating layer are characterized in that the prepreg of the semi-cured state.

In addition, in the method for manufacturing a flexible printed circuit board according to the present invention, the protective film is characterized in that the polyimide film.

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described with reference to an accompanying drawing.

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

Referring to FIG. 2, a flexible printed circuit board according to an embodiment of the present invention includes a flexible region (III) including at least one flexible film 102 having a first circuit pattern 106 formed on at least one surface thereof. ) And a rigid region (IV) comprising at least one insulating layer 120 formed therebetween with an extension of at least one flexible film 102 at a location adjacent to the flexible region (III). An opening is formed in the insulating layer 140 located at the outermost part of the region IV, so that the stepped portion A is formed on the surface of the rigid region IV.

Here, the insulating layer 140 positioned at the outermost portion of the rigid region IV further includes a second circuit pattern 160 electrically connected to the first circuit pattern 106 and the through hole 152 on the upper surface thereof. In addition, the stepped portion A of the rigid region IV may be used to mount at least a part of the electronic component.

In addition, the protective film 108 may be coated on the first circuit pattern 106 forming the flexible region III to be protected from the external environment.

In this case, the flexible printed circuit board according to another embodiment of the present invention has at least one circuit in which a second circuit pattern electrically connected to the first circuit pattern is formed between a plurality of insulating layers having no flexible film interposed therebetween. It may further comprise a layer.

In the flexible printed circuit board according to an embodiment of the present invention, at least a part of the electronic component is subsequently mounted on the stepped portion formed in the rigid region, thereby reducing the total thickness of the flexible printed circuit board on which the electronic component is mounted. A flexible printed circuit board enables the miniaturization of products used.

3 to 5 are views illustrating a method of manufacturing a flexible printed circuit board according to the present invention.

3 is a flowchart illustrating a method of manufacturing a flexible printed circuit board according to an exemplary embodiment of the present invention, and FIGS. 4A to 4H illustrate a method of manufacturing a flexible printed circuit board according to FIG. 3 in detail. 5A to 5G are flowcharts illustrating a method of manufacturing a flexible printed circuit board according to another exemplary embodiment of the present invention.

First, referring to FIG. 3, a method of manufacturing a flexible printed circuit board according to an exemplary embodiment of the present invention will be described.

A portion of the first circuit pattern formed on at least one surface of the flexible film provides a base substrate protected by a protective film (S100).

The protective film is applied to the first circuit pattern region in which the flexible region is to be formed in the base substrate so as to be protected from the external environment.

At this time, it is preferable to use a flexible polyimide film as a protective film.

Next, a first insulating layer having a first opening and a second insulating layer having a second opening and a third opening are provided (S200).

The second opening of the second insulating layer has a size corresponding to the first opening and the third opening has a predetermined size, for example, a size corresponding to the electronic component to be mounted later.

Here, the first insulating layer and the second insulating layer then form a rigid region, and the first opening of the first insulating layer and the second opening of the second insulating layer correspond to the first circuit pattern region protected by the protective film. It is formed to a size, and then to form a flexible region.

At this time, the first opening, the second opening, and the third opening may be formed by punching or router processing.

Thereafter, at least one first insulating layer and one or more base substrates are alternately stacked to form a laminate (S300).

At this time, a part of the first circuit pattern protected by the protective film on the base substrate is exposed to the outside by the first opening of the first insulating layer.

Next, a stepped portion is formed on the surface by laminating a second insulating layer on at least one surface of the laminate (S400).

The second opening of the second insulating layer and the first opening of the first insulating layer form a flexible region, and the third opening of the second insulating layer forms a stepped portion on the surface of the rigid region.

Here, the stepped portion may be used to mount at least a part of the electronic component when mounting the electronic component.

At this time, according to another embodiment of the present invention, the step of protecting a portion of the laminate exposed by the second opening of the second insulating layer with a protective film may be further performed before.

Finally, the second circuit pattern is formed on both surfaces of the laminate in which the second insulating layer is stacked (S500).

Here, the second circuit pattern is formed to be electrically connected to the first circuit pattern.

As described above, in the method of manufacturing a flexible printed circuit board according to the present invention, by forming a stepped portion in a rigid region and then mounting at least a part of the electronic component at the step of mounting the electronic component, the electronic component is mounted. It can have the effect of reducing the total thickness of the mounted flexible printed circuit board.

4A to 4H are process diagrams illustrating a method of manufacturing a flexible printed circuit board according to an exemplary embodiment of the present invention.

First, as shown in FIG. 4A, a cross-section flexible copper clad laminate having a copper foil layer 104 formed on one surface of the flexible film 102 is provided.

As the flexible film 102, for example, a polyester or polyimide film may be used.

Subsequently, as shown in FIG. 4B, the first circuit pattern 106 is formed on the copper foil layer 104, and a portion of the first circuit pattern 106 is protected by the protective film 108 to form the base substrate 100. To form.

For example, the first circuit pattern 106 may be formed by applying a photosensitive material (not shown) to the upper surface of the copper foil layer 104, closely attaching the artwork film on which the pattern is formed, and then performing an exposure and development process to form an etching resist pattern. It may be formed using a photolithography method of forming and performing an etching process.

At this time, the first circuit pattern 106 formed on the base substrate 100, in order to protect the region of the first circuit pattern 106 to form a flexible region from the external environment, such as a polyimide-based film having a flexible film Is applied as a protective film 108 to the upper surface of the first circuit pattern 106 in close contact to protect the first circuit pattern 106.

Next, as shown in FIG. 4C, the first insulating layer 120 having the first opening 122 is provided.

The first opening 122 may be formed in a size corresponding to the area of the first circuit pattern 106 protected by the protective film 108 of the base substrate 100 by using a punching process or a router process.

Here, the first insulating layer 120 is a prepreg or bonding sheet made of a semi-cured state by infiltrating the thermosetting resin into the glass fiber is used, to increase the interlayer adhesion when laminating, after lamination Can increase the physical strength of the rigid area.

Thereafter, as shown in FIG. 4D, a second insulating layer 140 having a second opening 142 and a third opening 144 is provided.

The second opening 142 may have a size corresponding to the first opening 122 of the first insulating layer 120, and the third opening 144 may be formed to have a predetermined size by using a punching process or a router process. have.

Here, the prepreg or bonding sheet may be used for the second insulating layer 120.

Next, as illustrated in FIG. 4E, the first insulating layer 120 and the base substrate 100 are alternately stacked as many as desired to form the laminate 146.

At this time, the first circuit pattern 106 formed on the surface of the stack 146 corresponding to the third opening 144 of the second insulating layer 140 is protected by the protective film 109. For example, when the second insulating layer 140 is stacked on one surface of the stack 146, the surface of the stack 146 is exposed by the third opening 144, and thus the surface exposed to protect from the external environment. The first circuit pattern 106 formed in the protective film 109 is protected.

Thereafter, as shown in FIG. 4F, the second insulating layer 140 is laminated on one surface of the laminate 146, and the copper foil layer 150 is laminated on both surfaces.

Next, as illustrated in FIG. 4G, a through hole 152 is formed in the laminate 146 in which the second insulating layer 140 and the copper foil layer 150 are stacked, and electroless plating and electroplating are performed. The plating layer 154 is formed.

The through hole 152 formed to electrically connect the second circuit pattern to be formed in the copper foil layer 150 with the first circuit pattern 106 has a flexible film 102, a first insulating layer 120, and a first inside. Since the insulating layer 140 includes the same insulating material as the insulating layer 140, the plating layer 154 is formed by performing electroless plating and electrolytic plating, thereby providing conductivity to the inside of the through hole 152.

Here, the through hole 152 is formed according to a preset position by using a mechanical drill such as a CNC drill (Computer Numerical Control Drill).

In some embodiments, the plating layer 154 may be filled in the through-hole 152 formed on the inner wall by using a filling ink (not shown).

Subsequently, as shown in FIG. 4H, a second circuit pattern is formed on the copper foil layer 150 on which the plating layer 154 is formed, and the copper foil layer corresponding to the third opening 144 of the second insulating layer 140 ( 150 is removed to form a flexible printed circuit board having a stepped portion A formed on its surface.

In the flexible printed circuit board, a region in which the first circuit pattern 106 of the base substrate 100 is protected by the protective film 108 forms a flexible region III and is formed on the upper and lower surfaces of the base substrate 100. The first insulating layer 120 and the second insulating layer 140 form a rigid region (IV).

The stepped portion A formed on the surface of the flexible printed circuit board according to an embodiment of the present invention is a place where at least a part of the electronic component (not shown) is mounted, and the electronic component is mounted by the height of the surface step. The total thickness of the printed circuit board can be reduced.

5A to 5G are process diagrams illustrating a method of manufacturing a flexible printed circuit board according to another exemplary embodiment of the present invention.

First, as shown in FIG. 5A, a portion of the first circuit pattern 206 formed on one surface of the flexible film 202 provides the base substrate 200 protected by the protective film 208.

As an example, the first circuit pattern 206 is formed on a cross-sectional copper foil laminate in which a copper foil layer is formed on one surface of the flexible film 202 to form a first circuit pattern 206 by a photolithography method, and then to form a flexible region. The base substrate 200 may be formed by closely applying the protective film 208 to a portion of the region.

Since the area of the first circuit pattern 206 corresponding to the flexible area is exposed to the outside, the area of the first circuit pattern 206 is protected by the protective film 208 to protect the first circuit pattern 206 from the external environment. In this case, the polyimide film having flexibility may be used as the protective film 208.

Subsequently, as illustrated in FIGS. 5B and 5C, the first insulating layer 220 having the first opening 222 and the second insulating layer having the second opening 242 and the third opening 244 ( 240).

The first openings 222 and the second openings 242 have a size corresponding to the area of the first circuit pattern 206 protected by the protective film 208 of the base substrate 200 by punching or router processing. Can be formed. The third opening 244 may be formed by punching or router processing to a predetermined size.

Here, the first insulating layer 220 and the second insulating layer 240 is preferably used a prepreg or bonding sheet that can serve as an interlayer adhesive when interlayer insulation and stacking.

Next, as illustrated in FIG. 5D, the laminate 260 is formed by stacking the first insulating layer 220 and the copper foil layer 250 on both surfaces of the base substrate 200.

Subsequently, as illustrated in FIG. 5E, the second circuit pattern 262 is formed in the copper foil layer 250, and the second circuit pattern 262 corresponding to the third opening 244 of the second insulating layer 240 is formed. ) Area is protected with a protective film 264.

Subsequently, when the second insulating layer 240 is stacked on one surface of the stack 260 on which the second circuit pattern 262 is formed, the second circuit pattern 262 is exposed by the third opening 244. In order to protect from the external environment, the second circuit pattern 262 exposed to be closely adhered with the protective film 264.

Next, as illustrated in FIG. 5F, the second insulating layer 240 and the copper foil layer 270 are formed on the upper surface of the laminate 260 on which the second circuit pattern 262 is formed, and the first insulating layer 220 is disposed on the lower surface thereof. ) And the copper foil layer 270 are laminated.

Subsequently, as shown in FIG. 5G, a through hole 272 is formed in the copper foil layer 270, and after the electroless plating and electrolytic plating is performed to form the plating layer 274, the copper foil having the plating layer 274 formed thereon. The region corresponding to the third opening 244 is removed from the layer 270, and the third circuit pattern 280 is formed in the remaining region to form a flexible printed circuit board having the stepped portion B formed on the surface thereof.

The through hole 272 imparted with conductivity by the plating layer 274 electrically connects the first circuit pattern 206, the second circuit pattern 262, and the third circuit pattern 280 to each other.

In the flexible printed circuit board, a region in which the first circuit pattern 206 of the base substrate 200 is protected by the protective film 208 forms a flexible region (V) and is formed on the upper and lower surfaces of the base substrate 200. The second circuit pattern 262 and the third circuit pattern 280 formed on the upper surface of the insulating layer 220, the second insulating layer 240, the first insulating layer 220, and the second insulating layer 240 are rigid. The region VI is formed.

As described above, in the method of manufacturing a flexible printed circuit board according to another embodiment of the present invention, the stepped portion is formed on the surface of the rigid region, and then the electronic component is mounted by mounting at least a part of the electronic component in the stepped portion when mounting the electronic component. By reducing the total thickness of the flexible printed circuit board in the mounted state, it is possible to realize the miniaturization of products in which the flexible printed circuit board is used.

FIG. 6A is a view illustrating an electronic component mounted on a conventional flexible printed circuit board illustrated in FIG. 1, and FIG. 6B is a diagram illustrating an electronic component in a flexible printed circuit board according to an exemplary embodiment of the present invention illustrated in FIG. 4H. The figure which mounts a component is shown.

Referring to this, FIG. 6A illustrates a flexible region I and a first circuit pattern 1 including a polyimide film 2 formed on one surface of a first circuit pattern 1 protected by a coverlay film 3. Rigid printed circuit comprising a rigid region (II) including an insulating layer (4) formed on an extension of the polyimide film (2) having a second) and a second circuit pattern (5) formed on an upper surface of the insulating layer (4). Although the total thickness of the flexible printed circuit board is mounted on the surface of the rigid region (II) on the substrate, the total thickness of the flexible printed circuit board is equal to the thickness of the electronic component 10 + the thickness of the flexible printed circuit board. 1 includes a flexible region (III) including a flexible film (102) on which a circuit pattern (106) is formed and an insulating layer (120) formed with an extension of the flexible film (102) interposed therebetween, An opening is formed in the insulating layer 140 so that the rigid region IV having the stepped portion A formed on the surface thereof. By mounting the electronic component 170 on the stepped portion A of the rigid region IV in the flexible printed circuit board including the printed circuit board, the total thickness of the flexible printed circuit board on which the electronic component 170 is mounted is (electronic component ( 170) thickness + thickness of the flexible printed circuit board)-It becomes the thickness of the stepped portion can realize the slim (slim) and miniaturization of the product in which the flexible printed circuit board is used.

As described above, the present invention has been described through specific embodiments, but the scope of the present invention is not limited to the above embodiments, and various modifications are possible within the scope of the present invention. It is intended that the scope of the invention only be limited by the following claims.

According to the flexible printed circuit board of the present invention and a method of manufacturing the same, the stepped portion is formed in the rigid region, and then, at the time of mounting the electronic component, at least a part of the electronic component is mounted to the stepped portion, thereby the rigidity on which the electronic component is mounted. By reducing the thickness of the printed circuit board, it is possible to realize slimming and miniaturization of products in which the flexible printed circuit board is used.

For example, when the flexible printed circuit board according to the present invention is used in a mobile communication terminal, at least a part of the LCD is mounted on the stepped portion of the flexible printed circuit board to reduce the thickness of the mobile communication terminal, thereby making the product slimmer and smaller. It has an effect that can be realized.

Claims (12)

A flexible region including at least one flexible film having a first circuit pattern formed on at least one surface thereof; And A rigid region including a plurality of insulating layers formed between the extension portions of the at least one flexible film at a position adjacent to the flexible region; Including, And an opening is formed in an insulating layer positioned at the outermost portion of the rigid region, and a stepped portion is formed on a surface of the rigid region. The flexible printed circuit board of claim 1, wherein the flexible region comprises a base substrate on which the first circuit pattern formed on at least one surface of the flexible film is protected by a protective film. The flexible printed circuit of claim 1, wherein the rigid region further comprises at least one circuit layer having a second circuit pattern electrically connected to the first circuit pattern between the plurality of insulating layers. Board. The flexible printed circuit board of claim 1, wherein the outermost insulating layer further comprises a third circuit pattern electrically connected to the first circuit pattern on an upper surface thereof. The flexible printed circuit board of claim 1, wherein the stepped portion of the rigid area is formed to mount at least a part of the electronic component. (A) providing a base substrate on which a portion of the first circuit pattern formed on at least one surface of the flexible film is protected by a protective film; (B) providing a first insulating layer having a first opening corresponding to the circuit pattern protected by the protective film, and a second insulating layer having a second opening corresponding to the first opening and a third opening having a predetermined size. step; (C) forming a laminate by alternately stacking one or more of the first insulating layer and the base substrate to expose a portion of the first circuit pattern protected by the protective film; (D) forming a stepped portion by laminating the second insulating layer on at least one surface of the laminate; And (E) forming a second circuit pattern electrically connected to the first circuit pattern on both surfaces of the laminate in which the second insulating layer is stacked; Method of manufacturing a flexible printed circuit board comprising a. The method of claim 6, wherein after step (C), (F) alternately forming at least one circuit layer having a third circuit pattern electrically connected with the first circuit pattern and at least one additional first insulating layer on both surfaces of the laminate; Method of manufacturing a flexible printed circuit board further comprising a. According to claim 6, Before the step (D), (G) protecting a portion of the laminate corresponding to the third opening with a protective film; Method of manufacturing a flexible printed circuit board further comprising a. The method of claim 6, wherein the first opening, the second opening, and the third opening are formed by punching. The method of claim 6, wherein the first opening, the second opening, and the third opening are formed by router processing. The method of claim 6, wherein the first insulating layer and the second insulating layer are prepregs in a semi-cured state. The method of claim 6, wherein the protective film is a polyimide film.

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