KR100467844B1 - Rigid flexible printed circuit board for mobile phone, and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a rigid flexible printed circuit board for a mobile phone and a manufacturing method thereof, comprising: (a) providing two cross-sectional CCLs; (b) forming an inner layer circuit in the two cross-sections CCL; (c) forming a flexible part by temporarily attaching and covering a coverlay on the substrate on which the inner layer circuit is formed; (d) stacking the prepreg at a predetermined position except for the central portion of the flexible portion; And (e) forming a circuit by forming a circuit after plating the stacked prepregs. According to the present invention, it is possible to provide a printed circuit board having high reliability by ensuring connection reliability by removing a connector, improving electrical characteristics, and having good flexibility by being applied to a mobile phone.

Description

Rigid flexible printed circuit board for mobile phone and its manufacturing method {RIGID FLEXIBLE PRINTED CIRCUIT BOARD FOR MOBILE PHONE, AND MANUFACTURING METHOD THEREOF}

The present invention relates to a rigid flexible printed circuit board in which a rigid part and a flexible part are combined, and a method of manufacturing the same. More particularly, the present invention relates to a rigid part without a connector system for use in a mobile phone. Rigid Flexible Printed Circuit Board for Mobile Phone, which electrically connects the conductive pads on the printed circuit board to each other, increases the surface mounting density of the parts, and strengthens the bending resistance of the bent portion by using a cross-section CCL. And it relates to a manufacturing method thereof.

In recent years, with the rapid growth of electronic devices such as notebook computers, PDAs, small video cameras, compact cameras, and electronic organizers, the printed circuit board industry is becoming an important core component for high integration and packaging of products. The technology for miniaturization, light weight, and light weight of the electronic device requires not only a small microfabrication technology of the mounted component, but also an optimized design technology for the mounting space, and a printed circuit that enables high density, high density component mounting, in particular. Provision of the substrate is necessary.

A printed circuit board is connected to or supports various components in accordance with a circuit design of an electric wiring to a printed circuit disc, which is often compared to neural circuits of electronic products. Current printed circuit boards include build-up boards, next-generation semiconductor package boards such as BGA (Ball Grid Array), CSP (Chip Size Package) and MCM (Multi Chip Module), aerospace / precision three-dimensional boards, Rigid It is focusing on special high value-added printed circuit boards such as flexible substrates, high-layer multilayer thin-impedance boards, metals, Teflon and ceramics. Among them, rigid flexible printed circuit board is a technology that combines the existing multilayer printed circuit board (MLB) technology and flexible (FPCB) technology together, and improves the reliability of connecting parts of MLB and FPCB in electronic devices and improves the surface mounting density of rigid parts. It is a special board capable of three-dimensional wiring using three-dimensional space.

That is, currently used multilayer printed circuit board (MLB) or flexible printed circuit board (FPCB) has a space problem, connection reliability problem, and component mounting problem due to the use of a separate connector, which is a rigid flexible printed circuit board This can be improved by applying Such a rigid flexible printed circuit board may simultaneously perform a function of a component mounting board and a function of an interface.

Therefore, a rigid flexible board is a board in which a rigid board and a flexible board are structurally coupled and a rigid part and a flexible part are connected without a separate connector. Since the connector is not used, a space problem on a printed circuit board can be solved. The reliability generated in the connection of the connector portion of the can be secured, and has the advantage of improving the component mountability.

International Patent Publication No. WO 96/04773 discloses a conventional method for forming a rigid flexible printed circuit board.

1 is a perspective view illustrating the conventional rigid flexible printed circuit board, and the first rigid substrate 140, the second rigid substrate 160, and the flexible substrate 120 connecting the rigid substrate to each other. It consists of. Each substrate includes conductive leads 126, 146, and 166, and the rigid substrates 140, 160 have through holes 148, 168 for connecting to inner layer circuits or for connecting surface mounted hardware or circuit elements. Include. Rigid substrates typically consist of many more layers than flexible substrates.

Referring to Fig. 2, there is shown a schematic vertical cross-sectional view of the conventional rigid flexible printed circuit board in a direction parallel to the longitudinal axis, wherein the flexible center layer is patterned with a polyimide layer 121 and a predetermined conductive circuit. Upper and lower copper foil layers 122a and 122b, and the center layer extends over the entire printed circuit board. A coverlay 123 is formed on the copper foil layers 122a and 122b to protect the surface circuit of the flexible substrate, and a prepreg 142 is formed on the coverlay to form a rigid substrate. It constitutes one or more circuit layers.

On the other hand, in the rapidly developing mobile phone industry, mobile phones are rapidly changing from the conventional bar type to the folder type, which is large in accordance with the needs of convenience and high functionality. The purpose of the present invention is to provide a display, increase an interface space, and ease of portability.

The FPCB, developed for this folder-type, is used to connect signals where a continuous repetitive motion of the bent portion is required, and connects between rigid boards using connectors, but the combination of such rigid boards and flexible boards Space problems due to the connector and poor connection reliability of the connector portion are occurring. In addition, the Multiflex product widely used in the mobile phone industry has the advantage of not requiring a connector, but has a problem in that component mounting is poor, hole reliability is low, and high cost due to raw materials.

In addition, there is a problem in that the bending resistance caused by the repetitive operation of opening and closing the folder as a mobile phone is converted to a folding mobile phone has a problem that needs to be improved.

As shown in FIG. 2, the double-sided CCL generally used for the flexible part 120 uses the polyimide 121 as a base film, and forms copper foils 122a and 122b on both sides. Therefore, when folding and unfolding the folding cellular phone, the stress is generated at the same time on both sides of the copper foils 122a and 122b. That is, when the copper foil 122a of one side is stretched and the copper foil 122b of the opposite side receives a larger force in a contracting form, the flexibility is reduced.

Accordingly, in order to solve the above problems, the present invention uses a mobile phone to electrically connect conductive pads on a printed circuit board arranged in a rigid part without a connector, increase the surface mounting density of the part, and uses a cross section CCL. A high quality printed circuit board and a manufacturing method thereof having enhanced flex resistance have been found, and the present invention has been completed based thereon.

SUMMARY OF THE INVENTION The present invention has been made to overcome the above-mentioned problems, and an object of the present invention is to provide a rigid flexible printed circuit board and a method of manufacturing the same for improving the reliability of the electrical connection by using in a mobile phone.

In addition, an object of the present invention is to solve the conventional problems as described above, to reduce the size and weight of a mobile phone by using a rigid flexible printed circuit board.

In addition, the present invention is to improve the flex resistance of the rigid flexible substrate bent portion that is a weak part in the use of a folding cell phone.

1 is a perspective view showing a conventional rigid flexible printed circuit board,

Figure 2 is a schematic vertical cross-sectional view of a conventional rigid flexible printed circuit board in a direction parallel to the longitudinal axis,

3 is a perspective view illustrating a rigid flexible printed circuit board for a mobile phone according to the present invention;

4 is a flowchart illustrating a manufacturing process of a rigid flexible printed circuit board for a mobile phone according to the present invention.

FIG. 5 is a cross-sectional view illustrating the A-A cross section of FIG. 3.

◎ Explanation of symbols for main part of drawing

120: flexible substrate 121: polyimide

122a, 122b: Copper foil 123: Coverlay

126, 146, 166: conductive leads 140, 160: rigid substrate

142: Prepreg 143: polyimide

144: circuit layer 148, 168: through hole

220: flexible substrate 221a, 221b: cross section CCL

222: inner layer circuit 223: coverlay

224: silver paste 225: cover paste

240, 260: rigid substrate 242: prepreg

246: conductive lead 248: through hole

As a means for achieving the above object, a method for manufacturing a rigid flexible printed circuit board for a mobile phone according to the present invention comprises: (a) providing two cross-sectional CCL; (b) forming an inner layer circuit in the two cross-sections CCL; (c) forming a flexible part by temporarily attaching and covering a coverlay on the substrate on which the inner layer circuit is formed; (d) stacking the prepreg at a predetermined position except for the central portion of the flexible portion; And (e) forming a circuit by forming a circuit after plating the stacked prepregs.

The two-sided CCL according to the present invention is characterized by using polyimide as the base film and using rolled annealed copper as the copper foil.

It is characterized in that it further comprises the step of shielding the silver paste on the flexible portion laminated the coverlay according to the present invention.

According to the invention is characterized in that it further comprises the step of coating the cover paste on the silver paste shield.

Shielding with an EMI shield film on the flexible portion laminated the coverlay according to the invention is characterized in that it further comprises.

In addition, the present invention is a printed circuit board comprising a flexible portion and a rigid portion,

(a) two cross-section CCLs with inner layer circuits formed; (b) a coverlay laminated at a predetermined position in the center of the cross section CCL; (c) prepregs stacked at predetermined positions except for the central portions of the two cross-sections CCL; And (d) a circuit formed on the stacked prepregs, wherein the flexible portion is formed at a predetermined position in the center portion, and the rigid portion is formed at a predetermined position except for the central portion which is the flexible portion. .

It characterized in that it further comprises a silver paste shield layer on the flexible portion laminated the coverlay according to the present invention.

A cover paste coating layer is further included on the silver paste shield layer according to the present invention.

EMI shield film layer is further included on the flexible part laminated the coverlay according to the present invention.

Accordingly, the present invention provides a high quality that electrically connects conductive pads on a printed circuit board arranged in a rigid part without a connector to be used in a mobile phone, increases the surface mounting density of parts, and enhances the bending resistance of the bent part by using a cross-section CCL. Provided are a printed circuit board and a method of manufacturing the same.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

3 is a perspective view showing an embodiment of a rigid flexible printed circuit board for a mobile phone according to the present invention, the first rigid substrate 240 and the second rigid substrate 260, and a flexible connecting the rigid substrate to each other It consists of the board | substrate 220. Each substrate includes conductive leads 246, and rigid substrates 240 and 260 include through holes 248 for connecting to inner layer circuits or for connecting surface mounted hardware or circuit elements.

The rigid flexible printed circuit board for mobile phones is a technology that combines the existing rigid (MLB) technology and the flexible (FPCB) technology. The substrate according to the present invention has a 4-2-4 layer structure (e.g., 8-2-8 layer structure, 8 rigid part layer, 2 flexible part layer) of polyimide cross-section CCL, It has the function of signal connection where continuous repetitive motion of parts is required, improves reliability of MLB and FPC connection in electronic devices, improves surface mount density of rigid parts, and enables three-dimensional wiring using three-dimensional space. Special board.

In such a rigid flexible printed circuit board 200 structure for a mobile phone, the flexible substrate 220 is connected throughout the rigid substrate, and the rigid substrates 240 and 260 are typically mounted in electronic components and other components in the assembly. It is connected to other circuit layers in the rigid substrate for electrical connection with the subcircuits and is also used to mount connectors and hardware. In particular, the flexible substrate functions to connect several rigid substrates, and allows the rigid substrates to be mounted on hardware devices of other substrates at various angles. In addition, as electronic circuits become more and more complicated, more complex multilayer rigid flexible printed circuit boards have been proposed.

Here, a rigid flexible printed circuit board refers to a board in which a rigid board (MLB) and a flexible board (FPCB) are structurally coupled so that a rigid part and a flexible part are connected without a separate connector. It is a printed circuit board that solves the component space problem caused by unused use, secures the connection reliability of the connector part, and improves the component mountability.

In addition, the MLB is a component mounting and signal connection board, and mainly serves as a main board, and is composed of four or more layers of FR-4 materials.

In addition, FPCB (Flexible printed circuit board) is a printed circuit board developed to cope with the trend of miniaturization and complexity of electronic products. It has excellent heat resistance, bending resistance, chemical resistance, small dimension change, and strong heat resistance. have.

FPCB has a single-sided structure, double-sided structure, double-sided exposure structure, and functions as an interface for signal connection where a continuous repetitive motion of a curved part is required, and functions as an interface, polyimide, coverlay, and adhesive ( It is mainly used for mobile phone LCD, camera battery, HDD, printer.

4 is a flowchart illustrating a manufacturing process of a rigid flexible printed circuit board for a mobile phone according to the present invention. This provides single-sided polyimide CCL → exposure → etching → internal inspection → coverlay cutting → coverlay punching → coverlay welding → flexible part vacuum press → oxide → no flow prepreg layup → lamination → Drill → Desmear and plating → Circuit formation → External inspection → PSR printing → Surface treatment → Router → Inspection

Here, CCL (Copper Clad Laminate) refers to a material that is completely cured to C-stage by attaching a copper foil to both sides of the prepared prepreg. The thickness of the CCL is less than 0.8 mm refers to the thickness of the prepreg only, and more than 0.8 mm refers to the thickness including the copper. In addition, prepreg refers to a material in which glass fibers are impregnated with resin (BT / Epoxy, FR4, FR5, etc.) and cured to B-stage.

Figure 5 is a schematic vertical cross-sectional view of a rigid flexible printed circuit board for a mobile phone according to the present invention in a direction parallel to the longitudinal axis.

Referring to this, an embodiment according to the present invention is a printed circuit board consisting of a rigid portion 240, 260 and a flexible portion 220, two-sided CCL (221a) coated with rolled copper foil on both sides using a polyimide as a base film. 221b) which extends over the entire printed circuit board. The two-sided CCLs 221a and 221b are formed through an exposure and etching process to form an inner circuit 222, and a coverlay 223 to protect the surface circuit of the flexible substrate on the copper foil layer on which the inner circuit 222 is formed. ) And the flexible part 220 is formed by a vacuum press. Then, the silver paste shield 224 is applied to the flexible portion 220 in which the coverlay 223 is stacked, and then the cover paste coating 225. It can also use an EMI shield film that combines silver paste shield and cover paste coating. In addition, a prepreg 242 is formed on the coverlay 223 to cover the remaining portions covered by the coverlay 223 to form the rigid substrates 240 and 260, and the cross-sectional CCLs 221a and 221b are formed. The prepreg 242 is laminated between and in the outer layer to form a rigid portion. Then, plating is performed on the prepregs laminated on the outer layer, or a copper foil layer is laminated, and then a circuit pattern is formed.

In addition, the present invention by using a silver paste shield and cover paste coating, or EMI shield film in the flexible portion as described above, it is possible to implement the electromagnetic interference (EMI) and electromagnetic compatibility (EMC) shield in the flexible portion, high reliability It is possible to provide a printed circuit board of.

This embodiment uses the materials shown in Table 1.

Item standard Polyimide CCL Cu thickness (rolled copper foil) 1 / 2Oz, 1Oz, 2Oz (single / duplex) Insulation layer thickness 1 / 2mil, 1mil, 2mil Coverlay (Polyimide Film) thickness 1 / 2mil, 1mil, 2mil No flow prepreg Glass cross type: t 0.06mm Reinforcement (FPC-only material) Glass Epoxy (FR-4) Polyimide film (Coverlay) Adhesive (FPC-only Material) Thermoplastic Adhesive (Epoxy + Acryl Resin) Silver film (EMI shield) Thickness 32㎛ (PPS FILM 9㎛, Conductive Adhesive 23㎛)

The rigid flexible printed circuit board for a mobile phone according to the present invention improves the flexibility which is important in a folding mobile phone. As shown in FIG. 5, the flexible part 220 is formed of two cross-sections CCL 221a and 221b. When the flexible part 220 is bent, the resilience or the compressive force is generated only on the side where the copper foils of the end face CCLs 221a and 221b are formed.

What has been described above is only one embodiment for implementing a rigid flexible printed circuit board for a mobile phone and a manufacturing method thereof according to the present invention, the present invention is not limited to the above-described embodiment, it is claimed in the claims As will be apparent to those skilled in the art to which the present invention pertains without departing from the gist of the present invention, the technical spirit of the present invention will be described to the extent that various modifications can be made.

As described above, the rigid flexible printed circuit board for a mobile phone and the manufacturing method thereof according to the present invention are applied to a mobile phone to secure connection reliability by removing a connector, improve electrical characteristics, and bendability to a high reliability printed circuit. A substrate can be provided.

Claims (10)

(a) providing two cross-section flexible CCLs; (b) forming an inner layer circuit on the copper foil of each of the two cross-sectional CCLs; (c) forming a flexible part by temporarily attaching and covering a coverlay on each of the substrates on which the inner layer circuits are formed; (c) stacking a prepreg formed between the two end face CCLs and an outer layer to cover a predetermined position except for the central portion of the flexible part; (e) laminating a copper foil layer on the prepreg laminated to the outer layer; And (f) forming a rigid part by forming a circuit on the laminated copper foil layer; Rigid flexible printed circuit board manufacturing method comprising a. The method of claim 1, The two-sided CCL uses a polyimide as a base film, and a rolled annealed copper as a copper foil. The method of claim 1, The forming of the flexible part may further include silver paste shielding the flexible part laminated with the coverlay. The method of claim 3, Rigid flexible printed circuit board manufacturing method comprising the step of coating the cover paste on the silver paste shield. The method of claim 1, The method of manufacturing a rigid flexible printed circuit board further comprising the step of shielding the coverlay with an EMI shield film on the flexible part. Two cross-section CCLs with inner layer circuits formed; A coverlay laminated at a predetermined position of a central portion of the cross section CCL; A prepreg laminated between the two end face CCLs and an outer layer so as to cover a portion except the center of the end face CCL; And An outer layer circuit on the stacked prepregs; Rigid flexible printed circuit board, characterized in that consisting of. The method of claim 6, The two-sided CCL is a rigid flexible printed circuit board for mobile phones, characterized in that polyimide (Polyimide) is used as the base film, and rolled annealed copper is used as the copper foil. The method of claim 6, A rigid flexible printed circuit board further comprising a silver paste shield layer stacked on the coverlay. The method of claim 8, A rigid flexible printed circuit board further comprising a cover paste coating layer laminated on the silver paste shield layer. The method of claim 6, A rigid flexible printed circuit board further comprising an EMI shield film layer stacked on the coverlay.