KR100752023B1 - Method for manufacturing Rigid-flexible Printed Circuit Board - Google Patents

Abstract

The present invention relates to a method of manufacturing a rigid-flexible substrate, and in particular, the circuit pattern is formed by varying the thickness of the flexible substrate portion from the thickness of the rigid substrate portion in an outer layer copper plate, thereby facilitating microcircuit implementation, and in subsequent steps. The present invention relates to a method of manufacturing a rigid-flexible substrate that prevents a defect.

According to the present invention, a polyimide film for protecting a circuit pattern is formed in a flexible substrate region of a polyimide base substrate on which a circuit pattern is formed, and a prepreg is formed in a rigid region, and then a base copper plate is laminated and partially formed. There is provided a method of manufacturing a rigid-flexible substrate by etching to form a base copper plate having a different thickness between the rigid region and the flexible region, and forming an outer layer circuit pattern in the rigid region.

Rigid-Flexible Substrates, Flying Tail Type, Partial Etching, Microcircuits

Description

Method for manufacturing rigid-flexible substrate {Method for manufacturing Rigid-flexible Printed Circuit Board}

1A to 1H are process drawings showing a method for manufacturing a rigid-flexible substrate of a conventional flying tail type.

2A to 2O are process diagrams illustrating a method of manufacturing a rigid-flexible substrate according to the present invention.

<Description of Symbols for Main Parts of Drawings>

110: polyimide copper clad laminate 110a: base substrate
111 polyimide layer 112 copper foil layer 112a inner layer circuit pattern 120 etching resist pattern

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130: polyimide film 140: prepreg

150: base copper plate 160: etching resistor
170: through hole 180: through hole 190: copper plated layer 200: outer layer copper plate 210: PSR ink

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BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a rigid-flexible substrate, and in particular, the thickness of the flexible substrate portion in the outer layer copper plate is different from the thickness of the rigid substrate portion to facilitate microcircuit implementation and also to prevent defects in subsequent processes. It relates to a method for producing a flexible substrate.

Rigid-Flex substrates are the mains and displays of hand held phones (HHPs) for mobile phones that require flexibility for dynamic bonding or three-dimensional circuits, digital still cameras (DSCs), A substrate used for a digital video camera, a digital versatile disc (DVD), a personal digital assistant (PDA), a personal computer (PC), and the like.

Such a rigid-flexible board reduces the noise generated in the connector by combining the rigid board and the flexible board structurally without additional connectors.

In addition, the rigid-flexible substrate can maximize component mountability by improving the strength of the rigid substrate portion in which the component elements are mounted, and increase the mounting density by using a laser via hole. Considering the development trend in printed circuit board technology, the transition to rigid-flex substrates, which improves the mountability and deterioration of mounting density, which are disadvantages of the existing multiplex, is expected to be accelerated. do.

Such a rigid-flexible substrate has a configuration form such as the most common rigid-flexible-rigid substrate form and a rigid-flexible substrate form (Flying Tail Type).

Hereinafter, a manufacturing process of a flying tail type rigid-flexible substrate according to the prior art will be described in detail with reference to FIGS. 1A to 1H.

Referring to FIG. 1A, a photolithography process is performed on the copper foil layer 12 of the polyimide copper clad laminate 10 including the polyimide layer 11 and the copper foil layer 12 to form an inner layer circuit pattern having a predetermined shape.

Subsequently, referring to FIG. 1B, the polyimide film 20 is processed according to the flexible substrate region in order to protect an inner circuit pattern formed on a portion of the polyimide copper clad laminate 10 from which the flexible substrate region is to be formed.

After attaching the processed polyimide film 20 to a part of the flexible substrate region having the inner layer circuit pattern formed thereon through an adhesive, polyimide film molding is performed in which the polyimide film 20 is temporarily bonded by iron by hand. do.

After the polyimide film molding is performed on the flexible substrate region using the polyimide film 20 as described above, a resistor cover 30 is formed in the remaining portion as shown in FIG. 1C.

The resistor cover 30 is used to protect the exposed inner circuit patterns from the external environment for external terminals and mounting pads. Heat resist tape or peelable ink is used. Unlike the polyimide film, the resistor cover 30 is removed when the substrate is completed. do.

Subsequently, referring to FIG. 1D, the prepreg 40 and the base copper plate 50 face each other above and below the base substrate in order to provide mechanical strength and adhesion to a portion of the polyimide copper clad laminate 10 where the rigid substrate region is to be formed. Laminated.

As described above, after the prepreg 40 and the base copper plate 50 are laminated, a rigid substrate region and a circuit pattern formed of a shape in which a circuit pattern is impregnated in the prepreg by press molding using a press are coated on the polyimide film. Forming a flexible substrate region having a predetermined shape.

Subsequently, referring to FIG. 1E, after the conductive hole 60 is formed for the conductive connection between the inner and outer layers of the substrate, the copper plating 70 is applied to the base copper plate 50 and the conductive hole 60. An outer layer circuit pattern of a shape is formed.

Here, the outer circuit pattern is formed by a predetermined photolithography process, and the plating layer of the flex ball region is also etched.

After forming the outer layer circuit pattern of a predetermined shape as described above, the resistor cover 30 is removed as shown in FIG. 1G.

In this case, referring to FIG. 1F, when the register cover is formed of the peelable ink, the peelable ink is secondarily applied to form a predetermined thickness in order to facilitate the removal of the peelable ink and then removed.

Subsequently, referring to FIG. 1H, by applying PSR ink (Photo Imageable Solder Resist Mask ink) 80 and performing surface treatment, a flexible tail region of a flying tail type in which a flexible substrate region is polyimide film-formed by a polyimide film and a resistor cover The rigid-flexible substrate was finally completed.

However, in the case of a flying tail-type rigid-flexible substrate formed by this method, since an external terminal or mounting pad is exposed to the inner layer, a resist cover is formed and removed using heat-resistant tape or peelable ink in the flexible substrate region. The process was complicated and defects occurred due to contamination by residues, resulting in a problem of increased cost and reliability.

Recently, by etching the base copper plate of the flexible substrate region when forming an outer layer circuit pattern without using a resistor cover, a process of reducing the process and cost and preventing defects caused by contamination has been studied.

However, in order to solve this problem, when using a method of not removing the copper foil of the window portion, and using a copper foil of 12㎛ or less to implement the microcircuit of the outer layer copper plate, cracks on the copper foil of the window portion in the molding and subsequent processes There was a problem that occurs cracks and bursting phenomenon.

In addition, defects such as cracks and bursting of copper foils are impregnated during the process of desmear, copper plating, circuit formation, and the like, and impurities and the treatment liquid penetrate, thereby causing problems such as defects and post-processing.

Accordingly, an object of the present invention is to provide a method of manufacturing a flying tail-type rigid-flexible substrate that facilitates the implementation of a microcircuit.

Moreover, an object of this invention is to provide the manufacturing method of the rigid-flexible substrate which has the high reliability of a process by preventing the window part copper foil from tearing.

In order to achieve the above object, the present invention comprises the steps of (a) providing a base substrate having an inner layer circuit pattern formed on at least one surface of the polyimide film; (b) forming a polyimide film on the flexible substrate region excluding the terminal portion of the inner circuit pattern; (c) forming a prepreg on the upper and lower surfaces of the base substrate corresponding to the rigid substrate region, forming an outer layer copper plate having a predetermined thickness corresponding to the rigid substrate region and the flexible substrate region on the upper surface of the prepreg, and then a rigid substrate region of the outer layer copper sheet Making a portion corresponding to the thin; And (d) forming an outer layer circuit pattern on the rigid substrate region of the outer layer copper plate, and removing a portion of the outer layer copper plate corresponding to the flexible substrate region.

Hereinafter, a method of manufacturing a flying tail type rigid-flexible substrate according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2A to 2O are process diagrams illustrating a method of manufacturing a rigid-flexible substrate according to an embodiment of the present invention.

First, as shown in FIG. 2A, a polyimide copper clad laminate 110 including a polyimide layer 111 and a copper foil layer 112 is provided.

Here, polyimide is a polymer material that is not only excellent in abrasion resistance, heat resistance, self-lubrication, creep resistance, electrical insulation, etc., but also excellent in plasma characteristics in a vacuum state, and thus suitable for working at high temperature and high pressure.

Thereafter, as illustrated in FIG. 2B, an etching resistor pattern 120 is formed on the copper foil layer 112 to form an inner circuit pattern.

Here, in order to form the etching resist pattern 120, the circuit pattern printed on the artwork film must be transferred onto the substrate. There are various methods of transferring, but the most commonly used method is a method of transferring a circuit pattern printed on an artwork film by ultraviolet light to a dry film using a photosensitive dry film.

At this time, the dry film to which the circuit pattern is transferred serves as an etching register, and when the etching process is performed using the dry film as the etching register, as shown in FIG. 2C, the etching resist pattern 120 is not formed. The copper foil layer (reference numeral 112 in FIG. 2B) in the unused region is removed to form an inner circuit pattern 112a of a predetermined shape.

As described above, after the inner circuit pattern 112a having a predetermined shape is formed, the base substrate 110a is removed by removing the etching resistor pattern 120 remaining on the inner circuit pattern 112a as shown in FIG. 2D. Complete

Thereafter, as shown in FIG. 2E, a polyimide film is used to protect a circuit pattern, excluding a terminal portion required for an external terminal and a mounting pad, from an inner circuit pattern formed on a portion where the flexible substrate region is to be formed in the base substrate 110a from an external environment. The 130 is processed in accordance with the flexible substrate region.

The polyimide film molding is performed by attaching the polyimide film 130 to an area except for the terminal portion of the flexible substrate region having the inner circuit pattern formed therebetween with an adhesive, and then temporarily joining the polyimide film with the iron by hand.

At this time, the terminal portion for the external terminal and the mounting pad in the flexible substrate region is exposed as it is without performing polyimide film molding.

As described above, after forming the polyimide film 130, as shown in FIG. 2F, the prepreg 140 is arranged at the portion where the rigid substrate regions above and below the base substrate 110a are to be formed, and the rigid is formed on the prepreg 140. The base copper plate 150 is arranged at the portion where the substrate region and the flexible substrate region are to be formed.

Here, the prepreg 140 is formed with a window corresponding to the flexible substrate region so as to be stacked only on the portion where the rigid substrate region is to be formed. In addition, the prepreg 140 is made of a semi-cured state by infiltrating the thermosetting resin into the glass fiber not only provides mechanical strength to the rigid substrate region, but also the adhesive between the base substrate 110a and the base copper plate 150 during compression Can play a role.

At this time, the base copper plate 150 is arranged on the prepreg 140 without a window so that the base copper plate 150 can be used not only as an outer layer circuit pattern of the rigid substrate region but also as a terminal portion protection plate of the flexible substrate region.

At this time, the thickness of the base copper plate which can be used is 1/2 oz (18 micrometers), 3/4 oz (25 micrometers), 1 oz (35 micrometers), etc. are possible.

Thereafter, by laminating each layer arranged in the form of the base copper plate 150, the prepreg 140, the base substrate 110a, the prepreg 140, and the base copper plate 150 using a predetermined temperature and pressure, A rigid substrate region having an inner circuit pattern 112a impregnated in the prepreg 140 and a flexible substrate region having a terminal portion having an inner circuit pattern 112a coated or exposed on the polyimide film are formed.

Thereafter, as shown in FIG. 2G, an etching resistor 160 is applied to the base copper plate 150 to partially etch the copper plate of the rigid substrate portion.

Here, in order to partially etch only the base copper plate 150 of the rigid substrate portion, the etching resist 160 of the rigid region is removed as shown in FIG. 2H.

As shown in FIG. 2I, after partially etching to a thickness of 2 μm to 12 μm to form a base copper plate 150 having a thickness different from that of the copper substrate in the rigid substrate region and the thickness of the flexible substrate region, FIG. As shown in 2j, the etching resist 160 applied over the flexible substrate region is removed.

As shown in FIG. 2K, after the respective layers are compressed, a through hole 170 is formed for the conductive connection between the inner and outer layers of the substrate.

At this time, the through hole 170 is formed by performing a CNC drilling process at a predetermined position of the rigid substrate region to form a through hole penetrating the substrate.

Thereafter, as shown in FIG. 2L, copper plating is performed on the through hole 170 and the base copper plate 150 to form a copper plating layer 190. In this case, the through hole 170 is formed on the inner plating layer 190. As a result, the through hole 180 is formed.

The copper plating layer 190 formed on the base copper plate 150 forms an outer layer copper plate 200 together with the base copper plate 150.

As described above, after the copper plating is performed to form the copper plating layer, an outer circuit pattern is formed on the outer copper plate 200 using a dry film (not shown) in FIG. 2M.

In this case, since the base copper plate 150 and the copper plating layer 190 corresponding to the flexible substrate region are finally removed in a subsequent process, the outer circuit pattern may be formed only in the rigid substrate region.

In addition, unlike the base copper plate 150 corresponding to the rigid substrate region when the outer layer pattern is formed only in the region corresponding to the rigid substrate region in the outer layer copper plate 200, the terminal portion exposed by the etching process has a thickness of 12 μm or more. Protect against

In addition, the base copper plate 150 and the copper plating layer 190 corresponding to the flexible substrate region in order to easily remove the base copper plate 150 and the copper plating layer 190 corresponding to the flexible substrate region in a subsequent process as shown in FIG. 2M. Is left about 0.05 mm to 5 mm larger than the actual flexible substrate area. In this way, the base copper plate 150 and the copper plated layer may be subjected to CNC drill or wood processing on the edge portions of the base copper plate 150 and the copper plated layer 190 corresponding to the boundary between the flexible substrate region and the rigid substrate region. 190 can be easily removed.

Thereafter, as shown in FIG. 2N, the base copper plate 150 and the copper plating layer 190 corresponding to the flexible substrate area left to protect the exposed terminal parts for the external terminal and the mounting pad are physically manufactured by using manual or automated machinery. After the removal, the protective tail is applied to the PSR ink 210 to prevent the solder bridge phenomenon between the outer circuit patterns in the soldering process while protecting the outer circuit patterns as shown in FIG. The type rigid-flexible substrate is finally completed.

As described above, according to the manufacturing method of the rigid-flexible substrate of the present invention, instead of using a method of protecting the exposed terminal portion by window etching the base copper foil of the existing flexible substrate region, the outer layer of the rigid substrate portion after forming the outer layer copper plate Partial etching of the copper plate surface has the effect of reducing the thickness of the copper foil to easily implement the microcircuit on the rigid substrate.

In addition, according to the present invention, by thickening the thickness of the copper foil of the flexible substrate portion, there is an effect of preventing the defects such as contamination caused by copper cracks in the subsequent process, damage to the circuit pattern, etc., thereby greatly increasing reliability.

Herein, the present invention described above has been described with reference to preferred embodiments, but those skilled in the art can variously modify the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. It will be appreciated that this can be changed.

Claims (4)

(a) providing a base substrate having an inner circuit pattern formed on at least one surface of a polyimide film; (b) forming a polyimide film on the flexible substrate region excluding the terminal portion of the inner circuit pattern; (c) forming a prepreg on the upper and lower surfaces of the base substrate corresponding to the rigid substrate region, forming an outer layer copper plate having a predetermined thickness corresponding to the rigid substrate region and the flexible substrate region on the upper surface of the prepreg, and then a rigid substrate region of the outer layer copper sheet Making the portion corresponding to the thinner; And (d) forming an outer layer circuit pattern on the rigid substrate region of the outer layer copper plate, and removing a portion of the outer layer copper plate corresponding to the flexible substrate region. The method of claim 1, wherein after step (c), (e) forming a through hole penetrating the base substrate, the prepreg and the outer layer copper plate; And (f) forming a plating layer in the through hole and the outer layer copper plate, wherein the through hole is a through hole and the outer layer copper plate includes a plated layer formed on a surface thereof. The method of claim 1, Step (c) is (g) forming a prepreg on the upper and lower surfaces of the base substrate corresponding to the rigid substrate region, and forming the outer layer copper plate having a predetermined thickness on the rigid substrate region and the flexible region on the upper surface of the prepreg; And (h) thinly etching a portion of the outer layer copper plate corresponding to the rigid region. The method of claim 3, wherein (H) the step; (i) applying an etching resistor to the upper surface of the outer layer copper plate; (j) removing the etching resistor applied to the upper surface of the outer layer copper plate corresponding to the rigid substrate region; And (k) partially etching the region of the outer layer copper plate corresponding to the rigid substrate.

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