KR100705969B1 - A multi layer type fpcb manufacture method for terminal area height conquest - Google Patents

Abstract

The present invention relates to a manufacturing method for overcoming the terminal step difference when forming the outer layer circuit of the multi-layer flexible printed circuit board, to minimize the step generation in the terminal portion during the substrate manufacturing process to improve the dry film adhesion and exposure work efficiency in the outer layer circuit forming process It is to be made, and thereby to show an effect that the circuit failure is improved.

In the manufacturing method of the present invention for realizing this, the first layer where the outer circuit is to be formed is located at the lowermost end, and the bonding sheet for interlayer adhesion is respectively provided on the plurality of layers of the second layer or more provided on the first layer. After the mold forming step for each of the upper layer or more of the second layer or more so that the terminal portions of the first layer are exposed to each other when being laminated with each other, the hot pressing step is carried out while the entire layers are stacked to form a multilayer type. In manufacturing the flexible printed circuit board, in the mold forming step for each upper layer of the second layer or more, through holes are formed with a width D smaller than the width d of the terminal portion; The bonding sheet provided with the second layer is subjected to a separate preliminary molding step before the bonding step, wherein the molding hole is formed to have the same size as the width d of the terminal part.

FPCB, step, terminal, substrate, molding, mold

Description

Manufacturing method to overcome terminal step difference when forming outer layer circuit of multilayer flexible printed circuit board {A MULTI LAYER TYPE FPCB MANUFACTURE METHOD FOR TERMINAL AREA HEIGHT CONQUEST}

1 is a schematic view and a partially enlarged cross-sectional view of a general multilayer printed circuit board for mounting a mobile phone.

Figure 2 is an enlarged laminated sheet showing the terminal portion monolayer structure according to the prior art.

3 is a flow chart of each layer forming process according to the prior art.

4 is a flow chart of each layer forming process in accordance with the present invention.

5 is an enlarged laminated sheet of the terminal portion monolayer structure according to the present invention.

<Explanation of symbols for the main parts of the drawings>

100: laminated sheet 101: flexible printed circuit board

101a: terminal 110: FCCL 1st floor

111: copper plating layer 120: FCCL 2 layer

121: coverlay (2 layers) 122: bonding sheet (2 layers)

130: FCCL 3 layers 131: bonding sheet (3 layers)

132: Coverlay (3F) 140: FCCL 4F

141: bonding sheet (4 layers) 142: copper plating layer (4 layers)

The present invention relates to a flexible printed circuit board (FPCB), and more particularly, to overcome a circuit defect due to a step formed in a terminal part when forming an outer layer circuit of a substrate pressed into a plurality of layers in the manufacturing process of a multilayer flexible printed circuit board. It relates to a manufacturing method for.

In general, with the development of electronic components and component embedding technology, printed circuit boards overlapping circuit conductors have been continuously developed.

Recently, in the field of electronics industry, the rapid development of integrated density of semiconductor integrated circuits and the surface mount technology for directly mounting small chip components have been developed and the electronic equipments have been miniaturized. Therefore, it is necessary to facilitate the installation in more complicated and narrow spaces. In order to meet these demands, multilayer flexible printed circuit boards have been developed.

In particular, in the case of high-flexibility flexible printed circuit boards (FPCBs), demand for mobile phones, DVDs, digital cameras, and PDPs is rapidly increasing due to technological developments. It is true.

The manufacturing process according to the prior art of such a flexible printed circuit board (FPCB) will be described.

1 is a detailed view of a multi-layer flexible printed circuit board 1 mounted on a mobile phone and an enlarged cross-sectional view of a terminal part 1a, and FIG. 2 is a laminated sheet 2 having a plurality of cutouts of the substrate provided at regular intervals. And AA cross-sectional view of the terminal portion (1a) is shown, such a substrate (1) has a four-layer structure as shown in general, and the manufacturing process for each layer is shown in FIG.

The manufacturing process of the conventional multilayer substrate 1 is a one-layer process sequence (ST 1), two-layer process sequence (ST 2), three-layer process sequence (ST 3), four-layer process sequence (ST 4) as shown in FIG. After each step is carried out separately to form a laminated sheet (2) of the multi-layered structure as shown in Figure 1 by pressing the high temperature in the multi-layer hot press step in the state equipped with each layer laminated to form a layered structure as shown in FIG. By cutting out the area indicated by the dotted line shape, it is separated into individual FPCBs 1 each having a terminal portion 1a. The terminal portion 1a is bent 180 degrees after bonding to the LCD of the mobile phone in a later step.

On the other hand, unlike the first layer forming the overall planar shape in the above, in the 2, 3, 4 layer process sequence, the die cutting molding step of forming the through-holes so that the terminal portion (1a) is exposed during lamination, respectively, is carried out Since the molding is performed using a primary mold forming a molding hole of a predetermined width d (about 4 mm) for forming the terminal portion 1a, the through holes formed in the 2, 3, and 4 layers are the same 4 mm. Will form the width of.

However, as shown in FIG. 2, in the multilayered laminated sheet 2 having the partial terminal portion 1a exposed, it is possible to laminate a dry film for forming a circuit on the outer circuit, that is, the copper plating layer 11 of one layer after the hot pressing step. At this time, the step is generated at a position corresponding to the terminal portion (1a) is reduced the adhesion of the dry film.

That is, since the thicknesses of the 2, 3, and 4 layers except for the one layer of the laminated substrate are about 300 µm, the step portion corresponding to the thickness occurs in the terminal portion 1a having a width of d, and thus dry film adhesion The deterioration, of course, does not completely vacuum during the exposure operation so that the film and the substrate do not come into close contact with each other.

Accordingly, there has been a problem that a large number of defects such as circuit open, short, and slit occur in the terminal portion 1a.

The present invention has been proposed to improve the above problems in the prior art, and the circuit formation is performed by allowing the outer layer circuit forming operation to be performed in a state where the step formed in the terminal portion is minimized during the outer layer circuit forming process of the multilayer circuit board. The purpose is to be able to improve the reliability of the circuit formation according to the increase in the substrate adhesion of the dry film.

The object is that the first layer where the outer circuit is to be formed at the lowermost end is located, the bonding sheet for interlayer adhesion is attached to each of the plurality of layers or more of the second layer or more provided on the upper portion of the first layer, In the manufacturing of a multilayer flexible printed circuit board by performing a hot forming step in a state in which the entire layer is laminated after performing a cutting molding step for each of the upper layers of the second layer or more so that the terminal part of the first layer is exposed. In the cutting molding step for each upper layer of the second layer or more, the cutting molding is performed by using a secondary mold so that the through hole is formed with a width smaller than the width of the terminal portion; Bonding sheets provided on the second layer are bonded after molding using a primary mold so that through holes can be formed in the same shape as the width of the terminal portion. It can be achieved through the production method.

Hereinafter, a specific embodiment of the present invention will be described in detail with reference to FIGS. 4 and 5.

4 shows a process sequence for each layer according to the present invention, and FIG. 5 shows a plan view and an enlarged cross-sectional view of the laminated sheet 100 in a state where a multi-layer hot press operation is performed by stacking each layer in the process sequence.

First, looking at the substrate manufacturing process according to the present invention through FIG. 4, the first layer process sequence (ST1) is a laminated sheet of FCCL (Flexible Copper Clad Laminate; 110) in which the copper plating layer 111 is formed on the outside as in the prior art After cutting according to the size (100) to form a drill hole for multi-layer matching.

On the other hand, in the case of the second layer process sequence (ST2) in the step of adhering the coverlay 121 and the bonding sheet 122 after the formation of the inner layer circuit, using the primary mold after cutting molding through the press forming operation After the mold reference hole punching step, cutting of the entire second layer is performed using the secondary mold.

That is, in the above process, the bonding sheet 122 is formed with a through hole having a width d of about 4 mm that is the same as that of the terminal portion 101a by using a primary mold having a molding hole for forming a terminal portion, and the remaining two-layer FCCL 120 and The coverlay 121 is formed by using a secondary mold to form a through hole (H) with a width (D) of about 0.5 mm, which is relatively small by cutting.

And, the third layer and the fourth layer is manufactured through the same conventional circuit forming step (exposure / development / etching), coverlay bonding step, bonding sheet bonding step, etc., but the final mold cutting molding step In the through-hole (H) is formed by the cutting molding using the secondary mold used in the second layer process sequence, rather than the conventional primary mold is also a relatively small minimum width of about 0.5mm ( D) can be seen.

When the high-temperature hot press step is performed in a state in which the first, second, third, and fourth layers made in this way are sequentially stacked, the bonding sheets 122, 131, and 141 provided between the layers are melted at a high temperature, and thus adhesive strength is applied to each other. As shown in FIG. 5, a plurality of substrate forms partially exposed at the terminal portion 101a along the incision line are formed at a predetermined interval to form a multi-layered substrate 100. Will be achieved.

At this time, the enlarged cross-sectional view of the main portion shown in the BB portion in Figure 5, the second through the fourth layer is a through-hole with a fine width (D) of about 0.5mm due to the cutting molding using the secondary mold (H) is formed so that only a part of the terminal space 101a as a minimum space is exposed to the upper portion. At this time, only the lowest bonding sheet 122 which is in contact with the first layer of the material forming the second layer is Since the cutting mold is formed in the same width d as the terminal portion 101a by the primary mold, it can be seen that the corresponding portion is not formed with the lower first layer.

That is, when the laminated sheet 100 produced by the method of the present invention sees the terminal portions 101a of each part, the second, third, and fourth layers are the secondary molds among the widths D of the entire terminal portions 101a. As the difference (dD) with the part formed by the forming the remaining state, the remaining portion thus serves to support the terminal portion (101a) in the process of forming the outer layer circuit for the subsequent one layer. .

Therefore, the adhesion of dry film laminating for forming the outer layer circuit is improved, and no defects in the circuit forming step can be eliminated because no vacuum defect is generated during the exposure operation.

After the outer layer circuit formation is completed, if the cutting operation is performed along the cut line indicated by the dotted line in FIG. 5, each individual FPCB is separated from the lamination sheet 100 in the above process, and at this time, the terminal portion 101a By remaining together as much as the dD width that supports the is to be completed a circuit board having a terminal portion of the shape as shown in the partial enlarged view of FIG.

As described above, the present invention, in the manufacturing process of the multi-layer flexible printed circuit board in the mold cutting for the two or more substrate-forming layer in the terminal portion when forming a small size (about 0.5mm) smaller than the terminal portion size (about 4mm) By performing the molding, it is possible to minimize the generation of the step, thereby improving the dry film adhesiveness and the exposure work efficiency in the outer layer circuit forming process has the effect of improving the circuit failure rate.

In particular, the outer layer circuit is formed by using a primary mold for separate molding with a width of about 4 mm for the bonding sheet provided in the second layer in addition to the secondary mold used for the mold cutting molding of the second, third, and fourth layers. The site supporting the step in the post-incision process can be separated in the incision process without being bonded to the first floor.

Claims (3)

The first layer where the outer circuit is to be formed is located at the lowermost end, and a plurality of layers of the second layer or more stacked on top of the first layer are provided with bonding sheets for interlayer adhesion, respectively. After performing a cutting molding step using a press mold to the corresponding portion of each of the upper layers of the second layer or more so that the inner terminal portion is exposed, the hot pressing step is performed while the entire layers are laminated. In the process of manufacturing a multilayer flexible printed circuit board forming a circuit, In the cutting molding step for each upper layer of the second layer or more, through holes are formed to have a width D smaller than the width d of the terminal portion; The bonding sheet provided to be bonded to the second layer is subjected to a separate preliminary cutting molding step before the bonding step, wherein the through-holes in which the cutting molding is formed are formed to have the same width (d) as the width (d) of the terminal part. The manufacturing method for overcoming the terminal step difference when forming the outer layer circuit of the multi-layer flexible printed circuit board. The method according to claim 1, When the through-hole is formed with the same width (d) as the terminal portion and the through-hole is formed with a smaller width (D) than the terminal portion in the cutting molding step, primary and secondary molds having different forming holes are formed. Manufacturing method for overcoming the terminal step difference when forming the outer layer circuit of the multi-layer flexible printed circuit board characterized in that it is selectively used. The method according to claim 1, In the bonding sheet provided at the lowermost end of the second layer, the entire region corresponding to the terminal portion is cut and molded, so that the upper layer including the second layer is non-adhesive with the first layer at a portion corresponding to the terminal portion region. Manufacturing method for overcoming the terminal step difference when forming the outer layer circuit of the multi-layer flexible printed circuit board characterized in that the.

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