KR20030085211A - Method for manufacturing a flexible printed circuit board with double side - Google Patents

Abstract

PURPOSE: A method for fabricating a double side flexible PCB(Printed Circuit Board) is provided to reduce the thickness of plating layers by performing directly a copper plating process on both sides of a base film. CONSTITUTION: A base film having both sides coated with thermosetting adhesive is provided(S31). A through-hole is formed on the base film by using a drill(S32). The first plating layer is formed on both sides of the base film and the through-hole by using an electroless plating method or a direct plating method(S33). The second plating layer is formed on an upper portion of the first plating layer by using an electric copper plating method(S34). The base film and the second plating layer are pressed by using a heat press(S35). A dry film is laminated on the second plating layer(S36). A circuit is formed by performing an exposure process, a developing process, and an etching process(S37,S38). A PCB is formed by adhering a cover film thereon(S39,S40).

Description

METHODS FOR MANUFACTURING A FLEXIBLE PRINTED CIRCUIT BOARD WITH DOUBLE SIDE

The present invention relates to a method of manufacturing a printed circuit board, and in particular, in the manufacturing process of a double-sided flexible printed circuit board (Double side flexible PCB) by directly performing copper plating directly on the both sides of the base film in the absence of copper foil, The present invention relates to a method for manufacturing a flexible printed circuit board having a double-sided structure that not only reduces the thickness of copper foil but also improves productivity and product competitiveness.

Recently, with the development of electronic components and component embedding technology, multilayer printed circuit boards that overlap circuit conductors have been continuously developed, and small chips and their components are directly mounted due to the rapid development of semiconductor integrated circuits in the electronic industrial technology field. With the development of surface-mount technology, as electronic products become thin and short, it is necessary to make it easy to embed in more complex and narrow spaces, and in order to meet these demands, flexible multilayer printed circuit boards have been developed.

In particular, the flexible printed circuit board of the double-sided structure, which is easy to laminate and high in use, has rapidly increased due to the technological development of cameras, mobile phones, batteries, printers, disk drives, small measuring instruments, LCDs, PDPs, and medical devices. At the same time, technology development and demand for it are increasing.

In general, the manufacturing method of the flexible printed circuit board of the double-sided structure until now to cut the dynamic layer plate with the copper foil on both sides to make a certain size, through the drilling work using expensive NC equipment (Guide Hole) By processing and electroless plating and electroplating, we had to go through the whole process in a single sheet. However, flexible printed circuit boards are thin, so it is impossible to cope with existing double-sided printed circuit board manufacturing facilities. Difficulties, such as the need for expensive expensive equipment, low productivity, high defect rate, and the need to purchase raw materials with copper foil on both sides, have caused the price to rise.

1 is a flowchart illustrating a conventional method for manufacturing a flexible printed circuit board having a double-sided structure. Referring to FIG. 2B, first, 8 μm to 70 μm are formed on both surfaces of a base film 11 called polyimide. The flexible dynamic layered plate 10a having a double-sided structure in which copper foils 12 are stacked is cut to a required size (S1 and S2).

After processing the through hole (19; guide hole) by cutting the dynamic layer plate (10a) by cutting (S3), after removing the bar around the through hole 19 and the inside of the hole (19) (S4) The electroconductive copper plating is applied to the inside of the hole processed by electroless copper plating, followed by electrolytic copper plating to form and polish the plating layer 14 on the top of the copper foil 12 (S5, S6, and S7).

Then, a dry film for photoresist is applied to the upper end of the plating layer 14 (S8), and the copper foil 12 on which the dry film is laminated is exposed to a necessary pattern using an exposure machine, and the exposed copper foil 12 is subjected to the exposure process. Is developed with a developer, and is etched by an etching process to form a necessary circuit pattern (S9).

Subsequently, after performing the thermal bonding by the adhesion and hot press of the coverlay film 17, the manufacturing of the double-sided flexible circuit board is completed through the outer processing (S10, S11, S12).

Therefore, as described above, in the conventional method of manufacturing a flexible printed circuit board, the cost is increased by using a dynamic layer plate in which only copper foil is laminated on both sides of the base film as a raw material, and further, copper plating is applied to the upper end of the copper foil to form a plating layer in double. As a result, the entire thickness of the copper foil layer becomes thick, making it difficult to form a high density pattern, and there is a problem in that the production cost increases due to double plating and productivity decreases.

Accordingly, an object of the present invention is to manufacture a double-sided flexible printed circuit board (Double side Flexible PCB) by directly performing copper plating directly in the absence of copper foil on both sides of the base film, thereby reducing the thickness of the plating The present invention provides a method for manufacturing a flexible printed circuit board having a double-sided structure that can reduce the overall thickness.

Another object of the present invention is to directly manufacture the copper plating directly in the absence of copper foil on both sides of the base film in the manufacturing process of the flexible printed circuit board of the double-sided structure, the manufacturing process can be reduced to increase the productivity and the manufacturing cost The present invention provides a method of manufacturing a flexible printed circuit board having a double-sided structure, which can lower the product and increase product competitiveness.

1 is a flowchart illustrating a conventional method for manufacturing a flexible printed circuit board having a double-sided structure.

2A and 2B are cross-sectional views showing the structure of a printed circuit board according to the present invention and the prior art, respectively.

3 is a flowchart illustrating a manufacturing process of a flexible printed circuit board having a double-sided structure according to an embodiment of the present invention.

4 is a flowchart illustrating a manufacturing process of a flexible printed circuit board having a double-sided structure according to another embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

10: double-sided flexible printed circuit board 10a: dynamic layer board

11: base film (polyimide film) 11a: thermosetting adhesive

12: copper foil 13: 1st plating layer

14: plating layer 15: second plating layer

17: coverlay film 17a: adhesive

19: through hole

Technical method of the present invention for achieving the above object, in a method for manufacturing a flexible printed circuit board of the double-sided structure: the step of injecting a base film coated with a thermosetting adhesive on both sides; Forming a through hole in the injected base film by using a drill; Forming a first plating layer on both surfaces of the base film and through holes by electroless copper plating or direct plating; Performing a copper plating on top of the conductive layer to form a second plating layer having a required plating thickness; After copper foil is formed on both sides of the base film by pressing with a heat press to increase the adhesion between the base film and the plating layer; Laminating a dry film for photoresist on top of the second plating layer, respectively; Exposing the dry film in a stacked state, and forming a circuit through a development and etching process; And completing the circuit board by thermally bonding and enclosing the coverlay film after the circuit is formed.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

2A and 2B are cross-sectional views illustrating a structure of a printed circuit board according to the present invention and the prior art, and FIG. 3 is a flowchart illustrating a process of manufacturing a flexible printed circuit board having a double-sided structure according to an embodiment of the present invention. 4 is a flowchart illustrating a manufacturing process of a flexible printed circuit board having a double-sided structure according to another embodiment of the present invention.

Figure 2a is a cross-sectional structure of a printed circuit board completed by the present invention, it is conceptually shown ignore the circuit pattern.

As shown in FIG. 2A, the double-sided flexible circuit board includes a base film 11 formed on the center surface of the circuit board, a thermosetting adhesive 11a formed on both surfaces of the base film 11, and the adhesive 11a. A first plating layer 13 formed at an upper end, a second plating layer 15 formed at an upper end of the first plating layer 13, a coverlay film 17 formed at an upper end of the second plating layer 15, and It consists of the adhesive 17a and the through-hole 19 drilled in the board | substrate.

In contrast, the prior art completed by the process of Figure 1 is a base film 11 formed on the center surface of the circuit board as shown in Figure 2b, the thermosetting adhesive (11a) formed on both sides of the base film 11, and the adhesive Copper foil 12 formed on the upper end of 11a, the electroplating layer 14 formed on the upper end of the copper foil 12, the coverlay film 17 formed on the upper end of the said electroplating layer 14, and its adhesive agent ( 17a) and through holes 19 formed in the substrate. That is, in the present invention, the copper foil 12 is not laminated on the top of the base film 11.

In addition, the process of manufacturing the circuit board as shown in FIG. 2A will be described with reference to FIGS. 3 and 4.

3 is a method of manufacturing a printed circuit board in a single sheet.

First, the base film 11 having the thermosetting adhesive coated on both surfaces thereof is cut into sheets of a required size and then introduced into the manufacturing process of the circuit board (S21 and S22). Here, the copper foil 12 is not formed on both sides of the base film 11 unlike the conventional.

A plurality of through-holes 19 are formed at a given position by using an NC drill or UV laser drill in the base film 11 introduced above (S23).

The surface and holes of the base film 11 are plated with copper by electroless copper plating or direct plating (shadow, black hole, DMSE, etc.) process on both surfaces of the base film 11 and through holes 19. Each of the first plating layers 13 is formed in a manner of providing conductivity to each of 19 (S24).

Subsequently, electroplating is performed on the upper end of the first plating layer 13 to form a second plating layer 15 having a required thickness (S25).

As described above, the plating layers 13 and 15 are formed on the upper surfaces of both sides of the base film 11 to impart conductivity, and then press the thermal press to harden the thermosetting adhesive of the base film 11 to harden the plating layer 13 and the base film 11. Increase the adhesive strength with) (S26). Compression pressure between the plating layers 13 and 15 and the base film 11 is based on approximately 24 kg / cm ² , but is set differently according to the size of the substrate to be manufactured, and the thermal temperature of the hot press is 130 ° C. to It is preferable to set it to the temperature of 160 degreeC.

Laminate the photoresist dry film on top of the second plating layer 15, respectively, by laminating (S27), align the required circuit pattern on the top, and expose the circuit pattern to the plating layer 15 through development and etching processes. It forms a (S28).

After the circuit is formed, the circuit board may be completed by thermally bonding and enclosing the coverlay film 17 (S29 and S30).

That is, in the present invention, the base film in the semi-cured state in which the thermosetting adhesive 11a is applied to both surfaces of the base film 11 instead of the double-sided dynamic layer plate 10a having the copper foil 12 coated on both surfaces of the base film 11. (11) is prepared and cut into sheets of predetermined size.

Next, a plurality of through holes 19 are continuously formed at a given place using an NC drill or a UV laser drill. The base film 11 cut into sheets is then formed in a state where the through holes 19 are formed. The first plating layer 13 is formed in the through hole 19 and on the surface of the base film 11 by passing the base film 11 through an electroless plating or direct plating process (shadow, black hole or DMSE, etc.). And also impart conductivity.

Next, the second plating layer 15 is formed by electroplating the upper end of the base film 11 to which conductivity is imparted.

After the heat treatment at a constant temperature or hot pressing (pressing with a constant heat and pressure), the thermosetting adhesive of the base film 11 is cured to generate the necessary adhesive strength between the plating layer 13 and the base film 11.

Laminate the dry film for photoresist on both sides of the base film (11). When the pattern is exposed again using a double-sided exposure machine and then developed and etched, a flexible printed circuit board having a double-sided structure in which a through hole 19 is formed is obtained.

And, Figure 4 is another embodiment of the present invention to form a printed circuit board in a roll-to-roll method, all processes are automatically carried out in a roll-to-roll method.

First, a base film 11 in a roll state in which a thermosetting adhesive is applied to both surfaces is prepared (S31). Here, the copper foil 12 is not formed on both sides of the base film 11 unlike the conventional.

In the base film 11 introduced in the roll method, a plurality of through holes 19 are continuously formed at a given position by using an NC drill or a UV laser drill (S32).

Surfaces and through holes of both surfaces of the base film 11 are plated with copper through an electroless copper plating process or a direct plating (shadow, black hole, DMSE, etc.) process. The first plating layer 13 is formed in such a manner as to impart conductivity to each of 19 (S33).

Subsequently, an electrocopper plating is performed on the first plating layer 13 to form a second plating layer 15 having a required thickness (S34).

As described above, the plating layers 13 and 15 are formed on the upper surfaces of both sides of the base film 11 to impart conductivity, and then press the thermal press to harden the thermosetting adhesive of the base film 11 to harden the plating layer 13 and the base film 11. Increase the adhesive strength with) (S35). Compression pressure of the plating layer 13 and the base film 11 is based on about 24kg / cm ² , but is set differently depending on the size of the substrate to be manufactured, the thermal temperature of the hot press is 130 ℃ to 160 ℃ It is preferable to set it to the temperature of.

The photoresist dry film is laminated on the top of the second plating layer 15, respectively, and laminated (S36), and a circuit pattern is aligned and exposed on the top of the second plating layer 15, and then the circuit pattern is applied to the plating layer 15 through development and etching processes. It forms a (S37).

After the circuit is formed, the circuit board may be cut to a required size (S38), and then the coverlay film 17 may be completed by thermally bonding and enclosing the circuit board (S39 and S40).

That is, FIG. 3 prepares a base film 11 coated with a thermosetting adhesive in a semi-cured state on both sides in a roll-to-roll state. This is moved in a roll-to-roll manner to process a plurality of through holes 19 in a designated place continuously using a UV laser drill.

Next, the base film 11 is moved in a roll-to-roll manner and passed through an electroless copper plating or direct plating process (shadow, black hole, DMSE, etc.) to form a first plating layer on the surface of the through hole 19 and the base film 11. (13) is formed to impart conductivity.

When the copper copper plating is carried out again in a roll-to-roll manner, a rolled material in which the second plating layer 15 and the conducting through hole 19 are formed is obtained.

The film is moved to the next process by the roll-to-roll method, and the dry film is laminated, and the circuit pattern is exposed by using the double-sided roll-to-roll exposure machine, which is then developed and etched by the roll-to-roll method. It is obtained in a roll state.

In this way, all the work that can only be done by sheeting in the existing method can be done in roll-to-roll, so productivity can be dramatically improved and quality can be improved.

The present invention is to change the conventional structure and manner made as shown in Figures 1 and 2b, first to prepare a base film 11, which is coated on both sides with a thermosetting adhesive in a roll state, using an NC drill or UV laser drill machine To process the through hole 19, and electroless plating the material processed by the through hole 19 or by direct plating (such as the shadowing method, the black hole method or the DMSE method) to conduct conductivity to the through hole 19. After applying, electroplating it again to form the copper foil thickness of the required plating layer, and heat-treating or hot pressing to harden the thermosetting adhesive applied to both sides of the base film 11, the plating layer 13 and the base film 11 Sufficient adhesion can be obtained between

In addition, in the method according to the present invention, when the conventional double-sided copper foil is used, since the drilling operation for processing the through-hole 19 is not roll-to-roll, the manufacturing method of the double-sided flexible printed circuit board is rolled in the previous step. Although not rolled, the base film 11 coated with the thermosetting adhesive can easily process the through-holes 19 using roll-to-roll using a UV laser. When the material having the through holes 19 formed thereon is subjected to electroless copper plating or direct plating process in a roll-to-roll manner, the conductive holes and the surface are imparted to the through-holes 19 and the surface is electro-plated with roll-to-roll, and the roll-to-roll is formed with a plating layer The material in the state is completed.

Next, if the material is passed through a dry film laminating, roll-to-roll exposure, roll-to-roll development, and etching process in a roll-to-roll manner, it is possible to easily mass-produce a flexible printed circuit board having a rolled double-sided structure.

This method roll-to-rolls the entire process of flexible printed circuit boards of double-sided structure, which was not possible with materials laminated with copper foil on both sides, to dramatically improve productivity, improve quality, and thinner plating thickness. That is, the flexible printed circuit board of the double-sided microcircuit pattern can be easily manufactured by making the surface plating layer thin.

Therefore, in the present invention, in the manufacturing process of the double-sided flexible printed circuit board (Double side Flexible PCB) by directly performing copper plating without forming a copper foil on both sides of the base film, by reducing the thickness of the plating to reduce the overall thickness of the substrate In addition, the manufacturing process is reduced due to the simplification and automation of the process, and the productivity can be increased, and the manufacturing cost and product competitiveness can be improved.

Claims (5)

In the method of manufacturing a flexible printed circuit board of double-sided structure: Putting a base film coated with a thermosetting adhesive on both sides; Forming a through hole in the injected base film by using a drill; Forming a first plating layer on both surfaces of the base film and through holes by electroless plating or direct plating; Performing a copper plating on top of the first plating layer to form a second plating layer having a required plating thickness; Forming copper foil on both sides of the base film by plating and then pressing the sheet by pressing with a heat press to increase adhesion between the base film and the plating layer; Laminating a dry film for photoresist on top of the second plating layer, respectively; Exposing the dry film in a stacked state, and forming a circuit through a development and etching process; And Comprising a step of completing the circuit board through the heat-bonding and outer processing of the coverlay film after forming the circuit. The method according to claim 1, The flexible printed circuit board of the double-sided structure is manufactured by a roll-to-roll method. The method according to claim 1, The first plating layer is a method of manufacturing a flexible printed circuit board having a double-sided structure, characterized in that formed using any one of the electroless copper plating or direct plating method of the shadow method, black hole method or DMSE method. The method according to claim 1, In the process of forming the second plating layer, the method of manufacturing a flexible printed circuit board having a double-sided structure, characterized in that the plating by adjusting to the thickness of the required plating layer. The method according to claim 1, After the development and etching process, further comprising the step of cutting the circuit board material to a predetermined size, the method of manufacturing a flexible printed circuit board having a double-sided structure.