KR100751471B1 - Method for making window-open part of flexible printed circuit board - Google Patents

Abstract

The present invention relates to a method of forming a window opening of a coverlay film that is thermally bonded to a copper foil layer on which a circuit is formed, and sets cam data to a control unit of a PC by inputting arbitrary window open coordinates using a key input unit of a PC. Storing; Converting the cam data into laser drill data so that the laser drill recognizes the cam data in accordance with a data conversion program preset in the controller of the PC; Setting a drill condition corresponding to a characteristic of the coverlay film to an input and a control unit of the PC using a key input unit of the PC; Processing the window opening of the coverlay film at a position corresponding to the laser drill data; Forming through-holes and via-holes in a multi-layer section of the flexible printed circuit board using a drill or a laser; Plating the through-holes and via-holes with electroless plating and electroplating to form a plating layer; Stacking the coverlay film and the copper foil layer on which the window opening is processed, and then compressing the coverlay film with a hot press to form a flexible printed circuit board; And performing plating on the outer layer copper foil layer exposed by the window opening portion, thereby forming a precise circular and square shape window opening portion, and being restricted from workability or positional matching in a drill using a wooden die or a bit. As the processability and positional accuracy are high, the user can change only the window open coordinates desired by the user through the key input unit, thus reducing the manufacturing cost because many tools such as molds and dies are not needed.

Description

Method for making window-open part of flexible printed circuit board

1 is a configuration diagram of a flexible printed circuit board according to the present invention;

2 is a process diagram of a flexible printed circuit board according to the present invention;

Figure 3 is a window opening portion forming process of the coverlay film according to the present invention,

Figure 4a is a plan view of the window opening of the coverlay film according to the invention,

4b is cam data of the window open coordinates according to the present invention;

4C is laser drill data of transformed window opening coordinates according to the present invention;

5A to 5D are plan views of window openings formed by different methods.

* Description of the symbols for the main parts of the drawings *

10: base film layer 20: copper foil layer

30: coverlay film layer 40: plating layer

50: open window

The present invention relates to a method of forming a window open portion of a flexible printed circuit board, and more particularly, to a method of forming a window open portion of a flexible printed circuit, which forms a window open portion of a coverlay film at a predetermined window open coordinate on a PC with a laser drill. It is about.

In recent years, due to the development of electronic components and component embedding technology and the miniaturization and thinning of electronic products, the demand for multilayer flexible printed circuit boards is continuously growing, and the rapid development of the integrated density of semiconductor integrated circuits enables the development of small chips and their components. BACKGROUND OF THE INVENTION With the development of surface mount technology to be mounted, the demand for multilayer flexible printed circuit boards that can be easily embedded in more complicated and narrow spaces continues to increase.

In particular, in the case of a flexible printed circuit board having a multi-layer or double-sided structure, which is easy to increase the density of circuits and has a high degree of use, as the usage of the camera, a mobile phone, a printer, a liquid crystal display, and a PDP increases, the usage increases rapidly. The demand for technological development of the manufacturing technology is increasing.

After cutting the polyimide base film and the copper foil to the user's required size, apply a dry film on the top of the copper foil, and expose the necessary circuit pattern by using an exposure machine on the copper foil laminated dry film, and the exposed copper foil It is developed with a developing solution, and is etched by an etching process to form a necessary circuit pattern, and then a coverlay film is bonded.

After laminating each copper foil layer to which the coverlay film is bonded using the bonding sheet as described above, through hole or blind via hole is formed by using an NC drill, and electroless plating and electroplating processes are performed. After forming the plating layer in the through-hole and the copper foil layer through the electrical connection between the necessary layers to produce a multilayer flexible printed circuit board by bonding the coverlay film on the upper side of the copper foil layer.

After completing such various processes, a window open part is formed in the outermost adhesive layer PSR of the flexible printed circuit board and plated on the window open part. In order to prevent abrasion of the plating formed on the window opening, the tape is attached with tape to perform a post-process. At this time, as the window opening is formed on the outer flexible printed circuit board late, the external eccentricity is adjusted in the previous process. Tolerance management is difficult, there was a problem that the work efficiency falls.

In addition, the window opening formed in the coverlay film is formed by a drill bit or a die or mold. The window opening formed by the drill bit generates foreign matters when machining a circle, and the window opening of the square cannot be processed. And unreliable in positional accuracy, the rectangular window openings formed by the wood pattern are bad due to the positional tolerances, and the circular window openings can be machined, which is also unreliable in machinability and positional accuracy. The circular and rectangular window openings formed by the pattern) have high reliability in processability and positional accuracy, but there are problems in that a lot of manufacturing costs are required as many tools are required depending on the shape.

The present invention was created in view of the above conditions, and an object of the present invention is to form a window opening of any shape desired by a user by forming a window opening in a coverlay film with a laser drill, Provided is a method of forming a window open of a flexible printed circuit board which is easy to form a window open part.

Still another object of the present invention is to form a window opening in the coverlay film with a laser drill, so that only the window open coordinate value is changed when the shape of the window opening is changed. It does not need to provide a method for forming a window open of a flexible printed circuit board that can significantly reduce the cost.

In order to achieve the above object, the technical method according to the present invention is a method of forming a window opening of a coverlay film that is thermally bonded to a copper foil layer on which a circuit is formed. Setting and storing cam data in a control unit of a PC by inputting coordinates; Converting the cam data into laser drill data so that the laser drill recognizes the cam data in accordance with a data conversion program preset in the controller of the PC; Setting a drill condition corresponding to a characteristic of the coverlay film to an input and a control unit of the PC using a key input unit of the PC; Processing the window opening of the coverlay film at a position corresponding to the laser drill data; Forming through-holes and via-holes in a multi-layer section of the flexible printed circuit board using a drill or a laser; Plating the through-holes and via-holes with electroless plating and electroplating to form a plating layer; Stacking the coverlay film and the copper foil layer on which the window opening is processed, and then compressing the coverlay film by hot pressing to form a flexible printed circuit board; And performing plating on the outer layer copper foil layer exposed by the window opening.

According to the present invention, by forming the window opening in the coverlay film with a laser drill, it is possible to form a precise circular and rectangular window opening, and is not subject to the processability or positional alignment in the drill using a wooden die or a bit, The location accuracy is high, and the user can change only the window open coordinates that the user wants through the key input unit, so that many tools such as molds and dies are not needed, and the manufacturing cost can be greatly reduced.

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

1 is a cross-sectional view illustrating a configuration of a flexible printed circuit board according to the present invention, and FIG. 2 is a flowchart illustrating a process sequence of the flexible printed circuit board according to the present invention. It consists of the film layer 10, the copper foil layer 20, the coverlay film layer 30, the plating layer 40, and the window opening part 50. As shown in FIG.

That is, the base film 10 made of an insulating material such as polyimide (PI), and the copper foil layer 20 adhered to one side of the base film (PI) by heat, and the adhesive copper foil layer has a specific portion. Is removed by etching to form a circuit pattern desired by the user.

That is, the coverlay film 30 is to protect the circuit pattern formed on the copper-clad laminate. The coverlay film is formed on the upper surface of the copper foil except for each end of the circuit, that is, the portion where the window opening is to be formed. Heat-bonded through the press, the outer layer of the copper foil layer is exposed to the outside through the portion in which the window opening is formed, and the exposed portion of the copper foil layer 20 constituting the circuit on the upper side of the base film layer 10 has a predetermined area. By forming a plated terminal structure, the parts come into contact with each other in correspondence with a specific device, thereby making a connection for conducting an electrical signal.

In addition, the window opening 50 of the coverlay film is processed by a laser drill, and the coverlay film layer 30 is laminated on a main region where an etched circuit pattern is formed to form an insulating layer. Used to protect and insulate exposed surfaces. Heat adhesiveness, electrical insulation, flame retardancy, flex resistance and flow of the adhesive is uniform, so it can be applied to microcircuits.

A process of manufacturing a flexible printed circuit board (Flexible Printed Circuit Board) through the same process as shown in FIG. 2 will be described in detail below. In addition, the detailed manufacturing process may vary depending on the use of the flexible printed circuit board or the circuit pattern.

First, after cutting the polyimide base film and the copper foil to the user's desired size (S1), apply a dry film on top of the copper foil, and expose the necessary circuit pattern by using an exposure machine on the copper foil laminated with the dry film. The exposed copper foil is developed with a developer, etched by an etching process to form a necessary circuit pattern, and then a coverlay film is bonded.

After laminating each copper foil layer to which the coverlay film is bonded using the bonding sheet as described above, through-holes and via-holes are selectively formed in necessary areas by using a drill or a laser in the multilayer section of the flexible printed circuit board laminated in multiple layers. S2).

Subsequently, the plated layer is formed by plating the through-holes and via-holes of the above-described flexible printed circuit board through electroless copper plating and electrolytic copper plating.

In addition, electroless (ie electroless) copper plating is referred to as chemical or catalytic plating, and is a metal deposition method. It is a chemical oxidation / reduction reaction that coats metal ions on the surface of a non-conductor. Coated phosphor gives conductivity. Copper thickness to be plated is 0.5 to 1.0㎛ and the catalyst used is generally lead (Pd).

In addition, electrolytic copper plating is a process of selectively secondary plating copper having a thickness specified on the circuit pattern and the inner wall of the hole by using the electroprecipitation method to suit the electrical characteristic capacity according to the user's arbitrary. Is determined.

The dry film which is a photosensitive etching resist is apply | coated to the upper surface of copper foil (S4), and a necessary circuit pattern is exposed using the exposure machine on the copper foil with which the dry film was laminated. This exposed copper foil is developed with a developing solution, and is etched (S5) by an etching step to form a circuit pattern.

In this case, the coverlay film 30 is thermally bonded to the upper side of the copper foil layer 20 on which the circuit pattern is formed. That is, after processing the user-opened window opening portion in the coverlay film using a laser drill (S6), and positioned one surface of the coverlay film pre-formed window opening portion on the upper surface of the copper foil, that is, coverlay except the window open portion One surface of the film 30 is heat-bonded (S7) with the copper foil layer using a hot press of high temperature and high pressure.

In addition, the temperature of the hot press is preferably about 170 ℃ or pressurized under the conditions recommended by the coverlay manufacturer, except for the portion that requires soldering on the printed circuit board, that is, the coverlay film 30 formed with the window opening 50 ) Is laminated with the copper foil layer 20 to which the base film 10 is adhered and thermally bonded using a hot press.

In the above, the plating layer 50 is formed by performing plating (S8) on the copper foil layer exposed by the window opening formed in the above (S8).

The process of forming the window opening of the coverlay film will be described in detail with reference to FIG. 3 as follows.

The method of forming the window opening portion 50 of the coverlay film layer 30 which is thermally bonded to the flexible printed circuit board on which the circuit pattern is formed is first performed by a PC which instructs and controls the circuit formation and plating of the flexible printed circuit board. By inputting coordinates of a plurality of window openings to be formed on a specific flexible printed circuit board to a controller (not shown) using a key input unit (not shown), cam data which is a plurality of window opening coordinates is set (S61). In addition, the set cam data is stored in a control unit or a memory (not shown) of the PC.

Thereafter, when the user's window open part formation instruction command signal is input through the key input unit, the cam drill stored in the PC control unit or the memory is loaded to correspond to the data conversion program preset in the control unit. The converted laser drill data is stored after being converted into recognizable laser drill data (S62).

4A is a plan view of a coverlay film in which a processing position of a window opening is set, and FIG. 4B is cam data set by inputting coordinates of a window opening into a PC corresponding to a position of the window opening on a coverlay film to be formed, 4C is laser drill data converted by a conversion program preset in a PC so that the laser drill can recognize the set cam data, and detailed description of the data converted by this program will be omitted.

In addition, the laser drill conditions according to the characteristics of the coverlay film corresponding to the type of coverlay film to be thermally bonded to the flexible printed circuit board to form a window opening in accordance with the characteristics corresponding to the type of coverlay film Input via the unit to set (S63) and store in the PC.

Thereafter, the window opening 50 is formed by machining (S64) a laser drill at a position corresponding to the laser drill data converted and stored in the PC, that is, the position of the window opening to be formed in the coverlay film.

When the plurality of window openings are formed through a laser drill, the window open points of the processed coverlay film are matched (S65) and laminated with a copper foil having a circuit to be thermocompressed (S7) with a hot press of high temperature and high pressure.

By forming the window opening 50 in the coverlay film layer 30 with a laser drill as described above, it is possible to form a precise circular, rectangular window opening, and also has high processability and position accuracy, and through the key input unit You only need to change the window open coordinates you want, so you don't need many tools such as molds and dies, which can greatly reduce your manufacturing costs.

The result can be seen in the plan view of the window openings formed by the different methods shown in FIGS. 5A to 5D.

Figure 5a is a window opening of the coverlay film formed by a laser drill, Figure 5b is a window opening of the coverlay film formed by a drill (bit), Figure 5c is a window of the coverlay film formed by a wooden die 5D is a view of the window cover of the coverlay film formed by a mold attached to the picture, the window opening of the coverlay film formed by laser drilling according to the present invention of the coverlay film formed by other methods It shows that the circular and rectangular shapes are more precise than the window openings.

The present invention is not limited to the above-described embodiments, and various changes can be made by those skilled in the art without departing from the gist of the present invention as claimed in the following claims.

As described in detail above, by forming a window opening in the coverlay film with a laser drill, it is possible to form a precise circular and square window opening, and is not limited to workability or positional alignment in a drill using a wooden die or a bit. As the processability and position accuracy are high, and only the window open coordinates desired by the user are changed through the key input unit, many tools such as molds and dies are not required, which greatly reduces the manufacturing cost.

In addition, foreign matter does not occur when machining the circular shape as in the drill bit, and the position tolerance does not occur when forming the rectangular window opening, as in the wooden die, it is possible to increase the reliability of the window opening.

Claims (2)

In the method of forming the window opening part of the coverlay film heat-bonded with the copper foil layer in which the circuit was formed, Setting and storing cam data in a control unit of a PC by inputting arbitrary window open coordinates of a user by using a key input unit of the PC; Converting cam data into laser drill data so that the laser drill recognizes the cam data in accordance with a data conversion program preset in the control unit of the PC; Inputting and setting a drill condition corresponding to a characteristic of the coverlay film to a control unit of the PC using a key input unit of the PC; Machining the window opening of the coverlay film at a position corresponding to the laser drill data; Forming through-holes and via-holes in a multi-layer section of the flexible printed circuit board using a drill or a laser; Forming a plating layer by plating the through holes and the via holes with electroless plating and electroplating; Forming a flexible printed circuit board by laminating the coverlay film and the copper foil layer on which the window opening is processed, and then pressing them by hot pressing; And Plating the outer copper foil layer exposed by the window opening; and forming a window opening of the flexible printed circuit board. delete

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