KR101168900B1 - Flexible print circuit board with prevention circuit interference among the layer - Google Patents

Abstract

The present invention relates to a flexible circuit board with improved interlayer circuit interference prevention to prevent signal distortion caused by interlayer circuit interference of layers constituting the flexible circuit board.

To this end, the present invention is composed of a plate (2) on the coverlay film (Polyimide) (1), a circuit composed of a copper foil (3) thereon, and composed of an insulating film (4) on the copper foil (3) A flexible circuit board having a multilayer structure in which layers are laminated; When the stacking order of one or more layers is reversed such that both sides of the coverlay film 1 are positioned, the stacking layer 5 is formed on the contact surface between the ground layer and the other layer, which is a contact surface of the insulating film 4 which is in contact with each other. Characterized in that the configuration.

According to the present invention, by designing the interlayer wiring to cross each other in the design of the flexible circuit board is shielded by the ground to remove the effect of the interlayer to provide the effect of fundamentally preventing signal distortion.

Flexible Circuit Board, FPCB, Interlayer Interference, Signal Distortion

Description

FLEXIBLE PRINT CIRCUIT BOARD WITH PREVENTION CIRCUIT INTERFERENCE AMONG THE LAYER}

1 is an exemplary schematic diagram of a flexible circuit board according to the prior art;

2 is an exemplary diagram of a multilayered flexible printed circuit board according to the prior art;

3 is a schematic view showing an arrangement of a flexible circuit board according to the present invention;

4 is an exemplary view showing an arrangement of a flexible circuit board according to the present invention.

♧ description of the symbols for the main parts of the drawing ♧

1 .... coverlay film 2 .... plate

3 .... copper foil 4 .... insulation film

The present invention relates to a flexible circuit board, and more particularly, to a flexible circuit board with improved interlayer circuit interference prevention to prevent signal distortion caused by interlayer circuit interference of layers constituting the flexible circuit board.

In general, a flexible printed circuit board (FLEXIBLE PRINTED CIRCUIT BOARD: hereinafter referred to as "FPCB") refers to a circuit board that can be bent, a substrate in which a predetermined circuit is laminated on a base film formed of a predetermined resin.

Such FPCB is a kind of electronic parts developed as electronic products are miniaturized and lightened. It is excellent in workability, strong in heat resistance, chemical resistance, and chemical resistance, and is heat resistant and is a key component of all electronic products such as cameras, computers, peripherals, and mobile communication. It is widely used in terminals, video and audio equipment, camcorders, printers, DVDs, TFT LCDs, satellite equipment, military equipment, and medical equipment.

Such FPCBs are generally classified into single-sided structure FPCB, double-sided structure FPCB, multi-layer structure FPCB, etc. according to the arrangement method and the number of sheets arranged in a film form.

In particular, in the multilayer FPCB, as shown in FIG. 1, a plate 2 is formed on a thin coverlay film 1 of 0.5 mil (0.0125 mm) or more, and a circuit is formed of copper foil 3 thereon. On the copper foil 3, a layer made of a polyimide 4 coated with a thin insulating film of 0.5 mil or more is again laminated in a group, and repeatedly stacked in a plurality of layers to form 5 or 6 layers. You'll configure Layer's FPCB.

For example, in FIG. 2A, five layers of FPCBs are illustrated, and in (b), six layers of FPCBs are illustrated. In the lower part of FIG. 2, a part of the cross section of the coverlay film 1, the plate 2, the copper foil 3, and the insulating film 4 is indicated by the reference numerals in order to show the laminated structure of each layer. .

Thus, layers are configured to handle functions such as signal, power, signal, audio, and ground.

However, since the FPCB is the outermost layer, that is, the uppermost layer and the lowermost layer must be composed of a coverlay film and used as the ground, when the layers are stacked, any one of the inner layers is adjacent to the opposite stacking order. Since the insulating film 4 forms the interface 5 in contact with each other, the copper foils 3 forming the circuit layer are arranged in close proximity, which causes a problem in that interlayer interference is severely generated.

For example, as illustrated in FIGS. 2A and 2B, in the 3 and 4 layers that process signals and audio, the insulating film 4 is in contact with each other to form an interface 5 while forming a boundary 5. This proximity is placed and interference occurs. Such interference phenomenon is maximized by ionization of molecules constituting the polyimide forming the insulating film 4 in this process because lamination, etching, and peeling are continuously performed in the process of manufacturing the FPCB.
Therefore, when such interlayer circuit interference occurs, an important signal distortion phenomenon is caused. In the example of FIG. 2, distortion between audio and signals is generated, which causes a problem of degrading product quality.

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The present invention has been made in view of the above-described problems of the prior art, and has been created to solve this problem. The outermost layer and the main layer which are used as grounds by varying the arrangement of the multilayers constituting the inner layer circuit of the flexible circuit board are used as the ground. The main object of the present invention is to provide a flexible printed circuit board which prevents the interlayer circuit interference by minimizing the interlayer circuit interference by allowing the inner layer forming the signal to be closely formed with the circuit.

In order to achieve the above technical problem, the present invention provides a plate (2) on a coverlay film (Polyimide) (1), a circuit composed of a copper foil (3) thereon, and an insulating film on the copper foil (3) A flexible circuit board having a multilayer structure, in which layers composed of (4) are laminated; When the stacking order of one or more layers is reversed so that both sides of the coverlay film 1 are positioned, a circuit is formed in which the interface 5, which is a contact surface of the insulating film 4, which is in contact with each other is formed on the contact surface of the ground layer and another layer. The technical features of the present invention are to provide a flexible circuit board with interlayer circuit interference prevented by the ground layer by removing the interlayer circuit interference generated by placing the copper foil 3 layers including each other in close proximity to each other.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment according to the present invention.

3 is a schematic view showing the arrangement of the flexible circuit board according to the present invention, Figure 4 is an exemplary view showing the arrangement of the flexible circuit board according to the present invention. In the lower part of FIG. 4, a part of the cross section of the coverlay film 1, the plate 2, the copper foil 3, and the insulating film 4 is indicated by the reference numerals in order to show the laminated structure of each layer. .

As shown in (a) of FIG. 3, the present invention has a structure in which the film layer 100 in charge of the insulation function and the circuit layer 110 in which the circuit pattern is designed are alternately stacked.

At this time, it is preferable that the film layer 100 is configured to minimize the interlayer interference in any one of the uppermost layer or the lowermost layer used as the ground by forming a boundary with each other.

In this way, the insulating film layers made of polyimide do not form an interface between the inner layers of the FPCB, that is, the layers between the uppermost layer and the lowermost layer.

That is, as shown in (b) of FIG. 3, the circuit layers 110 are naturally separated from each other in the inner layer, thereby minimizing the interference between the layers.

Here, a brief look at the manufacturing process of the FPCB is as follows.

The FPCB is usually formed by cutting the raw material to form an inner layer circuit, and then form an inner layer coverlay and then joining the first hot press.

In this state, the first drill operation is performed, and then the bonding and the outer layer base plate are welded, and in this state, the second hot press process is performed.

After the shrinkage rate is measured, the process of the second drill, copper plating, outer layer circuit formation, outer layer coverlay film welding, third hot press, gold plating and tin plating, printing, BBT, external punch, final inspection To be manufactured.

Even when such lamination, etching, plating, etc. are performed in many processes, the interlayer circuit interference is minimized because the circuit layers 110 do not form a boundary surface (see FIGS. 5, 2, and 4) at a distance from each other.

For example, in the case of the 5-layer FPCB illustrated in (a) of FIG. 4, the 5-layer FPCB is used as a 1-layer signal, a 2-layer power, a 3-layer signal, a 4-layer audio, and a 5-layer ground. The film 1, the plate 2, the copper foil 3, and the insulating layer 4 are sequentially stacked, so that only the five layers used as the ground are in contact with the insulating films 4 and the boundary surface 5 Are arranged to form

Alternatively, the reverse case may be arranged in a stack such as the insulating film 4, the copper foil 3, the plate 2, and the coverlay film 1, which are arranged by inverting the structure of FIG. For example, the case where the insulating film 4 is arranged to form a boundary surface at the ground and the uppermost layer, and (a) of FIG. 4 is a case where the insulating film 4 is arranged to form the boundary surface 5 at the ground and the lowest layer. .

Therefore, in the present invention, the signal is disposed adjacent to the ground arranged to keep the signal stable, or because the ground and the at least one coverlay film 1 form the interface 5, the adjacent layers of both layers forming the interface. When interlayer circuit interference occurs between the copper foils 3, the interlayer circuit interference is minimized by eliminating the interlayer circuit interference from which the ground layer is generated, so that signal stability can be maintained.

In addition, in the case of the six-layer FPCB illustrated in (b) of FIG. 4, the first-layer signal, the second-power, the third-signal, the fourth-audio, the fifth-signal, and the sixth-ground are used. As in the case of the five-layer FPCB described above, the six layers of the insulating film 4 forming the ground and the six layers of insulating film 4 are in contact with each other, and the six layers of the insulating film 4, which is the ground layer, and the five layers of the insulating film, which are the lowest layers ( 4) is arranged to contact and form the boundary surface (5).

 After all, in the case of the FPCB having a multi-layer structure, the insulating film 4 of the ground or the signal transmitting layer of either the uppermost layer or the lowermost layer is brought into contact with each other to form the interface 5, and the copper foil forming the circuit in the inner layer of the FPCB. Since (3) are not arranged in close proximity, even if interlayer circuit interference occurs between copper foils 3 included in both layers forming an interface due to repeated ionization factors such as laminating, etching, plating, etc. during the FPCB manufacturing process It is removed by the layers forming the ground, thereby minimizing the signal distortion caused by the interlayer circuit interference.

As described in detail above, according to the present invention, the interlayer wiring is designed to cross each other when the flexible circuit board is designed to be shielded by the ground, thereby removing the interlayer effect, thereby providing an effect of fundamentally preventing signal distortion.

Claims (1)

In a flexible printed circuit board of a multilayer structure; Multilayer in which a plate 2 is formed on a coverlay film 1, a circuit is formed of copper foil 3, and layers of insulating films 4 are laminated on the copper foil 3. In a flexible circuit board of the structure; When the stacking order of one or more layers is reversed such that both sides of the coverlay film 1 are positioned, the stacking layer 5 is formed on the contact surface between the ground layer and the other layer, which is a contact surface of the insulating film 4 in contact with each other. A flexible circuit board, wherein the interlayer circuit interference is prevented.

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