CN108601198A - A printed circuit board and its manufacturing method - Google Patents

Abstract

The invention discloses a printed circuit board and a manufacturing method thereof, wherein the printed circuit board comprises: flexible line way board module, flexible shielding layer and being located the hard line way board module of flexible line way board both sides, flexible line way board module includes flexible conducting layer and is located the flexible insulation layer of flexible conducting layer both sides, wherein: the corresponding positions of the hard circuit board modules on the two sides of the flexible circuit board module comprise at least one opening; a notch is formed in the position, corresponding to the opening, of the flexible insulating layer on at least one side of the flexible circuit board module; the flexible shielding layer is arranged in the opening, covers the flexible insulating layer and is connected with the flexible conductive layer through the notch. Because the flexible circuit board module of the printed circuit board is only composed of three layers, compared with the prior art, the thickness is effectively reduced, and the application of lightening and thinning of electronic products is more facilitated, thereby solving the problems in the prior art.

Description

A printed circuit board and its manufacturing method

technical field

The invention relates to the technical field of circuit boards, in particular to a printed circuit board and a manufacturing method thereof.

Background technique

A printed circuit board (PCB) is a support for electronic components in electronic products, and is used to provide electrical connections between various electronic components. The current printed circuit boards mainly include: rigid printed circuit boards (also known as rigid circuit boards), flexible printed circuit boards (also known as flexible circuit boards) and soft-hard printed circuit boards (also known as soft-hard printed circuit boards). Among them, the rigid-flex board has received more and more attention because it has the advantages of good durability of the rigid circuit board and good flexibility of the flexible printed circuit board.

As shown in Figure 1, it is a cross-sectional schematic diagram of a common rigid-flex board, which includes a flexible circuit board module 11 and a rigid circuit board module 12 located on both sides of the flexible circuit board module, and the rigid circuit board module 12 has an opening 13 for forming at least one flexible area in the rigid-flex board. The flexible circuit board module 11 is a multi-layer structure, which consists of a first flexible insulating layer 111, a flexible conductive layer 112, a second flexible insulating layer 113, a flexible shielding layer 114 and a third flexible insulating layer 115, wherein the flexible shielding layer 115 adopts Mesh-like copper or other metals are used for signal shielding and grounding. However, the thickness of the flexible circuit board module 11 in this kind of rigid-flex board is relatively large, which is not conducive to the thinning of electronic products. Therefore, how to reduce the thickness of the flexible circuit board module is the technical problem to be solved by the present invention.

Contents of the invention

Embodiments of the present invention provide a printed circuit board and a manufacturing method thereof, so as to solve the problem of relatively large thickness of a flexible circuit board module in a rigid-flex board in the prior art.

In order to solve the problems of the technologies described above, the present invention is achieved in that:

In a first aspect, a printed circuit board is provided, comprising: a flexible circuit board module, a flexible shielding layer, and rigid circuit board modules located on both sides of the flexible circuit board, the flexible circuit board module including a flexible conductive layer and a Flexible insulating layers on both sides of the flexible conductive layer, wherein:

The corresponding positions of the rigid circuit board modules on both sides of the flexible circuit board module include at least one opening;

A gap is opened in the flexible insulating layer on at least one side of the flexible circuit board module corresponding to the position of the opening;

The flexible shielding layer is disposed on the opening, covers the flexible insulating layer and is connected to the flexible conductive layer through the gap.

In a second aspect, a method for manufacturing a printed circuit board is provided, the method comprising:

A flexible circuit board module is provided, the flexible circuit board module includes a flexible conductive layer and flexible insulating layers located on both sides of the flexible conductive layer, and there is at least one gap on the flexible insulating layer on one side;

Rigid circuit board modules are respectively prepared on both sides of the flexible circuit board module, wherein the rigid circuit board modules on both sides include openings at positions corresponding to the gaps;

A flexible shielding layer is made on the opening on the side containing the notch, and the flexible shielding layer is connected to the flexible conductive layer through the notch.

In the printed circuit board provided by the embodiment of the present invention, since the flexible circuit board module only includes three layers of the flexible conductive layer and the flexible insulating layer on both sides of the flexible conductive layer, wherein: the flexible circuit board module on both sides The corresponding position of the rigid circuit board module includes at least one opening; the flexible insulating layer on at least one side of the flexible circuit board module has a gap corresponding to the position of the opening; the flexible shielding layer is arranged on the opening and covers the flexible insulating layer And it is connected with the flexible conductive layer through the gap. Since the flexible circuit board module of the printed circuit board is only composed of three layers, and is shielded by the flexible shielding layer arranged at the opening position, compared with the prior art, the thickness of the printed circuit board can be effectively reduced, which is more conducive to The application of light and thin electronic products solves the problems in the prior art.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute improper limitations to the present invention. In the attached picture:

Fig. 1 is a schematic cross-sectional view of a printed circuit board in the prior art;

2 is a schematic cross-sectional view of a printed circuit board provided by an embodiment of the present invention;

3 is a schematic cross-sectional view of another printed circuit board provided by an embodiment of the present invention;

4 is a schematic cross-sectional view of another printed circuit board provided by an embodiment of the present invention;

5 is a schematic flow diagram of a method for manufacturing a printed circuit board provided by an embodiment of the present invention;

Fig. 6 is a process flow chart of the preparation method of the printed circuit board provided by the embodiment of the present invention;

7 is a schematic cross-sectional view of a flexible circuit board module provided by an embodiment of the present invention;

Fig. 8 is a flow chart of the preparation process of the flexible circuit board module provided by the embodiment of the present invention;

Fig. 9 is a flow chart of the manufacturing process of the rigid circuit board module provided by the embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

As mentioned above, the flexible circuit board module in the existing rigid-flex board has a multi-layer structure, as shown in FIG. 1 , including a flexible conductive layer, a flexible shielding layer and three flexible insulating layers. Since the thickness of the flexible circuit board module is relatively large, the overall thickness of the rigid-flex board is also relatively large, which is not conducive to the thinning and lightening of electronic products.

Based on this, the present invention provides a printed circuit board, which can be used to solve the problems in the prior art. As shown in Figure 2, the printed circuit board 20 includes: a flexible circuit board module 21, a flexible shielding layer 22 and rigid circuit board modules 23 located on both sides of the flexible circuit board, the flexible circuit board module 21 includes a flexible conductive layer 211 and a flexible insulating layer 212 located on both sides of the flexible conductive layer, wherein:

The corresponding positions of the rigid circuit board modules 23 on both sides of the flexible circuit board module 21 include at least one opening 24, so that a flexible area is formed at the position of the opening 24, while other positions other than the opening 24 form a rigid area; This corresponding position may mean that at a certain position of the flexible circuit board module 21 , the rigid circuit board modules 23 on both sides of the flexible circuit board module 21 are provided with openings, and the openings on both sides may also have the same size.

A notch 25 is opened at the position corresponding to the opening 24 (in the flexible area) of the flexible insulating layer 212 on at least one side of the flexible circuit board module 21;

The flexible shielding layer 22 is disposed on the opening 24 , covers the flexible insulating layer 212 and is connected to the flexible conductive layer 211 through the gap 25 .

Using the printed circuit board 20 provided by the embodiment of the present invention, the flexible circuit board module 21 is composed of a flexible conductive layer 211 and two flexible insulating layers 212, and a gap 25 is provided on one of the flexible insulating layers 212, so that the flexible The shielding layer 22 and the flexible conductive layer 211 can be connected through the gap 25, so as to achieve the functions of grounding and shielding. Since the flexible circuit board module 21 of the printed circuit board 20 is only composed of three layers, compared with the multi-layer structure of five layers in the prior art, the thickness is effectively reduced, which is more conducive to the application of thinner and lighter electronic products, thereby The problems in the prior art are solved.

In practical applications, the flexible conductive layer 211 of the flexible circuit board module 21 can be a metal conductive layer made of a conductive metal material. For example, when the conductive metal is made to have a thickness less than a certain threshold, it can be used as the flexible conductive layer 211; Layer 211 can also be made of other conductive materials, such as a conductive layer made of conductive carbon material, etc. The material used to make the flexible conductive layer can be selected according to requirements such as cost and conductivity. It should be noted that, since copper, silver, etc. have good electrical conductivity, and the manufacturing cost is relatively low, usually copper or silver can be used as the material for manufacturing the flexible conductive layer 211 . Taking copper as an example, a thin copper plate (which increases flexibility when the thickness is small) can be made into a conductive circuit by etching or other methods, so as to serve as the flexible conductive layer 211 .

The two flexible insulating layers 212 of the flexible circuit board module 21 can be made of the same material or different materials, and the ways of making them can also be the same or different. For ease of description, the flexible insulating layer 212 covered by the flexible shielding layer 22 may be referred to as the first flexible insulating layer, and the flexible insulating layer 212 on the other side may be referred to as the second flexible insulating layer. Materials are used to make the second flexible insulating layer, and the selection of specific materials can be determined according to the requirements of insulating performance, such as polyimide film (Polyimide Film, PI) with high insulating performance can be used as the material for making the second flexible insulating layer, The second flexible insulating layer made at this time is a polyimide film PI insulating layer; of course, the first flexible insulating layer can also be made of insulating organic flexible materials, and commonly used materials can also be made of polyimide film (Polyimide Film, PI), and other insulating organic flexible materials can also be used according to the needs of insulation performance.

Since the insulating organic flexible material has high flexibility and is prone to breakage after repeated bending, the first flexible insulating layer and the second flexible insulating layer are made of insulating organic flexible material, which can improve the overall bending performance. performance. In particular, polyimide film PI can be used for both the first flexible insulating layer and the second flexible insulating layer. Since polyimide film PI has excellent insulating properties, it is more suitable in some scenarios that require high insulating properties. Be applicable.

During the application of the printed circuit board 20 , the flexible shielding layer 22 can shield external interference signals, and can also be grounded through the flexible shielding layer 22 . The flexible shielding layer 22 can be a multi-layer structure, such as a double-layer structure, including an organic insulating layer and a metal layer, wherein the metal layer is connected to the flexible conductive layer 211 through the gap 25, and the organic insulating layer covers the metal layer; Of course, in practical applications, in order to enhance the shielding effect, the flexible shielding layer 22 may also add other layers in addition to the above-mentioned double-layer structure, such as adding another metal layer on top of the organic insulating layer.

In addition, the flexible conductive layer 211 at the notch 25 can also be surface-treated to form a surface layer by spraying or gold plating to activate the flexible conductive layer 211 at this part. The material for spraying or gold-plating can be fine metal particles, specifically, the metal can be Ni, Au, Ag and other metals with excellent electrical conductivity, so as to improve the activation effect.

In practical applications, when the flexible shielding layer 22 is a double-layer structure composed of an organic insulating layer and a metal layer, the specific metal used in the metal layer can be specifically Ni, copper, Ag and other metals with better conductivity; The organic insulating layer above the layer can also use insulating flexible materials with good insulating properties such as polyimide film PI. Of course, because the flexible shielding layer 22 is located in the flexible area, it may be bent frequently in practical applications. Therefore, the organic The insulating layer can also be selected from other organic insulating materials with good bending properties.

Usually, in order to facilitate the preparation of the flexible shielding layer 22, the flexible shielding film can be integrally covered on the hard area and the flexible area, and then the flexible shielding layer 22 is formed as a whole by gluing or pressing. At this time, the flexible shielding layer 22 is shown in Figure 3 As shown, both hard and flexible regions are covered. This way of forming the flexible shielding layer 22 through the shielding film as a whole has lower manufacturing cost and simpler manufacturing process. In addition, since the shielding film is usually thin, even if the shielding film is used to integrally generate the flexible shielding layer 22 in the hard area and the flexible area, the The thickness of the printed wiring board 20 is also thinner than that of the prior art, which can also solve the problems of the prior art.

It should be noted that the area of the notch 25 may be smaller than or equal to the area of the corresponding opening 24 . An optional way is that the area of the notch 25 is smaller than the area of the corresponding opening 24 , at this time, the notch 25 is formed in a partial area on the flexible insulating layer 22 of the flexible circuit board 21 in the flexible area.

For the rigid circuit board module 23 in the printed circuit board 20, it can also be a multilayer structure, such as a two-layer structure composed of a rigid insulating layer 231 and a rigid conductive layer 232, as shown in Figure 4, the rigid insulating layer 231 It is connected to the flexible insulating layer 212 on the same side; of course, the rigid circuit board module 23 can also add other layers on the basis of the above-mentioned double-layer structure, such as adding a protective layer on the rigid conductive layer 232 to protect the rigid conductive layer 232.

In addition, in order to further increase the insulation effect, the hard insulating layer 231 can be further divided into a multi-layer structure, for example, it can be divided into a two-layer structure, which are respectively the first hard insulating layer 2311 and the second hard insulating layer 2312. At this time, the rigid circuit board The module 23 is composed of a rigid conductive layer 232 , a first rigid insulating layer 2311 and a second rigid insulating layer 2312 , and the second rigid insulating layer 2312 is connected to the flexible insulating layer 212 . The first rigid insulating layer 2311 and the second rigid insulating layer 2312 can be made of different rigid insulating materials, for example, the second rigid insulating layer 2312 can be made of polypropylene board PP, and the first rigid insulating layer 2311 can be made of epoxy glass fiber board FR4 .

The present invention also provides a method for manufacturing a printed circuit board, which can be used to manufacture the above-mentioned printed circuit board 20, so it can also solve the problems in the prior art, and will not go into details here, wherein the method is implemented In the example, if there is any unclear point, you can refer to the part of the embodiment of the printed circuit board 20 provided in this application. Below in conjunction with the method flow chart of Fig. 5 and the preparation process flow chart of Fig. 6 carry out specific description, the step of this method comprises:

Step S301: providing a flexible circuit board module.

The flexible circuit board module provided here may have the same structure as the above-mentioned flexible circuit board module 21. As shown in FIG. The flexible insulating layer 212, and there is at least one gap 25 on one side of the flexible insulating layer. Here, at least one can generally be multiple, that is to say, there can be multiple gaps 25 on the flexible insulating layer on one side of the flexible circuit board module 21 . In addition, the side of the flexible circuit board module 21 mentioned here may be any one of the two sides of the flexible circuit board module 21, or may be a specified side, which is not limited here.

Same as the printed circuit board 20 provided above, the flexible insulating layer 212 on both sides of the flexible conductive layer 211 here can be made of the same or different flexible insulating materials, and the preparation materials will not be repeated here.

It should be noted that, for the provided flexible circuit board module 21 , its preparation method can also be specifically described here. The preparation process of the provided flexible circuit board module 21 can be shown in Figure 8, including the following steps:

In the first step, a flexible insulating film 212' may be provided.

In the second step, the notch 25 is made on the flexible insulating film 212 ′ by die cutting, so as to make the flexible insulating film with the notch 25 (that is, the flexible insulating layer 212 with the notch).

In the specific production process of the flexible insulating film with a gap of 25, the Prepreg or Bonding sheet mold can be used to punch the shape, and the Prepreg or Bonding sheet and the punching mold can be aligned, and the mold punching method can be used to fit the mold in the opening area. Prepreg or Bonding sheet for punching.

In the third step, after making the flexible insulating film with the notch 25, it is covered to one side of the provided flexible conductive layer 211, thereby serving as the flexible insulating layer 212, wherein the other side of the flexible conductive layer 211 is also covered There is a flexible insulating layer 212, so that the flexible circuit board module 21 is produced.

Of course, the method of covering the flexible insulating film with the notch 25 on one side of the flexible conductive layer 211 may be by gluing or pressing, and of course other methods may also be used.

For the other side of the flexible conductive layer 211 is covered with a flexible insulating layer 212, the flexible conductive layer 211 can be produced in the following manner, a metal layer is provided, one side of the metal layer is covered with a flexible insulating layer, and then etched on Conductive lines are made on the other side of the metal layer, thereby forming the flexible conductive layer 211 , where the flexible insulating layer can be attached to the metal layer by means of gluing or pressing.

Step S302: Prepare rigid circuit board modules on both sides of the provided flexible circuit board module, wherein the rigid circuit board modules on both sides include openings at positions corresponding to the notches.

The rigid circuit board module prepared here may be the same as the rigid circuit board module 23 provided in the above embodiment. The rigid circuit board modules on both sides of the flexible circuit board module 21 include openings 24 at the corresponding positions of the notch 25, so that a flexible area and a rigid area outside the flexible area can be formed at the position of the opening 24, wherein the area of the opening 24 is greater than or equal to the area of the notch 25 area, and the position range of the notch 25 all falls within the range of the corresponding opening 24.

In practical applications, there may be various ways of preparing the rigid circuit board module 23 on both sides of the provided flexible circuit board module 21, for example, the rigid circuit board module 23 may be respectively pressed on both sides of the flexible circuit board module 21 , and then make the opening 24 on the corresponding position of the rigid circuit board module 23, wherein the specific way of making the opening 24 can be to make the opening 24 on the corresponding position of the rigid circuit board module by laser or die punching.

In addition, since the rigid circuit board module 23 is usually also a multi-layer structure, the rigid circuit board modules 23 can be prepared on both sides of the provided flexible circuit board module 21 in different ways according to the specific structure.

For example, the rigid circuit board module 23 is specifically made of polypropylene board PP to make the second rigid insulating layer 231″, and the first rigid insulating layer 2311 is made of epoxy glass fiber board FR4. At this time, the flexible circuit board module 21 is prepared For the rigid circuit board module, the opening 24 can be made from the polypropylene plate PP by die stamping, etc., and then the polypropylene plate PP with the opening 24 can be pressed onto the flexible circuit board module 21 as the second rigid circuit board module. Insulating layer 2312; then laminate epoxy glass fiber board FR4 and rigid conductive plate 232' layer by layer, after laminating epoxy glass fiber board FR4 and rigid conductive board, use laser or mold punching, etc., on epoxy glass fiber board FR4 And the opening 24 is made on the rigid conductive plate, respectively as the first rigid insulating layer 2311 and the rigid conductive layer 232. As shown in Figure 9, it is a schematic flow chart of the preparation process, wherein the rigid conductive plate 232' can be specifically a copper plate, the first The preparation material used for the first rigid insulating layer 2311 is epoxy glass fiber board FR4, and the preparation material used for the second rigid insulating layer 2312 is polypropylene board PP.

Step S303: making a flexible shielding layer on the opening on the side containing the notch, and connecting the flexible shielding layer to the flexible conductive layer through the notch.

In practical applications, there are various preparation methods according to the structure of the flexible shielding layer 22. For example, when the flexible shielding layer 22 only covers the opening 24 on one side of the notch 25, the material of the flexible shielding layer can be made into the opening 24. matching small pieces, and then cover the small piece on the opening 24 including the notch 25 by pressing. The printed circuit board manufactured in this way is relatively thin because the rigid area does not include the flexible shielding layer 22 , but the manufacturing process is relatively complicated, and it can be used in scenarios with high requirements for lightness and thinness. Of course, other ways can also be used to make the flexible shielding layer in the flexible area on one side of the notch 25, which is not limited here.

When the flexible shielding layer covers the flexible area and the hard area on the side of the notch 25 , the flexible shielding layer 22 can be made by directly gluing or pressing the flexible shielding film on the side of the notch 25 . Compared with the flexible shielding layer 22, the printed circuit board prepared in this way is thicker when it only covers the hard area on one side of the gap 25. Since the overall thickness of the flexible shielding film is relatively thin, it can also The overall thickness is reduced, and the preparation method through integral pressing of the flexible shielding film has simple process and low production cost. Therefore, in practical applications, a specific manufacturing method can be selected according to requirements such as manufacturing cost and thickness.

It should be noted that, before making the flexible shielding layer in step S303, the method may also include surface treatment of the flexible conductive layer at the position of the notch 25, specifically, the flexible conductive layer at the position of the notch 25 by spraying or gold plating. A surface layer is formed on the conductive layer, thereby activating the part of the flexible conductive layer. The material for spraying or gold-plating can be fine metal particles, specifically, the metal can be Ni, Au, Ag and other metals with excellent electrical conductivity, so as to further improve the activation effect.

By adopting the manufacturing method of the printed circuit board provided in the embodiment of the present application, the flexible circuit board module of the printed circuit board produced only includes a flexible conductive layer and flexible insulating layers located on both sides of the flexible conductive layer, and the flexible shielding The layer is disposed in the flexible area and is connected to the flexible conductive layer through the gap 25 in the flexible area. Since the flexible circuit board module has only 3 layers, it is thinner than the prior art, and the final printed circuit board is also thinner, which can be adapted to the application of light and thin electronic products and solves the problems in the prior art .

It should be noted that, in this document, the term "comprising", "comprising" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article or apparatus comprising a set of elements includes not only those elements, It also includes other elements not expressly listed, or elements inherent in the process, method, article, or device. Without further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus comprising that element.

Through the description of the above embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus a necessary general-purpose hardware platform, and of course also by hardware, but in many cases the former is better implementation. Based on such an understanding, the essence of the technical solution of the present invention or the part that contributes to the prior art can be embodied in the form of software products, and the computer software products are stored in a storage medium (such as ROM/RAM, disk, CD) contains several instructions to make a terminal (which may be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) execute the methods described in various embodiments of the present invention.

Embodiments of the present invention have been described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementations, and the above-mentioned specific implementations are only illustrative, rather than restrictive, and those of ordinary skill in the art will Under the enlightenment of the present invention, without departing from the gist of the present invention and the protection scope of the claims, many forms can also be made, all of which belong to the protection of the present invention.

Claims (10)

1. A printed circuit board, characterized in that it comprises: a flexible circuit board module, a flexible shielding layer and rigid circuit board modules positioned on both sides of the flexible circuit board, the flexible circuit board module comprising a flexible conductive layer and a Flexible insulating layers on both sides of the flexible conductive layer, wherein: The corresponding positions of the rigid circuit board modules on both sides of the flexible circuit board module include at least one opening; A gap is opened in the flexible insulating layer on at least one side of the flexible circuit board module corresponding to the position of the opening; The flexible shielding layer is disposed on the opening, covers the flexible insulating layer and is connected to the flexible conductive layer through the gap. 2. The printed circuit board according to claim 1, wherein the flexible shielding layer specifically comprises: an organic insulating layer and a metal layer, and the metal layer is connected to the flexible conductive layer through the gap. 3. The printed circuit board according to claim 1, wherein the flexible shielding layer also covers the rigid circuit board module on the same side. 4. The printed circuit board according to claim 1, wherein the area of the opening is larger than the area of the notch. 5. The printed circuit board as claimed in claim 1, characterized in that, The flexible insulating layer is specifically: a polyimide film PI insulating layer; The flexible conductive layer is specifically: a copper flexible conductive layer; The rigid circuit board module includes: a rigid insulating layer and a rigid conductive layer, wherein the rigid insulating layer is connected to the flexible insulating layer on the same side. 6. A method for manufacturing a printed circuit board, comprising: A flexible circuit board module is provided, the flexible circuit board module includes a flexible conductive layer and flexible insulating layers located on both sides of the flexible conductive layer, and there is at least one gap on the flexible insulating layer on one side; Rigid circuit board modules are respectively prepared on both sides of the flexible circuit board module, wherein the rigid circuit board modules on both sides include openings at positions corresponding to the gaps; A flexible shielding layer is made on the opening on the side containing the notch, and the flexible shielding layer is connected to the flexible conductive layer through the notch. 7. The method according to claim 6, wherein making a flexible shielding layer on the opening on one side of the notch includes: The flexible shielding layer is made by gluing or pressing a flexible shielding film over the opening. 8. The method according to claim 6, wherein the provided flexible circuit board module is made by the following method: providing a flexible insulating film; making at least one notch in the flexible insulating film by die cutting; Covering one side of the provided flexible conductive layer with the notched flexible insulating film, wherein the other side of the flexible conductive layer is covered with a flexible insulating layer. 9. The method according to claim 8, wherein the provided flexible conductive layer is made by the following method: providing a metal layer covered on one side with a flexible insulating layer; Conductive lines are made on the metal layer by etching. 10 . The method according to claim 6 , further comprising: performing surface treatment on the flexible conductive layer at the position of the notch before making the flexible shielding layer on the opening including the side of the notch. 11 .