TWI558285B - Flexible circuit board, method for making the same, and electronic device having the same - Google Patents

Description

Flexible circuit board, manufacturing method thereof, and electronic device

The present invention relates to a flexible circuit board and a method of fabricating the same, and an electronic device having the same.

In the past, electronic components of printed circuit boards (PCBs), such as inductors, capacitors, or resistors, were typically formed directly on the surface of the PCB. Under the trend of thin, high-frequency, and multi-functional electronic products, such electronic components are usually buried in PCBs during the manufacturing process of PCBs. The technology of embedded electronic components in PCBs has become more and more widely used in electronic products due to the miniaturization and thinning of electronic products and the advantages in improving signal transmission performance.

However, the traditional PCB embedding technology directly embeds the electronic components in the PCB. The overall thickness of the PCB is still limited by the thickness of the embedded electronic components, and it is difficult to truly achieve the purpose of lightness and shortness of the electronic products.

In view of the above, it is necessary to provide a method of fabricating a flexible circuit board that can effectively reduce the thickness of a flexible circuit board.

In addition, a flexible circuit board prepared by the above method and an electronic device using the flexible circuit board are provided.

A method for fabricating a flexible circuit board, comprising the steps of: providing a substrate comprising a flexible base layer and a first copper layer and a second copper layer respectively formed on opposite surfaces of the base layer; At least one receiving hole is formed in the stacking direction of the first copper layer, the base layer and the second copper layer, the receiving hole extends through at least the first copper layer and the base layer, and the receiving hole comprises at least one open end; filling a dielectric material Filling the accommodating hole; etching the first copper layer and the second copper layer to form the first conductive circuit layer and the second conductive circuit layer respectively; and forming a surface on the surface corresponding to each open end of the dielectric material a conductive layer electrically connected to the first conductive circuit layer or the second conductive circuit layer, a conductive layer electrically connected to the first conductive circuit layer, a region corresponding to the dielectric material forming a first electrode, and the dielectric material is away from the first A conductive layer on the electrode or a region of the second conductive wiring layer corresponding to the dielectric material forms a second electrode, and the first electrode, the dielectric material and the second electrode form a capacitor.

A flexible circuit board comprising a flexible base layer and a first conductive circuit layer and a second conductive circuit layer formed on opposite surfaces of the base layer, the flexible circuit board along the first conductive circuit layer, the base layer and the second At least one accommodating hole is formed in the stacking direction of the conductive circuit layer, the accommodating hole extends through at least the first conductive circuit layer and the base layer, and the accommodating hole includes at least one open end, and the accommodating hole is filled with a dielectric material Forming a conductive layer electrically connected to the first conductive circuit layer or the second conductive circuit layer on a surface corresponding to each open end of the dielectric material, and a conductive layer electrically connected to the first conductive circuit layer corresponds to a dielectric material a region forming a first electrode, a region on the conductive layer or the second conductive circuit layer of the dielectric material facing the first electrode corresponding to the dielectric material forming a second electrode, the first electrode, the dielectric material and the second The electrode forms a capacitor.

An electronic device comprising a flexible circuit board as described above.

In the process of preparing the flexible circuit board, the invention directly forms a capacitor required inside the flexible circuit board, instead of embedding the existing capacitor therein, thereby avoiding an increase in thickness of the flexible circuit board due to excessive volume of the buried capacitor. The situation, thereby reducing the thickness of the flexible circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing a substrate used for fabricating a flexible circuit board according to a first embodiment of the present invention.

2 is a cross-sectional view showing a through hole and a receiving hole formed in the substrate shown in FIG. 1.

FIG. 3 is a cross-sectional view showing the dielectric material filled in the accommodating hole shown in FIG.

Fig. 4 is a schematic cross-sectional view showing the formation of a plating layer on the wall of the through hole of Fig. 3.

FIG. 5 is a cross-sectional view showing the first conductive wiring layer and the second conductive wiring layer formed in the first copper layer and the second copper layer shown in FIG. 4, respectively.

6 is a schematic cross-sectional view showing the formation of a conductive ink layer on the surface of the dielectric material shown in FIG. 5 adjacent to the first conductive wiring layer.

Figure 7 is a schematic cross-sectional view showing the formation of a metal layer on the conductive ink layer shown in Figure 6.

FIG. 8 is a cross-sectional view showing the flexible circuit board obtained after the surface of the first conductive wiring layer and the second conductive wiring layer shown in FIG. 7 is covered with a protective layer.

Figure 9 is a cross-sectional view showing a flexible circuit board in accordance with a second embodiment of the present invention.

Figure 10 is a cross-sectional view showing a flexible circuit board in accordance with a third embodiment of the present invention.

Figure 11 is a partial cross-sectional view showing the flexible circuit board shown in Figure 8 at another angle.

FIG. 12 is a schematic diagram of an electronic device according to an embodiment of the present invention.

The manufacturing method of the flexible circuit board 100 of the first embodiment of the present invention includes the following steps:

Step S1, referring to FIG. 1, a substrate 10 is provided. The substrate 10 includes a flexible base layer 11 and a first copper layer 13 and a second copper layer 15 respectively formed on the opposite surfaces 11a, 11b of the base layer 11. The material of the base layer 11 is polyimine (PI) or polyethylene terephthalate (PET) formed of a dielectric material.

Step S2, referring to FIG. 2, at least one through hole 16 and at least one receiving hole 18 are formed in the stacking direction of the first copper layer 13, the base layer 11 and the second copper layer 15 on the substrate 10. The through hole 16 penetrates through the first copper layer 13 , the base layer 11 , and the second copper layer 15 . The receiving hole 18 is a blind hole penetrating the first copper layer 13 and the base layer 11 . The receiving hole 18 includes an open end 181.

Step S3, referring to FIG. 3, a dielectric material 20 is provided and filled in the receiving hole 18 and substantially flush with the outer surface of the first copper layer 13. Preferably, the dielectric material 20 is a material having a high dielectric constant, such as a ceramic powder.

Step S4, referring to FIG. 4, a plating layer 17 is formed on the hole wall of the through hole 16 by electroplating, thereby obtaining a conductive hole 30 for electrically connecting the first copper layer 13 and the second copper layer 15. . In this embodiment, the material of the plating layer 17 is copper. It will be appreciated that the material of the plating layer 17 may also be selected from other conductive materials.

Step S5, referring to FIG. 5, the first copper layer 13 is etched to form a first conductive wiring layer 130, and the second copper layer 15 is etched to form a second conductive wiring layer 150.

Step S6, referring to FIG. 6 and FIG. 7, a conductive layer 40 electrically connected to the first conductive wiring layer 130 is formed on the surface of the dielectric material 20 adjacent to the first conductive wiring layer 130. The first electrode 131 and the second electrode 151 are respectively formed on the conductive layer 40 corresponding to the region of the dielectric material 20 and the region corresponding to the dielectric material 20 of the second conductive circuit layer 150. The electrical material 20 and the second electrode 151 cooperate to form a capacitor 50.

The conductive layer 40 completely covers the dielectric material 20. Preferably, the coverage area of the conductive layer 40 is larger than the area of the surface of the dielectric material 20 adjacent to the first conductive circuit layer 130, so that the dielectric material 20 cannot be completely covered due to the positioning deviation of the conductive layer 40. The situation has improved the yield of the product. More specifically, the difference between the distance from the edge of the conductive layer 40 to the center of the receiving hole 18 and the distance from the open end 181 in the same direction to the center of the receiving hole 18 is less than 50 μm, when the edge of the conductive layer 40 The difference in the distance from the center of the accommodating hole 18 to the distance from the open end 181 in the same direction to the center of the accommodating hole 18 is more than 50 μm, which tends to cause a decrease in the capacitance of the capacitor 50. In this embodiment, the conductive layer 40 includes a conductive ink layer 41 and a metal layer 42. The conductive ink layer 41 can be directly formed on the dielectric material 20 by coating. The metal layer 42 can be formed on the conductive ink layer 41 by sputtering or electroplating, and the conductive ink layer 41 can be coated.

Step S7, referring to FIG. 8, the surface of the first conductive circuit layer 130, the second conductive circuit layer 150, and the conductive layer 40 is covered with a protective layer 60, and the protective layer 60 is filled in the conductive hole 30, and the first A gap between the conductive wiring layer 130 and the second conductive wiring layer 150 and the base layer 11 is obtained to obtain the flexible circuit board 100. In the embodiment, the protective layer 60 includes an insulating layer 61 and a protective layer 63. The insulating layer 60 covers the surfaces of the first conductive circuit layer 130, the second conductive circuit layer 150 and the conductive layer 40, and is filled in the conductive hole 30, and the first conductive circuit layer 130 and the capacitor second conductive circuit layer 150. A gap with the base layer 11. The material of the insulating layer 61 is selected from an insulating material having flexibility. Preferably, the insulating material is a resin such as an epoxy resin. Specifically, the insulating layer 61 is coated on the surface of the first conductive circuit layer 130 and the second conductive circuit layer 150 away from the base layer 11 by using a semi-cured (non-flowing, easily deformable) resin. The semi-cured resin on the first conductive wiring layer 130 and the second conductive wiring layer 150 is pressed, so that the semi-cured resin flows to fill the conductive via 30, and the first conductive wiring layer 130 and the second conductive wiring layer 150. Formed with a gap between the base layer 11. The protective layer 63 is formed on a surface of the insulating layer 61 away from the substrate 10, respectively. The protective layer 63 can be a solder mask or a cover layer (CVL) commonly used in the industry.

It can be understood that, before forming the protective layer 63, a plurality of conductive circuit layers (not shown) may be formed on the opposite surfaces of the insulating layer 61 by a build-up method, respectively, with the first conductive circuit layer 130 or the second conductive circuit layer. 150 is electrically connected to thereby produce a flexible circuit board 100 including a plurality of layers of conductive wiring layers. Among them, the formation of a plurality of layers of conductive circuit layers by the build-up method is a conventional technique, and will not be described herein.

In the second embodiment, referring to FIG. 9 , the difference from the first embodiment is that the receiving hole 18 formed in step S2 is a through hole penetrating through the first copper layer 13 , the base layer 11 , and the The second copper layer 15. The receiving hole 18 includes two opposite open ends 181. In this case, the step S6 further includes: forming a conductive layer 40 electrically connected to the second conductive circuit layer 150 on the surface of the dielectric material 20 adjacent to the second conductive circuit layer 150. The conductive layer 40 electrically connected to the first conductive wiring layer 130 forms a first region corresponding to the dielectric material 20 and the conductive layer 40 electrically connected to the second conductive wiring layer 150 corresponding to the dielectric material 20 The electrode 131 and a second electrode 153, the first electrode 131, the dielectric material 20 and the second electrode 153 cooperate to form a capacitor 50. The conductive layer 40 electrically connected to the second conductive circuit layer 150 covers the surface of the dielectric material 20 near the second conductive circuit layer 150.

In the third embodiment, referring to FIG. 10, the difference between the first embodiment and the second embodiment is that the conductive layer 40 is formed by printing in step S6, and the material of the conductive layer 40 is selected from the following. One or more of conductive silver paste, conductive carbon paste, conductive solder paste and conductive copper paste.

The flexible circuit board 100 manufactured by the above-described first and third embodiments is applied to the electronic device 200 (please refer to FIG. 12). The electronic device 200 can be a smart phone, a tablet computer, a notebook computer, a multimedia player, or the like. Referring to FIGS. 8 and 10, the flexible circuit board 100 includes a flexible base layer 11 and a first conductive circuit layer 130 and a second conductive circuit layer 150 formed on the opposite surfaces 11a, 11b of the base layer 11. The flexible circuit board 100 is provided with at least one receiving hole 18 in the stacking direction of the first conductive circuit layer 130, the base layer 11 and the second conductive circuit layer 150, that is, the receiving hole 18 sequentially penetrates the first conductive circuit layer 130 and Base layer 11. The receiving hole 18 is filled with a dielectric material 20. A conductive layer 40 electrically connected to the first conductive wiring layer 130 is formed on the surface of the dielectric material 20 adjacent to the first conductive wiring layer 130. The accommodating hole 18 includes an open end 181 , and the conductive layer 40 electrically connected to the first conductive circuit layer 130 covers the open end 181 , and the conductive layer 40 has a cross-sectional width larger than the aperture of the accommodating hole 18 . More specifically, the difference between the cross-sectional width of the conductive layer 40 and the aperture of the accommodating hole 18 is less than 50 μm. The conductive layer 40 electrically connected to the first conductive circuit layer 130 corresponds to the region of the dielectric material 20, and the region of the second conductive circuit layer 150 corresponding to the dielectric material 20 forms a first electrode 131 and a second portion, respectively. Electrode 151. The first electrode 131, the dielectric material 20 and the second electrode 151 cooperate to form a capacitor 50.

The flexible circuit board 100 further includes at least one conductive hole 30 electrically connecting the first conductive circuit layer 130 and the second conductive circuit layer 150. Each of the conductive vias 30 includes a via 16 formed in the substrate 10 and a plating layer 17 formed on the sidewall of the via 16 . Each of the through holes 16 penetrates the first copper layer 13 , the base layer 11 , and the second copper layer 15 .

The flexible circuit board 100 further includes a protective layer 60 covering the surfaces of the first conductive circuit layer 130, the second conductive circuit layer 150, and the conductive layer 40, and the protective layer 60 fills the first conductive line. A gap between the layer 130, the capacitor 50, the base layer 11, and the second conductive wiring layer 150. The protective layer 60 includes an insulating layer 61 and a protective layer 63. The insulating layer 60 is coated on the surface of the first conductive circuit layer 130 and the second conductive circuit layer 150 away from the base layer 11 , and is filled in the conductive hole 30 , and the first conductive circuit layer 130 and the second conductive line of the capacitor A gap between the layer 150 and the base layer 11. The protective layer 63 is formed on a surface of the insulating layer 61 away from the first conductive wiring layer 130 and the second conductive wiring layer 150.

Referring to FIG. 9, the flexible circuit board 100 obtained by the manufacturing method of the second embodiment described above is different from the flexible circuit board 100 manufactured by the manufacturing methods of the first and third embodiments in that the receiving hole 18 is The through hole, that is, the through hole 18 sequentially penetrates the first conductive circuit layer 130, the base layer 11 and the second conductive circuit layer 150, and includes two open ends 181. At this time, a conductive layer 40 electrically connected to the second conductive wiring layer 150 is further formed on the surface of the dielectric material 20 adjacent to the second conductive wiring layer 150. The conductive layer 40 electrically connected to the second conductive wiring layer 150 covers the surface of the dielectric material 20 near the second conductive wiring layer 150. The conductive layer 40 electrically connected to the first conductive wiring layer 130 and the region corresponding to the dielectric material 20 and the conductive layer 40 electrically connected to the second conductive wiring layer 150 respectively form a first electrode The first electrode 131, the dielectric material 20, and the second electrode 153 are combined to form the capacitor 50.

Referring to Figure 11, the capacitance value C of the capacitor 50 can be calculated according to the following formula: C = D _k • E ₀ • A/S. Where D _k is the dielectric constant of the dielectric material 20; E ₀ is a vacuum dielectric constant, which is approximately 8.85 x 10-12 F/m; S is the vertical distance between the first electrode 131 and the second electrode 151 (ie, the height of the base layer 11); A is the area of the first electrode 131 or the second electrode 151, A=H*L (L is the length of the first electrode 131 or the second electrode 151 of the capacitor 50, and H is the capacitor 50 The width of the first electrode 131 or the second electrode 151). It can be understood that the length L of the first electrode 131 or the second electrode 151 of the capacitor 50, the width H of the first electrode 131 or the second electrode 151 or the vertical between the first electrode 131 and the second electrode 151 can be changed according to actual needs. The distance S is such that the capacitance value C of the capacitor 50 is changed.

In the process of preparing the flexible circuit board 100, the present invention directly forms the capacitor 50 required inside the flexible circuit board 100 instead of embedding the existing capacitor therein, thereby avoiding the flexible circuit caused by the oversized capacitor. The case where the thickness of the board 100 is increased, thereby reducing the thickness of the flexible circuit board 100. In addition, the capacitance value C of the capacitor 50 can be adjusted by adjusting the area A of the first electrode 131 or the second electrode 151, the vertical distance S between the first electrode 131 and the second electrode 151, and selecting a different dielectric material 20. Adjust accordingly.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. The above is only a preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art will be included in the following claims.

100‧‧‧Flexible circuit board

10‧‧‧Substrate

11‧‧‧ grassroots

11a, 11b‧‧‧ surface

13‧‧‧First copper layer

15‧‧‧Second copper layer

16‧‧‧through hole

17‧‧‧Electroplating

18‧‧‧ accommodating holes

181‧‧‧Open end

20‧‧‧ dielectric materials

30‧‧‧Electrical hole

130‧‧‧First conductive circuit layer

150‧‧‧Second conductive circuit layer

40‧‧‧ Conductive layer

41‧‧‧Conductive ink layer

42‧‧‧metal layer

131‧‧‧First electrode

151‧‧‧second electrode

50‧‧‧ capacitor

60‧‧‧Protective layer

61‧‧‧Insulation

63‧‧‧Protective layer

200‧‧‧Electronic devices

no

100‧‧‧Flexible circuit board

11‧‧‧ grassroots

11a, 11b‧‧‧ surface

18‧‧‧ accommodating holes

181‧‧‧Open end

20‧‧‧ dielectric materials

30‧‧‧Electrical hole

130‧‧‧First conductive circuit layer

150‧‧‧Second conductive circuit layer

40‧‧‧ Conductive layer

41‧‧‧Conductive ink layer

42‧‧‧metal layer

131‧‧‧First electrode

151‧‧‧second electrode

50‧‧‧ capacitor

60‧‧‧Protective layer

61‧‧‧Insulation

63‧‧‧Protective layer

Claims (19)

A method for manufacturing a flexible circuit board, comprising the following steps:
Providing a substrate comprising a flexible base layer and a first copper layer and a second copper layer respectively formed on opposite surfaces of the base layer;
Disposing at least one accommodating hole in the stacking direction of the first copper layer, the base layer and the second copper layer on the substrate, the accommodating hole at least penetrating through the first copper layer and the base layer, the accommodating hole comprising at least one open end;
Filling a receiving hole with a dielectric material;
Etching the first copper layer and the second copper layer to form a first conductive circuit layer and a second conductive circuit layer, respectively; and forming a first conductive circuit layer or a second surface corresponding to each open end of the dielectric material a conductive layer electrically connected to the conductive circuit layer, a conductive layer electrically connected to the first conductive circuit layer, a region corresponding to the dielectric material forming a first electrode, a conductive layer located at the dielectric material away from the first electrode or a second conductive A region of the wiring layer corresponding to the dielectric material forms a second electrode, and the first electrode, the dielectric material and the second electrode form a capacitor. The method of fabricating a flexible circuit board according to claim 1, wherein the conductive layer completely covers the dielectric material, and the conductive layer has a coverage area larger than an area of the dielectric material adjacent to the surface of the first conductive circuit layer. And the difference between the distance from the edge of the conductive layer to the center of the receiving hole and the distance from the open end in the same direction to the center of the receiving hole is less than 50 μm. The method of fabricating a flexible circuit board according to claim 2, wherein the conductive layer comprises a conductive ink layer formed on the surface of the dielectric material corresponding to each open end by coating. . The method for fabricating a flexible circuit board according to claim 3, wherein the conductive layer further comprises a metal layer formed on the conductive ink layer by sputtering or electroplating and coating the conductive layer. Ink layer. The method for fabricating a flexible circuit board according to claim 2, wherein the conductive layer is formed by printing, and the material is selected from the group consisting of conductive silver paste, conductive carbon paste, conductive solder paste and conductive copper paste. Or several. The manufacturing method of the flexible circuit board of claim 1, wherein the receiving hole is a blind hole having an open end, which penetrates only the first conductive circuit layer and the base layer, and the conductive layer is formed on the dielectric layer. The material is adjacent to the surface of the first conductive circuit layer and electrically connected to the first conductive circuit layer, and the conductive layer electrically connected to the first conductive circuit layer corresponds to the region of the dielectric material and the second conductive circuit layer corresponds to The regions of the electrical material form a first electrode and a second electrode, respectively, and the first electrode, the dielectric material and the second electrode form the capacitor. The method of manufacturing the flexible circuit board of claim 1, wherein the receiving hole is a through hole having two open ends, and sequentially penetrates the first conductive circuit layer, the base layer and the second conductive circuit layer, The conductive layers are respectively formed on the surface of the dielectric material adjacent to the first conductive circuit layer and the surface of the dielectric material adjacent to the second conductive circuit layer, and are electrically connected to the first conductive circuit layer and the second conductive circuit layer, respectively. a conductive layer electrically connected to the first conductive circuit layer, a region corresponding to the dielectric material, and a region corresponding to the dielectric material electrically connected to the second conductive circuit layer respectively form a first electrode and a second electrode, The first electrode, the dielectric material, and the second electrode form the capacitor. The method for fabricating a flexible circuit board according to claim 1, wherein the method further includes: before etching the first copper layer and the second copper layer to form the first conductive circuit layer and the second conductive circuit layer, respectively. :
Having at least one through hole penetrating through the first conductive circuit layer, the base layer and the second conductive circuit layer; and plating the through hole to form a plating layer on the hole wall, thereby obtaining an electrical connection. a conductive hole of the conductive circuit layer and the second conductive circuit layer. The method for fabricating a flexible circuit board according to claim 8, wherein in the step of forming a surface electrically connected to the first conductive circuit layer or the second conductive circuit layer at a surface corresponding to each open end of the dielectric material After the conductive layer, it also includes:
The surface of the first conductive circuit layer, the second conductive circuit layer and the conductive layer is coated with a protective layer, and the protective layer is filled in the conductive hole, and the first conductive circuit layer and the second conductive circuit layer and the base layer a gap, wherein the protective layer includes an insulating layer and a protective layer, the insulating layer covers the first conductive circuit layer and the second conductive circuit layer and is filled in the conductive hole, and the first conductive circuit layer and the second a gap between the conductive circuit layer and the base layer, the protective layer being formed on a surface of the insulating layer away from the first conductive circuit layer and the second conductive circuit layer. A flexible circuit board comprising a flexible base layer and a first conductive circuit layer and a second conductive circuit layer formed on opposite surfaces of the base layer, wherein the flexible circuit board is along the first conductive circuit layer, The accommodating hole includes at least one open end, and the accommodating hole is filled in at least one accommodating hole, and the accommodating hole is at least one open end, and the accommodating hole is filled in the accommodating hole a dielectric material having a conductive layer electrically connected to the first conductive circuit layer or the second conductive circuit layer on a surface corresponding to each open end of the dielectric material, and a conductive layer pair electrically connected to the first conductive circuit layer a region of the dielectric material is formed to form a first electrode, and a region corresponding to the dielectric material is formed on the conductive layer or the second conductive wiring layer of the dielectric material away from the first electrode, the first electrode, the dielectric The material and the second electrode form a capacitor. The flexible circuit board of claim 10, wherein the conductive layer completely covers the dielectric material, the conductive layer has a coverage area larger than an area of the dielectric material adjacent to the surface of the first conductive circuit layer, and the conductive The difference between the edge of the layer to the center of the receiving hole and the distance from the open end in the same direction to the center of the receiving hole is less than 50 μm. The flexible circuit board of claim 11, wherein the conductive layer comprises a conductive ink layer formed on a surface of each of the open ends of the dielectric material. The flexible circuit board of claim 12, wherein the conductive layer further comprises a metal layer formed on the conductive ink layer and covering the conductive ink layer. The flexible circuit board of claim 11, wherein the conductive layer is made of one or more of a conductive silver paste, a conductive carbon paste, a conductive solder paste, and a conductive copper paste. The flexible circuit board of claim 10, wherein the receiving hole is a blind hole having an open end, which penetrates only the first conductive circuit layer and the base layer, and the conductive layer is formed on the dielectric material close to the first a surface of a conductive circuit layer and electrically connected to the first conductive circuit layer, the conductive layer electrically connected to the first conductive circuit layer corresponding to the region of the dielectric material, and the second conductive circuit layer corresponding to the dielectric material The regions respectively form a first electrode and a second electrode, and the first electrode, the dielectric material and the second electrode form the capacitor. The flexible circuit board of claim 10, wherein the receiving hole is a through hole having two open ends, and sequentially penetrates the first conductive circuit layer, the base layer and the second conductive circuit layer, wherein the conductive layer respectively Formed on a surface of the dielectric material adjacent to the first conductive circuit layer and a surface of the dielectric material adjacent to the second conductive circuit layer, and electrically connected to the first conductive circuit layer and the second conductive circuit layer, respectively, and the first a conductive layer electrically connected to the conductive circuit layer, a region corresponding to the dielectric material, and a region corresponding to the dielectric material electrically connected to the second conductive circuit layer respectively form a first electrode and a second electrode, the first An electrode, a dielectric material, and a second electrode form the capacitor. The flexible circuit board of claim 10, wherein the flexible circuit board further comprises at least one conductive hole electrically connecting the first conductive circuit layer and the second conductive circuit layer. The flexible circuit board of claim 17, wherein the flexible circuit board further comprises a protective layer, the protective layer is filled in the conductive hole, and the first conductive circuit layer and the second conductive circuit layer and the base layer a gap, wherein the protective layer includes an insulating layer and a protective layer, the insulating layer covers the first conductive circuit layer and the second conductive circuit layer and is filled in the conductive hole, and the first conductive circuit layer and the second a gap between the conductive circuit layer and the base layer, the protective layer being formed on a surface of the insulating layer away from the first conductive circuit layer and the second conductive circuit layer. An electronic device is improved in that the electronic device comprises at least one flexible circuit board as claimed in any one of claims 10-18.