CN106376170A - Flexible circuit board, manufacturing method thereof, and electronic device - Google Patents

Abstract

A flexible circuit board comprises a flexible substrate and a first conductive circuit layer and a second conductive circuit layer formed on two opposite surfaces of the substrate. At least one accommodating hole is arranged in the flexible circuit board along the overlapped direction of the first conductive circuit layer, the substrate and the second conductive circuit layer; the accommodating hole at least passes through the first conductive circuit layer and the substrate; the accommodating hole comprises at least one opening end; the accommodating hole is filled with a dielectric material; a conductive layer electrically connected with the first conductive circuit layer or the second conductive circuit layer is formed on the surface, corresponding to each opening end, of the dielectric material; a first electrode is formed in an area, corresponding to the dielectric material, on a conductive layer electrically connected with the first conductive circuit layer; a second electrode is formed in an area, corresponding to the dielectric material, on the conductive layer away from the first electrode of the dielectric material or the second conductive circuit layer; and the first electrode, the dielectric material, and the second electrode form a capacitor.

Description

Flexible circuit board, manufacturing method thereof, and electronic device

technical field

The invention relates to a flexible circuit board, a manufacturing method thereof, and an electronic device with the circuit board.

Background technique

In the past, electronic components (such as inductors, capacitors, or resistors) of a printed circuit board (PCB) were usually directly formed on the surface of the PCB. Under the trend of light, thin, small, high-frequency and multi-functional electronic products, such electronic components are usually buried in the PCB during the current PCB manufacturing process. The technology of embedded electronic components in PCB will be more and more widely used in electronic products because of its advantages in miniaturization and thinning of electronic products and in improving signal transmission performance.

However, the traditional PCB embedding technology is to embed electronic components directly in the PCB, and the overall thickness of the PCB is still limited by the thickness of the embedded electronic components, making it difficult to truly achieve the purpose of light, thin and short electronic products.

Contents of the invention

In view of this, it is necessary to provide a method for manufacturing a flexible circuit board that can effectively reduce the thickness of the 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 manufacturing a flexible circuit board, comprising the steps of: providing a substrate, the substrate including a flexible base layer and a first copper layer and a second copper layer respectively formed on two opposite surfaces of the base layer; Open at least one accommodating hole along the stacking direction of the first copper layer, the base layer, and the second copper layer, the accommodating hole at least penetrates the first copper layer and the base layer, and the accommodating hole includes at least one open end; a dielectric material filling in the accommodating hole; etching the first copper layer and the second copper layer to respectively form a first conductive circuit layer and a second conductive circuit layer; The 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 corresponds to a region of the dielectric material to form a first electrode, and the dielectric material is located away from the second conductive circuit layer. A region corresponding to the dielectric material on the conductive layer of the first electrode or the second conductive circuit layer forms a second electrode, and the first electrode, the dielectric material and the second electrode form a capacitor.

A flexible circuit board, which includes a flexible base layer and a first conductive circuit layer and a second conductive circuit layer formed on two opposite surfaces of the base layer, the flexible circuit board is formed along the first conductive circuit layer, the base layer and the second At least one accommodating hole is provided in the stacking direction of the two conductive circuit layers, the accommodating hole at least penetrates the first conductive circuit layer and the base layer, the accommodating hole includes at least one open end, and the accommodating hole is filled with dielectric material, a conductive layer electrically connected to the first conductive circuit layer or the second conductive circuit layer is formed on the surface of the dielectric material corresponding to each opening end, and a conductive layer electrically connected to the first conductive circuit layer corresponds to the dielectric material The region of the material forms a first electrode, and the region corresponding to the dielectric material on the conductive layer or the second conductive circuit layer located on the dielectric material away from the first electrode forms a second electrode. The first electrode, the dielectric material and the first electrode The two electrodes form a capacitor.

An electronic device includes at least one flexible circuit board as described above.

In the process of preparing the flexible circuit board, the present invention directly manufactures the required capacitors inside the flexible circuit board instead of embedding the existing capacitors in it, avoiding the thickness of the flexible circuit board due to the large volume of the buried capacitor. Increased situation, thereby reducing the thickness of the flexible circuit board.

Description of drawings

FIG. 1 is a schematic cross-sectional view of a substrate used in manufacturing a flexible circuit board according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of forming through holes and accommodating holes on the substrate shown in FIG. 1 .

FIG. 3 is a schematic cross-sectional view of filling the accommodating hole shown in FIG. 2 with a dielectric material.

FIG. 4 is a schematic cross-sectional view of forming an electroplating layer on the wall of the through hole shown in FIG. 3 .

5 is a schematic cross-sectional view of forming a first conductive circuit layer and a second conductive circuit layer on the first copper layer and the second copper layer shown in FIG. 4 .

FIG. 6 is a schematic cross-sectional view of forming a conductive ink layer on the surface of the dielectric material shown in FIG. 5 close to the first conductive circuit layer.

FIG. 7 is a schematic cross-sectional view of forming a metal layer on the conductive ink layer shown in FIG. 6 .

FIG. 8 is a schematic cross-sectional view of a flexible circuit board obtained after the surfaces of the first conductive circuit layer and the second conductive circuit layer shown in FIG. 7 are coated with a protective layer.

9 is a schematic cross-sectional view of a flexible circuit board according to a second embodiment of the present invention.

10 is a schematic cross-sectional view of a flexible circuit board according to a third embodiment of the present invention.

FIG. 11 is a schematic partial cross-sectional view of another angle of the flexible circuit board shown in FIG. 8 .

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

Description of main component symbols

flexible circuit board 100 Substrate 10 grassroots 11 surface 11a, 11b first copper layer 13 second copper layer 15 through hole 16 Plating 17 Accommodating hole 18 open end 181 Dielectric material 20 conductive hole 30 first conductive circuit layer 130 second conductive line layer 150 conductive layer 40 conductive ink layer 41 metal layer 42 first electrode 131 second electrode 151 capacitor 50 The protective layer 60 Insulation 61 protective layer 63 electronic device 200

The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings.

detailed description

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

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

Step S2 , referring to FIG. 2 , opening at least one through hole 16 and at least one accommodating hole 18 on the substrate 10 along the stacking direction of the first copper layer 13 , the base layer 11 and the second copper layer 15 . The through hole 16 runs through the first copper layer 13 , the base layer 11 and the second copper layer 15 . The accommodating hole 18 is a blind hole, which passes through 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 , providing a dielectric material 20 and filling it in the accommodating hole 18 to be substantially flush with the outer surface of the first copper layer 13 . Preferably, the dielectric material 20 is a material with a relatively high dielectric constant, such as ceramic powder.

Step S4, referring to FIG. 4 , forming an electroplating layer 17 on the 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 electroplating layer 17 is copper. It can be understood that the material of the electroplating layer 17 can also be selected from other conductive materials.

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

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

Wherein, the conductive layer 40 completely covers the dielectric material 20 . Preferably, the covering area of the conductive layer 40 is larger than the area of the surface of the dielectric material 20 close to the first conductive circuit layer 130, so as to avoid the inability to completely cover the dielectric material 20 due to positioning deviation of the conductive layer 40. The situation improves the yield rate of the product. More specifically, the difference between the distance from the edge of the conductive layer 40 to the center of the accommodating hole 18 and the distance from the open end 181 to the center of the accommodating hole 18 in the same direction is less than 50 μm, when the edge of the conductive layer 40 When the difference between the distance from the center of the receiving hole 18 and the distance from the opening end 181 to the center of the receiving hole 18 in the same direction is greater than 50 μm, the capacitance of the capacitor 50 is likely to decrease. 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 covers the conductive ink layer 41 .

Step S7, please refer to FIG. 8 , cover the surface of the first conductive circuit layer 130 , the second conductive circuit layer 150 and the conductive layer 40 with a protective layer 60 , and the protective layer 60 fills the conductive hole 30 and the second conductive circuit layer. The gap between the first conductive circuit layer 130 and the second conductive circuit layer 150 and the base layer 11 , so as to obtain the flexible circuit board 100 . In this 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 fills the conductive hole 30, the first conductive circuit layer 130 and the second conductive circuit layer 150 of the capacitor. and the gap between the base layer 11. The material of the insulating layer 61 is selected from flexible insulating materials. Preferably, the insulating material is resin, such as epoxy resin. Specifically, the insulating layer 61 is formed by coating a semi-cured (non-flowing, easily deformable) resin on the surface of the first conductive circuit layer 130 and the second conductive circuit layer 150 away from the base layer 11, and the first conductive circuit layer The semi-cured resin on the first conductive circuit layer 130 and the second conductive circuit layer 150 is pressed, so that the semi-cured resin flows to fill the conductive hole 30, and the first conductive circuit layer 130 and the second conductive circuit layer 150 and The gap between the base layers 11 is formed. The protective layers 63 are respectively formed on surfaces of the insulating layer 61 away from the substrate 10 . The protection 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 to be respectively connected with the first conductive circuit layer 130 or the second conductive circuit layer. 150 are electrically connected, so that the flexible circuit board 100 including multiple conductive circuit layers is produced. Wherein, the formation of multiple conductive circuit layers by a build-up method is a prior art, and will not be repeated here.

In the second embodiment, please refer to FIG. 9 , the difference from the first embodiment is that the accommodating hole 18 formed in step S2 is a through hole, which runs through the first copper layer 13 , the base layer 11 and the first copper layer 13 . Two copper layers 15. The receiving hole 18 includes two opposite open ends 181 . At this time, 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 close to the second conductive circuit layer 150 . The region of the conductive layer 40 electrically connected to the first conductive circuit layer 130 corresponding to the dielectric material 20 and the region of the conductive layer 40 electrically connected to the second conductive circuit layer 150 corresponding to the dielectric material 20 respectively form a first 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 . Wherein, the conductive layer 40 electrically connected to the second conductive circuit layer 150 covers the surface of the dielectric material 20 close to the second conductive circuit layer 150 .

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

The flexible circuit board 100 manufactured by the manufacturing methods of the above-mentioned first embodiment and the third embodiment is applied in an 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, and 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 two opposite surfaces 11a, 11b of the base layer 11 . The flexible circuit board 100 is provided with at least one accommodating hole 18 along the stacking direction of the first conductive circuit layer 130, the base layer 11 and the second conductive circuit layer 150, that is, the accommodating hole 18 runs through the first conductive circuit layer 130 and the second conductive circuit layer 150 sequentially. grassroots11. The accommodating hole 18 is filled with a dielectric material 20 . A conductive layer 40 electrically connected to the first conductive circuit layer 130 is formed on the surface of the dielectric material 20 close to the first conductive circuit layer 130 . Wherein, the accommodating hole 18 includes an open end 181 , the conductive layer 40 electrically connected to the first conductive circuit layer 130 covers the open end 181 , and the cross-sectional width of the conductive layer 40 is larger than the diameter of the accommodating hole 18 . More specifically, the difference between the cross-sectional width of the conductive layer 40 and the diameter of the accommodating hole 18 is less than 50 μm. The region of the conductive layer 40 electrically connected to the first conductive circuit layer 130 corresponding to the dielectric material 20 and the region of the second conductive circuit layer 150 corresponding to the dielectric material 20 form a first electrode 131 and a second electrode 131 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 conductive hole 30 includes a through hole 16 formed on the substrate 10 and an electroplating layer 17 formed on a wall of the through hole 16 . Wherein, each through hole 16 runs through the first copper layer 13 , the base layer 11 and the second copper layer 15 .

The flexible circuit board 100 also includes a protective layer 60, the protective layer 60 covers 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 circuit The gap between the layer 130 , the capacitor 50 , the base layer 11 and the second conductive circuit layer 150 . The protective layer 60 includes an insulating layer 61 and a protective layer 63 . The insulating layer 60 covers the surface of the first conductive circuit layer 130 and the second conductive circuit layer 150 away from the base layer 11, and fills the conductive hole 30, the first conductive circuit layer 130 and the second conductive circuit of the capacitor. The gap between layer 150 and base layer 11 . The protective layer 63 is formed on the surface of the insulating layer 61 away from the first conductive circuit layer 130 and the second conductive circuit layer 150 .

Please refer to Fig. 9. The difference from the first and third embodiments is that in the flexible circuit board 100 manufactured by the preparation method of the above-mentioned second embodiment, the accommodating hole 18 is also a through hole, that is, the accommodating hole 18 runs through the first conductive circuit layer 130 , the base layer 11 and the second conductive circuit layer 150 in sequence, and includes two open ends 181 . At this time, a conductive layer 40 electrically connected to the second conductive circuit layer 150 is further formed on the surface of the dielectric material 20 close to the second conductive circuit layer 150 . The conductive layer 40 electrically connected to the second conductive circuit layer 150 covers the surface of the dielectric material 20 close to the second conductive circuit layer 150 . The region of the conductive layer 40 electrically connected to the first conductive circuit layer 130 corresponding to the dielectric material 20 and the region of the conductive layer 40 electrically connected to the second conductive circuit layer 150 corresponding to the dielectric material 20 form first electrodes respectively. 131 and the second electrode 153 , the first electrode 131 , the dielectric material 20 and the second electrode 153 cooperate to form the capacitor 50 .

Referring to FIG. 11 , the capacitance C of the capacitor 50 can be calculated according to the following formula: C=Dk·E0·A/S. Wherein, Dk is the dielectric constant of the dielectric material 20; E0 is the vacuum dielectric constant, which is approximately 8.85×10-12F/m; S is the vertical distance between the first electrode 131 and the second electrode 151 (ie, the base layer 11 height); 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 first electrode of the capacitor 50 131 or the width of 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 distance between the first electrode 131 and the second electrode 151 can be changed according to actual needs. The distance S, thereby changing the capacitance C of the capacitor 50 .

In the process of preparing the flexible circuit board 100, the present invention directly manufactures the required capacitor 50 inside the flexible circuit board 100, instead of embedding the existing capacitors in it, avoiding the flexible circuit due to the large volume of the embedded capacitor. The thickness of the circuit board 100 is increased, thereby reducing the thickness of the flexible circuit board 100 . In addition, the capacitance 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 different dielectric materials 20. Adjust accordingly.

It can be understood that those skilled in the art can make various other corresponding changes and modifications according to the technical concept of the present invention, and all these changes and modifications should belong to the protection scope of the claims of the present invention.

Claims (19)

1. A method for manufacturing a flexible circuit board, comprising the steps of: A substrate is provided, the substrate includes a flexible base layer and a first copper layer and a second copper layer respectively formed on two opposite surfaces of the base layer; Open at least one accommodating hole on the substrate along the stacking direction of the first copper layer, the base layer, and the second copper layer, the accommodating hole at least penetrates the first copper layer and the base layer, and the accommodating hole includes at least one open end; filling a dielectric material in the accommodating hole; etching the first copper layer and the second copper layer to respectively form a first conductive circuit layer and a second conductive circuit layer; and A conductive layer electrically connected to the first conductive circuit layer or the second conductive circuit layer is formed on the surface of the dielectric material corresponding to each opening end, and a conductive layer electrically connected to the first conductive circuit layer corresponds to the dielectric material. The area forms the first electrode, and the area corresponding to the dielectric material on the conductive layer or the second conductive circuit layer located on the dielectric material away from the first electrode forms the second electrode. The first electrode, the dielectric material and the second electrode form a capacitor. 2. The manufacturing method of a flexible circuit board according to claim 1, wherein the conductive layer completely covers the dielectric material, and the covered area of the conductive layer is larger than that of the surface of the dielectric material close to the first conductive circuit layer. area, and the difference between the distance from the edge of the conductive layer to the center of the accommodating hole and the distance from the opening end to the center of the accommodating hole in the same direction is less than 50 μm. 3. The manufacturing method of a flexible circuit board according to claim 2, wherein the conductive layer includes a conductive ink layer, and the conductive ink layer is formed on the surface of the dielectric material corresponding to each opening end by coating superior. 4. The manufacturing method of a flexible circuit board according to claim 3, wherein the conductive layer further comprises a metal layer, and the metal layer is formed on the conductive ink layer and covers the conductive ink layer by sputtering or electroplating. conductive ink layer. 5. The manufacturing method of the flexible circuit board as claimed in claim 2, characterized in that: the conductive layer is formed by printing, and its material is selected from conductive silver paste, conductive carbon paste, conductive solder paste and conductive copper paste. one or several. 6. The manufacturing method of a flexible circuit board as claimed in claim 1, wherein the accommodating hole is a blind hole having an open end, which only runs through the first conductive circuit layer and the base layer, and the conductive layer forms On the surface of the dielectric material close to the first conductive circuit layer and electrically connected to the first conductive circuit layer, the conductive layer electrically connected to the first conductive circuit layer corresponds to the area of the dielectric material, and the second conductive circuit layer A first electrode and a second electrode are respectively formed corresponding to the region of the dielectric material, and the first electrode, the dielectric material and the second electrode form the capacitor. 7. The manufacturing method of a flexible circuit board according to claim 1, wherein the accommodating hole is a through hole having two open ends, which sequentially penetrate through the first conductive circuit layer, the base layer and the second conductive circuit layer, the conductive layer is respectively formed on the surface of the dielectric material close to the first conductive circuit layer and the surface of the dielectric material close to the second conductive circuit layer, and is respectively connected with the first conductive circuit layer and the second conductive circuit layer Electrically connected, the region of the conductive layer electrically connected to the first conductive circuit layer corresponding to the dielectric material, and the region of the conductive layer electrically connected to the second conductive circuit layer corresponding to the dielectric material respectively form a first electrode and a The second electrode, the first electrode, the dielectric material and the second electrode form the capacitor. 8. The manufacturing method of a flexible circuit board according to claim 1, wherein: before the step "etching the first copper layer and the second copper layer to form the first conductive circuit layer and the second conductive circuit layer respectively" Also includes: Opening at least one through hole through the first conductive circuit layer, the base layer and the second conductive circuit layer on the substrate; and Electroplating is performed on the through hole to form an electroplating layer on the hole wall, so as to obtain a conductive hole electrically connecting the first conductive circuit layer and the second conductive circuit layer. 9. The manufacturing method of the flexible circuit board according to claim 8, characterized in that: in the step "on the surface of the dielectric material corresponding to each opening end, a layer electrically connected to the first conductive circuit layer or the second conductive circuit layer is formed. Connected conductive layer" also includes: A protective layer is coated on the surface of the first conductive circuit layer, the second conductive circuit layer and the conductive layer, and the protective layer is filled in the conductive hole, and between the first conductive circuit layer, the second conductive circuit layer and the base layer The gap between, 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 fills the conductive hole, and the first conductive circuit layer and the second conductive circuit layer In the gap between the conductive circuit layer and the base layer, the protection layer is formed on the surface of the insulating layer away from the first conductive circuit layer and the second conductive circuit layer. 10. A flexible circuit board, which includes a flexible base layer and a first conductive circuit layer and a second conductive circuit layer formed on two opposite surfaces of the base layer, characterized in that: the flexible circuit board along the first conductive line layer At least one accommodating hole is provided in the stacking direction of the circuit layer, the base layer and the second conductive circuit layer, the accommodating hole at least penetrates the first conductive circuit layer and the base layer, the accommodating hole includes at least one open end, Dielectric material is filled inside, and a conductive layer electrically connected to the first conductive circuit layer or the second conductive circuit layer is formed on the surface of the dielectric material corresponding to each opening end, and a conductive layer electrically connected to the first conductive circuit layer is formed. The region of the conductive layer corresponding to the dielectric material forms a first electrode, and the region of the dielectric material located on the conductive layer or the second conductive circuit layer that is far away from the first electrode forms a second electrode, and the first electrode , the dielectric material and the second electrode form a capacitor. 11. The flexible circuit board according to claim 10, wherein the conductive layer completely covers the dielectric material, and the covering area of the conductive layer is larger than the area of the surface of the dielectric material close to the first conductive circuit layer, and The difference between the distance from the edge of the conductive layer to the center of the accommodating hole and the distance from the opening end to the center of the accommodating hole in the same direction is less than 50 μm. 12. The flexible circuit board as claimed in claim 11, wherein the conductive layer comprises a conductive ink layer, and the conductive ink layer is formed on a surface of the dielectric material corresponding to each open end. 13. The flexible circuit board as claimed in claim 12, wherein the conductive layer further comprises a metal layer, the metal layer is formed on the conductive ink layer and covers the conductive ink layer. 14. The flexible circuit board according to claim 11, wherein the conductive layer is made of one or more materials selected from conductive silver paste, conductive carbon paste, conductive solder paste and conductive copper paste. 15. The flexible circuit board according to claim 10, wherein the accommodating hole is a blind hole with an open end, which only penetrates the first conductive circuit layer and the base layer, and the conductive layer is formed on the dielectric The material is close to the surface of the first conductive circuit layer and electrically connected with the first conductive circuit layer, the conductive layer electrically connected with the first conductive circuit layer corresponds to the region of the dielectric material, and the second conductive circuit layer corresponds to the dielectric material The regions of electrical material respectively form a first electrode and a second electrode, and the first electrode, dielectric material and second electrode form the capacitor. 16. The flexible circuit board as claimed in claim 10, wherein the accommodating hole is a through hole having two open ends, which sequentially penetrate through the first conductive circuit layer, the base layer and the second conductive circuit layer, so that The conductive layers are respectively formed on the surface of the dielectric material close to the first conductive circuit layer and on the surface of the dielectric material close to the second conductive circuit layer, and are respectively electrically connected to the first conductive circuit layer and the second conductive circuit layer, The region of the conductive layer electrically connected to the first conductive circuit layer corresponding to the dielectric material, and the region of the conductive layer electrically connected to the second conductive circuit layer corresponding to the dielectric material form a first electrode and a second electrode respectively , the first electrode, the dielectric material and the second electrode form the capacitor. 17. The flexible circuit board according to 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. 18. The flexible circuit board according to claim 17, characterized in that: 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 gap between the base layers, 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 fills the conductive hole, and the first conductive circuit layer and the second conductive circuit layer In the gap between the second conductive circuit layer and the base layer, the protective layer is formed on the surface of the insulating layer away from the first conductive circuit layer and the second conductive circuit layer. 19. An electronic device, characterized in that the electronic device comprises at least one flexible circuit board according to claims 10-18.