CN116634697A - Flexible circuit board with embedded capacitor and manufacturing method thereof - Google Patents
Flexible circuit board with embedded capacitor and manufacturing method thereof Download PDFInfo
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- CN116634697A CN116634697A CN202310438928.7A CN202310438928A CN116634697A CN 116634697 A CN116634697 A CN 116634697A CN 202310438928 A CN202310438928 A CN 202310438928A CN 116634697 A CN116634697 A CN 116634697A
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- 239000003990 capacitor Substances 0.000 title claims abstract description 137
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 56
- 238000005530 etching Methods 0.000 claims abstract description 87
- 230000001681 protective effect Effects 0.000 claims abstract description 49
- 230000008093 supporting effect Effects 0.000 claims abstract description 36
- 238000000034 method Methods 0.000 claims abstract description 31
- 238000003825 pressing Methods 0.000 claims abstract description 12
- 239000000758 substrate Substances 0.000 claims description 64
- 238000005553 drilling Methods 0.000 claims description 31
- 239000000463 material Substances 0.000 claims description 27
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 26
- 229910052802 copper Inorganic materials 0.000 claims description 26
- 239000010949 copper Substances 0.000 claims description 26
- 239000000853 adhesive Substances 0.000 claims description 23
- 230000001070 adhesive effect Effects 0.000 claims description 23
- 238000001465 metallisation Methods 0.000 claims description 12
- 239000003292 glue Substances 0.000 claims description 10
- 238000005516 engineering process Methods 0.000 abstract description 24
- 239000010410 layer Substances 0.000 description 60
- 238000010586 diagram Methods 0.000 description 14
- 239000012790 adhesive layer Substances 0.000 description 7
- 238000010030 laminating Methods 0.000 description 4
- 239000004642 Polyimide Substances 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 3
- 239000000945 filler Substances 0.000 description 3
- 238000003475 lamination Methods 0.000 description 3
- 229920001721 polyimide Polymers 0.000 description 3
- 239000012779 reinforcing material Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 229910052454 barium strontium titanate Inorganic materials 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- NKZSPGSOXYXWQA-UHFFFAOYSA-N dioxido(oxo)titanium;lead(2+) Chemical compound [Pb+2].[O-][Ti]([O-])=O NKZSPGSOXYXWQA-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/46—Manufacturing multilayer circuits
- H05K3/4602—Manufacturing multilayer circuits characterized by a special circuit board as base or central core whereon additional circuit layers are built or additional circuit boards are laminated
- H05K3/4608—Manufacturing multilayer circuits characterized by a special circuit board as base or central core whereon additional circuit layers are built or additional circuit boards are laminated comprising an electrically conductive base or core
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/16—Printed circuits incorporating printed electric components, e.g. printed resistor, capacitor, inductor
- H05K1/162—Printed circuits incorporating printed electric components, e.g. printed resistor, capacitor, inductor incorporating printed capacitors
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/0011—Working of insulating substrates or insulating layers
- H05K3/0044—Mechanical working of the substrate, e.g. drilling or punching
- H05K3/0047—Drilling of holes
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/02—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding
Landscapes
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Manufacturing & Machinery (AREA)
- Production Of Multi-Layered Print Wiring Board (AREA)
Abstract
The invention discloses a flexible circuit board with embedded capacitor and a manufacturing method thereof, wherein the method comprises the following steps: providing a buried core plate, and performing primary etching on the outer surface of a first side of the buried core plate to form a first capacitor electrode and a first circuit; providing a flexible supporting layer, and pressing the supporting layer on the first side of the embedded core plate after one-time etching to form a semi-finished circuit board; performing secondary etching on the outer surface of the second side of the semi-finished circuit board to form a second capacitor electrode and a second circuit, thereby obtaining a buried capacitor circuit board; a facing area exists between the second capacitance electrode and the first capacitance electrode; and sticking a protective film on the buried circuit board to form the target flexible circuit board. The invention can apply the capacitance burying technology to the manufacturing technology of the flexible circuit board, realize the effective combination of the capacitance burying technology and the flexible circuit board, and further manufacture the flexible circuit board with good signal integrity, high reliability, high production yield, low cost and capability of accurately controlling the capacitance of the capacitance burying technology.
Description
Technical Field
The invention relates to the field of flexible circuit board manufacturing, in particular to a flexible circuit board with embedded capacitors and a manufacturing method thereof.
Background
With the rapid development of the electronic industry, electronic products increasingly tend to be light and thin and integrated. The number ratio of active devices to passive devices in the circuit board was investigated to be about 20:1, and as electronics technology advances, the ratio will continue to rise. In a typical circuit board assembly, less than 3% of passive devices such as capacitors, resistors, etc. occupy 40% of the surface space of the circuit board. In addition, parasitic effects exist among densely distributed components on the surface of the circuit board, and the influence on signal integrity is very large.
To solve the above increasingly significant contradictions, passive device embedding technology was proposed in the early eighties of the last century. The technology has remarkable advantages in the aspects of shortening the electrical length between components, improving the electrical characteristics, eliminating welding points, improving the reliability of products, reducing the packaging area, realizing the miniaturization of the products and the like. Under the development trend of high-frequency high-speed and dense signal lines, the capacitor is more important to eliminate the effects of electromagnetic coupling and stray crosstalk, so that the number of the capacitors is the highest in proportion of passive devices. The circuit board capacity burying technology has become a key technology for realizing high-quality high-density circuit boards in the next generation.
The existing capacity burying technology is mainly applied to the fields of rigid circuit boards such as MEMS microphones, HDI printed boards and the like, and the problems of low production yield, low capacity precision and the like still exist in the manufacturing process of the rigid circuit boards. There is currently no involvement in the field of flexible circuit boards. Along with the wider and wider application of Flexible-Printed-Circuit (FPC), the development of a novel Flexible Circuit board with high added value is particularly important to improve the technical development capability and product competitiveness of companies.
Therefore, how to combine the capacity burying technology with the manufacturing process of the flexible circuit board, develop a flexible circuit board with high production yield and capability of precisely controlling the capacity value is a problem to be solved in the prior art.
Disclosure of Invention
In view of the above, the embodiment of the invention provides a flexible circuit board with embedded capacitors and a manufacturing method thereof, so as to solve the problems that the existing embedded technology is only applied to the field of rigid circuit boards, and is not combined with the manufacturing process of the flexible circuit board, and the flexible circuit board with high production yield and capability of accurately controlling the capacitance is developed.
The invention provides a manufacturing method of a flexible circuit board with embedded capacitors, which comprises the following steps:
providing a buried core plate, and performing primary etching on the outer surface of a first side of the buried core plate to form a first capacitor electrode and a first circuit;
providing a flexible supporting layer, and pressing the flexible supporting layer on the first side of the embedded core plate after one-time etching to form a semi-finished circuit board;
performing secondary etching on the outer surface of the second side of the semi-finished circuit board to form a second capacitor electrode and a second circuit, thereby obtaining a buried capacitor circuit board; wherein a facing area exists between the second capacitance electrode and the first capacitance electrode;
and sticking a protective film on the buried circuit board to form the target flexible circuit board.
Optionally, the embedded core board includes an embedded layer, a first base material copper and a second base material copper, where the first base material copper and the second base material copper are respectively disposed on two sides of the embedded layer.
Optionally, the flexible supporting layer is a protective film or a first flexible copper-clad substrate.
Optionally, when the flexible supporting layer is the first flexible copper-clad substrate, before the second etching is performed on the outer surface of the second side of the semi-finished circuit board, the method further includes:
drilling holes on the outer surface of the first side of the semi-finished circuit board;
carrying out in-hole metallization on the drilled semi-finished circuit board so that electric conduction is formed among the holes formed by drilling, the first capacitor electrode and the first circuit;
etching is carried out on the outer surface of the first side of the semi-finished circuit board after the hole is metallized to form an outer layer circuit.
Optionally, when the flexible supporting layer is the first flexible copper-clad substrate, after the second etching is performed on the outer surface of the second side of the semi-finished circuit board, the method further includes:
drilling holes on the outer surface of the first side of the semi-finished circuit board after the secondary etching;
and carrying out in-hole metallization on the drilled semi-finished circuit board, so that electric conduction is formed among the holes formed by drilling, the first capacitor electrode, the first circuit, the second capacitor electrode and the second circuit.
Optionally, when the flexible supporting layer is a protective film, the first side of the embedded core board after one etching is pressed to form a semi-finished circuit board, which includes:
providing a protective film adhesive;
and attaching the protective film to the first side of the buried core plate after one-time etching by utilizing the protective film adhesive to form the semi-finished circuit board.
Optionally, when the flexible supporting layer is the first flexible copper-clad substrate, the first side of the buried core board after one etching is pressed to the first flexible copper-clad substrate to form a semi-finished circuit board, which includes:
providing bonding glue;
and pressing the first flexible copper-clad substrate on the first side of the embedded core plate after one-time etching by using the bonding adhesive to form the semi-finished circuit board.
Optionally, an uncapping area is reserved on the bonding adhesive;
after the buried capacitor circuit board is obtained, the method further comprises the following steps:
and opening the cover of the second side of the buried circuit board based on the cover opening area.
Optionally, before the attaching the protective film to the buried circuit board, the method further includes:
providing a second flexible copper-clad substrate;
and pressing the second flexible copper-clad substrate on the second side of the embedded circuit board, and carrying out drilling treatment on the second side of the embedded circuit board.
Optionally, the second flexible copper-clad substrate is any one of a single-panel, a double-panel, and a multi-layer board.
Optionally, the first flexible copper-clad substrate is any one of a single-panel, a double-panel, and a multi-layer board.
In addition, the invention also provides a flexible circuit board with the embedded capacitor, which is manufactured by adopting the manufacturing method.
The invention has the beneficial effects that: the first capacitor electrode, the first circuit corresponding to the first capacitor electrode and the second circuit corresponding to the second capacitor electrode are respectively formed through twice etching, and then the flexible support plate is pressed and drilled, so that the combination of the capacity burying technology and the manufacturing process of the flexible circuit board is realized, the capacitor is buried in the flexible circuit board, the component mounting cost in a flexible circuit board product can be reduced, the layout space of the surface of the circuit board is optimized, and the product reliability is improved; the electromagnetic interference problem existing in the transmission process of the radio frequency signal can be reduced, and the signal integrity is improved; after the first capacitor electrode is manufactured by one-time etching, the flexible supporting plate is pressed on the buried capacitor core plate, then the second capacitor electrode is manufactured by two-time etching, and the two capacitor electrodes are manufactured in sequence, on one hand, the manufacturing of the first capacitor electrode and the second capacitor electrode can be respectively and independently controlled by two-time etching of the two side surfaces, and the precision control of the buried capacitor is realized by controlling the facing areas of the two capacitor electrodes; on the other hand, as the dielectric layer of the embedded core plate is very fragile, the phenomenon of damage of the dielectric layer of the embedded core plate caused by simultaneous etching of two times can be avoided, and the supporting property of the embedded core plate is improved by utilizing the flexible supporting plate without adopting a rigid material, so that the steps of a process flow are reduced, and the cost is also reduced;
the flexible circuit board with the embedded capacitor and the manufacturing method thereof can apply the embedded capacitor technology to the manufacturing technology of the flexible circuit board, realize the effective combination of the embedded capacitor and the flexible circuit board, and further manufacture the flexible circuit board with good signal integrity, high reliability, high production yield and low cost and can accurately control the capacitance value of the embedded capacitor.
Drawings
The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and should not be construed as limiting the invention in any way, in which:
fig. 1 is a flowchart of a method for manufacturing a flexible circuit board with embedded capacitors according to a first embodiment of the present invention;
FIG. 2 is a cross-sectional view of a core plate of a first embodiment of the present invention;
FIG. 3 is a schematic cross-sectional view of a first etched buried core board according to an embodiment of the present invention;
fig. 4 is a schematic diagram showing a cross-sectional view of a semi-finished circuit board obtained by laminating a protective film on a core board in accordance with the first embodiment of the present invention;
fig. 5 is a schematic diagram showing a cross-sectional view of a buried capacitor circuit board obtained by performing secondary etching on the semi-finished circuit board of fig. 4 in accordance with an embodiment of the present invention;
fig. 6 is a schematic diagram showing a cross-sectional view of a target flexible circuit board obtained by attaching a protective film to the buried circuit board of fig. 4 according to an embodiment of the present invention;
fig. 7 is a schematic diagram showing a cross-sectional view of a semi-finished circuit board obtained by laminating a first flexible copper-clad substrate with a buried core board according to a first embodiment of the present invention;
fig. 8A is a cross-sectional view showing a first configuration of a buried wiring board in accordance with an embodiment of the present invention;
fig. 8B is a schematic diagram showing a cross-sectional view of a second implementation of the buried wiring board in accordance with the first embodiment of the present invention;
fig. 9A is a cross-sectional view showing a third configuration of the buried wiring board in the first embodiment of the present invention;
fig. 9B is a top view showing a third configuration of a buried wiring board according to an embodiment of the present invention;
fig. 10 is a cross-sectional view showing a structure of a fourth implementation of the buried wiring board in the first embodiment of the present invention;
fig. 11 is a schematic diagram showing a cross-sectional view of a buried wiring board after opening a cover in accordance with the first embodiment of the present invention;
fig. 12 is a cross-sectional view showing a structure of a first implementation of the objective flexible wiring board manufactured in the first embodiment of the present invention;
fig. 13 is a cross-sectional view showing a structure of a second implementation of the target flexible wiring board manufactured in the first embodiment of the present invention;
fig. 14A is a cross-sectional view showing a structure of a third implementation of the target flexible wiring board manufactured in the first embodiment of the present invention;
fig. 14B is a cross-sectional view showing a structure of a fourth implementation of the target flexible wiring board manufactured in the first embodiment of the present invention;
fig. 15A is a cross-sectional view showing a structure of a fifth implementation of the objective flexible wiring board manufactured in the first embodiment of the present invention;
fig. 15B is a cross-sectional view of the fifth embodiment of the objective flexible wiring board manufactured in the first embodiment of the present invention.
The reference numerals are described as follows:
1. the embedded core board comprises a buried core board, 2 parts of a first flexible copper-clad substrate, 3 parts of bonding glue, 4 parts of holes, 5 parts of protective film glue, 6 parts of protective film, 7 parts of a second flexible copper-clad substrate, 11 parts of buried layer, 12 parts of first base material copper, 13 parts of second base material copper, 14 parts of first capacitance electrode, 15 parts of first circuit, 16 parts of second capacitance electrode, 17 parts of second circuit, 21 parts of first PI layer, 22 parts of third base material copper, 31 parts of cover opening area, 71 parts of second PI layer, 72 parts of fourth base material copper, 100 parts of bendable area.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention.
Example 1
The embodiment provides a method for manufacturing a flexible circuit board with embedded capacitors, as shown in fig. 1, which comprises the following steps:
s1: providing a buried core plate, and performing primary etching on the outer surface of a first side of the buried core plate to form a first capacitor electrode and a first circuit;
s2: providing a flexible supporting layer, and pressing the flexible supporting layer on the first side of the embedded core plate after one-time etching to form a semi-finished circuit board;
s3: performing secondary etching on the outer surface of the second side of the semi-finished circuit board to form a second capacitor electrode and a second circuit, thereby obtaining a buried capacitor circuit board; wherein a facing area exists between the second capacitance electrode and the first capacitance electrode;
s4: and sticking a protective film on the buried circuit board to form the target flexible circuit board.
In the embodiment, the first capacitor electrode, the first circuit corresponding to the first capacitor electrode and the second circuit corresponding to the second capacitor electrode are respectively formed through two times of etching, and then the flexible supporting plate is pressed and drilled, so that the combination of the capacity burying technology and the manufacturing technology of the flexible circuit board is realized, the capacitor is buried in the flexible circuit board, the component mounting cost in a flexible circuit board product can be reduced, the layout space of the surface of the circuit board is optimized, and the product reliability is improved; the electromagnetic interference problem existing in the transmission process of the radio frequency signal can be reduced, and the signal integrity is improved; after the first capacitor electrode is manufactured by one-time etching, the flexible supporting plate is pressed on the buried capacitor core plate, then the second capacitor electrode is manufactured by two-time etching, and the two capacitor electrodes are manufactured in sequence, on one hand, the manufacturing of the first capacitor electrode and the second capacitor electrode can be respectively and independently controlled by two-time etching of the two side surfaces, and the precision control of the buried capacitor is realized by controlling the facing areas of the two capacitor electrodes; on the other hand, as the dielectric layer of the embedded core plate is very fragile, the phenomenon of damage of the dielectric layer of the embedded core plate caused by simultaneous etching of two times can be avoided, and the supporting property of the embedded core plate is improved by utilizing the flexible supporting plate without adopting a rigid material, so that the steps of a process flow are reduced, and the cost is also reduced.
The manufacturing method of the flexible circuit board with the embedded capacitor can apply the embedded capacitor technology to the manufacturing technology of the flexible circuit board, and achieve effective combination of the embedded capacitor technology and the flexible circuit board, so that the flexible circuit board with good signal integrity, high reliability, high production yield and low cost can be manufactured, and the capacitance value of the embedded capacitor can be accurately controlled.
Each step of the method for manufacturing the flexible wiring board with embedded capacitor is described in detail below.
In this embodiment S1, as shown in fig. 2, the buried core board 1 includes a buried layer 11, a first base copper 12 and a second base copper 13, and the first base copper 12 and the second base copper 13 are respectively disposed on two sides of the buried layer 11.
The buried layer 11 is composed of a main material, a filler and a reinforcing material, wherein the main material comprises polymers such as epoxy resin, polyimide and the like, and the filler comprises ceramic powder fillers such as barium strontium titanate, lead titanate and the like; the reinforcing material is composed of glass cloth and other reinforcing materials.
The first base material copper and the second base material copper are base material layers made of copper, and the first capacitor electrode and the second capacitor electrode are formed by adopting the etching process of the flexible circuit board conveniently and respectively based on the first base material copper, the second base material copper and the buried capacitance layer made of the materials, so that realization of buried capacitance in the flexible circuit board is ensured.
For convenience of description, the upper side of the core plate 1 is taken as a first side, and the lower side is taken as a second side in fig. 2.
In the embodiment S1, the conventional operation method of the etching process in the flexible circuit board manufacturing field can be adopted for the primary etching, and the details thereof will not be described here. During etching, etching parameters including etching positions and etching dimensions may be preset according to the capacitor design in a specific electronic product, and after etching the first substrate copper on the outer surface of the first side of the embedded core board according to the etching positions and etching dimensions, the first substrate copper left is the first capacitor electrode of the embedded capacitor and the first circuit corresponding to the first capacitor electrode (the first circuit is used for forming electrical conduction between the first capacitor electrode and other electronic components), namely the top electrode of the embedded core board 1 shown in fig. 2. The cross-sectional structure of the buried core board after the primary etching is shown in fig. 3, where 14 in fig. 3 is a first capacitor electrode, and 15 is a first line.
Preferably, the flexible supporting layer is a protective film or a first flexible copper-clad substrate.
Through protection film and first flexible copper-clad base plate, can both play better supporting role to the first side etched buries appearance core, the second electric capacity electrode of its second side of being convenient for and the preparation of second circuit to realize the preparation of the flexible circuit board of embedded electric capacity, need not to adopt rigid material to promote supportability, reduced the technological process step, also reduced the cost.
The first flexible copper-clad substrate in the present embodiment S2 may be any one of a single-sided board, a double-sided board, and a multilayer board. The single panel is a substrate composed of an insulating layer (such as polyimide and PI layer) and a conductive layer (such as copper layer), wherein the conductive layer is positioned on one side of the insulating layer; the double-sided board is a substrate with an insulating layer and two conductive layers, wherein the two conductive layers are respectively positioned on two sides of the insulating layer. The multilayer board is a substrate formed by combining the single-sided board and the double-sided board, wherein only one outer surface of the multilayer board can be used as a conductive layer, and a plurality of insulating layers and a plurality of conductive layers are contained in the multilayer board; the multilayer board may have both outer surfaces having a conductive layer, and may include a plurality of insulating layers and a plurality of conductive layers therein.
Preferably, when the flexible supporting layer is a protective film, in S2, the first side of the embedded core board after one etching is pressed to the flexible supporting layer to form a semi-finished circuit board, which includes:
s211: providing a protective film adhesive;
s212: and attaching the protective film to the first side of the buried core plate after one-time etching by utilizing the protective film adhesive to form the semi-finished circuit board.
The protective film is attached to the first side of the embedded core plate by utilizing protective film glue, the embedded core plate is supported, the phenomena of plate breakage and the like caused by brittleness of a medium layer of the embedded core plate are avoided, and the supportability of the embedded core plate is improved by a manufacturing technology of the flexible circuit board.
The cross-sectional structure of the semi-finished circuit board obtained by laminating the protective film on the embedded core board in this embodiment is shown in fig. 4, based on the semi-finished circuit board, the embedded circuit board obtained by performing the second etching according to the step S3 is shown in fig. 5, and the structure of the target flexible circuit board obtained by performing the protective film lamination according to the step S4 is shown in fig. 6, wherein since the protective film is already laminated on the first side, the step S4 is only required to laminate the protective film on the second side of the embedded circuit board, and when the protective film is laminated on the second side, the protective film is also laminated on the second side of the embedded circuit board by using the protective film adhesive; in fig. 4 to 6, 16 is a second capacitor electrode, 17 is a second circuit, 5 is a protective film adhesive, and 6 is a protective film, wherein the protective film is mainly made of PI (polyimide).
Preferably, when the flexible supporting layer is the first flexible copper-clad substrate, in S2, the flexible supporting layer is pressed on the first side of the buried core board after one etching to form a semi-finished circuit board, which includes:
s21: providing bonding glue;
s22: and pressing the first flexible copper-clad substrate on the first side of the buried core plate after one-time etching by using the binding glue to form the semi-finished circuit board.
The first flexible copper-clad substrate is pressed on the first side of the buried core board after one-time etching (namely the upper side of the buried core board in fig. 3) by using the binding glue, so that the capacitor is buried by effectively combining the manufacturing technology of the flexible circuit board, the embedded buried core board is replaced by the same volume value without increasing the thickness of the flexible circuit board, the cost of capacitance components in the circuit board is reduced, the component mounting cost is reduced, the layout space of the surface of the circuit board is optimized, the reliability of a product is improved, the electromagnetic interference problem existing in the transmission process of radio frequency signals is also reduced, the signal integrity is improved, and the adhesive layer can be combined to assist in supporting the buried core board so as to improve the operability of the buried core board and avoid the damage problem caused by the brittleness of a medium layer in the buried core board.
Specifically, in order to achieve the flexibility of the target flexible circuit board, an opening area can be arranged on the embedded core board, the adhesive layer is punched based on the opening area, the adhesive layer reserved with the opening area is formed, then in S2, the first flexible copper-clad substrate is pressed on the first side of the embedded core board after one-time etching by using the adhesive layer reserved with the opening area, and the semi-finished circuit board is formed. The cross-sectional structure of the semi-finished circuit board is shown in fig. 7, 2 is a first flexible copper-clad substrate, which is a single-sided board, including a first PI layer 21 and a third base material copper 22; and 3 is a glue layer reserved with an uncovering area, and 31 is the reserved uncovering area.
The embodiment utilizes the uncovering technology in the flexible circuit board to effectively realize the flexibility of the buried flexible circuit board.
Preferably, when the flexible supporting layer is the first flexible copper-clad substrate, before S3 in the first specific embodiment, the method further includes:
drilling holes on the outer surface of the first side of the semi-finished circuit board;
carrying out in-hole metallization on the drilled semi-finished circuit board so that electric conduction is formed among the holes formed by drilling, the first capacitor electrode and the first circuit;
etching is carried out on the outer surface of the first side of the semi-finished circuit board after the hole is metallized to form an outer layer circuit.
Preferably, when the flexible supporting layer is the first flexible copper-clad substrate, in a second specific embodiment, after S3, the method further includes:
drilling holes on the outer surface of the first side of the semi-finished circuit board after the secondary etching;
carrying out in-hole metallization on the drilled semi-finished circuit board, so that electric conduction is formed among the holes formed by drilling, the first capacitor electrode, the first circuit, the second capacitor electrode and the second circuit;
etching is carried out on the outer surface of the first side of the semi-finished circuit board after the hole is metallized to form an outer layer circuit.
In the first embodiment, the buried circuit board is manufactured according to the manufacturing sequence of performing the circuit forming on the first side and then performing the secondary etching on the second side, and in the second embodiment, the buried circuit board is manufactured according to the manufacturing sequence of performing the circuit forming on the first side and then performing the secondary etching on the second side, and the two manufacturing methods can manufacture the second capacitor plate of the embedded capacitor and the corresponding second circuit thereof on one hand, and the dead area existing between the second capacitor electrode and the first capacitor electrode is used as the effective area of the embedded capacitor, so as to realize the manufacturing of the buried flexible circuit board; on the other hand, a series of processes such as drilling, in-hole metallization, etching and the like can be utilized, so that holes formed by drilling, the first capacitor electrode, the first circuit, the second capacitor electrode and the second circuit can be electrically conducted, electric conduction between the embedded capacitor and the outer-layer first flexible copper-clad substrate is realized, and meanwhile, the functionality of the embedded capacitor and the first flexible copper-clad substrate is ensured.
In the two specific embodiments, the drilling and the in-hole metallization are sequentially performed after the drilling, and the etching of the first side of the semi-finished circuit board and the drilling and the in-hole metallization can be performed without limiting the sequence, namely, the drilling, the in-hole metallization and the etching can be performed firstly, and the drilling and the in-hole metallization can be performed firstly and then; meanwhile, the second side of the semi-finished circuit board needs to be etched after the first flexible copper-clad substrate is pressed, so that the etching of the first side can be performed simultaneously with the etching of the second side or sequentially, and the etching is determined according to the specific situation. The buried wiring boards of the following embodiments are fabricated according to the process sequence of drilling holes on the first side of the semi-finished circuit board, metallizing the holes, and then etching the first side and etching the second side simultaneously.
The holes formed by drilling can be blind holes or through holes, and the cross-sectional view structure diagrams of the manufactured buried capacitor circuit board are shown in fig. 8A and 8B, wherein the holes 4 in fig. 8A are blind holes, the holes 4 in fig. 8B are through holes, and the first flexible copper-clad substrate 2 is a single-sided board.
In the secondary etching, as in the primary etching, parameters such as the etching position and the etching dimension of the secondary etching are preset according to the capacitance design of the specific electronic product, and then the etching is performed according to the parameters such as the etching position and the etching dimension of the secondary etching, as shown in fig. 8A and 8B, the second capacitor electrode 16 and the first capacitor electrode 14 have a facing area.
In fig. 8A and 8B, since the etching positions and etching dimensions corresponding to the two etches are identical, the second capacitor electrode 16 is exactly opposite to the first capacitor electrode 14, and the effective area of the embedded capacitor is the area of the two capacitor electrodes.
If the etching positions corresponding to the two etches are the same, but the etching sizes are different, the second capacitor electrode 16 is also completely opposite to the first capacitor electrode 14, but the effective area of the embedded capacitor is the smaller of the areas of the two capacitor electrodes, as shown in fig. 9A and 9B, where fig. 9A is a cross-sectional view structure diagram, fig. 9B is a top view structure diagram (for convenience of illustration, only the first capacitor electrode and the second capacitor electrode are reserved in fig. 9B, and the rest is omitted), the first flexible copper-clad substrate 2 in fig. 9A and 9B is a single-sided board, the hole formed by drilling is a blind hole, and the first flexible copper-clad substrates and the holes of other types are similar, and are not shown here.
If the etching positions and the etching dimensions corresponding to the two etches are different, the second capacitor electrode 16 is not completely opposite to the first capacitor electrode 14, and only a partial area is opposite to the first capacitor electrode 14, so that the effective area of the embedded capacitor is the area of the opposite areas of the two capacitor electrodes, and as shown in fig. 10, the second capacitor electrode 16 is not completely opposite to the first capacitor electrode 14, and a staggered area exists. The first flexible copper-clad substrate 2 in fig. 10 is a single-sided board, the hole formed by drilling is a blind hole, and other types of first flexible copper-clad substrates and holes are similar, and are not shown here.
Preferably, when the cover opening area is reserved on the adhesive layer provided by pressing the first flexible copper-clad substrate, after S3, the method further includes:
and opening the cover of the second side of the buried circuit board based on the cover opening area.
Through the uncovering of the second side of the embedded circuit board, the manufacturing of the bendable embedded flexible circuit board can be facilitated, and the bending property of the whole product is improved.
As for the type of the buried wiring board shown in fig. 8A, a sectional view structural diagram after the cover is opened is shown in fig. 11, and similarly, the case of opening the cover of the type of the buried wiring board shown in fig. 8B is not shown here.
In the embodiment S4, the protective film is attached to one side or both sides of the buried wiring board by using a protective film adhesive. For the buried capacitor circuit board shown in fig. 5, the protective film is attached to the second side of the buried capacitor circuit board only by using protective film glue; for the type of the buried circuit board shown in fig. 8A, the cross-sectional structure diagram of the target flexible circuit board obtained after the protective film is attached is shown in fig. 12, 5 refers to the protective film adhesive, 6 refers to the protective film (the main material is PI), and when the protective film adhesive 5 is attached, the cover opening area 31 in the bonding adhesive 3 and the cover opening area of the buried core board 1 are filled, so that the bendable area 100 of the whole target flexible circuit board is finally formed. Similar to the case of the type of buried wiring board shown in fig. 8B, the detailed illustration is not shown here.
When the bonding adhesive adopted in the process of laminating the first flexible copper-clad substrate is not reserved with the cover opening area, cover opening is not required to be carried out on the second side of the buried circuit board, and then the buried circuit board is directly pasted with a protective film, the cross-sectional surface structure of the obtained target flexible circuit board is shown in fig. 13, the first flexible copper-clad substrate 2 in fig. 13 is a single panel, the second capacitor electrode 16 is not completely opposite to the first capacitor electrode 14, and the hole 4 formed by drilling is a blind hole.
Preferably, before S4, the method further includes:
providing a second flexible copper-clad substrate;
and pressing the second flexible copper-clad substrate on the second side of the embedded circuit board, and carrying out drilling treatment on the second side of the embedded circuit board.
And the second flexible copper-clad substrate is also pressed on the second side of the embedded circuit board, so that the embedded circuit board can be suitable for electronic product designs with different requirements. The lamination method of the second flexible copper-clad substrate is the same as that of the first flexible copper-clad substrate, and the second flexible copper-clad substrate can be laminated on the second side of the buried circuit board by utilizing the adhesive layer without the cover opening area or the adhesive layer with the cover opening area; after lamination, in order to ensure that the inner and outer layers of the whole target flexible circuit board have conductivity, the second flexible copper-clad substrate on the second side is also required to be drilled, metalized in the holes and etched to form through holes or blind holes and circuits which can be electrically conducted with the buried core board of the inner layer.
The second flexible copper-clad substrate is any one of a single-panel, a double-panel and a multi-layer board. The structure and material of the first flexible copper-clad substrate may be the same as or different from those of the first flexible copper-clad substrate.
For the buried circuit board of the type shown in fig. 8A, the bonding adhesive 3 is reserved with an opening area 31, and the second side of the bonding adhesive is pressed with a second flexible copper-clad substrate, drilled, metalized in the hole, etched and then a protective film is attached to obtain a cross-sectional structure diagram of the target flexible circuit board shown in fig. 14A; for the buried circuit board of the type shown in fig. 8B, the bonding adhesive 3 is reserved with an opening area 31, and the second side of the bonding adhesive is pressed with a second flexible copper-clad substrate, drilled, metalized in the hole, etched and then a protective film is attached to obtain a cross-sectional structure diagram of the target flexible circuit board as shown in fig. 14B; in fig. 14A and 14B, the first flexible copper-clad substrate 2 and the second flexible copper-clad substrate 7 (including the second PI layer 71 and the fourth base material copper 72) are both single-sided boards, the second capacitor electrode 16 is completely opposite to the first capacitor electrode 14, the hole 4 formed by drilling in fig. 14A is a blind hole, and the hole 4 formed by drilling in fig. 14B is a through hole (the structure of the double-sided laminate is similar, and is not shown here).
When the bonding adhesive 3 does not reserve the cover opening area, the second side of the bonding adhesive is pressed to the second flexible copper-clad substrate, holes are drilled, metallization in the holes is performed, and a protective film is attached after etching, so that a cross-sectional structure diagram of the target flexible circuit board is shown in fig. 15A and 15B, and in fig. 15A and 15B, the first flexible copper-clad substrate 2 and the second flexible copper-clad substrate 7 are both single-sided boards; in fig. 15A, the second capacitor electrode 16 is completely opposite to the first capacitor electrode 14, and the hole 4 formed by drilling is a blind hole; in fig. 15B, the second capacitor electrode 16 is not completely opposite to the first capacitor electrode 14, and the hole 4 formed by drilling is a through hole.
Example two
The embodiment provides a flexible circuit board with embedded capacitors, which is manufactured by the manufacturing method in the first embodiment.
The flexible circuit board with the embedded capacitor manufactured by the embodiment can be applied to the manufacturing technology of the flexible circuit board, the effective combination of the embedded capacitor and the flexible circuit board is realized, and the manufactured flexible circuit board has the advantages of good signal integrity, high reliability, high production yield and low cost, and can accurately control the capacitance value of the embedded capacitor.
The manufacturing method adopted by the flexible circuit board with embedded capacitor in this embodiment is the same as the steps of the method described in the first embodiment, so details of this embodiment are not described in detail in the first embodiment and the specific descriptions of fig. 1 to 15B, and the details of this embodiment are not described in detail.
Although embodiments of the present invention have been described in connection with the accompanying drawings, various modifications and variations may be made by those skilled in the art without departing from the spirit and scope of the invention, and such modifications and variations are within the scope of the invention as defined by the appended claims.
Claims (12)
1. The manufacturing method of the flexible circuit board with the embedded capacitor is characterized by comprising the following steps of:
providing a buried core plate, and performing primary etching on the outer surface of a first side of the buried core plate to form a first capacitor electrode and a first circuit;
providing a flexible supporting layer, and pressing the flexible supporting layer on the first side of the embedded core plate after one-time etching to form a semi-finished circuit board;
performing secondary etching on the outer surface of the second side of the semi-finished circuit board to form a second capacitor electrode and a second circuit, thereby obtaining a buried capacitor circuit board; wherein a facing area exists between the second capacitance electrode and the first capacitance electrode;
and sticking a protective film on the buried circuit board to form the target flexible circuit board.
2. The method for manufacturing a flexible circuit board with embedded capacitors as claimed in claim 1, wherein the embedded core board comprises an embedded layer, a first base material copper and a second base material copper, and the first base material copper and the second base material copper are respectively arranged on two sides of the embedded layer.
3. The method for manufacturing a flexible circuit board with embedded capacitors as claimed in claim 1, wherein the flexible supporting layer is a protective film or a first flexible copper-clad substrate.
4. The method of manufacturing a flexible circuit board with embedded capacitors as claimed in claim 3, wherein when said flexible supporting layer is said first flexible copper-clad substrate, said method further comprises, before performing the secondary etching on the outer surface of the second side of said semi-finished circuit board:
drilling holes on the outer surface of the first side of the semi-finished circuit board;
carrying out in-hole metallization on the drilled semi-finished circuit board so that electric conduction is formed among the holes formed by drilling, the first capacitor electrode and the first circuit;
etching is carried out on the outer surface of the first side of the semi-finished circuit board after the hole is metallized to form an outer layer circuit.
5. The method of manufacturing a flexible circuit board with embedded capacitors as claimed in claim 3, wherein when the flexible supporting layer is the first flexible copper-clad substrate, after the secondary etching is performed on the outer surface of the second side of the semi-finished circuit board, the method further comprises:
drilling holes on the outer surface of the first side of the semi-finished circuit board after the secondary etching;
carrying out in-hole metallization on the drilled semi-finished circuit board, so that electric conduction is formed among the holes formed by drilling, the first capacitor electrode, the first circuit, the second capacitor electrode and the second circuit;
etching is carried out on the outer surface of the first side of the semi-finished circuit board after the hole is metallized to form an outer layer circuit.
6. The method for manufacturing a flexible circuit board with embedded capacitor as claimed in claim 3, wherein when the flexible supporting layer is a protective film, the first side of the embedded core board after one etching is pressed with the flexible supporting layer to form a semi-finished circuit board, comprising:
providing a protective film adhesive;
and pressing the protective film on the first side of the buried core plate after one-time etching by utilizing the protective film adhesive to form the semi-finished circuit board.
7. The method for manufacturing a flexible circuit board with embedded capacitor as claimed in claim 3, wherein when the flexible supporting layer is the first flexible copper-clad substrate, the first side of the embedded capacitor core board after one etching is pressed to the flexible supporting layer, so as to form a semi-finished circuit board, comprising:
providing bonding glue;
and pressing the first flexible copper-clad substrate on the first side of the embedded core plate after one-time etching by using the bonding adhesive to form the semi-finished circuit board.
8. The method of manufacturing a flexible circuit board with embedded capacitors of claim 7, wherein an open cover area is reserved on the bonding adhesive;
after the buried capacitor circuit board is obtained, the method further comprises the following steps:
and opening the cover of the second side of the buried circuit board based on the cover opening area.
9. The method for manufacturing a flexible circuit board with embedded capacitor according to claim 1, further comprising, before attaching the protective film to the embedded capacitor circuit board:
providing a second flexible copper-clad substrate;
and pressing the second flexible copper-clad substrate on the second side of the embedded circuit board, and carrying out drilling treatment on the second side of the embedded circuit board.
10. The method of manufacturing a flexible circuit board with embedded capacitors as claimed in claim 9, wherein the second flexible copper-clad substrate is any one of a single-sided board, a double-sided board, and a multi-layered board.
11. The method of manufacturing a flexible wiring board with embedded capacitors as claimed in any one of claims 1 to 10, wherein the first flexible copper-clad substrate is any one of a single-sided board, a double-sided board, and a multi-layered board.
12. A flexible circuit board with embedded capacitors, characterized in that it is manufactured by the manufacturing method according to any one of claims 1 to 11.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310438928.7A CN116634697A (en) | 2023-04-23 | 2023-04-23 | Flexible circuit board with embedded capacitor and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310438928.7A CN116634697A (en) | 2023-04-23 | 2023-04-23 | Flexible circuit board with embedded capacitor and manufacturing method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116634697A true CN116634697A (en) | 2023-08-22 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310438928.7A Pending CN116634697A (en) | 2023-04-23 | 2023-04-23 | Flexible circuit board with embedded capacitor and manufacturing method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116634697A (en) |
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2023
- 2023-04-23 CN CN202310438928.7A patent/CN116634697A/en active Pending
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