CN115666016A - Manufacturing method of ultrathin high-shielding flexible circuit board - Google Patents
Manufacturing method of ultrathin high-shielding flexible circuit board Download PDFInfo
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- CN115666016A CN115666016A CN202211168451.7A CN202211168451A CN115666016A CN 115666016 A CN115666016 A CN 115666016A CN 202211168451 A CN202211168451 A CN 202211168451A CN 115666016 A CN115666016 A CN 115666016A
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 39
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 154
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 154
- 238000012545 processing Methods 0.000 claims abstract description 101
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 79
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- Printing Elements For Providing Electric Connections Between Printed Circuits (AREA)
Abstract
The invention discloses a manufacturing method of an ultrathin high-shielding flexible circuit board, which comprises the following steps: making patterns on two surfaces of a double-sided flexible copper-clad plate, making through holes, attaching an opening window to electroplate an auxiliary aluminum sheet to form a via hole, using a one-time pressing mode, performing special typesetting treatment of filling and releasing, performing filling processing on the via hole, performing laser ablation and pattern etching processing on the flexible plate, attaching a shielding film, and forming an ultrathin high-shielding flexible circuit board; the layout of the flexible circuit board is redistributed and structurally adjusted, so that the shielding type of the layout and the thinning of the structure of the flexible circuit board are improved, electroplating processing is carried out by utilizing a special structure, special processing of directly pressing prepreg filling holes is carried out at one time, and the ultrathin high-shielding flexible circuit board which is high in reliability, simple and convenient to process, free from exceeding the standard in thickness, and good in shielding performance is formed.
Description
Technical Field
The invention relates to the field of design and processing of flexible circuit boards, in particular to a manufacturing method of an ultrathin high-shielding flexible circuit board.
Background
In some electronic modules (for example, high precision inspection and testing equipment) with high precision and requiring three-dimensional assembly or repeated bending and folding, an ultra-thin flexible circuit board with high flexibility is required, and meanwhile, some precision equipment has high requirements on the strength and stability of signal transmission of the circuit board and the signal and impedance performance of a via hole, so that the ultra-thin high-shielding flexible circuit board is used.
At present, for an ultra-thin high-shielding flexible circuit board, a transmission line is generally arranged in the middle, and then a shielding line layer and a protective layer (covering film layer) are respectively arranged on the upper surface and the lower surface to form the effect of the high-shielding flexible circuit board; however, for a flexible circuit board requiring two-sided conduction, a via hole is designed, such a circuit board is generally designed to be double-sided, and the via hole increases a certain thickness of the flexible circuit board, and if a shielding circuit layer and a covering protection layer are arranged on the upper and lower surfaces, the total thickness of the circuit board product is thicker, so that the ultrathin characteristic of the circuit board product is influenced, and the actual application effect is influenced.
For the ultra-thin high-shielding flexible circuit board with the via hole, a common manufacturing method is to manufacture a pattern on a double-sided copper-clad plate, then perform drilling processing on the via hole, perform electroplating processing on the flexible circuit board, then press a glue layer and a shielding circuit layer, then manufacture the shielding circuit layer, and then press and cover a film layer to form a flexible circuit board product.
In the processing process, the electroplating processing generally adopts a whole-board direct processing mode, on one hand, the flexible circuit board is easy to twist and bend in the electroplating process due to the thinness of the flexible circuit board, and the problems of uneven electroplating, electric leakage plating, tearing of the flexible circuit board and the like are easy to generate, on the other hand, the overall thickness of the flexible circuit board is increased by direct electroplating, and the board thickness is easy to exceed the standard; the flexible circuit board is still required to be continuously manufactured with a glue layer, a shielding circuit layer and a covering film layer, so that a via hole needs to be subjected to solid processing, hole filling and solid processing are generally performed by adopting a mode of filling resin ink by silk screen printing, and the flexible circuit board is thin, the expansion and shrinkage of the circuit board are easily caused to exceed standards and even tear by the silk screen printing resin ink, and the resin ink can overflow out of the hole and needs to be polished.
Therefore, in view of the above problems, it is desirable to provide a method for manufacturing an ultra-thin high-shielding flexible circuit board having good workability and capable of satisfying thickness control of the ultra-thin flexible circuit board.
Disclosure of Invention
The invention aims to solve the problems that the thickness of an ultrathin high-shielding flexible circuit board in the prior art is easy to exceed the standard and the processing control difficulty is higher, and provides a manufacturing method of the ultrathin high-shielding flexible circuit board, which is characterized by comprising the following steps:
s10: the method comprises the steps of taking a double-sided flexible copper clad laminate, wherein the double-sided flexible copper clad laminate comprises a circuit copper layer and a shielding copper layer, baking the double-sided flexible copper clad laminate, carrying out copper reduction processing after baking is finished, then carrying out circuit pattern manufacturing processing, manufacturing a circuit wiring pattern on the circuit copper layer, and manufacturing an auxiliary circuit wiring pattern on the shielding copper layer to form the circuit pattern flexible board.
S20: and manufacturing a through hole on the circuit pattern flexible board to form a through hole flexible board.
S30: attaching dry films to two sides of the through hole flexible plate, performing windowing of dry film patterns to expose the through holes, attaching an opening window electroplating auxiliary aluminum sheet to the dry film on one side of the auxiliary circuit wiring pattern, wherein the size of the opening window electroplating auxiliary aluminum sheet is larger than or equal to that of the through hole flexible plate, an aluminum sheet opening window area is processed on the opening window electroplating auxiliary aluminum sheet, and the size of the aluminum sheet opening window area is unilateral larger than that of the dry film pattern opening window; an aluminum sheet auxiliary flexible board is integrally formed.
S40: and electroplating the aluminum sheet auxiliary flexible plate to enable the through holes to be electroplated to form via holes, carrying out micro-etching processing on the via holes including glue filling via holes and non-glue filling via holes, then removing the electroplating auxiliary aluminum sheet, and carrying out film removal treatment to form the via hole flexible plate.
S50: and carrying out glue filling processing treatment on the conducting hole flexible plate, wherein the glue filling processing treatment comprises the following steps:
s510: arranging a first flow adhesive prepreg layer, a first release film layer, a second flow adhesive prepreg layer and a second release film layer on one surface of the circuit wiring pattern of the via hole flexible board in sequence, and arranging a third flow adhesive prepreg layer, a third release film layer, a fourth flow adhesive prepreg layer and a fourth release film layer on one surface of the auxiliary circuit wiring pattern of the via hole flexible board in sequence to form an arranging flexible board;
s520: riveting, namely riveting the stacked flexible board by using rivets 5010, wherein the rivets 5010 are positioned in the board edge area of each unit sub-board of the stacked flexible board, and the number of the rivets 5010 in the board edge area of each unit sub-board is more than or equal to 2, so as to form a riveted flexible board 500A;
s530: pressing, namely arranging a first pressing aluminum sheet 5020 and a second pressing aluminum sheet 5030 on the two sides of the riveted flexible plate 500A respectively, typesetting, and pressing to form a pressed flexible plate 500B;
s540: disassembling, namely cutting the laminated flexible board 500B, cutting off the position area of the rivet 5110, and disassembling the first release film layer 520, the second flow prepreg layer 530, the second release film layer 540, the third release film layer 550, the fourth flow prepreg layer 570 and the fourth release film layer 580 to form the glue-filled flexible board 500.
S60: and carrying out laser ablation and pattern etching processing on the glue-filled flexible board to form a surface pattern flexible board.
S70: and carrying out attached shielding film processing on the surface pattern flexible board to form the ultrathin high-shielding flexible circuit board.
Further, the baking of S10 is baking with baking parameters of 140℃ × 30 min.
Further, the thickness of the double-sided flexible copper-clad plate of the S10 is less than or equal to 70 mu m; and carrying out copper reduction processing on the double-sided flexible copper clad laminate, namely thinning the copper layer of the double-sided flexible copper clad laminate to 10-15 mu m.
Further, the S30 includes:
s310: taking an auxiliary aluminum sheet, coating a strippable glue layer on one surface of the auxiliary aluminum sheet, attaching an aluminum sheet protection dry film on the other surface of the auxiliary aluminum sheet, and performing exposure processing to form an electroplating auxiliary aluminum sheet;
s320: manufacturing the aluminum sheet windowing region for the electroplating auxiliary aluminum sheet, wherein the aluminum sheet windowing region corresponds to the dry film pattern windowing region and is 10-50 mu m larger than the size single side of the dry film pattern windowing region to form an opening window electroplating auxiliary aluminum sheet;
s330: and attaching one surface of the opening window electroplating auxiliary aluminum sheet coated with the peelable adhesive layer to the dry film on one surface of the auxiliary circuit wiring pattern to form the aluminum sheet auxiliary flexible plate.
Further, the step S40 is to perform electroplating processing on the aluminum sheet auxiliary flexible board, perform micro etching processing, and perform, for the purpose of performing electroplating processing on the entire aluminum sheet auxiliary flexible board, copper thickness on the inner wall of the through hole formed by the electroplating processing is greater than finished copper thickness required by predetermined processing data, and the micro etching processing is to perform copper reduction etching processing on the aluminum sheet auxiliary flexible board after the electroplating processing.
Further, the copper-reduced etching process is to etch away a copper thickness of 3 μm to 8 μm.
Further, the first flow glue prepreg layer of S510 is set according to the thickness requirement of the predetermined processing data of the ultra-thin high shielding flexible circuit board;
the first flow glue prepreg layer is provided with a first through window area, and the first through window area corresponds to the non-glue-filling conducting hole and is larger than the single side of the non-glue-filling conducting hole by a certain distance;
the first release film layer is provided with a second through window area, and the second through window area is arranged corresponding to the glue filling through hole and is a certain distance greater than the single side of the glue filling through hole;
the third flow glue prepreg layer has the same structure as the first flow glue prepreg layer;
the third release film layer has the same structure as the first release film layer;
the second gumming prepreg layer, the fourth gumming prepreg layer, the second release film layer and the fourth release film layer are not provided with windows;
the sizes of the first gummy prepreg layer, the first release film layer, the second gummy prepreg layer, the third release film layer and the fourth gummy prepreg layer are equal to the size of the via hole flexible board;
the size single side of the second release film layer and the fourth release film layer is larger than the size of the conducting hole flexible plate;
the gel content of the first gummy prepreg layer, the second gummy prepreg layer, the third gummy prepreg layer and the fourth gummy prepreg layer is not less than 65%, and the gel overflow amount under the pressing condition is not more than 0.2mm.
Further, the pressing in S530 is vacuum pressing, and before the pressing, cold pressing is performed at normal temperature for 30min, where the pressure is 160PSI to 220PSI; and after the pressing is finished, cold pressing at normal temperature for 30min, wherein the pressure is 160PSI to 220PSI.
Further, in the step S60, laser ablation and pattern etching are performed on the glue-filled flexible board to form a surface pattern flexible board:
s610: performing laser ablation on the glue filling flexible plate, then punching a through groove on the side edge of the corresponding unit flexible plate of the glue filling flexible plate, and reserving a certain connecting position, wherein the connecting position enables the unit flexible plate to be integrally and fixedly connected to the glue filling flexible plate;
s620: manufacturing a supporting aluminum sheet, taking the supporting aluminum sheet layer, wherein the size of a single side of the supporting aluminum sheet layer is larger than that of the glue filling flexible plate, adhering a micro-adhesive film layer and a blue glue layer to two sides of the supporting aluminum sheet layer respectively to form a coated supporting aluminum sheet, performing unilateral amplification on the coated supporting aluminum sheet for a certain distance according to the distribution and the appearance of the corresponding unit flexible plate, and manufacturing a hollow area to form the supporting aluminum sheet;
s630: attaching one surface of the micro-adhesive film layer of the supporting aluminum sheet to the glue filling flexible plate in an aligned mode, wherein the hollow area corresponds to the unit flexible plate to form a flexible plate with a back attached supporting aluminum sheet;
and S640: and carrying out pattern etching processing on the flexible plate with the back attached supporting aluminum sheet, and then removing the supporting aluminum sheet to form the flexible plate with the surface pattern.
Furthermore, the thickness of the ultrathin high-shielding flexible circuit board is less than or equal to 130 μm.
In the technical scheme of the invention, the layout of the flexible circuit board is redistributed to form a form of one surface of the circuit wiring pattern and the other surface of the auxiliary circuit wiring pattern, and the laminated structure of the flexible circuit board is readjusted to form a double-sided structure which is beneficial to processing the ultrathin high-shielding flexible circuit board; in the processing process, the auxiliary aluminum sheet is used for fixing and electroplating, so that the electroplating quality of the ultrathin flexible circuit board can be effectively improved, the auxiliary aluminum sheet is effectively removed by designing the processing flow, and the flexible circuit board is not additionally influenced; by utilizing the lamination processing characteristics of the lamination process, the parameters of the prepreg are adjusted, and special typesetting and processing for directly laminating the prepreg filling holes are performed at one time, so that a highly-efficient, highly-reliable and conveniently-processed filling hole process is formed; by attaching the shielding film, the shielding performance of the flexible circuit board can be effectively improved under the condition of ensuring that the thickness of the board does not exceed the standard; the whole processing technology has high reliability and simple and convenient processing, can effectively ensure that the thickness of the ultrathin high-shielding flexible circuit board does not exceed the standard, and has repeated bending performance and good shielding performance.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic cross-sectional structure diagram of a typical ultra-thin high-shielding flexible circuit board in the prior art;
FIG. 2 is a process flow diagram of a processing technique according to an embodiment of the present invention;
FIG. 3 is a detailed process flow diagram of the S50 process technique of FIG. 2 according to an embodiment of the present invention;
FIG. 4 is a schematic cross-sectional view of a flexible printed circuit board with circuit patterns according to an embodiment of the present invention;
FIG. 5 is a schematic cross-sectional view of a flexible board with through holes formed thereon according to an embodiment of the present invention;
FIG. 6 is a flow chart of a process for manufacturing an aluminum sheet auxiliary flexible sheet according to an embodiment of the present invention;
FIG. 7 is a schematic cross-sectional structure diagram of an auxiliary flexible plate made of aluminum sheets according to an embodiment of the present invention;
FIG. 8 is a schematic cross-sectional view of an aluminum sheet auxiliary flexible board after being electroplated according to an embodiment of the present invention;
FIG. 9 is a schematic cross-sectional view of a via hole flexible board according to an embodiment of the present invention;
FIG. 10 is a schematic cross-sectional view of a press-fit flexible board according to an embodiment of the present invention;
FIG. 11 is a schematic cross-sectional view of a flexible board processed to form an underfill fillet in accordance with an embodiment of the present invention;
FIG. 12 is a schematic cross-sectional view of a flexible board with a patterned surface according to an embodiment of the present invention;
FIG. 13 is a flow chart of an alternative process for forming a surface patterned flexible sheet in accordance with embodiments of the present invention;
FIG. 14 is a schematic front plan view of an exemplary glue-filled flexible panel of the present invention adhered to a supporting aluminum sheet;
FIG. 15 is a schematic view of a back side planar structure of an exemplary glue-filled flexible panel adhered to a supporting aluminum sheet;
FIG. 16 is a schematic cross-sectional view of an adhesive-filled flexible sheet according to an embodiment of the present invention adhered to a supporting aluminum sheet;
fig. 17 is a schematic cross-sectional structure diagram of an ultra-thin high-shielding flexible circuit board according to an embodiment of the present invention.
The reference numbers illustrate:
| reference numerals | Name(s) | Reference numerals | Name(s) |
| 010X | Prior art first cover film | 500 | Glue-filled flexible board |
| 020X | Prior art first shield copper layer | 510 | First-class glue prepreg layer |
| 030X | Prior art first dielectric layer | 520 | The first release film layer |
| 040X | Prior art is pureGlue layer | 530 | Second flow prepreg layer |
| 050X | Prior art layout of wiring layers | 540 | The second release film layer |
| 060X | Second insulating dielectric layer of the prior art | 550 | Third flow prepreg layer |
| 070X | Second shield copper layer of the prior art | 560 | Third release film layer |
| 080X | Secondary cover film of the prior art | 570 | Fourth gummosis prepreg layer |
| 100 | Circuit pattern flexible board | 580 | The fourth release film layer |
| 110 | Circuit wiring pattern | 5010 | Rivet |
| 120 | Copper-clad plate dielectric insulating layer | 5020 | First press-fit aluminum sheet |
| 130 | Auxiliary wiring pattern | 5030 | Second press aluminum sheet |
| 200 | Through-hole flexible board | 5110 | First through window area |
| 210 | Through hole | 5120 | Second window area |
| 300 | Aluminum sheet auxiliary flexible plate | 500A | Riveted flexible board |
| 330 | Open window electroplating auxiliary aluminum sheet | 500B | Laminated flexible board |
| 310 | First dry film layer | 2110A | Finished product glue filling conducting hole |
| 320 | Second dry film layer | 2120A | Non-glue-filling through hole |
| 3110 | Dry film pattern windowing | 500C | Unit flexible board |
| 3310 | Aluminium sheet | 500D | Through groove |
| 3320 | Coating strippable glue layer | 500E | Connection site |
| 3330 | Aluminum sheet protection dry film | 5040 | Aluminum support sheet |
| 3340 | Aluminum sheet open window area | 5040A | Support aluminum sheet layer |
| 330A | Auxiliary aluminum sheet for electroplating | 5040B | Micromucosal layer |
| 210A | Conducting hole | 5040C | Blue glue layer |
| 2110 | Glue filling via hole | 5040D | Hollow out area |
| 2120 | Non-filled via | 600 | Surface pattern flexible board |
| 330A | Auxiliary aluminum sheet for electroplating | 610 | Shielding film |
| 400 | Via hole flexible board | 10 | Ultrathin high-shielding flexible circuit board |
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all directional indicators (such as up, down, left, right, front, and back \8230;) in the embodiments of the present invention are only used to explain the relative positional relationship between the components, the motion situation, etc. in a specific posture (as shown in the attached drawings), and if the specific posture is changed, the directional indicators are changed accordingly.
In addition, descriptions such as "first", "second", etc. in the present invention are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
Referring to fig. 1, fig. 1 is a schematic cross-sectional structure diagram of a conventional ultrathin high-shielding flexible circuit board in the prior art.
In the prior art, in order to improve the shielding performance of the layout circuit layer of the flexible circuit board, considering the factors of processing technology difficulty, processing cost, product effect and the like, a three-layer circuit design is generally adopted, namely, a circuit copper layer is additionally designed on the upper surface and the lower surface of the layout circuit layer, and the circuit copper layer is used for graphic design to realize the shielding effect of the circuit copper layer on the layout circuit layer; while adding a circuit copper layer, functional layers such as a corresponding insulating dielectric layer, a covering film layer, a pure glue layer and the like are required to be added to manufacture an electroplating through hole, so that the requirements of conducting or mounting a multilayer circuit are met, electroplating treatment is required, and the whole thickness of the flexible circuit board is increased, and the possibility that the whole thickness exceeds the application standard range exists; in addition, when the three-layer flexible circuit board is processed, a double-sided copper-clad plate and a single-sided copper-clad plate or three single-sided copper-clad plates or a double-sided copper-clad plate, an insulating medium layer and a copper foil are required to be processed, and the processing difficulty is further increased.
Please refer to fig. 2, fig. 3 and fig. 4; FIG. 2 is a process flow diagram of a processing technique according to an embodiment of the present invention; FIG. 3 is a detailed process flow diagram of the S50 process technique of FIG. 2 according to an embodiment of the present invention; fig. 4 is a schematic cross-sectional structural diagram of a flexible board processed to form a circuit pattern according to an embodiment of the invention.
The processing procedure of the embodiment of the present invention is executed according to fig. 2 and 3, and fig. 4 is a schematic cross-sectional structure diagram of the processing result of step S10 in fig. 2, that is:
s10: the method comprises the steps of baking a double-sided flexible copper clad laminate which comprises a circuit copper layer and a shielding copper layer, carrying out copper reduction processing after baking is finished, then carrying out circuit pattern manufacturing processing, manufacturing a circuit wiring pattern 110 on the circuit copper layer, and manufacturing an auxiliary circuit wiring pattern 130 on the shielding copper layer to form the circuit pattern flexible board 100.
The baking adopted in the embodiment is baking at 140 ℃ for 30 min; the thickness of the double-sided flexible copper clad laminate is less than or equal to 70 mu m; and carrying out copper reduction processing on the double-sided flexible copper-clad plate, namely reducing the copper layer of the double-sided flexible copper-clad plate to 10-15 microns.
In this embodiment, a double-sided copper clad laminate is directly adopted, a circuit wiring pattern 110 is manufactured on one side to meet the requirement of the layout of the circuit pattern, some simple circuit patterns are designed and manufactured on one side of an auxiliary circuit wiring pattern 130, copper mesh patterns are manufactured on the other places simultaneously, or the copper mesh patterns are manufactured integrally, a main circuit can be formed on one side of the circuit wiring pattern 110, an auxiliary circuit is formed on one side of the auxiliary circuit wiring pattern 130, and a via hole or a mounting hole is manufactured to form a design which can meet the requirement of the layout circuit and can meet the requirement of the high-shielding characteristic pattern; the double-sided copper-clad plate is baked to remove internal stress, so that the stability of materials in the subsequent processing process is facilitated, and a processing coefficient can be accurately given, and because the copper-clad plate in the embodiment is thinner and generally 36-85 μm thick, the stress-removing baking cannot be carried out at high temperature or for a long time, the baking can be carried out at 140 ℃ for 30min generally, or at 100 ℃ for 60min or 120 ℃ for 40min generally; because the copper surface of the copper-clad plate is generally rolled copper, the copper-clad plate with the copper thickness exceeding the required standard is adopted, and then the copper is subjected to micro-etching to reduce the copper thickness to the required standard, so that the whole copper thickness of the rolled copper is more uniform, and a layer of uniform and clean rough surface is formed on the surface of the rolled copper, thereby facilitating the use of the subsequent process; in general, the copper thickness is reduced to 10 μm to 15 μm, preferably to 12 μm, 13 μm, or even to 8 μm thinner for special applications.
Referring to fig. 5, fig. 5 is a schematic cross-sectional structure diagram of a flexible board with through holes formed by processing according to an embodiment of the present invention; fig. 5 is a schematic cross-sectional structure diagram of the processing result of step S20 in fig. 2, that is:
s20: manufacturing a through hole 210 on the circuit pattern flexible board 100 to form a through hole flexible board 200; in this embodiment, the through hole is formed by drilling with a drill or punching with a laser.
The through holes are manufactured, on one hand, the conduction connection of double-sided circuits can be met, and on the other hand, the functional requirements for installation, insertion and the like of the flexible circuit board are met.
FIG. 6 is a flow chart of a process for forming an aluminum sheet auxiliary flexible plate according to an embodiment of the invention; fig. 7 is a schematic cross-sectional structural view of an auxiliary flexible plate made of aluminum sheets according to an embodiment of the present invention.
Fig. 6 and 7 show the processing procedure of step S30 in fig. 2, namely:
s30: attaching dry films to two sides of the through hole flexible board 200, making a dry film pattern windowing 3110, exposing the through hole 210, attaching a through hole electroplating auxiliary aluminum sheet 330 to the dry film on one side of the auxiliary circuit wiring pattern 130, wherein the size of the through hole electroplating auxiliary aluminum sheet 330 is larger than or equal to that of the through hole flexible board 200, an aluminum sheet through hole area 3340 is processed on the through hole electroplating auxiliary aluminum sheet 330, and the size of the aluminum sheet through hole area 3340 is unilateral larger than that of the dry film pattern windowing 3110; an aluminum sheet auxiliary flexible board 300 is integrally formed.
In this embodiment, the step of S30 further includes:
s310: taking an auxiliary aluminum sheet 3310, coating a strippable glue layer 3320 on one surface of the auxiliary aluminum sheet 3310, attaching an aluminum sheet protection dry film 3330 on the other surface, and performing exposure processing to form the electroplating auxiliary aluminum sheet 330A.
S320: and manufacturing an aluminum sheet opening window area 3340 on the electroplating auxiliary aluminum sheet 330A, wherein the aluminum sheet opening window area 3340 corresponds to the area of the dry film pattern windowing 3110 and is 10-50 mu m larger than the size of a single side of the area of the dry film pattern windowing 3110, and thus the electroplating auxiliary aluminum sheet 330 with the opening window is formed.
S330: one side of the open-window plated auxiliary aluminum sheet 300 coated with the peelable glue layer 3320 is attached to the dry film 320 on one side of the auxiliary wiring pattern 130 (in this embodiment, the dry film layer on one side of the auxiliary wiring pattern 130 is the second dry film layer 320, and the dry film layer on the other side is the first dry film layer 310), and the aluminum sheet auxiliary flexible sheet 300 is formed as a whole.
In the embodiment, the flexible circuit board is an ultra-thin flexible circuit board, and if electroplating is directly performed, the problems of uneven electroplating, electric leakage plating, tearing of the flexible circuit board and the like are easily caused, in the embodiment, an aluminum sheet is attached to the back of the flexible circuit board, the support property of the through-hole flexible board 200 is enhanced, and the peelable glue 3320 is attached to the auxiliary aluminum sheet 3310, so that the auxiliary aluminum sheet 3310 can form good adhesive bonding with the through-hole flexible board 200 and can be operated, the peelable glue 3320 can be an adhesive layer with a protective layer film, the protective layer film in the area needing to be attached is subjected to graphic processing and peeling, the peelable glue 3320 is exposed and then attached, the area needing not to be attached is covered by the protective layer film, and the peelable glue 3320 can be epoxy resin, polyurethane or polytetrafluoroethylene peelable glue; the aluminum sheet protective dry film 3330 is manufactured on the other side of the auxiliary aluminum sheet 3310, so that a high-precision film layer for effectively protecting the aluminum sheet can be formed, and the auxiliary aluminum sheet 3310 is protected on two sides, so that the aluminum sheet is prevented from being plated with copper in the electroplating process to influence the electroplating processing process; and the through holes 210 corresponding to the aluminum sheets and needing to be electroplated are windowed, so that the liquid medicine exchange of the through holes 210 in the electroplating process is ensured.
In the prior art, the flexible circuit board is electroplated by adopting full-board electroplating, that is, the whole board is electroplated, and then a pattern is manufactured, but the whole board is directly electroplated, so that the thickness of the flexible circuit board is greatly increased, and the bending performance of the flexible circuit board is reduced.
Referring to fig. 8 and 9, fig. 8 is a schematic cross-sectional structure diagram of an aluminum sheet auxiliary flexible board after being subjected to electroplating processing according to an embodiment of the present invention; FIG. 9 is a schematic cross-sectional view of a via hole flexible board according to an embodiment of the present invention; fig. 8 and 9 show the processing procedure of step S40 in fig. 2, namely:
s40: electroplating the aluminum sheet auxiliary flexible board 300 to enable the through hole 210 to be electroplated to form a through hole 210A, wherein the through hole 210A comprises a glue filling through hole 2110 and a non-glue filling through hole 2120, then micro-etching is carried out, and then the electroplating auxiliary aluminum sheet 330A is removed and film removing treatment is carried out to form the through hole flexible board 400.
In this embodiment, the aluminum sheet auxiliary flexible board 300 is subjected to electroplating processing and micro etching processing, in order to perform electroplating processing on the entire aluminum sheet auxiliary flexible board 300, the copper thickness of the inner wall of the through hole 210 formed by electroplating processing is greater than the finished copper thickness required by the predetermined processing data, and the micro etching processing is performed to perform copper reduction etching processing on the aluminum sheet auxiliary flexible board 300 after electroplating processing; the copper etching process is reduced to etch away a copper thickness of 3 μm to 8 μm.
In the electroplating process, the through hole 210 is electroplated to form the through hole 210A, and the side wall of the aluminum sheet open window region 3340 of the aluminum sheet is also electroplated with a copper layer, but because the copper layer electroplated on the side wall of the aluminum sheet open window region 3340 is thinner, and more recently, the thickness of the copper layer electroplated on the dry film at the combination position of the dry film (the second dry film layer 320) on one side of the auxiliary circuit wiring pattern 130 and the peelable glue layer 3320 is thinner (even the copper layer cannot be electroplated), therefore, the thickness of the electroplated layer is electroplated to be thicker than the thickness of the finished copper required by the set processing data, and the copper layer electroplated on the side wall of the aluminum sheet open window region 3340 can be etched away, and the copper layer electroplated on the second dry film layer 320 can be etched away, so as to ensure no copper connection exists between the flexible circuit board and the auxiliary aluminum sheet, and in the process of removing the electroplated copper is prepared, so as to prevent the problem of copper connection pulling in the aluminum sheet hole.
Referring to fig. 10 and 11, fig. 10 is a schematic cross-sectional structure diagram of a press-fit flexible board formed by processing according to an embodiment of the present invention; FIG. 11 is a schematic cross-sectional view of a flexible glue-filled plate according to an embodiment of the present invention; fig. 10 and 11 show the processing procedure of step S50 in fig. 2, namely:
s50: the via hole flexible board 400 is subjected to a filling process, which includes:
s510: and (3) arranging in an overlapping manner, wherein a first flow glue prepreg layer 510, a first release film layer 520, a second flow glue prepreg layer 530 and a second release film layer 540 are sequentially arranged on one surface of the circuit wiring pattern 110 of the via hole flexible board 400, and a third flow glue prepreg layer 550, a third release film layer 560, a fourth flow glue prepreg layer 570 and a fourth release film layer 580 are sequentially arranged on one surface of the auxiliary circuit wiring pattern 130 of the via hole flexible board 400, so as to form the overlapping flexible board.
S520: and riveting, namely riveting the stacked flexible board by using rivets 5010, wherein the rivets 5010 are positioned in the board edge area of each unit daughter board of the stacked flexible board, and the number of the rivets 5010 in the board edge area of each unit daughter board is more than or equal to 2, so that the riveted flexible board 500A is formed.
S530: and (3) pressing, namely, respectively arranging a first pressing aluminum sheet 5020 and a second pressing aluminum sheet 5030 on the two sides of the riveted flexible plate 500A, typesetting, and pressing to form a pressed flexible plate 500B.
S540: disassembling, cutting the laminated flexible board 500B, cutting off the position area of the rivet 5110, and removing the first release film layer 520, the second release film layer 530, the second release film layer 540, the third release film layer 550, the fourth release film layer 570 and the fourth release film layer 580 to form the glue-filled flexible board 500.
Because the flexible circuit board of this embodiment is thin, and for the via hole 2110 of filling with glue, the via hole needs to be solidized, in the prior art, the way of filling resin ink by screen printing is generally adopted to solidize the filled hole, and because the flexible circuit board is thin, the screen printing resin ink is easy to cause the expansion and shrinkage of the circuit board to exceed standards, even tear, and the screen printing resin ink overflows out of the hole, the polishing process needs to be performed, the polishing process of the ultrathin flexible circuit board needs to adjust the polishing tools and parameters with high precision, and needs to be backed by a firmer and smoother support layer, therefore, the polishing process of the ultrathin flexible circuit board is generally not feasible; therefore, the embodiment adopts direct one-time pressing, and the prepreg insulating layer (tape prepreg layer) is used to fill the underfill via 2110.
It should be noted that in this embodiment, the first flow-glue prepreg layer 510 and the third flow-glue prepreg layer 550 are respectively disposed on two sides of the via flexible board 400, so as to meet the requirement of the flexible circuit board itself for the insulating dielectric layer on one hand, and meet the requirement of filling the via 2110 with the flow-glue on the other hand.
The first release film layer 520 and the third release film layer 560 are respectively arranged on two sides of the first flow-glue prepreg layer 510 and the third flow-glue prepreg layer 550, so that the laminating effect of the first flow-glue prepreg layer 510 and the third flow-glue prepreg layer 550 can be effectively guaranteed, and the separation after lamination can be well realized.
And set up second gummosis prepreg layer 530 and fourth gummosis prepreg layer 570, because the flexible circuit board is thinner, so set up and can prevent that the pressfitting dynamics from producing to the flexible circuit board and dragging deformation, harmomegathus excessively, the torn problem of pressfitting even, play good cushioning effect to can play fine additional effect for the underfill of underfill conducting hole 2110.
The second release film layer 540 and the fourth release film layer 580 are further arranged, so that a good leveling effect can be achieved, and the adhesive of the gummosis prepreg and the pressing lamination structure can be prevented.
After the unit boards and the whole board are stacked, rivets 5010 are used for riveting the periphery of each unit board and the whole board, the number of the rivets 5010 forming the board edge area of each unit sub-board is larger than or equal to 2, and due to the fact that the number of release layers in the typesetting structure is large, the rivets 5010 can effectively guarantee that the problems of deviation, pressing sliding plates and the like cannot occur in pressing, and the pressing quality of each unit board is guaranteed.
During the pressfitting, set up the aluminium lamella to riveting flexible sheet 500A's two sides, utilize the heat conduction of aluminium lamella, certain constraint nature, good compliance, can fully guarantee the filler of filler conducting hole 2110 to and the holistic pressfitting effect of flexible circuit board.
Because the release layer is arranged between layers needing to be separated in the typesetting structure, the press-fit typesetting structure can be easily separated only by punching or milling the riveting position during disassembly, and the glue-filled flexible board 500 is removed.
In the present embodiment, the first prepreg layer 510 of S510 is set according to the thickness requirement of the predetermined processing data of the ultra-thin high shielding flexible printed circuit board.
The first flow glue prepreg layer 510 is provided with a first through window area 5110, and the first through window area 5110 corresponds to the non-glue-filled via hole 2120 and is a certain distance greater than the single side of the non-glue-filled via hole 2120; typically 30 μm to 100 μm larger.
The first release film layer 520 is provided with a second through hole area 5120, and the second through hole area 5120 is arranged corresponding to the glue filling through hole 2110 and is a certain distance greater than the single side of the glue filling through hole 2110; typically 30 μm to 100 μm larger.
The third flow-through prepreg layer 550 is the same in structure as the first flow-through prepreg layer 510.
The third release film layer 560 has the same structure as the first release film layer 520.
It should be noted that the first flow-through prepreg layer 510 and the third flow-through prepreg layer 550 are not only used as the glue filling prepregs for filling the glue filling via hole 2110, but also used as the insulating dielectric layer of the flexible printed circuit board, and have a dual-purpose function, so that the first flow-through prepreg layer 510 and the third flow-through prepreg layer 550 are both set according to the thickness requirement of the predetermined processing data, that is, according to the thickness of the insulating dielectric layer after lamination, the compensation of lamination processing is performed.
And a window needs to be opened in the area of the non-filling via 2120 of the first flow-glue prepreg layer 510 and the third flow-glue prepreg layer 550 to prevent the flow-glue of the flow-glue prepreg from flowing into the non-filling via 2120.
The positions of the glue filling via holes 2110 corresponding to the first release film layer 520 and the third release film layer 560 are windowed, so that the glue of the second flow glue prepreg layer 530 and the fourth flow glue prepreg layer 570 can flow to the first flow glue prepreg layer 510 and the third flow glue prepreg layer 550 through the windowed areas, and the glue filling compensation is performed on the first flow glue prepreg layer 510 and the third flow glue prepreg layer 550, so that the glue filling via holes 2110 can be fully filled, and the problem that the plate surface is sunken and the like is caused due to the fact that the insulating medium layer is not uneven in thickness is solved.
The second runner prepreg layer 530, the fourth runner prepreg layer 570, the second release film layer 540 and the fourth release film layer 580 are all provided with no windows.
The sizes of the first flow prepreg layer 510, the first release film layer 520, the second flow prepreg layer 530, the third flow prepreg layer 550, the third release film layer 560 and the fourth flow prepreg layer 570 are equal to the size of the via flexible board 400.
The size of the second release film layer 540 and the fourth release film layer 580 is larger than the size of the via hole flexible board 400, generally 1.0mm to 3.0mm larger.
The sizes of the release film layers of the top layer and the bottom layer of the typesetting are larger, glue overflow of the flowing glue prepreg layers during the pressing can be effectively prevented, the typesetting structure is polluted, and the pressing is influenced.
The gel content of the first gummy prepreg layer 510, the second gummy prepreg layer 530, the third gummy prepreg layer 550 and the fourth gummy prepreg layer 570 is more than or equal to 65 percent, and the gel overflow amount under the pressing condition is less than or equal to 0.2mm.
Each glue flowing prepreg layer adopts higher glue content, and the prepreg with lower glue overflowing amount is controlled, so that the effects of pressing and filling glue and filling the glue through hole 2110 can be effectively ensured, and excessive glue overflowing of the prepreg layers can be prevented.
In one embodiment, the thickness of the second release film layer 540 is greater than the first release film layer 520; the thickness of the fourth release film layer 570 is greater than that of the third release film layer 560; the thicknesses of the first release film layer 520 and the third release film layer 560 are 10 μm to 50 μm, respectively, and preferably may be 30 μm, 40 μm, and 50 μm.
The first release film layer 520 and the third release film layer 560 are thinner, which is beneficial to the second flow glue prepreg layer 530 and the fourth flow glue prepreg layer 570 to supplement the flow glue through the opening window area on the release film, and is convenient for stripping.
In the embodiment, the pressing is vacuum pressing, and before the pressing, cold pressing is performed at normal temperature for 30min, wherein the pressure is 160PSI to 220PSI; and after the pressing is finished, cold pressing is carried out for 30min at normal temperature, and the pressure is 160PSI to 220PSI.
The cold pressing time is increased for a certain time before and after the pressing, so that the stress formed in the pressing can be effectively released, and the uneven pressing expansion and shrinkage or exceeding of the expansion and shrinkage of the ultrathin flexible circuit board can be prevented.
Referring to fig. 12, fig. 12 is a schematic cross-sectional structure diagram of a flexible board with a surface pattern according to an embodiment of the invention; fig. 12 shows the processing procedure of step S60 in fig. 2, namely:
s60: the flexible board 500 is processed by laser ablation and pattern etching to form a surface pattern flexible board 600.
After the disassembly, since the glue filling via hole 2110 is filled with the glue of the prepreg, and since the opening window regions of the first release film layer 520 and the third release film layer 560 are reserved, the glue of the prepreg of the glue filling via hole 2110 may be higher than the board surface, as shown in fig. 11, the glue of the prepreg needs to be removed, but the glue cannot be polished in a practical polishing manner due to the thin board thickness.
Referring to fig. 13 and 14, and fig. 15 and 16, fig. 13 is a flow chart of an alternative process for forming a surface pattern flexible board according to an embodiment of the present invention; FIG. 14 is a schematic front plan view of an exemplary glue-filled flexible panel of the present invention adhered to a supporting aluminum sheet; FIG. 15 is a schematic diagram of a back side plan view of an adhesive-filled flexible sheet of an embodiment of the present invention adhered to a supporting aluminum sheet; fig. 16 is a schematic cross-sectional view of a flexible glue-filled plate adhered to a supporting aluminum sheet according to an embodiment of the present invention.
In this embodiment, S60 further includes:
s610: carry out laser ablation to the flexible board 500 that glues fills, then at the side of the unit flexible board 500C that the correspondence of flexible board 500 glues, die-cut logical groove 500D to keep certain connection position 500E, connection position 500E makes the whole fixed connection of unit flexible board 500C on the flexible board 500 that glues fills.
According to the appearance of the unit flexible board 500C, the through groove 500D is punched on the side edge, so that the stress of the unit flexible board 500C can be effectively removed, and the connecting position 500E prevents the unit flexible board 500C from falling off, that is, the through groove 500D is only used for punching and processing the part between the unit flexible board 500C and the flexible circuit board body; and the connection position 500E is required to ensure that the unit flexible board 500C forming the through groove 500D does not have any state that one end of the unit flexible board is suspended.
S620: manufacturing a supporting aluminum sheet 5040, taking a supporting aluminum sheet 5040A, wherein the size of a single side of the supporting aluminum sheet 5040A is larger than that of the glue-filled flexible plate 500, adhering a micro-adhesive film layer 5040B and a blue glue layer 5040C to two sides of the supporting aluminum sheet 5040A respectively to form a film-covered supporting aluminum sheet, and manufacturing a hollow-out area 5040D to form the supporting aluminum sheet 5040 according to the distribution and the appearance of the corresponding unit flexible plate 500C and the single side of the film-covered supporting aluminum sheet by enlarging a certain distance; the unilateral magnification is typically 30 μm to 100 μm.
The glue-filled flexible board 500 is reinforced and supported by the supporting aluminum sheets 5040, and the glue-filled flexible board 500 is processed to form a unit flexible board 500C, so that the tearing problem of the glue-filled flexible board 500 in the processing processes of etching and the like can be effectively prevented; bonding the supporting aluminum sheet 5040 and the glue-filled flexible plate 500 by using a micro-adhesive film, wherein the micro-adhesive film can be selected, and the micro-adhesive film with a protective film layer attached to the surface is adopted to window the protective film layer at the position to be attached and attach the protective film layer to form an effective integral processing structure; the hollowed-out area 5040D of the supporting aluminum sheet 5040 can be effectively matched with the through groove 500D, the glue filling flexible plate 500 is attached to the back of the supporting aluminum sheet 5040, and a certain vacant area is formed between the hollowed-out area 5040D and the through groove 500D, so that liquid medicine can be fully exchanged in subsequent processing processes such as etching processing and the like, and the flexible plate 500C of the unit cannot be broken by washing.
S630: and attaching one surface of the micro adhesive film layer 5040B of the supporting aluminum sheet 5040 to the glue filling flexible plate 500 in an aligned mode, wherein the hollow area 5040D corresponds to the unit flexible plate 500C, and thus the flexible plate with the supporting aluminum sheet attached is formed.
S640: the flexible board with the back attached supporting aluminum sheet is subjected to pattern etching processing, and then the supporting aluminum sheet 5040 is removed to form the flexible board 600 with the surface pattern.
Since the aluminum support 5040 is protected by the micro-adhesive film layer and the blue adhesive layer, and the etching effect of the etching solution on the aluminum support 5040 is limited, the aluminum support 5040 is not excessively damaged by etching.
Referring to fig. 17, fig. 17 is a schematic cross-sectional structure diagram of an ultra-thin high-shielding flexible circuit board according to an embodiment of the present invention; fig. 17 shows the processing procedure of step S70 in fig. 2, namely:
s70: processing the surface pattern flexible board 600 by attaching the shielding film 610 to form the ultrathin high-shielding flexible circuit board 10; in the present embodiment, the thickness of the ultra-thin high-shielding flexible circuit board 10 is not more than 130 μm.
In this embodiment, the shielding film 610 is attached to the surface pattern flexible board 600 to meet and increase the shielding performance of the flexible circuit board, and the shielding film 610 generally has a relatively thin thickness and a relatively high flexibility, so as to meet the requirements of the flexible circuit board on ultra-thin characteristics and high flexibility; when the shielding film 610 is attached, windowing processing needs to be performed on the shielding film 610 according to a required attachment pattern, and rapid pressing attachment is adopted to form a good processing effect; through the processing, the thickness of the flexible circuit board can be less than 130 mu m.
It should be noted that, because there are different situations of design, processing and application of the flexible circuit board in the actual processing process and application process, the drawings of this embodiment are only used for illustrating the implementation process of this embodiment, and do not represent the size ratio of the actual product, nor represent the drawings which are enlarged in equal proportion according to the actual situation.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A manufacturing method of an ultrathin high-shielding flexible circuit board is characterized by comprising the following steps:
s10: taking a double-sided flexible copper clad laminate, wherein the double-sided flexible copper clad laminate comprises a circuit copper layer and a shielding copper layer, baking the double-sided flexible copper clad laminate, performing copper reduction processing after baking is completed, then performing circuit pattern manufacturing processing, manufacturing a circuit wiring pattern on the circuit copper layer, and manufacturing an auxiliary circuit wiring pattern on the shielding copper layer to form a circuit pattern flexible board;
s20: manufacturing a through hole on the circuit pattern flexible board to form a through hole flexible board;
s30: attaching dry films to two sides of the through hole flexible plate, performing windowing of dry film patterns to expose the through holes, attaching an opening window electroplating auxiliary aluminum sheet to the dry film on one side of the auxiliary circuit wiring pattern, wherein the size of the opening window electroplating auxiliary aluminum sheet is larger than or equal to that of the through hole flexible plate, an aluminum sheet opening window area is processed on the opening window electroplating auxiliary aluminum sheet, and the size of the aluminum sheet opening window area is unilateral larger than that of the dry film pattern opening window; integrally forming an aluminum sheet auxiliary flexible plate;
s40: electroplating the aluminum sheet auxiliary flexible plate to enable the through hole to be electroplated to form a via hole, carrying out micro-etching processing on the via hole comprising a glue filling via hole and a non-glue filling via hole, then removing the electroplated auxiliary aluminum sheet, and carrying out film removal processing to form a via hole flexible plate;
s50: and carrying out glue filling processing treatment on the conducting hole flexible plate, wherein the glue filling processing treatment comprises the following steps:
s510: arranging a first flow adhesive prepreg layer, a first release film layer, a second flow adhesive prepreg layer and a second release film layer on one surface of the circuit wiring pattern of the via hole flexible board in sequence, and arranging a third flow adhesive prepreg layer, a third release film layer, a fourth flow adhesive prepreg layer and a fourth release film layer on one surface of the auxiliary circuit wiring pattern of the via hole flexible board in sequence to form an arranging flexible board;
s520: riveting, namely riveting the stacked flexible board by using rivets, wherein the positions of the rivets are positioned in the board edge areas of the unit sub-boards of the stacked flexible board, and the number of the rivets in the board edge areas of the unit sub-boards is more than or equal to 2, so that the riveted flexible board is formed;
s530: pressing, namely arranging a first pressing aluminum sheet and a second pressing aluminum sheet on two sides of the riveting flexible plate respectively, typesetting, and pressing to form a pressing flexible plate;
s540: disassembling, namely cutting the laminated flexible board, cutting off the position area of the rivet, and disassembling the first release film layer, the second flow glue prepreg layer, the second release film layer, the third release film layer, the fourth flow glue prepreg layer and the fourth release film layer to form a glue-filled flexible board;
s60: carrying out laser ablation and pattern etching processing on the glue-filled flexible board to form a surface pattern flexible board;
s70: and carrying out attached shielding film processing on the surface pattern flexible board to form the ultrathin high-shielding flexible circuit board.
2. The method for manufacturing an ultra-thin high-shielding flexible circuit board of claim 1, wherein the baking of S10 is performed with baking parameters of 140 ℃ for 30 min.
3. The method for manufacturing the ultrathin high-shielding flexible circuit board as claimed in claim 1, wherein the thickness of the double-sided flexible copper clad plate of S10 is less than or equal to 70 μm; and carrying out copper reduction processing on the double-sided flexible copper clad laminate, namely thinning the copper layer of the double-sided flexible copper clad laminate to 10-15 mu m.
4. The method for manufacturing an ultra-thin high-shielding flexible circuit board according to claim 1, wherein the S30 comprises:
s310: taking an auxiliary aluminum sheet, coating a strippable adhesive layer on one surface of the auxiliary aluminum sheet, attaching an aluminum sheet protection dry film on the other surface of the auxiliary aluminum sheet, and performing exposure processing to form an electroplating auxiliary aluminum sheet;
s320: manufacturing the aluminum sheet windowing region for the electroplating auxiliary aluminum sheet, wherein the aluminum sheet windowing region corresponds to the dry film pattern windowing region and is 10-50 mu m larger than the size single side of the dry film pattern windowing region to form an opening window electroplating auxiliary aluminum sheet;
s330: and attaching one surface of the opening window electroplating auxiliary aluminum sheet coated with the peelable adhesive layer to the dry film on one surface of the auxiliary circuit wiring pattern to form the aluminum sheet auxiliary flexible plate.
5. The method of claim 4, wherein the step S40 is performed by electroplating the aluminum sheet auxiliary flexible board and performing micro etching, and in order to perform electroplating on the entire aluminum sheet auxiliary flexible board, the copper thickness of the inner wall of the through hole formed by electroplating is greater than the finished copper thickness required by the predetermined processing data, and the micro etching is performed by performing copper reduction etching on the aluminum sheet auxiliary flexible board after the electroplating.
6. The method as claimed in claim 5, wherein the copper reducing etching process is etching away a copper thickness of 3 μm to 8 μm.
7. The method according to claim 1, wherein the first prepreg layer in S510 is set according to thickness requirements of predetermined processing data of the ultra-thin high shielding flexible printed circuit board;
the first flow glue prepreg layer is provided with a first through window area, and the first through window area corresponds to the non-glue-filling conducting hole and is larger than the single side of the non-glue-filling conducting hole by a certain distance;
the first release film layer is provided with a second through window area, and the second through window area is arranged corresponding to the glue filling through hole and is a certain distance greater than the single side of the glue filling through hole;
the third flow glue prepreg layer has the same structure as the first flow glue prepreg layer;
the third release film layer has the same structure as the first release film layer;
the second gumming prepreg layer, the fourth gumming prepreg layer, the second release film layer and the fourth release film layer are not provided with windows;
the sizes of the first gummy prepreg layer, the first release film layer, the second gummy prepreg layer, the third release film layer and the fourth gummy prepreg layer are equal to the size of the via hole flexible board;
the size of the second release film layer and the fourth release film layer is unilateral larger than that of the via hole flexible plate;
the gel content of the first gummy prepreg layer, the second gummy prepreg layer, the third gummy prepreg layer and the fourth gummy prepreg layer is not less than 65%, and the gel overflow amount under the pressing condition is not more than 0.2mm.
8. The method for manufacturing an ultra-thin high-shielding flexible circuit board according to claim 1, wherein the pressing in S530 is vacuum pressing, and before the pressing, cold pressing is performed at normal temperature for 30min, and the pressure is 160PSI to 220PSI; and after the pressing is finished, cold pressing at normal temperature for 30min, wherein the pressure is 160PSI to 220PSI.
9. The method for manufacturing an ultra-thin high shielding flexible circuit board according to claim 1, wherein the glue-filled flexible board is subjected to laser ablation and pattern etching processing in step S60 to form a surface pattern flexible board:
s610: performing laser ablation on the glue-filled flexible board, then punching a through groove on the side edge of the corresponding unit flexible board of the glue-filled flexible board, and reserving a certain connecting position, wherein the connecting position enables the unit flexible board to be integrally and fixedly connected to the glue-filled flexible board;
s620: manufacturing a supporting aluminum sheet, taking the supporting aluminum sheet layer, wherein the size of a single side of the supporting aluminum sheet layer is larger than that of the glue filling flexible plate, adhering a micro-adhesive film layer and a blue glue layer to two sides of the supporting aluminum sheet layer respectively to form a coated supporting aluminum sheet, performing unilateral amplification on the coated supporting aluminum sheet for a certain distance according to the distribution and the appearance of the corresponding unit flexible plate, and manufacturing a hollow area to form the supporting aluminum sheet;
s630: attaching one surface of the micro-adhesive film layer of the supporting aluminum sheet to the glue filling flexible plate in an aligned mode, wherein the hollow area corresponds to the unit flexible plate to form a flexible plate with a back attached supporting aluminum sheet;
and S640: and carrying out pattern etching processing on the flexible plate with the back attached supporting aluminum sheet, and then removing the supporting aluminum sheet to form the flexible plate with the surface pattern.
10. The method for manufacturing the ultrathin high-shielding flexible circuit board as claimed in claim 1, wherein the thickness of the ultrathin high-shielding flexible circuit board is less than or equal to 130 μm.
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| CN115666016B (en) | 2024-04-09 |
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