CN114900998A - Multilayer circuit board and processing method thereof - Google Patents
Multilayer circuit board and processing method thereof Download PDFInfo
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- CN114900998A CN114900998A CN202210635766.1A CN202210635766A CN114900998A CN 114900998 A CN114900998 A CN 114900998A CN 202210635766 A CN202210635766 A CN 202210635766A CN 114900998 A CN114900998 A CN 114900998A
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- 238000003672 processing method Methods 0.000 title claims abstract description 12
- 230000001681 protective effect Effects 0.000 claims abstract description 88
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 64
- 239000010949 copper Substances 0.000 claims abstract description 63
- 229910052802 copper Inorganic materials 0.000 claims abstract description 63
- 238000000034 method Methods 0.000 claims abstract description 50
- 238000010030 laminating Methods 0.000 claims abstract description 15
- 239000003292 glue Substances 0.000 claims description 44
- 239000000853 adhesive Substances 0.000 claims description 38
- 230000001070 adhesive effect Effects 0.000 claims description 38
- 238000012545 processing Methods 0.000 claims description 22
- 238000005520 cutting process Methods 0.000 claims description 11
- 238000004080 punching Methods 0.000 claims description 8
- 238000003825 pressing Methods 0.000 claims description 6
- 239000002390 adhesive tape Substances 0.000 abstract description 10
- 239000010410 layer Substances 0.000 description 193
- 230000008569 process Effects 0.000 description 24
- 238000013461 design Methods 0.000 description 8
- 238000003475 lamination Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 239000000758 substrate Substances 0.000 description 7
- 239000004642 Polyimide Substances 0.000 description 5
- 238000005452 bending Methods 0.000 description 5
- 229920001721 polyimide Polymers 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 description 3
- 229910001431 copper ion Inorganic materials 0.000 description 3
- 238000005530 etching Methods 0.000 description 3
- 238000012805 post-processing Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 238000003698 laser cutting Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000013508 migration Methods 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 description 2
- 239000005020 polyethylene terephthalate Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 230000032798 delamination Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000007849 functional defect Effects 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000001020 plasma etching Methods 0.000 description 1
- 239000011120 plywood Substances 0.000 description 1
- 229920006267 polyester film Polymers 0.000 description 1
- -1 polyethylene terephthalate Polymers 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 229910000679 solder Inorganic materials 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Images
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
- H05K3/4644—Manufacturing multilayer circuits by building the multilayer layer by layer, i.e. build-up multilayer circuits
-
- 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
- H05K1/02—Details
- H05K1/0213—Electrical arrangements not otherwise provided for
-
- 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
- H05K1/02—Details
- H05K1/0296—Conductive pattern lay-out details not covered by sub groups H05K1/02 - H05K1/0295
- H05K1/0298—Multilayer circuits
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 multilayer circuit board and a processing method thereof, wherein the processing method of the multilayer circuit board comprises the following steps: the method comprises the steps of aligning and attaching an inner layer protective film on a double-sided board with an inner layer circuit to form the double-sided board with the inner layer protective film, attaching, laminating and baking a copper adhesive tape board and the double-sided board with the inner layer protective film, arranging an outer layer circuit on a single-sided board of the multilayer board, aligning, laminating and baking the processed multilayer board and the outer layer protective film until the outer layer protective film is completely cured, wherein a second opening is formed in an uncovering area of the outer layer protective film, the shape of the second opening is the same as the uncovering area, the width of the single-side uncovered area is smaller than a second preset length, and the difference value between the second preset length and the preset distance is larger than 0.
Description
Technical Field
The invention belongs to the technical field of flexible circuit boards, and particularly relates to a multilayer circuit board and a processing method thereof.
Background
A Flexible Printed Circuit (FPC) is a highly reliable and excellent Flexible Printed Circuit board made of a polyimide or polyester film as a base material. The high-density light-weight LED lamp has the characteristics of high wiring density, light weight, thin thickness and good bending property. The flexible circuit board can move and stretch in a three-dimensional space, three-dimensional wiring of a circuit is realized, the integration degree of component assembly connection is improved, the product volume is reduced, and high stability is kept, so that the FPC can be widely applied to industries such as mobile phones, computers, mobile peripherals, vehicle-mounted electronics and the like.
With the updating of electronic products, the number of three or more layers of multi-layer FPCs is gradually increasing to meet the functional requirements of high density. The higher the number of layers and the thicker the thickness of the flexible circuit board are, the poorer the bending performance is, and the reliability can not meet the requirement. In order to keep balance between the multi-functionality and the flexibility, a local layer reduction design is usually developed at a position where the multi-layer FPC needs to be bent, and an outer layer circuit board in a specific area is cut and peeled by a laser or punching process or the like, so that a local single-layer or double-layer structure is realized, the bending performance of the circuit board is improved, and the layer reduction area is also called a de-cap area.
At present, the prior art mainly adopts a rear cover opening process, namely, picosecond laser is used for cutting an outer layer copper foil, and in order to avoid the phenomenon of glue flowing caused by the fact that inner layer glue (bonding glue) is heated and melted in the laser process, the opening of the glue is usually shrunk by 0.1mm before the outer layer is attached; after the processes of hot rolling glue, laminating by a laminating machine and laser uncapping, the distance between the edge of the inner layer glue and the edge of the uncapping area is 60-140 mu m; after the protective film is subjected to fast pressing treatment, the protective film is well filled with the inner layer circuit, and the risk of inner layer gaps is low; however, if a lamination parameter with a larger pressure is used, the protective film adhesive is usually backfilled by 80-110um, and the possibility that the two types of adhesives are not contacted to cause a gap still exists, so that the insulation performance of the inner layer and the outer layer of the FPC is influenced, and under a long-time voltage load, the risk that copper ions migrate and grow in the gap exists, so that the FPC has poor functions such as spark testing (spark), short circuit and the like.
Disclosure of Invention
Therefore, the invention aims to solve the technical problem of poor functions such as spark test failure or short circuit caused by gaps in the uncovering area of the inner layer circuit of the flexible circuit board in the prior art.
In order to solve the above technical problems, the present invention provides a method for processing a multilayer circuit board, including the steps of:
step S100, attaching an inner layer protection film on a double-sided board with an inner layer circuit in an aligned mode to form the double-sided board with the inner layer protection film, wherein the shape of the inner layer protection film is the same as that of a cover opening area, and the width of the cover opening area with a single side opposite to the cover opening area is larger than a first preset length;
step S200, attaching a copper adhesive tape plate and a double-sided board with an inner-layer protective film, laminating and baking the copper adhesive tape plate and the double-sided board to enable the inner-layer adhesive in the copper adhesive tape plate to be melted and overflow and to fill the inner-layer circuit together with the inner-layer protective film in a molten state to obtain a multilayer board, wherein the copper adhesive tape plate comprises the inner-layer adhesive and a single-sided board which are laminated together, a first opening is formed in the copper adhesive tape plate, and the size and shape of the first opening are the same as those of the uncapped area;
step S300, arranging and forming an outer layer circuit on the single panel of the multilayer board, wherein a preset distance is reserved between the outer layer circuit and the edge of the open cover area;
step S400, the multilayer board processed in the step S300 is aligned with an outer layer protective film, laminated and baked until the outer layer protective film is completely cured, wherein a second opening is formed in the uncovering area of the outer layer protective film, the shape of the second opening is the same as that of the uncovering area, the width of the single side of the second opening, which is larger than the uncovering area, is smaller than a second preset length, and the difference between the second preset length and the preset distance is larger than 0.
Preferably, in the method for processing the multilayer circuit board, the difference between the second preset length and the preset distance is Δ L, and Δ L is 0.2 ± 0.1 mm.
Preferably, in the processing method of the multilayer circuit board, the preset distance is D, and D is 0.45 ± 0.1 mm.
Preferably, in the method for processing a multilayer wiring board, before the step S100, the method further includes the steps of:
and (3) attaching the protective film to the carrier film, and punching to obtain the inner protective film which has the same shape as the uncapped area and has the width of the single-edge opposite to the uncapped area with the first preset length.
Preferably, in the processing method of the multilayer circuit board, the first preset length is L1, and L1 is 0.70 ± 0.1 mm.
Preferably, in the method for processing a multilayer wiring board, before the step S200, the method further includes the steps of:
and sequentially attaching and pressing the inner layer glue and the single panel to form the copper glue board, and cutting the uncapping area of the copper glue board to form a first opening, wherein the size and the shape of the first opening are the same as those of the uncapping area.
Preferably, in the method for processing a multilayer wiring board, before the step S400, the method further includes the steps of:
and cutting the outer-layer protective film in the uncovering area to form a second opening, wherein the shape of the second opening is the same as that of the uncovering area, and the width of the single side of the second opening, which is larger than that of the uncovering area, is smaller than a second preset length.
Preferably, in the method for processing the multilayer circuit board, the second preset length is L2, and L2 is 0.25 ± 0.1 mm.
The present invention also provides a multilayer wiring board comprising:
the double-panel layer comprises an inner-layer protective film and a double-panel, wherein the inner-layer protective film and the double-panel are sequentially attached and laminated from a first direction, an inner-layer circuit is formed on the double-panel, the shape of the inner-layer protective film is the same as that of the uncapping area, and the width of the uncapping area with one side opposite to the uncapping area is greater than a first preset length;
the copper rubber plate is attached and laminated on the double-panel layer along a first direction and comprises an inner layer rubber and a single-panel, the inner layer rubber and the single-panel are sequentially attached and laminated along the first direction, an external circuit is arranged on the single-panel, a first opening is formed in the copper rubber plate, the size and the shape of the first opening are the same as those of the uncapped area, the inner layer rubber and the inner layer protective film jointly fill the internal circuit, and the distance between the outer layer circuit and the edge of the uncapped area is preset;
the outer protection film, along first direction laminating and laminating on the copper offset plate, the second opening has been seted up at the region of uncapping to outer protection film, the shape of second opening is the same with the region of uncapping, and unilateral regional width of uncapping is less than the second and predetermines length, the second is predetermine length and is less than predetermine the distance.
Preferably, in the multilayer circuit board, the difference between the second preset length and the preset distance is Δ L, and Δ L is 0.2 ± 0.1 mm; wherein,
the preset distance is D, and D is 0.45 +/-0.1 mm; and/or the presence of a gas in the atmosphere,
the second preset length is L2, and L2 is 0.25 +/-0.1 mm; and/or the presence of a gas in the atmosphere,
the first preset length is L1, and L1 is 0.70 +/-0.1 mm.
The technical scheme provided by the invention has the following advantages:
according to the invention, the inner-layer protective film is added in the uncovering area, the inner-layer glue retraction design is simultaneously cancelled, and the inner-layer glue is attached to the outer-layer single-sided board for post-processing, so that the fusion of the inner-layer glue and the inner-layer protective film glue is ensured, and the poor functions of spark test failure or short circuit and the like caused by the gap in the uncovering area of the inner-layer circuit are avoided;
further, the invention forms the double-sided board with the inner layer protective film by attaching the inner layer protective film on the double-sided board with the inner layer circuit in an aligned mode, wherein the shape of the inner layer protective film is the same as the shape of a cover opening area, the width of a single-side opposite cover opening area is larger than a first preset length, a copper adhesive tape board and the double-sided board with the inner layer protective film are attached and laminated and baked, so that inner layer adhesive in the copper adhesive tape board is melted and overflowed and fills the inner layer circuit together with the inner layer protective film in a molten state, a multilayer board is obtained, wherein the copper adhesive tape board comprises the inner layer adhesive and a single-sided board which are laminated together, the copper adhesive tape board is provided with a first opening, the size and the shape of the first opening are the same as the cover opening area, an outer layer circuit is arranged and formed on the single-sided board of the multilayer board, and the distance between the outer layer circuit and the edge of the cover opening area is preset distance, aligning and laminating the processed multilayer board and an outer layer protective film, and baking until the outer layer protective film is completely solidified, wherein a second opening is formed in the uncovering area of the outer layer protective film, the shape of the second opening is the same as that of the uncovering area, the width of a single side of the second opening, which is larger than that of the uncovering area, is smaller than a second preset length, the difference value between the second preset length and the preset distance is larger than 0, so that inner layer glue in the copper glue board is melted and overflows and fills the inner layer circuit together with the inner layer protective film in the molten state, and the size of the outer layer protective film, which is larger than that of the single side of the outer layer circuit, is larger by DeltaL, and the circuit is ensured to be completely coated in the protective film;
furthermore, the protective film is split into an inner layer and an outer layer, and the protective film is processed on the surface of the circuit board before and after the inner layer adhesive is attached, so that the filling stability of the adhesive in the uncapping area of the multilayer flexible circuit board is improved, the bad phenomena of copper ion migration and the like caused by incomplete filling of the adhesive are avoided, and the yield and the stability of the product are improved;
furthermore, the invention increases the cover opening design of the outer protective film and reduces the overall thickness of the cover opening area of the multilayer board.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments or the technical solutions in the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a cross-sectional view of a prior art multilayer wiring board;
FIG. 2 is a cross-sectional view of one embodiment of a double-sided board provided by the present invention;
FIG. 3 is a cross-sectional view of one embodiment of a double-sided board with inner layer traces according to the present invention;
FIG. 4 is a cross-sectional view of the double-sided board with inner layer circuit of FIG. 3 after an inner layer protection film is attached;
FIG. 5 is a cross-sectional view of the copper rubber plate with the first opening provided therein according to the present invention;
FIG. 6 is a cross-sectional view of one embodiment of a multi-layer board provided by the present invention;
FIG. 7 is a cross-sectional view of one embodiment of the multi-layer board of FIG. 6 provided with outer layer traces;
FIG. 8 is a cross-sectional view of the multi-layer board of FIG. 7 after being attached to an outer protective film;
fig. 9 is a schematic flow chart of an embodiment of a method for processing a multilayer circuit board according to the present invention.
Description of prior art reference numerals:
| reference numerals | Name (R) | Reference numerals | Name (R) |
| 100’ | Multilayer circuit board | 3’ | Copper rubber plate |
| 1’ | |
31’ | Inner layer glue |
| 2’ | Double-sided board | 32’ | Single panel |
| 21’ | A first copper layer | 321’ | Third copper layer |
| 22’ | A first substrate | 322’ | Second radicalWood material |
| 23’ | Second copper layer | 4’ | Gap |
Description of the reference numerals of the invention:
| reference numerals | Name (R) | Reference numerals | Name (R) |
| 100 | |
32 | |
| 1 | Inner |
321 | Third copper layer |
| 2 | Double- |
322 | Second base material |
| 21 | A |
33 | First opening |
| 22 | A |
4 | Outer |
| 23 | |
5 | |
| 3 | Copper rubber plate | 6 | |
| 31 | Inner layer glue |
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 of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. The invention will be described in detail hereinafter with reference to the accompanying drawings in conjunction with embodiments. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.
In the present invention, unless specified to the contrary, use of the terms of orientation such as "upper, lower, top, bottom" or the like, generally refer to the orientation as shown in the drawings, or to the component itself in a vertical, perpendicular, or gravitational orientation; likewise, for ease of understanding and description, "inner and outer" refer to the inner and outer relative to the profile of the components themselves, but the above directional words are not intended to limit the invention.
Fig. 1 is a cross-sectional view of a multilayer circuit board in the prior art, and referring to fig. 1, a method for processing a multilayer circuit board in the prior art includes:
step S100': aligning and attaching the inner layer adhesive 31 'and the double-sided board 2' according to the alignment holes;
the double-sided board 2 ' of step S100 ' includes a first copper layer 21 ', a first base material 22 ', and a second copper layer 23 ' sequentially stacked together.
Step S200'; aligning and attaching the single-sided board 32 'and the inner layer adhesive 31' and the double-sided board 2 'which are attached in the step S100', and curing the inner layer adhesive through high-temperature and high-pressure treatment of a laminating machine to form a multilayer board;
the single panel 32 ' includes a third copper layer 321 ' and a second substrate 322 ' sequentially stacked together.
Step S300': processing a through blind hole on the multilayer board by laser with a single-sheet process, etching and removing glue residue by plasma, plating a carbon film, and plating copper to form a through hole, and then pressing a dry film, exposing, developing, etching and removing the film to form an L3-layer circuit pattern;
step S400', a cover opening process: the area to be uncapped was located according to the L3 layer etched optical mark (Fiducial mark) and the pattern was cut using a picosecond laser, and then the L3 layers of substrate and copper above the glue opening were torn off using a machine, exposing the L2 layers of wiring. And then, manually checking whether the uncovering area has the defects of substrate residue, delamination or damage and the like, and finally, removing the glue residues by using plasma etching.
And after the step S400 ', the uncapped multilayer board sequentially passes through the functions of optical detection of flowing glue, electrical detection of open circuit, short circuit and the like, the conventional lamination protective film 1 ', the lamination protective film 1 ', resistance welding treatment, surface treatment and the like.
The processing method of the multilayer circuit board is the rear cover opening process, and the cover opening area of the inner layer circuit of the flexible circuit board has a gap 4' to cause the failure of spark test or short circuit and other functional defects.
Example 1
Fig. 2 to 9 are schematic diagrams illustrating steps of the method for processing a multilayer wiring board of the present invention. The present invention provides a method for processing a multilayer circuit board, wherein the multilayer circuit board 100 can be three layers, four layers, … …, etc., and is not limited herein. The present invention will be described below by taking a three-layer circuit board as an example, wherein the three-layer circuit board includes a double-sided board 2, an inner layer adhesive 31, a single-sided board 32, and the like.
Referring to fig. 9, the method for processing the multilayer circuit board includes the following steps:
step S100, aligning and attaching an inner layer protection film 1 to a double-sided board 2 with an inner layer circuit 5 to form the double-sided board 2 with the inner layer protection film 1, wherein the shape of the inner layer protection film 1 is the same as that of an uncapping area, and the width of the uncapping area relative to a single side is larger than a first preset length;
specifically, in the step S100, the inner layer protection film 1 is attached to the double-sided board 2 on which the inner layer circuit 5 is formed in an aligned manner, and then cured by a rapid press machine, and baked at a high temperature to remove moisture. Curing may also be carried out by lamination. This is the prior art and will not be described in detail. The first predetermined length is L1, L1 is 0.70 ± 0.1mm, i.e. L1 is 0.6mm to 0.80mm, for example L1 may be 0.65mm, 0.66mm, 0.68mm, 0.70mm, 0.72mm, 0.74mm, or 0.76 mm.
In the present embodiment, referring to fig. 2, the double-sided board 2 includes a first copper layer 21, a first substrate 22 (e.g. polyimide), and a second copper layer 23 formed in a lamination along a first direction.
Before step S100, the step S110 of the manufacturing process of the inner layer protective film 1 may be to attach the protective film to a carrier film, and to perform die cutting to obtain the inner layer protective film 1, which has the same shape as the uncapped area and has a single side opposite to the uncapped area and a first preset width, and specifically includes:
step S111, attaching an unprocessed protective film to a carrier film;
the attaching process may, but is not limited to, attach the raw protection film to a carrier film in a roll-to-roll process, and the carrier film may, but is not limited to, include a transparent polyethylene terephthalate (PET) material.
Step S112, punching the protective film in the step S111 to obtain an inner protective film 1 distributed on the surface of the carrier film, wherein the shape of the protective film is the same as that of the uncapped area, but the first preset length is increased on one side;
referring to fig. 4, the punching process may be, but is not limited to, punching the shape in a half-cut manner, where the shape is the same as the shape of the uncapped area, but the first preset length L1 is increased on one side (it should be understood that the first preset length is increased on one side compared to the uncapped area, that is, the distance between each side and the uncapped area is increased by the same first preset length), and the cutting depth is the same as that of the protection film, and in other embodiments, the cutting depth may be greater than that of the protection film, so that the shape of the protection film is completely cut.
The step S112 further includes a step of tearing off waste material after die cutting, which is not described in detail herein.
Referring to fig. 3, the double-sided board 2 with the inner layer circuit 5 may be processed in a conventional manner, for example, by roll-to-roll laser processing of blind via holes, dry film pressing, exposure, development, etching, and film removal, to form L2 layers of circuits.
Step S200, attaching, laminating and fixing a copper adhesive plate 3 and a double-sided board 2 with an inner-layer protective film 1, so that the inner-layer adhesive 31 in the copper adhesive plate 3 is melted and overflows and fills the inner-layer circuit 5 together with the inner-layer protective film 1 in a molten state, and a multilayer board is obtained, wherein the copper adhesive plate 3 comprises the inner-layer adhesive 31 and a single-sided board 32 which are laminated together, the copper adhesive plate 3 is provided with a first opening 33, and the size and shape of the first opening 33 are the same as those of an uncapped area;
specifically, referring to fig. 6, after aligning and bonding the copper adhesive sheet 3 and the double-sided sheet 2 with the inner protective film 1, laminating, baking, etc., a multilayer sheet is formed, wherein the inner adhesive 31 in the copper adhesive sheet 3 is melted and overflowed at high temperature and high pressure, and is fused with the inner protective film 1 in a molten state to fill the inner circuit 5 together, and finally, is cured together. The flow width of the inner layer rubber 31 is usually 0 to 0.125mm at high temperature and high pressure. Referring to fig. 5, the single panel 32 includes a third copper layer 321 and a second substrate 322 (polyimide) stacked along a first direction.
Before the step S200, please refer to fig. 5, which further includes the following steps:
step S210, sequentially attaching and pressing the inner layer glue 31 and the single-sided board 32 to form the copper-clad board 3, and forming a first opening 33 in the uncapped area of the copper-clad board 3, where the size and shape of the first opening 33 are the same as those of the uncapped area.
Specifically, the raw inner layer glue 31 is laminated with the single face plate 32 in a roll-to-roll process and is pressed into the copper veneer 3. And cutting the copper rubber plate 3 into single sheets, and laser processing or die punching the offset holes and the exhaust holes of the processed layer by using a single sheet process, wherein the aperture is generally 2 mm. Meanwhile, the shape of the uncapping area is subjected to laser cutting, and the size and the shape of the uncapping area are the same as those of the uncapping area. Unlike the back uncapping process, the front uncapping process does not require strict control of the cutting depth. And (5) performing laser cutting to obtain an opening, and cleaning to remove carbon powder and glue residues.
Step S300, arranging and forming an outer layer circuit 6 on the single panel 32 of the multilayer board, wherein the outer layer circuit 6 is spaced from the edge of the open cover area by a preset distance;
specifically, the process of forming the outer layer wiring 6 on the single face plate 32 of the multilayer board is similar to the conventional process and will not be described in detail. Please refer to fig. 7, the difference is that the distance between the outer layer circuit 6 and the edge of the uncovering area is a preset distance, in this embodiment, the preset distance is D, D is 0.45 ± 0.1mm, that is, D is 0.35mm to 0.55mm, so that it can be effectively ensured that after the protective film is attached, the running glue of the protective film and the protective film is far away from the uncovering area, the uncovering area is generally used for the bending function, and if the running glue or the protective film covers the uncovering area, the bending reliability can be affected. In other embodiments, D may be 0.37mm, 0.39mm, 0.41mm, 0.43mm, 0.45mm, 0.47mm, or 0.5 mm.
Step S400, the multilayer board processed in the step S300 is aligned with the outer layer protection film 4, laminated and cured completely, wherein a second opening is formed in the uncovering area of the outer layer protection film 4, the shape of the second opening is the same as that of the uncovering area, the width of the single side of the second opening, which is larger than the uncovering area, is smaller than a second preset length, the second preset length is smaller than the preset distance, so that the outer layer protection film 4 can be ensured to be larger than a line, and the outer layer protection film 4 is used for protecting a line layer. Specifically, referring to fig. 8, the multilayer board processed in step S300 is aligned and laminated with the outer layer protection film 4, but not limited to, the alignment and lamination are performed according to alignment holes, and then the glue of the outer layer protection film 4 is completely cured by lamination, because the unilateral distance of the outer layer protection film 4 compared with the outer layer circuit 6 is greater than a preset value (i.e., the difference Δ L between the second preset length and the preset distance), it can be ensured that the outer layer circuit 6 is completely covered in the outer layer protection film 4.
In the embodiment, Δ L is 0.2 ± 0.1mm, that is, Δ L is 0.1mm to 0.3mm, since the fitting tolerance of the outer layer protection film 4 is 0.2mm, if Δ L is too small, the outer layer protection film 4 may not cover the circuit layer in consideration of the bonding deviation of the outer layer protection film 4, and if Δ L is too large, the outer layer protection film 4 may be too close to the uncapping area, and the bonding deviation may cause the outer layer protection film 4 to shift to the uncapping area, which may cause a defect; in addition, for the multilayer board, the influence of factors such as expansion and contraction factors of the flexible board, environmental factors in the production process, equipment stability and the like on the bonding precision needs to be considered, so that the Δ L in the embodiment is 0.1 mm-0.3 mm, and the effect is better. In other embodiments, Δ L may be 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.20mm, 0.21mm, or 0.22 mm.
In this embodiment, the second predetermined length is L2, and L2 is 0.25 ± 0.1 mm.
Preferably, in the method for processing the multilayer circuit board 100, the first preset length is L1, and L1 is 0.70 ± 0.10mm, that is, L1 is 0.60mm to 0.80mm, so that the overlapping arrangement of the copperplate and the uncapped area is at least 0.2mm, so as to achieve better effect, for example, L1 may be 0.65mm, 0.72mm, 0.74mm, 0.76mm, or 0.78 mm.
Preferably, in the method for processing a multilayer circuit board 100, before the step S400, the method further includes the steps of:
and step S410, forming a second opening in the uncapping area of the outer-layer protective film 4, wherein the shape of the second opening is the same as that of the uncapping area, and the width of the uncapping area on one side is smaller than a second preset length.
Specifically, after the outer-layer protective film 4 is cut into single pieces, the alignment holes are processed through a laser or punching process, a second opening is cut in the uncovering area, the opening shape of the second opening is the same as that of the uncovering area, but the second preset length is reduced on one side, and the laser process needs to use alcohol to clean carbon powder or glue residues.
In addition, a solder resist process, a surface process, and the like are also included after the step S400, and since the subsequent processes may be conventional processes in the prior art, they are not described in detail herein.
According to the invention, the inner layer protective film 1 is added in the uncovering area, the inner layer glue 31 retraction design is simultaneously cancelled, and the inner layer glue 31 is attached to the outer layer single panel 32 for post-processing, so that the fusion of the inner layer glue 31 and the inner layer protective film 1 glue is ensured, and the poor functions of spark test failure or short circuit and the like caused by the gap in the uncovering area of the inner layer circuit 5 are avoided;
further, the invention forms the double-sided board 2 with the inner layer protection film 1 by aligning and adhering the inner layer protection film 1 on the double-sided board 2 with the inner layer circuit 5, wherein the shape of the inner layer protection film 1 is the same as the shape of the uncapped area, and the width of the uncapped area relative to one side is larger than a first preset length, a copper adhesive sheet 3 is adhered to the double-sided board 2 with the inner layer protection film 1, laminated and baked, so that the inner layer adhesive 31 in the copper adhesive sheet 3 is melted and overflowed and fills the inner layer circuit 5 together with the inner layer protection film 1 in the molten state, a multilayer board is obtained, wherein the copper adhesive sheet 3 comprises the inner layer adhesive 31 and a single-sided board 32 which are pressed together, the copper adhesive sheet 3 is provided with a first opening 33, the size and shape of the first opening 33 are the same as the uncapped area, an outer layer circuit 6 is formed on the single-sided board 32 of the multilayer board, the outer layer circuit 6 is spaced from the edge of the uncovering area by a preset distance, the processed multilayer board and the outer layer protective film 4 are aligned, attached and laminated to completely solidify the outer layer protective film 4, wherein the outer layer protective film 4 is provided with a second opening in the uncovering area, the shape of the second opening is the same as that of the uncovering area, the single side of the second opening is smaller than the width of the uncovering area by a second preset length, and the second preset length is smaller than the preset distance, so that the inner layer glue 31 in the copper glue board 3 is melted and overflows and fills the inner layer circuit 5 together with the inner layer protective film 1 in the melting state, and the single side of the outer layer protective film 4 is larger than the single side of the outer layer circuit 6 by delta L, so that the circuit is completely wrapped in the protective film;
furthermore, by splitting the protective film into an inner layer design and an outer layer design, the inner layer glue 31 is attached and processed on the surface of the circuit board before and after the inner layer glue is attached, the filling stability of the glue in the uncapping area of the multilayer flexible circuit board is improved, the bad phenomena of copper ion migration and the like caused by incomplete glue filling are avoided, and the yield and the stability of the product are improved;
furthermore, the invention adds the cover opening design of the outer protective film 4 and reduces the whole thickness of the cover opening area of the multilayer board.
Further, different from the rear cover opening process in the prior art, the cover opening process is carried out simultaneously with the inner layer adhesive before the single-sided board is attached, and then the single-sided board is attached and pressed with the double-sided board, so that the complex post-processing procedures of tearing after laser cover opening, manual inspection, machine inspection and the like are avoided, the design of the inner layer protective film is introduced, and the risks of poor product functions and the like caused by the fact that the inner layer adhesive and the outer layer protective film adhesive are not in complete contact to generate an inner layer gap after the cover opening are eliminated.
Example 2
The present invention further provides a multilayer circuit board 100, referring to fig. 2 to 8, the multilayer circuit board 100 includes a double-sided board 2 layer, a copper tape board 3, and an outer protective film 4, the double-sided board 2 layer includes an inner protective film 1 and a double-sided board 2 formed with an inner circuit 5, the inner protective film 1 has the same shape as an uncapped area, and the width of the single-sided opposite uncapped area is greater than a first preset length, the copper tape board 3 is attached and laminated on the double-sided board 2 layer along the first direction, the copper tape board 3 includes an inner adhesive 31 and a single-sided board 32, the inner adhesive 31 and the single-sided board 32 are sequentially attached and laminated along the first direction, the single-sided board 32 is provided with an external circuit, the copper tape board 3 is provided with a first opening 33, the first opening 33 has the same size and shape as the uncapped area, the inner adhesive 31 and the inner protective film 1 fill the internal circuit together, the outer layer circuit 6 with the distance is predetermine to the edge interval in the area of uncapping, and outer protection film 4 is along first direction laminating and laminating on the copper plywood 3, the second opening has been seted up at the area of uncapping to outer protection film 4, the shape of second opening is the same with the area of uncapping, and unilateral regional width of uncapping is less than the second and predetermines length, the second is predetermine length and be less than predetermine the distance.
Wherein the double-sided board 2 includes a first copper layer 21, a first base material 22 (e.g., polyimide), and a second copper layer 23, which are laminated in a first direction, and the single-sided board 32 includes a third copper layer 321, which is laminated in the first direction, and a second base material 322 (polyimide).
The multilayer wiring board 100 may be processed and formed by a processing method including the multilayer wiring board 100 provided in embodiment 1, or may be processed and formed by another processing method, which is not particularly limited herein. The embodiments of the multilayer wiring board 100 may be all of the embodiments including the processing method of the multilayer wiring board 100 described above.
Preferably, the preset distance is D, and D is 0.45 +/-0.1 mm, namely D is 0.35 mm-0.55 mm.
In this embodiment, the difference Δ L between the second predetermined length and the predetermined distance is 0.2 ± 0.1mm, i.e., Δ L is 0.1mm to 0.3mm, for example, Δ L may be 0.14mm, 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.20mm, 0.21mm, or 0.22 mm. .
In this embodiment, the second predetermined length is L2, and L2 is 0.25 ± 0.1 mm.
It is to be understood that the above-described embodiments are only a few, and not all, embodiments of the present invention. Based on the embodiments of the present invention, those skilled in the art may make other variations or modifications without creative efforts, and shall fall within the protection scope of the present invention.
Claims (10)
1. A processing method of a multilayer circuit board is characterized by comprising the following steps:
step S100, attaching an inner layer protection film on a double-sided board with an inner layer circuit in an aligned mode to form the double-sided board with the inner layer protection film, wherein the shape of the inner layer protection film is the same as that of a cover opening area, and the width of the cover opening area with a single side opposite to the cover opening area is larger than a first preset length;
step S200, a copper adhesive plate and a double-sided board with an inner-layer protective film are attached and laminated and baked, so that inner-layer glue in the copper adhesive plate is melted and overflows, and the inner-layer glue and the inner-layer protective film in a molten state are filled in an inner-layer circuit together, and a multilayer board is obtained, wherein the copper adhesive plate comprises the inner-layer glue and a single-sided board which are laminated together, a first opening is formed in the copper adhesive plate, and the size and the shape of the first opening are the same as those of an uncapping area;
step S300, arranging and forming an outer layer circuit on the single panel of the multilayer board, wherein a preset distance is reserved between the outer layer circuit and the edge of the open cover area;
step S400, the multilayer board processed in the step S300 is aligned with an outer layer protective film, laminated and baked until the outer layer protective film is completely cured, wherein a second opening is formed in the uncovering area of the outer layer protective film, the shape of the second opening is the same as that of the uncovering area, the width of the single side of the second opening, which is larger than the uncovering area, is smaller than a second preset length, and the difference between the second preset length and the preset distance is larger than 0.
2. The method of claim 1, wherein the second predetermined length differs from the predetermined distance by Δ L, where Δ L is 0.2 ± 0.1 mm.
3. The method for processing a multilayer wiring board according to claim 1 or 2, wherein the predetermined distance is D, and D is 0.45 ± 0.1 mm.
4. The method for processing a multilayer wiring board according to claim 1 or 2, further comprising, before the step S100, the steps of:
and attaching the protective film to the carrier film, and punching to obtain the inner layer protective film which has the same shape as the uncapped area and has the width of the single-side opposite uncapped area with the first preset length.
5. The method for processing a multilayer wiring board according to claim 1 or 2, wherein the first predetermined length is L1, and L1 is 0.70 ± 0.1 mm.
6. The method for processing a multilayer wiring board according to claim 1 or 2, further comprising, before the step S200, the steps of:
and sequentially attaching and pressing the inner layer glue and the single panel to form the copper glue board, and cutting the uncapping area of the copper glue board to form a first opening, wherein the size and the shape of the first opening are the same as those of the uncapping area.
7. The method for processing a multilayer wiring board according to claim 1 or 2, further comprising, before the step S400, the steps of:
and cutting the outer-layer protective film in the uncovering area to form a second opening, wherein the shape of the second opening is the same as that of the uncovering area, and the width of the single side of the second opening, which is larger than that of the uncovering area, is smaller than a second preset length.
8. The method for processing a multilayer wiring board according to claim 1 or 2, wherein the second predetermined length is L2, and L2 is 0.25 ± 0.1 mm.
9. A multilayer wiring board, comprising:
the double-panel layer comprises an inner-layer protective film and a double-panel, wherein the inner-layer protective film and the double-panel are sequentially attached and laminated from a first direction, an inner-layer circuit is formed on the double-panel, the shape of the inner-layer protective film is the same as that of the uncapping area, and the width of the uncapping area with one side opposite to the uncapping area is greater than a first preset length;
the copper rubber plate is attached and laminated on the double-panel layer along a first direction and comprises an inner layer rubber and a single-panel, the inner layer rubber and the single-panel are sequentially attached and laminated along the first direction, an external circuit is arranged on the single-panel, a first opening is formed in the copper rubber plate, the size and the shape of the first opening are the same as those of the uncapped area, the inner layer rubber and the inner layer protective film jointly fill the internal circuit, and the distance between the outer layer circuit and the edge of the uncapped area is preset;
the outer protection film, along first direction laminating and laminating on the copper offset plate, the second opening has been seted up at the region of uncapping to outer protection film, the shape of second opening is the same with the region of uncapping, and unilateral regional width of uncapping is less than the second and predetermines length, the second is predetermine length and is less than predetermine the distance.
10. The multilayer wiring board of claim 9, wherein said second predetermined length differs from said predetermined distance by Δ L, Δ L being 0.2 ± 0.1 mm; wherein,
the preset distance is D, and D is 0.45 +/-0.1 mm; and/or the presence of a gas in the gas,
the second preset length is L2, and L2 is 0.25 +/-0.1 mm; and/or the presence of a gas in the gas,
the first preset length is L1, and L1 is 0.70 +/-0.1 mm.
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