CN113395821A - Flexible circuit board for side key fingerprint identification and manufacturing method thereof - Google Patents
Flexible circuit board for side key fingerprint identification and manufacturing method thereof Download PDFInfo
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- CN113395821A CN113395821A CN202110534451.3A CN202110534451A CN113395821A CN 113395821 A CN113395821 A CN 113395821A CN 202110534451 A CN202110534451 A CN 202110534451A CN 113395821 A CN113395821 A CN 113395821A
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- 239000000853 adhesive Substances 0.000 claims abstract description 34
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- 230000003014 reinforcing effect Effects 0.000 claims abstract description 26
- 238000004080 punching Methods 0.000 claims abstract description 12
- 238000000034 method Methods 0.000 claims description 23
- 229910000831 Steel Inorganic materials 0.000 claims description 19
- 239000010959 steel Substances 0.000 claims description 19
- 229920001187 thermosetting polymer Polymers 0.000 claims description 16
- 238000003825 pressing Methods 0.000 claims description 13
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 12
- 229910052802 copper Inorganic materials 0.000 claims description 12
- 239000010949 copper Substances 0.000 claims description 12
- 239000013039 cover film Substances 0.000 claims description 12
- 238000005530 etching Methods 0.000 claims description 7
- 239000003292 glue Substances 0.000 claims description 4
- 239000010410 layer Substances 0.000 abstract description 15
- 239000012790 adhesive layer Substances 0.000 abstract description 7
- 238000005476 soldering Methods 0.000 abstract description 5
- 239000002390 adhesive tape Substances 0.000 description 31
- 239000010408 film Substances 0.000 description 12
- 239000002699 waste material Substances 0.000 description 12
- 238000013461 design Methods 0.000 description 6
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
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- 238000010438 heat treatment Methods 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 2
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- 229910052742 iron Inorganic materials 0.000 description 2
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- 238000000059 patterning Methods 0.000 description 2
- 238000007788 roughening Methods 0.000 description 2
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- 238000004806 packaging method and process Methods 0.000 description 1
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
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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
- H05K1/00—Printed circuits
- H05K1/02—Details
-
- 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
- H05K3/38—Improvement of the adhesion between the insulating substrate and the metal
-
- 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
- H05K3/4611—Manufacturing multilayer circuits by laminating two or more circuit boards
- H05K3/4626—Manufacturing multilayer circuits by laminating two or more circuit boards characterised by the insulating layers or materials
- H05K3/4635—Manufacturing multilayer circuits by laminating two or more circuit boards characterised by the insulating layers or materials laminating flexible circuit boards using additional insulating adhesive materials between the boards
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- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Manufacturing & Machinery (AREA)
- Structure Of Printed Boards (AREA)
Abstract
The invention relates to the technical field of circuit board manufacturing, and provides a manufacturing method of a flexible circuit board for side key fingerprint identification, which comprises the following steps: providing an FPC motherboard, wherein a plurality of flexible circuit boards are distributed on the FPC motherboard; attaching a covering film on the FPC motherboard, wherein a plurality of grounding windowing areas are arranged on the covering film, and each grounding windowing area is used for exposing a grounding position layer; carrying out first contour punching on the FPC mother board to cut out a contour edge of each flexible circuit board, wherein at least part of the contour edges of the flexible circuit boards are arranged below the grounding windowing area; attaching the reinforcing sheet to the FPC motherboard through the conductive adhesive and curing to enable the reinforcing sheet to be communicated with the grounding position layer and generate resistance; and punching the FPC mother board for the second time to obtain a plurality of flexible circuit boards. The application also provides a flexible circuit board for side key fingerprint identification. This application can avoid appearing the air thermal expansion in the back flow soldering ground connection windowing region and the conductive adhesive layer and the layering problem of ground connection position layer that leads to.
Description
Technical Field
The invention relates to the technical field of circuit board manufacturing, in particular to a flexible circuit board for side key fingerprint identification and a manufacturing method thereof.
Background
The flexible circuit board for the side key fingerprint is mainly used in the field of mobile phone terminal manufacturing, and with the requirements of product technology development and function application upgrading, the side key fingerprint identification technology function starts to rise in the mobile phone industry, and is used for the application of side key fingerprint touch functions such as mobile phone startup and shutdown, volume and the like.
At present, in the design, production and manufacture of a side key fingerprint identification flexible circuit board product, after the flexible circuit board is attached to a reinforcing sheet, when a subsequent reflow soldering process is carried out, air at a grounding windowing position is heated to expand, so that poor layering occurs between conductive adhesive and a grounding position layer, the grounding resistance is large, and the quality requirement is difficult to meet.
Disclosure of Invention
The invention provides a flexible circuit board for side key fingerprint identification and a manufacturing method thereof, and aims to solve the problems that in the prior art, when the flexible circuit board is in a reflow soldering process, grounding position air is heated and expands, so that poor layering occurs between a conductive adhesive and a grounding position layer, the grounding resistance is large, and the quality requirement is difficult to meet.
An embodiment of a first aspect of the present application provides a method for manufacturing a flexible circuit board for side key fingerprint identification, including:
providing an FPC motherboard, wherein a plurality of flexible circuit boards are distributed on the FPC motherboard;
attaching a cover film on the FPC motherboard, wherein a plurality of grounding windowing areas are arranged on the cover film, and each grounding windowing area is used for exposing a corresponding grounding position layer of the flexible circuit board;
carrying out first outline punching on the FPC mother board to cut out the outline edge of each flexible circuit board, wherein at least part of the outline edge of each flexible circuit board is arranged below the grounding windowing area;
attaching a reinforcing sheet to the FPC motherboard through a conductive adhesive and curing to enable the reinforcing sheet to be communicated with the grounding position layer and generate resistance;
and carrying out secondary punching on the FPC motherboard to obtain a plurality of flexible circuit boards.
In some of these embodiments, the ground fenestration region is 1.0mm in area2And 2-3 grounding windowing regions are arranged above the flexible circuit board correspondingly.
In some embodiments, the distance between the side edge of the ground windowing region far away from the flexible circuit board and the outline edge of the flexible circuit board is 0.3mm to 0.35mm in the direction parallel to the cover film.
In some embodiments, before the first outline blanking is performed on the FPC motherboard, the manufacturing method further includes:
etching a plurality of alignment lines on the FPC motherboard, wherein the alignment lines are arranged in one-to-one correspondence with the flexible circuit board and comprise a first alignment line and a second alignment line which are arranged in parallel at intervals, and the first alignment line and the second alignment line are both positioned outside the outline edge of the flexible circuit board or are both flush with the outline edge of the flexible circuit board;
and gummed paper is attached to the FPC motherboard and is in one-to-one correspondence with the flexible circuit boards, and the gummed paper on each flexible circuit board is positioned between the corresponding first alignment line and the second alignment line, and two ends of the gummed paper are positioned through the corresponding first alignment line and the second alignment line respectively.
In some embodiments, the first pair of bit lines and the second pair of bit lines are both located outside the outline edge of the corresponding flexible circuit board, and the line widths of the first pair of bit lines and the second pair of bit lines are both 0.2 mm.
In some embodiments, after the adhesive tape is attached to the FPC motherboard, the adhesive tape is subjected to low-temperature press-fitting.
In some embodiments, after the reinforcing sheet is pressed on the FPC motherboard through the conductive adhesive and cured, the 3D steel sheet is attached on the FPC motherboard through the thermosetting adhesive and cured, and the thickness of the thermosetting adhesive is greater than 0.025 mm.
In some of these embodiments, the thickness of the thermosetting adhesive is 0.035 mm.
In some embodiments, an R corner is disposed at a corner of a main body of the flexible circuit board, a copper sheet is disposed at a bottom of the R corner, a diameter of the R corner is greater than or equal to 2.0mm, and a width of the copper sheet is greater than or equal to 0.6 mm.
The embodiment of the second aspect of the present application provides a flexible circuit board for side key fingerprint identification, which is manufactured by using the manufacturing method of the flexible circuit board for side key fingerprint identification according to the embodiment of the first aspect.
The embodiment of the first aspect of the invention provides a method for manufacturing a flexible circuit board for side key fingerprint identification, the outline edge of each flexible circuit board is cut out by carrying out first outline punching on the FPC motherboard, the outline edge of the flexible circuit board is connected with the waste material on the FPC motherboard through a plurality of nodes, communicated gaps exist between the outline edge of the flexible circuit board and the waste material area, then the reinforcing sheet is attached to the FPC motherboard through the conductive adhesive and cured, when the reinforcing sheet is attached to the flexible circuit board, the air in the grounding windowing area can be discharged through a gap between the outer edge of the flexible circuit board and the waste area and a part of the grounding windowing area extending to the outer side of the flexible circuit board, the problem that the air in the grounding windowing area expands due to heating after reflow soldering to cause layering of a conductive adhesive layer and a grounding potential layer is avoided, the stability of the grounding resistance value of the circuit board is improved, and the resistance value is reduced.
According to the flexible circuit board for side key fingerprint identification, when the reinforcing sheet is attached to the flexible circuit board, air in the grounding windowing area is discharged through the gap between the outline edge of the flexible circuit board and the waste material area and the part of the grounding windowing area extending to the outer side of the flexible circuit board, so that the problem that the conductive adhesive layer and the grounding position layer are layered due to the fact that the air in the grounding windowing area expands due to heating after the flexible circuit board is reflowed and welded is solved, the stability of the grounding resistance of the flexible circuit board is improved, the resistance is reduced, and the flexible circuit board meets the quality requirement.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
FIG. 1 is a flowchart of a method for manufacturing a flexible printed circuit board for side key fingerprint identification according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of the relative positions of a flexible circuit board, a cover film, a reinforcing sheet and a conductive adhesive according to one embodiment of the present invention;
FIG. 3 is a schematic diagram of the relative positions of the flexible circuit board, the reinforcing patch and the ground opening region in one embodiment of the present invention;
FIG. 4 is a schematic diagram of the relative positions of the flexible circuit board, alignment lines and adhesive tape in one embodiment of the present invention;
FIG. 5 is an enlarged partial view of portion A of FIG. 4;
FIG. 6 is a schematic diagram of the relative positions of the flexible circuit board, the alignment lines and the adhesive tape in another embodiment of the present invention;
FIG. 7 is an enlarged partial view of the area B in FIG. 6;
FIG. 8 is a schematic diagram of the structure of the R-corners and copper sheets on the flexible circuit board in one embodiment of the present invention;
fig. 9 is a partially enlarged view of a portion C in fig. 8.
The designations in the figures mean:
10. a flexible circuit board; 11. an R angle; 12. copper sheet; 20. covering the film; 21. a ground windowed area; 30. a reinforcing sheet; 40. a conductive adhesive; 50. aligning a bit line; 51. a first pair of bit lines; 52. a second pair of bit lines; 53. a third pair of bit lines; 60. gummed paper.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings, which are examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.
Furthermore, the terms "first", "second" and "first" 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 one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In order to explain the technical solution of the present invention, the following description is made with reference to the specific drawings and examples.
Referring to fig. 1, fig. 2 and fig. 3, an embodiment of a first aspect of the present application provides a method for manufacturing a flexible circuit board for side key fingerprint identification, including:
s10: an FPC motherboard is provided with a plurality of flexible circuit boards 10 arranged thereon.
Specifically, the FPC motherboard can be a circuit board after the processes of cutting, laser drilling, shadow plasma, shadow, cutting, patterning and AOI, wherein the patterning process comprises the processes of dry film pasting, exposure, development, etching and film stripping.
Wherein the dry film is a dry film with a thickness of 40 specifications, the film sticking speed is 0.8-1.2 m/min, and the air pressure is 6-8 kg/cm2(ii) a The exposure energy is 37mj to 40mj during exposure, the exposure ruler is adjusted to 5 grids to 7 grids, potassium carbonate solution is used during development, the concentration is adjusted to 3% +/-0.2%, the development speed is adjusted to 2.0 +/-0.5 m/min, and the spraying pressure is 1.0 to 1.5kg/cm2(ii) a Etching with etching solution at a speed of 3.7 + -0.6 m/min; when the film is removed, sodium hydroxide solution is used, the concentration is adjusted to 3% +/-0.5%, and the speed is 3.0 +/-0.5 m/min.
S20: a cover film 20 is attached to the FPC motherboard, and a plurality of ground opening regions 21 are provided in the cover film 20, each ground opening region 21 being used to expose a ground potential layer of the corresponding flexible circuit board 10.
The cover film 20 is processed with a ground opening area 21 in advance, and the first surface of the FPC motherboard is a side surface to which the cover film 20 is to be attached.
S30: the FPC motherboard is subjected to first outline punching to cut out an outline edge of each flexible circuit board 10, at least a part of the outline edge of the flexible circuit board 10 being provided below the ground windowing region 21.
Specifically, the shape of the FPC motherboard is punched for the first time, and the shape of each flexible circuit board 10 can be punched through a precision die, so that when the shape of each flexible circuit board 10 is cut, the shape of each flexible circuit board 10 is connected with the waste on the FPC motherboard through a plurality of nodes, a communicated gap exists between the shape of each flexible circuit board 10 and the waste area, at least part of the shape of each flexible circuit board 10 is arranged below the ground windowing area 21, that is, one part of the ground windowing area 21 is arranged above the flexible circuit board 10, and the other part of the ground windowing area extends to the outer side of the flexible circuit board 10, and according to the shape of the flexible circuit board 10, the flexible circuit board can be provided with one, two or more than one side edges of the shape of the flexible circuit board 10 which are arranged below the ground windowing area 21.
S40: the reinforcing sheet 30 is attached to the FPC motherboard by the conductive adhesive 40 and cured, so that the reinforcing sheet 30 communicates with the ground potential layer and generates a resistance value.
Specifically, the reinforcing sheet 30 is adapted to the outer shape of the flexible circuit board 10, and the material of the reinforcing sheet 30 may be determined according to different use requirements, such as PET, PI, back glue, metal or resin, when the reinforcing sheet 30 is attached to the FPC motherboard through the conductive adhesive 40, since at least part of the outer shape of the flexible circuit board 10 is disposed below the ground windowing region 21, and there is a communicating gap between the outer shape of the flexible circuit board 10 and the waste region, air in the ground windowing region 21 during subsequent pressing may be discharged through the gap between the outer shape of the flexible circuit board 10 and the waste region and the portion of the ground windowing region 21 extending to the outer side of the flexible circuit board 10, thereby ensuring that the strong steel sheet 5, the conductive adhesive 40 and the flexible circuit board 10 are fully combined during pressing.
S50: and punching the FPC mother board for the second time to obtain a plurality of flexible circuit boards 10.
Specifically, the product can be delivered by punching through a precision model and carrying out necessary testing and packaging.
The method for manufacturing the flexible circuit board for side key fingerprint identification provided by the embodiment of the first aspect of the invention cuts out the outline edge of each flexible circuit board 10 by performing first outline punching on the FPC motherboard, at the moment, the outline edge of the flexible circuit board 10 is connected with the waste material on the FPC motherboard through a plurality of nodes, a communicated gap is formed between the outline edge of the flexible circuit board 10 and the waste material area, and then the reinforcing sheet 30 is attached to the FPC motherboard through the conductive adhesive 40 and is solidified, so that when the reinforcing sheet 30 is attached to the flexible circuit board 10, the air in the grounding windowing area 21 can be discharged through the gap between the outline edge of the flexible circuit board 10 and the waste material area and the part of the grounding windowing area 21 extending to the outer side of the flexible circuit board 10, and the problem of delamination between the conductive adhesive layer and the grounding potential layer caused by the expansion of the air in the grounding windowing area due to heating after reflow soldering is avoided, the stability of the grounding resistance of the circuit board is improved and the resistance is reduced.
Referring to fig. 2 and 3, in some embodiments, the ground window area 21 has an area of 1.0mm2And 2-3 grounding windowing regions are arranged above the flexible circuit board correspondingly.
The ground window area 21 is a square area, and in the same position, the space that can be enlarged compared with a circular window area is larger, and if the area of the ground window area 21 is less than 1.0mm2And the area is too small, so that the resistance value is easily influenced, and the risk problem of higher resistance value occurs.
Further, the area of the ground windowing region 21 is 1.0mm2To 1.5mm2Belongs to a more moderate and optimal range value, if the area exceeds 1.5mm2This may cause the risk of SMT reflow bubbles in subsequent processes, which may result in a large ground resistance.
Preferably, the area of the ground windowing region 21 is 1.2mm2The grounding resistor cannot be affected, the risk problem of high resistance is solved, the structure of an original product is not required to be changed, and the use requirement is met.
Referring again to fig. 2 and 3, in some embodiments, the distance between the side edge of the ground windowing region 21 away from the flexible circuit board and the outline edge of the flexible circuit board along the direction parallel to the cover film 20 is 0.3mm to 0.35mm, such as 0.3mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, and 0.35 mm.
If the distance between the side edge of the grounding windowing region 21 far away from the flexible circuit board 10 and the outer side edge of the flexible circuit board 10 is too large, the area of the grounding windowing region 21 can be affected, so that the area of the grounding windowing region is small, the grounding resistance value is easily affected, and the risk problem of high resistance value occurs.
Referring to fig. 4 and 5, in some embodiments, before the first outline punching is performed on the FPC motherboard, the manufacturing method further includes:
firstly, a plurality of alignment lines 50 are etched on the FPC motherboard, the alignment lines are arranged in one-to-one correspondence with the flexible circuit board 10, the alignment lines 50 include a first alignment line 51 and a second alignment line 52 which are arranged in parallel at intervals, and the first alignment line 51 and the second alignment line 52 are both located outside the outline edge of the corresponding flexible circuit board 10 or are both flush with the outline edge of the corresponding flexible circuit board 10.
Next, adhesive tapes 60 are attached to the FPC motherboard, the adhesive tapes 60 are arranged in one-to-one correspondence with the flexible circuit boards 10, the adhesive tape 60 on each flexible circuit board 10 is located between the corresponding first pair of bit lines 51 and second pair of bit lines 52, and two ends of the adhesive tape are respectively positioned by the corresponding first pair of bit lines 51 and second pair of bit lines 52.
Specifically, in order to reinforce the strength of the flexible circuit board 10 and prevent the flexible circuit board from breaking after being bent, the adhesive tape 60 is adhered to the bent portion of the flexible circuit board 10, and the adhesive tape 60 may be made of teflon adhesive tape 60. The automatic machine that directly pastes of week can be adopted during attached adhesive tape 60 to paste dress (mould limit is towards the limit and is pasted), mould size design is unanimous with adhesive tape 60 size design, adhesive tape 60 draws material interval 2mm to 4mm, the dress process no longer relies on the appearance edge location of flexible circuit board 10, but paste dress according to the alignment position, after attached adhesive tape 60, carry out the first appearance die-cut to the FPC mother board again, in order to cut out the appearance limit of every flexible circuit board 10, not only adhesive tape 60 edge burr not only after the die-cut, and solved adhesive tape 60 and pasted dress off normal position appearance problem, adhesive tape 60 pastes dress precision and can promote by 0.15mm to be less than or equal to 0.1 mm.
In some embodiments, the first pair of bit lines 51 and the second pair of bit lines 52 are located outside the outline of the corresponding flexible circuit board 10, and the first pair of bit lines 51 and the second pair of bit lines 52 each have a line width of 0.2 mm.
Since the adhesive tape 60 is designed to be attached to the center of the alignment line, the requirement of the attachment alignment tolerance of the adhesive tape 60 is ± 0.1mm, and etching the alignment line by 0.2mm can facilitate checking whether the adhesive tape 60 has a deviation exceeding the tolerance of 0.1mm, and if any one side of the adhesive tape 60 completely covers the first alignment line 51 or the second alignment line 52 or completely exposes the first alignment line 51 or the second alignment line 52, it represents that the adhesive tape 60 has a deviation failure.
Referring to fig. 6 and 7, in some embodiments, a plurality of alignment lines 50 are etched on the FPC motherboard, the alignment lines are disposed in a one-to-one correspondence with the flexible circuit boards 10, the alignment lines 50 include four "L" -shaped third alignment lines 53, the four third alignment lines 53 are distributed in a rectangular shape and are all located outside the outer edge of the corresponding flexible circuit board 10 or are all flush with the outer edge of the corresponding flexible circuit board 10, when the adhesive tape 60 is attached to the FPC motherboard, the adhesive tape 60 on each flexible circuit board 10 is located inside the corresponding four third alignment lines 53, and at this time, four corners of the adhesive tape 60 are respectively located by the corresponding third alignment lines 53. The adhesive paper 60 can be accurately positioned in two mutually perpendicular directions.
Optionally, the line width of the third pair of bit lines 53 is 0.2mm, which facilitates the detection of the offset of the adhesive tape 60 exceeding the tolerance of 0.1 mm.
In some embodiments, after the adhesive tape 60 is attached to the FPC motherboard, the adhesive tape 60 is subjected to a low-temperature pressing process.
Specifically, after the adhesive tape 60 is attached, a press is adopted for low-temperature pressing, the pressing condition is set to be 60-80 ℃, the pre-pressing time is 5-10 s, the forming time is 15-30 s, and the pressure is 60-70 kg, and the low-temperature pressing laminated structure sequentially comprises an upper template, a silicon aluminum foil, a release film, the adhesive tape 60, a side flexible circuit board 10, a-release film-green silica gel, fiberglass cloth, a baked iron plate and a lower template.
In some embodiments, after the reinforcing sheet 30 is pressed onto the FPC motherboard by the conductive adhesive 40 and cured, the 3D steel sheet is attached onto the FPC motherboard by a thermosetting adhesive with a thickness greater than 0.025mm and cured.
Specifically, the reinforcing sheet 30 and the 3D steel sheet are located on two sides or the same side of the flexible circuit board 10, specifically, the product design structure is used for determining, the 3D steel sheet is used for side key (such as an on-off key and a volume key of the side key) fingerprint sensing assembly, and when a subsequent terminal device is assembled, a fingerprint sensing element is further installed on the 3D steel sheet.
As one way that can be implemented, when attaching the 3D steel sheet to the flexible circuit board 10, the head attaching temperature of the automatic reinforcement machine is set to 150 ℃ to 170 ℃, the platform temperature is set to 80 ℃ to 100 ℃, and the attachment delay time is set to 200ms to 300 ms; pressing the 3D steel sheet and thermosetting adhesive on a flexible circuit board 10, specifically adopting four-opening oil pressure rapid pressing, wherein the pressing laminated structure sequentially comprises an upper template, a silicon-aluminum foil, a 2-layer release film, a 0.3mm FR4 cover plate, the flexible circuit board 10, the 3D steel sheet, a jig, green silica gel, glass fiber cloth, a sintered iron plate and a lower template; and finally, baking and curing: 2-3 products are placed on each layer of the flexible circuit board 10, the products are placed independently without being overlapped, and the baking condition is that the temperature is 160-170 ℃ and the time is 60 min.
The thickness of the thermosetting adhesive is more than 0.025mm, the thickness of the adhesive can be improved, the filling property of quick pressing and pressing can be increased, the surface gap between the adhesive layer and the flexible circuit board 10 can be reduced, the bonding tightness between the adhesive layer and the flexible circuit board 10 can be improved, the bonding tightness between the flexible circuit board 10 and the 3D steel sheet can be improved, and the stripping force between the thermosetting adhesive and the flexible circuit board 10 can be improved to be more than 1.5kgf/cm from less than or equal to 1.2 kgf/cm.
Further, after the reinforcing sheet 30 is pressed on the flexible circuit board 10 through the conductive adhesive 40 and is cured, before the 3D steel sheet is attached on the flexible circuit board 10 through the thermosetting adhesive and is cured, plasma surface roughening treatment is carried out on the surface of the flexible circuit board 10 to which the 3D steel sheet needs to be attached, the surface roughness of the flexible circuit board 10 can be improved, so that the adhesion degree of the follow-up thermosetting adhesive and the surface of the flexible circuit board 10 is improved, the combination tightness of the flexible circuit board 10 and the 3D steel sheet is improved, the same effect is achieved, plasma surface roughening treatment can also be carried out on the surface of the 3D steel sheet to which the thermosetting adhesive needs to be attached, the adhesion degree of the follow-up thermosetting adhesive and the surface of the 3D steel sheet is improved, and the combination tightness of the flexible circuit board 10 and the 3D steel sheet is improved.
In some embodiments, the thickness of the thermosetting adhesive is 0.035mm, which can improve the adhesion between the thermosetting adhesive and the surface of the 3D steel sheet, further improve the bonding tightness between the flexible circuit board 10 and the 3D steel sheet, and also ensure the quality of the overflowing adhesive.
Referring to fig. 8 and 9, in some embodiments, an R corner 11 is disposed at a corner of a main body of the flexible circuit board 10, a copper sheet 12 is disposed at a bottom of the R corner 11, a diameter of the R corner 11 is greater than or equal to 2.0mm, and a width of the copper sheet 12 is greater than or equal to 0.6 mm.
Specifically, the diameter of the R corner 11 is directly designed to be more than 2.0mm through engineering data, the line width of the copper sheet 12 is designed to be more than 0.6mm through engineering data, a corresponding circuit film is manufactured according to the improved design data, and the R corner 11 and the copper sheet 12 are manufactured and molded through processing modes of graphic dry film pasting, exposure, development, etching and film removal. By designing the diameter of the R angle 11 to be more than or equal to 2.0mm and the width of the copper sheet 12 to be more than or equal to 0.6mm, the R angle 11 of the flexible circuit board 10 is not easy to tear and break, and the tearing resistance is improved to be more than or equal to 6N.
If the diameter of the R corner 11 and the width of the copper sheet 12 are designed to be too large, the structure of the side key fingerprint FPC is changed to include circuit layout, appearance design and the like.
An embodiment of a second aspect of the present application provides a flexible circuit board for side key fingerprint identification, which is manufactured by using the manufacturing method of the flexible circuit board for side key fingerprint identification in the embodiment of the first aspect.
According to the flexible circuit board for side key fingerprint identification, when the reinforcing sheet 30 is attached to the flexible circuit board 10, air in the grounding windowing area 21 is discharged through a gap between the outer edge of the flexible circuit board 10 and the waste area and a part of the grounding windowing area 21 extending to the outer side of the flexible circuit board 10, so that the problem that the conductive adhesive layer and the grounding potential layer are layered due to the fact that the air in the grounding windowing area expands when heated after the flexible circuit board is reflowed and welded is solved, the stability of the grounding resistance of the flexible circuit board is improved, the resistance is reduced, and the flexible circuit board meets the quality requirement.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.
Claims (10)
1. A manufacturing method of a flexible circuit board for side key fingerprint identification is characterized by comprising the following steps:
providing an FPC motherboard, wherein a plurality of flexible circuit boards are distributed on the FPC motherboard;
attaching a cover film on the FPC motherboard, wherein a plurality of grounding windowing areas are arranged on the cover film, and each grounding windowing area is used for exposing a corresponding grounding position layer of the flexible circuit board;
carrying out first outline punching on the FPC mother board to cut out the outline edge of each flexible circuit board, wherein at least part of the outline edge of each flexible circuit board is arranged below the grounding windowing area;
attaching a reinforcing sheet to the FPC motherboard through a conductive adhesive and curing to enable the reinforcing sheet to be communicated with the grounding position layer and generate resistance;
and carrying out secondary punching on the FPC motherboard to obtain a plurality of flexible circuit boards.
2. The method for manufacturing a flexible circuit board for side key fingerprint identification according to claim 1, wherein the ground windowing region has an area of 1.0mm2Above thatAnd 2-3 grounding windowing regions are arranged above each flexible circuit board.
3. The method for manufacturing a flexible circuit board for side key fingerprint identification according to claim 2, wherein a distance between a side edge of the ground windowing region away from the flexible circuit board and an outer shape edge of the flexible circuit board is 0.3mm to 0.35mm in a direction parallel to the cover film.
4. The method for manufacturing a flexible circuit board for side key fingerprint recognition according to claim 1, wherein before the first outline blanking of the FPC motherboard, the method further comprises:
etching a plurality of alignment lines on the FPC motherboard, wherein the alignment lines are arranged in one-to-one correspondence with the flexible circuit board and comprise a first alignment line and a second alignment line which are arranged in parallel at intervals, and the first alignment line and the second alignment line are both positioned outside the outline edge of the flexible circuit board or are both flush with the outline edge of the flexible circuit board;
and gummed paper is attached to the FPC motherboard and is in one-to-one correspondence with the flexible circuit boards, and the gummed paper on each flexible circuit board is positioned between the corresponding first alignment line and the second alignment line, and two ends of the gummed paper are positioned through the corresponding first alignment line and the second alignment line respectively.
5. The method for manufacturing a flexible circuit board for side key fingerprint identification according to claim 4, wherein the first pair of bit lines and the second pair of bit lines are both located outside corresponding to the outer shape edge of the flexible circuit board, and the line widths of the first pair of bit lines and the second pair of bit lines are both 0.2 mm.
6. The method for manufacturing a flexible circuit board for side key fingerprint identification according to claim 4, wherein after the adhesive paper is attached to the FPC motherboard, the adhesive paper is subjected to low-temperature pressing treatment.
7. The method for manufacturing a flexible circuit board for side key fingerprint identification according to claim 1, wherein after the reinforcing sheet is pressed on the FPC motherboard by conductive glue and cured, the 3D steel sheet is attached on the FPC motherboard by thermosetting glue and cured, and the thickness of the thermosetting glue is more than 0.025 mm.
8. The method for manufacturing a flexible circuit board for side key fingerprint identification according to claim 7, wherein the thickness of the thermosetting adhesive is 0.035 mm.
9. The method for manufacturing the flexible circuit board for side key fingerprint identification according to any one of claims 1 to 8, wherein an R corner is arranged at a corner of a main body of the flexible circuit board, a copper sheet is arranged at the bottom of the R corner, the diameter of the R corner is greater than or equal to 2.0mm, and the width of the copper sheet is greater than or equal to 0.6 mm.
10. A flexible circuit board for side key fingerprint identification, characterized by being manufactured by the method for manufacturing a flexible circuit board for side key fingerprint identification according to any one of claims 1 to 9.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110534451.3A CN113395821A (en) | 2021-05-17 | 2021-05-17 | Flexible circuit board for side key fingerprint identification and manufacturing method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110534451.3A CN113395821A (en) | 2021-05-17 | 2021-05-17 | Flexible circuit board for side key fingerprint identification and manufacturing method thereof |
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| CN113395821A true CN113395821A (en) | 2021-09-14 |
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| JP2009295705A (en) * | 2008-06-04 | 2009-12-17 | Nippon Mektron Ltd | Flexible printed circuit and method of manufacturing the same |
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| CN107249255A (en) * | 2017-06-09 | 2017-10-13 | 上达电子（深圳）股份有限公司 | It is die cut gummed paper applying method |
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Application publication date: 20210914 |