CN118632445A - PCB manufacturing method for improving circuit density - Google Patents
PCB manufacturing method for improving circuit density Download PDFInfo
- Publication number
- CN118632445A CN118632445A CN202410770727.1A CN202410770727A CN118632445A CN 118632445 A CN118632445 A CN 118632445A CN 202410770727 A CN202410770727 A CN 202410770727A CN 118632445 A CN118632445 A CN 118632445A
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- China
- Prior art keywords
- etching
- copper
- circuit
- layer
- dry film
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 31
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 43
- 238000005530 etching Methods 0.000 claims abstract description 42
- 229910052802 copper Inorganic materials 0.000 claims abstract description 33
- 239000010949 copper Substances 0.000 claims abstract description 33
- 238000000608 laser ablation Methods 0.000 claims abstract description 23
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 21
- 238000000034 method Methods 0.000 claims abstract description 18
- 238000003384 imaging method Methods 0.000 claims abstract description 12
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims abstract description 9
- 238000012545 processing Methods 0.000 claims abstract description 5
- 239000011889 copper foil Substances 0.000 claims description 10
- 238000009713 electroplating Methods 0.000 claims description 7
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 6
- 238000007747 plating Methods 0.000 claims description 6
- 239000011248 coating agent Substances 0.000 claims description 5
- 238000000576 coating method Methods 0.000 claims description 5
- 239000003822 epoxy resin Substances 0.000 claims description 5
- 229920000647 polyepoxide Polymers 0.000 claims description 5
- 239000004593 Epoxy Substances 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 238000005507 spraying Methods 0.000 claims description 3
- 239000011135 tin Substances 0.000 claims description 3
- 238000001020 plasma etching Methods 0.000 claims description 2
- 238000005260 corrosion Methods 0.000 abstract description 13
- 230000007797 corrosion Effects 0.000 abstract description 8
- 230000002035 prolonged effect Effects 0.000 abstract description 4
- 238000005516 engineering process Methods 0.000 abstract description 2
- 239000011295 pitch Substances 0.000 description 12
- 238000010586 diagram Methods 0.000 description 7
- 238000011161 development Methods 0.000 description 3
- 238000002679 ablation Methods 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
Landscapes
- Manufacturing Of Printed Circuit Boards (AREA)
Abstract
The invention discloses a PCB manufacturing method for improving circuit density, which relates to the technical field of PCB processing technology and can greatly improve the circuit density and the process level by utilizing conventional green equipment. The PCB manufacturing method capable of improving the circuit density does not need etching precompensation for the line width spacing of the dry film in the external light imaging step. The line width pitch formed by the dry film is the line width pitch after etching, so the line width limit capability of the dry film is the limit capability of the etched line. The tin layer which is easy to react with sodium hydroxide is not arranged during film stripping, so that the treatment time can be prolonged as much as possible, the film stripping is ensured to be sufficient, and the film clamping can be almost completely avoided. The side copper layer of the circuit can completely avoid the problem of side etching because the corrosion resistance layer is manufactured, the copper layer after laser ablation is thinned, the circuit etching is easier, and the etching difficulty is reduced, so that the circuit density of the PCB manufactured by a conventional factory can be greatly improved.
Description
Technical Field
The invention relates to the technical field of PCB processing technology, in particular to a PCB manufacturing method for improving circuit density.
Background
With the development of electronic products toward portability, high integration and high power, higher and higher demands are being placed on the circuit density of PCBs (Printed Circuit Board, printed circuit boards), from the original line width/pitch of 75/75 microns, up to 50/50 microns, and even up to 30/30 microns, 25/25 microns on the carrier board level. For most conventional PCB process factories at present, the line width/space capacity of the PCB process factories is limited to 75/75 microns, and the PCB process factories are further improved, so that the equipment investment and the production cost are increased by an order of magnitude. How to improve the line width/space process capability of the circuit based on the existing PCB process equipment is the biggest requirement and difficulty of the PCB industry nowadays.
In the prior art, when etching copper layers, the etching solution can laterally erode the copper layers below the resist layer (tin layer), and the term of the etching solution is called lateral etching in the PCB industry. Undercut can lead to narrowing of the actual line being produced, and therefore, it is generally necessary to pre-widen the line, known in the art as etch pre-compensation, i.e., to extra widen the dry film line in engineering, typically by at least an additional 25 microns. When the line width/spacing of the etched copper layer is 75/75 microns, the actual design is 100 microns, and the spacing is 50 microns. The etched line width is 100-25=75 microns and the pitch is 50+25=75 microns due to 25 micron undercut of the line. The minimum linewidth/spacing capability of conventional dry films is 50/50 microns, with a dry film spacing of 50 microns being the limit, so the line spacing after etching is no less than 75 microns.
In addition, the side etching can cause the etched line shape to be in a trapezoid shape with a narrow upper part and a wide lower part, the width difference between the upper part and the lower part is 50 microns, and the wider part at the bottom of the line is used as the actual line width in actual operation, so if the bottom (the widest part) of the line is smaller than 75 microns, the top of the line is smaller than 25 microns, and even the top of the line is corroded to be completely used and the corrosion-resistant tin layer falls off under extreme conditions, so that the line width (the bottom width) after etching is generally more than or equal to 75 microns.
Disclosure of Invention
The invention aims to at least solve one of the technical problems in the prior art, and provides a PCB manufacturing method for improving the circuit density, which can greatly improve the circuit density by using conventional green equipment and improve the process level.
According to a first aspect of the present invention, there is provided a PCB manufacturing method for improving circuit density, comprising the steps of: cutting, external light imaging, pattern electroplating, film stripping, resist layer manufacturing, laser ablation, circuit etching and resist layer stripping.
According to the PCB manufacturing method for improving the circuit density, in the material cutting step, the copper-clad plate is cut into a proper processing size, and the copper-clad plate is a layer of copper foil coated on the surface of the epoxy resin plate.
According to the PCB manufacturing method for improving the circuit density, in the external light imaging step, a layer of dry film is coated on the surface of a copper-clad plate, the dry film is sensitized in a laser exposure mode, a circuit pattern is transferred onto the dry film, and then the unexposed dry film is washed out through development, so that a required circuit pattern is formed.
According to the PCB manufacturing method for improving the circuit density, in the external light imaging step, etching pre-compensation is not carried out on the line width spacing of the dry film, and the line width spacing formed by the dry film is the etched line width spacing.
According to the PCB manufacturing method for improving the circuit density, in the pattern electroplating step, a layer of copper is plated on the uncovered area of the dry film in a copper electroplating mode.
According to the PCB manufacturing method for improving the circuit density, in the film removing step, the dry film is dissolved and removed by the principle of sodium hydroxide solution or plasma biting.
According to the PCB manufacturing method for improving the circuit density, in the manufacturing step of the anti-corrosion layer, a layer of anti-corrosion layer is formed on the whole copper surface by adopting a mode of electroplating tin or nickel or coating an organic film.
According to the PCB manufacturing method for improving the circuit density, in the laser ablation step, the laser is adopted to ablate the anti-corrosion layer at the valley bottom between the circuits, the laser ablation is required to ablate the copper layer below the anti-corrosion layer by more than 2 microns so as to ensure that the anti-corrosion layer is completely removed, and etching compensation is reserved at two sides of the laser ablation, wherein the compensation value is 5-20 microns on one side.
According to the PCB manufacturing method for improving the circuit density, in the laser ablation step, the thickness of a copper layer above an ablated epoxy resin plate is 1-5 microns.
According to the PCB manufacturing method for improving the circuit density, in the circuit etching step, the copper exposed after laser ablation is dissolved and removed through spraying etching liquid, copper surfaces of areas which are not ablated by laser are reserved because of the protection of the corrosion resistant layer, the side surfaces of the circuit cannot be corroded due to the protection of the corrosion resistant layer, and in the corrosion resistant layer stripping step, the corrosion resistant layer above the circuit layer is stripped by using the corrosion resistant layer stripper, and only the copper layer circuit is left.
The invention has at least the following beneficial effects: the PCB manufacturing method capable of improving the circuit density does not need etching precompensation for the line width spacing of the dry film in the external light imaging step. The line width pitch formed by the dry film is the line width pitch after etching, so the line width limit capability of the dry film is the limit capability of the etched line. The tin layer which is easy to react with sodium hydroxide is not arranged during film stripping, so that the treatment time can be prolonged as much as possible, the film stripping is ensured to be sufficient, and the film clamping can be almost completely avoided. The side copper layer of the circuit can completely avoid the problem of side etching because the corrosion resistance layer is manufactured, the copper layer after laser ablation is thinned, the circuit etching is easier, and the etching difficulty is reduced. Thus conventional PCB factories can produce PCBs with linewidth pitches as low as 35/35 microns using this approach; when the scheme is used by a carrier PCB factory, the difficulty of producing the carrier with the line width spacing of 25/25 micrometers or even 20/20 micrometers is obviously reduced.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The invention is further described below with reference to the drawings and examples;
FIG. 1 is a process flow diagram of a preferred embodiment of the present invention;
FIG. 2 is a schematic view of a copper-clad plate according to a preferred embodiment of the present invention;
FIG. 3 is a schematic diagram of the structure of the present invention after the photo-imaging is performed;
FIG. 4 is a schematic diagram of the structure of the electroplated film according to the preferred embodiment of the present invention;
FIG. 5 is a schematic diagram of the structure of the film-removing process according to the preferred embodiment of the present invention;
FIG. 6 is a schematic diagram of a resist layer according to a preferred embodiment of the invention;
FIG. 7 is a schematic diagram of a circuit etched structure according to a preferred embodiment of the invention;
FIG. 8 is a schematic diagram of a resist stripping structure according to a preferred embodiment of the invention.
Reference numerals:
Epoxy resin board 10, copper foil layer 20, dry film 30, resist layer 40.
Detailed Description
Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein the accompanying drawings are used to supplement the description of the written description so that one can intuitively and intuitively understand each technical feature and overall technical scheme of the present invention, but not to limit the scope of the present invention.
In the description of the present invention, it should be understood that references to orientation descriptions such as upper, lower, front, rear, left, right, etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of description of the present invention and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.
In the description of the present invention, a number means one or more, a number means two or more, and greater than, less than, exceeding, etc. are understood to not include the present number, and above, below, within, etc. are understood to include the present number. The description of the first and second is for the purpose of distinguishing between technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present invention can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical scheme.
Referring to fig. 1 to 8, a PCB manufacturing method for improving a circuit density includes the steps of:
Cutting, external light imaging, pattern electroplating, film stripping, resist layer manufacturing, laser ablation, circuit etching and resist layer stripping.
It will be appreciated that in embodiments of the present invention, the extraneous photoimaging step does not require etch precompensation of the linewidth spacing of dry film 30. The line width pitch formed by the dry film is the line width pitch after etching, so the line width limit capability of the dry film is the limit capability of the etched line. The tin layer which is easy to react with sodium hydroxide is not arranged during film stripping, so that the treatment time can be prolonged as much as possible, the film stripping is ensured to be sufficient, and the film clamping can be almost completely avoided. The side copper layer of the circuit can completely avoid the side etching problem because the resist layer 40 is manufactured, the copper foil layer 20 after laser ablation is thinned, the circuit etching becomes easier, and the etching difficulty is reduced. Therefore, the circuit density of the PCB manufactured by the conventional factory can be greatly improved. Conventional PCB factories can produce PCBs with line width spacing as low as 35/35 microns using this scheme; when the scheme is used by a carrier PCB factory, the difficulty of producing the carrier with the line width spacing of 25/25 micrometers or even 20/20 micrometers is obviously reduced.
Further, in the step of cutting, a copper-clad plate is cut into a proper processing size, and the copper-clad plate is formed by coating a copper foil layer 20 on the surface of the epoxy resin plate 10.
Further, in the external light imaging step, a layer of dry film 30 is coated on the surface of the copper-clad plate, the dry film 30 is sensitized in a laser exposure mode, a circuit pattern is transferred onto the dry film 30, and then the unexposed dry film 30 is washed away through development, so that a required circuit pattern is formed.
Further, in the external light imaging step, the line width pitch of the dry film 30 is not pre-compensated by etching, and the line width pitch formed by the dry film 30 is the line width pitch after etching.
It can be appreciated that the line pitch and line width can be greatly reduced without etching compensation, thereby improving the line density.
Further, in the pattern plating step, the uncovered area of the dry film 30 is plated with a layer of copper by means of copper plating.
Further, in the film stripping step, the dry film 30 is dissolved and removed by the principle of sodium hydroxide solution or plasma etching.
In the embodiment of the invention, the film stripping step has no tin layer which is easy to react with sodium hydroxide, so that the treatment time can be prolonged as much as possible, the film stripping is ensured to be sufficient, and the film clamping can be almost completely avoided.
Further, in the resist layer manufacturing step, a resist layer 40 is formed on the entire copper surface by means of plating tin or nickel or coating an organic film.
It will be appreciated that the side walls of the circuit copper layer can be protected by the resist layer 40 to avoid undercutting the circuit copper layer.
It should be noted that, in the embodiment of the present invention, the resist layer 40 may be plated by electroplating or coated by coating.
Further, in the step of laser ablation, the resist layer 40 at the bottom of the valleys between the lines is ablated by laser, and the copper foil layer 20 below the resist layer 40 is ablated by laser more than 2 micrometers to ensure complete removal of the resist layer 40, and etching compensation is reserved at two sides of the laser ablation, wherein the compensation value is 5 micrometers to 20 micrometers on one side.
It will be appreciated that the laser ablation step is capable of removing the resist layer 40 over the circuit-side copper foil layer 20 to be processed, thereby effecting the etching operation of the copper foil layer 20.
It should be noted that, in the laser ablation step, it is necessary to ensure that the laser energy is not too high, so as to avoid complete breakdown of the underlying copper layer and ablation to the epoxy plate 10.
It should be noted that, in the laser ablation step, precise alignment is required according to a preset target on the PCB.
Further, in the laser ablation step, the thickness of the copper foil layer 20 over the ablated epoxy plate 10 is 1 to 5 microns.
It will be appreciated that, for example, in the case of producing very fine line pitches, e.g., 20/20 microns, the laser energy can be properly adjusted in this step to leave only 1-5 microns of the ablated copper foil layer 20, so that the line etching becomes easier and the etching difficulty can be significantly reduced.
Further, in the line etching step, copper exposed after laser ablation is dissolved and removed by spraying an etching solution, copper surfaces of the laser non-ablated areas are all preserved by the protection of the resist layer 40, and the side surfaces of the line are not undercut by the protection of the resist layer 40, and in the resist stripping step, the resist layer 40 above the line layer is stripped by using a resist stripper, and only the copper layer line is left.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of one of ordinary skill in the art without departing from the spirit of the present invention.
Claims (10)
1. The PCB manufacturing method for improving the circuit density is characterized by comprising the following steps of:
Cutting, external light imaging, pattern electroplating, film stripping, resist layer manufacturing, laser ablation, circuit etching and resist layer stripping.
2. The method for manufacturing a PCB with improved circuit density according to claim 1, wherein in the step of cutting, a copper-clad plate is cut into a suitable processing size, and the copper-clad plate is a copper foil layer on the surface of an epoxy resin plate.
3. The method for manufacturing the PCB with the improved circuit density according to claim 1, wherein in the external light imaging step, a layer of dry film is coated on the surface of the copper-clad plate, the dry film is sensitized by a laser exposure mode, a circuit pattern is transferred onto the dry film, and then the unexposed dry film is washed out by developing, so that a required circuit pattern is formed.
4. The method of claim 3, wherein the line width pitch of the dry film is not pre-compensated by etching in the step of external light imaging, and the line width pitch of the dry film is the line width pitch after etching.
5. The method for manufacturing a PCB with increased circuit density according to claim 1, wherein in the pattern plating step, a copper layer is plated on the uncovered area of the dry film by means of copper plating.
6. The method of claim 1, wherein the dry film is dissolved and removed by the principle of sodium hydroxide solution or plasma etching in the film removing step.
7. The method for manufacturing a PCB with improved circuit density according to claim 1, wherein in the resist layer manufacturing step, a resist layer is formed on the entire copper surface by means of plating tin or nickel or coating an organic film.
8. The method for manufacturing a PCB with increased line density according to claim 1, wherein in the step of laser ablation, a resist layer at the bottom of the valleys between the lines is ablated by laser, and the laser ablation is performed by ablating a copper layer under the resist layer by more than 2 microns to ensure complete removal of the resist layer, and etching compensation is reserved at both sides of the laser ablation, wherein the compensation value is 5 microns to 20 microns on one side.
9. The method of claim 8, wherein in the step of laser ablation, the thickness of the copper layer over the ablated epoxy plate is 1 to 5 microns.
10. The method of claim 1, wherein in the step of etching the circuit, the copper exposed after laser ablation is dissolved and removed by spraying an etching solution, copper surfaces of the laser non-ablated areas remain due to protection of the resist layer, and the side surfaces of the circuit are not undercut due to protection of the resist layer, and in the step of stripping the resist layer, a resist layer stripper is used to strip the resist layer above the circuit layer, leaving only the copper layer circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410770727.1A CN118632445A (en) | 2024-06-14 | 2024-06-14 | PCB manufacturing method for improving circuit density |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410770727.1A CN118632445A (en) | 2024-06-14 | 2024-06-14 | PCB manufacturing method for improving circuit density |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN118632445A true CN118632445A (en) | 2024-09-10 |
Family
ID=92609257
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410770727.1A Pending CN118632445A (en) | 2024-06-14 | 2024-06-14 | PCB manufacturing method for improving circuit density |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN118632445A (en) |
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2024
- 2024-06-14 CN CN202410770727.1A patent/CN118632445A/en active Pending
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