CN109548321B - Manufacturing method of positive undercut PCB - Google Patents
Manufacturing method of positive undercut PCB Download PDFInfo
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- CN109548321B CN109548321B CN201811502710.9A CN201811502710A CN109548321B CN 109548321 B CN109548321 B CN 109548321B CN 201811502710 A CN201811502710 A CN 201811502710A CN 109548321 B CN109548321 B CN 109548321B
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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
- H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
- H05K3/42—Plated through-holes or plated via connections
- H05K3/423—Plated through-holes or plated via connections characterised by electroplating method
- H05K3/424—Plated through-holes or plated via connections characterised by electroplating method by direct electroplating
Abstract
The invention discloses a manufacturing method of a positive concave etched PCB, which comprises the steps of drilling an auxiliary hole on a production board, metalizing the auxiliary hole to serve as a conductive layer during electroplating, then drilling a connecting hole, and radially thickening an inner layer circuit copper layer in the connecting hole through electroplating to expose and protrude out of a hole wall, so that a three-dimensional connection is formed between the later-stage electroplated hole wall copper layer and the protruding inner layer circuit copper layer, the high reliability requirements of products such as aerospace, military industry and the like are met, the reliability of the PCB is improved, resin and glass fiber yarns on the hole wall can be guaranteed not to be damaged, the flatness of the hole wall is maintained, and the quality of the PCB is improved; the method of the invention replaces the conventional method for producing the undercut PCB by using the glass etching solution, and can avoid the problems of environmental pollution, potential safety hazard, rough hole wall and the like.
Description
Technical Field
The invention relates to the technical field of printed circuit board manufacturing, in particular to a manufacturing method of a positive undercut PCB.
Background
The positive undercut printed circuit board, called an undercut board for short, refers to a printed circuit board in which epoxy resin and glass fiber filaments on a hole wall are etched to a certain depth after drilling, so that an inner layer circuit copper layer is completely exposed, and then the inner layer circuit copper layer and the hole wall copper layer are connected in a three-dimensional manner through hole wall metallization, so that high-reliability electrical connection is met.
In the current market, most printed circuit board products do not need to form the three-dimensional connection between the inner circuit copper layer and the hole wall copper plating layer, but for some aerospace and military products, due to the severe environments such as extreme heat, extreme cold, high pressure and the like, the requirements on the reliability of electronic components are extremely strict compared with those of common products, and the concave corrosion circuit board is generally required to be formed.
The problem to be solved first in the production of the positive-pitting PCB is that the pitting removes partial resin and glass fiber cloth on the hole wall, so that the inner layer circuit copper layer is fully exposed; the common treatment method at present is to remove resin by removing the drilling dirt and then remove the glass fiber cloth by using the glass etching solution.
The use of glass etching solution for making an etching plate has the following disadvantages:
1. the main component of the glass etching solution is hydrofluoric acid, which is an extremely dangerous chemical, has extremely strong corrosivity, high operation requirement, great environmental pollution and great potential safety hazard of production;
2. the biting rate of the glass etching solution is not easy to control, the glass fiber cloth at different parts of the hole wall bites unevenly, the roughness of the hole wall is large, and the phenomenon of folding and plating is easy to occur.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a manufacturing method of a positive-concave-etching PCB, which thickens an inner-layer circuit copper layer through electroplating and exposes the inner-layer circuit copper layer to protrude out of a hole wall, so that the inner-layer circuit copper layer and the hole wall copper layer form three-dimensional connection, the high reliability requirements of products such as aerospace, military industry and the like are met, and the problems of environmental pollution, potential safety hazard, rough hole wall and the like can be avoided.
In order to solve the technical problem, the invention provides a manufacturing method of a positive-pitting PCB, which comprises the following steps:
s1, drilling auxiliary holes on a production board, wherein the production board is a multilayer board with an inner-layer circuit manufactured;
s2, metallizing the auxiliary hole through copper deposition and full-board electroplating, wherein the hole wall copper layer is communicated with the inner-layer circuit;
s3, drilling a connecting hole on the production board;
s4, pasting a film on the production board, and windowing at the position on the film corresponding to the connecting hole;
s5, electroplating the connecting hole to enable the inner layer circuit copper layer in the connecting hole to protrude out of the hole wall, and then removing the film; the auxiliary hole after metallization is used as a conductive layer during electroplating;
s6, pasting a film on the production board, and windowing at the position corresponding to the auxiliary hole; then, removing the hole wall copper layer in the auxiliary hole by etching;
s7, filling resin in the auxiliary holes and grinding the auxiliary holes to be flat;
s8, metallizing the connecting holes by copper deposition and full-board electroplating;
and S9, manufacturing an outer layer circuit, manufacturing a solder mask layer, performing surface treatment and molding on the production board in sequence to obtain the PCB.
Preferably, in step S2, the whole board is electroplated for 50min at a current density of 2.1ASF, and the thickness of the hole copper is more than or equal to 15 μm.
Preferably, the step S31 is further included between the steps S3 and S4: and carrying out glue removing treatment on the connecting hole.
Preferably, in step S4, the size of the window is 0.1mm larger than the size of the connection hole.
Preferably, in step S5, the inner layer circuit copper layer is electroplated for 240min at a current density of 1.1ASD, so as to protrude 20-50 μm from the hole wall.
Preferably, in step S6, the size of the opening is 0.075mm larger than the size of the auxiliary hole on one side.
Preferably, in step S8, the whole board is electroplated for 30min at a current density of 1.1ASF, and the thickness of the hole copper is more than or equal to 5 μm.
Preferably, in step S1, auxiliary holes are drilled in the production board corresponding to the open regions or large copper areas of the inner layer circuits.
Preferably, the production board is a multilayer board formed by laminating an inner core board and an outer copper foil into a whole through a prepreg.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, an auxiliary hole is drilled and metalized, and then used as a conductive layer during electroplating, and then the inner layer circuit copper layer in the connecting hole is radially thickened and exposed to protrude out of the hole wall through electroplating, so that three-dimensional connection is formed between the later-stage electroplated hole wall copper layer and the protruding inner layer circuit copper layer, the high reliability requirements of products such as aerospace and military industry are met, the reliability of a PCB is improved, resin and glass fiber yarns on the hole wall can be prevented from being damaged, the flatness of the hole wall is maintained, and the quality of the PCB is improved; the method of the invention replaces the conventional method for producing the undercut PCB by using the glass etching solution, and can avoid the problems of environmental pollution, potential safety hazard, rough hole wall and the like.
Drawings
FIG. 1 is a schematic view of an embodiment after a connection hole is drilled in a production board;
FIG. 2 is a schematic diagram of an embodiment of an electroplated inner layer circuit copper layer in a via hole.
Detailed Description
In order to more fully understand the technical contents of the present invention, the technical solutions of the present invention will be further described and illustrated with reference to specific embodiments.
Example 1
The embodiment provides a manufacturing method of a positive undercut PCB, which comprises the following specific processes:
(1) cutting: the core board is cut according to the dimension of the jointed board of 520mm multiplied by 620mm, the thickness of the core board is 0.075mm, and the thickness of the outer layer copper foil is 1 OZ.
(2) Inner layer circuit manufacturing (negative film process): transferring inner layer patterns, coating a photosensitive film on a core plate by using a vertical coating machine, controlling the film thickness of the photosensitive film to be 8 mu m, and completing inner layer line exposure on the core plate by using 5-6 exposure rulers (21 exposure rulers) by using a full-automatic exposure machine; etching the inner layer, etching the exposed and developed core board to form an inner layer circuit, wherein the line width of the inner layer is measured to be 3 mil; and (4) inner layer AOI, and then, detecting defects of an inner layer circuit, such as open short circuit, circuit notch, circuit pinhole and the like, and performing defect scrapping treatment, wherein a defect-free product is discharged to the next flow.
(3) And pressing: the core board passes through a vertical blackening process, then the core board and the outer copper foil are pre-laminated together by using prepregs (the copper foil, the prepregs, the core board, the prepregs and the copper foil are arranged from top to bottom in a concrete board arrangement sequence), and then the laminated board is pressed by selecting proper laminating conditions according to the Tg of the board material to form the production board.
(4) Drilling: according to the drilling data, auxiliary holes 1 (shown in figure 1) are drilled in the production board by using a mechanical drilling mode; specifically, need bore the inlayer copper ring region of connecting hole to the later stage to the principle (be located near the connecting hole that the later stage was bored out) drills out the auxiliary hole on the production board nearby, and the auxiliary hole position distributes according to the inlayer circuit, and the preferred choice inlayer is spacious to be distinguished or big copper face is regional, ensures that auxiliary hole and inlayer copper ring are at same network (being linked together promptly).
(5) And copper deposition: and depositing a layer of thin copper on the wall of the auxiliary hole in a chemical reaction mode to provide a foundation for the subsequent full-board electroplating, testing the backlight to 10 grades, wherein the thickness of the deposited copper in the hole is 0.3-0.7 mu m, and the copper layer in the hole is communicated with the copper layer of the inner-layer circuit.
(6) And electroplating the whole plate: according to the principle of electrochemical reaction, a layer of copper is electroplated on the basis of copper deposition, and specifically, the whole plate is electroplated for 50min at the current density of 2.1ASF, so that the thickness of the hole copper is more than or equal to 15 mu m.
(7) Drilling: according to the drilling data, a connection hole 2 (shown in fig. 1) for connecting the inner and outer layer circuits is drilled in the production board by using a mechanical drilling method.
(8) Removing glue residues: the production plate is subjected to degumming residue treatment by a plasma degumming method to remove the drilling dirt (the degumming residue) on the production plate and obtain a smooth and flat hole wall.
(9) Plating a hole pattern: pasting a film on the production board, and windowing at the position corresponding to the connecting hole on the dry film through exposure and development; the size of the window is 0.1mm larger than that of the connecting hole on one side.
(10) Plating holes: electroplating the connecting hole, radially thickening the inner layer circuit copper layer in the connecting hole to make the inner layer circuit copper layer protrude out of the hole wall (as shown in figure 2), and then removing the film; during electroplating, the auxiliary hole after metallization is used as a conductive layer (namely, the auxiliary hole has the same effect as an electroplating lead), and electroplating is carried out for 240min at the current density of 1.1ASD, so that the electroplating thickened copper layer 3 protruding out of the hole wall in the copper layer of the inner layer circuit is 20-50 mu m; and the surface copper foil at the connecting hole is also thickened radially.
(11) Outer layer pattern: pasting a film on the production board, and windowing at the position corresponding to the auxiliary hole on the dry film through exposure and development; the size unilateral of this windowing is greater than the size of auxiliary hole 0.075mm, ensures later stage with the downthehole pore wall copper layer etching of auxiliary hole clean.
(12) And etching: and etching the hole wall copper layer in the auxiliary hole to ensure that the hole wall has no copper.
(13) Selective resin hole plugging: and filling resin into the auxiliary holes, and removing the resin protruding out of the plate surface through a belt sanding plate to enable the plate surface to be flush with the resin.
(14) And copper deposition: a layer of thin copper is deposited on the wall of the connecting hole in a chemical reaction mode to provide a foundation for the subsequent full-board electroplating, the backlight test is 10-level, and the thickness of the copper deposition in the hole is 0.3-0.7 mu m.
(15) And electroplating the whole plate: according to the principle of electrochemical reaction, a layer of copper is electroplated on the basis of copper deposition, specifically, the whole plate is electroplated for 30min at the current density of 1.1ASF, and the thickness of the hole copper is more than or equal to 5 mu m.
(16) And manufacturing an outer layer circuit (positive process): transferring an outer layer pattern, completing outer layer circuit exposure on a production board by using a full-automatic exposure machine and a positive film circuit film and using 5-7 exposure rulers (21 exposure rulers), and forming an outer layer circuit pattern on the production board through development; electroplating an outer layer pattern, then respectively plating copper and tin on a production plate, wherein the copper plating is performed for 150min by full-plate electroplating at the current density of 1.0-2.2ASD, the surface copper is plated to 1OZ, the hole wall copper thickness is thickened to be more than or equal to 25mm, so that a smooth and uniform hole wall copper plating layer with high reliability is obtained, the hole wall copper layer and an inner layer circuit copper layer form three-dimensional connection, and the tin plating is performed for 10min at the current density of 1.2ASD and has the tin thickness of 3-5 mu m; then sequentially removing the film, etching and removing tin, and etching an outer layer circuit on the production board; and the outer layer AOI uses an automatic optical detection system to detect whether the outer layer circuit has the defects of open circuit, gap, incomplete etching, short circuit and the like by comparing with CAM data.
(17) Solder resist and silk screen printing of characters: printing TOP surface solder resist ink by adopting a white screen, and adding a UL mark to TOP surface characters; specifically, a protective layer for preventing the bridging between the wires during welding, providing a permanent electrical environment and resisting chemical corrosion is coated on the wires and the base material which do not need welding, and the protective layer has the function of beautifying the appearance.
(18) Surface treatment (nickel-gold deposition): the copper surface of the welding pad at the solder stop windowing position is communicated with a chemical principle, a nickel layer and a gold layer with certain required thickness are uniformly deposited, and the thickness of the nickel layer is as follows: 3-5 μm; the thickness of the gold layer is as follows: 0.05-0.1 μm.
(19) And electrical test: testing the electrical conduction performance of the finished board, wherein the board use testing method comprises the following steps: and (5) flying probe testing.
(20) And forming: according to the prior art and according to the design requirement, routing the shape, and manufacturing the PCB with the tolerance of +/-0.05 mm.
(21) FQC: and (4) inspecting the PCB appearance according to the customer acceptance standard and the I's inspection standard, and timely repairing the PCB if the PCB has defects so as to ensure that excellent quality control is provided for customers.
(22) FQA: and measuring whether the appearance, the hole copper thickness, the dielectric layer thickness, the green oil thickness, the inner layer copper thickness and the like of the PCB meet the requirements of customers or not.
(23) And packaging: and hermetically packaging the PCBs according to the packaging mode and the packaging quantity required by the customer, putting a drying agent and a humidity card, and then delivering.
The technical solutions provided by the embodiments of the present invention are described in detail above, and the principles and embodiments of the present invention are explained herein by using specific examples, and the descriptions of the embodiments are only used to help understanding the principles of the embodiments of the present invention; meanwhile, for a person skilled in the art, according to the embodiments of the present invention, there may be variations in the specific implementation manners and application ranges, and in summary, the content of the present description should not be construed as a limitation to the present invention.
Claims (9)
1. A manufacturing method of a positive undercut PCB is characterized by comprising the following steps:
s1, drilling auxiliary holes on a production board, wherein the production board is a multilayer board with an inner-layer circuit manufactured;
s2, metallizing the auxiliary hole through copper deposition and full-board electroplating, wherein the hole wall copper layer is communicated with the inner-layer circuit;
s3, drilling a connecting hole on the production board;
s4, pasting a film on the production board, and windowing at the position on the film corresponding to the connecting hole;
s5, electroplating the connecting hole to enable the inner layer circuit copper layer in the connecting hole to protrude out of the hole wall, and then removing the film; during electroplating, the hole wall copper layer of the auxiliary hole after metallization is used as a conductive layer of the inner layer circuit, and the conductive layer has the same function as the electroplating lead;
s6, pasting a film on the production board, and windowing at the position corresponding to the auxiliary hole; then, removing the hole wall copper layer in the auxiliary hole by etching;
s7, filling resin in the auxiliary holes and grinding the auxiliary holes to be flat;
s8, metallizing the connecting holes by copper deposition and full-board electroplating;
and S9, manufacturing an outer layer circuit, manufacturing a solder mask layer, performing surface treatment and molding on the production board in sequence to obtain the PCB.
2. The method for manufacturing a positive undercut PCB according to claim 1, wherein in step S2, the full-plate electroplating is performed for 50min at a current density of 2.1ASF, and the hole copper thickness is greater than or equal to 15 μm.
3. The method for manufacturing a positive undercut PCB according to claim 1, further comprising a step S31 between the steps S3 and S4: and carrying out glue removing treatment on the connecting hole.
4. The method of manufacturing a forward concave etched PCB as recited in claim 1, wherein in step S4, the size of the window is 0.1mm larger than the size of the connection hole on one side.
5. The method of claim 1, wherein in step S5, the inner layer circuit copper layer is electroplated at 1.1ASD current density for 240min to protrude from the hole wall by 20-50 μm.
6. The method of fabricating a forward recessing PCB as recited in claim 1, wherein in step S6, the size of the window is 0.075mm larger than the size of the auxiliary hole on one side.
7. The method for manufacturing a forward etching PCB according to claim 1, wherein in step S8, the full-plate electroplating is performed for 30min at a current density of 1.1ASF, and the hole copper thickness is greater than or equal to 5 μm.
8. The method for manufacturing a positive-concavity PCB according to claim 1, wherein in step S1, auxiliary holes are drilled in the production board corresponding to the open areas or large copper areas of the inner layer circuits.
9. The method for manufacturing a forward concave etched PCB according to any one of claims 1 to 8, wherein the production board is a multi-layer board formed by laminating an inner core board and an outer copper foil together by a prepreg.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811502710.9A CN109548321B (en) | 2018-12-10 | 2018-12-10 | Manufacturing method of positive undercut PCB |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811502710.9A CN109548321B (en) | 2018-12-10 | 2018-12-10 | Manufacturing method of positive undercut PCB |
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| CN109548321A CN109548321A (en) | 2019-03-29 |
| CN109548321B true CN109548321B (en) | 2021-06-25 |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111712052A (en) * | 2020-07-13 | 2020-09-25 | 广东喜珍电路科技有限公司 | Back drilling hole sealing method for PCB outer shielding layer |
| CN112930033B (en) * | 2021-01-22 | 2022-05-03 | 景旺电子科技(珠海)有限公司 | Circuit board manufacturing method |
| CN115038261A (en) * | 2022-05-06 | 2022-09-09 | 江门崇达电路技术有限公司 | Manufacturing method of PCB large-size metallized slotted hole |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1196016A2 (en) * | 2000-10-03 | 2002-04-10 | Hitachi, Ltd. | Wiring substrate and manufacturing method of the same along with electroless copper plating solution used therefor |
| CN103533766A (en) * | 2013-10-22 | 2014-01-22 | 东莞生益电子有限公司 | Fabrication method of circuit board and circuit board fabricated by method |
| CN108449887A (en) * | 2018-04-10 | 2018-08-24 | 生益电子股份有限公司 | A kind of production method and PCB of the thick copper of part hole wall plating |
| CN108449889A (en) * | 2018-03-23 | 2018-08-24 | 深圳崇达多层线路板有限公司 | Production method is just recessed in a kind of wiring board |
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2018
- 2018-12-10 CN CN201811502710.9A patent/CN109548321B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1196016A2 (en) * | 2000-10-03 | 2002-04-10 | Hitachi, Ltd. | Wiring substrate and manufacturing method of the same along with electroless copper plating solution used therefor |
| CN103533766A (en) * | 2013-10-22 | 2014-01-22 | 东莞生益电子有限公司 | Fabrication method of circuit board and circuit board fabricated by method |
| CN108449889A (en) * | 2018-03-23 | 2018-08-24 | 深圳崇达多层线路板有限公司 | Production method is just recessed in a kind of wiring board |
| CN108449887A (en) * | 2018-04-10 | 2018-08-24 | 生益电子股份有限公司 | A kind of production method and PCB of the thick copper of part hole wall plating |
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