阅读说明：本技术 一种高可靠性印制电路板的制作方法 (Manufacturing method of high-reliability printed circuit board ) 是由 胡永国 寻瑞平 冯兹华 张细海 叶卫 于 2021-07-14 设计创作，主要内容包括：本发明公开了一种高可靠性印制电路板的制作方法,该印制电路板由两个外层芯板和至少一个内层芯板压合而成,制作方法包括以下步骤：在压合前或压合后先将两外层芯板中位于外侧的铜面厚度减薄至8-10μm；而后在板上钻欲填塞树脂的塞孔；依次通过沉铜和全板电镀使塞孔金属化；在塞孔中填塞树脂并固化,而后通过磨板使板面平整,磨板后使板面铜层的厚度控制在22-25μm；在板上钻出通孔,并依次通过沉铜和全板电镀使通孔金属化；而后依次在板上制作外层线路、制作阻焊层、表面处理和成型,制得高可靠性印制电路板。本发明方法通过先减薄外层铜面的厚度以加大包覆铜的厚度,解决常规现有技术包覆铜厚度不够及无法制作的问题。(The invention discloses a method for manufacturing a high-reliability printed circuit board, which is formed by laminating two outer core boards and at least one inner core board, and comprises the following steps: before or after pressing, the thickness of the copper surface positioned at the outer side in the two outer-layer core plates is reduced to 8-10 mu m; then drilling a plug hole to be filled with resin on the plate; sequentially carrying out copper deposition and full-plate electroplating to metalize the plug hole; filling resin in the plug holes and curing, then grinding the board to flatten the board surface, and controlling the thickness of the copper layer on the board surface to be 22-25 mu m after grinding the board; drilling a through hole on the board, and metallizing the through hole by copper deposition and full-board electroplating in sequence; and then sequentially manufacturing an outer layer circuit, a solder mask layer, surface treatment and molding on the board to obtain the high-reliability printed circuit board. The method of the invention firstly thins the thickness of the outer layer copper surface to increase the thickness of the cladding copper, and solves the problems that the cladding copper in the conventional prior art is not enough in thickness and can not be manufactured.)

1. A manufacturing method of a high-reliability printed circuit board is provided, the printed circuit board is formed by laminating two outer core boards positioned on an outer layer and at least one inner core board positioned on an inner layer, the thickness of copper layers on two surfaces of the outer core board and the inner core board is 0.5oz, and the manufacturing method is characterized by comprising the following steps:

s1, before or after pressing, the thickness of the copper surface on the outer side of the two outer-layer core boards is reduced to 8-10 μm;

s2, drilling a plug hole to be filled with resin on the plate;

s3, sequentially carrying out copper precipitation and full-plate electroplating to metalize the plug hole;

s4, filling resin in the plug holes and curing, then grinding the board to enable the board surface to be flat, and controlling the thickness of the copper layer on the board surface to be 22-25 mu m after grinding the board;

s5, drilling a through hole on the board, and metallizing the through hole by copper deposition and full board electroplating in sequence;

and S6, sequentially manufacturing an outer layer circuit, a solder mask layer, surface treatment and molding on the board to obtain the high-reliability printed circuit board.

2. The method for manufacturing a high reliability printed circuit board according to claim 1, wherein the step S1 specifically comprises the steps of:

s10, firstly, thinning the copper layer on one surface of the two outer-layer core boards to 8-10 mu m through microetching to be used as a thinning surface;

s11, manufacturing an inner layer circuit on the other surface of the inner layer core plate and the other surface of the two outer layer core plates which is not thinned;

and S12, overlapping the two outer core plates and the inner core plate according to the lamination sequence, and pressing to form the production plate, wherein the thinned surfaces of the two outer core plates are positioned at the outer side of the production plate.

3. The method of claim 2, wherein in step S10, when the copper layer on one surface is thinned, the other surface of the two outer core boards is protected by a film.

4. The method for manufacturing a high reliability printed circuit board according to claim 1, wherein the step S1 specifically comprises the steps of:

s10, firstly, thinning the copper layers on the two surfaces of the two outer-layer core boards to 8-10 mu m through microetching to be used as thinning surfaces;

s11, plating the thickness of the copper layer on one surface of the outer core board to 40 +/-5 mu m through full-board electroplating to serve as a thickened surface;

s12, manufacturing inner layer circuits on the thickened surfaces of the inner layer core board and the two outer layer core boards;

and S13, overlapping the two outer core plates and the inner core plate according to the lamination sequence, and pressing to form the production plate, wherein the thinned surfaces of the two outer core plates are positioned at the outer side of the production plate.

5. The method of claim 4, wherein in step S11, when the copper layer on one surface is thickened, the other surface of the two outer core boards is coated with a film to form a plating resist.

6. The method for manufacturing a high reliability printed circuit board according to claim 1, wherein the step S1 specifically comprises the steps of:

s10, manufacturing an inner layer circuit on one surface of the inner layer core board and the two outer layer core boards;

s11, laminating the two outer core boards and the inner core board according to the lamination sequence, and then pressing to form a production board, wherein the surface of the two outer core boards, on which the inner circuit is not manufactured, is positioned at the outer side of the production board;

and S12, thinning the copper layers on the two surfaces of the production plate to 8-10 mu m by microetching.

7. The method for manufacturing a highly reliable printed circuit board according to any one of claims 1 to 6, wherein the thickness of the copper layer on the board surface is plated to 31 to 33 μm after the full board plating in step S3.

8. The method for manufacturing a high reliability printed circuit board according to any one of claims 1 to 6, further comprising the steps between steps S3 and S4 of:

s31, manufacturing a plated hole pattern on the plate;

and S32, thickening the hole wall copper layer of the plug hole by hole filling electroplating.

9. The method for manufacturing a high reliability printed circuit board according to any one of claims 1 to 6, wherein in step S4, the surface of the board is flattened by ceramic grinding.

10. The method for manufacturing a high reliability printed circuit board according to any one of claims 1 to 6, wherein after the plug hole and the through hole are drilled, the drilling contamination is removed by plasma degumming.

Technical Field

The invention relates to the technical field of printed circuit board manufacturing, in particular to a manufacturing method of a high-reliability printed circuit board.

Background

The multilayer Printed Circuit Board (PCB) realizes the electrical connection among all layers of circuits of the circuit board by the processes of manufacturing all inner-layer circuits, pressing, drilling, copper deposition, board electricity, electroplating and the like, and generally requires the thickness of hole walls and surface copper to reach certain requirements in order to ensure certain electrical performance and reliability.

In the current market, most circuit board products only need to adopt conventional PCB hole metallization technology can, but to some products such as aerospace, war industry, because severe environment such as its applied extreme heat, extreme cold, high pressure, its requirement to the reliability is higher than ordinary product, can generally require the hole to form cladding copper, and cladding copper thickness will satisfy the relevant standard of IPC (the hole cladding one deck reaches the copper layer of requiring thickness, and forms an entirety with hole wall copper), cladding copper is the part that the hole department plated out with the hole wall copper layer simultaneously.

The prior art process comprises the following steps: front process → pressing (outer copper surface is generally 18 μm) → flow removing glue → drilling resin hole plugging (grinding after drilling → plasma desmearing → outer copper deposition → outer plate electric → outer hole plating pattern → plating hole → film removal → resin hole plugging → ceramic grinding plate → outer hole drilling → plasma desmearing 2 → outer copper deposition 2 → outer plate electric 2 → outer pattern → pattern electroplating → outer etching → silk screen welding resistance, character → nickel deposition → electric testing → molding → FQC → FQA → press fitting

The prior art has hidden quality troubles, after pressing and resin hole plugging, the surface copper is plated at 18 microns (0.5OZ), the surface copper is plated to 31-33 microns through copper deposition and full-plate electroplating copper plating, a ceramic grinding plate is ground to 22-25 microns after the resin hole plugging, theoretically, the coated copper surface is only 4-7 microns (the thickness of the surface copper subtracted from the thickness of the copper surface after grinding the plate is the coated copper electroplated together with a hole wall copper layer), the thickness compensation of the coated copper is insufficient, and the insufficient coated copper is caused by the fact that the ceramic grinding plate needs to be ground for multiple times, and the reasons of copper plating uniformity and the uniformity of multiple times of plate grinding are accumulated.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a method for manufacturing a high-reliability printed circuit board, which solves the problems that the thickness of the clad copper in the conventional prior art is not enough and the clad copper can not be manufactured by firstly reducing the thickness of the outer layer copper surface to increase the thickness of the clad copper.

In order to solve the technical problems, the invention provides a manufacturing method of a high-reliability printed circuit board, the printed circuit board is formed by laminating two outer core boards positioned at an outer layer and at least one inner core board positioned at an inner layer, the thickness of copper layers on the two surfaces of the outer core board and the inner core board is 0.5oz, and the manufacturing method comprises the following steps:

s1, before or after pressing, the thickness of the copper surface on the outer side of the two outer-layer core boards is reduced to 8-10 μm;

s2, drilling a plug hole to be filled with resin on the plate;

s3, sequentially carrying out copper precipitation and full-plate electroplating to metalize the plug hole;

s4, filling resin in the plug holes and curing, then grinding the board to enable the board surface to be flat, and controlling the thickness of the copper layer on the board surface to be 22-25 mu m after grinding the board;

s5, drilling a through hole on the board, and metallizing the through hole by copper deposition and full board electroplating in sequence;

and S6, sequentially manufacturing an outer layer circuit, a solder mask layer, surface treatment and molding on the board to obtain the high-reliability printed circuit board.

Further, step S1 specifically includes the following steps:

s10, firstly, thinning the copper layer on one surface of the two outer-layer core boards to 8-10 mu m through microetching to be used as a thinning surface;

s11, manufacturing an inner layer circuit on the other surface of the inner layer core plate and the other surface of the two outer layer core plates which is not thinned;

and S12, overlapping the two outer core plates and the inner core plate according to the lamination sequence, and pressing to form the production plate, wherein the thinned surfaces of the two outer core plates are positioned at the outer side of the production plate.

Further, in step S10, when the copper layer on one surface is thinned, the other surface of the two outer core boards is protected by a film.

Further, step S1 specifically includes the following steps:

s10, firstly, thinning the copper layers on the two surfaces of the two outer-layer core boards to 8-10 mu m through microetching to be used as thinning surfaces;

s11, plating the thickness of the copper layer on one surface of the outer core board to 40 +/-5 mu m through full-board electroplating to serve as a thickened surface;

s12, manufacturing inner layer circuits on the thickened surfaces of the inner layer core board and the two outer layer core boards;

and S13, overlapping the two outer core plates and the inner core plate according to the lamination sequence, and pressing to form the production plate, wherein the thinned surfaces of the two outer core plates are positioned at the outer side of the production plate.

Further, in step S11, when the copper layer on one surface is thickened, the plating resist layer is formed on the other surface of the two outer core boards by film pasting.

Further, step S1 specifically includes the following steps:

s10, manufacturing an inner layer circuit on one surface of the inner layer core board and the two outer layer core boards;

s11, laminating the two outer core boards and the inner core board according to the lamination sequence, and then pressing to form a production board, wherein the surface of the two outer core boards, on which the inner circuit is not manufactured, is positioned at the outer side of the production board;

and S12, thinning the copper layers on the two surfaces of the production plate to 8-10 mu m by microetching.

Further, in step S3, the thickness of the copper layer on the board surface is plated to 31-33 μm after the full-board electroplating.

Further, the following steps are included between steps S3 and S4:

s31, manufacturing a plated hole pattern on the plate;

and S32, thickening the hole wall copper layer of the plug hole by hole filling electroplating.

Further, in step S4, the board surface is smoothed by ceramic grinding.

Furthermore, after the plug hole and the through hole are drilled, the drilling dirt is removed in a plasma glue removing mode.

Compared with the prior art, the invention has the following beneficial effects:

the thickness of copper layers positioned on two outer layers is reduced to 8-10 mu m before or after lamination, after resin hole plugging is drilled, the hole wall copper layer and the outer layer copper surface of the hole plugging are simultaneously thickened through copper deposition and full-plate electroplating until the thickness of a ceramic grinding plate is equal to the plate surface thickness controlled to be 22-25 mu m, under the condition, the thickness of cladding copper on the two outer layer copper surfaces is the thickness (22-25 mu m) of the copper layer after the grinding plate minus the thickness (8-10 mu m) of bottom copper, namely, the theoretical protection copper thickness of the cladding copper is 10-17 mu m, and the theoretical protection copper thickness is 6-10 mu m more than the original 4-7 mu m, so that the resin cladding copper can meet the IPC secondary standard, and the high reliability requirements of products such as aerospace hole plugging, military industry and the like are met.

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 manufacturing method of the high-reliability printed circuit board shown in this embodiment sequentially includes the following processing steps:

(1) cutting: two outer core plates and one inner core plate are arranged according to the size of the jointed board of 520mm multiplied by 620mm, the thickness of the outer core plate and the thickness of the inner core plate are both 0.2mm, and the thickness of the copper layers on the two surfaces of the core plates are both 0.5oz (approximately equal to 18 mu m).

(2) Micro-etching: firstly, a film is pasted on one surface of the two outer core boards and exposed to form a protective layer, then the surface of the outer core board which is not pasted with the film is subjected to micro-etching treatment, the thickness of the copper layer on the surface is etched and thinned to 8-10 mu m to be used as a thinning surface, and then the film is removed.

(3) Inner layer circuit manufacturing (negative film process): transferring an inner layer pattern, coating photosensitive films on the two outer layer core plates and the inner layer core plate by using a vertical coating machine, controlling the film thickness of the photosensitive films to be 8 mu m, completing inner layer circuit exposure by using a full-automatic exposure machine and 5-6 exposure rulers (21 exposure rulers), wherein during exposure, the film on the thinning surface in the two outer layer core plates is exposed on the whole surface to form a protective layer, and forming an inner layer circuit pattern after development; etching the inner layer, etching the unmagnified surfaces of the exposed and developed inner layer core board and the two outer layer core boards to form an inner layer circuit, wherein the line width of the inner layer is 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.

(4) And (3) laminating: and (3) brown oxidizing at a speed of brown oxidizing according to the thickness of the bottom copper, sequentially overlapping the outer core plate, the prepreg, the inner core plate, the prepreg and the outer core plate according to requirements, and then laminating the laminated plate by selecting proper laminating conditions according to the Tg of the plate to form a production plate, wherein the thinned surfaces of the two outer core plates are positioned at the outer side of the production plate, namely the thickness of the bottom copper in the surface of the outer layer of the production plate is 8-10 mu m.

(5) Drilling: according to the known drilling technique, the holes to be filled with resin are drilled in the production plate according to the design requirements.

(6) Removing glue residues: and removing the drilling dirt on the plate by adopting a plasma degumming mode.

(7) Copper deposition: and (3) depositing a layer of thin copper on the plate surface and the hole wall by using an electroless copper plating method, and testing the backlight to 10 grades, wherein the thickness of the deposited copper in the hole is 0.5 mu m.

(8) Electroplating the whole plate: and performing full-plate electroplating for 60min at a current density of 18ASF, and thickening the thicknesses of the hole copper and the plate surface copper layer to ensure that the thickness of the plate surface copper layer is additionally plated to 31-33 mu m.

(9) Plating a hole pattern: and pasting a film on the production board, and windowing at the position corresponding to the plug hole after exposure and development in sequence to form a plated hole pattern.

(10) Hole filling and electroplating: hole wall copper layers of the plug holes are thickened through hole filling electroplating;

(11) resin hole plugging: filling resin in the plug holes and curing, then removing the resin protruding out of the board surface by ceramic grinding board to make the board surface flat, and controlling the thickness of the copper layer on the board surface to be 22-25 μm after grinding the board.

(12) Drilling an outer layer: according to the known drilling technique, through holes are drilled in the production plate according to the design requirements.

(13) Removing glue residues: and removing the drilling dirt on the plate by adopting a plasma degumming mode.

(14) Copper deposition: and (3) depositing a layer of thin copper on the plate surface and the hole wall by using an electroless copper plating method, and testing the backlight to 10 grades, wherein the thickness of the deposited copper in the hole is 0.5 mu m.

(15) Electroplating the whole plate: and performing full-plate electroplating for 20min at the current density of 18ASF to increase the thickness of the hole copper and the plate surface copper layer.

(16) Manufacturing an outer layer circuit (positive process): transferring an outer layer pattern, completing outer layer line exposure by using a full-automatic exposure machine and a positive film line film with 5-7 exposure rulers (21 exposure rulers), and forming an outer layer line pattern on a production board through development; electroplating an outer layer pattern, then respectively plating copper and tin on the production plate, setting electroplating parameters according to the required finished copper thickness, wherein the copper plating is carried out for 60min at the current density of 1.8ASD, and the tin plating is carried out for 10min at the current density of 1.2ASD, and the tin thickness is 3-5 mu m; then sequentially removing the film, etching and removing tin, and etching an outer layer circuit on the production board, wherein the copper thickness of the outer layer circuit is more than or equal to 70 mu m; 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: after the solder resist ink is printed on the surface of the production board in a silk-screen manner, the solder resist ink is cured into a solder resist layer through pre-curing, exposure, development and thermocuring treatment in sequence; specifically, the TOP surface solder resist ink is added with a UL mark on the TOP surface character, so that a protective layer which prevents bridging between circuits during welding and provides a permanent electrical environment and chemical corrosion resistance is coated on the circuits and the base materials which do not need welding, and the protective layer plays a role in 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, the shape is milled, the tolerance of the appearance is +/-0.05mm, and the high-reliability printed circuit board is manufactured.

(21) FQC: according to the customer acceptance standard and the inspection standard of my department, the appearance of the circuit board is inspected, if a defect exists, the circuit board is repaired in time, and the excellent quality control is guaranteed to be provided for the customer.

(22) FQA: and (5) 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 circuit board meet the requirements of customers or not again.

(23) And packaging: and hermetically packaging the circuit boards according to the packaging mode and the packaging quantity required by customers, putting a drying agent and a humidity card, and then delivering.

Example 3

The manufacturing method of the high-reliability printed circuit board shown in this embodiment is the same as that in embodiment 1 in most of the processing steps of a board with an inner layer circuit copper thickness of 40 ± 5 μm, except that the steps (2) and (3) specifically include:

(2) micro-etching: firstly, thinning the thickness of copper layers on two surfaces of two outer-layer core plates to 8-10 mu m by microetching to be used as thinning surfaces; and then, pasting a film on one surface of the two outer core boards and exposing to form a protective layer, plating the thickness of the copper layer on the other surface of the outer core board to 40 +/-5 mu m through full-board electroplating to serve as a thickened surface, and removing the film.

(3) Inner layer circuit manufacturing (negative film process): transferring an inner layer pattern, coating photosensitive films on the two outer layer core plates and the inner layer core plate by using a vertical coating machine, controlling the film thickness of the photosensitive films to be 8 mu m, completing inner layer circuit exposure by using a full-automatic exposure machine and 5-6 exposure rulers (21 exposure rulers), wherein during exposure, the film on the thinning surface in the two outer layer core plates is exposed on the whole surface to form a protective layer, and forming an inner layer circuit pattern after development; etching the inner layer, namely etching the exposed and developed thickened surfaces of the inner layer core board and the two outer layer core boards to form an inner layer circuit, wherein the line width of the inner layer circuit 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.

Example 3

The manufacturing method of the high-reliability printed circuit board shown in this embodiment sequentially includes the following processing steps:

(1) cutting: two outer core plates and one inner core plate are arranged according to the size of the jointed board of 520mm multiplied by 620mm, the thickness of the outer core plate and the thickness of the inner core plate are both 0.2mm, and the thickness of the copper layers on the two surfaces of the core plates are both 0.5oz (approximately equal to 18 mu m).

(2) Inner layer circuit manufacturing (negative film process): transferring an inner layer pattern, coating photosensitive films on the two outer layer core plates and the inner layer core plate by using a vertical coating machine, controlling the film thickness of the photosensitive films to be 8 mu m, completing inner layer circuit exposure by using a full-automatic exposure machine and 5-6 exposure rulers (21 exposure rulers), wherein during exposure, the film on one surface of the two outer layer core plates is exposed in a whole surface to form a protective layer, and developing to form an inner layer circuit pattern; etching the inner layer, etching an inner layer circuit on one surface of the exposed and developed inner layer core board and one surface of the two outer layer core boards, 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 (3) laminating: and (3) brown oxidizing at the bottom copper thickness, sequentially overlapping the outer core plate, the prepreg, the inner core plate, the prepreg and the outer core plate according to requirements, and then laminating the laminated plate by selecting proper lamination conditions according to the Tg of the plate to form a production plate, wherein the surface of the two outer core plates without the inner circuit is positioned on the outer side of the production plate.

(4) Micro-etching: the thickness of the copper layers on the two surfaces of the production plate is reduced to 8-10 mu m through microetching, namely the thickness of the copper used as the bottom copper in the surface of the outer layer of the production plate is 8-10 mu m.

(5) Drilling: according to the known drilling technique, the holes to be filled with resin are drilled in the production plate according to the design requirements.

(6) Removing glue residues: and removing the drilling dirt on the plate by adopting a plasma degumming mode.

(7) Copper deposition: and (3) depositing a layer of thin copper on the plate surface and the hole wall by using an electroless copper plating method, and testing the backlight to 10 grades, wherein the thickness of the deposited copper in the hole is 0.5 mu m.

(8) Electroplating the whole plate: and performing full-plate electroplating for 60min at a current density of 18ASF, and thickening the thicknesses of the hole copper and the plate surface copper layer to ensure that the thickness of the plate surface copper layer is additionally plated to 31-33 mu m.

(9) Plating a hole pattern: and pasting a film on the production board, and windowing at the position corresponding to the plug hole after exposure and development in sequence to form a plated hole pattern.

(10) Hole filling and electroplating: hole wall copper layers of the plug holes are thickened through hole filling electroplating;

(11) resin hole plugging: filling resin in the plug holes and curing, then removing the resin protruding out of the board surface by ceramic grinding board to make the board surface flat, and controlling the thickness of the copper layer on the board surface to be 22-25 μm after grinding the board.

(12) Drilling an outer layer: according to the known drilling technique, through holes are drilled in the production plate according to the design requirements.

(13) Removing glue residues: and removing the drilling dirt on the plate by adopting a plasma degumming mode.

(14) Copper deposition: and (3) depositing a layer of thin copper on the plate surface and the hole wall by using an electroless copper plating method, and testing the backlight to 10 grades, wherein the thickness of the deposited copper in the hole is 0.5 mu m.

(15) Electroplating the whole plate: and performing full-plate electroplating for 20min at the current density of 18ASF to increase the thickness of the hole copper and the plate surface copper layer.

(16) Manufacturing an outer layer circuit (positive process): transferring an outer layer pattern, completing outer layer line exposure by using a full-automatic exposure machine and a positive film line film with 5-7 exposure rulers (21 exposure rulers), and forming an outer layer line pattern on a production board through development; electroplating an outer layer pattern, then respectively plating copper and tin on the production plate, setting electroplating parameters according to the required finished copper thickness, wherein the copper plating is carried out for 60min at the current density of 1.8ASD, and the tin plating is carried out for 10min at the current density of 1.2ASD, and the tin thickness is 3-5 mu m; then sequentially removing the film, etching and removing tin, and etching an outer layer circuit on the production board, wherein the copper thickness of the outer layer circuit is more than or equal to 70 mu m; 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: after the solder resist ink is printed on the surface of the production board in a silk-screen manner, the solder resist ink is cured into a solder resist layer through pre-curing, exposure, development and thermocuring treatment in sequence; specifically, the TOP surface solder resist ink is added with a UL mark on the TOP surface character, so that a protective layer which prevents bridging between circuits during welding and provides a permanent electrical environment and chemical corrosion resistance is coated on the circuits and the base materials which do not need welding, and the protective layer plays a role in 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, the shape is milled, the tolerance of the appearance is +/-0.05mm, and the high-reliability printed circuit board is manufactured.

(21) FQC: according to the customer acceptance standard and the inspection standard of my department, the appearance of the circuit board is inspected, if a defect exists, the circuit board is repaired in time, and the excellent quality control is guaranteed to be provided for the customer.

(22) FQA: and (5) 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 circuit board meet the requirements of customers or not again.

(23) And packaging: and hermetically packaging the circuit boards according to the packaging mode and the packaging quantity required by customers, 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.