Manufacturing method of printed circuit board and printed circuit board

Abstract

The invention discloses a manufacturing method of a printed circuit board and the printed circuit board. The manufacturing method comprises the following steps: filling anti-plating ink at a position needing back drilling of a first core board; the first core plate is laminated into a multi-layer plate, and the first core plate is located on the outermost layer; a through hole is formed in the multilayer board, and anti-plating ink is arranged on the peripheral side of one end of the through hole; copper deposition processing is carried out on the multilayer board, and the hole walls of the through holes and the surface of the anti-plating ink are covered with copper; covering two ends of the through hole with a dry film; performing exposure and development on the multilayer board; washing and fading the multilayer board so as to remove the anti-plating ink and the dry film; and carrying out back drilling processing on the multi-layer board from one side where the first core board is located so as to obtain a back drilling hole without a metal hole ring. Wherein the first core plate is filled with the anti-plating ink, and the back drilling hole without the metal hole ring can be manufactured only through one-time back drilling, so that the risk that hole copper is corroded is avoided while the cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of printed circuit boards, and in particular to a method for manufacturing a printed circuit board and a printed circuit board. Background Art

[0002] As an important foundation for electronic circuit interconnection, the processing and manufacturing process of PCB has many steps. The traditional pattern and back drilling manufacturing process of PCB is usually after making vias in a multilayer board, through electroless copper plating, and then using dry film to cover the holes and the film of the circuit at the position of the back drill holes. After developing and exposing, the circuit is made and then back drilling is carried out. However, because it is difficult to prevent the dry film from covering the holes properly, the patterns of the dry film covering the metallized holes are relatively large. The reason is that if the etching solution enters the holes, the hole copper will be etched, and there is a risk of open circuit in the inner layer connection. After the circuit is made, this process leaves a relatively large metal hole ring at the position of the back drill holes.

[0003] In the related art, by performing back drilling again, this undoubtedly increases the manufacturing cost of the PCB. At the same time, it is also limited by the back drilling processing ability. If the diameter of the second back drill hole is too large, it will also squeeze the wiring space on the board surface. Therefore, it is worthy of research and development to find a processing method that can avoid secondary back drilling to reduce costs and at the same time has no risk of etching solution entering the holes, so as to enable products based on PCB to meet the customer's requirements for cost and quality. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a method for manufacturing a printed circuit board. By filling anti-plating ink in the first core board, a back drill hole without a metal hole ring can be made with only one back drill, saving costs and having no risk of hole copper being etched.

[0005] The method for manufacturing a printed circuit board according to the first aspect embodiment of the present invention includes: S1: Fill anti-plating ink at the position of the first core board that needs to be back drilled; S2: Laminate the first core board into a multilayer board, and the first core board is located on the outermost layer; S3: Make vias on the multilayer board, and anti-plating ink is provided on the circumferential side of one end of the via; S4: Perform electroless copper plating on the multilayer board, and the hole wall of the via and the surface of the anti-plating ink are both covered with copper; S5: Cover both ends of the via with dry film; S6: Expose and develop the multilayer board; S7: Wash and strip the multilayer board to remove the anti-plating ink and the dry film; S8: Back drill the multilayer board from the side where the first core board is located to obtain a back drill hole without a metal hole ring.

[0006] According to the method for manufacturing a printed circuit board of an embodiment of the present invention, by filling anti-plating ink on the first core board, a back drill hole without a metal hole ring can be produced with only one back drill, saving costs and having no risk of the hole copper being etched.

[0007] According to some embodiments of the present invention, before back drilling the multilayer board from the side where the first core board is located, it further includes: thickening the copper plating on the hole wall of the through hole.

[0008] According to some embodiments of the present invention, the dry film size is smaller than the size of the anti-plating ink and larger than the size of the through hole.

[0009] According to some embodiments of the present invention, filling anti-plating ink at the position of the first core board to be back drilled includes: opening a filling groove at the position of the first core board to be back drilled, and filling anti-plating ink in the filling groove.

[0010] According to some embodiments of the present invention, the projection of the filling groove on the first core board is circular or elliptical.

[0011] According to some embodiments of the present invention, filling anti-plating ink at the position of the first core board to be back drilled includes: opening a filling hole at the position of the first core board to be back drilled, and filling anti-plating ink in the filling hole.

[0012] According to some embodiments of the present invention, the projection of the filling hole on the first core board is circular or elliptical.

[0013] According to some embodiments of the present invention, a first step is formed on the side where the first core board is located, and the first step is arranged around the circumference of the back drill hole.

[0014] The printed circuit board according to the second embodiment of the present invention is manufactured according to the method for manufacturing a printed circuit board described above.

[0015] The additional aspects and advantages of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention. Description of the Drawings

[0016] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where: Figure 1 is a flowchart of the method for manufacturing a printed circuit board according to an embodiment of the present invention; Figure 2is a schematic diagram of a first core plate having a filling hole formed therein according to an embodiment of the present invention; Figure 3 The first core board is filled with anti-plating ink according to an embodiment of the present invention Figure 4 is a schematic diagram of laminating a first core board into a multilayer board according to an embodiment of the present invention; Figure 5 is a schematic diagram of drilling a through hole in a multilayer board according to an embodiment of the present invention; Figure 6 is a schematic diagram of copper deposition on a multilayer board according to an embodiment of the present invention; Figure 7 is a schematic diagram of covering a through hole with a dry film according to an embodiment of the present invention; Figure 8 is a schematic diagram of exposure and development according to an embodiment of the present invention; Figure 9 is a schematic diagram of removing dry film and resist ink according to an embodiment of the present invention; Figure 10 is a schematic diagram of thickening copper plating of a through hole according to an embodiment of the present invention; Figure 11 is a schematic diagram of back drilling according to an embodiment of the present invention.

[0017] Reference numerals: 11. First core board; 111. Insulation layer; 112. Copper layer; 113. Filling hole; 12. Anti-plating ink; 13. Multilayer board; 14. Through hole; 15. Dry film; 16. Back drilling; 17. First step; 18. Second step. DETAILED DESCRIPTION

[0018] Embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. Embodiments of the present invention are described in detail below.

[0019] Reference below Figures 1-11 A method for manufacturing a printed circuit board according to an embodiment of the present invention is described, and a printed circuit board manufactured by the method for manufacturing the printed circuit board is also proposed.

[0020] The method for manufacturing a printed circuit board of the present invention comprises the following steps: S1: Fill the anti-plating ink 12 at the position of the first core board 11 that needs back drilling.

[0021] The first core board 11 includes: an insulating layer 111 and copper layers 112 on both sides, and the upper and lower surfaces of the insulating layer 111 are covered with the copper layer 112, that is, the upper and lower surfaces of the insulating layer 111 are covered with copper foil. After determining which positions of the first core board 11 need to be back-drilled, grooves or holes are opened at the positions of the first core board 11 that need to be back-drilled, and the grooves or holes are filled with anti-plating ink 12.

[0022] The anti - plating ink 12 has good adhesion and corrosion resistance, and can maintain stable performance under various electroplating conditions. The anti - plating ink 12 can form stable chemical bonding or physical barriers with the metal surface during electroplating, thereby preventing the electroplating solution from eroding the anti - plating ink 12.

[0023] S2: Laminate the first core board 11 into a multi - layer board 13, and the first core board 11 is located on the outermost layer.

[0024] The first core board 11 and other core boards are laminated into a multi - layer board 13. The multi - layer board 13 can be hierarchically laid out, and the signal traces of different functional modules are laid out on different board layers. This can improve circuit performance and reduce signal interference. Through the lamination method, signal lines, power lines, and ground lines can be arranged between different layers to form a good signal loop, and the rigidity and durability of the printed circuit board can be improved.

[0025] The first core board 11 is located on the outermost layer on one side of the multi - layer board 13, that is, the anti - plating ink 12 is located on the outermost layer of the multi - layer board 13.

[0026] S3: Make vias 14 on the multi - layer board 13, and anti - plating ink 12 is provided on the periphery of one end of the via 14.

[0027] That is to say, drill vias 14 on the multi - layer board 13. The first core board 11 is located on the side of the back - drilled via 14, and the anti - plating ink 12 corresponds to the via 14. The size of the anti - plating ink 12 is larger than that of the via 14. After making the metallized via 14, a part of the anti - plating ink 12 opposite to the via 14 is removed, and the remaining anti - plating ink 12 is arranged around the periphery of one end of the via 14.

[0028] S4: Perform copper - deposition processing on the multi - layer board 13, and the hole walls of the vias 14 and the surfaces of the anti - plating ink 12 are covered with copper.

[0029] In step S4, perform copper - deposition processing on the multi - layer board 13, electroplate the inner walls of the vias 14, and electroplate the surfaces of the anti - plating ink 12, so that the hole walls of the vias 14 and the surfaces of the anti - plating ink 12 are covered with copper foil.

[0030] The holes formed by mechanical drilling or laser drilling have hole walls mainly composed of non - conductive materials. If electroplating is directly carried out, the current cannot pass through these hole walls, resulting in the inability to perform copper electroplating. Therefore, it is necessary to first form electroplated copper on the hole walls of the vias 14 through the copper - deposition process to achieve the adhesion of electroplated copper.

[0031] S5: Cover both ends of the via 14 with a dry film 15.

[0032] After the copper deposition process of the multilayer board 13, the upper and lower end faces of the through hole 14 are covered with a dry film 15. The dry film 15 covers both ends of the through hole 14. The dry film 15 can shield the areas that do not need to be exposed and developed, protect the copper plated on the inner wall of the through hole 14, control the scope of exposure and development, and prevent the etching solution from entering the through hole 14, which may cause the copper in the hole to be etched and pose a risk of open circuit in the inner layer connection.

[0033] S6: Perform exposure and development on the multilayer board 13.

[0034] After the dry film 15 covers both ends of the through hole 14, exposure and development are performed on the two outermost surfaces of the multilayer board 13 to produce the outer layer pattern. At this time, both ends of the through hole 14 are covered with the dry film 15. During the etching process after exposure and development, the etching solution will not enter the through hole 14 to corrode the copper on the inner wall of the through hole 14, avoiding open circuit in the inner layer connection.

[0035] S7: Wash and strip the multilayer board 13 to strip off the anti-plating ink 12 and the dry film 15.

[0036] Among them, the method of stripping the dry film 15 and the anti-plating ink 12 can be chemical stripping or physical stripping.

[0037] First, strip the dry film 15, and the dry film 15 can be stripped in an acidic environment; then strip the anti-plating ink 12, and the anti-plating ink 12 can be stripped in an alkaline environment. After the anti-plating ink 12 wound around the periphery of the end of the through hole 14 that needs to be back-drilled is stripped, a second step 18 is formed between the first core board 11 and the remaining boards. The second step 18 is the position where the multilayer board 13 needs to be back-drilled, and there is no copper foil on the second step 18.

[0038] S8: Perform back-drilling on the multilayer board 13 from the side where the first core board 11 is located to obtain a back-drilled hole 16 without a metal hole ring.

[0039] Perform back-drilling on the multilayer board 13 from the side where the first core board 11 is located, and move the position of the drill bit so that the drill bit is coaxial with the through hole 14. The drill bit is larger than the size of the through hole 14 and smaller than the size of the first step 17, then the size of the back-drilled hole 16 is smaller than the first step 17.

[0040] In the related art, secondary back-drilling increases the manufacturing cost of the circuit board. If the diameter of the second back-drilled hole 16 is too large, it will also squeeze the wiring space on the board surface. Therefore, in the present invention, by filling the anti-plating ink 12 in the first core board 11, a back-drilled hole 16 without a metal hole ring can be produced with only one back-drilling, saving costs and having no risk of the copper in the hole being etched.

[0041] In an embodiment of the present invention, before back drilling the multilayer board 13 from the side where the first core board 11 is located, it further includes: thickening the copper plating on the hole wall of the through hole 14. Specifically, before performing step S8, it is necessary to first thicken the copper plating on the hole wall of the through hole 14. After copper deposition in step S4, a thin copper layer adheres to the hole wall of the through hole 14, but it is likely to cause partial disconnection of the inner layer circuit of the multilayer board 13. After thickening the copper plating on the hole wall, the reliability of the inner layer circuit interconnection can be improved, the interlayer interconnection requirements of the multilayer board 13 can be met, and the flexibility of the interlayer interconnection density is greatly increased.

[0042] In some embodiments, the size of the dry film 15 is smaller than the size of the anti - plating ink 12 and larger than the size of the through hole 14. Specifically, in order to prevent the etching solution from entering the through hole 14 and corroding the copper on the hole wall of the through hole 14, resulting in an open circuit of the inner layer connection, the size of the dry film 15 is larger than the size of the through hole 14; if the size of the dry film 15 is larger than the size of the anti - plating ink 12, the size of the dry film 15 is too large, and a metal hole ring will be left on the periphery of the back - drilled hole 16.

[0043] In some embodiments, filling the anti - plating ink 12 at the position of the first core board 11 that needs to be back - drilled includes: opening a filling groove at the position of the first core board 11 that needs to be back - drilled and filling the anti - plating ink 12 in the filling groove. Specifically, a filling groove can be opened at the position corresponding to the back - drilling of the first core board 11. The depth of the filling groove is greater than the thickness of the copper foil on the surface of the first core board 11 and less than the thickness of the first core board 11. Fill the anti - plating ink 12 in the filling groove and cure the anti - plating ink 12. After curing, the anti - plating ink 12 is substantially flush with the upper surface of the first core board 11, which is convenient for copper deposition processing of the multilayer board 13 in step S4.

[0044] If the thickness of the insulating layer 111 of the first core board 11 is A, the thickness of the copper layers on both surfaces is B, and the thickness of the filling groove is H, then H satisfies the relationship: B < H < A + B or A + B < H < A + 2B. This ensures that there is no metal hole ring on the periphery of the back - drilled hole 16 after removing the anti - plating ink 12.

[0045] The filling groove can be a regular shape or an irregular shape. For the convenience of process production, the filling groove can be a regular shape, such as a rectangle, a circle, or an ellipse, etc.

[0046] In some embodiments, the projection of the filling groove on the first core board 11 is a circle or an ellipse. Specifically, the filling groove is larger than the size of the through hole 14 so that the size of the anti - plating ink 12 is larger than the size of the through hole 14. The projection of the filling groove on the first core board 11 can be a circle, and the diameter of the circle is larger than the diameter of the through hole 14. At this time, the amount of anti - plating ink 12 used in the process of manufacturing the printed circuit board can be minimized, reducing the manufacturing cost.

[0047] In addition, the projection of the filling groove on the first core board 11 can be oval. Since the size of the dry film 15 is larger than that of the through hole 14 and the anti-plating ink 12 is larger than the dry film 15, the minimum diameter of the oval needs to be larger than the diameter of the through hole 14 to ensure that the etching solution does not enter the through hole 14 during the exposure and development process to etch the copper, thus avoiding the inner-layer connection open circuit of the multilayer board 13.

[0048] In some embodiments, filling the anti-plating ink 12 at the back-drilling position of the first core board 11 includes: opening a filling hole 113 at the back-drilling position of the first core board 11 and filling the anti-plating ink 12 into the filling hole 113. Specifically, the filling hole 113 can be first opened at the back-drilling position of the first core board 11, the anti-plating ink 12 is filled into the filling hole 113, and the anti-plating ink 12 is cured. The cured anti-plating ink 12 is substantially flush with the upper surface of the first core board 11, which is convenient for the copper deposition process of the multilayer board 13 in step S4.

[0049] Among them, the filling hole 113 can be a regular shape or an irregular shape. For the convenience of process manufacturing, the filling hole 113 can be a regular shape, such as a rectangle, a circle or an oval, etc.

[0050] In some embodiments, the projection of the filling hole 113 on the first core board 11 is circular. The filling hole 113 is larger than the size of the through hole 14 so that the size of the anti-plating ink 12 is larger than the through hole 14. The projection of the filling hole 113 on the first core board 11 can be a circle, and the diameter of the circle is larger than the diameter of the through hole 14. At this time, the amount of the anti-plating ink 12 used in the process of manufacturing the printed circuit board can be reduced, and the manufacturing cost can be lowered.

[0051] Or, the projection of the filling hole 113 on the first core board 11 is oval. Since the size of the dry film 15 is larger than the through hole 14 and the anti-plating ink 12 is larger than the dry film 15, the minimum diameter of the ellipse needs to be larger than the diameter of the through hole 14 to ensure that the etching solution does not enter the through hole 14 during the exposure and development process to etch the copper, thus avoiding the inner-layer connection open circuit of the multilayer board 13.

[0052] In some embodiments, a first step 17 is formed on one side where the first core board 11 is located, and the first step 17 is arranged around the circumference of the back-drilled hole 16. Specifically, after the multilayer board 13 is back-drilled, the first step 17 is formed at the original position of the second step 18. The surface of the first step 17 is non-metallic to obtain a back-drilled hole 16 without a metal hole ring. Thus, by filling the anti-plating ink 12 in the first core board 11, a back-drilled hole 16 without a hole ring can be obtained by one-time back-drilling, with low manufacturing cost and high reliability of the internal interconnection of the multilayer board 13.

[0053] The printed circuit board according to the second embodiment of the present invention is manufactured according to the manufacturing method of the above-mentioned printed circuit board.

[0054] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention.

[0055] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example.

[0056] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for manufacturing a printed circuit board, characterized in that, Including: S1: Fill anti - plating ink (12) at the position of the first core board (11) that needs to be back - drilled; S2: Laminate the first core board (11) into a multi - layer board (13), and the first core board (11) is located on the outermost layer; S3: Make a via hole (14) on the multi - layer board (13), and anti - plating ink (12) is arranged on the periphery of one end of the via hole (14); S4: Conduct copper deposition processing on the multi - layer board (13), and copper covers the hole wall of the via hole (14) and the surface of the anti - plating ink (12); S5: Cover both ends of the via hole (14) with a dry film (15); S6: Conduct exposure and development on the multi - layer board (13); S7: Conduct washing and stripping on the multi - layer board (13) to strip the anti - plating ink (12) and the dry film (15); S8: Conduct back - drilling processing on the multi - layer board (13) from the side where the first core board (11) is located to obtain a back - drilled hole (16) without a metal hole ring.

2. The manufacturing method of the printed circuit board according to claim 1, characterized in that, Before conducting the back - drilling processing on the multi - layer board (13) from the side where the first core board (11) is located, it further includes: Thicken the copper plating on the hole wall of the via hole (14).

3. The manufacturing method of the printed circuit board according to claim 1, characterized in that The size of the dry film (15) is smaller than the size of the anti - plating ink (12) and larger than the size of the via hole (14).

4. The manufacturing method of the printed circuit board according to claim 1, wherein The step of filling anti - plating ink (12) at the position of the first core board (11) that needs to be back - drilled includes: Open a filling groove at the position of the first core board (11) that needs to be back - drilled, and fill anti - plating ink (12) in the filling groove.

5. The manufacturing method of the printed circuit board according to claim 4, characterized in that, The projection of the filling groove on the first core board (11) is circular or elliptical.

6. The manufacturing method of the printed circuit board according to claim 1, characterized in that, The step of filling anti - plating ink (12) at the position of the first core board (11) that needs to be back - drilled includes: Open a filling hole (113) at the position of the first core board (11) that needs to be back - drilled, and fill anti - plating ink (12) in the filling hole (113).

7. The manufacturing method of the printed circuit board according to claim 6, characterized in that The projection of the filling hole (113) on the first core board (11) is circular or elliptical.

8. The manufacturing method of the printed circuit board according to claim 1, characterized in that, A first step (17) is formed on the side where the first core board (11) is located, and the first step (17) is arranged around the periphery of the back - drilled hole (16).

9. A printed circuit board, characterized in that, Manufactured by the manufacturing method of the printed circuit board according to any one of claims 1 - 8.

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