Manufacturing method of inner layer of printed circuit board and printed circuit board

Abstract

The invention discloses a manufacturing method of an inner layer of a printed circuit board and the printed circuit board, and the manufacturing method of the inner layer of the printed circuit board comprises the steps: pasting first dry films on the two sides of a core board, and forming exposure holes in the first dry films; etching the core plate, and removing the remaining first dry film; pasting a second dry film on the core plate, exposing the second dry film, and forming an electroplating hole in the second dry film; electroplating the electroplating hole to form a first metal layer; and removing the residual second dry film. According to the method, the dry films are pasted for the second time, and the second metal layer is etched after the first dry film is pasted, so that the minimum distance of the first dry film can reach a limit value, the operation is carried out according to the limited distance during electroplating, the accuracy is higher, and the requirements of small distance and larger copper thickness of the inner layer of the printed circuit board are met.

Description

Technical Field

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

[0002] Coil motor coil products require increasingly greater thrust, and accordingly, the wire resistance must be increasingly lower. According to Ohm's law, when the wire length remains unchanged, the wire resistance can only be reduced by increasing the cross-sectional area of ​​the wire, that is, increasing the copper thickness and reducing the conductor spacing.

[0003] In related technologies, MSAP or SAP additive processes are commonly used, but rapid etching will corrode the surface and sides of the circuit, and the circuit spacing is increased by at least 3-8μm. The spacing achieved at this time is larger than the resolution capability of the dry film. This process cannot fully realize the minimum spacing advantage of the dry film capability, and cannot meet the requirements of smaller spacing and thicker copper thickness. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for manufacturing the inner layer of a printed circuit board, wherein the second metal layer is etched after the first dry film is applied, so that the minimum spacing of the first dry film can reach the limit value, thereby achieving the requirements of small spacing and thick copper thickness of the inner layer of the printed circuit board.

[0005] The invention also provides a printed circuit board.

[0006] According to the first aspect of the present invention, the method for manufacturing the inner layer of a printed circuit board includes: attaching a first dry film to both sides of a core board and opening exposure holes on the first dry film; etching the core board and removing the remaining first dry film; attaching a second dry film to the core board and exposing the second dry film to form electroplating holes on the second dry film; electroplating the electroplating holes to form a first metal layer; and removing the remaining second dry film.

[0007] According to the method for manufacturing the inner layer of a printed circuit board in an embodiment of the present invention, a dry film is applied twice, and the second metal layer is etched after the first dry film is applied, so that the minimum spacing of the first dry film can reach a limit value. During electroplating, the operation is carried out according to the limited spacing, which has higher accuracy and meets the requirements of small spacing and thicker copper thickness of the inner layer of the printed circuit board.

[0008] According to some embodiments of the present invention, the second dry film is an anti-plating dry film.

[0009] According to some embodiments of the present invention, the step of forming electroplated holes on the second dry film further comprises: performing black shadow or copper deposition treatment on the electroplated holes.

[0010] According to some embodiments of the present invention, the core board includes: a first insulating layer and two second metal layers, and the two second metal layers are arranged on both sides of the first insulating layer; the step of etching the core board also includes: etching the two second metal layers at the exposure hole.

[0011] According to some embodiments of the present invention, the thickness of the core plate is h, and h satisfies the relationship: h≤5 μm.

[0012] The printed circuit board according to the second embodiment of the present invention comprises: an inner layer, which is made by the manufacturing method of the inner layer of the printed circuit board; and two outer layers, which are respectively arranged on both sides of the inner layer.

[0013] According to some embodiments of the present invention, the inner layer includes: a first insulating layer, two first metal layers and two second metal layers, wherein one of the first metal layers is sandwiched between one side of the first insulating layer and one of the second metal layers, and another first metal layer is sandwiched between the other side of the first insulating layer and another second metal layer, and a plurality of first blind holes are formed in the two first metal layers and the two second metal layers.

[0014] According to some embodiments of the present invention, the outer layer includes: a second insulating layer, a third metal layer and a fourth metal layer, the third metal layer is arranged between the second insulating layer and the fourth metal layer, the fourth metal layer is arranged on the side of the third metal layer away from the second insulating layer, and a plurality of second blind holes are formed in the third metal layer and the fourth metal layer.

[0015] According to some embodiments of the present invention, a plurality of filling parts are provided on the second insulating layer, and the plurality of filling parts are respectively matched in the plurality of first blind holes.

[0016] The beneficial effects of the embodiments of the present invention are as follows: by applying the dry film twice and etching the second metal layer after applying the first dry film, the minimum spacing of the first dry film can reach the limit value, and the electroplating is performed according to the limited spacing, with higher accuracy, so that the inner layer of the printed circuit board can meet the requirements of small spacing and thicker copper thickness.

[0017] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1is a schematic structural diagram of a printed circuit board according to an embodiment of the present invention; Figure 2 This is step 1 of the method for manufacturing the inner layer of a printed circuit board according to an embodiment of the present invention; Figure 3 This is step 2 of the method for manufacturing the inner layer of the printed circuit board according to the embodiment of the present invention; Figure 4 This is step three of the method for manufacturing the inner layer of a printed circuit board according to an embodiment of the present invention; Figure 5 This is step 4 of the method for manufacturing the inner layer of the printed circuit board according to the embodiment of the present invention; Figure 6 This is step five of the method for manufacturing the inner layer of the printed circuit board according to the embodiment of the present invention; Figure 7 This is step six of the method for manufacturing the inner layer of a printed circuit board according to an embodiment of the present invention; Figure 8 This is step seven of the method for manufacturing the inner layer of the printed circuit board according to the embodiment of the present invention.

[0019] Reference numerals: 100. Printed circuit board; 10. Inner layer; 11. Core board; 12. First insulation layer; 13. Second metal layer; 14. First dry film; 15. Exposure hole; 16. Second dry film; 17. Electroplating hole; 18. First metal layer; 20. Outer layer; 21. Second insulating layer; 22. Third metal layer; 23. Fourth metal layer; 24. Filling part. DETAILED DESCRIPTION

[0020] 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.

[0021] Reference below Figure 1-Figure 8 A method for manufacturing an inner layer of a printed circuit board according to an embodiment of the present invention is described. The present invention also provides a printed circuit board 100 .

[0022] Reference Figure 1-Figure 8 As shown, the method for manufacturing the inner layer 10 of the printed circuit board 100 of the embodiment of the present invention includes: attaching a first dry film 14 on both sides of a core board 11, and opening exposure holes 15 on the first dry film 14, etching the core board 11, and removing the remaining first dry film 14, attaching a second dry film 16 on the core board 11, and exposing the second dry film 16, forming electroplating holes 17 on the second dry film 16, electroplating the electroplating holes 17 to form a first metal layer 18, and removing the remaining second dry film 16.

[0023] Therefore, by applying the dry film twice and etching the second metal layer 13 after applying the first dry film 14, the minimum spacing of the first dry film 14 can reach the limit value, and the electroplating is performed according to the specified spacing, which has higher accuracy and meets the requirements of small spacing and thicker copper thickness for the inner layer 10 of the printed circuit board 100.

[0024] The second dry film 16 may be an anti-electroplating dry film, and the step of forming the electroplating hole 17 on the second dry film 16 further includes: performing black shadow or copper deposition treatment on the electroplating hole 17 .

[0025] And, the core board 11 includes: a first insulating layer 12 and two second metal layers 13, the two second metal layers 13 are arranged on both sides of the first insulating layer 12, the first insulating layer 12 is a substrate, and the second metal layer 13 is a copper layer. The step of etching the core board 11 also includes: etching the two second metal layers 13 at the exposure hole 15. The thickness of the core board 11 is h, and h satisfies the relationship: h≤5μm.

[0026] In summary, the circuit board manufacturing method of this embodiment is as follows: Figures 2 to 8 The following steps are shown: Reference Figure 2 As shown, step 1, a first dry film 14 is attached to both sides of the second metal layer 13 of the core board 11, the first dry film 14 is a common dry film, the thickness of the core board 11 is not more than 5μm, that is, the core board 11 is an ultra-thin copper core board 11, and its copper foil thickness can be divided into 2μm, 3μm and 5μm. There is a layer of protective copper foil outside the ultra-thin copper, generally 15μm or 18μm is used, and the protective copper foil can effectively reduce the scratches of the ultra-thin copper.

[0027] Reference Figure 3 As shown, step 2, the first dry film 14 is exposed to form an exposure hole 15. Exposure refers to the use of ultraviolet (UV) energy to make the photosensitive material in the dry film or printing ink undergo a photochemical reaction to achieve the effect of selective local bridging and hardening to complete the purpose of image transfer. This exposure is to process the two layers of the second metal layer 13 of the core board 11, reserve the positioning marks required for the secondary exposure, and improve the processing accuracy of the secondary exposure.

[0028] Reference Figure 4 As shown, in step 3, etching the second metal layer 13 can form a specific circuit pattern on the second metal layer 13 to provide a conductive path for electronic components, and after etching is completed, the remaining first dry film 14 is removed. By etching the second metal layer 13, part of the second metal layer 13 is removed, and the circuit spacing is initially etched out.

[0029] Reference Figure 5As shown, in step 4, a second dry film 16 is attached to the two second metal layers 13 of the core board 11, and the second dry film 16 is exposed to expose the circuit made by the first exposure, so as to facilitate the subsequent electroplating. Among them, the second dry film 16 is an anti-electroplating dry film, which is a composite material composed of a high-strength fabric substrate and a polymer coating, and is used to accompany the electroplating process to make a thin film in a membrane structure engineering. The minimum spacing limit of the dry film's resolution can be broken by the secondary exposure, ensuring that the circuit spacing will not increase during the manufacturing process.

[0030] Reference Figure 6 As shown, in step 5, the exposed second dry film 16 is removed to form a plating hole 17 on the second dry film 16 to facilitate subsequent electroplating.

[0031] Reference Figure 7 As shown, step 6, the core board 11 is subjected to black shadow or copper deposition pre-treatment to ensure that the surface of the first insulating layer 12 of the core board 11 and the hole wall are clean and activated, to ensure the quality and reliability of the electroplating process, and then electroplating is performed after treatment. Among them, the electroplating method is graphic electroplating, and the thickness of the second metal layer 13 is increased by electroplating to meet the design requirements. The copper thickness is controlled by electroplating to meet the demand for increasing the copper thickness.

[0032] Reference Figure 8 As shown, in step 7, the second dry film 16 is removed, and the electroplated leads are removed to avoid copper exposure during the external shape processing and the reduction of line resistance, thereby completing the manufacture of the inner layer 10 of the printed circuit board 100.

[0033] The printed circuit board 100 according to the second embodiment of the present invention comprises: an inner layer 10 and two outer layers 20. The inner layer 10 is made by the manufacturing method of the inner layer 10 of the printed circuit board 100, and the two outer layers 20 are arranged on both sides of the inner layer 10 respectively.

[0034] Reference Figure 1 As shown, the inner layer 10 includes: a first insulating layer 12, two first metal layers 18 and two second metal layers 13, wherein one first metal layer 18 is sandwiched between one side of the first insulating layer 12 and one of the second metal layers 13, and another first metal layer 18 is sandwiched between the other side of the first insulating layer 12 and another second metal layer 13, and a plurality of first blind holes are formed on the two first metal layers 18 and the two second metal layers 13. That is, thickened copper layers are provided on both sides of the core board 11, and the core board 11 is sandwiched between the two first metal layers 18.

[0035] The outer layer 20 includes: a second insulating layer 21, a third metal layer 22 and a fourth metal layer 23, the third metal layer 22 is arranged between the second insulating layer 21 and the inner layer 10, the fourth metal layer 23 is arranged on the side of the third metal layer 22 away from the second insulating layer 21, and a plurality of second blind holes are formed on the third metal layer 22 and the fourth metal layer 23. Among them, the third metal layer 22 and the fourth metal layer 23 are both copper layers, the third metal layer 22 is the copper foil of the core board 11, and the fourth metal layer 23 is a thickened copper layer, that is, the printed circuit board 100 is supported by the lamination of the multi-layer core board 11, and the process of thickening the copper layer is the same.

[0036] A plurality of filling parts 24 are provided on the second insulating layer 21, and the plurality of filling parts 24 are respectively matched in the plurality of first blind holes. The second insulating layer 21 is a semi-cured sheet, which is mainly composed of resin and reinforcing materials. The reinforcing materials are divided into several types such as glass fiber cloth, paper base, and composite materials. The semi-cured sheets (adhesive sheets) used to make the multi-layer printed circuit board 100 mostly use glass fiber cloth as the reinforcing material. The semi-cured sheets are filled in the core board 11 to play an insulating role.

[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0038] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0039] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for manufacturing an inner layer of a printed circuit board, characterized in that: include: A first dry film (14) is attached to both sides of the core board (11), and an exposure hole (15) is formed on the first dry film (14); Etching the core board (11) and removing the remaining first dry film (14); A second dry film (16) is attached to the core board (11), and the second dry film (16) is exposed to light, so that electroplating holes (17) are formed on the second dry film (16); Electroplating the electroplated hole (17) to form a first metal layer (18); The remaining second dry film (16) is removed.

2. The method for manufacturing the inner layer of a printed circuit board according to claim 1, characterized in that: The second dry film (16) is an anti-electroplating dry film.

3. The method for manufacturing the inner layer of a printed circuit board according to claim 1, characterized in that: The step of forming the electroplating hole (17) on the second dry film (16) further comprises: The electroplated hole (17) is subjected to a black shadow or copper deposition process.

4. The method for manufacturing the inner layer of a printed circuit board according to claim 1, characterized in that: The core board (11) comprises: a first insulating layer (12) and two second metal layers (13), wherein the two second metal layers (13) are arranged on both sides of the first insulating layer (12); The step of etching the core board (11) further comprises: etching the two layers of the second metal layer (13) at the exposure hole (15).

5. The method for manufacturing the inner layer of a printed circuit board according to claim 1, characterized in that: The thickness of the core plate (11) is h, and h satisfies the relationship: h≤5 μm.

6. A printed circuit board, characterized in that: include: An inner layer (10), the inner layer (10) being made by the method for making an inner layer of a printed circuit board according to any one of claims 1 to 5; Two outer layers (20), the two outer layers (20) being respectively arranged on both sides of the inner layer (10).

7. The printed circuit board according to claim 6, characterized in that: The inner layer (10) comprises: a first insulating layer (12), two first metal layers (18) and two second metal layers (13), wherein one of the first metal layers (18) is sandwiched between one side of the first insulating layer (12) and one of the second metal layers (13), and another of the first metal layers (18) is sandwiched between the other side of the first insulating layer (12) and another of the second metal layers (13), and a plurality of first blind holes are formed on the two first metal layers (18) and the two second metal layers (13).

8. The printed circuit board according to claim 7, characterized in that: The outer layer (20) comprises: a second insulating layer (21), a third metal layer (22) and a fourth metal layer (23); the third metal layer (22) is arranged between the second insulating layer (21) and the fourth metal layer (23); the fourth metal layer (23) is arranged on a side of the third metal layer (22) away from the second insulating layer (21); and a plurality of second blind holes are formed on the third metal layer (22) and the fourth metal layer (23).

9. The printed circuit board according to claim 8, characterized in that: A plurality of filling portions (24) are provided on the second insulating layer (21), and the plurality of filling portions (24) are respectively fitted in the plurality of first blind holes.

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