A PCB manufacturing method for improving plating uniformity and a PCB

Abstract

This invention discloses a PCB manufacturing method and PCB for improving electroplating uniformity, relating to the field of PCB manufacturing technology. The method includes: laminating a prepreg and a carrier copper foil on both sides of a substrate A, and pressing them together to form a substrate B; fabricating laser holes on the surface of substrate B extending to target positions on the patterned lines on the surface of substrate A; metallizing the inner walls of the laser holes and the surface of substrate B to form a conductive layer; laminating an anti-plating dry film onto the conductive layer; exposing and developing the patterned lines on the anti-plating dry film to create fine patterned windows extending to the conductive layer; sputtering a copper layer on the surface of the anti-plating dry film and the inner walls of the fine patterned windows to form a continuous conductive film; performing patterned electroplating on the surface of the conductive film, removing excess portions to form the desired fine patterned lines. This invention sputters a uniform conductive film on the surface of the anti-plating dry film, effectively improving the uniformity of current distribution during electroplating, thereby achieving a more uniform copper plating thickness.

Description

Technical Field

[0001] This invention relates to the field of PCB manufacturing technology, and in particular to a PCB manufacturing method and PCB for improving electroplating uniformity. Background Technology

[0002] PCB trace widths are typically no less than 40μm, and board dimensions are generally greater than or equal to 400mm × 400mm. Such designs usually include long-distance routing for connecting BGA pads in different locations, while the remaining areas are protected by a large copper layer covered with solder mask ink, resulting in a significant amount of open space on the board surface.

[0003] When integrating the carrier board structure onto the PCB, the pad size and spacing in the area connected to the package carrier board need to be reduced accordingly, while the non-functional areas retain their original design. This design approach leads to a significant problem: uneven circuit distribution between functional and non-functional areas results in excessively large differences in local residual copper content. In subsequent pattern plating processes, this difference will cause uneven copper thickness distribution, especially between densely packed circuit areas and open areas, where the difference in copper thickness is more pronounced. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a PCB manufacturing method and PCB with improved electroplating uniformity, thereby solving the technical problem of uneven distribution of residual copper in local areas in existing PCB manufacturing.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution: In a first aspect, the present invention provides a PCB manufacturing method for improving electroplating uniformity, comprising: A substrate A with patterned circuitry on its surface is fabricated. Prepreg and carrier copper foil are laminated on both sides of the substrate A and pressed together to form substrate B. Laser holes are formed on the surface of substrate B, extending to the target position on the patterned line on the surface of substrate A; Metallization treatment is performed on the inner wall of the laser hole and the surface of the substrate B to form a conductive layer, and an anti-electroplating dry film is laminated on the conductive layer. A fine circuit pattern window extending to the conductive layer is created by exposing and developing circuit patterns on the anti-electroplating dry film. A copper layer is sputtered onto the surface of the anti-electroplating dry film and the inner wall of the fine circuit pattern window to form a continuous conductive film; Pattern electroplating is performed on the surface of the conductive film, the conductive film on the surface of the anti-electroplating dry film is etched away, the anti-electroplating dry film is removed by a film removal process, and the conductive layer, the conductive film and the carrier copper foil that are not protected by pattern electroplating are etched to form the fine circuit pattern required.

[0006] Optionally, the substrate A with patterned circuitry on its surface includes: Patterned circuits are fabricated on the inner layer chips, and multiple fabricated inner layer chips are laminated together to form a multilayer board; patterned circuits are set on the surface of the multilayer board to form a substrate A. The inner layer chip has a conventional PCB circuit pattern, while the multilayer board surface has a fine circuit pattern.

[0007] Optionally, the thickness of the carrier copper foil can be selected according to the required level of fine circuitry, including 2μm, 3μm or 5μm.

[0008] Optionally, the metallization treatment of the inner wall of the laser hole and the surface of the substrate B to form a conductive layer includes: The inner wall of the laser hole and the surface of the substrate B are treated to remove adhesive residue, chemically plated with copper, and flash plated to form a conductive layer.

[0009] Optionally, before laminating the anti-electroplating dry film onto the conductive layer, the conductive layer is pretreated to clean the board surface.

[0010] Optionally, the sputtered copper layer is produced using a magnetron sputtering process, and the thickness of the conductive thin film is 0.1 μm to 0.5 μm.

[0011] Optionally, before performing pattern electroplating on the surface of the conductive film, the conductive film is subjected to degreasing, water washing, acid activation, and water washing treatment.

[0012] Secondly, the present invention provides a PCB, which is manufactured using the PCB manufacturing method described above.

[0013] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The present invention provides a PCB manufacturing method and PCB for improving electroplating uniformity. In the pattern electroplating process, a thin copper layer is sputtered onto the surface of the resist dry film after development, and the thin copper layer is used as the electroplating substrate, thereby forming a continuous and complete conductive film on the entire board surface. The conductive film is used to improve the uniform distribution of electroplating current lines, thereby improving the uniformity of copper plating on the board surface. Attached Figure Description

[0014] Figure 1 This is a flowchart of a PCB manufacturing method for improving electroplating uniformity provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of substrate B provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of laser holes being fabricated on substrate B according to an embodiment of the present invention; Figure 4This is a schematic diagram of the conductive layer, anti-electroplation dry film, and fine circuit pattern window fabricated on substrate B according to an embodiment of the present invention. Figure 5 This is a schematic diagram of forming a continuous conductive thin film according to an embodiment of the present invention; Figure 6 This is a schematic diagram of forming a fine circuit pattern provided in an embodiment of the present invention. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0016] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0017] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0018] Example 1

[0019] like Figure 1 As shown, this embodiment of the invention provides a PCB manufacturing method for improving electroplating uniformity, including the following steps: Step S1: Fabricate substrate A with patterned circuitry on its surface. Lay prepreg and carrier copper foil on both sides of substrate A, and then press them together to form substrate B. Figure 2 As shown.

[0020] Specifically, in this embodiment, the thickness of the carrier copper foil is selected according to the required level of fine circuitry, including 2μm, 3μm or 5μm.

[0021] The substrate A with patterned circuitry on its surface includes: Patterned circuits are fabricated on the inner layer chips, and multiple fabricated inner layer chips are laminated to form a multilayer board; patterned circuits are set on the surface of the multilayer board to form substrate A; The inner-layer chip's circuitry is at the standard PCB level, while the surface circuitry on the multilayer board is at the fine-line level. The fine-line level has a line width / spacing of 25μm or less.

[0022] Step S2: Create laser holes on the surface of substrate B that extend to the target location (generally a pad location, thereby bringing out the internal pattern lines on substrate A) on the surface of substrate A, such as... Figure 3 As shown.

[0023] Step S3: Metallize the inner wall of the laser hole and the surface of substrate B to form a conductive layer, and then laminate an anti-plating dry film (insulating) onto the conductive layer, such as... Figure 4 As shown.

[0024] Specifically, in this embodiment, the metallization treatment of the inner wall of the laser hole and the surface of substrate B to form a conductive layer includes: removing adhesive residue from the inner wall of the laser hole and the surface of substrate B, electroless copper plating, and flash plating to form the conductive layer. Before laminating the anti-plating dry film onto the conductive layer, the conductive layer is also pretreated to clean the board surface.

[0025] Step S4: Expose and develop the circuit pattern on the anti-plating dry film to create a fine circuit pattern window extending to the conductive layer, such as... Figure 4 As shown.

[0026] Step S5: Sputter a copper layer onto the surface of the anti-plating dry film and the inner wall of the fine circuit pattern window to form a continuous conductive film, such as... Figure 5 As shown.

[0027] Specifically, in this embodiment, the sputtered copper layer is sputtered using a magnetron sputtering process, and the thickness of the conductive film is 0.1 μm to 0.5 μm.

[0028] Step S6: Perform pattern electroplating on the conductive film surface, etch to remove the conductive film on the surface of the anti-plating dry film, remove the anti-plating dry film through a film removal process, and etch the conductive layer, conductive film, and carrier copper foil that are not protected by pattern electroplating to form the required fine circuit pattern, such as... Figure 6 As shown.

[0029] Specifically, in this embodiment, before pattern electroplating on the surface of the conductive film, the conductive film is subjected to degreasing, water washing, acid activation, and water washing treatment to protect the conductive film from being damaged by subsequent pattern electroplating.

[0030] Through the above process, the embodiments of the present invention sputter a continuous and uniform conductive film on the surface of the resist plating dry film after development, which effectively improves the problem of uneven current distribution caused by uneven local residual copper distribution in subsequent pattern plating processes, especially on large-area PCB boards. This significantly improves the uniformity of copper plating thickness on the board surface and achieves the goal of stably fabricating fine lines on the PCB board.

[0031] Example 2

[0032] Based on the PCB manufacturing method for improving electroplating uniformity provided in Embodiment 1, this embodiment of the invention provides a PCB manufactured using the PCB manufacturing method described above.

[0033] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A PCB manufacturing method for improving electroplating uniformity, characterized in that, include: A substrate A with patterned circuitry on its surface is fabricated. Prepreg and carrier copper foil are laminated on both sides of the substrate A and pressed together to form substrate B. Laser holes are formed on the surface of substrate B, extending to the target position on the patterned line on the surface of substrate A; Metallization treatment is performed on the inner wall of the laser hole and the surface of the substrate B to form a conductive layer, and an anti-electroplating dry film is laminated on the conductive layer. A fine circuit pattern window extending to the conductive layer is created by exposing and developing circuit patterns on the anti-electroplating dry film. A copper layer is sputtered onto the surface of the anti-electroplating dry film and the inner wall of the fine circuit pattern window to form a continuous conductive film; Pattern electroplating is performed on the surface of the conductive film, the conductive film on the surface of the anti-electroplating dry film is etched away, the anti-electroplating dry film is removed by a film removal process, and the conductive layer, the conductive film and the carrier copper foil that are not protected by pattern electroplating are etched to form the fine circuit pattern required.

2. The PCB manufacturing method for improving electroplating uniformity according to claim 1, characterized in that, The substrate A with patterned circuitry on its surface comprises: Patterned circuits are fabricated on inner-layer chips, and multiple fabricated inner-layer chips are laminated together to form a multilayer board; patterned circuits are set on the surface of the multilayer board to form substrate A. The inner layer chip has a conventional PCB circuit pattern, while the multilayer board surface has a fine circuit pattern.

3. The PCB manufacturing method for improving electroplating uniformity according to claim 1, characterized in that, The thickness of the carrier copper foil is selected according to the required level of fine circuitry, including 2μm, 3μm or 5μm.

4. The PCB manufacturing method for improving electroplating uniformity according to claim 1, characterized in that, The step of metallizing the inner wall of the laser hole and the surface of the substrate B to form a conductive layer includes: The inner wall of the laser hole and the surface of the substrate B are treated to remove adhesive residue, chemically plated with copper, and flash plated to form a conductive layer.

5. The PCB manufacturing method for improving electroplating uniformity according to claim 1, characterized in that, Before the anti-electroplation dry film is laminated onto the conductive layer, the conductive layer is pretreated to clean the board surface.

6. The PCB manufacturing method for improving electroplating uniformity according to claim 1, characterized in that, The sputtered copper layer is produced using magnetron sputtering, and the thickness of the conductive film is 0.1 μm to 0.5 μm.

7. The PCB manufacturing method for improving electroplating uniformity according to claim 1, characterized in that, Before performing pattern electroplating on the surface of the conductive film, the conductive film is subjected to degreasing, water washing, acid activation, and water washing treatment.

8. A PCB, characterized in that, The PCB is manufactured using the PCB manufacturing method as described in any one of claims 1-7.

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