Printed circuit board surface thick metal layer processing method and printed circuit board

Abstract

The embodiment of the invention provides a method for processing a thick metal layer on the surface of a printed circuit board, and the method comprises the steps: coating the surface of the printed circuit board with solder resist ink, and forming a solder resist ink layer; removing the solder resist ink in a target area on the solder resist ink layer through optical exposure and development treatment, and then curing the solder resist ink layer; the surface of the solder resist ink layer is coated with a flowing protection object, flowing filling treatment is conducted on the surface of the solder resist ink layer, a flat temporary protection layer is formed, and then the flowing protection object in a target area on the temporary protection layer is removed; pasting a dry film on the surface of the temporary protection layer to form a dry film layer; removing the dry film in the target area on the dry film layer through optical exposure and development treatment; manufacturing a metal layer in the target area so as to form the metal layer in the target area on the surface of the printed circuit board; and removing the dry film and the temporary protection layer. The method solves the problems that in the prior art, machining efficiency is low, machining precision is poor, and foreign matter anti-sticking is likely to be caused.

Description

Technical Field

[0001] The present application relates to the technical field of printed circuit board manufacturing, and in particular to a method for processing a thick metal layer on the surface of a printed circuit board and a printed circuit board. Background Art

[0002] With the iterative development and application promotion of electronic information technology, as one of the core components, printed circuit boards have been gradually popularized and applied in the field of electronic terminal products. From the perspective of product design, a printed circuit board is a highly customized and personalized product. Different products have different design requirements for wiring density, wiring rules, conduction structure design, and surface treatment per unit area. Therefore, generally different types of printed circuit boards require different product technical solutions to meet the requirements of their terminal functions and performance. Currently, to meet the personalized design of terminal products, more and more printed circuit board products are designed with functional structures of local thick copper and local thick gold on the outer layer to achieve the functions of rapid heat dissipation and plugging of printed circuit product modules. Compared with the conventional copper layer surface treatment process, the thickness of the substrate at the bottom layer of the surface ink is 0.12 mm or more higher. Affected by the height difference between the two thicknesses, multiple processes need to be added to assist production during actual product manufacturing, and its manufacturing requirements pose new challenges to the traditional printed circuit board processing technology.

[0003] For printed circuit board products with a locally thick metal layer on the surface, the traditional manufacturing method is to attach a relatively thick blue tape to the entire board surface, utilize the ductility and sealing performance of the blue tape to attach and fill the structures with different thickness differences on the board surface, then cut and open the window of the surface blue tape according to the surface CAM data, and finally perform thick plating on the metal surface at the window position.

[0004] However, the above method also has the following disadvantages: 1. The processing efficiency is low. It is necessary to cut each metal structure position, and then remove the blue tape by manual tearing. After the board surface is metallized, the blue tape is manually removed from the entire board. For products with ordinary structures, the window opening time for one board usually takes 20 minutes; 2. The processing accuracy is poor. Due to the influence of the thickness tolerance of the cutting tool itself, the alignment and accuracy ability during the processing process are low, and it is easy to have abnormal window opening deviation; 3. It is easy to cause quality problems of foreign matter adhesion. Due to the precise design of some surface metal structures, the window opening position is small, resulting in abnormal adhesion of blue tape fine chips during the tearing process, and residual glue and foreign matter adhesion occur during the actual production process, resulting in production quality problems. Therefore, the above method is not applicable to products with batch production, precise surface metallization structure design, and a large number of designed quantities. Summary of the Invention

[0005] An embodiment of the present application provides a method for processing a thick metal layer on the surface of a printed circuit board and a printed circuit board, which are used to solve the technical problems of low processing efficiency, poor processing accuracy, and easy foreign object adhesion in the existing method for processing a local thick metal coating on a printed circuit board.

[0006] In a first aspect, the present application provides a method for processing a thick metal layer on the surface of a printed circuit board, and the method includes:

[0007] Coat a solder mask ink on the surface of the printed circuit board to form a solder mask ink layer;

[0008] Through optical exposure and development processing, remove the solder mask ink in the target area on the solder mask ink layer, and then cure the solder mask ink layer;

[0009] Coat a fluid protective material on the surface of the solder mask ink layer, perform a flow leveling process on the surface of the solder mask ink layer to form a flat temporary protective layer, and then remove the fluid protective material in the target area on the temporary protective layer;

[0010] Lay a dry film on the surface of the temporary protective layer to form a dry film layer;

[0011] Through optical exposure and development processing, remove the dry film in the target area on the dry film layer;

[0012] Fabricate a metal layer in the target area to form a metal layer in the target area on the surface of the printed circuit board;

[0013] Remove the dry film and the temporary protective layer.

[0014] In a possible implementation manner, the coating of the fluid protective material on the surface of the solder mask ink layer and the performance of the flow leveling process on the surface of the solder mask ink layer to form a temporary protective layer include:

[0015] Coat an anti-electroplating ink on the surface of the solder mask ink layer and perform a flow leveling process on the surface of the solder mask ink layer;

[0016] Perform a pre-baking process on the anti-electroplating ink to make the anti-electroplating ink semi-cure to form the temporary protective layer.

[0017] In a possible implementation manner, the removal of the fluid protective material in the target area on the temporary protective layer includes:

[0018] Through optical exposure and development processing, remove the anti-electroplating ink in the target area on the temporary protective layer.

[0019] In a possible implementation manner, the laying of the dry film on the surface of the temporary protective layer includes:

[0020] Clean the surface of the anti - electroplating ink layer to be laminated with a micro - etching solution;

[0021] Laminated a dry film on the surface of the to - be - laminated film.

[0022] In a possible implementation manner, the removing of the temporary protective layer includes:

[0023] Dissolve the anti - electroplating ink with an alkaline solution to remove the temporary protective layer.

[0024] In a possible implementation manner, the coating of a flowable protective material on the surface of the solder mask ink layer and performing a flow - leveling treatment on the surface of the solder mask ink layer to form a temporary protective layer includes:

[0025] Coat a photosensitive resin on the surface of the solder mask ink layer and perform a flow - leveling treatment on the surface of the solder mask ink layer;

[0026] Perform a pre - baking treatment on the photosensitive resin so that the photosensitive resin is semi - cured to form the temporary protective layer.

[0027] In a possible implementation manner, the removing of the flowable protective material in the target area on the temporary protective layer includes:

[0028] Remove the photosensitive resin in the target area on the temporary protective layer through an optical exposure and development treatment.

[0029] In a possible implementation manner, the removing of the temporary protective layer includes:

[0030] Dissolve the photosensitive resin with an organic solvent to remove the temporary protective layer.

[0031] In a possible implementation manner, the making of a metal layer in the target area includes:

[0032] Perform a metal plating treatment in the target area.

[0033] In a second aspect, the present application provides a printed circuit board, which is processed by the method described in the first aspect.

[0034] The method for processing a thick metal layer on the surface of a printed circuit board and the printed circuit board provided by the embodiments of the present application have the following technical effects:

[0035] Due to the problems of low efficiency, poor precision, and foreign object residues in traditional methods that rely on mechanical cutting with blue tape, this solution stacks a fluid protective layer on the solder mask ink layer, uses the openings in the solder mask ink and subsequent curing to provide reference positioning, and fills the surface height differences with the fluidity of the fluid protective layer, thereby ensuring a flat board surface and improving the precision of subsequent optical openings on the dry film. At the same time, combined with subsequent dry film attachment and optical exposure and development, three high-precision openings can be achieved, thus improving the opening precision and avoiding the offset problem of mechanical cutting. In addition, since the double protection of the fluid protective layer and the dry film replaces the operation of tearing off the blue tape, the risk of residual glue and foreign object re-adhesion is completely eliminated, thereby improving the yield and adapting to complex structure designs. Finally, this solution improves production efficiency through the standardized process of ink filling and optical processes and is compatible with batch production, thus comprehensively solving the multiple defects of efficiency, precision, quality, and cost in traditional technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0037] Figure 1 Schematic flow of the method for processing a thick metal layer on the surface of a printed circuit board provided by an embodiment of the present application Figure 1 ;

[0038] Figure 2 Schematic flow of the method for processing a thick metal layer on the surface of a printed circuit board provided by an embodiment of the present application Figure 2 。

[0039] Through the above accompanying drawings, specific embodiments of the present application have been shown, and there will be more detailed descriptions hereinafter. These drawings and textual descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] Here, the exemplary embodiments will be described in detail, and the examples are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0041] First, the terms involved in the present application are explained:

[0043] In view of the technical problems of low processing efficiency, poor processing accuracy and easy foreign object adhesion in the existing processing methods for local thick metal coatings on printed circuit boards, the technical concept of this application is as follows: Apply solder mask ink on the surface of the printed circuit board, open a window in the target area of this layer of solder mask ink through optical exposure and development, and then cure the solder mask ink to protect the non-metallized area of the circuit board. Apply a flowable protective material on the surface of the solder mask ink layer, level the surface of the solder mask ink layer and open a window. Affix a dry film on the surface of the temporary protective layer formed by the flowable protective material, and through secondary optical exposure and development, open a window in the target area on the surface of the dry film. Fabricate a metal layer in the opened target area to form a metal layer on the surface of the printed circuit board. Finally, remove the dry film and the temporary protective layer.

[0044] The following uses specific embodiments to elaborate in detail on the technical solutions of this application and how the technical solutions of this application solve the above technical problems. These several specific embodiments below can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of this application will be described below with reference to the accompanying drawings.

[0045] Figure 1 Schematic flow of the method for processing a thick metal layer on the surface of a printed circuit board provided by an embodiment of this application Figure 1 , as Figure 1 shown, the method includes:

[0046] S101. Apply solder mask ink on the surface of the printed circuit board to form a solder mask ink layer;

[0047] Specifically, before applying the solder mask ink, the following processes are also included:

[0048] Inner layer circuit fabrication:

[0049] Material preparation: Select a suitable copper clad laminate, usually an epoxy resin fiberglass board (FR4).

[0050] Graphic transfer: Transfer the circuit pattern to the copper clad laminate through lithography technology. Cover the board with a photosensitive film, and then through exposure and development, the circuit pattern is revealed.

[0051] Etching: Put the developed board into an etching solution to remove the unprotected copper foil, leaving the required circuit pattern.

[0052] Desmearing: Remove the photosensitive film protecting the circuit to expose the copper circuit.

[0053] 2. Lamination:

[0054] Lamination preparation: Align the layers of the multi-layer circuit board and place them in a laminator. Use prepreg as the insulating layer.

[0055] Thermal Compression Bonding: Under high temperature and high pressure, laminate each layer together to make it a whole. This process ensures the bonding and electrical connection between layers.

[0056] 3. Drilling:

[0057] Positioning Drilling: Use a CNC drilling machine to drill through-holes (vias) and mounting holes on the board. These holes are used for interlayer connection and component mounting.

[0058] Deburring: After drilling, perform deburring to ensure the smoothness of the hole edges.

[0059] 4. Electroplating:

[0060] Hole Metallization: Deposit a layer of copper on the inner wall of the drilled holes through electroless copper plating and electroplating processes to achieve interlayer electrical connection.

[0061] Full Board Electroplating: Electroplate the entire board surface to increase the thickness of the copper layer, improving conductivity and mechanical strength.

[0062] 5. Outer Layer Pattern Making:

[0063] Pattern Transfer: Similar to the inner layer circuit production, transfer the outer layer circuit pattern to the board through photolithography technology.

[0064] Etching: Remove the unprotected copper to form the outer layer circuit pattern.

[0065] Film Removal: Remove the protective film to expose the final copper circuit.

[0066] 6. Automatic Optical Inspection (AOI):

[0067] Inspection: Use AOI equipment to inspect the circuit board to ensure the integrity and accuracy of the circuit, and identify any defects or non-conformities with the design.

[0068] 7. Pretreatment before Solder Mask:

[0069] Surface Cleaning: Clean the circuit board surface to remove any residual chemicals or impurities, ensuring good adhesion of the solder mask ink.

[0070] Oxidation Treatment: Sometimes, perform a slight oxidation treatment to improve the adhesion of the solder mask ink.

[0071] After completing the above steps, the circuit board is ready for the solder mask process. Since it is necessary to distinguish the metallized areas from the non-metallized areas on the surface of the printed circuit board, the technical idea of this step is to provide a basic protective layer for subsequent selective metallization. By applying the solder mask ink, a physical and chemical isolation barrier can be formed in the non-target areas to prevent metal deposition on the non-designed areas during the subsequent electroplating process. Specifically, when implemented, the solder mask ink can be evenly covered on the board surface, for example, by screen printing, spraying or roll coating, and the ink layer is preliminarily cured by pre-baking (for example, at 80 - 100 °C for 30 - 60 minutes). The technical effect of this step is that through the preliminary construction of the solder mask layer, it lays a foundation for subsequent precise window opening and height difference filling, while avoiding interference of the metallization process on non-target areas.

[0072] S102. Through optical exposure and development processing, remove the solder mask ink on the target areas of the solder mask ink layer, and then cure the solder mask ink layer.

[0073] Due to the defects of low precision and poor efficiency in traditional mechanical cutting methods, the technical idea of this step is to use optical imaging exposure technology to achieve high-precision window opening. Specifically, when implemented, for example, a photomask (including a transparent pattern of the target area) can be first covered on the solder mask ink layer, and the ink in the target area undergoes a photochemical reaction through ultraviolet light exposure. Then, an alkaline developer (such as a 1 - 2% sodium carbonate solution) is used to dissolve the ink in the unexposed areas, thereby precisely exposing the areas to be metallized. The curing process can be carried out, for example, by high-temperature baking (for example, at 150 - 160 °C for 60 - 90 minutes) to completely crosslink and harden the solder mask ink. The technical effect of this step is that through precise control of the photochemical reaction, high-precision window opening accuracy is achieved, and at the same time, the cured solder mask layer can resist chemical and mechanical impacts in subsequent processes.

[0074] S103. Coat a flowable protective material on the surface of the solder mask ink layer, perform a flow leveling treatment on the surface of the solder mask ink layer to form a flat temporary protective layer, and remove the flowable protective material on the target areas of the temporary protective layer.

[0075] Due to the height difference between the solder mask layer and the substrate on the board surface, the technical idea of this step is to use a fluid protective material to fill the surface to eliminate the defect that traditional blue tape cannot be fully adhered. The fluid protective material can be, for example, anti-electroplating ink. Specifically, when implementing, anti-electroplating ink (such as acrylic photosensitive ink) can be applied by screen printing or spraying. Utilize its fluidity to automatically fill the concave areas and form a semi-cured temporary protective layer through pre-baking (for example, at 70 - 80 °C for 20 - 30 minutes). When removing the protective material in the target area, for example, the same photomask as in S102 can be used for secondary exposure and development, or laser direct imaging (LDI) technology can be used. The technical effect of this step is that the board surface reaches a flat state through fluid filling, providing a uniform base for subsequent dry film attachment and avoiding the risk of foreign matter residue at the same time.

[0076] S104. Apply a dry film on the surface of the temporary protective layer to form a dry film layer;

[0077] Since the non-metallized area needs to be protected during the metallization process, the technical idea of this step is to provide an effective barrier through the dry film layer. Specifically, when implementing, for example, a photoresist dry film can be laminated on the surface of the temporary protective layer by a thermal lamination process (such as at a temperature of 100 - 120 °C and a pressure of 0.3 - 0.5 MPa), or a vacuum laminator can be used to ensure no bubbles are attached. When using anti-electroplating ink to form the temporary protective layer, a micro-etching solution can be used to clean the surface of the anti-electroplating ink layer to be laminated. The micro-etching solution is a chemical solution that usually contains acidic components and can slightly etch the surface to remove a very thin layer of material. This not only cleans the surface but also increases the surface roughness, thereby improving the adhesion of the dry film. By using the micro-etching solution to clean the surface of the anti-electroplating ink layer to be laminated, oxides, contaminants, and other impurities that may affect the dry film adhesion on the surface of the temporary protective layer can be removed. The technical effect of this step is that through the double-layer protection structure of the dry film and the fluid protective material, it not only prevents the non-metallized area from being affected during the metallization process but also improves the anti-mechanical scratching ability, thereby reducing the quality abnormality rate during the production process.

[0078] S105. Through optical exposure and development processing, remove the dry film in the target area on the dry film layer;

[0079] To achieve precise positioning of the metallized area, the technical idea of this step is to pattern the dry film in combination with a high-resolution photomask. Specifically, when implementing, for example, the same optical exposure parameters as in S102 can be used, and a 1 - 2% sodium carbonate solution can be used for development to remove the dry film in the unexposed area. For high-precision requirement scenarios, for example, it can be upgraded to laser direct imaging (LDI) technology to directly write the design data into the dry film layer. The technical effect of this step is to improve the positioning accuracy of the metallized area, that is, the target area, through the superimposed application of photochemical processes.

[0080] S106. Fabricate a metal layer in the target area to form a metal layer on the target area on the surface of the printed circuit board;

[0081] To achieve reliable deposition of the local thick metal layer, the technical idea of this step is to adopt a selective electroplating process. Specifically, for example, a pulse electroplating device can be used to sequentially deposit electroless nickel palladium gold (ENEPIG) or directly electroplate hard gold in the target area.

[0082] S107. Remove the dry film and the temporary protective layer.

[0083] To complete the final surface treatment, the technical idea of this step is to remove the temporary masking material in stages. Specifically, for example, the dry film can be peeled off first with a 3 - 5% sodium hydroxide solution at 40 - 50°C, and then the anti - electroplating ink layer can be dissolved with a special film - removing agent (such as a dimethyl sulfoxide - based solvent) or an alkaline solution. For special ink materials, physical removal methods such as plasma cleaning or laser ablation can be used, for example. The technical effect of this step is that through the chemical - physical collaborative removal process, while thoroughly removing the temporary layer, damage to the solder mask ink layer and the metallized area is avoided, and finally a finished surface with high cleanliness is obtained.

[0084] The technical effects of this embodiment are as follows: Since the traditional method relies on mechanical cutting with blue tape, there are problems such as low efficiency, poor precision, and foreign matter residue. In this solution, by superimposing a fluid - type protective material on the solder mask ink layer, using the openings of the solder mask ink and subsequent curing to provide reference positioning, and using the fluidity of the fluid - type protective material to fill the surface height difference, the flatness of the board surface is ensured, and the precision of subsequent optical windowing on the dry film is improved; at the same time, combined with subsequent dry film attachment and optical exposure and development, three - time high - precision windowing can be achieved, thus improving the windowing precision and avoiding the offset problem of mechanical cutting; in addition, since the double - layer protection of the fluid - type protective material and the dry film replaces the operation of tearing the blue tape, the risk of residual glue and foreign matter re - adhesion is completely eliminated, thus improving the yield and adapting to complex structure designs; finally, through the standardized process of ink filling and optical processes, this solution improves production efficiency and is compatible with batch production, so it comprehensively solves multiple defects of efficiency, precision, quality, and cost in traditional technologies.

[0085] Optionally, a photosensitive resin can be used as the fluid - type protective material. Figure 2 Schematic flow of the method for processing a thick metal layer on the surface of a printed circuit board provided by an embodiment of the present application Figure 2 , as Figure 2 shown, this method includes:

[0086] S201. Coat a solder mask ink on the surface of the printed circuit board to form a solder mask ink layer;

[0087] S202. Through optical exposure and development processes, remove the solder mask ink on the target area of the solder mask ink layer, and then cure the solder mask ink layer.

[0088] S203. Coat a photosensitive resin on the surface of the solder mask ink layer, perform a flow leveling process on the surface of the solder mask ink layer, and pre-bake the photosensitive resin to semi-cure it to form a temporary protective layer.

[0089] The technical idea of this step is to achieve surface planarization using a photosensitive resin. Specifically, for example, the photosensitive resin can be evenly coated on the surface of the solder mask layer through a spin coating process, and its fluidity is used to fill the concave areas. Subsequently, it is pre-baked at 80 °C for 10 minutes to make the resin reach a semi-cured state. The technical effect of this step is that the surface undulations are eliminated through the flow leveling of the photosensitive resin, forming a temporary protective layer with a uniform thickness, providing a flat base surface for subsequent dry film attachment.

[0090] S204. Through optical exposure and development processes, remove the photosensitive resin on the target area of the temporary protective layer.

[0091] Specifically, for example, a laser direct imaging device can be used to expose the photosensitive resin, and then it is developed with a propylene glycol monomethyl ether acetate (PGMEA) solution to dissolve the resin in the unexposed area. The technical effect of this step is to achieve precise alignment of the second opening through the developability of the photosensitive resin.

[0092] S205. Attach a dry film on the surface of the temporary protective layer to form a dry film layer, and then through optical exposure and development processes, remove the dry film on the target area of the dry film layer.

[0093] S206. Fabricate a metal layer in the target area to form a metal layer on the target area on the surface of the printed circuit board.

[0094] S207. Remove the dry film and the temporary protective layer.

[0095] Specifically, for example, first soak the dry film in a 3% sodium hydroxide solution at 50 °C for 10 minutes to peel it off, then dissolve the photosensitive resin with an organic solvent such as acetone, and finally rinse with deionized water and dry.

[0096] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention, which follow the general principles of the present invention and include common general knowledge or conventional technical means in the technical field not disclosed in the present invention. It is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A method for processing a thick metal layer on the surface of a printed circuit board, characterized in that The method includes: Coating a solder mask ink on the surface of a printed circuit board to form a solder mask ink layer; Removing the solder mask ink in a target area on the solder mask ink layer through optical exposure and development processing, and then curing the solder mask ink layer; Coating a flowable protective material on the surface of the solder mask ink layer, performing a flow leveling process on the surface of the solder mask ink layer to form a flat temporary protective layer, and then removing the flowable protective material in the target area on the temporary protective layer; Laminating a dry film on the surface of the temporary protective layer to form a dry film layer; Removing the dry film in the target area on the dry film layer through optical exposure and development processing; Fabricating a metal layer in the target area to form a metal layer in the target area on the surface of the printed circuit board; Removing the dry film and the temporary protective layer.

2. The method according to claim 1, wherein The coating of the flowable protective material on the surface of the solder mask ink layer and performing a flow leveling process on the surface of the solder mask ink layer to form a temporary protective layer includes: Coating an anti-electroplating ink on the surface of the solder mask ink layer and performing a flow leveling process on the surface of the solder mask ink layer; Performing a pre-baking process on the anti-electroplating ink to semi-cure the anti-electroplating ink to form the temporary protective layer.

3. The method according to claim 2, wherein The removing of the flowable protective material in the target area on the temporary protective layer includes: Removing the anti-electroplating ink in the target area on the temporary protective layer through optical exposure and development processing.

4. The method according to claim 2, wherein The laminating of the dry film on the surface of the temporary protective layer includes: Cleaning the surface of the anti-electroplating ink layer to be laminated with the dry film using a micro-etching solution; Laminating a dry film on the surface to be laminated with the dry film.

5. The method according to claim 2, characterized in that The removing of the temporary protective layer includes: Dissolving the anti-electroplating ink using an alkaline solution to remove the temporary protective layer.

6. The method according to claim 1, wherein The coating of the flowable protective material on the surface of the solder mask ink layer and performing a flow leveling process on the surface of the solder mask ink layer to form a temporary protective layer includes: Coating a photosensitive resin on the surface of the solder mask ink layer and performing a flow leveling process on the surface of the solder mask ink layer; Performing a pre-baking process on the photosensitive resin to semi-cure the photosensitive resin to form the temporary protective layer.

7. The method according to claim 6, characterized in that, The removing of the flowable protective material in the target area on the temporary protective layer includes: Removing the photosensitive resin in the target area on the temporary protective layer through optical exposure and development processing.

8. The method according to claim 6, wherein The removing of the temporary protective layer includes: Dissolving the photosensitive resin using an organic solvent to remove the temporary protective layer.

9. The method according to any one of claims 1-8, characterized in that, The fabricating of the metal layer in the target area includes: Performing a metal plating process in the target area.

10. A printed circuit board, characterized in that, The printed circuit board is processed by the method described in any one of claims 1-9.

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