Circuit board manufacturing method and circuit board

Abstract

The invention discloses a manufacturing method of a circuit board and the circuit board. The manufacturing method comprises the following steps: cutting a working board according to engineering data; wherein the working plate comprises a substrate and a copper layer covering an element surface and a welding surface on two sides of the substrate; carrying out first whole plate electroplating on the working plate; covering a dry film on the surface of the element; developing the element surface; performing acid etching on the first non-circuit region; screen printing resin in the first non-circuit area; carrying out second-time whole plate electroplating on the working plate; covering a dry film on the element surface, and performing external image development on the element surface, the first circuit area being not covered by the dry film, and the first non-circuit area being covered by the dry film; electroplating a copper layer with the thickness of H3 in the first circuit area; and removing a dry film from the first non-circuit area after tinning the first circuit area so as to carry out alkaline etching on the first non-circuit area. The first non-line area is etched twice, the copper thickness of each etching is reduced, the line width compensation can be greatly reduced, and the problem that the line width compensation is small is solved.

Description

Circuit board manufacturing methods and circuit boards Technical Field

[0001] This invention relates to the field of circuit board technology, and in particular to a method for manufacturing a circuit board and a circuit board. Background Technology

[0002] Traditional circuit board etching involves electroplating and micro-etching to reduce copper thickness to the required thickness, followed by a final etching process to obtain the circuit pattern that meets the customer's size requirements.

[0003] For some power supply products, the line compensation specified by the customer is significantly insufficient. This is due to the insufficient linewidth compensation on the component surface; in addition, the difference in copper thickness between the component and the solder side is close to 100um. When processed using traditional methods, the overall linewidth of the component surface is about 0.2mm smaller than required by the customer, which does not meet the customer's requirements. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method for manufacturing a circuit board in which the first non-circuit zone on the component side is etched twice, and the copper area of ​​each etching is reduced, which can greatly reduce the linewidth compensation and solve the problem of insufficient linewidth compensation.

[0005] According to a first aspect of the present invention, a method for manufacturing a circuit board includes: S1: cutting a work board with dimensions conforming to engineering data; wherein the work board includes a substrate and copper layers covering component surfaces and solder surfaces on both sides of the substrate; S2: performing a first full-board electroplating on the work board to form a copper layer with a thickness of H1 on the component surfaces and solder surfaces located on both sides of the substrate; S3: covering the component surfaces of the substrate with dry film and exposing it; S4: developing the component surfaces, wherein the areas covered by dry film are first circuit areas, and the areas not covered by dry film are first non-circuit areas; S5: performing acid etching on the first non-circuit areas; S6: screen printing resin on the first non-circuit areas. S7: The resin is cured and then polished with a ceramic brush until it is flush with the copper surface; S8: The work board is electroplated a second time, with the copper layer thickness of the first circuit area being H1+H2 and the copper layer thickness of the first non-circuit area being H2; S9: A dry film is applied to the component surface and exposed, and the component surface is developed externally, with no dry film covering the first circuit area and a dry film covering the first non-circuit area; S10: A copper layer with a thickness of H3 is electroplated in the first circuit area to make the first circuit area electroplated to a preset thickness; S11: After tin plating in the first circuit area, the dry film in the first non-circuit area is removed to perform alkaline etching on the first non-circuit area.

[0006] According to the circuit board manufacturing method of the present invention, the etching is performed in two stages, and the copper area of ​​each etching is reduced, which can greatly reduce the line width compensation and solve the problem of insufficient line width compensation.

[0007] According to some embodiments of the present invention, between step S3 and step S4, the manufacturing method further includes: performing a first micro-etching to reduce copper on the welding surface and covering the component surface with a dry film.

[0008] According to some embodiments of the present invention, the working plate is washed with dry film between step S5 and step S6.

[0009] According to some embodiments of the present invention, after step S7, the welding surface is subjected to a second micro-etching to reduce the copper layer thickness to H4.

[0010] According to some embodiments of the present invention, H2 and H4 satisfy the relationship: 5 mm ≤ H4 - H2 ≤ 20 mm.

[0011] According to some embodiments of the present invention, step S8 further includes: covering the welding surface with a dry film and performing external pattern development on the welding surface, wherein the area covered by the dry film is the second non-circuit area and the area not covered by the dry film is the second circuit area.

[0012] According to some embodiments of the present invention, step S9 further includes: electroplating a copper layer with a thickness of H3 in the second line area, so that the second line area is electroplated to a preset thickness.

[0013] According to some embodiments of the present invention, step S10 further includes: removing the dry film from the second non-circuit region after tin plating in the second circuit region, so as to perform alkaline etching on the second non-circuit region.

[0014] According to a second aspect of the present invention, the circuit board is characterized in that it is manufactured using the circuit board manufacturing method according to any one of claims 1-8.

[0015] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: FIG1 is a flowchart of a method for manufacturing a circuit board according to an embodiment of the present invention; FIG2 is a structural schematic diagram of a work board according to an embodiment of the present invention; FIG3 is a schematic diagram of the work board after the first full-board copper plating according to an embodiment of the present invention; FIG4 is a schematic diagram of copper reduction on the soldering surface after covering the component surface with dry film according to an embodiment of the present invention; FIG5 is a schematic diagram of developing the component surface according to an embodiment of the present invention; FIG6 is a schematic diagram of the component surface after acid etching according to an embodiment of the present invention; FIG7 is a schematic diagram of screen printing resin on the first non-circuit area according to an embodiment of the present invention; FIG8 is a schematic diagram of developing the component surface according to an embodiment of the present invention; FIG8 is a schematic diagram of developing the component surface with dry film after acid etching according to an embodiment of the present invention; FIG7 is a schematic diagram of screen printing resin on the first non-circuit area according to an embodiment of the present invention; FIG8 is a schematic diagram of developing the component surface according to an embodiment of the present invention; FIG8 is a schematic diagram of developing the component surface according to an embodiment of the present invention; FIG8 is a schematic diagram of developing the component surface according to an embodiment of the present invention; FIG9 is a schematic diagram of developing the component surface according to an embodiment of the present invention; FIG1 is a flowchart of a method for manufacturing a circuit board ... Figure 9 is a schematic diagram of a second full-board electroplating of a substrate according to an embodiment of the present invention; Figure 10 is a schematic diagram of covering the component side with dry film and performing a second copper reduction on the solder side according to an embodiment of the present invention; Figure 11 is a schematic diagram of exposure and development of the component side and the solder side according to an embodiment of the present invention; Figure 12 is a schematic diagram of tin plating after pattern electroplating of the first circuit area and the second circuit area according to an embodiment of the present invention; Figure 13 is a schematic diagram of removing the dry film from the component side and the solder side according to an embodiment of the present invention; Figure 14 is a schematic diagram of alkaline etching of the component side and the solder side according to an embodiment of the present invention.

[0017] Reference numerals: 11, substrate; 12, component side; 121, first circuit area; 122, first non-circuit area; 13, soldering side; 131, second circuit area; 132, second non-circuit area; 14, resin; 15, tin. Detailed Implementation

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

[0019] A method for manufacturing a circuit board according to an embodiment of the present invention will be described below with reference to Figures 1-14. A circuit board including the above method will also be proposed.

[0020] Referring to Figures 1-14, the method for manufacturing a circuit board according to a first aspect of the present invention includes the following steps: S1: cutting a work board with dimensions that meet the requirements according to engineering data; wherein, the work board includes a substrate 11 and a copper layer covering the component surface 12 and the solder surface 13 on both sides of the substrate 11.

[0021] As shown in Figure 1, the specific specifications of the work board, such as length, width, and thickness, need to be determined first based on detailed engineering data (including design drawings, dimensional parameters, process specifications, etc.). Then, suitable raw materials are selected. These materials form the basic structure of the work board, consisting of a substrate 11 and copper layers covering both sides of the substrate 11. One side of the copper layer will later serve as the component surface 12, used for soldering and mounting various electronic components; the other side serves as the soldering surface 13, mainly used for electrical connection and fixation between component pins and the circuit board.

[0022] Specifically, both the upper and lower surfaces of the substrate 11 are covered with copper layers. The upper surface of the substrate 11 is the component surface 12, and the lower surface of the substrate 11 is the solder surface 13. Both the component surface 12 and the solder surface 13 are covered with copper layers, and the thickness of the copper layers is between 10μm and 20μm.

[0023] S2: Perform the first full-board electroplating on the work board to form a copper layer with a thickness of H1 on the component surface 12 and the solder surface 13 located on both sides of the substrate 11.

[0024] The thickness H1 of the copper layer is 65%-70% of the copper thickness required by the customer.

[0025] As shown in Figure 3, the first full-board electroplating can enhance the conductivity of the substrate 11. More importantly, it provides sufficient copper material reserves for the subsequent circuit electroplating after pattern transfer, avoiding damage or breakage of the circuit during the subsequent etching process due to the base copper layer being too thin, thereby ensuring the electrical performance and structural stability of the circuit board.

[0026] Specifically, the work board is subjected to a first full-board electroplating, that is, copper layers are electroplated on both the component surface 12 and the solder surface 13 located on both sides of the substrate 11. After electroplating, the total thickness of the copper layer on the component surface 12 and the solder surface 13 is H1. The total thickness of the initial copper layer of the work board plus the copper layer of the first full-board electroplating is H1.

[0027] S3: Cover the component side 12 of the substrate 11 with a dry film and expose it.

[0028] After the dry film is applied to the component surface 12, it covers the copper layer of the component surface 12. The dry film can shield areas that do not need to be exposed and developed, control the range of exposure and development, and prevent the etching solution from etching the copper layer, thus preventing the copper layer of the component surface 12 from being eroded in subsequent operations.

[0029] S4: Develop the component surface 12. The area covered by dry film is the first circuit area 121, and the area not covered by dry film is the first non-circuit area 122.

[0030] As shown in Figures 4 and 5, after the dry film is applied to the component surface 12, the component surface 12 can be exposed and developed to transfer the circuit pattern to the component surface 12. The area between the circuits is not covered by dry film, that is, the area between the circuits is the first non-circuit area 122; the area where the circuit pattern is located is covered by dry film, that is, the location of the circuit pattern is the first circuit area 121.

[0031] S5: Perform acid etching on the first non-circuit region 122.

[0032] As shown in Figure 6, specifically, under the action of the chemical reaction, the exposed copper layer is gradually dissolved and peeled off, while the circuit pattern area protected by the photoresist remains unaffected. Acid etching is performed on the first non-circuit region 122, which is not covered by the dry film, to etch away the copper layer of thickness H1 in the first non-circuit region 122. Then, the copper layer thickness of the first non-circuit region 122 becomes 0, forming a copper-free groove between the first non-circuit region 122 and the first circuit region 121.

[0033] During the acid etching process, it is necessary to ensure that the copper layer of the first non-line area 122 is completely etched clean, while avoiding over-etching that would cause severe edge erosion of the first line area 121, affecting the accuracy and integrity of the line.

[0034] S6: Silk screen resin 14 in the first non-circuit area 122 and cure the resin 14. Then, polish the resin 14 with a ceramic brush plate until it is flush with the copper surface.

[0035] As shown in Figure 7, screen printing resin 14 is typically based on polymer resin 14 (such as epoxy resin 14, acrylic resin 14, etc.), with added curing agents, pigments, fillers, and additives to form a paste or liquid ink with specific properties. It can maintain good fluidity to pass through the screen mesh, and can also quickly set after printing to avoid sagging or spreading.

[0036] Resin 14 is screen-printed in the groove of the first non-circuit area 122, such that the thickness of resin 14 is the same as the thickness of copper layer of the first circuit area 121, and the upper surface of resin 14 is flush with copper layer of the first circuit area 121.

[0037] S7: Perform a second full-board hole formation and electroplating on the work board. The copper layer thickness of the first circuit area 121 is H1+H2, and the copper layer thickness of the first non-circuit area 122 is H2.

[0038] As shown in Figure 8, the second full-board electroplating involves electroplating a copper layer of thickness H2 on both the component surface 12 and the solder surface 13. After electroplating, the surfaces of the first circuit area 121 and the second circuit area 131 on the component surface 12 are flush. The copper layer of the first circuit area 121 is thickened by H2 on top of the original thickness H1, so the thickness of the copper layer of the first circuit area 121 is H1 + H2. The first non-circuit area 122 is electroplated with a copper layer on the surface of the resin 14. Since the surfaces of the first circuit area 121 and the second circuit area 131 are flush, the total thickness of the first non-circuit area 122 is also H1 + H2, where the thickness of the resin 14 is H1 and the thickness of the copper layer in the first non-circuit area 122 is H2.

[0039] S8: Cover the component surface 12 with a dry film and expose it, and perform external pattern development on the component surface 12. The first circuit area 121 is not covered by dry film, and the first non-circuit area 122 is covered by dry film.

[0040] As shown in Figure 11, after the second full-board electroplating of the work board, a dry film is applied to the component surface 12. The dry film covers the copper layer of the component surface 12. The dry film can shield areas that do not need to be exposed and developed, control the exposure and development range, and prevent the etching solution from etching the copper layer, thus preventing the copper layer of the component surface 12 from being eroded in subsequent operations. The dry film of the first circuit area 121 is exposed and developed away, while the dry film of the first circuit area 121 is retained, that is, the component surface 12 is subjected to external pattern development.

[0041] S9: Electroplating a copper layer with a thickness of H3 in the first line area 121 to electroplat the first line area 121 to a preset thickness.

[0042] Referring to Figure 12, a copper layer is electroplated at the location where the dry film has been developed using a pattern electroplating process. The thickness of the copper layer is H3, which is the same as the thickness of the dry film. The surfaces of the first line area 121 and the first non-line area 122 are flush.

[0043] The preset thickness is the copper thickness required by the customer, and it is flush with the first non-circuit area 122.

[0044] S10: After tin plating 15 in the first line area 121, the dry film in the first non-line area 122 is removed to perform alkaline etching on the first non-line area 122.

[0045] As shown in Figures 13 and 14, tin 15 is often used as an anti-etching protective layer in the "pattern plating-etching" process for circuit board pattern fabrication. A tin 15 layer is plated onto the surface of the copper traces that need to be preserved through pattern plating. During subsequent etching, the tin 15 layer resists the corrosion of the etching solution, protecting the underlying copper traces from dissolution. After etching, the tin 15 layer is removed, resulting in a precise circuit pattern.

[0046] The dry film can be removed by chemical washing or physical washing.

[0047] After removing the dry film from the first non-circuit region 122, an alkaline etching process is performed on the copper layer of the first non-circuit region 122 with a thickness of H3 to remove the copper layer of the first non-circuit region 122 and complete the circuit pattern of the component surface 12.

[0048] Therefore, the first etching uses acidic etching with a depth of H1, and the second etching uses alkaline etching with a depth of H3. With a copper thickness of H1+H2+H3, the copper area is reduced in each etching step. The smaller the copper area, the smaller the required linewidth compensation. This greatly reduces the linewidth compensation and is suitable for situations where the customer's required linewidth compensation is too small. It can solve the problem of the linewidth being too small after etching.

[0049] In some embodiments, between steps S3 and S4, the manufacturing method further includes: performing a first micro-etching to reduce copper on the soldering surface 13 and covering the component surface 12 with a dry film.

[0050] As shown in Figure 4, an acidic etching solution (such as ammonium persulfate, sulfuric acid-hydrogen peroxide system, etc.) is used to undergo a mild chemical reaction with copper to perform the first micro-etching of the copper layer on the welding surface 13, dissolving a certain thickness of copper layer and thus reducing the thickness of the copper layer.

[0051] During the operation, the micro-etching parameters must be strictly controlled, including the concentration of the etching solution, temperature, processing time and spray pressure, to ensure that the reduction in copper layer thickness is precise and controllable—achieving both surface cleaning and roughening effects, while avoiding excessive etching that could lead to excessive loss of copper layer thickness.

[0052] After micro-etching to reduce copper, before acid etching the component surface 12, a dry film needs to be applied to the solder surface 13. The dry film covers the copper layer of the solder surface 13. The dry film can shield areas that do not need to be exposed and developed, control the range of exposure and development, and prevent the etching solution from etching the copper layer, thus preventing the copper layer of the solder surface 13 from being eroded in subsequent operations.

[0053] In some embodiments, between steps S5 and S6, the dry film on the work board is stripped. That is, after acid etching of the component surface 12, the dry film on the component surface 12 and the solder surface 13 is removed to facilitate the subsequent second full-board electroplating of the work board.

[0054] As shown in Figure 9, after step S7, the soldering surface 13 undergoes a second micro-etching process to reduce the copper layer thickness to H4. H2 and H4 satisfy the relationship: 5 mm ≤ H4 - H2 ≤ 20 mm. That is, the copper layer difference between the soldering surface 13 and the first non-circuit area 122 of the component surface 12 is between 5 μm and 20 μm. By controlling the difference in copper layer thickness between the component surface 12 and the soldering surface 13 that requires alkaline etching within the range of 5 μm to 20 μm, the surface copper difference between the component surface 12 and the soldering surface 13 is greatly reduced, significantly lowering the difficulty of the etching process and reducing the risk of under-etching of the circuit after etching.

[0055] As shown in Figures 10 and 11, step S8 further includes: covering the soldering surface 13 with a dry film and exposing it, and performing external pattern development on the soldering surface 13. The area covered by the dry film is the second non-circuit area 132, and the area not covered by the dry film is the second circuit area 131.

[0056] After the second full-board electroplating of the work board, a dry film is also needed to cover the component surface 12. The dry film covers the copper layer of the component surface 12. The dry film can shield areas that do not need to be exposed and developed, control the exposure and development range, and prevent the etching solution from etching the copper layer, thus preventing the copper layer of the component surface 12 from being eroded in subsequent operations. The dry film of the first line area 121 is exposed and developed away, while the dry film of the first line area 121 is retained, that is, the component surface 12 is subjected to external pattern development.

[0057] As shown in Figure 12, step S9 further includes: electroplating a copper layer with a thickness of H3 in the second circuit area 131, so that the second circuit area 131 is electroplated to a preset thickness. Specifically, a copper layer is electroplated at the location where the dry film has been developed on the solder surface 13 using a pattern electroplating process, that is, a copper layer is electroplated in the second circuit area 131, and the thickness of the copper layer is H3, that is, the thickness of the copper layer is the same as that of the dry film, and the surfaces of the second circuit area 131 and the second non-circuit area 132 are flush.

[0058] The preset thickness is the copper thickness required by the customer.

[0059] Referring to Figures 13 and 14, step S10 further includes: removing the dry film from the second non-circuit region 132 after tin plating 15 in the second circuit region 131, in order to perform alkaline etching on the second non-circuit region 132. Specifically, by removing the protective coating and selectively etching excess copper layers, a precise circuit pattern is finally formed. The dry film covers the first non-circuit region 122 and the second non-circuit region 132 (copper surfaces that do not require electroplating), while the copper surfaces of the first circuit region 121 and the second circuit region 131 have been plated with a tin 15 layer (as a protective layer for subsequent etching). At this point, the dry film removal process is required. The first circuit region 121 and the second circuit region 131 are protected by the tin 15 plating layer, while the copper layers of the first non-circuit region 122 and the second non-circuit region 132 are fully exposed, preparing for subsequent alkaline etching.

[0060] After the dry film is removed, the circuit enters the alkaline etching process, which selectively etches the exposed copper layer in non-circuit areas. After alkaline etching is completed, the residual etching solution is removed by cleaning. Only the circuit pattern protected by the 15-layer tin is left on the surface of the circuit board. The 15-layer tin plating is then removed by the 15-layer tin removal process to obtain the final circuit board.

[0061] The circuit board according to a second aspect embodiment of the present invention is manufactured using the above-described manufacturing method. The etching is performed in two stages, with each etching reducing the area of ​​copper, which significantly reduces the need for linewidth compensation and solves the problem of insufficient linewidth compensation.

[0062] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this 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. Therefore, they should not be construed as limitations on this invention.

[0063] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0064] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for manufacturing a circuit board, characterized in that, The manufacturing method includes the following steps: S1: Cutting a work board with the required size according to engineering data; wherein, the work board includes a substrate (11) and a copper layer covering the component surface (12) and the solder surface (13) on both sides of the substrate (11); S2: Performing a first whole-board electroplating on the work board to form a copper layer with a thickness of H1 on the component surface (12) and the solder surface (13) on both sides of the substrate (11); S3: Covering the component surface (12) of the substrate (11) with a dry film and exposing it; S4: Developing the component surface (12), the area covered by the dry film is the first circuit area (121), and the area not covered by the dry film is the first non-circuit area (122); S5: Performing acid etching on the first non-circuit area (122); S6: Screen printing resin (14) on the first non-circuit area (122) and etching the resin (14). S7: Perform a second full-board electroplating on the work board. The copper layer thickness of the first line area (121) is H1+H2, and the copper layer thickness of the first non-line area (122) is H2. S8: Cover the component surface (12) with a dry film and expose it. Then perform external pattern development on the component surface (12). The first line area (121) is not covered with a dry film, and the first non-line area (122) is covered with a dry film. S9: Electroplat a copper layer with a thickness of H3 on the first line area (121) to make the first line area (121) electroplated to a preset thickness. S10: After tin plating (15) on the first line area (121), remove the dry film from the first non-line area (122) to perform alkaline etching on the first non-line area (122).

2. The method for manufacturing a circuit board according to claim 1, characterized in that, Between steps S3 and S4, the manufacturing method further includes: performing a first micro-etching to reduce copper on the welding surface (13) and covering the component surface (12) with a dry film.

3. The method for manufacturing a circuit board according to claim 2, characterized in that, Between steps S5 and S6, the work plate is washed to remove the dry film.

4. The method for manufacturing a circuit board according to claim 1, characterized in that, After step S7, the welding surface (13) is subjected to a second micro-etching to reduce the copper layer thickness to H4.

5. The method for manufacturing a circuit board according to claim 4, characterized in that, H2 and H4 satisfy the following relationship: 5 mm ≤ H4 - H2 ≤ 20 mm.

6. The method for manufacturing a circuit board according to claim 1, characterized in that, Step S8 further includes: covering the welding surface (13) with a dry film and developing the welding surface (13) externally. The area covered by the dry film is the second non-circuit area (132), and the area not covered by the dry film is the second circuit area (131).

7. The method for manufacturing a circuit board according to claim 6, characterized in that, Step S9 further includes: electroplating a copper layer with a thickness of H3 in the second line area (131) to electroplat the second line area (131) to a preset thickness.

8. The method for manufacturing a circuit board according to claim 7, characterized in that, Step S10 further includes: removing the dry film from the second non-line area (132) after tin plating (15) in the second line area (131) to perform alkaline etching on the second non-line area (132).

9. A circuit board, characterized in that, It is manufactured using the circuit board manufacturing method according to any one of claims 1-8.

Images