A high-precision circuit board manufacturing method for a through-hole single-sided via ring

Abstract

The application discloses a kind of high-precision circuit board manufacturing methods of single-face hole ring of through-hole, one surface of circuit board is designed with hole ring pattern, to the circuit board to be drilled formed by processing before process upper and lower two sides are light copper surface, drill through-hole and then flash plating, form flash plating plate, first surface of flash plating plate is made dry film pattern corresponding to hole ring pattern, first through-hole is made corresponding to through-hole on second surface, first through-hole is less than through-hole on single side, form pattern plate;Pattern plate is sequentially electroplated copper layer and electroplated tin layer, form electroplated plate;Remove dry film and protective film of electroplated plate, then etch, after tin layer is faded, form circuit board, overall process uses dry film pattern, cooperates electroplated copper layer and electroplated tin layer processing, uses electroplated tin to protect electroplated copper layer, form ideal single-face hole ring structure, closely form an efficient and reliable production chain before and after cooperation, avoid polishing processing, greatly improve processing precision and the quality of final circuit board.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing, and in particular to a high-precision circuit board manufacturing method for a single-sided through-hole hole ring. Background Technology

[0002] Some high-precision circuit board products have high wiring density, so unnecessary vias are usually removed during the design process to increase wiring space. This type of design is usually applied to high-precision circuit boards with single-sided vias.

[0003] The manufacturing method for high-precision circuit boards with single-hole through-holes generally involves using a dry film to protect the through-hole when fabricating the circuitry on the side without the hole ring, then etching away the hole ring to form a hole-free ring pattern, followed by subsequent processing steps such as electroplating.

[0004] However, this method has the following drawbacks: on the one hand, the exposure alignment process in the pattern making process has errors, which affect the etching accuracy of the hole ring and easily lead to problems such as etching misalignment; on the other hand, the dry film in the through hole is easy to fall off during etching, making it difficult to form an effective protection for the copper layer on the inner wall of the through hole, thus leading to problems such as the copper in the hole being etched away.

[0005] Therefore, to solve the problems mentioned above, a method for manufacturing high-precision circuit boards with single-sided through-hole rings is provided. Summary of the Invention

[0006] This invention aims to solve the comprehensive problems in the existing technology for manufacturing single-sided through-hole hole ring circuit boards, such as etching misalignment due to exposure errors and easy etching and peeling off of the dry film inside the through-holes, resulting in low processing accuracy. It proposes a high-precision circuit board manufacturing method for single-sided through-hole hole rings, wherein one surface of the circuit board is designed with a hole ring pattern. The manufacturing method includes the following steps:

[0007] S10: Take the copper-clad board, process it through the previous process to form a circuit board to be drilled with bright copper surfaces on both the top and bottom. Drill the first through hole and then flash plate it to form a flash plated board.

[0008] S20: Apply a dry film to the first side of the flash-plated plate and create a dry film pattern corresponding to the hole ring pattern; apply a protective film to the second side and create a second through hole corresponding to the first through hole; the second through hole is smaller on one side than the first through hole, forming a pattern plate.

[0009] S30: Electroplating a copper layer and an electroplating tin layer onto the graphic board sequentially to form an electroplated board;

[0010] S40: Remove the dry film and the protective film from the electroplated plate, then etch, and then remove the tin layer to form the circuit board.

[0011] Furthermore, the flash plating is performed by electroplating at a current density of 3 ASF to 8 ASF for 20 to 30 minutes to form a copper thickness of 3 μm to 8 μm.

[0012] Furthermore, the graphic plate is fabricated by attaching the dry film to both the first and second sides of the flash-plated plate, and fabricating the dry film pattern on the first side corresponding to the hole ring pattern position, and fabricating the second through hole on the second side corresponding to the first through hole position, wherein one side of the second through hole is smaller than the first through hole, thus forming the graphic plate.

[0013] Furthermore, the dry film is removed by a film stripping process.

[0014] Furthermore, the graphic board is fabricated by applying a dry film to the first side of the flash-plated plate and fabricating the dry film pattern at the position corresponding to the hole ring pattern on the first side. Then, a PET film, PP film, acrylic film, polyimide film, epoxy resin film, or blue tape is applied to the second side, and a second through hole is fabricated corresponding to the first through hole. The second through hole is smaller on one side than the first through hole, thus forming the graphic board.

[0015] Furthermore, the protective film is removed by peeling or alkaline washing.

[0016] Furthermore, the second through hole and the first through hole are at the same center, and the diameter of the second through hole is 1 / 3 to 1 / 2 smaller than the diameter of the first through hole.

[0017] Furthermore, the second through hole is fabricated using a laser ablation method.

[0018] Furthermore, the electroplated copper layer is an additional 3μm to 8μm of copper thickness electroplated onto the graphic board according to the design; forming the circuit board also includes micro-etching after removing the tin layer.

[0019] Furthermore, the micro-etching involves etching away a copper thickness of 3μm to 8μm.

[0020] This invention compensates for exposure errors by applying a protective film to the second surface (where no hole ring is designed) and fabricating a second through-hole corresponding to the first through-hole, with the diameter of the second through-hole being smaller than that of the first through-hole. This ensures that the edge of the hole wall is completely covered and effectively prevents copper layer deposition on the edge of the dry film or even above the board surface during electroplating. This simplifies post-processing and planarization, reduces the probability of quality problems such as short circuits, and solves the problems of exposure alignment errors affecting the etching accuracy of the hole ring and easily leading to etching misalignment during pattern fabrication in existing technologies. Furthermore, by plating a tin layer on top of the electroplated copper layer... This process protects the copper layer and solves the problem of dry film easily falling off during etching, causing the copper inside the hole to be etched away. The overall process uses dry film patterning, combined with electroplated copper and tin layers. The tin plating protects the electroplated copper layer, ensuring that the electroplating process only occurs on the hole ring pattern and the inner wall of the first through hole, thus forming an ideal single-sided hole ring structure and achieving high-precision processing. The close cooperation between the front and back ends forms an efficient and reliable production chain, avoiding the significant impact of grinding on the expansion and contraction of the board, and greatly improving processing accuracy, first-pass yield, and the quality of the final circuit board. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the process flow of an embodiment of the present invention;

[0023] Figure 2 This is a cross-sectional schematic diagram of the flash-plating plate according to an embodiment of the present invention;

[0024] Figure 3 This is a cross-sectional schematic diagram of the graphic plate according to an embodiment of the present invention;

[0025] Figure 4 for Figure 3 A plan view;

[0026] Figure 5 This is a cross-sectional schematic diagram of the electroplated plate according to an embodiment of the present invention;

[0027] Figure 6 This is a cross-sectional schematic diagram of the film-removing plate according to an embodiment of the present invention;

[0028] Figure 7 This is a cross-sectional schematic diagram of the high-precision circuit board with a single-hole through-hole ring according to this embodiment.

[0029] Explanation of icon numbers:

[0030]

[0031] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] It should be noted that all directional indications (such as up, down, left, right, front, back, inside, outside, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0034] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0035] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0036] Please see Figure 1 , Figure 1 This is a schematic diagram of the process flow according to an embodiment of the present invention.

[0037] One surface of the circuit board in this embodiment of the invention is designed with a hole ring pattern, and the manufacturing method includes using... Figure 1 The implementation of each step in the process will be described below. Figure 1 The process of each step will be explained step by step.

[0038] Please refer to Figure 2 , Figure 2 This is a cross-sectional schematic diagram of the flash-plating plate according to an embodiment of the present invention.

[0039] Step S10:

[0040] Take the copper-clad board, process it through the previous process to form a circuit board to be drilled with bright copper surfaces on both the top and bottom. Drill the first through hole 1010, and then flash plate it to form flash plated board 10.

[0041] The purpose of flash plating after drilling the first through hole 1010 is to form a very thin and uniform conductive metal layer 1020 on the inner wall of the first through hole 1010, providing a conductive path for the subsequent electroplating process, allowing current to pass through the interior of the first through hole 1010, thereby allowing the copper layer to be deposited on the hole wall.

[0042] Furthermore, flash plating is performed using a current density of 3 ASF to 8 ASF for 20 to 30 minutes to form a copper thickness of 3 μm to 8 μm. The thickness of the conductive metal layer 1020 is controlled between 3 μm and 8 μm, which ensures good conductivity without increasing unnecessary costs and processing complexity due to excessive copper thickness.

[0043] Since current density directly affects the quality of the conductive metal layer 1020, lower current density (such as 3 ASF) usually produces a finer, more uniform coating with less internal stress, while higher current density (such as 8 ASF) may lead to a faster deposition rate, but also increases defects such as roughness, resulting in a decrease in the quality of the conductive metal layer 1020. Therefore, this embodiment selects a current density of 3 ASF to 8 ASF and further controls it within 20 to 30 minutes to effectively ensure the rapid and efficient formation of a uniform and thin conductive metal layer 1020, ensuring good conductivity and the feasibility of subsequent processing, and providing a processing basis for subsequent processing steps.

[0044] Please see Figure 3 and Figure 4 , Figure 3 This is a cross-sectional schematic diagram of the graphic plate according to an embodiment of the present invention; Figure 4 for Figure 3 A plan view.

[0045] Step S20:

[0046] A dry film 2030 is applied to the first side of the flash-plated plate, and a dry film pattern 2010 is made corresponding to the hole ring pattern. A protective film 2040 is applied to the second side, and a second through hole 2020 is made corresponding to the first through hole 1010. The second through hole 2020 is smaller on one side than the first through hole 1010, forming a patterned plate 20.

[0047] The process of creating a dry film graphic in 2010 involves applying the dry film, exposure, and development.

[0048] As an alternative implementation, the dry film 2030 is tightly attached to the first side of the flash plating plate 10, and then the hole ring pattern to be retained is exposed onto the dry film 2030 using laser imaging technology (LDI). After that, the unexposed part of the dry film 2030 is removed by the development process, leaving the corresponding hole ring pattern. This step ensures that only the hole ring and its hole wall of the first through hole 1010 will be plated with a metal layer during the subsequent electroplating process.

[0049] As an alternative implementation, film can be applied to the already attached dry film 2030 and placed in an exposure machine for exposure. Afterward, the unexposed parts of the dry film 2030 are removed through a development process, leaving the corresponding hole ring pattern.

[0050] A protective film 2040 is then applied to the second side of the flash plating plate 10. In order to maintain the chemical balance in the electroplating tank and ensure the electroplating quality, the electroplating solution needs to be replaced or replenished regularly. A second through hole 2020 is made corresponding to the first through hole 1010 to form a flow channel for the electroplating solution. This ensures that the electroplating solution can smoothly enter and exit the first through hole 1010 to facilitate the exchange of solutions and is conducive to the formation of a good coating on the inner wall of the first through hole 1010.

[0051] The key to this step is that the second through-hole 2020 and the first through-hole 1010 are centered on the same hole. The diameter of the second through-hole 2020 is 1 / 3 to 1 / 2 smaller than the diameter of the first through-hole 1010, or even less than 10μm to 35μm on one side. This is to compensate for exposure errors. Due to certain errors in exposure accuracy, the dry film 2030 or protective film 2040 covering the surface forms a structure that extends into the hole, compensating for possible positional errors during exposure and ensuring that the edge of the hole wall is fully covered. On the other hand, when electroplating copper, if the dry film 2030 or protective film 2040 is designed exactly according to the actual size of the first through-hole 1010, copper may be deposited on the edge of the dry film 2030 or even above the board surface during electroplating. The excess copper deposited will be difficult to remove in subsequent processing. Therefore, making the diameter of the second through-hole 2020 smaller than the diameter of the first through-hole 1010 can limit the height of the electroplated copper layer, reduce the amount of copper protruding above the board surface, and facilitate subsequent processing and leveling operations.

[0052] In one embodiment, the protective film 2040 is also a dry film. The pattern plate 20 is made by attaching a dry film 2030 to both the first and second sides of the flash plate 10, and making a dry film pattern 2010 at the position corresponding to the hole ring pattern on the first side, and making a second through hole 2020 at the position corresponding to the first through hole 1010 on the second side. The second through hole 2020 is smaller on one side than the first through hole 1010, thus forming the pattern plate 20.

[0053] Furthermore, the dry film removal process 2030 in the subsequent steps uses a film stripping method, which is gentler than mechanical peeling and less likely to cause micro-cracks or other forms of physical damage. This avoids damage to the already formed circuit pattern and helps maintain the overall quality and reliability of the circuit board.

[0054] In one embodiment, the protective film 2040 is an insulating and corrosion-resistant protective film layer such as blue tape. The pattern board 20 is fabricated by attaching the dry film 2030 to the first side of the flash-plated plate 10, and fabricating a dry film pattern 2010 at the corresponding hole ring pattern position on the first side. Then, a PET film, PP film, acrylic film, polyimide film, epoxy resin film, or blue tape is attached to the second side, and a second through hole 2020 is fabricated corresponding to the first through hole 1010. The second through hole 2020 is smaller on one side than the first through hole 1010, thus forming the pattern board 20. The thickness of the protective film 2040 can optionally be from 10μm to 100μm.

[0055] Furthermore, the second through-hole 2020 is fabricated using a laser ablation method. If the protective film is made of PET film, PP film, acrylic film, polyimide film, epoxy resin film, or blue tape, it is not possible to create the protective film pattern using exposure and development methods. Therefore, laser ablation is preferred. A high-energy-density laser beam is used to locally heat the material to the evaporation temperature in a short time to form an ablation, thus creating the second through-hole 2020. This method is suitable for fabricating high-precision, small-sized second through-holes 2020. Alternatively, when the protective film 2040 is a dry film, laser ablation can also be used.

[0056] Furthermore, the protective film 2040 is removed in the subsequent process by peeling or alkaline washing.

[0057] Please see Figure 5 , Figure 5 This is a cross-sectional schematic diagram of the electroplated plate according to an embodiment of the present invention.

[0058] Step S30:

[0059] A copper layer 3010 and a tin layer 3020 are electroplated sequentially onto the graphic board 20 to form an electroplated board 30.

[0060] The function of the electroplated tin layer 3020 is to protect the electroplated copper layer from being etched in the subsequent etching step. In this embodiment, the thickness of the tin layer 3020 is 2μm to 10μm, preferably 5μm.

[0061] Furthermore, the electroplated copper layer 3010 is an additional 3μm to 8μm of copper thickness on the graphic board 20 according to the design, providing sufficient copper layer allowance for subsequent processes, compensating for the unavoidable copper layer loss during the micro-etching process in the later process, and ensuring that the copper thickness provided by the final circuit board meets the design requirements. Under normal circumstances, the copper thickness of the hole wall formed by electroplating is 15μm to 35μm. In this embodiment, the copper thickness of the hole wall formed by electroplating reaches 18μm to 43μm.

[0062] Please see Figure 6 and Figure 7 , Figure 6 This is a cross-sectional schematic diagram of the film-removing plate according to an embodiment of the present invention; Figure 7 This is a cross-sectional schematic diagram of the high-precision circuit board with a single-hole through-hole ring according to this embodiment.

[0063] Step S40:

[0064] Remove the dry film 2030 and protective film 2040 from the electroplated plate 30 to form the stripping plate 40. Then etch and remove the tin layer 3020. Perform micro-etching to form a high-precision circuit board 50 with through-hole single-sided hole ring.

[0065] Furthermore, micro-etching involves etching away 3μm to 8μm of copper thickness. That is, after removing the tin layer 3020, a chemical etching method is used to remove 3μm to 8μm of copper thickness. This complements the previous electroplating process, which involves an additional 3μm to 8μm of copper thickness. This not only helps to adjust to the required final copper layer 3010 thickness, but also refines the hole ring pattern, removes burrs, flash, and other undesirable copper layers from the hole edges, removes oxides and other impurities, and enhances the solderability and reliability of the circuit board.

[0066] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for manufacturing a high-precision circuit board with a single-sided through-hole hole ring, wherein one surface of the circuit board is designed with a hole ring pattern, characterized in that, The manufacturing method includes the following steps: S10: Take the copper-clad board, process it through the previous process to form a circuit board to be drilled with bright copper surfaces on both the top and bottom. Drill the first through hole and then flash plate it to form a flash plated board. S20: Apply a dry film to the first surface of the flash-plated plate, and fabricate a dry film pattern corresponding to the hole ring pattern. A protective film is applied to the second side, and a second through hole is made corresponding to the first through hole. The second through hole is smaller on one side than the first through hole, forming a graphic board. S30: Electroplating a copper layer and an electroplating tin layer onto the graphic board sequentially to form an electroplated board; S40: Remove the dry film and the protective film from the electroplated plate, then etch, and then remove the tin layer to form the circuit board.

2. The method for manufacturing a high-precision circuit board with a single-sided through-hole hole ring as described in claim 1, characterized in that, The flash plating is performed by electroplating at a current density of 3 ASF to 8 ASF for 20 to 30 minutes to form a copper thickness of 3 μm to 8 μm.

3. The method for manufacturing a high-precision circuit board with a single-sided through-hole hole ring as described in claim 1, characterized in that, The graphic plate is fabricated by applying a dry film to both the first and second sides of the flash-plated plate, fabricating the dry film pattern on the first side corresponding to the hole ring pattern position, and fabricating a second through hole on the second side corresponding to the first through hole position. The second through hole is smaller on one side than the first through hole, thus forming the graphic plate.

4. The method for manufacturing a high-precision circuit board with a single-sided through-hole hole ring as described in claim 3, characterized in that, The dry film is removed by a film stripping process.

5. The method for manufacturing a high-precision circuit board with a single-sided through-hole hole ring as described in claim 1, characterized in that, The graphic board is fabricated by attaching the dry film to the first side of the flash-plated plate and fabricating the dry film pattern at the position corresponding to the hole ring pattern on the first side. Then, a PET film, PP film, acrylic film, polyimide film, epoxy resin film, or blue tape is attached to the second side, and a second through hole is fabricated corresponding to the first through hole. The second through hole is smaller on one side than the first through hole, thus forming the graphic board.

6. A method for manufacturing a high-precision circuit board with a single-sided through-hole hole ring as described in claim 1 or 5, characterized in that, The protective film is removed by peeling or alkaline washing.

7. A method for manufacturing a high-precision circuit board with a single-sided through-hole hole ring as described in claim 1 or 3, characterized in that, The second through hole and the first through hole are at the same center, and the diameter of the second through hole is 1 / 3 to 1 / 2 smaller than the diameter of the first through hole.

8. A method for manufacturing a high-precision circuit board with a single-sided through-hole hole ring as described in claim 1 or 5, characterized in that, The second through hole is fabricated using a laser ablation method.

9. A method for manufacturing a high-precision circuit board with a single-sided through-hole hole ring as described in claim 1 or 3, characterized in that, The electroplated copper layer is an additional 3μm to 8μm of copper thickness electroplated onto the graphic board according to the design. The process of forming the circuit board also includes removing the tin layer and then performing micro-etching.

10. A method for manufacturing a high-precision circuit board with a single-sided through-hole hole ring as described in claim 9, characterized in that, The micro-etching refers to etching away a copper thickness of 3μm to 8μm.

Images