A PCB etching method
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-10
- Publication Date
- 2026-08-14
AI Technical Summary
[0004]在采用湿膜覆盖金手指区域和引线区域的过程中，由于湿膜具有流动性，湿膜面积大，不仅存在褪膜困难、易残留的问题，而且会浪费大量油墨
[0016]本申请的实施例具有如下优点：本申请提供的PCB蚀刻方法，通过在PCS单元内的预设区域丝印湿膜，通过预制挡网能够对油墨进行导流和限位的作用，从而控制湿膜用量，不仅能够降低成本，而且褪膜残留风险大幅降低，有效解决PTH孔口渗蚀问题，推升产品的良品率，还能够减少后续阻焊前的清洁工序。
Smart Images
Figure CN122579484A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of circuit board processing technology, and in particular to a PCB etching method. Background Technology
[0002] Gold fingers (or edge connectors) are a row of gold-colored conductive contacts found on computer memory modules and graphics cards. In the circuit board design and manufacturing industry, gold fingers serve as the interface for external connections to the circuit board.
[0003] In the fabrication of gold fingers on circuit boards, a wet film is typically used to cover the lead area. The gold finger area contains multiple gold finger precursors, and the lead area contains multiple leads connected to the gold finger precursors. The leads are then energized and electroplated to deposit gold onto the gold finger precursors, thus obtaining the gold fingers. Finally, the leads are removed by etching.
[0004] When using wet film to cover the gold finger area and lead wire area, the wet film has fluidity and a large area, which not only makes it difficult to remove and leaves residue, but also wastes a lot of ink. Summary of the Invention
[0005] In view of this, the purpose of this application is to overcome the shortcomings of the prior art and provide a PCB etching method.
[0006] This application provides the following technical solution: a PCB etching method, comprising: Obtain the PCB board and prefabricated retaining mesh; Screen printing with a prefabricated screen is used to screen print a wet film in a preset area within the PCS unit. Wet film exposure and development: The first exposure film is placed on the wet film, and the wet film area covered by the first exposure film is removed by development; Apply dry film: Apply dry film to the PCB board and cover the copper surface to be protected; Second exposure and development: The second exposure film is placed on the surface of the dry film. After the second exposure and development, the lead area to be etched is exposed. Remove the leads by removing the lead areas exposed by secondary exposure and development through a double windowing process using both dry and wet films. De-filming, removing both dry and wet film; Solder resist.
[0007] In some embodiments, the PCS unit includes leads, electroplated through-holes, and an area to be screen-printed.
[0008] In some embodiments, the screen printing of the screen barrier further includes the step of screen printing a prefabricated screen barrier on the lead wire, the electroplated through hole and the area to be screen printed.
[0009] In some embodiments, the wet film exposure and development further includes the step of: covering the lead wire with a strip of wet film along the path direction of the lead wire.
[0010] In some embodiments, covering the lead wire with the strip wet film along the path direction of the lead wire further includes extending the edges of the strip wet film on the two opposite sides of the lead wire by at least 100 μm along the width direction of the lead wire.
[0011] In some embodiments, the wet film exposure and development further includes the step of: reserving a wet film ring of a predetermined width at the edge of the opening of the electroplated through hole.
[0012] In some embodiments, the width of the wet film ring is equal to or greater than 0.5 mm.
[0013] In some embodiments, the dry film application further includes the step of: attaching the dry film to the hole wall of the electroplated through hole and covering the hole wall of the electroplated through hole.
[0014] In some embodiments, the film removal process further includes the step of simultaneously removing the dry film and the wet film using a film removal solution.
[0015] In some embodiments, the step of removing the gold plating film is included before the screen printing.
[0016] The embodiments of this application have the following advantages: The PCB etching method provided by this application screen prints wet film in a preset area within the PCS unit. The prefabricated baffle can guide and limit the ink flow, thereby controlling the amount of wet film used. This not only reduces costs but also significantly reduces the risk of film peeling residue, effectively solves the problem of PTH orifice corrosion, improves the product yield, and reduces the cleaning process before subsequent solder resist.
[0017] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description
[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 A flowchart illustrating one perspective of a PCB etching method provided by some embodiments of this application is shown. Detailed Implementation
[0020] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.
[0021] It should be noted that when an element is said to be "fixed" to another element, it can be directly on the other element or there may be an intervening element. When an element is said to be "connected" to another element, it can be directly connected to the other element or there may be an intervening element. Conversely, when an element is said to be "directly" on another element, there is no intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.
[0022] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.
[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the template description is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0025] like Figure 1 As shown, some embodiments of this application provide a PCB etching method, which is mainly used to solve the problem of PTH orifice erosion, reduce the cleaning process before subsequent solder mask, reduce the amount of wet film used and the amount of film removed, reduce production costs, and improve product yield.
[0026] In this embodiment, the PCB etching method includes: Step S100: Obtain the PCB board and the prefabricated mesh.
[0027] It should be noted that prefabricated screen protectors refer to the screen protector structure that is set up in the area to be screen protected as needed before the screen protector screen printing step.
[0028] Step S200, screen printing with a prefabricated screen, using a prefabricated screen to screen print a wet film in a preset area within the PCS unit.
[0029] It should be noted that a PCS unit refers to a single finished unit in a PCB board.
[0030] By screen printing wet film in a preset area within the PCS unit, the ink can be guided and limited by the baffle, effectively preventing ink from covering areas such as broken edges and test points, thus saving 30%-40% of ink.
[0031] Step S300, wet film exposure and development: the first exposure film is placed on the wet film, and the wet film area covered by the first exposure film is removed by development.
[0032] In this embodiment, the wet film is a liquid UV photoresist. The first exposure film is irradiated with 365nm ultraviolet light (parallel exposure machine film / LDI laser), causing the wet film in the light-transmitting area of the first exposure film to undergo photocrosslinking and curing, forming an alkali-resistant protective film. The wet film in the light-shielding area of the first exposure film does not react, so that the wet film area covered by the first exposure film can be removed by development.
[0033] Step S400: Apply dry film. Apply dry film to the PCB board and cover the copper surface to be protected.
[0034] It should be noted that a uniform solid photomask is pressed onto the entire PCB board surface for circuit pattern transfer, and subsequent exposure, development, and etching are used to create precision copper lines.
[0035] Understandably, by covering the copper surface to be protected with a dry film to form a uniform resist mask, preparation is made for the exposure and transfer of precision circuit patterns.
[0036] Step S500, Second exposure and development: The second exposure film is placed on the surface of the dry film. After the second exposure and development, the lead area to be etched is exposed.
[0037] In this embodiment, the second exposure film is irradiated with 365nm ultraviolet light (parallel exposure machine film / LDI laser) to cause photocrosslinking and curing of the wet film in the light-transmitting area of the second exposure film, forming an alkali-resistant and electroplating-resistant protective film. The wet film in the light-shielding area of the second exposure film does not react, so that the dry film area covered by the second exposure film can be removed by development.
[0038] Specifically, after secondary exposure and development, the lead area to be etched is exposed, thereby obtaining the desired exposed lead circuit pattern.
[0039] Step S600: Remove the leads by removing the lead area to be etched exposed by secondary exposure and development through double windowing of dry film and wet film.
[0040] It should be noted that wet film has the advantages of liquid ink fluidity and solid hot-pressed film, uniform thickness, high resolution, and the ability to create ultra-fine lines below 20μm. By using wet film to fill in gaps and level the surface, and dry film to handle high-precision routing, the two layers work together to create windows, balancing flatness and pattern accuracy. This double windowing allows for precise removal of the lead areas to be etched.
[0041] In this embodiment, the copper layer of the leads is removed by an alkaline etching solution.
[0042] Step S700: Demold the film, removing the dry and wet films.
[0043] In this embodiment, the cured dry and wet films are completely dissolved and removed using a film stripping solution.
[0044] Step S800, solder resist.
[0045] After the leads are removed, a layer of UV-sensitive insulating ink is applied to the bare copper area of the PCB surface to form an insulating layer, preventing short circuits between adjacent copper lines. This also protects the copper traces from oxidation or scratches.
[0046] It should be noted that the PCB etching method provided in this application screen prints wet film in a preset area within the PCS unit. The prefabricated baffle can guide and limit the ink flow, thereby controlling the amount of wet film used. This not only reduces costs but also significantly reduces the risk of film peeling residue, effectively solving the problem of PTH orifice corrosion, increasing the product yield, and reducing the cleaning process before subsequent solder resist application.
[0047] In some embodiments of this application, the wet film can also be produced by spraying or jet printing, and the accuracy can be further improved by using an automatic alignment system.
[0048] In some embodiments of this application, the PCS unit includes leads, electroplated through holes, and areas to be screen-printed.
[0049] In some embodiments of this application, the screen printing of the screen barrier further includes the step of screen printing a prefabricated screen barrier on the lead wire, the electroplated through hole and the area to be screen printed.
[0050] In this embodiment, solid photosensitive adhesive dots are made at each electroplated through-hole location to block the hole opening during printing and prevent green solder mask from filling the hole. Through CCD alignment, each solid dot of the baffle is precisely aligned with the upper and lower openings of each electroplated through-hole. Additionally, by setting baffles at the edges of the leads, the gold plating solution is isolated, preventing gold plating onto the leads and avoiding residual copper buildup during etching. This precisely defines the boundary between the gold fingers and the leads, preventing gold plating from spreading to the lead edges and creating gold burrs, thus protecting the effective circuitry. During etching, the edges of the gold fingers are not damaged, facilitating thorough removal of the leads during subsequent etching.
[0051] In some embodiments of this application, the wet film exposure and development further includes the step of: covering the lead wire with a strip-shaped wet film along the path direction of the lead wire.
[0052] It is understood that this application controls the amount of wet film used to reduce the manufacturing cost of the PCB board by covering the lead wire with a strip-shaped wet film along the lead wire path direction, thereby forming an isolation and protective layer on the surface of the lead wire.
[0053] In some embodiments of this application, the wet film exposure and development further includes the step of: reserving a wet film ring of a predetermined width at the edge of the opening of the electroplated through hole.
[0054] It should be noted that a wet film ring of a predetermined width is reserved at the edge of the electroplated through hole to prevent the dry film from wrinkling.
[0055] In some embodiments of this application, the step of applying the dry film further includes: attaching the dry film to the hole wall of the electroplated through hole and covering the hole wall of the electroplated through hole.
[0056] It should be noted that a dry film is attached to the wall of the electroplated through hole to provide protection for the copper surface of the inner wall of the through hole.
[0057] In this embodiment, a wet film is used to fill the unevenness around the electroplating through hole, and then a dry film is applied to cover the electroplating through hole. During the second exposure, the film at the location of the electroplating through hole is exposed to light, and the UV light causes the dry film on the surface of the hole opening and hole wall to solidify and adhere, thereby achieving the sealing of the electroplating through hole wall and preventing the electroplating solution from entering the hole.
[0058] In some embodiments of this application, the step of covering the lead wire with the strip-shaped wet film along the path direction of the lead wire further includes: extending the edges of the two opposite sides of the strip-shaped wet film along the width direction of the lead wire by at least 100 μm.
[0059] It should be noted that, in this embodiment, during the process of covering the lead wire along the path direction of the lead wire, the strip wet film extends along the width direction of the lead wire, so that the wet film extends at least 100μm along the width direction of the lead wire, so as to further ensure that the wet film can completely cover the lead wire, and at the same time, it can effectively control the amount of wet film used, reduce the area of the wet film used, and thus reduce costs.
[0060] In this embodiment, the strip-shaped wet film extends 100 μm from the edges of the two opposite sides along the width direction of the lead wire.
[0061] In some embodiments of this application, the film removal further includes the step of simultaneously removing the dry film and the wet film using a film removal solution.
[0062] The stripping solution can be a sodium hydroxide solution or a potassium hydroxide solution.
[0063] In some embodiments of this application, the step of removing the gold plating film is included before the screen printing.
[0064] It should be noted that gold plating removal refers to: covering the conductive leads on the PCB board with a wet or dry film, leaving only a window to expose the gold fingers for nickel-gold plating; after the gold plating is completed, this wet film is removed with an inorganic strong alkaline removal solution, and then the leads are etched away.
[0065] It is understood that in this embodiment, a wet film covers the conductive leads before gold plating, with only a window exposed to expose the gold fingers; gold plating only occurs on the gold fingers, and the leads have no gold layer, so the leads can be completely removed during etching, without gold burrs or residual copper.
[0066] In some embodiments of this application, the width of the wet film ring is equal to or greater than 0.5 mm.
[0067] It should be noted that by reserving a wet film ring of not less than 0.5mm around the opening of the electroplated through hole, and by controlling the width of the wet film ring, the amount of wet film used can be reduced, thereby preventing corrosion caused by dry film wrinkling and reducing costs.
[0068] In this embodiment, the width of the wet film ring is 0.5 mm.
[0069] In all examples shown and described herein, any specific values should be interpreted as merely exemplary and not as limitations; therefore, other examples of exemplary embodiments may have different values.
[0070] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0071] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application.
Claims
1. A PCB etching method, characterized in that, include: Obtain the PCB board and prefabricated retaining mesh; Screen printing with a prefabricated screen is used to screen print a wet film in a preset area within the PCS unit. Wet film exposure and development: The first exposure film is placed on the wet film, and the wet film area covered by the first exposure film is removed by development; Apply dry film: Apply dry film to the PCB board and cover the copper surface to be protected; Second exposure and development: The second exposure film is placed on the surface of the dry film. After the second exposure and development, the lead area to be etched is exposed. Remove the leads by removing the lead areas exposed by secondary exposure and development through a double windowing process using both dry and wet films. De-filming, removing both dry and wet film; Solder resist.
2. The PCB etching method according to claim 1, characterized in that, The PCS unit includes leads, electroplated through holes, and an area to be screen-printed.
3. The PCB etching method according to claim 2, characterized in that, The screen printing of the screen also includes the step of screen printing a prefabricated screen on the lead wire, the electroplated through hole and the area to be screen printed.
4. The PCB etching method according to claim 1, characterized in that, The wet film exposure and development also includes the step of covering the lead wire with a strip of wet film along the path direction of the lead wire.
5. The PCB etching method according to claim 4, characterized in that, The step of covering the lead wire with the strip-shaped wet film along the path direction of the lead wire further includes: extending the edges of the two opposite sides of the strip-shaped wet film by at least 100 μm along the width direction of the lead wire.
6. The PCB etching method according to claim 1, characterized in that, The wet film exposure and development process also includes the step of: reserving a wet film ring of a preset width at the edge of the opening of the electroplated through hole.
7. The PCB etching method according to claim 6, characterized in that, The width of the wet film ring is equal to or greater than 0.5 mm.
8. The PCB etching method according to claim 1, characterized in that, The dry film application process further includes the step of: attaching a dry film to the wall of the electroplated through hole and covering the wall of the electroplated through hole.
9. The PCB etching method according to claim 1, characterized in that, The film removal process also includes the step of using a film removal solution to remove both the dry and wet films simultaneously.
10. The PCB etching method according to claim 1, characterized in that, The process before screen printing includes a step of removing the gold plating film.