A method for making a graphic transfer

Abstract

The application provides a pattern transfer manufacturing method, and belongs to the technical field of PCBs. The pattern transfer manufacturing method comprises the following steps: obtaining a PCB substrate; pattern plating, plating a layer of tin on the surface of the substrate to form a protective layer; laser tin burning, removing part of the tin on the protective layer according to a first preset pattern to form a first pattern; etching, etching the copper layer exposed by the first pattern on the PCB substrate to complete the pattern transfer; film stripping, removing the protective layer remaining on the PCB substrate to form a second pattern; and drying, drying the PCB substrate after film stripping. Compared with the prior art, the pattern transfer manufacturing method provided by the application discards the traditional method of relying on dry film as an etching-resistant mask, instead uses the high bonding force between tin metal and the copper surface at the molecular level to form a strong protective layer, and through the efficient selective removal of the tin layer by carbon dioxide laser, directly defines the transfer pattern, and realizes high-precision pattern transfer.

Description

Technical Field

[0001] This application relates to the field of PCB technology, and in particular to a method for fabricating a pattern transfer. Background Technology

[0002] Due to the rapid development of PCB products, the requirements for circuit density in product design are constantly increasing. At the same time, the differences in interlayer design lead to lower board flatness after outer layer lamination. The main difficulty in making conventional PCB outer layer patterns lies in the firmness of pattern transfer film, which is related to the board flatness and the angle of circuit pattern design, especially for PCB substrates with high-density circuits and small circuit angles.

[0003] Traditional methods use a film-coating method for pattern transfer on the outer layer, which is prone to problems such as poor film adhesion, film peeling, residual adhesive on the board surface, and debris on the board surface leading to open circuits. In addition, the dry film is relatively soft and has a certain thickness, which places certain requirements on the flatness of the board surface and the circuit design.

[0004] In addition, the dry film has a certain thickness, which has a certain impact on the exchange of etching chemicals during pattern etching, thus affecting the accuracy of the circuit. 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 method for creating graphic transfer.

[0006] This application provides the following technical solution: a method for creating graphic transfer, comprising the following steps: Obtain the PCB substrate; Pattern plating involves plating a layer of tin onto the surface of the substrate to form a protective layer. Laser tin removal removes a portion of the tin from the protective layer according to a first preset pattern, forming the first pattern; Etching involves etching the copper layer exposed in the first pattern of the PCB substrate to complete the pattern transfer. The protective layer remaining on the PCB substrate is removed to form the second pattern; Drying: Dry the PCB substrate after removing the film.

[0007] In some embodiments of this application, a pretreatment is included before the pattern electroplating step, which removes stains from the PCB substrate surface by washing with water and acid.

[0008] In some embodiments of this application, obtaining the PCB substrate includes the steps of: obtaining a first copper layer, an inner layer, and a second copper layer; pressing the first copper layer onto the upper surface of the inner layer; and pressing the second copper layer onto the lower surface of the inner layer.

[0009] In some embodiments of this application, the step of electroplating a layer of tin on the surface of the PCB substrate includes: electroplating a layer of tin on the surface of the first copper layer to form a first protective layer; and electroplating a layer of tin on the surface of the second copper layer to form a second protective layer.

[0010] In some embodiments of this application, the thickness of both the first protective layer and the second protective layer is h, wherein the value of h is in the range of h≥3μm.

[0011] In some embodiments of this application, removing a portion of the tin from the protective layer according to the first preset pattern includes: performing laser tin burning on the first protective layer according to the first preset pattern to remove a portion of the tin from the first protective layer.

[0012] In some embodiments of this application, removing a portion of the tin from the protective layer according to the first preset pattern includes: performing laser tin burning on the second protective layer according to the first preset pattern to remove a portion of the tin from the second protective layer.

[0013] In some embodiments of this application, etching the copper layer exposed in the first pattern of the PCB substrate includes: etching away the first copper layer exposed from the first protective layer, and etching away the second copper layer exposed from the second protective layer.

[0014] In some embodiments of this application, removing the protective layer remaining on the PCB substrate includes: removing the first protective layer and the second protective layer.

[0015] In some embodiments of this application, the laser tin burning further includes the step of: performing unilateral pre-compensation based on the copper etching thickness compensation.

[0016] The embodiments of this application have the following advantages: Compared with the prior art, this application abandons the traditional method of relying on dry film as an anti-etching mask, and instead utilizes the high bonding force between tin metal and copper surface at the molecular level to form a robust protective layer, and uses a carbon dioxide laser to efficiently and selectively remove the tin layer, directly defining the transfer pattern. This architecture ensures the cleanliness and roughening of the copper surface through a pre-processing module, achieves dense deposition of the tin layer across the entire board through a pattern electroplating module, completes high-precision pattern engraving through a laser tin-burning module, and finally obtains the target copper circuit through an etching and tin-removal module. The entire process eliminates the obstruction of chemical exchange by the dry film thickness, fundamentally eliminates lateral etching, and enables the transfer of sharp-angle patterns with extremely small linewidths and spacings.

[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 a graphic transfer production 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] It should be noted that when PCB products have uneven surfaces after lamination due to differences in interlayer design, the dry film cannot completely fill and adhere to the recessed areas. This easily leads to poor adhesion or film peeling during the thermoforming stage. In subsequent processes, the seepage of etching chemicals into the bottom of the mask can cause residual adhesive and debris on the board surface, ultimately resulting in open circuits in the etched circuitry. Furthermore, for high-density circuitry and designs with small line angles, the physical thickness of the dry film can hinder the efficient exchange of fresh etching chemicals and reaction products during etching, exacerbating the lateral etching effect and severely limiting the etching precision of fine lines.

[0026] Based on this, such as Figure 1 As shown, some embodiments of this application provide a method for creating a graphic transfer, which includes the following steps: S100, Obtain the PCB substrate.

[0027] In this embodiment, obtaining the PCB substrate includes the following steps: obtaining a first copper layer, an inner layer, and a second copper layer; pressing the first copper layer onto the upper surface of the inner layer; and pressing the second copper layer onto the lower surface of the inner layer.

[0028] It should be noted that the first copper layer and the second copper layer respectively cover the inner layer.

[0029] In some embodiments, the thickness of the first copper layer is equal to the thickness of the second copper layer, and the projections of the first copper layer and the second copper layer onto the plane containing the inner layer coincide.

[0030] S200, pattern plating, involves plating a layer of tin onto the surface of a PCB substrate to form a protective layer.

[0031] In this process, a layer of tin is electroplated on the upper and lower surfaces of the PCB substrate in the thickness direction, thereby forming a protective layer on the surface of the PCB substrate.

[0032] Copper oxidizes very easily in the air, forming copper oxide or verdigris, which makes welding difficult.

[0033] Therefore, in this embodiment, a layer of tin is electroplated on the surface of the first copper layer and the surface of the second copper layer to form the protective layer.

[0034] Understandably, the tin layer is chemically stable, effectively isolating the copper layer from air and preventing oxidation, thus ensuring that the PCB substrate maintains good solderability during storage periods of several months. Furthermore, electroplating a layer of tin improves the surface flatness of the first and second copper layers in the PCB substrate, making it suitable for the soldering requirements of high-density, narrow-pitch surface mount technology.

[0035] In addition, the tin plating layer and the copper layer are bonded together by metal bonds, resulting in strong adhesion and making it less prone to bubbling or peeling off. This further improves the flatness of the PCB substrate surface and prevents warping.

[0036] Specifically, the PCB substrate is hung on a titanium electroplating rack, and the conductive areas of the board edge are clamped by fixtures. The rack and the PCB substrate are then vertically immersed into a tin plating bath. The PCB substrate is connected to the negative terminal (cathode) of the power supply, and the Sn² solution is applied. + Upon gaining electrons, it is reduced to metallic tin, which is deposited only on the surfaces of the exposed first copper layer and the second copper layer, forming the first tin layer (i.e., the first protective layer) and the second tin layer (i.e., the second protective layer), respectively.

[0037] Then, the PCB substrate with the first and second protective layers electroplated is taken out, rinsed with tap water overflow, and then rinsed with deionized water for a final rinse. Multiple tanks are used to thoroughly rinse the PCB substrate to completely remove the residual acidic tin plating solution.

[0038] Finally, the electroplated PCB substrate is dried by air drying, thus completing the tin plating process.

[0039] S300, laser tin burning, removes part of the tin from the protective layer according to the first preset pattern to form the first pattern.

[0040] Laser tin removal can precisely, at low temperature, efficiently, and reliably remove a portion of the tin corresponding to the first preset pattern on the conductive layer, improving the accuracy and efficiency of pattern preparation and enhancing the quality of PCB manufacturing.

[0041] It should be noted that in the tin plating process, a tin layer thickness greater than 3 micrometers is a critical process window. Its lower limit is set based on a balance of two factors: first, the tin layer must be free of pinholes and completely cover the microscopic peaks and valleys of the copper surface to resist etching solution penetration; second, it must provide sufficient energy absorbers for CO2 laser ablation to prevent laser penetration and damage to the underlying copper layer. If the tin thickness is less than 3 micrometers, protection failure during etching can easily lead to wire breakage, and laser ablation can also easily cause copper surface melting and sputtering.

[0042] Based on this, a selective removal mechanism was adopted during laser tin ablation, utilizing the significant difference in absorption rates between tin and copper to a 10.6-micron wavelength laser. Energy compensation was performed at corners by real-time adjustment of the laser pulse frequency and the moving speed of the scanning galvanometer, ensuring ablation precision at sharp corners of the pattern. Furthermore, throughout the entire process, the micro-etching depth of the pre-processing module was precisely controlled between 0.5 and 1.5 microns to ensure copper surface roughening while avoiding impact on subsequent tin layer coverage. This achieved high-precision closed-loop control from board cleaning and protective layer construction to pattern transfer.

[0043] S400, Etching, etches the copper layer exposed in the first pattern of the PCB substrate to complete the pattern transfer.

[0044] In this process, mechanical etching is used to etch the exposed first and second copper layers in the first pattern, thereby achieving pattern transfer.

[0045] S500, stripping, removes the protective layer remaining on the PCB substrate to form a second pattern.

[0046] In some embodiments, the etched PCB substrate is selectively dissolved in the tin stripping solution, and all the residual tin on the surface of the PCB substrate is dissolved in the tin stripping solution, which not only improves the tin stripping efficiency, but also does not damage the copper layer.

[0047] S600, drying, drying the PCB substrate after the film is removed.

[0048] In this embodiment, the PCB substrate after the film is removed is placed in a hot air circulating oven for drying, and after drying, the PCB substrate is taken out and allowed to cool naturally in a clean environment.

[0049] The pattern transfer fabrication method provided in this application involves electroplating tin on the surface of a PCB substrate and forming a protective layer on the surface of the PCB substrate. The tin and the copper layer on the surface of the PCB substrate are bonded together in molecular form to form a strong protective layer. This protective layer isolates the surface of the PCB substrate from oxygen and moisture, and can adapt to the roughness, flatness, and warpage of the PCB substrate surface, thereby improving the stability and quality of PCB manufacturing.

[0050] Compared to existing technologies, this application abandons the traditional method of relying on dry film as an etch-resistant mask. Instead, it utilizes the high molecular-level adhesion between tin metal and the copper surface to form a robust protective layer, and then uses a carbon dioxide laser to efficiently and selectively remove the tin layer, directly defining the transfer pattern. This architecture ensures copper surface cleanliness and roughening through a pre-processing module, achieves dense deposition of the entire board tin layer through a pattern plating module, completes high-precision patterning through a laser tin-burning module, and finally obtains the target copper circuitry through an etching and tin-removal module. The entire process eliminates the obstruction of chemical exchange caused by dry film thickness, fundamentally preventing lateral etching and enabling the transfer of sharp-angled patterns with extremely small linewidths and spacings.

[0051] like Figure 1 As shown, in some embodiments of this application, a pretreatment is further included before the pattern electroplating step, which removes stains from the PCB substrate surface by water washing and acid washing.

[0052] It should be noted that the pretreatment process removes fingerprints, oil, dust, and the thin oxide layer on the copper surface of the PCB substrate.

[0053] In some embodiments, dust, debris, and particulate contaminants on the surface of the PCB substrate are first rinsed off with water to reduce the introduction of solid impurities into the subsequent chemical bath; then, oil stains on the surface of the PCB substrate are removed with a PCB-specific alkaline degreasing agent; then, the PCB-specific alkaline degreasing agent on the surface of the PCB substrate is washed off with clean water; then, the oxide layer on the surface of the PCB substrate is removed by acid washing; finally, after the acidic substances on the surface of the PCB substrate are washed off with clean water, it is dried to obtain a clean PCB substrate.

[0054] By pre-treating the PCB substrate, the adhesion stability of the electroplated layer is ensured, ions are eliminated, leakage and corrosion are prevented, and the stability and reliability of the PCB substrate are guaranteed.

[0055] like Figure 1 As shown, in some embodiments of this application, the step of electroplating a layer of tin on the surface of the PCB substrate includes: electroplating a layer of tin on the surface of the first copper layer to form a first protective layer; and electroplating a layer of tin on the surface of the second copper layer to form a second protective layer.

[0056] It is understood that the protective layer includes a first protective layer and a second protective layer, which are stacked on opposite sides of the inner layer in the thickness direction.

[0057] In some embodiments of this application, the thickness of both the first protective layer and the second protective layer is h, wherein the value of h is in the range of h≥3μm.

[0058] It is understandable that the thickness of the first and second protective layers is equal to or greater than 3μm. By controlling the thickness of the protective layers, the flatness and stability of the protective layer surface can be ensured. At the same time, it provides support for the first and second copper layers and can also avoid the problem of abnormal etching patterns caused by poor film adhesion. In this way, it can improve the warping and flatness of the PCB substrate caused by the large difference in residual copper rate between the patterns and the film adhesion.

[0059] In this embodiment, a first protective layer is stacked on the surface of the first copper layer, and a second protective layer is stacked on the surface of the second copper layer. The first protective layer provides support and protection for the first copper layer, and the second protective layer provides support and protection for the second copper layer, thereby preventing warping at the edges of the first and second copper layers and ensuring the flatness of the PCB substrate surface.

[0060] It should be noted that in the existing technology, when the first preset pattern turning angle is ≤60°, etching is performed after the dry film is exposed. Since the dry film curing cannot achieve a high-precision and accurate acute angle, the actual pattern cannot achieve an extremely small acute angle pattern.

[0061] Based on this, such as Figure 1 As shown, in some embodiments of this application, removing a portion of the tin from the protective layer according to the first preset pattern includes: performing laser tin burning on the first protective layer according to the first preset pattern to remove a portion of the tin from the first protective layer.

[0062] Understandably, by using laser soldering and precise positioning with laser energy, the accuracy of the circuit can be improved, thereby enabling precise engraving on the first protective layer according to the first preset pattern.

[0063] It should be noted that the laser spot size can be made at the tens of micrometer level, which can burn only the tin in the specified location while leaving the rest of the area completely unaffected, thereby further improving precision.

[0064] Secondly, laser tin burning, a non-contact process, does not generate mechanical stress compared to mechanical etching, thus avoiding wear or scratches on the surface of the first copper layer and ensuring the precision of the fabrication.

[0065] In this embodiment, laser tin burning can improve the accuracy of pattern transfer. At the same time, the tin surface is smooth and hard during the etching process, which can effectively exchange chemicals and realize sharp-angled patterns.

[0066] like Figure 1 As shown, in some embodiments of this application, removing a portion of the tin from the protective layer according to the first preset pattern includes: performing laser tin burning on the second protective layer according to the first preset pattern to remove a portion of the tin from the second protective layer.

[0067] Understandably, by using laser soldering and precise positioning with laser energy, the accuracy of the circuit can be improved, thus allowing for accurate engraving on the second protective layer according to the first preset pattern.

[0068] Secondly, by using non-contact laser tin burning, wear or scratches on the surface of the second copper layer can be avoided, thus ensuring the precision of the fabrication.

[0069] like Figure 1 As shown, in some embodiments of this application, etching the copper layer exposed in the first pattern of the PCB substrate includes: etching away the first copper layer exposed from the first protective layer, and etching away the second copper layer exposed from the second protective layer.

[0070] The first and second copper layers are etched by mechanical etching.

[0071] In some embodiments of this application, removing the protective layer remaining on the PCB substrate includes: removing the first protective layer and the second protective layer.

[0072] In this embodiment, the etched PCB substrate is selectively dissolved in the solder stripping solution, and all the remaining first and second protective layers on the surface of the PCB substrate are dissolved in the solder stripping solution. This not only improves the solder stripping efficiency, but also avoids damaging the first and second copper layers.

[0073] It should be noted that the tin stripping solution is an acidic chemical solution that can selectively dissolve metallic tin. With the help of copper corrosion inhibitors, it can prevent corrosion of the first and second copper layers, thus ensuring the quality of tin stripping while maintaining the integrity of the first and second copper layers.

[0074] In some embodiments of this application, the laser tin burning further includes the step of: performing unilateral pre-compensation based on the copper etching thickness compensation.

[0075] In this embodiment, the tin-plated board is placed on the working platform of the laser tin-burning module. The computer-aided manufacturing system converts the coordinates of non-graphic areas in the circuit graphic data into a laser scanning path. The carbon dioxide laser operates with adjustable parameters, with a pulse frequency adjustment range of 40 kHz to 80 kHz and an average output power that is continuously adjustable between 8 and 20 watts. The galvanometer system drives the spot to scan at a speed of 800 to 2000 mm per second, precisely ablating the tin layer in the non-graphic areas according to the path. The specific parameters are matched according to the tin layer thickness and the required ablation precision.

[0076] For example, for a 3.5-micron tin layer, a frequency of 50 kHz, a power of 12 watts, and a scanning speed of 1000 mm / s are preferred. The laser energy is efficiently absorbed by the tin layer and instantly vaporized, while the underlying copper surface remains intact due to its high reflectivity to a wavelength of 10.6 microns. This allows the copper surface area to be etched to be defined while removing the tin layer, thus achieving maskless pattern transfer.

[0077] Secondly, a single-sided pre-compensation micrometer is superimposed on the standard linewidth to finally generate the laser ablation path (the linewidth of the etching process should be slightly larger than the actual linewidth). The copper thickness is 18μm and compensated by 1mil, 35μm and compensated by 1.5mil, and 45μm and compensated by 2mil.

[0078] For example, if the line width is 4mil and the copper etching thickness is 18μm, then pre-compensation is performed. The actual production data design line width is 5mil. Pre-compensation is used to make up for the deviation caused by the etching of the pattern after tin burning.

[0079] 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.

[0080] 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.

[0081] 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 method for creating a graphic transfer, characterized in that, Including the following steps: Obtain the PCB substrate; Pattern electroplating involves electroplating a layer of tin onto the surface of the PCB substrate to form a protective layer. Laser tin removal removes a portion of the tin from the protective layer according to a first preset pattern, forming the first pattern; Etching involves etching the copper layer exposed in the first pattern of the PCB substrate to complete the pattern transfer. The protective layer remaining on the PCB substrate is removed to form the second pattern; Drying: Dry the PCB substrate after removing the film.

2. The graphic transfer method according to claim 1, characterized in that, The process includes a pretreatment step before the pattern electroplating step, which removes stains from the PCB substrate surface by washing with water and acid.

3. The graphic transfer method according to claim 1, characterized in that, The process of obtaining the PCB substrate includes the following steps: obtaining a first copper layer, an inner layer, and a second copper layer; pressing the first copper layer onto the upper surface of the inner layer; and pressing the second copper layer onto the lower surface of the inner layer.

4. The graphic transfer method according to claim 3, characterized in that, The step of electroplating a layer of tin on the surface of the PCB substrate includes: electroplating a layer of tin on the surface of the first copper layer to form a first protective layer; and electroplating a layer of tin on the surface of the second copper layer to form a second protective layer.

5. The graphic transfer method according to claim 4, characterized in that, The thickness of both the first protective layer and the second protective layer is h, where the value of h is in the range of h≥3μm.

6. The graphic transfer method according to claim 4, characterized in that, The step of removing a portion of the tin from the protective layer according to the first preset pattern includes: performing laser tin burning on the first protective layer according to the first preset pattern to remove a portion of the tin from the first protective layer.

7. The graphic transfer method according to claim 4, characterized in that, The step of removing a portion of the tin from the protective layer according to the first preset pattern includes: performing laser tin burning on the second protective layer according to the first preset pattern to remove a portion of the tin from the second protective layer.

8. The graphic transfer method according to claim 4, characterized in that, The etching of the copper layer exposed in the first pattern of the PCB substrate includes: etching away the first copper layer exposed from the first protective layer, and etching away the second copper layer exposed from the second protective layer.

9. The graphic transfer method according to claim 4, characterized in that, The removal of the protective layer remaining on the PCB substrate includes: removing the first protective layer and the second protective layer.

10. The graphic transfer method according to claim 1, characterized in that, The laser tin burning process also includes the step of performing unilateral pre-compensation based on the copper etching thickness compensation.

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