A method for improving etching yield of outer layer circuit of PCB, PCB and preparation method thereof

Abstract

The application discloses a method for improving etching yield of outer layer circuit of a PCB (Printed Circuit Board), the PCB and a preparation method thereof, and relates to the technical field of PCB manufacturing. The method is characterized in that after the PCB is subjected to membrane stripping, the PCB is subjected to preliminary water washing, mild etching treatment, final water washing and drying. The mild etching treatment is to immerse the PCB subjected to preliminary water washing in an acid etching solution or contact the acid etching solution through spraying, so as to dissolve the copper layer on the PCB. The method divides the traditional water washing into preliminary water washing and final water washing, and inserts the mild etching treatment between the preliminary water washing and the final water washing. Before the oxidation layer and the residual organic matter are completely stable, the mild etching treatment realizes immediate intervention and in-situ removal, avoids the hysteresis and secondary pollution of the traditional post-treatment, and improves the etching yield of the outer layer circuit of the PCB.

Description

Technical Field

[0001] This invention relates to the field of PCB manufacturing technology, specifically to a method for improving the etching yield of outer layer circuits in PCBs, and to a PCB and its preparation method. Background Technology

[0002] A PCB, or printed circuit board, is the support and electrical connection carrier for electronic components. It is known as the "mother of electronic products." By laying conductive copper foil lines on an insulating substrate using processes such as printing and etching, it provides precise soldering positions for various components such as resistors and chips, and realizes complex circuit connections between them. As an indispensable core component of modern electronic devices, PCBs can highly integrate complex circuit systems in a compact space, ensuring the stability and reliability of electronic products and enabling mass production.

[0003] In PCB manufacturing, the standard process is: pretreatment → lamination → exposure → development → etching → stripping → washing and drying. However, in actual production, the board surface often exhibits the following problems after the stripping process:

[0004] 1. Residual resist layer: Alkaline stripping solutions are difficult to completely remove the bonding layer between the resist and the copper surface, especially the organic residue on the sidewalls of the circuit and intricate circuit components.

[0005] 2. Surface passivation / oxidation: Fresh copper surfaces after film removal are highly susceptible to oxidation in air or during water washing, forming a very thin oxide layer. This oxide layer can affect the adhesion and reliability of subsequent processes (such as hindering pretreatment, gold plating, tin immersion, and browning of subsequent overlays).

[0006] 3. Microscopic contamination: There may be trace amounts of drug crystals or adsorption of pollutants. Summary of the Invention

[0007] Current PCB manufacturing methods suffer from issues such as resist residue, easy oxidation of copper surfaces, and trace amounts of chemical crystallization or contaminant adsorption. The purpose of this invention is to provide a method for improving the etching yield of the outer layer circuitry of a PCB, as well as the PCB itself and its preparation method. By performing gentle micro-etching after resist removal, "instant intervention and in-situ removal" are achieved before the oxide layer and residual organic matter are fully stabilized, thoroughly removing organic residues and chemical oxide layers, and avoiding the lag and secondary pollution of post-processing.

[0008] This invention is achieved through the following technical solution:

[0009] In one aspect, this application provides a method for improving the etching yield of the outer layer circuits of a PCB circuit board. The method involves first washing the PCB circuit board after the film removal process with water, then performing a mild micro-etching process, followed by washing and drying again. The mild micro-etching process involves immersing the PCB board after the initial water wash into or spraying it with an acidic micro-etching working solution to dissolve the copper layer on the PCB board.

[0010] This invention divides traditional water washing into preliminary water washing and final water washing, and embeds a mild micro-etching process between the preliminary water washing and the final water washing. Before the oxide layer and residual organic matter are fully stabilized, it achieves "instant intervention and in-situ removal", avoiding the lag and secondary pollution of traditional post-processing, and improving the etching yield of the outer layer of PCB circuit boards.

[0011] This processing method requires the introduction of an online micro-etching tank, directly integrated between the existing film removal line and washing section. No production line reconstruction is necessary; mass production can be achieved through modular modification. This micro-etching tank must be resistant to acid and alkali corrosion (e.g., PP, PVDF materials). It is equipped with a circulating filtration system for the acidic micro-etching working solution, a precise temperature control system, an automatic concentration replenishment system, a sealing cover and exhaust system, and a conveying system. This achieves closed-loop control of all parameters in the micro-etching process, ensuring consistent processing for products of different plate types and line widths. The circulating filtration system maintains a uniform, particle-free solution. The precise temperature control system maintains a stable solution temperature. The automatic concentration replenishment system monitors and replenishes the main acid and oxidant in real time. The sealing cover and exhaust system prevents solution evaporation and diffusion. The conveying system ensures smooth plate transport and avoids plate jamming.

[0012] During the mild micro-etching process, the concentration of copper ions in the acidic micro-etching working solution is controlled below 30 g / L to ensure uniformity of micro-etching.

[0013] Furthermore, the acidic micro-etching working solution comprises a mixture of sulfuric acid and an oxidant with a concentration of 5-15% v / v.

[0014] The acidic micro-etching working solution of this invention can dissolve extremely thin copper layers (approximately 0.1~0.5 micrometers) while also possessing a weak oxidative decomposition ability against organic residues. Sulfuric acid is used to provide the acidic environment. The oxidant concentration is much lower than that of the previous etching solution, serving only to maintain uniform and gentle dissolution of the copper.

[0015] Further, the oxidant is hydrogen peroxide with a concentration of 1-5% v / v or persulfate with a concentration of 10-50 g / L. The persulfate includes sodium persulfate.

[0016] Furthermore, the acidic micro-etching working solution also includes a copper ion complexing agent at a concentration of 0.5-2% v / v and / or a slow-release agent at a concentration of 10-100 ppm. The corrosion inhibitor is used to control lateral corrosion. A surfactant may also be added to improve wettability.

[0017] Furthermore, the copper ion complexing agent includes citric acid.

[0018] Furthermore, the corrosion inhibitor includes benzotriazole.

[0019] Furthermore, the micro-etching rate is controlled at 0.1~0.5 μm / min, and the processing time is 15~30 seconds. The micro-etching rate is controlled to ensure that only the oxide and contaminant layers are removed, with minimal impact on the line width. The processing time is controlled because too short a time will result in poor treatment effects, while too long a time may lead to excessive side etching or copper thickness loss.

[0020] Furthermore, the temperature of the acidic micro-etching working solution used for micro-etching is controlled at 30~35℃. Temperature control is implemented to prevent excessively high temperatures from causing the reaction to become too rapid and difficult to control.

[0021] Secondly, this application provides a method for manufacturing a PCB circuit board, comprising the following steps:

[0022] Pre-treatment: Roughening the incoming PCB board to remove contaminants from the PCB board surface and increase the surface roughness;

[0023] Lamination: Applying dry film to the surface of a PCB board after pretreatment;

[0024] Exposure: The dry film attached to the PCB surface is photopolymerized by ultraviolet irradiation to form a stable structure that adheres to the PCB surface and blocks etching;

[0025] Development: The dry film that has not undergone polymerization on the PCB board surface is developed away, while the dry film that has undergone polymerization remains on the PCB board surface;

[0026] Etching: The process of etching the areas of the PCB board that are not covered with dry film to create circuitry.

[0027] Removal: Removing the resist pattern from the surface of a PCB board after the outer layer circuitry has been etched;

[0028] Preliminary water washing: Use clean water to spray or soak the PCB board surface after film removal to remove the film removal solution;

[0029] Mild micro-etching treatment: Immerse the PCB board, which has been preliminarily washed with water, into or spray it with an acidic micro-etching working solution to dissolve the copper layer on the PCB board.

[0030] Final rinse: The PCB board that has undergone mild micro-etching is immediately and thoroughly rinsed with clean water; this usually includes multi-stage countercurrent rinsing.

[0031] Drying: Dry the cleaned PCB board.

[0032] Thirdly, this application provides a PCB circuit board, which is prepared using the above-described preparation method.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] (1) The present invention divides the traditional water washing into preliminary water washing and final water washing, and embeds a mild micro-etching treatment between the preliminary water washing and the final water washing. Before the oxide layer and residual organic matter are completely stable, it achieves "instant intervention and in-situ removal", avoiding the lag and secondary pollution of traditional post-processing, and improving the etching yield of the outer layer of PCB circuit board.

[0035] (2) The present invention significantly improves the surface cleanliness and activity of PCB circuit boards: through gentle micro-etching treatment, organic residues and chemical oxide layers that cannot be removed by conventional cleaning can be completely removed, resulting in a fresh and highly active copper surface.

[0036] (3) The present invention improves the bonding strength of subsequent processes, provides a more ideal and consistent substrate for solder resist ink coating and surface treatment (electroplating / immersion tin / OSP, etc.), and significantly improves adhesion, solderability and anti-aging performance.

[0037] (4) This invention improves product yield and reliability, and effectively solves the hidden defects caused by poor surface condition after film removal, which is especially important for the production of high reliability and high density PCB products.

[0038] (5) The apparatus used in the method of the present invention is easy to integrate and can be directly modified and added to the existing production line. The micro-etching solution has a simple composition and low consumption, and the overall operating cost increases only slightly, resulting in significant benefits.

[0039] (6) The process of this invention is controllable and the quality is stable. By controlling the micro-etching rate and time, a stable copper surface treatment effect can be achieved. It is highly adaptable to products with different board types and line widths. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered 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. In the drawings:

[0041] Figure 1 This is a flowchart illustrating the manufacturing process of a PCB circuit board according to an embodiment of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0043] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0044] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those different embodiments or examples.

[0045] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0046] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0047] Example 1

[0048] This embodiment provides a method for manufacturing a PCB circuit board, referring to... Figure 1 The specific preparation method is as follows:

[0049] S1. Pre-treatment: Roughen the incoming PCB board to remove contaminants from the PCB board surface and increase the surface roughness;

[0050] S2, lamination: Applying dry film to the surface of the PCB board after pretreatment;

[0051] S3, Exposure: The dry film attached to the PCB surface is irradiated with ultraviolet light to trigger a photopolymerization reaction to form a stable structure, which is attached to the PCB surface to block etching;

[0052] S4. Development: The dry film that has not undergone polymerization on the PCB board surface is developed away, while the dry film that has undergone polymerization remains on the PCB board surface.

[0053] S5. Etching: Etching the areas of the PCB board surface that are not covered with dry film to create circuitry.

[0054] S6. Removal: Remove the resist pattern from the surface of the PCB board after the outer layer circuit etching is completed;

[0055] S7. Preliminary water washing: Soak and wash the PCB board surface with clean water to remove the stripping solution;

[0056] S8. Mild micro-etching treatment: The PCB board, which has undergone preliminary water washing, is immersed in an acidic micro-etching working solution. The temperature of the micro-etching working solution is controlled at 30℃, the micro-etching rate is controlled at 0.1μm / min, and the treatment time is about 30 seconds. The mild micro-etching treatment dissolves the copper layer on the PCB board. The acidic micro-etching working solution is a mixture of 10L of 10% v / v sulfuric acid (98% sulfuric acid) and 9L of 3% v / v hydrogen peroxide (35% hydrogen peroxide).

[0057] S9. Final rinse: The PCB board that has undergone mild micro-etching is immediately and thoroughly rinsed with clean water; this usually includes multi-stage countercurrent rinsing.

[0058] S10. Drying: Dry the cleaned PCB board.

[0059] Example 2

[0060] This embodiment provides a method for preparing a PCB circuit board. Compared with Embodiment 1, the micro-etching working solution used in this embodiment for mild micro-etching is different. The concentration of sulfuric acid in the micro-etching working solution in this embodiment is 5% v / v, and the concentration of hydrogen peroxide is 1% v / v. Other process conditions are the same as in Embodiment 1.

[0061] The specific preparation method is as follows:

[0062] S1. Pre-treatment: Roughen the incoming PCB board to remove contaminants from the PCB board surface and increase the surface roughness;

[0063] S2, lamination: Applying dry film to the surface of the PCB board after pretreatment;

[0064] S3, Exposure: The dry film attached to the PCB surface is irradiated with ultraviolet light to trigger a photopolymerization reaction to form a stable structure, which is attached to the PCB surface to block etching;

[0065] S4. Development: The dry film that has not undergone polymerization on the PCB board surface is developed away, while the dry film that has undergone polymerization remains on the PCB board surface.

[0066] S5. Etching: Etching the areas of the PCB board surface that are not covered with dry film to create circuitry.

[0067] S6. Removal: Remove the resist pattern from the surface of the PCB board after the outer layer circuit etching is completed;

[0068] S7. Preliminary water washing: Soak and wash the PCB board surface with clean water to remove the stripping solution;

[0069] S8. Mild micro-etching treatment: Immerse the PCB board, which has undergone preliminary water washing, in an acidic micro-etching working solution. The temperature of the micro-etching working solution is controlled at 30℃, the micro-etching rate is controlled at 0.1μm / min, and the treatment time is 30 seconds to dissolve the copper layer on the PCB board. The acidic micro-etching working solution is a mixture of 10L of 5% v / v sulfuric acid (98% sulfuric acid) and 9L of 1% v / v hydrogen peroxide (35% hydrogen peroxide).

[0070] S9. Final rinse: The PCB board that has undergone mild micro-etching is immediately and thoroughly rinsed with clean water; this usually includes multi-stage countercurrent rinsing.

[0071] S10. Drying: Dry the cleaned PCB board.

[0072] Example 3

[0073] This embodiment provides a method for preparing a PCB circuit board. Compared with Embodiment 1, the micro-etching working solution used in this embodiment for mild micro-etching is different. The concentration of sulfuric acid in the micro-etching working solution in this embodiment is 15% v / v, and the concentration of hydrogen peroxide is 5% v / v. Other process conditions are the same as in Embodiment 1.

[0074] The specific preparation method is as follows:

[0075] S1. Pre-treatment: Roughen the incoming PCB board to remove contaminants from the PCB board surface and increase the surface roughness;

[0076] S2, lamination: Applying dry film to the surface of the PCB board after pretreatment;

[0077] S3, Exposure: The dry film attached to the PCB surface is irradiated with ultraviolet light to trigger a photopolymerization reaction to form a stable structure, which is attached to the PCB surface to block etching;

[0078] S4. Development: The dry film that has not undergone polymerization on the PCB board surface is developed away, while the dry film that has undergone polymerization remains on the PCB board surface.

[0079] S5. Etching: Etching the areas of the PCB board surface that are not covered with dry film to create circuitry.

[0080] S6. Removal: Remove the resist pattern from the surface of the PCB board after the outer layer circuit etching is completed;

[0081] S7. Preliminary water washing: Soak and wash the PCB board surface with clean water to remove the stripping solution;

[0082] S8. Mild micro-etching treatment: Immerse the PCB board, which has undergone preliminary water washing, in an acidic micro-etching working solution. The temperature of the micro-etching working solution is controlled at 30℃, the micro-etching rate is controlled at 0.1μm / min, and the treatment time is 30 seconds to dissolve the copper layer on the PCB board. The acidic micro-etching working solution is a mixture of 10L of 15% v / v sulfuric acid (98% sulfuric acid) and 9L of 5% v / v hydrogen peroxide (35% hydrogen peroxide).

[0083] S9. Final rinse: The PCB board that has undergone mild micro-etching is immediately and thoroughly rinsed with clean water; this usually includes multi-stage countercurrent rinsing.

[0084] S10. Drying: Dry the cleaned PCB board.

[0085] Example 4

[0086] This embodiment provides a method for preparing a PCB circuit board. Compared with Embodiment 1, the difference between this embodiment and Embodiment 1 is that the oxidant used is 30 g / L sodium persulfate. Other process conditions are the same as in Embodiment 1.

[0087] The specific preparation method is as follows:

[0088] S1. Pre-treatment: Roughen the incoming PCB board to remove contaminants from the PCB board surface and increase the surface roughness;

[0089] S2, lamination: Applying dry film to the surface of the PCB board after pretreatment;

[0090] S3, Exposure: The dry film attached to the PCB surface is irradiated with ultraviolet light to trigger a photopolymerization reaction to form a stable structure, which is attached to the PCB surface to block etching;

[0091] S4. Development: The dry film that has not undergone polymerization on the PCB board surface is developed away, while the dry film that has undergone polymerization remains on the PCB board surface.

[0092] S5. Etching: Etching the areas of the PCB board surface that are not covered with dry film to create circuitry.

[0093] S6. Removal: Remove the resist pattern from the surface of the PCB board after the outer layer circuit etching is completed;

[0094] S7. Preliminary water washing: Soak and wash the PCB board surface with clean water to remove the stripping solution;

[0095] S8. Mild micro-etching treatment: Immerse the PCB board, which has been preliminarily washed with water, in an acidic micro-etching working solution. The temperature of the micro-etching working solution is controlled at 30℃, the micro-etching rate is controlled at 0.1μm / min, and the treatment time is 30 seconds to dissolve the copper layer on the PCB board. The acidic micro-etching working solution is a mixture of 10L of 10% v / v sulfuric acid (98% sulfuric acid) and 30g / L of sodium persulfate.

[0096] S9. Final rinse: The PCB board that has undergone mild micro-etching is immediately and thoroughly rinsed with clean water; this usually includes multi-stage countercurrent rinsing.

[0097] S10. Drying: Dry the cleaned PCB board.

[0098] Example 5

[0099] This embodiment provides a method for preparing a PCB circuit board. The difference from Embodiment 1 is that the acidic micro-etching working solution in this embodiment also contains citric acid (copper ion complexing agent) at a concentration of 1% v / v. Other process conditions are the same as in Embodiment 1.

[0100] The specific preparation method is as follows:

[0101] S1. Pre-treatment: Roughen the incoming PCB board to remove contaminants from the PCB board surface and increase the surface roughness;

[0102] S2, lamination: Applying dry film to the surface of the PCB board after pretreatment;

[0103] S3, Exposure: The dry film attached to the PCB surface is irradiated with ultraviolet light to trigger a photopolymerization reaction to form a stable structure, which is attached to the PCB surface to block etching;

[0104] S4. Development: The dry film that has not undergone polymerization on the PCB board surface is developed away, while the dry film that has undergone polymerization remains on the PCB board surface.

[0105] S5. Etching: Etching the areas of the PCB board surface that are not covered with dry film to create circuitry.

[0106] S6. Removal: Remove the resist pattern from the surface of the PCB board after the outer layer circuit etching is completed;

[0107] S7. Preliminary water washing: Soak and wash the PCB board surface with clean water to remove the stripping solution;

[0108] S8. Mild micro-etching treatment: Immerse the PCB board, which has been preliminarily washed with water, in an acidic micro-etching working solution. The temperature of the micro-etching working solution is controlled at 30℃, the micro-etching rate is controlled at 0.1μm / min, and the treatment time is 30 seconds to dissolve the copper layer on the PCB board. The acidic micro-etching working solution is a mixture of 10L of 10% v / v sulfuric acid (98% sulfuric acid), 9L of 3% v / v hydrogen peroxide (35% hydrogen peroxide), and 1L of 1% v / v (99% pure citric acid).

[0109] S9. Final rinse: The PCB board that has undergone mild micro-etching is immediately and thoroughly rinsed with clean water; this usually includes multi-stage countercurrent rinsing.

[0110] S10. Drying: Dry the cleaned PCB board.

[0111] Example 6

[0112] This embodiment provides a method for preparing a PCB circuit board. Unlike Embodiment 1, the acidic micro-etching working solution in this embodiment also contains citric acid (copper ion complexing agent) at a concentration of 2% v / v and benzotriazole (corrosion inhibitor) at a concentration of 50 ppm. Other process conditions are the same as in Embodiment 1.

[0113] The specific preparation method is as follows:

[0114] S1. Pre-treatment: Roughen the incoming PCB board to remove contaminants from the PCB board surface and increase the surface roughness;

[0115] S2, lamination: Applying dry film to the surface of the PCB board after pretreatment;

[0116] S3, Exposure: The dry film attached to the PCB surface is irradiated with ultraviolet light to trigger a photopolymerization reaction to form a stable structure, which is attached to the PCB surface to block etching;

[0117] S4. Development: The dry film that has not undergone polymerization on the PCB board surface is developed away, while the dry film that has undergone polymerization remains on the PCB board surface.

[0118] S5. Etching: Etching the areas of the PCB board surface that are not covered with dry film to create circuitry.

[0119] S6. Removal: Remove the resist pattern from the surface of the PCB board after the outer layer circuit etching is completed;

[0120] S7. Preliminary water washing: Soak and wash the PCB board surface with clean water to remove the stripping solution;

[0121] S8. Mild micro-etching treatment: Immerse the PCB board, which has undergone preliminary water washing, in an acidic micro-etching working solution. The temperature of the micro-etching working solution is controlled at 30℃, the micro-etching rate is controlled at 0.1μm / min, and the treatment time is 30 seconds to dissolve the copper layer on the PCB board. The acidic micro-etching working solution is a mixture of 10L of 10% v / v sulfuric acid (98% sulfuric acid), 9L of 3% v / v hydrogen peroxide (35% hydrogen peroxide), 1L of 1% v / v citric acid (99% pure citric acid), and 5g of 50ppm benzotriazole.

[0122] S9. Final rinse: The PCB board that has undergone mild micro-etching is immediately and thoroughly rinsed with clean water; this usually includes multi-stage countercurrent rinsing.

[0123] S10. Drying: Dry the cleaned PCB board.

[0124] Example 7

[0125] This embodiment provides a method for fabricating a PCB circuit board. The difference from Embodiment 1 is that the micro-etching process in this embodiment lasts for 15 seconds. Other process conditions are the same as in Embodiment 1.

[0126] The specific preparation method is as follows:

[0127] S1. Pre-treatment: Roughen the incoming PCB board to remove contaminants from the PCB board surface and increase the surface roughness;

[0128] S2, lamination: Applying dry film to the surface of the PCB board after pretreatment;

[0129] S3, Exposure: The dry film attached to the PCB surface is irradiated with ultraviolet light to trigger a photopolymerization reaction to form a stable structure, which is attached to the PCB surface to block etching;

[0130] S4. Development: The dry film that has not undergone polymerization on the PCB board surface is developed away, while the dry film that has undergone polymerization remains on the PCB board surface.

[0131] S5. Etching: Etching the areas of the PCB board surface that are not covered with dry film to create circuitry.

[0132] S6. Removal: Remove the resist pattern from the surface of the PCB board after the outer layer circuit etching is completed;

[0133] S7. Preliminary water washing: Soak and wash the PCB board surface with clean water to remove the stripping solution;

[0134] S8. Mild micro-etching treatment: Immerse the PCB board, which has undergone preliminary water washing, in an acidic micro-etching working solution. The temperature of the micro-etching working solution is controlled at 30℃, the micro-etching rate is controlled at 0.1μm / min, and the treatment time is 15 seconds to dissolve the copper layer on the PCB board. The acidic micro-etching working solution is a mixture of 10L of 10% v / v sulfuric acid (98% sulfuric acid) and 9L of 3% v / v hydrogen peroxide (35% hydrogen peroxide).

[0135] S9. Final rinse: The PCB board that has undergone mild micro-etching is immediately and thoroughly rinsed with clean water; this usually includes multi-stage countercurrent rinsing.

[0136] S10. Drying: Dry the cleaned PCB board.

[0137] Example 8

[0138] This embodiment provides a method for fabricating a PCB circuit board. The difference from Embodiment 1 is that the micro-etching process in this embodiment lasts for 20 seconds. Other process conditions are the same as in Embodiment 1.

[0139] The specific preparation method is as follows:

[0140] S1. Pre-treatment: Roughen the incoming PCB board to remove contaminants from the PCB board surface and increase the surface roughness;

[0141] S2, lamination: Applying dry film to the surface of the PCB board after pretreatment;

[0142] S3, Exposure: The dry film attached to the PCB surface is irradiated with ultraviolet light to trigger a photopolymerization reaction to form a stable structure, which is attached to the PCB surface to block etching;

[0143] S4. Development: The dry film that has not undergone polymerization on the PCB board surface is developed away, while the dry film that has undergone polymerization remains on the PCB board surface.

[0144] S5. Etching: Etching the areas of the PCB board surface that are not covered with dry film to create circuitry.

[0145] S6. Removal: Remove the resist pattern from the surface of the PCB board after the outer layer circuit etching is completed;

[0146] S7. Preliminary water washing: Soak and wash the PCB board surface with clean water to remove the stripping solution;

[0147] S8. Mild micro-etching treatment: Immerse the PCB board, which has been preliminarily washed with water, in an acidic micro-etching working solution. The temperature of the micro-etching working solution is controlled at 30℃, the micro-etching rate is controlled at 0.1μm / min, and the treatment time is 20 seconds to dissolve the copper layer on the PCB board. The acidic micro-etching working solution is a mixture of 10L of 10% v / v sulfuric acid (98% sulfuric acid) and 9L of 3% v / v hydrogen peroxide (35% hydrogen peroxide).

[0148] S9. Final rinse: The PCB board that has undergone mild micro-etching is immediately and thoroughly rinsed with clean water; this usually includes multi-stage countercurrent rinsing.

[0149] S10. Drying: Dry the cleaned PCB board.

[0150] Comparative Example 1

[0151] This comparative example provides a method for manufacturing a PCB circuit board. Unlike Example 1, this comparative example does not involve micro-etching. Other process conditions are the same as in Example 1.

[0152] The specific preparation method is as follows:

[0153] S1. Pre-treatment: Roughen the incoming PCB board to remove contaminants from the PCB board surface and increase the surface roughness;

[0154] S2, lamination: Applying dry film to the surface of the PCB board after pretreatment;

[0155] S3, Exposure: The dry film attached to the PCB surface is irradiated with ultraviolet light to trigger a photopolymerization reaction to form a stable structure, which is attached to the PCB surface to block etching;

[0156] S4. Development: The dry film that has not undergone polymerization on the PCB board surface is developed away, while the dry film that has undergone polymerization remains on the PCB board surface.

[0157] S5. Etching: Etching the areas of the PCB board surface that are not covered with dry film to create circuitry.

[0158] S6. Removal: Remove the resist pattern from the surface of the PCB board after the outer layer circuit etching is completed;

[0159] S7. Water washing: Soak and wash the PCB board surface with clean water to remove the stripping solution.

[0160] S8. Drying: Dry the cleaned PCB board.

[0161] Comparative Example 2

[0162] This comparative example provides a method for preparing a PCB circuit board. Unlike Example 1, hydrogen peroxide was not added to the acidic micro-etching working solution in this comparative example. Other process conditions were the same as in Example 1.

[0163] The specific preparation method is as follows:

[0164] S1. Pre-treatment: Roughen the incoming PCB board to remove contaminants from the PCB board surface and increase the surface roughness;

[0165] S2, lamination: Applying dry film to the surface of the PCB board after pretreatment;

[0166] S3, Exposure: The dry film attached to the PCB surface is irradiated with ultraviolet light to trigger a photopolymerization reaction to form a stable structure, which is attached to the PCB surface to block etching;

[0167] S4. Development: The dry film that has not undergone polymerization on the PCB board surface is developed away, while the dry film that has undergone polymerization remains on the PCB board surface.

[0168] S5. Etching: Etching the areas of the PCB board surface that are not covered with dry film to create circuitry.

[0169] S6. Removal: Remove the resist pattern from the surface of the PCB board after the outer layer circuit etching is completed;

[0170] S7. Preliminary water washing: Soak and wash the PCB board surface with clean water to remove the stripping solution;

[0171] S8. Mild micro-etching treatment: Immerse the PCB board, which has been preliminarily washed with water, in an acidic micro-etching working solution. The temperature of the micro-etching working solution is controlled at 30℃, the micro-etching rate is controlled at 0.1μm / min, and the treatment time is 30 seconds to dissolve the copper layer on the PCB board. The acidic micro-etching working solution is 10L of 10%v / v sulfuric acid (98% sulfuric acid).

[0172] S9. Final rinse: The PCB board that has undergone mild micro-etching is immediately and thoroughly rinsed with clean water; this usually includes multi-stage countercurrent rinsing.

[0173] S10. Drying: Dry the cleaned PCB board.

[0174] Comparative Example 3

[0175] This comparative example provides a method for preparing a PCB circuit board. Unlike Example 1, the micro-etching process in this comparative example is only 10 seconds, which is considered too short. Other process conditions are the same as in Example 1.

[0176] The specific preparation method is as follows:

[0177] S1. Pre-treatment: Roughen the incoming PCB board to remove contaminants from the PCB board surface and increase the surface roughness;

[0178] S2, lamination: Applying dry film to the surface of the PCB board after pretreatment;

[0179] S3, Exposure: The dry film attached to the PCB surface is irradiated with ultraviolet light to trigger a photopolymerization reaction to form a stable structure, which is attached to the PCB surface to block etching;

[0180] S4. Development: The dry film that has not undergone polymerization on the PCB board surface is developed away, while the dry film that has undergone polymerization remains on the PCB board surface.

[0181] S5. Etching: Etching the areas of the PCB board surface that are not covered with dry film to create circuitry.

[0182] S6. Removal: Remove the resist pattern from the surface of the PCB board after the outer layer circuit etching is completed;

[0183] S7. Preliminary water washing: Soak and wash the PCB board surface with clean water to remove the stripping solution;

[0184] S8. Mild micro-etching treatment: Immerse the PCB board, which has been preliminarily washed with water, in an acidic micro-etching working solution. The temperature of the micro-etching working solution is controlled at 30℃, the micro-etching rate is controlled at 0.1μm / min, and the treatment time is 10 seconds to dissolve the copper layer on the PCB board. The acidic micro-etching working solution is a mixture of 10L of 10% v / v sulfuric acid (98% sulfuric acid) and 9L of 3% v / v hydrogen peroxide (35% hydrogen peroxide).

[0185] S9. Final rinse: The PCB board that has undergone mild micro-etching is immediately and thoroughly rinsed with clean water; this usually includes multi-stage countercurrent rinsing.

[0186] S10. Drying: Dry the cleaned PCB board.

[0187] Comparative Example 4

[0188] This comparative example provides a method for manufacturing a PCB circuit board. Unlike Example 1, the micro-etching process in this comparative example takes 35 seconds, which is considered an excessively long micro-etching time. Other process conditions are the same as in Example 1.

[0189] The specific preparation method is as follows:

[0190] S1. Pre-treatment: Roughen the incoming PCB board to remove contaminants from the PCB board surface and increase the surface roughness;

[0191] S2, lamination: Applying dry film to the surface of the PCB board after pretreatment;

[0192] S3, Exposure: The dry film attached to the PCB surface is irradiated with ultraviolet light to trigger a photopolymerization reaction to form a stable structure, which is attached to the PCB surface to block etching;

[0193] S4. Development: The dry film that has not undergone polymerization on the PCB board surface is developed away, while the dry film that has undergone polymerization remains on the PCB board surface.

[0194] S5. Etching: Etching the areas of the PCB board surface that are not covered with dry film to create circuitry.

[0195] S6. Removal: Remove the resist pattern from the surface of the PCB board after the outer layer circuit etching is completed;

[0196] S7. Preliminary water washing: Soak and wash the PCB board surface with clean water to remove the stripping solution;

[0197] S8. Mild micro-etching treatment: Immerse the PCB board, which has been preliminarily washed with water, in an acidic micro-etching working solution. The temperature of the micro-etching working solution is controlled at 30℃, the micro-etching rate is controlled at 0.1μm / min, and the treatment time is 10 seconds to dissolve the copper layer on the PCB board. The acidic micro-etching working solution is a mixture of 10L of 10% v / v sulfuric acid (98% sulfuric acid) and 9L of 3% v / v hydrogen peroxide (35% hydrogen peroxide).

[0198] S9. Final rinse: The PCB board that has undergone mild micro-etching is immediately and thoroughly rinsed with clean water; this usually includes multi-stage countercurrent rinsing.

[0199] S10. Drying: Dry the cleaned PCB board.

[0200] The defect rate of foreign matter in the PCB boards prepared in the above embodiments and comparative examples was detected by an optical inspection instrument. The test results are shown in Table 1.

[0201] Table 1

[0202] sample Foreign matter defect rate Example 1 7.4% Example 2 8.1% Example 3 6.8% Example 4 6.5% Example 5 5.3% Example 6 4.5% Example 7 8.8% Example 8 8.3% Comparative Example 1 40.1% Comparative Example 2 38.1% Comparative Example 3 33.7%

[0203] According to the test data in the table, the foreign matter defect rate of the technical solutions of Examples 1 to 8 is lower than that of Comparative Examples 1 to 3, which proves that the method of this application improves the etching yield of the outer layer circuit of PCB circuit board.

[0204] Finally, it should be noted that the specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. It is obvious to those skilled in the art that this application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this application is defined by the appended claims rather than the foregoing description, and therefore all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within this application.

Claims

1. A method for improving the etching yield of outer layer circuits on a PCB circuit board, characterized in that, After the film removal process, the PCB circuit board is first pre-washed with water and then subjected to mild micro-etching, followed by a second wash and drying. The mild micro-etching process involves contacting the pre-washed PCB board with an acidic micro-etching working solution to dissolve the copper layer on the PCB board.

2. The method for improving the etching yield of outer layer circuits on a PCB board according to claim 1, characterized in that, The acidic micro-etching working solution comprises a mixture of sulfuric acid and an oxidant with a concentration of 5-15% v / v.

3. The method for improving the etching yield of outer layer circuits on a PCB board according to claim 2, characterized in that, The oxidant is hydrogen peroxide with a concentration of 1-5% v / v or persulfate with a concentration of 10-50 g / L.

4. The method for improving the etching yield of outer layer circuits on a PCB board according to claim 2, characterized in that, The acidic micro-etching working solution also includes a copper ion complexing agent with a concentration of 0.5-2% v / v and / or a slow-release agent with a concentration of 10-100 ppm.

5. A method for improving the etching yield of outer layer circuits on a PCB according to claim 4, characterized in that, The copper ion complexing agent includes citric acid.

6. The method for improving the etching yield of outer layer circuits on a PCB board according to claim 2, as described in claim 4, is characterized in that... The corrosion inhibitor includes benzotriazole.

7. The method for improving the etching yield of outer layer circuits on a PCB board according to claim 1, characterized in that, The micro-etching rate was controlled at 0.1~0.5 μm / min, and the processing time was 15~30 seconds.

8. The method for improving the etching yield of outer layer circuits on a PCB board according to claim 1, characterized in that, The temperature of the acidic micro-etching working solution used for micro-etching is controlled at 30~35℃.

9. A method for manufacturing a PCB circuit board, characterized in that, Includes the following steps: Pre-treatment: Roughening the incoming PCB board to remove contaminants from the PCB board surface and increase the surface roughness; Lamination: Applying dry film to the surface of a PCB board after pretreatment; Exposure: The dry film attached to the PCB surface is photopolymerized by ultraviolet irradiation to form a stable structure that adheres to the PCB surface and blocks etching; Development: The dry film that has not undergone polymerization on the PCB board surface is developed away, while the dry film that has undergone polymerization remains on the PCB board surface; Etching: The process of etching the areas of the PCB board that are not covered with dry film to create circuitry. Removal: Removing the resist pattern from the surface of a PCB board after the outer layer circuitry has been etched; Preliminary water washing: Use clean water to spray or soak the PCB board surface after film removal to remove the film removal solution; Mild micro-etching treatment: Immerse the PCB board, which has been preliminarily washed with water, into or spray it with an acidic micro-etching working solution to dissolve the copper layer on the PCB board. Final rinse: The PCB board that has undergone gentle micro-etching should be thoroughly rinsed with clean water immediately. Drying: Dry the cleaned PCB board.

10. A PCB circuit board, characterized in that, It is prepared using the preparation method described in claim 9.

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