A PCB board surface roughening process

Abstract

The present application relates to the field of PCB board manufacturing, and specifically discloses a process for roughening the surface of a PCB board. A process for roughening the surface of a PCB board comprises: rinsing the surface of the PCB board with water; spraying dilute sulfuric acid on the PCB board for 30s-60s; spraying a roughening solution evenly on the surface of the PCB board, wherein the temperature of the roughening solution is controlled at 35-45°C and the spraying time is 30s-120s, and the roughening solution contains sulfuric acid, anhydrous copper sulfate, and a surface conditioner; spraying the dilute sulfuric acid on the PCB board for 30s-60s; spraying the surface of the PCB board again with water; and drying the washed PCB board. The roughening process for the surface of the PCB board of the present application has the advantage of improving the uniformity of the roughening morphology of the copper surface.

Description

Technical Field

[0001] The present application relates to the field of PCB board manufacturing, and more specifically, to a PCB board surface roughening process. Background Art

[0002] In recent years, the electronics industry has experienced rapid growth, significantly driving the rapid development of the printed circuit board (PCB) industry. PCBs are widely used in numerous fields, including AI servers, 5G base stations, consumer electronics, and aerospace. The primary functions of a PCB include supporting various functional sub-boards, distributing power to them, and enabling signal and electrical interconnection between them. The backplane and the sub-boards it supports jointly complete system functions. In 5G base stations in particular, to meet the demands of high-capacity, high-speed communication and data transmission, the design of communication backplanes is evolving towards higher density and integration. This is further driving the evolution of backplanes towards larger sizes, multiple layers, and smaller apertures.

[0003] As PCB manufacturing processes evolve toward larger sizes, multiple layers, and smaller apertures, their complexity continues to increase. During PCB fabrication, the tight bond between the surface copper metal and the dielectric polymer (between the dry film solder mask and the ink) becomes a critical factor affecting the PCB's functional performance. PCB surface copper typically undergoes electroplating to thicken the copper layer. However, this process is affected by numerous factors, including the plating equipment, plating chemicals, current, and production line control. This makes it difficult to achieve a uniform and consistent coating, negatively impacting subsequent processes, particularly the quality of the hot-pressed dry film and printed solder mask ink.

[0004] In order to improve the adhesion between the copper surface and the dry film and ink, the copper surface is often pre-treated to roughen the copper surface to enhance the bonding force. At present, the conventional treatment method of brushing + micro-etching is used. Due to factors such as the wear of the brushing tool and the uneven distribution of brushing pressure, the degree of roughening at the edge and center areas of the PCB board and between different circuits will be inconsistent. The main component of the micro-etching solution, such as the sulfuric acid-hydrogen peroxide system, hydrogen peroxide is easily decomposed. Under the influence of factors such as temperature changes and metal ion impurities, the decomposition rate of hydrogen peroxide will be accelerated. This will lead to unstable concentrations of the active ingredients in the micro-etching solution, requiring frequent testing and adjustment of the solution components. Therefore, a new surface treatment method is needed to replace the existing brushing + micro-etching process. Summary of the Invention

[0005] In order to improve the uniformity of the roughened morphology of the copper surface, the present application provides a roughening treatment process for the surface of a PCB board.

[0006] The present application provides a PCB surface roughening process using the following technical solutions:

[0007] A PCB surface roughening process includes the following steps:

[0008] One-time water washing: rinse the surface of the PCB board with water;

[0009] Primary pickling: spray dilute sulfuric acid on the PCB for 30s-60s;

[0010] Medium roughening treatment: Spray medium roughening solution evenly on the surface of the PCB board. The temperature of the medium roughening solution is controlled at 35-45°C and the spraying time is 30s-120s. The medium roughening solution contains sulfuric acid, anhydrous copper sulfate and surface conditioner.

[0011] Secondary pickling: spray dilute sulfuric acid on the PCB board for 30s-60s;

[0012] Secondary water washing: spray the PCB surface with water again;

[0013] Drying: Dry the PCB board after washing.

[0014] By adopting the above-mentioned technical solution, the elimination of the brushing step effectively avoids the problem of inconsistent roughening levels between the edge and center areas of the PCB board and between different circuits due to wear of the brushing tool and uneven distribution of brushing pressure. The roughening process of the entire PCB copper surface relies solely on the chemical spray method, which reduces the interference of physical factors on the roughening uniformity from the source and lays the foundation for achieving a more uniform roughening morphology. Under the process conditions of this application, the medium roughening solution can react chemically with the copper surface in a relatively stable and uniform manner, so that the roughening reaction process of various parts of the copper surface tends to be consistent. Compared with the sulfuric acid-hydrogen peroxide system of traditional micro-etching, the medium roughening solution in this process uses a combination of sulfuric acid, anhydrous copper sulfate and a surface conditioner. This system reduces the instability caused by the easy decomposition of hydrogen peroxide. Since there is no problem of rapid decomposition of hydrogen peroxide, the concentration of the active ingredient in the solution fluctuates less during use, and there is no need to frequently test and adjust the solution ingredients as in traditional micro-etching processes, which reduces the difficulty and cost of process control in the production process. The components of the medium-coarsening solution work synergistically, making it relatively insensitive to temperature fluctuations and metal ion impurities during repeated use. By eliminating the need for a brushing process, the large amount of copper shavings and abrasive particle waste generated during the brushing process is eliminated, reducing environmental pollution and subsequent waste disposal costs. Furthermore, the medium-coarsening solution is relatively simple and stable. During post-use treatment, the pollutants in the wastewater are relatively uniform, reducing the difficulty and cost of wastewater treatment and making it more environmentally friendly.

[0015] Optionally, the medium roughening solution comprises, by mass percentage, 3-8% sulfuric acid, 0.001-0.005% anhydrous copper sulfate, 2-3% surface conditioner, and the remainder is deionized water.

[0016] Using the above technical solution, sulfuric acid comprises 3-8% of the medium-roughening solution. This gradually corrodes the copper surface, creating a microscopic roughness and increasing its surface area. This moderate corrosion facilitates subsequent bonding with dry film, ink, and other materials. Within a specified concentration range, the degree and rate of roughening can be controlled to a certain extent, preventing excessive corrosion. Anhydrous copper sulfate, containing 0.001-0.005%, contributes to the reaction equilibrium with the copper surface. When copper ions are released from the copper surface in the solution, anhydrous copper sulfate acts as a buffer, maintaining a relatively stable copper ion concentration within the solution, thereby ensuring uniformity and stability in the roughening process and achieving more consistent roughening across different areas of the copper surface. The copper ions in copper sulfate may affect the copper surface's redox potential to a certain extent, acting synergistically with sulfuric acid to promote the roughening reaction and achieve a more optimal roughening effect. A surface conditioner, comprising 2-3%, adsorbs on the copper surface and preferentially binds to its active sites. During the roughening process, the roughening reaction can be guided to proceed more uniformly across the copper surface, avoiding localized over-roughening or under-roughening. This results in a more regular and uniform surface roughening morphology, which is beneficial for improving the tightness and uniformity of subsequent bonding with the dielectric polymer. Deionized water, as the primary solvent, avoids interference from impurity ions and provides a stable, pure reaction medium for sulfuric acid, anhydrous copper sulfate, and surface conditioners to function. This helps improve the repeatability and stability of the roughening process and ensures a consistent roughening effect on the copper surface.

[0017] Optionally, the medium-coarsening solution further includes 5-8% hydrogen peroxide by mass. When hydrogen peroxide is added to the medium-coarsening solution, the concentration of sulfuric acid is controlled to be 5-10%.

[0018] By adopting the above technical solution, the sulfuric acid and hydrogen peroxide in the roughening solution, utilizing their strong oxidizing properties in an acidic environment, undergo a redox reaction with the copper surface. This strong oxidizing property can more effectively corrode the copper surface, forming a more pronounced microscopic roughness structure. Compared to roughening solutions with a single component, this redox reaction can accelerate the roughening process and improve production efficiency. The active oxygen species produced by the decomposition of hydrogen peroxide under acidic conditions can evenly attack the copper surface, making the roughening degree of different areas of the copper surface more similar, thereby improving the uniformity of the roughened morphology of the copper surface. By controlling the sulfuric acid concentration at 5-10% and the hydrogen peroxide concentration at 5-8%, a relatively stable roughening reaction system can be formed. Within this concentration range, the rate and extent of the redox reaction can be better controlled, avoiding situations where the reaction is too intense, causing excessive corrosion of the copper surface, or the reaction is too slow, affecting production efficiency.

[0019] Optionally, the surface adjuster includes 5-7% 4-hydroxypiperidine, 10-16% 4-methylbenzenesulfonic acid, 1-2% 5-phenyltetrazole, 0.3-0.5% tetrazole, and the rest is deionized water.

[0020] By employing this technical solution, the reaction rate-suppressing properties of the aforementioned ingredients effectively prevent overly rapid reaction between the copper surface and the solution during the intermediate roughening process, promoting uniform etching and modifying surface properties. By suppressing the reaction rate, the degree of copper surface roughening can be precisely controlled, ensuring PCB quality. The surface conditioner's enhanced ion adsorption and dispersion properties ensure a uniform distribution of the copper etching reaction across the copper surface. Under its action, a network-plus-porous structured etching layer forms on the copper surface. This unique structure is achieved by the conditioner guiding the reaction uniformly across the copper surface, avoiding localized over- or under-etching and ensuring uniform roughening across the entire copper surface. The microscopic roughness of the network-plus-porous structured etching layer transforms the copper surface from hydrophobic to hydrophilic. A hydrophilic copper surface is more conducive to bonding with dry film or ink, as some components in dry film and ink adhere better to hydrophilic surfaces. This microscopic roughness significantly increases the surface area of ​​the copper surface, essentially increasing the contact area with the dry film or ink. A larger contact area means more bonding sites, which significantly improves the bonding strength between the copper surface and the dry film or ink, ensuring the stability and reliability of the PCB board during subsequent use and reducing quality problems such as delamination and short circuits caused by poor bonding.

[0021] Optionally, the surface adjuster further comprises 1-3% nano-silicon dioxide by mass, and the particle size of the nano-silicon dioxide is 20-30 nm.

[0022] By adopting the above technical solution, the addition of nano-silicon dioxide will affect the microstructure formed on the copper surface during the medium-roughening process, increase the reactive sites on the copper surface, assist in removing the passivation layer on the copper surface, improve the roughening efficiency and effect, increase the surface roughness after roughening, and enhance the bonding strength between the subsequent plating layer and the PCB board.

[0023] Optionally, the surface conditioner further comprises 2-4% by mass of ethylenediaminetetramethylenephosphonic acid.

[0024] By adopting this technical solution, EDTA can form a stable complex with copper ions. During the intermediate roughening process, EDTA can adjust the concentration of copper ions in the solution, preventing excessive concentrations in local areas. This effectively controls the reaction rate between the copper surface and the solution, preventing overly rapid local reactions and improving the roughening quality.

[0025] Optionally, the surface conditioner further comprises 1-3% by mass of mercaptoethanol.

[0026] By employing this technical solution, the sulfur atoms in mercaptoethanol are highly chemically active, reacting with copper atoms during the intermediate roughening process. This reaction forms a highly reactive sulfide film on the copper surface. This film acts as an intermediate transition layer, guiding the subsequent roughening reaction in an orderly manner and resulting in a more uniform roughening of the copper surface.

[0027] Optionally, the concentration of the dilute sulfuric acid solution in the first pickling step is 10-15%.

[0028] By adopting the above technical solution, when the concentration of the dilute sulfuric acid solution is between 10-15%, the sulfuric acid is sufficient to dissolve the oxides on the copper surface, exposing the pure metallic copper and providing a good reaction foundation for subsequent steps such as roughening. Within this concentration range, the goal of removing oxides and activating the copper surface is achieved while ensuring that the basic structure of the copper surface is not damaged. If the sulfuric acid concentration is too high, the copper surface will be subjected to excessive chemical attack, potentially damaging the integrity of the copper layer and affecting the dimensional accuracy and performance of the PCB board. Too low a concentration will result in poor pickling results.

[0029] Optionally, the concentration of the dilute sulfuric acid solution in the secondary pickling step is 1-3%.

[0030] By adopting the above technical solution, the dilute sulfuric acid at this concentration is relatively mild and will not cause strong corrosion to the copper surface like high-concentration acid. It is mainly used to fine-tune the copper surface and remove some minor oxide layers or unstable compounds that may appear after medium roughening.

[0031] Optionally, in the drying step, the surface of the PCB board is dried with an air flow at 40-60° C. and a flow rate of 15-20 m / s, and the drying time is 30s-60s.

[0032] By employing this technical solution, a temperature of 40-50°C allows moisture to evaporate from the PCB surface without causing thermal damage such as deformation. At this temperature, combined with an airflow rate of 15-20 m / s for 30-60 seconds, drying accelerates moisture removal from the PCB surface, effectively removing residual moisture from the washing and pickling steps. This rapid and moderate drying process prevents oxidation of the copper surface in humid environments, facilitating good bonding with dry film and ink in subsequent processes, ensuring the functionality and stability of the PCB.

[0033] In summary, this application has the following beneficial effects:

[0034] 1. Since the present application systematically cleans, activates, roughens and dries the copper surface through the synergistic effect of multiple steps such as water washing, pickling, medium roughening, re-pickling, water washing and drying, it overcomes the problem of inconsistent thickness and density of the electroplated copper layer, improves the uniformity of the copper surface roughening morphology, thereby ensuring the quality of the PCB board and meeting the PCB industry's demand for high-quality copper surface roughening treatment technology.

[0035] 2. In this application, the medium roughening solution preferably contains 3-8% sulfuric acid, 0.001-0.005% anhydrous copper sulfate, 2-3% surface conditioner and deionized water. Sulfuric acid can moderately corrode the copper surface to increase the surface area and control the degree of roughening. Anhydrous copper sulfate maintains a stable copper ion concentration in the solution to ensure uniform roughening. The surface conditioner guides uniform roughening. Deionized water provides a stable reaction medium. By adding sulfuric acid and hydrogen peroxide, the two utilize their strong oxidizing properties to undergo an oxidation-reduction reaction with the copper surface, accelerating the roughening speed and improving uniformity. Sulfuric acid can also remove the oxide layer, and within this concentration range, the reaction system can be stabilized to avoid excessive corrosion of the copper surface or slow reaction.

[0036] 3. This application preferably uses a surface conditioning agent containing 5-7% 4-hydroxypiperidine, 10-16% 4-methylbenzenesulfonic acid, 1-2% 5-phenyltetrazole, 0.3-0.5% tetrazole, and deionized water. Its reaction rate inhibition property can prevent the copper surface from reacting too quickly with the solution during the medium roughening process, accurately control the roughening degree to ensure quality, enhance the adsorption and dispersion of ions to ensure uniform distribution of the copper etching reaction, and form a network-plus-porous structure etching layer to ensure roughening uniformity. This structure changes the copper surface from hydrophobic to hydrophilic, increases the surface area, and thus increases the contact area with the dry film or ink, thereby improving the bonding strength, ensuring the stability of the PCB board, and reducing the problem of poor bonding. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a SEM image of Example 1 of the present application;

[0038] Figure 2 This is the SEM image of Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0039] The present application is further described in detail below with reference to the examples. It is particularly noted that if no specific conditions are specified in the following examples, the reactions are carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following examples can be obtained from common commercial sources.

[0040] Preparation Example 1

[0041] A preparation method for a medium-roughening solution:

[0042] 1. Prepare the raw materials

[0043] Prepare sulfuric acid (analytical grade), anhydrous copper sulfate (analytical grade), 4-hydroxypiperidine (purity 98%), 4-methylbenzenesulfonic acid (purity 98%), 5-phenyltetrazole (purity 98%), and tetrazolium (purity 98%).

[0044] Prepare sufficient deionized water.

[0045] 2. Preparation of surface conditioning agent

[0046] Weigh 0.6 kg of 4-hydroxypiperidine, 1.3 kg of 4-methylbenzenesulfonic acid, 0.15 kg of 5-phenyltetrazole, and 0.04 kg of tetrazole, and place them in a clean container.

[0047] Deionized water was added to the container until the total mass of the container reached 10 kg, and the mixture was stirred at a speed of 100 r / min for 20 minutes to prepare a surface conditioning agent solution.

[0048] 3. Preparation of coarsening solution

[0049] Weigh 0.6 kg of sulfuric acid, 0.0003 kg of anhydrous copper sulfate, and 0.25 kg of surface conditioner, and add sulfuric acid dropwise to 1 kg of deionized water. Stir continuously during the addition process to prevent sulfuric acid from splashing.

[0050] Then add anhydrous copper sulfate and surface adjuster into the sulfuric acid solution and continue stirring to completely dissolve them.

[0051] The entire solution was supplemented with deionized water to a total amount of 10 kg, and stirred evenly again to obtain a medium-coarsening solution.

[0052] Preparation Example 2

[0053] A method for preparing a medium-roughening solution is different from Preparation Example 1 in that:

[0054] Weigh 0.5 kg of 4-hydroxypiperidine, 1 kg of 4-methylbenzenesulfonic acid, 0.1 kg of 5-phenyltetrazole, and 0.03 kg of tetrazole, and place them in a clean container.

[0055] Deionized water was added to the container until the total mass of the container reached 10 kg, and the mixture was stirred at a speed of 100 r / min for 20 minutes to prepare a surface conditioning agent solution.

[0056] Preparation Example 3

[0057] A method for preparing a medium-roughening solution is different from Preparation Example 1 in that:

[0058] Weigh 0.7 kg of 4-hydroxypiperidine, 1.6 kg of 4-methylbenzenesulfonic acid, 0.2 kg of 5-phenyltetrazole, and 0.05 kg of tetrazole, and place them in a clean container.

[0059] Deionized water was added to the container until the total mass of the container reached 10 kg, and the mixture was stirred at a speed of 100 r / min for 20 minutes to prepare a surface conditioning agent solution.

[0060] Preparation Example 4

[0061] Weigh 0.7 kg of 4-hydroxypiperidine, 1.6 kg of 4-methylbenzenesulfonic acid, 0.2 kg of 5-phenyltetrazole, 0.05 kg of tetrazole, and 0.1-0.3 kg of nano-silicon dioxide with a particle size of 20-30 nm, and put them into a clean container.

[0062] Deionized water was added to the container until the total mass of the container reached 10 kg, and the mixture was stirred at a speed of 100 r / min for 20 minutes to prepare a surface conditioning agent solution.

[0063] Preparation Example 5

[0064] Weigh 0.7 kg of 4-hydroxypiperidine, 1.6 kg of 4-methylbenzenesulfonic acid, 0.2 kg of 5-phenyltetrazolyl, 0.05 kg of tetrazole, and 0.3 kg of ethylenediaminetetramethylenephosphonic acid, and place them in a clean container.

[0065] Deionized water was added to the container until the total mass of the container reached 10 kg, and the mixture was stirred at a speed of 100 r / min for 20 minutes to prepare a surface conditioning agent solution.

[0066] Preparation Example 6

[0067] Weigh 0.7 kg of 4-hydroxypiperidine, 1.6 kg of 4-methylbenzenesulfonic acid, 0.2 kg of 5-phenyltetrazole, 0.05 kg of tetrazole, and 0.2 kg of mercaptoethanol, and place them in a clean container.

[0068] Deionized water was added to the container until the total mass of the container reached 10 kg, and the mixture was stirred at a speed of 100 r / min for 20 minutes to prepare a surface conditioning agent solution.

[0069] Preparation Example 7

[0070] A method for preparing a medium-roughening solution is different from Preparation Example 1 in that:

[0071] Weigh 0.3 kg of sulfuric acid, 0.00015 kg of anhydrous copper sulfate, and 0.2 kg of surface conditioner, and add sulfuric acid dropwise to 1 kg of deionized water. Stir continuously during the addition process to prevent sulfuric acid from splashing.

[0072] Then add anhydrous copper sulfate and surface adjuster into the sulfuric acid solution and continue stirring to completely dissolve them.

[0073] The entire solution was supplemented with deionized water to a total amount of 10 kg, and stirred evenly again to obtain a medium-coarsening solution.

[0074] Preparation Example 8

[0075] A method for preparing a medium-roughening solution is different from Preparation Example 1 in that:

[0076] Weigh 0.8 kg of sulfuric acid, 0.0005 kg of anhydrous copper sulfate, and 0.3 kg of surface conditioner, and add sulfuric acid dropwise to 1 kg of deionized water. Stir continuously during the addition process to prevent sulfuric acid from splashing.

[0077] Then add anhydrous copper sulfate and surface adjuster into the sulfuric acid solution and continue stirring to completely dissolve them.

[0078] The entire solution was supplemented with deionized water to a total amount of 10 kg, and stirred evenly again to obtain a medium-coarsening solution.

[0079] Preparation Example 9

[0080] A preparation method for a medium-roughening solution:

[0081] 1. Prepare the raw materials

[0082] Prepare sulfuric acid (analytical grade), hydrogen peroxide (analytical grade), anhydrous copper sulfate (analytical grade), 4-hydroxypiperidine (purity 98%), 4-methylbenzenesulfonic acid (purity 98%), 5-phenyltetrazole (purity 98%), and tetrazolium (purity 98%).

[0083] Prepare sufficient deionized water.

[0084] 2. Preparation of surface conditioning agent

[0085] Weigh 0.6 kg of 4-hydroxypiperidine, 1.3 kg of 4-methylbenzenesulfonic acid, 0.15 kg of 5-phenyltetrazole, and 0.04 kg of tetrazole, and place them in a clean container.

[0086] Deionized water was added to the container until the total mass of the container reached 10 kg, and the mixture was stirred at a speed of 100 r / min for 20 minutes to prepare a surface conditioning agent solution.

[0087] 3. Preparation of coarsening solution

[0088] Weigh 0.8 kg of sulfuric acid, 0.65 kg of hydrogen peroxide, 0.0003 kg of anhydrous copper sulfate, and 0.25 kg of a surface conditioner, and add sulfuric acid dropwise to 1 kg of deionized water. Stir continuously during the addition to prevent sulfuric acid from splashing.

[0089] Then add anhydrous copper sulfate, surface conditioner and hydrogen peroxide into the sulfuric acid solution and continue stirring to completely dissolve them.

[0090] The entire solution was supplemented with deionized water to a total amount of 10 kg, and stirred evenly again to obtain a medium-coarsening solution.

[0091] Preparation Example 10

[0092] A method for preparing a medium-roughening solution is different from that of Preparation Example 6 in that:

[0093] Weigh 0.5 kg of sulfuric acid and 0.5 kg of hydrogen peroxide.

[0094] Preparation Example 11

[0095] A method for preparing a medium-roughening solution is different from that of Preparation Example 6 in that:

[0096] Weigh 1 kg of sulfuric acid and 0.8 kg of hydrogen peroxide.

[0097] Example 1

[0098] A PCB surface roughening process:

[0099] One wash

[0100] Prepare the spraying equipment and connect the normal temperature water supply pipe, keeping the water temperature at 20-25℃.

[0101] Place the PCB on a fixture and start the spraying system to rinse the PCB surface with room-temperature water. Keep the rinse time within 45 seconds to ensure that all parts of the PCB are fully rinsed.

[0102] One pickling

[0103] Prepare dilute sulfuric acid solution and control the sulfuric acid concentration at 13%.

[0104] Place the PCB in a fixed position below the spray equipment and start the spray equipment to evenly spray the dilute sulfuric acid solution onto the PCB surface for 45 seconds.

[0105] Medium coarsening

[0106] The medium-coarsening solution was prepared according to Preparation Example 1.

[0107] The prepared medium-coarsening solution is placed into a device with heating and spraying functions, and the heating device heats the solution to 40±1℃.

[0108] Place the PCB under the roughening solution spraying equipment and start the spraying equipment to evenly spray the roughening solution on the PCB surface. The spraying time should be controlled within 80 seconds.

[0109] Secondary pickling

[0110] Prepare dilute sulfuric acid solution with a concentration of 2%.

[0111] Start the spraying equipment to spray the dilute sulfuric acid solution at room temperature onto the surface of the PCB board for 45 seconds.

[0112] Secondary water washing

[0113] Start the spraying equipment and spray the surface of the PCB board with normal temperature water for 45 seconds.

[0114] drying

[0115] The PCB surface was dried using a drying fan with a temperature of 50°C and an air flow velocity of 18 m / s for 45 seconds.

[0116] Example 2

[0117] A PCB surface roughening process, which differs from Example 1 in that:

[0118] The medium-roughening solution was prepared by Preparation Example 2.

[0119] Example 3

[0120] A PCB surface roughening process, which differs from Example 1 in that:

[0121] The medium-coarsening solution was prepared by Preparation Example 3.

[0122] Example 4

[0123] A PCB surface roughening process, which differs from Example 1 in that:

[0124] The medium-coarsening solution was prepared by Preparation Example 4.

[0125] Example 5

[0126] A PCB surface roughening process, which differs from Example 1 in that:

[0127] The medium-coarsening solution was prepared by Preparation Example 5.

[0128] Example 6

[0129] A PCB surface roughening process, which differs from Example 1 in that:

[0130] The medium-coarsening solution was prepared by Preparation Example 6.

[0131] Example 7

[0132] A PCB surface roughening process, which differs from Example 1 in that:

[0133] The medium-coarsening solution was prepared by Preparation Example 7.

[0134] Example 8

[0135] A PCB surface roughening process, which differs from Example 1 in that:

[0136] The medium-coarsening solution was prepared by Preparation Example 8.

[0137] Example 9

[0138] A PCB surface roughening process, which differs from Example 1 in that:

[0139] The medium-coarsening solution was prepared by Preparation Example 9.

[0140] Example 10

[0141] A PCB surface roughening process, which differs from Example 1 in that:

[0142] The medium-coarsening solution was prepared by Preparation Example 10.

[0143] Example 11

[0144] A PCB surface roughening process, which differs from Example 1 in that:

[0145] The medium-coarsening solution was prepared by Preparation Example 11.

[0146] Example 12

[0147] A PCB surface roughening process, which differs from Example 1 in that:

[0148] The medium-coarsening solution was prepared according to Preparation Example 1.

[0149] Mix 1.2 kg of medium-coarsening solution with 8.8 kg of deionized water, and put them into a device with heating and spraying functions. The heating device heats the solution to 40±1°C.

[0150] Example 13

[0151] A PCB surface roughening process, which differs from Example 1 in that:

[0152] The concentration of the dilute sulfuric acid solution in the primary pickling step is 10%.

[0153] Example 14

[0154] A PCB surface roughening process, which differs from Example 1 in that:

[0155] The concentration of the dilute sulfuric acid solution in the primary pickling step is 15%.

[0156] Example 15

[0157] A PCB surface roughening process, which differs from Example 1 in that:

[0158] The concentration of the dilute sulfuric acid solution in the secondary pickling step is 1%.

[0159] Example 16

[0160] A PCB surface roughening process, which differs from Example 1 in that:

[0161] The concentration of the dilute sulfuric acid solution in the secondary pickling step is 3%.

[0162] Comparative Example 1

[0163] A PCB surface treatment process, which differs from Example 1 in that:

[0164] The medium roughening step in Example 1 was replaced by a brushing plus micro-etching process.

[0165] The PCB was treated using a brushing and micro-etching method. A nylon brush was used for 30 seconds. The micro-etching solution contained 3% sulfuric acid and 30g / L sodium persulfate, and the micro-etching time was 60 seconds at a temperature of 30°C.

[0166] Comparative Example 2

[0167] A PCB surface roughening treatment process is provided, which differs from Example 1 in that no surface conditioner is added to the roughening solution.

[0168] Comparative Example 3

[0169] A roughening treatment process for a PCB board surface is different from that of Example 1 in that the PCB board surface is dried with an air flow at 80° C. and a flow rate of 18 m / s for 45 seconds.

[0170] In each embodiment / comparative example, 5 test boards of the same specification are used in each group, and the amount of bite and roughness are measured after the treatment. The amount of bite is calculated by measuring the mass change of the PCB board before and after the bite. The bite process will cause the copper layer material to be corroded and removed, resulting in a reduction in mass. The volume of the corroded copper layer can be calculated based on the mass difference, and then the amount of bite can be obtained. The stylus of the contact profilometer is moved on the copper surface of the PCB board. The stylus moves up and down with the microscopic undulations of the copper surface. The instrument converts this displacement change into an electrical signal, and the surface roughness parameters are obtained after processing. The cumulative difference is calculated based on the average value of the bite and roughness. For example, when the bite amounts are 0.75, 0.80, 0.85, 0.90, and 0.95, respectively, the average value is 0.85, and the cumulative difference is 0.3.

[0171] A PCB board was prepared using the methods of Example 1 and Comparative Example 3, and its surface quality after drying was observed.

[0172] A PCB board was prepared using the methods of Example 1 and Comparative Example 1, respectively. Scanning electron microscopy (SEM) was performed on the two PCB boards to compare the copper surface conditions under the SEM images.

[0173] Table 1 Test data

[0174] Average erosion amount / μm Average roughness / Ra value Cumulative difference in erosion Roughness cumulative difference Example 1 0.82 0.31 0.06 0.06 Example 2 0.82 0.36 0.08 0.07 Example 3 0.77 0.36 0.07 0.08 Example 4 0.84 0.34 0.05 0.05 Example 5 0.84 0.33 0.04 0.05 Example 6 0.86 0.36 0.04 0.04 Example 7 0.82 0.34 0.08 0.07 Example 8 0.84 0.32 0.07 0.09 Example 9 0.82 0.34 0.05 0.07 Example 10 0.79 0.31 0.06 0.10 Example 11 0.77 0.36 0.07 0.10 Example 12 0.80 0.34 0.08 0.09 Example 13 0.79 0.36 0.06 0.06 Example 14 0.82 0.36 0.08 0.08 Example 15 0.80 0.32 0.07 0.06 Example 16 0.82 0.33 0.10 0.08 Comparative Example 1 1.02 0.18 0.35 0.27 Comparative Example 2 1.13 0.08 0.23 0.15

[0175] Table 2 PCB surface quality under different drying methods

[0176] Example 1 Good surface quality Comparative Example 3 There is local thermal deformation

[0177] Combined with Example 1 and Comparative Example 1 and Table 1 and Figure 1-2 It can be seen that the copper surface after medium-roughening treatment exhibits a microscopically rough structure of a network-plus-porous etched layer; the copper surface after brushing and micro-etching exhibits a flaky, concave-convex structure. SEM images show a large area of ​​planar structure and a small area of ​​rough structure, demonstrating an uneven surface roughness. The roughness structure is unevenly distributed across the copper surface and the roughness is not fine enough. The network-like pore structure of the former can firmly grasp the dry film or ink, forming a recessed structure that locks the surface and improves adhesion. This comparative example demonstrates that the medium-roughening process significantly improves the roughness Ra value while maintaining a nearly identical amount of etch. Furthermore, both the etch amount and the roughness are more stable with a narrow fluctuation range.

[0178] Combining Example 1 and Comparative Example 2 with Table 1, it can be seen that the surface conditioner's reaction rate suppression effectively prevents excessive reaction between the copper surface and the solution during the intermediate roughening process, promoting uniform etching and modifying surface properties. By suppressing the reaction rate, the degree of copper surface roughening can be precisely controlled, ensuring the quality of the PCB. The surface conditioner's enhanced ion adsorption and dispersion properties ensure a uniform distribution of the copper etching reaction across the copper surface.

[0179] Combining Example 1 and Comparative Example 3 with Table 2, it can be seen that a temperature of 40-50°C allows for evaporation of moisture from the PCB surface without causing thermal damage to the PCB, such as deformation. At this temperature, combined with an airflow rate of 15-20 m / s for 30-60 seconds, drying accelerates the removal of moisture from the PCB surface, effectively removing residual moisture after the water and acid wash steps. A rapid and moderate drying process prevents oxidation of the copper surface in humid environments, facilitating good bonding with the dry film and ink in subsequent processes, ensuring the functionality and stability of the PCB.

[0180] It can be seen from Examples 1-11 and Table 1 that the average bite amount of Examples 1-11 is between 0.77-0.86 μm, and the fluctuation range is relatively small. This shows that under different changes in the formula of the medium-roughening solution, the control ability of the entire medium-roughening treatment process on the bite amount and roughness is relatively stable. Comparing Examples 1-3, it can be found that when the proportions of 4-hydroxypiperidine, 4-methylbenzenesulfonic acid, 5-phenyltetrazole, and tetrazole in the surface adjuster are changed within the scope of this application, the bite amount and roughness changes are relatively stable, which is conducive to the subsequent uniform adhesion of the dry film or ink on the copper surface. Example 4 adds nano-silica, Example 5 adds ethylenediaminetetramethylenephosphonic acid, and Example 6 adds mercaptoethanol. The addition of these additives increases the bite amount and roughness, and the cumulative difference in the bite amount and roughness becomes smaller, indicating that the surface etching effect is improved and the uniformity of the surface morphology is higher.

[0181] Combining Example 1 with Examples 11-16 and Table 1, it can be seen that Examples 12-16 primarily alter process parameters such as the concentration of the intermediate roughening solution or the pickling concentration. Compared to Example 1, Example 12 alters the concentration of the intermediate roughening solution, Examples 13-14 alter the concentration of the primary pickling sulfuric acid, and Examples 15-16 alter the concentration of the secondary pickling sulfuric acid. These changes result in variations in the amount of erosion, but within the process scope of this application, excellent roughening levels and uniform surface morphology are still achieved, while maintaining a relatively stable amount of erosion and a roughness level conducive to subsequent processing.

[0182] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A PCB surface roughening process, characterized in that: The following steps are involved: One-time water washing: rinse the surface of the PCB board with water; Primary pickling: spray dilute sulfuric acid on the PCB for 30s-60s; Medium roughening treatment: Spray medium roughening solution evenly on the surface of the PCB board. The temperature of the medium roughening solution is controlled at 35-45°C and the spraying time is 30s-120s. The medium roughening solution contains sulfuric acid, anhydrous copper sulfate and surface conditioner. Secondary pickling: spray dilute sulfuric acid on the PCB board for 30s-60s; Secondary water washing: spray the PCB surface with water again; Drying: Dry the PCB board after washing; The coarsening solution components adopt the following scheme: The composition comprises, by mass percentage, 3-8% sulfuric acid, 0.001-0.005% anhydrous copper sulfate, 2-3% surface conditioner, and the remainder deionized water; The surface adjuster comprises, by mass percentage, 5-7% 4-hydroxypiperidine, 10-16% 4-methylbenzenesulfonic acid, 1-2% 5-phenyltetrazole, 0.3-0.5% tetrazole, 1-3% nano-silicon dioxide, and the remainder is deionized water. The particle size of the nano-silicon dioxide is 20-30 nm.

2. The PCB surface roughening process according to claim 1, wherein: The surface adjuster further comprises 2-4% by mass of ethylenediaminetetramethylenephosphonic acid.

3. The PCB surface roughening process according to claim 1, wherein: The surface adjuster also includes 1-3% by mass of mercaptoethanol.

4. The PCB surface roughening process according to claim 1, wherein: The concentration of the dilute sulfuric acid solution in the primary pickling step is 10-15%.

5. The PCB surface roughening process according to claim 1, wherein: The concentration of the dilute sulfuric acid solution in the secondary pickling step is 1-3%.

6. The PCB surface roughening process according to claim 1, wherein: In the drying step, the surface of the PCB board is dried with an air flow at 40-60° C. and a flow rate of 15-20 m / s, and the drying time is 30s-60s.

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