Medium roughening treatment process for surface of PCB (Printed Circuit Board)

Abstract

The invention relates to the field of PCB manufacturing, and particularly discloses a PCB surface roughening treatment process. The roughening treatment process for the surface of the PCB comprises the following steps: washing the surface of the PCB by using water; dilute sulfuric acid is sprayed on the PCB for 30 s to 60 s; medium roughening liquid medicine is evenly sprayed on the surface of the PCB, the temperature of the medium roughening liquid medicine is controlled to be 35-45 DEG C, the spraying time is 30-120 s, and the medium roughening liquid medicine contains sulfuric acid, anhydrous cupric sulfate and a surface conditioning agent; dilute sulphuric acid is sprayed on the PCB, and the spraying time is 30 s to 60 s; spraying and washing the surface of the PCB with water again; and drying the PCB which is washed with water. The roughening treatment process for the surface of the PCB 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 medium roughening treatment process for the surface of a PCB board. Background Art

[0002] In recent years, the electronics industry has shown a rapid development trend, which has greatly driven the high-speed development of the printed circuit board industry. In many fields such as AI servers, 5G base stations, consumer electronics, and aerospace, PCB boards are widely used. The main functions of PCB boards include carrying each functional daughter board, distributing power to the daughter board, and realizing the interconnection and interoperability of signals and electricity of each daughter board. The backplane and the daughter boards it carries jointly complete the system functions. Especially in 5G base stations, in order to meet the requirements of large-capacity and high-speed transmission of communication and data, the design of communication backplanes is developing towards high density and high integration, which further promotes the evolution of backplanes towards large size, multi-layers, and small apertures.

[0003] As the process of PCB boards develops towards large size, multi-layers, and small apertures, its complexity is increasing day by day. During the production process of PCB boards, the tight bonding between the surface copper metal and the dielectric polymer (between the dry film solder mask and the ink) has become a key factor affecting the functional performance of PCB boards. The copper on the surface of PCB boards usually needs to be thickened by electroplating. However, the process of electroplating and thickening the copper layer will be affected by various factors such as electroplating equipment, electroplating solutions, current, and production line control, resulting in the difficulty of achieving a uniform state of the coating, which will have an adverse impact on subsequent processes, especially the quality of 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 usually pretreated to roughen the copper surface to enhance the bonding force. Currently, the conventional treatment method of using abrasive brushing + micro-etching, due to factors such as the wear of abrasive brushing tools and uneven distribution of abrasive brushing pressure, will result in inconsistent roughening degrees between the edges and the central area of the PCB board and between different circuits. The main components in the micro-etching solution, such as the sulfuric acid-hydrogen peroxide system, are prone to decomposition of hydrogen peroxide. Under the influence of factors such as temperature change and metal ion impurities, the decomposition rate of hydrogen peroxide will accelerate. This will lead to unstable concentration of the effective components of the micro-etching solution, and it is necessary to frequently detect and adjust the solution components. Therefore, a new surface treatment method is needed to replace the existing abrasive 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 medium roughening treatment process for the surface of a PCB board.

[0006] A medium roughening treatment process for the surface of a PCB board provided by the present application adopts the following technical solutions: A medium roughening treatment process for the surface of a PCB board includes the following steps: First water wash: Rinse the surface of the PCB board with water; First pickling: Spray dilute sulfuric acid on the PCB board for 30s - 60s; Medium roughening treatment: Evenly spray the medium roughening solution 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 a surface conditioner; Second pickling: Spray dilute sulfuric acid on the PCB board, and the spraying time is 30s - 60s; Second water wash: Spray and rinse the surface of the PCB board with water again; Drying: Dry the PCB board after water wash.

[0007] By adopting the above technical solution, canceling the brushing link effectively avoids the problem of inconsistent roughening degree between the edge and the center area of the PCB board and between different circuits caused by the wear of the brushing tool and the uneven distribution of the brushing pressure. The roughening process of the entire copper surface of the PCB board only depends on the chemical spraying method, reducing the interference of physical factors on the roughening uniformity from the source and laying a foundation for achieving a more uniform roughening morphology. Under the process conditions of this application, the medium roughening solution can react with the copper surface stably and evenly, so that the roughening reaction process of each part of the copper surface tends to be consistent. Compared with the traditional sulfuric acid - hydrogen peroxide system for micro - etching, the medium roughening solution in this process adopts a combination of sulfuric acid, anhydrous copper sulfate, and a surface conditioner. This system reduces the unstable factors brought by the easy decomposition of hydrogen peroxide. Due to the absence of the rapid decomposition problem of hydrogen peroxide, the concentration fluctuation of the effective components in the solution during use is small, and it is not necessary to detect and adjust the solution components as frequently as in the traditional micro - etching process, reducing the process control difficulty and cost during the production process. The components in the medium roughening solution system interact synergistically and are relatively less affected by temperature changes and metal ion impurities during multiple uses. Since the brushing process is not adopted, a large amount of copper chips and abrasive particle waste generated during the brushing process are avoided, reducing environmental pollution and the subsequent waste treatment cost. At the same time, the medium roughening solution system is relatively simple and stable. During the treatment process after the solution is used, the pollutant components in the wastewater are relatively single, reducing the difficulty and cost of wastewater treatment and being more in line with environmental protection requirements.

[0008] Optionally, the components of the medium roughening solution include 3 - 8% sulfuric acid, 0.001 - 0.005% anhydrous copper sulfate, 2 - 3% surface conditioner by mass percentage, and the rest is deionized water.

[0009] By adopting the above technical solution, sulfuric acid accounts for 3-8% in the medium roughening solution. Sulfuric acid can gradually corrode the copper surface, forming a microscopic rough structure on the copper surface and increasing the surface area of the copper surface. This moderate corrosion helps to better bond with materials such as dry film and ink in the subsequent process, and within the specified concentration range, it can control the degree and speed of roughening to a certain extent and avoid over-corrosion. The content of anhydrous copper sulfate is 0.001-0.005%. A small amount of anhydrous copper sulfate can participate in the reaction equilibrium with the copper surface. When copper ions are dissolved out from the copper surface under the action of the solution, anhydrous copper sulfate can play a certain buffering role to maintain the relative stability of the copper ion concentration in the solution, thus ensuring the uniformity and stability of the roughening process and making the roughening degree of different regions of the copper surface more consistent. The copper ions in copper sulfate may affect the oxidation-reduction potential of the copper surface to a certain extent and cooperate with sulfuric acid to promote the roughening reaction of the copper surface, making the roughening effect more ideal. The surface conditioner accounts for 2-3%. It can adsorb on the copper surface and preferentially bind to the active sites on the copper surface. During the roughening process, it can guide the roughening reaction to proceed more uniformly on the copper surface, avoiding local over-roughening or insufficient roughening, making the roughening morphology of the copper surface more regular and uniform, and being beneficial to improving the tightness and uniformity of the subsequent bonding with the dielectric polymer. Deionized water, as the main solvent, can avoid the interference of impurity ions and provide a stable and pure reaction medium for sulfuric acid, anhydrous copper sulfate and the surface conditioner to play their roles, helping to improve the repeatability and stability of the roughening process and ensuring the consistency of the roughening effect of the copper surface.

[0010] Optionally, the medium roughening solution further includes 5-8% hydrogen peroxide by mass percentage. When hydrogen peroxide is added to the medium roughening solution, the sulfuric acid concentration is controlled at 5-10%.

[0011] By adopting the above technical solution, sulfuric acid and hydrogen peroxide in the medium roughening solution undergo an oxidation-reduction reaction with the copper surface by virtue of their strong oxidizing properties in an acidic environment. This strong oxidizing property can more effectively corrode the copper surface and form a more obvious microscopic rough structure. Compared with a roughening solution of a single component, this oxidation-reduction reaction can accelerate the roughening speed and improve production efficiency. The active oxygen species generated by the decomposition of hydrogen peroxide under acidic conditions can uniformly attack the copper surface, making the roughening degree of different regions of the copper surface closer, thereby improving the uniformity of the roughening morphology of the copper surface. Controlling the sulfuric acid concentration at 5-10% and the hydrogen peroxide concentration at 5-8% can form a relatively stable roughening reaction system. Within this concentration range, the rate and degree of the oxidation-reduction reaction can be better controlled, avoiding the situation that the reaction is too violent resulting in over-corrosion of the copper surface or the reaction is too slow affecting production efficiency.

[0012] Optionally, the surface conditioner comprises 4-hydroxy piperidine 5-7%, p-toluenesulfonic acid 10-16%, 5-phenyltetrazole 1-2%, tetrazole 0.3-0.5%, and the balance being deionized water.

[0013] By adopting the above technical solution, the reaction rate inhibition characteristics of the above components can effectively avoid the too-fast reaction between the copper surface and the solution during the medium coarsening process and can achieve the effects of promoting uniform etching and changing the surface properties. By inhibiting the reaction rate, the coarsening degree of the copper surface can be precisely controlled to ensure the quality of the PCB board. The enhanced adsorption ions and dispersion effect of the surface conditioner enable the copper etching reaction to be evenly distributed on the copper surface. Under its action, a network plus pore-like structure etching layer is formed on the copper surface. This special structure is generated because the conditioner guides the reaction to proceed evenly on the copper surface, avoiding problems such as local over-etching or under-etching and ensuring the uniformity of the entire copper surface coarsening. The microscopic rough structure of the network plus pore-like structure etching layer changes the copper surface from hydrophobic to hydrophilic. The hydrophilic copper surface is more conducive to bonding with the dry film or ink because some components in the dry film and ink have better adhesion on the hydrophilic surface. The microscopic rough structure greatly increases the surface area of the copper surface. Essentially, it increases the contact area with the dry film or ink. A larger contact area means more binding sites, thus significantly improving the bonding force 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 circuit caused by poor bonding.

[0014] Optionally, the surface conditioner further comprises 1-3% by mass of nano-silica, and the particle size of the nano-silica is 20-30 nm.

[0015] By adopting the above technical solution, the addition of nano-silica will affect the microscopic structure formed on the copper surface during the medium coarsening process, increase the reactive active sites on the copper surface, assist in removing the passivation layer on the copper surface, improve the coarsening efficiency and effect, increase the surface roughness after coarsening, and enhance the bonding force between the subsequent plating layer and the PCB board.

[0016] Optionally, the surface conditioner further comprises 2-4% by mass of ethylenediamine tetramethylenephosphonic acid.

[0017] By adopting the above technical solution, ethylenediamine tetramethylenephosphonic acid can form a stable complex with copper ions. During the medium coarsening process, ethylenediamine tetramethylenephosphonic acid can regulate the concentration of copper ions in the solution, avoid the too-high concentration of copper ions in local areas, effectively control the reaction rate between the copper surface and the solution, prevent local reactions from being too fast, and improve the coarsening quality.

[0018] Optionally, the surface conditioner further comprises 1-3% by mass of mercaptoethanol.

[0019] By adopting the above technical solution, the sulfur atom in mercaptoethanol has strong chemical activity. During the medium roughening process, it can chemically react with copper atoms. This reaction forms a sulfide film with specific activity on the copper surface. This sulfide film can serve as an intermediate transition layer to guide the subsequent roughening reaction to proceed more orderly, making the roughening of the copper surface more uniform.

[0020] Optionally, the concentration of the dilute sulfuric acid solution in the first pickling step is 10 - 15%.

[0021] By adopting the above technical solution, when the concentration of the dilute sulfuric acid solution is 10 - 15%, sulfuric acid is sufficient to dissolve the copper surface oxide, exposing the pure metallic copper on the copper surface, providing a good reaction basis for subsequent steps such as medium roughening. Within this concentration range, it can not only achieve the purpose of removing oxides and activating the copper surface, but also ensure that the basic structure of the copper surface is not damaged. If the sulfuric acid concentration is too high, the copper surface will be overly chemically eroded, possibly damaging the integrity of the copper layer and affecting the dimensional accuracy and performance of the PCB board. If the concentration is too low, the pickling effect will be poor.

[0022] Optionally, the concentration of the dilute sulfuric acid solution in the second pickling step is 1 - 3%.

[0023] 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 mainly fine - tunes the copper surface, removing some slightly oxidized layers or unstable compounds that may appear after medium roughening.

[0024] 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 30 s - 60 s.

[0025] By adopting the above technical solution, the temperature of 40 - 50°C can not only evaporate the moisture on the surface of the PCB board but also will not cause thermal damage to the PCB board due to high temperature, such as deforming the board material. At this temperature, combined with an air flow speed of 15 - 20 m / s and drying for 30 - 60 s, it can accelerate the detachment of moisture from the surface of the PCB board, effectively removing the residual moisture after the water washing and pickling steps. A fast and appropriate drying process can prevent the copper surface from oxidizing in a humid environment, which is beneficial to the good bonding with the dry film and ink in subsequent processes, ensuring the functionality and stability of the PCB board.

[0026] In summary, the present application has the following beneficial effects: 1. Since this application systematically cleans, activates, roughens, and dries the copper surface through the coordinated action 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 roughened morphology of the copper surface, thus ensuring the quality of the PCB board and meeting the requirements of the PCB industry for high-quality copper surface roughening treatment processes.

[0027] 2. In this application, it is preferably adopted that the medium roughening potion components contain 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 roughening degree. Anhydrous copper sulfate maintains the stability of the copper ion concentration in the potion to ensure uniform roughening. The surface conditioner guides uniform roughening, and deionized water provides a stable reaction medium. By adding sulfuric acid and hydrogen peroxide, the two use strong oxidizing properties to carry out redox reactions with the copper surface, accelerating the roughening speed and improving uniformity. Sulfuric acid can also remove the oxide layer, and within this concentration range, it can stabilize the reaction system, avoiding excessive corrosion of the copper surface or too slow reaction.

[0028] 3. In this application, it is preferably adopted that the surface conditioner contains 5 - 7% 4 - hydroxypiperidine, 10 - 16% 4 - methylbenzenesulfonic acid, 1 - 2% 5 - phenyltetrazole, 0.3 - 0.5% tetrazole, and deionized water. Its characteristic of inhibiting the reaction rate can avoid too fast reaction between the copper surface and the potion during medium roughening, precisely control the roughening degree to ensure quality, enhance the adsorption of ions and the dispersion effect to make the copper etching reaction evenly distributed, form a network plus pore - like structure etching layer to ensure the uniformity of roughening. This structure changes the copper surface from hydrophobic to hydrophilic, increases the surface area, that is, increases the contact area with the dry film or ink, improves the bonding force, ensures the stability of the PCB board, and reduces the problem of poor bonding. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is the SEM image of Example 1 of this application; Figure 2 is the SEM image of Comparative Example 1 of this application. DETAILED DESCRIPTION OF THE INVENTION

[0030] The following further elaborates on this application in combination with examples. It should be specifically noted that: for those not specifying specific conditions in the following examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. Except for special instructions, the raw materials used in the following examples can all be obtained from ordinary commercial sources.

[0031] Preparation Example 1 A preparation method of a medium roughening potion: I. Prepare raw materials Prepare sulfuric acid (analytical grade), anhydrous copper sulfate (analytical grade), 4-hydroxypiperidine (purity 98%), 4-methylbenzenesulfonic acid (purity 98%), 5-phenyltetrazole (purity 98%), and tetrazole (purity 98%).

[0032] Prepare a sufficient amount of deionized water.

[0033] II. Preparation of surface conditioner 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.

[0034] Add deionized water to the container until the total mass in the container reaches 10 kg, and use a stirrer to stir at a speed of 100 r / min for 20 min to prepare a surface conditioner solution.

[0035] III. Preparation of medium roughening solution Weigh 0.6 kg of sulfuric acid, 0.0003 kg of anhydrous copper sulfate, and 0.25 kg of surface conditioner. Add sulfuric acid dropwise to 1 kg of deionized water, and continuously stir during the dropping process to prevent sulfuric acid splashing.

[0036] Then add anhydrous copper sulfate and surface conditioner to the sulfuric acid solution, and continue to stir until it is completely dissolved.

[0037] Use deionized water to make up the total amount of the entire solution to 10 kg, and stir evenly again to obtain the medium roughening solution.

[0038] Preparation Example 2 A method for preparing a medium roughening solution, which is different from Preparation Example 1 in that: 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.

[0039] Add deionized water to the container until the total mass in the container reaches 10 kg, and use a stirrer to stir at a speed of 100 r / min for 20 min to prepare a surface conditioner solution.

[0040] Preparation Example 3 A method for preparing a medium roughening solution, which is different from Preparation Example 1 in that: 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.

[0041] Add deionized water to the container until the total mass in the container reaches 10 kg, and use a stirrer to stir at a speed of 100 r / min for 20 min to prepare a surface conditioner solution.

[0042] Preparation Example 4 Weigh 0.7 kg of 4-hydroxypiperidine, 1.6 kg of p-toluenesulfonic acid, 0.2 kg of 5-phenyltetrazole, 0.05 kg of tetrazole, and 0.1 - 0.3 kg of nano-silica with a particle size of 20 - 30 nm, and put them into a clean container.

[0043] Add deionized water to the container until the total mass in the container reaches 10 kg, and use a stirrer to stir at a speed of 100 r / min for 20 min to prepare a surface conditioner solution.

[0044] Preparation Example 5 Weigh 0.7 kg of 4-hydroxypiperidine, 1.6 kg of p-toluenesulfonic acid, 0.2 kg of 5-phenyltetrazole, 0.05 kg of tetrazole, and 0.3 kg of ethylenediaminetetramethylenephosphonic acid, and put them into a clean container.

[0045] Add deionized water to the container until the total mass in the container reaches 10 kg, and use a stirrer to stir at a speed of 100 r / min for 20 min to prepare a surface conditioner solution.

[0046] Preparation Example 6 Weigh 0.7 kg of 4-hydroxypiperidine, 1.6 kg of p-toluenesulfonic acid, 0.2 kg of 5-phenyltetrazole, 0.05 kg of tetrazole, and 0.2 kg of mercaptoethanol, and put them into a clean container.

[0047] Add deionized water to the container until the total mass in the container reaches 10 kg, and use a stirrer to stir at a speed of 100 r / min for 20 min to prepare a surface conditioner solution.

[0048] Preparation Example 7 A method for preparing a medium roughening chemical solution, which is different from Preparation Example 1 in that: Weigh 0.3 kg of sulfuric acid, 0.00015 kg of anhydrous copper sulfate, and 0.2 kg of surface conditioner. Add sulfuric acid dropwise to 1 kg of deionized water, and continuously stir during the dropping process to prevent sulfuric acid from splashing.

[0049] Then add anhydrous copper sulfate and surface conditioner to the sulfuric acid solution, and continue to stir until it is completely dissolved.

[0050] Use deionized water to make up the total amount of the whole solution to 10 kg, and stir evenly again to obtain the medium roughening chemical solution.

[0051] Preparation Example 8 A preparation method of medium coarsening solution, different from Preparation Example 1 in that: Weigh 0.8 kg of sulfuric acid, 0.0005 kg of anhydrous copper sulfate, and 0.3 kg of surface conditioner. Dropwise add sulfuric acid into 1 kg of deionized water, and continuously stir during the dropping process to prevent sulfuric acid from splashing.

[0052] Then add anhydrous copper sulfate and surface conditioner into the sulfuric acid solution, and continue to stir until they are completely dissolved.

[0053] Use deionized water to make up the total amount of the whole solution to 10 kg, and stir evenly again to obtain the medium coarsening solution.

[0054] Preparation Example 9 A preparation method of medium coarsening solution: I. Prepare raw materials Prepare sulfuric acid (analytical pure), hydrogen peroxide (analytical pure), anhydrous copper sulfate (analytical pure), 4-hydroxypiperidine (purity 98%), 4-methylbenzenesulfonic acid (purity 98%), 5-phenyltetrazole (purity 98%), and tetrazole (purity 98%).

[0055] Prepare sufficient deionized water.

[0056] II. Prepare surface conditioner 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 put them into a clean container.

[0057] Add deionized water into the container until the total mass in the container reaches 10 kg, and use a stirrer to stir at a speed of 100 r / min for 20 min to prepare a surface conditioner solution.

[0058] III. Prepare medium coarsening solution 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 surface conditioner. Dropwise add sulfuric acid into 1 kg of deionized water, and continuously stir during the dropping process to prevent sulfuric acid from splashing.

[0059] Then add anhydrous copper sulfate, surface conditioner, and hydrogen peroxide into the sulfuric acid solution, and continue to stir until they are completely dissolved.

[0060] Use deionized water to make up the total amount of the whole solution to 10 kg, and stir evenly again to obtain the medium coarsening solution.

[0061] Preparation Example 10 A preparation method of medium coarsening solution, different from Preparation Example 6 in that: Weigh 0.5 kg of sulfuric acid and 0.5 kg of hydrogen peroxide.

[0062] Preparation Example 11 A preparation method of medium roughening solution, which is different from Preparation Example 6 in that: Weigh 1 kg of sulfuric acid and 0.8 kg of hydrogen peroxide.

[0063] Example 1 A medium roughening treatment process for the surface of a PCB board: Primary water washing Prepare a spray device and connect it to a normal temperature water supply pipe, with the water temperature maintained at 20 - 25 °C.

[0064] Place the PCB board on a fixing device, start the spray device, and spray and wash the surface of the PCB board with normal temperature water. The washing time is controlled within 45 seconds to ensure that all parts of the PCB board can be fully washed by water.

[0065] Primary pickling Prepare a dilute sulfuric acid solution with the sulfuric acid concentration controlled at 13%.

[0066] Place the PCB board at a fixed position under the spray device, start the spray device, and evenly spray the dilute sulfuric acid solution on the surface of the PCB board. The spraying time is 45 seconds.

[0067] Medium roughening The medium roughening solution is prepared according to Preparation Example 1.

[0068] Load the prepared medium roughening solution into a device with heating and spraying functions, and the heating device heats the temperature of the solution to 40 ± 1 °C.

[0069] Place the PCB board under the medium roughening solution spraying device, start the spray device, and evenly spray the medium roughening solution on the surface of the PCB board. The spraying time is controlled within 80 seconds.

[0070] Secondary pickling Prepare a dilute sulfuric acid solution with a concentration of 2%.

[0071] Start the spray device, and spray the normal temperature dilute sulfuric acid solution on the surface of the PCB board. The spraying time is 45 seconds.

[0072] Secondary water washing Start the spray device, and spray and wash the surface of the PCB board with normal temperature water. The spraying time is 45 seconds.

[0073] Drying Use a drying fan with a temperature of 50 °C and an air flow rate of 18 m / s to dry the surface of the PCB board. The drying time is 45 seconds.

[0074] Example 2 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: The medium roughening potion is prepared from Preparation Example 2.

[0075] Example 3 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: The medium roughening potion is prepared from Preparation Example 3.

[0076] Example 4 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: The medium roughening potion is prepared from Preparation Example 4.

[0077] Example 5 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: The medium roughening potion is prepared from Preparation Example 5.

[0078] Example 6 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: The medium roughening potion is prepared from Preparation Example 6.

[0079] Example 7 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: The medium roughening potion is prepared from Preparation Example 7.

[0080] Example 8 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: The medium roughening potion is prepared from Preparation Example 8.

[0081] Example 9 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: The medium roughening potion is prepared from Preparation Example 9.

[0082] Example 10 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: The medium roughening potion is prepared from Preparation Example 10.

[0083] Example 11 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: The medium roughening potion is prepared from Preparation Example 11.

[0084] Example 12 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: The medium roughening chemical solution is prepared from Preparation Example 1.

[0085] Mix 1.2 kg of the medium roughening chemical solution with 8.8 kg of deionized water, and load it into a device with heating and spraying functions. The heating device heats the temperature of the chemical solution to 40 ± 1 °C.

[0086] Example 13 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: In the first pickling step, the concentration of the dilute sulfuric acid solution is 10%.

[0087] Example 14 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: In the first pickling step, the concentration of the dilute sulfuric acid solution is 15%.

[0088] Example 15 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: In the second pickling step, the concentration of the dilute sulfuric acid solution is 1%.

[0089] Example 16 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: In the second pickling step, the concentration of the dilute sulfuric acid solution is 3%.

[0090] Comparative Example 1 A surface treatment process for a PCB board, which is different from that of Example 1 in that: Replace the medium roughening treatment step in Example 1 with grinding and brushing plus micro-etching treatment.

[0091] Use the method of grinding and brushing plus micro-etching to treat the PCB board. The grinding and brushing uses a nylon grinding brush, and the grinding and brushing time is 30 s. The concentration of sulfuric acid in the micro-etching solution is controlled at 3%, the concentration of sodium persulfate is controlled at 30 g / L, the micro-etching time is 60 s, and the temperature is 30 °C.

[0092] Comparative Example 2 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: No surface conditioner is added to the medium roughening chemical solution.

[0093] Comparative Example 3 A medium roughening treatment process for the surface of a PCB board, which is different from that of Example 1 in that: Dry the surface of the PCB board with an air flow at 80 °C and a flow rate of 18 m / s, and the drying time is 45 s.

[0094] In each of the examples and comparative examples, 5 test boards of the same specification were used. After the treatment, the etching amount and roughness were measured. The etching amount was calculated by measuring the mass change of the PCB board before and after etching. During the etching process, the copper layer material was corroded and removed, resulting in a decrease in mass. According to the mass difference, the volume of the etched copper layer could be calculated, and then the etching amount could be obtained. The stylus of the contact profilometer moved on the copper surface of the PCB board. The stylus moved up and down with the microscopic undulations of the copper surface. The instrument converted this displacement change into an electrical signal, and after processing, the surface roughness parameter was obtained. Based on the average values of the etching amount and roughness, the cumulative difference was calculated. For example, when the etching amounts were 0.75, 0.80, 0.85, 0.90, and 0.95 respectively, the average value was 0.85, and the cumulative difference was 0.3.

[0095] One PCB board was prepared by the methods of Example 1 and Comparative Example 3 respectively, and its surface quality after drying was observed.

[0096] One PCB board was prepared by the methods of Example 1 and Comparative Example 1 respectively. The two PCB boards were subjected to a scanning electron microscope (SEM) project, and the copper surface states under the SEM images were compared.

[0097] Table 1 Detection data Average etching amount / μm Average roughness / Ra value Cumulative difference in etching amount Cumulative difference in roughness 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 Table 2 Surface quality of PCB boards under different drying methods Example 1 Good surface quality Comparative Example 3 There is local thermal deformation Combining Example 1 and Comparative Example 1 and combining Table 1 and Figure 1-2 It can be seen that after the medium roughening treatment, the copper surface presents a microscopic rough structure of a network plus pore-like etched layer; the copper surface after the grinding brush + micro-etching treatment presents a flaky concave-convex structure. Observing its SEM image, it can be seen that there is a large-area planar structure and a small part of the rough structure, which proves that the surface roughness is uneven, the rough structure is unevenly distributed on the copper surface, and the roughness is not fine enough. The former network pore-like structure can firmly hold the dry film or ink, form an inlaid structure to lock the surface to improve the bonding force. This comparative example can prove that under the premise of almost the same etching amount, the Ra value of the roughness has a significant increase in the medium roughening process, and both the etching amount and the roughness are more stable with a very small fluctuation range.

[0098] Combining Example 1 and Comparative Example 2 and combining Table 1, it can be seen that the inhibition of the reaction rate characteristic of the surface conditioner can effectively avoid the too-fast reaction between the copper surface and the chemical solution during the medium roughening process and can achieve the effects of promoting uniform etching and changing the surface properties. By inhibiting the reaction rate, the roughening degree of the copper surface can be precisely controlled to ensure the quality of the PCB board. The enhanced adsorption ions and dispersion effects of the surface conditioner make the copper etching reaction evenly distributed on the copper surface.

[0099] Combining Example 1 and Comparative Example 3 and referring to Table 2, it can be seen that a temperature of 40 - 50°C can not only cause the moisture on the surface of the PCB board to evaporate, but also will not cause thermal damage to the PCB board due to high temperature, such as deforming the board material. At this temperature, drying for 30 - 60 s with an air flow rate of 15 - 20 m / s can accelerate the detachment of moisture from the surface of the PCB board, effectively removing the residual moisture after the water washing and pickling steps. A fast and appropriate drying process can prevent the copper surface from oxidizing in a humid environment, which is beneficial to the good bonding with the dry film and ink in the subsequent process, ensuring the functionality and stability of the PCB board.

[0100] Combining Examples 1 - 11 and referring to Table 1, it can be seen that the average etching amount of Examples 1 - 11 is between 0.77 - 0.86 μm, and the fluctuation range is relatively small. This indicates that under different changes in the medium roughening potion formula, the control ability of the entire medium roughening treatment process for the etching amount and roughness is relatively stable. Comparing Examples 1 - 3, it can be found that when the proportions of 4 - hydroxypiperidine, p - toluenesulfonic acid, 5 - phenyltetrazole, and tetrazole in the surface conditioner vary within the scope of this application, the changes in the etching amount and roughness are relatively stable, which is beneficial to the uniform adhesion of the subsequent dry film or ink on the copper surface. Nano - silica was added in Example 4, ethylenediaminetetramethylphosphonic acid was added in Example 5, and mercaptoethanol was added in Example 6. The addition of these additives all increased the etching amount and roughness, while the cumulative difference in the etching amount and roughness became smaller, indicating that the surface etching effect was improved and the uniformity of the surface morphology was higher.

[0101] Combining Example 1 and Examples 11 - 16 and referring to Table 1, it can be seen that Examples 12 - 16 mainly changed process parameters such as the concentration of the medium roughening potion or the pickling concentration. Compared with Example 1, the concentration of the medium roughening potion was changed in Example 12, the concentration of sulfuric acid for the first pickling was changed in Examples 13 - 14, and the concentration of sulfuric acid for the second pickling was changed in Examples 15 - 16. These changes led to variations in the etching amount, but within the process scope of this application, an excellent roughening degree and a uniform surface morphology could still be achieved, maintaining the relative stability of the etching amount and enabling the roughness to be maintained at a level beneficial to subsequent processing.

[0102] This specific embodiment is only an explanation of this application and is not a limitation to this application. Those skilled in the art can make modifications without creative contributions to this embodiment according to needs after reading this specification, but as long as it is within the scope of the claims of this application, it is 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 coarsening treatment: Spray the medium coarsening solution evenly on the surface of the PCB board. The temperature of the medium coarsening solution is controlled at 35-45°C and the spraying time is 30s-120s. The medium coarsening solution contains sulfuric acid, anhydrous copper sulfate and surface adjuster. 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.

2. The PCB surface roughening process according to claim 1, characterized in that: The components of the medium roughening solution include 3-8% sulfuric acid, 0.001-0.005% anhydrous copper sulfate, 2-3% surface adjuster, and the rest is deionized water.

3. The PCB surface roughening process according to claim 2, characterized in that: The medium-coarsening solution also includes 5-8% hydrogen peroxide by mass. When hydrogen peroxide is added to the medium-coarsening solution, the concentration of sulfuric acid is controlled at 5-10%.

4. The PCB surface roughening process according to claim 2, characterized in that: The surface adjuster includes 5-7% of 4-hydroxypiperidine, 10-16% of 4-methylbenzenesulfonic acid, 1-2% of 5-phenyltetrazolyl, 0.3-0.5% of tetrazole, and the rest is deionized water.

5. The PCB surface roughening process according to claim 4, characterized in that: The surface adjuster also includes 1-3% nano silicon dioxide by mass percentage, and the particle size of the nano silicon dioxide is 20-30nm.

6. The PCB surface roughening process according to claim 4, characterized in that: The surface adjuster also includes 2-4% by mass of ethylenediaminetetramethylenephosphonic acid.

7. The PCB surface roughening process according to claim 4, characterized in that: The surface conditioning agent also includes 1-3% of mercaptoethanol by mass.

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

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

10. The PCB surface roughening process according to claim 1, characterized in that: 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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