Glue residue removing process of printed circuit board

Abstract

The invention relates to the technical field of printed circuit boards, and particularly discloses a glue residue removing process of a printed circuit board. The glue residue removing process mainly comprises the following steps: placing the printed circuit board in a bulky working solution, dipping, taking out, draining, and washing with water; placing in a degumming working solution, dipping, taking out, draining, and washing with water; putting into a pre-neutralization working solution, dipping, taking out, draining, and washing with water; and putting into a neutralization working solution, dipping, taking out, draining, washing and drying to finish the glue residue removal process. The bulking working solution is mainly prepared from the following raw materials: a bulking agent and water; the swelling agent is mainly prepared from the following raw materials: dipropylene glycol dimethyl ether, fluorocarbon modified p-aminoanisole and sodium didecyl sulfosuccinate. According to the glue residue removing technology, through mutual cooperation of all the steps, on the basis that the printed circuit board is not affected, the glue residue removing technology has the advantages of being high in glue removing speed, thorough in glue residue removing, good in glue residue removing effect, capable of roughening the surface and enhancing the binding force with copper, and the market requirement is met.

Description

Technical Field

[0001] This application relates to the technical field of printed circuit boards, and more specifically, it relates to a process for removing glue residues from printed circuit boards. Background Art

[0002] Printed circuit boards are important components of modern electronic products, and are also the support for electronic components and the carrier for electrical connections, and are widely used in fields such as communication, computers, electronic equipment, aerospace, etc. Printed circuit boards can be divided into single-layer, double-layer, four-layer, six-layer and multi-layer according to the number of layers. For multi-layer printed circuit boards, during their manufacturing process, drilling is inevitably required to achieve interconnection between layers. For the printed circuit board obtained after drilling the printed circuit board, glue residues are likely to form on its surface and in the drill holes. At this time, it is necessary to remove the glue residues on the printed circuit board, and then perform electroless copper plating to reduce the influence of the glue residues on the bonding force between the printed circuit board and copper. The existing glue residue removal process, such as the horizontal glue removal process for printed circuit boards disclosed in CN112867276A, which undergoes swelling, cleaning, pre-neutralization, cleaning, neutralization, and cleaning to complete the glue residue removal process, and the glue removal rate is 0.4mg / cm 2 , and the glue removal rate is insufficient and still needs to be improved. Summary of the Invention

[0003] In order to improve the glue removal rate, this application provides a process for removing glue residues from printed circuit boards, and adopts the following technical solutions: A process for removing glue residues from printed circuit boards mainly includes the following steps: S1. Place the printed circuit board in the swelling working solution, immerse it for 5 - 10 minutes, take it out to drain water, and wash it with water; S2. Place the printed circuit board after swelling treatment in the glue removal working solution, immerse it for 10 - 20 minutes, take it out to drain water, and wash it with water; S3. Place the printed circuit board after glue removal treatment in the pre-neutralization working solution, immerse it for 1 - 5 minutes, take it out to drain water, and wash it with water; S4. Place the printed circuit board after pre-neutralization treatment in the neutralization working solution, immerse it for 5 - 10 minutes, take it out to drain water, wash it with water, and dry it to complete the glue residue removal process; The temperature of the swelling working solution is 50 - 70°C, and the swelling working solution is mainly made of the following raw materials by weight percentage: swelling agent 10 - 20%, and the balance is water; The swelling agent is mainly made of the following raw materials by weight: 60 - 80 parts of dipropylene glycol dimethyl ether, 20 - 40 parts of fluorocarbon-modified p-anisidine, and 3 - 6 parts of sodium diisodecyl sulfosuccinate; the fluorocarbon-modified p-anisidine is obtained by treating p-anisidine with 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propionyl fluoride.

[0004] In the desmear process of the printed circuit board of the present application, first, the smear on the printed circuit board is loosened, then the smear is removed, and then pre-neutralization and neutralization are carried out to obtain a desmeared printed circuit board. And through the mutual cooperation between each step, without affecting the printed circuit board, the desmearing rate is > 0.5 mg / cm 2 , which has the advantage of fast desmearing rate, and the printed circuit board has clean desmearing during drilling, and the surface texture of the printed circuit board is roughened, which is beneficial to improving the subsequent electroless copper plating process, making the desmear process show better desmearing effect.

[0005] For the swelling agent of the present application, dipropylene glycol dimethyl ether and fluorocarbon-modified anisidine are added to the raw materials, and the synergistic effect between the two is utilized to reduce the molecular bond force between the smears and between the smear and the printed circuit board, and to carry out softening and swelling. It also fully penetrates the smear, enhances the contact area between the smear and the swelling agent, promotes the depolymerization of the smear, reduces the difficulty of desmearing, and effectively removes the smear with the cooperation of the desmearing working solution, improving the desmearing effect.

[0006] Optionally, the fluorocarbon-modified anisidine is prepared by the following method: Under the protection of inert gas, chloroform and isopropanol are mixed, anisidine is added and mixed, triethylamine is added and mixed, the temperature is lowered to 0 - 5 °C, and 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propionyl fluoride is added dropwise. The dropping time of 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propionyl fluoride is 20 - 40 min. After the dropping is completed, the temperature is raised to room temperature, and stirring is carried out for 4 - 6 h. Water is added, and stirring is carried out for 30 - 50 min. Then, vacuum distillation is carried out to obtain fluorocarbon-modified p-phenylenediamine.

[0007] Optionally, the weight ratio of anisidine, 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propionyl fluoride, triethylamine, water, chloroform, and isopropanol is (40 - 60):(55 - 80):(5 - 15):(5 - 15):(70 - 130):(70 - 130).

[0008] By adopting the above technical solution, a substitution reaction occurs between the amino group in anisidine and the propionyl fluoride group in 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propionyl fluoride, so that 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propionyl fluoride is grafted into anisidine, introducing a fluorine group. The fluorocarbon-modified anisidine obtained by the preparation method of the present application is easy to prepare, and increases the purity and reaction yield, ensures the stability of the fluorocarbon-modified anisidine, improves the use effect of the swelling agent, and enhances the desmearing rate and desmearing effect of the desmear process.

[0009] Optionally, the temperature of the degumming working solution is 60-80 °C, and the degumming working solution is mainly made of the following raw materials in parts by weight: 1000 parts of water, 20-50 parts of sodium hydroxide, and 50-80 parts of potassium permanganate.

[0010] By adopting the above technical solution, the content of sodium hydroxide and potassium permanganate in the degumming working solution is optimized. Utilizing the strong oxidizing property of potassium permanganate, the glue residues on the drilled holes and the surface of the printed circuit board are oxidized and decomposed, enhancing the bonding force between the hole wall and copper. Moreover, the temperature of the degumming working solution is optimized, reducing the impact on the degumming rate due to too low temperature and also reducing the damage to the printed circuit board caused by too high temperature.

[0011] In multiple embodiments, in the raw materials of the degumming working solution, the addition amount of sodium hydroxide is 40 parts of water, and the addition amount of potassium permanganate is 65 parts. It can also set the addition amount of sodium hydroxide to 20 parts, 25 parts, 30 parts, 35 parts, 45 parts, 50 parts according to needs. It can also set the addition amount of potassium permanganate to 50 parts, 55 parts, 60 parts, 70 parts, 75 parts, 80 parts according to needs, but it is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0012] Optionally, the pre-neutralization working solution is mainly made of the following raw materials in weight percentages: 1-5% of sulfuric acid, 3-8% of neutralization medicinal liquid, and the balance is water.

[0013] By adopting the above technical solution, the sulfuric acid and neutralization medicinal liquid in the pre-neutralization working solution are optimized. It can not only remove the residual potassium permanganate, potassium manganate, and manganese dioxide on the printed circuit board, but also pre-adjust the pH value to ensure the treatment effect of the subsequent neutralization working solution on the printed circuit board. In multiple embodiments, in the raw materials of the pre-neutralization working solution, the mass content of sulfuric acid is 2%, and the mass content of the neutralization medicinal liquid is 6%. It can also set the mass content of sulfuric acid to 1%, 3%, 4%, 5% according to needs. It can also set the mass content of the neutralization medicinal liquid to 3%, 4%, 5%, 7%, 8% according to needs, but it is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0014] Optionally, the temperature of the neutralization working solution is 30-60 °C, and the neutralization working solution is mainly made of the following raw materials in weight percentages: 3-10% of sulfuric acid, 10-20% of neutralization medicinal liquid, and the balance is water.

[0015] By adopting the above technical solution, the sulfuric acid content and neutralization medicinal liquid content in the neutralization working solution are optimized to ensure the effective removal of the residual potassium permanganate, potassium manganate, and manganese dioxide on the printed circuit board. At the same time, the temperature of the neutralization working solution is optimized, not only ensuring the treatment effect of the neutralization working solution, but also reducing the situation that the water volatilizes too fast due to too high temperature.

[0016] In multiple embodiments, in the raw materials of the neutralization working solution, the mass content of sulfuric acid is 6%, and the mass content of the neutralization medicament solution is 15%. Optionally, the mass content of sulfuric acid can be set to 3%, 5%, 7%, 10% as needed, and the mass content of the neutralization medicament solution can also be set to 10%, 13%, 18%, 20% as needed. However, it is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0017] Optionally, the neutralization medicament solution is mainly made of the following raw materials in parts by weight: 20 - 30% hydrogen peroxide, 0.1 - 0.5% corrosion inhibitor, 0.1 - 0.5% chelating agent, 0.1 - 0.3% surfactant, and the balance is water.

[0018] By adopting the above technical solution, the raw materials and raw material ratios of the neutralization medicament solution are optimized. Hydrogen peroxide can react with the residual potassium permanganate on the printed circuit board to form potassium manganate, further react with potassium manganate to form manganese dioxide, and then further react with manganese dioxide to form manganese ions, improving the backlight level and quality of the printed circuit board for removing gum residues.

[0019] In multiple embodiments, in the raw materials of the neutralization medicament solution, the mass content of hydrogen peroxide is 25%, the mass content of the corrosion inhibitor is 0.3%, the mass content of the chelating agent is 0.3%, and the mass content of the surfactant is 0.2%. Optionally, the mass content of hydrogen peroxide can be set to 20%, 22%, 28%, 30% as needed, the mass content of the corrosion inhibitor can also be set to 0.1%, 0.2%, 0.4%, 0.5% as needed, the mass content of the chelating agent can also be set to 0.1%, 0.2%, 0.4%, 0.5% as needed, and the mass content of the surfactant can also be set to 0.1%, 0.15%, 0.25%, 0.3% as needed. However, it is not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0020] Optionally, the corrosion inhibitor is one or more of imidazole, 2 - phenylimidazole, N - methylimidazole, 2 - (p - chlorobenzyl)pyridinium methylbenzotriazole.

[0021] By adopting the above technical solution, the corrosion inhibitor is optimized, facilitating the selection of the corrosion inhibitor. Moreover, imidazole, 2 - phenylimidazole, N - methylimidazole, and 2 - (p - chlorobenzyl)pyridinium methylbenzotriazole can all adsorb on the surface of the printed circuit board and form a tight protective barrier, improving the corrosion resistance and integrity of the printed circuit board and reducing the etching effect of the neutralization medicament solution on the printed circuit board.

[0022] Optionally, the chelating agent is one or more of aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, sodium ethylenediaminetetramethylenephosphonate, sodium ethylenediaminetetraacetate, and sodium diethylenetriaminepentaacetate.

[0023] By adopting the above technical solution, the chelating agent is optimized, which facilitates the selection of the chelating agent. Moreover, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, sodium ethylenediaminetetramethylenephosphonate, sodium ethylenediaminetetraacetate, and sodium diethylenetriaminepentaacetate can all complex with metal ions, reduce the interference of metal ions on hydrogen peroxide, and ensure the stability and reliability of the neutralizing liquid medicine.

[0024] Optionally, the chelating agents are aminotrimethylenephosphonic acid and ethylenediaminetetramethylenephosphonic acid, and the weight ratio of aminotrimethylenephosphonic acid to ethylenediaminetetramethylenephosphonic acid is (1-3):(1-3). In multiple embodiments, the weight ratio of aminotrimethylenephosphonic acid to ethylenediaminetetramethylenephosphonic acid is 1:1, and the weight ratio can also be set to 1:2, 1:3, 2:1, 2:3, 3:1, 3:2 as needed, but it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0025] Optionally, the surfactant is one or more of surfactant AEO3, surfactant AEO5, surfactant APG0810, surfactant APG1214, and surfactant LD500.

[0026] By adopting the above technical solution, the surfactant is optimized, which facilitates the selection of the surfactant. Moreover, surfactant AEO3, surfactant AEO5, surfactant APG0810, surfactant APG1214, and surfactant LD500 can all play a dispersing role, ensure the stability of the neutralizing liquid medicine, and also ensure the stability and use effect of the pre-neutralizing working liquid and the neutralizing working liquid.

[0027] Optionally, in step S1, during the process of treating the printed circuit board with the swelling working liquid, the content of the swelling agent in the swelling working liquid is detected every 10-15 h, and the swelling agent is replenished in the swelling working liquid to the original content until 100-300 m of the printed circuit board is treated per 1 L of the swelling working liquid 2 and the swelling working liquid is updated.

[0028] By adopting the above technical solution, the content of the swelling agent in the swelling working liquid is detected, which ensures the stability of the effective component concentration during the long-term use of the swelling working liquid, ensures that the expected effect can be achieved each time the printed circuit board is treated, guarantees the swelling effect, and reduces the waste liquid discharge and cost. At the same time, when the swelling working liquid is used to a certain extent, the swelling working liquid is updated to reduce the reduction of its use effect on the printed circuit board due to the long-term use of the swelling working liquid.

[0029] Optionally, the content of the swelling agent in the swelling working fluid is detected by spectrophotometry. The swelling agent contains organic substances, and the organic substances can selectively absorb light. Different contents of the swelling agent in the swelling working fluid have different absorbance values, and there is a one-to-one correspondence. Using spectrophotometry to detect the content of the swelling agent in the swelling working fluid is simple, practical, and accurate.

[0030] Optionally, in step S2, during the process of treating the printed circuit board with the degumming working fluid, every 10 - 15 h, the sulfuric acid content and potassium permanganate content in the degumming working fluid are detected, and sulfuric acid and potassium permanganate are replenished in the degumming working fluid to the original content until every 1 L of the degumming working fluid treats 100 - 300 m 2 of the printed circuit board, and the degumming working fluid is updated.

[0031] By adopting the above technical solution, detecting the sulfuric acid and potassium permanganate contents in the degumming working fluid can ensure the stability of the concentration of the active ingredients during the long-term use of the degumming working fluid, ensure that the expected effect can be achieved each time the printed circuit board is treated, improve the degumming efficiency, reduce the waste liquid discharge, and lower the cost. At the same time, when the degumming working fluid is used to a certain extent, the degumming working fluid is updated to reduce the failure due to the long-term use of the degumming working fluid and ensure the consistency and reliability of the degumming process.

[0032] Optionally, the sulfuric acid content in the degumming working fluid is detected by titration, and the potassium permanganate content in the degumming working fluid is detected by titration. Titration is carried out by using the acidity of sulfuric acid and the oxidizing property of potassium permanganate, and detecting the sulfuric acid content and potassium permanganate content is simple, practical, and accurate.

[0033] Optionally, in step S3, during the process of treating the printed circuit board with the pre-neutralization working fluid, every 1 - 3 h, the content of the neutralizing medicine liquid in the pre-neutralization working fluid is detected, and the neutralizing medicine liquid is replenished in the pre-neutralization working fluid to the original content until every 1 L of the pre-neutralization working fluid treats 3 - 10 m 2 of the printed circuit board, and the pre-neutralization working fluid is updated.

[0034] By adopting the above technical solution, detecting the content of the neutralizing medicine liquid in the pre-neutralization working fluid can ensure the stability of the concentration of the active ingredients during the long-term use of the pre-neutralization working fluid, reduce the waste liquid discharge, and lower the cost. At the same time, when the pre-neutralization working fluid is used to a certain extent, the pre-neutralization working fluid is updated to reduce the decline in effect due to the long-term use of the pre-neutralization working fluid.

[0035] Optionally, the content of the neutralizing liquid medicine in the pre-neutralizing working liquid is detected by titration. The neutralizing liquid medicine contains hydrogen peroxide, and the oxidation-reduction property of hydrogen peroxide is used for titration, and the content of the neutralizing liquid medicine is detected, which is simple, practical and accurate.

[0036] Optionally, in step S4, during the process of treating the printed circuit board with the neutralizing working liquid, every 6-10 hours, the content of the neutralizing liquid medicine in the neutralizing working liquid is detected, and the neutralizing liquid medicine is supplemented in the neutralizing working liquid to the original content until 10-50 m of the printed circuit board per 1 L of the neutralizing working liquid 2 is processed, and the neutralizing working liquid is updated.

[0037] By adopting the above technical solution, the content of the neutralizing liquid medicine in the neutralizing working liquid is detected, which ensures the stability of the concentration of the active ingredient during the long-term use of the neutralizing working liquid, can also reduce the waste liquid discharge and lower the cost. At the same time, when the neutralizing working liquid is used to a certain extent, the neutralizing working liquid is updated to reduce the decline in effect caused by the long-term use of the neutralizing working liquid.

[0038] Optionally, the content of the neutralizing liquid medicine in the neutralizing working liquid is detected by titration.

[0039] In summary, the present application has at least the following beneficial effects: In the process of removing the glue residue of the printed circuit board of the present application, dipropylene glycol dimethyl ether and fluorocarbon-modified p-anisidine are added to the raw materials of the swelling agent, and the synergistic effect between the two is utilized to fully penetrate, soften and expand the glue residue, reduce the molecular bond force between the glue residues and between the glue residue and the printed circuit board, promote the depolymerization of the glue residue, and reduce the difficulty of removing the glue. And with the cooperation of the degumming working liquid, without affecting the printed circuit board, the degumming rate is > 0.5 mg / cm 2 , having the advantages of fast degumming rate, and also having the characteristics of clean degumming residue, good degumming residue removal effect, roughened surface and enhanced bonding force with copper, meeting the market demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a picture of the drilled holes of the printed circuit board before removing the glue residue in Embodiment 1 of the present application.

[0041] Figure 2 is a picture of the drilled holes of the printed circuit board after removing the glue residue in Embodiment 1 of the present application.

[0042] Figure 3 is a picture of the surface of the printed circuit board before removing the glue residue in Embodiment 1 of the present application.

[0043] Figure 4 is a picture of the surface of the printed circuit board after removing the glue residue in Embodiment 1 of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] To make this application easier to understand, the following will further elaborate on this application in combination with embodiments. These embodiments are only illustrative and not limited to the application scope of this application. The raw materials or components used in this application can be obtained through commercial channels or conventional methods without special instructions.

[0045] Preparation Example Preparation Example 1 A fluorocarbon-modified p-anisidine is prepared by the following method: Under a nitrogen protection at a rotation speed of 400 r / min, 100 kg of isopropanol is added to 100 kg of chloroform, and stirred for 1 min. 50 kg of p-anisidine is added and stirred for 5 min. 10 kg of triethylamine is added and stirred for 2 min. The temperature is lowered to 2 °C, and 69 kg of 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propionyl fluoride is added dropwise, and the dropping time of 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propionyl fluoride is 30 min. After the dropping is completed, the temperature is raised to 23 °C and stirred for 5 h. 10 kg of water is added and stirred for 40 min. Then, chloroform, isopropanol and water are removed by vacuum distillation to obtain fluorocarbon-modified p-phenylenediamine.

[0046] Preparation Example 2 A fluorocarbon-modified p-anisidine is prepared by the following method: Under a nitrogen protection at a rotation speed of 400 r / min, 130 kg of isopropanol is added to 70 kg of chloroform, and stirred for 1 min. 40 kg of p-anisidine is added and stirred for 5 min. 15 kg of triethylamine is added and stirred for 2 min. The temperature is lowered to 2 °C, and 55 kg of 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propionyl fluoride is added dropwise, and the dropping time of 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propionyl fluoride is 20 min. After the dropping is completed, the temperature is raised to 23 °C and stirred for 4 h. 5 kg of water is added and stirred for 30 min. Then, chloroform, isopropanol and water are removed by vacuum distillation to obtain fluorocarbon-modified p-phenylenediamine.

[0047] Preparation Example 3 A fluorocarbon-modified p-anisidine is prepared by the following method: Under a nitrogen protection at a rotational speed of 400 r / min, 70 kg of isopropanol was added to 130 kg of chloroform and stirred for 1 min. 60 kg of p-anisidine was added and stirred for 5 min. 5 kg of triethylamine was added and stirred for 2 min. The temperature was lowered to 2 °C, and 80 kg of 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propionyl fluoride was added dropwise over 40 min. After the addition was complete, the temperature was raised to 23 °C and stirred for 6 h. 15 kg of water was added and stirred for 50 min. Then, chloroform, isopropanol, and water were removed by vacuum distillation to obtain fluorocarbon-modified p-phenylenediamine. Example

[0048] Example 1 A process for removing glue residues from a printed circuit board mainly includes the following steps: S0. Prepare a printed circuit board, a swelling agent, and a neutralizing solution.

[0049] Among them, the printed circuit board is a printed circuit board after drilling and drying, the printed circuit board is an FR-4 printed circuit board, and the Tg value of the printed circuit board is 180 °C.

[0050] The swelling agent is made from the following raw materials by weight: 70 parts of dipropylene glycol dimethyl ether, 30 parts of fluorocarbon-modified p-anisidine, and 5 parts of sodium di-n-decyl sulfosuccinate. And the fluorocarbon-modified p-anisidine is obtained by using the method of Preparation Example 1.

[0051] The swelling agent is prepared by the following method: Add fluorocarbon-modified p-anisidine and sodium di-n-decyl sulfosuccinate to dipropylene glycol dimethyl ether and stir for 2 min to obtain the swelling agent.

[0052] The neutralizing solution is made from the following raw materials by weight: 25% hydrogen peroxide, 0.3% corrosion inhibitor, 0.3% chelating agent, 0.2% surfactant, and the balance is water. And the corrosion inhibitor is imidazole; the chelating agent is aminotrimethylene phosphonic acid and ethylenediaminetetramethylene phosphonic acid, and the weight ratio of aminotrimethylene phosphonic acid to ethylenediaminetetramethylene phosphonic acid is 1:1; the surfactant is surfactant APG0810.

[0053] The neutralizing solution is prepared by the following method: Add water, corrosion inhibitor, chelating agent, and surfactant to hydrogen peroxide with a mass concentration of 30% and stir for 2 min to obtain the neutralizing solution.

[0054] S1. In the swelling tank, place the printed circuit board in the swelling working solution at a temperature of 60 °C, immerse it for 8 min, take it out and drain for 30 s, and wash it 3 times with water.

[0055] Among them, the bulking working fluid is made of raw materials with the following weight percentages: 15% of the bulking agent, and the balance is water. And it is prepared by the following method: adding the bulking agent to water and stirring for 2 minutes to obtain the bulking working fluid.

[0056] During the process of treating the printed circuit board with the bulking working fluid, every 12 hours, the content of the bulking agent in the bulking working fluid is detected by spectrophotometry, and the bulking agent is replenished in the bulking working fluid to the original content until every 1 L of the bulking working fluid treats 200 m 2 of the printed circuit board. At this time, the bulking working fluid in the bulking tank is updated.

[0057] S2. In the degumming tank, place the printed circuit board after bulking treatment in the degumming working fluid at a temperature of 70 °C, soak for 15 minutes, take it out and drain for 30 seconds, and wash it 3 times with water.

[0058] Among them, the degumming working fluid is made of raw materials with the following weight parts: 1000 parts of water, 40 parts of sodium hydroxide, and 65 parts of potassium permanganate. And it is prepared by the following method: adding sodium hydroxide to water, stirring for 10 minutes, adding potassium permanganate, and stirring for 5 minutes to obtain the degumming working fluid.

[0059] During the process of treating the printed circuit board with the degumming working fluid, every 12 hours, the sulfuric acid content and potassium permanganate content in the degumming working fluid are detected by titration, and sulfuric acid and potassium permanganate are replenished in the degumming working fluid to the original content until every 1 L of the degumming working fluid treats 200 m 2 of the printed circuit board. At this time, the degumming working fluid in the degumming tank is updated.

[0060] S3. In the pre-neutralization tank, place the printed circuit board after degumming treatment in the pre-neutralization working fluid, soak for 3 minutes, take it out and drain for 30 seconds, and wash it 4 times with water.

[0061] Among them, the pre-neutralization working fluid is made of raw materials with the following weight percentages: 2% of sulfuric acid, 6% of the neutralization liquid, and the balance is water. And it is prepared by the following method: adding the neutralization liquid to water and stirring for 5 minutes to obtain the pre-neutralization working fluid.

[0062] During the process of treating the printed circuit board with the pre-neutralization working fluid, every 2 hours, the content of the neutralization liquid in the pre-neutralization working fluid is detected by titration, and the neutralization liquid is replenished in the pre-neutralization working fluid to the original content until every 1 L of the pre-neutralization working fluid treats 5 m 2 of the printed circuit board. At this time, the pre-neutralization working fluid in the pre-neutralization tank is updated.

[0063] S4. In the neutralization tank, place the pre-neutralized printed circuit board in the neutralization working solution at a temperature of 50°C, soak for 8 minutes, take it out and drain for 30 seconds, wash 5 times with water, and dry to complete the process of removing the glue residue, obtaining a printed circuit board with the glue residue removed.

[0064] Among them, the neutralization working solution is made of raw materials with the following weight percentages: 6% sulfuric acid, 15% neutralization medicine solution, and the balance is water. And it is prepared by the following method: Add the neutralization medicine solution to water and stir for 5 minutes to obtain the neutralization working solution.

[0065] During the process of treating the printed circuit board with the neutralization working solution, every 8 hours, use the titration method to detect the content of the neutralization medicine solution in the neutralization working solution, and supplement the neutralization medicine solution in the neutralization working solution to the original content until 30 m of printed circuit board is processed per 1 L of the neutralization working solution. 2 At this time, update the neutralization working solution in the neutralization tank.

[0066] Example 2 A process for removing the glue residue of a printed circuit board, which is different from Example 1 in that the raw material ratio of the swelling agent is different, and the swelling agent is made of the following raw materials in parts by weight: 60 parts of dipropylene glycol dimethyl ether, 40 parts of fluorocarbon-modified p-anisidine, and 3 parts of sodium diisodecyl sulfosuccinate.

[0067] Example 3 A process for removing the glue residue of a printed circuit board, which is different from Example 1 in that the raw material ratio of the swelling agent is different, and the swelling agent is made of the following raw materials in parts by weight: 80 parts of dipropylene glycol dimethyl ether, 20 parts of fluorocarbon-modified p-anisidine, and 6 parts of sodium diisodecyl sulfosuccinate.

[0068] Example 4 A process for removing the glue residue of a printed circuit board, which is different from Example 1 in that among the raw materials of the swelling agent, the source of fluorocarbon-modified p-anisidine is different, and the fluorocarbon-modified p-anisidine is obtained by the method of Preparation Example 2.

[0069] Example 5 A process for removing the glue residue of a printed circuit board, which is different from Example 1 in that among the raw materials of the swelling agent, the source of fluorocarbon-modified p-anisidine is different, and the fluorocarbon-modified p-anisidine is obtained by the method of Preparation Example 3.

[0070] Comparative Example Comparative Example 1 A process for removing the glue residue of a printed circuit board, which is different from Example 1 in that among the raw materials of the swelling agent, an equal amount of dipropylene glycol dimethyl ether is used to replace fluorocarbon-modified p-anisidine.

[0071] Comparative Example 2 A desmear process for a printed circuit board, which is different from that of Example 1 in that in the raw materials of the swelling agent, dipropylene glycol dimethyl ether is replaced with p-anisidine modified with fluorocarbon in equal amounts.

[0072] Comparative Example 3 A desmear process for a printed circuit board, which is different from that of Example 1 in that in the raw materials of the swelling agent, p-anisidine is replaced with p-anisidine modified with fluorocarbon in equal amounts.

[0073] Performance detection (1) Use the method of Example 1 to perform desmear treatment on the printed circuit board after drilling and drying to obtain a desmear printed circuit board. Observe the drilled holes and the surface of the printed circuit board after drilling and drying and the desmear printed circuit board. The picture of the drilled holes of the printed circuit board after drilling and drying is shown in Figure 1 , that is, the picture of the drilled holes of the printed circuit board before desmear is shown in Figure 1 ; the picture of the drilled holes of the desmear printed circuit board is shown in Figure 2 , that is, the picture of the drilled holes of the printed circuit board after desmear is shown in Figure 2 ; the picture of the surface of the printed circuit board after drilling and drying is shown in Figure 3 , that is, the picture of the surface of the printed circuit board before desmear is shown in Figure 3 ; the picture of the surface of the desmear printed circuit board is shown in Figure 4 , that is, the picture of the surface of the printed circuit board after desmear is shown in Figure 4 .

[0074] Combined with Figure 1 , Figure 2 , it can be seen that after the printed circuit board is treated by the desmear process, the gum residue generated by drilling can be removed, so that a good contact conduction is formed between the subsequent inner layer copper and the hole copper. Combined with Figure 3 , Figure 4 , it can be seen that after the printed circuit board is treated by the desmear process, the surface can be roughened, so that the subsequent electroless copper deposition has a good combination with the printed circuit board.

[0075] (2) Respectively take the desmear printed circuit boards obtained in Step S4 of Examples 1-5 and Comparative Examples 1-3, and detect the desmear rate and desmear effect of the desmear printed circuit boards. The detection results are shown in Table 1.

[0076] Among them, the desmear rate / (mg / cm 2 ) = (the weight of the printed circuit board before desmear - the weight of the printed circuit board after desmear) / the area of the printed circuit board.

[0077] The desmear effect is divided into five grades, and the grades are from high to low in turn: excellent, good, general, poor, extremely poor.

[0078] Table 1 Test Results Test Items <![CDATA[Etch rate / (mg / cm 2 )]]> Glue Removal Effect Example 1 0.583 Excellent Example 2 0.565 Excellent Example 3 0.534 Excellent Example 4 0.552 Excellent Example 5 0.558 Excellent Comparative Example 1 0.363 Average Comparative Example 2 0.455 Good Comparative Example 3 0.427 Good As can be seen from Table 1, the desmear printed circuit board obtained by the desmear process of this application has a relatively high desmear rate, and the desmear rate is 0.534 - 0.583 mg / cm 2 , showing the advantage of a fast desmear rate. Moreover, by using the desmear process of this application, the desmear effect on the printed circuit board is excellent, the desmear is clean, and the surface texture is roughened, which is beneficial to the subsequent copper deposition process, making the desmear process show a better desmear effect and meet the market demand.

[0079] Compare Comparative Examples 1 - 2 and Example 1. In Comparative Example 1, dipropylene glycol dimethyl ether is added to the raw material of the blowing agent; in Comparative Example 2, fluorocarbon-modified anisole is added to the raw material of the blowing agent; in Example 1, dipropylene glycol dimethyl ether and fluorocarbon-modified anisole are added to the raw material of the blowing agent. It can be seen from this that by adding dipropylene glycol dimethyl ether and fluorocarbon-modified anisole to the raw material of the blowing agent at the same time and utilizing their synergistic effect, the desmear rate and desmear effect can be improved.

[0080] Compare Comparative Example 3 and Example 1. In Comparative Example 3, anisole is added to the raw material of the blowing agent; in Example 1, fluorocarbon-modified anisole is added to the raw material of the blowing agent. It can be seen from this that by treating anisole with 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propionyl fluoride and introducing active groups such as fluorine groups, the interaction with dipropylene glycol dimethyl ether can be enhanced, the desmear rate can be increased, and it is beneficial to the desmear process of the printed circuit board.

[0081] It should be noted that the above-described embodiments are only used to explain this application and do not constitute any limitation to this application. This application has been described by referring to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words rather than limiting words. Modifications can be made to this application within the scope of the claims of this application as stipulated, and the present invention can be revised without departing from the scope and spirit of this application. Although the described application herein relates to specific methods, materials, and embodiments, it does not mean that this application is limited to the specific examples disclosed therein. On the contrary, this application can be extended to all other methods and applications with the same functions.

Claims

1. A desmearing process for a printed circuit board, characterized in that: The main steps are as follows: S1. Place the printed circuit board in the bulking working solution, immerse it for 5-10 minutes, take it out, drain it, and wash it with water; S2, placing the printed circuit board after the swelling treatment in the degumming working solution, immersing for 10-20 minutes, taking it out to drain, and washing with water; S3, placing the printed circuit board after the degumming treatment in the pre-neutralization working solution, immersing for 1-5 minutes, taking it out to drain, and washing with water; S4, placing the pre-neutralized printed circuit board in the neutralization working solution, immersing for 5-10 minutes, taking it out to drain, wash with water, and dry it to complete the desmearing process; The temperature of the bulking working liquid is 50-70° C. The bulking working liquid is mainly made of the following raw materials in percentage by weight: 10-20% of bulking agent and the balance of water; The leavening agent is mainly prepared from the following raw materials in parts by weight: 60-80 parts of dipropylene glycol dimethyl ether, 20-40 parts of fluorocarbon-modified p-aminoanisole, and 3-6 parts of sodium didecyl sulfosuccinate; the fluorocarbon-modified p-aminoanisole is obtained by treating p-aminoanisole with 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propionyl fluoride.

2. The process for removing smear from a printed circuit board according to claim 1, characterized in that: The fluorocarbon-modified p-aminoanisole is prepared by the following method: Under the protection of inert gas, chloroform and isopropanol are mixed, p-aminoanisole is added and mixed, triethylamine is added and mixed, the temperature is lowered to 0-5°C, 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propionyl fluoride is added dropwise, and the addition time of 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propionyl fluoride is 20-40min. After the addition is completed, the temperature is raised to room temperature, stirred for 4-6h, water is added, stirred for 30-50min, and distilled under reduced pressure to obtain fluorocarbon-modified p-aminoaniline.

3. The desmearing process for a printed circuit board according to claim 2, characterized in that: The weight ratio of p-aminoanisole, 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propionyl fluoride, triethylamine, water, chloroform and isopropanol is (40-60):(55-80):(5-15):(5-15):(70-130):(70-130).

4. The desmearing process for a printed circuit board according to claim 1, characterized in that: The temperature of the degumming working solution is 60-80° C., and the degumming working solution is mainly made of the following raw materials in parts by weight: 1000 parts of water, 20-50 parts of sodium hydroxide, and 50-80 parts of potassium permanganate.

5. The desmearing process for a printed circuit board according to claim 1, characterized in that: The pre-neutralization working solution is mainly made of the following raw materials in percentage by weight: 1-5% sulfuric acid, 3-8% neutralization liquid, and the balance is water.

6. The process for removing smear from a printed circuit board according to claim 5, characterized in that: The temperature of the neutralization working solution is 30-60° C. The neutralization working solution is mainly made of the following raw materials in weight percentage: 3-10% sulfuric acid, 10-20% neutralization liquid, and the balance is water.

7. The process for removing smear from a printed circuit board according to claim 6, characterized in that: The neutralization liquid is mainly made of the following raw materials in parts by weight: 20-30% hydrogen peroxide, 0.1-0.5% corrosion inhibitor, 0.1-0.5% chelating agent, 0.1-0.3% surfactant, and the balance is water.

8. The process for removing smear from a printed circuit board according to claim 7, characterized in that: The corrosion inhibitor is one or more of imidazole, 2-phenylimidazole, N-methylimidazole, and 2-p-chlorobenzylpyridylmethylbenzotriazole.

9. The process for removing smear from a printed circuit board according to claim 7, characterized in that: The chelating agent is one or more of aminotri(methylene)phosphonic acid, ethylenediaminetetra(methylene)phosphonic acid, sodium ethylenediaminetetra(methylene)phosphonate, sodium ethylenediaminetetraacetate, and sodium diethylenetriaminepentaacetate.

10. The process for removing smear from a printed circuit board according to claim 7, characterized in that: The surfactant is one or more of surfactant AEO3, surfactant AEO5, surfactant APG0810, surfactant APG1214, and surfactant LD500.

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