Circuit board surface primer removing liquid and use method thereof

Abstract

The invention belongs to the technical field of circuit board surface treatment, and provides a circuit board surface primer removing liquid and a use method thereof. The cleaning liquid comprises the following components: an alkaline buffer system, an organic solvent, sodium hydroxide, a reduction system, a composite surfactant, a metal corrosion inhibitor, a chelating agent, a rheology modifier, a defoaming agent and water. Through the synergistic effect of the alkaline buffer system and the organic solvent, efficient swelling decomposition of the primer layer is achieved, and meanwhile, the infiltration capacity of a circuit board of a complex structure is remarkably improved by means of the directional wetting characteristic of the composite surfactant. The composite compatibility of the metal corrosion inhibitor and the chelating agent effectively blocks the erosion of active components to the metal substrate, and ensures the functional integrity of the circuit board while thoroughly removing the primer.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board surface treatment, and in particular to a circuit board surface primer removal liquid and a use method thereof. Background Art

[0002] During circuit board manufacturing and repair, removing the primer from the surface is a critical process. While primer is typically used to secure electronic components or as a temporary protective layer, it must be completely removed during subsequent processing or rework to prevent residue from affecting soldering quality, signal transmission, or causing short circuits. Traditional primer removal techniques rely on strong acids, bases, or organic solvents, but these methods have significant limitations in practical applications.

[0003] In the prior art, although strong alkaline solutions (such as high-concentration sodium hydroxide) can effectively dissolve part of the primer, their strong corrosiveness can easily damage the metal circuits, pads and microelectronic components on the circuit board, especially the oxidation and etching problems of metals such as copper and aluminum. In addition, although some organic solvents (such as dichloromethane, acetone, etc.) have good solubility for primers, they have problems such as high volatility, high toxicity, and serious environmental pollution, which do not meet the requirements of modern green manufacturing. At the same time, traditional cleaning solutions are often low in efficiency in removing complex primers (such as epoxy resins, polyimides, etc.) due to their single components or lack of synergy, requiring multiple treatments or extended immersion time, which increases production costs and energy consumption.

[0004] In recent years, some improved cleaning fluids have attempted to alleviate metal corrosion problems by adding corrosion inhibitors or surfactants. However, these solutions often suffer from unstable corrosion inhibition due to irrational component ratios, or poor compatibility between surfactants and solvent systems, which in turn affects cleaning efficiency. In addition, existing technologies generally lack the ability to regulate the rheological properties of cleaning fluids, resulting in insufficient permeability and residual control on the surfaces of complex circuit boards, especially in areas such as micropores and slits. Although ultrasonic-assisted cleaning technology has been introduced to improve efficiency, the components of traditional cleaning fluids are unstable under high temperatures or ultrasonic waves, and are prone to decomposition and failure, and may even produce harmful gases.

[0005] Therefore, there is an urgent need to develop an efficient, environmentally friendly primer removal liquid that does not damage the metal parts of the circuit board. It can quickly decompose various types of primers under mild conditions and has good process adaptability and long-term stability to meet the needs of the high-precision electronic manufacturing field. Summary of the Invention

[0006] In view of this, the present invention provides a circuit board surface primer removal liquid and a method for using the same, the purpose of which is to solve technical problems such as poor removal efficiency of existing primer removal liquids.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a circuit board surface primer removal liquid, which comprises the following components by weight percentage:

[0009] Alkaline buffer system 20-35%, organic solvent 15-30%, sodium hydroxide 10-20%, reducing system 1-6%, composite surfactant 3-8%, metal corrosion inhibitor 0.5-3%, chelating agent 0.1-1.5%, rheology regulator 0.05-0.3%, defoaming agent 0.01-0.1%, and the balance is water.

[0010] Furthermore, the alkaline buffer system includes urea and triethanolamine, and the molar ratio of urea to triethanolamine is 1:0.5-1.5.

[0011] Furthermore, the organic solvent includes one or more of propylene glycol n-propyl ether, propylene glycol methyl ether acetate and γ-butyrolactone.

[0012] Furthermore, the reduction system includes hydrazine hydrate, sodium sulfite and a hydroxylamine derivative; the mass ratio of the hydrazine hydrate, sodium sulfite and hydroxylamine derivative is 1:0.8-1.2:0.05-0.15.

[0013] Furthermore, the hydroxylamine derivative includes N,N-diethylhydroxylamine and / or N-isopropylhydroxylamine.

[0014] Furthermore, the composite surfactant includes at least two of OP-10 emulsifier, isomeric alcohol ether surfactant and fluorocarbon surfactant.

[0015] Furthermore, the metal corrosion inhibitor is a complex of benzotriazole and sodium molybdate, wherein the mass ratio of benzotriazole to sodium molybdate is 1:0.3-0.7;

[0016] The chelating agent is a mixture of EDTA tetrasodium salt and sodium citrate, and the mass ratio of EDTA tetrasodium salt to sodium citrate is 1:0.5-2;

[0017] The rheology modifier is a mixture of a hydrophobically modified polyurethane thickener and polyvinyl pyrrolidone, and the mass ratio of the hydrophobically modified polyurethane thickener to polyvinyl pyrrolidone is 1:1-3;

[0018] The defoaming agent is a compound of polydimethylsiloxane and silicon dioxide, and the mass ratio of the polydimethylsiloxane to the silicon dioxide is 1:1-3.

[0019] The present invention provides a method for using the above-mentioned circuit board surface primer removal liquid, comprising the following steps:

[0020] S1. Soak the circuit board in the primer removal solution at 35-45°C for 3-8 minutes.

[0021] S2. Raise the temperature to 50-60°C and use ultrasonic-assisted treatment for 2-7 minutes.

[0022] Furthermore, in step S2, the frequency of the ultrasonic wave is 25-40 kHz, and the power density is 0.3-0.8 W / cm 2 .

[0023] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. The synergistic effect of the alkaline buffer system and organic solvent achieves efficient swelling and decomposition of the primer layer. The directional wetting properties of the composite surfactant significantly enhance penetration into complex circuit boards. The combination of metal corrosion inhibitors and chelating agents effectively blocks the active ingredients from corroding the metal substrate, ensuring the functional integrity of the circuit board while thoroughly removing the primer.

[0025] 2. The unique reduction system design activates the decomposition reaction at room temperature. The thixotropic system formed with the rheology modifier not only avoids excessive emissions of volatile organic compounds but also ensures the viscosity stability of the working fluid during dynamic processes. The synergistic effect of the defoamer further optimizes the fluid state during the treatment process and reduces process defects.

[0026] 3. The composite corrosion inhibition system of benzotriazole and sodium molybdate creates a dual protective layer of physical adsorption and chemical passivation. Combined with the chelating network of tetrasodium EDTA and sodium citrate, it provides comprehensive protection against multiple metal components such as copper and nickel. This system effectively inhibits secondary contamination caused by metal ion redeposition.

[0027] 4. By coupling staged temperature control with the energy of specific frequency ultrasound, the reaction kinetics are significantly enhanced while avoiding thermal damage to the substrate. The rheological combination of hydrophobically modified polyurethane and polyvinyl pyrrolidone ensures that the cleaning solution has both storage stability and shear-thinning properties during application, making it suitable for various process scenarios such as spraying and immersion.

[0028] 5. The optimized nonionic surfactant system improves cleaning efficiency while reducing interfacial tension and reducing the amount of active ingredients used. The precise ratio of hydrazine hydrate and hydroxylamine derivatives significantly reduces system toxicity while maintaining reducing power, meeting the strict chemical management requirements of the modern electronics manufacturing industry. DETAILED DESCRIPTION

[0029] The present invention provides a circuit board surface primer removal liquid, which comprises the following components by weight percentage:

[0030] Alkaline buffer system 20-35%, organic solvent 15-30%, sodium hydroxide 10-20%, reducing system 1-6%, composite surfactant 3-8%, metal corrosion inhibitor 0.5-3%, chelating agent 0.1-1.5%, rheology regulator 0.05-0.3%, defoaming agent 0.01-0.1%, and the balance is water.

[0031] In the present invention, the amount of the alkaline buffer system is preferably 25-30%.

[0032] In the present invention, the amount of the organic solvent is preferably 20-25%.

[0033] In the present invention, the amount of sodium hydroxide used is preferably 12 to 18%, more preferably 14 to 16%.

[0034] In the present invention, the amount of the reducing system is preferably 2-4%, more preferably 3%.

[0035] In the present invention, the usage of the composite surfactant is preferably 4-6%, more preferably 5%.

[0036] In the present invention, the amount of the metal corrosion inhibitor is preferably 1-2%.

[0037] In the present invention, the amount of the chelating agent is preferably 0.5-1%.

[0038] In the present invention, the amount of the rheology modifier is preferably 0.1 to 0.2%.

[0039] In the present invention, the usage of the defoaming agent is preferably 0.02 to 0.08%, more preferably 0.04 to 0.06%.

[0040] In the present invention, the alkaline buffer system comprises urea and triethanolamine, and the molar ratio of urea to triethanolamine is 1:0.5-1.5, preferably 1:1.

[0041] In the present invention, the organic solvent includes one or more of propylene glycol n-propyl ether, propylene glycol methyl ether acetate and γ-butyrolactone.

[0042] In the present invention, the reduction system comprises hydrazine hydrate, sodium sulfite and a hydroxylamine derivative; the mass ratio of hydrazine hydrate, sodium sulfite and hydroxylamine derivative is 1:0.8-1.2:0.05-0.15, preferably 1:1:0.1.

[0043] In the present invention, the hydroxylamine derivatives include N,N-diethylhydroxylamine and / or N-isopropylhydroxylamine.

[0044] In the present invention, the composite surfactant includes at least two of OP-10 emulsifier, isomeric alcohol ether surfactant and fluorocarbon surfactant; the isomeric alcohol ether surfactant is preferably isomeric octanol polyoxyethylene ether and / or isomeric decanol polyoxyethylene ether; the fluorocarbon surfactant is preferably perfluorohexyltrimethylammonium iodide and / or perfluoroalkyldimethylbenzylammonium iodide.

[0045] In the present invention, the metal corrosion inhibitor is a complex of benzotriazole and sodium molybdate, and the mass ratio of benzotriazole to sodium molybdate is 1:0.3 to 0.7, preferably 1:0.5;

[0046] The chelating agent is a mixture of EDTA tetrasodium salt and sodium citrate, and the mass ratio of EDTA tetrasodium salt to sodium citrate is 1:0.5-2, preferably 1:1;

[0047] The rheology modifier is a mixture of a hydrophobically modified polyurethane thickener and polyvinyl pyrrolidone, wherein the mass ratio of the hydrophobically modified polyurethane thickener to polyvinyl pyrrolidone is 1:1 to 3, preferably 1:2;

[0048] The defoaming agent is a compound of polydimethylsiloxane and silicon dioxide, and the mass ratio of the polydimethylsiloxane to silicon dioxide is 1:1 to 3, preferably 1:2.

[0049] The present invention provides a method for using the above-mentioned circuit board surface primer removal liquid, comprising the following steps:

[0050] S1. Soak the circuit board in the primer removal solution at 35-45°C for 3-8 minutes.

[0051] S2. Raise the temperature to 50-60°C and use ultrasonic-assisted treatment for 2-7 minutes.

[0052] In the present invention, in step S2, the frequency of the ultrasonic wave is 25-40 kHz, and the power density is 0.3-0.8 W / cm 2 .

[0053] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0054] Example 1

[0055] Alkaline buffer system (urea: triethanolamine = 1:1 molar ratio) 25%;

[0056] Organic solvent (propylene glycol n-propyl ether) 20%;

[0057] Sodium hydroxide 14%;

[0058] Reduction system (hydrazine hydrate: sodium sulfite: N,N-diethylhydroxylamine = 1:1:0.1) 3%;

[0059] Composite surfactant (OP-10: isomeric octanol polyoxyethylene ether = 1:1) 5%;

[0060] Metal corrosion inhibitor (benzotriazole: sodium molybdate = 1:0.5) 1%;

[0061] Chelating agent (tetrasodium EDTA: sodium citrate = 1:1) 0.5%;

[0062] Rheology modifier (hydrophobically modified polyurethane thickener: polyvinyl pyrrolidone = 1:2) 0.1%;

[0063] Defoaming agent (polydimethylsiloxane:silicon dioxide=1:2) 0.05%;

[0064] The balance is 31.35% deionized water.

[0065] Mix all the components and stir them at a rate of 1000 rpm for 30 minutes at room temperature and pressure to obtain the circuit board surface primer removal liquid.

[0066] Randomly select 5 circuit boards and immerse them in the cleaning solution. First, immerse them at a constant temperature of 40℃ for 5 minutes, then raise the temperature to 55℃ and start 35kHz ultrasonic wave with a power density of 0.5W / cm 2 After removing the circuit board and rinsing it with deionized water, the surface of the circuit board was smooth and there was no trace of primer residue.

[0067] Example 2

[0068] Alkaline buffer system (urea: triethanolamine = 1:1 molar ratio) 30%;

[0069] Organic solvent (propylene glycol methyl ether acetate) 25%;

[0070] Sodium hydroxide 16%;

[0071] Reduction system (hydrazine hydrate: sodium sulfite: N-isopropylhydroxylamine = 1:1:0.1) 3%;

[0072] Composite surfactant (OP-10: perfluorohexyltrimethylammonium iodide = 1:1) 5%;

[0073] Metal corrosion inhibitor (benzotriazole: sodium molybdate = 1:0.5) 2%;

[0074] Chelating agent (tetrasodium EDTA: sodium citrate = 1:1) 1%;

[0075] Rheology modifier (hydrophobically modified polyurethane thickener: polyvinyl pyrrolidone = 1:2) 0.2%;

[0076] Defoaming agent (polydimethylsiloxane:silicon dioxide=1:2) 0.06%;

[0077] The balance is 18.74% deionized water.

[0078] Mix all the components and stir them at a rate of 1000 rpm for 30 minutes at room temperature and pressure to obtain the circuit board surface primer removal liquid.

[0079] Randomly select 5 circuit boards and immerse them in the cleaning solution. First, immerse them at a constant temperature of 45℃ for 3 minutes, then raise the temperature to 60℃ and start 40kHz ultrasonic waves with a power density of 0.8W / cm 2 After removing the circuit board and rinsing it with deionized water, the surface of the circuit board was smooth and there was no trace of primer residue.

[0080] Example 3

[0081] Alkaline buffer system (urea: triethanolamine = 1:0.8 molar ratio) 25%;

[0082] Organic solvent (γ-butyrolactone) 20%;

[0083] Sodium hydroxide 12%;

[0084] Reduction system (hydrazine hydrate: sodium sulfite: N,N-diethylhydroxylamine = 1:0.8:0.05) 2%;

[0085] Composite surfactant (isomeric decyl alcohol polyoxyethylene ether: perfluoroalkyl dimethyl benzyl ammonium iodide = 3:1) 4%;

[0086] Metal corrosion inhibitor (benzotriazole: sodium molybdate = 1:0.3) 1%;

[0087] Chelating agent (tetrasodium EDTA: sodium citrate = 1:0.5) 0.5%;

[0088] Rheology modifier (hydrophobically modified polyurethane thickener: polyvinyl pyrrolidone = 1:1) 0.1%;

[0089] Defoaming agent (polydimethylsiloxane:silicon dioxide=1:1) 0.04%;

[0090] The balance is 36.36% deionized water.

[0091] Mix all the components and stir them at a rate of 1000 rpm for 30 minutes at room temperature and pressure to obtain the circuit board surface primer removal liquid.

[0092] Randomly select 5 circuit boards and immerse them in the cleaning solution. First, immerse them at a constant temperature of 35℃ for 8 minutes, then raise the temperature to 50℃ and start 25kHz ultrasonic wave with a power density of 0.3W / cm2 After removing the circuit board and rinsing it with deionized water, the surface of the circuit board was smooth and there was no residue of primer.

[0093] Example 4

[0094] Alkaline buffer system (urea: triethanolamine = 1:1.2 molar ratio) 28%;

[0095] Organic solvent (propylene glycol n-propyl ether: γ-butyrolactone = 1:1) 22%;

[0096] Sodium hydroxide 15%;

[0097] Reduction system (hydrazine hydrate: sodium sulfite: N-isopropylhydroxylamine = 1:1.2:0.15) 4%;

[0098] Composite surfactant (OP-10: isomeric octanol polyoxyethylene ether: perfluorohexyltrimethylammonium iodide = 2:2:1) 6%;

[0099] Metal corrosion inhibitor (benzotriazole: sodium molybdate = 1:0.7) 1.5%;

[0100] Chelating agent (tetrasodium EDTA: sodium citrate = 1:2) 0.8%;

[0101] Rheology modifier (hydrophobically modified polyurethane thickener: polyvinyl pyrrolidone = 1:3) 0.15%;

[0102] Defoaming agent (polydimethylsiloxane:silicon dioxide=1:3) 0.08%;

[0103] The balance is 26.37% deionized water.

[0104] Mix all the components and stir them at a rate of 1000 rpm for 30 minutes at room temperature and pressure to obtain the circuit board surface primer removal liquid.

[0105] Randomly select 5 circuit boards and immerse them in the cleaning solution. First, immerse them at a constant temperature of 38°C for 6 minutes, then raise the temperature to 58°C and start 30kHz ultrasonic waves with a power density of 0.6W / cm 2 After removing the circuit board and rinsing it with deionized water, the surface of the circuit board was smooth and there was no residue of primer.

[0106] Example 5

[0107] Alkaline buffer system (urea: triethanolamine = 1:1 molar ratio) 27%;

[0108] Organic solvent (propylene glycol methyl ether acetate) 24%;

[0109] Sodium hydroxide 18%;

[0110] Reduction system (hydrazine hydrate: sodium sulfite: N,N-diethylhydroxylamine = 1:1:0.1) 3.5%;

[0111] Composite surfactant (OP-10: perfluoroalkyl dimethyl benzyl ammonium iodide = 4:1) 5.5%;

[0112] Metal corrosion inhibitor (benzotriazole: sodium molybdate = 1:0.5) 1.2%;

[0113] Chelating agent (tetrasodium EDTA: sodium citrate = 1:1) 0.7%;

[0114] Rheology modifier (hydrophobically modified polyurethane thickener: polyvinyl pyrrolidone = 1:2) 0.18%;

[0115] Defoaming agent (polydimethylsiloxane:silicon dioxide=1:2) 0.07%;

[0116] The balance is 18.75% deionized water.

[0117] Mix all the components and stir them at a rate of 1000 rpm for 30 minutes at room temperature and pressure to obtain the circuit board surface primer removal liquid.

[0118] Randomly select 5 circuit boards and immerse them in the cleaning solution. First, immerse them at a constant temperature of 42°C for 4 minutes, then raise the temperature to 56°C and start 38kHz ultrasonic waves with a power density of 0.7W / cm 2 After removing the circuit board and rinsing it with deionized water, the surface of the circuit board was smooth and there was no residue of primer.

[0119] Substrate corrosion test: Five copper foils (35 μm thick) were immersed in the cleaning solutions prepared in Examples 1 to 5 (25°C ± 2°C, 72 h). The corrosion rate was calculated according to V = (m0 - m1) / (S·t), where m0 is the initial mass of the copper foil, m1 is the mass after immersion, S is the area of ​​the copper foil, and t is the immersion time. The corrosion rates of the cleaning solutions prepared in Examples 1 to 5 were all ≤ 0.08 mg / cm 2 Therefore, the cleaning liquid prepared by the present invention can achieve a good cleaning effect, is short in time, is environmentally friendly, safe, can be used repeatedly, and is suitable for industrial batch and large-scale production.

[0120] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A circuit board surface primer removal liquid, characterized in that: The following components are included by weight percentage: Alkaline buffer system 20-35%, organic solvent 15-30%, sodium hydroxide 10-20%, reducing system 1-6%, composite surfactant 3-8%, metal corrosion inhibitor 0.5-3%, chelating agent 0.1-1.5%, rheology regulator 0.05-0.3%, defoaming agent 0.01-0.1%, and the balance is water.

2. The circuit board surface primer removal liquid according to claim 1, characterized in that: The alkaline buffer system comprises urea and triethanolamine, and the molar ratio of the urea to the triethanolamine is 1:0.5-1.

5.

3. The circuit board surface primer removal liquid according to claim 2, characterized in that: The organic solvent includes one or more of propylene glycol n-propyl ether, propylene glycol methyl ether acetate and gamma-butyrolactone.

4. The circuit board surface primer removal liquid according to any one of claims 1 to 3, characterized in that: The reduction system comprises hydrazine hydrate, sodium sulfite and a hydroxylamine derivative; the mass ratio of the hydrazine hydrate, sodium sulfite and hydroxylamine derivative is 1:0.8-1.2:0.05-0.

15.

5. The circuit board surface primer removal liquid according to claim 4, characterized in that: The hydroxylamine derivatives include N,N-diethylhydroxylamine and / or N-isopropylhydroxylamine.

6. The circuit board surface primer removal liquid according to claim 5, characterized in that: The composite surfactant comprises at least two of an OP-10 emulsifier, an isomeric alcohol ether surfactant and a fluorocarbon surfactant.

7. The circuit board surface primer removal liquid according to claim 2, 3 or 6, characterized in that: A complex of the metal corrosion inhibitor benzotriazole and sodium molybdate, wherein the mass ratio of the benzotriazole to sodium molybdate is 1:0.3-0.7; The chelating agent is a mixture of EDTA tetrasodium salt and sodium citrate, and the mass ratio of EDTA tetrasodium salt to sodium citrate is 1:0.5-2; The rheology modifier is a mixture of a hydrophobically modified polyurethane thickener and polyvinyl pyrrolidone, and the mass ratio of the hydrophobically modified polyurethane thickener to polyvinyl pyrrolidone is 1:1-3; The defoaming agent is a compound of polydimethylsiloxane and silicon dioxide, and the mass ratio of the polydimethylsiloxane to the silicon dioxide is 1:1-3.

8. The method for using the circuit board surface primer removal liquid according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Soak the circuit board in the primer removal solution at 35-45°C for 3-8 minutes. S2. Raise the temperature to 50-60°C and use ultrasonic-assisted treatment for 2-7 minutes.

9. The method of use according to claim 8, characterized in that: In step S2, the frequency of the ultrasonic wave is 25-40 kHz, and the power density is 0.3-0.8 W / cm 2 .