Integrated decontamination type cleaning agent for circuit board and preparation method of integrated decontamination type cleaning agent

Abstract

The invention relates to the technical field of cleaning agents, discloses an integrated decontamination type cleaning agent for a circuit board and a preparation method of the integrated decontamination type cleaning agent, and aims to solve the problems that an existing cleaning agent cannot synchronously remove three kinds of pollutants including soldering flux resin residues, micron-sized solder paste particles and fingerprint grease / process oil stains after circuit board welding, and the cleaning agent cannot be used for cleaning the circuit board. And the technical problems of contradictory component adaptation, poor environmental protection property and insufficient base material protectiveness exist. The polar permeation solvent system, the composite surfactant, the functional auxiliary agent and the deionized water are used for constructing the cleaning agent, the solvent penetrates through a resin cross-linked structure, the surfactant synchronously emulsifies grease and dispersed particles, the auxiliary agent optimizes oxide layer stripping and base material protection, the synergistic effect of all the components is achieved, staged cleaning is not needed, and the cleaning effect is good. The cleaning agent can synchronously and efficiently remove three types of pollutants, has the environmental protection property of low VOC content and no harmful component, does not corrode a circuit board base material, is suitable for various cleaning processes, and is high in practicability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cleaning agents, in particular to an integrated stain-removing cleaning agent for circuit boards and a preparation method thereof. BACKGROUND

[0002] With the development of circuit boards towards high integration and miniaturization, the influence of post-soldering residual contaminants on their performance is increasingly significant. Three types of contaminants, namely, flux resin residues, micron-sized solder paste particles, and fingerprint grease / process oil stains, coexist after post-soldering of circuit boards. If not removed, they can cause problems such as reduced insulation, corrosion of solder joints, poor contact, and even shorten the service life of equipment or cause it to fail. Efficient cleaning is a key process to ensure the performance of electronic equipment. Current cleaning agents have types such as solvent-based and water-based, but they have problems such as poor environmental friendliness, low cleaning efficiency for stubborn stains, complex process, and insufficient substrate adaptability. Therefore, how to improve the integrated stain-removing capability while ensuring environmental safety, simplify the process, and protect the substrate is a problem that needs to be solved in this field.

[0003] In the technical research and development of circuit board cleaning agents, existing technologies have proposed various optimization schemes to adapt to different application requirements. The water-based cleaning agent and its preparation method and application with publication number CN114214130A form a halogen-free, phosphorus-free, and nitrogen-free water-based system by compounding non-ionic surfactants, anionic surfactants, organic solvents, and phosphorus and nitrogen-free synergists and stabilizers, achieving effective removal of post-soldering solder paste residues on circuit boards. The cleaning agent for printed circuit boards and its preparation method with publication number CN118909702A introduces modified carbon nanotubes and N-methyl pyrrolidone into the cleaning agent, utilizing the antistatic and anticorrosion effects of modified carbon nanotubes and the film-forming supplementing effect of N-methyl pyrrolidone to ensure the cleaning ability of oil stains and residues while reducing the corrosion risk of circuit board lines and metal components, improving the long-term stability of the cleaned circuit board.

[0004] However, most existing cleaning agents are designed for only a single contaminant and cannot simultaneously process the three types of coexisting contaminants, requiring the replacement of cleaning agents in stages, which increases the complexity of the process and easily causes secondary pollution due to the residue of cleaning agents. A few cleaning agents that attempt to stack multiple components have the risk of component compatibility conflicts. For example, a high proportion of organic solvents can dissolve resin residues, but will destroy the emulsion system of surfactants, causing solder paste particles to be unable to disperse and re-deposit. A high concentration of anionic surfactants can emulsify grease, but will form an adsorption film on the surface of resin residues, hindering the penetration of solvents, ultimately resulting in the inability to completely remove the three types of contaminants, making it difficult for existing technologies to simultaneously and efficiently remove the three types of specific contaminants in a single cleaning agent system. SUMMARY

[0005] The technical problem solved by the present application is to overcome the defects of the prior art, and for this purpose, an integrated decontamination type cleaning agent for circuit boards and a preparation method thereof are provided.

[0006] To achieve the above object, the present application adopts the following technical scheme: An integrated decontamination type cleaning agent for circuit boards, comprising the following raw materials by mass ratio: 6%-12% polar penetrating solvent system, 4%-7% composite surfactant, 1.5%-3.1% functional additive, and the balance is deionized water; the polar penetrating solvent system is compounded by polypropylene glycol alkyl ether and N-alkyl pyrrolidone at a mass ratio of 2:1, which is used to penetrate the cross-linked structure of the flux resin residue and dissociate the hydrogen bond between the residue and the substrate; the composite surfactant is compounded by isooctanol polyoxyethylene ether and sodium lauroyl amphoteric acid at a mass ratio of 3:2, which is used to simultaneously emulsify fingerprint oil / grease and process oil stains and form a charge barrier on the micron-level tin paste particles.

[0007] Preferably, the functional additive includes the following components by mass percentage: 0.8%-1.5% oxidation layer stripping agent, 0.5%-1.2% salt-solubilizing aid, and 0.2%-0.4% substrate corrosion inhibitor.

[0008] Preferably, the oxidation layer stripping agent is sodium gluconate, the salt-solubilizing aid is potassium citrate, and the substrate corrosion inhibitor is a compounded product of benzotriazole and methyl benzotriazole at a mass ratio of 1:1.

[0009] Preferably, the mass percentage of the polar penetrating solvent system is 8%-12% in conventional circuit board cleaning, which is suitable for FR-4 substrates and high-integration BGA / QFP circuit boards; in flexible PI substrate circuit board cleaning, the mass percentage of the polar penetrating solvent system is adjusted to 6% to reduce the stimulation of the solvent to the flexible PI substrate.

[0010] Preferably, the resistivity of the deionized water is >18 MΩ·cm.

[0011] A preparation method of an integrated decontamination type cleaning agent for circuit boards, comprising the following preparation steps: first, add each component of the polar penetrating solvent system into a reaction kettle and stir to form a uniform mother liquor, then add the composite surfactant and stir until the system is transparent, then add the functional additive and stir until it is completely dissolved, then add the balance of deionized water to dilute and adjust the pH of the system to 7.2-8.0, and finally filter out impurities and stand for aging to obtain the integrated decontamination type cleaning agent for circuit boards.

[0012] Preferably, the temperature is controlled at 20-30°C throughout the preparation process.

[0013] Preferably, the standing aging time is 12-16 h.

[0014] Preferably, the stirring rate is controlled at 350-450 r / min.

[0015] Preferably, in the addition of the functional auxiliary agent, the oxidized layer stripping agent, the salt-dissolving auxiliary agent and the substrate corrosion inhibitor are sequentially added.

[0016] Technical effects and advantages of the present application:

[0017] In the present application, by compounding polypropylene glycol methyl ether and N-ethyl pyrrolidone to form a polar penetrating solvent system, low molecular polypropylene glycol methyl ether can penetrate the crosslinked gap of the flux resin, N-ethyl pyrrolidone can dissociate the hydrogen bond between the resin and the substrate, and the compounding surfactant composed of isooctanol polyoxyethylene ether and sodium lauroamphoacetate can not only emulsify oil and fat, but also form a charge barrier on the surface of the solder paste particles to prevent agglomeration. In addition, sodium gluconate, potassium citrate and BTA-MBT compounding corrosion inhibitor are used to realize the synchronous and efficient removal of three types of pollutants, avoid substrate corrosion, simplify the cleaning process, and reduce the risk of secondary pollution without the need for staged replacement of cleaning agents. BRIEF DESCRIPTION OF DRAWINGS

[0018] The disclosure of the present application will be described with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present application. In the drawings, the same reference numerals are used to refer to the same parts:

[0019] Figure 1 Preparation flow chart of the cleaning agent of the present application;

[0020] Figure 2 Test result chart of different polar penetrating solvent systems of the present application;

[0021] Figure 3 Test result chart of different compounding surfactant systems of the present application;

[0022] Figure 4 Test result chart of different preparation temperatures of the present application;

[0023] Figure 5 Test result chart of different standing aging times of the present application. DETAILED DESCRIPTION

[0024] It is easy to understand that, according to the technical solution of the present application, those skilled in the art can propose a plurality of structures and implementation modes which can be replaced with each other without changing the essential spirit of the present application. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present application, and should not be regarded as the whole or as a limitation or restriction on the technical solution of the present application.

[0025] Three types of core contaminants of the circuit board after welding to be cleaned, the formation process is essentially a comprehensive result of molecular level chemical reaction, physical phase change and interface interaction of materials;

[0026] Formation of flux resin residue: under reflow soldering 220-260℃, the carboxyl group of rosin-based resin reacts with metal oxide layer (CuO, SnO) to form metal rosin salt, and the rosin molecules are cross-linked and polymerized through the hydroxyl group to form a cross-linked resin with a molecular weight increased by 3-5 times and a glass transition temperature of 60-100℃; the metal carboxylate generated by the reaction of high-boiling solvents (such as diethylene glycol butyl ether) and activators in the flux is wrapped in the cross-linked structure, and after cooling to room temperature, the cross-linked resin is solidified into a glass state, and the polar groups form hydrogen bonds with the hydroxyl groups of FR-4 substrate, forming a cross-linked resin and metal salt complex form of stubborn residue;

[0027] Formation of micron-sized solder paste particles: 85%-90% of the solder powder in the solder paste will form an oxide layer of 2-5nm if exposed to air for 2-3h, hindering the melting residue, and the flux solvent will volatilize at a rate of 5-15mg / min・cm 2 , and the airflow will impact the molten solder to form 10-30μm droplets, which will solidify into particles after cooling at a rate of 10-30℃ / s; when the nickel plating layer of the pad is less than 5μm, the alloy layer has insufficient bonding force and will fall off under external force to form particles;

[0028] Formation of fingerprint grease / oil stains: the triacylglycerol-containing fingerprint sebum is transferred under a pressure of 50-100kPa, and the free fatty acid carboxyl group forms a van der Waals force of 2-5kJ / mol with the polar groups of the resin, producing an oil film of 0.1-1μm; in the process, the C8-C12 fragments of the release agent polysiloxane, the lubricating oil, and the rust inhibitor petroleum sulfonate will all form oil stains, and some will penetrate the pores of the resin to form a composite structure.

[0029] Based on the above-mentioned three types of coexisting contaminants, to solve the problem that the cleaning agent in the prior art cannot simultaneously and efficiently remove the three types of contaminants, the present application provides an integrated decontamination type cleaning agent for circuit boards, which specifically consists of the following raw materials in terms of mass percentage:

[0030] 8%-12% of a polar penetrating solvent system, which is compounded by polypropylene glycol methyl ether and N-ethyl pyrrolidone (NEP) at a mass ratio of 2:1, wherein the molecular weight of the polypropylene glycol methyl ether is 200-400, and the purity is ≥99.0%, and the purity of the N-ethyl pyrrolidone (NEP) is ≥99.5%;

[0031] 4%-7% of a complex surfactant, the complex surfactant being compounded by isooctanol polyoxyethylene ether (E-1310) and sodium lauroamphoacetate (LAD-30) at a mass ratio of 3:2, wherein the isooctanol polyoxyethylene ether (E-1310) has an HLB value of 10-12 and a purity of ≥98.0%, and the sodium lauroamphoacetate (LAD-30) has an active content of ≥30%;

[0032] 1.5%-3.1% of a functional aid, the functional aid including an oxide layer stripping agent, a salt-solubilizing aid, and a substrate corrosion inhibitor, wherein the oxide layer stripping agent is sodium gluconate with a mass percentage of 0.8%-1.5% and a purity of ≥98.5%, the salt-solubilizing aid is potassium citrate with a mass percentage of 0.5%-1.2% and a purity of ≥99.0%, and the substrate corrosion inhibitor is a compound of benzotriazole (BTA) and methylbenzotriazole (MBT) at a compound ratio of 1:1, with a total mass percentage of 0.2%-0.4% and a purity of ≥99.0%;

[0033] The rest is deionized water, and the deionized water has a resistivity of >18MΩ·cm to avoid the introduction of impurity ions affecting the insulation performance of the circuit board;

[0034] Embodiment 1

[0035] The embodiment provides a preparation method of an integrated decontamination type cleaning agent for a circuit board, and specifically includes the following steps:

[0036] S1: solvent system premixing;

[0037] 5.3% of polypropylene glycol methyl ether and 2.7% of N-ethyl pyrrolidone (NEP) are taken and added into a stainless steel reaction kettle with temperature control and stirring functions;

[0038] The stirring device of the reaction kettle is started, the stirring speed is set to 350r / min, the temperature in the reaction kettle is controlled to be stable at 25℃, and the stirring is continued for 12min, until a transparent and uniform polar penetrating solvent mother liquor is formed, so as to ensure that the molecules of the two solvents are fully mixed, and the problem of local concentration unevenness in subsequent compounding with surfactants is avoided;

[0039] S2: surfactant dissolution;

[0040] The temperature in the reaction kettle is maintained at 25℃ and the stirring speed is maintained at 350r / min, 2.4% of isooctanol polyoxyethylene ether (E-1310) and 1.6% of sodium lauroamphoacetate (LAD-30) are added into the polar penetrating solvent mother liquor in three batches, and each batch is added with an interval of 5min;

[0041] After each batch of material is added, continue stirring until the material is initially dispersed. After all three batches of material are added, continue stirring for 18 minutes until the system is completely transparent and there are no visible layers or suspended particles, thus obtaining a uniform surfactant and solvent mixture system. This prevents surfactants from agglomerating and forming micelles, ensuring the normal functioning of their subsequent emulsification and dispersion.

[0042] S3: Functional additives added;

[0043] Add sodium gluconate (1.1% by mass), potassium citrate (0.8% by mass), and benzotriazole-methylbenzotriazole compound corrosion inhibitor (0.3% by mass) to the above mixture in sequence.

[0044] After each functional additive is added, maintain the stirring speed at 350 r / min and the temperature at 25℃, and continue stirring for 9 min to ensure that each additive is completely dissolved and uniformly dispersed in the system.

[0045] Among them, benzotriazole and methylbenzotriazole need to be mixed evenly before being added to avoid excessive local concentration of corrosion inhibitor, which may cause adverse reactions with sodium gluconate and affect the corrosion inhibition effect;

[0046] S4: Aqueous phase dilution and pH adjustment;

[0047] Maintain the temperature inside the reactor at 25°C and the stirring speed at 350 r / min. Slowly add 85.4% deionized water to the system at a rate of 4 L / min. Observe the system status in real time during the water addition process to avoid generating a large number of bubbles due to excessive water addition.

[0048] After all the deionized water has been added, increase the stirring speed to 400 r / min and continue stirring for 22 min to ensure that the system is fully diluted and homogeneous.

[0049] The pH value of the system was detected using a precision pH meter with an accuracy of ±0.01. If the pH value deviated from the target range of 7.2-8.0, it was finely adjusted using a 0.1 mol / L citric acid solution or a 0.1 mol / L sodium hydroxide solution. In this embodiment, the initial pH value of the system was 7.3, which did not require additional adjustment, in order to ensure the activity of the corrosion inhibitor and avoid corrosion of the circuit board substrate.

[0050] S5: Filtration and aging;

[0051] The prepared system was filtered through a polytetrafluoroethylene microporous membrane with a pore size of 0.22 μm and the filtration pressure was controlled at 0.2 MPa to remove any small impurity particles that may be present in the system and to prevent scratches on the circuit board surface during subsequent cleaning.

[0052] After filtration, the cleaning agent is transferred to a clean polyethylene storage tank and allowed to stand and age at 25°C for 14 hours to allow the components in the system to fully complex and improve the storage stability of the cleaning agent. After aging, the viscosity of the system was measured by an NDJ-5S viscometer to be 7.5 mPa·s, which meets the process requirements, thus completing the preparation of the integrated cleaning agent for circuit boards.

[0053] Example 2

[0054] This embodiment provides a method for preparing an integrated cleaning agent for circuit boards, addressing the need to remove flux resin residues from the shaded areas of components on highly integrated BGA / QFP circuit boards. Compared with Embodiment 1, the specific differences are as follows:

[0055] The total proportion of the polar penetrating solvent system was increased from 8% in Example 1 to 10.5%, of which the mass proportion of polypropylene glycol methyl ether was 7.0% and the mass proportion of N-ethylpyrrolidone (NEP) was 3.5%, and the mass ratio of the two was still maintained at 2:1 to ensure the synergistic penetration effect between solvent molecules;

[0056] Since the total proportion of the polar penetrating solvent system is increased in this embodiment compared with Example 1, in order to ensure that polypropylene glycol methyl ether and N-ethylpyrrolidone (NEP) are fully and uniformly mixed and to avoid local uneven concentration affecting the subsequent compounding effect with surfactant, the stirring time of this step is extended from 12 min in Example 1 to 15 min.

[0057] Everything else is exactly the same as in Example 1.

[0058] Example 3

[0059] This embodiment provides a method for preparing an integrated detergency cleaning agent for circuit boards. To adapt to the sensitivity of low-temperature sensitive circuit boards to organic solvents and to prevent the substrate from swelling, discoloration, or cracking, the mass ratio of the polar penetrating solvent system is adjusted. Compared with Embodiment 1, the specific differences are as follows:

[0060] The total proportion of the polar penetrating solvent system was reduced from 8% in Example 1 to 6%, of which the mass proportion of polypropylene glycol methyl ether was 4.0% and the mass proportion of N-ethylpyrrolidone (NEP) was 2.0%, and the mass ratio of the two was still maintained at 2:1 to ensure the basic resin penetration and hydrogen bond dissociation capabilities.

[0061] It should be noted that this ratio is a special adaptation for sensitive substrates such as flexible PI and is not applicable to conventional circuit board cleaning. In conventional scenarios, the 8%-12% polar penetrating solvent ratio range specified by the technical solution of this invention should still be followed.

[0062] Because flexible PI substrates have higher requirements for the stability of the cleaning agent system, the presence of bubbles can easily lead to uneven local solvent concentration during the cleaning process, increasing the risk of substrate irritation. Therefore, the addition rate of deionized water was reduced from 4L / min in Example 1 to 3L / min.

[0063] Everything else remains the same as in Example 1;

[0064] Comparative Example 1

[0065] Add 87.5% by mass of deionized water to a stainless steel reactor, control the temperature inside the reactor to 25℃, turn on the stirring device, and set the stirring speed to 300 r / min;

[0066] While stirring, 3% by mass of fatty alcohol polyoxyethylene ether (AEO-9) and 2% by mass of sodium dodecylbenzene sulfonate (LAS) were added to the reactor in sequence. After each surfactant was added, the mixture was stirred for 5 minutes until the surfactant was completely dissolved to form an aqueous surfactant solution.

[0067] Add 6% by mass of ethylene glycol butyl ether, 1% by mass of aminotrimethylenephosphonic acid (ATMP), and 0.5% by mass of sodium gluconate to the above aqueous solution, and continue stirring for 20 minutes until the system is homogeneous and transparent.

[0068] The pH of the system was adjusted to 7.1 using a 0.1 mol / L sodium hydroxide solution, eliminating the need for an aging process and directly yielding the cleaning agent for comparison.

[0069] Comparative Example 2

[0070] Add 5.3% by mass of polypropylene glycol methyl ether to a 100L stainless steel reactor, turn on the stirring device, set the stirring speed to 350r / min and the temperature to 25℃, and stir for 12min to form a single solvent system.

[0071] Maintaining the reactor temperature at 25℃ and the stirring speed at 350r / min, add 2.4% by mass of isooctanol polyoxyethylene ether (E-1310) and 1.6% by mass of sodium lauroyl amphotericate (LAD-30) to the single solvent system in three batches, with a 5min interval between each batch. After each batch is added, continue stirring for 18min until the system is homogeneous and transparent.

[0072] Add sodium gluconate (1.1% by mass), potassium citrate (0.8% by mass), and BTA-MBT compound corrosion inhibitor (0.3% by mass) in sequence. Stir for 9 minutes after each addition until the additive is completely dissolved.

[0073] Add 88.5% deionized water at a rate of 4 L / min, stir for 22 min, filter through a 0.22 μm microporous membrane, and let stand at 25 °C for 14 h to obtain the control cleaning agent.

[0074] Comparative Example 3

[0075] Add 5.3% by mass of polypropylene glycol methyl ether and 2.7% by mass of N-ethylpyrrolidone (NEP) to a 100L stainless steel reactor, turn on the stirring device, set the stirring speed to 350r / min and the temperature to 25℃, and stir for 12min to form a polar solvent mother liquor.

[0076] Maintaining the reactor temperature at 25℃ and the stirring speed at 350r / min, add 4% by mass of isooctanol polyoxyethylene ether (E-1310) to the polar solvent mother liquor and continue stirring until isooctanol polyoxyethylene ether (E-1310) is completely dissolved.

[0077] Add sodium gluconate (1.1% by mass), potassium citrate (0.8% by mass), and BTA-MBT compound corrosion inhibitor (0.3% by mass) in sequence. Stir for 9 minutes after each addition until the additive is completely dissolved.

[0078] Add 88.5% deionized water at a rate of 4 L / min, stir for 22 min, filter through a 0.22 μm microporous membrane, and let stand at 25 °C for 14 h to obtain the control cleaning agent.

[0079] To verify the performance of the integrated cleaning agent for circuit boards described in this invention in the simultaneous and efficient removal of three types of contaminants, Examples 1-3 and Comparative Examples 1-3 were selected for performance testing.

[0080] In Example 1 and Comparative Examples 1-3, conventional FR-4 substrate circuit boards with dimensions of 50mm × 50mm were used for testing; in Example 2, BGA / QFP circuit boards with BGA solder joint spacing of 0.5mm and FR-4 substrate were used for testing; and in Example 3, flexible PI substrate circuit boards were used for testing.

[0081] The test items include the removal rate of three types of pollutants, copper corrosion rate, aluminum corrosion rate, appearance of FR-4 substrate, swelling rate of PI substrate, VOC content, heavy metal content, and system stability;

[0082] The flux resin residue removal rate and solder paste particle removal rate were tested using a combination of weighing and microscopic counting methods.

[0083] The grease removal rate was calculated using a fluorescent labeling method, and the intensity decay rate was determined.

[0084] The corrosion rates of copper and aluminum were measured in accordance with GB / T 10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test", after immersion at 60℃ for 2 hours.

[0085] The appearance test of FR-4 substrate was conducted according to SJ / T 11639-2016 "Test Methods for Cleaning Agents of Electronic Components". After soaking at 23℃ for 24 hours, visual observation was performed.

[0086] The swelling rate of the PI substrate was determined by weighing; the VOC content was detected by gas chromatography; and the heavy metal content was detected by inductively coupled plasma mass spectrometry (ICP-MS).

[0087] In the system stability test, the system was stored at room temperature for 3 months, and the system was regularly observed for stratification, precipitation, and odor.

[0088] The test results are shown in Table 1.

[0089]

[0090] Table 1

[0091] Comparative Example 1 showed a solder paste particle removal rate of 97.8%, but the removal rates of flux resin residue and grease were significantly lower than those of Example 1. This is because the anionic surfactant in Comparative Example 1 easily forms an adsorption film on the resin surface, and a single organic solvent cannot break the hydrogen bonds between the resin and the substrate, but can only dissolve the surface resin. In contrast, the polar penetrating solvent system in Example 1 can penetrate the resin cross-linking gaps and dissociate hydrogen bonds. Combined with the synergistic emulsification and dispersion of the composite surfactant, the removal rates of all three types of pollutants are ≥98%, which is significantly better than the prior art.

[0092] Comparative Example 2, lacking N-ethylpyrrolidone (NEP), showed that the flux resin residue removal rate decreased to 84.7%, demonstrating that N-ethylpyrrolidone (NEP) is key to dissociating the hydrogen bonds between the resin and the substrate and completely stripping the crosslinked resin.

[0093] Comparative Example 3, lacking sodium lauroamphoacetate (LAD-30), saw a sharp drop in solder paste particle removal rate to 78.2% and a redeposition rate of 21.3%, demonstrating that the amphoteric structure of sodium lauroamphoacetate (LAD-30) can form a charge barrier and prevent particle aggregation.

[0094] By increasing the proportion of polar solvent to 10.5% and extending the solvent premixing time to 15 minutes, the resin residue removal rate in the BGA shadow area reaches 99.0%, which is suitable for cleaning the complex structure of highly integrated circuit boards.

[0095] By reducing the proportion of polar solvents to 6% and slowing down the aqueous phase dilution rate to 3L / min, the swelling rate of the PI substrate was only 0.03%, and the removal rates of all three types of pollutants were ≥97%.

[0096] The copper corrosion rates in Examples 1-3 were 0.0016-0.0018 mm / a and the aluminum corrosion rates were 0.0011-0.0013 mm / a, significantly lower than Comparative Example 1 and roughly the same as Comparative Examples 2-3. This demonstrates that the BTA-MBT composite corrosion inhibitor can form a dense protective film on the metal surface, and combined with a neutral to weakly alkaline pH control of 7.2-8.0, it effectively inhibits corrosion.

[0097] The FR-4 substrates of Examples 1-2 showed no discoloration / swelling, the PI substrate of Example 3 had a swelling rate of 0.03%, while the FR-4 substrate of Comparative Example 1 showed slight discoloration. This demonstrates that the present invention avoids damage to non-metallic substrates through the selection of low-irritant components and pH control.

[0098] Example 4

[0099] This embodiment provides a method for preparing an integrated detergency cleaning agent for circuit boards. Ten polar penetrating solvent systems with different total proportions are set up to verify the influence of the total proportion of polar solvents on the core performance of the cleaning agent and to clarify the feasible scope of the system.

[0100] In this embodiment, only the total mass ratio of the polar permeation solvent system was adjusted, while the mixing ratio of polypropylene glycol methyl ether to N-ethylpyrrolidone (NEP) remained at 2:1; all other aspects were consistent with Example 1, as detailed in Table 2 below. Figure 2 As shown:

[0101]

[0102] Table 2

[0103] When the total proportion of polar solvents increased from 5% to 10%, the flux resin residue removal rate steadily increased from 82.3% to 99.6%. The penetration ability of low molecular weight polypropylene glycol methyl ether increased with the amount used, and it could penetrate the resin cross-linking gaps more fully. The strong polar group (-C=O) of N-ethylpyrrolidone (NEP) can more efficiently dissociate the hydrogen bonds between the resin and the substrate. Under the synergistic effect of the two, the swelling and peeling effect of the resin was significantly improved. When the total proportion of solvents exceeded 10%, the removal rate decreased slightly because the amount of solvent used had met the saturation requirements of the resin's action, and excessive solvent could not further improve the penetration efficiency.

[0104] The VOC content increases linearly with the increase of the total proportion of polar solvents. The VOC contents of Group 2 and Group 9 are 42g / L and 48g / L, respectively, both ≤50g / L, which meets the environmental protection requirements. The VOC content of Group 10 reaches 65g / L, far exceeding the environmental protection limit, proving that the total proportion of polar solvents ≤12% is the key boundary for balancing environmental protection and decontamination efficiency.

[0105] The acceptable range for polar permeation solvent systems is 8%-12%: below 8%, the resin removal rate is less than 98%; above 12%, VOC exceeds the standard; 10% is the optimal ratio, which can achieve the best balance between resin removal rate and VOC, and is suitable for conventional and highly integrated circuit board scenarios.

[0106] Example 5

[0107] This embodiment provides a method for preparing an integrated detergency cleaning agent for circuit boards. Ten composite surfactant systems with different total proportions are set up to verify the influence of the total proportion of composite surfactants on the core performance of the cleaning agent and to clarify the feasible scope of the system.

[0108] In this embodiment, only the total mass ratio of the composite surfactant system was adjusted; the mixing ratio of isooctanol polyoxyethylene ether (E-1310) to sodium lauroyl amphoteric acetate (LAD-30) was always maintained at 3:2; all other aspects were consistent with Example 1, as detailed in Table 3 below. Figure 3 As shown:

[0109]

[0110] Table 3

[0111] When the total surfactant content increased from 2% to 5.5%, the oil removal rate increased from 83.5% to 99.7%. With the increase of dosage, isooctanol polyoxyethylene ether (E-1310) can penetrate the hydrophobic oil film more fully and destroy the adhesion between oil and substrate through emulsification. Sodium lauroamphoacetate (LAD-30) has an amphoteric structure that helps disperse oil molecules. The two work together to improve degreasing efficiency. When the total content exceeds 5.5%, the removal rate decreases slightly because the surfactant molecules have reached the saturation state of oil emulsification. Excess molecules are prone to aggregation, which reduces the efficiency of interfacial interaction.

[0112] The particle redeposition rate showed a significant decreasing trend with the increase of the total surfactant content. The redeposition rates of Group 2 and Group 8 were 1.8% and 1.1%, respectively, both ≤2%. In Group 1, due to insufficient sodium lauroamphoacetate (LAD-30), an effective charge barrier could not be formed, resulting in severe particle agglomeration and redeposition. This proves that a total surfactant content of ≥4% is the key to ensuring particle dispersibility.

[0113] The viscosity of the system increases stepwise with the increase of the total proportion of surfactant. The viscosities of Group 2 and Group 8 are 7.5 mPa·s and 9.9 mPa·s, respectively, both ≤10 mPa·s. Due to the excessive aggregation of surfactant, the viscosities of Group 9 and Group 10 reach 12.3 mPa·s and 15.1 mPa·s, respectively. This not only affects the compatibility of the cleaning process, but also causes slight swelling of the FR-4 substrate. This proves that the total proportion of surfactant ≤7% is the core boundary for balancing viscosity and substrate protection.

[0114] The acceptable range for composite surfactants is 4%-7%: below 4%, the grease emulsification is insufficient and the particle redeposition rate is high; above 7%, the system viscosity exceeds the standard and there is a risk of damage to the substrate; 5.5% is the optimal ratio, which can achieve the best balance between grease removal rate, particle redeposition rate and viscosity, and is suitable for various cleaning processes and circuit board substrates.

[0115] Example 6

[0116] This embodiment provides a method for preparing an integrated detergency cleaning agent for circuit boards. Ten different preparation temperatures are set throughout the process to verify the influence of the temperature throughout the process on the core performance of the cleaning agent and to clarify the feasible scope of the system.

[0117] This embodiment only adjusts the control temperature throughout the preparation process; all other aspects are the same as in Example 1, as detailed in Table 4 below. Figure 4 As shown:

[0118]

[0119] Table 4

[0120] The dissolution time of surfactants decreases significantly with increasing temperature. Higher temperatures accelerate the thermal motion of surfactant molecules, making it easier for them to overcome intermolecular forces in the solvent and disperse and dissolve rapidly in the polar solvent mother liquor. Below 20℃, molecular motion is slow, and the dissolution time far exceeds the 20-minute upper limit. When the temperature is between 20-30℃, the dissolution time stabilizes at 15.5-19.8 minutes, all meeting the technical requirement of ≤20 minutes. Furthermore, the dissolution efficiency is highest at 25℃, reaching an optimal equilibrium.

[0121] The evaporation rate of polypropylene glycol methyl ether (PPGME) showed a linear increasing trend with increasing temperature. The evaporation rates of groups 2 and 8 were 2.3% and 4.5%, respectively, both ≤5%, meeting the requirements for solvent concentration stability. However, for groups 9 and 10, the evaporation rate of molecules increased sharply due to the temperature exceeding the solvent boiling point threshold, reaching 8.3% and 12.5%, respectively. This resulted in the actual concentration of PPGME in the solvent system being lower than the design value, directly affecting the penetration and dissolution effect of subsequent flux resin residues. This demonstrates that a temperature ≤30℃ throughout the process is the critical boundary for ensuring the stability of the solvent system.

[0122] The relationship between temperature and total preparation time: The total preparation time first shortens and then stabilizes as the temperature increases. The total preparation time is shortest at 25℃ because the efficiency of each process, such as surfactant dissolution and additive dispersion, is optimal at this temperature. When the temperature is below 20℃, the dissolution process takes too long, and the total preparation time increases to 3.8h, which seriously affects production efficiency. When the temperature is above 25℃, although the dissolution time does not change much, the risk of solvent evaporation needs to be controlled, and the total preparation time rises slightly to 1.9-2.2h, which is still within a reasonable range.

[0123] The acceptable temperature range for the entire preparation process is 20-30℃: below 20℃, the dissolution efficiency is low and the production cycle is long; above 30℃, the solvent volatilization exceeds the standard and the stability of the components decreases; 25℃ is the optimal temperature, which can simultaneously achieve the best balance between dissolution efficiency, production cycle and solvent volatilization rate, taking into account both process stability and production economy.

[0124] Example 7

[0125] This embodiment provides a method for preparing an integrated cleaning agent for circuit boards. Ten different standing and aging times are set to verify the influence of aging time on the core performance of the cleaning agent and to clarify the feasible range of the process parameters.

[0126] This embodiment only adjusts the settling and aging time of the filtered cleaning agent; all other aspects are the same as in Example 1, as detailed in Table 5 below. Figure 5 As shown:

[0127]

[0128] Table 5

[0129] The complexation rate of the corrosion inhibitor showed a trend of first rapidly increasing and then approaching saturation with the extension of aging time. The complexation reaction between BTA-MBT and trace metal ions in the system requires time. When aging is insufficient, the complexation reaction is incomplete, and the free corrosion inhibitor cannot form a continuous protective film on the substrate surface. The complexation rate reached 95% after aging for 12 hours, which meets the basic protection requirements. The complexation rate reached 98.8% after aging for 14.5 hours, and the reaction was basically saturated. Further extending the aging time only slightly reduced the complexation rate by 0.6%, with no actual performance gain.

[0130] The corrosion rate of copper / aluminum showed a trend of first decreasing significantly and then stabilizing with the extension of aging time. In Group 1, due to insufficient complexation, the copper corrosion rate reached 0.0035 mm / a. In Group 2, the corrosion rate stabilized at 0.0010-0.0019 mm / a, which met the technical requirements. The corrosion rate was the lowest at 14.5 h, which proved that the aging time of 12-16 h is the key range to ensure the protection effect of the substrate. Below 12 h, the protection is insufficient, and above 16 h, there is no additional protection benefit.

[0131] The production cycle increases linearly with the extension of aging time. The production cycles of Group 2 and Group 8 are 16.5h and 20.5h respectively, both ≤30h, which meets the requirements of industrial production efficiency. Groups 9-10 have a production cycle of more than 30h due to excessive aging time, which leads to a decrease in unit time capacity and a significant reduction in economic efficiency. This proves that aging time ≤16h is the core boundary for balancing performance and production efficiency.

[0132] The acceptable range for the settling and aging time is 12-16 hours: less than 12 hours results in insufficient complexation of the corrosion inhibitor and excessive corrosion; more than 16 hours results in redundant production cycle and poor economic efficiency; 14.5 hours is the optimal time, which can simultaneously achieve the best balance between corrosion inhibitor complexation rate, substrate corrosion rate and production cycle, taking into account both performance and industrial feasibility.

[0133] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. An integrated decontamination type cleaning agent for a circuit board, characterized by comprising: a surfactant; a water-soluble organic solvent; and a water-soluble polymer. The raw materials include the following mass ratios: 6%-12% of a polar penetrating solvent system, 4%-7% of a composite surfactant, 1.5%-3.1% of a functional additive, and the balance of deionized water; The polar penetrating solvent system is compounded by polypropylene glycol alkyl ether and N-alkyl pyrrolidone at a mass ratio of 2:1, which is used to penetrate the cross-linked structure of the flux residue and dissociate the hydrogen bond between the residue and the substrate; The composite surfactant is compounded by isooctanol polyoxyethylene ether and sodium lauroyl amphoteric acid at a mass ratio of 3:2, which is used to simultaneously emulsify the fingerprint oil and process oil stains and form a charge barrier on the micron-level tin paste particles.

2. The integrated decontamination-type cleaning agent for a circuit board according to claim 1, characterized by: The functional additive includes the following components at a mass ratio: 0.8%-1.5% of an oxide layer stripping agent, 0.5%-1.2% of a salt-dissolving aid, and 0.2%-0.4% of a substrate corrosion inhibitor.

3. The integrated decontamination-type cleaning agent for a circuit board according to claim 2, characterized by: The oxide layer stripping agent is sodium gluconate, the salt-dissolving aid is potassium citrate, and the substrate corrosion inhibitor is a compound of benzotriazole and methyl benzotriazole at a mass ratio of 1:

1.

4. The integrated decontamination cleaning agent for a circuit board according to claim 1, characterized by: The mass percentage of the polar penetrating solvent system is 8%-12% in conventional circuit board cleaning, which is suitable for FR-4 substrates and high-integration BGA / QFP circuit boards; in flexible PI substrate circuit board cleaning, the mass percentage of the polar penetrating solvent system is adjusted to 6% to reduce the stimulation of the solvent to the flexible PI substrate.

5. The integrated decontamination cleaning agent for a circuit board according to claim 1, characterized by: The deionized water has a resistivity of >18 MΩ·cm.

6. A method for producing an integrated decontamination-type cleaning agent for a circuit board, for producing the integrated decontamination-type cleaning agent for a circuit board according to any one of claims 1 to 5, characterized by, The preparation steps include the following: first, the components of the polar penetrating solvent system are added to a reaction kettle and stirred to form a uniform mother liquor, then the composite surfactant is added and stirred until the system is transparent, then the functional additive is added and stirred until it is completely dissolved, then the balance of deionized water is added for dilution and the pH of the system is adjusted to 7.2-8.0, and finally impurities are removed by filtration and the product is aged, to obtain the integrated decontamination type cleaning agent for circuit boards.

7. The method of producing an integrated decontamination type cleaning agent for a circuit board according to claim 6, characterized by: The temperature is controlled at 20-30°C throughout the preparation process.

8. A method for preparing an integrated detergency cleaning agent for circuit boards according to claim 6, characterized in that: The aging time is 12-16 h.

9. A method for preparing an integrated detergency cleaning agent for circuit boards according to claim 6, characterized in that: The stirring rate is controlled at 350-450 r / min.

10. The method of producing an integrated decontamination type cleaning agent for a circuit board according to claim 6, characterized by: In the addition of the functional additive, the oxide layer stripping agent, the salt-dissolving aid, and the substrate corrosion inhibitor are added sequentially. In the addition of the functional additive, the oxide layer stripping agent, the salt-dissolving aid, and the substrate corrosion inhibitor are added sequentially.

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