Low-toxicity degradable PCB (Printed Circuit Board) cleaning agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of industrial cleaning, and particularly discloses a low-toxicity degradable PCB (Printed Circuit Board) cleaning agent as well as a preparation method and application thereof. The low-toxicity degradable PCB cleaning agent is characterized by being prepared by mixing the following raw materials in percentage by weight: 50%-90% of D-methyl lactate, 10%-30% of isopropanol, 0-5% of glucoside and 0-5% of benzotriazole. The cleaning agent is reasonable in formula, all the components are synergistic, and the cleaning agent has the characteristics of being high in cleaning efficiency, mild to a base material and environmentally friendly, is free of residues after volatilization, is free of corrosion and damage to metal parts, is suitable for cleaning the surfaces of various materials such as electronic elements and metal workpieces, is especially suitable for precise cleaning of copper-containing metal parts, and has good application prospects. The application prospect is wide.

Description

Technical Field

[0001] This invention relates to the field of industrial cleaning technology, and in particular to a low-toxicity, biodegradable PCB circuit board cleaning agent, its preparation method, and its application. Background Technology

[0002] As the core carrier and connection component of electronic devices, printed circuit boards (PCBs) are susceptible to damage from contaminants such as solder paste residue, flux residue, oil, and dust during manufacturing and rework. These contaminants can severely affect the insulation performance, signal transmission stability, and lifespan of the PCB, and may even lead to short circuits and frequent malfunctions in electronic devices. Therefore, efficient cleaning of PCBs is an indispensable and critical process in the electronics manufacturing industry.

[0003] Currently, PCB cleaning agents widely used in the industry are mainly divided into three categories: traditional organic solvent-based, water-based, and semi-aqueous-based. Traditional organic solvent-based cleaning agents, with chlorofluorocarbons, trichloroethylene, and dichloromethane as main components, offer advantages such as high cleaning efficiency, strong oil solubility, and rapid evaporation; however, these cleaning agents can damage the ozone layer or are highly toxic, resulting in high subsequent environmental treatment costs. Water-based cleaning agents use water as a solvent, combined with surfactants, chelating agents, corrosion inhibitors, and other additives, exhibiting lower toxicity and relatively better environmental friendliness; however, their cleaning effect is easily affected by water quality, cleaning temperature, and cleaning time, and their ability to dissolve stubborn contaminants such as solder paste residue is insufficient. Semi-aqueous-based cleaning agents combine some advantages of organic solvents and water-based cleaning agents, using alcohols, esters, and other organic solvents as main components, combined with a small amount of water and additives, balancing cleaning efficiency with a certain degree of environmental friendliness; however, these cleaning agents have poor biodegradability, and long-term discharge can easily lead to environmental pollution accumulation.

[0004] With the increasing global awareness of environmental protection and the transformation and upgrading of the electronics manufacturing industry, countries around the world have successively introduced stricter environmental regulations and occupational health standards, placing higher demands on the low toxicity, biodegradability, environmental friendliness, and safety of PCB cleaning agents. Existing PCB cleaning agents generally suffer from problems such as difficulty in balancing environmental friendliness and cleaning performance, high toxicity, and poor biodegradability, failing to meet the current environmental requirements and precision cleaning needs of the electronics manufacturing industry. Therefore, developing a low-toxicity, biodegradable, environmentally friendly, and pollution-free PCB cleaning agent with high cleaning efficiency, good compatibility, simple preparation process, and convenient use has become an urgent technical challenge in the electronics manufacturing field. This is of great significance for promoting the green and sustainable development of the electronics manufacturing industry and protecting the occupational health of operators. Summary of the Invention

[0005] This invention provides a low-toxicity, biodegradable PCB circuit board cleaning agent, its preparation method, and its application, aiming to solve the technical problems of existing cleaning agents having insufficient cleaning power, easy corrosion of metal substrates, or poor biodegradability.

[0006] This invention is achieved through the following technical solution: A low-toxicity, biodegradable PCB cleaning agent is made from the following raw materials in the indicated weight ratios: 60%-90% D-methyl lactate, 10%-30% isopropanol, 0-5% glycoside, and 0-5% benzotriazole.

[0007] The cleaning agent of the present invention is composed of D-methyl lactate, isopropanol, glycosides and benzotriazole. D-methyl lactate and isopropanol synergistically enhance the detergency and effectively dissolve oil and organic stains. Glycosides, as surfactants, improve wetting and dispersing effects and are also biodegradable. Benzotriazole plays an excellent role in corrosion inhibition and can protect copper and other metal substrates from corrosion.

[0008] A more preferred technical solution of the present invention is as follows: The preferred weight ratio of each raw material is as follows: D-methyl lactate 75%-85%, isopropanol 12%-20%, glycoside 1%-2%, benzotriazole 1-3%.

[0009] The weight ratio of each raw material is further optimized as follows: 80% D-lactic acid methyl ester, 18% isopropanol, 1% glycoside, and 1% benzotriazole.

[0010] This invention also discloses a method for preparing the above-mentioned low-toxicity biodegradable PCB circuit board cleaning agent, comprising the following steps: (1) Clean and dry the beakers and reagent bottles with isopropanol, and cool them to room temperature before use; (2) Weigh out benzotriazole and put it into a dry beaker. Add isopropanol and turn on magnetic stirring until benzotriazole is completely dissolved. (3) Slowly add glycosides to the solution obtained in step (2) and stir to form a homogeneous mixed phase; (4) Add D-lactic acid methyl ester to the mixed phase and stir until the solution is completely transparent and there is no layering or turbidity. The product is obtained.

[0011] More preferably, in step (1), the drying conditions are drying at 110°C for 1 hour, followed by natural cooling to room temperature for later use.

[0012] More preferably, in step (2), the magnetic stirring conditions are 200 r / min for 1 h.

[0013] In a further preferred embodiment, in step (3), the glycoside is added dropwise at room temperature while magnetic stirring is turned on and the speed is controlled at 300 r / min.

[0014] An application of the low-toxicity biodegradable PCB circuit board cleaning agent as described in any one of claims 1-3 involves immersing the PCB circuit board to be cleaned in the cleaning agent, ultrasonically treating it, observing the cleaning effect, and calculating the residue content.

[0015] More preferably, the ultrasonic treatment conditions are 30-50 kHz for 30 min. The cleaning agent of this invention has a reasonable formula with synergistic effects among its components. It features high cleaning efficiency, gentleness on substrates, and environmental friendliness. Moreover, the cleaning agent leaves no residue after evaporation and does not corrode or damage metal parts. It is suitable for cleaning the surfaces of various materials such as electronic components and metal workpieces, and is especially suitable for precision cleaning of copper-containing metal parts. It has broad application prospects. Attached Figure Description

[0016] The invention will now be further described with reference to the accompanying drawings.

[0017] Figure 1 Photograph of an uncleaned PCB circuit board; Figure 2 This is a photo of the PCB circuit board after cleaning; Figure 3 The image shows a comparison of the infrared spectra of the PCB circuit board before and after cleaning. Figure 4 This is a metallographic microscope image of the PCB circuit board after cleaning. Detailed Implementation

[0018] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0020] The present invention will now be described in detail with reference to the accompanying drawings.

[0021] Example 1: A low-toxicity, biodegradable PCB circuit board cleaning agent and its preparation method In this embodiment, the amounts of each component are as follows: D-methyl lactate 75%, Isopropanol 20%, 2% glycosides Benzotriazole 3%.

[0022] The preparation method of the cleaning agent in this embodiment includes the following steps: Step 1: Clean the beakers and reagent bottles with isopropanol, dry them, and cool them to room temperature before use; Step 2: Weigh 3.0g of benzotriazole into a dry beaker, add 20.0g of isopropanol, and turn on magnetic stirring until the benzotriazole is completely dissolved; Step 3: Slowly add 2.0g of glycoside to the above solution to form a homogeneous mixed phase; Step 4: Add 75g of D-methyl lactate to the above mixture and stir until the solution is completely transparent and there is no layering or turbidity. The cleaning agent product is then obtained. Example

[0023] In this embodiment, the amounts of each component are as follows: D-methyl lactate 80%, Isopropyl alcohol 18%, Glycoside 1.0%, Benzotriazole 1.0%.

[0024] The preparation method of the cleaning agent in this embodiment is the same as that in Example 1. Example

[0025] In this embodiment, the amounts of each component are as follows: D-methyl lactate 85%, Isopropanol 12%, 1.5% glycosides Benzotriazole 1.5%.

[0026] The preparation method of the cleaning agent in this embodiment is the same as that in Example 1.

[0027] Comparative Example 1: The cleaning agent contains D-methyl lactate.

[0028] Comparative Example 2: The cleaning agent consists of D-methyl lactate and isopropanol. The preparation method is as follows: Clean the beaker and reagent bottle with isopropanol, dry them, and cool them to room temperature; measure 73.4 mL of D-methyl lactate into the beaker, then measure 24.2 mL of isopropanol, and stir at room temperature for 10 minutes until a homogeneous solution is formed.

[0029] Comparative Example 3: The cleaning agent consists of D-methyl lactate, isopropanol, and glycosides. The preparation method is as follows: Clean the beaker and reagent bottle with isopropanol, dry them, and cool them to room temperature; measure 24.2 mL of isopropanol into the beaker, then measure 0.55 mL of glycosides and add them dropwise at room temperature while simultaneously turning on a magnetic stirrer at 300 rpm for 10 minutes; finally, measure 73.4 mL of D-methyl lactate and add it to the above solution until a homogeneous solution is formed.

[0030] Comparative Example 4: The cleaning agent consists of D-methyl lactate, isopropanol, glycoside, and benzotriazole. The preparation method is as follows: Clean the beaker and reagent bottle with isopropanol, dry them, and cool to room temperature; measure 24.2 mL of isopropanol into the beaker, weigh 0.4 g of benzotriazole, add it to the above solution, and simultaneously turn on the magnetic stirrer at 300 rpm for 10 min at room temperature; then measure 0.55 mL of glycoside and add it dropwise at room temperature, simultaneously turning on the magnetic stirrer at 300 rpm for 200 min at room temperature; finally, measure 73.4 mL of D-methyl lactate and add it to the above solution until a homogeneous solution is formed.

[0031] Comparative Example 5: Replace D-methyl lactate with other conventional solvents in the art, such as ethanol. In this case, the cleaning agent consists of ethanol, isopropanol, glycoside, and benzotriazole. The preparation method is as follows: Clean the beaker and reagent bottle with isopropanol, dry them, and cool them to room temperature; measure 24.2 mL of isopropanol into the beaker, weigh 0.4 g of benzotriazole, add it to the above solution, and simultaneously turn on the magnetic stirrer, controlling the speed at 300 r / min, and stir at room temperature for 10 min; then measure 0.55 mL of glycoside, add it dropwise at room temperature, and simultaneously turn on the magnetic stirrer, controlling the speed at 300 r / min, and stir at room temperature for 200 min; finally, measure 101.4 mL of D-methyl lactate and add it to the above solution until a homogeneous solution is formed.

[0032] The cleaning agents obtained in Examples 1-3 were used to clean PCB circuit boards. The specific cleaning method was as follows: PCB circuit boards from the same batch to be cleaned were placed in the cleaning agent, ensuring the agent completely submerged the boards, and then ultrasonically treated at 50kHz. The PCB circuit boards in the cleaning agents of Examples 1, 2, and 3 were treated for 20 min, 25 min, and 30 min, respectively. The residue content of the treated PCB circuit boards was then measured. The specific cleaning data are shown in the table below. The cleaning effect of flux is shown in Table 1. Table 1: Statistical Table of Cleaning Effect of Cleaning Agent on Flux

[0033] As shown in Table 1, the cleaning agents in Examples 1-3 were effective in cleaning flux, and no white spots remained on the surface after cleaning.

[0034] Using the same cleaning method, the cleaning effects of the cleaning agents obtained in Comparative Examples 1-5 were tested. The specific cleaning data are shown in the table below:

[0035] The residue rate was determined using a gravimetric method, which involved weighing the sample before and after cleaning and calculating the residue rate of the substance on the sample surface based on the change in mass. The calculation formula is as follows: R = m2 / m1 × 100%, In the formula, R is the residual rate (%), m1 is the mass of the substance adhering to the sample surface before cleaning (g), and m2 is the mass of the residual substance on the sample surface after cleaning (g).

[0036] The comparison between Comparative Examples 1 and 2 shows that isopropanol and D-methyl lactate form a polarity complementary relationship. Isopropanol possesses both polarity and weak lipophilicity, allowing it to dissolve some non-polar / weakly polar components. D-methyl lactate evaporates slowly, while isopropanol evaporates relatively quickly, forming a gradient evaporation with D-methyl lactate, thus avoiding slow drying, watermarks, and residues. The application data from Comparative Example 3 shows that glycosides can reduce the surface tension of the cleaning agent, significantly improving wetting and spreading on the circuit board surface and microstructures. It can also act as a flux to emulsify, disperse, and suspend residues; its good biodegradability facilitates post-processing. The application data from Comparative Examples 4 and 5 show that benzotriazole provides passivation protection for copper circuits, preventing corrosion and oxidation during the cleaning process, with a relatively significant cleaning effect. Furthermore, compared to conventional ethanol in the field, and under the same composition application scenario, the cleaning agent containing D-methyl lactate exhibits superior performance.

[0037] In addition, refer to the instruction manual appendix Figure 1 and Figure 2 It can be seen that before cleaning, a large amount of solder paste adhered to the surface of the PCB circuit board; after cleaning, visual inspection showed that there was no obvious solder paste residue on the surface of the PCB circuit board. Figure 3 The results show that the intensity of the infrared characteristic peaks of the sample decreased significantly after cleaning, indicating that the residues on the sample surface were effectively removed. After fitting and calculating the peak area of ​​the characteristic peaks, it was found that the remaining proportion of residues on the sample surface was only 4%, which further verified the excellent effect of the cleaning method.

[0038] Appendix Figure 4Metallurgical microscope images show the surface microstructure of a circuit board sample after 30 minutes of cleaning. The images clearly show that after the cleaning process, there is no visible residue, corrosion, or abnormal surface roughness. This result directly confirms the effectiveness of the current cleaning process in removing solder paste residue, ensuring the reliability and long-term stability of the circuit board in subsequent use.

[0039] To ensure the reliable environmental friendliness of the mixed cleaning agent composed of D-methyl lactate, isopropanol, glycosides, and benzotriazole, we conducted a systematic component analysis and recovery treatment verification of its residual liquid after use. After treatment with a professional distillation recovery process, the test data showed: The recovery rate of D-methyl lactate and isopropanol exceeds 90%, and the reuse purity reaches over 99%; glycoside surfactants can achieve a biodegradation rate of over 98% in the biochemical treatment unit; and trace amounts of benzotriazole are completely decomposed through the equipped ozone advanced oxidation system.

[0040] The entire treatment process enables the recycling of organic solvents and the targeted removal of hazardous substances, ensuring from the source that the cleaning agent system does not cause observable negative impacts on water bodies, soil, and biological communities in practical applications, which is in line with the closed-loop management concept of green chemistry.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A low-toxicity, biodegradable PCB circuit board cleaning agent, characterized in that, It is made from the following raw materials in the indicated weight ratios: 60%-90% D-lactic acid methyl ester, 10%-30% isopropanol, 0-5% glycoside, and 0-5% benzotriazole.

2. The low-toxicity, biodegradable PCB circuit board cleaning agent as described in claim 1, characterized in that, It is made from the following raw materials in the indicated weight ratios: 75%-85% D-lactic acid ester, 12%-20% isopropanol, 1%-2% glycoside, and 1-3% benzotriazole.

3. The low-toxicity, biodegradable PCB circuit board cleaning agent as described in claim 1 or 2, characterized in that, It is made from the following raw materials in the following weight ratio: 80% D-lactic acid methyl ester, 18% isopropanol, 1% glycoside, and 1% benzotriazole.

4. The preparation method of the low-toxicity biodegradable PCB circuit board cleaning agent according to any one of claims 1-3, characterized in that, The steps include: (1) Cleaning and drying the beaker and reagent bottle with isopropanol, and cooling them to room temperature for later use; (2) Weighing benzotriazole and placing it in the dried beaker, adding isopropanol, and turning on magnetic stirring until the benzotriazole is completely dissolved; (3) Slowly adding glycosides to the solution obtained in step (2) and stirring to form a uniform mixed phase; (4) Adding D-methyl lactate to the mixed phase and stirring until the solution is completely transparent and there is no layering or turbidity, thus obtaining the product.

5. The preparation method according to claim 4, characterized in that: In step (1), the drying conditions are 110°C for 1 hour, followed by natural cooling to room temperature for later use.

6. The preparation method according to claim 4, characterized in that: In step (2), the magnetic stirring conditions are 200 r / min for 1 h.

7. The preparation method according to claim 4, characterized in that: In step (3), the glycosides are added dropwise at room temperature while the magnetic stirrer is turned on and the speed is controlled at 300 r / min.

8. An application of the low-toxicity biodegradable PCB circuit board cleaning agent as described in any one of claims 1-3, wherein the PCB circuit board to be cleaned is placed in the cleaning agent and ultrasonically treated.

9. The application as described in claim 8, characterized in that: The ultrasonic treatment conditions were 30-50 kHz for 30 minutes.

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