Cleaning process of printed circuit board assembly

Abstract

The invention relates to the field of cleaning of printed circuit board assemblies, and particularly discloses a cleaning process of a printed circuit board assembly. A cleaning process of a printed circuit board assembly comprises the following steps that the printed circuit board assembly is sequentially subjected to primary cleaning, secondary cleaning, spraying, primary rinsing, secondary rinsing and drying, and cleaning liquid used in the primary cleaning and the secondary cleaning is composed of a cleaning agent and water according to the weight ratio of (10-15): (85-90). The specific operation of the primary rinsing and the secondary rinsing is as follows: spraying the printed circuit board assembly after the secondary cleaning, performing the primary rinsing on the printed circuit board assembly after the spraying, performing the secondary rinsing on the printed circuit board assembly after the primary rinsing with water, and using the secondary rinsing water for the primary rinsing when the TDS of the secondary rinsing water is greater than or equal to 10. The whole process has both environmental protection benefits and cleaning efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of cleaning of printed circuit board assemblies, and in particular to a cleaning process of printed circuit board assemblies. Background Art

[0002] As a core component of electronic devices, the manufacturing process of printed circuit board assemblies involves a variety of precision assembly technologies, such as surface mount technology and through-hole technology. In order to ensure the reliability and service life of printed circuit board assemblies, it is usually necessary to clean the surface of printed circuit board assemblies to remove contaminants and prepare for the subsequent coating of three-proof materials. This process occupies an important position in the manufacturing of modern electronic products and directly affects the performance and quality of the products.

[0003] At present, the commonly used methods in the cleaning process of printed circuit board assemblies include spray cleaning, ultrasonic cleaning and drying treatment. Spray cleaning mainly uses high-pressure water to rinse the surface of the printed circuit board assembly to remove larger particles of pollutants; ultrasonic cleaning uses the cavitation effect generated by high-frequency vibration to further remove tiny particles or stubborn stains; drying treatment removes residual moisture through heating to ensure that the printed circuit board assembly is dry and clean. In addition, the ratio of the cleaning liquid and the setting of the cleaning parameters also play a key role in the cleaning effect. However, these methods are often implemented independently in practical applications, lacking the optimization design for the recycling of water resources.

[0004] In the prior art, although the above-mentioned cleaning methods can effectively remove pollutants on the surface of printed circuit board assemblies, there is an obvious waste of water resources. In particular, in the multi-step cleaning process, the cleaning water between each process is not effectively recycled, resulting in a large amount of water resources being directly discharged, which not only increases production costs but also does not meet environmental protection requirements. Therefore, how to achieve efficient use of water resources while ensuring the cleaning effect has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides a cleaning process for a printed circuit board assembly.

[0006] A cleaning process for a printed circuit board assembly provided by this application includes the following steps: sequentially subjecting the printed circuit board assembly to primary cleaning, secondary cleaning, spraying, primary rinsing, secondary rinsing, and drying. The cleaning liquid used in the primary cleaning and secondary cleaning is composed of a cleaning agent and water with a weight ratio of (10 - 15):(85 - 90). The specific operations of the primary rinsing and secondary rinsing are as follows: subject the printed circuit board assembly after spraying to primary rinsing under the conditions of an ultrasonic frequency of 35 - 45 Hz and a temperature of 40 - 50 °C for 8 - 12 min. Subject the printed circuit board assembly after primary rinsing to secondary rinsing with water under the conditions of an ultrasonic frequency of 35 - 45 Hz and a temperature of 40 - 50 °C. When the TDS of the secondary rinsing water ≥ 10, it is reused for primary rinsing.

[0007] By adopting the above technical solution, this application sets up primary cleaning and secondary cleaning steps, and uses a cleaning liquid composed of a cleaning agent and water in a specific ratio, which can effectively remove the contaminants on the surface of the printed circuit board assembly. The introduction of the spraying step combined with ultrasonic primary rinsing and secondary rinsing further improves the cleaning effect, and at the same time realizes the recycling of cleaning water. Most importantly, when the TDS value of the secondary rinsing water reaches a certain threshold in this application, it is reused for primary rinsing, ensuring water resource conservation during the cleaning process, and having both environmental benefits and cleaning efficiency.

[0008] Preferably, the specific operation of the spraying is as follows: when the TDS of the primary rinsing water ≥ 50, it is reused for spraying.

[0009] By adopting the above technical solution, this application effectively utilizes the water after primary rinsing for spraying treatment. When the TDS value of the primary rinsing water reaches or exceeds 50, its impurity content has reached a certain level, but it still has a certain cleaning ability and can be used in the spraying step to initially remove the contaminants on the surface of the printed circuit board assembly. This design not only realizes the hierarchical utilization of cleaning water, but also significantly reduces the demand for fresh water sources, thereby greatly improving the environmental performance and economy of the cleaning process.

[0010] Preferably, the cleaning agent includes an anionic surfactant and a non-ionic surfactant with a weight ratio of (1 - 7):(3 - 9).

[0011] By adopting the above technical solution, the cleaning agent is composed of an anionic surfactant and a non-ionic surfactant with a weight ratio of (1 - 7):(3 - 9). This combination can effectively improve the decontamination ability of the cleaning agent, reduce the amount of cleaning agent used at the same time, thereby reducing the cleaning cost and mitigating the impact on the environment.

[0012] Preferably, the cleaning agent includes an anionic surfactant and a non-ionic surfactant with a weight ratio of 2:8.

[0013] By adopting the above technical solution, the present application optimizes the weight ratio of the anionic surfactant and the non-ionic surfactant in the cleaning agent to 2:8, which can effectively improve the cleaning effect. The cleaning agent under this ratio has better decontamination ability, and can achieve good cleaning effect with less dosage, facilitating the subsequent washing process. Combined with the water-saving cleaning process, it further realizes the dual benefits of environmental protection and efficient cleaning.

[0014] Preferably, the anionic surfactant includes sodium dodecylbenzenesulfonate and potassium alcohol ether phosphate with a weight ratio of 2:8.

[0015] By adopting the above technical solution, the anionic surfactant of the present application is composed of sodium dodecylbenzenesulfonate and potassium alcohol ether phosphate according to the weight ratio of 2:8, which can effectively improve the decontamination ability of the cleaning agent, while maintaining good water solubility and environmental protection characteristics. The anionic surfactant under this ratio can significantly reduce the surface tension of the cleaning solution during the cleaning process, enhance the peeling effect on the surface pollutants of the printed circuit board assembly, thereby improving the cleaning efficiency. In addition, this ratio can also reduce the residue of the cleaning agent, facilitating the subsequent rinsing step, further saving water resources and reducing environmental pollution.

[0016] Preferably, the non-ionic surfactant includes polymethyltrisiloxane ethoxylate, fatty alcohol polyoxyethylene ether and nonylphenol polyoxyethylene ether.

[0017] By adopting the above technical solution, the present application utilizes the good hydrophobicity and decontamination ability of polymethyltrisiloxane ethoxylate, while fatty alcohol polyoxyethylene ether and nonylphenol polyoxyethylene ether can further enhance the emulsification and dispersion effects of the cleaning agent on oil-based pollutants. The combination of the three can achieve good cleaning effect under the premise of less dosage, reduce the usage amount of the cleaning agent, and facilitate the subsequent washing. Combined with the water recycling in the cleaning process, it realizes the dual effects of environmental protection benefits and efficient cleaning.

[0018] Preferably, the weight ratio of polymethyltrisiloxane ethoxylate, fatty alcohol polyoxyethylene ether and nonylphenol polyoxyethylene ether is 1:2:2.

[0019] By adopting the above technical solution, the present application uses polymethyltrisiloxane ethoxylate, fatty alcohol polyoxyethylene ether and nonylphenol polyoxyethylene ether in combination according to the weight ratio of 1:2:2, which can enable the three to play a good synergistic effect and effectively improve the cleaning effect of the cleaning agent. The combination of non-ionic surfactants under this ratio can not only effectively remove the pollutants on the surface of the printed circuit board assembly, but also achieve good cleaning performance at a lower dosage, thereby reducing the usage amount of the cleaning agent and the requirements for subsequent rinsing water, and further saving water resources.

[0020] Preferably, the temperature during the first cleaning is 65 - 75°C and the time is 15 min.

[0021] Preferably, the temperature during the second cleaning is 65 - 75°C and the time is 15 min.

[0022] By adopting the above technical solution, both the first cleaning step and the second cleaning step of the present application are carried out at a temperature of 65 - 75°C, which can effectively activate the active ingredients in the cleaning solution, enhance its ability to dissolve and peel off the contaminants on the surface of the printed circuit board assembly. At the same time, the 15 - minute cleaning time ensures the sufficiency of the cleaning process, neither causing incomplete cleaning due to too short time nor resulting in waste of resources due to too long time. The combined use of this temperature and time significantly improves the efficiency of the first cleaning and the second cleaning, laying a good foundation for the subsequent rinsing step, thus overall enhancing the cleaning effect and saving energy.

[0023] Preferably, the temperature during drying is 115 - 135°C.

[0024] By adopting the above technical solution, the present application controls the drying temperature within the range of 115 - 135°C, which can effectively remove the moisture on the surface of the printed circuit board assembly, ensuring the drying effect after cleaning. This temperature range can not only ensure a high drying speed but also avoid thermal damage to electronic components caused by too high temperature, while reducing energy consumption and enhancing the overall efficiency and reliability of the cleaning process.

[0025] In summary, the present application has the following beneficial technical effects: 1. By optimizing the cleaning process, the present application classifies and recycles the water for spraying, the first rinsing, and the second rinsing. When the TDS value of the washed water reaches a certain standard, it is reused for different cleaning steps in sequence, which can save more than 60% of the cleaning water and significantly reduce water resource waste. 2. The present application uses a specific ratio of cleaning agent and water in the first cleaning and the second cleaning. The cleaning agent contains an anionic surfactant and a non - ionic surfactant, which can achieve a high - efficiency decontamination effect with a small dosage and is convenient for thorough removal in the subsequent cleaning steps. 3. The cleaning process of the present application combines ultrasonic cleaning and temperature control to ensure the effective removal of contaminants during the cleaning process. At the same time, through the drying treatment, the surface of the printed circuit board assembly is ensured to be dry and clean. The overall process has both environmental benefits and high - efficiency cleaning performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow schematic diagram of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The present application will be further described in detail below in conjunction with examples and comparative examples.

[0028] Example 1.1 A cleaning process for a printed circuit board assembly, comprising the following steps: S1. Framing: Place the printed circuit board assembly in a full washing frame and wait for cleaning. S2. Primary cleaning: Mix the cleaning agent and water in a weight ratio of 10:90 to obtain a cleaning solution. Then pour the cleaning solution into the cleaning tank, adjust the temperature in the tank to 65 °C, and after the temperature stabilizes, perform primary cleaning on the printed circuit board assembly in the full washing frame for 15 minutes. S3. Secondary cleaning: Mix the cleaning agent and water in a weight ratio of 15:85 to obtain a cleaning solution. Then pour the cleaning solution into the cleaning tank, adjust the temperature in the tank to 75 °C, and after the temperature stabilizes, perform secondary cleaning on the printed circuit board assembly after primary cleaning for 15 minutes. The components of the cleaning agent in steps S2 and S3 are the same, both being sodium dodecylbenzenesulfonate and nonylphenol polyoxyethylene ether with a weight ratio of 1:9. S4. Spraying: Ensure that the water volume in the spraying water tank is sufficient, and then spray the printed circuit board assembly after secondary cleaning. During the spraying process, toss the printed circuit board assembly up and down for cleaning, and spray the cleaning water simultaneously from the front side, rear side, and upper side of the printed circuit board assembly for 30 seconds. S5. Primary rinsing: Ensure that the water volume in the primary rinsing water tank is sufficient, and then perform primary rinsing on the printed circuit board assembly after spraying under the conditions of an ultrasonic frequency of 45 Hz and a temperature of 40 °C for 8 minutes. S6. Secondary rinsing: Ensure that the water volume in the secondary rinsing water tank is sufficient, and then perform secondary rinsing on the printed circuit board assembly after primary rinsing under the conditions of an ultrasonic frequency of 35 Hz and a temperature of 50 °C for 12 minutes. Recycle the secondary rinsing water to the first recovery water tank, and when the TDS of the secondary rinsing water ≥ 10, introduce it into the primary rinsing water tank and reuse it for primary rinsing. S7. Drying: Use an air gun to remove the surface moisture of the printed circuit board assembly after secondary rinsing, and then dry it at a temperature of 135 °C to obtain the cleaned printed circuit board assembly.

[0029] Example 1.2 A cleaning process for a printed circuit board assembly, comprising the following steps: S1. Framing: Place the printed circuit board assembly in a full washing frame and wait for cleaning. S2. Primary cleaning: Mix the cleaning agent and water according to a weight ratio of 15:85 to obtain a cleaning solution. Then pour the cleaning solution into the cleaning tank, adjust the temperature in the tank to 75 °C, and after the temperature stabilizes, perform primary cleaning on the printed circuit board assembly in the cleaning frame for 15 minutes. S3. Secondary cleaning: Mix the cleaning agent and water according to a weight ratio of 10:90 to obtain a cleaning solution. Then pour the cleaning solution into the cleaning tank, adjust the temperature in the tank to 65 °C, and after the temperature stabilizes, perform secondary cleaning on the printed circuit board assembly after primary cleaning for 15 minutes. The components of the cleaning agent in steps S2 and S3 are the same, both being sodium dodecylbenzenesulfonate and nonylphenol polyoxyethylene ether with a weight ratio of 7:3. S4. Spraying: Ensure that the water volume in the spraying water tank is sufficient, and then spray the printed circuit board assembly after secondary cleaning. During the spraying process, toss the printed circuit board assembly up and down for cleaning, and spray the cleaning water simultaneously from the front side, rear side, and upper side of the printed circuit board assembly for 30 seconds. S5. First rinsing: Ensure that the water volume in the first rinsing water tank is sufficient, and then perform first rinsing on the printed circuit board assembly after spraying under the conditions of an ultrasonic frequency of 35 Hz and a temperature of 50 °C for 12 minutes. S6. Second rinsing: Ensure that the water volume in the second rinsing water tank is sufficient, and then perform second rinsing on the printed circuit board assembly after first rinsing under the conditions of an ultrasonic frequency of 45 Hz and a temperature of 40 °C for 8 minutes. Recycle the second rinsing water to the first recovery water tank, and when the TDS of the second rinsing water ≥ 10, introduce it into the first rinsing water tank for reuse in first rinsing. S7. Drying: Use an air gun to remove the surface moisture of the printed circuit board assembly after second rinsing, and then dry it at a temperature of 115 °C to obtain the cleaned printed circuit board assembly.

[0030] Example 2.1 A cleaning process for a printed circuit board assembly, which is different from Example 1.1 in that: in step S5, the first rinsing water is recycled to the second recovery water tank, and when the TDS of the first rinsing water ≥ 40, it is introduced into the spraying water tank for reuse in spraying, and the rest are the same as in Example 1.1.

[0031] Example 2.2 A cleaning process for a printed circuit board assembly, which is different from Example 1.1 in that: in step S5, the first rinsing water is recycled to the second recovery water tank, and when the TDS of the first rinsing water ≥ 50, it is introduced into the spraying water tank for reuse in spraying, and the rest are the same as in Example 1.1.

[0032] Example 3.1 A cleaning process for a printed circuit board assembly, which is different from Example 2.2 in that: the weight ratio of sodium dodecylbenzenesulfonate to nonylphenol polyoxyethylene ether in Steps S2 and S3 is 2:8, and the rest are the same as in Example 2.2.

[0033] Example 3.2 A cleaning process for a printed circuit board assembly, which is different from Example 2.2 in that: the weight ratio of sodium dodecylbenzenesulfonate to nonylphenol polyoxyethylene ether in Steps S2 and S3 is 3:7, and the rest are the same as in Example 2.2.

[0034] Example 3.3 A cleaning process for a printed circuit board assembly, which is different from Example 2.2 in that: the weight ratio of sodium dodecylbenzenesulfonate to nonylphenol polyoxyethylene ether in Steps S2 and S3 is 4:6, and the rest are the same as in Example 2.2.

[0035] Example 3.4 A cleaning process for a printed circuit board assembly, which is different from Example 2.2 in that: the weight ratio of sodium dodecylbenzenesulfonate to nonylphenol polyoxyethylene ether in Steps S2 and S3 is 5:5, and the rest are the same as in Example 2.2.

[0036] Example 3.5 A cleaning process for a printed circuit board assembly, which is different from Example 2.2 in that: the weight ratio of sodium dodecylbenzenesulfonate to nonylphenol polyoxyethylene ether in Steps S2 and S3 is 6:4, and the rest are the same as in Example 2.2.

[0037] Example 4.1 A cleaning process for a printed circuit board assembly, which is different from Example 3.1 in that: the sodium dodecylbenzenesulfonate in Steps S2 and S3 is replaced with a mixture of sodium dodecylbenzenesulfonate and potassium alcohol ether phosphate with a weight ratio of 2:8, and the rest are the same as in Example 3.1.

[0038] Example 4.2 A cleaning process for a printed circuit board assembly, which is different from Example 3.1 in that: the sodium dodecylbenzenesulfonate in Steps S2 and S3 is replaced with a mixture of sodium dodecylbenzenesulfonate and potassium alcohol ether phosphate with a weight ratio of 8:2, and the rest are the same as in Example 3.1.

[0039] Example 4.3 A cleaning process for a printed circuit board assembly, which is different from Example 3.1 in that: the sodium dodecylbenzenesulfonate in Steps S2 and S3 is replaced with potassium alcohol ether phosphate, and the rest are the same as in Example 3.1.

[0040] Example 5.1 A cleaning process for a printed circuit board assembly, which is different from Example 4.1 in that: the nonylphenol polyoxyethylene ether in steps S2 and S3 is replaced with a poly(methyltrisiloxane) ethoxylate, fatty alcohol polyoxyethylene ether, and nonylphenol polyoxyethylene ether in a weight ratio of 1:1:1, and the rest are the same as in Example 4.1.

[0041] Example 5.2 A cleaning process for a printed circuit board assembly, which is different from Example 4.1 in that: the nonylphenol polyoxyethylene ether in steps S2 and S3 is replaced with a poly(methyltrisiloxane) ethoxylate and nonylphenol polyoxyethylene ether in a weight ratio of 1:1, and the rest are the same as in Example 4.1.

[0042] Example 5.3 A cleaning process for a printed circuit board assembly, which is different from Example 4.1 in that: the nonylphenol polyoxyethylene ether in steps S2 and S3 is replaced with a fatty alcohol polyoxyethylene ether and nonylphenol polyoxyethylene ether in a weight ratio of 1:1, and the rest are the same as in Example 4.1.

[0043] Example 5.4 A cleaning process for a printed circuit board assembly, which is different from Example 4.1 in that: the nonylphenol polyoxyethylene ether in steps S2 and S3 is replaced with a poly(methyltrisiloxane) ethoxylate and fatty alcohol polyoxyethylene ether in a weight ratio of 1:1, and the rest are the same as in Example 4.1.

[0044] Example 5.5 A cleaning process for a printed circuit board assembly, which is different from Example 4.1 in that: the nonylphenol polyoxyethylene ether in steps S2 and S3 is replaced with a poly(methyltrisiloxane) ethoxylate, and the rest are the same as in Example 4.1.

[0045] Example 5.6 A cleaning process for a printed circuit board assembly, which is different from Example 4.1 in that: the nonylphenol polyoxyethylene ether in steps S2 and S3 is replaced with a fatty alcohol polyoxyethylene ether, and the rest are the same as in Example 4.1.

[0046] Example 6.1 A cleaning process for a printed circuit board assembly, which is different from Example 5.1 in that: in steps S2 and S3, the weight ratio of poly(methyltrisiloxane) ethoxylate, fatty alcohol polyoxyethylene ether, and nonylphenol polyoxyethylene ether is 1:2:1, and the rest are the same as in Example 5.1.

[0047] Example 6.2 A cleaning process for a printed circuit board assembly, which is different from Example 5.1 in that: in steps S2 and S3, the weight ratio of polymethyltrisiloxane ethoxylate, fatty alcohol polyoxyethylene ether, and nonylphenol polyoxyethylene ether is 2:2:1, and the rest are the same as in Example 5.1.

[0048] Example 6.3 A cleaning process for a printed circuit board assembly, which is different from Example 5.1 in that: in steps S2 and S3, the weight ratio of polymethyltrisiloxane ethoxylate, fatty alcohol polyoxyethylene ether, and nonylphenol polyoxyethylene ether is 1:2:2, and the rest are the same as in Example 5.1.

[0049] Comparative Example 1.1 It is different from Example 1.1 in that: in steps S2 and S3, the cleaning agent and water are mixed evenly according to a weight ratio of 5:95 to obtain a cleaning solution, and the rest are the same as in Example 1.1.

[0050] Comparative Example 1.2 It is different from Example 1.1 in that: in steps S2 and S3, the cleaning agent and water are mixed evenly according to a weight ratio of 20:80 to obtain a cleaning solution, and the rest are the same as in Example 1.1.

[0051] Comparative Example 2 It is different from Example 1.1 in that: in step S6, when the TDS of the secondary rinse water ≥ 8, it is immediately passed into the primary rinse water tank and reused for primary rinsing, and the rest are the same as in Example 1.1.

[0052] Comparative Example 3 It is different from Example 1.1 in that: in step S6, when the TDS of the secondary rinse water ≥ 10, it is passed into the primary spray water tank and reused for spraying, and the rest are the same as in Example 1.1.

[0053] Performance Detection 1. Detection of water resource conservation effect: First, set a blank group for the cleaning process, specifically: clean according to the process of Example 1.1, but do not reuse the secondary rinse water, and measure the water consumption of the cleaning process with a duration of 100 min as the reference value (mL); then measure the water consumption of the cleaning processes of the examples and comparative examples with a duration of 100 min as the experimental value (mL), and obtain the water consumption reduction ratio for each group. The calculation formula is: water consumption reduction ratio % = [(reference value - experimental value) / reference value] × 100%, and record the results in Table 1; 2. Monitoring of cleaning effect: Test according to the standard of IPC-TM-2009. By extracting the residues on the printed circuit board assembly after cleaning and quantifying with ion chromatography, obtain the ion contamination degree (ug / cm 2Eq NaCl) Record the result in Table 1; 3. Detection of cleaning agent residue: The surface insulation resistance of the printed circuit board assemblies after cleaning in the examples and comparative examples was tested according to the standard of IPC-92010 to obtain the surface insulation resistance value, denoted as SIR (Ω), and the result was recorded in Table 1.

[0054] Table 1 Performance detection Data analysis: As can be seen from Table 1, the cleaning processes of Examples 1.1 - 1.2 can reduce the water consumption by 60.5 - 62.2%, and ensure that the ionic contamination of the printed circuit board assemblies after cleaning is maintained at 0.25 - 0.26 ug / cm 2Eq NaCl , keep the SIR at 3.55×10 9 - 3.61×10 9 Ω, proving that the cleaning process of this application ensures water resource conservation during the cleaning process, with both environmental benefits and cleaning efficiency.

[0055] In Examples 2.1 - 2.2, on the basis of Example 1.1, the primary rinse water in step S5 was recycled into the second recovery water tank, and when the TDS of the primary rinse water reached a certain threshold, it was introduced into the spray water tank and reused for spraying. The results showed that the water consumption could be reduced by 66.3 - 69.8% at this time, and there was no significant difference in ionic contamination and SIR compared with Example 1.1, proving that this application effectively utilized the water after primary rinsing for spraying treatment. Although its impurity content had reached a certain level, it still had a certain cleaning ability and could be used in the spraying step to initially remove the pollutants on the surface of the printed circuit board assembly.

[0056] In Examples 3.1 - 6.3, this application continuously adjusted the components of the cleaning agent. While maintaining the water consumption reduction ratio not less than 69.6%, the ionic contamination was reduced to 0.24 ug / cm 2Eq NaCl , and the SIR was increased to 3.77×10 9 Ω, proving that this application composed an anionic surfactant from sodium dodecylbenzenesulfonate and potassium alcohol ether phosphate in a weight ratio of 2:8, composed a non-ionic surfactant from polymethyltrisiloxane ethoxylate, fatty alcohol polyoxyethylene ether, and nonylphenol polyoxyethylene ether in a weight ratio of 1:2:2, and then optimized the weight ratio of the anionic surfactant and non-ionic surfactant in the cleaning agent to 2:8, which could effectively remove the pollutants on the surface of the printed circuit board assembly, and could also achieve good cleaning performance at a lower dosage, thereby reducing the usage amount of the cleaning agent and the requirements for subsequent rinse water, and saving water resources.

[0057] In Comparative Examples 1.1 - 1.2, the present application changed the weight ratio of the cleaning agent to water in Steps S2 and S3. The results showed that in Comparative Example 1.1, not only was the water consumption reduction ratio and ion contamination level severely increased, but also the SIR was not significantly improved. Meanwhile, in Comparative Example 1.2, the SIR decreased significantly and the ion contamination level did not decrease significantly either. This proves that by using a cleaning solution composed of a cleaning agent and water in a specific ratio, the present application can effectively remove contaminants on the surface of printed circuit board assemblies, ensure water resource conservation during the cleaning process, and have both environmental benefits and cleaning efficiency.

[0058] In Comparative Example 2, the present application changed the TDS recovery threshold of the secondary rinse water. The results showed that not only was the SIR not significantly improved, but also the water consumption reduction ratio decreased significantly. This proves that although the impurity content in the secondary rinse water has reached a certain level, it still has a certain cleaning ability and can be used in the primary rinse step to remove contaminants on the surface of printed circuit board assemblies.

[0059] In Comparative Example 3, the present application directly recycled the secondary rinse water to the spraying step for spraying. The results showed that the water consumption reduction ratio did not change significantly, and at the same time, the ion contamination level increased to a certain extent. This proves that the cleaning process of the present application has strict operating specifications, and each step is closely linked. As a whole, it improves the cleaning effect of printed circuit board assemblies and significantly saves water resources.

[0060] The embodiments of this specific implementation manner are all preferred embodiments of the present application, and do not limit the protection scope of the present application accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A cleaning process for a printed circuit board assembly, characterized in that: The method comprises the following steps: subjecting a printed circuit board assembly to a primary cleaning, a secondary cleaning, spraying, a primary rinsing, a secondary rinsing and drying treatments in sequence, wherein the cleaning liquid used in the primary cleaning and the secondary cleaning comprises a cleaning agent and water in a weight ratio of (10-15):(85-90), and the specific operations of the primary rinsing and the secondary rinsing are: subjecting the sprayed printed circuit board assembly to a primary rinsing under the conditions of an ultrasonic frequency of 35-45 Hz and a temperature of 40-50° C. for 8-12 minutes, subjecting the rinsed printed circuit board assembly to a secondary rinsing with water under the conditions of an ultrasonic frequency of 35-45 Hz and a temperature of 40-50° C., and when the TDS of the secondary rinsing water is ≥10, the secondary rinsing water is reused for the primary rinsing.

2. A printed circuit board assembly cleaning process according to claim 1, characterized in that: The specific operation of the spraying is: when the TDS of the rinse water is ≥50, it is reused for spraying.

3. A printed circuit board assembly cleaning process according to claim 1, characterized in that: The cleaning agent comprises an anionic surfactant and a nonionic surfactant in a weight ratio of (1-7):(3-9).

4. A cleaning process for a printed circuit board assembly according to claim 3, characterized in that: The cleaning agent includes an anionic surfactant and a nonionic surfactant in a weight ratio of 2:

8.

5. A cleaning process for a printed circuit board assembly according to claim 3, characterized in that: The anionic surfactant comprises sodium dodecylbenzene sulfonate and potassium alcohol ether phosphate in a weight ratio of 2:

8.

6. A printed circuit board assembly cleaning process according to claim 3, characterized in that: The nonionic surfactant includes polymethyl trisiloxane ethoxylate, fatty alcohol polyoxyethylene ether and nonylphenol polyoxyethylene ether.

7. A printed circuit board assembly cleaning process according to claim 6, characterized in that: The weight ratio of the polymethyl trisiloxane ethoxylate, fatty alcohol polyoxyethylene ether and nonylphenol polyoxyethylene ether is 1:2:

2.

8. A printed circuit board assembly cleaning process according to claim 1, characterized in that: The temperature during the first cleaning is 65-75°C and the time is 15 minutes.

9. A printed circuit board assembly cleaning process according to claim 1, characterized in that: The temperature during the secondary cleaning is 65-75°C and the time is 15 minutes.

10. A printed circuit board assembly cleaning process according to claim 1, characterized in that: The temperature during the drying is 115-135°C.

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