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In PCB, solder protection process and precautions are explained in detail.

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The solder-proofing process in PCB (Printed Circuit Board) is an important part in the manufacturing of circuit boards, the purpose of which is to form a protective film on the circuit board to prevent unnecessary areas from being soldered during the soldering process, and also to protect the circuit board from mechanical damage and environmental corrosion. The following is a detailed description of the solder protection process and precautions to be taken:

Soldermask Process

Surface Cleaning: 

Before the anti-soldering process, first ensure that the surface of the circuit board is clean and free of contamination, no residual flux, grease or other impurities, as these residues may affect the adhesion of the anti-soldering layer.


The cleaned circuit board needs to be thoroughly dried to avoid moisture adversely affecting the adhesion of the anti-solder layer.

Soldermask application: Soldermask material is applied to the non-conductive areas of the board. Soldermask can be applied by different methods, such as screen printing, spraying, rolling or brushing.


After application, the film needs to undergo a curing process, usually in a hot air or infrared oven, to harden the film and form a strong protective layer.


After curing, the layer needs to be inspected to ensure that it is uniform, free of defects and that it completely covers the area to be protected.


Any untidy edges of the soldermask or excess material that may have occurred during the application process need to be trimmed to maintain a neat and professional appearance of the board.


Electrical and physical tests are carried out to ensure that the soldermask does not affect the electrical properties of the board and has good resistance to abrasion and corrosion.


Material Selection: 

It is very important to select the right material for the soldermask. Different materials have different physical and chemical properties and should be selected according to the usage environment and performance requirements of the board.

Environmental Control: 

Environmental conditions during the coating and curing process, such as temperature, humidity and dust levels, need to be strictly controlled to prevent quality problems with the soldermask.

Equipment Maintenance: 

Regular maintenance of the coating and curing equipment ensures that it operates accurately and avoids uneven coating or inadequate curing due to equipment problems.

Operational Safety: 

Soldermask materials may contain hazardous chemicals. Operators should wear appropriate personal protective equipment and ensure good ventilation.

Quality Control: 

Establish a strict quality control process and carefully inspect the soldermask on each board to ensure it meets quality standards.

Waste Disposal: 

Waste generated during the soldermask process, such as waste solvents and waste soldermask, should be disposed of in accordance with environmental requirements.


Additional Details

Thickness of The Film: 

Ensure that the thickness of the film is as designed, as too thick a film may make soldering difficult, while too thin a film may not provide adequate protection.


Pre-baking the board before applying the soldermask removes residual solvents and moisture and helps to improve the adhesion and curing quality of the soldermask.

Soldermask Curing Methods: 

In addition to traditional hot air curing, technologies such as ultraviolet (UV) curing or electron beam curing can be used, which offer faster curing speeds and better environmental performance.

Soldermask Repairability: 

In some cases, the soldermask may be damaged or require modification. The use of repairable soldermask materials allows for necessary repairs or modifications to be made at a later stage.

Testing of Soldermask: 

In addition to electrical and physical testing, chemical testing, such as salt spray testing, can be performed to assess the corrosion resistance of the soldermask.


Further Considerations

Storage Conditions: 

Raw materials used in the soldermask process, such as soldermask, hardeners, etc., need to be stored under appropriate temperature and humidity conditions to maintain their properties and stability.


When applying different colours or types of soldermask, measures should be taken to prevent cross-contamination and to ensure the purity and performance of each material.

Records of Process Parameters: 

Detailed records of all process parameters in the soldermask process, including coating speed, temperature, humidity, etc., should be kept to facilitate tracking and reproducing the production process.

Employee Training: 

Regular training is provided to employees to improve their understanding of the soldermask process and their operational skills to ensure process consistency and reliability.

Continuous Improvement: 

By regularly reviewing and analysing production data and identifying potential problems and opportunities for improvement in the solder protection process, the process is continually optimised to improve product quality and productivity.

By taking these additional details and considerations into account, PCB manufacturers can further enhance the quality of the soldermask process to ensure that the boards provide reliable performance and long-term durability in a variety of applications.

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