In the process of PCBA production and processing, it is very important to ensure the quality of the product, and it is also very difficult to control. In actual production, there are many factors that affect the quality of the product. Only by understanding some precautions in the PCBA production and processing process can the quality of the product be effectively improved.
In the process of PCBA production and processing, matters needing attention include anti-static treatment, storage and use of solder paste, production and use of steel mesh, PCBA functional testing and operating specifications.
Static electricity is the most easily generated in our daily life, and it is not easy to detect. In the production and processing of PCBA, static electricity is very harmful to electronic components, and in severe cases, it will lead to component failure.
1. When in contact with electronic components or products, you must wear electrostatic clothing, electrostatic shoes and electrostatic wristbands.
2. The transportation of PCB power boards in the factory should be transported by special anti-static turnover vehicles.
3. The anti-static system must have a reliable anti-static system. The anti-static ground wire should not be connected to the power supply zero wire, and should not be shared with the lightning protection ground wire.
4. Regularly test the above anti-static tools, settings and materials to ensure that they can play an anti-static role.
Solder paste is used as a soldering material, how the quality of the solder paste will directly affect the quality of the product, and many details need to be paid attention to in the preservation and use of the solder paste.
1. When the solder paste is stored, it should be refrigerated, and the temperature should be kept at 2-8 degrees Celsius.
2. The temperature of the solder paste printing process should be kept between 20-25 degrees Celsius, and the ambient humidity of the solder paste of the PCBA board should be controlled between 40-50% RH.
3. The solder paste that has just been taken out of the storage room should be rewarmed naturally without opening the lid. The rewarming time should be 4-8 hours, and then start stirring.
In the process of printing solder paste, it is very important to print an appropriate amount of solder paste into the PCB pads. In the printing process, it is easy to cause problems such as more tin and less tin, which is closely related to the quality of the stencil.
1. The steel mesh port is generally 10 microns smaller than the IC tin pad, which can avoid the formation of bad solder balls on the PCBA board.
2. The stencil needs to be cleaned before each use. Generally, the stencil needs to be wiped once every 10 times of printing.
1. When using ICT equipment for testing, pay attention to the poor test caused by flux residue.
2. When the ICT test is completed, the power-on test can be started at the end.
1. Do not use skin-protecting grease or various detergents containing silicone resins, which can cause problems in solderability and adhesion of conformal coatings. Detergents specially formulated for PCBA soldering surfaces are available.
2. It is absolutely not allowed to stack the PCBA, otherwise physical damage will occur. The assembly surface of the PCBA board should be equipped with various special brackets.
3. Keep the workbench clean and tidy. There should be no food and beverages in the work area, smoking and placing cigarettes and ashtrays are prohibited.
4. Reduce the operation steps of PCBA and components to a minimum to prevent danger. In professional PCB assembly areas where gloves must be used, soiled gloves will contaminate the PCBA board, so gloves should be changed frequently if necessary.
5. As a general rule, the surface to be welded should not be taken with bare hands or fingers, because the grease secreted by human hands will reduce the solderability.
In the process of PCBA processing, the quality is very difficult to control, and any irregular operation and negligence will result in defective products.