What aspects of a PCB affect PCBA quality?
2023-12-09
PCBA manufacturing and processing is a very complex process, and the whole PCBA processing seems to be only one word different from the PCB, but in fact, the poor process is very different. PCBA needs to carry out a series of back-end processes on the PCB, such as solder paste printing, SPI inspection, SMT processing, reflow soldering, DIP plug-in post-soldering, wave soldering/selective wave soldering, PCBA first article inspection, etc., these processes are not available in PCB.
However, because all the following processes are placed on the operation of the PCB board, the quality of the PCB determines the quality of the entire PCBA, so what aspects of the PCB have an impact on the PCBA?
However, because all the following processes are placed on the operation of the PCB board, the quality of the PCB determines the quality of the entire PCBA, so what aspects of the PCB have an impact on the PCBA?
1. The board surface is dirty
Dirty board surface is mainly caused by high flux solid content, excessive coating amount, high or low preheating temperature, or due to too dirty PCB gripping jaws on the conveyor belt, too much oxide and solder dross in the solder tank, etc.
The main solutions are to select the appropriate flux, control the amount of flux coated, control the preheating temperature, check the cleaning effect of the automatic cleaning PCB clamping jaw and take measures, and clean the oxide and solder slag on the surface of the solder groove in time.
2. The white line retention
White residue is commonly known as hoarfrost. Although it does not affect the surface insulation resistance, it is not accepted by the customer.
Solution: Use flux first, and then use solvent to clean, if it can't be cleaned, it may be due to the expiration of the flux, or exposure to the air to absorb water vapor, or because the moisture content in the cleaning agent (solvent) is too high, or the flux and the cleaning agent do not match, the supplier should be asked to assist in solving or replacing the flux and cleaning agent.
3. PCB deformation
PCB deformation is mainly caused by the large size of the PCB or the uneven arrangement of components.
When designing the PCB, try to make the components evenly distributed, design a support belt in the middle of the large-size PCB (design a non-deployed component area with a width of 2~3mm), or use a mass balance tooling to press the sparse position of the components on the PCB, and achieve mass balance during soldering.
PCB board assembly process requirements
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