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Common Welding Defects and Cause Analysis of PCBA Processing

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Published by: Keyou November 04,2019

PCBA processing is a complex processing process that requires inspection and cooperation in all aspects to produce high quality PCBA products.

 

1. Poor wetting: Poor wetting is manifested in poor soldering on the PCB pad or poor soldering of the component pins.

Causes: Component leads/PCB pads have been oxidized/contaminated; too low reflow temperature; poor solder paste quality results in poor wettability and severe soldering in severe cases.

2. Small amount of solder joint tin: The small amount of solder joint tin is characterized by insufficient solder joints and a small monthly curved surface at the root of the IC pin.

Cause: The printing template window is small; the wick phenomenon (poor temperature curve); the solder paste metal content is low. One of the above reasons will result in a small amount of tin and insufficient solder joint strength.

3. Pin damage: Pin damage is caused by poor coplanarity or bending of the device pins, which directly affects the soldering quality.

Cause: In case of damage during transportation/handling, care should be taken to store components, especially FQFP.

4. Pads are covered by contaminants: Pads are covered by contaminants during PCBA production.

Cause: Paper from the scene; foreign matter from the tape; hand touch PCB pads or components; the character map is not in the right position. At the time of production, attention should be paid to the cleaning of the production site, and the process should be standardized.

5.The amount of solder paste is insufficient: insufficient solder paste is also a phenomenon that often occurs in PCBA production.

Cause: The first PCB printing / printing after the machine stops; the printing process parameters change; the steel plate window is blocked; the quality of the solder paste is deteriorated.

6.The solder paste is angular: PCBA production often occurs and is not easy to find, in case of serious welding.

Cause: The solder paste printing machine lifts the web too fast; the template hole wall is not smooth, and the solder paste is easy to make the it shape.

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