Common solder joints in SMT: solder balls

solutions

1. After the solder paste is taken out of the refrigerator, it should not be opened immediately. It should be placed for more than 4 hours. After the temperature of the solder paste in the sealed cylinder is stable, open the cover.

2. It is strictly forbidden to touch the welding surface of the circuit board and the soldering feet of the components with bare hands;

3. The thickness of the solder particles should be uniform. Generally, the number of particles below 25p m should not exceed 5% of the total number of solder particles;

4. Improve the metal content of the solder paste, generally the metal content of the solder paste is between 65% and 96%;

5. Elimination of solder bumps, misalignment, etc. The practice has proved that it is ideal to control the temperature rise of the preheating zone at 1 to 4 degrees Celsius.

Common weld defects in SMT: poor wetting

solutions

1. Do not store components in a humid environment, do not exceed the specified period of use, and clean and dry the printed board;

2. Choose the right solder;

Common welding defects in SMT: slab phenomenon

solutions

1. Set the process parameters of the preheating period correctly to achieve uniform heating during welding;

2. Perform pad design in strict accordance with standard specifications;

3. When selecting components. If possible, priority should be given to components with larger dimensions and weight.