Welding is an important process in PCB circuit board proofing. When we make PCBs, we often see many soldering defects. So, what are the common soldering defects of PCB circuit boards?
1. False soldering: There is an obvious black boundary line between the solder and the component lead or copper foil, and the solder is sunken toward the boundary line.
Hazard: The circuit board will not work properly.
reason:
1) The component leads are not cleaned well, not tinned or oxidized;
2) The printed board is not cleaned well, and the quality of the sprayed flux is not good.
2. Solder accumulation: The structure of solder joints is loose, white and dull.
Hazard: Insufficient mechanical strength, possible false welding.
reason:
1) The solder quality is not good;
2) The welding temperature is not enough;
3) The component leads are loose.
3. Too much solder: The solder surface is convex.
Hazard: Wastes solder and may harbor defects.
Reason: Solder removal is too late.
4. Too little solder: The soldering area is less than 80% of the pad, and the solder does not form a smooth transition surface.
Hazard: Insufficient mechanical strength of the circuit board.
reason:
1) Poor solder fluidity or premature removal of solder;
2) Insufficient flux;
3) Welding time is too short.
5. Rosin welding: There is rosin slag in the weld.
Hazard: Insufficient strength, poor conduction, may be on and off sometimes.
reason:
1) There are too many welde or have failed;
2) Insufficient welding time and insufficient heating;
3) The oxide film on the surface is not removed.
6. Overheating: The solder joints are whitish, without metallic luster, and the surface is rough.
Hazard: The pad is easy to peel off and the strength is reduced.
Reason: The power of the soldering iron is too large, and the heating time is too long.
7. Cold welding: the surface becomes tofu-like particles, and sometimes there may be cracks.
Hazard: low strength, poor electrical conductivity.
Reason: There is vibration before the solder solidifies.
8. Poor infiltration: the contact between the solder and the weldment is too large and not smooth.
Hazards: low intensity, blocked or disconnected from time to time.
reason:
1) The weldment is not clean;
2) Insufficient flux or poor quality;
3) The weldment is not fully heated.
The above is the analysis of common soldering defects on PCB circuit boards. I hope you have some understanding of these defects and try to avoid them in practice.
