PCB board soldering is an important process in PCB circuit board proofing. When we make PCB, we often see many soldering defects. So, what are the common soldering defects of custom made pcb boards?
1. Virtual soldering: There is a clear black boundary between the solder and the lead of the component or with the copper foil, and the solder is recessed toward the boundary.
Hazard: The custom made PCB boards do not work properly.
Reasons: 1) The component leads are not cleaned well, tinned or oxidized; 2) The printed circuit board is not cleaned well, and the sprayed flux is of poor quality.
2. Solder accumulation: The solder joint structure is loose, white and dull.
Hazard: insufficient mechanical strength, possible false welding.
Reasons: 1) The quality of solder is not good; 2) The soldering temperature is not enough; 3) The leads of components are loose.
3. Too much solder: the solder surface is convex.
Hazard: Waste solder, and may contain defects.
Reason: The solder evacuation was too late.
4. Too little solder: The soldering area of the PCB board is less than 80% of the pad, and the solder does not form a smooth transition surface.
Harm: Lead to insufficient mechanical strength of the circuit board.
Reasons: 1) poor solder fluidity or premature solder withdrawal; 2) insufficient flux; 3) too short soldering time.
5. Rosin welding: There is rosin residue in the weld.
Hazard: Insufficient strength, poor continuity, and may be on and off.
Reasons: 1) too many welders or failure; 2) insufficient welding time and insufficient heating; 3) surface oxide film is not removed.
6. Overheating: The solder joints are white, 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: After the PCB board soldering, the surface becomes tofu-like particles, and sometimes there may be cracks.
Harm: low strength, poor conductivity.
Reason: The solder shakes before it solidifies.
8. Poor wetting: The interface between the solder and the solder is too large and not smooth.
Hazard: Low strength, blocked or intermittently connected.
Reasons: 1) The weldment is not cleaned up; 2) The flux is insufficient or poor quality; 3) The weldment is not fully heated.