What are the common soldering defects of Multi-layer PCB
Now Sun&Lynn Multi-layer PCB factory will explain to you what are the common soldering defects of PCB circuit 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 circuit board does not work properly.
Reason:
1) Leads of components are not cleaned, tinned or oxidized;
2) The printed circuit board is not clean, and the sprayed flux is of poor quality.
2. Solder accumulation:
The solder joint structure is loose, white and dull.
Hazard: Insufficient mechanical strength, possibly false welding.
Reason:
1) The solder quality is not good;
2) The welding temperature is not enough;
3) The leads of the 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 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1) The solder fluidity is poor or the solder is withdrawn too early;
2) Insufficient flux;
3) The welding time is too short.
5. Rosin welding:
There is rosin slag in the weld.
Hazard: Insufficient strength, poor continuity, and may be switched on and off.
Reason:
1) Too many welders or have failed;
2) Insufficient welding time and insufficient heating;
3) The surface oxide film is not removed.
6. Overheating:
The solder joints are white, no 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, sometimes there may be cracks.
Harm: Low strength and poor conductivity.
Reason: The solder shakes before it solidifies.
8. Poor wetting:
The contact between the solder and the soldering interface is too large and not smooth.
Hazard: Low strength, unavailable or intermittently on and off.
Reason:
1) The weldment is not cleaned up;
2) Insufficient flux or poor quality;
3) The weldment is not fully heated.
The above is the analysis of the common soldering defects of PCB circuit boards. I hope everyone can avoid them in practice.
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