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1) The solder fluidity is poor or the solder is withdrawn too early;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.