16 Kinds Of PCB Soldering Defects

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Welding

1.Appearance characteristics

There is a clear black boundary line between the solder and the component lead or the copper foil, and the solder is recessed toward the boundary line.

2. Harm

Can not work normally.

3.Cause analysis

1) The component leads are not cleaned, tin-plated or oxidized.

2) The printed board is not cleaned well, and the quality of the sprayed flux is not good.

 

Solder accumulation

1.Appearance characteristics

The solder joint structure is loose, white, and matte.

2. Harm

Insufficient mechanical strength, may be welded.

3.Cause analysis

1) The solder quality is not good.

2) The welding temperature is insufficient.

3) When the solder is not solidified, the component leads are loose.

 

Too much solder

1.Appearance characteristics

The solder surface is convex.

2. Harm

Solder is wasted and defects can be trapped.

3.Cause analysis

Solder withdrawal was too late.

 

Too little solder

1.Appearance characteristics

The soldering area is less than 80% of the pad.

2. Harm

Insufficient mechanical strength.

3.Cause analysis

1) Poor solder fluidity or premature solder withdrawal.

2) Insufficient flux.

3) The welding time is too short.

 

Rosin welding

1.Appearance characteristics

Rosin residue was trapped in the weld.

2.Harm

Insufficient strength, poor continuity, and sometimes on and off.

3.Cause analysis

1) Welders are too many or have failed.

2) Insufficient welding time and insufficient heating.

3) The surface oxide film is not removed.

 

Overheating

1.Appearance characteristics

The solder joints are white, without metallic luster, and the surface is rough.

2. Harm

The pads are easy to peel off and the strength is reduced.

3.Cause analysis

The power of the soldering iron is too high and the heating time is too long.

 

Cold welding

1.Appearance characteristics

The surface is made of tofu-like particles, which may sometimes have cracks.

2. Harm

Low strength and poor conductivity.

3.Cause analysis

There is jitter before the solder solidifies.

 

Poor infiltration

1.Appearance characteristics

The interface between solder and weldment is too large and not smooth.

2. Harm

Low strength, intermittent or intermittent.

3.Cause analysis

1) Weldments are not cleaned.

2) Insufficient or poor quality flux.

3) The weldment is not sufficiently heated.

 

Asymmetry

1.Appearance characteristics

Solder does not flow across the pad.

2. Harm

Insufficient strength.

3.Cause analysis

1) The solder has poor fluidity.

2) Insufficient or poor quality flux.

3) Insufficient heating.

 

Loose

1.Appearance characteristics

Wire or component leads are removable.

2. Harm

Poor or non-conducting.

3.Cause analysis

1) The lead moves before the solder solidifies, causing voids.

2) The lead is not treated well (poor wetting or not wet).

 

Partially outstanding

1.Appearance characteristics

The tip appears.

2. Harm

Poor appearance, easy to cause bridging phenomenon.

3.Cause analysis

1) Too little flux and too long heating time.

2) Improper soldering iron withdrawal angle.

 

Bridging

1.Appearance characteristics

Adjacent wires are connected.

2. Harm

Electrical short.

3.Cause analysis

1) Too much solder.

2) Improper soldering iron withdrawal angle.

Common defects, hazards, and cause analysis of circuit board welding

 

Pinhole

1.Appearance characteristics

There are holes in the visual inspection or low magnification amplifier.

2. Harm

Insufficient strength, solder joints are easily corroded.

3.Cause analysis

The gap between the lead and the pad hole is too large.

 

Bubble

1.Appearance characteristics

The root of the lead has a spray-type solder bump, and a cavity is hidden inside.

2. Harm

Temporary conduction, but it is easy to cause poor conduction for a long time.

3.Cause analysis

1) The gap between the lead and the pad hole is large.

2) Poor lead wetting.

3) The double-panel plugging of the through hole takes a long time to weld and the air in the hole expands.

 

Copper foil lift

1.Appearance characteristics

The copper foil was peeled from the printed board.

2. Harm

The printed board is damaged.

3.Cause analysis

The welding time is too long and the temperature is too high.

 

Strip

1.Appearance characteristics

The solder joint is peeled off from the copper foil (not the copper foil from the printed board).

2. Harm

Open circuit.

3.Cause analysis

Defective metal plating on the pad.