Sixteen Common Welding Defects in Circuit Board Processing (Part 2)

9. Asymmetry

a.) Appearance Characteristics: The solder does not flow to the pad.

b.) Hazards:  Insufficient strength.

c.) Possible Causes:

— The solder has poor fluidity.

— Insufficient flux or poor quality.

— Insufficient heating.

10. Loose

a.) Appearance Characteristics: The wire or component lead can be moved.

b.) Hazards:  Poor or non-conduction.

c.) Possible Causes:

— Leads move before the solder is solidified and cause voids.

— The lead is not processed well (poor or not wetted).

11. Sharpen the Tip

a.) Appearance Characteristics:  The tip is showing.

b.) Hazards: Poor appearance can easily cause bridging.

c.) Possible Causes:

— Too little flux and too long heating time.

— Improper evacuation angle of the soldering iron.

12. Bridge

a.) Appearance Characteristics:  Adjacent wires are connected.

b.) Hazards: Electrical short circuit.

c.) Possible Causes:

— Too much solder.

— Improper evacuation angle of the soldering iron.

13. Pinhole

a.) Appearance Characteristics:  Visual inspection or low-power amplifier can see holes.

b.) Hazards: The strength is insufficient, and the solder joints are easily corroded.

c.) Possible Causes:

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

14. Bubbles

a.) Appearance Characteristics:  There is a spit-fire solder bulge at the root of the lead, and a cavity is hidden inside.

b.) Hazards: Temporary conduction, but it is easy to cause poor conduction for a long time.

c.) Possible Causes:

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

— Poor lead infiltration.

— The welding time of the double-sided board plugging the through hole is long, and the air in the hole expands.

15. Copper Foil is Upturned

a.) Appearance Characteristics:  The copper foil is peeled from the printed board.

b.) Hazards: The printed board is damaged.

c.) Possible Causes:

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

16. Stripping
a.) Appearance Characteristics:  The solder joints peeled off from the copper foil (not the copper foil and the printed board peeled off).
b.) Hazards:  Open circuit.
c.) Possible Causes:
— Bad metal plating on the pad.