Soldering defects are solder joints that are not soldered correctly. These defects may arise when solder temperature is too low. When the base metals are too cold, the solder will not flow and will "ball up", without creating the metallurgial bond. An incorrect solder type (for example, electronics solder for mechanical joints or vice versa) will lead to a weak joint. An incorrect or missing flux can corrode the metals in the joint. Without flux the joint may not be clean. A dirty or contaminated joint leads to a weak bond. A lack of solder on a joint will make the joint fail. An excess of solder can create a "solder bridge" which is a short circuit. Movement of metals being soldered before the solder has cooled will make the solder appear grainy and may cause a weakened joint.
Soldering defects in electronics can lead to short circuits, high resistance in the joint, intermittent connections, components overheating, and damaged circuit boards. Flux left around integrated circuits' leads will lead to inter-lead leakage. It is a big issue on surface mount components and causes improper device operation as moisture absorption rises, In mechanical joints defects lead to joint failure and corrosion.
