These are common defects associated with soldering iron and involve the final result being solder-starved or having excess solder. These lead to instable joints, poor electrical connections and failure of components. We look at how the problems come to be and how to solve them.
Excess solder on the other hand occurs when too much solder is applied on a component lead or pad or both. This usually results in an almost spherical ball of solder. The downside to excess solder is that in most instances, wetting is very poor with the lead and pad and may therefore lead to a very poor electrical connection.
In soldering, a solder-starved joint is the point of a bond formed by molten solder that did not receive as much solder as required. Solder starved joints can be caused by a wide range of factors including incorrect soldering temperatures, poor contact between the solder and iron tip and use of poor quality solder. A solder-starved joint often develops cracks with time, forms poor bonding of components and is thus generally unreliable as a contact point especially in soldered electrical components. There are however easy solutions to these problems. These include:
Desoldering and resoldering
For excess solder, the easiest solution is to desolder the joint and remove all the solder. After this, redo the soldering taking care to feed just the right amount of solder into the joint. The end result should be a symmetrical concave shaped mound of solder that is even on all sides. For a solder-starved joint, desoldering may not be necessary since all that is needed is the application of additional solder on the joint. It however takes a bit of time, practice and a few mistakes to make the perfect solder joint.