Keyword: pcb, pcb board, printed circuit board
Solder Starved A solder starved joint simply does not have enough pcb board solder. It may make good electrical contact, but it is hard to verify by inspection. In any case pcb board, it is not a strong joint and may develop stress cracks and fail over time.
Repair: Re-heat the joint and add more solder to make a good strong joint. pcb board Too Much Solder This might be a perfectly good joint, but we can't tell for sure. It is entirely possible that this blob of solder wets neither the pin nor the pad and is not a reliable electrical connection. The best evidence of proper wetting (and good electrical contact) is a nice concave surface as on the joint on the far left pcb board.
Repair: It is usually possible to pcb board draw off some of the excess solder with the tip of a hot iron. In extreme cases, a solder-sucker or some solder wick can be helpful as well. Untrimmed Leads Leads that are too long are potential short circuits. The two joints on the left are an obvious danger of touching. But the one on the right is long enough to pcb board be dangerous as well. It would not take much force to bend that lead over to touch an adjacent trace.
Repair: Trim all leads just at the top of the solder joint.pcb board Solder Bridge pcb board The left two solder joints have melted together, forming an unintended connection between the two.
Repair: Sometimes the excess solder can be drawn off by dragging the tip of a hot iron between the two solder joints pcb board. If there is too much solder, a solder sucker or solder wick can help get rid of the excess. Prevention: Solder bridges most often happen between joints with too much solder to begin with. Use only enough solder to make a good joint. Lifted Pad pcb board This photo shows a solder pad that has become detached from the surface of the circuit board. This most often occurs when trying to de-solder components from the board. But it can result simply from overworking the joint to the point where the adhesive bond between copper and the board is destroyed. Lifted pads are especially common on boards with thin copper layers and/or no through-plating on the holes pcb board.
Repair:It may not be pretty, but a lifted pad can usually be repaired. pcb board The simplest repair is to fold the lead over to a still-attached copper trace and solder it as shown to the left. If your board has a solder-mask, you will need to carefully scrape off enough to expose the bare copper. Other alternatives are to follow the trace to the next via and run a jumper to there. Or, in the worst case, follow the trace to the nearest component and solder your jumper to the leg of that. Not exactly pretty, but functional. Stray Solder Spatters These bits of solder are held to the board only by sticky flux residue. If they work loose, pcb board they can easily cause a short circuit on the board.
Repair: pcb board These are easy to remove with the tip of a knife or tweezers.
