You will most often see pad lifting on a single-sided board in the course of assembly. If you have plated-through hole boards, it is unlikely pad lifting will occur, although it is not impossible. Anytime you have the combination of extreme heat and serious physical handling, pad lifting is a possibility to consider.
What causes pad lifting on PCB?
Most commonly with single-sided boards, after the wave soldering, the heating up of the surface can lower the adhesion of the copper, so any force you apply to the components may cause lifting. Essentially, you have to consider two elements: the thermal factor and the physical factor. The more heat you apply during wave soldering and other assembly processes, and the more energy with which you handle the printed circuit boards, the more likely you will have components come loose and pads lifting.
How to avoid pad lifting on PCB?
Is there anything you can do to prevent pad lifting with respect to printed circuit boards? There is little you can do about the thermal element. You can try to use an epoxy with high thermal resistance, but it is inevitable that any prolonged, high degree of heat will reduce adhesion. Again, one solution is to use plated-through hole boards, which make it much harder for pads and components to come loose.
You have much more control over the mechanical aspects of pad lifting. To avoid pad lifting on a printed circuit board, it’s important to take single-sided boards off the conveyor or out of pallets very carefully, and make sure your operators do not use large components as handles. In general, whenever you think there is a danger of pad lifting, handle those printed circuit boards with extra care.
How to fix PCB with loose pad?
If you don’t want to trash the printed circuit board and start over with a new one, there are a number of things you can try. For example:
- Find where the trace the pad lifted from starts and ends, then run wires to every disconnected point. For the pad that lifted, stick the component through the hole and solder your wire to the component leg.
- Glue the pad back to the circuit board with a strong epoxy.
- Bend the component lead to replace the track where the solder pad/trace that lifted should be and solder it directly to the track that still has a connection to the board. If the lead is too short, solder an extension onto the lead, then proceed.
Is it worth to fix pad lifting on PCB?
While all of these methods can be effective, if you are reselling your printed circuit boards or you are using them as components in products you are reselling, you may not want to use these methods, as there is still a risk of failure. If you are confident you can successfully work around a lifted pad problem, or if you don’t mind repairing the product for the consumer should it fail again, you should consider one of these methods. If you don’t want to risk customers calling you for repair on a product with a printed circuit board that has had lifted pads, you may want to consider discarding this PCB and starting over with a new circuit board.
If you are repeatedly getting printed circuit boards from your PCB distributor with lifted pads, or pads that lift with normal handling after you receive them — especially if you are experiencing lifted pad problems with plated-through hole boards — you should strongly consider changing your PCB distributor.