Printed Circuit Boards-Dirty PCB
by Howie Liu Electronics Engineer
The Printed Circuit Boards are sometime corroded due to a number of reasons. Some of the reasons are its exposure to the moisture or some other agents might also corrode it. These are then called as dirty PCBs. There is a proper technique to make such PCBs back to working condition.
Steps for the Recovery of Dirty PCBs
When any of the dirty PCBs are returned back to the manufacturing company due to some reasons, the company is firstly investigating the agents due to which the corrosion has happened. Finding the contamination agent is very vital in fashioning a strategy for the recovery of the PCBs. There are numerous techniques through which the composition of the contaminants could be determined. By the time when the composition of the contaminant is known, the agents can be determined due to which the corrosion has happened.
The Use of Electron Microscope
First of all the dirty PCB which is corroded is being scanned through a dedicated microscope known as the electron microscope. The electron microscope is well equipped with the x-ray detector which is also energy dispersive. However, the electron microscope is unable to detect whether the composition is of more than one element or of a single element.
Example of Pictures
In both the pictures above, the lower layers are open circuited due to the circuit breakage. The main problem is that the solder mask is opened and as a result the circuit breakage occurred. This is why the dirty PCB is not working anymore. The PCB has been exposed to an environment having highly oxidized copper. The dirty PCBs in both of the above pictures are having an evidence that the conduction among the conduction has been happening and is evident from the epoxy layer among the conductors. This proved that the corrosion has occurred because of natural factors.
Created on Oct 23rd 2017 04:50. Viewed 550 times.