Often, failing systems are so complex that it can be difficult to find a good starting point. A circuit board may be hundreds of square inches of densely packed discrete components, integrated circuits, and wiring; a schematic view may be so intricate as to require several feet of paper to print out. In these cases, electronic component failure analysis gains a whole new aspect of complexity; an analyst must be able to isolate the failing component amongst a plethora of other devices. At first glance, this may seem to be a Herculean task – devising a test program to analyze all the thousands of different components on a board is no easy feat. Fortunately, with the right approach, such an endeavor is not necessary.
Isolating a device for electronic component failure analysis starts by forming a plan of action. Given a specific failure mode, there are a limited number of possible explanations; by determining which of these is the most plausible, an analyst may begin to put together a theory that will help to limit the number of possible failing components. Board layouts and schematics are invaluable at this point – by allowing the analyst to see the hidden connections between devices, they enable a more straightforward determination of where a problem may exist. Once an analyst has developed a reasonably solid idea of where the defect may exist, the project can progress from the planning stages into action.
In order to prove their theory, an analyst must be able to provide concrete electrical data pinpointing the failing component. In order to accomplish this, it is often necessary to “modify” the failing circuit in order to narrow down the location of the failure. This process may be as simple as removing components from the board and checking to see if the reported failure is still present; in more complex cases, it may be necessary to carefully cut traces on a board in order to isolate a device from other parts of the circuit. Immediately following every circuit modification, additional electrical testing is necessary to determine whether the correct component has been identified; once the failing device has been found, failure analysis of the individual electronic component can begin.
The most satisfying moment of any electronic component failure analysis is the moment when a defect is finally revealed, clearly proclaiming the root cause of failure. However, a solid foundation must be built through diligent preparation before success can be achieved; in many cases, this preparation follows exactly these steps, wherein an analyst must first form a theory, then run through the iterative process of testing and isolation until a defective component can be identified. It is only once this initial work has been followed through to its conclusion that any anomalies can be brought to the surface.
Derek Snider is a failure analyst at Insight Analytical Labs, where he has worked since 2004. He is currently an undergraduate student at the University of Colorado, Colorado Springs, where he is pursuing a Bachelors of Science degree in Electrical Engineering.