Journal of SMT Article

Case Histories in Failure Analysis of Electronics Assemblies

Author: Vladimir Igoshev
Company: SENTEC Testing Laboratory Inc.
Date Published: 7/30/2011   Volume: 24-3

Abstract: Several case histories of failure analysis of "typical" problems for electronics assemblies will be presented. Even though the selected cases originally looked as "typical" problems, in depth analysis was required to establish the actual root cause for each of the problems.

When an electronics company faces an assembly problem either due to improper processing (surface mount technology, wave, ctc.), or defective components they must perform analyses on the process/components/printed wiring boards (PWB) Inspection capabilities of the vast majority of electronics manufacturing service (EMS) companies are limited only to visual, using stereo microscopy with the maximum power of 70x, or more powerful reflected light microscopes. In many cases it may not be sufficient to solve the problem, or even resolve some features in structural elements of a board, e.g. microvias. Therefore, even though it’s obvious where to look it may not be that easy to establish exactly what the root cause of the problem is.

To overcome "the lack of technical ammunition" the company would try different things to solve the problem. The process could be tweaked or the suspect components could be tempered with (particularly BGAs) or replaced. It may take several days to try everything and even if the problem goes away, there will be no guarantee the same issue(s) will not pop up again, because the REAL root cause for the problem has never been established.

Alternatively, if proper failure analysis is done and the root cause for a problem established [1], then appropriate corrective actions can be implemented to avoid the same issue in the future. Although solving problems this way may involve the cost of hiring a testing/failure analysis contractor, it often saves time and definitely money in the long run and usually results in a more satisfied customer because proper analysis has been done.

In real life, a company would try everything to solve a problem in house and only then would they think of hiring a third party to solve it. The majority of case histories below represent similar situations.

Keywords: 

Root cause analysis



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