4.6 Analysis of the results and conclusions

4.6 ANALYSIS OF THE RESULTS AND CONCLUSIONS

After a successful FA there is enough information about the failure to make a conclusion about the cause and the mechanism of the failure. Validity of the FA results should always be evaluated, and the results of different FA steps and methods must be consistent.

When the FA is related to reliability testing there should be consistency between the stress caused by the testing and the FA results. But as the failure is usually an outcome of several causes there is always a possibility that something unexpected will reveal and the initial hypotheses of the failure mechanisms has to be adjusted according to the FA results.

If the FA is evaluated to be valid and causes of the failure is determined it is time to report the work. FA-report should include all relevant data of the samples and the used analysis methods as well as the conclusions. After that the actual failure analysis process is complete.

After the failure analysis is complete it is time to utilize the results by looping the information back to the design board and manufacturing process.

Failure analysis is a key tool during the whole lifespan of a product. During product and reliability design phase the results are used to correct the possible design or manufacturing errors. Besides just determining why a device failed the failure analysis results can be used to predict when a failure will occur.

Later when the product is in service the possible field failures should be failure analysed to reveal the possible previously undetected failure mechanisms or changes in the manufacturing process or in the materials.

36 • Mört & Sääski