Duplication of the failure mode means verifying that the reported failure symptoms (failure mode) of the component can be reproduced.
The failure symptoms should be duplicated for several reasons, including: (1) to assure that the reported failure mode exists in the component being analyzed (and therefore ensure that the correct component is being analyzed); (2) to determine what electrical stimulus method(s) can be used to reproduce the failure mode during analysis; and (3) to assure that additional or different failure modes have not been introduced during the activities prior to analysis, such as system troubleshooting, component removal, or delivery of the component to failure analysis.
The failure mode can be duplicated in a variety of ways, dependent upon the type of test equipment or testing services available to failure analyst. The following are several examples of methods used to duplicate the failure conditions. For all of the methods, it is important to have as detailed a description of the electrical failure conditions as possible in order to ensure that correct and complete duplication is achieved.
For components manufactured by the same company performing the analysis, it may be possible to retest the component using the same test equipment and test programs used during the manufacture of the component. This is often most desirable, since it stimulates and evaluates the performance of the component in a manner as similar as possible to the conditions prior to failure. This method can can be very useful if there is concern that the manufacturing test process did not detect the failure mechanism or defect (in other words, the failure existed prior to the manufacturing test and was not detected by the test; it was a test escape). Another method is to use the production test vectors on a different test system. For example, the manufacturing test may have been performed on a Sentry test system and the component is retested during failure analysis with an HP82000 test system using the Sentry test vectors translated into the HP82000 format. Depending upon the complexity of the component and the failure mode,it may also be possible to reproduce the failure mode using simple benchtop equipment, such as an HP4145 and a switch box to set the power, input, and I/O pins into their appropriate states.
It is very important that the reported failure mode be reproduced as soon as possible during the analysis. Normally, failure mode duplication is the first activity after visual examination of the component to ensure that the correct component has been received for analysis.