Issue link: https://iconnect007.uberflip.com/i/1166358
42 PCB007 MAGAZINE I SEPTEMBER 2019 latest build specification is to be used. Older designs by OEM military contractors may call for older revisions of say MIL-PRF-31032, 55110, and 50884. For electrical test (ET), this can be especially significant. Advances in test technology have brought new methodologies that were not allowed or even known in the older revisions of specifi- cations. Just because the latest revision of a specification allows the use of these technolo- gies, one cannot assume the new options ap- ply. If an older specification is called, the re- quirements of that specification shall be used. This can be challenging for a third-party ET contractor. Many times, the ET contractor may have ac- cess to the master drawing only when the order is being processed. Job-specific notes may be added to the ET database for future reference, but special notes may be lost when the job re- turns to the fabrication house. This is where it is crucial to save the notes or retain a copy of the master drawing. Most ET contractors will have NDAs with their fabrication houses, so this isn't usually a problem. However, this be- comes extremely important when the fabrica- tion house or ET contractor is audited and al- lows absolute traceability and assurance that the product was built and tested as originally designed. Certificate of Compliance Documents This brings up another item that comes up quite frequently on the certificate of compli- ance (C of C) documents for ET. What specifi- cation should appear on the C of C for ET is a confusing topic. A master drawing may state, "Build to IPC-6012D." Should the ET C of C state IPC-6012D? The answer is no. If the C of C were to say IPC-6012D, it could be inter- preted that the ET C of C is certifying the entire build, which it is not; it is only certifying the product was tested. Reading the fine print in most build speci- fications will state that ET shall be in accor- dance with IPC-9252; that is the specific speci- fication regarding ET of unpopulated printed wiring boards. The exception is when the aerospace and military avionics addendums are called from either 6012C or 6012DS. These require atypical test parameters outside of the standard 9252, and those specifications should appear on the C of C, in this case. Military Just because MIL-PRF-31032 is the current specification does not mean that it is auto- matic. Many military master drawings call out MIL-PRF-55110. MIL-PRF-55110 is alive and well, and if called, shall be used. But there is a vast inventory of military products out there that was designed long before the release of MIL-PRF-31032. Reorders of these products will require adherence to the older specifica- tion. Fabrication houses and ET contractors must be aware of this and adjust build and test methodologies to be compliant with the speci- fication. Another common issue is with MIL- PRF-31032 and the performance "slash sheets." An ET C of C is non-compliant if it just states MIL-PRF-32032. The Defense Lo - gistics Agency (DLA) is very specific on this issue. A build to MIL-PRF-31032 must also state which applicable slash sheet the prod- uct was built to and also tested. This will be MIL-PRF-31032/1, /2, /3, /4, /5, or /6 with their appropriate revision and amendment level if applicable. The fine print here is that if the performance class (slash sheet) is not provided in the procurement and/or master drawing, this must be remedied before build and test. Failure to do so can (and will) result in a nonconformance during a DLA audit, so be forewarned. Advances in test technology have brought new methodologies that were not allowed or even known in the older revisions of specifications.