The following summarizes the ESS engineering guidance provided in this Section:
- Identify the nature of anticipated defects for unit
design and manufacturing processes.
Develop and finalize the ESS
- Select appropriate levels of assembly, e.g., printed wiring assembly, assembly, system, etc., at which ESS should be performed.
- Review product design.
Evaluate repair cost at various levels against fixture and ESS costs,
including teardown, repair, checkout, reassembly and the potential of
introducing new defects.
- Review available in-house and industry-wide data relative to the design of screening profiles for comparable equipment.
- Review product design information to identify any thermal characteristics of mechanical resonances/weakness which could impact detail of screening profiles.
- Tailor and finalize the temperature cycling screen, at each level of assembly selected, for temperature limits, product rate of temperature change, number of temperature cycles, and whether monitored during screen.
- Tailor and finalize the random vibration screen, at each level of assembly selected, for spectrum, gRMS level, number of axes, true random or quasi-random, and whether the product is monitored during screen.
- Optimize or modify the ESS profiles based on results from the screens and operational use.
- Assess the timeliness and comprehensiveness of the
FRACAS and assure that the corrective action process for any inadequate
manufacturing processes has been extended back to the OEM.
- Finalize the procedures governing reapplication
of ESS after correction of ESS related flaws.