This publication addresses specific design and manufacturing
fundamentals. To this end, it is essential that readers responsible for
implementing low-voltage power supply designs (program managers, engineering
managers, design engineers, et al.) become familiar with the contents of Section 4
Designing reliable low-voltage power supplies requires accounting for
the effects of peak instantaneous transients, applying conservative derating
practices which result in operation at low junction/hot-spot temperatures, and
using printed wiring boards and connectors instead of point-to-point wiring
and wiring harnesses. Maintaining inherent reliability through manufacturing
requires tight control of processes and the application of stringent
environmental stress screening. These design and manufacturing principles have
been used successfully in power supplies demonstrating over 200,000 hours of
service between failures.
Power supply complexity is not generally
recognized or understood. Damage and failures can occur as a result of the
adverse conditions and effects listed in Table 2-1.
There is a large database which clearly indicates that subjecting all
electronic hardware to thermal cycling and random vibration during
manufacturing is a very effective method of purging workmanship failures from
the equipment and thus provides the ultimate user with reliable equipment.
While NAVMAT P-9492 describes such testing, detailed guidelines are provided
in paragraph 4.6 of this document.
The Navy's approach to reliable
hardware is based on (1) designing for inherent reliability and (2)
manufacturing to ensure that the inherent reliability is in fact achieved in
production. However, this approach does not advocate measuring reliability
after the "design improvement" window has been passed. Rather, it makes
reliability measurement tools integral to the design process and specifies and
manages hardware engineering fundamentals to create reliable