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Unfortunately, and as much as some
would like you to believe, standard
parts are generally not of a high
enough performance or quality
to be suitable for use in harsh
environments, such as defence,
aerospace and space applications.
Extremes of shock, vibration and
temperature, extended life cycles,
possible attack by gases and liquids
require components that have been
designed to work under specific and
often very demanding conditions.
Not only that, but they must be ultra-
reliable…often such applications
simply must not fail, either because
failure would risk life, or the cost
of failure would be astronomical
(sometimes literally!).
The most widely specified and used
standard governing such ‘high-
performance’ parts is the US defence
standard known as MIL -STD. A huge
variety of electronic components –
active, passive, emech, interconnect,
hybrid and even sub-systems – are
covered by various different MIL-
STDs which govern the manufacture
and testing of the parts in question.
All well and good, but there is
a problem. MIL-STD numbers
are associated with a specific
component. Developing MIL-STDs
for new parts is a long process, and
once the standard is developed, for a
component manufacturer to get that
part listed is a long a costly process.
What this means is that engineers
working on designs that require
high performance, high reliability
components will be limited to older
technology components, as new
smaller, lighter, faster – maybe even
cheaper – parts will not yet have had
a MIL-STD created for them, or of it
has, the manufacturer may not yet
have received approval.
Luckily a couple of alternatives are
emerging.
COTS+
Many engineers will have heard
the term COTS – Commercial Off-
The-Shelf. In the USA, COTS is a
Federal Acquisition Regulation (FAR)
term for commercially-available
items and services that can be
bought and used under government
contract. It has come to be a
widely used term, and the concept
appears especially appealing in
the light of defence budget cuts
and restrictions. However, to put it
COTS
+
and DSCC parts emerge as alternatives
to MIL-STD
Lee Thompson, TTI Inc.
60 l New-Tech Magazine Europe