Today's Designer
IEN / DECEMBER '16
33
www.ien.com
M
ore than 70%
of all passive
components on
the market are commer-
cial-grade, or designed
for use in consumer or
industrial applications, in-
cluding cellphones, com-
puters, appliances and
the machinery required
to manufacture such
products. Another 25%
or so are designed for
use in automotive appli-
cations, and fewer than
5% are especially de-
signed for use in high-re-
liability medical, military
and aerospace applica-
tions. The components
that comprise each of
these categories tend to
be more alike than not,
but their slight differenc-
es can prove immensely
impactful in more critical
applications like autono-
mous vehicles and med-
ical devices. In general,
the more critical a com-
ponent is to the success-
ful operation of an end
device, and the more
potential the end device
has to cause harm, the
more regulations it has to
comply with before it can
be released to market or
approved for design-in.
Since there are signifi-
cantly more commercial
components on the mar-
ket than medical compo-
nents, it can be extremely
tempting to design them
into medical devices, and
especially those that are
external/non-implantable
and non-life-supporting.
Doing so, however, could
cause serious problems.
Commercial compo-
nents are generally of-
fered with a wide range
of performance charac-
teristics, as this enables
both maximum compat-
ibility with various man-
ufacturing materials and
processes, and allows
the same part number
to be slightly modified
and supplied in any one
of several different ways
to satisfy circuit require-
ments for an extensive
range of end products.
This parametric flexibility
presents little risk for con-
sumer products, which
tend to be fairly easy to
repair or replace, but can
present significant risks
in medical devices.
Commercial Components vs.
Medical Components: Why Design
Controls are Necessary, & How to Make
Compliance Less of a Headache
by Lizzie Geismar, Product Marketing Manager, Medical Division & High-Reliability Tantalum, AVX Corporation