July 11,
2007
Defense
and Aerospace Watch as Leaded Parts Disappear
Last
year, in the middle of the transition to RoHS-compliant parts, I spoke with a
defense contractor who noted that the shift to lead-free parts wouldn’t affect
his business because the defense and aerospace industries were exempt from the
RoHS directive. Then he paused and said, “Maybe I have my head in the sand.”
Now
that the RoHS deadline of July 1, 2006 is more than a year old, the great irony
is that the defense and aerospace industries – that are exempt from the RoHS
directive – have been more profoundly affected by the law than the consumer
electronics manufacturers that have to comply with RoHS. For consumer product
manufacturers, their COTS components became available in lead-free versions.
The transition was relatively smooth. Defense and aerospace manufacturers,
however, suddenly found they were no longer able to procure leaded versions of
COTS parts. Nor were they willing to use the lead-free parts, since they
haven’t been exhaustively tested for reliability in harsh environments.
The
defense and aerospace manufacturers still want their COTS components. COTS are
cheap, and in their leaded versions, they’re reliable. Unfortunately, most COTS
parts have shifted to lead-free-only versions. “Off-the-shelf parts have
absolutely gone RoHS,” says Tom Barnum, VP of sales for VersaLogic, a company
that produces rugged computers for defense contractors. “But the military and
aerospace customers only make up about 1 percent of their business.” Because of
this, most component manufacturers have phased out the leaded version of their
products. The market for non-compliant, leaded product was simply too small to
justify running two lines, one leaded and one lead-free.
Yet
the defense industry has come to depend on the inexpensive COTS components. The
problem goes back to the $800 toilet seat and $500 coffee maker. For decades,
military products were custom made in small quantities. They were ruggedized
and designed for harsh environments, which differ dramatically from commercial,
consumer products. But in the mid-1980s, legislators balked at the seemingly
ridiculous costs for military products that were available in inexpensive
consumer versions.
In
response, the defense and aerospace industries started buying consumer
off-the-shelf (COTS) components. The reliability was assured because the
components were produced with the traditional solder and finishes that were
made up of tin with lead added to mitigate tin whiskers. Tin whiskers grow on
pure tin when the component is exposed to the harsh environments and long-term
use that’s common with military and aerospace products. Those tin whiskers can
break off and cause shorts that lead to component failure.
While
component manufacturers shifted to lead-free versions to comply with RoHS,
their defense and aerospace customers still clamored for leaded parts for fear
tin whiskers would grow when the lead-free components were exposed to harsh
environments. “We inform these contractors that we will conform to their
request for non-compliant product just so long as the manufacturer they call
out on the purchase order is still manufacturing the respective product,” says
Jeff Shafer, VP of product at component distributor, Newark InOne. Problem is, Shafer
finds that many of those component manufacturers on the purchase orders no
longer produce non-compliant – or leaded – parts.
In
the absence of leaded parts produced as COTS, defense and aerospace
manufacturers have the option of turning to high-reliability military
specification (mil-spec) parts. But those parts are more expensive than COTS.
“The military contractor still has the option of purchasing a high-reliability
military part,” says Shafer. “But in many cases, the products are priced at much
as 10 times higher than the COTS products.” So much for avoiding the $800
toilet seat.
Those
in the components industry insist their RoHS-compliant products are plenty
reliable enough. Certainly that’s true when it comes to consumer products. Your
CD player or Apple iPhone is not likely to malfunction due to tin whiskers. But
your CD player or iPhone won’t face the harsh environment of space, nor will
they have to perform without interruption for 10 years in a Hummer stationed in
the Mid-East.
Defense
and aerospace manufacturers simply don’t trust the tin alloys developed in
recent years to replace tin-lead. While component manufacturers insist the
alloys mitigate the growth of tin whiskers, the defense and aerospace experts
are skeptical. They want years upon years of study before they’ll trust a
lead-free component. After all, they had more than 100 years of history with
lead.
Visit SourceESB.com for all your sourcing needs.
We would like to hear from
you. Please e-mail article feedback or
comments to esbideas@SourceESB.com