Board designers ID library troubles
By Richard Goering
EE Times
(10/18/99, 11:11 a.m. EDT)
MARLBORO, Mass. - The schematic, footprint and simulation
model
libraries that underlie pc-board CAD systems have become
a minefield for
EDA vendors and users alike, according to participants at
last week's PCB
Design Conference East. At two panels, participants
blasted component
vendors for providing inaccurate information, not
conforming to standards
and generally disregarding the needs of designers.
"Total chaos" was the way Randy Allen, vice president for
customer
service at Valor Computerized Systems, described the
library situation at
one PCB East panel. Allen spoke of his company's
experience in building a
commercialized component database.
"It was surprising how disorganized the information is,"
Allen said. "There's
a lack of standards. Component manufacturers are really
not serving their
customers very well, or providing libraries that make
sense."
The library situation is "a bit of a zoo," said Dieter
Bergman, director of
technology transfer and implementation at the Institute
for Interconnecting
and Packaging Electronic Circuits (IPC). There are
component data
standards, he noted - some of which were established by
the IPC - but
that doesn't mean they're being accurately followed.
"There's no guarantee that when you buy a component from
a supplier that
claims to meet a standard, that it will match your
perception of what that
component is going to be," he said.
Moreover, some of the standards are just plain wrong.
Bergman showed
how the calculations underlying one set of EIA standard
dimensions could
cause two electrodes to short out. "We blindly accept
what the standards
say, but nobody checks the math," he said.
Matt Bromley, principal applications engineer for
consulting at Cadence
Design Services, said there's an acute need to get
parametric information
with library parts. However, he said, a lot of that
information is company
specific. The Electronic Component Information Exchange
(ECIX)
standard, now under development by the Silicon
Integration Initiative, should
help, he said.
Audience members at the PCB East panel didn't hold back.
"Those damned
manufacturers are sleazy as heck," said one. He spoke of
the "nightmare"
that resulted when one supplier moved fabrication to
Taiwan, and the
footprints in the library no longer matched the
components.
"We buy a service that updates part status," said another
audience member.
"But sometimes the footprint registration on the new part
doesn't match."
The solution to some of these problems may lie in the
Internet, according to
both Bromley and Allen. Bromley said the XML format will
allow
manufacturers to include parametric data that describes
components, and
that users will be able to read this information into
their own databases.
Component libraries were also a hot topic at the EDA
face-to-face
roundtable at PCB East. "It's a huge issue," said Jack
Woida, director of the
library products group for Mentor Graphics.
Woida noted that a run-of-the-mill pc-board with one
hundred 20-pin
components will still involve thousands of individual
properties, since there
may be 20 properties per pin. Yet if even one property is
incorrect, it could
cause an error and possibly even require respinning the
board.
But now, Woida noted, some components have hundreds of
pins. "Entering
data by hand, by a librarian, is almost impossible with
the new high pin
counts," he said. "The only solution is automation.
"Mentor Graphics has the tools, but we still need the
source data in
parametric form," Woida said. "It hasn't been available,
but the ECIX
committee is working on it."
"I believe Web access to library data is the way to go,"
said Charles Pfeil,
product architect at VeriBest. "But you still have to
certify the data, and
make sure it's correct. Library integrity is a serious
problem in companies."
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