Hi Rich,

You can make a calculation if you know the ppm levels for the process
and the number of defect opportunities per board. But then there are
still many factors to consider like complexity of the the board,
batchsizes, components quality, whether DFM rules were applied, and
more.
Anyway 99% without any electrical testing seems excessively high for a
2000 parts boards.
Am I still in time for your meeting ?

Daan Terstegge
Thales Communications
Unclassified mail
Personal Website: http://www.smtinfo.net

>>> [log in to unmask] 02/27/03 03:38pm >>>
Good morning everyone,

I am having a debate with regards to first pass yields and how testing
strategy (ie.. ICT or Functional Test) plays a role.

I am looking for any "factual data" or "industry studies" that have
been
done to show the difference in yields between a batch of assemblies
that are
subjected to only visual inspection and to those batches that receive
visual
inspection and some type of ICT or functional test.  I have my own
internal
data that shows the differences but want to compare that against the
industry.

Summary - I have a customer that is expecting 99% First pass yield
(including board functionality) to their facility but does not utilize
or
want ICT or functional testing done to their products.  Now the old
rule of
thumb that I've gone by for many years is that visual inspection is
approx.
80% accurate and there are bound to be defects that slide through this
visual inspection process.  To consistently achieve yields in the high
90%'s
additional test strategies should be looked into.  Note: The boards in
question range anywhere from 200 components per board to approx. 2000
components per board.

Any feedback or published industry articles documenting the yield
differences between visual inspections only and using ICT/Functional
testing
would be very helpful!

P.S. I have a meeting at 1:30pm today (Central Time) so any feedback
before
then would definitely be appreciated.

Thanks,

Rich Lasko
Badger Electronics



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