Good morning,
My morning has not been so good.  I have a build of PCB's (over 300 boards)
where two inner layers have been swapped.  The board fabricator constructed
the board in the wrong order.  These boards are RF in nature and have
frequencies approaching 2GHz on them.  In many places we put a signal trace
on the inner layer furthest from the component side and then a wide grounded
trace over it on the closer inner layer as shielding.  So not only is there
no longer shielding over many traces, these signals are also about .03"
closer to the component circuitry than they used to be.  Can you contemplate
the nightmare of spurious issues that have been created?  We did not notice
the problem until they were fully populated and almost thru our testing
process and started failing one of the tests miserably.
Needless to say, we will be revising our inspection techniques to try to
catch occurrences like this much sooner.

I was wondering if anyone knows of a way that layer order could be
electrically tested for on a bare board, that we could require our
fabricator to complete?

Genny Gibbard (mailto:[log in to unmask])

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------