[PCB_FORUM] Re: First Article Inspection

Dennis,

            I assume that you are saying that the boards are fabricated at a
subcontractor, and you want to do an incoming inspection before placing
components onto the boards?  If so, the board should already have been
tested to make sure it complies with the fab drawing by the fab house.

 

            If that is the case I think your process should involve just a
couple of steps:

            1.  Make sure that your fab drawing calls out everything that
you care about, including 100% electrical test, any impedance requirements,
and compliance to various industry/government specs.

            2.  When the boards arrive, inspect the inspection reports.
Make sure that it looks like the testing was actually done.  I.e. the
impedance of controlled impedance traces should vary slightly from board to
board, it shouldn't just say "50ohms" straight down the report.  The
measured dimensions of the board have the same issue.  The tolerance is
probably +/-10 mils, if the report says that everything is perfect, they
probably didn't actually measure it.

            3.  Pick a couple tests and spot check them:

                        a.  do a visual inspection looking for soldermask
issues

                        b.  do a visual inspection looking for drill
breakout issues

                        c.  get a Multimeter and check impedance between the
various plane layers.

 

            My experience is that fab issues come in two flavors:
cosmetic/outside layer stuff, and buried electrical stuff.  You can't find
the buried electrical stuff on the bare fab unless you check every net, but
you already paid the fab house to do that for you.  And the cosmetic outside
stuff should be easy to spot if you look.

 

Tom
Arira Design, Inc.
408-844-8433 x112 

 

  _____  

From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Carrow, Dennis
Sent: Wednesday, January 25, 2006 8:25 AM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] First Article Inspection

 

Hello Everyone,

            I'm at a new company that does its own manufacturing but it
appears they don't have an inspection group doing a first article inspection
on bare boards.  I know it should be done but I don't know what to tell them
to inspect.  The other PWB guy here wants to tell them to inspect to IPC
A-600F but that doesn't tell them what I think they need to know.  Is there
any information out there that can help me document what they need to look
for?  Thanks for any advice!

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