Steve, hello,
First of all - you are absolutely right. In case of process indicator I
send a photograph rather than product. Apart of the IMC issue, unneeded
rework will affect the PCB reliability - pads lifting, vias cracking and
other goodies. Tell your inspectors on my behalf - extra rework equals
damage.
Secondly - if I remember correctly - this is a long debate: didn't you
write about it some months ago?
Regards
Ofer Cohen
Manager - Quality, Reliability and Production Technologies
Seabridge - a Siemens company
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Tuesday, November 02, 2004 03:02
To: [log in to unmask]
Subject: [TN] Process Indicators...
Hi All!!
I've been getting into a number of debates about "Process Indicators" as
described in the IPC-610...mostly with our inspectors. I know their
hearts are
in the right place, but it seems that many times they will reject the
assemblies with "Process Indicators" back to our operators to touch them
up, so that
they look more like the "Target Condition", to be more cosmetically
pleasing.
I've tried to explain things as best I can, but find that sometimes our
operators are touching up way more solder joints than they need
too...they're
being "trained", as it were, by our inspectors. The operators know that
if
something isn't "pretty" enough, it's going to come back to them...so
they're
putting more labor into product than they should.
I'm trying to find some way, any way, to be able to show our inspectors
that
to touch-up something because it doesn't look like the target condition,
doesn't mean one is making things any better...I understand that beauty
is in
the eye of beholder.
There was some talk in the past about the Intermetallic Layer being
thickened during subsequent reflow cycles, and causing fractures, but
Werner said
that he's never seen a failure because of a thick Intermetallic layer.
Process Indicators may happen as spelled out in the -610, sometimes not
only
because of the assembly process, but because of the design, or other
factors.
I look at Process Indicators as a "Flag" to investigate whether or not
the
issues can be addressed and resolved properly, if they can't be
resolved, then
it's not a defect. Am I wrong about this?
As always, TIA!
-Steve Gregory-
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