George, Werner,
These are unpopulated brds.
YES THERE ARE CPNS ON THE PANEL.(as per IPC-2221)
1) CPNS SHOW more than 0.0015" mini in the via holes (in cpns representing
via holes)
2) However, some assy have failed due to cracked copper.
3) 2 assy were X-sectioned and showed low copper ~ 0.001" in the vias that
cracked. (these are vias in the brd)... we do have pretty good
plating quality....we check tensile elongation every 2 wks and elongation always
runs > 20%.
4) We X-secitoned some scrap brds...via plating was fine.
5) SO WE feel that, some brds may less plating in these via holes even
though the cpns show adequate plating.
6) HENCE WE WANT TO MEASURE COPPER PLATING IN VIA HOLES (IN A BARE BRD)
NON_destructively.
Rush
818-415-0030
In a message dated 10/13/2007 4:55:02 PM Pacific Daylight Time,
[log in to unmask] writes:
I haven't see your product but just knowing the board i
Hi Rush,
I haven't see your product but just knowing the board is a 20-layer 150
mils PCB with a 1.5 mil thick copper requirement for the vias it sounds
like this isn't a cheap assembly. I guess that is the reason you're
looking for a non-destructive measurement. Unfortunately I don't think
you are going to find a non-destructive technique for measuring the
copper thickness in vias on a fully populated PCBA. Werner's comment
about a "classic case" is correct. In fact I would add to his statement
and say that a non-populated PCB retention sample is always a good idea
as is non-destructive measurements on bare PCB's prior to assembly.
Regards,
George
George M. Wenger
Andrew Corporation Wireless Network Solutions
Senior Principal FMA / Reliability Engineer
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 [Office] (732) 309-8964 [Cell]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /*
Sent: Saturday, October 13, 2007 7:30 PM
To: [log in to unmask]
Subject: Re: [TN] SV: [TN] URGENT HELP NEEDED:- non-destructive method
for via hole plating thickness
Hi Rush,
Here is a classic case as to why it is imperative to have coupons as
part of
the panel.
you state:
20 layers, ~150 mils thick
Via holes are 20-22 mils finished; Required plating is 0.0015 min.
Also, for via holes, the finished hole size is totally unimportant-you
need
to know the drilled hole size.
Is the required plating thickness 1.5 mils minimum? or measures how?
You also do not say whether you have problems, and what the problems
are.
Werner
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