In a message dated 07/06/2000 12:50:07 PM Central Daylight Time,
[log in to unmask] writes:
<< We have recently received a few memory assemblies from an off-shore vendor
that exhibit a copper or bronze hue to the terminations of the bypass caps.
There are only 2 caps on the assembly, and they both show this anomaly. Very
light scraping exposes good looking terminations just under the surface of
the discoloration. All other terminations and leadframes look fine (TSOPs,
Resistors, Tantalum), just this one component looks 'funny'. In addition,
the board appears clean (to the eye) under high magnification. This is a new
one on me, what could be the cause of this?
Mike McMonagle
PCBA Process Engineering
Telxon Corporation
(713) 307-2443 Phone
(713) 307-2581 Fax
www.telxon.com
' Innovative Solutions for
Mobile Information and
Wireless Communications' >>
Hi Mike!!
Hmmmm, that sounds kinda' strange...but anything is possible. I can relate
one story to you back when I was working for a memory company in California.
This ain't gonna be pretty, so fasten your seatbelts.
We got an order to build-up 25,000 SIMM's from a overseas customer. Thing
about this deal was they were half-built...one side was already populated and
we were going to put more DRAM on the other side, then route them out of the
panel, test, and ship them. This job was one them phone call rush jobs, no
real planning or anything.
Next thing you know, we've got boxes and boxes of these half stuffed panels
back in receiving. Well they started building them on swing shift (we ran
3-shifts there), I worked day shift. So the next morning when I came in, I
was greeted by; "Hey Steve, the boards we've been building aren't coming
clean very good..." I went and looked, and they had been assembled with a
no-clean flux overseas on one side, while our processes in the states was
water soluble at the time...lovely! Somebody on graveyard shift went out to
the chemical locker and found some saponifier that had been there for a long
time (before we had close-looped our water with a ION exchange system) and
dumped it in the cleaner trying to clean the panels...
Well, of course our resin beds died quickly in a short and painfull death,
now we had no capabilty to wash anything until we got new beds...nobody
understood why I had to go outside and walk around to cool down...
The solder joints looked kind funny on those boards too...don't understand
why though (wink, wink..)
So the moral of the story, haste makes waste, and Mike, like I said, anything
could've happened that would cause the joints on the caps to look funny.
Hopefully not as bad as my story...
-Steve Gregory-
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