I've seen that from wave before. I always thought it was just a heat discolored by product from a really hot solder pot. The wave I saw this from had a weak pump motor. I haven't seen any functional failures caused by these joints and they meet all of the acceptance criteria. We let it go, quite giving away the farm.....
Kathy
>>> [log in to unmask] 02/26/01 08:30PM >>>
Hi ya'll!!
It's picture time again. Just to let ya'll know, Driveway is discontinuing
the free storage, sharing service that it once had, service will stop March
5th (that's what I've been using in the past).
They offer to do the same service at another place: www.freedrive.com...the
only problem is that for anyone to view a file that someone has, you have to
sign-up as a user...maybe not a big deal, but I like to post a URL and let
everyone see something without the sign-up hassles. So I found another
free-drive place:
http://www.xdrive.com
You have 25-megs of space for free...
So, go to: http://www.xdrive.com/share/983237599927EkdOzD4nV39P1mRq3zXk
and look at this picture, it's called bluesolder.jpg. It is of a solder joint
that our inspectors are calling "blue solder"...(in fact they have a PQI code
for it, acronyms again, Process Quality Indicator) it does have a light
"bluish" tint to it. What may appear in the photo as some sort of residue,
doesn't seem to be, it doesn't clean off at all. I've tried taking an acid
brush with alcohol and scrubbing the surface...it doesn't touch it, it's like
it's something in the surface of the solder joint. I've done a omegameter
check, and nothing comes up as being ionic...
The board was wave soldered with a RMA flux, and cleaned with Kyzen Aquanox
and deionized water at the recommended concentrations. From what I've
gathered from people that have been here a lot longer than I have, they have
seen this before...but nobody knows what causes it...in they past they have
touched-up every single joint to get rid of this appearance, which to me is
kinda' ridiculous. We waved three boards, and two of them have this
condition, and one doesn't. They were all waved at the same time...
The large grain structure that you may notice in the photo is because (I
think) of the long cool-down time this assembly takes after wave...all the
parts are ceramic, and there's some heavy metal planes in this board. It goes
without saying that the wave profile I have to use to get good topside
fillets is pretty hot compared to other boards (it's polyimide, so the fab
can take the heat)...could that be something that is causing this appearance?
But why two boards, and not all three?
I have good wetting, and all other visual appearances look fine...it's just
this "Blue Looking Solder"...any ideas? BTW, our customers source inspector
accepted the boards, even after pointing this appearance out to her, but our
QA wants it to look better when we ship it....YAAAAAAA!
Thanks!!
-Steve Gregory-
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