Thanks Steve Gregory, william campbell and the rest of you guys
it helps a lot.
God Bless
"Campbell,
William To: Jonathan A Noquil/Cebu/FSC@Fairchild
(wcampbel)" cc:
<wcampbel@har Subject: RE: [TN] Non-Reflow
ris.com>
07/26/01
08:15 PM
Jonathan-
sorry, I reread your message more carefully and saw the pic. However, I
still think your track speed is the crux of the matter, perhaps it's
slightly out of cal on your "problem" oven. Pretty simple to mark a spot
on
the chain, and measure how far it moves after 30 sec.
best of luck. Bill C
-----Original Message-----
From: Campbell, William (wcampbel)
Sent: Wednesday, July 25, 2001 8:38 AM
To: [log in to unmask]
Subject: RE: [TN] Non-Reflow
Your pic didn't come through. I suspect however that you have a lot of
thermal mass (ground plane, etc) and your soak time isn't long enough to
bring it to reflow temp. If you were baking a cake, and the recipie says
20min @ 350F, you can't expect the same tasty result if you cook it for
10min at 700F.
I also don't know what your process is, lead free, etc, but I would try a
more reasonable temp around 250 for your hottest zone, and slowing the
track
speed to increase your soak time.
Good luck, and let me know if you have any other questions.
Bill C
-----Original Message-----
From: Jonathan A Noquil [mailto:[log in to unmask]]
Sent: Wednesday, July 25, 2001 8:07 AM
To: [log in to unmask]
Subject: [TN] Non-Reflow
Hello Friends,
Can anybody explain why there is always a non-reflow
of solder paste as shown by the drawing below?
(Embedded image moved to file: pic07711.pcx)
The solder paste used for assembly was
88Pb10Sn2Ag and it is an Indium No clean paste.
Its liquidus temp was 290 C and solidus temp of 268 C.
Reflow Atmosphere: N2 purge as hot gas and cool gas (shown at the above
drawing)
although we tried to increase the temp to over than 300 C, it is still the
same results.
I tried the paste to other oven with a forming gas blanket, and reflow it
to a peak of 295 C
the results were good (All reflowed).
We had profiled the above oven at 3 points Left edge, Midle and. Right edge
and
temperature difference vs setting was ± 5 degree C on that three points.
Was the non-reflow due to the blanket? O2 ppm level? But why on the left
side only?
Does a localized heating have occured? But the temp profile was okay?
Do you have any insights that you can share?
God Bless You All...
Thanks
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