In a message dated 7/10/98 10:54:27 AM Pacific Daylight Time,
[log in to unmask] writes:
> Hi techies,
> We just purchased a new oven (Heller 1900w) it is 12 zones. We are not
> using the first two zones only using 10. The machine set up is
> 80,100,110,120,140,150,170,175,230,265 and conveyor at 65. The profile
> looks good, peak temp at 220, max rise at 2/sec total time above is
> between 50 and 60 sec. My problem is when the board exit the oven they
> are very hot! I mean these things are flexing, is this normal for a 12
> zone reflow oven or are we doing something wrong?
Hi Angie,
I have a Heller 1500 and I think basically they're the same oven except
you have a few more zones than I do. Your profile doesn't seem all that hot,
and your belt speed is right around 25.5 inches per minute which is not
unusual...hmmmmm, is the board real dense with a lot of mass? Like a mess of
DRAM's or PLCC's packed together?
What could be happening if that's the case is that the assembly is
retaining the heat longer because of the themal mass. You should lower the
temperatures and slow the belt speed down a little if that's the case. If
that's not the case, I'm gonna ask what may be a dumb question, but do you
have your cooling fans on? I'm not absolutely sure about your model oven, but
with mine you enable your cooling fans by the fan reostat knob that's beneath
the keyboard on the side of the oven...it's difficult to see unless you bend
over and look underneath the keyboard. Heller doesn't enable the cooling fans
in the profile software like say Conceptronic does, you gotta' physically turn
the fans on....
-Steve Gregory-
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