Jeff,
I've worked with 4 brands of convection ovens; Conceptronic, Heller, ABW,
and BTU. Of the four, I think I like BTU the best. Why, you may ask? Well, I'm
not trying to slam any of the other ovens, but the BTU oven seems to be more
efficient as far as it's heat transfer goes... and that may have something to
do with the way they've designed the airflow inside the oven or something. It
also seems to be more accurate as far as the temperature that the board sees
vs. what you've put in as set-point temperature for the zone. I know that
because I've done temperature plots on all 4 ovens using a "Supermole Gold",
and if I've set 150-degrees in a zone on a BTU oven, by george, that's what
I've got on my plot...
With the other ovens, it seems like you first have to get to know it's
"personality" by doing a few plots and see what temperature you actually get
inside the oven from the set-points that you've entered, and then you can
write some decent profiles. With the other ovens, it seems like you need to
enter a temperature around 30-40 degrees or so higher than the temperature you
want to see on the board...maybe it has something to do with where the
different oven makers put the thermocouples that sense the heated air or
something, I'm not quite sure. But with the BTU, if I put 150-degrees in
zone-2, the board will see 150 degrees in zone -2.
I also like BTU's oven control software, you can password every single
level so people can't dink with your profiles, it's got a nice logging system
incorporated in the software, logs all the oven parameters while it's running
if you want it to, and counts the number of boards you've reflowed...or is it
reflown? What's the past tense of reflow? (Oh well, I was never very good at
english...hehehe)
The other ovens are okay, but I will speak for myself and say that I have
had a couple of problems with two of the brands. With Conceptronic, I had a
oven that had a bearing seize on the edge-rail conveyer jackscrew that's
inside the oven...that wasn't good, wound-up having to replace a whole
conveyer rail that got kinda' "tweeked" because of that. But to speak a little
in defense of Conceptronic, they've corrected that problem since then and
spec'd out a new heat resistant bearing for the jackscrews inside the oven.
With a ABW oven, I had this random problem with the oven losing
communication with it's computer for a few seconds. Problem with that was that
anytime the oven lost communication with the computer, it had this default
function that would crank-up the belt to warp speed to clear any PCB's out
from inside so they wouldn't fry, but then everything would go back to normal
all by itself....weird huh? It took me the longest time to figure out what in
the world was going on when the inspector would bring me a board with cold
solder all over the place on a product that we had been building for days
without so much as a pimple on it...that is until I finally seen the oven go
into it's "Christine-mode" as I called it. As far as I know, ABW or the people
where I used to work still don't know what was causing that...
With the Heller ovens the only thing I don't like about them is the
temperature set-point thing I talked about in the beginning...but that's not a
big deal, it's something that you can adjust to very easily if you really want
to...
I hope this is of some use...
-Steve Gregory-
P.S. By the way, I've done no-clean reflow on all four ovens...
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