Alexandre Guimarces wrote:

>     Please be carefull when opening the oven door or putting a fan to cool
> the boards faster ! Be very carefull.... All the manufacturers
> specifications call for a maximun temperature gradient also on the colling
> ramp and opening the oven door above 70 dg celsius will stress the
> components ! That is specially true for SMD multilayer capacitors, they will
> make micro-cracks with big temperature changes.


Alexandre is correct, I apologise for suggesting
that just opening the door after soldering is a
good way to do it. In reality our needs were quite
different, ie only soldering a few SMD chips and
no other components, and it wasn't "instantly"
opening the door as it may have sounded. I posted
that system in reply to someone who suggested it
was difficult to do SMD in a cheap oven, and the
main point I was trying to make was that it's not
really difficult and no expensive controllers
are needed.

At the time we were using this simple stopwatch
method I tested the system time over temperature
and the different phases, ie oven preheat, on full,
turn off, and door open, gave temperature in
each phase that was close enough to the proper
times and temperature ramps that it worked quite
ok.

If we had to solder the small parts (or larger
areas of the PCB than just 1.5 square inches)
I would go with the proper temp controller system
as Alexandre has suggested. :o)
-Roman

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