Are you saying that nothing has changed but now your oven cannot maintain 
the 150 C temp now but did before?  Sounds more like something has changed.

What is the temperature of the last heated zone before your 150 
zone......there is such a thing as over spillage between zones.  Depending 
on the model and make, there is a certain maximum delta between zones that 
the ovens can control.

The answer to your question will come from your thermocouple data, as has 
already been mentioned above.....maintain the -3 C/sec minimum and you 
should be fine, the 150 is not the requirement.

Phil



At 10:17 AM 12/5/2007 -0500, Leland Woodall wrote:
>Good morning, everyone!
>
>Lately we've had a slight issue with one of our reflow ovens.  We have
>set our temp parameter for the last zone at 150 degrees C.  When we
>first received this oven we had no problem with maintaining this zone as
>prescribed.
>
>I assume we have an insulation barrier that's breaking down and causing
>this situation.
>
>Anyway, how critical is this cooling zone?  If the oven is no longer
>able to maintain the current setpoint, would it harm anything for this
>zone to move up in the 160 to 170 degree range?
>
>We're running a pb-free process here, just in case it makes any
>difference...
>
>Thanks in advance for your help.
>
>Leland Woodall
>
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