We are looking at several reflow ovens with intent to acquire one for both air and nitrogen reflow capability (i.e. have the capability to reflow in either air or nitrogen environment). Would be interested to know what I should look for in comparing the N2 capable ovens.
Do all the ovens feed N2 into the chambers/zones in essentially the same manner? On the outside panel of the ovens, I noticed several flow gauges (4-8) . . . are these the gauges which control the flow rate of N2 into each zone? In several semicon processes, I know that vacuum is created to suck out the mixed oxygen and nitrogen atmosphere (while the nitrogen purge is ongoing) so that over time O2 is in the desired <20ppm range. Is vacuum also the standard process in reflow ovens or is it that nitrogen is continuously purged into the chambers until the desaired O2 atmosphere is achieved; and then we feed the boards? If nitrogen is simply purged, on average how long would it take to reach an atmosphere of <20ppm O2 (I know it would vary by ovens but is it close to the 20 minute mark that we consider "warm-up" time or the 5 minute mark)?
Also, do reflow ovens come equipped with specific gauges or pre-installed analyzers to display a reading of O2 inside the zone?
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