Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.

Reflow Power Failure

Hany A. Salam


Reflow Power Failure | 14 November, 1999

In our facility we face a lot of power failures due to the to the city electricity network problems.So, it has hppend many times to loose some PCA's inside the reflow oven. Of course it costs a big money tobuy a UPS for a reflow oven. One suggested to connect a power generator to the oven as a standby powr source.And to avoid the high cost once again he suggested a low power generator just to drive the oven chain to get the asemblies out & later reflow them again.Do we have technical problems if we do this ? keeping in mind assemblies with very expensive components.

Thank you Hany

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Re: Reflow Power Failure | 14 November, 1999

What is your definition of a lot of money for a UPS? You mention very expensive components on your boards. What is their worth comapred to the UPS? A generator hooked to the conveyor would in theory work. but what is the cost of the generator? Who will start it? We are talking melting temperatures in the oven. Leave the parts for a minute or two and you may as well throw them away. The parts and boards are not designed to see high temps for long periods. Check the specs on your most costly components.Even if the parts and boards could take being stuck in the oven for a short period, what about the paste?. You will have cooked the paste. Your best and really only viable process control comes from a UPS for the oven. It only has to be big enough however to keep the conveyor running. Ray

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Brian W.


Re: Reflow Power Failure | 15 November, 1999

I think the issue may be more than just the oven. I worked at a facility in Florida, where lightning strikes were common. We installed backup generators for the facility. Among the issues and costs we analyzed were: frequency of outages, boards in reflow ovens, SMT equipment down time, labor impacts of overtime to catch up for lost time, testing issues (burn-in, etc.), damage to computers, wave solder and hand assembly impacts. We found that due to the frequency of power outages, we were losing a lot more cost than just boards stuck in the reflow oven. Depending on how long the power was out for, it reset the SMT equipment, stopped burn-in testing (which then had to be restarted from the beginning), and cost lots of labor dollars from operators sitting idle, then paying for overtime to make up for the lost production time from the power outage. Then figure out if there are delivery impacts from the lost production time. It was expensive to provide facility backup generators, but it saved a lot more money in the long run.


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Re: Reflow Power Failure | 22 November, 1999

Hany, Chartrain has some good points, if you product is expensive, what does the cost of a UPS amount to? Remember, you don't want to 'back up' the heating zones, just the controller and conveyor drive system so product doesn't get stuck in the oven.

The old fashioned solution; Some years ago, the inexpensive solution offered by some vendors was a hand crank which fit on the end of the conveyor drive roller shaft, if you lost power, put the crank on the machine and empty the conveyor. I figured we wouldn't know were we put the crank by the time we had a power outage. But it is simple and would work.


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Fluid Dispensing Aerospace

Reflow Oven