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Flux drop in lead free process

Views: 1899

Harsha

#46116

Flux drop in lead free process | 8 December, 2006

I am seeing a problem of flux droping on the PCBA during reflow. This is a pb free process and I am using KOKI pb free paste with 8 zone (and some 9 zone) reflow ovens. Line throughput is about 10,000 boards/24 hours. I suspect that the exhaust is not powerful enough because I see a lot of black flux residue in the last heating zone and especially the cooling zone. I was just wondering why is it so much in the cooling zone and what else can be done to prevent this (other than adding more exhaust which is very expensive). I would appreciate any explanations suggestions.

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#46145

Flux drop in lead free process | 9 December, 2006

With high volume production, this can happen. The flux is vaporizing in the heating zones, and is condensing in the cooling zones. Depending on the machine, cooling can act differently on different machines. Less cooling may reduce this problem. What kind of oven do you have?

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Harsha

#46180

Flux drop in lead free process | 15 December, 2006

Thanks for the response. I am using mainly two brands of ovens. One is Heller and the other is a chinese brand called Fulongwin (copy of Vitronics). I see the problem in both, more severe in the Fulongwin. Both are 8 zones and a few 9 zone Hellers. I see the problem in both 8 zone and 9 zone.

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RDR

#46189

Flux drop in lead free process | 15 December, 2006

unfortunately you need to increase your maintenance on these ovens, I would doubt if anything is wrong with your equipment. the Flux accumulation is normal, and you are putting alot of flux through those ovens.

Just clean more often

Russ

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greg york

#46226

Flux drop in lead free process | 18 December, 2006

Probably because the flux manufacturers have deemed it necessary to increase flux volume by 20 - 25% compared to Leaded this is why more is being left over. Really not convinced of this increase in volume actually does anything. Black residue will be charred rosin and you will need something like NMP to get it off (N-Methyl-2-Pyrolidone). Hits the cooling zone and chills back to a solid - nice Cheers Greg

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#46278

Flux drop in lead free process | 19 December, 2006

Where are you located. I know a guy that has experience on the Folung oven, and can hook you up with him.

Drop me an E, and I'll reply to that with his contact information.

Bill West bill@ietechnology.net www.ietechnology.net

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