The boards were manufactured to Class II, Water soluble flux, half the board us split up ground areas, and half 10 mil traces. Don't know about the machine used. If this board was .093 thick, would you prebake as a matter of process control, or is it depending on your customer's requests?
Thank You!
Kathy

Kathy Kuhlow wrote:

> I wonder if the bumper/dirty solder isn't a dross residue from the solder pot.  This is a common issue if the solder pot motors aren't strong enough or the maintenance of the machine doesn't include regular dross removal.  Profile is determined by a lot of factors.  The wave profile is going to depend on the components used, ground/power planes, workmanship class of the end product, flux used, and  wave machine configuration (dual, single wave, chip wave, nitrogen or not, etc.).  Can you supply some more process information?  Prebaking of PCB's that we have performed are (for standard .062" FR4 boards) is typically at 60-70C for 2-4 hours depending on the storage and age of the PCB.
>
> Hope this helps.
> Kathy
>
>
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