Roger,
     OMIKRON is a Tin Immersion process that does currently contain thiourea.
On the positive side, it replaces a process (HAL) that currently contains
lead.  Recently many shops have switched to using Tin as an etch resist in an
effort to remove the lead from their shops, leaving the Hot Air Leveler as the
last lead source left.
     As far as discharge goes, there are many options.  The OMIKRON bath life
is indefinite and should not have to be dumped.  One simple way to keep your
rinse water clean and prevent unnecessary loss of chemistry due to drag out is
to install a fog mister to rinse boards over the process tank.  The OMIKRON
bath is a heated bath and will need to have the evaporated water replaced
anyway.
     To further answer your question regarding preferred methods of treatment,
Thiourea is not on the Federal EPA list of TTO's, in the State of California
it is not a regulated hazardous waste substance, and I know of no POTW's that
place limitations on the amount of thiourea being discharged.  I hope this
information is of some help to you, if you have any other questions or
concerns please feel free to contact me.




Stephen M. Wentz

Florida CirTech Inc.

VM# 408-233-0443

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