The First stage
 |
As the etcher density rises and it
calls for fresh material, regenerated etchant
containing approximately 100 G/L copper is added to
the etcher module. Spent material is removed from
the module and stored in a buffer tank for
processing in the Mecer system. Also added as
needed is ammonia for pH control, chlorides to
compensate for drag-out and etchant additive to
control banking and etch speed.
When enough spent etchant has accumulated in the spent buffer tank, the Mecer system automatically turns on and begins to regenerate etchant. Using a process known as solvent extraction or liquid ion exchange, a portion of the copper is transferred out of the etchant into an organic extractant. The regenerated etchant is then sent back to storage for reuse in the etcher. The organic is passed on to the next step in the solvent extraction process. |