Address,

We are currently using a Chemical Clean line to prep inner layers
for lamination resist.  For the most part, the chemicals are being 
maintained and the only operator variable is the conveyor speed.
We have had good success with this process.  

For external images we are using a mechanical scrub (Sommer&Maca)
prior to external image.  Unlike the chemical clean line, most 
of our operators are not insuring the brushes make a light to 
medium contact to the copper surface.  What usually happens is a
63mil panel is scrubbed and behind it follows a 125mil panel.  The
brush distance is not compensated for the increase in panel thickness
which in turn removes needed copper and deep copper valleys.  It
has been a difficult task in monitering operators.


Q.  Is there an alternative to mechnical scrubbing for external 
    layers?

NOTE:  We will continue using the mechanical scrub for deburr.

Q.  Are other PCB shops using Chemical Clean lines for external
    layers?  And is so, does your resist hold up in the 
    Electrolytic bath, Nickel bath and Gold bath.  No resist 
    breakdown.

Q.  Do other PCB shops experience resist breakdown that is result
    of improper mechanical scrub.  In this case, deep copper 
    scratches that interrupt the image and polymerization process.

Please advise.  Thank you.

John Gulley
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