>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
>[log in to unmask]
>


John,
        I'll suggest another alternative.  Motivating the operators to set
up the scrubber correctly.  I would suggest that only few people are tasked
with this cleaning operation.  Now the fun part.  Provide the operator with
an air driven brush, a rubbermaid plastic mat, a sink area, and a bucket of
pumice.  "Shut down" the mechanical brush process, due to the cleaning
problems on thick panels.  Have the operator pumice scrub ALL the boards
for a week.  Work dilligently trying to figure out the problem.  Ask for
the operators input.  Help him to understand that if you can't fix the
brush machine, pumice scrubbing might become the only method of cleaning
boards.

Now if the operator is still not motivated to help get the machine fixed,
then it is time to push the operator through the brush, leaving it set up
for .062 material.  At least he or she would know how it feels.

This worked for me once when I really did not know what the problem was.
(Not the part about pushing the operator through the machine.) The foreman
took me aside and praised me for my people engineering skills.  We both
laughed, and I dried off a little more of the water from behind my wet
ears.  Ah, Youth!


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                           George Franck
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