June 2006
Practical Etch Improvements
As photo chemical machined (PCM) parts become
smaller and more complex, the need to properly maintain
the etching machines become more critical. Along
with solution chemical controls, the physical considerations
of etch directionality and solution puddling on
the top side of the work piece become more critical. On
a horizontal conveyorized system etch directionality is
when etched lines perpendicular to the conveyor direction
etch at a different rate than etched lines that are
parallel to the conveyor direction due to the dynamics
of the forward conveyor direction. Puddling is the effect
of etch solution accumulating on the surface of the
work piece. In order to etch the top surface of the panel
the solution puddle must be moved by the pressure of
the spray nozzle thus replenishing fresh etchant to the
metal surface. As this puddle increases in volume or
becomes difficult to push over the sides of the panel due
to the panel area, etched lines at the edge of the panel
are etched more than etched lines under the middle of
the puddle.
Ken Bridges, CTO, Kenchi International Ltd
