Dear team,

We have problem during dry film stripping, which is the process just before
etching.

During the dry film stripping, two stages of dry film stripping processes
are used and some of the Tin(act as etch resist) seems dissolve a bit at
the bare copper area just after stripping when in contact with stripping
solution of caustic soda and result etching problem.  Especially for fine
spacing of 6-8mil, the incomplete etching problem are more serious and
sometimes re-etch the boards for twice again are required.

Do anyone have any idea to resolve it?  The temperature employed is 40 C
and the conc. of NaOH is 150 g/L.

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