Clean Stripping of Dry Film Photoresists on Non-Copper Surfaces
Dry film photoresists have been used in photochemical
machining since their advent for printed circuit boards in the
1960's. Although the metallic surfaces in photochemical machining are
typically not copper as in circuit boards, the issues
of good dry film adhesion through development and etching,
combined with clean stripping are nevertheless the
same. Cosmetic considerations make thin resist residues or a
colored stain of the metal surface particularly objectionable.
The objective of this study was to compare the stripping characteristics
of four different dry film resists with regard to residual color stains on a variety of metals typically used in chemical milling by testing common stripping chemistries
and judging stain residues visually and by different spectroscopic techniques.
Karl H. Dietz and Anne-Marie Coffin, DuPont Electronics