Precise window mask prodn. in bimetal foil - by etching each layer with different selective etchant to give mechanical support at edge of window

摘要

In the prodn of precise window masks from bimetal foil, the pattern is etched in the thick carrier foil with the first etchant (I) as troughs enlarged by under etching, which extend only partly to the front layer. Then the precise window pattern is etched in the thin front layer with another etchant (II), only slight under etching taking place. Finally, the thick carrier foil is etched through from both sides with (I) so close to the upper layer that the edges of the windows in the thin upper layer are still just supported by the robust carrier foil and thus mechanically protected. The masks are useful in the prodn of electronic circuits, e.g. thin film transistor matrices, by vacuum evapn. They are more robust than usual, allow finer patterns to be etched and are made with thinner Au layer.