Study of Thick Film Thermal Head Structure

Abstract

The protective layer for a thick--film thermal printhead is formed usually by the conventional screen-printing method. The curvature of the protection layer is dependent on the formation of the heater nib. If the cross-sectional structure of a heater nib is thin or wide, the curvature of the protection layer is large. Though the platen pressure becomes small, the printing characteristics is uneven due to larger contact area. On the other hand, if the crosssectional structure of a heater nib is thick or narrow, the curvature of the protection layer is small. The contact pressure with media is large and may generate sticking, and intense wear result. A new approach of protective layer formation by means of a direct dispensing system to realize a convex cross-sectional structure with a desirable curvature is studied. It possesses the following advantages over the conventional screen-printing method: (1) Forms of various curvatures can be studied, independent of the form of a heater nib structure. This is critical in manufacturing a high-resolution printhead where the heater nib is usually very thin, and high reliability and long life expectancy are desirable. (2) Reduction in manufacturing cost since screen masks are not required and the waste paste used in screen-printing is saved.