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High Resolution Matrix Print Element Structure and Method For Manufacturing The Structure

IP.com Disclosure Number: IPCOM000048752D
Original Publication Date: 1982-Mar-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 3 page(s) / 72K

Publishing Venue

IBM

Related People

Powell, DO: AUTHOR [+2]

Abstract

The reduced energy levels required by the write electrodes of certain electrolytic printers has led to a search for the best methods of implementing an integrated print head that can take full advantage of this energy reduction while still achieving relatively high print density. A matrix printer which is to have 240 printing elements per inch resolution (pel) requires a print element geometry similar to that shown in Fig. 1.

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High Resolution Matrix Print Element Structure and Method For Manufacturing The Structure

The reduced energy levels required by the write electrodes of certain electrolytic printers has led to a search for the best methods of implementing an integrated print head that can take full advantage of this energy reduction while still achieving relatively high print density. A matrix printer which is to have 240 printing elements per inch resolution (pel) requires a print element geometry similar to that shown in Fig. 1.

Each of the conductive print elements or styli 10 must be connected by a conductive line to a driver and/or decoding logic circuitry therefore which is contained in an integrated chip. The styli must be electrically isolated from each other as well as from the conductive reference plane. This isolation is accomplished using rings of dielectric material. The thickness of the rings is limited by the voltage and current requirements for printing and their compatibility with LSI or VLSI (very large-scale integration) chip technology.

Ruthenium dioxide (RuO(2)), either alone or dispersed in a glass matrix, has been selected as a covering surface conductor material for the styli and reference plane because of its excellent wear resistance and chemical inertness. Electrical connection from the driver chips to the styli and reference plane requires a two-level metallurgy structure to provide crossovers. Vias or thru- holes must be provided in the dielectric separating the metal layers to allow interconnection between the layers. Fig. 1 is a top view showing the print styli detail, Fig. 2 shows a cross-sectional view A-A of the print element structure, Fig. 3 illustrates a detail of the first level metallurgy in the print element area, and Fig. 4 depicts the detail of the interlevel via or thru-hole pattern.

The first layer of metallurgy would be made using processes similar to those used in metallized ceramic (MC) technology and provide the conductor patterns for external I/O and power to the decoder/driver chips, as well as connection to the print element styli and reference plane. The standard chrome-copper- chrome MC metallurgy could be used, or the top and bottom Chrome layers could be eliminated or replaced with other suitable metals that would improve adhesion to the substrate or photoresist. The first level conductor lines are then covered with a photoresist 0.5 to 3.0 mils thick. Either a dry film or liquid resist could be employed. The resist is then exposed through a patterened mask and developed. It is removed wherever a connection from the first to the second metal layer is desired, i.e., print styli, chip or I/O pad sites. Copper is then plated up in the areas where the resist was removed until it is the same thickness as the remaining resist. Plating can be accomplished eith...