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One Level Metallurgy Bridging Process for Gas Panels

IP.com Disclosure Number: IPCOM000084549D
Original Publication Date: 1975-Nov-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 3 page(s) / 57K

Publishing Venue

IBM

Related People

Hammer, R: AUTHOR

Abstract

In fabricating gas panels, parallel conductors are provided on two glass plates orthogonally oriented. For applications of gas panels which do not require complete-random-access input capability, shift register techniques are utilized.

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One Level Metallurgy Bridging Process for Gas Panels

In fabricating gas panels, parallel conductors are provided on two glass plates orthogonally oriented. For applications of gas panels which do not require complete-random-access input capability, shift register techniques are utilized.

Gas panels operated in a 3-phase shift method require 3 sets of parallel conductors connected in common to bus conductors, forming a comb-like pattern. These patterns pose a problem in that a bus conductor for one phase must cross over lines of one of the other phases. A portion of such a pattern is shown in Fig. 1 with the points where the 02 bus conductor crosses over 03 lines indicated.

Various techniques are possible for delineation of gas panel metallurgy. Photolithographic techniques currently used involve a number of costly and time- consuming steps. An alternative technique involves deposition of the metallization pattern directly, through masks. Regardless of the metallization technique used however, for shift-logic type (SLT) gas panels, provision must be made to obtain bridging.

In SLT microelectronic packaging, bridging is typically obtained by depositing an insulator over the metallurgy to be bridged, followed by deposition of a 2nd level of metallurgy. Aside from adding processing steps, such a technique in gas panel fabrication would pose severe mask alignment problems due to the dimensions involved (line width and spacing).

In the method described below only one level of metallization is needed, and the additional masking and processing steps normally employed to obtain bridging, i.e., deposition of dielectric and 2nd level metallization, are eliminated. This is accomplished by placing only the vertical metallurgy of the comb pattern on one plate (bottom plate) and all horizontal metallurgy on the other plate, including bus conductors used for common connections to the vertical lines of the bottom plate. Contact between the vertical lines and the horizontal bus conductors is obtained at appropriately placed contact pads, by a reflow technique similar to that used for "Reflow Chip Joining" in SLT module fabrication
*. Bridging is obtained by virtue of the gap, maintained by 2-4 mil spacer rods, between plates.

Shown in Fig. 2, is one possible configuration for the bottom plate metallurgy with large contact pads provided for subsequent joining to the horizontal bus conductors. An additional benefit realized from this scheme can be seen by compari...